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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 19 (1983), S. 214-218 
    ISSN: 1432-1432
    Keywords: Codon: anticodon adaptation ; Mutation ; Selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Synonymous codon usage frequencies, derived from cDNA clone sequences, were compared for several sets of vertebrate genes. Gene sets as diverse as those expressed in avian skeletal muscle and in mammalian liver showed similar patterns of synonymous codon usage. There were no significant differences suggesting tissue-specific co-adaptation of codon usage patterns and tRNA anticodon profiles. The results indicate a consensus codon usage pattern for vertebrate genes which is largely independent of taxonomic class, tissue of expression, and the cellular fate and rate of evolution of the encoded proteins. Certain elements of the consensus codon usage pattern indicate that it is the product of natural selection and not simply a mutational equilibrium among phenotypically equivalent synonyms.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0983
    Keywords: Thymidylate auxotrophy ; Mutation ; Recombination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A diploid yeast thymidylate auxotroph was grown under conditions of thymidylate stress ranging from depletion to excess levels of the nucleotide. High concentrations of thymidylate were mutagenic and recombinagenic whereas starvation for thymine nucleotides was recombinagenic and only slightly mutagenic. These results are discussed in relation to possible mutagenic and recombinagenic mechanisms of nucleotide pool imbalances.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 124 (1980), S. 143-148 
    ISSN: 1432-072X
    Keywords: Anacystis ; Blue-green algae ; Cyanobacteria ; Mutation ; Pigments ; Red light ; Synecaococcus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Under far-red (〉650 nm) illumination Anacystis nidulans grows poorly and develops a low chlorophyll content. During continued culture over many generations there are increases in growth rate and in the chlorophyll/phycocyanin ratio, usually occurring in concomitant and stepwise fashion. From such selection cultures six clones have been established which differ from the parent in pigment content and show improved growth rate in far-red light. From the evidence at hand the six clones are presumed to be spontaneous mutants selected under the photosynthetically restrictive condition of far-red illumination.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of mathematical biology 12 (1981), S. 355-362 
    ISSN: 1432-1416
    Keywords: Branching process ; Mutation ; Extinction ; Progeny size
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract A branching process method is employed to study the survival probability of a slightly advantageous mutant gene with a general distribution of progeny size in a large population. A counter-example to a classic proposition is given. A somewhat weaker result is proved.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of mathematical biology 13 (1981), S. 95-104 
    ISSN: 1432-1416
    Keywords: Stochastic migration ; Island model ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Recurrence relations are derived for stochastic migration in the island model with a finite number of subpopulations. Two models are considered, one involving a constant probability that each individual breeding in a given colony has migrated from another, the other assuming the exchange of fixed numbers of migrants between colonies each generation. The equilibrium solutions are expressed in terms of two measures of genetic differentiation among subpopulations, one similar to Nei's measure of genetic distance, and the other closely related to the coefficient of kinship. Both measures are shown to be necessary for a complete description of population structure. The predictions of the models of stochastic migration are compared with the corresponding classical model of deterministic migration.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 65 (1983), S. 41-46 
    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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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 65 (1983), S. 225-230 
    ISSN: 1432-2242
    Keywords: Tissue culture ; Mutation ; Sequential mutations ; Rice ; Oryza sativa L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Four mutations for early heading, albina, short culm and sterility were obtained in the progenies of twelve rice plants regenerated from a single callus of a rice seed. Studies on the segregation rates of these mutations revealed that for each mutation a single recessive gene was likely to be involved and that there was no linkage among the genes. The segregation pattern also showed that these mutations were induced in the following sequence: early heading, albina, and short culm and sterility during the stage of callus growth until the beginning of the regeneration of the rice plants.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-2242
    Keywords: Mutation ; Normalizing-selection ; Lethal-equivalence ; Genetic-load ; Neutral-theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Through a series of genetic load studies made on 1) samples of Drosophila willistoni from two sites in Mesitas, Colombia, it was found that the relative contributions to the total, subvital and lethal loads reflect lethal equivalences (B/A) ratios which support more the balancing theory of population structure than the neutralist theory. Moreover, measurements of population size have revealed the existance of very small demes in local populations. Under such conditions we have calculated extremely small lethal equivalence ratios in demes where probably a great deal of consanguinity takes place. We are aware that under these conditions B/A ratios cannot be very good monitors of random load measurements and, therefore, suggest a change in the mathematical formulation that take into consideration the existance of small populations. Furthermore, it appears plausible that the degree of penetrance in the heterozygous condition changes as the population structure changes. We speculate that natural populations may have unknown selective mechanisms capable of guiding unknown dominance modifiers according to the intensity of selection.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-2242
    Keywords: Interchange ; Chromosome polymorphism ; Mutation ; Selection ; Equilibrium ; Rye
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A persistent chromosomal polymorphism exists in a population of cultivated rye, Secale cereale (Candela et al. 1979). In order to ascertain the possible causes that maintain it, we have estimated the fitness values of structurally homozygous and heterozygous plants and the mutation rate of spontaneous interchange. The estimates of the selection coefficient against heterozygotes (s=0.15-0.40) and of the mutation rate u=6.12×10−2 support a mutation-selection equilibrium as a likely cause of the interchange chromosome polymorphism.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 67 (1984), S. 203-205 
    ISSN: 1432-2242
    Keywords: Ethyl methanesulphonate ; Mutation ; Myo-inositol ; Nicotiana tabacum, tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Tobacco seeds treated with ethyl methanesulphonate produces mutations as well as physiological growth debility. The addition of myo-inositol to seeds undergoing mutagenic treatment stimulated growth and increased survival of subsequent plants with negligible effect on the mutation frequency.
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