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  • 1980-1984  (1,051)
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  • 1
    ISSN: 1432-2242
    Keywords: Genetic control ; Aneuploidy ; Y chromosome ; Sexing systems ; Lucilia cuprina
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Viable and fertile Y-linked duplications have been recovered in Lucilia cuprina for autosomal segments ranging in size from 2–12% of the autosomal polytene chromosome complement. No viable deficiency in this size range was recovered. Survival to adulthood of the duplications decreased with increasing duplication size. Genetic background also influenced recovery of some duplications. Recovery of duplications from fertile duplication-male parents was frequently much higher than from translocation-male parents, possibly due to low adjacent-1 segregation in some translocations or to meiotic-drive-type events. Chromosome 4R may contain a triplo-lethal locus. The use of sex-linked duplications in female-killing systems for genetic control programs may have considerable advantages over reciprocal sex-linked translocations, both in terms of fertility and strain stability.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2242
    Keywords: Diallel cross ; Maternal effects ; Heterosis ; Mice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A genetic framework was developed for the interpretation of statistical parameters estimated from a diallel experiment among a fixed set of lines. These included average direct genetic, average maternal genetic, general combining ability, reciprocal, and line and specific direct and maternal heterotic effects. The genetic model is based on direct and maternal additive and dominance genetic effects as would be expected in animal species. The model assumes that dominance is the underlying basis of heterosis. As an example, litter size at birth was analyzed from a 5 × 5 diallel cross with mice.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2242
    Keywords: Tissue culture ; Seed development ; Starch synthesis ; Starch mutants ; Zea mays L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Kernels of wild type maize (Zea mays L.) and the mutants shrunken-1 and shrunken-2 developed as much as in vivo when excised at five days post-pollination and grown in culture using existing methods. Mature kernels from culture exhibited their expected phenotypes. Starch, sugar and enzyme levels of kernels grown in culture were similar to those known to occur in kernels of the same genotypes grown in vivo. Differences in percentage germination of kernels grown in vitro were similar to those of kernels grown in vivo.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2242
    Keywords: C-banding ; Improved technique ; Diploid Aegilops ; Genome symbols ; Heterochromatin repatterning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Based on an improved C-banding technique, the C-banding patterns of all 11 diploid Aegilops species were described and compared. All diploid species exhibit characteristically different patterns which enable the chromosomes of any complement to be identified individually. These patterns confirm existing genome symbols and provide further evidence for the suggested changes in genome symbols of Ae. umbellulata and Ae. sharonensis, U and Ssh respectively. Furthermore, Ae. uniaristata should be given a separate symbol, probably N. Aegilops speltoides and Ae. sharonensis could be possible donors to the B genome of wheat. Interspecific divergence in these diploid species has been accompanied by either amplification or deletion as well as massive repatterning of heterochromatin from the centromere to the telomere.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Wheat ; Protein ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Poor adaptability or functional quality of much germplasm used for breeding high-protein hard red winter wheats prompted mutagenesis as an alternative means of increasing grain protein content. Four hard red winter wheat genotypes — KS644 (‘Triumph// Concho/Triumph’), ‘Kaw’, ‘Parker’, and ‘Shawnee’ — were treated with 0.40 M ethyl methanesulfonate (EMS). Advanced lines (M8-M10) were selected that had a 3-year mean grain protein advantage of 0.7% to 2.0% over controls. Increased grain protein content was generally associated with decreased grain yield and kernel weight, but some high-protein mutant lines had yields or kernel weights similar to those of original genotypes. Changes in height and lodging induced by EMS were generally favorable, most mutants being shorter and lodging less than controls, but blooming date was generally delayed, a deleterious change. One line also changed from resistant to segregating for wheat soil-borne mosaic virus. Mutant lines might be utilized in cross-breeding programs, particularly if negative pleiotropic effects and linkages are absent.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-2242
    Keywords: Linkage disequilibrium ; Selection ; Genetic variance ; Quantitative traits ; Epistasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Selection for a character controlled by additive genes induces linkage disequilibrium which reduces the additive genetic variance usable for further selective gains. Additive x additive epistasis contributes to selection response through development of linkage disequilibrium between interacting loci. To investigate the relative importance of the two effects of linkage disequilibrium, formulae are presented and results are reported of simulations using models involving additive, additive x additive and dominance components. The results suggest that so long as epistatic effects are not large relative to additive effects, and the proportion of pairs of loci which show epistasis is not very high, the predominant effect of linkage disequilibrium will be to reduce the rate of selection response.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 65 (1983), S. 218-218 
    ISSN: 1432-2242
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-2242
    Keywords: Reciprocal translocation ; Autotetraploid ; Chromosome pairing ; Simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Reciprocal translocations in autotetraploids create extremely complex cytological and genetic situations. Along with three types of heterozygotes with one, two or three pairs of translocated chromosomes, a large array of aneuploid and unbalanced genotypes can be expected in the F2 and advanced generations. These types arise from gametes formed by adjacent and anomalous disjunctions of multivalents and by numerical non-disjunction of non-cooriented multivalents. To determine the expected patterns of meiotic chromosome pairing configurations in all of these genotypes without the use of a computer program that constructs all possible pairing configurations, and recognizes and sums both the individual meiotic figures (univalents, rod and ring bivalents etc.) and combinations of meiotic figures, would be a very difficult task. The program has been used to construct all the possible meiotic configurations for a large array of normal and translocated genotypes with five, six, seven, eight, nine or ten chromosomes. Several inferences about the behavior of translocated chromosomes in autotetraploid populations have been drawn.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 65 (1983), S. 72-72 
    ISSN: 1432-2242
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-2242
    Keywords: Heritability ; Family size ; Genetic relationship ; Analysis of variance ; Sheep
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Heritability estimated from sire family variance components, ignoring dams, pools conventional paternal and maternal half sib estimates, in a way which is biased upward, and sub-optimal for minimizing the sampling variance. Standard error of a sire family estimate will be smaller than that of the equivalent paternal half sib estimate, but not as small as that of an estimate obtained by optimal pooling of paternal and maternal half sib estimates. If only additive genetic variance components are significant, the bias may be removed by use of a computed average genetic relationship for sire families, in place of a nominal R = 0.25. Average genetic relationship may be computed from mean and variance of dam family size within sire families. If dominance, epistatic, or maternal components are significant, this simple correction is not appropriate. In situations likely to be encountered in large domestic species such as sheep and cattle (dam family size small and uniform) bias will be negligible. The method could be useful where cost of dam identification is a limiting factor.
    Type of Medium: Electronic Resource
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