Genetic analysis of IREB2, FAM13A and XRCC5 variants in Chinese Han patients with chronic obstructive pulmonary disease

Recently, variants (rs2568494, rs2869967 and rs3821104) in the IREB2, FAM13A and XRCC5 genes were found to be associated with chronic obstructive pulmonary disease (COPD) in non-Asian populations by genome-wide association study (GWAS) analysis. To evaluate whether variants in these genes are related to COPD in Chinese Han population, we investigated COPD patients of Chinese Han ethnicity from Mainland China. Significant differences in genotypic distributions (χ² = 6.319, p = 0.042 for rs2869967; χ² = 6.062, p = 0.048 for rs3821104) and allele distributions (χ² = 4.014, p = 0.045 for rs2869967; χ² = 5.607, p = 0.018 for rs3821104) were observed between patients and control subjects for variants rs2869967 and rs3821104, whereas no statistically significant associations for genotypic and allelic distribution between IREB2 rs2568494 and COPD phenotype (p > 0.05) were identified. Our results support that FAM13A rs2869967 and XRCC5 rs3821104 are associated with COPD in Chinese Han population.     

A parallel coiled-coil tetramer with offset helices

Specific helix-helix interactions are fundamental in assembling the native state of proteins and in protein-protein interfaces. Coiled coils afford a unique model system for elucidating principles of molecular recognition between alpha helices. The coiled-coil fold is specified by a characteristic seven amino acid repeat containing hydrophobic residues at the first (a) and fourth (d) positions. Nonpolar side chains spaced three and four residues apart are referred to as the 3-4 hydrophobic repeat. The presence of apolar amino acids at the e or g positions (corresponding to a 3-3-1 hydrophobic repeat) can provide new possibilities for close-packing of alpha-helices that includes examples such as the lac repressor tetramerization domain. Here we demonstrate that an unprecedented coiled-coil interface results from replacement of three charged residues at the e positions in the dimeric GCN4 leucine zipper by nonpolar valine side chains. Equilibrium circular dichroism and analytical ultracentrifugation studies indicate that the valine-containing mutant forms a discrete alpha-helical tetramer with a significantly higher stability than the parent leucine-zipper molecule. The 1.35 A resolution crystal structure of the tetramer reveals a parallel four-stranded coiled coil with a three-residue interhelical offset. The local packing geometry of the three hydrophobic positions in the tetramer conformation is completely different from that seen in classical tetrameric structures yet bears resemblance to that in three-stranded coiled coils. These studies demonstrate that distinct van der Waals interactions beyond the a and d side chains can generate a diverse set of helix-helix interfaces and three-dimensional supercoil structures.     

Enzymatic condensation of dopamine and acetaldehyde: a salsolinol synthase from rat brain

Salsolinol (1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline; Sal) is structurally similar to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, which is supposed to have a role in the development of Parkinson-like syndrome in both human and non-human subjects. In the human brain, the amount of (R)-enantiomer of Sal is much higher than (S)-enantiomer, suggesting that a putative enzyme may participate in the synthesis of (R)-salsolinol, called (R)-salsolinol synthase. In this study, the (R)-salsolinol synthase activity in the condensation of dopamine and acetaldehyde was investigated in the crude extracts from the brains of Sprague Dawley rats. Identification of the enzymatic reaction products and enzyme activity detection were achieved by HPLC-electrochemical detection. The discovery of this enzyme activity in rat’s brain indicates the natural existence of (R)-salsolinol synthase in the brains of humans and rats, and it is distributed in most brain regions of rat with higher activity in soluble proteins extracted from striatum and substantia nigra.     

