家蚕细胞色素P450基因CYP9A22的克隆及在中肠和脂肪体的诱导转录

细胞色素P450对昆虫的生长发育、环境适应性以及抗药性具有重要作用。为了探讨氯氰菊酯对家蚕(Bombyxmori)细胞色素P450基因转录的诱导作用,采用RT-PCR技术和cDNA末端快速扩增(RACE)策略,从家蚕5龄幼虫克隆到细胞色素P450基因CYP9A22(GenBank登录号:EF535804)。CYP9A22基因的cDNA编码区长1 596 bp,编码531个氨基酸,推定的蛋白质分子质量为61 kD,等电点为7.71。将该基因的cDNA和家蚕基因组序列比对,有9个内含子;与已知的CYP9家族的棉铃虫(Helicoverpa armigera)CYP9A14基因的相应氨基酸同源性达到62.3%。用半定量RT-PCR方法分析氯氰菊酯诱导家蚕CYP9A22表达水平,结果表明:CYP9A22的mRNA转录表达具有组织特异性,在中肠的表达量高于脂肪体;氯氰菊酯诱导家蚕24 h,在其脂肪体的表达量是未诱导家蚕脂肪体的3.1倍,初步推测CYP9A22的过量表达可能与抗药性有一定关系。     

慢病毒载体的构建及其应用于转基因动物的研究进展

为提高慢病毒载体构建水平,提高转基因整体效率,作者综述了慢病毒载体结构及围绕改善生物安全性、提高目标基因装载量、扩大宿主范围而进行的慢病毒载体改造研究发展历程,指出新型慢病毒载体去除了病毒所有辅助基因,引入了外源调控序列,替换了包膜蛋白,大大提高了慢病毒载体的安全性、基因转移效率和表达效率,使宿主细胞类型更广范,而下游表达载体转染方法的研究又为转基因方法的集成与优化奠定了基础。慢病毒载体制备与多种转基因技术的优化集成,将有助于发展简便、高效、经济的转基因新技术,提高转基因技术的整体水平。     

Mechanisms Involved in the Growth Promotion of Weaned Piglets by High-level Zinc Oxide

Dietary supplementation with high levels of zinc oxide (ZnO) is an effective method to prevent diarrhea and promote growth in weaned piglets. However, the mechanisms behind these beneficial effects are not well understood. Recent advances in this field indicated that the effects of ZnO on piglet growth are achieved through multiple regulatory pathways rather than a single pathway. This review focuses on recent advances in the effects of high level ZnO on:1) Zn status in weaned piglets;2) intestinal microbe flora regulation;3)intestinal structure and function;4 )ion secretion in the intestine epithelium;5) intestinal immunology; and 6) secretion of brain-intestine peptides. ZnO appears to regulate the intestinal microflora and decreases the release of histamine to prevent diarrhea. ZnO also increases the expression of intestinal insulin-like growth factor-1 (IGF-1) and the IGF-1 receptor to ameliorate intestinal injury associated with weaning, and mediates secretion of brain-gut peptides to stimulate food intake, to promote the growth of piglets. Better understanding of the underlying mechanisms should inspire us to supplement the diet for weaned piglets with ZnO and investigate new approaches to prevent diarrhea and enhance growth.     

饲料用混合油脂中苯并(a)芘测定方法的比较与优化

文中分析比较了三种油脂中苯并(a)芘含量的测定方法,其中GB/T22509—2008《动植物油脂苯并(a)芘的测定》方法安全性高、可行性强。本试验对该方法存在的一些不足之处加以优化后,用以测定饲料用混合油脂中苯并(a)芘的残留。标准品苯并(a)芘在0.5～20μg/l范围内的线性回归方程为:Y=1.445 6X+0.004 1,R2=0.999 5。油脂样品添加苯并(a)芘10μg/kg水平时的平均回收率为102.2%(N=5,RSD=2.3%);添加5μg/kg水平时的平均回收率为95.5%(N=5,RSD=4.2%)。结果表明该方法稳定性好、分析准确度高,非常适合用以评价油脂中苯并(a)芘的残留情况。抽样检测结果表明我国饲料级混合油中苯并(a)芘都有检出而且含量高于美国进口饲料级混合油,具有一定安全隐患。     

纳豆菌制剂在动物养殖中的应用

纳豆菌是生产微生态制剂的理想菌株之一,现已作为绿色饲料添加剂广泛应用于饲料。本文主要就近年来纳豆菌制剂在动物养殖中的研究与应用成果作一概述,以期为畜牧生产提供参考。     

