水稻叶绿体的petG-trnP片段的测定和系统学分析*

本研究主要对水稻的叶绿体petG-trnP片段进行PCR直接测序和系统学分析。结果表明,水稻的petG-trnP的序列长度十分保守,其间隔区全长为316bp,扣除trnW序列后的非编码区长为242bp,其中两段非编码区分别为116bp和126bp。非编码区中G+C含量在37.19%-38.02%之间。对五种水稻材料进行ClustalW等分析表明,它们的序列结构有所变异,共有7个变异位点,比例为2.89%,这预示着水稻的petG-trnP的非编码区中有着一定的系统学信息,可在分子水平上为稻属的系统关系提供一定的证据。     

Genetic characterization of the Golovinomyces cichoracearum complex in Australia

To characterize the evolutionary lineages of the Golovinomyces cichoracearum complex on introduced plants in Australia, the rDNA ITS regions from 47 herbarium specimens were compared by RFLPs and sequencing. Six RFLP groups were found, each corresponding to a previously reported evolutionary lineage in the complex. The largest of these groups (Group 1) contained 15 specimens infecting a range of tribes in the Asteraceae, despite a previous report that this lineage is largely restricted to the Tribe Heliantheae (Asteraceae). This group contained the only specimens with ascomata. Curved foot cells were formed by two lineages; one (Groups 5 & 6) containing specimens from a range of host families including the Asteraceae (Tribe Lactucae only), the other (Groups 2 & 3) containing members of the Asteraceae (Tribe Anthemidae only). Group 5 may represent G. orontii sensu stricto , while Group 6 is currently unnamed. Golovinomyces cichoracearum sensu stricto (specimens from Scorzonera ) formed a distinct group that did not contain any specimens from Australia. Suggestions are made for future species delimitation in the complex.     

长江下游4属6种鳞科鱼类线粒体16S rDNA部分序列的比较分析

采用PCR扩增获得了长江下游鲿科(Bagridae)4个属6个种类的线粒体16S rDNA序列片段。序列长度介于920 bp与933 bp之间,A+T含量明显高于C+G含量。共有939个比对位点,其中190个为变异位点;52个为简约信息位点。以大鳞脂鲤(Chalceus macrolepidotus)为外群,采用邻接法(NJ)和最大简约法(MP)分析鲿科4属6种鱼类的系统发生关系。结果表明,16S rDNA序列可以作为鲿科属间系统发育分析的有效分子标记。聚类结果显示,鲿科鱼类构成一个单系类群,其中鳠属(Mystus)较特化,黄颡鱼属(Pelteobagrus)次之,而拟鲿属(Pseud-obagrus)与鮠属(Leiocassis)的亲缘关系最近。     

微卫星技术在绵羊品种级进杂交育种中的应用

分析了10个微卫星基因座10个微卫星标记在7个绵羊群体（德美♂×当地羊♀级进杂交一代、级进杂交二代、级进杂交三代、德克赛尔、道赛特羊、德国美利奴羊、当地羊）205只绵羊中的遗传多态性。结果表明,这10个微卫星标记在7个绵羊群体中的等位基因数分别为12、22、26、23、14、21、29、17、24和14,由多态信息含量／有效等位基因数／杂合度可知其中AGLA269的遗传变异最大,BMS1714最小。基于Nei氏距离和共祖遗传距离,采用UPGMA方法构建了系统发生树。该发生树将德美×当地羊级进杂交一代、二代、三代和德国美利奴羊归为一类后又与当地羊聚为一大类,将德克赛尔、道赛特羊归为另一类。绵羊微卫星基因分型技术为检查品种（群体）之间的遗传关系提供了一个有用的工具。     

A monograph of the entomopathogenic genera Hypocrella,Moelleriella, and Samuelsia gen. nov. (Ascomycota,Hypocreales, Clavicipitaceae), and their aschersonia-like anamorphs in the Neotropics