Overexpression of a new rice vacuolar antiporter regulating protein OsARP improves salt tolerance in tobacco

We examined the function of the rice (Oryza sativa L.) antiporter-regulating protein OsARP by overexpressing it in tobacco (Nicotiana tabacum L.). In public databases, this protein was annotated as a putative Os02g0465900 protein of rice. The OsARP gene was introduced into tobacco under the control of the cauliflower mosaic virus 35S promoter. The transformants were selected for their ability to grow on medium containing kanamycin. Incorporation of the transgene in the genome of tobacco was confirmed by PCR, and its expression was confirmed by Western blot analysis. Transgenic plants had better growth and vigor than non-transgenic plants under salt stress in vitro. Overexpression of OsARP in transgenic tobacco plants resulted in salt tolerance, and the plants had a higher rate of photosynthesis and effective PSII photon yield when compared with the wild type. The OsARP protein was localized in the tonoplast of rice plants. Transgenic plants accumulated more Na+ in their leaf tissue than did wild-type plants. It is conceivable that the toxic effect of Na+ in the cytosol might be reduced by sequestration into vacuoles. The rate of water loss was higher in the wild type than in transgenic plants under salt stress. Increased vacuolar solute accumulation and water retention could confer salt tolerance in transgenic plants. Tonoplast vesicles isolated from OsARP transgenic plants showed Na+/H+ exchange rates 3-fold higher than those of wild-type plants. These results suggest that OsARP on the tonoplasts plays an important role in compartmentation of Na+ into vacuoles. We suggest that OsARP is a new type of protein participating in Na+ uptake in vacuoles.     

Cloning, sequence analysis and identification of a nonsense mutation-mediated mRNA decay of porcine GSTM2 gene

The glutathione S-transferase mu 2 gene （GSTM2） encodes a GST functioning in the elimination of electrophilic compounds and the regulation of cell growth. In this study, the sequence of porcine GSTM2 gene that contains the complete sequence encoding a protein of 218 amino acids was cloned. The deduced amino acid sequence shared 76%, 78% and 76% identity with that of human, mouse and rat, respectively, mRNA expression analysis showed that the porcine GSTM2 gene was expressed at a high level in liver and testis, at a medium level in longissimus dorsi muscle, adipose tissue, spleen and lung, at a low level in kidney, and at a very low level in heart and embryo. A nonsense mutation （CGA→TGA） resulted from C27T substitution in the fifth exon to produce a premature translation termination codon was identified, and it was discovered that nonsense-mediated mRNA decay might have an effect on the regulation of porcine GSTM2 gene expression. This polymorphism was analyzed in Large White, Landrace, Meishan and Qingping pig populations using the Taq I-polymerase chain reaction-restriction fragment length polymorphism method. The result showed that allele C had a higher frequency than allele T in each population.     

A change from phalanx to guerrilla growth form is an effective strategy to acclimate to sedimentation in a wetland sedge species Carex brevicuspis (Cyperaceae)

The rhizomatous sedge Carex brevicuspis can produce clumping ramets from shortened rhizomes (phalanx) and spreading ramets from elongated rhizomes (guerrilla) to form a combined clonal growth form. In this paper, changes in clonal growth and biomass allocation pattern of C. brevicuspis in response to sedimentation were studied. Four sedimentation depths (0, 3, 6, and 9 cm) were applied to 48 ramets in a randomized block design. Plants were harvested after 20 weeks. With increasing sedimentation depth, the proportion of spreading ramets to total ramets increased from 19.6% in 0 cm to 92.9% in 9 cm sedimentation treatments, whereas that of clumping ramets decreased from 80.4% to 7.1%, indicating a change of clonal growth form from phalanx to guerrilla as a response to sedimentation. With increasing sedimentation depth, biomass allocation to shoots and roots did not change, but rhizome mass ratio increased from 2.7% in 0 cm to 7.2% in 9 cm sedimentation treatments, suggesting that production of long rhizomes changes biomass allocation pattern. The results show that plasticity of clonal growth forms, by which more spreading ramets are produced, is an effective strategy to avoid sedimentation stress under our experimental conditions.     

巴东过路黄中三萜皂苷及其体外抗肿瘤活性研究

从巴东过路黄(Lysimachia patungensis)95%乙醇提取物的正丁醇萃取部位中,分离到2个齐墩果烷型三萜皂苷,经光谱鉴定,分别为ardicrenin(1)和ardisiacrispinA(2)。体外抗肿瘤实验显示ardicrenin(1)对人脑胶质瘤(SWO-38)、口腔上皮癌(KB)、人乳腺癌(MCF-7)和人宫颈癌(Hela)细胞的半数毒性浓度(TC50)分别为3.16、3.16、2.97、2.42μmol/L,ArdisiacrispinA(2)对上述细胞的TC50分别为3.96、3.01、1.98、2.73μmol/L。