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At least 415 records · Page 23Linked to original sources
PubMed2005

[Effective size of the early-run sockeye salmon Oncorhynchus nerka population of Lake Azabach'e, Kamchatka Peninsula evaluation of the effect of interaction between subpopulations within a subdivided population].

The effect of subdivision on the effective size (Ne) of the early-run sockeye salmon Oncorhynchus nerka population of Lake Azabach'e (Kamchatka Peninsula) has been studied. The mode of this effect is determined by the relative productivity of the subpopulations and its magnitude, by the rate of individual migration among subpopulations and genetic differentiation. If the contributions of subpopulations (offspring numbers) are different, genetic differentiation can reduce the Ne of the subdivided population. At equal subpopulation contributions, genetic differentiation always increases the Ne of the subdivided population in comparison with a panmictic population. We have found that all sockeye salmon subpopulations of Azabach'e Lake produce equal offspring numbers contributing to the next generation. The genetic differentiation between sockeye salmon subpopulations is low, and the subdivision increases the Ne of the early-run race with reference to the sum of the effective sizes of the subpopulations by as little as 2%.

Animals↗
PubMed2005

[The "horse-shoe effect"of correspondence analysis for human population genetic structure and its population genetic explanation].

At present study, the reasons of "horse-shoe effect" in correspondence analysis for analyzing human population genetic structure was explained. Based on the structure of gene frequency matrix, we displaye the different patterns of Scallergram of correspondent analysis from different types of loci (HLA-A locus, and STR- CSF1PO locus in Chinese Han populations). The results indicate that different types of loci showed different patterns of Scallergram of correspondent analysis. When some alleles have very low frequency in the gene frequency matrix, there would be "horse-shoe effect" in the Scallergram of correspondent analysis. The reason is that the c2 distance measurement in correspondent analysis usually overrates the effect of the genes with low frequencies. To carry out the correspondent analysis of human population genetic structure, when the Scallergram presents "horse-shoe effect", one should examine the structure of gene frequency matrix, and confirm whether the "horse-shoe effect" shows the real pattern of population genetic structure. Only in this way, one can explain the "horse-shoe effect" correctly.

Alleles↗
PubMed2006

The population genetics of phenotypic deterioration in experimental populations of Bacillus subtilis.

Although many examples of trait loss exist in nature, the underlying population genetic mechanism responsible for the loss is usually unknown. Selective or neutral processes can result in the deterioration of a trait, and often one of these is inferred based on indirect evidence. Furthermore, selective pressures that are unique to particular environments and the effect these might have on the population genetic cause of trait loss are not well understood. Here we describe an experimental evolution system where two different environments were used for addressing the population genetic cause of trait loss throughout evolutionary time. We found that growth in minimal medium (i.e., prototrophy) was lost in all populations regardless of the experimental environment and that the pattern of trait loss in one environment was due to selection, whereas in the other environment the cause remains inconclusive.

Bacillus subtilis↗
PubMed1986

[Medico-genetic study of the population of Uzbekistan. VIII. Territorial distribution of hereditary diseases in the population of four regions of the Khorezm province and its genetic load].

The load of hereditary diseases was estimated on the basis of data obtained during medical-genetic study of the population of four districts of Khorezm province. The load of autosomal recessive disorders comprised 2-3 X 10(-3) affected, that of autosomal dominant disorders - 0.4-0.5 X 10(-3) and that of X-linked disorders - 0.2-0.4 X 10(-3) males. The main part of patients with autosomal recessive disorders belonged to separate families randomly spread over the populations. A trend for local accumulation of families with the same disorder was observed in small populations. It was shown that overall frequency of autosomal recessive genes per individual increased with the increase in the population size.

Gene Frequency↗
PubMed1986

[Medico-genetical study of the Uzbekistan population. IX. Variability of hereditary pathology, territorial distribution of hereditary diseases and hereditary disease load in the population of the Urgut district of the Samarkand region].

