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PubMed1978

Genetic variation, cellular distribution and ontogeny of sorbitol dehydrogenase and alcohol dehydrogenase isozymes in male reproductive tissues of the mouse.

Cellulose acetate zymograms of alcohol dehydrogenase (ADH) and sorbitol dehydrogenase (SDH) extracted from male reproductive tissues of inbred mice were examined. ADH isozymes were differentially distributed in these tissues of C3H/He mice; ADH-B2 was observed in all tissues and testis cellular preparations examined; ADH-C2 was localized predominantly in the epididymis but was also present in the seminal vesicles, coagulating gland, and prostate gland. SDH was broadly distributed in these tissues but exhibited highest activities in the seminal vesicles, coagulating glands, and germinal cells of mature testes. Genetic variants for ADH-C2 and SDH provided evidence for (1) the identity of a second form of SDH in epididymis with ADH-C2; (2) the genetic identity of kidney, seminal vesicle, and testis SDH; and (3) the gentic identity of stomach and epididymal ADH-C2. Developmental changes in testis and epididymal ADH isozymes during maturation were examined. ADH-C2 appeared in the mature epididymis whereas ADH-B2 exhibited no major changes in activity in testis and epididymis during development.

Alcohol Oxidoreductases↗
PubMed2005

Genetic variation and phylogeographic analyses of two species of Carpobrotus and their hybrids in California.

Despite the commonality and study of hybridization in plants, there are few studies between invasive and noninvasive species that examine the genetic variability and gene flow of cytoplasmic DNA. We describe the phylogeographical structure of chloroplast DNA (cpDNA) variation within and among several interspecific populations of the putative native, Carpobrotus chilensis and the introduced, Carpobrotus edulis (Aizoaceae). These species co-occur throughout much of coastal California and form several 'geographical hybrid populations'. Two hundred and thirty-seven individuals were analysed for variation in an approximate 7.0 kb region of the chloroplast genome using PCR-RFLP (polymerase chain reaction - restriction fragment length polymorphism) data. Phylogenetic analyses and cpDNA population differentiation were conducted for all morphotypes. Historic geographical dispersion and the coefficient of ancestry of the haplotypes were determined using nested clade analyses. Two haplotypic groupings (I and II) were represented in C. chilensis and C. edulis, respectively. The variation in cpDNA data is in agreement with the previously reported allozyme and morphological data; this supports relatively limited variation and high population differentiation among C. chilensis and hybrids and more wide-ranging variation in C. edulis and C. edulis populations backcrossed with C. chilensis. C. chilensis disproportionately contributes to the creation of hybrids with the direction of gene flow from C. chilensis into C. edulis. The cpDNA data support C. chilensis as the maternal contributor to the hybrid populations.

Aizoaceae↗
PubMed2006

Common genetic variation in the prothrombin gene, hormone therapy, and incident nonfatal myocardial infarction in postmenopausal women.

Genetic variants in coagulation factors are associated with myocardial infarction and may modify the association between hormone therapy and cardiovascular disease risk. This study assessed whether common variation in the prothrombin gene was associated with incident nonfatal myocardial infarction in postmenopausal women and whether this association differed according to current estrogen use. Eight variants representing 98% of common prothrombin variants were selected using publicly available genomic variation data. These variants and the functional G20210A variant were genotyped and used to infer haplotypes in a population-based Washington State case-control study of postmenopausal Caucasian women (1995-1999; 273 cases and 788 controls). Women carrying a nonsynonymous polymorphism in exon 6 (C5467T) had an increased risk of myocardial infarction (for each additional copy, relative to women with one fewer copy, odds ratio = 1.4, 95% confidence interval: 1.0, 1.8). Prothrombin haplotypes were also associated with myocardial infarction (with minimal adjustment, global p = 0.056; with full adjustment, p = 0.034). Associations between haplotypes and myocardial infarction were similar among users of hormone therapy and nonusers (global p = 0.61), though statistical power was limited. These preliminary results suggest that common genetic variants in the prothrombin gene or other variants in linkage disequilibrium are associated with myocardial infarction in postmenopausal women.

Aged↗
PubMed1989

Genetic variation within two linguistic Amerindian groups: relationship to geography and population size.

