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  • 1
    Publication Date: 2022-05-25
    Description: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Romagnoni, G., Kvile, K. o., Dagestad, K., Eikeset, A. M., Kristiansen, T., Stenseth, N. C., & Langangen, O. Influence of larval transport and temperature on recruitment dynamics of North Sea cod (Gadus morhua) across spatial scales of observation. Fisheries Oceanography, (2020): 1-16, doi:10.1111/fog.12474.
    Description: The survival of fish eggs and larvae, and therefore recruitment success, can be critically affected by transport in ocean currents. Combining a model of early‐life stage dispersal with statistical stock–recruitment models, we investigated the role of larval transport for recruitment variability across spatial scales for the population complex of North Sea cod (Gadus morhua ). By using a coupled physical–biological model, we estimated the egg and larval transport over a 44‐year period. The oceanographic component of the model, capable of capturing the interannual variability of temperature and ocean current patterns, was coupled to the biological component, an individual‐based model (IBM) that simulated the cod eggs and larvae development and mortality. This study proposes a novel method to account for larval transport and success in stock–recruitment models: weighting the spawning stock biomass by retention rate and, in the case of multiple populations, their connectivity. Our method provides an estimate of the stock biomass contributing to recruitment and the effect of larval transport on recruitment variability. Our results indicate an effect, albeit small, in some populations at the local level. Including transport anomaly as an environmental covariate in traditional stock–recruitment models in turn captures recruitment variability at larger scales. Our study aims to quantify the role of larval transport for recruitment across spatial scales, and disentangle the roles of temperature and larval transport on effective connectivity between populations, thus informing about the potential impacts of climate change on the cod population structure in the North Sea.
    Description: G.R. was supported by the Norden Top‐level Research Initiative sub‐programme “Effect Studies and Adaptation to Climate Change” through the Nordic Centre for Research on Marine Ecosystems and Resources under Climate Change (NorMER). K.Ø.K. was supported by the WHOI John H. Steele Post‐doctoral Scholar award and VISTA – a basic research program in collaboration between The Norwegian Academy of Science and Letters, and Equinor. We thank an anonymous referee for valuable comments that substantially improved the article.
    Keywords: Atlantic cod ; biophysical model ; larval transport ; North Sea ; populations ; stock–recruitment ; temperature
    Repository Name: Woods Hole Open Access Server
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  • 2
    Publication Date: 2017-04-04
    Description: We show the magnetic model of the Selli-Vavilov region. The Selli Line is known as the northwestern edge of the southern Tyrrhenian basin. The tectonic evolution of the Tyrrhenian basin is dominated by a Tortonian - Quaternary extension through the eastward movement of the Apennine subduction system. This migration has generated a diffuse stretching of the continental crust with the emplacement of new oceanic material. This latter occurred in several localized zones where the eastward retreating of the Ionian subduction system produced a strong depletion of the crust with formation of basins and correlated spreading. Nowadays the presence of oceanic crust is confirmed through direct drilling investigation but a complete mapping of the oceanic crustal distribution is still lacking. The Selli-Vavilov region shows a differentiated crustal setting where seamount structures, the oceanic basement portions and continental crust blocks are superimposed. To this aim, a 2D inversion of the magnetic data of this region was conducted to define buried structures. The magnetic susceptibility pattern was computed by solving the least squares problem of the misfit between the predicted and real data for separated wavebands. This method produced two 2D models of the high and low frequency fields of the Selli-Vavilov region. The two apparent susceptibility maps provide different information for distinct ranges of depth. The results of the inversions were also combined with seismic data of the Selli region highlighting the position of the highly-magnetized buried bodies. The results confirm a role for the Selli Line as a deep crustal boundary dividing the Sardinian passive domain from the easternmost active region where different oceanic structures are located. The Selli Line has worked as a detachment fault system which has moved eastward. Finally, the Selli-Vavilov region may be interpreted as a tectonic result due to a passive asymmetrical rift occurred between the Tortonian and Pliocene.
    Description: Published
    Description: 251-266
    Description: 2.6. TTC - Laboratorio di gravimetria, magnetismo ed elettromagnetismo in aree attive
    Description: 3.4. Geomagnetismo
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: JCR Journal
    Description: reserved
    Keywords: Geomagnetism ; Tectonics ; Geodynamics ; Inversion ; Oceanic crust ; Volcanic structure ; 04. Solid Earth::04.05. Geomagnetism::04.05.04. Magnetic anomalies ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 05. General::05.01. Computational geophysics::05.01.03. Inverse methods
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Keywords: Assessment ; Malaria ; Public Health ; Scale ; Weather ; climate change ; public health policy ; temperature
    Description / Table of Contents: Awareness that many key aspects of public health are strongly influenced by climate is growing dramatically, driven by new research and experience and fears of climate change and the research needed to underpin policy developments in area is growing rapidly . This awareness has yet to translate into a practical use of climate knowledge by health policy-makers. Evidence based policy and practice is the mantra of the health sector. If climate scientists are to contribute effectively to health policy at local and global scales then careful empirical studies must be undertaken – focused on the needs of the public health policy and decision-makers. Results presented at the Wengen conference make clear that the science and art of integrating climate knowledge into the control of climate sensitive diseases on a year to year time frame as well as careful assessments of the potential impacts of climate change on health outcomes over longer time frames is advancing rapidly on many fronts. This includes advances in the empirical understanding of mechanisms, methodologies for modeling future impacts, new partnership developments between the health and climate community along with access to relevant data resources, and education and training. In a rapidly evolving field this book provides a snapshot of these emerging themes.
    Pages: Online-Ressource (X, 232 pages)
    ISBN: 9781402068775
    Language: English
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  • 4
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    In:  Computers and Geosciences, Münster, 3, vol. 28, no. 45, pp. 309-326, pp. L11609, (ISBN 0-471-26610-8)
    Publication Date: 2002
    Keywords: Inversion ; Data analysis / ~ processing ; Non-linear effects ; Discrimination ; C&G
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  • 5
    ISSN: 1570-7458
    Keywords: Anagyrus kamali ; Encyrtidae ; parasitoid ; Maconellicoccus hirsutus ; Pseudococcidae ; host density ; functional response ; temperature ; photoperiod
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The peformance of the parasitoid Anagyrus kamali Moursi [Hymenoptera: Encyrtidae], as a function of host density, temperature, and photoperiod was investigated with the objective to optimize a mass-rearing system in the context of a biological control program. The number of hosts parasitized at densities varying from 2–100 hibiscus mealybug (HMB), Maconellicoccus hirsutus Green [Homoptera: Pseudococcidae], corresponded to a type II-III functional response in fixed-time conditions and a type III in variable-time conditions. Twenty-six percent of the oviposited eggs led to progeny emergence with a sex ratio of 0.49±0.102 (M/F), regardless of host density. Fecundity and oviposition period under six abiotic combinations (i.e., two temperatures (26±2 °C and 32±2 °C) and three photoperiods (L0:D24, L12:D12, L24:D0)) were measured. Lifetime fecundity and reproductive life were significantly affected by temperature and photoperiod conditions. Optimum female parasitoid lifetime fecundity was attained at 26±2 °C, L0:D24 with an average of 116.1±17.43 eggs. At 32±2 °C, L24:D0 and L12:D12, an average of 79.4±34.57 and 85.8±35.81 eggs were laid, respectively. Reproductive longevity was maximal at 26±2 °C, L0:D24 with 12±4.85 days of oviposition. Because the parasite A. kamali can be reared optimally without light, this may save tremendous energy costs.
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  • 6
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    Entomologia experimentalis et applicata 95 (2000), S. 173-184 
    ISSN: 1570-7458
    Keywords: Aphidius ervi ; Aphidius rhopalosiphi ; Praon volucre ; Sitobion avenae ; temperature ; development time ; parasitization ; superparasitization ; lower temperature thresholds ; immature mortality ; sex ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Temperature dependencies were established for the egg-to-mummy and mummy-to-adult phases, for mummy mortality, and for parasitism of Aphidius ervi Haliday, Aphidius rhopalosiphi De Stefani-Perez, and Praon volucre (Haliday) (Hymenoptera, Aphidiidae), three parasitoids of Sitobion avenae (Fabricius) (Homoptera, Aphididae), at 8 °C, 12 °C, 16 °C, 20 °C, and 25 °C on winter wheat (cv. Haven). A physiological model described temperature-dependent development over the full temperature range, whereas a linear model was fitted for data above 8 °C and used to estimate the lower temperature thresholds and day-degrees (° D) required for development. The thresholds for A. ervi were 2.2 °C for egg-mummy development and 6.6 °C for mummy-adult development, those for A. rhopalosiphi were 4.5 °C and 7.2 °C, and those for P. volucre were 3.8 °C and 5.5 °C. The time to develop into mummies and adults differed significantly between the three species: A. ervi development into mummies required an average of 159 ° D, while development into adults took an average of 73 ° D. The corresponding average times required for A. rhopalosiphi and P. volucre to develop mummies were 124° D and 126° D, while their development into adults required an average of 70° D and 150° D, respectively. Mummy mortality was 25–35% at 8 °C and less at the higher temperatures tested, but began to increase again at 25 °C, showing a quadratic relationship between mortality and temperature. Parasitization was very low or, in the case of P. volucre, absent up to 12 °C and thereafter increased with increasing temperature. The relationship between parasitization, recorded as percent aphids mummified, and temperature was linear at the temperatures tested and depended on species. A. ervisuperparasitized 11.1% aphids at 20 °C and 16.6% aphids at 25 °C, whereas superparasitism was low in A. rhopalosiphi and absent in P. volucre. From 16 °C to 25 °C the P. volucre sex ratio increased. For A. ervi and A. rhopalosiphi there was no trend with temperature, but at 20 °C and 25 °C it was close to even. Field data for 1996 and 1997 allowed for a comparison of actual and expected emergence of overwintering mummies. In both years, parasitoids were predicted to have emerged from overwintering mummies well in advance of the onset of aphid infestation, and more than a month earlier than the first parasitized aphids were found in winter wheat. Observations from trap plants in other crops supported the predictions of the models. Other factors that can affect biological control by cereal aphid parasitoids are discussed.
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  • 7
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    Journal of solution chemistry 29 (2000), S. 63-86 
    ISSN: 1572-8927
    Keywords: Thorium ; hydrolysis ; potentiometry ; solvent extraction ; temperature ; thermodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The stability constants of thorium(IV) hydrolysis species have been measured at15, 25, and 35°C (in 1.0 mol dm−3 NaClO4) using both potentiometry and solventextraction. The results indicate the presence of the monomeric speciesTh(OH)3+, Th(OH)2+ 2, Th(OH)+ 3, and Th(OH)4, in addition to the polymericspecies Th4(OH)8+ 8 and Th6(OH)9+ 15. The polymeric species were found to beimportant, although the total thorium concentration was limited to 0.01–0.1mmol-dm−3. The solvent extraction measurements required the use of acetylacetone.As such, the stability constants of thorium(IV) with acetylacetone were alsomeasured using both potentiometry and solvent extraction. All logarithms of thestability constants were found to be linear functions of the reciprocal absolutetemperature indicating that ΔH o and ΔSo of reaction are both independent oftemperature (over the temperature range examined in the study).
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  • 8
    ISSN: 1572-8927
    Keywords: Flow-through cell ; conductivity ; electrolyte ; ion association ; temperature ; pressure ; LiCl ; NaCl ; KCl
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A flow-through electrical conductance cell was assembled in order to measuremolar conductances of dilute aqueous electrolytes with a high degree of accuracyat high temperatures and pressures. The design of the cell is based on the conceptdeveloped at the University of Delaware and built in 1995, with modificationsthat will allow the cell to operate at much higher temperatures (to 600°C) andpressures (to 300 MPa). At present, the cell has been tested successfully bymeasuring aqueous (10−4-10−3 mol-kg−1) solutions of LiCl, NaCl, and KCl attemperatures 25–410°C and pressures 9.8–33 MPa. The results are in goodagreement with reported values, including those measured with the Delawareflow-through cell. These new results are also complementary to our previousresults, which were measured with a static high-pressure cell. Measurements attemperatures near the critical point of water (374°C, 22.1 MPa) require the useof lower solution concentrations that were unachievable in the past with thestatic cell.
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  • 9
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    Geometriae dedicata 83 (2000), S. 31-37 
    ISSN: 1572-9168
    Keywords: Vollständiges Viereck ; Kegelschnittbüschel ; Konjugiertheitsabbildung ; Inversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The conjugacy mapping rel. to a complete quadrangle in a Pappian projective plane of characteristic ≠2 is constructed by using a bijection of the line set onto the bundle of conics through the diagonal points of the quadrangle. The inversion with center O of the inversion circle going through the point P in the Euclidean plane proves to be the product of the reflection at OP and the affine restriction of the conjugacy mapping rel. to the quadrangle having P as one of its vertices and O together with the circular points at infinity as diagonal points.
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  • 10
    ISSN: 1573-0417
    Keywords: diatoms ; climate change ; temperature ; pH ; transfer functions ; lake sediments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The relationships between diatoms (Bacillariophyceae) in surface sediments of lakes and summer air temperature, pH and total organic carbon concentration (TOC) were explored along a steep climatic gradient in northern Sweden to provide a tool to infer past climate conditions from sediment cores. The study sites are in an area with low human impact and range from boreal forest to alpine tundra. Canonical correspondence analysis (CCA) constrained to mean July air temperature and pH clearly showed that diatom community composition was different between lakes situated in conifer-, mountain birch- and alpine-vegetation zones. As a consequence, diatoms and multivariate ordination methods can be used to infer past changes in treeline position and dominant forest type. Quantitative inference models were developed to estimate mean July air temperature, pH and TOC from sedimentary diatom assemblages using weighted averaging (WA) and weighted averaging partial least squares (WA-PLS) regression. Relationships between diatoms and mean July air temperature were independent of lake-water pH, TOC, alkalinity and maximum depth. The results demonstrated that diatoms in lake sediments can provide useful and independent quantitative information for estimating past changes in mean July air temperature (R2 jack = 0.62, RMSEP = 0.86 °C; R2 and root mean squared error of prediction (RMSEP) based on jack-knifing), pH (R2 jack = 0.61, RMSEP = 0.30) and TOC (R2 jack = 0.49, RMSEP = 1.33 mg l-1). The paper focuses mainly on the relationship between diatom community composition and mean July air temperature, but the relationships to pH and TOC are also discussed.
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  • 11
    ISSN: 1349-9432
    Keywords: optical fibres ; temperature ; sensors ; tantalum pentoxide ; thermal optic ; thermal expansion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A fiber optic low-coherence sensor based on the spectral shift of tantalum pentoxide thin films for absolute temperature sensing up to 650°C is described. A tantalum pentoxide single layer was deposited directly onto the cleaved end-face of a single mode optical fibre and was illuminated with an super luminescence diode (SLD) source through a directional coupler. Interference fringes of the film on reflection were obtained within the optical bandwidth of the SLD using an optical spectrum analyser. The spectral shift versus temperature rise showed no turning points and the output was unambiguous, linear, monotonic and gave about 0.016 nm wavelength shift in the spectrum per°C. A semi-empirical calibration procedure based on the refractive index (n) and thickness (l) of the tantalum pentoxide film for absolute thermometric measurements is described.
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  • 12
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    Optical review 7 (2000), S. 555-560 
    ISSN: 1349-9432
    Keywords: lidar ; remote sensing ; Rayleigh scattering ; wind ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new method of simultaneous remote sensing of atmospheric wind and temperature by a ultraviolet Rayleigh lidar is described. This technique uses two narrowband filters located at either side of the wings of the Rayleigh backscatter spectrum to analyze Rayleigh backscattering signals. These filters are selected to be greatly sensitive to both velocity and temperature. By measuring the ratio and the sum of the two normalized filtered signals, the line-of-sight wind velocity and temperature profiles can be retrieved. A lidar system is proposed for the wind velocity and temperature measurements in the middle atmosphere, and the simulation results show that the accuracies of velocity and temperature are about 1 m/s and 2 K at the height of 30 km, respectively. The influence of aerosol component has been estimated for clear weather conditions, and with an uncertainty of aerosol component of 15% the errors are about 0.1 m/s and 2 K above the troposphere, respectively.
