Differences In Gene Frequencies Research Articles

Association between human leukocyte antigen DQB1 gene polymorphisms and bronchial asthma among Mongolia and Han nationalities

Objective To investigate association between human leukocyte antigen DQB1 (HLADQB1 ) gene polymorphisms and bronchial asthma among Mongolian and Han nationalities. Methods Sequence-specific primer polymerase chain reaction (PCR-SSP) was used to detect frequencies of HLA DQB1 genotypes and alleles in 50 cases of Han and 68 Mongolian asthmatic patients, and 50 Han and 54 Mongolian healthy controls, respectively. Difference in gene frequencies between the two nationalities was estimated by odds ratio (OR) and chi-square test. Results Frequency of the HLA-DQB1 0602 allele was significantly higher in Han patients with bronchial asthma than that in healthy Han nationality (OR = 6.163,P ＜0.01 ). Frequency of the HLA-DQB1 0603/0608 allele decreased in Mongolian asthmatic patients, as compared to that in healthy Mongolians ( OR = 0.199, P ＜ 0.05 ). Frequency of the HLA-DQB1 0301/4 allele was significantly higher in Mongolian asthmatic patients as compared to that in healthy Mongolians ( OR =2.074,P ＜0.05). Frequency of the HLA-DQB1 0301/4 allele was significantly higher in Mongolian than that in Han asthmatic patients ( OR = 2.482 ,P =0.05). Frequency of the HLA- DQB1 0602 allele was significantly higher in healthy Mongolians than that in healthy Han nationality ( OR = 3.341, P ＜ 0.05 ), in contrast, frequency of the HLA-DQB1 0402 allele was significantly lower in healthy Mongolians than that in healthy Han nationality ( OR = 0.209, P ＜ 0.05 ). Conclusions The HLA-DQB1 0603/0608 allele is possibly a protective gene and the HLA-DQB1 0301/4 allele a susceptible gene for bronchial asthma in Mongolians, and the HLA-DQB1 0602 allele is possibly a susceptible gene for bronchial asthma in Han nationlity. Key words: Asthma; HLA antigens; Mongolian nationality; Han nationality

Endothelial Nitric Oxide Synthase genotypes in the etiology of retinopathy of prematurity in premature infants

Purpose: Retinopathy of Prematurity (ROP) is a vasoproliferative disorder affecting preterm infants leading to visual impairment. ROP is more common in Caucasians than African Americans. Very low birth weight infants have immature retinas and are susceptible to ROP. Because of differences in individual responses to the treatment, various genetic factors have been looked into to understand the etiology of ROP. Endothelial nitric oxide (eNO) serves as a vasodilator, relaxes smooth muscle, prevents platelet aggregation, and facilitates improved blood flow and vascular tonicity. Mutant eNO synthase (eNOS) genotypes result in reduced nitric oxide levels by decreasing enzyme activity. Since eNO affects vasculature and ROP is a vascular disease, the present investigation was aimed at studying the association of genotypes with ROP.Methods: Two eNOS gene single nucleotide polymorphisms (SNPs) (T-786C, and G894T) were studied by microplate-Restriction Fragment Length Polymorphism Polymerase Chain Reaction (RFLP PCR) method. Genotypes were studied in 146 premature infants.Results: The present data showed significant differences in the baseline gene frequencies between Caucasians and African Americans. ROP patients displayed 3-fold higher frequencies of mutant -786C and 894T alleles in both ethnicities compared to respective controls.Conclusions: The present data suggest ethnic stratification of genotypes. Mutant -786C and 894T alleles are significant risk factors in the development of ROP, and suggest a strong association between eNOS polymorphisms and the disease. It is interesting to know if a larger dataset of ROP patients can confirm our initial findings.