Medical-genetic study was carried out in the population of Samarkand province (the population size about 150 000). Hereditary pathology was ascertained among families with two or more affected members with chronic diseases. 110 families with 210 patients were registered. The most frequent were autosomal-recessive disorders (42 nozological forms). 15 nozological forms are probably "new" conditions in this province, because they were absent in our previous medical-genetic study of this province. A tendency to local accumulation of families with the same disorder in small populations was observed. The load of autosomal-recessive disorders comprised 2.2 X 10(-3) affected, that of autosomal-dominant disorders being 0.51 X 10(-3) and of X-linked disorders being 0.25 X 10(-3) males. The importance of assortative maitings in manifestation of rare autosomal-recessive genes in Uzbek population is discussed.

Female↗
PubMed1978

An estimate of a rare population group: the U.S. Jewish population.

High, middle, and low estimates for a rare population group, the Jewish population of the United States, are presented together with their root mean square errors. These estimates are based upon a national sample whose essential survey design features are outlined. The features indicate that difficult-to-find populations can be sampled in adequate numbers if some sort of a list can be developed with a fair proportion of the population. To this list must be added an integrated area sample.

Housing↗
PubMed1994

Mitochondrial DNA polymorphism in natural populations of Drosophila albomicans (I)--Remarkable mtDNA polymorphism in the population of D. albomicans.

The technique of mtDNA restriction fragments length polymorphism (RFLP) was used to survey the population structure of D. albomicans. Remarkable mtDNA polymorphism has been observed in D. albomicans populations. A total of 34 nucleomorphs were detected from 82 isofemale lines assayed by only 8 restriction enzymes. The cause and the effect of this phenomenon were discussed. As a result, it is suggested that a mechanism which maintains mtDNA diversity exists in this fly, and that the high intra-populational polymorphism could numerically conceal the extent of differentiation between populations. In addition, on the base of restriction maps, it was found that the mtDNA molecule of D. albomicans might be impacted by the selection pressure during its evolution process both on the nucleotide composition and on the functional regions.

Animals↗
PubMed1993

[Population-genetic characteristic of the rural population of southern Tajikistan].

The results of genetic and demographic study of the inhabitants in south Tadjikistan are presented. It had been shown that the population studied is a typical rural population of Middle Asia and is characterized by the extended reproductive capacity, homogeneity of national composition and a high proportion of consanguineous marriages. Genetic variation in blood groups (AB0, MN, Rh-D, P1), serum proteins and red cell enzyme systems (Tf, Gc, Hp, PGM1, PGD, EsD, AcP1) was examined. A comparative analysis of gene frequencies in the population studied and some other Middle Asia populations has been carried out.

Adolescent↗
PubMed1996

Population structure and genetic differentiation among 16 tribal populations of central India.

Genetic polymorphisms for six blood groups, three red cell enzymes, three serum proteins, and hemoglobin were examined in sixteen central Indian tribal populations. Nine of the tribes belonged to Orissa, five to Madhya Pradesh, and two to Maharashtra. Eleven tribes spoke the Dravidian language, three Indo-Ayran, and two the language of the Austro-Asiatic families. The population structure of these tribal populations was analyzed at the inter- and intrastate and linguistic levels, using data for 13 genetic systems (38 alleles or haplotypes). Nine of the 13 loci showed significant heterogeneity in the 16 tribes, and the pattern of heterogeneity was also discernible in the different states and in the Dravidian-speaking tribes. As expected, the extent of genetic differentiation or gene diversity was the highest so far reported from central India. The mean FIS and HS for each locus in the different state, linguistic, and total tribal groups were consistently higher than the FST and GST values, respectively, showing that the genetic structure of each tribe is highly influenced by inbreeding. In a genetic affinity analysis by genetic distance the Indo-Aryan and Austro-Asiatic language groups showed little affinity with each other, although there was some tendency toward geographic affinity. The present analysis indicates that, in addition to genetic drift, gene flow, and selection, the genetic structure of the populations of central India is also highly influenced by sociocultural adaptation and inbreeding.

Ethnicity↗
PubMed1977

[Population surveillance and its importance in the study of the effectiveness of primary and secondary prevention of ischemic heart disease among the population].

