Evaluation of inactivated vaccine of the variant 2 (IS-1494 /GI-23) genotype of avian infectious bronchitis

The infectious bronchitis virus (IBV) is the cause of avian infectious bronchitis (IB). IB is one of the most highly contagious diseases, which results in many economic losses in the poultry industry worldwide. The nature of this virus is such that it generates new genotypes continuously. Proper vaccination is the most suitable way of combatting IB. One of the novel genotypes of IBV, which has been circulating in the Middle Eastern countries, is the variant 2 (IS-1494/GI-23) genotype. This study aims to design and produce an autogenous variant 2 vaccines. After isolation and characterization of the Iranian variant 2, the inactivated vaccine was formulated according to the OIE guidelines, and its different aspects (Purity, titration, inactivation, immunization) were evaluated. The designed vaccine passed all of OIE quality control standards. In the assessment process, the protection rate in the groups receiving the variant 2 and commercial vaccines was 67 % and 60 %, respectively. Although the differences were not significant, they indicated better protection, and the viral load in the feces and the kidney of the group receiving the variant 2 vaccine was lower than that in the commercial vaccine. It is suggested that the variant2 strain should be added as one of the local strains to the commercial inactivated vaccines in areas affected by this genotype. The use of this vaccine in layer and breeder flocks can help to protect them against variant 2 during the production phase. Also, the transfer of maternal antibodies to offspring can provide strain-specific immunity for one-day-old chickens.     

Risk,prognosis and causality of parvo viral enteritis in dogs in Sri Lanka

We studied the causal variation, prognosis and risk factors of parvo viral enteritis using both molecular and statistical analysis. A multivariate factor analysis was performed to see the effect of the breed, age, vaccination status and the leukocyte counts on disease severity and survival. Twenty PCR amplicons (partial VP2 gene) from vaccinated dogs were sequenced to identify the variants. A total of 109 samples were positive for parvo viral DNA, 71 of which were from dogs who have received at least one dose of CPV-2 vaccine. Over 90% were leukopenic on 2^nd and 3^rd day of diarrhoea. Age < 6 months was negatively correlated with leukocyte count and the leukocyte count was negatively correlated with survival. Dobermans and Labradors showed significant negative correlation with survival. All variants of parvovirus affected dogs with the 2c being the predominant (2c = 12, 2a = 7, 2b = 1). All 20 strains harboured three additional amino acid substitutions (i.e. Phe267Tyr, Ser297Ala and Tyr324Ile) and warrant further studies on potential changes of the antigenicity of the virus.     

无PAM限制的CRISPR/Cas9系统构建及效率验证

CRISPR/Cas9系统在进行靶向基因敲除、转录激活以及抑制时,需要通过识别Cas9靶位点上的一个原间隔子相邻基序(PAM)序列进行特异性靶向基因编辑。现阶段,被广泛认可的化脓性链球菌SpCas9仅识别比较短的PAM为NGG(N为任意碱基,G为鸟嘌呤)。本实验在野生型SpCas9、PAM为NG的xCas9和SpCas9-NG的基础上,构建预期PAM为NNG的突变体SpCas9NNG、预期PAM为NNN的突变体xCas9NNN和ngCas9NNN,通过双荧光素酶报告基因检测评价其切割活性。结果显示:本次实验构建的ngCas9NNN突变体对PAM为NNN的靶标DNA具有显著的切割活性,为后续拓宽CRISPR/Cas9系统的靶向范围提供重要参考。     

牛αS1酪蛋白基因变异及其与生产性状的关系

αS1酪蛋白是牛乳中含量最高的蛋白,其基因的多态类型会影响奶牛的产奶性状和牛乳的一些加工特性,人们已经对其进行了广泛研究.牛αS1酪蛋白基因编码区全长17 508 bp(不计启动子序列),由19个外显子和18个内含子构成,外显子与内含子长度比例为1∶14.4.尽管其编码区突变率较高,但侧翼序列比较保守.到目前为止,牛αS1酪蛋白共发现有9种变异体,由核苷酸非同义替换、插入或缺失及外显子跳跃造成.牛αS1酪蛋白蛋白质序列及DNA序列的高度差异性揭示其编码基因可能是一个高速进化的基因家族.αS1酪蛋白基因与泌乳性状之间的关联性可以用基因调控区,特别是转录因子结合位点存在突变位点来解释.但是,有关牛αS1酪蛋白基因变异体还存在一些未探明的结果,因此,阐明其基因的结构特点并进一步揭示它们与生产性状之间的关系是非常必要的.     

黄桃变异株系遗传稳定性的孢粉学鉴定

采用扫描电镜观测方法,对若干黄桃变异株系优良性状遗传稳定性及与来源品种之间的亲缘关系进行孢粉学鉴定,结果表明：选自锦绣的3个变异株系花粉与锦绣具有诸多共同特征,也存在一定差异,既表明它们之间亲缘关系紧密,又说明变异株系在遗传上发生了一定变化;选自丰黄的锦黄的花粉与丰黄差异更为明显,表明锦黄在遗传上产生较大变异。     

牛κ酪蛋白基因变异及其与奶用性状的关系

文章综述了牛κ酪蛋白基因变异特征及其对生产性状的影响,并且对目前存在问题进行了讨论和展望。     

转大豆DNA高蛋白小麦变异株系的硝酸还原酶、叶绿素含量分析

以新麦9号为对照,对M6代离子束介导转大豆DNA的高蛋白小麦A,B株系生育后期旗叶的硝酸还原酶活性(NR),Chl(a+b),Chla,Chlb含量及Chla/b进行了分析。结果表明:B株系硝酸还原酶活性和Chl(a+b)含量比对照高,而A株系硝酸还原酶活性比对照低(5月23日除外),Chl(a+b)含量比对照高。     

大豆Kunitz型胰蛋白酶抑制剂(SKTI)研究进展

大豆Kunitz型胰蛋白酶抑制剂（SKTI）是一种典型的丝氨酸蛋白酶抑制剂，主要集中在大豆的子叶中，近60年来，对其生化特性及结构已有较多研究，通常认为这种蛋白酶抑制剂具有贮藏，调节内源蛋白酶活性及植物防御等作用，研究表明，这种蛋白酶抑制剂抗虫谱广，能显著抑制幼虫的生长发育不易产生抗性，对人畜无害，因此对其进行研究及开发利用具有重要的经济和社会效益。迄今为止，至少已有4种基因被克隆，通过转基因技术在烟草，水稻，小麦等作物获得了抗性植株，本文从SKTI的类型，基因克隆及生理功能等方面作一简单综述。