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  • 13
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    Environmental geology 39 (2000), S. 360-371 
    ISSN: 1432-0495
    Keywords: Key words Environmental geophysics ; Resistivity ; Inversion ; Landfill mining ; Waste ; Characterization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Geophysical investigations using 2-D DC resistivity were carried out on old parts of two similar landfills, with waste of different ages. The data sets, which included high data density in both vertical and horizontal directions, were interpreted with 2-D smoothness constrained inversion. The landfills were excavated after the surveying. The objective was to test the capability of the resistivity method as a pre-characterization technique. The objectives were only partially fulfilled. First, the moisture content was the parameter that appeared to exert the dominant control over the resistivity distribution of the landfill. The most important potential information that can be recovered is, therefore, an indication of the waste piles hydraulics. Second, it was neither possible to estimate the amount of recoverable soils, nor to correlate the type of waste with the resistivity models. However, discrete anomalies were identified, and if specific materials are searched for, the resistivity models indicate possible places to search.
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  • 14
    ISSN: 1432-1211
    Keywords: Key words Vβ13 ; CD4/CD8 ratio ; Rat ; Tcrb ; Polymorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Three rat BV13S1 alleles (T-cell receptor β-chain variable gene 13) were characterized by new BV13S1-allele specific monoclonal antibodies (18B1 and 17D5) and sequence analysis of expressed and genomic BV13S1. Two alleles were functional and designated BV13S1A1 present in strains LEW, BUF, PVG, and BV13S1A2 present in BN and WF. Their products differed by six amino acids, two of them in complementarity-determing region (CDR)1 and one in CDR2. A third nonfunctional allele, BV13S1A3P, was found in strains F344 and DA. Apart from a single nucleotide insertion, it was identical to BV13S1A2. All 12 rat strains tested showed association of TCRBC1 with BV8S2/4 alleles but not with the BV13S1 alleles, which may reflect a different gene order of the rat BV compared to mouse. BV13S1A1-encoded T-cell receptors (TCRs) which bind both monoclonal antibody (mAb) 18B1 and mAb 17D5 are over-represented in the CD4 lymphocyte subset. BV13S1A2-encoded TCRs which are stained by mAb 18B1 but not by mAb 17D5 show a slight CD8-biased expression. Preferential usage of BV13S1A1-positive TCRs by CD4 but not by CD8 cells in (LEW×WF)F1 hybrids and cosegregation of BV13SA1 and increased frequency of BV13S1 TCR-positive CD4 cells in a (LEW×BN)×BN backcross suggest structural differences of the two allelic products as the reason for their contrasting CD4/CD8 subset bias.
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  • 15
    ISSN: 1432-119X
    Keywords: Endothelin-A receptor ; Endothelin-B receptor ; Rat ; Pulmonary fibrosis ; Immunohistochemistry ; Quantitative PCR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: AbstractPulmonary fibrosis is characterized by excessive extracellular matrix deposition with concomitant loss of gas exchange units, and endothelin-1 (ET-1) has been implicated in its pathogenesis. Increased levels of ET-1 from tissues and bronchoalveolar lavage have been reported in patients with pulmonary fibrosis and in animal models after intratracheal bleomycin. We characterized the cellular distribution of alveolar ET receptors by immunohistochemistry in bleomycin-induced pulmonary fibrosis in the rat and determined the regulation by bleomycin of ET receptor mRNA expression in isolated alveolar macrophages and rat lung fibroblasts. We found significant increases in the numbers of fibroblasts and macrophages at day 7 compared to day 28 and control animals. ETB receptor immunoreactivity was observed on fibroblasts and invading monocytes. Isolated fibroblasts expressed both ETA and ETB receptor mRNA, and ETA receptor mRNA was upregulated by bleomycin. Isolated resident alveolar macrophages expressed neither ETA nor ETB receptor mRNA which were also not induced by bleomycin. We conclude that, while ETB receptor stimulation of fibroblasts and monocytes recruited during bleomycin-induced lung injury exerts antagonistic effects on fibroblast collagen synthesis, the observed increase in the number of fibroblasts in vivo and upregulation of fibroblast ETA receptor mRNA by bleomycin in vitro point to a predominance of the profibrotic effects of ET receptor engagement.
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  • 16
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    Journal of thermal analysis and calorimetry 60 (2000), S. 1081-1091 
    ISSN: 1572-8943
    Keywords: second law of thermodynamics ; temperature ; thermometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A brief outline of the history of development of the temperature concept in physics is given. Simultaneously, some persisting imperfections in the conceptual basis of classical thermodynamics closely related to the first and the second law of thermodynamics are discussed.
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  • 17
    ISSN: 1573-1561
    Keywords: Allelopathy ; autotoxicity ; activated charcoal ; cucumber ; Cucumis sativus L ; 2,4-dichlorobenzoic acid ; organic acids ; photoperiod ; temperature ; root exudates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract In order to elucidate the effects of temperature and photoperiod on the quality and quantity of plant root exudates, a Japanese cucumber (Cucumis sativus, cv. Shougoin-Aonaga-Fushinari) was grown hydroponically in growth chambers under controlled temperature and photoperiod conditions with or without the addition of activated charcoal (AC) to the nutrient solutions. Fresh AC was used to trap the organic compounds exuded from cucumber roots every two weeks. Cucumber plants without AC were severely retarded in root growth and in the accumulation of dry matter, especially at high temperature and long photoperiod, compared to those with AC. The growth inhibitors, adsorbed on the AC or accumulated in the nutrient solution without AC, were extracted by organic solvents and analyzed by GC-MS. Benzoic acid and its derivatives, cinnamic acid derivatives, and fatty acids were identified. The rate of root exudation in vegetative and reproductive stages for some of these organic acids increased with the elevation of temperature and the elongation of photoperiod, and the mean rate was two or more times higher than the minimum exudation at low temperature with short photoperiod. Some of the identified compounds significantly inhibited the germination and/or root growth of lettuce and cucumber.
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  • 18
    ISSN: 1573-4943
    Keywords: Ribonuclease A ; limited proteolysis ; temperature ; guanidine hydrochloride ; unfolding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Moderate temperatures or low concentrations of denaturants diminish the catalytic activity of some enzymes before spectroscopic methods indicate protein unfolding. To discriminate between possible reasons for the inactivation of ribonuclease A, we investigated the influence of temperature and guanidine hydrochloride on its proteolytic susceptibility to proteinase K by determining the proteolytic rate constants and fragment patterns. The results were related to changes of activity and spectroscopic properties of ribonuclease A. With thermal denaturation, the changes in activity and in the rate constants of proteolytic degradation coincide and occur slightly before the spectroscopically observable transition. In the case of guanidine hydrochloride-induced denaturation, however, proteolytic resistance of ribonuclease A initially increases accompanied by a drastic activity decrease far before unfolding of the protein is detected by spectroscopy or proteolysis. In addition to ionic effects, a tightening of the protein structure at low guanidine hydrochloride concentrations is suggested to be responsible for ribonuclease A inactivation.
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  • 19
    ISSN: 1608-3237
    Keywords: poly-β-hydroxybutyric acid ; Yersinia pseudotuberculosis ; Listeria monocytogenes ; temperature ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A comparative investigation of the intracellular content of poly-β-hydroxybutyric acid showed that Yersinia pseudotuberculosis strains accumulated, on the average, lower amounts of this reserve substance than Listeria monocytogenes strains. The intracellular pool of poly-β-hydroxybutyric acid was responsible for the growth of the bacteria at low temperatures (4–6°C) in the absence of any exogenous carbon and energy source.
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  • 20
    ISSN: 1608-3407
    Keywords: red microalgae ; collection of algae ; maintenance conditions ; darkness ; temperature ; chlorophyll fluorescence ; phycobiliproteins ; viability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of light and temperature conditions on the maintenance of some red microalgae (order Porphyridiales) in collections were studied. Periodical subculturing on solid and liquid media was used for maintenance. Halophilic species P. aeruginosa, P. cruentum, and P. sordidum were lost in 2.5 months if kept in darkness. The viability of algae in the dim light slightly declined in 4–5 months and was species-dependent. The results were compared with earlier obtained data on mesophilic Chlorococcales. For the green algae, darkness proved to be the optimal condition, while their viability markedly decreased at light. It was suggested that this discrepancy was caused by the presence of phycobiliproteins in the cells of red algae. Dim light conditions are optimal for the synthesis of phycobiliproteins, which are rapidly destroyed in darkness, thus leading to cell death.
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  • 21
    ISSN: 1573-5125
    Keywords: diapause ; Diaptomus ; permanent environment ; photoperiod ; pond chemistry ; proximate cues ; temperature ; temporary environment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Field and laboratory studies were carried out between 1995 and 1997 on four populations of Diaptomus leptopus found in seasonally temporary, occasionally temporary, and a permanent environment to assess the relative importance of photoperiod and temperature regimes versus other proximate local cues in inducing diapause egg production. Patterns of diapausing and subitaneous egg production were determined by observation of individual females bearing clutches that were produced in the field. A laboratory common-garden experiment was performed to assess the effects of four different regimes of temperature and photoperiod on the induction of diapause. Patterns of diapausing egg production differed among ponds: diapause occurred early in the seasonally temporary environment and occurred rarely in the permanent environment. In the common-garden experiment, populations exhibited substantial changes in the onset of diapause when compared to patterns found under field conditions. These results provide indirect evidence that the different populations respond to available cues of environmental change in different ways in nature, or that environmental cues vary among habitats.
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  • 22
    ISSN: 1573-5125
    Keywords: body size ; chlorophyll concentration ; salinity ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The seasonal variation in length of the most abundant copepod species in the lagoon of Venice were compared and the relative influence of temperature, chlorophyll concentration and salinity examined. Temperature seems to be the primary factor influencing copepod body length in the lagoon of Venice, but the different species vary markedly in their response. Calanoid copepods (Acartia clausi, A. tonsa, Paracalanus parvus and Centropages ponticus) showed a more definite trend of size variation with temperature than the cyclopoids (Oithona nana and O. similis) and the harpacticoid Euterpina acutifrons. The size of the poecilostomatoids Oncaea media and O. subtilis was not affected by temperature, and was almost constant over time. Differences in the metabolic rates, longevity and specialization of calanoid, cyclopoid and harpacticoid copepods could explain their different responses to temperature.
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  • 23
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    Aquatic ecology 34 (2000), S. 227-242 
    ISSN: 1573-5125
    Keywords: cladocerans ; demography ; Microcystis aeruginosa ; rotifers ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The response of selected rotifers and cladocerans to Microcystis aeruginosa, offered as colonies and single cells, was compared to that on a diet of Chlorella vulgaris using the life table demography approach. The test zooplankton species were Simocephalus vetulus, Daphnia carinata, Moina macrocopa, Scapholeberis kingi, Ceriodaphnia cornuta, Brachionus calyciflorus and Hexarthra mira. To detect the development of resistance to toxins from Microcystis in zooplankton, in addition to the laboratory cultured strain of Ceriodaphnia cornuta, another strain of the same species was also used (designated as C. cornuta 2, this was collected from a pond containing Microcystis and cultured in the laboratory on Chlorella for a few weeks prior to experimentation). Experiments were conducted at 20 °C and 30 °C. Survivorship was high on Chlorella in most species but low on diets of Microcystis. Except for C. cornuta 2, S. kingi and S. vetulus, all other test species were adversely affected by Microcystis. The ability to utilise Microcystis improved at 30 °C in M. macrocopa, D. carinata and H. mira. The longest mean lifespan was recorded for C. cornuta 2 (25.3 ± 4.86 d) and the lowest for B. calyciflorus (0.58 ± 0.05 d). The highest net reproductive rate was observed for C. cornuta 1 (44.9 ± 4.88) and the longest generation time of 26.6 ± 2.13 d for S. vetulus. Among the cladocerans that showed positive values of population growth rate (r), M. macrocopa had the highest of 0.96 ± 0.04 per day.
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  • 24
    ISSN: 1573-5176
    Keywords: desiccation ; growth ; growth model ; inorganic carbon ; nutrients ; photoperiod ; photosynthesis ; pigments ; Porphyra linearis ; PPF ; respiration ; temperature ; water velocity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of environmental parameters on the growthof Porphyra linearis gametophytes was examinedunder controlled conditions, and related to themultilinear regression growth model recently developedfor this seaweed under coastal conditions in theeastern Mediterranean. Growth chambers, a gradienttable, special culture devices and analytical methodswere combined for this culture study.The major factors significantly controlling thegrowth rate of the P. linearis gametophytein glass dishes were: photoperiod, temperature, agein culture, photosynthetic photon flux (PPF), salinityand water dynamics. Maximal growth occurred underdaylength of 12 h, medium temperature (15–20 °C), low PPF (70–140 μmol photon m-2s-1), ambient salinity (30–40 ppt), 1–3 h ofdaily air exposure, and water velocity of 4 cm s-1.Photosynthesis and respiration rates weredominantly affected by daylength and temperature,while the concentration of pigments was dominantlyaffected by PPF and temperature.These conditions correspond well to the optimalnatural growth environment of this local species andare in agreement with the optimum estimated throughthe recently developed outdoor mathematical growthmodel.
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  • 25
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    Aquaculture international 8 (2000), S. 513-530 
    ISSN: 1573-143X
    Keywords: great scallop (Pecten maximus) ; hatchery ; metamorphosis ; seawater flow ; spat development ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Variations in growth and survival of hatchery-reared post-metamorphicjuveniles of great scallop Pecten maximus prompted anexamination of settlement and postlarval development. The effects ofseawater flow and temperature on great scallop metamorphosis andpostlarvae were studied over a 4–5 week period. In allexperiments, and regardless of environmental conditions, great scallopmetamorphosed after a 2–3 week period with values of 35 to70%. Subsequently, spat numbers increased slightly. Spatmortality generally occurred from the third week onward and reachedlevels as high as 30% by the fifth week under standardconditions. At 20 °C, however, 60% mortality levels wererecorded. Differences in spat growth rate, ranging from 37 to 45 μmday−1, were noticed at different seawater flow ratesbut no clear tendency could be discerned. Temperature affected spatgrowth with an increase in size from 24 μm day−1 at15 °C to 35 μm day−1 at 18 °C. Conversely,growth was suppressed at 20 °C (14 μm day−1).For optimal metamorphosis and postlarval development in great scallop, aseawater flow of 4.3 L h−1 per sieve and a temperatureof 15 °C are recommended.
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  • 26
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    Evolutionary ecology 14 (2000), S. 627-643 
    ISSN: 1573-8477
    Keywords: adaptation ; Bergmann's rule ; clutch size ; egg size ; physiological constraint ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Organisms and parts of an organism like eggs or individual cells developing in colder environments tend to grow bigger. A unifying explanation for this Bergmann's rule extended to ectotherms has not been found, and whether this is an adaptive response or a physiological constraint is debated. The dependence of egg and clutch size on the mother's temperature environment were investigated in the yellow dung fly Scathophaga stercoraria. Smaller eggs were laid at warmer temperatures in the field and the laboratory, where possible confounding variables were controlled for. As clutch size at the same time was unaffected by temperature, this effect was not due to a trade-off between egg size and number. Temperature-dependent egg sizes even persisted within individuals: when females were transferred to a cooler (warmer) environment, they laid third-clutch eggs that were larger (smaller) than their first-clutch eggs. The fitness consequences of these temperature-mediated egg sizes were further investigated in two laboratory experiments. Neither egg and pre-adult survivorship nor larval growth rate were maximized, nor was development time minimized, at the ambient temperature corresponding to the mother's temperature environment. This does not support the beneficial acclimation hypothesis. Instead, this study yielded some, but by no means conclusive indications of best performance by offspring from eggs laid at intermediate temperatures, weakly supporting the optimal temperature hypothesis. In one experiment the smaller eggs laid at 24°C had reduced survivorship at all ambient temperatures tested. Smaller eggs thus generally performed poorly. The most parsimonious interpretation of these results is that temperature-mediated variation in egg size is a maternal physiological response (perhaps even a constraint) of unclear adaptive value.
