多酚氧化酶基因NtPPOE差异表达的效应分析

为研究烟草中多酚氧化酶基因的功能,本研究从GenBank中挑选一个烟草多酚氧化酶基因Polyphenol oxidase E(基因登录号:NW_015916967.1),命名为NtPPOE。构建NtPPOE基因的CRISPR载体和超表达载体,分别得到NtPPOE基因抑制/过量表达的转化植株。研究表明,基因敲除植株NtPPOE基因相对表达量降低,PPO活性降低,多酚类物质含量升高;超表达植株NtPPOE基因相对表达量升高,PPO活性升高,多酚类物质含量降低。NtPPOE基因表达量与PPO酶活性呈正相关,与多酚类物质含量呈极显著性负相关,NtPPOE基因的表达影响了烟草多酚代谢。本研究通过分析NtPPOE基因差异表达产生的效应,初步验证了NtPPOE基因的功能,并得到了NtPPOE基因抑制/过量表达的突变植株,为PPO基因功能研究和不同PPO活性品种的育种提供材料基础。     

Repetitive DNA Sequences in Wheat and Its Relatives

Repetitive DNA sequences form a large portion of eukaryote genomes. Using wheat ( Triticum )as a model, the classification, features and functions of repetitive DNA sequences in the Tritieeae grass tribe is reviewed as well as the role of these sequences in genome differentiation, control and regulation of homologous chromosome synapsis and pairing. Transposable elements, as an important portion of dispersed repetitives,may play an essential role in gene mutation of the host. Dynamic models for change of copy number and sequences of the repetitive family are also presented after the models of Charlesworth et al. Application of repetitive DNA sequences in the study of evolution, chromosome fingerprinting and marker assisted gene transfer and breeding are described by taking wheat as an example.     

Characterization of donor genome contents of backcross progenies detected by SSR markers in rice

Backcrossing is a trait introgression method of renewed importance in crops. The evolution of introgressed or substituted segments through backcross generations has been analyzed theoretically using simulations. In this study, the content of donor genomes, including donor segment number (DSN), donor segment length (DSL), and donor genome size (DGS), were directly analyzed in six crosses over three successive backcrosses using a set of single sequence repeat (SSR) markers covering the entire rice genome. The results of this analysis demonstrated that the average DSN in each genome was 8.39 in BC₂F₁, 4.13 in BC₃F₁, and 2.41 in BC₄F₁, decreasing nearly by half with each backcrossing. The average DSL was 33.43 cM (centiMorgans) in BC₂F₁, 29.04 cM in BC₃F₁, and 25.07 cM in BC₄F₁, display a progressive decrease slightly greater than 10% in each additional backcross generation. Meanwhile the average DGS was 280.51 cM in BC₂F₁, 119.97 cM in BC₃F₁, and 60.53 cM in BC₄F₁, decreasing 57.2% from BC₂F₁ to BC₃F₁ and 50.4% from BC₃F₁ to BC₄F₁. This revealed that the reduction in DGS was approximately 50% with each backcrossing. These results provide a guide for introgression or substitution of target chromosome segments from donors into recipients in backcross programs. Zhang-Ying Xi and Feng-Hua He contributed equally to this work.     

根瘤菌基因组内简单重复序列的分析

【目的】分析根瘤菌基因组中的简单重复序列（simple sequence repeats,SSRs）,为其在根瘤菌遗传多样性研究中的应用提供有益的信息。【方法】利用公共的微生物串联重复序列数据库资源,对已测序的3种根瘤菌基因组中SSRs的结构类型、分布、丰度等进行系统的比较分析。【结果】大豆慢生根瘤菌（Bradyrhizobium japonicum）、百脉根根瘤菌（Mesorhizobium loti）和苜蓿中华根瘤菌（Sinorhizobium meliloti）基因组中的SSRs分别为1 410个、859个和638个,3种根瘤菌基因组中长重复的四、五、六核苷酸基序更为丰富,变异性更高。数目最少的为单碱基重复。【结论】3种根瘤菌的SSR在结构类型和分布规律上均具有一定的相似性。     

基于全长cDNA序列的小麦cSNP发掘

以测序得到的来自小麦不同基因组的基因序列为源序列,用AutoSNP软件,在GenBank中的小麦EST库中检测到一批cSNP,开辟了一条发掘小麦基因组特异候选cSNP的新途径。在2089个源序列中,检测到1 296个cSNP,其中有397个来自A基因组,322个来自S基因组,420个来自D基因组;另外,A和D基因组共有的SNP有154个,A和S,S和D,A、S和D基因组共有的SNP各仅有1个,这一结果也同时表明,小麦的3个基因组供体种中,A、D基因组关系比较近,而它们与S基因组的关系比较远。统计分析表明,小麦中SNP出现的频率约为0.914‰。     