The present taxonomic revision deals with Neotropical species of three entomopathogenic genera that were once included in Hypocrella s. l.: Hypocrella s. str. (anamorph Aschersonia), Moelleriella (anamorph aschersonia-like), and Samuelsia gen. nov (anamorph aschersonia-like). Species of Hypocrella, Moelleriella, and Samuelsia are pathogens of scale insects (Coccidae and Lecaniidae, Homoptera) and whiteflies (Aleyrodidae, Homoptera) and are common in tropical regions. Phylogenetic analyses of DNA sequences from nuclear ribosomal large subunit (28S), translation elongation factor 1-α (TEF 1-α), and RNA polymerase II subunit 1 (RPB1) and analyses of multiple morphological characters demonstrate that the three segregated genera can be distinguished by the disarticulation of the ascospores and shape and size of conidia. Moelleriella has filiform multi-septate ascospores that disarticulate at the septa within the ascus and aschersonia-like anamorphs with fusoid conidia. Hypocrella s. str. has filiform to long-fusiform ascospores that do not disarticulate and Aschersonia s. str. anamorphs with fusoid conidia. The new genus proposed here, Samuelsia, has filiform to long-fusiform ascospores that do not disarticulate and aschersonia-like anamorphs with small allantoid conidia. In addition, the present study presents and discusses the evolution of species, morphology, and ecology in Hypocrella, Moelleriella, and Samuelsia based on multigene phylogenetic analyses.Taxonomic novelties: New genus: Samuelsia. New species: Hypocrella disciformis, H. hirsuta, Moelleriella basicystis, M. boliviensis, M. cornuta, M. evansii, M. madidiensis, M. umbospora, S. chalalensis, S. geonomis, S. intermedia, S. rufobrunnea, and S. sheikhii. New combinations: M. castanea, M. colliculosa, M. disjuncta, M. epiphylla, M. gaertneriana, M. globosa, M. guaranitica, M. javanica, M. libera, M. macrostroma, M. ochracea, M. palmae, M. phyllogena, M. rhombispora, M. sloaneae, M. turbinata, and M. zhongdongii.     

温州光唇鱼线粒体基因组结构及系统发育分析

采用已公布的鱼类线粒体基因组全序列,设计8对引物扩增、测定并注释温州光唇鱼(Acrossocheilus wenchowensis)线粒体基因组(GenBank登录号:KC_495074)。序列全长16 591 bp,包括13个蛋白质基因、22个tRNA基因、2个rRNA基因和1个非编码区,各基因的位置及组成与已公布的鲤科鱼类一致;37个基因中,1个蛋白质编码基因(ND6)和8个tRNA基因(tRNAGln、tRNAAla、tRNAAsn、tRNACys、tRNATyr、tRNASer(UCN)、tRNAGlu和tRNAPro)由L链编码,其余的均由H链编码。A、T、G、C碱基组成分别为30.92%、24.86%、16.41%、27.81%;除tRNASer(AGN)外,其它21个tRNA的二级结构均具有典型的三叶草结构;13个蛋白编码基因中,除COⅠ起始密码子为GTG外,其余均以ATG为起始密码子,而COⅡ、ND4和Cytb基因的终止密码子为不完整的T,其它10个基因均具有完整的终止密码子。利用鲤科共17属18种线粒体基因组13个蛋白质基因的氨基酸序列,从线粒体基因组水平探讨了温州光唇鱼在鲤科鱼类中的系统进化地位,为光唇鱼属乃至鲤科鱼类的系统分类学研究提供基础资料。     

Identification of <Emphasis Type="Italic">Globodera rostochiensis</Emphasis> and <Emphasis Type="Italic">G. pallida</Emphasis> in the Ukraine by PCR

Multiplex polymerase chain reaction was used to identify the potato cyst nematodes in soil samples from the Ukraine. The results show the occurrence of Globodera pallida in the Uzhhorod region (Zakarpatska oblast), where only G. rostochiensis had been previously reported. In the mixed potato cyst nematode (PCN) populations, G. pallida was less prevalent (2–5%) than G. rostochiensis (95–98%). A phylogenetic analysis based on ribosomal DNA internal transcribed spacer sequences showed that the Ukrainian population of G. pallida had >99% sequence identity with other G. pallida pa2/3 isolates from Europe. This study has demonstrated that polymerase chain reaction-mediated amplification of specific regions of the potato cyst nematode genome is not only highly effective as a species diagnostic tool but is also a sensitive method which can be used for taxonomic purposes with cyst collections which vary in age.     