重庆地区表观健康猪中猪链球菌的检测

本研究旨在调查重庆地区表观健康猪的猪链球菌带菌情况,并揭示健康猪群携带猪链球菌的公共卫生学意义。随机采集重庆市17个区县(市)定点屠宰场表观健康猪的腭扁桃体1 360份,进行猪链球菌的分离鉴定,并对致病性较强的1、2、7、9、14型及1/2型进行分型与毒力因子分析。结果共分离到225株猪链球菌,分离率为16.54%;检出猪链球菌2型4株,猪链球菌7型3株,猪链球菌9型3株,猪链球菌1/2型1株;毒力因子谱分析发现多数(10/11)分离株缺失部分毒力因子,但也存在具有全部已知毒力因子的强毒株,且在国内首次检出小片段mrp型猪链球菌1/2型1株和7型2株。结果提示,重庆地区健康猪群带菌现象普遍,且流行菌株具有与国外不同的特点,对屠宰场工作人员健康造成威胁。     

Effects of dietary oregano essential oil supplementation on growth performance,intestinal antioxidative capacity,immunity, and intestinal microbiota in yellow-feathered chickens

Essential oils are plant-derived aromatic volatile oils, and they contain bioactive compounds that have been shown to improve poultry nutrition. In this study, we investigated the effects of oregano essential oil (OEO) on intestinal antioxidative capacity, immunity, and gut microbiota of young yellow-feathered chickens. A total of nine hundred and sixty 1-d-old female Qingyuan partridge chickens were randomly allocated to four treatment groups with six replicates of 40 birds each, and the feeding trial was lasted for 30 d. The controls were fed on a basal diet without in-feed antibiotics; the birds in the antibiotic group were fed the basal diet supplemented with 20 mg/kg virginiamycin; the remaining birds were fed the basal diet containing 150 or 300 mg/kg OEO, respectively. Dietary supplementation with 150 or 300 mg/kg OEO increased average daily feed intake (P = 0.057) and average daily gain (P < 0.05). The activities of glutathione peroxidase and total antioxidative capacity in plasma, jejuna, and ileal mucosa were increased by OEO supplementation (P < 0.05), with a trend of lower jejunal content of malonaldehyde (P = 0.062). Moreover, dietary OEO increased the content of secretory immunoglobulin A (P = 0.078) and the relative expression of Claudin 1, Mucin 2, and Avain beta-defensin 1 in ileum (P < 0.05). Sequencing data of 16S rRNA indicated that dietary OEO increased the relative abundance of Firmicutes phylum, and Clostridium and Lactobacillus genera, and decreasing that of Romboutsia. Functional analyses indicated that microbial amino sugar and nucleotide sugar metabolism, replication, and repair systems were higher in OEO groups than those of controls and antibiotic treatment. In conclusion, dietary supplementation with OEO enhanced growth performance, alleviated local oxidative stress in intestine, improved production of natural antibodies, and favorably modulated intestinal microbiota composition.     

H9N2亚型禽流感流行分析及疫苗毒株的筛选

本研究旨在筛选新型免疫原性好、广谱的优秀 H9亚型禽流感病毒疫苗株。通过 H9N2分子流行病学调查对分离得到的37株禽流感 H9N2亚型病毒进行 HA 基因分子遗传进化及其关键位点分析,利用交叉 HI 效价及鸡胚中和试验分析毒株间毒力及其相关性,制备疫苗用毒株进行免疫攻毒保护试验。结果显示,从37株病毒中选出12株病毒作为代表,分为3个分支,同分支之间交叉 HI 效价及中和效价最高。HI 试验及鸡胚中和试验均显示同分支毒株间的相关系数高。免疫攻毒保护试验显示同分支疫苗株安全性高。表明我国禽流感 H9N2亚型情况复杂,且疫苗保护效果与疫苗株的抗原匹配性密切相关,生产多种分支 H9疫苗株联合更有利于控制 H9型禽流感,     

关于天津市非洲猪瘟无疫小区创建工作的思考

2019年12月,农业农村部组织制定颁发了《无规定动物疫病小区评估管理办法》(农业农村部公告第242号)、《农业农村部办公厅关于印发<无非洲猪瘟区标准>和<无规定动物疫病小区管理技术规范>的通知》(农办牧〔2019〕86号)等文件,随即启动了非洲猪瘟无疫小区建设工作.天津市农业农村部门高度重视该项工作,第一时间组织了...     

遗传算法优化超声辅助低共熔溶剂提取红枣总黄酮工艺研究

本文采用一种新型绿色溶剂提取红枣总黄酮,并对其提取工艺进行优化.通过单因素试验探究含水量、超声功率、提取时间、提取温度和料液比对红枣总黄酮得率的影响.在此基础上,采用遗传算法优化超声辅助低共熔溶剂提取红枣总黄酮工艺.结果表明:超声辅助低共熔溶剂提取红枣总黄酮最优的工艺参数为:含水量37％、超声功率167 W、提取时间3...