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Biomedical subjects

A I Kozlov

Publications and source records attributed to A I Kozlov.

At least 19 recordsLinked to original sources
PubMed2004

Y chromosomal haplogroup J as a signature of the post-neolithic colonization of Europe.

In order to attain a finer reconstruction of the peopling of southern and central-eastern Europe from the Levant, we determined the frequencies of eight lineages internal to the Y chromosomal haplogroup J, defined by biallelic markers, in 22 population samples obtained with a fine-grained sampling scheme. Our results partially resolve a major multifurcation of lineages within the haplogroup. Analyses of molecular variance show that the area covered by haplogroup J dispersal is characterized by a significant degree of molecular radiation for unique event polymorphisms within the haplogroup, with a higher incidence of the most derived sub-haplogroups on the northern Mediterranean coast, from Turkey westward; here, J diversity is not simply a subset of that present in the area in which this haplogroup first originated. Dating estimates, based on simple tandem repeat loci (STR) diversity within each lineage, confirmed the presence of a major population structuring at the time of spread of haplogroup J in Europe and a punctuation in the peopling of this continent in the post-Neolithic, compatible with the expansion of the Greek world. We also present here, for the first time, a novel method for comparative dating of lineages, free of assumptions of STR mutation rates.

Africa, Northern↗
PubMed2001

A multistep process for the dispersal of a Y chromosomal lineage in the Mediterranean area.

In this work we focus on a microsatellite-defined Y-chromosomal lineage (network 1.2) identified by us and reported in previous studies, whose geographic distribution and antiquity appear to be compatible with the Neolithic spread of farmers. Here, we set network 1.2 in the Y-chromosomal phylogenetic tree, date it with respect to other lineages associated with the same movements by other authors, examine its diversity by means of tri- and tetranucleotide loci and discuss the implications in reconstructing the spread of this group of chromosomes in the Mediterranean area. Our results define a tripartite phylogeny within HG 9 (Rosser et al. 2000), with the deepest branching defined by alleles T (Haplogroup Eu10) or G (Haplogroup Eu9) at M172 (Semino et al. 2000), and a subsequent branching within Eu9 defined by network 1.2. Population distributions of HG 9 and network 1.2 show that their occurrence in the surveyed area is not due to the spread of people from a single parental population but, rather, to a process punctuated by at least two phases. Our data identify the wide area of the Balkans, Aegean and Anatolia as the possible homeland harbouring the largest variation within network 1.2. The use of recently proposed tests based on the stepwise mutation model suggests that its spread was associated to a population expansion, with a high rate of male gene flow in the Turkish-Greek area.

Alleles↗
PubMed2000

Lactase haplotype diversity in the Old World.

Lactase persistence, the genetic trait in which intestinal lactase activity persists at childhood levels into adulthood, varies in frequency in different human populations, being most frequent in northern Europeans and certain African and Arabian nomadic tribes, who have a history of drinking fresh milk. Selection is likely to have played an important role in establishing these different frequencies since the development of agricultural pastoralism approximately 9,000 years ago. We have previously shown that the element responsible for the lactase persistence/nonpersistence polymorphism in humans is cis-acting to the lactase gene and that lactase persistence is associated, in Europeans, with the most common 70-kb lactase haplotype, A. We report here a study of the 11-site haplotype in 1,338 chromosomes from 11 populations that differ in lactase persistence frequency. Our data show that haplotype diversity was generated both by point mutations and recombinations. The four globally common haplotypes (A, B, C, and U) are not closely related and have different distributions; the A haplotype is at high frequencies only in northern Europeans, where lactase persistence is common; and the U haplotype is virtually absent from Indo-European populations. Much more diversity is seen in sub-Saharan Africans than in non-Africans, consistent with an "Out of Africa" model for peopling of the Old World. Analysis of recent recombinant haplotypes by allele-specific PCR, along with deduction of the root haplotype from chimpanzee sequence, allowed construction of a haplotype network that assisted in evaluation of the relative roles of drift and selection in establishing the haplotype frequencies in the different populations. We suggest that genetic drift was important in shaping the general pattern of non-African haplotype diversity, with recent directional selection in northern Europeans for the haplotype associated with lactase persistence.

Africa South of the Sahara↗
PubMed2000

Genetic and environmental influence on the asymmetry of dermatoglyphic traits.

Fluctuating asymmetry (FA) is defined as random deviations from bilateral symmetry of the body. Thus, its magnitude is often used to evaluate developmental homeostasis. In this study we evaluate the following hypotheses: 1) FA of dermatoglyphic traits has a significant genetic component; 2) prenatal maternal environment (PME) has a significant effect on the FA of dermatoglyphic traits in developmentally healthy individuals; and 3) genetic or environmental factors affect FA on organismal or systemic levels. Therefore, their effect is better seen in composite scores of FA rather than in FA indices for single traits. We analyzed 15 dermatoglyphic traits from 140 pairs of monozygous twins, 120 pairs of dizygous twins, and 106 pairs of mothers and daughters. All individuals were developmentally healthy. The influence of genetic and environmental factors on FA was evaluated by analysis of variance and regression analysis. For a majority of the traits in our study, FA showed significant but weak heritabilities, with values falling within the 0.20-0.35 range. None of the traits taken separately demonstrated the effect of PME on FA to be significantly greater than zero. The composite score of FA tended to have greater heritability values than individual traits. One of them, obtained in principal components analysis, showed a significant PME effect, supporting the hypothesis that FA is a systemic property.

