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  • 1
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    Seasonal variations in the circulation over the Middle Atlantic Bight continental shelf (2010)
    American Meteorological Society
    Details
    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2008. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 38 (2008): 1486–1500, doi:10.1175/2007JPO3767.1.
    Beschreibung: Fits of an annual harmonic to depth-average along-shelf current time series longer than 200 days from 27 sites over the Middle Atlantic Bight (MAB) continental shelf have amplitudes of a few centimeters per second. These seasonal variations are forced by seasonal variations in the wind stress and the cross-shelf density gradient. The component of wind stress that drives the along-shelf flow over most of the MAB mid- and outer shelf is oriented northeast–southwest, perpendicular to the major axis of the seasonal variation in the wind stress. Consequently, there is not a significant seasonal variation in the wind-driven along-shelf flow, except over the southern MAB shelf and the inner shelf of New England where the wind stress components forcing the along-shelf flow are north–south and east–west, respectively. The seasonal variation in the residual along-shelf flow, after removing the wind-driven component, has an amplitude of a few centimeters per second with maximum southwestward flow in spring onshore of the 60-m isobath and autumn offshore of the 60-m isobath. The spring maximum onshore of the 60-m isobath is consistent with the maximum river discharges in spring enhancing cross-shelf salinity gradients. The autumn maximum offshore of the 60-m isobath and a steady phase increase with water depth offshore of Cape Cod are both consistent with the seasonal variation in the cross-shelf temperature gradient associated with the development and destruction of a near-bottom pool of cold water over the mid and outer shelf (“cold pool”) due to seasonal variations in surface heat flux and wind stress.
    Beschreibung: This research was funded by the Ocean Sciences Division of the National Science Foundation under Grants OCE-820773, OCE-841292, and OCE- 848961.
    Schlagwort(e): Seasonal variability ; Ocean circulation ; Continental shelf ; Wind stress ; Density currents
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  • 2
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    North Pacific decadal variability in the Community Climate System Model version 2 (2010)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 20 (2007): 2416-2433, doi:10.1175/JCLI4103.1.
    Beschreibung: North Pacific decadal oceanic and atmospheric variability is examined from a 650-yr control integration of the Community Climate System Model version 2. The dominant pattern of winter sea surface temperature (SST) variability is similar to the observed “Pacific decadal oscillation,” with maximum amplitude along the Kuroshio Extension. SST anomalies in this region exhibit significant spectral peaks at approximately 16 and 40 yr. Lateral geostrophic heat flux divergence, caused by a meridional shift of the Kuroshio Extension forced by basin-scale wind stress curl anomalies 3–5 yr earlier, is responsible for the decadal SST variability; local surface heat flux and Ekman heat flux divergence act as a damping and positive feedback, respectively. A simple linear Rossby wave model is invoked to explicitly demonstrate the link between the wind stress curl forcing and decadal variability in the Kuroshio Extension. The Rossby wave model not only successfully reproduces the two decadal spectral peaks, but also illustrates that only the low-frequency (〉10-yr period) portion of the approximately white noise wind stress curl forcing is relevant. This model also demonstrates that the weak and insignificant decadal spectral peaks in the wind stress curl forcing are necessary for producing the corresponding strong and significant oceanic peaks in the Kuroshio Extension. The wind stress curl response to decadal SST anomalies in the Kuroshio Extension is similar in structure but opposite in sign and somewhat weaker than the wind stress curl forcing pattern. These results suggest that the simulated North Pacific decadal variability owes its existence to two-way ocean–atmosphere coupling.
    Beschreibung: The first author gratefully acknowledges financial support from NOAA’s Office of Global Programs (grant to C. Deser) and the CCSM Project Office.
    Schlagwort(e): Decadal variability ; Fluxes ; Rossby waves ; Wind stress ; Coupled models
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  • 3
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    Midlatitude wind stress–sea surface temperature coupling in the vicinity of oceanic fronts (2010)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 20 (2007): 3785–3801, doi:10.1175/JCLI4234.1
    Beschreibung: The influences of strong gradients in sea surface temperature on near-surface cross-front winds are explored in a series of idealized numerical modeling experiments. The atmospheric model is the Naval Research Laboratory Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS) model, which is fully coupled to the Regional Ocean Modeling System (ROMS) ocean model. A series of idealized, two-dimensional model calculations is carried out in which the wind blows from the warm-to-cold side or the cold-to-warm side of an initially prescribed ocean front. The evolution of the near-surface winds, boundary layer, and thermal structure is described, and the balances in the momentum equation are diagnosed. The changes in surface winds across the front are consistent with previous models and observations, showing a strong positive correlation with the sea surface temperature and boundary layer thickness. The coupling arises mainly as a result of changes in the flux Richardson number across the front, and the strength of the coupling coefficient grows quadratically with the strength of the cross-front geostrophic wind. The acceleration of the winds over warm water results primarily from the rapid change in turbulent mixing and the resulting unbalanced Coriolis force in the vicinity of the front. Much of the loss/gain of momentum perpendicular to the front in the upper and lower boundary layer results from acceleration/deceleration of the flow parallel to the front via the Coriolis term. This mechanism is different from the previously suggested processes of downward mixing of momentum and adjustment to the horizontal pressure gradient, and is active for flows off the equator with sufficiently strong winds. Although the main focus of this work is on the midlatitude, strong wind regime, calculations at low latitudes and with weak winds show that the pressure gradient and turbulent mixing terms dominate the cross-front momentum budget, consistent with previous work.
    Beschreibung: This work was supported by the Office of Naval Research Grant N00014-05-1-0300.
    Schlagwort(e): Fronts ; Sea surface temperature ; Wind stress ; Coupled models ; Boundary layer
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  • 4
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    Can paleoceanographic tracers constrain meridional circulation rates? (2010)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 37 (2007): 394-407, doi:10.1175/jpo3018.1.
    Beschreibung: The ability of paleoceanographic tracers to constrain rates of transport is examined using an inverse method to combine idealized observations with a geostrophic model. Considered are the spatial distribution, accuracy, and types of tracers required to constrain changes in meridional transport within an idealized single-hemisphere basin. Measurements of density and radioactive tracers each act to constrain rates of transport. Conservative tracers, while not of themselves able to inform regarding rates of transport, improve constraints when coupled with density or radioactive observations. It is found that the tracer data would require an accuracy one order of magnitude better than is presently available for paleo-observations to conclusively rule out factor-of-2 changes in meridional transport, even when assumed available over the entire model domain. When data are available only at the margins and bottom of the model, radiocarbon is unable to constrain transport while density remains effective only when a reference velocity level is assumed. The difficulty in constraining the circulation in this idealized model indicates that placing firm bounds on past meridional transport rates will prove challenging.
    Beschreibung: The first author is supported by the NOAA Postdoctoral Program in Climate and Global Change and GG by the National Ocean Partnership Program (ECCO). Author OM acknowledges support from the National Science Foundation.
    Schlagwort(e): Tracers ; Transport ; Paleoclimatology ; Ocean models
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  • 5
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    Shelf circulation and cross-shelf transport out of a bay driven by eddies from an open-ocean current. Part I : interaction between a barotropic vortex and a steplike topography (2011)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2011. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 41 (2011): 889–910, doi:10.1175/2010JPO4496.1.
    Beschreibung: This paper examines interaction between a barotropic point vortex and a steplike topography with a bay-shaped shelf. The interaction is governed by two mechanisms: propagation of topographic Rossby waves and advection by the forcing vortex. Topographic waves are supported by the potential vorticity (PV) jump across the topography and propagate along the step only in one direction, having higher PV on the right. Near one side boundary of the bay, which is in the wave propagation direction and has a narrow shelf, waves are blocked by the boundary, inducing strong out-of-bay transport in the form of detached crests. The wave–boundary interaction as well as out-of-bay transport is strengthened as the minimum shelf width is decreased. The two control mechanisms are related differently in anticyclone- and cyclone-induced interactions. In anticyclone-induced interactions, the PV front deformations are moved in opposite directions by the point vortex and topographic waves; a topographic cyclone forms out of the balance between the two opposing mechanisms and is advected by the forcing vortex into the deep ocean. In cyclone-induced interactions, the PV front deformations are moved in the same direction by the two mechanisms; a topographic cyclone forms out of the wave–boundary interaction but is confined to the coast. Therefore, anticyclonic vortices are more capable of driving water off the topography. The anticyclone-induced transport is enhanced for smaller vortex–step distance or smaller topography when the vortex advection is relatively strong compared to the wave propagation mechanism.
    Beschreibung: Y. Zhang acknowledges the support of theMIT-WHOI Joint Programin Physical Oceanography, NSF OCE-9901654 and OCE-0451086. J. Pedlosky acknowledges the support of NSF OCE- 9901654 and OCE-0451086.
    Schlagwort(e): Transport ; Eddies ; Barotropic flow ; Topographic effects ; Vortices ; Currents ; Potential vorticity ; Rossby waves
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  • 6
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    On the role of eddies and surface forcing in the heat transport and overturning circulation in marginal seas (2011)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2011. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 24 (2011): 4844–4858, doi:10.1175/2011JCLI4130.1.
    Beschreibung: The factors that determine the heat transport and overturning circulation in marginal seas subject to wind forcing and heat loss to the atmosphere are explored using a combination of a high-resolution ocean circulation model and a simple conceptual model. The study is motivated by the exchange between the subpolar North Atlantic Ocean and the Nordic Seas, a region that is of central importance to the oceanic thermohaline circulation. It is shown that mesoscale eddies formed in the marginal sea play a major role in determining the mean meridional heat transport and meridional overturning circulation across the sill. The balance between the oceanic eddy heat flux and atmospheric cooling, as characterized by a nondimensional number, is shown to be the primary factor in determining the properties of the exchange. Results from a series of eddy-resolving primitive equation model calculations for the meridional heat transport, overturning circulation, density of convective waters, and density of exported waters compare well with predictions from the conceptual model over a wide range of parameter space. Scaling and model results indicate that wind effects are small and the mean exchange is primarily buoyancy forced. These results imply that one must accurately resolve or parameterize eddy fluxes in order to properly represent the mean exchange between the North Atlantic and the Nordic Seas, and thus between the Nordic Seas and the atmosphere, in climate models.
    Beschreibung: This study was supported by the National Science Foundation under Grants OCE-0726339 and OCE-0850416.
    Schlagwort(e): Eddies ; Forcing ; Meridional overturning circulation ; Transport ; North Atlantic Ocean ; Seas/gulfs/bays
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  • 7
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    Wind-driven cross-equatorial flow in the Indian Ocean (2013)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2012. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 42 (2012): 2234–2253, doi:10.1175/JPO-D-12-033.1.
    Beschreibung: Meridional velocity, mass, and heat transport in the equatorial oceans are difficult to estimate because of the nonapplicability of the geostrophic balance. For this purpose a steady-state model is utilized in the equatorial Indian Ocean using NCEP wind stress and temperature and salinity data from the World Ocean Atlas 2005 (WOA05) and Argo. The results show a Somali Current flowing to the south during the winter monsoon carrying −11.5 ± 1.3 Sv (1 Sv ≡ 106 m3 s−1) and −12.3 ± 0.3 Sv from WOA05 and Argo, respectively. In the summer monsoon the Somali Current reverses to the north transporting 16.8 ± 1.2 Sv and 19.8 ± 0.6 Sv in the WOA05 and Argo results. Transitional periods are considered together and in consequence, there is not a clear Somali Current present in this period. Model results fit with in situ measurements made around the region, although Argo data results are quite more realistic than WOA05 data results.
    Beschreibung: This study has been partly funded by the MOC Project (CTM 2008- 06438) and the Spanish contribution to the Argo network (AC2009 ACI2009-0998), financed by the Spanish Government and Feder.
    Beschreibung: 2013-06-01
    Schlagwort(e): Indian Ocean ; Subtropics ; Currents ; Ocean circulation ; Transport ; Wind stress
    Repository-Name: Woods Hole Open Access Server
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  • 8
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    On the exchange of momentum over the open ocean (2013)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2013. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 43 (2013): 1589–1610, doi:10.1175/JPO-D-12-0173.1.
    Beschreibung: This study investigates the exchange of momentum between the atmosphere and ocean using data collected from four oceanic field experiments. Direct covariance estimates of momentum fluxes were collected in all four experiments and wind profiles were collected during three of them. The objective of the investigation is to improve parameterizations of the surface roughness and drag coefficient used to estimate the surface stress from bulk formulas. Specifically, the Coupled Ocean–Atmosphere Response Experiment (COARE) 3.0 bulk flux algorithm is refined to create COARE 3.5. Oversea measurements of dimensionless shear are used to investigate the stability function under stable and convective conditions. The behavior of surface roughness is then investigated over a wider range of wind speeds (up to 25 m s−1) and wave conditions than have been available from previous oversea field studies. The wind speed dependence of the Charnock coefficient α in the COARE algorithm is modified to , where m = 0.017 m−1 s and b = −0.005. When combined with a parameterization for smooth flow, this formulation gives better agreement with the stress estimates from all of the field programs at all winds speeds with significant improvement for wind speeds over 13 m s−1. Wave age– and wave slope–dependent parameterizations of the surface roughness are also investigated, but the COARE 3.5 wind speed–dependent formulation matches the observations well without any wave information. The available data provide a simple reason for why wind speed–, wave age–, and wave slope–dependent formulations give similar results—the inverse wave age varies nearly linearly with wind speed in long-fetch conditions for wind speeds up to 25 m s−1.
    Beschreibung: This work was funded by the National Science Foundation Grant OCE04-24536 as part of the CLIVAR Mode Water Dynamics Experiment (CLIMODE) and the Office of Naval Research Grant N00014-05-1-0139 as part of the CBLAST-LOW program.
    Beschreibung: 2014-02-01
    Schlagwort(e): Wind shear ; Wind stress ; Atmosphere-ocean interaction ; Fluxes ; Momentum ; Algorithms
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  • 9
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    Stommel’s box model of thermohaline circulation revisited - the role of mechanical energy supporting mixing and the wind-driven gyration (2010)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2008. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 38 (2008): 909–917, doi:10.1175/2007JPO3535.1.
    Beschreibung: The classical two-box model of Stommel is extended in two directions: replacing the buoyancy constraint with an energy constraint and including the wind-driven gyre. Stommel postulated a buoyancy constraint for the thermohaline circulation, and his basic idea has evolved into the dominating theory of thermohaline circulation; however, recently, it is argued that the thermohaline circulation is maintained by mechanical energy from wind stress and tides. The major difference between these two types of models is the bifurcation structure: the Stommel-like model has two thermal modes (one stable and another one unstable) and one stable haline mode, whereas the energy-constraint model has one stable thermal mode and two saline modes (one stable and another one unstable). Adding the wind-driven gyre changes the threshold value of thermohaline bifurcation greatly; thus, the inclusion of the wind-driven gyre is a vital step in completely modeling the physical processes related to thermohaline circulation.
    Beschreibung: YPG was supported by the National Science Foundation of China (NSFC, 40676022), the National Basic Research Program of China (2006CB403605), and the Guangdong Natural Science Foundation (5003672). RXH was supported by the National Oceanic and Atmospheric Administration through CICOR Cooperative Agreement NA17RJ1223 to the Woods Hole Oceanographic Institution.
    Schlagwort(e): Thermohaline circulation ; Mixing ; Wind stress ; Buoyancy ; Energy budget
    Repository-Name: Woods Hole Open Access Server
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  • 10
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    The effect of breaking waves on a coupled model of wind and ocean surface waves. Part II : growing seas (2010)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2008. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 38 (2008): 2164–2184, doi:10.1175/2008JPO3962.1.
    Beschreibung: This is the second part of a two-part investigation of a coupled wind and wave model that includes the enhanced form drag of breaking waves. The model is based on the wave energy balance and the conservation of air-side momentum and energy. In Part I, coupled nonlinear advance–delay differential equations were derived, which govern the wave height spectrum, the distribution of breaking waves, and vertical air side profiles of the turbulent stress and wind speed. Numeric solutions were determined for mature seas. Here, numeric solutions for a wide range of wind and wave conditions are obtained, including young, strongly forced wind waves. Furthermore, the “spatial sheltering effect” is introduced so that smaller waves in airflow separation regions of breaking longer waves cannot be forced by the wind. The solutions strongly depend on the wave height curvature spectrum at high wavenumbers (the “threshold saturation level”). As the threshold saturation level is reduced, the effect of breaking waves becomes stronger. For young strongly forced waves (laboratory conditions), breaking waves close to the spectral peak dominate the wind input and previous solutions of a model with only input to breaking waves are recovered. Model results of the normalized roughness length are generally consistent with previous laboratory and field measurements. For field conditions, the wind stress depends sensitively on the wave height spectrum. The spatial sheltering may modify the number of breaking shorter waves, in particular, for younger seas.
    Beschreibung: This work was supported by the U.S. National Science Foundation (Grant OCE- 0526177) and the U.S. Office of Naval Research (Grant N00014–06–10729).
    Schlagwort(e): Wave breaking ; Coupled models ; Wind stress ; Momentum ; Sea state
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  • 11
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    Observations and a model of undertow over the inner continental shelf (2010)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2008. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 38 (2008): 2341-2357, doi:10.1175/2008JPO3986.1.
    Beschreibung: Onshore volume transport (Stokes drift) due to surface gravity waves propagating toward the beach can result in a compensating Eulerian offshore flow in the surf zone referred to as undertow. Observed offshore flows indicate that wave-driven undertow extends well offshore of the surf zone, over the inner shelves of Martha’s Vineyard, Massachusetts, and North Carolina. Theoretical estimates of the wave-driven offshore transport from linear wave theory and observed wave characteristics account for 50% or more of the observed offshore transport variance in water depths between 5 and 12 m, and reproduce the observed dependence on wave height and water depth. During weak winds, wave-driven cross-shelf velocity profiles over the inner shelf have maximum offshore flow (1–6 cm s−1) and vertical shear near the surface and weak flow and shear in the lower half of the water column. The observed offshore flow profiles do not resemble the parabolic profiles with maximum flow at middepth observed within the surf zone. Instead, the vertical structure is similar to the Stokes drift velocity profile but with the opposite direction. This vertical structure is consistent with a dynamical balance between the Coriolis force associated with the offshore flow and an along-shelf “Hasselmann wave stress” due to the influence of the earth’s rotation on surface gravity waves. The close agreement between the observed and modeled profiles provides compelling evidence for the importance of the Hasselmann wave stress in forcing oceanic flows. Summer profiles are more vertically sheared than either winter profiles or model profiles, for reasons that remain unclear.