Nine Carib and eight Tupi groups were studied for a minimum of eight common polymorphic systems and compared in terms of genetic distances using the methods of Nei and Edwards. Two levels of genetic information were distinguished, one with a maximum of 20 loci and another with a maximum of 12 loci considered. The dendrograms produced consistent, reproducible results, independent of the method used, when a minimum of ten polymorphic systems were included in the analysis. Irrespective of the number of systems or the method used, the Tupi showed two to three times higher average interpopulation genetic distances than the Carib groups, which may be due to their lower average population sizes, allowing for the action of genetic drift and/or founder effects, as these two sets of populations do not differ significantly in geographic range, years of contact with non-Indians, or degree of acculturation.

Bolivia↗
PubMed1977

Genetic variation in antibody response and natural killer cell activity against a Moloney virus-induced lymphoma (YAC).

Antibody formation against the Moloney virus-determined surface antigen (MCSA) was found to be under genetic control. In the (A X C57BL)F1 cross one dominant gene played a major role, resulting in bimodal distribution of the antibody response. This gene showed no linkage to H-2, IgG heavy chain immunoglobulin allotype, the coat color markers B and C, and five different isozyme markers representing chromosome numbers 1, 4, 7, 8 and 9. Antibody response to MCSA was not correlated with antibody titers against the virion proteins, confirming that MCSA was an independent entity. There was no relationship between the segregation of natural killer cell activity and antibody response in a [(A X C57BL) X A] backcross population.

Animals↗
PubMed1992

Genetic variation in Trypanosoma brucei and the epidemiology of sleeping sickness in the Lambwe Valley, Kenya.

A contingency table approach was used to explore the influence of location, host species and time on the genetic composition of a Trypanosoma brucei population in Lambwe Valley, Kenya. Significant differences in zymodeme frequencies were noticed over comparatively short geographical distances suggesting that transmission of T. brucei is somewhat localized. A significant association was observed between zymodeme and the mammalian host from which T. brucei was derived. The association was consistent in different localities in Lambwe valley and remained stable for at least 32 months. These observations indicate that zymodemes are adapted to different host species and that genetic exchange has not disrupted host associations over this time-scale. A major change in the composition of the T. brucei population during a sleeping sickness outbreak in 1980 was confirmed. But while new zymodemes emerged, a decline in overall diversity was noted during times of high sleeping sickness incidence. The results can be explained by selection of T. brucei zymodemes for particular transmission cycles. Although it is not necessary to invoke genetic exchange, sex may help T. brucei to adapt to changes in selection pressures. Such a hypothesis helps to explain why T. brucei appears largely clonal in the short term, even though population studies indicate that sex is responsible for much genetic diversity in the long term. It also explains why neighbouring populations of T. brucei are composed of a different range of zymodemes formed from the same alleles. Such a view implies that genetic exchange has an important role in the microevolution of T. brucei populations.

Animals↗
PubMed2002

Genetic variation in the 22q11 locus and susceptibility to schizophrenia.

An increased prevalence of microdeletions at the 22q11 locus has been reported in samples of patients with schizophrenia. 22q11 microdeletions represent the highest known genetic risk factor for the development of schizophrenia, second only to that of the monozygotic cotwin of an affected individual or the offspring of two schizophrenic parents. It is therefore clear that a schizophrenia susceptibility locus maps to chromosome 22q11. In light of evidence for suggestive linkage for schizophrenia in this region, we hypothesized that, whereas deletions of chromosome 22q11 may account for only a small proportion of schizophrenia cases in the general population (up to approximately 2%), nondeletion variants of individual genes within the 22q11 region may make a larger contribution to susceptibility to schizophrenia in the wider population. By studying a dense collection of markers (average one single nucleotide polymorphism20 kb over 1.5 Mb) in the vicinity of the 22q11 locus, in both family- and population-based samples, we present here results consistent with this assumption. Moreover, our results are consistent with contribution from more than one gene to the strikingly increased disease risk associated with this locus. Finer-scale haplotype mapping has identified two subregions within the 1.5-Mb locus that are likely to harbor candidate schizophrenia susceptibility genes.

Amino Acid Sequence↗