GENETIC CHARACTERISTICS AND DISTANCES AMONGST SPANISH AND FRENCH RABBIT POPULATIONS

A total of 990 rabbits were tested using 18 blood electrophoretic markers. These animals belong to 6 breed populations presently breed in Spain (Spanish Common, Spanish Giant, Butterfly, Burgandy Fawn, New Zealand White and Californian), one Spanish cross-breed population, three French crossbreed populations originated from the INRA selected lines (1077, 2066 and 9077) and one Wild Spanish population. 12 markers were found to be polymorphic (Dia-2, 6-Pgd, Es-1, Es-2, Es-3, Es-7, Ada, Hp, Tf, Ca-2 and Hb), each one being controlled by one locus and showing autosomal co-dominant Mendelian inheritance. We have found large differences in gene frequencies of Dia-2, 6-Pgd, Ada, Es- 1, Es-2 and Es-3 loci in French populations. The genetic variabiliy estimated using the average degree of heterozygosity was lower in French than in Spanish populations. The results obtained from genetic distance analysis showed differences between French and Spanish populations. France 3 was the most divergent population. The genetic distance values obtained revealed that French populations are as different amongst themselves as they are between Spanish populations (the value obtained was corresponding to subspecie, NEI, 1987). These differences could have originated from the high selectiva pressure applied to parental lines. In the Spanish group, Spanish Giant was the most divergent population.

An evolutionary approach to the high frequency of the Delta F508 CFTR mutation in European populations

The diffusion of the cattle pastoralism across Europe during the Neolithic period was probably accompanied by the emergence and spread of diverse contagious diseases that were unknown in the Paleolithic and that would have affected the frequency of genes directly or indirectly associated with differential susceptibility and/or resistance to infectious pathogens. We therefore propose that the high frequency of the CFTR gene, and in particular, the common Delta F508 allele mutation in current European and European-derived populations might be a consequence of the impact of selective pressures generated by the transmission of pathogenic agents from domesticated animals, mainly bovine cattle, to the man. Intestinal infectious diseases were probably a major health problem for Neolithic peoples. In such a context, a gene mutation that conferred an increased resistance to the diseases caused by pathogens transmitted by dairy cattle would have constituted a definite selective advantage, particularly in those human groups where cow's milk became an essential component of the diet. This selective advantage would be determined by an increased resistance to Cl(-)-secreting diarrheas of those individuals carrying a single copy of the Delta F508 CFTR mutation (heterozygote resistance). This hypothesis is supported by the strong association between the geography of the diffusion of cattle pastoralism (assessed indirectly by the lactase persistence distribution), the geographic distribution of a sizeable number of HLA alleles (as indicative of potential selective pressures generated by epidemic mortality) and the geographic distribution of the most common mutation causing cystic fibrosis (Delta F508). The systematic interaction of humans with infectious pathogens would have begun in northern Europe, among the carriers of the Funnel Beaker Culture, the first farmers of the North European plain, moving progressively to the south with the dissemination of the cattle pastoralism. This gradual exposure to epidemic mortality among populations located further and further south in Europe as cattle pastoralism expanded could have generated differences in CFTR gene frequencies, thereby shaping the latitudinal frequency gradients observed in present-day European populations.

Human population structure of the Costa Rican Central Provinces. An evaluation through isonymic methods

The human population structure of the Central Provinces of Costa Rica was analyzed through isonymic methods and the use of Electoral Registers (1990 and 2006). Four parameters that define, in a genetic and evolutionary context, this structure were estimated: the consanguinity due to random mating (Morton’s a-priori kinship Fii), the genetic isolation (Fisher’s α), the migration (Karlin-McGregor’s υ), and the degree of subdivision or population differentiation (Fst). The possible geographical distribution of these variables is shown by the use of a Principal Components Analysis (PCA). There is a coincidence between groups of counties obtained by similarity in surname diversity and their geographic location in the territory. Differences were found for the values of the components of consanguinity (F=15.6; p<0.05) and genetic isolation (F=14.38; p<0.05) between different sectors of the Central Provinces. There is an association between population density and the breaking up of genetic isolates and another possible association between the geography of the region, the migration patterns of individuals, and the consequent levels of inbreeding and genetic isolation. The differences in the values of population structure components, inbreeding and genetic isolation, between the different zones of the central region, allow the assumption of the existence of differences in gene frequencies. The migration of blocks of genes from the center to the periphery is also possible and the variation in this sense might be attributed mostly to changes in the components of the population structure: mating patterns, migration and the consequence of the effective population size in the genetic drift process.

