Heterochromatin of the Y-chromosome and variability of human morphophysiological traits

80 morpho-physiological traits were studied in a group of 55 men with morphologically identical subtotal deletion of Y chromosome heterochromatin and in a control group of 55 men with normal Y chromosome. No significant differences in mean values of most traits were found between these groups, except for some haematological parameters. With the help of the pattern recognition algorithm, 20 features were extracted which classify the two groups of individuals compared, the recognition error being 4.6%. Electrocardiographic parameters (25% of total traits), some haematological, anthropometric traits and age were included into the pattern recognition system. The results of the study suggest the existence of some modification influence of Y chromosome heterochromatin on the structure of phenotypic relationships between morpho-physiological traits in human ontogenesis.     

Population genetic study of differential fertility in man (illustrated by habitual abortion). V. Distribution of individual heterozygosity and parameters of genotypic variability for a set of immunological genetic markers

Distribution of individual heterozygosity (the number of heterozygous loci per individual), frequencies of genotypes formed by paired combinations of 5 loci and values of linkage disequilibrium between 6 blood group loci were studied both in a group of couples and single women with recurrent abortions in anamnesis, and in a group of couples and single women with normal fertility. Statistically significant deficit of highly heterozygous individuals was found in the experimental group. Marked increase of genetical variability was shown for the women with repeated abortions, as a consequence of elevation of rare genotypic paired combination frequency. Therefore, differential fertility as a component of stabilizing selection alters the distribution of complex genotypes in human populations. Differences in values of linkage disequilibrium between women with repeated abortions and those of normal fertility were not found.     

The joint variability of the growth-weight characteristics and biochemical gene markers in newborn infants

A relationship between heterozygosity of 6 biochemical loci and variability of 4 anthropometric traits at birth has been studied in 304 boys and girls from Moscow population. All 4 traits in boys are positively correlated with the number of loci for which they are heterozygous. The values of all the traits in girls are highest in homozygous individuals. In order to reduce the number of variables the principal component analysis is applied. Boys and girls with average level of heterozygosity turned out to be closest to the corresponding population averages of morphological traits. The results are discussed in terms of 3 models: Lerner's concept of genetical homeostasis, additive and overdominance polygenic models. It is concluded that an average level of heterozygosity is optimal for a population.     

The ABO blood group system as genetic markers of quantitative traits in man

A model of correlative variability of AB0 blood groups and a quantitative trait (mad-model) was analysed. Statistics for evaluation of additive and non-additive effects of alleles IA, IB and i on quantitative trait were developed. Restrictions of the model application are discussed. The obtained results may be used in genetic epidemiology for study of sensitivity or resistance to different diseases.     

The gene pool of Belgorod oblast population: the distribution of immunological and biochemical gene markers

The frequencies of 33 alleles of 12 loci of immunological and biochemical gene markers (ABO, RH, HP, GC, TF, PI, C'3, ACP1, GLO1, PGM1, ESD, and 6-PGD) have been estimated in the indigenous Russian and Ukrainian populations of Belgorod oblast. Differences of the Belgorod population from other populations of Russia with respect to the genetic structure have been determined. It has been found that the frequency distributions of all alleles studied in the Belgorod population are similar to those typical of the genetic structure of Caucasoid populations.     

The gene pool of Belgorod oblast population: The distribution of immunological and biochemical gene markers

The frequencies of 33 alleles of 12 loci of immunological and biochemical gene markers (AB0, RH, HP, GC, TF, PI, C′3, ACP1, GLO1, PGM1, ESD, and 6-PGD) have been estimated in the indigenous Russian and Ukrainian populations of Belgorod oblast. Differences of the Belgorod population from other populations of Russia with respect to the genetic structure have been determined. It has been found that the frequency distributions of all alleles studied in the Belgorod population are similar to those typical of the genetic structure of Caucasoid populations.     

