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  • American Physical Society  (60.609)
  • Blackwell Publishing Ltd  (25.582)
  • Cell Press  (20.108)
  • National Academy of Sciences  (13.796)
  • 1995-1999  (120.095)
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  • 1
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    Light intensity regulation of cab gene transcription is signaled by the redox state of the plastoquinone pool. (1995)
    National Academy of Sciences
    In:  PNAS Proceedings of the National Academy of Sciences of the United States of America, 92 (22). pp. 10237-10241.
    Details
    Publikationsdatum: 2016-11-14
    Beschreibung: The eukaryotic green alga Dunaliella tertiolecta acclimates to decreased growth irradiance by increasing cellular levels of light-harvesting chlorophyll protein complex apoproteins associated with photosystem II (LHCIIs), whereas increased growth irradiance elicits the opposite response. Nuclear run-on transcription assays and measurements of cab mRNA stability established that light intensity-dependent changes in LHCII are controlled at the level of transcription. cab gene transcription in high-intensity light was partially enhanced by reducing plastoquinone with 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU), whereas it was repressed in low-intensity light by partially inhibiting the oxidation of plastoquinol with 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB). Uncouplers of photosynthetic electron transport and inhibition of water splitting had no effect on LHCII levels. These results strongly implicate the redox state of the plastoquinone pool in the chloroplast as a photon-sensing system that is coupled to the light-intensity regulation of nuclear-encoded cab gene transcription. The accumulation of cellular chlorophyll at low-intensity light can be blocked with cytoplasmically directed phosphatase inhibitors, such as okadaic acid, microcystin L-R, and tautomycin. Gel mobility-shift assays revealed that cells grown in high-intensity light contained proteins that bind to the promoter region of a cab gene carrying sequences homologous to higher plant light-responsive elements. On the basis of these experimental results, we propose a model for a light intensity signaling system where cab gene expression is reversibly repressed by a phosphorylated factor coupled to the redox status of plastoquinone through a chloroplast protein kinase.
    Materialart: Article , PeerReviewed
    Format: text
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  • 2
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    Bacterial infection as assessed by in vivo gene expression (1997)
    National Academy of Sciences
    In:  PNAS Proceedings of the National Academy of Sciences of the United States of America, 94 (3). pp. 934-939.
    Details
    Publikationsdatum: 2015-08-27
    Beschreibung: In vivo expression technology (IVET) has been used to identify 〉100 Salmonella typhimurium genes that are specifically expressed during infection of BALB/c mice and/or murine cultured macrophages. Induction of these genes is shown to be required for survival in the animal under conditions of the IVET selection. One class of in vivo induced (ivi) genes, iviVI-A and iviVI-B, constitute an operon that resides in a region of the Salmonella genome with low G+C content and presumably has been acquired by horizontal transfer, These ipi genes encode predicted proteins that are similar to adhesins and invasins from prokaryotic and eukaryotic pathogens (Escherichia coli [tia], Plasmodium falciparum [PfEMP1]) and have coopted the PhoPQ regulatory circuitry of Salmonella virulence genes. Examination of the in vivo induction profile indicates (i) many ivi genes encode regulatory functions (e.g., phoPQ and pmrAB) that serve to enhance the sensitivity and amplitude of virulence gene expression (e.g., spvB); (ii) the biochemical function of many metabolic genes may not represent their sole contribution to virulence; (iii) the host ecology can be inferred from the biochemical functions of ipi genes; and (iv) nutrient limitation plays a dual signaling role in pathogenesis: to induce metabolic functions that complement host nutritional deficiencies and to induce virulence functions required for immediate survival and spread to subsequent host sites
    Materialart: Article , PeerReviewed
    Format: text
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  • 3
    Digitale Medien
    Digitale Medien
    Metamorphic evolution of the Susunai metabasites in southern Sakhalin, Russian Republic (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of metamorphic geology 15 (1997), S. 0 
    Details
    ISSN: 1525-1314
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Geologie und Paläontologie
    Notizen: The Susunai Complex of southeast Sakhalin represents a subduction-related accretionary complex of pelitic and basic rocks. Two stages of metamorphism are recognized: (1) a local, low-P/T event characterized by Si-poor calcic amphiboles; (2) a regional, high-P/T event characterized by pumpellyite, actinolite, epidote, sodic amphibole, sodic pyroxene, stilpnomelane and aragonite. The major mineral assemblages of the high-P/T Susunai metabasites contain pumpellyite + epidote + actinolite + chlorite, epidote + actinolite + chlorite, epidote + Na-amphibole + Na-pyroxene + chlorite-(-haematite. The Na-amphibole is commonly magnesioriebeckite. The Na-pyroxene is jadeite-poor aegirine to aegirine-augite. Application of empirically and experimentally based thermobarometers suggests peak conditions of T= 250–300C, P= 4.7–6 kbar. Textural relationships in Susunai metabasite samples and a petrogenetic grid calculated for the Fe3+-rich basaltic system suggest that pressure and temperature increased during prograde metamorphism.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1525-1314.1997.tb00636.x
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  • 4
    Digitale Medien
    Digitale Medien
    Petrological significance of prograde homogenization of growth zoning in garnet: an example from the Llano Uplift (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of metamorphic geology 15 (1997), S. 0 
    Details
    ISSN: 1525-1314
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Geologie und Paläontologie
