In vitro screening and QTL analysis for drought tolerance in diploid potato

Drought stress is a major abiotic constraint limiting crop production worldwide. Screening for drought tolerance and the traits that enhance drought tolerance is not straightforward in large mapping populations. In this study, we investigated the possibility of screening a mapping population in vitro for PEG-induced water deficit stress and recovery potential. We have measured several shoot and root growth parameters or traits in the C × E diploid potato mapping population. Significant variation was observed for genotype-specific responses to water deficit and recovery potential. Genetic variation and heritability estimates were high to very high for the measured traits depending on growth conditions. In order to identify potato QTLs for drought tolerance and recovery potential an SNP marker-rich integrated linkage map was used. A total of 23 QTLs were detected under control, stress and recovery treatments explaining 10.3–22.4% of the variance for each phenotypic trait. Among these, 10 QTLs were located on chromosome 2. Three QTLs involved in the important trait root to shoot ratio were identified on linkage groups 2, 3 and 8. These loci explained together 41.1% of the variance for this trait, and may be breeding targets for stress tolerance and yield in the field as well. The SNP markers derived from EST sequences underlying these QTLs led to the identification of putative candidate genes for further study in potato. This study constitutes the first knowledge of in vitro screening of a mapping population for drought tolerance in potato.     

Charts for Guiding Irrigation in Real Time

In order to adjust correctly the irrigationcalendar to actual weather and waterlimiting conditions, farmers requireguidelines to help them in their day to daydecisions. In this paper a procedure isoutlined to present such guidelines in theform of a single chart. On the chartinformation concerning the irrigationinterval and irrigation duration ispresented. Tables guide the user (i) toadjust the irrigation interval to theactual weather conditions throughout thegrowing season and (ii) to select theduration of the water application as afunction of the characteristics of theirrigation system. In case of watershortage during a particular period,additional data informs the user on thesensitivity of the crop to water stress. Anexample is presented for drip irrigatedtomatoes in the region of Tunis on afluvisol.     

Pathogenesis of leptospirosis: the influence of genomics

Leptospirosis is the most widespread zoonosis worldwide and is caused by serovars of pathogenic Leptospira species. The understanding of leptospiral pathogenesis lags far behind that of many other bacterial pathogens. Current research is thus directed at identification of leptospiral virulence factors. Saprophytic Leptospira species are environmental organisms that never cause disease. Comparative genomics of pathogens and saprophytes has allowed the identification of more than 900 genes unique to either Leptospira interrogans or Leptospira borgpetersenii; these genes potentially encode virulence-associated proteins. However, genes of unknown function are over-represented in this subset of pathogen-specific genes, accounting for 80% and 60% of open reading frames, respectively. This finding, together with the absence of virulence factor homologues among the proteins of known function, suggests that Leptospira possesses unique virulence mechanisms. Whole genome microarray studies have identified genes whose expression is differentially regulated under a range of simulated in vivo conditions, such as physiological temperature and osmolarity, low iron levels, and the presence of serum. The subset of genes identified by these studies is likely to include virulence factors. However, most such genes encode proteins of unknown function, consistent with the hypothesis that leptospiral virulence genes do not have homologues in other bacterial species. The recent development of mutagenesis systems for pathogenic Leptospira spp. has allowed the screening of defined mutants for attenuation of virulence in animal infection models and has identified definitively for the first time a range of virulence factors, including lipopolysaccharide, flagella, heme oxygenase, and the OmpA-family protein, Loa22. Interestingly, inactivation of a number of genes hypothesised to encode virulence factors based on in vitro virulence-associated properties did not result in attenuation of virulence, suggesting a degree of functional redundancy in leptospiral pathogenic mechanisms.     

拟松材线虫对黑松苗的致病性

测定来源于中国、日本、韩国、加拿大、挪威和法国的20个拟松材线虫种群对2年生黑松苗的致病力。根据其致病力大小分为3类：第1类致病力很强，致死率大于85％，RHS(相关寄主适生性)系数大于100，包括法国的1个种群和中国的3个种群；第Ⅱ类有较强的致病潜能，在环境适宜的情况下可能造成严重危害，这一类数量最多，包括中国的11个种群和加拿大的1个种群；第Ⅲ类几乎没有致病力，其致死率和RHS系数都是0，包括韩国的2个种群及日本和挪威各1个种群。试验证明法国BmFr种群致死速度最快，致病力最强。黑松苗在感染拟松材线虫后，用自然界水分胁迫和PEG胁迫处理，结果表明，干旱胁迫能明显加快黑松苗死亡速度，且大大提高死亡率。提示在高温干旱的年份拟松材线虫可造成松树的大面积死亡。     

