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At least 1,117 records · Page 62Linked to original sources
PubMed1998

Dopamine receptor genetic variation, psychosis, and aggression in Alzheimer disease.

OBJECTIVE: To examine if selected polymorphisms in the dopamine receptor genes DRD1, DRD2, DRD3, and DRD4 are associated with the presence of psychosis or aggressive behavior in patients with Alzheimer disease (AD). DESIGN: A cohort of patients with AD were longitudinally evaluated for behavioral symptoms and classified with regard to the presence of psychotic symptoms and physical aggression. SETTING: Alzheimer's Disease Research Center. PATIENTS: Two hundred seventy-five elderly outpatients diagnosed as having probable AD. RESULTS: Among white patients, psychosis and aggression were both significantly more frequent in DRD1 B2/B2 homozygotes (P < .02), while psychosis was significantly more frequent in DRD3 1/1 or 2/2 homozygotes (P < .05). The joint risk for psychosis due to the DRD1 and DRD3 polymorphisms exceeded the risks due to either locus alone, suggesting an interaction. Neither the DRD2 S311C polymorphism nor the presence of long alleles for the DRD4 exon III repeat sequence was associated with psychosis or aggression. CONCLUSIONS: Genetic variation in DRD1 and DRD3 genes may act to modify the course of AD, predisposing to the development of psychotic or aggressive symptoms. Confirmation in other samples of patients with AD is required.

Aged↗
PubMed2002

[Genetic variation and differentiation of peat-bog and dry-meadow populations of the dwarf mountain pine Pinus mugo Turra in the highlands of the Ukrainian Carpathians].

Based on electrophoretic analysis of 21 isozyme loci controlling 10 enzyme systems, the intra- and inter-population variation was studied in two peat-bog and three dry-meadow populations of the dwarf mountain pine Pinus mugo Turra from the highlands of the Ukrainian Carpathians. In the studied samples (a total of 164 trees), on average 62% of the studied genes were polymorphic; the mean heterozygosity was 21.3%. The dry-meadow populations differed from the peat-bog populations by allele and genotype diversity and by heterozygosity although the indices characterizing population heterogeneity (Fst and Gst) were small (0.027 and 0.032, respectively). Nei's genetic distances between the populations ranged of 0.011 to 0.032 with the mean of 0.018.

Genetic Variation↗
PubMed2002

Generating samples under a Wright-Fisher neutral model of genetic variation.

A Monte Carlo computer program is available to generate samples drawn from a population evolving according to a Wright-Fisher neutral model. The program assumes an infinite-sites model of mutation, and allows recombination, gene conversion, symmetric migration among subpopulations, and a variety of demographic histories. The samples produced can be used to investigate the sampling properties of any sample statistic under these neutral models.

Computational Biology↗
PubMed1999

A preliminary examination of genetic variation in a peripheral population of Blanding's turtle, Emydoidea blandingii.

Random amplified polymorphic DNA (RAPD) was used to compare the Nova Scotia population of Blanding's turtle (Emydoidea blandingii) with several populations from the species' main range. The Nova Scotia population is believed to have been isolated from the main range for 4000-8000 years. Cluster analysis using a neighbour-joining algorithm produced a dendrogram showing the Nova Scotia population clustering separately from those populations in the main range. Analysis of molecular variance shows 34.28% of total variance to be accounted for between the Nova Scotia population and populations in the main range. While this study is preliminary, the results suggest that the Nova Scotia population of Blanding's turtle may be important to the maintenance of genetic diversity in the species.

Analysis of Variance↗
PubMed2003

Cloning of and genetic variation in protease VCP1 from the nematophagous fungus Pochonia chlamydosporia.

The fungus Pochonia chlamydosporia is a biocontrol agent with commercial potential for root knot and cyst nematodes. It produces an alkaline serine protease, VCP1, during infection of nematode eggs. The gene encoding VCP1 was sequenced and the sequences of cDNAs from six isolates from different nematode hosts were compared. The gene encoding VCP1 was similar to PR1 from Metarhizium anisopliae with similar regulatory elements. Comparison of translated cDNA sequences revealed two amino acid polymorphisms at positions 65 and 99, indicating a difference between isolates from cyst and root nematodes. The positions and nature of the polymorphisms indicated that the two forms of VCP1 might have different properties and this was tested with five chromogenic polypeptide substrates. Enzyme assays revealed the two forms differed in their abilities to utilise Succ-Ala-Ala-Pro-Phe-pNa and Succ-Ala-Val-Pro-Phe-pNa, suggesting different amino acid affinities at the S3 binding region. This indicates host related genetic variation in VCP1 between isolates of P. chlamydosporia isolated from different nematode hosts, which might contribute to host preference. Such differences may be important in future exploitation of P. chlamydosporia as a nematode biocontrol agent.

