沙棘黄酮枇肉鸡生长性能和内分泌的影响

选择1日龄健康AA肉仔鸡360只,采用单因子试验设计,随机分为3个处理组,每组4个重复,每个重复30只,分别为基础日粮组、0．1％沙棘黄酮组、0．2％沙棘黄酮组,进行为期8N的饲养试验。试验结果表明：在肉鸡生长全期饲料中添加0．1％、0．2％沙棘黄酮对AA肉鸡的生长性能、血清生长激素、三碘甲腺原氨酸、甲状腺素、睾酮含量没有显著影响（P〉0.05）;添加0．1％沙棘黄酮对饲料中蛋白质代谢率有提高趋势（P=0.054）,可显著提高饲料中钙的代谢率、21日龄的血清胰岛素、42日龄的血清胰高血糖素和胰岛素样生长因子-Ⅰ（P〈0.05）。     

家蚕嗅觉相关蛋白质的研究进展

昆虫对气味物质的识别是一个非常复杂的连锁反应过程,气味分子首先被嗅觉感器淋巴液中的气味结合蛋白或化学感受蛋白所结合,然后运转到位于嗅觉神经元末梢膜上的气味受体并将其激活,最后引起嗅觉神经兴奋,并传入中枢神经而被感知。家蚕成虫的嗅觉十分灵敏,长期以来一直作为研究昆虫化学通讯的理想模型。近年来,随着家蚕分子生物学研究的不断深入,在家蚕中已发现了7种气味结合蛋白、多种化学感受蛋白和气味受体蛋白,这些蛋白质因子对于家蚕识别气味分子起着关键作用,但多数蛋白因子的具体生理功能仍不清楚。以家蚕方面的研究为重点,综述了与嗅觉相关的蛋白质的生化特性、分子结构、基因表达及其生理功能等方面的研究进展。     

色氨酸对产肠毒素大肠杆菌感染SD大鼠肠道的防御作用

旨在研究色氨酸对产肠毒素大肠杆菌(ETEC)感染损伤SD大鼠肠道的防御作用。本试验采用2*2双因子试验设计,将40只28日龄雌性SD大鼠,体质量(68.41±0.29)g,随机分为4组:基础日粮组(B);ETEC攻毒组(E,1.0×10^8 ETEC K88);色氨酸缺乏组(I,0.1 mL/d、10 g/L依那普利)。色氨酸缺乏+ETEC攻毒组(E+I,1.0×10^8 ETEC K88+0.1 mL/d、10 g/L依那普利),每组10个重复,每个重复1只。采用H.E染色组织切片观察、酶联免疫吸附测定(ELISA)、三重聚合酶链式反应(PCR)、免疫蛋白印迹、实时荧光定量(RT-PCR)和变性梯度凝胶电泳(DGGE)法分别对SD大鼠肠道细胞因子水平、抗菌肽表达和蛋白水平、粪便中ETEC数量以及盲肠微生物区系变化进行检测。结果表明,依那普利通过抑制ACE2酶阻碍肠道色氨酸吸收,显著降低大鼠空肠和回肠黏膜绒毛高度、淋巴细胞数量和绒毛高度/隐窝深度值(P<0.05);ETEC攻毒显著降低大鼠空肠淋巴细胞数量、绒毛高度/隐窝深度值(P<0.05)和回肠绒毛高度和淋巴细胞数量(P<0.05)。ETEC攻毒使SD大鼠粪便中ETEC数量显著增高(P<0.05)。依那普利抑制剂对SD大鼠粪便中ETEC数量无显著影响(P<0.05);依那普利通过抑制ACE2酶阻碍肠道色氨酸吸收增加空肠和回肠IL-6(P<0.05)和空肠TNF-α质量浓度(P=0.059),降低空肠TGF-β质量浓度(P=0.056);ETEC攻毒使空肠IL-6和回肠IL-6、IL-8和TNF-α质量浓度显著增加(P<0.05),降低空肠TGF-β质量浓度(P=0.059)。依那普利通过抑制ACE2酶阻碍肠道色氨酸吸收显著降低大鼠空肠和回肠Defa-5、BD-2基因mRNA相对表达量(P<0.05);ETEC攻毒使空肠Defa-5、IDO基因和回肠IDO基因mRNA相对表达量显著增加(P<0.05);依那普利通过抑制ACE2酶阻碍肠道色氨酸吸收使空肠、回肠mTOR、BD-2蛋白水平显著降低(P<0.05),使空肠TLR-4蛋白水平显著增加(P<0.05)。色氨酸缺乏、ETEC攻毒降低盲肠微生物多样性,降低拟杆菌门微生物数量,色氨酸不缺乏组盲肠微生物多样性优于缺乏组。结果显示色氨酸通过维持肠道炎性细胞因子浓度稳定、促进肠道黏膜发育和提高肠道抗菌肽基因表达改善肠道微生态环境,对ETEC感染SD大鼠肠道具有防御作用。     