    Beschreibung: This research was funded by the Ocean Sciences Division of the National Science Foundation under Grants OCE-0241292 and OCE-0548961.
    Schlagwort(e): Continental shelf ; Transport ; Shear structure/flows ; Coastal flows ; Gravity waves
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  • 12
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    Western Arctic shelfbreak eddies : formation and transport (2010)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2008. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 38 (2008): 1644-1668, doi:10.1175/2007JPO3829.1.
    Beschreibung: The mean structure and time-dependent behavior of the shelfbreak jet along the southern Beaufort Sea, and its ability to transport properties into the basin interior via eddies are explored using high-resolution mooring data and an idealized numerical model. The analysis focuses on springtime, when weakly stratified winter-transformed Pacific water is being advected out of the Chukchi Sea. When winds are weak, the observed jet is bottom trapped with a low potential vorticity core and has maximum mean velocities of O(25 cm s−1) and an eastward transport of 0.42 Sv (1 Sv ≡ 106 m3 s−1). Despite the absence of winds, the current is highly time dependent, with relative vorticity and twisting vorticity often important components of the Ertel potential vorticity. An idealized primitive equation model forced by dense, weakly stratified waters flowing off a shelf produces a mean middepth boundary current similar in structure to that observed at the mooring site. The model boundary current is also highly variable, and produces numerous strong, small anticyclonic eddies that transport the shelf water into the basin interior. Analysis of the energy conversion terms in both the mooring data and the numerical model indicates that the eddies are formed via baroclinic instability of the boundary current. The structure of the eddies in the basin interior compares well with observations from drifting ice platforms. The results suggest that eddies shed from the shelfbreak jet contribute significantly to the offshore flux of heat, salt, and other properties, and are likely important for the ventilation of the halocline in the western Arctic Ocean. Interaction with an anticyclonic basin-scale circulation, meant to represent the Beaufort gyre, enhances the offshore transport of shelf water and results in a loss of mass transport from the shelfbreak jet.
    Beschreibung: This study was supported by the National Science Foundation Office of Polar Programs under Grants 0421904 and 035268 (MS), and by the Office of Naval Research Grant N00014-02-1-0317 (RP and PF). Analysis by AJP was supported by the Office of Naval Research under Grant N00014-97-1-0135 and by the National Science Foundation under Grant OPP-9815303.
    Schlagwort(e): Arctic ; Eddies ; Transport ; Currents ; Jets
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  • 13
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    Decadal changes of wind stress over the Southern Ocean associated with Antarctic ozone depletion (2010)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 20 (2007): 3395-3410, doi:10.1175/JCLI4195.1
    Beschreibung: Using 40-yr ECMWF Re-Analysis (ERA-40) data and in situ observations, the positive trend of Southern Ocean surface wind stress during two recent decades is detected, and its close linkage with spring Antarctic ozone depletion is established. The spring Antarctic ozone depletion affects the Southern Hemisphere lower-stratospheric circulation in late spring/early summer. The positive feedback involves the strengthening and cooling of the polar vortex, the enhancement of meridional temperature gradients and the meridional and vertical potential vorticity gradients, the acceleration of the circumpolar westerlies, and the reduction of the upward wave flux. This feedback loop, together with the ozone-related photochemical interaction, leads to the upward tendency of lower-stratospheric zonal wind in austral summer. In addition, the stratosphere–troposphere coupling, facilitated by ozone-related dynamics and the Southern Annular Mode, cooperates to relay the zonal wind anomalies to the upper troposphere. The wave–mean flow interaction and the meridional circulation work together in the form of the Southern Annular Mode, which transfers anomalous wind signals downward to the surface, triggering a striking strengthening of surface wind stress over the Southern Ocean.
    Beschreibung: This study was supported by MOST of China (Grant 2006CB403604) and Chinese Academy of Sciences (Grant KZSW2-YW-214) (for YXY and DXW) and W. Alan Clark Chair from Woods Hole Oceanographic Institution (for RXH).
    Schlagwort(e): Wind stress ; Decadal variability ; Ozone ; Southern Ocean ; Stratospheric circulation
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  • 14
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    The western North Atlantic shelfbreak current system in summer (2010)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography. 37 (2007): 2509-2533, doi:10.1175/JPO3123.1.
    Beschreibung: Twelve years of historical hydrographic data, spanning the period 1990–2001, are analyzed to examine the along-stream evolution of the western North Atlantic Ocean shelfbreak front and current, following its path between the west coast of Greenland and the Middle Atlantic Bight. Over 700 synoptic sections are used to construct a mean three-dimensional description of the summer shelfbreak front and to quantify the along-stream evolution in properties, including frontal strength and grounding position. Results show that there are actually two fronts in the northern part of the domain—a shallow front located near the shelf break and a deeper front centered in the core of Irminger Water over the upper slope. The properties of the deeper Irminger front erode gradually to the south, and the front disappears entirely near the Grand Banks of Newfoundland. The shallow shelfbreak front is identifiable throughout the domain, and its properties exhibit large variations from north to south, with the largest changes occurring near the Tail of the Grand Banks. Despite these structural changes, and large variations in topography, the foot of the shelfbreak front remains within 20 km of the shelf break. The hydrographic sections are also used to examine the evolution of the baroclinic velocity field and its associated volume transport. The baroclinic velocity structure consists of a single velocity core that is stronger and penetrates deeper where the Irminger front is present. The baroclinic volume transport decreases by equal amounts at the southern end of the Labrador Shelf and at the Tail of the Grand Banks. Overall, the results suggest that the Grand Banks is a geographically critical location in the North Atlantic shelfbreak system.
    Beschreibung: This work was supported by the National Science Foundation under Grants OCE00- 95261 (PF) and OCE-0450658 (RP).
    Schlagwort(e): Continental shelf ; Currents ; Atlantic Ocean ; Fronts ; Transport
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  • 15
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    Effect of sea surface temperature-wind stress coupling on baroclinic instability in the ocean (2010)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 37 (2007): 1092–1097, doi:10.1175/JPO3045.1.
    Beschreibung: The impact of the observed relationship between sea surface temperature and surface wind stress on baroclinic instability in the ocean is explored using linear theory and a nonlinear model. A simple parameterization of the influence of sea surface temperature on wind stress is used to derive a surface boundary condition for the vertical velocity at the base of the oceanic Ekman layer. This boundary condition is applied to the classic linear, quasigeostrophic stability problem for a uniformly sheared flow originally studied by Eady in the 1940s. The results demonstrate that for a wind directed from warm water toward cold water, the coupling acts to enhance the growth rate, and increase the wavelength, of the most unstable wave. Winds in the opposite sense reduce the growth rate and decrease the wavelength of the most unstable wave. For representative coupling strengths, the change in growth rate can be as large as ±O(50%). This effect is largest for shallow, strongly stratified, low-latitude flows.
    Beschreibung: This work was supported by the Office of Naval Research Grant N00014-05-1-0300.
    Schlagwort(e): Wind stress ; Instability ; Sea surface temperature ; Baroclinic flows ; Ocean dynamics
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  • 16
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    Offshore transport of shelf waters through interaction of vortices with a shelfbreak current (2013)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2013. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 43 (2013): 905–919, doi:10.1175/JPO-D-12-0150.1.
    Beschreibung: Interactions between vortices and a shelfbreak current are investigated, with particular attention to the exchange of waters between the continental shelf and slope. The nonlinear, three-dimensional interaction between an anticyclonic vortex and the shelfbreak current is studied in the laboratory while varying the ratio ε of the maximum azimuthal velocity in the vortex to the maximum alongshelf velocity in the shelfbreak current. Strong interactions between the shelfbreak current and the vortex are observed when ε 〉 1; weak interactions are found when ε 〈 1. When the anticyclonic vortex comes in contact with the shelfbreak front during a strong interaction, a streamer of shelf water is drawn offshore and wraps anticyclonically around the vortex. Measurements of the offshore transport and identification of the particle trajectories in the shelfbreak current drawn offshore from the vortex allow quantification of the fraction of the shelfbreak current that is deflected onto the slope; this fraction increases for increasing values of ε. Experimental results in the laboratory are strikingly similar to results obtained from observations in the Middle Atlantic Bight (MAB); after proper scaling, measurements of offshore transport and offshore displacement of shelf water for vortices in the MAB that span a range of values of ε agree well with laboratory predictions.
    Beschreibung: Laboratory work was supported by the National Science Foundation through Grant OCE- 0081756. Glider observations in March–April 2006 were supported by the National Science Foundation through Grant OCE-0220769. Glider observations in July– October 2007 were supported by a grant from Raytheon. RET was supported by the Postdoctoral Scholar Program at the Woods Hole Oceanographic Institution, with funding provided by the Cooperative Institute for the North Atlantic Region. The REMUS observations were funded by the Office of Naval Research. GGG was supported by the National Science Foundation through Grant OCE-1129125 for analysis and writing.
    Beschreibung: 2013-11-01
    Schlagwort(e): Continental shelf/slope ; Eddies ; Fronts ; Transport ; Laboratory/physical models
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  • 17
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    The turbulent oscillator : a mechanism of low-frequency variability of the wind-driven ocean gyres (2010)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography. 37 (2007): 2363-2386, doi:10.1175/jpo3118.1.
    Beschreibung: Intrinsic low-frequency variability is studied in the idealized, quasigeostrophic, midlatitude, wind-driven ocean gyres operating at large Reynolds number. A robust decadal variability mode driven by the transient mesoscale eddies is found and analyzed. The variability is a turbulent phenomenon, which is driven by the competition between the eddy rectification process and the potential vorticity anomalies induced by changes of the intergyre transport
    Beschreibung: Funding for Pavel Berloff was provided by NSF Grants OCE-0091836 and OCE- 0344094, by the U.K. Royal Society Fellowship, and by the Newton Trust Award, A. M. Hogg was supported by an Australian Research Council Postdoctoral Fellowship (DP0449851) during this work, and William K. Dewar was supported by NSF Grants OCE-0424227 and OCE-0550139.
    Schlagwort(e): Turbulence ; Gyres ; Transport ; Potential vorticity ; Mesoscale processes
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  • 18
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    Potential vorticity constraint on the flow between two basins (2010)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography. 37 (2007): 2251-2266, doi:10.1175/jpo3116.1.
    Beschreibung: This paper examines the role of potential vorticity (PV) balance in source- and sink-driven flows between two basins. As shown in previous studies, PV advection into a basin, say a positive PV advection, requires a negative frictional torque to maintain a steady PV balance. This sense of torque may be provided by a cyclonic boundary current within the basin. The PV advection through a channel is due almost entirely to advection of planetary PV, f/H, where f is the Coriolis parameter and H is the column thickness. Therefore a localized change of depth, and thus H in the channel, directly affects the PV transport and will result in a basinwide change of the circulation pattern. For example, if the channel depth is made shallower while holding the transport fixed, the PV advection is then increased and the result may be a strong recirculation within the basin, as much as two orders of magnitude greater than the transport through the channel. When the basins are connected by two channels at different latitudes or with different sill depths, the throughflow is found to be divided between the two channels in a way that satisfies the integral constraint for flow around an island. The partition of the flow between two channels appears to be such as to minimize the net frictional torque. In still another set of experiments, the large-scale pressure difference (layer thickness) between the basins is specified and held fixed, while the throughflow is allowed to vary in response to changes in the frictional torque. The interbasin transport is strongly influenced by the length of the boundary or the magnitude of the viscosity in the sense that a greater PV frictional torque allows a greater PV transport and vice versa. This result is counterintuitive, if it is assumed that the throughflow is determined by viscous drag within the channel but is a straightforward consequence of the basin-scale PV balance. Thus, the important frictional effect in these experiments is on the basin-scale flow and not on the channel scale.
    Beschreibung: This study is supported by NSF Grants OCE-0611530 and OCE-0351055. Price was supported in part by the U.S. Office of Naval Research through Grant 13010900.
    Schlagwort(e): Potential vorticity ; Coriolis effect ; Boundary currents ; Advection ; Friction ; Transport
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  • 19
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    The role of advection, straining, and mixing on the tidal variability of estuarine stratification (2012)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2012. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 42 (2012): 855–868, doi:10.1175/JPO-D-10-05010.1.
    Beschreibung: Data from the Hudson River estuary demonstrate that the tidal variations in vertical salinity stratification are not consistent with the patterns associated with along-channel tidal straining. These observations result from three additional processes not accounted for in the traditional tidal straining model: 1) along-channel and 2) lateral advection of horizontal gradients in the vertical salinity gradient and 3) tidal asymmetries in the strength of vertical mixing. As a result, cross-sectionally averaged values of the vertical salinity gradient are shown to increase during the flood tide and decrease during the ebb. Only over a limited portion of the cross section does the observed stratification increase during the ebb and decrease during the flood. These observations highlight the three-dimensional nature of estuarine flows and demonstrate that lateral circulation provides an alternate mechanism that allows for the exchange of materials between surface and bottom waters, even when direct turbulent mixing through the pycnocline is prohibited by strong stratification.
    Beschreibung: The funding for this research was obtained from NSF Grant OCE-08-25226.
    Beschreibung: 2012-11-01
    Schlagwort(e): Mixing ; Ocean circulation ; Shear structure/flows ; Transport ; Turbulence
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  • 20
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    The Kuroshio Extension northern recirculation gyre : profiling float measurements and forcing mechanism (2010)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2008. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 38 (2008): 1764-1779, doi:10.1175/2008JPO3921.1.
    Beschreibung: Middepth, time-mean circulation in the western North Pacific Ocean (28°–45°N, 140°–165°E) is investigated using drift information from the profiling floats deployed in the Kuroshio Extension System Study (KESS) and the International Argo programs. A well-defined, cyclonic recirculation gyre (RG) is found to exist north of the Kuroshio Extension jet, confined zonally between the Japan Trench (145°E) and the Shatsky Rise (156°E), and bordered to the north by the subarctic boundary along 40°N. This northern RG, which is simulated favorably in the eddy-resolving OGCM for the Earth Simulator (OFES) hindcast run model, has a maximum volume transport at 26.4 Sv across 159°E and its presence persists on the interannual and longer time scales. An examination of the time-mean x-momentum balance from the OFES hindcast run output reveals that horizontal convergence of Reynolds stresses works to accelerate both the eastward-flowing Kuroshio Extension jet and a westward mean flow north of the meandering jet. The fact that the northern RG is eddy driven is further confirmed by examining the turbulent Sverdrup balance, in which convergent eddy potential vorticity fluxes are found to induce the cyclonic RG across the background potential vorticity gradient field. For the strength of the simulated northern RG, the authors find the eddy dissipation effect to be important as well.
    Beschreibung: This study was supported by NSF through Grant OCE-0220680 (UH) and OCE-0220161 (WHOI).
    Schlagwort(e): Gyres ; Ocean circulation ; Profilers ; Jets ; Transport
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  • 21
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    The mechanical energy input to the ocean induced by tropical cyclones (2010)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2008. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 38 (2008): 1253-1266, doi:10.1175/2007JPO3786.1.
    Beschreibung: Wind stress and tidal dissipation are the most important sources of mechanical energy for maintaining the oceanic general circulation. The contribution of mechanical energy due to tropical cyclones can be a vitally important factor in regulating the oceanic general circulation and its variability. However, previous estimates of wind stress energy input were based on low-resolution wind stress data in which strong nonlinear events, such as tropical cyclones, were smoothed out. Using a hurricane–ocean coupled model constructed from an axisymmetric hurricane model and a three-layer ocean model, the rate of energy input to the world’s oceans induced by tropical cyclones over the period from 1984 to 2003 was estimated. The energy input is estimated as follows: 1.62 TW to the surface waves and 0.10 TW to the surface currents (including 0.03 TW to the near-inertial motions). The rate of gravitational potential energy increase due to tropical cyclones is 0.05 TW. Both the energy input from tropical cyclones and the increase of gravitational potential energy of the ocean show strong interannual and decadal variability with an increasing rate of 16% over the past 20 years. The annual mean diapycnal upwelling induced by tropical cyclones over the past 20 years is estimated as 39 Sv (Sv ≡ 106 m3 s−1). Owing to tropical cyclones, diapycnal mixing in the upper ocean (below the mixed layer) is greatly enhanced. Within the regimes of strong activity of tropical cyclones, the increase of diapycnal diffusivity is on the order of (1 − 6) × 10−4 m2 s−1. The tropical cyclone–related energy input and diapycnal mixing may play an important role in climate variability, ecology, fishery, and environments.
    Beschreibung: LLL and WW were supported by the National Basic Research Priorities Programmer of China through Grant 2007CB816004 and National Outstanding Youth Natural Science Foundation of China FIG. 15. Annual-mean vertical diffusivity induced by tropical cyclones from 1984 to 2003 (units: 10 4 m2 s 1): (right) the horizontal distribution and (left) the zonally averaged vertical diffusivity. JUNE 2008 L IU ET AL . 1265 under Grant 40725017. RXH was supported by the W. Alan Clark Chair from Woods Hole Oceanographic Institution.
    Schlagwort(e): Tropical cyclones ; Ocean circulation ; Wind stress ; Mixing ; Interannual variability
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  • 22
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    Subtidal salinity and velocity in the Hudson River estuary : observations and modeling (2010)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2008. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 38 (2008): 753-770, doi:10.1175/2007JPO3808.1.
