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Results for “Gene Pool”

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At least 109 records · Page 6Linked to original sources
PubMed1998

Signs of glaucoma in rhesus monkeys from a restricted gene pool.

PURPOSE: To investigate the distribution of intraocular pressure (IOP) and cup properties in a colony of rhesus monkeys that has had no outside genetic input since 1938 (approximately 12 generations). This sample of sequestered monkeys is significantly larger than any previously reported. Comparisons are made with a sample of random-source monkeys to develop population estimates defining the limits of normalcy. METHODS: The IOP and cup/disc ratio estimates were collected from 701 eyes of 354 adult rhesus monkeys from the closed colony on Cayo Santiago, Puerto Rico. Results for IOP were compared with the normal rhesus IOP population distribution function calculated from an earlier sample of genetically heterogeneous rhesus. RESULTS: The mean +/- standard deviation IOP in the Cayo Santiago monkeys (15.8+/-3 mmHg) related well to the calculated "normal" rhesus distribution (14.5+/-2 mmHg) below and around the mean IOP only. Above the mean rhesus IOP, the samples from the Cayo monkeys were strongly skewed: 129 eyes had IOP more than two standard deviations above the normal mean IOP, and 54 eyes had IOP more than three standard deviations above the normal mean IOP. Cup/disc ratio estimations tended to cluster as higher values in the higher IOP quartiles. Some eyes with IOP below the mean had cup/disc ratios > 0.5. Values for IOP that were more than two standard deviations above the mean and cup/disc ratios > 0.4 were not uniformly distributed across social groupings, although incidence of high IOP was more than 25% in one group. CONCLUSION: After 12 generations with the same genetic pool, expression of ocular hypertension and large optic disc cups is high but not uniform.

Animals↗
PubMed1999

Broad-sense sexual selection, sex gene pool evolution, and speciation.

Studies of sexual selection have traditionally focused on explaining the extreme sexual dimorphism in male secondary sexual traits and elaborate mating behaviors displayed by males during courtship. In recent years, two aspects of sexual selection have received considerable attention in the literature: an extension of the sexual selection concept to other traits (i.e., postcopulatory behaviors, external and internal genital morphology, gametes, molecules), and alternative mechanistic explanations of the sexual selection process (i.e., coevolutionary runaway, good-genes, sexual conflicts). This article focuses on the need for an extension of sexual selection as a mechanism of change for courtship and (or) mating male characters (i.e., narrow-sense sexual selection) to all components of sexuality not necessarily related to courtship or mating (i.e., broad-sense sexual selection). We bring together evidence from a wide variety of organisms to show that sex-related genes evolve at a fast rate, and discuss the potential role of broad-sense sexual selection as an alternative to models that limit speciation to strict demographic conditions or treat it simply as an epiphenomenon of adaptive evolution.

Animals↗
PubMed2006

What is a population? An empirical evaluation of some genetic methods for identifying the number of gene pools and their degree of connectivity.

We review commonly used population definitions under both the ecological paradigm (which emphasizes demographic cohesion) and the evolutionary paradigm (which emphasizes reproductive cohesion) and find that none are truly operational. We suggest several quantitative criteria that might be used to determine when groups of individuals are different enough to be considered 'populations'. Units for these criteria are migration rate (m) for the ecological paradigm and migrants per generation (Nm) for the evolutionary paradigm. These criteria are then evaluated by applying analytical methods to simulated genetic data for a finite island model. Under the standard parameter set that includes L = 20 High mutation (microsatellite-like) loci and samples of S = 50 individuals from each of n = 4 subpopulations, power to detect departures from panmixia was very high ( approximately 100%; P < 0.001) even with high gene flow (Nm = 25). A new method, comparing the number of correct population assignments with the random expectation, performed as well as a multilocus contingency test and warrants further consideration. Use of Low mutation (allozyme-like) markers reduced power more than did halving S or L. Under the standard parameter set, power to detect restricted gene flow below a certain level X (H(0): Nm < X) can also be high, provided that true Nm < or = 0.5X. Developing the appropriate test criterion, however, requires assumptions about several key parameters that are difficult to estimate in most natural populations. Methods that cluster individuals without using a priori sampling information detected the true number of populations only under conditions of moderate or low gene flow (Nm < or = 5), and power dropped sharply with smaller samples of loci and individuals. A simple algorithm based on a multilocus contingency test of allele frequencies in pairs of samples has high power to detect the true number of populations even with Nm = 25 but requires more rigorous statistical evaluation. The ecological paradigm remains challenging for evaluations using genetic markers, because the transition from demographic dependence to independence occurs in a region of high migration where genetic methods have relatively little power. Some recent theoretical developments and continued advances in computational power provide hope that this situation may change in the future.