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  • 27
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    Annals of biomedical engineering 28 (2000), S. 128-134 
    ISSN: 1573-9686
    Keywords: Hippocampus ; Vigilance states ; Paired-pulse ; Dentate gyrus ; Dentate granule cells ; Evoked response ; Rat ; In vivo studies ; Perforant path ; Maturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract This study examined the effect of normal development and vigilance state on the modulation of dentate granule cell activity in the freely moving rat at 15, 30, and 90 days of age across three vigilance states: quiet waking, slow-wave sleep, and rapid eye movement sleep. Using paired-pulse stimulation, the paired-pulse index (PPI) was obtained for the dentate evoked field potentials elicited by the stimulation of the medial perforant path. Although significant differences in PPI values were observed during development, no significant vigilance state related changes were obtained. Preweaning infant rats, i.e., 15-day old, exhibited significantly less early (interpulse intervals, IPI= 20–50 ms) and late (IPI = 300–1000 ms) inhibition, and less facilitation (IPI = 50–150 ms) when compared to the 90-day old adult rats during all three vigilance states. PPI values obtained from the 30-day old group fell intermediate between the 15- and 90-day old animals. These changes in PPI values provide a quantitative measure of changes in the modulation of dentate granule cell excitability during normal maturation. They can now can be used to evaluate the impact of various insults, such as prenatal protein malnutrition or neonatal stress, on hippocampal development. © 2000 Biomedical Engineering Society. PAC00: 8717Nn, 8719La, 8719Nn
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  • 28
    ISSN: 1573-9686
    Keywords: Heart ; Left ventricle ; LV contractility ; ESPVR ; Pig ; Rat ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The end systolic pressure–volume relation (ESPVR) has been shown to be a relatively load independent measure of left ventricular (LV) contractility. Recently, several single-beat ESPVR computation methods have been developed, enabling the quantification of LV contractility without the need to alter vascular loading conditions on the heart. Using a single-beat ESPVR method, which has been validated previously in humans and assumes that normalized elastance is constant between individuals of a species, we studied the effects of myocardial infarction on LV contractility in two species, the rat and the pig. In our studies, LV pressure was acquired invasively and LV volume determined noninvasively with magnetic resonance imaging, at one week postinfarction in pigs and at 12 weeks postinfarction in rats. Normalized systolic elastance curves in both animal species were not statistically different from that of humans. Also, the slope of the ESPVR $$\left( {E_{es} } \right)$$ decreased significantly following infarction in both species, while the volume-axis intercept $$\left( {V_0 } \right)$$ was unaffected. These results indicate that a single-beat ESPVR method can be used to measure the inotropic response of the heart to myocardial infarction, and that the basis for this method (i.e., constant normalized elastance) is applicable to a variety of mammalian species. © 2000 Biomedical Engineering Society. PAC00: 8719Uv, 8761Lh, 8719Hh, 8719Rr, 8719Ff
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  • 29
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    Annals of biomedical engineering 28 (2000), S. 1101-1115 
    ISSN: 1573-9686
    Keywords: Time–frequency analysis ; Coherence ; Cross correlation ; Nonstationary persistent signals ; Central pattern generator ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract We present a novel time-varying phase spectrum (TVPS) method to quantify the dynamics of coevolution of two persistent nonstationary coupled signals. Based on the TVPS, an instantaneous intersignal phase shift is defined within the primary frequency range in which the two signals are highly correlated. The TVPS is estimated using a fixed-window method or an adaptive-window method. In the latter method, the window length changes dynamically and automatically as a function of change in frequency of the signals. The effects of altering window types and lengths on the accuracy of the estimation of the primary phase shift is assessed by analyzing synthesized linear chirp signals with decaying amplitude and constant relative phase shift or decaying amplitude and changing relative phase shifts. The methods developed are also used for determining the evolution of the primary phase shift among ventral root activities during fictive locomotion in an in vitro rat spinal cord preparation. The analyses indicate that the TVPS method in conjunction with the determination of the primary frequency range, allows determination of both the evolution of the coupling strength and the evolution of the phase shift between two persistent nonstationary rhythmic signals in the joint time–frequency domain. An adaptive window reduces the estimation bias and the estimation variability. © 2000 Biomedical Engineering Society. PAC00: 0230-f, 8780Tq
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  • 30
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    Powder metallurgy and metal ceramics 39 (2000), S. 599-602 
    ISSN: 1573-9066
    Keywords: solid-phase reaction ; solubility ; temperature ; cobalt silicides ; boron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The system Co ― Si ― B is promising for development of new soft magnetic materials. We studied the effect of boron on the structure and composition of cobalt silicides during solid-phase reaction of powders of the starting components under a 3·10−3 Pa vacuum in the temperature range 200°C to 1300°C for boron content from 0.5 mass% to 7.7 mass% by differential thermal analysis, metallographic analysis, x-ray analysis, and electron-probe microanalysis. We established that boron is not soluble in cobalt silicides. Formation of ternary chemical compounds is typical for the Co ― Si ― B system.
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  • 31
    ISSN: 1573-5036
    Keywords: Arctic ; Cerastium alpinum ; nitrogen source ; nitrogen-uptake ; organic N ; polar-desert plants ; Saxifraga caespitosa ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Polar-desert plants experience low average air temperatures during their short growing season (4–8 °C mean July temperature). In addition, low availability of inorganic nitrogen in the soil may also limit plant growth. Our goals were to elucidate which N sources can be acquired by polar-desert plants, and how growth and N-uptake are affected by low growth temperatures. We compared rates of N-uptake and increases in mass and leaf area of two polar-desert species (Cerastium alpinum L. and Saxifraga caespitosa L.) over a period of 3 weeks when grown at two temperatures (6 °C vs. 15 °C) and supplied with either glycine, NH4 + or NO3 −. At 15 °C, plants at least doubled their leaf area, whereas there was no change in leaf area at 6 °C. Measured mean N-uptake rates varied between 0.5 nmol g−1 root DM s−1 on glycine at 15 °C and 7.5 nmol g−1 root DM s−1 on NH4 + at 15 °C. Uptake rates based upon increases in mass and tissue N concentrations showed that plants had a lower N-uptake rate at 6 °C, regardless of N source or species. We conclude that these polar-desert plants can use all three N sources to increase their leaf area and support flowering when grown at 15 °C. Based upon short-term (8 h) uptake experiments, we also conclude that the short-term capacity to take up inorganic or organic N is not reduced by low temperature (6 °C). However, net N-uptake integrated over a three-week period is severely reduced at 6 °C.
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  • 32
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    Hydrobiologia 419 (2000), S. 141-148 
    ISSN: 1573-5117
    Keywords: Crustacea ; Ostracoda ; Krithe praetexta praetexta ; life cycle ; ontogeny ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of temperature on growth rate, shell size and shell shape in Krithe praetexta praetexta (Sars) was studied in four thermocultures. From July 1995 to June 1996, the cultures were kept in a continuously flowing open system pumping water from the intermediate watermass of the Gullmarn fjord, west coast of Sweden. Three cultures were kept at constant temperatures of 5, 10 and 14 °C, respectively. The fourth (reference) culture largely followed the natural variation in temperature. At the termination of the experiment, all living ostracods from a 125 μm sieve were sampled from the cultures. Population age structures were analysed for the various thermocultures of K. praetexta praetexta. These were more shifted towards later ontogenetic stages with higher temperature, i.e. the ontogenetic development was more rapid in the warmer cultures. An alternative explanation is due to diapause causing cohorts to accumulate in some ontogenetic stages only when the temperature is constant. The differences in shell size of K. praetexta praetexta among the thermoconstant cultures were not statistically significant.
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  • 33
    ISSN: 1573-5117
    Keywords: Chirocephalus ; metabolic potential ; intermittent lake ; ecology ; physiology ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Electron transport system (ETS) activity was measured in Chirocephalus croaticus from the intermittent lake, Petelinjsko Jezero. The ETS activities were measured at 5, 10, 15, 20, and 25 °C, and were studied separately in juveniles, females and males. Juveniles had significantly higher activity than adults at a standard temperature of 20 °C. The mass-specific ETS activity decreased with increasing size of the animals; the value b was 0.787. Respiration rates (R) were determined at 20 °C and the ratio ETS/R (±standard deviation) for C. croaticus was 1.43±0.46 (n=38). ETS activity increased with temperature. Females had higher Q10 than males in higher temperature range (t-test; t=2.50; d.f.=8; p〈0.05). Activation energy Ea was higher for females than males (t-test; t=2.35; d.f.=8; p〈0.05). Females exhibited lower ETS activity than males over the lower temperature range, but their ETS could function more efficient at higher temperature.
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  • 34
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    Environmental biology of fishes 57 (2000), S. 113-115 
    ISSN: 1573-5133
    Keywords: photoperiod ; temperature ; spawning ; larva rearing ; larva food
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Adult fish of a freshwater population of the Iberian endangered cyprinodontid Aphanius iberus, were induced to reproduce at salinities of 5, 15, 30, 45 and 60 ppt. For each salinity five 30 l aquaria were used, each one including a male and two females. Maturity and spawning outside the natural season, were obtained at conditions of 22 to 28°C and a photoperiod of 14L:10D. The larvae were fed with rotifers Brachionus plicatilis and Synchaeta cecilia valentina. Experiment lasted 40 days. The first spawning occurred on the 17th day at 45 ppt of salinity and the first embryos hatched on the 34th day at 5 and 15 ppt salinity. The final average number of larvae per aquarium ranged from 5.2 (45 ppt salinity) to 10.8 (15 ppt salinity). No significant differences were found between the average values at different salinities (p〈0.01).
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  • 35
    ISSN: 1573-5133
    Keywords: deep pools ; young salmonids ; habitat use ; habitat availability ; temporal variation ; temperature ; winter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract There was a pronounced decline in activity of young pool-dwelling Atlantic salmon, Salmo salar, and brown trout, Salmo trutta, as the water temperatures dropped in the autumn and early winter, and the fish switched from a predominantly diurnal towards a nocturnal activity pattern. Such a switch in activity pattern has previously been observed in young brown trout, but the present study is the first documentation for juvenile Atlantic salmon under natural conditions. Juvenile fish fed actively even when water temperatures were below 0°C, although foraging behaviour at near-freezing temperatures was recorded exclusively during night surveys. This indicates that other proximate factors, in addition to water temperature, affect the activity of young salmon and trout in rivers. Trout kept feeding positions significantly higher above bottom than salmon in August and September, but both species reduced the height above bottom at the onset of winter, possibly due to reduced swimming performance and lowered food availability in the upper part of the water column.
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  • 36
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    Hydrobiologia 441 (2000), S. 55-62 
    ISSN: 1573-5117
    Keywords: climate change ; temperature ; mayflies ; Cloeon dipterum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Populations of the mayfly Cloeon dipterum from 48 ponds (3000 l fibre-glass tanks of 1 m depth) were monitored over the course of 1 year. To simulate possible patterns of climatic change, the ponds were subject to three temperature treatments: continuous heating to 3 °C above ambient; heating to 3 °C above ambient during the summer only; and no heating. Further experimental complexity included enhanced nutrient input into the ponds and the presence or absence of fish, giving a factorial combination of 3 temperature regimes × 2 nutrient levels × presence/absence of fish predation. Few nymphs were found in the presence of fish. Where fish were absent, the temperature treatments did not significantly affect nymph abundances, and only marginally influenced mean nymph body-lengths. In contrast, the nutrient treatment had significant effects on both nymph abundance and size, with greater numbers of generally larger nymphs occurring in those fish-free ponds receiving additional nutrients. Adult emergence began earlier in the year from the heated ponds, particularly those ponds receiving additional nutrients. Adult body-length differed between temperature treatments, but consistent patterns were difficult to ascertain because of interactions with nutrient treatment and seasonal effects. Our results show that during the short term at least, elevated temperature as a simulation of climate change does not have an overwhelming influence on either mayfly abundance or size. The influence of temperature is subtle and subject to complex interaction with other habitat variables. We therefore suggest that the direct consequences of small changes in temperature will likely be of little significance to C. dipterum, relative to indirect effects operating through interactions with predation and nutrient input.
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  • 37
    ISSN: 1573-5117
    Keywords: Meganyctiphanes norvegica ; respiration ; temperature ; vertical migration ; Kattegat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Alkor-Deep (140 m), which forms part of a depression system in the northern Kattegat channel east of the island of Læsø (Denmark), is the location of a self sustaining population of Northern krill, Meganyctiphanes norvegica (Euphausiacea). This population is exposed to one of the most pronounced thermal gradients within the distributional range of this pelagic crustacean. During summer, the temperature of the water column ranges between 4 and 6 in the deep to 16 °C near the surface which results in the krill being exposed to temperature differences of 8–10 °C during diel vertical migration. Oxygen consumption rates were used to investigate the physiological adaptation of the animal to such gradients in temperature. The rates were found to increase exponentially from 31 μmol O2 h-1 gdw -1 at 4 °C to 72 μmol O2 h-1 gdw -1 at 16 °C, giving a Q 10-value of 2.0, and indicating that physiological adaptation to varying thermal conditions does not take place. Behavioural adaptations are discussed which may help the krill to cope with large temperature gradients in their environment.
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  • 38
    ISSN: 1573-5117
    Keywords: Cercopagis ; invasion ; Baltic Sea ; depth ; temperature ; salinity ; morphological variations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The onychopod cladoceran Cercopagis that recently invaded the Baltic Sea is reported from new zones of the northern Baltic proper. Because of successful survival and an expanding distribution range, the addition of Cercopagis to the Baltic fauna is considered to be permanent. What has previously been cited as Cercopagis pengoi encompasses the morphology of several other species, subspecies and forms. Either a number of morphologically similar species is present, or there is a number of spurious species in Cercopagis. The last hypothesis is favoured. The spatial distribution pattern of Cercopagis, as well as that of total zooplankton, was correlated with depth. Deep (〉100 m) and shallow (〈10 m) stations had significantly lower abundance than stations of intermediate depth (〈100 m). An overview of the distribution of C. pengoi group in fresh and brackish waters suggests a high tolerance to environmental factors, but with differences among taxa. Due to this ecological flexibility, the colonization of the Baltic is not unexpected. Increasing salinity may restrict dispersal of cercopagids to the southern areas of the Baltic and to the North Sea, but inland lakes (e.g. in Sweden) present an ecological profile suitable for colonization.