    Beschreibung: A tidally and cross-sectionally averaged model based on the temporal evolution of the quasi-steady Hansen and Rattray equations is applied to simulate the salinity distribution and vertical exchange flow along the Hudson River estuary. The model achieves high skill at hindcasting salinity and residual velocity variation during a 110-day period in 2004 covering a wide range of river discharges and tidal forcing. The approach is based on an existing model framework that has been modified to improve model skill relative to observations. The external forcing has been modified to capture meteorological time-scale variability in salinity, stratification, and residual velocity due to sea level fluctuations at the open boundary and along-estuary wind stress. To reflect changes in vertical mixing due to stratification, the vertical mixing coefficients have been modified to use the bottom boundary layer height rather than the water depth as an effective mixing length scale. The boundary layer parameterization depends on the tidal amplitude and the local baroclinic pressure gradient through the longitudinal Richardson number, and improves the model response to spring–neap variability in tidal amplitude during periods of high river discharge. Finally, steady-state model solutions are evaluated for both the Hudson River and northern San Francisco Bay over a range of forcing conditions. Agreement between the model and scaling of equilibrium salinity intrusions lends confidence that the approach is transferable to other estuaries, despite significant differences in bathymetry. Discrepancies between the model results and observations at high river discharge are indicative of limits at which the formulation begins to fail, and where an alternative approach that captures two-layer dynamics would be more appropriate.
    Beschreibung: This research was supported by the Hudson River Foundation Grant 005/03A, NSF Grant OCE-0452054, and by the Postdoctoral Scholar Program at the Woods Hole Oceanographic Institution, with funding provided by the J. Seward Johnson Fund.
    Schlagwort(e): Estuaries ; Salinity ; Rivers ; Tides ; Wind stress
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  • 23
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    The effects of mesoscale ocean–atmosphere coupling on the large-scale ocean circulation (2010)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2009. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 22 (2009): 4066–4082, doi:10.1175/2009JCLI2629.1.
    Beschreibung: Small-scale variation in wind stress due to ocean–atmosphere interaction within the atmospheric boundary layer alters the temporal and spatial scale of Ekman pumping driving the double-gyre circulation of the ocean. A high-resolution quasigeostrophic (QG) ocean model, coupled to a dynamic atmospheric mixed layer, is used to demonstrate that, despite the small spatial scale of the Ekman-pumping anomalies, this phenomenon significantly modifies the large-scale ocean circulation. The primary effect is to decrease the strength of the nonlinear component of the gyre circulation by approximately 30%–40%. This result is due to the highest transient Ekman-pumping anomalies destabilizing the flow in a dynamically sensitive region close to the western boundary current separation. The instability of the jet produces a flux of potential vorticity between the two gyres that acts to weaken both gyres.
    Beschreibung: AH and WD were supported by an ARC Linkage International Grant (LX0668781). WD was also supported by NSF Grants OCE 0424227 and OCE 0550139. Funding for PB was provided by NSF Grants OCE 0344094 and OCE 0725796 and by the research grant from the Newton Trust of the University of Cambridge. SK was supported by U.S. DOE Grant DE-FG02–02ER63413 and NASA Grant NNG-06- AG66G-1.
    Schlagwort(e): Airndashsea interaction ; Coupled models ; Mesoscale processes ; Wind stress ; Ekman pumping/transport
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  • 24
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    Anisotropic material transport by eddies and eddy-driven currents in a model of the North Atlantic (2010)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2009. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 39 (2009): 3162-3175, doi:10.1175/2009JPO4239.1.
    Beschreibung: This study analyzes anisotropic properties of the material transport by eddies and eddy-driven zonal jets in a general circulation model of the North Atlantic through the analysis of Lagrangian particle trajectories. Spreading rates—defined here as half the rate of change in the particle dispersion—in the zonal direction systematically exceed the meridional rates by an order of magnitude. Area-averaged values for the upper-ocean zonal and meridional spreading rates are approximately 8100 and 1400 m2 s−1, respectively, and in the deep ocean they are 2400 and 200 m2 s−1. The results demonstrate that this anisotropy is mainly due to the action of the transient eddies and not to the shear dispersion associated with the time-mean jets. This property is consistent with the fact that eddies in this study have zonally elongated shapes. With the exception of the upper-ocean subpolar gyre, eddies also cause the superdiffusive zonal spreading, significant variations in the spreading rate in the vertical and meridional directions, and the difference between the westward and eastward spreading.
    Beschreibung: Funding for IK was provided by NSF Grants OCE 0346178, 0749722, and 0842834. Funding for PB was provided by NSF Grants OCE 0344094 and OCE 0725796 and by the research grant from the Newton Trust of the University of Cambridge. For JP the acknowledgement is to NSF OCE-0451086.
    Schlagwort(e): Eddies ; Transport ; Currents ; North Atlantic Ocean
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  • 25
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    Transport in an idealized three-gyre system with application to the Adriatic Sea (2010)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2009. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 39 (2009): 675-690, doi:10.1175/2008JPO3975.1.
    Beschreibung: Motivated by observations of surface drifters in the Adriatic Sea, transport in a three-gyre system is studied with the aid of dynamical systems techniques. Particular attention is paid to the issue of intergyre transport. The velocity field is assumed to be two-dimensional and incompressible and composed of a steady three-gyre background flow on which a time-dependent perturbation is superimposed. Two systems of this type are considered: 1) an observationally motivated, analytically prescribed model consisting of a steady background on which a multiperiodic time-dependent perturbation is superimposed, and 2) an observationally based model of the Adriatic Sea consisting of the mean surface circulation derived from surface drifter trajectories on which a time-dependent altimetry-based perturbation velocity field is superimposed. It is shown that for a small perturbation to the steady three-gyre background, two of the gyres exchange no fluid with the third gyre. When the perturbation strength exceeds a certain threshold, transport between all three gyres occurs. This behavior is described theoretically, illustrated using the analytic model and shown to be consistent with the observationally based model of the Adriatic. The relevance of the work presented to more complicated multiple-gyre problems is discussed.
    Beschreibung: This work was supported by the National Science Foundation Grants CMG0417425 and CMG0825547.
    Schlagwort(e): Transport ; Gyres ; Mediterranean region ; Ocean circulation ; Lagrangian circulation
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  • 26
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    Transport and dynamics of the Panay Sill overflow in the Philippine Seas (2011)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2010. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 40 (2010): 2679–2695, doi:10.1175/2010JPO4395.1.
    Beschreibung: Observations of stratification and currents between June 2007 and March 2009 reveal a strong overflow between 400- and 570-m depth from the Panay Strait into the Sulu Sea. The overflow water is derived from approximately 400 m deep in the South China Sea. Temporal mean velocity is greater than 0.75 m s−1 at 50 m above the 570-m Panay Sill. Empirical orthogonal function analysis of a mooring time series shows that the flow is dominated by the bottom overflow current with little seasonal variance. The overflow does not descend below 1250 m in the Sulu Sea but rather settles above high-salinity deep water derived from the Sulawesi Sea. The mean observed overflow transport at the sill is 0.32 × 106 m3 s−1. The observed transport was used to calculate a bulk diapycnal diffusivity of 4.4 × 10−4 m2 s−1 within the Sulu Sea slab (575–1250 m) ventilated from Panay Strait. Analysis of Froude number variation across the sill shows that the flow is hydraulically controlled. A suitable hydraulic control model shows overflow transport equivalent to the observed overflow. Thorpe-scale estimates show turbulent dissipation rates up to 5 × 10−7 W kg−1 just downstream of the supercritical to subcritical flow transition, suggesting a hydraulic jump downstream of the sill.
    Beschreibung: This work was supported by the Office of Naval Research Grant N00014-09-1-0582 to Lamont-Doherty Earth Observatory of Columbia University; Grants ONR-13759000 and N00014-09-1-0582 to the Woods Hole Oceanographic Institution; Grant ONR-N00014-06-1-0690 to Scripps Institute of Oceanography; and a National Defense Science and Engineering Graduate Fellowship.
    Schlagwort(e): Transport ; Dynamics ; Topographic effects ; Currents ; Empirical orthogonal functions
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  • 27
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    Near-surface transport pathways in the north Atlantic Ocean : looking for throughput from the subtropical to the subpolar gyre (2011)
    American Meteorological Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society, 2011. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 41 (2011): 911–925, doi:10.1175/2011JPO4498.1.
    Beschreibung: Motivated by discrepancies between Eulerian transport estimates and the behavior of Lagrangian surface drifters, near-surface transport pathways and processes in the North Atlantic are studied using a combination of data, altimetric surface heights, statistical analysis of trajectories, and dynamical systems techniques. Particular attention is paid to the issue of the subtropical-to-subpolar intergyre fluid exchange. The velocity field used in this study is composed of a steady drifter-derived background flow, upon which a time-dependent altimeter-based perturbation is superimposed. This analysis suggests that most of the fluid entering the subpolar gyre from the subtropical gyre within two years comes from a narrow region lying inshore of the Gulf Stream core, whereas fluid on the offshore side of the Gulf Stream is largely prevented from doing so by the Gulf Stream core, which acts as a strong transport barrier, in agreement with past studies. The transport barrier near the Gulf Stream core is robust and persistent from 1992 until 2008. The qualitative behavior is found to be largely independent of the Ekman drift.
    Beschreibung: This work was supported by the National Science Foundation Grants CMG-82469600 and CMG-82579600 and by the Office of Naval Research Grant ONR-13108700.
    Schlagwort(e): Atlantic Ocean ; Transport ; Gyres ; Lagrangian circulation/transport ; Tracers ; Currents ; Meridional overturning circulation
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  • 28
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    An enhancement of low-frequency variability in the Kuroshio–Oyashio Extension in CCSM3 owing to ocean model biases (2011)
    American Meteorological Society
    Details
    Publikationsdatum: 2022-05-26
    Beschreibung: Author Posting. © American Meteorological Society, 2010. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 23 (2010): 6221–6233, doi:10.1175/2010JCLI3402.1.
    Beschreibung: Enhanced decadal variability in sea surface temperature (SST) centered on the Kuroshio Extension (KE) has been found in the Community Climate System Model version 3 (CCSM3) as well as in other coupled climate models. This decadal peak has higher energy than is found in nature, almost twice as large in some cases. While previous analyses have concentrated on the mechanisms for such decadal variability in coupled models, an analysis of the causes of excessive SST response to changes in wind stress has been missing. Here, a detailed comparison of the relationships between interannual changes in SST and sea surface height (SSH) as a proxy for geostrophic surface currents in the region in both CCSM3 and observations, and how these relationships depend on the mean ocean circulation, temperature, and salinity, is made. We use observationally based climatological temperature and salinity fields as well as satellite-based SSH and SST fields for comparison. The primary cause for the excessive SST variability is the coincidence of the mean KE with the region of largest SST gradients in the model. In observations, these two regions are separated by almost 500 km. In addition, the too shallow surface oceanic mixed layer in March north of the KE in the subarctic Pacific contributes to the biases. These biases are not unique to CCSM3 and suggest that mean biases in current, temperature, and salinity structures in separated western boundary current regions can exert a large influence on the size of modeled decadal SST variability.
    Beschreibung: Support for L.T. was provided by the NASA sponsored Ocean Surface Topography Science Team, under Contract 1267196 with the University of Washington, administered by the Jet Propulsion Laboratory. Support for Y.-O. K. comes from the NOAA Office of Global Programs (grant to C. Deser and Y.-O. Kwon) and the WHOI Heyman fellowship.
    Schlagwort(e): Bias ; Coupled models ; Decadal variability ; Ocean models ; Sea surface temperature ; Wind stress
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
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  • 29
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    Residual sediment fluxes in weakly-to-periodically stratified estuaries and tidal inlets (2013)
    American Meteorological Society
    Details
    Publikationsdatum: 2022-05-26
    Beschreibung: Author Posting. © American Meteorological Society, 2013. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 43 (2013): 1841–1861, doi:10.1175/JPO-D-12-0231.1.
    Beschreibung: In this idealized numerical modeling study, the composition of residual sediment fluxes in energetic (e.g., weakly or periodically stratified) tidal estuaries is investigated by means of one-dimensional water column models, with some focus on the sediment availability. Scaling of the underlying dynamic equations shows dependence of the results on the Simpson number (relative strength of horizontal density gradient) and the Rouse number (relative settling velocity) as well as impacts of the Unsteadiness number (relative tidal frequency). Here, the parameter space given by the Simpson and Rouse numbers is mainly investigated. A simple analytical model based on the assumption of stationarity shows that for small Simpson and Rouse numbers sediment flux is down estuary and vice versa for large Simpson and Rouse numbers. A fully dynamic water column model coupled to a second-moment turbulence closure model allows to decompose the sediment flux profiles into contributions from the transport flux (product of subtidal velocity and sediment concentration profiles) and the fluctuation flux profiles (tidal covariance between current velocity and sediment concentration). Three different types of bottom sediment pools are distinguished to vary the sediment availability, by defining a time scale for complete sediment erosion. For short erosion times scales, the transport sediment flux may dominate, but for larger erosion time scales the fluctuation sediment flux largely dominates the tidal sediment flux. When quarter-diurnal components are added to the tidal forcing, up-estuary sediment fluxes are strongly increased for stronger and shorter flood tides and vice versa. The theoretical results are compared to field observations in a tidally energetic inlet.
    Beschreibung: Project funding was provided by the German Research Foundation (DFG) in the framework of the Project ECOWS (Role of Estuarine Circulation for Transport of Suspended Particulate Matter in the Wadden Sea, BU 1199/11) and by the German Federal Ministry of Research and Education in the framework of the Project PACE [The future of the Wadden Sea sediment fluxes: still keeping pace with sea level rise? (FKZ 03F0634A)].
    Beschreibung: 2014-03-01
    Schlagwort(e): Channel flows ; Coastal flows ; Mixing ; Transport ; Turbulence ; Single column models
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Format: application/pdf
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  • 30
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    Continuous, array-based estimates of Atlantic Ocean heat transport at 26.5°N (2011)
    American Meteorological Society
    Details
    Publikationsdatum: 2022-05-26
    Beschreibung: Author Posting. © American Meteorological Society, 2011. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 24 (2011): 2429–2449, doi:10.1175/2010JCLI3997.1.
    Beschreibung: Continuous estimates of the oceanic meridional heat transport in the Atlantic are derived from the Rapid Climate Change–Meridional Overturning Circulation (MOC) and Heatflux Array (RAPID–MOCHA) observing system deployed along 26.5°N, for the period from April 2004 to October 2007. The basinwide meridional heat transport (MHT) is derived by combining temperature transports (relative to a common reference) from 1) the Gulf Stream in the Straits of Florida; 2) the western boundary region offshore of Abaco, Bahamas; 3) the Ekman layer [derived from Quick Scatterometer (QuikSCAT) wind stresses]; and 4) the interior ocean monitored by “endpoint” dynamic height moorings. The interior eddy heat transport arising from spatial covariance of the velocity and temperature fields is estimated independently from repeat hydrographic and expendable bathythermograph (XBT) sections and can also be approximated by the array. The results for the 3.5 yr of data thus far available show a mean MHT of 1.33 ± 0.40 PW for 10-day-averaged estimates, on which time scale a basinwide mass balance can be reasonably assumed. The associated MOC strength and variability is 18.5 ± 4.9 Sv (1 Sv ≡ 106 m3 s−1). The continuous heat transport estimates range from a minimum of 0.2 to a maximum of 2.5 PW, with approximately half of the variance caused by Ekman transport changes and half caused by changes in the geostrophic circulation. The data suggest a seasonal cycle of the MHT with a maximum in summer (July–September) and minimum in late winter (March–April), with an annual range of 0.6 PW. A breakdown of the MHT into “overturning” and “gyre” components shows that the overturning component carries 88% of the total heat transport. The overall uncertainty of the annual mean MHT for the 3.5-yr record is 0.14 PW or about 10% of the mean value.
    Beschreibung: This research was supported by the U.S. National Science Foundation under Awards OCE0241438 and OCE0728108, by the U.K. RAPID Programme (RAPID Grant NER/T/S/2002/00481), and by the U.S. National Oceanic and Atmospheric Administration, as part of its Western Boundary Time Series Program.
    Schlagwort(e): Atlantic Ocean ; Meridonial overturning circulation ; Sea surface temperature ; Transport ; Anomalies
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Format: application/pdf
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  • 31
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    Aerial imaging of fluorescent dye in the near shore (2014)
    American Meteorological Society
    Details
    Publikationsdatum: 2022-05-26
    Beschreibung: Author Posting. © American Meteorological Society, 2014. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Atmospheric and Oceanic Technology 31 (2014): 1410–1421, doi:10.1175/JTECH-D-13-00230.1.
    Beschreibung: Aerial images are used to quantify the concentration of fluorescent Rhodamine water tracing (WT) dye in turbid and optically deep water. Tracer releases near the shoreline of an ocean beach and near a tidal inlet were observed with a two-band multispectral camera and a pushbroom hyperspectral imager, respectively. The aerial observations are compared with near-surface in situ measurements. The ratio of upwelling radiance near the Rhodamine WT excitation and emission peaks varies linearly with the in situ dye concentrations for concentrations 〈20 ppb (r2 = 0.70 and r2 = 0.85–0.88 at the beach and inlet, respectively). The linear relationship allows for relative tracer concentration estimates without in situ calibration. The O(1 m) image pixels resolve complex flow structures on the inner shelf that transport and mix tracer.
    Beschreibung: We thank ONR and NSF for funding this work.
    Beschreibung: 2014-12-01
    Schlagwort(e): Coastal flows ; Mixing ; Transport ; Aircraft observations ; Remote sensing ; Tracers
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Format: application/pdf
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  • 32
    Digitale Medien
    Digitale Medien
    Ein Tabu Search-Verfahren für Containerbeladeprobleme mit schwach heterogenem Kistenvorrat (1998)
    Springer
    OR spectrum 20 (1998), S. 237-250 
    Details
    ISSN: 1436-6304
    Schlagwort(e): Transport ; Container ; Containerbelade-problem ; Tabu Search ; Praxisrelevante Restriktionen ; Packing ; Container ; Container loading problem ; Tabu search ; Practical restrictions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Abstract The paper presents a tabu search algorithm (TSA) for weakly heterogeneous container loading problems. The approach includes two integrated components: The generation of different stowage plans by means of a greedy algorithm and a tabu search using an appropriate representation of these plans. The TSA considers some restrictions of practical relevance. The overall algorithm has been applied to numerous benchmark problems and its performance is demonstrated by a numerical comparison with several loading procedures suggested by other authors.