Polymorphism of immunological and biochemical marker genes in rural populations of the Tuva Republic

This article continues the series of publications on the population genetic structure of the Tuva Republic. The polymorphism of immunological (ABO, MN, and the Dd locus of Rhesus) and biochemical (TF, GC, HP, PGD, PGM1, ACP1, and ESD) marker systems was studied in three rural populations of the Tuva Republic: the Shinaanskii, Todzhinskii, and Bai-Taiginskii populations (the Kungurtug, Toora-Khem, and Teeli villages, respectively). Genetic subdivision of the populations and genetic distances between the Tuvinian populations and the populations of neighboring regions were estimated. Tuvinians were demonstrated to be genetically heterogeneous. Data on their population-genetic structure with respect to several classical marker systems agree with the results obtained for quasigenetic (family names) and molecular (mtDNA) markers. Prolonged isolation of individual populations in the republic promoted formation of specific patterns of gene frequencies in some of them. These patterns account for differences between Tuvinians and other populations belonging to the Altaic language family. Tuvinians in general are genetically closer to Mongolian populations inhabiting the regions bordering the Tuva Republic than to southern Altaians.     

Allelic diversity for neutral markers retains a higher adaptive potential for quantitative traits than expected heterozygosity

The adaptive potential of a population depends on the amount of additive genetic variance for quantitative traits of evolutionary importance. This variance is a direct function of the expected frequency of heterozygotes for the loci which affect the trait (QTL). It has been argued, but not demonstrated experimentally, that long‐term response to selection is more dependent on QTL allelic diversity than on QTL heterozygosity. Conservation programmes, aimed at preserving this variation, usually rely on neutral markers rather than on quantitative traits for making decisions on management. Here, we address, both through simulation analyses and experimental studies with Drosophila melanogaster, the question of whether allelic diversity for neutral markers is a better indicator of a high adaptive potential than expected heterozygosity. In both experimental and simulation studies, we established synthetic populations for which either heterozygosity or allelic diversity was maximized using information from QTL (simulations) or unlinked neutral markers (simulations and experiment). The synthetic populations were selected for the quantitative trait to evaluate the evolutionary potential provided by the two optimization methods. Our results show that maximizing the number of alleles of a low number of markers implies higher responses to selection than maximizing their heterozygosity.     

Genetic variability and association of ISSR markers with some biochemical traits in mulberry (Morus spp.) genetic resources available in India

Utilizing intersimple sequence repeat (ISSR) markers, 18 mulberry (Morus spp.) germplasm collections were studied for genetic variability, phylogenetic relationship, and association with protein and sugar content. The genetic polymorphism exhibited by ISSR primers was 100%, and the genetic diversity recorded among the mulberry accessions had an average of 0.263 ± 0.094. Dendrogram (unweighted pair group method analysis) clustered the mulberry accessions into two major groups, one comprised the accessions collected from north or northeast regions of India, and the other comprised three subclusters and one isolate, i.e., Assamjati, a collection from Assam. Another subcluster contained accessions collected from Kerala, which belong to Morus indica. These accessions of M. indica from Kerala were found to be genetically diverse from north and northeast India. Multidimensional scaling of the ISSR data clearly separated the mulberry accessions according to their genetic diversity and protein content. Mulberry accessions were arbitrarily grouped into three classes viz. very low, moderate, and high in terms of protein and sugar content using standard statistical programs. Stepwise multiple regression analysis identified four ISSR markers (835_1,600, 835_5,600, 822_2,500, and 807_2,500) associated with protein content with highly positive correlation (p < 0.001) with linear curves with high F values (18.055 to 48.674; p < 0.001). In case of sugar content, four ISSR markers viz. 812₉₀₀, 817_1,500, 826_1,500, and 810_8,000 showed negative correlation. Hence, DNA markers for proteins seem promising and may be used in marker-assisted breeding program.     

The relation between the variability of polygenic morphological and monogenic biochemical traits as exemplified by Karakul sheep

A quantitative method for investigation of relationship between polygenic and monogenic traits has been proposed. It is based on examination of relationship between frequencies of distribution classes of an adaptive quantitative trait and frequencies of certain genetic character in the same classes. The method permits to locate a gene marker within a space of quantitative trait values. Using adaptively significant morpho-anatomic traits, it is possible to estimate indirectly adaptive values of gene markers under consideration, since, in accordance with the concept of adaptive norm, "average" phenotypes have maximal fitness, whereas deviative phenotypes transgress the bounds of the optimum. As a genetical character, genotype of certain biochemical locus, individual heterozygosity range or interlocus combinations of alleles could be used. The method has been applied to newborn Astrakhan lambs. Principal component analysis has been used to obtain complex characterization for six constitutional characters. Some regularities in location of homo- and heterozygous genotypes of the transferrin locus within a space of morphological characters' values have been revealed.     