The results of epidermiologic surveys conducted in the USSR and in other countries are briefly analysed. It is noted that study of the effectiveness of the elaborated measures for primary and secondary prevention of ischemic heart disease is the principal object of long-term surveys among the population. The author believes the term population surveys to be most justified. The general principles of the organization of population surveys are described. Approaches to the evaluation of the effectiveness of intervention among the population are briefly characterized.

Adult↗
PubMed1992

Population and women in development: gender issues in the context of population and development.

"The objective of this paper is to examine women's productive and reproductive roles and their intricate linkages and the interplay with the demographic variables of population and development. Although these interactions...are not yet fully understood, attempts will be made utilizing available data and literature to make an analysis of the linkages and interplays that exist between population variables with factors associated with the role, status and participation of women in the social and economic lives of African societies.... The paper will analyze the linkages and integrate the implications for population policies and programmes towards the enhancement of women's role and status and their participation in the development process."

Africa↗
PubMed1996

[Population and underdevelopment--thoughts on the Cairo International Conference on Population and Development].

The continuing rapid growth of world population, particularly in the developing countries, is described. "The backward social and economic environment is not able to keep pace with the growing population. The result is an increasing population pressure which finds its expression in unemployment, hunger, the depletion of...nature, deforestation as well as migration, uncontrolled expansion of the cities and slum-building. These problems [already have] global dimensions and their aggravation is expected in the next 30 years. Our civilisation is exposed to these global risks. And we have no practicable conception for solving them." (SUMMARY IN ENG)

Conservation of Natural Resources↗
PubMed1995

[Cohort analysis of population distribution change in Japan: processes of population concentration in the Tokyo region and its future].

"This paper aims at analyzing the relationships between net-migration and the transition of population distribution from the perspective of cohort analysis. The article consists of three parts: (1) review of...previous studies...; (2) evaluation of the transition of population distribution in Japan...; (3) presentation of a new projection method, where a basic concept of a new method for regional population projection and the preliminary trial for the Tokyo Region are discussed." (SUMMARY IN ENG)

Asia↗
PubMed1981

[Dermatoglyphics in the study of genetic processes in human populations (the example of the population of Arminia)].

Demographic data on the sizes of local populations of Armenia and the rates of people migration were employed for prediction of genetic differentiation level using S. Wright's f-statistics. This expected value of fe was applied for approximation of the observed level of dermatoglyphic f0d and familial f0n differentiation. Both empirical estimations of f were found to be closely to each other (f0d = 0,0616, f0n = 0,0600) and fall within the limits 0,0712 greater than or equal to fst greater than or equal to 0,0580 predicted from "island" model of Armenian population structure. The present state and direction of the genetic process in Armenia is discussed in the paper with the main conclusion that the dermatoglyphics and family surnames could be used in studies of the genetic process in human population.

Armenia↗
PubMed1996

[Geography of effective size of rural populations of Northern Eurasia. Geographic correlation between effective size and level of heterozygosity of populations].

A significant geographical correlation (r = 0.719) was found between the logarithm of effective size (InNe) and heterozygosity level (H) in populations under the assumption of the Hardy-Weinberg equilibrium. The area of highest positive correlation was positioned meridionally between the Ob and Yenisei rivers, from the Arctic coast of Taimyr Peninsula to eastern Sayans and the southern Cis-Baikal region, i.e., in the same region where the highest distribution density of mean Ne values was found. Two additional areas of high correlations were found on the northern Black Sea coast and in the lower Lena river region. Analysis and mapping of correlation ratios eta H/lnNe2 and eta lnNe/H2 revealed that effective size substantially influenced heterozygosity level (as could be expected in the case of an intense gene drift), and heterozygosity level influenced effective size to the same extent. The latter relationship indicated an intense adaptation, and changes in diversity of the gene pool caused substantial demographic changes. However, this might be accounted for by direct gene migration into a population prevailing over reverse migration, i.e., mechanical population growth prevailing over natural growth.

Adaptation, Physiological↗
PubMed1990

Patterns of skeletal histologic change through time: comparison of an archaic native American population with modern populations.