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  • 39
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    Hydrobiologia 431 (2000), S. 175-184 
    ISSN: 1573-5117
    Keywords: Dreissena ; lake stratification ; water clarity ; temperature ; oxygen ; metalimnion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Colonization and proliferation of zebra mussel (Dreissena polymorpha) population in Hargus lake, a small thermally stratified reservoir in Ohio, U.S.A., caused a significant increase in water clarity and a remarkable decrease in phytoplankton biomass during the period from 1993 to 1995. Increased light penetration and reduced organic matter loading to the meta-and hypolimnion were reflected in the lake stratification patterns, particularly in the temperature and oxygen profiles in the metalimnion. The meta- and hypolimnetic water temperature increased significantly over three years, irrespective of variation in surface water temperature. The epilimnion depth (mixing depth) increased by about the same magnitude as did the average Secchi depth. However, the total heat content of the lake did not show a consistent trend to increasing zebra mussel abundance, as it was largely influenced by the temperature of the large water volumes near the surface, which were in turn affected by weather conditions. Concurrent with the thermal structure change, the dissolved oxygen structure also changed over three years, though to a lesser extent. The changes in oxygen stratification pattern were reflected by increased oxygen concentrations in the metalimnion and a lowered depth of 3 mg l−1 DO isopleth. These observed changes were likely attributed to increased water mixing depth, metalimnion photosynthesis and reduced oxygen consumption by organic matter. With increased epilimnion thickness and improved oxygen conditions in the metalimnion, the habitable space for aquatic macro-organisms (including fish) expanded substantially. Our results suggest that the indirect impacts of zebra mussels on small lake stratification patterns may have much broader implications than do the direct trophic interactions to the whole ecosystem.
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  • 40
    ISSN: 1573-5117
    Keywords: nutrient flux ; nitrogen ; phosphate ; tidal flats ; temperature ; geographical comparison
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During an annual cycle, flux rates of oxygen, nitrate, nitrite, ammonium, phosphate and silicate were measured in light and dark bell jars at three sites in Ria Formosa (Algarve, Portugal) enclosing either a natural macrophytic community (macroalgae on sand or mud, a seagrass bed of Zostera noltii) or bare sediments. The results are compared with a preceeding study in which the same bell jar technique has been applied in the Sylt-Rømø Bay of the northern Wadden Sea. Nitrate flux was mainly directed from the water column to the benthic communities in Ria Formosa, as well as in the Sylt-Rømø Bay. However, nitrate uptake was higher in the northern, more eutrophic study area. In Ria Formosa, nutrient concentrations were lower than in the Sylt-Rømø Bay possibly due to strong water exchange with Atlantic waters. High temperatures and strong insolation had a greater impact on nitrate fluxes in Ria Formosa than in the Sylt-Rømø Bay. Bioturbating macrofauna increased ammonium efflux in the Sylt- Rømø Bay while this effect was not as pronounced in the Ria Formosa study sites. Benthic phosphate uptake dominated in the Ria Formosa and was correlated to initial phosphate concentrations in incoming waters. At both study sites, oxygen and nutrient fluxes were correlated with temperature. Additionally, flux rates were strongly influenced by biotic components and levels of eutrophication. A literature survey showed that mainly in temperate regions, material fluxes increase with temperature, whereas in warmer areas, ammonium and phosphate fluxes between sediment and water were generally lower.
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  • 41
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    Biogeochemistry 48 (2000), S. 21-51 
    ISSN: 1573-515X
    Keywords: carbon cycle ; decomposition ; global change ; soil organic matter ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The world's soils contain about 1500 Gt of organic carbon to a depth of 1m and a further 900 Gt from 1--2m. A change of total soil organic carbon by just 10% would thus be equivalent to all the anthropogenic CO2 emitted over 30 years. Warming is likely to increase both the rate of decomposition and net primary production (NPP), with a fraction of NPP forming new organic carbon. Evidence from various sources can be used to assess whether NPP or the rate of decomposition has the greater temperature sensitivity, and, hence, whether warming is likely to lead to an increase or decrease in soil organic carbon. Evidence is reviewed from laboratory-based incubations, field measurements of organic carbon storage, carbon isotope ratios and soil respiration with either naturally varying temperatures or after experimentally increasing soil temperatures. Estimates of terrestrial carbon stored at the Last Glacial Maximum are also reviewed. The review concludes that the temperature dependence of organic matter decomposition can be best described as: d(T) = exp[3.36 (T − 40)/(T + 31.79)] where d(T) is the normalised decomposition rate at temperature T (in °C). In this equation, decomposition rate is normalised to ‘1’ at 40 °C. The review concludes by simulating the likely changes in soil organic carbon with warming. In summary, it appears likely that warming will have the effect of reducing soil organic carbon by stimulating decomposition rates more than NPP. However, increasing CO2 is likely to simultaneously have the effect of increasing soil organic carbon through increases in NPP. Any changes are also likely to be very slow. The net effect of changes in soil organic carbon on atmospheric CO2 loading over the next decades to centuries is, therefore, likely to be small.
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  • 42
    ISSN: 1573-5028
    Keywords: cell cycle ; kinematic analysis ; leaf development ; light ; temperature ; water deficit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In planta quantitative studies of cell cycle are necessary for examining the role of cell division in the response of plants to environmental conditions and to analyse the behaviour of transformed plants in this context. We present and discuss non-intrusive kinematic methods which allow estimating the duration of cell cycle with a high spatial resolution in the leaf. Different methods are proposed and discussed for monocotyledons and dicotyledons, and compared with methods involving the use of chemicals. In monocotyledon leaves, cell division is restricted to a limited zone near the leaf insertion point, twice as long in the mesophyll as in the epidermis. In dicotyledons, cell division occurs in the whole leaf with a uniform and constant cell cycle duration for a determinate number of cell cycles, representing about half of leaf development. Over several experiments, this number is well conserved in a given leaf zone in the absence of stresses, but larger near the leaf base than near the leaf tip. After that, cell cycle duration increases because cells are progressively blocked in G1 while the durations of S-G2-M phases do not change with time. Leaf temperature affects neither the distribution of nuclei in each phase of the cycle nor the number of cell cycles in a leaf. Water or light deficits both cause a partial blockage of nuclei in G1 during the stress only, thereby increasing cell cycle duration and decreasing final cell number. These results suggest that a strong developmental programme drives cell division in leaves, so a simple framework allows analysis of temporal patterns, of spatial gradients and of the effect of environmental conditions.
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  • 43
    ISSN: 1573-5168
    Keywords: chloride cells ; Epinephelus coioides ; grouper ; Na+,K+-ATPase activity ; salinity ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The activity of the enzyme Na+,K+-ATPase and morphological changes of gill chloride cells in grouper, Epinephelus coioides larvae and juveniles were determined 6–48 h after abrupt transfer from ambient rearing conditions (30–32 ppt, 26.5–30 °C) to different salinity (8, 18, 32, 40 ppt) and temperature (25, 30 °C) combinations. Na+,K+-ATPase activity in day 20 larvae did not change at salinities 8–32 ppt. Activity decreased significantly (P 〈0.01) after exposure to 40 ppt at 25–30 °C, which was accompanied by an increase (P 〈0.05) in density and fractional area of chloride cells. Enzyme activity in 40 ppt did not reach a stable level and larvae failed to recover from an osmotic imbalance that produced a low survival at 25 °C and death of all larvae at 30 °C. Enzyme activity and chloride cell morphology in day 40 groupers did not change in 8–40 ppt at 25 °C and 8–32 ppt at 30 °C. A significant decrease and a subsequent increase in Na+,K+-ATPase activity in 40 ppt at 30 °C was associated with the increase in chloride cell density resulting in an increased fractional area but a decreased cell size. Enzyme activity and chloride cells of day 60 grouper were unaffected by abrupt transfer to test salinities and temperatures. These results demonstrate that grouper larvae and juveniles are efficient osmoregulators over a wide range of salinities. Salinity adaptation showed an ontogenetic shift as the larvae grew and reached the juvenile stage. This development of tolerance limits may reflect their response to actual conditions existing in the natural environment.
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  • 44
    ISSN: 1573-5168
    Keywords: Atlantic cod ; temperature ; melatonin ; photoperiod
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study investigated the effects of photoperiod and temperature on plasma melatonin secretion in Atlantic cod (Gadus morhua L.). Initial work confirmed the presence of a diel profile of melatonin synthesis, with elevated levels during the dark phase. Unusually for fish, the peak in plasma melatonin occurred towards the end of the dark phase, which is indicative of a type `A' melatonin profile. When exposed to 60 hours of continuous darkness a clear endogenous rhythm of melatonin synthesis was observed, which continued for 4 cycles with a periodicity which, approximated to 24 h. When acclimated to varying temperatures (4, 8, 12 or 16 °C) no variation in melatonin production was seen, however, body size appeared to be an important influence, with the smallest fish exhibiting significantly higher levels of dark phase melatonin. Finally, the application of additional night-time illumination to cod maintained in sea cages i.e. without blackout, did not significantly reduce dark phase plasma melatonin, suggesting that cod are less sensitive to photoperiod manipulation in cages than salmonids.
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  • 45
    ISSN: 1573-5168
    Keywords: cortisol ; ACTH ; α-MSH ; GH ; head kidney ; pituitary ; temperature ; stress ; Sparus aurata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study investigated the effects of a drop in water temperature (18 °C to 9 °C in 24 h) on the pituitary and interrenal hormones of the gilthead sea bream Sparus aurata. The in vitro sensitivity of the interrenal tissue to ACTH, plasma levels of cortisol, ACTH, α-MSH, GH, glucose, lactate and ions were determined. In vitro ACTH, stimulated the release of cortisol from isolated interrenal glands from control gilthead sea bream in a concentration dependent fashion. However, the interrenal cells were less sensitive to ACTH as soon as 24 h following the onset of the temperature drop. At this time, plasma cortisol and ACTH levels were raised, and plasma GH concentrations were decreased, whereas no significant changes were found in plasma α-MSH. After 96 h plasma ACTH levels had recovered whereas plasma cortisol levels were still higher than controls after 8 days of the beginning of the experiment. Interrenal sensitivity had recovered after 8 days. The results may help to clarify the relationship between the stress response and the aetiology of the winter syndrome in sea bream.
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  • 46
    ISSN: 1573-6857
    Keywords: altitude ; clines ; latitude ; phenotypic variability ; temperature ; Zaprionus indianus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We analyzed natural populations of Zaprionus indianusin 10 Indian localities along a south-north transect (latitude: 10–31°3 N). Size traits (body weight, wing length and thorax length) as well as a reproductive trait (ovariole number) followed a pattern of clinal variation, that is, trait value increased with latitude. Wing/thorax ratio, which is inversely related to wing loading, also had a positive, but non-significant correlation with latitude. By contrast, bristle numbers (sternopleural and abdominal) exhibited a non-significant but negative correlation with latitude. Sex dimorphism, estimated as the female/male ratio, was very low in Z. indianus, contrasting with results already published in other species. Genetic variations among populations were also analyzed according to other geographic parameters (altitude and longitude) and to climatic conditions from each locality. A significant effect of altitude was found for size traits. For abdominal bristles, a multiple regression technique evidenced a significant effect of both latitude and altitude, but in opposite directions. Genetic variations were also correlated to climate, and mainly with average year temperature. Taking seasonal variations into account failed however to improve the predictability of morphometrical variations. The geographic differentiation of Z.indianusfor quantitative traits suggests adaptive response to local conditions, especially to temperature, but also reveals a complex situation according to traits investigated and to environmental parameters, which does not match results on other drosophilid species.
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  • 47
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    World journal of microbiology and biotechnology 16 (2000), S. 297-301 
    ISSN: 1573-0972
    Keywords: Anaerobic bacteria ; growth ; protease ; psychrotrophs ; temperature ; volatile fatty acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Five anaerobic proteolytic bacteria were isolated from water bodies of Leh, India, where the ambient temperature varies from −25 to 25 °C. Isolates showed growth at all temperatures ranging from 5 to 37 °C except SPL-4 and SPL-5 which showed no growth at 5 °C. The cultures could grow and produce proteases on various protein substrates and the yield varied with the substrates. Two of the cultures showed the presence of spores. Acetate was the dominant VFA during hydrolysis of protein substrates.
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  • 48
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    World journal of microbiology and biotechnology 16 (2000), S. 571-572 
    ISSN: 1573-0972
    Keywords: Anaerobes ; hydrogen sulphide ; rubber stoppers ; sulphate reduction ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Common black rubber stoppers, made from natural rubber and styrene–butadiene, may cause a loss of hydrogen sulphide from aqueous media and impede the growth of sulphate-reducing bacteria under thermophilic conditions.
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  • 49
    ISSN: 1573-0972
    Keywords: Carbondioxide ; fungi ; oxygen ; Rhizopus ; solid-substrate fermentation SSF ; tempe modelling ; temperature ; water activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Rhizopus microsporus var. microsporus and var. oligosporus are used in the manufacture of various Asian fermented foods (tempe, black oncom, sufu). In view of solid-substrate fermentation (SSF) control, mycelial growth of strains of both varieties was tested for sensitivity to fluctuations of temperature, water activity and interstitial gas composition. This was achieved by measuring radial growth as well as biomass dry weight of pre-germinated microcolonies on defined media. The optimum conditions were temperature 40 °C, a w 0.995 and a gas composition of air for the growth of both strains on a model medium. Whereas radial growth rates of var. microsporus and var. oligosporus were similar, biomass growth rates of var. oligosporus were higher than those of var. microsporus under optimum conditions. The temperature-dependent growth of Rhizopus spp. at a w 〉 0.98 could be described by the Ratkowsky Equation. Carbon dioxide (5–10% v/v) inhibited the growth of Rhizopus spp. at non-limiting levels of oxygen. The two strains were able to grow at low (0.5% v/v) oxygen levels, but the mycelial density was rather low. No interrelation of water activity and gas composition was observed, but at high water activity the fungi were more sensitive to changes of temperature. The implications for process control are discussed.
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  • 50
    ISSN: 1573-0662
    Keywords: monoterpene emission ; Mediterranean pine ; seasonal variation ; light ; temperature ; algorithms ; model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Current inventories of terpenes released from vegetation consider only the short-term influences of light and temperature on emissions to simulate temporal variation during the year. We studied whole canopy emissions from young Pinus pinea during a 15-month enclosure in greenhouse chambers and examined data for other long-term influences. Mean daytime emission rates strongly increased during spring, reached an annual maximum of ≈ 200 pmol m−2 total needle area s−1 (1.1 μg g−1 leaf dry weight h−1) between mid June and mid August, strongly declined in fall and reached an annual minimum of ≈ 1 pmol m−2 s−1 (0.006 μg g−1 h−1) between January and February. Normalization to standard temperature and light conditions did not change the annual time course of emissions, but reduced summer to winter ratio from a factor of 200 to about 45. Seasonal variation was characterized also by changes in terpene composition: among the six main compounds, three (t-β-ocimene, linalool, 1.8-cineol) were exclusively emitted during sunlit hours in the main vegetation period, whereas the other (limonene, α-pinene, myrcene) were emitted day and night and throughout the seasons. The results suggest that different terpene sources in P. pinea foliage exist and that a great part of the annual emission course observed here results from seasonal influences on these sources. A global model to simulate plant emissions is proposed, which accounts for seasonal influences on emissions in addition to the short-term effects of temperature and light. The model is tested on field data and discussed for its general application.
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  • 51
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    Experimental and applied acarology 24 (2000), S. 579-596 
    ISSN: 1572-9702
    Keywords: Tetranychus urticae ; ambulatory dispersal ; temperature ; humidity ; mortality ; emigration ; immigration ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a greenhouse and in an open field, aspects of aerial and ambulatory dispersal of the phytoseiid mite, Neoseiulus fallacis (Garman) were studied with a focus on events that would occur after aerially dispersing mites had landed on soil or associated substrates. We measured recovery of predators on lima bean plants (Phaseolus lunatus L.) that were infested with the two-spotted spider mite, Tetranychus urticae Koch. Factors thought to affect movement and colonization were distance to a receiver unit from a release (landing) point, intervening soil surfaces such as clods, gravel, fine soil and grass, and management of soil surfaces such as mulching, watering or both. In the field, the effect of distance (0.11–1.76 m) from a landing point to a receiver unit was significant, with a negative log-linear relationship. Soil surfaces such as clods and management actions such as watering with mulching allowed for more capture of predators on bean plants with prey than did other treatments. Environmental conditions greatly affected survival of N. fallacis.Predators in the field that were present on bare soil suffered high mortality (ca. 90%) at fluctuating daytime conditions of 26.4 ± 4.8°C and 56 ± 13.4% RH. Predators only suffered 10% mortality in the greenhouse under the same setting, but under more controlled and favorable environmental conditions. Effects of environmental conditions, mode of dispersal and implications to biological control are discussed.
