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  • 1
    ISSN: 1573-6822
    Keywords: DNA ; flow cytometry ; genotoxicology ; largemouth bass ; red blood cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Analysis of cellular DNA content by flow cytometry has been used to detect genetic changes associated with exposure to environmental contaminants. In lower vertebrates, nucleated red blood cells can be collected for analysis without harm to the animal. Because erythrocytes sampled from an individual should have identical amounts of DNA, the coefficient of variation (CV) around the G0/G1 peak should be small. Increases in CV can indicate genetic aberrations, but may also be caused by sample handling and preparation or problems with instrumentation. To increase confidence in associating increases in CV with external causes, artifactual changes in CV due to sample treatment and instrument parameters should be identified and minimized. We assessed the effects of various sampling and handling protocols on the CV of nucleated blood cells collected from largemouth bass (Micropterus salmoides). We also compared the distribution of cells among the G0/G1, S, and G2/M phases of the cell cycle to see whether these were affected by sampling or treatment protocols. Groups of 7 fish were bled on 7 consecutive days, and blood from each fish was analyzed by flow cytometry when freshly collected, and after freezing for 1 hour or 10 days. The same fish were bled again over a consecutive 7-day period, and the experiment was repeated. CV and cell cycle distribution were not affected by our freezing protocol. Repeat sampling from the same individual did not affect CV, but altered the distribution of cells in the cell cycle, suggesting increased hemopoiesis in response to blood sampling. Day-to-day variation in the CV occurred in both fresh and frozen samples, probably as the result of small variations in instrument adjustments. These results demonstrate the suitability of this freezing protocol for these blood samples, and illustrate the importance of assessing sources of variation when using flow cytometry to screen wild populations in genotoxicological studies.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-6857
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Evidence for multiple insemination in the mosquitofish, Gambusia affinis, was detected by statistical analysis of the enzyme phenotypes in mother-offspring combinations for three loci. The probability of nondetection of multiple insemination events for diallelic loci with two or more males mating with a female was presented. The frequency of multiple insemination for G. affinis is at least 56% but is probably nearer to 100%. The high incidence of multiple insemination together with sperm storage and delayed fertilization could have important effects on allele frequencies through time and space. These effects are due to the increase in effective population size and overlap among generations.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Human evolution 5 (1990), S. 283-291 
    ISSN: 1824-310X
    Keywords: Inbreeding ; primates ; genetic variation ; lethal equivalents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The two subspecies of ruffed lemurs (Vareica variegata variegata andVarecia variegata rubra) have been maintained in captivity since 1959 and all institutions which hold ruffed lemurs have contributed data to theVarecia International Studbook. Studbook data were used to analyze inbreeding effects on survival in both subspecies ofVarecia. Several variables, including offspring's inbreeding coefficient, litter size, mother's inbreeding coefficient, and mother's age, were examined for significant associations with percent survivorship per litter. Percent survivorship per litter was negatively correlated to the offspring inbreeding coefficient in the black and white ruffed lemurs (p〈0.001) but no significant association was found for red ruffed lemurs. Although emphasis has been put towards the status of the red ruffed lemurs due to the small founder size, the black and white ruffed lemurs should also be managed with care due to the lower tolerance to inbreeding in captivity.
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  • 4
    ISSN: 1573-6857
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A chromosomal centric fusion polymorphism in populations of the plains pocket gopher, Geomys bursarius, was studied to determine the relative fitness associated with the karyotypic phenotypes. There was a greater number of heterozygous individuals than expected χ1 2=8.58, P=0.001. Calculations indicate that the viabilities of the two chromosomal homozygotes were only 35 and 76 percent or that of the heterozygote. Differences in fitness values for the chromosomal morphs for Geomys strongly emphasize the possible adaptive nature of the karyotype and provides a primary mechanism for chromosomal evolution, even in species composed of demes of relatively large size. This is the first case of positive chromosomal heterosis in vertebrates. The plains pocket gopher can now be added to the few empirically documented samples of balanced polymorphism.
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  • 5
    ISSN: 1573-6857
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Protein variation in 182 Sylvilagus floridanus from 19 playa basins in Castro Co., Texas was examined using starch-gel electrophoresis. Heterozygote deficiencies were noted for all populations. This heterozygote deficiency may be due to differential selection against heterozygous individuals over the winter months. Results of F-statistics indicated a significant degree of population differentiation at six loci. Nei's genetic distance between populations ranged from 0.20 to 0.388 and a significant association between genetic distance and linear geographic distance among playas was found. These results suggest that genetic exchange and long-distance dispersal may be hindered by expanses of unsuitable habitat.
    Type of Medium: Electronic Resource
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  • 6
    Publication Date: 1994-06-01
    Print ISSN: 0742-2091
    Electronic ISSN: 1573-6822
    Topics: Biology , Medicine
    Published by Springer
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