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  • 1
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    Abstracts (1977)
    Springer
    Details
    Publication Date: 1977-01-01
    Print ISSN: 0364-152X
    Electronic ISSN: 1432-1009
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering
    Published by Springer
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    PAPER CURRENT
  • 2
    Electronic Resource
    Electronic Resource
    Community interactions and zoogeography of the Indian Ocean Candaciidae (Copepoda: Calanoida) (1977)
    Springer
    Marine biology 43 (1977), S. 71-92 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Eighteen species of Candaciidae have been identified from collections made at 339 stations in the Indian Ocean. Most species are zonally distributed; however, on the eastern and western sides of the Indian Ocean, species ranges are extended north or south by boundary currents. Factor analysis was used to cluster phenotypically similar species based on 130 characters taken from the maxilla (a feeding appendage), the first swimming foot, and the fifth foot (a secondary sexual structure). Four morphological clusters were extracted. Clusterings based on separate factor analyses limited to characters from feeding or from sexually adapted appendages are in substantial agreement with the clusters based on composite morphology. Two geographically recurrent groups of species were also identified, one from equatorial waters, one from the central gyre. Each recurrent group is composed of species exceptionally different in body size and belonging to different morphological clusters. Niches of the species are compared using Hutchinson's multidimensional hypervolume as a model. An attempt is made to describe the niche of each species in terms of environmental variables measured at stations where the species was abundant. Environmental variables (dimensions) included in this study are space, time, temperature, food, oxygen and salinity. Mean niche adaptations of most of the species are separable from congeners along at least one niche dimension. It is proposed that community relationships among the Candaciidae developed to prevent both gamete loss and to avoid trophic competition. It is postulated that newly evolving species underwent contemporaneous displacement of both secondary sexual and trophic characters as a condition for sympatry, or diverged in their physiological adaptations to escape sympatric interference.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392573
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  • 3
    Electronic Resource
    Electronic Resource
    The effect of nitrogen deficiency on the growth and metabolism of Lemna minor L. (1977)
    Springer
    Planta 137 (1977), S. 259-264 
    Details
    ISSN: 1432-2048
    Keywords: Glycolysis ; Lemna ; Nitrogen deficiency ; Protein degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When Lemna is deprived of nitrogen, growth and respiration decrease and the pattern of 14CO2 release from [1-14C]glucose and [6-14C]glucose is consistent with a relatively strong inhibition of glycolysis. Protein degradation is enhanced but the concentration of free amino acid decreases. It is argued that the biological significance of the increased protein degradation does not lie in its contribution to respiration but as a mechanism to replace one set of enzymes adapted to a particular environmental condition (high nitrogen) with another set of enzymes adapted for low nitrogen in the environment. The change in enzyme pattern associated with the change from high to zero nitrogen in the growth medium has been examined for nine enzymes. The changes in activity observed are consistent with the observed apparent inhibition of glycolysis during nitrogen starvation, but do not explain the inhibition of the pentose phosphate pathway.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00388160
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  • 4
    Electronic Resource
    Electronic Resource
    Storing covariance with nonlinearly interacting neurons (1977)
    Springer
    Journal of mathematical biology 4 (1977), S. 303-321 
    Details
    ISSN: 1432-1416
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Summary A time-dependent, nonlinear model of neuronal interaction which was probabilistically analyzed in a previous article is shown here to be a natural generalization of the Hartline-Ratliff model of the Limulus retina. Although the primary physical variables in the model are the membrane potentials of neurons, the equations which govern the means and covariances of the membrane potentials are coupled through the average firing rates; as a consequence, the average firing rates control the selective storage and retrieval of covariance information. Motor learning in the cerebellar cortex is treated as a problem of covariance storage, and a prediction is made for the underlying synaptic plasticity: the change in synaptic strength between a parallel fiber and a Purkinje cell should be proportional to the covariance between discharges in the parallel fiber and the climbing fiber. Unlike previous proposals for synaptic plasticity, this prediction requires both facilitation and depression to occur (under different conditions) at the same synapse.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00275079
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of linkage and interaction in a comparison of theoretical populations derived by diploidized haploid and single seed descent methods (1977)
    Springer
    Theoretical and applied genetics 49 (1977), S. 111-115 
    Details
    ISSN: 1432-2242
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Comparisons were made between the genetic means and variances of a quantitative trait determined by 8 loci in simulated populations of lines derived by diploidizing haploids (DH) on the one hand and by single seed descent (SSD) on the other. In the absence of linkage no differences between the populations were observed, but when linkage was present, recombination was more frequent in the SSD populations as indicated by the relative differences in variance between these and the DH populations. In addition, differences in means between the populations derived by the two methods were observed when non-allelic interaction was present. The direction and magnitude of the differences in both means and variances depended upon the linkage phase, the recombination frequency and the presence or absence of interaction. The conclusion was drawn that the SSD method was to be preferred from theoretical considerations although in practice the choice of method will also depend upon practical and technical factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00281708