Amino Acid Sequence↗
PubMed1998

Genetic variation in captive koalas (Phascolarctos cinereus): parentage determination and individual identification.

Highly repeatable randomly amplified polymorphic DNA (RAPD) markers were developed for parentage studies in the koala (Phascolarctos cinereus). Of the 25 RAPD primers screened, 5 (20.0%) produced 32 repeatable polymorphic RAPD bands (average/primer = 6.4 +/- 4.2). A high level of polymorphism was observed for each group of koalas (Featherdale, 71.9%; Lone Pine, 84.4%). All 25 koalas could be uniquely identified using either RAPD or microsatellite markers. Of the 32 RAPD markers generated in koalas, 25 were informative for parentage analyses. These RAPD markers successfully determined both parents to three offspring and a male parent to a fourth offspring. Paternity analysis (where the female parent is known) succeeded in assigning the correct male parent to seven offspring. Our RAPD-PCR method generates informative genetic markers that are useful for parentage determination and individual identification of captive koalas. This would provide genetic analysis to zoos and wildlife parks as a low-cost alternative to the more expensive microsatellite markers.

Animals↗
PubMed2005

Genetic variation along time in a Brazilian population of Aedes aegypti (Diptera: Culicidae), detected by changes in the esterase patterns.

Aedes aegypti from the Brazilian cities of São José do Rio Preto (SJ) and Goiânia (GO) were analyzed as to their esterase patterns and the results were compared with data obtained about 5 years before for SJ population. Esterase bands not detected in the previous study were now observed in mosquitoes from both SJ and GO populations, being the last considered a population resistant to insecticides. Other similarities between SJ and GO populations in this study, and some differences in comparison with the previous data on SJ were observed, involving, in addition to changes in band type, changes in frequency of mosquitoes expressing them and differential gene activation during development. As it is generally true for genetic features, changes in the esterase patterns are expected to be the result of factors such as selection by environmental conditions and genetic drift. In the present case, continuous use of insecticides aiming mosquito population size control in SJ by sanitary authorities could be involved in the observed changes. Changed esterases were classified as carboxylesterases and cholinesterases, which are enzymes already shown to take part in the development of resistance in several organisms. In addition, data obtained in the elapsed time by authorities responsible for the mosquito control has shown increasing insecticide resistance of SJ population mosquitoes parallel to increase in the total amount of esterases, reinforcing the mentioned possibility.

Aedes↗
PubMed2001

Genetic variation in a Pacific Island land snail: population history versus current drift and selection.

Previous studies of Partula land snails from the Society Islands, French Polynesia, have shown that there can be striking differences in shell shape, colour and banding pattern between nearby populations, even in the absence of any obvious geographical barriers to the movement of snails, or environmental gradients. Elsewhere, there may be relative uniformity over large distances. Analysis of a mitochondrial gene from Partula taeniata (Mörch) shows a similar pattern. The relative frequencies of two mitochondrial haplotypes change abruptly over small distances, seemingly independent of the environment. Although the transition roughly coincides with clines in the frequencies of some morphological characteristics, it appears to be unrelated to others. It is likely that many of the differences accumulated while populations were isolated from one another, through the effects of random genetic drift and selection. Isolation of populations may have occurred as a result of demographic changes, or during the process of colonization if occasional long-distance migrants establish populations ahead of the main invading front. Current genetic drift, even without restrictions to gene flow, may contribute to genetic patchiness on a small scale, although it is likely that conspicuous characteristics such as shell colours and banding patterns are also influenced by selection.

Animals↗
PubMed2001

Microsatellite analysis of genetic variation among and within Alpine marmot populations in the French Alps.

The genetic structure of the Alpine marmot, Marmota marmota, was studied by an analysis of five polymorphic microsatellite loci. Eight locations were sampled in the French Alps, one from Les Ecrins valley (n = 160), another from La Sassière valley (n = 289) and the six others from the Maurienne valley (n = 139). Information on social group structure was available for both Les Ecrins and La Sassière but not for the other samples. The high levels of genetic diversity observed are at odds with the results obtained using microsatellites, minisatellites and allozymes on Alpine marmots from Germany, Austria and Switzerland. Strong deficits in heterozygotes were found in Les Ecrins and La Sassière. They are caused by a Wahlund effect due to the family structure (i.e. differentiation between the family groups). The family groups exhibit excess of heterozygotes rather than deficits. This may be caused by outbreeding and this is compatible with recent results from the genetics of related social species when information on the social structure is taken into account. The observed outbreeding could be the result of females mating with transient males or males coming from neighbouring colonies. Both indicate that the species may not be as monogamous as is usually believed. The results are also compatible with a male-biased dispersal but do not allow us to exclude some female migration. We also found a significant correlation between geographical and genetic distance indicating that isolation by distance could be an issue in marmots. This study is the first that analysed populations of marmots taking into account the social structure within populations and assessing inbreeding at different levels (region, valley, population, and family groups). Our study clearly demonstrated that the sampling strategy and behavioural information can have dramatic effects on both the results and interpretation of the genetic data.

