3种鼢鼠线粒体DNA控制区结构及其系统发育分析

采用PCR 产物直接测序法测定了3种鼢鼠Mospalax spp.18个个体的线粒体控制区(Control region)核苷酸全序列,并进行了结构分析。通过与仓鼠亚科其他啮齿动物的控制区序列进行比较,将鼢鼠的控制区分为终止序列区、中央保守区和保守序列区3个区域。同时识别了鼢鼠中一系列保守序列,并给出了它们的一般形式。选用普通田鼠Microtus rossiaemeridionalis、褐家鼠Rattus norvegicus、小家鼠Mus musculus、鼹鼠Nannospalax ehrenbergi为外类群,采用NJ和UPGMA法构建分子系统发育树。结果显示：鼢鼠中控制区基因适于系统发育分析,根据分子系统学、形态学的结果初步认为高原鼢鼠M.baileyi和甘肃鼢鼠M.cansus达到了种级地位。     

竹类植物与水稻等其它禾本科作物的系统进化关系及基因序列组成的比较

利用8个全长mRNA基因序列比较了竹类植物和水稻等禾本科作物的系统进化和序列组成等.结果表明,在与水稻、玉米和麦类作物的比较中,竹类植物与水稻有着最近的亲缘关系和更相似的基因序列特征(GC含量分布和密码子使用频率),它们甚至比水稻与玉米或水稻与麦类之间的亲缘关系更近.这一结果提示,水稻作为禾本科植物的模式物种,应与竹类植物存在良好的基因组共线性关系,水稻基因组序列信息对竹类植物基因组研究与分析具有重要参考价值.     

南天竹过氧化物酶同工酶的研究

采用聚丙烯酰胺凝胶电泳(PAGE)对湖南南天竹13个种质资源的过氧化物酶(POD)同工酶谱进行了分析。依据不同种质间酶带特征的不同,并利用聚类分析的方法,研究了南天竹种质间的亲源关系及遗传多样性。研究表明,这些种质资源共出现10条酶带,所有种质资源都有3条共同特征的谱带,同时不同种质资源酶谱带数目、迁移率(Rf)、酶活性及分布特征均有不同程度的差异,POD酶谱聚类分析将湖南南天竹13个种质分为3大类。     

4种河蓝蛤线粒体COI和16S rRNA基因序列的种间遗传分析

对光滑河蓝蛤Potamocorbula laevis、黑龙江河蓝蛤P.amurensis、焦河蓝蛤P.ustulata、红肉河蓝蛤P.rubromuscula4个野生种共40个个体的线粒体COI和16SrRNA基因片段进行了扩增和测序,经过筛选和剪切,得到长度为650bp和450bp的片段。序列分析显示,序列的碱基组成中G+C含量较低,16SrRNA基因种间和种内的变异较低,COI基因片段种内和种间的变异较高。以沙海螂Mya arenaria为外群,用MEGA 4.0软件中的NJ法构建了系统进化树,通过遗传距离和系统进化树可以看出,4种河蓝蛤未能达到不同种之间显著的遗传分化。     

辽东湾斑海豹线粒体ND4、tRNAArg、ND4L和ND3基因序列分析

用PCR产物直接测序法,测定渤海辽东湾斑海豹15个个体线粒体的一段从ND3到ND4基因长度为625 bp的DNA序列。其中的1~118 bp是ND3基因的后部分,120~188 bp是tRNAArg基因完整序列,189~485 bp是ND4L基因完整序列,479~625 bp是ND4基因的前部分。在ND4L和ND4之间,有7个碱基是重叠编码的。15个序列间,只有ND4L基因中有一个位点发生C/T碱基转换。与GenBank中的斑海豹序列比较,tRNAArg基因序列完全一致,而ND4L基因序列则有两处发生转换。利用从GenBank中下载的22个海豹科动物的ND4L基因序列的系统发生分析表明,海豹科动物分为南半球和北半球两大类群,斑海豹与港海豹为北半球种类,亲缘关系最近。     