    Notizen: Zusammenfassung Gegenstand des Beitrags ist die Entwicklung eines Tabu Search-Verfahrens (TSV) für Containerbeladeprobleme mit schwach heterogenem Kistenvorrat. Das TSV basiert auf einem zweistufigen Verfahrensansatz. Ein integrierter Greedy-Algorithmus dient unmittelbar der Erzeugung von Stauplänen. Vermittelt über eine geeignete Repräsentation zulässiger Problemlösungen wird in einer zweiten Verfahrensstufe eine Tabu-Suche durchgeführt. Das TSV berücksichtigt einige praxisrelevante Restriktionen. Die Performance des TSV wird anhand von Benchmarkproblemen aus der Literatur demonstriert, wobei Containerbeladeverfahren verschiedener Autoren zu Vergleichszwecken herangezogen werden.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01539742
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  • 33
    Digitale Medien
    Digitale Medien
    Molecular identification of co-occurring Cortinarius and Dermocybe species from southeastern Australian sclerophyll forests (1999)
    Springer
    Mycorrhiza 9 (1999), S. 85-90 
    Details
    ISSN: 1432-1890
    Schlagwort(e): Key words PCR ; RFLP ; ITS sequence analysis ; Ectomycorrhizal fungi ; Cortinarius taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  The ability of restriction fragment length polymorphism (RFLP) analysis of the rDNA internal transcribed spacer (ITS) region to discriminate 10 co-occurring Cortinarius and Dermocybe species at a southeastern Australian sclerophyll forest site was assessed. Using the basidiomycete-specific primers ITS1F and ITS4B, some taxa were separated on the basis of individual RFLP patterns derived using the restriction endonucleases Hae III or Hinf I. Combined data from both endonucleases were, however, required to separate all taxa [Dermocybe austro-veneta Clel. (Moser & Horak), C. rotundisporus Clel. & Cheel, C. archeri Berk., C. sinapicolor Clel., C. violaceus (L.: Fr.) S.F.Gray, C. radicatus Clel. and four morphologically-distinct, but unidentified Cortinarius spp.]. ITS sequence comparisons confirmed that D. austro-veneta belongs in Dermocybe, that C. rotundisporus is correctly placed in subgenus Phlegmacium, and suggest that Australian C. violaceus collections are not conspecific with northern hemisphere C. violaceus.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s005720050004
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  • 34
    Digitale Medien
    Digitale Medien
    Survival of bacteria introduced into soil by means of transport by Lumbricus rubellus (1995)
    Springer
    Biology and fertility of soils 20 (1995), S. 63-69 
    Details
    ISSN: 1432-0789
    Schlagwort(e): Lumbricus rubellus ; Introduced bacteria ; Transport ; Survival ; Casts
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Four strains of bacteria, Rhizobium leguminosarum biovar trifolii, Pseudomonas fluorescens, Pseudomonas cepacia, and Flavobacterium sp., were introduced into loamy sand and then transported by earthworms of the species Lumbricus rubellus to uninoculated soil. Cell densities recovered from the earthworm gut and casts (both expressed per gram dry material) were significantly lower (up to 3 log units) than cell densities recovered from the inoculated soil. Total bacterial counts in casts were similar to those in the inoculated soil. In casts excreted into a sterile environment numbers of colony-forming units (CFU) increased, suggesting a favourable environment for growth. In casts excreted in a non-sterile environment, cell densities of introduced strains decreased. Casts therefore did not offer the introduced bacteria a protective micro-environment for survival in the bulk soil. Transport by worms of R. leguminosarum biovar trifolii and of P. fluorescens appeared to occur mostly by means of cast production; with the Flavobacterium sp. and P. cepacia a large proportion of the cells was possibly transported on the skin of earthworms.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307843
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  • 35
    Digitale Medien
    Digitale Medien
    Sex in Escherichia coli does not disrupt the clonal structure of the population: evidence from random amplified polymorphic DNA and restriction-fragment-length polymorphism (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 440-448 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Escherichia coli ; RAPD ; RFLP ; Clonal theory ; Recombination
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Analysis of the Escherichia coli population by multilocus enzyme electrophoresis (MLEE) has established its clonal organization, but there is increasing evidence that horizontal DNA transfer occurs in E. coli. We have assessed the genetic structure of the species E. coli and determined the extent to which recombination can affect the clonal structure of bacteria. A panel of 72 E. coli strains from the ECOR collection was characterized by random amplified polymorphic DNA (RAPD) and restriction-fragment-length polymorphism (RFLP) of the ribosomal RNA gene (rrn) regions. These strains have been characterized by MLEE and are assumed to reflect the range of genotypic variation in the species as a whole. Statistical analysis, including factorial analysis of correspondence (FAC) and hierarchical classifications, established that the data obtained with the three genetic markers are mutually corroborative, thus providing compelling evidence that horizontal transfer does not disrupt the clonal organization of the population. However, there is a gradient of correlation between the different classifications which ranges from the highly clonal structure of 132 group strains causing extraintestinal infections in humans to the less-stringent structure of B1 group strains that came mainly from nonprimate mammals. This group (B1) appears to be the framework from which the remaining non-A group strains have emerged. These results indicate that RAPD analysis is well suited to intraspecies characterization of E. coli. Lastly, treating the RAPD data by FAC allowed description of subgroup-specific DNA fragments which can be used, in a strategy comparable to positional cloning, to isolate virulence genes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00160315
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  • 36
    Digitale Medien
    Digitale Medien
    Comparative Analysis of Different DNA Extraction Protocols: A Fast, Universal Maxi-Preparation of High Quality Plant DNA for Genetic Evaluation and Phylogenetic Studies (1998)
    Springer
    Plant molecular biology reporter 16 (1998), S. 69-86 
    Details
    ISSN: 1572-9818
    Schlagwort(e): cpDNA ; DNA extraction ; fingerprinting ; forest trees ; M13 fingerprinting ; method ; PCR ; rDNA ; RFLP ; rhododendron ; plant
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Four DNA extraction protocols were compared for ability to produce DNA from the leaves or needles of several species: oak, elm, pine, fir, poplar and maize (fresh materials) and rhododendron (silica dried or frozen material). With the exception of maize and poplar, the species are known to be difficult for DNA extraction. Two protocols represented classical procedures for lysis and purification, and the other two were a combination of classical lysis followed by anion exchange chromatography. The DNA obtained from all procedures was quantified and tested by PCR and Southern hybridisation.Test results indicated superiority of one of the four protocols; a combination of CTAB lysis followed by anion exchange chromatography which enabled DNA extraction from all seven species. A second protocol also produced DNA from leaves or needles of all species investigated and was well suited for PCR applications but not Southern hybridisations. The remaining protocols produced DNA from some but not all species tested. Abbreviations: CTAB, hexadecyltrimethylammonium bromide; EtOH, Ethanol; TBE, tris-borate-EDTA.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1007428009556
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  • 37
    Digitale Medien
    Digitale Medien
    A Rapid DNA Extraction Method for RFLP and PCR Analysis from a Single Dry Seed (1998)
    Springer
    Plant molecular biology reporter 16 (1998), S. 90-90 
    Details
    ISSN: 1572-9818
    Schlagwort(e): DNA extration ; DNA fingerprint ; half seed ; PCR ; RFLP ; target gene
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A single-seed DNA extraction method was developed for rapid identification of plant genotype. The method was applied to 12 plant species, including the oil seeds sesame and soybean. The results were comparable to those obtained for oil-less seeds such as rice. This method will be useful for genotypic selection which requires rapid screening of large populations. It can also be used to identify varietal purity of seed stocks by PCR and RFLP analysis. The method includes two major steps, (i) treatment by proteinase K in an SDS extraction buffer, and (ii) grinding of a single half seed in the buffer after incubation. About 1.5–2 µg of DNA per half seed (the endosperm part) of rice was obtained and more than 200 half seed samples could be handled by one person in a day. The DNA could be used for fingerprinting and detection of target genes in a transgenic plant by PCR. The amplified PCR products from the half seed DNA exhibited the same banding patterns as those from leaf DNA. Yield and quality of DNA extracted from half seeds of rice was also sufficient for RFLP analysis. The remnant half seeds containing the embryo can be maintained for later germination of selected genotypes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1007418606098
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  • 38
    Digitale Medien
    Digitale Medien
    The Rev axis of HIV-1 and its associated host cofactors: A viral window onto the workings of eukaryotic posttranscriptional RNA processing (1996)
    Springer
    Journal of biomedical science 3 (1996), S. 69-77 
    Details
    ISSN: 1423-0127
    Schlagwort(e): HIV ; Rev ; Nucleus ; Transport ; RNA ; Cofactors ; Processing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The Rev axis of HIV is one of two key autoregulatory pathways required for viral replication and pathogenesis. The viral Rev protein interacts with its RNA target sequence, the RRE, to overcome the inhibitory effects of constitutive repressor sequences and promote nucleocytoplasmic transport and expression of viral RNAs. The Rev axis is the subject of intense scrutiny not only because it plays a central role in the viral life cycle, but also because it offers a window onto the workings of key mechanisms of posttranscriptional regulation, including splicing, polyadenylation, degradation, transport, and translation. Recent reports have conclusively demonstrated a central role for transport in the Rev mechanism and have identified cellular factors that are good candidates for mediating the transport phenomena. Other potentially involved cellular factors are being investigated. Much of the apparent heterogeneity in the observed effects of Rev may actually derive from heterogeneity in the constitutive repressor sequences rather than from heterogeneity in the mechanism of action of Rev per se.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02255533
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  • 39
    Digitale Medien
    Digitale Medien
    Subseabed disposal of radioactive waste: effects of consolidational fluid flow (1996)
    Springer
    Environmental geology 27 (1996), S. 300-308 
    Details
    ISSN: 1432-0495
    Schlagwort(e): Subseabed disposal ; Consolidation ; Transport
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract Subseabed disposal of radioactive waste applies a multiple-barrier concept with the sediment being the most important barrier for preventing a release of nuclides into the biosphere. While many investigations have been carried out to analyze the risk potential in this type of disposal, the effects of sediment consolidation and associated fluid flow have not fully been taken into consideration. Here, possible effects of consolidational fluid flow in the penetrator disposal option and possible consequences to the transport of nuclides in the sediment are analyzed. Results of numerical experiments demonstrate that consolidation contributes to the transport of radioactive nuclides released from containers buried in the sediment and to the release of nuclides at the sediment-water interface. Both depend on geological conditions and to a large extent on possible alterations of hydraulic conductivity i of the sediment in the vicinity of the entry path of a penetrator.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00766699
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  • 40
    Digitale Medien
    Digitale Medien
    Effective porosity and longitudinal dispersivity of sedimentary rocks determined by laboratory and field tracer tests (1995)
    Springer
    Environmental geology 25 (1995), S. 71-85 
    Details
    ISSN: 1432-0495
    Schlagwort(e): Effective porosity ; Longitudinal dispersivity ; Tracer test ; Transport ; Groundwater flow ; Sedimentary rock ; Dispersion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract We performed two field tracer tests in Tertiary sedimentary rocks and laboratory tracer tests using core samples of the sedimentary rock and bentonite and quartz sand mixtures. We have estimated effective porosity and longitudinal dispersivity, which are essential to the evaluation of mass transport in groundwater. The results of these tests indicate that test scale should be considered in the evaluation of effective porosity and longitudinal dispersivity. As the test scale increases, effective porosity decreases and longitudinal dispersivity increases. The relationship may be useful for estimating mass transport in groundwater. From the laboratory scale to the field scale, the decrease in effective porosity and increase in longitudinal dispersivity may be due to the existence of cracks or fissures. At the laboratory scale, the decrease in effective porosity is probably due to a loss of connectivity of continuous pores.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00767863
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  • 41
    Digitale Medien
    Digitale Medien
    Subseabed disposal of radioactive waste: effects of consolidational fluid flow (1996)
    Springer
    Environmental geology 27 (1996), S. 300-308 
    Details
    ISSN: 1432-0495
    Schlagwort(e): Key words: Subseabed disposal ; Consolidation ; Transport
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract. Subseabed disposal of radioactive waste applies a multiple-barrier concept with the sediment being the most important barrier for preventing a release of nuclides into the biosphere. While many investigations have been carried out to analyze the risk potential in this type of disposal, the effects of sediment consolidation and associated fluid flow have not fully been taken into consideration. Here, possible effects of consolidational fluid flow in the penetrator disposal option and possible consequences to the transport of nuclides in the sediment are analyzed. Results of numerical experiments demonstrate that consolodation contributes to the transport of radioactive nuclides released from containers buried in the sediment and to the release of nuclides at the sediment-water interface. Both depend on geological conditions and to a large extent on possible alterations of hydraulic conductivity of the sediment in the vicinity of the entry path of a penetrator.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002540050063
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  • 42
    Digitale Medien
    Digitale Medien
    A new polymorphism in the 5' flanking region of the human interleukin (IL)-4 gene (1999)
    Springer
    Immunogenetics 49 (1999), S. 738-739 
    Details
    ISSN: 1432-1211
    Schlagwort(e): Key words Interleukin (IL)-4 ; Promoter ; Polymorphism ; RFLP ; Linkage disequilibrium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002510050677
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  • 43
    Digitale Medien
    Digitale Medien
    A new polymorphism in the promoter of the Interleukin 5 receptor alpha subunit (IL-5RA) gene (1998)
    Springer
    Immunogenetics 48 (1998), S. 65-66 
    Details
    ISSN: 1432-1211
    Schlagwort(e): Key words IL-5Rα ; Promoter ; Polymorphism ; RFLP
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002510050402
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  • 44
    Digitale Medien
    Digitale Medien
    Ultrastructural and molecular study of plastid inheritance in Abies alba and some Abies hybrids (1998)
    Springer
    Sexual plant reproduction 11 (1998), S. 284-291 
    Details
    ISSN: 1432-2145
    Schlagwort(e): Key words Abies ; Egg cell ; Plastid inheritance ; RFLP ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  The ultrastructure of egg cells in Abies alba was examined to elucidate the lack of maternal inheritance of plastids. Before fertilization, maternal plastids are absent in the perinuclar zone containing mainly mitochondria and smooth endoplasmic reticulum. During egg cell development the maternal plastids are transformed into large inclusions which are situated mostly towards the periphery of the egg cell, and finally disintegrate. As a consequence, they do not participate in zygote formation. RFLP analysis of cpDNA of parental trees and their F1 interspecific hybrids (A. alba×A. numidica, A. alba×A. nordmanniana, A. nordmanniana×A. Alba) using HindIII and BamHI showed a paternal mode of cpDNA inheritance. Paternal inheritance has also been found with PCR/RFLP analysis of cpDNA from parental trees and their hybrids (A. alba×A. pinsapo, A. pinsapo×A. alba, A. pinsapo×A. numidica) using ApaI and HaeIII digests, as well as in the crosses of A. cephalonica×A. nordmanniana, A. nordmanniana×A. cephalonica, A. cephalonica×A. numidica using TagI digests.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004970050155
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  • 45
    Digitale Medien
    Digitale Medien
    Non-Mendelian and skewed segregation of DNA markers in wide crosses of the bean rust fungus,Uromyces appendiculatus (1996)
    Springer
    Current genetics 29 (1996), S. 159-167 
    Details
    ISSN: 1432-0983
    Schlagwort(e): Genetic linkage mapping ; Segregation distortion ; RAPD ; RFLP
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The inheritance of DNA markers was investigated in 27 F2 progeny from a single F1 hybrid derived from a wide cross inUromyces appendiculatus. This cross was unusual because asexual spores were used to fertilize sexual fruiting structures. Sixty percent of the DNA markers failed to segregate according to simple Mendelian ratios. Segregation bias was evident, in that F2 progeny inherited on average 91 % of maternal bands and 52% of paternal bands, which deviates significantly from the expected value for each of 75% for dominant markers. Because of these distortions, linkage mapping was not possible with this population. Evaluation of two F1s from a second wide cross, reciprocals obtained by normal fertilization, also showed non-Mendelian inheritance of one of three co-dominant RFLPs and five of six isozyme markers, indicating that the method of crossing was probably not responsible for the abnormal segregation patterns in the first cross. Either genetic incompatibility, similar to that of an interspecific cross, or selection of particular genotypes could explain the genetic anomalies reported here.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02221580
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  • 46
    Digitale Medien
    Digitale Medien
    Heterogeneity in intergenic regions of the ribosomal repeat of the pine-blister rustsCronartium flaccidum andPeridermium pini (1996)
    Springer
    Current genetics 29 (1996), S. 388-394 
    Details
    ISSN: 1432-0983
    Schlagwort(e): Cronartium flaccidum ; Pine blister rusts ; Ribosomal intergenic region polymorphism ; RFLP ; HPA analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Mixed aeciospore isolates ofCronartium flaccidum andPeridermium pini were obtained from single-tree infections in Britain, Italy and Greece. The 5.8s ribosomal RNA gene and flanking intergenic transcribed spacer regions ITS 1 and ITS2 were found to be highly similar betweenC. flaccidum andP. pini. Within samples heterogeneity was detected at three nucleotide loci in the ITS1 and at four loci in the ITS2 suggesting that several fungal genotypes may occur at a single infection court. The heterogeneity was confirmed by heteroduplex polymorphism analysis of mixed aeciospore products. RFLP of the ribosomal intergenic spacer region 1 (IGSI) amplified from the same templates indicated limited sequence polymorphism in some copies of this repeated locus. Both the sexual and asexual forms ofC. flaccidum show evidence of sequence polymorphism in two independent, non-coding regions of the ribosomal gene array. Variation appears to be greater in the sexual formC. flaccidum, than in the monoaecious formP. pini.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02208620
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  • 47
    Digitale Medien
    Digitale Medien
    Heterogeneity in intergenic regions of the ribosomal repeat of the pine-blister rusts Cronartium flaccidum and Peridermium pini (1996)
    Springer
    Current genetics 29 (1996), S. 388-394 
    Details
    ISSN: 1432-0983
    Schlagwort(e): Key words  Cronartium flaccidum ; Pine blister rusts ; Ribosomal intergenic region polymorphism ; RFLP ; HPA analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract   Mixed aeciospore isolates of Cronartium flaccidum and Peridermium pini were obtained from single-tree infections in Britain, Italy and Greece. The 5.8s ribosomal RNA gene and flanking intergenic transcribed spacer regions ITS1 and ITS2 were found to be highly similar between C. flaccidum and P. pini. Within samples heterogeneity was detected at three nucleotide loci in the ITS1 and at four loci in the ITS2 suggesting that several fungal genotypes may occur at a single infection court. The heterogeneity was confirmed by heteroduplex polymorphism analysis of mixed aeciospore products. RFLP of the ribosomal intergenic spacer region 1 (IGS1) amplified from the same templates indicated limited sequence polymorphism in some copies of this repeated locus. Both the sexual and asexual forms of C. flaccidum show evidence of sequence polymorphism in two independent, non-coding regions of the ribosomal gene array. Variation appears to be greater in the sexual form C. flaccidum, than in the monoaecious form P. pini.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002940050060
