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At least 991 records · Page 55Linked to original sources
PubMed2005

Genetic variation analysis of the Bali street dog using microsatellites.

BACKGROUND: Approximately 800,000 primarily feral dogs live on the small island of Bali. To analyze the genetic diversity in this population, forty samples were collected at random from dogs in the Denpasar, Bali region and tested using 31 polymorphic microsatellites. Australian dingoes and 28 American Kennel Club breeds were compared to the Bali Street Dog (BSD) for allelic diversity, heterozygosities, F-statistics, GST estimates, Nei's DA distance and phylogenetic relationships. RESULTS: The BSD proved to be the most heterogeneous, exhibiting 239 of the 366 total alleles observed across all groups and breeds and had an observed heterozygosity of 0.692. Thirteen private alleles were observed in the BSD with an additional three alleles observed only in the BSD and the Australian dingo. The BSD was related most closely to the Chow Chow with a FST of 0.088 and also with high bootstrap support to the Australian dingo and Akita in the phylogenetic analysis. CONCLUSIONS: This preliminary study into the diversity and relationship of the BSD to other domestic and feral dog populations shows the BSD to be highly heterogeneous and related to populations of East Asian origin. These results indicate that a viable and diverse population of dogs existed on the island of Bali prior to its geographic isolation approximately 12,000 years ago and has been little influenced by domesticated European dogs since that time.

Alleles↗
PubMed2006

[Analysis of genetic variations in different goose breeds using microsatellite markers].

The genetic diversity of six goose breeds (White Goose, Zi Goose, Huoyan Goose, Wanxi Goose, Rhin, Landoise) was analyzed using microsatellite markers. Heterozygosity(H), polymorphism information content (PIC) and genetic distances were calculated for each breed based on the allele frequency. Results showed that 7 microsatellite sites were highly polymorphic, and could be used as effective markers for analysis of genetic relationship among different goose breeds. The mean heterozygosityies of were between 0.6617 (Rhin) and 0.8814 (Zi goose), among six goose breeds, the lowest was Rhin goose (0.6617) and the highest was Zi goose (0.8814). The range of mean PIC was between 0.6145 and 0.7814, which was in the similar range as the mean heterozygosities. Based on the UPGMA cluster analysis results, six goose breeds were grouped into classes, White, Zi, Huoyan and Wanxi Goose in one class, and the foreign breeds of Rhin and Landoise goose in another class. These results indicated that the dendrogram obtain from genetic distance could be used to correctly reflect the phylogenetic relationship among the six goose breeds, suggesting that microsatellite DNA marker is a useful tool to determine the genetic diversity in closely related breeds.

Alleles↗
PubMed1999

Genetic variation within a fragmented population of swietenia humilis zucc

With large tracts of once continuous forest now modified by human use to leave reduced and highly fragmented stands of trees, the determination of the genetic consequences of forest fragmentation is a priority for ascertaining the conservation value of resultant stands, and in formulating sustainable management strategies. The levels and distribution of genetic diversity over 10 microsatellite loci were investigated within a fragmented population of the neotropical tree Swietenia humilis Zucc. High levels of genetic variation, typical of a highly outcrossing species, were found in all fragments at all loci (mean HE = 0.548). The majority of the variation was within rather than between fragments (RST = 0.032), giving high indirect estimates of gene flow (Nm = 8.9), probably reflecting the genetic structure of the trees present under more continuous forest. A high proportion of loci also showed significant departures from Hardy-Weinberg equilibrium with associated significant levels of FIS. The initial effects of fragmentation were, however, seen in the fragments through the loss of low-frequency alleles present in the continuous 'control' stand. The percentage of this allelic loss increased with a decrease in fragment size.

Journal Article↗
PubMed1976

Some physiological aspects of genetic variation in the blood of sheep.

The principal genetic variants in sheep red cells and plasma are listed. Current hypotheses as to how the L blood group antigen affects active potassium transport across the red cell membrane are summarized. Recent work on an inherited defect in amino acid transport which results in a red cell GSH deficiency is also described.

Amino Acids↗
PubMed1996

An analysis of genetic variation in Astragalus cremnophylax var. cremnophylax, a critically endangered plant, using AFLP markers.