Association of hemorrhagic fever with renal syndrome and HLA-DRB allele polymorphisms in Han nationality, Hubei province

To understand the association of human leukocyte antigen (HLA)-DRB polymorphism and patients diagnosed as hemorrhagic fever with renal syndrome (HFRS). HLA-DR allele polymorphism was detected by PCR-sequence specific primers (PCR-SSP). Hantavirus (HV) typed as Hantaan virus (HTNV) and Seoul virus (SEOV) in patients were detected by RT-heminested PCR. The gene frequency of DRB1*0401-0411, *1001 and *1101-1105 in HFRS case group were 3.1%, 2.2% and 15.7% respectively. Compared with control group, it was significant higher in HFRS case group (RR = 13.87, 9.72 and 2.00 respectively with Chi-square value as 10.006, 6.324 and 6.472 respectively, P < 0.05). When compared with HFRS case group, the gene frequency of DRB1*1501-1502, DRB4 and DRB5 in control group were 11.0%, 19.0% and 16.9% respectively, markedly lower than in patients (RR = 0.45, 0.58 and 0.23 respectively. Chi-square values were 6.138, 4.583 and 21.076 respectively, P < 0.05). There was no significant difference in other HLA-DR gene frequencies. Mixed infection was found in Hubei, with HTNV slightly more than SEOV. Distinct hantaviruses could coexist in either different or the same geographic or ecological zores in Hubei province. Patients with HLA-DRB1*1101-1105 alleles were 81.8% (27/33) infected by HTNV and only 18.2% infected by SEOV, which had significant difference (P < 0.05). DRB1*0401-0411, *1001 and *1101-1105 were possibly associated with increased susceptibility to HV infection. On the other hand there was an inverse correlation among HFRS, DRB1*1501-1502, DRB4 and DRB5.

Population studies in Northern Sweden. II. Red cell enzyme polymorphism in the Swedish Lapps.

Five polymorphic red cell enzyme systems (phosphoglucomutase, adenylate kinase, acid phosphatase, 6-phosphogluconate dehydrogenase and adenosine deaminase) were studied in a series of Swedish nomad Lapps. No departures from the Hardy-Weinberg equilibria were found. Adenylate kinase was probably not polymorphic in the original Lappish population. In all five systems significant gene frequency differences from non-Lappish Scandinavian populations were found, which further stresses the genetic uniqueness of the Lapps. In four enzyme systems significant differences were found between Lappish groups. It is unlikely that the unique genetic composition of the Lapps is due to natural selection in an arctic environment. The accumulated genetic information on the Lapps suggests that founder effect and genetic drift are to a large extent responsible for the peculiar gene pool of the original Lappish population.

High genetic homogeneity of the moon jelly Aurelia aurita (Scyphozoa, Semaeostomeae) along the Mediterranean coast of Tunisia

The moon jelly Aurelia aurita is one of the most common and widespread species of scyphomedusa in the Mediterranean Sea. In all, 18 allozyme loci were studied to investigate the genetic variation and population structure of 11 A. aurita populations from the Tunisian coast. Polymorphism was detected at 14 loci across the sampling localities. Gene frequency differences rather than alternative fixation of alleles characterised the collecting sites. The mean number of alleles per locus ranged from 1.89 to 2.17 (average 2.02), and the mean values of observed (H o) and expected (H e) heterozygosities ranged from 0.20 to 0.36 and from 0.32 to 0.37 respectively. Five out of 14 polymorphic loci were out of Hardy-Weinberg equilibrium (H-WE). Likewise, the multilocus tests showed deviation from H-WE in six populations. These populations apparently showed heterozygote deficiency, whereas the average heterozygosity for the remaining ones is quite similar to the expected values. Despite extensive sampling across a microgeographical scale and genotyping efforts, the populations of A. aurita under study showed an absence of genetic differentiation under the background of high gene flow (mean F ST = 0.01, p < 0.05) and higher value of N e m, suggesting that A. aurita is genetically homogeneous throughout the study area. The absence of population genetic structuring may be associated with environmental conditions and life-history parameters.