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  • 52
    ISSN: 1573-5095
    Keywords: Coastal Plain sites ; Pinus echinata Mill. ; P. taeda L. ; precipitation ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Seed production was monitored during24 years using seed-collection traps inloblolly–shortleaf pine (Pinus taeda L.–P.echinata Mill.) stands located in southeast Arkansas,north-central Louisiana, and southwest Mississippi onthe southeastern Coastal Plain, USA. Sound seedproduction was correlated with mean monthlyprecipitation and temperature from National Oceanicand Atmospheric Administration weather stationslocated near the seed-collection areas to determinethe potential of weather factors in forecasting pineseed crops. Correlations were restricted to threecritical periods in the pine reproductive cycle –strobili primordia differentiation, pollination, andfertilization. The most important (P ≤ 0.05)variables correlated with pine seed production for combined locations were cumulative precipitation (r = +0.60) during July, August, and September at 27 to 25 months before seed dispersal and mean temperature (r = −0.45) in August at 26 months before seed dispersal. Because multiple environmental factors can negatively impact pine seed development during the two yearsfollowing strobili primordia differentiation,seed-production forecasts based on weather variablesshould be verified by on-site cone counts during thesummer preceding autumn seed dispersal.
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  • 53
    ISSN: 1573-5036
    Keywords: Acacia ; Libya ; root-nodulating bacteria ; salinity ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Thirty isolates of root-nodulating bacteria obtained from Acacia cyanophylla, A. karroo, A. cyclops, A. tortilis (subsp.raddiana), Faidherbia albida and Acacia sp., grown in different regions of Libya, were studied by performing numerical analysis of 104 characteristics. Three fast- and one slow-growing reference strains from herbaceous and woody legumes were included. Five distinct clusters were formed. The fast-growing reference strains were separated from the isolates whereas the slow-growing was included in cluster 4. With the exception of one cluster, the majority of clusters were formed regardless of the host plant or site of origin. Based on plant tests, generation times, acid production and carbon utilization the isolates were diverse (fast and slow-growing isolates). Like slow-growing isolates, most of the fast-growing isolates appeared to be non-specific, nodulated many species from the same genus notably F. albida, known to nodulate only with slow-growing strains. Most clusters grew at temperatures 35 °C and 37 °C; some grew at temperatures above 40 °C. The majority of isolates grew at acid and alkaline pH and only one isolate grew below pH 4. Most isolates were able to utilize many amino acids as nitrogen sources and to reduce nitrate. Urea was hydrolysed by all clusters. Monosaccharides and polyols were used by slow and fast-growing isolates as the only carbon sources whereas assimilation of disaccharides varied: Some isolates, like slow-growing isolates, failed to utilize these carbon sources. Most isolates were unable to utilize polysaccharides. Regarding tolerance to NaCl on agar medium, the majority of isolates were unable to grow at a concentration of 2% NaCl, but some were highly resistant and there was one isolate which grew at 8% NaCl. Most isolates were resistant to heavy metals and to antibiotics.
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  • 54
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    Plant cell, tissue and organ culture 61 (2000), S. 59-67 
    ISSN: 1573-5044
    Keywords: alar ; in vitro plantlet ; mannitol ; nitrogen ; rooting ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The importance of leaf area of in vitro propagated potato (Solanum tuberosum L.) plantlets for further growth during acclimatisation and the after-effects of in vitro treatments on growth were examined. The in vitro treatments included different levels of alar, nitrogen or mannitol or different temperatures during the last in vitro phase, the rooting phase. Leaf area or ground cover was recorded one day after planting to soil and at the end of the first phase of ex vitro growth, the acclimatisation phase. Regression analysis showed that leaf area of a transplant at the end of acclimatisation phase was positively influenced by leaf area of the same plantlet at the beginning of the phase. The relative increase in leaf area during acclimatisation (increase/early leaf area) was linearly related to the inverse of the early leaf area, indicating almost comparable relative increases for plantlets having larger early leaf areas, but more variable responses for plantlets having smaller early leaf areas. In vitro treatments mainly affected leaf area of transplants through their effects on early leaf area. Adding alar, reducing nitrogen and reducing temperature increased leaf area. Reducing mannitol increased ground cover. A lower nitrogen concentration and higher temperature in some cultivars had slight negative effects on the relative increase in leaf area after acclimatisation. For nitrogen these negative effects were less significant than the positive effects through early leaf area. Results stress the importance of manipulation of leaf area in vitro to enhance plant performance in later stages of growth.
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  • 55
    ISSN: 1573-5117
    Keywords: urban runoff ; in situ bioassay ; Gammarus minus ; heavy metals ; water quality ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Thompson Run, a headwater stream in central Pennsylvania (U.S.A.), supports an impaired macroinvertebrate community downstream of the outlet of a detention pond that receives urban runoff. To determine if toxicity from the metals or other pollutants in urban runoff contributed to impairment, we exposed adult, male Gammarus minus to urban runoff during a 42-day in situ bioassay that included 12 rain events. Test animals were collected from a site upstream of the detention pond outlet using two methods: precopula pair separation and sieving. Water quality, temperature and tissue metal concentrations were measured during the bioassay. The survival of precopula G. minus was lower (p=0.048) at a site downstream of the detention pond outlet compared to a site upstream of it, but the survival of sieved G. minus was not different between sites (p=0.803). Large hourly increases in temperature (up to 6.6 °C) and major reductions in water quality including order of magnitude increases in suspended materials (measured as turbidity) and the concentrations of copper, zinc and lead occurred downstream of the detention pond outlet during stormflow (i.e. following rain events). In contrast, changes in temperature and water quality were minor upstream of the pond outlet throughout the bioassay. Copper and cadmium concentrations in leaf samples and copper, zinc and lead concentrations in G. minus samples were significantly higher downstream of the pond outlet than they were upstream of it. Despite harsh conditions downstream of the pond outlet (i.e. metal contamination, inputs of suspended materials and rapid temperature increases), the in situ bioassay did not convincingly demonstrate that urban runoff was toxic to adult, male G. minus.
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  • 56
    ISSN: 1573-3025
    Keywords: aerobiology ; airborne pollen ; León (Spain) ; lower atmosphere ; meteorology ; mixing ratio ; relative humidity ; tethered balloon ; temperature ; wind speed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study was undertaken in order to understand thebehaviour of airborne pollen grains, namely therelationship between their concentrations andconcomitant meteorological parameters, at differentaltitudes (ground level, 200, 400 and 600 m) of thelower atmosphere and its daily variations over onesite (the experimental farm of the University ofLeón). The experimental design involved a tetheredballoon (2.25 m3), an ADAS remote meteorologicalstation and an original radio controlled three headedpollen and spore sampler (called GABIS) using theRotorod design. Each head sampled a differentaltitude, while two control samples were taken atground level. Twenty-one takeoffs could be realized inthe 5 weeks period between end of May and end of June1997. Sampling was done early in the morning and sampling time at each altitudewas of 15 minutes. Results show that 45 differenttypes of pollen grains could be collected at this timeof the year and that significant variations could beobserved in the behaviour of the pollen cloud on a dayto day basis, probably because of differentmeteorological situations. Contrary to what isgenerally believed, pollen was in most cases moreabundant at higher altitude – on average by 30% ascompared to ground level – making evident anaerobiological layer of transport at about 500 m aboveground. This was especially the case for trees (Quercus and Castanea). The atmosphere MixingRatio was the most explicative factor at 200 m, whiletemperature dominated significance analysis at both400 and 600 m.
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  • 57
    ISSN: 1573-2932
    Keywords: diffusion rate ; migration ; pH ; temperature ; total dissolved solids ; unplasticized PVC pipes ; vinyl chloride monomer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The migration of vinyl chloride monomer (VCM) from unplasticizedpolyvinyl chloride (uPVC) pipes was investigated using locallymanufactured pipes. Specimens of 33 cm long were used throughoutthe research. The investigation was carried out under differentconditions of water temperature, pH and total dissolved solidsconcentration and at different durations of exposure. The VCMconcentration in the water was evaluated using the gaschromotography (GC)/head-space technique. A VCM concentration ofmore than 2.5 ppb was detected after 30 days of exposure at45 °C. The initial VCM concentration in the uPVC pipewas predicted using equations derived from Fick's first law ofdiffusion. Water tenperature did not affect the migration ofVCM, unless it was raised to high values (i.e. 45 °C).Total dissolved solids (TDS) and pH of water were found toaffect the release of VCM from uPVC pipes. Diffusion rate of VCMwas predicted as a function of pH or TDS values.
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  • 58
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    Environmental monitoring and assessment 60 (2000), S. 337-357 
    ISSN: 1573-2959
    Keywords: cellulose ; charcoal kiln ; decomposition ; herb seeds ; moisture ; respiration ; smoke pollution ; soil ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Long-term charcoal production in small private charcoal kilns (CK) in Eastern Bieszczady Mts. (SE Poland) can cause local smoke contamination of the ambient forest environment. Responses of model soil systems, contaminated or not contaminated by CK smoke, to contrasting combinations of hydrothermic regimes were compared in laboratory microcosms (respiration of soil community, decomposition rate of soil organic matter and cotton stripes, herb seeds germination were studied). The majority of the obtained data show a markedly higher level of soil biological activity in the CK versus the control series. In some cases CK and control soil systems show different patterns of reactions to the tested combinations of microclimate regime. These phenomena should at least partly be attributed to the effects of CK pollution.
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  • 59
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    Environmental monitoring and assessment 61 (2000), S. 285-291 
    ISSN: 1573-2959
    Keywords: adsorption ; NO2 ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The sodium arsenite method developed by Jacobs andHochheiser is one of the most widely used manualmethods for nitrogen dioxide (NO2) monitoring inambient air, particularly in developing countries. Asreported, the method gives 82% NO2 absorptionefficiency (NAE) in the concentration range from 40 to750 μg/m3, when only one impinger tube isemployed in the sampling train at a flow rate of 0.2lpm and for 24 h sampling duration. Accordingly,a uniform correction factor (0.82) is used indenominator to calculate the ultimate concentration ofNO2 in ambient air.In the present investigation, the effect oftemperature on absorption efficiency of NO2 isstudied employing four impinger tubes in series tocollect the maximum NO2 generated in the gasstream. The study conducted at 16, 26 and 36 °Ctemperatures shows maximum absorption efficiency(average) of 87.8% at 26°C in 1st impingertube. At lower and higher temperatures, it is foundconsiderably less. A suitable correction factor,therefore, must be applied to estimate actual NO2concentration in ambient air using arsenite method, intropical countries like India, where atmospherictemperature variations are large (less than 5°Cin winter and more than 45°C in summer).
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  • 60
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    Studia geophysica et geodaetica 44 (2000), S. 442-459 
    ISSN: 1573-1626
    Keywords: temperature ; groundwater ; sedimentary basin ; exploitation ; transient effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Abstract The subsurface temperature field was studied on a set of 46 borehole logs measured in the vicinity of uranium deposits in the Bohemian Cretaceous Basin. Vertical variations of the steady state temperature and the temperature gradient are governed by thermal conductivity which strongly varies in dependence on lithology. Large departures from undisturbed temperature detected in many holes are associated with uranium mining. A positive anomaly is observed in leaching fields where large amounts of acid are injected into the uranium-bearing Cenomanian. A negative anomaly is linked to the operation of hydraulic barriers which enclose the mining area and helps to contain pollution by pumping clean water into the Cenomanian aquifer. The spatial distribution of the observed temperature anomalies helps to map the migration of the fluids used in both processes. The temperature disturbance is propagated from the Cenomanian aquifer up through overlying impermeable sediments. The good fit of transient conductive models to the measured temperatures rules out heat advection and hence upward water flow towards and contamination of the upper Middle Turonian aquifer in the vicinity of the holes studied.
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  • 61
    ISSN: 0219-1032
    Keywords: c-Fos ; Dopamine ; D1 ; Hippocampus ; Rat ; Synaptic Plasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract While dopamine is likely to modulate hippocampal synaptic plasticity, there has been little information about how dopamine affects synaptic transmission in the hippocampus. The expression of IEGs including c-fos has been associated with late phase LTP in the CA1 region of the hippocampus. The induction of c-fos by dopaminergic receptor activation in the rat hippocampus was investigated by using semiquantitative RT-PCR and immuno-cytochemistry. The hippocampal slices which were not treated with dopamine showed little expression of c-fos mRNA. However, the induction of c-fos mRNA was detected as early as 5 min after dopamine treatment, peaked at 60 min, and remained elevated 5 h after treatment. Temporal profiles of increases in c-fos mRNA by R(+)-SKF-38393 (50 μM) and forskolin (50 μM) were similar to that of dopamine. An increase in [cAMP] was observed in dopamine-, SKF-, or forskolin-treated hippocampal slices. By immunocytochemical studies, control hippocampal cells showed little expression of c-Fos immunoreactivity. However, when cells were treated with dopamine, an increase in the expression of c-Fos immunoreactivity was observed after treatment for 2 h. The treatment of hippocampal neurons with R(+)-SKF38393 (50 μM) or forskolin (50 μM) also induced a significant increase in c-Fos expression. These results indicate that the dopamine D1 receptor-mediated cAMP dependant pathway is associated with the expression of c-Fos in the hippocampal neurons. These data are consistent with the possible role of endogenous dopamine on synaptic plasticity via the regulation of gene expression. Furthermore, these results imply that dopamine might control the process of memory storage in the hippocampus through gene expression.
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  • 62
    ISSN: 1573-2932
    Keywords: microalgal communities ; photosynthesis ; temperature ; thermal pollution ; tropical coast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The influence of thermal discharges on thephytoplankton community from a coastal zone of theGulf of Mexico was evaluated through their structureand photosynthetic behaviour focusing on responses tochanges in light and temperature. Biological andphysicochemical parameters were measured over a periodof two years in an area with permanent hot waterdischarges from a thermoelectric plant. Thetemperature in the sampling area ranged from 23.5 to36 °C with differences between the coldest andthe hottest station from 5.3 to 9.2 °C.Photosynthetically active radiation (PAR) were reducedin the discharge area water column, due to turbulence.One hundred and one different taxa were identifiedwith a strong predominance of Diatoms. The chlorophylla concentration ranged from 0.3 to 6.1 μgL-1, with highest values of thephaeophytin:chlorophyll ratio found at the hottest station.The community structure did not show significativedifferences among sampling stations with respect totemperature variations. However, in the algalassemblages influenced by thermal discharges, it waspossible to observe alterations in the photosynthesisbehaviour. Phytoplankton response to short termphotosynthesis experiments was segregated according tocomposition and origin of microalgal assemblages.Samples with larger heterogeneous composition had moreconsistent oxygen production responses. Algalcommunities exposed to hot effluent showed differentdegrees of photosynthesis rate reduction,higher light requirements (〉500 μE m2 s-1)and lower temperature (25 °C) to achieve Pmaxthan algae sampled in sites without such exposure.