A recently developed molecular technique (amplified fragment length polymorphisms, AFLP) was used for characterizing genetic heterogeneity within and among populations of a critically endangered species of plant, Astragalus cremnophylax var. cremnophylax. Using AFLP, up to 50 polymorphic genetic markers per AFLP-PCR amplification were generated, and a total of 220 variable markers overall. This information was used first to assess genetic diversity within each of the three known populations of Astragalus cremnophylax var. cremnophylax from Grand Canyon National Park in Arizona, USA: North Rim (NR; n = 970), South Rim Site 1 (SR1; n = 500), and South Rim Site 2 (SR2; n = 2). Diversity in the form of average heterozygosity [symbol: see text] H [symbol: see text] and the proportion of polymorphic genes [symbol: see text] P [symbol: see text] was greatest in the NR population ([symbol: see text] H [symbol: see text] = 0.13 and [symbol: see text] P [symbol: see text] = 0.38) and least in the SR2 population ([symbol: see text] H [symbol: see text] = 0.02 and [symbol: see text] P [symbol: see text] = 0.04). Diversity was also quite low for the SR1 population ([symbol: see text] H [symbol: see text] = 0.04 and [symbol: see text] P [symbol: see text] = 0.10). In addition, substantial genetic differentiation among populations was indicated by both phenetic (AMOVA) and genetic analyses (overall corrected FST = 0.41). This finding was corroborated by the results of several multivariate analyses which utilized the genetic data, including a UPGMA cluster analysis and a principal coordinate analysis which revealed the existence of discrete groups corresponding to the populations. Population structure was further revealed within the NR population which was known to consist of four spatially separated groups of plants. Several recommendations for the future management of the species are discussed.

Genetic Markers↗
PubMed2005

Genetic variation in XPD, sun exposure, and risk of skin cancer.

The XPD gene is involved in the nucleotide excision repair pathway removing DNA photoproducts induced by UV radiation. Genetic variation in XPD may exert a subtle effect on DNA repair capacity. We assessed the associations between two common nonsynonymous polymorphisms (Asp312Asn and Lys751Gln) with skin cancer risk in a nested case-control study within the Nurses' Health Study (219 melanoma, 286 squamous cell carcinoma, 300 basal cell carcinoma, and 874 controls) along with exploratory analysis on the haplotype structure of the XPD gene. There were inverse associations between the Lys751Gln and Asp312Asn polymorphisms and the risks of melanoma and squamous cell carcinoma. No association was observed between these two polymorphisms and basal cell carcinoma risk. We also observed that the association of the 751Gln allele with melanoma risk was modified by lifetime severe sunburns, cumulative sun exposure with a bathing suit, and constitutional susceptibility score (P for interaction = 0.03, 0.04, and 0.02 respectively). Similar interactions were also observed for the Asp312Asn. Our data suggest these two XPD nonsynonymous polymorphisms may be associated with skin cancer risk, especially for melanoma.

Adult↗
PubMed2006

Patterns of genetic variation in the hypertension candidate gene GRK4: ethnic variation and haplotype structure.

Association studies using single nucleotide polymorphisms (SNPs) have the potential to help unravel the genetic basis of hypertension. Nevertheless, to date, association studies of hypertension have yielded ambiguous results. It is becoming clear that such association studies must be interpreted within the context of the genetic structure of the populations being studied, and patterns of variation within specific genomic regions. With this in mind we analyzed genetic variation in the G protein-coupled receptor kinase 4 (GRK4) gene, a gene whose product has recently been shown to inhibit the dopamine receptor D1 (DRD1) from increasing sodium excretion. We genotyped three previously identified GRK4 SNPs, as well as ten additional SNPs, over 71.6 kb of the GRK4 locus in four populations: African Americans, Asians, Hispanics and Caucasians. Haplotype structure varied among populations, with Hispanics and Caucasians having the most linkage disequilibrium (LD) among SNPs. African Americans had three shorter haplotype blocks, while patterns of markers in the Asian populations demonstrated less LD among markers, a pattern inconsistent with block structure. We observed limited haplotype diversity in each of the four populations, with differing haplotype frequencies among the ethnic groups. We also found substantial evidence for population differentiation, with the largest differences between the African-American and Asian samples with F(ST) values in the upper 90(th) percentile when compared to a genome-wide distribution. However, for all population comparisons, F(ST) values decreased sharply in the 3' region of the gene. This pattern of differentiation among populations is consistent with selection in this part of the gene maintaining similar patterns of variation among otherwise divergent populations. Our results document not only different allele frequencies between populations, but differences in haplotype structure that may be important in evaluating association studies between hypertension and GRK4.

Black or African American↗
PubMed2005

Clinical response to morphine in cancer patients and genetic variation in candidate genes.