In silico prioritisation of candidate genes for prokaryotic gene function discovery: an application of phylogenetic profiles

BackgroundIn silico candidate gene prioritisation (CGP) aids the discovery of gene functions by ranking genes according to an objective relevance score. While several CGP methods have been described for identifying human disease genes, corresponding methods for prokaryotic gene function discovery are lacking. Here we present two prokaryotic CGP methods, based on phylogenetic profiles, to assist with this task.ResultsUsing gene occurrence patterns in sample genomes, we developed two CGP methods (statistical and inductive CGP) to assist with the discovery of bacterial gene functions. Statistical CGP exploits the differences in gene frequency against phenotypic groups, while inductive CGP applies supervised machine learning to identify gene occurrence pattern across genomes. Three rediscovery experiments were designed to evaluate the CGP frameworks. The first experiment attempted to rediscover peptidoglycan genes with 417 published genome sequences. Both CGP methods achieved best areas under receiver operating characteristic curve (AUC) of 0.911 in Escherichia coli K-12 (EC-K12) and 0.978 Streptococcus agalactiae 2603 (SA-2603) genomes, with an average improvement in precision of >3.2-fold and a maximum of >27-fold using statistical CGP. A median AUC of >0.95 could still be achieved with as few as 10 genome examples in each group of genome examples in the rediscovery of the peptidoglycan metabolism genes. In the second experiment, a maximum of 109-fold improvement in precision was achieved in the rediscovery of anaerobic fermentation genes in EC-K12. The last experiment attempted to rediscover genes from 31 metabolic pathways in SA-2603, where 14 pathways achieved AUC >0.9 and 28 pathways achieved AUC >0.8 with the best inductive CGP algorithms.ConclusionOur results demonstrate that the two CGP methods can assist with the study of functionally uncategorised genomic regions and discovery of bacterial gene-function relationships. Our rediscovery experiments also provide a set of standard tasks against which future methods may be compared.

The snails the dinosaurs saw: are the pleurocerid populations of the Older Appalachians a relict of the Paleozoic Era?

AbstractPleurocerid snails are a common element of the benthos in rivers and streams throughout the Appalachian highlands from Virginia to Georgia on both sides of the continental divide. Yet their dispersal capabilities are so limited today that significant gene frequency differences have been demonstrated over a scale of meters. We obtained mitochondrial cytochrome oxidase c subunit I (COI) sequence data from 3 individual snails sampled from each of 13 populations of pleurocerids representing 3 species—Leptoxis carinata (4 populations), Goniobasis (“Elimia”) catenaria (4 populations), and Goniobasis (“Elimia”) proxima (5 populations). To these data we added previously published COI sequences from 3 other G. proxima populations. Levels of intrapopulation sequence divergence were strikingly high, ranging up to 21.9% within populations and 22.6% between populations within species. A neighbor-joining analysis revealed 3 loose clusters corresponding to the species, but featured numerous extreme outliers. Wil...

Polymorphism at two esterase loci in Drosophila melanogaster from northern Greece

Polymorphism at the Est-6 and Est-C loci was studied in three different populations of Drosophila melanogaster from northern Greece. In the Est-6 system no significant differences were found between the populations from Greece, while there were distinct differences between the populations from Greece and those from most other parts of the world. In the Est-C system there were significant gene-frequency differences between the Greek Drosophila populations. The possibility was discussed that variable use of organophosphoric insecticides in the three populations might have had a selective effect on the Est-C polymorphism.

