黑麂线粒体基因组序列分析

采用PCR产物直接测序方法测定了黑麂线粒体基因组全序列 ,初步分析了其基因组特点并定位了各基因的位置 .结果显示 :黑麂的线粒体基因组全序列长度为 1 6 35 7bp ,可编码 2 2种tRNA、2种rRNA、1 3种蛋白质 ,碱基组成及基因位置与小麂、赤麂和其它哺乳类动物的线粒体基因组相似 ;模拟电子酶切图谱与先前的报道基本一致 ;基于细胞色素b的全基因序列 ,分别以最大简约法、N J法、最大似然数法与其它 1 4种鹿类动物的相应序列进行了聚类分析 ,构建出相似的系统进化树 :初步确定了麂亚科动物在鹿科中处于与鹿亚科、北美鹿亚科并列的进化地位 .在此基础上 ,进一步以黑麂、赤麂、小麂的线粒体编码RNA和编码蛋白质的基因序列构建系统进化树 ,分析了三者的亲缘关系 .结果表明 :黑麂和赤麂亲缘关系较近 ,是较新的物种 ,而小麂是较为原始的物种     

Detection of nonribosomal peptide synthetase genes in Xylaria sp. BCC1067 and cloning of XyNRPSA

Nonribosomal peptides, synthesized by nonribosomal peptide synthetases (NRPS), are an important group of diverse bioactive fungal metabolites. Xylaria sp. BCC1067, which is known to produce a variety of biologically active metabolites, was studied for gene encoding NRPS by two different PCR-based methods and seven different NRPS fragments were obtained. In addition, screening a genomic library with an amplified NRPS fragment as a probe identified a putative NRPS gene named XyNRPSA. The functionality of XyNRPSA for the production of a corresponding metabolite was probed by gene insertion inactivation. Comparing the disrupting metabolite profile with that of the wild type led to the identification of a speculated metabolite. The crude extract of Xylaria sp. BCC1067 also exhibits antifungal activity against the human pathogens Candida albicans and Trichophyton mentagrophytes. However, the evaluation of biological activity of the XyNRPSA product suggests that it is neither a compound with antifungal activity nor a siderophore. In the vicinity of XyNRPSA, a second gene (named XyPtB) was identified. Its localization and homology to orfB of the ergot alkaloid biosynthetic gene cluster suggests that XyPtB may be involved in XyNRPSA product biosynthesis.     

The evolution of Queensland spiny mountain crayfish of the genus Euastacus. I. Testing vicariance and dispersal with interspecific mitochondrial DNA

The upland mesic rainforests of eastern Australia have been described as a "mesothermal archipelago" where a chain of cool mountain "islands" arise from a warm "sea" of tropical and subtropical lowlands. An endemic freshwater crayfish belonging to the genus Euastacus is found on each of these mountain "islands." The Euastacus are particularly suitable for the study of evolution because each mountain harbors a unique species, there are many taxa present providing replication within the group and, most importantly, their distribution is linear, extending along a south-north axis. This group could have evolved by "simultaneous vicariance" where there was one vicariant separation event of a widespread ancestor, or by "south to north stepping stone dispersal" where there were long distance dispersal events from neighboring mountain islands, starting in the south and proceeding north in a dispersal-colonization wave. We used pairwise genetic distances between nearest geographic neighbors as a novel way to test the two hypotheses. If diversification was due to "south to north stepping stone dispersal," then pairwise genetic distances between nearest geographic neighbors should decrease progressively the farther north the taxon pairs are found, reflecting the decreasing periods of isolation. In this case there should be a negative correlation between the south to north rank order of nearest neighbors and pairwise genetic distances. A Spearman's correlation on 16S mtDNA pairwise genetic distances and geographic rank order was not significant, indicating there was no support for the south to north stepping stone dispersal hypothesis. If simultaneous vicariance was responsible for diversification then all nearest geographic neighbor taxon pairs should have similar genetic distances and, therefore, the variance in nearest neighbor distances should be zero, or close to it. To test if the observed variance was tending towards zero we developed a randomization test where nearest neighbor taxon pairs were assigned random genetic distances and the variances calculated. The observed variance lay in the < 0.05 range of the simulated variances, providing support for the simultaneous vicariance hypothesis. The data also suggest there was simultaneous vicariance of at least two ancestral Queensland lineages. The timing of this vicariant event was probably in the Pliocene, which is consistent with the divergence times reported for other Australian mesic rainforest restricted taxa.     