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  • 63
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    Water, air & soil pollution 123 (2000), S. 337-352 
    ISSN: 1573-2932
    Keywords: bleaching ; bacterial infection ; coral ; Oculina ; temperature ; toxin ; zooxanthellae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Bleaching in stony-corals is the result of disruption of symbiosis between the coral hosts and photosynthetic microalgal endosymbionts (zooxanthellae). Coral bleaching events of unprecedented frequency and global extent have been reported during the last two decades. Recently, we demonstrated that bleaching of the coral Oculina patagonica in the Mediterranean Sea is caused by the bacterium Vibrio shiloi, when seawater temperature rises and allows the bacterium to become virulent. The first step in the infection process is host-specific adhesion of V. shiloi to O. patagonica via a β-galactoside receptor on the coral surface. The bacterium then penetrates into the coral tissue and produces extracellular materials which rapidly inhibit photosynthesis of zooxanthellae and bleach and lyse the algae. The inhibition of pothosynthesis is due to a low molecular weight, heat stable toxin and ammonia. Bleaching and lysis are due to a heat-labile, high molecular weight materials, probably lytic enzymes. Elevated temperature induces different virulence factors within the infectious agent of the disease, V. shiloi. Adhesion was found to be temperature-regulated. When the bacteria were grown at 16°C there was no adhesion to corals maintained at either 25°C or 16°. However, when the bacteria were grown at 25°C they adhered avidly to corals maintained at 16°C and 25°C. In addition, the production of lytic enzymes and the photosynthesis inhibitor was also found to be temperature dependent. Production of the latter toxin was ten times greater at 29°C than at 16°C, and extracellular protease was 5-fold higher in cultures grown at 29°C than at 16°C. The data presented here suggest an explanation for the correlation between elevated seawater temperatures and seasonal coral bleaching.
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  • 64
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    World journal of microbiology and biotechnology 16 (2000), S. 607-612 
    ISSN: 1573-0972
    Keywords: Aflatoxin ; apple ; fruit oils ; fungi ; patulin ; sodium hypochlorite ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Aspergillus flavus, A. niger, Penicillium expansum and Rhizopus stolonifer were the most frequently isolated fungi from healthy apple fruits. Alternaria alternata was the most common organism of rotten apple fruits, followed by A. niger, A. flavus, P. expansum and R. stolonifer. The prevalent type of decay, brown rot lesion, is caused by R. stolonifer followed by A. flavus, A. niger, A. alternata and P. expansum. Sodium hypochlorite had good curative properties against fruit rots. The main natural mycotoxins produced in rotten apple were patulin and aflatoxins. The optimum temperature for patulin production by P. expansum was 15 °C after 15 days. Complete inhibition of patulin formation was attained using 0.2% lemon oil and 〉 90% inhibition using 0.05% lemon and 0.2% orange oils. Also significant inhibition (〉 90%) of aflatoxin production was observed with 0.2% lemon oil.
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  • 65
    ISSN: 1573-2711
    Keywords: solid lubricants ; lubricious oxides ; TiO2 ; rutile ; oxygen stoichiometry ; Magnéli phases ; tribometry ; friction ; wear ; shear strength ; temperature ; atmosphere ; extreme environment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In part I of this paper series, wide temperature range SEM-tribometric results generated in vacuum and various partial pressures of oxygen are combined with relevant literature data to examine a hypothesis correlating the oxygen stoichiometry of the Ti n O2n−1 Magnéli phases of the rutile polymorph of titania with their tribological behavior. Single-crystal and polycrystalline rutile specimens of narrow stoichiometry ranges were sliding against α-SiC and themselves. The surface shear strength changes were determined as a function of the thermal–atmospheric test environment, and the shear strength values were estimated by the coefficients of friction, the real area of contact and the published yield strength of rutile. The data appear to be sufficient and sufficiently reliable to confirm the accuracy of the hypothesis. The tendency of the rutile stoichiometry (ergo the friction) to shift as a function of temperature and partial pressure of oxygen causes this material to be thermo-oxidatively unstable for tribological applications in extreme environments. In part II, a study is described to formulate oxidatively more stable Magnéli phases by Cu-doping, and test the new materials by SEM tribometry using a procedure used for pure rutile here in part I. By employing this doping methodology similar to creating high-temperature superconductive oxides in part II, some feasibility of producing oxidatively stable, lubricious oxides with acceptably low wear rates is indicated.
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  • 66
    ISSN: 1573-2711
    Keywords: AFM ; force ; friction ; adhesion ; molecular water layer ; temperature ; capillary forces ; PMIRRAS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Under ambient conditions, a water film is always present on a silica substrate and generates additional capillary forces between the nanotip and the studied surface. In the present paper, we report AFM measurements of pull-off and friction forces as a function of the temperature and a comparative FTIR spectroscopy study. The AFM results show a net decrease of the forces as the temperature increases, while the IR spectroscopy indicates that the liquid film is removed at high temperature. Consequently, we deduce that a liquid neck is created between the tip and the surface and that the forces measured are mostly capillary forces. The present work shows that temperature studies with AFM can be a useful way to probe the influence of the capillary force in turn to characterize surface properties.
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  • 67
    ISSN: 1573-2711
    Keywords: solid lubricants ; lubricious oxides ; TiO2 ; rutile ; oxygen stoichiometry ; Magnéli phases ; tribometry ; friction ; wear ; shear strength ; temperature ; atmosphere ; extreme environment ; molecular engineering ; cation doping ; aliovalency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract As a follow-up to the work described in part I of this paper series, a preliminary study was conducted with polycrystalline rutile TiO−x to render its friction and wear performance independent of the environment. The main goal was to confine the most tribologically desirable oxygen stoichiometries of the crystallographic shear-induced Magnéli phases (CSMP) of rutile by doping with cations similar in size and polarizability to the Ti4+, but with lower valences. The resultant chemical expulsion of oxygen from the rutile lattice was intended to generate CSMP free of friction and wear variations caused by changes in the thermal–atmospheric environment. Copper, iron, cobalt and nickel ions were tried as dopants introduced as their stable oxides via a simple ball-milling, hot-pressing and annealing procedure, but only a (Ti + Cu)O1.80 model blend resulted in a desired reaction. A portion of the copper entered the lattice to form a new titanium–copper CSMP, resembling the well-known V3Ti6O17 catalyst equivalent to an undoped rutile CSMP with an O/Ti ratio of 1.89. Although the shear behavior of this new, wear-resistant compound was in accordance with predictions, its friction is higher and more variable than desired for a wide environmental regime lubricant. The preparation technique was only sufficient to demonstrate that oxygen vacancy-induced creation of low-friction CSMP may be possible by doping; it does not appear to be useful for formulating practical, rutile-based lubricious oxides.
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  • 68
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    European journal of plant pathology 106 (2000), S. 77-85 
    ISSN: 1573-8469
    Keywords: Pestalotiopsis sydowiana ; morphology ; pathogenicity ; ericaceous plants ; conifers ; temperature ; pH ; water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Pestalotiopsis isolates obtained from the foliage, stem-base and roots of hardy ornamentals grown on commercial nurseries in the UK were identified and characterised according to pathogenicity and colony morphology. All 18 isolates were identified as Pestalotiopsis sydowiana on the basis of conidia morphology, and confirmation of identification was made by experts at CABI Bioscience. Isolates were pathogenic on the host from which originally isolated. Typical symptoms included foliar browning of foliage and stems, and the presence of black or greenish-black acervuli on diseased tissue. Isolates were not host specific and infected other species of hardy ornamentals. Three colony types on potato dextrose agar were distinguished according to colour and production of acervuli by individual isolates. Three selected isolates of P. sydowiana were characterised by examining the effects of growth media, temperature, pH, and water potential on hyphal extension. Isolates grew well on commonly used growth media, including PDA, Sabouraud dextrose agar (SDA), V8 juice agar (V8), malt extract agar (MEA) and Czapek Dox agar (CDA). The optimum temperature for growth on PDA was in the range 20–25°C, with little or no growth occurring below 5°C or above 30°C. Hyphal extension occurred over a pH range between 2.6–8.6, with optimum values occurring at pH 5.5. In general, decreases in osmotic and matric potential caused a reduction in growth. Hyphal extension on media adjusted osmotically as NaCl ceased between −9.9 and −10.5 MPa. Isolates were more tolerant of osmotic than matric potential, with no growth occurring at −6.5 MPa on media adjusted with polyethylene glycol.
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  • 69
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    BioControl 45 (2000), S. 453-462 
    ISSN: 1573-8248
    Keywords: development ; fecundity ; functional response ; reproductive numerical response ; temperature ; Coccinellidae ; Aphis gossypii ; Scymnus levaillanti
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Development and fecundity of Scymnus levaillanti(Mulsant) were recorded at fiveconstant temperatures ranging from 15 to 35 ± 1 °C in 5 °C increments, 60 ± 5% RHand 16 h of artificial light (5000 Lux). Developmentaltime (egg to adult) of S. levaillantisignificantly decreased with increasing temperatures,ranging from 63.9 days at 15 °C to 11.1 days at35 °C. Development from egg to adult required305.2 DD above a developmental threshold estimated as11.7 °C. Oviposition periods lasted 86.5, 76.1,47.2, and 31.5 days at 20, 25, 30 and 35 °C,respectively. No eggs were deposited at 15 °C.Higher temperatures resulted in shorter generationtimes (TO) and in decreased net reproductiverates (RO) of the coccinellid. S.levaillanti kept at 30 °C produced 0.151females/female/day, the highest per capita rate ofpopulation growth (rm). The `functional response'of larvae and adults of S. levaillanti matcheswell that described by Holling (1959) as Type 2.Daily number of eggs deposited by females increased toa plateau with increasing prey density. Resultsobtained here provide information about the biology ofS. levaillanti, and its feeding capacityindicates that it may act as an important control agent.
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  • 70
    ISSN: 1573-8248
    Keywords: anti-fungal substances ; control ; host plant resistance ; Megalurothrips sjostedti ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The susceptibility of Megalurothrips sjostedtito Metarhizium anisopliae when reared on susceptible, tolerant, and moderately resistant varieties of cowpea at different constant temperatures was evaluated in the laboratory. Insects were exposed either to direct spray of the conidia or to fungus-treated floral tissues. Mortality was significantly higher on the moderately resistant variety at all temperatures compared to the susceptible and tolerant varieties. Correspondingly, lethal time and lethal concentration values were significantly shorter and lower, respectively, on the moderately resistant variety compared to the other varieties, thus indicating that the two control methods are compatible as part of an integrated pest management strategy. Thrips raised on the tolerant variety incurred an exceptionally low level of mortality when the inoculum was sprayed directly on the insects or when the insects were exposed tofungus-treated floral tissues. Observations on the effects of airborne volatiles and crude extracts of this variety revealed an inhibitory effect on fungal germination, colony forming units and growth. This suggests the existence of anti-fungal substances in the tolerant variety.
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  • 71
    ISSN: 1573-8248
    Keywords: adjuvants ; attapulgite ; bentonite ; infectivity ; osmolarity ; pH ; survival ; temperature ; Heterorhabditis bacteriophora ; Heterorhabditis indica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Successful control of insect pests through theapplication of entomopathogenic nematode dauerjuveniles of H. bacteriophora and H.indica can only be achieved when the nematodematerial reaches the end user in good condition.Storage and formulation techniques must provideoptimum conditions to guarantee a maximum survival andinfectivity of the nematodes. Nematode survival wastested at temperatures ranging between 5–25 °C.A maximum survival of H. indica was achieved at15 °C and the highest mortality at 5 °C.H. bacteriophora survived best at 7.5 °Cand least at 25 °C. An increase of the saltconcentration had positive effects on dauer juvenilesurvival in aqueous suspensions. Low pH between 6 and4 reduced the bacterial growth and prolonged survivalof stored dauer juveniles. Of the organic acidsascorbic, benzoic, citric and sorbic acid, onlyascorbic acid had a positive effect on H. indicasurvival. Extracts of the dried spice plants cinnamon,cloves, rosemary and oregano were tested. Enhancementof H. indica survival was recorded for cinnamonand cloves. Survival and infectivity of nematodesstored in attapulgite and bentonite clays and spongewere recorded over several weeks at different storagetemperatures. Infectivity was not influenced by thedifferent formulation materials. When stored insponge at 25 °C nematodes survived less than 1week and the formulation in clay could only prolongthis period for another week. At 5 °C thesurvival of H. bacteriophora in sponge wassuperior to that in clay, whereas H. indicasurvived less well in sponge than in clay at15 °C. Storage in aerated water at 5 °Cfor H. bacteriophora and at 15 °C for H. indica resulted in the lowest mortality. Forstorage at controlled conditions (temperature, pH andosmolarity), aerated water is superior to all othermethods tested and the addition of preservatives willincrease survival.
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  • 72
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    Medical & biological engineering & computing 38 (2000), S. 42-48 
    ISSN: 1741-0444
    Keywords: Bowel sounds ; Rat ; Motility ; Body acoustics ; Signal detection ; Signal characterisation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract This study is aimed at detecting gastrointestinal sounds (GIS) and correlating their characteristics with gastrointestinal (GI) conditions. The central hypotheses are that GIS generation depends on the motility patterns and the mechanical properties of the gut, and that changes in those result in measurable differences in GIS. An animal model which included both healthy rats and those with small bowel obstruction (SBO) was developed. The acoustic bursts, of GIS were detected by amplitude thresholding the signal envelope. Three methods of envelope estimation were proposed and evaluated. Envelope estimation using a Hilbert transform was found to produce the best results in the current application. The duration and dominant frequency of each detected GIS event was estimated and clear differences between healthy and diseased rats were discovered. In the control state, GIS events were found to consistently be of relatively short duration (3–65ms). Although the majority of events in the SBO state had similar short duration, infrequent longer events were also detected and appeared to be pathognomonic. Long duration events (〉100 ms) occurred in each of seven obstructed, but in none of 14 non-obstructed, cases (p〈0.001). It is concluded that GIS analysis may prove useful in the non-invasive, rapid, and accurate diagnosis of SBO.
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  • 73
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    In:  Berlin, 306 pp., Springer, vol. 2, no. XVI:, pp. 1-14, (ISBN: 0-387-30752-4)
    Publication Date: 2000
    Keywords: Textbook of geophysics ; Textbook of geology ; Textbook of mathematics ; Data analysis / ~ processing ; Modelling ; Inversion
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  • 74
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    In:  New York, Springer, vol. 31, no. 3, pp. 2-203, (ISBN 0-87590-533-1)
    Publication Date: 2000
    Keywords: Data analysis / ~ processing ; Error analysis ; Handbook of geophysics ; Handbook of geodesy ; toolbox ; Statistical investigations ; Inversion ; Non-linear effects ; aerial ; images ; Diffraction ; Tomography ; 1214 ; Geodesy ; and ; gravity ; Geopotential ; theory ; and ; determination ; 1224 ; Photogrammetry ; remote ; sensing ; 0902 ; Exploration ; geophysics ; Computational ; methods, ; seismic ; Gruen ; Grun
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  • 75
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    Animal cognition 2 (1999), S. 123-129 
    ISSN: 1435-9456
    Keywords: Key words Face recognition ; Inversion ; Expertise ¶effect ; Matching-to-sample ;  Macaca mulatta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study investigated the face inversion effect in rhesus monkeys (Macaca mulatta). Face stimuli consisted of ten black-and-white examples of unfamiliar rhesus monkey faces, brown capuchin faces, and human faces. Two non-face categories included ten examples of automobiles and abstract shapes. All stimuli were presented in a sequential matching-to-sample format using an automated joystick-testing paradigm. Subjects performed significantly better on upright than on inverted presentations of automobiles, rhesus monkey and capuchin faces, but not human faces or abstract shapes. These results are inconsistent with data from humans and chimpanzees that show the inversion effect only for categories of stimuli for which subjects have developed expertise. The inversion effect in rhesus monkeys does not appear to be face-specific, and should therefore not be used as a marker of specialized face processing in this species.