    Notizen: In the Llano Uplift of central Texas (USA), prograde homogenization of garnet growth zoning took place during moderate-to high-pressure dynamothermal metamorphism over a narrow temperature range near the transition from the amphibolite to the granulite facies. This subtle record of early dynamothermal metamorphism survived subsequent static metamorphism at low pressures in the middle-amphibolite facies, despite the destruction of most high-pressure mineral assemblages that originated in the early metamorphic episode. Geographically systematic variations in the degree of homogenization indicate that the uplift as a whole underwent high-pressure metamorphism, in accord with emerging tectonic models for the mid-Proterozoic evolution of the southern margin of the North American continent.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1525-1314.1997.tb00640.x
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  • 5
    Digitale Medien
    Digitale Medien
    The Role of GIS in Selecting Sites for Riparian Restoration Based on Hyderology and Land Use (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Restoration ecology 5 (1997), S. 0 
    Details
    ISSN: 1526-100X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Successful long-term wetland restoration efforts require consideration of hydrology and currounding land use during the site selection process. This article describes an approach to initial site selection in the San Luis Rey River watershed in southern California that uses watershed-level information on basin topography and land cover to rank the potential suitability of all sites within a watershed for either preservation of restoration. This approach requires the use of a geographic information system (GIS)to map relative wetness and land cover within a watershed. Relative potential wetness values were derived from U.S. Geological Survey (USGS) 30-m digital elevation models by calculating the flow that would potentially accumulate at all 30-m × 30-m pixels within the watershed. Land cover was derived from a Landsat scene covering the 1500 Km2 study area. We ranked sites (contiguous groups of pixels 〉 1 ha with similar land cover) in terms of their potential for restoration or preservation based on their wetness values (Iow, medium, and high), size, and proximity to existing riparian vegetation. Sites with medium or high wetness values and extant vegetation were identified as potential preservation sites. Agiricultural or barren sites with medium to high wetness were identified as potential restoration sites. Approximately 5500 ha (3.67% of the total watershed) were prioritized for preservation or resloration.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1526-100X.1997.tb00205.x
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  • 6
    Digitale Medien
    Digitale Medien
    Riparian Restoration in the Western United States: Oveview and Perspecive (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Restoration ecology 5 (1997), S. 0 
    Details
    ISSN: 1526-100X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: This historical and conceptual overview of riparian ecosystem restoration discusses how riparian ecosystems have been defined, describes the hydrologic, geomorphic, and biotic processes that create and maintain riparian ecosystems of the western USA, identifies the main types of anthropogenic desturbances occurring in these ecosystems, and provides an overview of restoration methods for each disturbance type. We suggest that riparian ecosystems consist of two zones: Zone I occupies the active floodplain and is frequently inundated and Zone II extends from the active floodplain to the valley wall. Successful restoration depends n understanding the physical and biological processes that influence natural riparian ecosystems and the types of disturbance that have degraded riparian areas. Thus we recommend adopting a process-based approach for riparian restoration. Disturbances to riparian ecosystems in the western USA result from streamflow modifications by dams, reservoirs, and diversions; stream channelization; direct modification of the riparian ecosystem; and watershed disturbances. Four topics should be addressed to advance the state of science for restoration of riparian ecosys-tems: (1) interdisciplinary approaches, (2) a unified framework, (3) a better understanding of fundamental riparian ecosystem processes, and (4) restoration po-tential more closely related to disturbance type. Three issues should be considered regarding the cause of the degraded environment: (1) the location of the causative disturbance with respect to the degraded riparian area, (2) whether the disturbance is ongoing or can be elim-inated, and (3) whether or not recovery will occur nat-urally if the disturbance is removed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1526-100X.1997.tb00200.x
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  • 7
    Digitale Medien
    Digitale Medien
    Applying a Two-Stage System to Prioritize Riparian Restoration at the San Luis Rey River, San Diego County, California (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Restoration ecology 5 (1997), S. 0 
    Details
    ISSN: 1526-100X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: A two-stage system for selecting stream reaches and riparian communities for restoration was applied to the 80-km San Luis Rey River below the Lake Henshaw dam in southern California. In the first satge, data from topographic quadrangles and aerial photographs were analyzed to define and classiy reaches. These analyses concluded that (1) 28 km of the river and adjacent floodplain were suitable for second-stage evaluation of restoration needs and (2) 32 km met criteria for reference conditions at the stream reach scale and should be protected from further impacts. The remaining 20 km of the river and floodplain were considered unsuitable for restoration to reach-scale reference conditions; individual sites may be restored under existing regulatory review. Second-stage field sampling provided data on vegetation and floodplain landforms and substrate from more thatn 3000 plots within the 28 km of river and 1120 ha of floodplain selected for further Study. Classification of floristic samples stratified by landform/substrate class indicated six primary riparian communities on the floodplain, some associated with particular floodplain landform/substrate classes and others ubiquitous. Reference conditions for these communities were interpreted from the data. There were two major departures from reference conditions: tree-dominated communities were less extensive than historic levels and exotic plants had significantly invaded some landforms and communities, displacing natural com-munities. General goals would include restoration of tree communities and removal of exotics, with further consideration of site-specific objectives. The results included estimates of the areas by community type re-quiring restoration. The approach was developed for streams in the semi-arid western United States, but it may be adapted for use elsewhere.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1526-100X.1997.tb00204.x
