Estimation of the number of sex alleles and queen matings from diploid male frequencies in a population of Apis mellifera. The distribution of diploid males in a population of Apis mellifera was obtained by direct examination of the sexual phenotypes of the larvae. Using these data, estimates are derived for the number of sex alleles and the number or matings undergone by the queen. The number of sex alleles is estimated to be 18.9. The estimate is larger than previous ones, which have ranged between 10 and 12. However, the increase in the number of sex alleles can be explained by the large effective population number for our data. The best estimator of the number of matings by a queen is a maximum likelihood type that assumes a prior distribution on the number of matings. For the data presented here, this estimate is 17.3. This estimate is compared to others in the literature obtained by different approaches.


The evolution of epistasis and the advantage of recombination in populations of bacteriophage T4. Experiments reported here test two hypotheses about the evolution of recombination: first, the Fisher-Muller concept that sexual organisms respond to selection more rapidly than do asexual ones, and second, that epistasis is more likely to evolve in the absence of recombination. Populations of bacterio-phage T4 were selected by the drug proflavine in discrete generations and the change in mean population fitness was monitored. Three separate selection series yielded results supporting the Fisher-Muller hypothesis. The amount of epistasis evolved was measured by partitioning the T4 map into regions and comparing the sum of the proflavine resistances of each region with the resistance of the whole. Significantly more interactions were found in phage isolated from the populations with lower total recombination than in those from populations with higher recombination. The degree to which these experiments fit preconceived notions about natural selection suggests that microorganisms may be advantageously used in other population genetics experiments.


Phylogenies constrained by the crossover process as illustrated by human hemoglobins and a thirteen-cycle, eleven-amino-acid repeat in human apolipoprotein A-I. Examination of human apolipoprotein A-I revealed a segment of eleven amino acids that repeated itself 13 times in succession without any additional intervening amino acids between the beginning of the repeats (amino acid 93) and their end at the carboxyl terminus of the sequence. The segments are not identical, but the pattern of their physical and chemical properties is highly conserved. The pattern is shown to be suitable to the formation of alpha helices with an amphipathic character consistent with the formation of a micellar structure, a process entirely appropriate to the protein's known function in the blood stream as a lipid carrier. The simplest hypothesis to account for repeated segments is a series of unequal crossovers. But such a series implies that some segments are more closely related to each other than they are to others, that is, they have a "phylogenetic" relationship. It is shown that only a small fraction of all possible phylogenies are consistent with a set of segments arising by simple unequal crossing over. Nevertheless, it is shown that the apolipoprotein A-I segments are readily interpretable as the result of simple unequal crossing over. Moreover, the crossover constraint applies with as much force to segments larger than a gene as to segments within a gene, and this is shown to require that the human gamma (Gly) hemoglobin gene lie to the left, rather than to the right, of the other non-alpha human hemoglobin genes, a conclusion for which there is no direct genetic evidence currently available.


Three linked enzyme loci in fishes: implications in the evolution of vertebrate chromosomes. A three-point linkage group comprised of loci coding for adenosine deaminase (ADA), glucose-6-phosphate dehydrogenase (G6PDH), and 6-phospho-gluconate dehydrogenase (6PGD) is described in fish of the genus Xiphophorus (Poeciliidae). The alleles at loci in this group were shown to assort independently from the alleles at three other loci--isocitrate dehydrogenase 1 and 2, and glyceraldehyde-3-phosphate dehydrogenase 1. Alleles at the latter three loci also assort independently from each other. Data were obtained by observing the segregation of electrophoretically variant alleles in reciprocal backcross hybrids derived from crosses between either X. helleri guentheri or X. h. strigatus and X. maculatus. The linkage component of chi2 was significant (less than 0.01) in all crosses, indicating that the linkage group is conserved in all populations of both species of Xiphophorus examined. While data from X. h. guentheri backcrosses indicate the linkage relationship ADA--6%--G6PDH--24%--6PGD, and ADA--29%--6PGD (30% when corrected for double crossovers), data from backcrosses involving strigatus, while supporting the same gene order, yielded significantly different recombination frequencies. The likelihood of the difference being due to an inversion could not be separated from the possibility of a sex effect on recombination in the present data. The linkage of 6PGD and G6PDH has been shown to exist in species of at least three classes of vertebrates, indicating the possibility of evolutionary conservation of this linkage.