Novel A14841G mutation is associated with high penetrance of LHON/C4171A family

We report the clinical and genetic characterization of a Chinese LHON family carrying an ND1/C4171A mutation. This family has high penetrance of visual impairment and extremely low frequency of vision recovery, which is in marked contrast to previously reported results for Korean LHON families with the same mutation. Sequence analysis of the complete mtDNA in the partially defined East Asian haplogroup N9a1 revealed the presence of 29 other variants. A novel heteroplasmic A14841G mutation, one of the variants with a serine substituted for a highly conserved asparagine at amino acid 32 of Cytochrome b (Cytb), may play a synergistic role with the C4171A mutation, leading to significantly different clinical manifestations of LHON among these families. The study further confirmed that C4171A was a rare primary LHON mutation, and the mtDNA background could also contribute to the clinical manifestation of the LHON/C4171A mutation.     

草丁膦对转bar基因水稻GS酶活性和光合功能的影响

喷施草丁膦后,对草丁膦无抗性水稻Cypress(未转bar基因)叶片的谷氨酰胺合成酶(GS)活性先受到抑制,随后叶片内NH 4积累上升,叶绿素含量、PSⅡ原初光化学效率(Fv/Fm)、光能转化效率(ΦPSⅡ)和叶片叶绿素荧光的光化学猝灭系数(qp)下降,光合速率显著降低;最后引起植株死亡.另一方面,Cypress PB-6(转bar基因抗草丁膦水稻)的GS酶活性在喷施草丁膦后虽然先被抑制,但随后能恢复至正常水平,接着NH 4积累下降,草丁膦对叶绿素含量、荧光参数Fv/Fm、ΦPSⅡ、qp的影响被解除,光合速率恢复到正常水平,整个植株生长正常.     

Comparison of bacterial and plant genes participating in proline biosynthesis with Osmotin gene, with respect to enhancing salinity tolerance of transgenic tobacco plants

In an attempt to increase tolerance to salinity stress in tobacco plants, the genes encoding the mutant form of glutamyl kinase (proB), pyrroline-5-carboxylate synthetase, and osmotin were cloned into three different shuttle vectors and were separately introduced into the tobacco plants. The transgenic lines were compared for their ability to produce shoots and grow in MS medium containing 320 mM NaCl; it was shown that the transgenic lines containing genetically handled osmotin gene are more resistant to salinity. The amount of chlorophyll a was used to show continuing growth of plant lines. The results showed that only the tobacco lines transformed with the modified osmotin gene exhibited greater tolerance to salinity. Published in Russian in Fiziologiya Rastenii, 2006, Vol. 53, No. 1, pp. 122–127. The text was submitted by the authors in English.     

Diversity and phylogeny of mitochondrial DNA isolated from mithun Bos frontalis located in Bhutan

We sequenced the 16S rRNA gene in mitochondrial DNA to characterize mithun located in Bhutan and to increase our understanding of its origin. We compared mithun with yak, European cattle, Bhutanese zebu and Indian zebu. Sequencing revealed low nucleotide diversity within the mithun population and their phylogenetic proximity to gaur. A close relationship between Bhutanese mithun and gaur was confirmed by an additional comparison with wild gaur specimens from three locations in Bhutan. Direct domestication of mithun from gaur was supported, while maternal contribution from the cattle lineage during domestication was not supported.     

Extensive genetic differentiation in Gobiomorphus breviceps from New Zealand

Partial mitochondrial DNA sequences for parts of the cytochrome b gene and control region were obtained for 89 upland bullies Gobiomorphus breviceps from 19 catchments in New Zealand. There were two highly distinctive mtDNA clades: a northern clade corresponding to the North Island, northern South Island and west coast South Island, and a south‐east clade, in the southern and eastern South Island. Within these major clades there were further distinct clades that correlated with geographic sub‐regions and catchments. The marked genetic differentiation has occurred in the absence of obvious morphological divergence. Based on cytochrome b sequence divergences and the molecular clock hypothesis, the northern and southeastern clades correspond with the uplift of the Southern Alps during the Pliocene, while populations in the North Island and northern South Island were estimated to have diverged during the Pleistocene. The widescale geographic divergences were similar to those observed in the galaxiids, Galaxias vulgaris and Galaxias divergens , but biogeographic management boundaries may not be the same, reflecting different evolutionary histories for non‐diadromous species occupying the same areas.