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  • 76
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    Journal of ornithology 140 (1999), S. 81-86 
    ISSN: 1439-0361
    Keywords: Reed Warbler ; timing of breeding ; spring arrival ; global climate change ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung In einem Untersuchungsgebiet am westlichen Bodensee (Halbinsel Mettnau) zeichnet sich zwischen 1976 und 1997 eine deutliche Zunahme früh ausgeflogener Teichrohrsänger ab, was auf ein früheres Brüten schließen läßt. Weiterhin hat sich die Erstankunft des Teichrohrsängers am Bodensee in den letzten 16 Jahren (1982–1997) im Vergleich zum Zeitraum 1961 bis 1980 um genau eine Woche verfrüht (im Mittel vom 26.4. auf den 19.4.). Während sich zwischen der jährlichen Erstankunft des Teichrohrsängers am Bodensee und der Zahl früh ausgeflogener Jungvögel kein statistisch gesicherter Zusammenhang finden läßt, ist die Temperatur in der ersten Maihälfte ein guter (statistisch signifikanter) Indikator für die Zahl früh ausgeflogener Teichrohrsänger. Die vorliegende Untersuchung zeigt, daß sich offenbar auch Langstreckenzieher an die sich abzeichnende Klimaveränderung anzupassen beginnen.
    Notes: Summary Data from a standardized mist-netting programme (the so-called "MRI-Programm") were used to assess the timing of breeding in Reed Warblers (Acrocephalus scirpaceus) at Lake Constance (South Germany). The number of Reed Warblers fledged early in the season increased significantly between 1976 and 1997 (rs=0.614; p〈0.01). This is most probably due to a long-term increase in spring temperature as suggested by the high correlation between the number of early-fledged Reed Warblers and mean temperature in the first half of May (rs=0.416; p〈0.01). While in the period from 1961 to 1980 the mean date of spring arrival was on the 26th of April, it shifted towards the 19th April from 1981 to 1997. However, the number of early-fledged Reed Warblers and the date of spring arrival are not significantly correlated. The lack of a significant correlation may be due to a number of reasons, for instance early arriving birds do not belong to the local population or there could be an observational bias among years. Yet, the most likely explanation is that the timing of breeding in Reed Warblers is triggered by vegetation growth and food supply rather than by the timing of spring arrival. There is growing body of evidence from this and other studies that the recent climate change is responsible for the shift in both the timing of migration and breeding in birds.
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    Entomologia experimentalis et applicata 93 (1999), S. 149-155 
    ISSN: 1570-7458
    Keywords: Megalurothrips sjostedti ; temperature ; photoperiod ; development ; pre-oviposition ; oviposition ; diapause
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Megalurothrips sjostedti is an economic pest of cowpea in tropical Africa. There are no reports of the effect of temperature on the development of the pest and no diapause has been detected. The developmental rate and reproduction of M. sjostedti was studied under six constant temperatures (14, 17, 20, 23, 26 and 29 °C ) and a photoperiod of L12:D12 in the laboratory. Total developmental time ranged from 33.1 days at 14 °C to 19.2 days at 26 °C. At 29 °C, all larvae died during hatching. Egg, larval and pupal stages required 94.3, 97.1 and 105.3 deg-days (DD) above a threshold of 8.2, 9.1 and 10.4 °C, respectively, to complete development. Total developmental cycle was completed at 163.9 DD above a threshold of 12.6 °C. Adult longevity was lowest (11.1 days) at 29 °C and highest (28.7 days) at 14 °C. At constant temperatures, the highest pre-oviposition period was observed at 29 °C under a photoperiod of L16:D8. Egg production also ceased at this temperature/photoperiod combination. Total fecundity was highest at 26 °C under L10:D14. At cyclical temperatures, pre-oviposition period was longest (12.4 days) at 20/29 °C under L16:D8. Total fecundity was highest (168.4 eggs) at 14/26 °C under L10:D14, and lowest (8.2 eggs) at 20/29 °C under L16:D8. The significance of these findings in the management of M. sjostedti is discussed.
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    Entomologia experimentalis et applicata 90 (1999), S. 25-35 
    ISSN: 1570-7458
    Keywords: Aphis gossypii ; development ; survival ; fecundity ; intrinsic rate of increase ; life table ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Life table parameters of Aphis gossypii Glover (Homoptera: Aphididae) on Gossypium hirsutum L. were determined at six temperatures (10, 15, 20, 25, 30, and 35 ± 0.5 °C) in the laboratory. Relationships of life table parameters with temperature were described with mathematical equations. Development was fastest at 30 °C, with a pre-larviposition period of 4.6 d. Survival to adult was greatest at 25 °C (81%). Fecundity was highest at 25 °C, with a total fecundity of 28.3 nymphs per female and a mean reproductive rate of 3.1 nymphs per female per day. Threshold temperatures for development in the first through fourth instar and the adult were 8.2, 8.0, 7.2, 6.2 and 7.9 °C, respectively. The durations of these stages, expressed as temperature sums above these thresholds, were 24.2, 23.7, 23.0, 25.5 and 168.8 degree-days (D°), respectively. A. gossypii achieved its maximum net reproductive number (24.4 nymphs per female) and greatest intrinsic rate of increase (0.386 d−1) at 25 °C. The high relative rate of population increase at 25 °C results in a daily population increase of 47% and a doubling time of only 1.8 d, illustrating the tremendous growth capacity of A. gossypii populations under favourable conditions. Compared to literature sources, our source of A. gossypii, fed on cotton, showed a comparatively great heat tolerance.
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    Entomologia experimentalis et applicata 93 (1999), S. 297-302 
    ISSN: 1570-7458
    Keywords: smaller fruit tortrix ; Grapholita lobarzewskii ; phenology ; post-diapause development ; temperature ; thermal threshold ; thermal constant ; forecasting ; modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The smaller fruit tortrix, Grapholita lobarzewskii Nowicki, has become a major pest in the recent past in apple orchards north of the Alps. Nevertheless little is known about the biology and the behaviour of this species. The effect of temperature on post-diapause development and survival was studied under controlled conditions in order to establish a basis for the forecasting of adult emergence. Survival was found to be highest at 17 °C and lowest at 11.8 °C. The sex ratio did not differ significantly from 1:1. Based on a linear relationship between temperature and developmental rates, thermal thresholds of 9.6 °C and 9.8 °C were determined for females and males respectively. The thermal constants, i.e., the mean developmental times in physiological time units, were found to be 342 day-degrees for females and 317 day-degrees for males, suggesting a slight protandry. Based on the mean and the variance of the developmental times, a simple temperature-driven phenology model was built using a time-varying distributed delay. The model was validated by visually comparing the predictions with independent observations on adult emergence, and by calculating the temporal deviations of the predictions. In 4 out of 5 years the mean error was less than 3 days. The model was therefore found to give reliable forecasts of the emergence of G. lobarzewskii and can be used to determine the optimal time for the exposure of pheromone traps, the application of pheromone dispensers for mating disruption, and for the timing of insecticide applications.
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  • 80
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    Journal of polymers and the environment 7 (1999), S. 101-108 
    ISSN: 1572-8900
    Keywords: Polylactic acid ; temperature ; respirometers ; soil degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A respirometric system was used to analyze the biodegradation of high molecular weight (120,000 to 200,000 g mol−1) polylactic acid (PLA) plastic films in soil under laboratory conditions. The respirometric system consisted of air-conditioning pretraps, a soil reactor, and a carbon dioxide (CO2) posttrap. A 200-g homogeneous soil mixture of all-purpose potting soil : manure soil : sand [1 : 1 : 1 (w/w)] and 1.5 g of PLA plastic films in 1 × 1-cm2 squares was added to each bottle. The respirometers were placed in a 28, 40, or 55°C water bath for 182 days. Treatments (three replicates) included native corn starch (positive control), polyethylene (Glad Cling Wrap; negative control), and three PLA films: Ca-I (Cargill Dow Polymers LLC, monolayer), GII (Cargill Dow Polymers LLC, Generation II), and Ch-I (Chronopol; monolayer). The degree of polymer mineralization was indicated by the cumulative CO2 liberated from each respirometer. The initial average mineralization rate and total percentage mineralized of the PLA plastic films at 28, 40, and 55°C was 24.3, 41.5, and 76.9 mg/day with a 27, 45, and 70% carbon loss, respectively. No decrease in soil pH was observed after 182 days of mineralization. Hence, increase in soil temperature drastically enhanced the biodegradation of PLA plastic films in soil under laboratory conditions (P 〈 0.0001).
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    Journal of polymers and the environment 7 (1999), S. 83-92 
    ISSN: 1572-8900
    Keywords: Polylactic acid ; temperature ; relative humidity ; degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Three high molecular weight (120,000 to 200,000 g mol−1) polylactic acid (PLA) plastic films from Chronopol (Ch-I) and Cargill Dow Polymers (GII and Ca-I) were analyzed for their degradation under various temperature and relative humidity (RH) conditions. Two sets of plastic films, each containing 11 samples, were randomly hung in a temperature/humidity-controlled chamber by means of plastic-coated paper clips. The tested conditions were 28, 40, and 55°C at 50 and 100% RH, respectively, and 55°C at 10% RH. The three tested PLA films started to lose their tensile properties when their weight-average molecular weight (M w) was in the range of 50,000 to 75,000 g mol−1. The average degradation rate of Ch-I, GII, and Ca-I was 28,931, 27,361, and 63,025 M w/week, respectively. Hence, GII had a faster degradation rate than Ch-I and Ca-I under all tested conditions. The degradation rate of PLA plastics was enhanced by the increase in temperature and relative humidity. This trend was observed in all three PLA plastics (Ca-I, GII, and Ch-I). Of the three tested films, Ch-I was the first to lose its mechanical properties, whereas Ca-I demonstrated the slowest loss, with mechanical properties under all tested conditions.
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    Journal of applied electrochemistry 29 (1999), S. 81-85 
    ISSN: 1572-8838
    Keywords: cupric oxide ; powder ; current density ; temperature ; sodium sulfate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electrosynthesis of cupric oxide powder was carried out on a laboratory scale in an electrochemical cell under various experimental conditions. The electrolysis was appraised in terms of the particle size of the cupric oxide product and the anodic dissolution of the copper electrode. Using a previously determined pH value of 7.50, the other optimum electrolysis operating conditions established were a current density of 4000Am−2, temperature of 353K, and Na2SO4 concentration of 0.5m. The optimum values of current efficiency, cell voltage and specific energy consumption for the electrochemical synthesis of cupric oxide powder were determined.
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  • 83
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    Journal of applied electrochemistry 29 (1999), S. 525-528 
    ISSN: 1572-8838
    Keywords: brine ; chlor-alkali cells ; solubility ; sulfate ions ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
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  • 84
    ISSN: 1573-0417
    Keywords: diatoms ; temperature ; sediment traps ; seasonal succession ; resuspension ; Lake Holzmaar
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The seasonal sedimentation pattern of diatom valves in Lake Holzmaar was investigated during 1995 by deploying sediment traps at three different lake depths. According to the sedimentation pattern, the major reproduction zone of diatoms was restricted to the upper 6 m of the water body. The population growth started late in April and blooms of Cyclotella cf. comensis Grun., which dominates the plankton diatoms, and Fragilaria crotonensis Kitton were collected in traps during June and September, and July, respectively. During summer, the seasonal sedimentation pattern of each taxon, as collected in the upper traps, was reflected in the concentrations in the lowest trap. However, in May and from September onwards, the community composition in the lowest trap and augmented trapping rates suggest both sediment focusing and resuspension of bottom sediments. The temperature signals as recorded by δ18O values of diatom valves should, therefore, reflect integrated temperatures between 0 and 6 m depth. However, temperatures during summer and autumn are expected to be accentuated in the sedimentary record since the isotopic signal is weighted by both the number and the weight-mass of the valves. During summer, the transfer of these signals by the sedimenting diatoms retains the information pattern recorded, while in spring and autumn/winter additional influxes caused by resuspension may somewhat alter those temperature informations. The proxy signals finally stored in the sediments, may, therefore, not precisely represent the successive temperatures currently recorded during 1995 within mid-lake.
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  • 85
    ISSN: 1573-0832
    Keywords: interspecific interactions ; ochratoxin ; Aspergillus ochraceus ; spoilage fungi ; water relations ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The effect of water availability (water activity,aw; 0.995–0.90) and temperature (18–30 °) on in vitro interactions between an ochratoxin producing strain of Aspergillus ochraceus and six other spoilage fungi was assessed in dual culture experiments on a maize meal-based agar medium. Inprimary resource capture of nutrient substrate, A. ochraceus was dominant against many of the interacting species, being able to overgrow and replace A. candidus, and sometimes A. flavus and the Eurotium spp. regardless of aw or temperature. However, with freely available water (0.995 aw) A. alternata and A. niger were dominant, with mutual antagonism between A. ochraceus and A. flavus at 25–30 °C. In the driest conditions tested (0.90 aw) there was also mutual antagonism between A. ochraceus and the two Eurotium spp. Overall, under allconditions tested the Index of Dominance for A. ochraceus was much higher than for other competing species combined suggesting that A. ochraceus wasa good competitive colonist able to replace a numberof other species. However, the growth rate ofA. ochraceus was modified and decreased by the interaction with competitors. Interaction between A. ochraceus and species such as A. alternata (18°C/0.995) and Eurotium spp. (0.995–0.95 and 25–30 °C) resulted in a significant stimulation of ochratoxin production. Theresults are discussed in relation to the effect that environmental factors have on the possible competitiveness of A. ochraceus in the maizegrain ecosystem and the role of ochratoxin in nicheexclusion of competitors.
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  • 86
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    Experimental and applied acarology 23 (1999), S. 669-679 
    ISSN: 1572-9702
    Keywords: Panonychus ulmi ; dipause eggs ; overwintering ; dipause termination ; temperature ; photoperiod
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In apple orchards in northern Greece, females of Panonychus ulmi Koch were found to lay diapause eggs from late August to the beginning of October. The course of diapause termination in the field was determined by transferring diapause eggs during winter and early spring from apple orchards with the varieties ‘Starkinson’ and ‘Firiki’ to short days (LD 8:16) (1992–1996), and long days (LD 16:8) (1994–1995), both at 20 °C. Percentages of diapause termination were very low to zero from October to the beginning of January, then progressively increased throughout January and February. Diapause termination in 50% of the eggs occurred in the first half of February in lowland mite populations irrespective of the year and location from which the eggs originated, and about one month earlier in a population originating from an altitude of 300 m. For each sampling date throughout the winter, the mean number of days required for 50% egg hatch at 20 °C (T50%) was similar under either a long (LD 16:8) or a short (LD 8:16) photoperiod. Diapause eggs collected in October 1995 from two orchards and maintained at 0, 5, 10 and 15 °C for various periods were subsequently transferred to 20 °C and LD 8:16, where TP50% was determined. It was shown that temperature, duration of maintenance at the different temperatures and the orchard from which the eggs originated had a significant effect on T50% and therefore on diapause development. Additionally, in our strains diapause intensity was much weaker than in strains from more northern latitudes and was terminated even without any cold exposure. The variation in diapause intensity in different strains of P. ulmi may have an adaptive significance for this widespread species.
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  • 87
    ISSN: 1432-1211
    Keywords: Key words Class II MHC sequence ; Rat ; Cloning ; RT-PCR ; Polymorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
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  • 88
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    Geotechnical and geological engineering 17 (1999), S. 335-349 
    ISSN: 1573-1529
    Keywords: underground gas storage ; pressure barrier ; fibre shotcrete ; stress ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The paper describes an investigation of pressure barriers (plugs) for an underground gas storage facility which were to be constructed from fibre shotcrete. An extensive measurement program on a test plug was carried out to verify the suitability of fibre shotcrete for this purpose. The results of stress and temperature measurements carried out during the construction of the test plug and during cyclic loading of the plug to a water pressure up to 13 MPa are presented. The measurement program provided information on the stress and temperature development inside the plug body during hydration and hardening and also on the residual tensile stresses at the interface between the plug and the rock mass after the end of hydration. Another important output was information on the quality of the plug-rock mass interface, which was critical for a possible leakage. The results obtained during the cyclic loading of the plug revealed uneven stress distribution at the contact and in the adjacent rock mass. It also provided information on the rate of stress redistribution at the contact and inside the rock mass. The results were used to modify the technology of the shotcrete technique to be applied in the final plugs. The gas storage facility using the modified design has been in trial operation since the end of 1998.