Variance in quantitative traits due to linked dominant genes and variance in heterozygosity in small populations

The influence of small population size (N) on the genetic variance within and between randomly bred unselected lines, with selfing permitted, is investigated for a model of a quantitative trait determined by linked genes that show dominance within loci but are additive over loci. Formulae for within-line variance include terms in linkage disequilibrum, which occurs by chance in the lines and these are evaluated in terms of N, map length and gene number.—The expected variance within lines is increased by this disequilibrium, quite substantially if there are many loci, with most of the increase being between or within full-sib families and almost no change expected between half-sib families or in the covariance of offspring and parent. If all loci are unlinked, there is no increase in variance within full-sib families. The variance between lines is little affected by disequilibrum generated by chance.—Expressions for the variance between individuals in heterozygosity over the whole genome are special cases of those for the variance due to linked dominated genes, and formulae are given and evaluated. The coefficient of variation of heterozygosity is at least (see PDF) and can be much higher for species with few chromosomes.     

Physiological and biochemical traits involved in the genotypic variability to salt tolerance of Tunisian Cakile maritima

Cakile maritima (family: Brassicaceae) was collected from three provenances belonging to different bioclimatic stages (humid, semi arid and arid) in Tunisia to study their eco‐physiological and biochemical responses to salinity. Seedlings were cultivated on inert sand for 20 days under NaCl treatments (0, 100, 200, 400 mm NaCl). Plant response to salinity was provenance‐ and salt‐dependent. At 100 mm NaCl, growth parameters (leaf biomass, area, number per plant and relative growth rate) were improved in plants from Jerba (originating from arid bioclimatic stage) compared with the control, while growth was reduced in those from Tabarka (from humid area). High salt levels (400 mm NaCl) decreased the plant growth in the three provenances, but plants in Tabarka were the most salt sensitive. The relative salt tolerance of plants from Jerba and Bekalta provenances was associated with low levels of malondialdehyde as well as of electrolyte leakage and endoproteolytic activity. Salt reduced leaf hydration, the decrease in water content being dose‐dependent and more pronounced in Tabarka. Increase in salinity led to significant increase in leaf succulence and decrease in leaf water potential, especially in Jerba plants. The plants from the latter displayed the highest leaf levels of Na⁺ and Cl^?, proline, soluble carbohydrates, soluble proteins, and polyphenols. Overall, the higher salt tolerance of plants from Jerba provenance, and to a lower extent of those from Bekalta, may be partly related to their better capacity for osmotic adjustment and to limit oxidative damage when salt‐challenged.     

Genetics of Caucasian population: distribution of various immunological and biochemical markers in western Georgia

The distribution of genetic markers of blood groups (ABO, Rhesus, MNSs, P, Duffy, Kell-Cellano), plasma proteins (Hp, Gc, Tf, C'3) and red-cell enzymes (AcP, EstD, GLO-1), and also ABH secretion among 10 populations of Western Georgia has been studied. The common characteristic of distribution of gene frequencies for the markers studied was obtained as a whole in Georgia. The Georgians were compared for these markers with some populations of the Caucasus, Europe and West Asia. Among Caucasian populations, Georgians are most similar to Abkhasians. According to some systems, Georgians are close to European groups (ABO, Dubby, GLO-1, EstD), while they are similar to West-Asian groups, as judged by other systems (ABH secretion, AcP). According to Rhesus and MNSs systems, Georgians differ both from populations of Europe and from populations of West Asia.     

Genetics of human populations of Caucasus: distribution of various immunological and biochemical markers in eastern Georgia

The distribution of genetic markers of blood groups (AB0, P, Rhesus, MNSs, Duffy, Lewis, Kell-Cellano), of the serum proteins (Hp, Gc, Tf, C'3), red-cell enzymes (AcP, EstD, GLO1) and also ABH-secretion among seven native populations of Eastern Georgia has been studied. The frequencies of genes and haplotypes were calculated for the polymorphic markers and the results obtained were used in analysis of interpopulation variation and genetic relationship of these populations to their geographical neighbours as well as to European and West Asian populations.