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  • 48
    Digitale Medien
    Digitale Medien
    The charge state of an ion channel controls neutral polymer entry into its pore (1997)
    Springer
    European biophysics journal 26 (1997), S. 471-476 
    Details
    ISSN: 1432-1017
    Schlagwort(e): Key words Ion channel ; Transport ; Polymers ; Hydration ; Water structure ; Alpha hemolysin ; Poly(ethylene glycol)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Physik
    Notizen: Abstract Electrostatic potentials created by fixed or induced charges regulate many cellular phenomena including the rate of ion transport through proteinaceous ion channels. Nanometer-scale pores of these channels also play a critical role in the transport of charged and neutral macromolecules. We demonstrate here that, surprisingly, changing the charge state of a channel markedly alters the ability of nonelectrolyte polymers to enter the channel's pore. Specifically, we show that the partitioning of differently-sized linear nonelectrolyte polymers of ethylene glycol into the Staphylococcus aureus α-hemolysin channel is altered by the solution pH. Protonating some of the channel side chains decreases the characteristic polymer size (molecular weight) that can enter the pore by ∼25% but increases the ionic current by ∼15%. Thus, the “steric” and “electric” size of the channel change in opposite directions. The results suggest that effects due to polymer and channel hydration are crucial for polymer transport through such pores.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002490050101
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  • 49
    Digitale Medien
    Digitale Medien
    Non-Mendelian and skewed segregation of DNA markers in wide crosses of the bean rust fungus, Uromyces appendiculatus (1996)
    Springer
    Current genetics 29 (1996), S. 159-167 
    Details
    ISSN: 1432-0983
    Schlagwort(e): Key words Genetic linkage mapping ; Segregation distortion ; RAPD ; RFLP
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  The inheritance of DNA markers was investigated in 27 F2 progeny from a single F1 hybrid derived from a wide cross in Uromyces appendiculatus. This cross was unusual because asexual spores were used to fertilize sexual fruiting structures. Sixty percent of the DNA markers failed to segregate according to simple Mendelian ratios. Segregation bias was evident, in that F2 progeny inherited on average 91% of maternal bands and 52% of paternal bands, which deviates significantly from the expected value for each of 75% for dominant markers. Because of these distortions, linkage mapping was not possible with this population. Evaluation of two F1s from a second wide cross, reciprocals obtained by normal fertilization, also showed non-Mendelian inheritance of one of three co-dominant RFLPs and five of six isozyme markers, indicating that the method of crossing was probably not responsible for the abnormal segregation patterns in the first cross. Either genetic incompatibility, similar to that of an interspecific cross, or selection of particular genotypes could explain the genetic anomalies reported here.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002940050031
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  • 50
    Digitale Medien
    Digitale Medien
    Sec-dependent preprotein translocation in bacteria (1996)
    Springer
    Archives of microbiology 165 (1996), S. 1-8 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Key wordsEscherichia coli ; ATPase ; Energetics ; Membrane protein ; Protein folding ; Sec Proteins ; Transport
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Translocation of precursor proteins across the cytoplasmic membrane in bacteria is mediated by a multi-subunit protein complex termed translocase, which consists of the integral membrane heterotrimer SecYEG and the peripheral homodimeric ATPase SecA. Preproteins are bound by the cytosolic molecular chaperone SecB and targeted in a complex with SecA to the translocation site at the cytoplasmic membrane. This interaction with SecYEG allows the SecA/preprotein complex to insert into the membrane by binding of ATP to the high affinity nucleotide binding site of SecA. At that stage, presumably recognition and proofreading of the signal sequence occurs. Hydrolysis of ATP causes the release of the preprotein in the translocation channel and drives the withdrawal of SecA from the membrane-integrated state. Hydrolysis of ATP at the low-affinity nucleotide binding site of SecA converts the protein into a compact conformational state and releases it from the membrane. In the absence of the proton motive force, SecA is able to complete the translocation stepwise by multiple nucleotide modulated cycles.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002030050289
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  • 51
    Digitale Medien
    Digitale Medien
    Characterization of Cyanobacteria by SDS-PAGE of whole-cell proteins and PCR/RFLP of the 16S rRNA gene (1997)
    Springer
    Archives of microbiology 168 (1997), S. 176-184 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Key words Cyanobacteria ; Planktonic ; Total protein ; SDS-PAGE ; PCR ; RFLP ; 16S rRNA ; UPGMA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Planktonic, filamentous cyanobacterial strains from different genera, both toxic and nontoxic strains, were characterized by SDS-PAGE of whole-cell proteins and PCR/RFLP of the 16S rRNA gene. Total protein pattern analysis revealed the mutual relationships at the genus level. Restriction fragment length polymorphism (RFLP) of the 16S rRNA gene with reference strains proved to be a good method for the cyanobacterial taxonomy. The nonheterocystous strains outgrouped from the nitrogen-fixing ones. With both methods, Aphanizomenon clustered with Anabaena, and Nodularia with Nostoc. In the RFLP study of Anabaena, the neurotoxic strains were identical, but the hepatotoxic ones formed a heterogeneous group. Genetic distances found in the RFLP study were short, confirming that close genotypic relationships underlie considerable diversity among cyanobacterial genera.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002030050485
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  • 52
    Digitale Medien
    Digitale Medien
    Megaplasmids in Thermus oshimai isolates from two widely separated geographical areas: restriction fragment profiling and DNA homology (1997)
    Springer
    Archives of microbiology 168 (1997), S. 473-479 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Key words Thermus oshimai ; Megaplasmids ; Pulsed-field gel electrophoresis ; RFLP ; Southern ; hybridization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Megaplasmid DNA was detected in ten isolates belonging to the recently described thermophilic eubacterial species Thermus oshimai and isolated from hot springs in Portugal (eight isolates) and Iceland (two isolates). The estimated size of the large plasmids purified from T. oshimai SPS-18 from S. Pedro do Sul, Portugal, and from isolate JK-91 from Hveragerdhi-Hengill, Iceland, was 214 and 275 kb, respectively. No sequence homologous to isolate SPS-18 megaplasmid is present in chromosomal DNA as indicated by Southern hybridization analysis. Overall examination of the HindIII fragment profiles of megaplasmid DNAs purified from isolates from the same geographical area gave similar but not always identical restriction profiles on agarose gels. Restriction fragment length polymorphism (RFLP) was higher for megaplasmids present in isolates purified from the Portuguese and Icelandic isolates than for megaplasmids from the same hot spring. Megaplasmid RFLP correlated with previous results obtained on the polymorphism of macrorestriction patterns of whole genomic DNA and with the RFLP of co-resident small plasmid DNA that was found in one half of the isolates examined. The 16-kb HindIII–HindIII fragment from isolate SPS-18 megaplasmid showed DNA–DNA homology with restriction fragments of similar size generated by the large plasmids present in all the other isolates, even in those from hot springs of widely separated geographical areas. This suggests a high degree of sequence conservation in T. oshimai megaplasmids.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002030050524
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  • 53
    Digitale Medien
    Digitale Medien
    Thiamin biosynthesis in prokaryotes (1999)
    Springer
    Archives of microbiology 171 (1999), S. 293-300 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Key words Thiamin ; Biosynthesis ; Prokaryotes ; Transport ; Kinase ; Mechanism ; Structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Twelve genes involved in thiamin biosynthesis in prokaryotes have been identified and overexpressed. Of these, six are required for the thiazole biosynthesis (thiFSGH, thiI, and dxs), one is involved in the pyrimidine biosynthesis (thiC), one is required for the linking of the thiazole and the pyrimidine (thiE), and four are kinase genes (thiD, thiM, thiL, and pdxK). The specific reactions catalyzed by ThiEF, Dxs, ThiDM, ThiL, and PdxK have been reconstituted in vitro and ThiS thiocarboxylate has been identified as the sulfur source. The X-ray structures of thiamin phosphate synthase and 5-hydroxyethyl-4-methylthiazole kinase have been completed. The genes coding for the thiamin transport system (thiBPQ) have also been identified. Remaining problems include the cloning and characterization of thiK (thiamin kinase) and the gene(s) involved in the regulation of thiamin biosynthesis. The specific reactions catalyzed by ThiC (pyrimidine formation), and ThiGH and ThiI (thiazole formation) have not yet been identified.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002030050713
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  • 54
    Digitale Medien
    Digitale Medien
    Magnesium transport in prokaryotes (1999)
    Springer
    JBIC 4 (1999), S. 523-527 
    Details
    ISSN: 1432-1327
    Schlagwort(e): Key words Magnesium ; Transport ; Prokaryotes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract  Possessing the largest hydrated radius, the smallest ionic radius, and the highest charge density among the biologically relevant cations, Mg2+ provides an interesting problem for transport into living cells. Transport systems for Mg2+ have been characterized primarily in Salmonella typhimurium because the well-developed genetics of Gram-negative bacteria make cloning and studying the transporters a viable proposition. The CorA transport system is expressed constitutively and is the major Mg2+ transporter in Eubacteria and Archaea. It has three transmembrane domains, a uniquely large periplasmic domain, and no sequence homology to other proteins. The MgtE Mg2+ transporter also lacks sequence homology to other proteins, and it is unclear if Mg2+ transport is its primary function. The MgtA and MgtB Mg2+ transporters have sequence homology to P-type ATPases. They are more closely related to the mammalian Ca2+–ATPases than to the prokaryotic P-type ATPases. MgtA and MgtB mediate Mg2+ influx with, rather than against, the Mg2+ electrochemical gradient. Unlike corA and mgtE, the mgtA and mgtC/mgtB loci are regulated, being induced by the two-component regulatory system PhoP/PhoQ. PhoQ is a Mg2+ membrane sensor kinase that phosphorylates the transcription factor PhoP under Mg2+–limiting conditions. This factor then induces transcription of mgtA and mgtCB. MgtC, which is encoded by the first gene in the mgtCB operon, has no sequence homology to any known protein and is essential for S. typhimurium virulence in mice and macrophages, but does appear to be a Mg2+ transporter. The physiological roles of these Mg2+ transporters and their mechanisms are not yet completely clear, but initial data indicate that Mg2+ transporters are unique transport systems with unusual mechanisms for mediating Mg2+ movement through the membrane.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s007750050374
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  • 55
    Digitale Medien
    Digitale Medien
    The transport kinetics of lanthanide species in a single erythrocyte probed by confocal laser scanning microscopy (1999)
    Springer
    JBIC 4 (1999), S. 447-456 
    Details
    ISSN: 1432-1327
    Schlagwort(e): Key words Lanthanide ; Erythrocyte ; Transport ; Confocal laser scanning microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract  A novel method has been developed to visualize and follow the temporal course of lanthanide transport across the membrane into a single living erythrocyte. By means of confocal scanning microscopy and the optical section technique, the entry of lanthanide ions was followed by the fluorescence quenching of fluorescein isothiocyanate (FITC)-labeled membrane and cytosol. From the difference of the quenching kinetics of the whole section and the central area, the time for diffusion through the membrane and the diffusion in the extracellular and intracellular media can be deduced. To clarify the mechanism of lanthanide-induced fluorescence quenching of FITC-labeled erythrocytes and to ensure that this reaction can be used in this method, the reaction was investigated by steady-state fluorescence techniques. The results showed that the lanthanides strongly quenched the florescence emitted by FITC covalently bound to membrane proteins and cytosolic proteins. The static quenching mechanism is responsible for the fluorescence quenching of FITC-labeled proteins by Ln species. The quenching mechanism is discussed on the basis of complex formation. The dependence of fluorescence quenching on both ion size and the total orbital angular momentum L supports the complexation mechanism. The transport time across the membrane is strikingly correlated with Ln species and extracellular concentration. For a given concentration, the transport time of [Ln(cit)2]3– is much shorter than that of Ln3+, since they enter the cells via the anion channel. This is supported by the inhibition effect of 4,4′-diisothiocyanato-2,2′-stilbenendisulfonate on the transport of [Ln(cit)2]3–. On the other hand, the transport of free Ln3+ might be attributed to the enhanced permeability of erythrocytes owing to Ln3+ binding. These findings strongly demonstrate the existence of the non-internalization mechanism of Ln species uptake by erythrocytes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s007750050331
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  • 56
    Digitale Medien
    Digitale Medien
    Opportunities for materials modeling in microelectronics: Programmed rate chemical vapor deposition (1999)
    Springer
    Journal of computer-aided materials design 6 (1999), S. 283-309 
    Details
    ISSN: 1573-4900
    Schlagwort(e): Aluminum ; Growth ; Nucleation ; Predictive process engineering ; Reaction ; Semiconductor processing ; Thin films ; Transport ; Tungsten
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Two case studies are presented in order to highlight the status of materials modeling in semiconductor materials processing, as well as some opportunities in the area. Both case studies involve programmed rate chemical vapor deposition (PRCVD), which is a CVD process in which conditions are systematically changed during deposition in order to enhance either processing properties or resulting film properties. In the tungsten study, quantitative simulations, based on fundamental transport and reaction modeling and a continuum film representation, are used to guide experiments that demonstrate how PRCVD can provide significantly greater throughput than conventional, constant rate CVD (CRCVD). We start the deposition process at a much higher temperature, compared to a CRCVD process, then decrease the temperature during deposition. We achieve throughput increases of about a factor of three, with more improvement clearly obtainable. In addition to the increase in throughput, the properties of the PRCVD films are equal to, or superior to, CRCVD films. The aluminum PRCVD case study demonstrates some opportunities for materials modeling. The protocols used are based upon qualitative models of nucleation and film growth, as there are no simulators that predict microstructure and film properties. Nevertheless, we demonstrate that the PRCVD processes, designed using qualitative models, can yield films with better properties than CRCVD processes. PRCVD films can have higher nuclei densities, higher fractions of (111) orientated Al, lower surface roughnesses, higher reflectivities, and resistivities closer to that of bulk aluminum. In general, PRCVD protocols provide degrees of freedom that can be used to improve processing or film properties. PRCVD may become much more important as films get thinner and interfaces become more important.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008762530690
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  • 57
    Digitale Medien
    Digitale Medien
    Lithium ion transport in a model of amorphous polyethylene oxide (1996)
    Springer
    Journal of computer-aided materials design 3 (1996), S. 385-402 
    Details
    ISSN: 1573-4900
    Schlagwort(e): Lithium ; Polyethylene oxide ; Batteries ; Transport
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Summary We have made a molecular dynamics study of transport of a single lithium ion in a previously reported model of amorphous polyethylene oxide. New ab initio calculations of the interaction of the lithium ion with 1,2-dimethoxyethane and with dimethyl ether are reported which are used to determine force fields for the simulation. We report preliminary calculations of solvation energies and hopping barriers and a calculation of the ionic conductivity which is independent of any assumptions about the mechanism of ion transport. We also report some details of a study of transport of the trapped lithium ion on intermediate time and length scales.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01185677
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  • 58
    Digitale Medien
    Digitale Medien
    On momentum flux and velocity spectra over waves (1999)
    Springer
    Boundary layer meteorology 92 (1999), S. 489-515 
    Details
    ISSN: 1573-1472
    Schlagwort(e): Air-sea fluxes ; Wind stress ; Wind waves ; Swell ; Universal spectra ; Monin--Obukhov theory
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract Data from a research tower in Lake Ontario are used to study the validity of Monin--Obukhov scaling in the marine atmospheric boundary layer under various wave conditions. It is found that over pure wind seas, the velocity spectra and cospectra follow established universal scaling laws. However, in the presence of swells outrunning weak winds, velocity spectra and cospectra no longer satisfy universal spectral shapes. Here, Monin–Obukhov similarity theory, and the classical logarithmic boundary layers, are no longer valid. It is further shown that, in the presence of such swells, the momentum flux can be significantly modified in comparison to pure wind sea values. The implications of these findings for bulk flux estimations and on the inertial dissipation method for calculating fluxes are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1002054820455
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  • 59
    Digitale Medien
    Digitale Medien
    Wind Stress Structure in the Unstable Marine Surface Layer Detected by Sar (1998)
    Springer
    Boundary layer meteorology 86 (1998), S. 1-28 
    Details
    ISSN: 1573-1472
    Schlagwort(e): Wind stress ; Synthetic Aperture Radar ; Marine surface layer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The wind stress in the marine surface layer under unstable conditions and low wind speed has been studied using a Synthetic Aperture Radar (SAR) image of the sea surface and time series of the horizontal and vertical wind velocities and of the wind stress recorded on board the C.N.R. research platform, in the northern Adriatic Sea, during a SAR overflight. A conditional sampling technique has been used on the wind stress time series and on the SAR image to detect downward (sweep) and upward (ejection) bursts of the momentum flux, as well as the two-dimensional structure of the radar backscatter. From the ensemble average of both the wind stress and the backscatter structures, it has been possible to estimate the mean duration of the upward (≈11 s) and the downward (≈15 s) wind stress bursts and the mean size of the bright patches of the SAR image (≈120 m). The front of the mean backscatter structure, associated with the downward wind stress bursts, has been related to the time length of the mean sweep stress structure to get, after accounting for a threshold of the wind stress for the generation of the sea surface wavelets, the translation velocity Ut of the mean wind stress of sweep, very close to the mean wind speed. The vertical coherence of the wind stress structures has permited to refer the translation velocity to a level very close to the sea surface, but above the viscous sublayer. The variability of Ut with height has been studied through comparison with the mean wind speed at different heights z calculated by a boundary-layer model. Accounting for the results reported in the literature, there is an indication that Ut is constant with height in the range 0.5 m ≤ z ≤ 15 m. The two-dimensional pattern of the wind stress structures has been derived from the SAR image. The structures appear elongated crosswind, as with microfronts, with an average cross- to down-wind ratio of ≈ 4. The area covered by the downward wind stress structures represents 13% of the total area.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1000522423136