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of weathering and flue-curing on methomyl residues on tobacco (1977)
    Springer
    Archives of environmental contamination and toxicology 5 (1977), S. 199-206 
    Details
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract A replicated field experiment was conducted at two locations to determine the disappearance of methomyl from flue-cured tobacco. Immediately after application, methomyl residues were 88 and 113 ppm at Clayton and 44 and 105 ppm at Reidsville, respectively, for 0.56 and 1.12 kg/ha application rates. After 5 days these levels dropped to 0.7 and 2.8 ppm at Clayton and 1.4 and 4.1 ppm at Reidsville. At 9 days after application, 99% of the methomyl had disappeared at both locations. Losses of methomyl during flue-curing averaged 96% over locations, rates of application, and times of harvest, compared to an average loss of 98% due to weathering in the field for 5 days. The disappearance of methomyl during the curing process was approximately the same for both locations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02220903
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  • 7
    Electronic Resource
    Electronic Resource
    Lipid and protein histochemistry of enamel — Effects of fluoride (1977)
    Springer
    Calcified tissue international 24 (1977), S. 119-125 
    Details
    ISSN: 1432-0827
    Keywords: Protein ; Lipid ; Histochemistry ; Enamel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Staining reactions for a number of histochemical procedures for lipophilic staining and protein were studied in the enamel matrix along the length of rat incisors. Sudan Black gave a positive stain across the whole thickness of very early enamel (up to 30 μm) but this staining only continued as a narrow band close to the ameloblasts as the enamel matured. A variety of tests for protein produced almost identical staining patterns in enamel matrix up to 100 μm thick. Since the pattern of “lipid” staining persisted, after using a number of procedures which could normally be expected to remove lipid, it is suggested that Sudan Black positive staining may be due to lipophilic protein rather than lipid itself. Fluoride did not significantly alter the staining reactions for “lipid” and protein but did proceduce matrix which was much more effectively stained by cross-linking agents FFDNB and FF sulphene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02223305
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  • 8
    Electronic Resource
    Electronic Resource
    The absolute configuration of SU 23397: A novel neuroleptic agent (1977)
    Springer
    Cellular and molecular life sciences 33 (1977), S. 575-577 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The absolute configuration of a novel chiral neuroleptic agent SU 23397 (I) was determined by ORD comparison of (+)-5-methoxy dihydro coumarilic acid (VIII), a synthetic precursor of SU 23397 (I), with (+)-dihydro coumarilic acid, whose absolute configuration is known9. This assignment was confirmed by oxidative degradation of (+)-5-methoxy dihydro coumarilic acidVIII tod-(+)-malic acid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01946504
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  • 9
    Electronic Resource
    Electronic Resource
    Influence of fixation and buffer treatment on the release of enzymes from the plasma membrane (1977)
    Springer
    Histochemistry and cell biology 54 (1977), S. 57-66 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Pretreatment of frozen cryostat sections with formaldehyde or calcium ions inhibits diffusion of the plasma membrane enzymes 5′-nucleotidase, ATP-ase and alkaline phosphatase during incubation. 2. Treatment of fixed sections with different kinds of buffer at 37°C induces diffusion of enzyme activity from the plasma membrane to other sites of the section and into the incubation medium. This buffer influence depends on temperature: at 4°C only a slight diffusion occurs. Addition of phospholipase C, digitonin or taurocholate to the buffer opposes the buffer effect. 3. Pretreatment of frozen cryostat sections with a mixture of equal parts of chloroform and acetone gives a good fixation of the plasma membrane enzymes 5′-nucleotidase, ATP-ase, alkaline phosphatase and leucyl-β-naphthylamidase. During this treatment the different kinds of lipids present in the membrane are extracted equally. After this fixation buffer treatment does not cause a visible diffusion of enzyme activity in the section. Only a slight diffusion (1 till 7 percent) into the buffer solution takes place. 4. The mentioned treatments open up possibilities to get insight into the membrane anchorage of plasma membrane enzymes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00493329
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  • 10
    Electronic Resource
    Electronic Resource
    Application of enzymehistochemical methods to isolated subcellular fractions and to sucrose-ficoll density gradients (1977)
    Springer
    Histochemistry and cell biology 53 (1977), S. 165-181 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary To compare histochemical and biochemical determinations of enzyme activities, enzymehistochemical procedures are applied to sections of pellets of subcellular fractions. These investigations are of value to determine the subcellular localization of histochemically demonstrable enzyme activities and to test the homogeneity of an isolated fraction. In homogenating duckling liver a great part of the endothelial cells is not destructed and consequently is found in the nuclear fraction. Kupffer cell lysosomes land in the heavy mitochondrial fraction, whereas hepatocyte lysosomes are chiefly found in the light mitochondrial fraction. β-Glucuronidase activity shows a preferentially microsomal localization. Application of enzymehistochemical staining reactions to discontinuous gradients and comparison with biochemical data provides additional information about the validity of an enzymehistochemical reaction. In rat liver the tetrazolium reductases show a distinctly dual localization: activity in the mitochondrial band and in microsomal bands. As to their localization in different bands of the gradients non-specific esterases demonstrate a clear pH-dependency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00498491
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