Analysis of a Secreted Aspartic Peptidase Disruption Mutant of Glomerella cingulata

Peptidases have been implicated in the pathogenicity of fungi that cause disease in plants. Expression of the secreted aspartic peptidase gene (gcsap), of a Glomerella cingulata isolate pathogenic on apples, is induced during appressorium formation. To determine whether the secreted aspartic peptidase (GcSAP) is essential to pathogenicity, gcsap was disrupted using a vector containing a 637 bp fragment of genomic DNA that encodes the sequence spanning the two active site aspartic acid (Asp) residues. To ensure that the truncated gcsap gene products could not have residual peptidase activity the codons for the active site residues Asp¹¹² and Asp²⁹⁷ were both mutated to histidine residues. Both PCR and Southern analysis confirmed disruption of gcsap. Neither gcsap mRNA nor GcSAP activity was detected in the disruption mutant. Pathogenicity tests on fruit from three apple cultivars showed that GcSAP was not required for pathogenicity. The disruption mutant grew on medium containing protein as the sole source of nitrogen because G. cingulata secretes a previously undetected peptidase(s). A serine peptidase that had a pH optimum between pH 7.0 and 8.0 and a K _m of 0.25 mM for the synthetic substrate succinyl-Ala–Ala–Pro–Phe-p-nitroanilide was identified.     

Review: The strobilurin fungicides

The original article to which this Correction refers was published in Pest Management Science 58 (7): 649–662 (2002).Copyright © 2004 Society of Chemical Industry     

母猪卧向行为学的观察

本文通过2个试验对母猪在分娩圈和分娩栏中的卧向行为进行了观察，试验一中，选择10头大白（Yorkshire）经产母猪作为观察对象，试验二中分别选择10头大白（Yorkshire）经产母猪和10头长白（Landrace）经产母猪作为观察对象。观察采用瞬时记录方法，每周观察三次，隔日观察，每天上午、下午各观察一次，每次3h，每次观察间隔5min。观察中发现，母猪卧向以向外为主。分娩栏（四周是栏杆）中的母猪以选择卧向外（向北）为主，其次是卧向内（向南），卧向左和卧向右最少且差异不显著，上栏前和下栏后差异不显著。分娩圈（四周是墙壁）中母猪以选择卧向外为主，卧向内最少，卧向左和卧向右差异不显著。长白母猪比大白母猪选择卧向外的多，妊娠阶段比哺乳阶段选择卧向外的多。     

中国野牦牛种质资源库体系的建立及利用

介绍构建野牦牛种质资源信息收集、整理及调查的方法;建立了野牦牛50头规模的可良性运作的遗传繁育基地，可年产2万支冷冻精液的动态保存库，以及0.1万～0.15万枚野牦牛冷冻胚胎动态保存库的条件与规模;创建了国内外相关野生动物保护组织、行业、协会等保护和利用野牦牛遗传资源的共享平台.     

遗传标记及其在家禽育种中的应用

1 SNP SNP是染色体中遗传变异的最普通形式,如在人体已经检测基因组DNA中每1,000到2,000个单位有1个SNP,在某些区域估计每300个单位有一个SNP.基于SNP的高分辨率,遗传图谱在一些人的染色体上通常没有得到发展.正如其名称所指,SNP是发生在基因(启动子、外显子、或内含子)或基因之间(基因间隔区)的单个碱基改变或核苷酸变异.编码序列中的SNP以同义(不会导致氨基酸改变)或非同义(导致氨基酸改变)来分类.非同义SNP由于对蛋白质表达及最终对表现型的潜在影响而受到重视.相反,同义SNP可能对基因表达有微小的影响(除那些在启动子和其它基因组区域中,对DNA-蛋白质作重要的核苷酸或与RNA稳定性有关的核苷酸).同义和非同义SNP在基因图谱研究中均是很好的遗传标记.     

出血性大肠杆菌O157eae-stx1/2B融合基因的构建和表达

构建表达eae和stx1／2B的融合基因，克隆eae基因的C端280个氨基酸残基(Int280)基因部分，以正确地阅读框定向插入到含有stx1／2B融合基因的质粒，构建重组质粒，将其转化于BL21(DE3)，用IPTG进行诱导表达，经SDS—PAGE电泳检测，该融合蛋白获得了高效表达。薄层扫描分析表明：目的蛋白表达量占菌体总蛋白含量的50．67％。由于该融合蛋白由eae、stx1B、stx2B等三部分抗原组成，可刺激机体产生针对紧密素和StxB的抗体，在EHEC O157亚单位疫苗设计或单克隆抗体抗制备中具有重要价值。     

Ultrastructure of the tubular glands in the isthmus region of the oviduct in laying and natural moulting commercial egg‐type chickens

The study investigated the ultrastructural characteristics of tubular gland and duct cells, as well as luminal gland cells in the isthmus region of the oviduct of laying and natural moulting hens. Tubular glands in laying birds were composed of type 1 and 2 cells. Based on the preponderance of each cell type, in relation to the location of a developing egg in the oviduct of the domestic fowl, these gland cells may represent different functional states of the same cell. The findings of the study on natural moulting birds suggest that autophagy is a process confined to the early stages of degeneration, while necrosis occurs in the terminal stages.