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  • 60
    Digitale Medien
    Digitale Medien
    Nucleotide sequence of a major satellite DNA element isolated from a saltwater fishSillago japonica (1995)
    Springer
    Molecular biology reports 22 (1995), S. 33-35 
    Details
    ISSN: 1573-4978
    Schlagwort(e): fish ; repetitive DNA ; RFLP ; satellite DNA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A member of satellite repetitive DNA was isolated and sequenced from a saltwater fishSillago japonica (Percoidei). This sequence consists of several oligo-dA/dT tracts and two inverted repeats which resemble each other. Dot blot hybridization analysis using a satellite DNA clone pSJ2 among the species in the suborder Percoidei revealed that the pSJ2 sequence was amplified at least after the family Sillaginidae had been derived.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00996302
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  • 61
    Digitale Medien
    Digitale Medien
    Chalcone synthase in rice (Oryza sativa L.): Detection of the CHS protein in seedlings and molecular mapping of the chs locus (1996)
    Springer
    Plant molecular biology 32 (1996), S. 735-743 
    Details
    ISSN: 1573-5028
    Schlagwort(e): chalcone synthase cDNA (chs cDNA) ; RFLP ; anthocyanins ; flavonoids ; synteny
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The chalcone synthase is a key enzyme that catalyses the first dedicated reaction of the flavonoid pathway in higher plants. The chs gene and its protein product in rice has been investigated. The presence of a chalcone synthase (CHS) protein in rice seedlings and its developmental stage-specific expression has been demonstrated by western analysis. The chalcone synthase of rice was found to be immunologically similar to that of maize. A rice cDNA clone, Os-chs cDNA, encoding chalcone synthase, isolated from a leaf cDNA library of an indica rice variety Purpleputtu has been mapped to the centromeric region of chromosome 11 of rice. It was mapped between RFLP markers RG2 and RG103. RG2 is the nearest RFLP marker located at a genetic distance of 3.3 cM. Some segments of chromosome 11 of rice including chs locus are conserved on chromosome 4 of maize. The markers, including chs locus on chromosome 11 of rice are located, though not in the same order, on chromosome 4 of maize. Genetic analysis of purple pigmentation in two rice lines, Abhaya and Shyamala, used in the present mapping studies, indicated the involvement of three genes, one of which has been identified as a dominant inhibitor of leaf pigmentation. The Os-chs cDNA shows extensive sequence homology, both for DNA and protein (deduced), to that of maize, barley and also to different monocots and dicots.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00020214
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  • 62
    Digitale Medien
    Digitale Medien
    Aquaporin function, structure, and expression: are there more surprises to surface in water relations? (1998)
    Springer
    Planta 204 (1998), S. 131-139 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Key words: Aquaporin ; Plasma membrane intrinsic protein ; Tonoplast intrinsic protein ; Transport ; Water
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004250050239
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  • 63
    Digitale Medien
    Digitale Medien
    Assessment of the type and degree of restriction fragment length polymorphism (RFLP) in diploid species of the genus Triticum (1995)
    Springer
    Theoretical and applied genetics 90 (1995), S. 1063-1067 
    Details
    ISSN: 1432-2242
    Schlagwort(e): T. monococcum ssp. monococcum ; T. monococcum ssp. boeoticum ; T. urartu ; RFLP ; Diversity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The A genome of the Triticeae is carried by three diploid species and subspecies of the genus Triticum: T. monococcum ssp. monococcum, T. monococcum ssp. boeoticum, and T. urartu, the A-genome donor of bread wheat. These species carry many genes of agronomic interest, including disease resistances, and may also be used for the genetic mapping of the A genome. The aim of this study was to evaluate the variability present in a sample of 25 accessions representative of this group using RFLP markers. Twenty probes, consisting of genomic DNA or cDNA from wheat, were used in combination with four restriction enzymes. A high level of polymorphism was found, especially at the interspecific level. Selecting the most informative enzymes appeared to be of great importance in order to obtain a stable structure for the diversity observed with only 20 probes. The results are largely consistent with taxonomy and data relating to geographical origins. The probes were also tested on 14 wheat cutivars. A good correlation coefficient was found for their informative values on wheat cultivars and diploid lines. Whether the group of species studied here would be useful for genetic mapping remains to be determined. Nevertheless, RFLP markers will be useful to follow genes that can possibly be introgressed from these species into cultivated wheat.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00222922
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  • 64
    Digitale Medien
    Digitale Medien
    Detection of the apomictic mode of reproduction in maize-Tripsacum hybrids using maize RFLP markers (1995)
    Springer
    Theoretical and applied genetics 90 (1995), S. 1198-1203 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Diplospory ; RFLP ; Bulk-segregant analysis ; Genome similarity ; Intergeneric hybrids ; Zea mays
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Polyploid plants in the genus Tripsacum, a wild relative of maize, reproduce through gametophytic apomixis of the diplosporous type, an asexual mode of reproduction through seed. Moving gene(s) responsible for the apomictic trait into crop plants would open new areas in plant breeding and agriculture. Efforts to transfer apomixis from Tripsacum into maize at CIMMYT resulted in numerou intergeneric F1 hybrids obtained from various Tripsacum species. A bulk-segregant analysis was carried out to identify molecular markers linked to diplospory in T. dactyloides. This was possible because of numerous genome similarities among related species in the Andropogoneae. On the basis of maize RFLP probes, three restriction fragments co-segregating with diplospory were identified in one maize-Tripsacum dactyloides F1 population that segregated 1∶1 for the mode of reproduction. The markers were also found to be linked in the maize RFLP map, on the distal end of the long arm of chromosome 6. These results support a simple inheritance of diplospory in Tripsacum. Manipulation of the mode of reproduction in maize-Tripsacum backcross generations, and implications for the transfer of apomixis into maize, are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00222943
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  • 65
    Digitale Medien
    Digitale Medien
    Mapping quantitative trait loci for downy mildew resistance in pearl millet (1995)
    Springer
    Theoretical and applied genetics 91 (1995), S. 448-456 
    Details
    ISSN: 1432-2242
    Schlagwort(e): QTLs ; RFLP ; Pearl millet ; Downy mildew resistance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Quantitative trait loci (QTLs) for resistance to pathogen populations of Scelerospora graminicola from India, Nigeria, Niger and Senegal were mapped using a resistant x susceptible pearl millet cross. An RFLP map constructed using F2 plants was used to map QTLs for traits scored on F4 families. QTL analysis was carried out using the interval mapping programme Mapmaker/QTL. Independent inheritance of resistance to pathogen populations from India, Senegal, and populations from Niger and Nigeria was shown. These results demonstrate the existence of differing virulences in the pathogen populations from within Africa and between Africa and India. QTLs of large effect, contributing towards a large porportion of the variation in resistance, were consistently detected in repeated screens. QTLs of smaller and more variable effect were also detected. There was no QTLs that were effective against all four pathogen populations, demonstrating that pathotype-specific resistance is a major mechanism of downy mildew resistance in this cross. For all but one of the QTLs, resistance was inherited from the resistant parent and the inheritance of resistance tended to be the result of dominance or over-dominance. The implications of this research for pearl millet breeding are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00222972
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  • 66
    Digitale Medien
    Digitale Medien
    Identification of a RAPD marker for palmitic-acid concentration in the seed oil of spring turnip rape (Brassica rapa ssp. oleifera) (1995)
    Springer
    Theoretical and applied genetics 91 (1995), S. 477-480 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Brassica rapa ; RFLP ; RAPD ; QTL ; Palmitic acid
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract F2 progeny (105 individuals) from the cross Jo4002 x Sv3402 were used to identify DNA markers associated with palmitic-acid content in spring turnip rape (Brassica rapa ssp. oleifera). QTL mapping and ANOVA analysis of 140 markers exposed one linkage group with a locus controlling palmitic-acid content (LOD score 27), and one RAPD (random amplified polymorphic DNA) marker, OPB-11a, closely linked (1.4 cM) to this locus. Palmitic-acid content in the 62 F2 plants with the visible allele of marker OPB-11a was 8.45 ±3.15%, while that in the 24 plants without it was 4.59 ±0.97%. As oleic-acid concentration is affected by a locus on the same linkage group as the palmitic-acid locus, this locus probably controls the chain elongation from palmitic acid to oleic acid (through stearic acid). Marker OPB-11a may be used in future breeding programs of spring turnip rape to simplify and hasten the selection for palmitic-acid content.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00222976
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  • 67
    Digitale Medien
    Digitale Medien
    Cytoplasmic DNAs and nuclear rDNA restriction fragment length polymorphisms in commercial witloof chicories (1995)
    Springer
    Theoretical and applied genetics 91 (1995), S. 505-509 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Chloroplast DNA ; Mitochondrial DNA ; rDNA ; RFLP ; Witloof chicory
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Restriction fragment length polymorphisms of cytoplasmic DNAs and nuclear rDNA were analyzed in several Cichorium intybus genotypes, comprising four white inbred lines, eight red witloof experimental lines, and a number of F1 hybrids derived from two white parents. Chloroplast and mitochondrial restriction patterns led to the distinction between two different cytoplasms, called I and II. Southern hybridization using a nuclear rDNA probe revealed that all the lines possessed two types of rDNA repeat units. The shortest unit was 10 kb and was common to all lines. The largest rDNA repeat unit was 10.5 kb in lines I and 10.4 kb in lines II. In addition, a sequence heterogeneity between the 10.5 and 10.4-kb rDNA repeat units was revealed by Sac I digestion. A 10-kb rDNA unit was successively cloned, mapped, and used as a probe to check the genetic purity of F1 hybrid seeds between line I and II white parents. We found a 30% average percentage of impurities, originating both from selfing and full-sib crossing, in different open-pollinated hybrid samples.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00222980
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  • 68
    Digitale Medien
    Digitale Medien
    Genetic mapping of soybean cyst nematode race-3 resistance loci in the soybean PI 437.654 (1995)
    Springer
    Theoretical and applied genetics 91 (1995), S. 574-581 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Glycine max ; Heterodera glycines ; RFLP ; Genetic mapping
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Resistance to the soybean cyst nematode (SCN) (Heterodera glycines Ichinohe) is difficult to evaluate in soybean [Glycine max (L.) Merr.] breeding. PI 437.654 has resistance to more SCN race isolates than any other known soybean. We screened 298 F6∶7 recombinant-inbred lines from a cross between PI 437.654 and ‘BSR101’ for SCN race-3 resistance, genetically mapped 355 RFLP markers and the I locus, and tested these markers for association with resistance loci. The Rhg 4 resistance locus was within 1 cM of the I locus on linkage group A. Two additional QTLs associated with SCN resistance were located within 3cM of markers on groups G and M. These two loci were not independent because 91 of 96 lines that had a resistant-parent marker type on group G also had a resistant-parent marker type on group M. Rhg 4 and the QTL on G showed a significant interaction by together providing complete resistance to SCN race-3. Individually, the QTL on G had greater effect on resistance than did Rhg 4, but neither locus alone provided a degree of resistance much different from the susceptible parent. The nearest markers to the mapped QTLs on groups A and G had allele frequencies from the resistant parent indicating 52 resistant lines in this population, a number not significantly different from the 55 resistant lines found. Therefore, no QTLs from PI 437.654 other than those mapped here are expected to be required for resistance to SCN race-3. All 50 lines that had the PI 437.654 marker type at the nearest marker to each of the QTLs on groups A and G were resistant to SCN race-3. We believe markers near to these QTLs can be used effectively to select for SCN race-3 resistance, thereby improving the ability to breed SCN-resistant soybean varieties.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00223282
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  • 69
    Digitale Medien
    Digitale Medien
    A barley RFLP map: alignment of three barley maps and comparisons to Gramineae species (1995)
    Springer
    Theoretical and applied genetics 91 (1995), S. 681-690 
    Details
    ISSN: 1432-2242
    Schlagwort(e): RFLP ; Barley ; Hordeum vulgare ssp. spontaneum ; Gramineae ; Comparative mapping
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Several gene linkage maps have been produced for cultivated barley. We have produced a new linkage map for barley, based on a cross between Hordeum vulgare subsp. spontaneum and Hordeum vulgare subsp. vulgare (Hvs x Hvv), having a higher level of polymorphism than most of the previous barley crosses used for RFLP mapping. Of 133 markers mapped in the Hvs x Hvv F2 population, 69 were previously mapped on other barley maps, and 26 were mapped in rice, maize, or wheat. Two known gene clones were mapped as well as two morphological markers. The distributions of previously mapped markers were compared with their respective barley maps to align the different maps into one consensus map. The distributions of common markers among barley, wheat, rice and maize were also compared, indicating colinear linkage groups among these species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00223297
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  • 70
    Digitale Medien
    Digitale Medien
    Linkage relationships among stress-induced genes in wheat (1995)
    Springer
    Theoretical and applied genetics 91 (1995), S. 795-801 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Salt stress ; Water deficient ; Heat shock ; Mapping ; Triticeae ; RFLP ; Linkage map
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Linkage relationships among genes responding to water-deficit, salt stress, and heat shock were investigated in diploid wheat, Triticum monococcum L. The position of these gene loci relative to closely linked markers and the centromeres is reported. It is proposed to continue to use the present T. monococcum mapping population and the genetic maps based thereon as a framework for future determination of relationships among other genes related to environmental stress in the tribe Triticeae.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00220962
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  • 71
    Digitale Medien
    Digitale Medien
    Detection of a highly heterozygous locus in recombinant inbred lines of rice and its possible involvement in heterosis (1995)
    Springer
    Theoretical and applied genetics 91 (1995), S. 978-986 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Heterozygosity ; Oryza sativa ; Heterosis ; RFLP ; Recombinant inbred lines
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Forty-seven recombinant inbred (RI) lines derived from a cross between two indica rices, cv ‘Phalguna’ and the Assam land race ARC 6650, were subjected to restriction fragment length polymorphism (RFLP) analysis using cloned probes defining 150 single-copy loci uniformly dispersed on the 12 chromosomes of rice. Of the probes tested, 47 detected polymorphism between the parents. Heterozygosity was calculated for each line and for each of the polymorphic loci. Average heterozygosity per line was 9.6% but was excessive (〉20%) in the 5 lines that seemed to have undergone outcrossing immediately prior to harvest. Average heterozygosity detected by each probe across the 47 RI lines was 9.7%. The majority of probes revealed the low level of heterozygosity (〈8%) expected for F5-F6 lines in a species showing about 5% outbreeding. On the other hand, 7 probes exhibited heterozygosity in excess of 15%, while with a eighth probe (RG2 from chromosome 11) heterozygosity varied according to the restriction enzyme employed, ranging from 2% with SaII to 72% with EcoRV. The presence of 34 recombination sites in a segment of the genome as short as 24 kb indicates a strong selection for recombination between two neighbouring loci, one required as homozygous for the ‘Phalguna’ allele, and the other heterozygous. Since selection was principally for yield advantage over that of the high-yielding parent, ‘Phalguna’, one or both of these loci may be important for heterosis in this cross. The results also indicate that heterozygosity as measured by RFLP can depend on the particular restriction endonuclease employed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00223909
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  • 72
    Digitale Medien
    Digitale Medien
    Mapping quantitative trait loci for seedling vigor in rice using RFLPs (1996)
    Springer
    Theoretical and applied genetics 92 (1996), S. 395-402 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Quantitative trait locus (QTL) ; RFLP ; Seedling vigor ; Shoot growth ; Oryza sauva
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Improving seedling vigor is an important objective of modern rice (Oryza saliva L.) breeding programs. The purpose of this study was to identify and map quantitative trait loci (QTL) underlying seedling vigor-related traits using restriction fragment length polymorphisms (RFLPs). An F2 population of 204 plants was developed from a cross between a low-vigor japonica cultivar ‘Labelle’ (LBL) and a high-vigor indica cultivar ‘Black Gora’ (BG). A linkage map was constructed of 117 markers spanning 1496 Haldane cM and encompassing the 12 rice chromosomes with an average marker spacing of 14 cM. The length of the shoots, roots, coleoptile and mesocotyl were measured on F3 families in slantboard tests conducted at two temperatures (18° and 25°C). By means of interval analysis, 13 QTLs, each accounting for 7% to 38% of the phenotypic variance, were identified and mapped in the two temperature regimes at a log-likelihood (LOD) threshold of 2.5. Four QTLs controlled shoot length, 2 each controlled root and coleoptile lengths and 5 influenced mesocotyl length. Single-point analysis confirmed the presence of these QTLs and detected additional loci for shoot, root and coleoptile lengths, these latter usually accounting for less than 5% of the phenotypic variation. Only 3 QTLs detected both by interval and singlepoint analyses were expressed under both temperature regimes. Additive, dominant and overdominant modes of gene action were observed. Contrary to what was predicted from parental phenotype, the low-vigor LBL contributed 46% of the positive alleles for shoot, root and coleoptile lengths. Positive alleles from the high-vigor parent BG were identified for increased root, coleoptile and mesocotyl lengths. However, BG contributed alleles with only minor effects for shoot length, the most important determinant of seedling vigor in water-seeded rice, suggesting that it would not be an ideal donor parent for introducing faster shoot growth alleles into temperate japonica cultivars.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00223685
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  • 73
    Digitale Medien
    Digitale Medien
    Identification of molecular markers linked to the Agropyron elongatum-derived leaf rust resistance gene Lr24 in wheat (1995)
    Springer