Biological Evolution↗
PubMed1977

[Koryaks of Kamchatka. The genetic characteristics and formation of a gene pool].

Investigation of korak population of Kamchatka is carried out for 10 non-linked blood groups loci, serum proteins, PTC taste and ABH antigens secretion. The korak population enters in the system of Middle Asian mongoloids for the genetical characteristics studied. Koraks occupy an intermediate position between Siberian and Far East populations in their genetic pecularities, revealing the most close genetical similarity with Siberian population. The main contribution in the genofond of ancient korak athnic community is carried by neolytic inhabitants of Siberia.

Asia, Southeastern↗
PubMed1984

Prevalence of diabetes in Mexican Americans. Relationship to percent of gene pool derived from native American sources.

We have estimated the prevalence of non-insulin-dependent diabetes mellitus (NIDDM) in Mexican Americans and Anglos in three San Antonio neighborhoods. The age-adjusted NIDDM rates (both sexes pooled) for Mexican Americans were 14.5%, 10%, and 5% for residents of a low-income barrio, a middle-income transitional neighborhood, and a high-income suburb, respectively. In Mexican American women, though not in men, obesity also declined from barrio to suburbs. We have previously shown, however, that, although obesity is an important cause of NIDDM in Mexican Americans, there is a two- to fourfold excess in the rate of NIDDM in this ethnic group over and above that which can be attributed to obesity. We therefore speculated that genetic factors might also contribute to excess NIDDM in this ethnic group. The percent native American admixture of Mexican Americans as estimated from skin color measurements was 46% in the barrio, 27% in the transitional neighborhood, and 18% in the suburbs. The NIDDM rates in Mexican Americans thus paralleled the proportion of native American genes. Furthermore, the San Antonio Mexican American rates were intermediate between the NIDDM rates of "full-blooded" Pima Indians (49.9%), who presumably have close to 100% native American genes, and the San Antonio Anglo population (3.0%) and the predominantly Anglo HANES II population (3.1%), both of which presumably have few if any native American genes. The association of genetic admixture with NIDDM rates suggests that much of the epidemic of NIDDM in Mexican Americans is confined to that part of the population with a substantial native American heritage.

Adult↗
PubMedDate not supplied

[Gene pool of the population of Ukraine: Current state and new approaches to maintenance and conservation].

Defense and conservation of the Ukraine Population genofond are the most topical problem of nowadays. Stating of the criteria of population genofond status valuation, revealing all the damaging factors and applying of scientific methods of modern genetics are necessary for the development of theoretical and methodological bases of this problem. The authors try to analyze in detail negative factors causing damage in genofond of the Ukraine population, to forecast the dynamics of further development of ecological-genetic situation in the Ukraine, to analyze new approaches to the problem of genofond defense and conservation, as well as estimation of possible consequences caused by changes in population genofond.

Ecology↗
PubMed2001

[T4336C variant--a marker of mitochondrial subgroup H1, a common component of the Russian and German gene pool].

Analysis of mitochondrial DNA (mtDNA) restriction polymorphism carried out in a sample of Russians from Magadan (n = 150) showed that the frequency of the +4332AvaII variant (a T-C transition at nucleotide position 4336) in this population was 4.7%. All +4332AvaII types of mtDNA belonged to the mitochondrial group H. They were characterized by a back of the AluI restriction endonuclease site at position 7025. According to hypervariable segment 1 sequencing data, they contained the 16304C variant, and thus belong to the subgroup H1. Thus, the +4332AvaII (T4336C) variant is a marker of the mitochondrial subgroup H1, chiefly occurring in German-speaking populations. Utilization of the H1-mtDNA markers for the investigation of the genetic history and the origin of Slavs is discussed.

DNA, Mitochondrial↗
PubMed1998

[Characteristics of the gene pool of Russian Old Believers in Siberia based on polymorphism of blood groups, isoenzymes, and blood proteins].

The frequency distributions of A1A2B0, Rhesus, MNSs, P, Duffy, Kell, Hp, Tf, AcP, PGM1 alleles, and haplotypes were studied in Siberian populations of Old Believers (Burnyi village, Krasnoyarskii krai, and Isetskii raion, Tyumenskaya oblast) and in ethnic Russians from Tyumenskaya oblast. Features characteristic of the genetic structure of these groups were revealed. The Siberian groups of Russians were shown to be genetically removed from European Russian populations (Tverskaya and Vologodskaya oblasts). The Burnyi population of Old Believers was significantly removed from the other groups of Russians due to peculiarities in the sample.