Morphine is the analgesic of choice for moderate to severe cancer pain; however, 10-30% of patients do not tolerate morphine. This study evaluated genetic variation in the mu-opioid receptor, betaarrestin2, stat6 and uridine diphosphate-glucuronysltransferase 2B7 (UGT2B7) genes, in patients who responded to morphine vs those who were switched to alternative opioids. We prospectively recruited and genotyped 162 Caucasian patients (117 controls, 39 switchers). Switchers, were more likely to carry the common allele at 1182 G/A, 5864 G/A, 8622T/C and 11143 G/A in the betaarrestin2 gene (P = 0.021, 0.043, 0.013, 0.043, respectively). Switchers had increased carriage of the T allele (-1714 C/T) and a significant difference in the allelic frequency at 9065 C/T (chi(2) = 3.86, P = 0.049) in the stat6 gene. No differences were seen in genotype or allele frequencies of SNPs in the mu-opioid receptor gene or UGT2B7 gene. This study presents novel data suggesting that variation in genes involved in mu-opioid receptor signalling influence clinical response to morphine.

Alleles↗
PubMed2005

Genetic variation and selection response in model breeding populations of Brassica rapa following a diversity bottleneck.

Domestication and breeding share a common feature of population bottlenecks followed by significant genetic gain. To date, no crop models for investigating the evolution of genetic variance, selection response, and population diversity following bottlenecks have been developed. We developed a model artificial selection system in the laboratory using rapid-cycling Brassica rapa. Responses to 10 cycles of recurrent selection for cotyledon size were compared across a broad population founded with 200 individuals, three bottleneck populations initiated with two individuals each, and unselected controls. Additive genetic variance and heritability were significantly larger in the bottleneck populations prior to selection and this corresponded to a heightened response of bottleneck populations during the first three cycles. However, the overall response was ultimately greater and more sustained in the broad population. AFLP marker analyses revealed the pattern and extent of population subdivision were unaffected by a bottleneck even though the diversity retained in a selection population was significantly limited. Rapid gain in genetically more uniform bottlenecked populations, particularly in the short term, may offer an explanation for why domesticators and breeders have realized significant selection progress over relatively short time periods.

Brassica rapa↗
PubMed2005

Phenotypic and genetic variation in emergence and development time of a trimorphic damselfly.

Although colour polymorphisms in adult organisms of many taxa are often adaptive in the context of sexual selection or predation, genetic correlations between colour and other phenotypic traits expressed early in ontogeny could also play an important role in polymorphic systems. We studied phenotypic and genetic variation in development time among female colour morphs in the polymorphic damselfly Ischnura elegans in the field and by raising larvae in a common laboratory environment. In the field, the three different female morphs emerged at different times. Among laboratory-raised families, we found evidence of a significant correlation between maternal morph and larval development time in both sexes. This suggests that the phenotypic correlation between morph and emergence time in the field has a parallel in a genetic correlation between maternal colour and offspring development time. Maternal colour morph frequencies could thus potentially change as correlated responses to selection on larval emergence dates. The similar genetic correlation in male offspring suggests that sex-limitation in this system is incomplete, which may lead to an ontogenetic sexual conflict between selection for early male emergence (protandry) and emergence times associated with maternal morph.

Age Factors↗
PubMed1985

[Vitamin D-binding protein in human plasma. Analysis of genetic variation].

The vitamin-D-binding protein (DBP) also known as group-specific component (GC) is described. This transport protein for vitamin D and its metabolic derivatives has genetic variants which are disclosed by electrophoretic procedures or by isoelectric focusing. Three common and one hundred rare alleles are known. The biochemical, molecular and population genetics are briefly outlined as an example of inherited variability in man.

Chemical Phenomena↗
PubMed1992

Patterns of genetic variation in Native America.

Allele frequencies from seven polymorphic red cell antigen loci (ABO, Rh, MN, S, P, Duffy, and Diego) were examined in 144 Native American populations. Mean genetic distances (Nei's D) and the fixation index FST are approximately equal for the North and South American samples but are reduced in the Central American geographic area. The relationship between genetic distance and geographic distance differs markedly across geographic areas. The correlation between geographic distance and genetic distance for the North and Central American data is twice as large as that observed for the South American samples. This geographic difference is confirmed in spatial autocorrelation analyses; no geographic structure is apparent in the South American data but geographic structure is prominent in North and Central American samples. These results confirm earlier observations regarding differences between North and South American gene frequency patterns.

Blood Group Antigens↗