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  • 8
    Digitale Medien
    Digitale Medien
    A Comparison of Approaches to Prioritizing Sites for Riparian Restoration (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Restoration ecology 5 (1997), S. 0 
    Details
    ISSN: 1526-100X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: This study compares the results of Olson and Harris (1997) and Russell et al. (1997) in their work to prioritize sites for riparian restoration in the San Luis Rey River watershed. Olson and Harris defined reaches of the mainstem and evaluated the relative potential for restoration and protection based on cover of natural vegetation, land use, and connectivity. Then they used data on geomorphic conditions, plant species composition, and community structure to prescribe strategies for restoration. Russell et al. used a modeling approach within a geographic information system to combine data on wetness and land use/land cover to identify areas with potential for protection and restoration. They prioritized the areas based on patch size and proximity to extant riparian habitat. The main-stem and associated floodplain defined by Olson and Harris was more than twice the size of the area defined by Russell et al., because Olson and Harris considered the entire valley floor, whereas Russell et al. used a wetness index to identify saturated zones within the floodplain. For seven of the twelve management units delineated along the mainstem, the two studies agreed on a strategy of restoration or protection. They differed on two. No comparison could be made of the three units for which Olson and Harris used project review, a unique category. Agreement of the results is due to the similarity of criteria used to identify and rank sites for protection and restoration; disagreement is due primarily to the level of resolution of the data. Both approaches have potential for use in watershed-level planning. The predictive power of the two approaches may be maximized when they are used in a complementary fashion.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1526-100X.1997.tb00206.x
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  • 9
    Digitale Medien
    Digitale Medien
    Identifying Sites for Riparian Wetland Restoration: Application of a Model to the Upper Arkansas River Basin (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Restoration ecology 5 (1997), S. 0 
    Details
    ISSN: 1526-100X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: We present a conceptual model for identifying restoration sites for riparian wetlands and discuss its application to reaches within the Upper Arkansas River basin in Colorado. The model utilizes a Geographic Information System (GIS) to analyze a variety of spatial data useful in characterizing geomorphology, hydrology, and vegetation of riparian wetland sites. The model focuses on three basic properties of riparian wetland sites: relative soil moisture, disturbance regime, and vegetative characteristics. A relative wetness index is used to define nominal soil moisture classes within the watershed. These classes generally coincide with uplands (low), channel margins (moderate), and channels or open water (high). Vegetative conditions are characterized using color infrared aerial photographs. Land cover types are grouped into five major land cover classes: riparian, moist herbaceous, bare ground, upland, and open water. Disturbance regime is characterized by a reach-based index of specific power (ω). Preliminary results indicate that reaches within the Upper Arkansas River basin can be classified as high energy (ω≥ 8 W/m2) or low energy (ω≤ 3W/m2), using discharge estimates that reflect the 10-year flood event. Field surveys of channel and floodplain conditions show that high-energy reaches (ω≥ 8 W/m2) are characterized by sites where the channel occupies a large proportion of the valley bottom. By contrast, low-energy reaches (ω≤ 3 W/m2) are characterized by meandering channels with wide alluvial valleys. Restoration potential is evaluated as a combination of nominal scores from wetness, land cover, and disturbance indices. Application of these methods to field sites within the Upper Arkansas River basin identifies a wide range of riparian wetland sites for preservation or restoration. Potential sites within identified reaches are prioritized using size and proximity criteria.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1526-100X.1997.tb00208.x
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  • 10
    Digitale Medien
    Digitale Medien
    Restoration Biology: A Population Biology Perspective (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Restoration ecology 5 (1997), S. 0 
    Details
    ISSN: 1526-100X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: A major goal of population biologists involved in restoration work is to restore populations to a level that will allow them to persist over the long term within a dynamic landscape and include the ability to undergo adaptive evolutionary change. We discuss five research areas of particular importance to restoration biology that offer potentially unique opportunities to couple basic research with the practical needs of restorationists. The five research areas are: (1) the influence of numbers of individuals and genetic variation in the initial population on population colonization, establishment, growth, and evolutionary potential; (2) the role of local adaptation and life history traits in the success of restored populations; (3) the influence of the spatial arrangement of landscape elements on metapopulation dynamics and population processes such as migration; (4) the effects of genetic drift, gene flow, and selection on population persistence within an often accelerated, successional time frame; and (5) the influence of interspecific interactions on population dynamics and community development. We also provide a sample of practical problems faced by practitioners, each of which encompasses one or more of the research areas discussed, and that may be solved by addressing fundamental research questions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1526-100X.1997.00542.x
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