This paper compares patterns of histologic change in an archaic Native American population with those in modern white populations. Histologic sections were removed from core biopsies taken from the anterior femoral cortex of an archeologic sample of Pecos Indians. The data demonstrate many microstructural similarities between the Pecos and modern populations, even though they were genetically and culturally distinct. Pecos women had small Haversian canals and large osteon mean wall thickness, with no clear evidence of an intracortical bone volume deficit even in the older age groups, although significant marrow cavity expansion occurred in both males and females with age. No striking relationships were found between bone tissue changes and gross geometric changes with age. The data suggest that a more active life-style is associated with greater osteon mean wall thickness or osteon population density, but that it alone does not protect against significant bone loss on the cortical-endosteal surface.

Adult↗
PubMed1984

Precursor lesions of oesophageal cancer in a low-risk population in China: comparison with high-risk populations.

An endoscopic survey was undertaken in Jiaoxian, People's Republic of China, a population at low risk for oesophageal cancer, to determine the prevalence of precancerous lesions of the oesophagus, and this rate was compared with the prevalence observed previously in high-risk populations in Iran and Linxian, China. The study involved 252 subjects whose exposure to suspected risk factors was determined by a questionnaire and all of whom underwent physical examination and oesophagoscopy, including cytology and biopsy. Chronic oesophagitis, with endoscopic and histologic characteristics similar to those observed in the high-risk populations of Iran and Linxian, was found in 28% of the study subjects compared to 80% in Iran and 65% in Linxian. Oesophagitis accompanied by atrophy of the epithelium was found in 0.4% compared to 10.5% in Iran and 10.8% in Linxian. No case of dysplasia was diagnosed in Jiaoxian while this condition was diagnosed in 4% of the subjects examined in Iran and in 8% of those in Linxian. The findings suggest that these lesions are in fact precancerous. Vitamin analysis showed that riboflavin deficiency was widespread in Jiaoxian, as in Iran and Linxian, but was more severe in Linxian than in Jiaoxian. No significant difference was found in the mean levels of retinol, beta-carotene and zinc between the two populations.

Adolescent↗
PubMed1999

Abdominal adiposity in six populations of West African descent: prevalence and population attributable fraction of hypertension.

OBJECTIVES: The objective of this investigation was to examine the prevalence of abdominal adiposity and its association with the prevalence of hypertension among African descent populations in Nigeria, Cameroon, Jamaica, St. Lucia, Barbados, and the United States (US). RESEARCH METHOD: The data for this investigation were obtained from the International Collaborative Study on Hypertension in Blacks. Hypertension was defined as mean diastolic blood pressure > or =90 mmHg, systolic blood pressure > or = 140 mmHg or current treatment with prescribed anti-hypertension medication. Abdominal overweight was defined as waist circumference (WC) > or =94 and > or =80 cm for men and women, respectively. Abdominal obesity was defined as WC > or =102 and > or =88 cm for men and women, respectively. We estimated the site-specific prevalence of abdominal overweight and obesity across age and body mass index cut-points. We also calculated the population attributable fraction (AF) of hypertension due to abdominal adiposity. RESULTS: The prevalence of hypertension in these populations was tightly linked to abdominal adiposity. Increases in abdominal overweight accompanied an increasing degree of Westernization, rising from 6.4% and 26.3% in Nigeria, 16.5% and 62.8% in Cameroon, 15.8% and 58.6% in Jamaica, 14.3% and 62.1% in St. Lucia, 21.4% and 70.3% in Barbados to 38.9%, and 76.4% in the US for men and women, respectively. The corresponding values for abdominal obesity were 1.6% and 12.3% in Nigeria, 5.1% and 38.9% in Cameroon, 5.5% and 34.0% in Jamaica, 2.7% and 40.7% in St. Lucia, 7.8% and 44.7% in Barbados to 21.7% and 54.1% in the US for men and women, respectively. Body mass index-adjusted estimates of AF suggest that in most of these populations, especially in females, avoidance of abdominal overweight or obesity would help to curb the development of hypertension. DISCUSSION: An important public health challenge is to clarify how lifestyle factors influence risks of abdominal adiposity and ultimately the increased risk of cardiovascular diseases.

Abdomen↗