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  • 89
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    Environmental monitoring and assessment 59 (1999), S. 111-119 
    ISSN: 1573-2959
    Keywords: adsorbent concentration ; adsorbent size ; adsorption ; chitin ; pH ; reactive dye ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The adsorption of reactive dye on chitin has been investigated with a view to obtain the design data for batch processing of effluents for dye adsorption. The effect of several factors governing the dye adsorption such as the adsorbent concentration, adsorbent size, temperature and pH have been elicited. Desorption of the dye at different temperatures and pH have also been investigated.
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  • 90
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    Cell & tissue research 296 (1999), S. 235-246 
    ISSN: 1432-0878
    Keywords: Key words Transplantation ; Parkinson’s disease ; CNS fetal development ; CNS differentiation ; Neurotrophic factors ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have previously shown that a combination of the cytokines interleukin (IL)-1, IL-11, leukemia inhibitory factor (LIF), and glial cell line-derived neurotrophic factor (GDNF) can convert rat fetal (E14.5) mesencephalic progenitor cells into tyrosine hydroxylase (TH)-immunoreactive (ir) neurons in vitro. The experiments described here characterize the mesencephalic progenitor cells and their cytokine-induced conversion into dopamine (DA) neurons. For all experiments, we used bromodeoxyuridine (BrdU)-ir cultures of (E14.5) mesencephalic progenitor cells that had been expanded at least 21 days. We first demonstrated that IL-1 induced DA neuron conversion in mesencephalic progenitors, but not in striatal progenitors (P〈0.001). Thus, these cells should be classified as lineage-restricted progenitors, and not omnipotent stem cells. To further characterize cell populations in these cultures, we used monoclonal antibodies against Hu (an early marker for neurons), growth-associated protein (GAP)-43 (a marker for neuronal process extension), TH (a marker for DA neurons), and glial fibrillary acidic protein (GFAP, a marker for astrocytes). We assessed (E14.5) mesencephalic progenitor cell cultures (plated at 125,000 cells/cm2) incubated in the cytokine mixture (described above) or in complete media (CM, negative control). Following 7 days incubation, GFAP-positive cells formed a nearly confluent carpet in both types of cultures. However, numbers of Hu-ir and GAP-43-ir cells in the cytokine-incubated cultures far exceeded those in CM-incubated controls (P=0.0003, P=0.0001, respectively), while numbers of TH-ir cells were 58-fold greater in the cytokine-incubated cultures versus CM-incubated controls. The TH phenotype persisted for 7 days following withdrawal of the differentiation media. Numerous double-labeled cells that were BrdU-ir and also TH-ir, or Hu-ir and also TH-ir, were observed in the cytokine-incubated cultures. These data suggest that cytokines ”drive” the conversion of progenitor cells into DA neurons.
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  • 91
    ISSN: 1432-0878
    Keywords: Key words Subcommissural organ ; Isograft ; Xenograft ; Reissner’s fiber ; Cerebrospinal fluid ; Rat ; Bovine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The subcommissural organ (SCO) secretes glycoproteins into the cerebrospinal fluid (CSF) that aggregate and form Reissner’s fiber (RF). The factors involved in this aggregation are not known. One factor may be the hydrodynamics of the CSF when flowing through the aqueduct. This hypothesis was tested by isografting rat SCO and xenografting bovine SCO into the lateral ventricle of rats. Xenografts were either fresh bovine SCO or explants cultured for 30 days before transplantation. The grafts were investigated by electron microscopy and immunocytochemistry using antibodies against RF glycoproteins, serotonin and the glucose transporter I. Maximal time of transplantation was 43 days for isografts and 14 days for xenografts. The isografts were not reinnervated but were revascularized; they secreted into the ventricle RF glycoproteins that became progressively packed into pre-RF and RF structures identical to those formed by the SCO in situ. RF was confined to the host ventricle and at its distal end the constituent proteins disassembled. Xenografts were neither reinnervated nor revascularized and secreted into the host ventricle a material that never formed an RF. These findings indicate that the CSF factor responsible for the formation of RF is species specific, and that this process does not depend on the hydrodynamics of the CSF. The blood vessels revascularizing the isografted SCO acquired the characteristics of the vessels irrigating the SCO in situ, namely, a tight endothelium displaying glucose transporter I, and a perivascular space containing long-spacing collagen, thus indicating that basal release of glycoproteins may also occur in the grafted SCO.
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  • 92
    ISSN: 1432-0878
    Keywords: Key words Axonal transport ; Purkinje cell ; Organotypic culture ; Microinjection ; Antimitotic drugs ; Cytoskeleton ; Dendritic transport ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Axonal and dendritic transport in single Purkinje neurons of cerebellar slice cultures was quantified as single transport distances. Examination of the cells within a vital tissue was regarded as being an approach to the in situ condition. The Purkinje cells were organotypically integrated in the in vitro tissues and extended long axonal projections connecting synapses to the target neurons. The tracer horseradish peroxidase (HRP) was applied via microinjection to the somata of the Purkinje cells and the injected neurons were incubated thereafter for defined time-intervals. The tracer was transported anterogradely into the neuron processes. The measurements on both the axonal and the dendritic transport of microinjected HRP revealed continuous transportation with increasing times of postincubation. This transport was reduced by the use of microtubule-depolymerizing drugs. The axonal transport of the tracer was either retarded in colchicine-treated cells or continuously reduced for up to 50% in vinblastine-treated neurons. Thus, a correlation of axonal transport to the microtubules was demonstrated. The dendrites were filled with the tracer after 60 min of postincubation. Dendritic transport was reduced by the use of vinblastine, and not significantly by colchicine. The results strongly support the dependence of neuronal transport on microtubules as a component of the cytoskeleton.
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  • 93
    ISSN: 1432-0878
    Keywords: Key words Neurofilament ; Basket cell ; Pinceau ; Golgi apparatus ; Calcium binding protein ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract NCS-1 (neuronal calcium sensor) is a recently characterized member of a highly conserved neuron-specific family of calcium-binding proteins, which also includes frequenin and recoverin. The cellular and subcellular distributions of NCS-1 in the rat nervous system were investigated using light- and electron-microscopic immunohistochemistry. NCS-1 immunoreactivity was localized to neuronal cell bodies and axons throughout the brain and spinal cord but not to glial cells. The most intense labeling was observed in myelinated axons, the axonal ramifications of the basket cell in the cerebellar cortex, and large neurons in the brainstem and pons. These same structures were also characterized by heavy labeling for neurofilament protein, as determined by double-labeling experiments. Most axon terminals were unlabeled or only lightly labeled. The most remarkable subcellular staining occurred in the perikarya where intense labeling was associated with the membranes of the trans saccules of the Golgi apparatus. The widespread distribution of NCS-1 indicates that it may be active in a variety of calcium-dependent neuronal functions, whereas the specific subcellular localization to the Golgi apparatus and neurofilament-rich structures suggests a specialized role in calcium regulated protein trafficking and cytoskeletal interactions.
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  • 94
    ISSN: 1432-0878
    Keywords: Key words Glial cell line-derived neurotrophic factor ; GDNF ; Ret ; GDNFR-α ; Brain-derived neurotrophic factor ; BDNF ; NT-3 ; NT-4 ; trk receptors ; Thyroid tissue ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Levels of mRNA for neurotrophins (brain-derived neurotrophic factor, BDNF; neurotrophin 3, NT-3; neurotrophin 4, NT-4) and their receptors (trkA, trkB, trkC) and for glial cell line-derived neurotrophic factor (GDNF) and its receptors (ret, GDNFR-α) were measured in rat thyroid tissue by ribonuclease protection assays. In thyroid tissue the NT-3 mRNA level was threefold lower and the NT-4 mRNA level sixfold higher than those detected in adult rat hippocampus, while BDNF mRNA was undetectable. Very low levels of mRNA for truncated trkB and trkC receptors and no catalytic trkA, trkB or trkC were found. In conclusion NT-3 and NT-4, but not the corresponding functional receptors, are expressed in the thyroid tissue. Therefore, it is unlikely that these factors serve a direct local autocrine or paracrine function in thyroid cell types, and a target-derived mode of action on neurons innervating the thyroid tissue is suggested. An opposite result has been found for the neurotrophic factor GDNF: thyroid tissue showed a high level of transcripts for the GDNF receptor subunits (GDNFR-α and Ret), while GDNF mRNA was undetectable. The in situ hybridization analysis of GDNFR-α and ret mRNA revealed an interesting difference in the cell distribution of these transcripts: ret mRNA is selectively expressed in a subpopulation of cells scattered in the follicular epithelium and in the interfollicular spaces, while GDNFR-α expression is more homogeneous and widespread, including the more abundant cell type of the thyroid gland: the follicular cell. Double-labeling in situ hybridization/immunocytochemistry experiments, with a specific marker (calcitonin), showed that parafollicular cells express ret but not GDNFR-α. This differential distribution of the GDNF receptor components (GDNFR-α and ret) may reflect a peculiar biological role in intercellular communication in the thyroid gland.
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  • 95
    ISSN: 1432-0878
    Keywords: Key words Water channel protein ; Aquaporin ; AQP5 ; Rat ; Salivary glands ; Immunolocalization ; Secretory stimulation ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Aquaporin-5 (AQP5) is a water channel protein and is considered to play an important role in water movement across the plasma membrane. We raised anti-AQP5 antibody and examined the localization of AQP5 protein in rat salivary and lacrimal glands by immunofluorescence microscopy. AQP5 was found in secretory acinar cells of submandibular, parotid, and sublingual glands, where it was restricted to apical membranes including intercellular secretory canaliculi. In the submandibular gland, abundant AQP5 was also found additionally at the apical membrane of intercalated duct cells. Upon stimulation by isoproterenol, apical staining for AQP5 in parotid acinar cells tended to appear as clusters of dots. These results suggest that AQP5 is one of the candidate molecules responsible for the water movement in the salivary glands.
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  • 96
    ISSN: 1573-5125
    Keywords: irradiance ; nitrogen uptake ; phytoplankton ; Tagus estuary ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of light, temperature and ammonium on inorganic nitrogen uptake by phytoplankton was investigated from June 1994 through December 1995 at three sites in the Tagus estuary (Portugal), during high tide of neap tides. Ammonium concentrations higher than 10 μM reduced nitrate uptake down to 24% but never prevented it. Below this threshold concentration, nitrate uptake was neither inhibited nor changed. Uptake of both nitrate and ammonium as a function of light intensity exhibited a saturation response. Uptake reduction occurred in the near bottom phytoplankton populations, particularly for nitrate. The ammonium uptake system was less limited by light than the nitrate uptake system, indicating the importance of ammonium as a nitrogen source for the phytoplankton which is likely to experience high changes in light in the well-mixed water column of this estuarine environment. Ammonium uptake was exponentially related to temperature in the upper estuary whereas in the mid and lower estuary this relationship was linear. The effect of temperature on nitrate uptake was linear but far less marked than for ammonium uptake.
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  • 97
    ISSN: 1573-143X
    Keywords: alevin ; Atlantic salmon (Salmo salar) ; development ; egg ; temperature ; thermal tolerance ; yolk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three embryonic stages of Atlantic salmon (Salmo salar L.) were subjected to eight constant incubation temperatures (4, 7, 10, 12, 14, 16, 19 and 22 °C) exceeding the range usually experienced in natural conditions. A change in thermal tolerance during the embryonic and larval development was registered: pre-hatching stages showed an upper thermal limit at about 16 °C, while hatched larvae survived until 22 °C. Temperature significantly affects developmental rate, resulting in a faster development and, consequently, lower yolk weight percentage at higher temperatures. We found positive relationships between incubation temperature and body size (length and weight) in the less developed stages, in which some yolk remained, but size decreased at increasing temperatures when yolk was completely exhausted.
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  • 98
    ISSN: 1573-143X
    Keywords: cyanobacteria ; microalgae ; Spirulina ; Spirulina composition ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The influence of temperature on growth and biomass composition of two species of Spirulina, S. maxima and S. platensis used for food was studied. A 4L fermenter with temperature and agitation control was used to cultivate both species. Under continuous light, maximum cell production of 2.4 g l−1 was verified for both cultures studied at temperatures above 25 °C: S. maxima (30 °C and 35 °C) and S. platensis (25 °C and 30 °C). An accentuated lag phase was observed for all cultures at lower temperatures (15–20 °C), and a maximum biomass production of 1.5 g l−1 was achieved. It was also observed that an increase of temperature caused a marked decrease in protein content, while carbohydrate synthesis was stimulated. The concentration of γ-linolenic acid varied from 11–16% for S. maxima and from 12–14% for S. platensis, at the optimum growth temperatures. Greater culture volumes were also studied in order to compare the performance of glass and plastic containers. At optimum growth temperature, S. maxima produced the same cell growth and similar final biomass composition.
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  • 99
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    European journal of plant pathology 105 (1999), S. 509-512 
    ISSN: 1573-8469
    Keywords: tospovirus ; resistance ; Capsicum sp. ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Infection by two isolates of impatiens necrotic spot tospovirus (INSV) under temperature regimes of 25/18°C (day/night) or 33°C (continuous) was studied in Capsicum annuum (systemically susceptible to tomato spotted wilt tospovirus, TSWV), C. chinense PI 152225 and PI 159236 (reacting hypersensitively to TSWV) and Nicotiana benthamiana (systemically susceptible to both tospoviruses). At 25/18°C infection was systemic in all hosts tested. At 33°C infection in N. benthamiana was systemic whereas in C. annuum and C. chinense it was restricted to the inoculated leaves. The result differed from that reported for TSWV, where high temperature made plants more susceptible, or caused no difference. Exchanging temperature regimes 6 h to 4 days after inoculation did not affect the final results one month later, with plants being only locally infected at 33°C continuous regime, or systemically infected at 25/18°C alternate regime. The two INSV isolates were biologically and serologically stable for 5 passages in N. benthamiana held continuously at 33°C.
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  • 100
    ISSN: 1573-9104
    Keywords: Bioavailability ; Magnesium ; Hijiki ; Sodium alginate ; Rat ; Wakame
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The bioavailability of magnesium from Wakame and Hijiki, and the effects of alginic acid on absorption of dietary magnesium were examined in five groups of rats fed either control, Wakame, Hijiki, AW (containing the same amount of alginate as in the Wakame) and AH (containing the same amount of alginate as in the Hijiki) diets, and animals fed a low magnesium diet (LMg) (twentieth amount of magnesium in the original mineral mixtures as the control). Food intake and body weight gain were decreased by adding sodium alginate to the diets. A large amount of calcium accumulated only in the kidneys of the rats fed the LMg diet. Serum magnesium concentration decreased only in the LMg group. The magnesium content in the defatted left femurs did not differ between the control and Wakame fed animals and also among the animals eating Wakame, Hijiki and AW diets. The breaking force of the right femurs did not differ among all the groups except the LMg group. The ratio of apparent magnesium absorption (%) of the control, LMg, Wakame, Hijiki, AW and AH groups was 82.2, 72.7, 66.9, 50.8, 69.3 and 54.2 in the first experimental period, and was 75.3, 52.1, 57.7, 46.9, 62.6 and 60.5 in the second experimental period, respectively. It was clear that the bioavailability of magnesium in the Wakame fed rats was higher than in those eating the Hijiki. Large amounts of sodium alginate lowered magnesium absorption from the diet.
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