Comparative analysis of pathogenic and nonpathogenic Fusarium oxysporum populations associated with banana on a farm in Minas Gerais,Brazil

Fusarium wilt is one of the most devastating diseases on banana. The causal agent, Fusarium oxysporum f. sp. cubense (Foc) is genetically diverse and its origin and virulence are poorly understood. In this study, pathogenic Foc isolates and nonpathogenic F. oxysporum isolates from Minas Gerais in Brazil were compared using EF‐1α and IGS sequences. This allowed the examination of the origin and evolutionary potential of Foc in a country outside the region of origin of the banana plant. Two different sequence types were found among Foc isolates. One appeared to be of local origin because it was identical to the sequence type of the largest group of nonpathogenic isolates. To explore if the ‘local’ Foc isolates had acquired pathogenicity either independently through coevolution with the host, or through horizontal gene transfer (HGT) of pathogenicity genes from other, probably introduced, Foc isolates, the presence and sequence of putative SIX effector genes were analysed. Homologues of SIX1, SIX3 and SIX8 were found. SIX1 sequences were identical and exclusively found in all pathogenic isolates, while variable ratios of sequences of multicopy gene SIX8 were found among nonpathogenic and different pathogenic isolates. This observation supports the HGT hypothesis. Horizontal transfer of genes between isolates of F. oxysporum has important implications for the development of reliable diagnostic tools and effective control measures. Full genome sequencing is required to confirm HGT and to further unravel the virulence mechanisms of forma specialis cubense.     

从流行毒株的系统发生看中国目前狂犬病流行的主要特征

以2006～2012年本实验室狂犬病病毒分离株核蛋白基因完整核苷酸序列和GenBank收录的主要数据为基础,通过构建系统发生树和比对病毒分离株相互间的同源性,对中国狂犬病流行特征进行分析.结果显示,目前涉及中国17个狂犬病主要流行省区的62个狂犬病病毒代表流行株,均为基因Ⅰ型,但在系统发生树上可分为i、ii、iii、iv、v共5个基因群,群内同源性91.4％～99.9％,群间同源性84.5％～90.1％.其中,i、ii群占国内新分离株的绝大多数,为2个主要流行基因群.i群遍布各主要流行省区,主要为来源于犬的分离株.ii群主要分布于南方省区,迄今分离到的多个鼬獾狂犬病病毒株在系统发生上也属于ii群.iii群仅见于广西壮族自治区、云南省两地,与东南亚国家狂犬病分离株同源性高达97.7％.iv群的地区分布不规律,在中国东北、中原、东南和西部地区均有零星报道,分离株较少.v群近年来仅偶见于内蒙东北部及黑龙江省与俄接壤地区,与俄罗斯远东及韩国流行株同源性高达98.5％.综上,中国狂犬病流行以犬间传播为主,野生动物狂犬病的流行日益严重,东北和西南地区存在境外狂犬病传入.犬等动物种群免疫覆盖率低应是狂犬病持续传播的主因.     

基于全基因组编码区序列的烟草花叶病毒分子进化分析

为揭示烟草花叶病毒分子进化特征,从GenBank中下载已报道的烟草花叶病毒全基因组编码区序列,进行重组、系统发育、遗传变异、种群结构和基因漂流等分析。结果表明:突变和负选择作用是驱动烟草花叶病毒进化的主要作用力,种群结构稳定,处于扩张趋势中,基因变异程度低,重组在烟草花叶病毒分子进化中作用不明显。烟草花叶病毒不同分离物形成3个有一定地理相关性的种群ChinaⅠ、ChinaⅡ和Europe。欧洲分离物核苷酸序列多样性比中国的差异大,Europe和ChinaⅠ种群可能受到遗传漂变影响,Europe与ChinaⅡ、ChinaⅠ与ChinaⅡ之间存在发生基因交流的渠道。