TECHNICAL ADVANCES: A maximum-likelihood relatedness estimator allowing for negative relatedness values

Previously reported maximum-likelihood pairwise relatedness (r) estimator of Thompson and Milligan (M) was extended to allow for negative r estimates under the regression interpretation of r. This was achieved by establishing the equivalency of the likelihoods used in the kinship program and the likelihoods of Thompson. The new maximum-likelihood (ML) estimator was evaluated by Monte Carlo simulations. It was found that the new ML estimator became unbiased significantly faster compared to the original M estimator when the amount of genotype information was increased. The effects of allele frequency estimation errors on the new and existing relatedness estimators were also considered.     

Catechol-O-methyltransferase: Effects of the val108met polymorphism on protein turnover in human cells

A single nucleotide polymorphism in the human COMT (catechol-O-methyltransferase) gene has been associated with increased risk for breast cancer and several CNS diseases and disorders. The G to A polymorphism causes a valine (val) to methionine (met) substitution at codon 108 soluble - (S)/158 membrane - (MB)-COMT, generating alleles encoding high and low-activity forms of the enzyme, COMT^H and COMT^L, respectively. Tissues and cells with a COMT^LL genotype have decreased COMT activity compared to COMT^HH cells. Previously, we reported that the decreased activity was due to decreased amounts of S-COMT^L protein in human hepatocytes. In this study, we investigated the role of S-COMT protein synthesis and turnover as determinates of reduced COMT protein in COMT^LL compared to COMT^HH cells. No association between S-COMT protein synthesis and COMT genotype was detected. Using a pulse-chase protocol, the half-life of S-COMT^H was determined to be 4.7 days, which was considerably longer than expected from the half-lives of other phase 2 enzyme proteins. The half-life of S-COMT^L compared to S-COMT^H protein was significantly shorter at 3.0 days, but the difference was affected by the medium used during the chase period. These results suggest that increased turnover may contribute to reduced COMT activity in cells and tissues from COMT^LL individuals. Subtle differences appear to be able to affect the stability of the S-COMT^L protein, and this may contribute to the differences observed in epidemiological studies on the association of this polymorphism with breast cancer risk.     

Impact of habitat fragmentation on genetic population structure of roach, Rutilus rutilus, in a riparian ecosystem

During the last 200 years, the riparianecosystem along major rivers has been reducedto a few scattered remnants. Important elementsof the riparian ecosystem are water bodieswhich were originally connected to the mainriver channel by annual floodings. Due to riverregulations many of these remnants are nowvirtually isolated. In an allozyme analysisusing roach, Rutilus rutilus, as a studyspecies we demonstrate that the geneticdiversity (number of alleles per locus,expected heterozygosity) of populations livingwithin floodplain water bodies is not severelyimpoverished compared to the genetic diversitywithin the main river channel. However, wefound slight differences in the allelefrequencies of flood plain water bodies and themain river channel. Nevertheless, fishpopulations in floodplain water bodies mayserve as reservoirs of autochthonous geneticmaterial for restoration of fish populations inthe main river channel after populationextinction due to catastrophic accidents (e.g.industrial pollution).     

Association between Alcohol, Smoking and HLA-DQA1*0201 Genotype in Psoriasis

Psoriasis is a common chronic disease characterizedby erythema and scaling plaques. Although the disease isnot fatal, it detrimentally affects the life-quality of thesufferer, but no effective curative therapy has beenestablished. Up to now, the pathogene…     

Polymorphic microsatellite loci from the red urchin,Strongylocentrotus franciscanus,with comments on heterozygote deficit

Strongylocentrotus sea urchins are common subjects for studies in developmental and cell biology, reproductive biology, ecology, and evolution. We report 14 microsatellite loci from the red urchin, S. franciscanus, isolated for the purpose of estimating paternal success of males in experimental group spawns. Most of these loci were found to be highly polymorphic in a population from British Columbia. A high frequency of null alleles appears responsible for heterozygote deficit at a majority of these loci, but if used with appropriate caution, these microsatellites should be effective markers for studies of Strongylocentrotus populations.     

Microsatellite loci from the northern house mosquito (Culex pipiens), a principal vector of West Nile virus in North America

Microsatellites were isolated and characterized in the northern house mosquito, Culex pipiens, a widespread pest species and important vector of diseases such as West Nile virus. An enrichment protocol yielded 150 positive clones. We designed primers to amplify 17 unique (GT)_n microsatellites, eight of which amplified cleanly and were polymorphic. A survey of 29 individuals showed that these loci are highly variable with the number of alleles ranging from seven to 19 and expected heterozygosity ranging from 0.66 to 0.93. These markers will be useful for studies of population structure and intraspecific variation in epidemiological characteristics of Cx. pipiens.     

鲤科鱼蓝黑鲮微卫星位点的种间扩增(英文)

本研究使用105对微卫星引物对7种鲤科鱼类进行跨越种间PCR扩增,共得到14个多态性微卫星位点.其中9个扩增效果较好的位点用于分析来自帕吉勒提河(Bhagirathi, n=20)和戈达瓦里河(Godavari, n=25)的蓝黑鲮(Labeo calbasu)样品的遗传多样性.结果显示,前者在每个位点的平均等位基因数为7.33,而后者为8 1,期望杂合度介于0.795(Bhagirathi)和0.801(Godavari)之间;4个位点MFW11* (Godavari)、R1*(Godavari)、R3* (Bhagirathi) 和 Lr38*(Bhagirathi和Godavari)都表现出明显的杂合子缺失和哈迪温伯格平衡偏离;而任意两位点间都未观测到连锁不平衡现象;位点R3*极可能存在无效等位基因.上述结果表明这些多态性微卫星位点作为共显性标记在蓝黑鲮群体遗传学研究中有着较好的应用前景.     

Highly polymorphic microsatellite markers developed for the social halictine bee Lasioglossum (Chilalictus) hemichalceum

Lasioglossum ( Chilalictus ) hemichalceum is a social halictine bee species for which we developed 10 polymorphic microsatellite loci in order to investigate detailed genetic structure of cooperating indvididuals. The loci are highly polymorphic with allele numbers ranging between eight and 22. A null allele was detected at one locus in the absence of pedigree information.     

Variable Tandem Repeat VcA of Vibrio cholerae

Computer analysis revealed seven potential variable-number tandem-repeat (VNTR) loci in the Vibrio cholerae genome. Specific primers were designed to amplify locus VcA located on chromosome 2 and containing a TGCTGT repeat. The locus was found in all tested strains from aV. cholerae strain collection, the repeat number varying from 3 to 23. In total, 14 VcA alleles were observed. The VcA locus was proposed as a marker for the molecular typing of V. cholerae strains.     

Biochemical and genetic analysis of variant C of caprine αs2-casein (Capra hircus)

Two alleles, A and B, were previously described at the goat α_s2-casein locus. Isoelectric focusing allowed us to subdivide the former one in two new alleles, called A and C. Although α_s2-casein C cannot actually be distinguished from its A counterpart by starch or polyacrylamide gel electrophoresis, it differs from the previous allele by a single substitution Lys (A)/Ile (C) at position 167, which was confirmed at the nucleotide level. The frequencies of the three α_s2-casein alleles A, B and C were estimated to be 0.85, 0.04 and 0.11 in the French dairy breeds ‘Alpine’ and ‘Saanen’.