Lack of genetic association between the angiotensin-converting enzyme gene insertion/deletion polymorphism and longevity in a Han Chinese population

Introduction. The insertion/deletion polymorphism of the angiotensin-converting enzyme (ACE) gene has been reported to associate with human longevity. However, little information is available in a Han Chinese longevity Population. Therefore, we investigat

Evidence of gene conversion in the evolutionary process of the codon 41/42 (-CTTT) mutation causing beta-thalassemia in southern China

The 4-bp deletion (-CTTT) at codon 41/42 (CD41/42) of the human beta-globin gene represents one of the most common beta-thalassemia mutations in East Asia and Southeast Asia, which is historically afflicted with endemic malaria, thus hypothetically evolvi

Prion protein gene (PRNP) polymorphisms in native Chinese cattle

Le polymorphisme au sein de quatre regions du gene codant pour la proteine prion bovine (PRNP) confere la susceptibilite a l'encephalopathie bovine spongiforme (BSE). Ceux-ci comprennent un polymorphisme d'insertion/deletion (indel) de 23 pb dans le promoteur, un indel de 12 pb dans l'intron 1, un octapeptide repete ou un indel de 24 pb au sein du cadre de lecture, et un polymorphisme mononucleotidique (SNP) dans la region codante. Dans ce travail, les auteurs ont examine la frequence des genotypes, des alleles et des haplotypes pour ces indel au sein de 349 bovins d'origine chinoise, de meme que la sequence nucleotidique de ce gene chez 50 de ces animaux. Leurs resultats montrent que l'allele ayant la deletion de 12 pb et l'haplotype combinant la deletion de 23 pb et la deletion de 12 pb, lesquels ont ete suggeres comme etant importants pour la susceptibilite a la BSE, sont rares au sein des bovins du sud de la Chine. Une difference significative a ete observee entre les bovins affectes par la BSE et les bovins chinois sains pour ce qui est de l'indel de 12 pb. Au total, 14 SNP ont ete observes dans la region codante du gene PRNP chez les bovins chinois. Trois de ces SNP etaient associes a des changements d'acides amines (K3T, P54S et S154N). La substitution E211K qui a ete rapportee recemment chez un cas atypique de la BSE chez un bovin americain n'a pas ete detectee dans ce travail.

Deletion of yeast CWP genes enhances cell permeability to genotoxic agents

We have previously reported the development of a novel genotoxic testing system based on the transcriptional response of the yeast RNR3-lacZ reporter gene to DNA damage. This system appears to be more sensitive than other similar tests in microorganisms, and is comparable with the Ames test. In an effort to further enhance detection sensitivity, we examined the effects of altering major cell wall components on cell permeability and subsequent RNR3-lacZ sensitivity to genotoxic agents. Although inactivation of single CWP genes encoding cell wall mannoproteins had little effect, the simultaneous inactivation of both CWP1 and CWP2 had profound effects on the cell wall structure and permeability. Consequently, the RNR3-lacZ detection sensitivity is markedly enhanced, especially to high molecular weight compounds such as 4-nitroquinoline-N-oxide (> sevenfold) and phleomycin (> 13-fold). In contrast, deletion of genes encoding representative membrane components or membrane transporters had minor effects on cell permeability. We conclude that the yeast cell wall mannoproteins constitute the major barrier to environmental genotoxic agents and that their removal will significantly enhance the sensitivity of RNR-lacZ as well as other yeast-based genotoxic tests.

Phylogenetic relationships of the Chinese sisorid catfishes: a nuclear intron versus mitochondrial gene approach