Relationship between single nucleotide polymorphisms in −174G/C and −634C/G promoter region of interleukin-6 and prostate cancer

The association between the single nucleotide polymorphisms (SNPs) in -174G/C and -634C/G of interleukin-6 (IL-6) promoter region and prostate cancer was examined in the population of Han people in Hubei region. TaqMan PCR was employed for the gene-typing of -174G/C and -634C/G in promoter region of IL-6 gene to compare the prostate cancer patients and normal controls in terms of genotype frequency, allele frequency and risk of prostate cancer. Enzyme-linked immunosorbent assay (ELISA) was used for the detection of IL-6 concentration in peripheral blood of the patients with prostate cancer and the relationship between the IL-6 level and the genotype was studied. Our results showed that in all the subjects, the genotype of genetic locus -174G/C was found to be GG and no CG and CC were observed. There was a significant difference in gene frequency of GG, CG and CC of -634C/G and allele frequency of G and C between prostate cancer patients and normal controls (P<0.05) and the gene frequency of GG+CG increased with the clinical stages and pathological grades of prostate cancer. The IL-6 level in GG+CG group was significantly higher than that in CC group. It was concluded that no SNP in -174G/C IL-6 promoter region was found in the population of Han people in Hubei region. The SNP in -634C/G was, to some extent, associated with the development and progression of prostate cancer. The population with GG+CG genetype has higher risk for prostate cancer.

Alpha and beta globin polymorphism in Italian islander sheep breeds

Previous investigations have highlighted the elevated haemoglobin polymorphism of Apulian native sheep. Thanks to the use of highly resolving analytical procedures (PAGIF, AUT-PAGE and RP-HPLC), the alpha globin genetic system (HBA) has been shown to exhibit both qualitative and quantitative variations (HBA1L, HBA1A, HBA1D, HBA2L, HBA2H, HBA3L, HBA3H, and HBA4H), while three allelic variants have been detected at the beta globin locus (HBBA, HBBB, and HBBI). The effect of a possibly adaptive response to the Apulian environmental conditions was suggested to account for both for the unusual presence of alpha haplotypes characterized by extra-numerary genes and the high frequency of the HBBB and HBBI alleles. Unfortunately, the few data in the literature regarding the HBA system polymorphism and the presence of the HBBI gene do not allow a comparison between Apulian sheep and those from other geographical areas. This work reports the results of a screening of Italian islander sheep breeds with a view to expanding the existing data set. A total of 465 blood samples were taken from 156 Comisana (C), 159 Sardinian (S) and 150 Valle del Belice (VdB) sheep belonging to 13 different flocks located in Apulia. Haemolysates were prepared from EDTA samples and analyzed by PAGIF, AUT-PAGE and RP-HPLC. Based on our results, the islander breeds exhibited slight differences in the HBA2H gene frequency compared to the HBA system of the Apulian native sheep; the most interesting finding was that though no HBA1D genes were recorded, the frequencies of triplicated haplotypes were very close, which supports the hypothesis that extra-numerary genes in Mediterranean environments may be an adaptive response to endemic tick borne parasites. Regarding the HBB locus, the results indicated that both Sicilian breeds exhibit an HBBI allele frequency of about 0.2, which is more than double that of previously reported data; this finding provided confirmatory evidence that HBBI is a rather common allele in Southern Italian sheep breed and suggested that an appropriate next step should be to investigate whether it presents the same frequency latitudinal cline as HBBB gene.