The detection of sympatric sibling species using genetic correlation analysis. I. Two loci, two gamodemes. Four models are presented describing zygotic frequencies at two loci for one or two sympatric but genetically differentiated populations of "gamodemes." Linkage disequilibrium within gamodemes is allowed in two of the models. Maximum likelihood criteria are used to fit the models to the observed numbers of zygotes in a sample. A fitting-testing sequence for choosing a best model is described and the power of the test is analyzed. The statistical characteristics of the genetic parameter estimates were examined by simulation studies. In general, estimates were reliable when allele frequency differences between gamodemes were greater than 0.30 at both loci. This method may be used to study the population structure of samples with fewer heterozygotes than expected for Hardy-Weinberg populations, including the detection and genetic description of sibling species having overlapping ranges.--An example is given for Drosophila longicornis and D. propachuca, two sibling species within the mulleri complex of the repleta group which have been studied in detail using more conventional techniques. The reanalysis using the approach derived in this paper confirmed the reproductive isolation of these two species, and hinted at the possibility of further subdivision within D. propachuca.


A model of functional epistasis and linkage disequilibrium in populations with overlapping generations. A model of functional epistasis is proposed in which it is assumed that coupling and repulsion genotypes differ in metabolic efficiency and thus in development time and net fecundity. The implications of this model are investigated for iteroparous populations with fluctuating rates of increase. It is found that the fluctuations in rate of increase can lead to large fluctuations in gamete frequency and D, the coefficient of linkage disequilibrium, but that D will almost always have a value of zero at some point during the populations' demographic cycle. Some of the model populations would be expected to be in a state of linkage disequilibrium only fleetingly: others would exhibit D-cycles interpretable as random fluctuation. Implications of the model for interpretations of existing data on linkage disequilibrium among enzyme loci in Drosophila are discussed.


Mutation-selection balance with stochastic selection. Diffusion theory has been used to analyze a model of mutation-selection balance in which the selection process is assumed to be stochastic in time. The limiting outcome of the mutation-stochastic selection process is determined qualitatively by the geometric mean fitnesses of the genotypes, and the conditions for fixation or polymorphism are similar to those that determine the outcome of the mutation-selection process when selection is constant. However, in the case of a completely recessive allele, detailed numerical study of the polymorphism associated with stochastic selection has shown that the average allele frequency maintained is greater than the equilibrium frequency expected when selection is constant, even when the geometric mean fitness of the recessive homozygotes is identical in the stochastic and deterministic models. Thus, allele frequencies in natural populations that are too high to be plausibly explained by a balance between mutation and constant selection can be accounted for if selection is stochastic.


Identity coefficients in finite populations. I. Evolution of identity coefficients in a random mating diploid dioecious population. Properties of identity relation between genes are discussed, and a derivation of recurrent equations of identity coefficients in a random mating, diploid dioecious population is presented. Computations are run by repeated matrix multiplication. Results show that for effective population size (Ne) larger than 16 and no mutation, a given identity coefficient at any time t can be expressed approximately as a function of (1--f), (1--f)3 and (1--f)6, where f is the mean inbreeding coefficient at time t. Tables are presented, for small Ne values and extreme sex ratios, showing the pattern of change in the identity coefficients over time. The pattern of evolution of identity coefficients is also presented and discussed with respect to Neu, where u is the mutation rate. Applications of these results to the evolution of genetic variability within and between inbred lines are discussed.