Animals↗
PubMed1999

Disparate phylogeographic patterns of molecular genetic variation in four closely related South American small cat species.

Tissue specimens from four species of Neotropical small cats (Oncifelis geoffroyi, N = 38; O. guigna, N = 6; Leopardus tigrinus, N = 32; Lynchailurus colocolo, N = 22) collected from throughout their distribution were examined for patterns of DNA sequence variation using three mitochondrial genes, 16S rRNA, ATP8, and NADH-5. Patterns between and among O. guigna and O. geoffroyi individuals were assessed further from size variation at 20 microsatellite loci. Phylogenetic analyses using mitochondrial DNA sequences revealed monophyletic clustering of the four species, plus evidence of natural hybridization between L. tigrinus and L. colocolo in areas of range overlap and discrete population subdivisions reflecting geographical isolation. Several commonly accepted subspecies partitions were affirmed for L. colocolo, but not for O. geoffroyi. The lack of geographical substructure in O. geoffroyi was recapitulated with the microsatellite data, as was the monophyletic clustering of O. guigna and O. geoffroyi individuals. L. tigrinus forms two phylogeographic clusters which correspond to L.t. oncilla (from Costa Rica) and L.t. guttula (from Brazil) and which have mitochondrial DNA (mtDNA) genetic distance estimates comparable to interspecific values between other ocelot lineage species. Using feline-specific calibration rates for mitochondrial DNA mutation rates, we estimated that extant lineages of O. guigna diverged 0.4 million years ago (Ma), compared with 1.7 Ma for L. colocolo, 2.0 Ma for O. geoffroyi, and 3.7 Ma for L. tigrinus.

Alleles↗
PubMed1996

Association of genetic variation with interindividual variation in ambulatory blood pressure.

OBJECTIVE: To determine whether genetic and non-genetic components of interindividual variation in systolic and diastolic blood pressure are constant throughout the day or are time or activity dependent. METHODS: We obtained 24 h ambulatory blood pressure recordings in 263 members of 68 unrelated nuclear families (i.e. parents and their offspring) representative of the Caucasian population of Rochester, MN, USA. Using the time each patient got into bed as a reference point, we identified 198 records in which this reference point was preceded by eight consecutive active hours (out of bed) and followed by four consecutive inactive hours (in bed) in which four or more blood pressure readings taken each hour were judged to be technically satisfactory. For each hourly mean for systolic and diastolic blood pressure, we estimated total interindividual variance, variance associated with concomitant variables (generation; sex within generation strata; and age, height, weight, body mass index, and abdomen-to-hip ratio within generation and sex strata), and variance associated with additive genetic effects (i.e. the chief cause of resemblance between relatives). To assess trends in each component of interindividual blood pressure variance over the 12 h period, we estimated the slope of the linear regression line fit to the hourly estimates. RESULTS: For systolic blood pressure, total interindividual variance did not change significantly (slope of regression line = -0.23, P = 0.717). In contrast, total interindividual variance for diastolic blood pressure was greater during active hours than inactive hours (slope of regression line = -5.53, P < 0.001). For both systolic and diastolic blood pressure, variance associated with the concomitant variables was greater during active hours than during inactive hours (for systolic blood pressure slope of regression line = -2.98, P = 0.001; for diastolic blood pressure slope of regression line = -6.14, P < 0.001). Likewise, for both systolic and diastolic blood pressure, variance associated with additive genetic effects was also greater during active hours than during inactive hours (for systolic blood pressure slope of regression line = -1.65, P = 0.090; for diastolic blood pressure slope of regression line = -1.47, P = 0.018). CONCLUSIONS: This study demonstrates that components of interindividual variation in blood pressure are not constant, but are time or activity dependent.

Adolescent↗
PubMed1975

Genetic variation of body temperature of Coturnix coturnix in two ambient temperatures.

Coturnix quail were placed in an environmental chamber maintained at 21 degree C. and rectal temperatures taken. The birds were subjected to an abrupt change to 36 degree C. and the temperatures taken hourly for eight hours and at 25, 38 and 72 hours. Females had higher temperatures than males. When birds were moved to 36 degrees C. their temperatures rose rapidly and then dropped to a level higher than when birds were in the 21 degrees C. chamber. The genetic and total variation estimated from the analysis of variance method decreased under this sudden thermal stress condition. Birds kept in 36 degrees C. for three weeks were shifted to 21 degrees C. Their body temperature dropped sharply and then increased to a level lower than that obtained in the 36 degrees C. environment. The genetic variation was essentially zero when shifted to a lower temperature while the total variation increased.