    Theoretical and applied genetics 90 (1995), S. 982-990 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Leaf rust ; RFLP ; RAPD ; Wheat ; Agropyron elongatum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The objective of this study was to identify molecular markers linked to the wheat leaf rust resistance gene Lr24 derived from Agropyron elongatum (3DL/3Ag translocation). Two near isogenic lines (NILs), ‘Arina’ and Lr24/7 * “Arina”, were screened for polymorphism at the DNA level with 115 RFLP probes. Twenty-one of these probes map to the homoeologous group 3. In addition, 360 RAPD primers were tested on the NILs. Six RFLP probes showed polymorphism between the NILs, and 11 RAPD primers detected one additional band in the resistant NIL. The genetic linkage of the polymorphic markers with Lr24 was tested on a segregating F2 population (150 plants) derived from a cross between the leaf rust resistant Lr24/7 * “Arina” and the susceptible spelt (Triticum spelta) variety ‘Oberkulmer’. All 6 RFLP markers were completely linked to Lr24: one was inherited as a codominant marker (PSR1205), one was in coupling phase (PSR1203) and 4 were in repulsion phase (PSR388, PSR904, PSR931, PSR1067) with Lr24. The localization of these probes on chromosome 3D was confirmed by nulli-tetrasomic analysis. Distorted genotypic segregation was found for the Codominant RFLP marker PSR1205. This distortion can be explained by the occurrence of hemizygous plants. One of the 11 RAPD markers (OPJ-09) also showed complete linkage to theLr24 resistance gene. The polymorphic RAPD fragment was cloned and sequenced. Specific primers were synthesized, and they produced an amplification product only in the resistant plants. This specific marker allows a reliable and rapid screening of a large number of genotypes in practical breeding. Analysis of 6 additional lines containing Lr24 revealed that 3 lines have a smaller chromosomal segment of A. elongatum than lines derived from ‘Agent’, a commonly used gene donor for the Lr24 resistance gene.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00222911
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  • 74
    Digitale Medien
    Digitale Medien
    The genetic and molecular characterization of pollen-derived plant lines from octoploid triticale x wheat hybrids (1996)
    Springer
    Theoretical and applied genetics 92 (1996), S. 811-816 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Doubled haploids ; Octoploid triticale ; Wheat ; Wheat/rye translocations ; Wheat/rye addition ; Genomic in situ hybridization (GISH) ; SDS-PAGE ; RFLP
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Six doubled-haploid (DH) lines, derived by anther culture from octoploid triticale x wheat hybrids, were characterized using cytological, biochemical and molecular techniques. Lines varied in their wheat and rye genome composition, and were either wheat-rye chromosome multiple addition lines or had spontaneous substitutions and/or wheat-rye translocations. Most of the lines contained a pair of 4R chromosomes, whereas 1R or 7R were present in others. The results are similar to those previously obtained with hexaploid triticale x wheat crosses and indicate that it is possible to produce alien (wheat/rye) addition, substitution, and translocation lines directly from the anther culture of intergeneric hybrids.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00221892
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  • 75
    Digitale Medien
    Digitale Medien
    The genetic and molecular characterization of pollen-derived plant lines from octoploid triticale × wheat hybrids (1996)
    Springer
    Theoretical and applied genetics 92 (1996), S. 811-816 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words  Doubled haploids ; Octoploid triticale ; Wheat ; Wheat/rye translocations ; Wheat/rye addition ; Genomic in situ hybridization (GISH) ; SDS-PAGE ; RFLP
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract   Six doubled-haploid (DH) lines, derived by anther culture from octoploid triticale × wheat hybrids, were characterized using cytological, biochemical and molecular techniques. Lines varied in their wheat and rye genome composition, and were either wheat-rye chromosome multiple-addition lines or had spontaneous substitutions and/or wheat-rye translocations. Most of the lines contained a pair of 4R chromosomes, whereas 1R or 7R were present in others. The results are similar to those previously obtained with hexaploid triticale × wheat crosses and indicate that it is possible to produce alien (wheat/rye) addition, substitution, and translocation lines directly from the anther culture of intergeneric hybrids.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220050197
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  • 76
    Digitale Medien
    Digitale Medien
    Linkage between RFLP markers and genes affecting kernel hardness in wheat (1996)
    Springer
    Theoretical and applied genetics 93 (1996), S. 580-586 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Kernel hardness ; Wheat ; RFLP ; QTL ; Puroindoline
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A molecular-marker linkage map of wheat (Triticum aestivum L. em. Thell) provides a powerful tool for identifying genomic regions influencing breadmaking quality. A variance analysis for kernel hardness was conducted using 114 recombinant inbred lines (F7) from a cross between a synthetic and a cultivated wheat. The major gene involved in kernel hardness, ha (hard), known to be on chromosome arm 5DS, was found to be closely linked with the locus Xmta9 corresponding to the gene of puroindoline-a. This locus explained around 63% of the phenotypic variability but there was no evidence that puroindoline-a is the product of Ha (soft). Four additional regions located on chromosomes 2A, 2D, 5B, and 6D were shown to have single-factor effects on hardness, while three others situated on chromosomes 5A, 6D and 7A had interaction effects. Positive alleles were contributed by both parents. A three-marker model explains about 75% of the variation for this trait.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00417951
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  • 77
    Digitale Medien
    Digitale Medien
    Genetic localization of four genes for nematode (Heterodera schachtii Schm.) resistance in sugar beet (Beta vulgaris L.) (1996)
    Springer
    Theoretical and applied genetics 92 (1996), S. 991-997 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Sugar beet ; Beta vulgaris ; Nematode resistance ; RFLP ; Genetic maps ; Bulk segregant analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  Sugar beet (Beta vulgaris L.) is highly susceptible to the beet cyst nematode (Heterodera schachtii Schm.). Three resistance genes originating from the wild beets B. procumbens and B. webbiana have been transferred to sugar beet via species hybridization. We describe the genetic localization of the nematode resistance genes in four different sugar beet lines using segregating populations and RFLP markers from our current sugar beet linkage map. The mapping studies yielded a surprising result. Although the four parental lines carrying the wild beet translocations were not related to each other, the four genes mapped to the same locus in sugar beet independent of the original translocation event. Close linkage (0–4.6 cM) was found with marker loci at one end of linkage group IV. In two populations, RFLP loci showed segregation distortion due to gametic selection. For the first time, the non-randomness of the translocation process promoting gene transfer from the wild beet to the sugar beet is demonstrated. The data suggest that the resistance genes were incorporated into the sugar beet chromosomes by non-allelic homologous recombination. The finding that the different resistance genes are allelic will have major implications on future attempts to breed sugar beet combining the different resistance genes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220050220
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  • 78
    Digitale Medien
    Digitale Medien
    Comparative genetic mapping between duplicated segments on maize chromosomes 3 and 8 and homoeologous regions in sorghum and sugarcane (1996)
    Springer
    Theoretical and applied genetics 92 (1996), S. 1024-1030 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Maize ; Sorghum ; Sugarcane ; RFLP ; Synteny
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  Comparative mapping within maize, sorghum and sugarcane has previously revealed the existence of syntenic regions between the crops. In the present study, mapping on the sorghum genome of a set of probes previously located on the maize and sugarcane maps allow a detailed analysis of the relationship between maize chromosomes 3 and 8 and sorghum and sugarcane homoeologous regions. Of 49 loci revealed by 46 (4 sugarcane and 42 maize) polymorphic probes in sorghum, 42 were linked and were assigned to linkage groups G (28), E (10) and I (4). On the basis of common probes, a complete co-linearity is observed between sorghum linkage group G and the two sugarcane linkage groups II and III. The comparison between the consensus sorghum/sugarcane map (G/II/III) and the maps of maize chromosomes 3 and 8 reveals a series of linkage blocks within which gene orders are conserved. These blocks are interspersed with non-homoeologous regions corresponding to the central part of the two maize chromosomes and have been reshuffled, resulting in several inversions in maize compared to sorghum and sugarcane. The results emphasize the fact that duplication will considerably complicate precise comparative mapping at the whole genome scale between maize and other Poaceae.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220050225
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  • 79
    Digitale Medien
    Digitale Medien
    RFLP mapping of QTLs for yield and related characters in rice (Oryza sativa L.) (1996)
    Springer
    Theoretical and applied genetics 92 (1996), S. 920-927 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Oryza sativa L. ; RFLP ; Yield traits ; QTLs
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  Quantitative triat loci (QTLs) for yield and related traits in rice were mapped based on RFLP maps from two indica/indica populations, Tesanai 2/CB and Waiyin 2/CB. In Tesanai 2/CB, 14 intervals carrying QTLs for eight traits were detected, including 3 for grain weight per plant (GWT), 2 for number of panicles per plant (NP), 2 for number of grains per panicle (NG), 1 for total number of spikelets per panicle (TNS), 1 for spikelet fertility (SF), 3 for 1000-grain weight (TGWT), 1 for spikelet density (SD), and 1 for number of first branches per main panicle. The 3 QTLs for GWT were located on chromosomes 1, 2, and 4, with 1 in each chromosome. The additive effect of the single locus ranged from 2.0 g to 9.1 g. A major gene (np4) for NP was detected on chromosome 4 within the interval of RG143-RG214, about 4 cM for RG143, and this locus explained 26.1% of the observed phenotypic variance for NP. The paternal allele of this locus was responsible for reduced panicles per plant (3 panicles per plant). In another population, Waiyin 2/CB, 12 intervals containing QTLs for six of the above-mentioned traits were detected, including 3 for GWT, 2 for each of NP, TNS, TGWT and SD, 1 for SF. Three QTLs for GWT were located on chromosome 1, 4, and 5, respectively. The additive effect of the single locus for GWT ranged from 6.7 g to 8.8 g, while the dominance effect was 1.7–11.5 g. QTL mapping in two populations with a common male parent is compared and discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220050212
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  • 80
    Digitale Medien
    Digitale Medien
    Linkage between RFLP markers and genes affecting kernel hardness in wheat (1996)
    Springer
    Theoretical and applied genetics 93 (1996), S. 580-586 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Kernel hardness ; Wheat ; RFLP ; QTL ; Puroindoline
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A molecular-marker linkage map of wheat (Triticum aestivum L. em. Thell) provides a powerful tool for identifying genomic regions influencing breadmaking quality. A variance analysis for kernel hardness was conducted using 114 recombinant inbred lines (F7) from a cross between a synthetic and a cultivated wheat. The major gene involved in kernel hardness, ha (hard), known to be on chromosome arm 5DS, was found to be closely linked with the locus Xmta9 corresponding to the gene of puroindoline-a. This locus explained around 63% of the phenotypic variability but there was no evidence that puroindoline-a is the product of Ha (soft). Four additional regions located on chromosomes 2A, 2D, 5B, and 6D were shown to have single-factor effects on hardness, while three others situated on chromosomes 5A, 6D and 7A had interaction effects. Positive alleles were contributed by both parents. A three-marker model explains about 75% of the variation for this trait.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220050318
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  • 81
    Digitale Medien
    Digitale Medien
    Comparative QTL mapping of resistance to Ustilago maydis across four populations of European flint-maize (1998)
    Springer
    Theoretical and applied genetics 97 (1998), S. 1321-1330 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Maize ; Ustilago maydis ; QTL mapping ; RFLP ; Resistance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  We mapped and characterized quantitative trait loci (QTLs) for resistance to Ustilago maydis and investigated their consistency across different flint-maize populations. Four independent populations, comprising 280 F3 lines (A×BI), 120 F5 lines (A×BII), 131 F4 lines (A×C) and 133 F4 lines (C×D), were produced from four European elite flint inbreds (A, B, C, D) and genotyped at 89, 151, 104, and 122 RFLP marker loci, respectively. All Fn lines were evaluated in field trials with two replications in five German environments. Genotypic variances were highly significant for the percentage of U. maydis infected plants (UST) in all populations, and heritabilities exceeded 0.69. Between five and ten QTLs were detected in individual populations by composite interval mapping, explaining between 39% and 58% of the phenotypic variance. These 19 different QTLs were distributed over all ten chromosomes without any clustering on certain chromosomes. In most cases, gene action was dominant or overdominant. Fourteen pairs of the detected QTLs for UST displayed significant digenic epistatic interactions, but only two of them did so after arcsin √UST/100 transformation. Significant QTL× environment interactions occurred frequently. Between two to four QTLs were common between pairs of populations. Population C×D was also grown in Chartres, a location with a high U. maydis incidence. Two out of six QTLs identified for Chartres were in common with QTLs detected across five German environments for C×D. Consequently, marker-assisted or phenotypic selection based on results from natural infection seem to be suitable breeding strategies for improving the resistance of maize to U. maydis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220051025
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  • 82
    Digitale Medien
    Digitale Medien
    Inter- and intra-genomic homology of the Brassica genomes: implications for their origin and evolution (1996)
    Springer
    Theoretical and applied genetics 93 (1996), S. 1225-1233 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Brassica rapa ; B. oleracea ; B. nigra ; Genome homology ; RFLP ; Linkage maps
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In order to determine the homologous regions shared by the cultivated Brassica genomes, linkage maps of the diploid cultivated B. rapa (A genome, n = 10), B. nigra (B genome, n = 8) and B. oleracea (C genome, n = 9), were compared. We found intergenomic conserved regions but with extensitve reordering among the genomes. Eighteen linkage groups from all three species could be associated on the basis of homologous segments based on at least three common markers. Intragenomic homologous conservation was also observed for some of the chromosomes of the A, B and C genomes. A possible chromosome phylogenetic pathway based on an ancestral genome of at least five, and no more than seven chromosomes, was drawn from the chromosomal inter-relationships observed. These results demonstrate that extensive duplication and rearrangement have been involved in the formation of the Brassica genomes from a smaller ancestral genome.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00223454
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  • 83
    Digitale Medien
    Digitale Medien
    Ribosomal DNA variation in foxtail millet, Setaria italica (L.) P. Beauv., and a survey of variation from Europe and Asia (1997)
    Springer
    Theoretical and applied genetics 95 (1997), S. 751-756 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Foxtail millet ; rDNA ; RFLP ; Restriction mapping ; Geographical distribution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  Restriction fragment length polymorphism (RFLP) and the structure of ribosomal RNA genes (rDNA) were investigated in 117 landraces of foxtail millet, Setaria italica (L.) P. Beauv. Five RFLP phenotypes were found when the genomic DNA was digested with BamHI; these were named types I–V. Of these types I, II and III were the most frequent. Type I was mainly distributed in the temperature zone, type II in the Taiwan-Philippines Islands and type III in South Asia. Restriction mapping of the cloned rDNA and comparison with RFLP phenotypes showed that the different types originated from a polymorphism in the length within the intergenic spacer (IGS) and BamHI site changes within the IGS.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220050621
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  • 84
    Digitale Medien
    Digitale Medien
    Phylogenetic analysis of Acacia (Mimosaceae) as revealed from chloroplast RFLP data (1999)
    Springer
    Theoretical and applied genetics 98 (1999), S. 291-298 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words DNA ; Molecular evolution ; Parsimony ; PAUP ; Phylogeny ; RFLP
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  Chloroplast DNA of 22 species of Acacia (Tourn.) Miller was digested with ten restriction endonucleases, Southern-blotted and probed with cloned fragments covering the chloroplast genome of tobacco (Nicotiana tabacum L.). Phyletic and phenetic analyses of the resulting 176 polymorphic bands recorded among the 22 species were performed. The phylogram was reconstructed using heuristic search and Wagner parsimony. The resulting most parsimonious consensus phylogram displayed three major phyletic lineages, consistent with the previously established three subgenera of Acacia. The 10 species of subgenus Acacia and the 6 species of subgenus Heterophyllum formed two monophyletic sister clades. The 5 species of subgenus Aculeiferum studied and Acacia albida (Syn. Faidherbia albida) grouped together and were basal to the clades of subgenera Acacia and Heterophyllum. The phylogram indicated that subgenus Heterophyllum diverged earlier from subgenus Aculeiferum than did subgenus Acacia; however, the phenogram indicated the reverse. The study indicated that A. nilotica and A. farnesiana are sister species, though A. nilotica is Afro-Asiatic and A. farnesiana is American. The phenogram separated the three subgenera in agreement with the phylogram, but the two dendrograms differed regarding the topologies of the species and the distance of evolution between subgenera Acacia and Heterophyllum.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220051071
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  • 85
    Digitale Medien
    Digitale Medien
    Mapping of Ve in tomato: a gene conferring resistance to the broad-spectrum pathogen, Verticillium dahliae race 1 (1999)
    Springer
    Theoretical and applied genetics 98 (1999), S. 315-319 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Linkage analysis ; Mapping populations ; Introgression Lines ; RFLP ; Host range
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  The soil-borne fungi Verticillium spp. cause vascular wilt disease in a wide range of crop plants. In tomato, resistance to Verticillium dahliae race 1 is conferred by a single dominant gene, Ve. Previous efforts to map Ve in tomato have yielded confusing results, locating it on different chromosomes, which subsequently raised the possibility that Verticillium resistance may be controlled by a number of loci. We used three different mapping populations to obtain an unambiguous map location of Ve: a recombinant inbred (RI) line population; an F2 population segregating for Verticillium resistance; and a population of 50 introgression lines (IL). In all of the mapping populations Ve was positioned on the short arm of chromosome 9 tightly linked to the RFLP marker GP39. This linkage was confirmed by screening for GP39 in different breeding lines with known resistance or susceptibility to Verticillium. A perfect match was found between GP39 and the Verticillium response of the lines, indicating the potential of GP39 in the rapid detection of Verticillium resistance and as a starting point for map-based cloning of Ve. This approach is particularly relevant for Verticillium dahliae race 1, since in the present work we also show that the isolate that infects tomato is responsible for wilt disease in other important crop plants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220051075
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  • 86
    Digitale Medien
    Digitale Medien
    Comparative molecular mapping of GA insensitive Rht loci on chromosomes 4B and 4D of common wheat (Triticum aestivum L.) (1997)
    Springer
    Theoretical and applied genetics 95 (1997), S. 1133-1137 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Comparative genetic mapping ; Dwarfing genes ; GA insensitivity ; Microsatellites ; RFLP ; Wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  The two GA-insensitive dwarfing gene loci Rht-B1 and Rht-D1 were mapped using three F2 populations, segregating for Rht-B1c (Rht3), Rht-D1b (Rht2) or Rht-D1c (Rht10). Rht-B1c was mapped on chromosome 4BS in the centromere region, distal and closely linked to the RFLP markers Xpsr144 (11.9 cM) and Xpsr584 (17.8 cM), but proximal to Xmwg634 (30 cM). Rht-D1c, however, was found to be closely linked to the distally located markers Xpsr921 (0.8 cM) and Xmwg634 (1.5 cM). The homoeologous relationships between the GA-insensitive dwarfing genes within the Triticeae are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220050673
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  • 87
    Digitale Medien
    Digitale Medien
    A genetic linkage map of cowpea (Vigna unguiculata) developed from a cross between two inbred, domesticated lines (1997)
    Springer
    Theoretical and applied genetics 95 (1997), S. 1210-1217 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Vigna unguiculata ; RFLP ; RAPD ; AFLP ; Linkage map