糜子分子遗传研究进展与展望

糜子是最古老的驯化栽培作物之一,具有抗旱、耐瘠、水分利用效率高、营养丰富等特点,在北方旱作农业区特色粮食生产中占有重要地位。为深入推动糜子农艺、产量及品质相关性状遗传解析,在介绍国内糜子遗传研究现状基础上,通过文献分析综述了糜子分子遗传研究进展,并展望了未来发展趋势。     

一株猪高致病性蓝耳病病毒的分离鉴定与遗传变异分析

为研究猪蓝耳病病毒(PRRSV)的遗传进化规律,于2018年从新疆某猪场采集的病猪血液中分离了一株PRRSV,命名为XJ-b。对临床样品采用RT-PCR扩增鉴定,将阳性样品过滤处理之后接种在Marc-145细胞系进行培养,将盲传3代之后出现病变(CPE)的Marc-145样品进行间接免疫荧光鉴定。通过噬斑纯化后,利用RT-PCR对分离株的全基因组进行扩增,使用SeqMan软件对测序结果进行拼接,并根据NCBI上已公布的PRRSV全基因组及Nsp2基因核苷酸序列进行遗传进化与同源性比对分析。结果表明,临床病料RT-PCR检测呈PRRSV核酸阳性,处理后的病料接种至Marc-145细胞72 h之后产生CPE,间接免疫荧光鉴定为PRRSV抗原阳性;序列拼接显示分离株全基因组开放阅读框大小为15119 bp;全基因组和Nsp2基因核苷酸序列分析和同源性比对显示该分离毒株属于中国的高致病性PRRSV亚群。研究结果可为近年来新疆地区PRRSV的毒株差异分析提供参考。     

食用真菌线粒体基因组的研究进展

本文综述了近年来国内外对食用真菌线粒体DNA(mt DNA)大小、形态及结构的研究,对线粒体基因组遗传及同源性的分析及对线粒体中类质粒 DNA 的探讨结果。并评价了这些研究结果的意义及应用前景。     

Analysis of pathogenic biology of SARS-associated coronavirus and its implication

Severe acute respiratory syndrome (SARS) is the first new epidemic of the twenty-first century. A novel coronavirus (SARS-CoV) has been identified as the causative agent of SARS. The genome of SARS-CoV has 29 727 nucleatides in length. The genome organization, with 11 open reading frames, is similar to that of coronaviruses. Phylogenetic analyses and sequence comparisons showed that SARS-CoV is not closely related to any of the known coronaviruses, indicating neither a mutant nor recombinant of wel-characterized coronaviruses. It is a complete new coronavirus from nonhuman host. Pathological studies show that severe immune response, associated to cytokine dysregulation, may be related to the lung damage of fatal SRAS. Recombination of genomes of wild-type strains with vaccine coronavirus is a potential risk associated with the application of living attenuated coronavirus vaccines. The proteinases, controlling the activities of the SARS-CoV replication, and spike protein, involved in viral entry and pathogenesis, represent at ractive targets of anti-SARS drug development. Comparative full-length genome sequence analysis of 14 SARS coronavirus isolates suggests a remarkable genetic conservation of the virus. Anti-SARS vaccine and drug development wil benefit from this genet ic conservation.SARS-CoV is not likely to change rapidly and thus may not readily mutate to a benign infection. The progress in anti-SARS research has been impressive. However, one of the most effective tools in the control of the SARS is quickly tracing and isolating the contacts of stricken patients before they spread the virus further.     

Analyzing clinical characteristic of miR-196b in human colorectal cancer using TCGA and effect of miR-196b on 5-FU resistance of CRC cell line

AIM: To investigate the clinical characteristics of microRNA (miR)-196b in colorectal cancer (CRC) and to study its biological function in 5-fluorouracil (5-FU) resistance. METHODS: miRNA sequence dataset and the corresponding clinical data of CRC patients were downloaded from The Cancer Genome Atlas (TCGA). Expression level and clinical characteristics of miR-196b in CRC patients were analyzed using SPSS 17.0. CRC cell line overexpres-sing miR-196b was established using transient transfection method. MTS test was used to evaluate the effect of miR-196b overexpression on 5-FU resistance. RESULTS: miR-196b expression was associated with lymph node metastasis and TNM stage (P<0.05), but not related with age and sex. Lymph node metastasis and distant metastasis were independent prognostic factors for rectal patients (P<0.05). The expression level of miR-196b was not associated with survival condition of rectal patients. The viability of the cells overexpressing miR-196b treated with different concentrations of 5-FU was significantly higher than that in control group (P<0.05). CONCLUSION: miR-196b may be a potential biomarker of TNM stage and lymph node metastasis in CRC. miR-196b increases the 5-FU resistance of CRC cells.