Animals↗
PubMed1994

Genetic variation of the repeated MAL loci in natural populations of Saccharomyces cerevisiae and Saccharomyces paradoxus.

In Saccharomyces cerevisiae, the gene functions required to ferment the disaccharide maltose are encoded by the MAL loci. Any one of five highly sequence homologous MAL loci identified in various S. cerevisiae strains (called MAL1, 2, 3, 4 and 6) is sufficient to ferment maltose. Each is a complex of three genes encoding maltose permease, maltase and a transcription activator. This family of loci maps to telomere-linked positions on different chromosomes and most natural strains contain more than one MAL locus. A number of naturally occurring, mutant alleles of MAL1 and MAL3 have been characterized which lack one or more of the gene functions encoded by the fully functional MAL loci. Loss of these gene functions appears to have resulted from mutation and/or rearrangement within the locus. Studies to date concentrated on the standard maltose fermenting strains of S. cerevisiae available from the Berkeley Yeast Stock Center collection. In this report we extend our genetic analysis of the MAL loci to a number of maltose fermenting and nonfermenting natural strains of S. cerevisiae and Saccharomyces paradoxus. No new MAL loci were discovered but several new mutant alleles of MAL1 were identified. The evolution of this gene family is discussed.

Alleles↗
PubMed2005

Genetic variation in major histocompatibility complex class I alpha2 gene among broilers divergently selected for high or low early antibody response to Escherichia coli.

The MHC genes have a profound effect on animal abilities to respond to specific antigens because they play a role in presenting foreign antigens to T cells during the course of the humoral or cellular immune response. In the current study, polymorphism in the MHC class I alpha2 domain was compared in 2 lines divergently selected for high (HH) or low (LL) antibody response to Escherichia coli vaccine. These lines also differ markedly in their antibody response to natural E. coli exposure and to vaccination with Newcastle disease virus, infectious bronchitis virus, and infectious bursa disease virus. Recent trials have shown that the LL chicks exhibit a significantly higher percentage of CD8+ T lymphocytes in their peripheral blood lymphocytes and spleen than HH chicks. Despite symmetrical selection intensity in both lines, polymorphism of the alpha2-domain gene was higher in the LL line than in the HH line. Among 29 single-nucleotide polymorphism positions found, 3 were unique to the HH line, 15 were unique to the LL line, and 11 were polymorphic in both lines. These single nucleotide polymorphism positions were not 100% line specific and were in agreement with the genetic variation in antibody level or cellular response still found within the selection lines. Five amino acid positions showed significant differences in polymorphism between the selection lines. These were located within the antigen-binding cleft, suggesting that these positions might influence the ability of MHC class I to bind foreign antigens and leading to differences in immunocompetence between the lines.

Amino Acid Sequence↗
PubMed2005

Genetic variation of 15 STR autosomal loci in the Maracaibo population from Venezuela.

Allele frequencies for 15 short tandem repeats (STRs) autosomal loci (D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, vWA, TPOX, D18S51, D5S818 and FGA, included in the AmpFLSTR Identifiler, Applied Biosystems) were studied in the city of Maracaibo, Venezuela and were compared with other published Latin-American populations for the same loci. Population and forensic parameters were estimated.

DNA Fingerprinting↗
PubMedDate not supplied

Y-chromosome genetic variation in Rio de Janeiro population.

The present-day Brazilian gene pool is known to be the outcome of an admixture process of populations from different origins, mainly Amerindians, Europeans, and Africans. It is also known that in Brazil, a wide variation in the admixture process occurred in different regions of the country or even in different subpopulations from the same region. In the present study, we aimed to characterize the male lineages present in the Rio de Janeiro population, the second most populated of the 26 Brazilian states. A random sample of 127 unrelated males from Rio de Janeiro was typed for 28 Y-chromosome-specific biallelic markers. In total, 17 different haplogroups were defined within our sample, most of them of European ancestry (88.1%). Those of sub-Saharan African origin (E3a) amounted to 7.9%, while only 2 males carried Amerindian lineages (characterized by the presence of an M3 mutation: haplogroup Q3). Using both Y-STR haplotype and Y-SNP haplogroup information, genetic distances were calculated between the subgroup of Rio de Janeiro males carrying European haplogroups and the Portuguese population. Low, nonsignificant, values were obtained. Thus, in contrast with what is observed in their female counterparts, the vast majority of the present Rio de Janeiro male gene pool is of European extraction, while the original Amerindian lineages are residual and much less frequent than the sub-Saharan component resulting from the slave trade. These observations can be interpreted as the signature of the strong gender asymmetry of the admixture processes in colonial systems.

Black People↗