瓶鼻海豚、中华白海豚和糙齿海豚线粒体16SrRNA基因的序列分析

采用聚合酶链式反应(PCR)技术扩增瓶鼻海豚、中华白海豚和糙齿海豚的线粒体DNA16S rRNA基因,获得了大约600bp的片段。扩增产物直接测序,去除引物序列后分别获得515、519和529bp的核苷酸片段。碱基组成平均为T25·8%,C20·7%,A32·1%,G21·4%,GC含量为42·1%。与35种鲸豚类的55条同源序列比对,去除部分端部序列后得到497个比对位点,包括14个插入/缺失位点和127个变异位点(104个简约信息位点,23个单突变子)。序列比较表明,我国水域的瓶鼻海豚和中华白海豚与国外种存在一定的差异。NJ聚类分析结果与目前的主流观点基本相同,即须鲸亚目形成单系群而齿鲸亚目则为多系群,后者包括海豚总科、抹香鲸总科、喙鲸总科和淡水豚总科。其中抹香鲸总科与须鲸亚目聚合在一起,然后与海豚总科聚合再与喙鲸总科相聚。淡水豚总科为一并系群并处于整个鲸豚类的基部,其中恒河豚科是最早分化的一支。但在海豚总科中,鼠海豚科的江豚则与一角鲸科的白鲸聚合一起,与形态分类不同。     

Leaf-inhabiting genera of the Gnomoniaceae,Diaporthales

The Gnomoniaceae are characterised by ascomata that are generally immersed, solitary, without a stroma, or aggregated with a rudimentary stroma, in herbaceous plant material especially in leaves, twigs or stems, but also in bark or wood. The ascomata are black, soft-textured, thin-walled, and pseudoparenchymatous with one or more central or eccentric necks. The asci usually have a distinct apical ring. The Gnomoniaceae includes species having ascospores that are small, mostly less than 25 μm long, although some are longer, and range in septation from non-septate to one-septate, rarely multi-septate. Molecular studies of the Gnomoniaceae suggest that the traditional classification of genera based on characteristics of the ascomata such as position of the neck and ascospores such as septation have resulted in genera that are not monophyletic. In this paper the concepts of the leaf-inhabiting genera in the Gnomoniaceae are reevaluated using multiple genes, specifically nrLSU, translation elongation factor 1-alpha (tef1-α), and RNA polymerase II second largest subunit (rpb2) for 64 isolates. ITS sequences were generated for 322 isolates. Six genera of leaf-inhabiting Gnomoniaceae are defined based on placement of their type species within the multigene phylogeny. The new monotypic genus Ambarignomonia is established for an unusual species, A. petiolorum. A key to 59 species of leaf-inhabiting Gnomoniaceae is presented and 22 species of Gnomoniaceae are described and illustrated.Taxonomic novelties: New genus: Ambarignomonia. New species: Gnomonia incrassata, G. monodii, G. neognomon, G. orcispora, G. pendulorum, G. rodmanii, G. skokomishica, G. virginianae, Gnomoniopsis paraclavulata, Ophiognomonia balsamiferae, O. pseudoclavulata, O. vasiljevae, Plagiostoma barriae. New combinations: Ambarignomonia petiolorum; Apiognomonia hystrix; Gnomonia alnea, G. carpinicola, Gnomoniopsis clavulata, G. comari, G. fructicola, G. macounii, G. racemula, G. tormentillae; Ophiognomonia alni-viridis, O. gei-montani, O. intermedia, O. ischnostyla, O. leptostyla, O. micromegala, O. nana, O. rubi-idaei, O. setacea, O. trientensis; Plagiostoma aesculi, P. amygdalinae, P. robergeanum, and P. salicellum.     