Genome-wide SNP typing reveals signatures of population history

Single-nucleotide polymorphism (SNP) arrays have become a popular technology for disease-association studies, but they also have potential for studying the genetic differentiation of human populations. Application of the Affymetrix GeneChip Human Mapping 500K Array Set to a population of 102 individuals representing the major ethnic groups in the United States (African, Asian, European, and Hispanic) revealed patterns of gene diversity and genetic distance that reflected population history. We analyzed allelic frequencies at 388,654 autosomal SNP sites that showed some variation in our study population and 10% or fewer missing values. Despite the small size (23–31 individuals) of each subpopulation, there were no fixed differences at any site between any two subpopulations. As expected from the African origin of modern humans, greater gene diversity was seen in Africans than in either Asians or Europeans, and the genetic distance between the Asian and the European populations was significantly lower than that between either of these two populations and Africans. Principal components analysis applied to a correlation matrix among individuals was able to separate completely the major continental groups of humans (Africans, Asians, and Europeans), while Hispanics overlapped all three of these groups. Genes containing two or more markers with extraordinarily high genetic distance between subpopulations were identified as candidate genes for health differences between subpopulations. The results show that, even with modest sample sizes, genome-wide SNP genotyping technologies have great promise for capturing signatures of gene frequency difference between human subpopulations, with applications in areas as diverse as forensics and the study of ethnic health disparities.

Detection of genetic diversity in rough fescue (Festuca campestris Rydb) populations of southern Alberta and British Columbia, Canada, using RAPD markers

Mountain rough fescue (Festuca campestris Rydb.) is a tufted native grass in southern Alberta and British Columbia, Canada, and has attracted interest for use in reclamation. However, its seed is often available from only a few localized sources and may not be adapted for areas removed from the collection site. We conducted a study to determine the genetic variability among rough fescue populations to assess its potential adaptation. Thirty plants were collected from each of six populations and analyzed using Random Amplified Polymorphic DNA (RAPD). One population (Kamloops, BC) was separated by several mountain ranges from the five easterly Alberta populations.The Kamloops population was also separated from the Alberta populations by genetic distance in two clusters. Of the total genetic variation present in the data, 21% was found among populations while the remaining (79%) was found within populations. Nei’s genetic distances among populations were related to their geographical distances. Genetic differences among populations appeared to be caused primarily by differences in gene frequencies rather than rare genes. Also, genetic diversity appeared to increase from west to east suggesting that the more easterly populations had greater adaptation potential. We speculate that the more easterly populations are less likely to share genes since the prevailing winds are from the west. Germplasm from the more easterly populations may be used with suitable precautions within Alberta and possibly around Kamloops. Key words: Genetic distance, geographic distance, reclamation, potential adaptation

Comparison of the rapidly evolving KIR locus in Parsis and natives of India

The extreme variability at the Killer cell Immunoglobulin-like Receptor (KIR) locus along with that of the genes encoding their ligands, HLA class I, appears to modulate risk for viral, autoimmune, and malignant diseases, and reproductive failure. Differences in KIR gene and haplotype frequencies across world populations may reflect some combination of ancestral genotypes, locale-specific selection pressures, and genetic drift. We genotyped unrelated healthy Parsis and Maharashtrian Hindus, neighboring peoples from Western India. These two populations showed remarkable similarity in KIR gene frequencies despite their distinct ethnic background and the fairly recent migration of Parsis to Western India from Persia around 900 A.D: . One clear exception is KIR3DS1, which is found at a significantly higher frequency in the Parsis than in the Maharashtrians, previously characterized North Indians, and most other world populations. The high KIR3DS1 frequency of Parsis corresponds with a low frequency of its putative HLA-B ligand group, an inverse correlation that has been observed previously across other world populations. Thus, KIR3DS1 frequency in Parsis may be a remnant of their distinct ancestral Persian origin. KIR gene frequencies and profiles of the Parsis and Maharashtrians were more similar to one another than they were to North Indians, suggesting a potential effect of local environmental factors on KIR evolution and/or some degree of admixture between Parsis and populations from Western India. Overall, these data support other studies indicating the rapid evolution of the KIR locus and the apparent dependency of this evolution on the loci encoding HLA class I ligands.