Blood Group Antigens↗
PubMed1982

Survey of the extrachromosomal gene pool of Clostridium difficile.

Pseudomembranous colitis, a severe diarrheal disease, has been linked to the administration of antibiotics and to two toxins produced by Clostridium difficile. Eighty-two strains of C. difficile isolated from humans and hamsters were assayed for the presence of plasmid DNA. Agarose gel electrophoresis of Sarkosyl-lysed cells indicated that 18% of the strains contained from one to four plasmids. The plasmid DNA in these strains ranged in molecular weight from 2.7 X 10(6) to 60 X 10(6). Strains with and without plasmids were examined for the cytopathogenic effect of the toxins on MRC-5 cells. No correlation was observed between plasmid content and cytopathogenic effect. The results of in vitro antibiotic susceptibility testing with plasmid-containing strains revealed that 33% of the strains tested exhibited growth with four or more of the antimicrobial agents used.

Anti-Bacterial Agents↗
PubMedDate not supplied

[African DNA lineages in mitochondrial gene pool of Europeans].

Mitochondrial DNA (mtDNA) nucleotide sequences of African origin have been found at low frequency (1%, in average) in different European populations. In the present study, data on mtDNA variability in populations of Eurasia and Africa are analyzed and search of African-specific lineages present in Europeans is conducted. The results of analysis indicate that, despite a high diversity of African mtDNA haplotypes found in Europeans, monophyletic clusters of African mtDNA lineages, arisen in Europe and characterized by long-term diversity, are nearly absent in Europe. Only two respective clusters (belonging to haplogroups L1b and L3b), which evolutionary age does not exceed 6.5 thousands years, were revealed. Comparative analysis of distribution of frequencies of autosomal microsatellite alleles found in Russian individuals, carrying the African-specific mitochondrial haplotypes, in populations of Europe and Africa has indicated that autosomal genotypes of those Russian individuals are characterized by the presence of alleles characteristic mostly for Europeans.

Africa↗
PubMed1998

Beta1,4-galactosyltransferase and lactose biosynthesis: recruitment of a housekeeping gene from the nonmammalian vertebrate gene pool for a mammary gland specific function.

Beta1,4-galactosyltransferase (beta4GalT-I) is a constitutively expressed trans-Golgi enzyme, widely distributed in vertebrates, which synthesizes the beta4-N-acetyllactosamine structure commonly found in glycoconjugates. In mammals beta4GalT-I has been recruited for a second biosynthetic function, the production of lactose; this function takes place exclusively in the lactating mammary gland. In preparation for lactose biosynthesis, beta4GalT-I enzyme levels are increased significantly. We show that mammals have evolved a two-step mechanism to achieve this increase. In step one there is a switch to the use of a second transcriptional start site, regulated by a stronger, mammary gland-restricted promoter. The transcript produced is distinguished from its housekeeping counterpart by the absence of approximately 180 nt of 5'-untranslated sequence. In step two, this truncated transcript is translated more efficiently, relative to the major transcript expressed in all other somatic tissues.

Animals↗
PubMed1995

[Computer technology of gene geographic analysis of a gene pool: III. Derivation of trend surfaces].

A computer technology for obtaining a set of trend (background) maps on the basis of an original geographic map is reported. These trend maps reveal the patterns of distribution of the mapped trait. The technology allows one to shape the reliefs of the genetic surfaces that reflect patterns having different origin and appearing at different times, via changing the parameters of algorithms for averaging and approximation. The set of maps, which is obtained with the use of approximation methods, simulates the hypotheses of the through trend and of the mono-, di-, or polycentric distribution of the trait. New methods for deriving the trend surfaces on the basis of averaging throughout the area of either the "moving window" or the window of variable size ("changing window") are proposed. The informative significance of maps that are obtained with the use of Chebyshev polynomials of high (up to several tens of) degrees is demonstrated.

Algorithms↗
PubMed2003

The influenza virus gene pool in a poultry market in South central china.

We surveyed influenza activity in a live poultry market in Central China for 16 months, isolating viruses from 1% of 6360 fecal samples. We obtained multiple H3N6, H9N2, H2N9, H3N3, and H4N6 isolates and single H1N1 and H3N2 isolates. Two distinct H3 molecules were identified; other hemagglutinin subtypes were phylogenetically homogeneous. The H3N6 viruses (9 genotypes) and H9N2 viruses (4 genotypes) were genetically heterogeneous, whereas the H2N9, H3N3 and H4N6 viruses had single genotypes. Thirteen representative viruses were tested for their ability to replicate in quail and chickens. All tested viruses replicated in the respiratory tract of quail. Only nine of the viruses were shed in detectable levels in infected chickens, and four of these were detected in less than 50% of infected birds. A single H4N6 isolate caused disease and systemic spread in chickens. These findings show that quail are broadly susceptible to different subtypes of influenza A virus.