[Cytogenetic activity of the pesticides phthalophos, chlorophos and gardona in a culture of human lymphocytes]. The cytogenetic action of three phosphoorganic pesticides, imidan, dipterex and gardona, in cultured human lymphocytes is studied. It is found that all the sunstances induce the signficant increase in the frequency of metaphases with chromosomes aberrations as compared with the control level. Maximal effects in vitro qere 6,0; 4,8 and 4,0% of aberrant cells for imidan, dipterex and gardona respectively. All investigated substances had a weak mutagenic activity in human lymphocyte culture.


[Inheritability of blood metabolite concentrations in cattle at different age periods and seasons of the year]. Coefficients of heritability of lipid, carbohydrate and protein-nitrous blood metabolites were studied through comparison of mothers and their daughters at different age periods (6, 9, 12, 15, 18 months and the 1st lactation) and seasons. The highest and most statistically significant are heritability coefficients of triglycerides, phospholipids, cholesterin, total lipids; coefficients of acetic acid, 3-hydroxybutyric acid, acetone and acetylacetic acid and blood glucose are lower. The highest coefficients of heritability among protein-nitrous metabolites are those of globulins; coefficients of albumins, total protein, blood amino nitrogen are lower. Heritability coefficients of blood metabolites, except albumins, globulins and glucose are stable enough at different age periods. No pronounced season differences are observed. The presence of high and statistically significant heritability coefficients of a number of blood metabolites, their age and season stability indicate the possibility of using these metabolites as additional tests in selection of dairy cattle.


[Further genetic analysis of mink serum Lpm-allotypes]. The results obtained by testing 3127 mink sera as well as the analysis of families completely confirmed that the Lpm allotype system of very high density proteins is under genetic control, as postulated earlier. The polymorphism of the first five allotypes is due to the genetic units Lpm1, Lpm4, Lpm1,2, Lpm3,4 and Lpm2,4,5, which behave as Mendelian alleles. The data obtained suggest the existence of an additional gene, LpmX, which, in the homozygous state, determines a very rare phenotype, negative for the first five markers.


[Isolation and preliminary characteristics of the extrachromosomal elements of Bacillus thuringiensis DNA]. Centrifugation of Bacillus thuringiensis 351 DNA in CsCl-ethidium bromide density gradient has revealed, besides the main band of chromosomal DNA (p = 1.56 g/cm2), some additional bands with higher density, which usually correspond cicle superhelix DNAs, are revealed. 6 discrete bands are observed under electrophoresis of total fraction of minor DNA bands, which suggests, that the preparation contains cicle DNAs of different size. The treatment with DNAse results in the appearance of 3 bands corresponding to opened cicle DNA forms, their molecular weight being 12-10(6)--4-10(6) daltons. Cicle super-helix and opened cicle DNA forms are found in minor fraction by means of electrone microscopy. Statistical analysis has revealed the presence of at least three types of cicle molecules of different size. The variant 351-10, free of extrachromosomal elements, is isolated after ethidium bromide treatment at high temperature. Possible mechanisms of cicle DNAs formation are discussed. Biological function of DNA extrachromosomes fragments in Bacillus thuringiensis is still obscure.


[Recombination in amber mutants of bacteriophage T4B. III. Influence of X-mutation on intragenic recombination in T4 phages]. Study was made of the influence of X-mutation on interallelic and intergenic recombination at the region of genes 34-38 of phage T4B. In the case of intergenic crosses in all studied recombinations of genes mutation X caused a 2-fold decrease in recombination frequency. X-mutation showed the same effect on integenic recombination in genes 36 and 38. In the case of crossing flank markers of gene 35 the frequency of recombination decreased 3.5-fold, that of gene 34--6 fold. Crosses of double am-X mutants mapped at different sites of gene 34 allowed to detect the gradient of the effect X-mutation on recombination in gene 34 in the direction from gene 33 to gene 35. The data obtained indicate a local anomaly of DNA structure of the region of genes 34 and 35 and allowed to draw a conclusion that the degree of suppressing recombination process under the influence of X-mutation depends nor on the original recombination frequency between markers to be crossed, that is on the internal structure of the given region of the genome of bacteriophage T4. Possible reasons for specific effect of X-mutations on the recombination in genes 34 and 35 of phage T4B are discussed.