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  We have constructed a genetic linkage map within the cultivated gene pool of cowpea (2n=2x=22) from an F8 recombinant inbred population (94 individuals) derived from a cross between the inbreds IT84S-2049 and 524B. These breeding lines, developed in Nigeria and California, show contrasting reactions against several pests and diseases and differ in several morphological traits. Parental lines were screened with 332 random RAPD decamers, 74 RFLP probes (bean, cowpea and mung bean genomic DNA clones), and 17 AFLP primer combinations. RAPD primers were twice as efficient as AFLP primers and RFLP probes in detecting polymorphisms in this cross. The map consists of 181 loci, comprising 133 RAPDs, 19 RFLPs, 25 AFLPs, three morphological/classical markers, and a biochemical marker (dehydrin). These markers identified 12 linkage groups spanning 972 cM with an average distance of 6.4 cM between markers. Linkage groups ranged from 3 to 257 cM in length and included from 2 to 41 markers, respectively. A gene for earliness was mapped on linkage group 2. Seed weight showed a significant association with a RAPD marker on linkage group 5. This map should facilitate the identification of markers that “tag” genes for pest and disease resistance and other traits in the cultivated gene pool of cowpea.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220050683
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  • 88
    Digitale Medien
    Digitale Medien
    Genetic linkage map of a wheat×spelt cross (1999)
    Springer
    Theoretical and applied genetics 98 (1999), S. 1163-1170 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key wordsTriticum aestivum ; Triticum spelta ; RFLP ; Genetic map ; QTL
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  We constructed a genetic map of a cross between the Swiss winter wheat (Triticum aestivum L.) variety Forno and the Swiss winter spelt (Triticum spelta L.) variety Oberkulmer. For the linkage analysis,176 polymorphic RFLP probes and nine microsatellites were tested on 204 F5 recombinant inbred lines (RILs) of Forno×Oberkulmer revealing 242 segregating marker loci. Thirty five percent of these loci showed significant (P〉0.05) deviation from a 1 : 1 segregation, and the percentage of Forno alleles ranged from 21% to 83% for individual marker loci. Linkage analysis was performed with the program MAPMAKER using the Haldane mapping function. Using a LOD threshold of 10, we obtained 37 linkage groups. After finding the best order of marker loci within linkage groups by multi-point analysis we assembled the linkage groups into 23 larger units by lowering the LOD threshold. All except one of the 23 new linkage groups could be assigned to physical chromosomes or chromosome arms according to hybridisation patterns of nulli-tetrasomic lines of Chinese Spring and published wheat maps. This resulted in a genetic map comprising 230 marker loci and spanning 2469 cM. Since the analysed population is segregating for a wide range of agronomically important traits, this genetic map is an ideal basis for the identification of quantitative trait loci (QTLs) for these traits.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220051181
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  • 89
    Digitale Medien
    Digitale Medien
    Construction of RFLP-based maps of foxtail millet, Setaria italica (L.) P. Beauv. (1998)
    Springer
    Theoretical and applied genetics 96 (1998), S. 31-36 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Foxtail millet ; Genetic map ; Primary trisomics ; RFLP ; Setaria italica ; Setaria viridis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  An RFLP-based map consisting of 160 loci was constructed in an intervarietal cross of foxtail millet [Setaria italica (L.) P. Beauv.], Longgu 25×Pagoda Flower Green. The map comprises nine linkage groups, which were aligned with the nine foxtail millet chromosomes using trisomic lines, and spans 964 cM. The intraspecific map was compared to an interspecific map, constructed in a S. italica×S. viridis cross. Both the order of the markers and the genetic distances between the loci were highly conserved. Deviations from the expected 1 : 2 : 1 Mendelian segregation ratios were observed in both the intra- and inter-specific populations. The segregation data indicate that chromosome VIII in the Longgu 25×Pagoda Flower Green cross carries a gene that strongly affects gamete fertility.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220050705
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  • 90
    Digitale Medien
    Digitale Medien
    Organization of an Arabidopsis thaliana gene cluster on chromosome 4 including the RPS2 gene, in the Brassica nigra genome (1998)
    Springer
    Theoretical and applied genetics 96 (1998), S. 468-474 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Microsynteny ; Genome ; Gene cluster ; RFLP ; PFGE
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  Genetic and physical maps, consisting of a large number of DNA markers for Arabidopsis thaliana chromosomes, represent excellent tools to determine the organization of related genomes such as those of Brassica. In this paper we report the chromosomal localization and physical analysis by pulsed-field gel electrophoresis (PFGE) of a well-defined gene complex of A. thaliana in the Brassica nigra genome (B genome n=8). This complex is approximately 30 kb in length in A. thaliana and contains a cluster of six genes including ABI1 (ABA-responsive), RPS2 (resistance against Pseudomonas syringae, a bacterial disease), CK1 (casein kinase I), NAP (nucleosome-assembly protein), X9 and X14 (both of unknown function). The Arabidopsis chromosomal complex was found to be duplicated and conserved in gene number at different levels in the Brassica genome. Linkage group B1 had the most-conserved arrangement carrying all six genes tightly linked. Group B4 had an almost complete complex except for the absence of RPS2. Other partial complexes of fewer members were found on three other chromosomes. Our studies demonstrate that by this approach it is possible to identify ancestrally related chromosome segments in a complex and duplicated genome, such as the genome of B. nigra, permitting one to draw conclusions as to its origin and evolution.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220050763
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  • 91
    Digitale Medien
    Digitale Medien
    QTL mapping of resistance to Sporisorium reiliana in maize (1999)
    Springer
    Theoretical and applied genetics 99 (1999), S. 593-598 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Keywords Maize ; Head smut ; Sporisorium reiliana ; QTL ; RFLP ; Ustilago maydis ; Puccinia sorghi
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  We mapped and characterized quantitative trait loci (QTL) for resistance to Sporisorium reiliana. A population of 220 F3 families produced from the cross of two European elite inbreds (D32, D145) was evaluated with two replications at a French location with high natural incidence of S. reiliana and at a Chinese location employing artificial inoculation. The 220 F3 families were genotyped with 87 RFLP and seven SSR markers. Using composite interval mapping, we identified two different sets of 3 and 8 QTL for the French and the Chinese locations explaining 13% and 44% of respectively. Individual QTL explained up to 14% of σ^2 p. The 11 QTL mapped to eight maize chromosomes and displayed mostly additive or partial dominant gene action. Significant digenic epistatic interactions were detected for one pair of these QTL. Only a few QTL for S. reiliana were in common with QTL for resistance to Ustilago maydis and Puccinia sorghi, identified at a German location for the same population. Consequently, in our materials resistance to these three fungal pathogens of maize seems to be inherited independently.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220051273
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  • 92
    Digitale Medien
    Digitale Medien
    RFLP mapping of BaYMV resistance gene rym3 in barley (Hordeum vulgare) (1999)
    Springer
    Theoretical and applied genetics 99 (1999), S. 727-732 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Hordeum vulgare ; BaYMV ; Resistance gene ; RFLP ; Mapping
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  The rym3 (formerly designated ym3) gene conferring resistance to barley yellow mosaic virus (BaYMV) is effective against all strains of the virus but up to now has not been mapped to any chromosome. We performed a linkage analysis, using DNA extracted from individually harvested mature leaves of 153 F2 plants derived from a cross between BaYMV-resistant cv ’Ishuku Shirazu’ carrying rym3 and susceptible cv ’Ko A’. Additionally, the F3 lines derived from F2 plants were grown in the BaYMV-infested field and examined for their reaction to BaYMV. Our results indicated that rym3 is located on the short arm of chromosome 5H and flanked by RFLP markers MWG28and ABG705A at distances of 7.2 and 11.7 cM, respectively. The chromosomal configuration estimated by DNA markers around rym3 and the utilization of these molecular markers for pyramiding with the BaYMV resistance genes in barley breeding programs are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220051290
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  • 93
    Digitale Medien
    Digitale Medien
    Molecular phylogeny of mangroves V. Analysis of genome relationships in mangrove species using RAPD and RFLP markers (1998)
    Springer
    Theoretical and applied genetics 97 (1998), S. 617-625 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Mangroves ; Genome relationship ; Phylogeny ; RAPD ; RFLP
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  DNA from pooled leaf samples of 11 true major mangrove, three true minor mangrove, two mangrove associate, two mangrove parasite, three terrestrial and one cultivated species were isolated for the present study. In total, 198 random amplified polymorphic DNAs (RAPDs) and 180 restriction fragment length polymorphism (RFLP) loci were scored by using ten primers and 14 enzyme-probe combinations respectively. The polymorphism observed for these markers revealed a high degree of genetic diversity in mangroves at both inter-specific or inter-generic levels. A dendrogram, constructed after pooling both RAPD and RFLP data, using a similarity index was analysed for genome relationships among these species. The dendrogram showed clustering of all the major mangroves, except for Nypa fruticans (Arecaceae), into one group. All species under the tribe Rhizophorae formed a sub-cluster, to which Xylocarpus granatum was found to be the most closesly related species. The clustering pattern implied that Excoecaria agallocha and Acanthus ilicifolius should be considered as true minor mangroves. The present study also provided molecular data favouring the separation of Avicennia spp. from the Verbenaceae to create a monotypic family the Avicenniaceae. The separation of Viscum orientale into the Viscaceae was also favoured.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220050937
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  • 94
    Digitale Medien
    Digitale Medien
    A genetic linkage map of durum wheat (1998)
    Springer
    Theoretical and applied genetics 97 (1998), S. 721-728 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Durum wheat ; Mapping ; Linkage map ; RFLP ; Morphological markers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  A genetic linkage map of tetraploid wheat [Triticum turgidum (L.) Thell.] was constructed using segregation data from a population of 65 recombinant inbred lines (RILs) derived from a cross between the durum wheat cultivar Messapia and accession MG4343 of T. turgidum (L.) Thell. ssp dicoccoides (Korn.) Thell. A total of 259 loci were analysed, including 244 restriction fragment length polymorphisms (RFLPs), one PCR (polymerase chain reaction) marker (a sequence coding for a LMW (low-molecular-weight) glutenin subunit gene located at the Glu-B3 locus), seven biochemical (six seed-storage protein loci and one isozyme locus) and seven morphological markers. A total of 213 loci were mapped at a LOD≥3 on all 14 chromosomes of the A and B genomes. The total length of the map is 1352 cM and the average distance between adjacent markers is 6.3 cM. Forty six loci could not be mapped at a LOD≥3. A fraction (18.6%) of the markers deviated significantly from the expected Mendelian ratios; clusters of loci showing distorted segregation were found on chromosomes 1B, 3AL, 4AL, 6AL and 7AL. The durum wheat map was compared with the published maps of bread wheat using several common RFLP markers and general features are discussed. The markers detected the known structural rearrangements involving chromosomes 4A, 5A and 7B as well as the translocation between 2B-6B, but not the deletion on 2BS. This map provides a useful tool for analysing and breeding economically important quantitative traits and for marker-assisted selection, as well as for studies of genome organisation in small grain cereal species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220050948
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  • 95
    Digitale Medien
    Digitale Medien
    A molecular genetic map of the long arm of chromosome 6R of rye incorporating the cereal cyst nematode resistance gene, CreR (1998)
    Springer
    Theoretical and applied genetics 97 (1998), S. 1000-1012 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words CCN ; RFLP ; PCR ; Heterodera avenae ; Genetic mapping
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  A genetic map of the long arm of chromosome 6R of rye was constructed using eight homoeologous group-6 RFLP clones and five PCR markers derived from the rye-specific dispersed repetitive DNA family, R173. The map was developed using a novel test-cross F1 (TC-F1) population segregating for resistance to the cereal cyst nematode. Comparisons were made between the map generated with other rye and wheat group-6 chromosome maps by the inclusion of RFLP clones previously mapped in those species. Co-linearity was observed for common loci. This comparison confirmed a dramatic reduction in recombination for chromosome 6R in the TC-F1 population. The CreR locus was included in the linkage map via progeny testing of informative TC-F1 individuals. CreR mapped 3.7 cM distal from the RFLP locus, XksuF37. Comparative mapping should allow the identification of additional RFLP markers more closely linked to the CreR locus.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220050984
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  • 96
    Digitale Medien
    Digitale Medien
    Linkage relationships among molecular markers and storage root traits of carrot (Daucus carota L. ssp. sativus) (1999)
    Springer
    Theoretical and applied genetics 99 (1999), S. 58-64 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Genetic map ; RFLP ; AFLP ; RAPD ; SAMPL ; Daucus carota L. ssp. sativus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  A 109-point linkage map consisting of three phenotypic loci (P 1, Y 2, and Rs), six restriction fragment length polymorphisms (RFLPs), two random amplified polymorphic DNAs (RAPDs), 96 amplified fragment length polymorphisms (AFLPs), and two selective amplification of microsatellite polymorphic loci (SAMPL) was constructed for carrot (Daucus carota L. ssp. sativus; 2n=2x=18). The incidence of polymorphism was 36% for RFLP probes, 20% for RAPD primers, and 42% for AFLP primers. The overall incidence of disturbed segregation was 18%. Linkage relationships at a LOD score of 4.0 and θ=0.25 indicated 11 linkage groups. The total map length was 534.4 cM and the map was clearly unsaturated with markers spaced at 4.9 cM. AFLP P6B15 was 1.7 cM from P 1, AFLP P1B34 was 2.2 cM from Y 2, and AFLP P3B30XA was 8.1 cM from Rs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220051208
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  • 97
    Digitale Medien
    Digitale Medien
    Genetic localization of four genes for nematode (Heterodera schachtii Schm.) resistance in sugar beet (Beta vulgaris L.) (1996)
    Springer
    Theoretical and applied genetics 92 (1996), S. 991-997 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Sugar beet ; Beta vulgaris ; Nematode resistance ; RFLP ; Genetic maps ; Bulk segregant analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Sugar beet (Beta vulgaris L.) is highly susceptible to the beet cyst nematode (Heterodera schachtii Schm.). Three resistance genes originating from the wild beets B. procumbens (Hs1 pro-1) and B. webbiana (Hs1 web-1, Hs2 web-7) have been transferred to sugar beet via species hybridization. We describe the genetic localization of the nematode resistance genes in four different sugar beet lines using segregating F2 populations and RFLP markers from our current sugar beet linkage map. The mapping studies yielded a surprising result. Although the four parental lines carrying the wild beet translocations were not related to each other, the four genes mapped to the same locus in sugar beet independent of the original translocation event. Close linkage (0–4.6 cM) was found with marker loci at one end of linkage group IV. In two populations, RFLP loci showed segregation distortion due to gametic selection. For the first time, the non-randomness of the translocation process promoting gene transfer from the wild beet to the sugar beet is demonstrated. The data suggest that the resistance genes were incorporated into the sugar beet chromosomes by non-allelic homologous recombination. The finding that the different resistance genes are allelic will have major implications on future attempts to breed sugar beet combining the different resistance genes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00224039
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
    Digitale Medien
    Digitale Medien
    A putative major gene for rust resistance linked with a RFLP marker in sugarcane cultivar ‘R570’ (1996)
    Springer
    Theoretical and applied genetics 92 (1996), S. 1059-1064 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Major gene ; Polyploidy ; Puccinia melanocephala ; Sugarcane ; RFLP ; Rust
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Inheritance of resistance to rust was investigated in the self progeny of the sugarcane cultivar ‘R570’ also used to build a RFLP genetic map. Resistance was evaluated through both field and controlled greenhouse trials. A clear-cut 3 (resistant) ∶ 1 (susceptible) segregation indicative of a probable dominant resistant gene was observed. This is the first documented report of a monogenic inheritance for disease resistance in sugarcane. This gene was found linked at 10 cM with an RFLP marker revealed by probe CDSR29. Other minor factors involved in the resistance were also detected.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00224049
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  • 99
    Digitale Medien
    Digitale Medien
    An integrated genetic linkage map for eucalypts using RFLP, RAPD and isozyme markers (1995)
    Springer
    Theoretical and applied genetics 91 (1995), S. 869-875 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Genetic map ; Linkage ; Eucalypts ; RFLP ; RAPD
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract An integrated genetic linkage map for E. nitens was constructed in an outbred three-generation pedigree. Analysis of 210 RFLP, 125 RAPD and 4 isozyme loci resulted in 330 markers linked in 12 linkage groups covering 1462 cM (n=11 in eucalypts). The 12th linkage group is comprised of only 5 markers and will probably coalesce with another linkage group when further linked loci are located. Co-dominant RFLP loci segregating in both parents were used to integrate linkages identified in the male and female parents. Differences in recombination frequencies in the two parents were observed for a number of pairs of loci, and duplication of sequences was identified both within and between linkage groups. The markers were distributed randomly across the genome except for the RFLPs in linkage group 10 and for some loci showing segregation distortion, which were clustered into three regions of the map. The use of a large number of co-dominant RFLP loci in this map enables it to be used in other pedigrees of E. nitens and forms a basis for the detection and location of QTL in E. nitens and other eucalypt species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00223894
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  • 100
    Digitale Medien
    Digitale Medien
    Restriction fragment length polymorphism detected by cDNA and genomic DNA clones in Stylosanthes (1995)
    Springer
    Theoretical and applied genetics 91 (1995), S. 1210-1213 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Stylosanthes ; DNA isolation ; RFLP
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A DNA isolation method suitable for genomic library construction and RFLP analyses of the forage legume Stylosanthes was developed. Probes isolated using this method were used to investigate the feasibility of constructing RFLP-based genetic maps in this genus. Two hundred and seventy-one PstI genomic DNA and 134 cDNA clones were analysed against four Stylosanthes accessions, including two tetraploids and two diploids, with the use of two restriction enzymes, DraI and HindIII. The proportion of clones which detected single-copy sequences from the PstI genomic library was higher than that from the cDNA library, but the percentage of clones which detected low-copy sequences was doubled in the latter. There was no significant difference in the level of RFLPs detected by gDNA and cDNA probes, although the level of polymorphism was lower in the diploids. A large proportion of RFLPs seemed to have resulted from mutation/base substitution events, and this was especially the case in diploids.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00220931
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