Animals↗
PubMed1983

Multiple-locus departures from panmictic equilibrium within and between village gene pools of Amerindian tribes at different stages of agglomeration.

A comparative analysis of departures from multiple-locus Hardy-Weinberg equilibrium is presented for a set of four tribal Indian groups (the Yanomama, Makiritare, Wapishana and Ticuna) from the lowlands of South America. These tribes span a range of agglomeration and acculturation from the most traditional, swidden horticulturalists to frontier townspeople. The small-group social organization typical of traditional horticulturalists leads to substantial departures from tribal panmixia, as manifested by the distribution of multiple-locus genotypes both within and between villages. Within villages, the departures from single-locus Hardy-Weinberg equilibrium are small and nonsignificant, but the departures from gametic equilibrium (independence of loci) are substantial, even for the unlinked loci we have used to characterize these populations. The departures from single-locus homogeneity across villages are also substantial. One of the normal concomitants of increasing acculturation in this setting is an increase in agglomeration. As agglomeration increases, the departures from multiple-locus panmixia decrease, a process that can be very rapid. We discuss both the shifting balance theory of evolution and punctuated evolutionary rates in light of the small group social organization that must have obtained throughout most of human evolution.

Brazil↗
PubMed1995

[Gene pool of residents of northeastern Eurasia in light of data on polymorphism of mitochondrial DNA. I. New data on polymorphism of restriction sites of the D-loop of mtDNA in aboriginal populations of the Caucasus and Siberia].

New data about eleven polymorphic sites of restriction in the D-loop of mtDNA revealed with the Ava II, BamH I, EcoR V, Hae III, Kpn I, Rsa I, and Sau3A I restriction enzymes in native populations of the Caucasus (N = 40) and Siberia (N = 44) are presented. A comparison of these groups with each other and with common data for western and eastern Europe as well as for central and eastern Asia reveals a large similarity of all the population groups of Eurasia in respect to the frequency of each polymorphic site separately. The interpopulation differentiation of frequency of polymorphic restriction sites in Eurasia is low and identical at such different hierarchical levels of population structure as ethnic group and extended regional population group. An analysis of differences between sites in the frequency of the presence of restriction sites for BamH I, EcoR V, Hae III, and Sau3A I and the absence of sites for Ava II, Kpn I, and Rsa I at definite loci of the nucleotide chain allowed determination of the region of equilibrium between direct, site-generating, and reverse mutations to be 0.43q. Among eleven polymorphic restriction sites analyzed here, only polymorphism in the Hae III site at the position 16,517 in the population of Eurasia was characterized with frequencies close to equilibrium that determined the extremely large evolutionary age of this polymorphism.

Base Sequence↗
PubMed2004

The molecular dissection of mtDNA haplogroup H confirms that the Franco-Cantabrian glacial refuge was a major source for the European gene pool.

Complete sequencing of 62 mitochondrial DNAs (mtDNAs) belonging (or very closely related) to haplogroup H revealed that this mtDNA haplogroup--by far the most common in Europe--is subdivided into numerous subhaplogroups, with at least 15 of them (H1-H15) identifiable by characteristic mutations. All the haplogroup H mtDNAs found in 5,743 subjects from 43 populations were then screened for diagnostic markers of subhaplogroups H1 and H3. This survey showed that both subhaplogroups display frequency peaks, centered in Iberia and surrounding areas, with distributions declining toward the northeast and southeast--a pattern extremely similar to that previously reported for mtDNA haplogroup V. Furthermore, the coalescence ages of H1 and H3 (~11,000 years) are close to that previously reported for V. These findings have major implications for the origin of Europeans, since they attest that the Franco-Cantabrian refuge area was indeed the source of late-glacial expansions of hunter-gatherers that repopulated much of Central and Northern Europe from ~15,000 years ago. This has also some implications for disease studies. For instance, the high occurrence of H1 and H3 in Iberia led us to re-evaluate the haplogroup distribution in 50 Spanish families affected by nonsyndromic sensorineural deafness due to the A1555G mutation. The survey revealed that the previously reported excess of H among these families is caused entirely by H3 and is due to a major, probably nonrecent, founder event.

Base Sequence↗