The genetic diversity of SMLS (Sitobion miscanthi L type symbiont) and its effect on the fitness,mitochondrial DNA diversity and Buchnera aphidicola dynamic of wheat aphid,Sitobion miscanthi (Hemiptera: Aphididae)

SMLS (Sitobion miscanthi L type symbiont) is a recently discovered aphid secondary symbiont. Using evidence extracted from 16S rRNA sequences, previous studies indicate that SMLS is the most widely distributed and most recently transferred secondary symbiont in Chinese Sitobion miscanthi populations. Here, we further investigated genetic diversity among SMLS geographic strains with multiloci data. Furthermore, the influence of SMLS on S. miscanthi was uncovered with ecological and evolutionary evidence. The results indicated that there was limited influence of infection with SMLS on variation and evolutionary patterns of S. miscanthi mitochondrial DNA. By hemolymph injection, the SMLS‐infected and SMLS‐uninfected S. miscanthi clones with the identical genetic background were built in this study. Although similar Buchnera aphidicola dynamics were observed between SMLS‐infected and SMLS‐uninfected S. miscanthi population, B. aphidicola density of SMLS‐infected S. miscanthi population was always significantly higher than SMLS‐uninfected ones. The results of fitness measurements indicated that under laboratory rearing conditions, transfection of SMLS could confer modest advantages to some fitness components of S. miscanthi, that is, total number of offspring, longevity, age of first reproduction and weight of adult. However, as SMLS is not strictly associated with S. miscanthi, further investigations are needed to uncover the mechanisms responsible for this inconceivable association.     

CRISPR/Cas系统与志贺菌毒力和耐药的关系及插入序列IS600对cse2表达水平的影响北大核心CSCD

【目的】了解志贺菌中成簇的规律间隔短回文重复序列(Clustered regularly interspaced short palindromic repeats,CRISPR)的分布及其与毒力和耐药的关系,并分析志贺菌中插入序列IS600对CRISPR相关蛋白基因cse2 m RNA表达水平的影响。【方法】利用课题组前期设计的引物PCR扩增志贺菌的3个CRISPR位点、CRISPR相关蛋白基因cse2、耐药基因和毒力基因;改良Kirby-Bauer(K-B)纸片法进行药敏试验;台盼蓝计数试验检测细菌毒力;Real-time PCR检测志贺菌中cse2基因m RNA表达水平。分别分析志贺菌中CRISPR/Cas系统与耐药基因、耐药表型、毒力基因、毒力表型的关系;了解IS600对CRISPR相关蛋白基因cse2 m RNA表达水平的影响。【结果】志贺菌中CRISPR1位点阴性细菌的毒力强;插入序列IS600使cse2 m RNA表达水平降低。【结论】志贺菌中存在CRISPR1、2、3位点;CRISPR1位点与毒力有关;插入序列IS600对cse2 m RNA表达水平有影响。     

Length–weight relationships of two fish species from Yalong River,southwestern China

Length–weight relationships (LWRs) were evaluated for Jinshaia sinensis (Sauvage & Dabry de Thiersant, 1874) and Lepturichthys fimbriata (Günther, 1888) using a total of 289 specimens caught by gill nets (mesh size 5.0 cm) and angling in the Yalong River, southwestern China during February and March 2007. This study presents the first reference on LWR for these species from the Yalong River.     

Length–weight relationships of three fish species from the Yangtze River,China

Length–weight relationships (LWRs) were determined for three endemic fish species [Gobiobotia filifer (Garman, 1912), Homatula potanini (Günther, 1896) and Xenophysogobio boulengeri (Tchang, 1929)] from the Yangtze River in China. Samples were obtained between April 2008 and June 2012 using various types of fishing gear and electroshock fishing techniques. For each species, the sample size, length range, weight range, LWR, 95% confidence intervals of a and b, and coefficient of correlation were determined. Prior to this study, the LWRs for two species [Gobiobotia filifer (Garman, 1912) and Homatula potanini (Günther, 1896)] were unknown.