Several recent molecular phylogenetic studies of the sisorid catfishes (Sisoridae) have challenged some aspects of their traditional taxonomy and cladistic hypotheses of their phylogeny. However, disagreement with respect to relationships within this family in these studies highlights the need for additional data and analyses. Here we subjected 15 taxa representing 12 sisorids genera to comprehensive phylogenetic analyses using the second intron of low-copy nuclear S7 ribosomal protein (rpS7) gene and the mitochondrial 16S rRNA gene segments both individually and in combination. The competing sisorid topologies were then tested by using the approximately unbiased (AU) test and the Shimodaira-Hasegawa (SH) test. Our results support previously suggested polyphyly of Pareuchiloglanis. The genus Pseudecheneis is likely to be nested in the glyptosternoids and Glaridoglanis might be basal to the tribe Glyptosternini. However, justified by AU and SH test, the sister-group relationship between Pseudecheneis and the monophyletic glyptosternoids cannot be rejected based on the second intron of rpS7 gene and combined data analyses. It follows that both gene segments are not suitable for resolving the phylogenetic relationships within the sisorid catfishes. Overall, the second intron of rpS7 gene yielded poor phylogenetic performance when compared to 16S rRNA gene, the evolutionary hypothesis of which virtually agreed with the combined data analyses tree. This phenomenon can be explained by the insufficient length and fast saturation of substitutions in the second intron of rpS7 gene, due to substitution patterns such as frequent indels (insertion/deletion events) of bases in the sequences during the evolution.

Chromosomal localization and molecular marker development of the lipopolysaccharide and beta-1,3-glucan binding protein gene in the Zhikong scallop Chlamys farreri (Jones et Preston) (Pectinoida, Pectinidae)

Zhikong scallop Chlamys farreri(Jones et Preston) is an economically important species in China. Understanding its immune system would be of great help in controlling diseases. In the present study, an important immunity-related gene, the Lipopolysaccharide and Beta-1,3-glucan Binding Protein (LGBP) gene, was located on C. farreri chromosomes by mapping several lgbp-containing BAC clones through fluorescence in situ hybridization (FISH). Through the localization of various BAC clones, it was shown that only one locus of this gene existed in the genome of C. farreri, and that this was located on the long arm of a pair of homologous chromosomes. Molecular markers, consisting of eight single nucleotide polymorphism (SNPs) markers and one insertion-deletion (indel), were developed from the LGBP gene. Indel marker testing in an F1 family revealed slightly distorted segregation (p = 0.0472). These markers can be used to map the LGBP gene to the linkage map and assign the linkage group to the corresponding chromosome. Segregation distortion of the indel marker indicated genes with deleterious alleles might exist in the surrounding region of the LGBP gene.

The polymorphism of lysozyme gene in Zhikong scallop (Chlamys farreri) and its association with susceptibility/resistance to Listonella anguillarum

Lysozyme functions as a crucial biodefence effector against the infection of bacterial pathogens in innate immunity. The nucleotide sequence polymorphisms in promoter region of a nuclear goose type lysozyme gene from Zhikong scallop Chlamys farreri (designated as CFLysG) were investigated to explore their association with susceptibility/resistance to Listonella anguillarum infection. Eight sites of single nucleotide polymorphisms (SNPs) and two sites of insert-deletion (ins-del) polymorphisms were identified in the promoter region of CFLysG. Two of them, -753 TATCTCGATCAGG ins-del polymorphism and -391 A-G SNP were selected to analyze their distribution in the susceptible and resistant stocks, which were identified according to the survival time after L. anguillarum challenge. Using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), two genotypes were found at each site, which were ins/del and ins/ins at locus -753, and A/A and A/G at locus -391, respectively. The -753 ins/del genotype was more prevalent in the resistant stock than that in the susceptible stock, 30% vs 16.67% in frequency, but there was no significant difference in the frequency distribution between these two stocks (P=0.15). In contrast, the frequency of -391A/G genotype in the resistant stock was significantly higher (30%) than that in the susceptible stock (7.14%) (P=0.007), indicating a significant association with the resistance of Zhikong scallop to L anguillarum. To confirm the presumption, another independent challenge experiment was performed, in which the cumulative mortality of scallops with -391 A/A genotype (96.8%) was significantly higher than those with -391 A/G genotype (64.5%) (P=0.001), which further validate the association between -391 A/G genotype and the resistance of Zhikong scallop to L anguillarum. These results suggested that the -391 A/G could be a potential marker applied in future selection of Zhikong scallop with enhanced resistance to L anguillarum. (C) 2008 Elsevier Ltd. All rights reserved.