松材线虫与拟松材线虫杂交及后代的致病性

收集松材线虫5虫株与拟松材线虫1虫株进行生物学杂交,结果显示:松材线虫各虫株均能与拟松材线虫杂交且杂交率均较高,但杂交后代中普遍存在线虫死亡率较高的现象.用杂交后代线虫与未杂交亲本线虫分别接种2年生马尾松苗,结果表明杂交后代线虫对接种松苗的致病性小于其未杂交亲本线虫,从接种后萎蔫的松苗中再分离线虫,杂交后代线虫再分离数远少于亲本线虫数.     

Benign peripheral nerve sheath tumor of the perianal region in a young pony.

A 20 x 10 cm, lobulated mass was present in the perianal region of a 4-year-old Dales pony. Histopathology revealed an unencapsulated, loose arrangement of sheets and whorls of narrow mesenchymal cells, situated in the deep dermis. Intervening areas had a myxomatous appearance. The whorls were often arranged around a central structure resembling an axon or a vascular structure. Immunohistochemistry revealed that the elongated mesenchymal cells and central axon-like structures expressed vimentin, S-100, and neuron-specific enolase, but not pancytokeratin, glial fibrillary acid protein, and the neurofilament markers, NR4 and 2F11. On the basis of the histopathology and immunohistochemistry, a diagnosis of benign peripheral nerve sheath tumor (schwannoma type) was made. This case was unusual in that the concentric laminations of Schwann cells were very loosely arranged, with an intervening myxomatous stroma (Antoni type B appearance) and despite its benign histological appearance, the mass extended deeply to the proximal sacral vertebrae. Its exact origin was unclear; it may have arisen from cutaneous nerves with deep extension or from neural structures in the sacral region. Due to the incomplete surgical removal, regrowth of the mass occurred.     

甘蔗根癌农杆菌介导转化海藻糖合酶基因获得抗渗透胁迫能力增强植株

 由双拷贝CaMV35S启动子驱动担子菌灰树花 (Grifolafrondosa)的海藻糖合酶基因 (TSase)构建植物表达载体 pBBBT ,通过三亲交配法将 pBBBT导入根癌农杆菌EHA10 5菌株 ,经根癌农杆菌介导转化甘蔗 (Saccha rumhybrid)栽培品种 ,以增强甘蔗的抗旱能力。结果表明 ,甘蔗胚性愈伤组织对EHA10 5菌株敏感 ,甘蔗外植体开始大量形成胚性愈伤组织时是感染的适宜时期 ,用膦丝菌素 (PPT)筛选 ,抗性植株发生频率平均为 4 .5 %。经PCR及dot Southern检测证明 ,TSase已经整合到甘蔗基因组中。部分转化植株根叶畸形、株型异常、生长缓慢。移栽到含PEG80 0 0 17.4 % (w/v)的MS培养基后 ,观察到转基因植株抗渗透胁迫能力增强     

YW-S血缘玉米自交系昌7-2的选育及应用

YW-S血缘玉米自交系昌7-2是运用相同雄亲交叉巢式遗传设计的选育技术，导入亚热带玉米种质，经安阳市农业科学研究所内、海南连续7个世代交替培育而成，目前国内育种单位利用该自交系已育成10多个通过国家审定、省审定的优良新杂交种。在全国推广应用面积达700万hm^2。获得了显著的经济效益和社会效益。     

动物园动物体内寄生虫的调查

为了摸清我市龙沙公园内展出的野生观赏动物寄生虫的感染情况 ,1991年以来随机对齐齐哈尔市龙沙公园的 33种 2 2 5头 (只 )的不同动物进行了以肠道寄生虫为主的 (不包括皮肤寄生虫 )调查 ,基本查清了感染情况 ,对临床治疗、动物管理和人员防护将起到协助作用。报告如下。1　普查方法1.1　蠕虫学常规粪检法收集虫卵。饱和食盐浮集法、反复洗涤沉淀法等 ,对肠道寄生原虫除直接涂片碘着色观察外 ,并用铁苏木素染色法 ,制成标本保存 ,以便鉴定虫体。1.2　用蠕虫学剖检对尸体进行虫体收集。1.3　对临床检查寄生虫阳性的动物进行驱虫 ,对驱出的虫…