Vascular endothelial growth factor 936 C/T polymorphism is associated with vascular invasion in oral squamous cell carcinoma

The objective of this study was to analyze the relation of VEGF 936 C/T polymorphisms in progression of oral squamous cell carcinoma (OSCC) patients and healthy subjects in Taiwan. We genotyped 218 patients with OSCC, comparing the genotypes and gene frequencies with those of 121 control subjects. VEGF 936 C/T polymorphisms were determined by using polymerase chain reaction and restriction fragment length polymorphism. There were no significant differences in genotype, phenotype, or gene frequency between the OSCC and control groups. Among patients with OSCC, there were also no significant differences in the polymorphism between those with and without cervical lymph node metastases or in survival. However, 21 of the 218 patients had vascular invasion by their OSCC, and these patients were significantly more likely to have a C/C (P = .033) or C/T genotype (P = .026) than were those without vascular invasion. This study suggests that the VEGF 936 C allele is associated with vascular invasion in OSCC.

Genetic variation among white croaker populations

To investigate the genetic structures and differentiation of different wild populations of white croaker (Pennahia argentata), horizontal starch gel electrophoresis was performed on 133 individuals collected from five different locations in China and Japan. The eleven enzyme systems revealed 15 loci, of which eleven were polymorphic. The percentage of polymorphic loci of white croaker populations varied from 6.67% to 53.33%; the mean observed and expected heterozygosity ranged from 0.0033 to 0.0133 and 0.0032 to 0.0191, respectively. The expected heterozygosity revealed a low genetic variability for white croaker in comparison with other marine fishes. The genetic distances between populations ranged from 0.00005 to 0.00026. A weak differentiation was observed within each clade and between clades; and no significant differences in gene frequencies among populations were observed in white croaker. Among the five populations, three Chinese populations showed more genetic diversity than that in Japanese populations.

Allelic Differences in the Brain-Derived Neurotrophic Factor Val66Met Polymorphism in Late-Life Depression

The Val66Met polymorphism of the brain-derived neurotrophic factor gene is associated with cognitive and neuroimaging changes. The authors examined the relationship between this polymorphism and depression in an elderly sample, hypothesizing that the Met66 allele would be associated with late-life depression. A total of 245 elderly depressed white subjects and 94 elderly comparison white subjects completed clinical assessments and provided a blood sample for genotyping. Subjects were dichotomized as either homozygous for the Val66 allele or Met66 allele carriers. Gene frequencies were compared between groups, with separate analyses examining for differences in gene frequencies based on age of depression onset, family history, and depression history. Logistic regression models examined the relationship between genotype and depression after controlling for age, sex, and race. Depressed subjects were more likely to be Met66 allele carriers than were comparison subjects (38.8% versus 24.4%; chi(2) = 6.13, 1 df, p = 0.0133). This relationship remained significant after controlling for covariates (Wald chi(2) = 5.10, 1 df, p = 0.024; odds ratio: 1.92, 95% confidence interval: 1.09-3.38). There were no significant relationships between genotype and age of onset, number of episodes, or family history of depression. Met66 allele carriers have almost double the odds of having geriatric depression than do Val66 allele homozygotes. This polymorphism was unrelated to other clinical characteristics of depression in later life.

Genetic variation and differentiation in populations of Japanese emperor oak Quercus dentata Thunb. and Mongolian oak Quercus mongolica Fisch. ex Ledeb.) in the south of the Russian Far East

Allozyme variation of Japanese emperor oak Quercus dentata Thunb. and Mongolian oak Quercus mongolica Fisch. ex Lebed.) was examined in 11 populations of these species from southern Primorye. Analysis of 18 loci showed that in these populations, 66.7% of genes of Mongolian oak are polymorphic, the number of alleles per locus being 2.28. In Japanese emperor oak, these parameters were respectively 59.8 and 2.36%. The observed heterozygosity in both species did not differ from the expected values, constituting 0.198 in Japanese emperor oak and 0.161 in Maongolian oak. The Nei's distance between Quercus mongolica and Q. dentate was 0.053. The Japanese emperor oak and Mongolian oak populations formed separate clusters in an UPGMA dendrogram. Taking into account morphological and ecological isolation of the species, we suggest that the differences in gene frequencies may reflect selection acting in favor of adaptation to different growth conditions and counteracting between-species hybridization.