Analysis of Variance↗
PubMed1998

Hypolactasia in the indigenous populations of northern Russia.

The distribution of hypolactasia (PH) in the indigenous populations of the polar and related territories of the Russian Federation was investigated by an oral lactose tolerance. The frequency of hypolactasia in Kildin Saami population is 48%, Komi-Izhem-63%, Northern Mansi-71%, Northern Khanty-72%, West Siberia Nenets-78%. Generally hypolactasia frequencies in indigenous groups of Arctic and Sub-Arctic territories of Russia are higher than in the "reference" samples of Slav (Russian, 40-49%) and Permian Finn (Komi-Permiak and Udmurtian, 50-59%) groups.

Adolescent↗
PubMed1998

[Genogeographic primary hypolactasia in the Old World populations].

The geographic distribution of primary hypolactasia (i.e., the genetically determined (LAC*R), age-dependent decrease in lactase activity, which is phenotypically expressed as the intolerance to whole milk), was studied. Data on the distribution of primary hypolactasia and the LAC*R gene frequencies in populations of the Old World are analyzed, with special emphasis on LAC*R distribution in Russia. New data on populations of Kildin Saamis, Mordovian ethnic groups (Mokshas and Erzyas), Udmurtians, Komi-Permiaks, Komi-Zyrians (Komi-Izhem ethnographic group), Northern (Sos'va) Mansis, Northern Khantys, and Russians are described. Gene geographic maps of the LAC*R gene's distribution in populations of the Old World, Europe, and the Ural region were constructed. A map reflecting the amount of the original information on different regions and, therefore, the reliability of the gene geographic maps, is given. In Europe, the interpopulation diversity Gst of the LAC*R gene was significantly higher (0.169) than the average diversity of the European gene pool. The high variation was assumed to result from a potent differentiating selection that affects the gene for primary hypolactasia.

Africa↗
PubMed1992

[Lactase polymorphism in representatives of different ethnic-territorial groups].

Lactase polymorphism was studied in the native population of West Siberia and also in Buryatia. LAC*R frequency observed is-Khants- 0.8367, Mansi - 0.8660, Nenets - 0.8944, Buryats - 0.6883. The data obtained are considered to be the result of natural selection under traditional historical economical-cultural environment of the ethnic groups in question.

Ethnicity↗
PubMed1990

[Signet ring cell carcinoma of Brunner's glands].

Signet-cell carcinoma of Brunner's glands and two chronic ulcers of the duodenum were revealed in the course of the histologic examination of the autopsy material from a 76-year-old patient. One of the ulcers penetrated into the pancreas. This case is interesting for rare occurrence of Brunner's glands carcinoma and its combination with chronic duodenum ulcers.

Adenocarcinoma, Mucinous↗
PubMed1989

[Topographic and quantitative characteristics of adipose tissue in various aborigines of Siberia (women)].

The main task of the investigation is to prove suitability of the scheme suggested for estimation of the dynamics of fat content in the organism, in order to analyse age changeability of topography and amount of the subcutaneous fat in 254 women of various race-geographic groups in Siberia and populations, belonging to different adaptive groups. Representatives of the central-east-european (Russians), north europeoid (Komi), uralian (Manci) and central-asian (Buryats) race groups have been investigated. Age groups of 18-23 and 24-55 years of age have been compared. The first group gives possibilities to estimate the fat content value in the body composition and peculiarities in distribution of the subcutaneous fat in persons at early period of maturation; the second group--to follow age alterations of certain signs. For the representatives of the first group predominance of the subcutaneous fat below the waist is specific. In Russians predominance of the subcutaneous fat in extremities in comparison with the trunk is noted in 47-50%, in Komi, Manci and Buryats--in 12-25%. In the older age group the summational skin-fold thickness of the adipose tissue changes but slightly. For the representatives of all elderly groups increase of the fat content above the waist with predominance in the trunk is specific.

Adipose Tissue↗
PubMed1983

[Evolutional aspects of changes in the configuration of the foot].

At late stages of anthropogenesis a high positive "hand--foot" structural correlation was disturbed. In paleoanthropuses from the Sxul group and in the fossil man from Sungiry, an excessive development of the fibular components of the foot ("lateralization") was revealed. Certain evolutional and morphological causes contributing to the appearance of this rare variant are considered. A conclusion is made that development of lateralization in the foot can support the hypothesis on transition towards a leading role of the hand at the natural selection of the "hand--foot" system only at the latest stages of anthropogenesis.

Animals↗