Giardia duodenalis in primates: Classification and host specificity based on phylogenetic analysis of sequence data

Giardia duodenalis colonizes the gastrointestinal tract of a wide range of hosts, including humans and other primates. It is grouped into eight different Assemblages and, beyond that, into a number of sub‐Assemblages, defined ad hoc on the basis of genetic differences; these various groups are often considered to be associated with a specific restricted host range. The aim of this study was to use publicly available genotyping data to investigate the relatedness of human and non‐human primate (NHP) Giardia isolates in order to evaluate the usefulness of current taxonomic classification and to assess whether there is potential for zoonotic transmission between humans and NHP. Our final data set consisted of sequence data from 165 isolates, 111 from NHP and 54 from humans. Assemblages were well defined, but sub‐Assemblages across Assemblage B were not resolved. Although sub‐Assemblages AI and AII were resolved, the terms were not found to capture any useful molecular or host/deme properties. In the phylogenetic tree, NHP isolates were scattered among human isolates across Assemblages A and B, and were even found in Assemblage E. We conclude that there does not appear to be significant molecular distinction between human and NHP Giardia isolates across these four molecular markers. Thus, on the basis of these markers, we cannot exclude a risk for zoonotic and anthropozoonotic transmission of Assemblages A and B isolates, irrespective of sub‐Assemblage classification. We further evaluated the relative merit of the four genes used in genotyping studies. The tpi, gdh and bg genes gave relatively congruent tree topologies, but the SSU gene did not resolve Assemblages according to the current classification. Future genotyping efforts should aim for multilocus or whole‐genome approaches and, in particular, use of the SSU gene as the sole marker should be avoided when possible.     

Cryptic diversity in the common flap-necked chameleon Chamaeleo dilepis in South Africa

The spatial genetic structure of a species, and whether distinct genetic lineages are present, is strongly influenced by their biology and habitat requirements. Given habitat specificity and low vagility, many herpetofaunal species are reservoirs for high levels of cryptic diversity; chameleons are a case in hand. The common flap-necked chameleon Chamaeleo dilepis has a large range that spans much of sub-Saharan Africa. Within South Africa, the species is largely confined to the north-eastern and central areas of the country, and occurs from the coastal forests in southern KwaZulu-Natal westwards into Namibia. Their large range, together with anecdotal evidence that there is considerable morphological and phenotypic diversity across the range, suggests a questionable taxonomy with possible cryptic lineages. The aims of the present study were to investigate whether C. dilepis is genetically structured across parts of its South African range, and whether this species (as it currently stands) might include cryptic lineages. To this end, 72 C. dilepis individuals sampled from four localities across South Africa (Gauteng, n = 2; KwaZulu-Natal, n = 2) were sequenced for two mitochondrial markers (ND4 and 16S). The phylogenetic results suggest that C. dilepis is indeed spatially structured. In addition, the large sequence divergence values between groups strongly suggests the presence of cryptic lineages and, pending the inclusion of more data from a larger geographic range, the group may be in need of a taxonomic revision.     

稻瘟菌Rho族蛋白及其编码基因表达特点

 Rho族蛋白是Ras超家族小G蛋白最主要成员,在真核生物中极为保守,包括Rho、Rac、Cdc42等,作为分子开关,参与细胞极性、细胞运动、细胞形状、细胞间及细胞与其基质互作等多个信号转导途径。基因组数据库分析显示,稻瘟菌中含有30余个小G蛋白,其中7个可能是Rho族蛋白,包括Cdc42、Rac1及5个Rho亚家族蛋白。结构分析表明,7个推导的Rho族蛋白均具有典型结构域。进一步以半定量RT-PCR分析了稻瘟菌7个Rho族蛋白编码基因在菌丝、分生孢子、芽管以及附着胞等不同生长发育阶段的表达情况。结果表明,Rho族蛋白编码基因具有不同的表达模式。通过BLASTP搜索GenBank等数据库,获得迄今已公布的真菌Rho1、Cdc42和Rac1蛋白序列,建立了系统发育树,一定程度地反映了真菌进化关系,说明在真菌进化中Rho族蛋白的结构与功能也经历了共同演化的过程。