Screening and Identification of Laccase Fungi in Alpine Meadow北大核心CSCD

Nine strains of fungi that isolated from alpine meadow were used as research objects. The laccase-producing strains were identified by rDNA-ITS method. According to the strains, guaiacol, anthrone, catechol and neighbors were identified. Growth on selective medium of toluidine, o-toluidine, crnaphthol, benzidine, gallic acid as substrate, colony size, size of the color circle produced by laccase-catalyzed redox reaction, and the degree of color depth, the laccase-producing fungus is firstly screened, and the laccase activity is determined by the liquid-producing enzyme fermentation method using ABTS as a substrate for re-screening. The results showed that strain 1. 9 was Uncultured fungus clone. 2. la was Scytalidium, 310b was Marasmius tricolor, 2.1c was Saccharicola, 2. 3a was fungal sp, 2. 4d was Saccharicola. 10a was Marasmiusrotalis, 3. 7c was Alternaria. WB was Verticilliumlongisporum. The screening results showed that except for strain 3. 7c, the other 8 strains basically produced oxidative bands on the culture medium with guaiacol, anthrone, ortho-toluidine and benzidine as substrates, and cultured in gallic acid substrate. No oxidative bands were produced on the culture medium; strains 1. 9, 2. la, 310b, 2. 4d, 10a, 2. lc, and 2. 3a all had laccase activity, and strain 310b had stronger laccase activity than the other strains. © 2019 China Agricultural University. All rights reserved.     

生物安全三级实验室生物安全风险点的识别与控制?

BSL-3实验室须经国家生物安全认可和严格的实验活动审批才能开展相应活动,是国家(地区)开展高致病性病原微生物实验活动的重要技术支撑平台。实验室生物安全风险点易发生在样本及菌毒种的接收、传递和保存,动物实验,污水以及固体废弃物处理等环节,而实验室的意外事件(电力故障、火灾、积水等)与生物安保漏洞也会造成重大的生物安全事故。提示应准确地识别风险并通过人员日常监管、标准操作规程、两级屏障设施和个人防护装备等系列措施对生物安全风险点予以严格控制。     

猪仿生消化中小肠阶段消化酶对饲粮总能与粗蛋白质消化率的贡献

本试验旨在探讨猪仿生消化中小肠阶段主要消化酶的组成及活性对饲粮养分消化率的贡献,为仿生消化法评定猪饲粮养分的消化率提供参考。试验采用单因素完全随机设计,5个处理分别为胃模拟消化、胃+小肠(淀粉酶)模拟消化、胃+小肠(淀粉酶+糜蛋白酶)模拟消化、胃+小肠(淀粉酶+糜蛋白酶+胰蛋白酶)模拟消化、胃+小肠(淀粉酶+糜蛋白酶+胰蛋白酶+小肠消化4 h时补充消化酶)模拟消化,每个处理5个重复,每个重复1根消化管。考察各处理条件下玉米、豆粕、小麦麸及玉米-豆粕型饲粮的干物质、粗蛋白质及总能消化率的差异和各消化酶的贡献。结果表明:1)模拟小肠液中淀粉酶、糜蛋白酶均可显著提高胃消化后玉米、豆粕、小麦麸及玉米-豆粕型饲粮的干物质、粗蛋白质以及总能的消化率(P<0.05);胰蛋白酶可以进一步提高胃消化后豆粕、小麦麸的干物质、粗蛋白质以及总能消化率(P<0.05);补充3种消化酶可以提高对小麦麸粗蛋白质及玉米-豆粕型饲粮干物质、粗蛋白质及总能的消化率(P<0.05)。2)小肠液中消化酶对饲粮养分消化率的贡献上,因饲粮底物的不同而异,其中淀粉酶、糜蛋白酶对总能和粗蛋白质消化率的贡献相对较高,而胰蛋白酶和补充消化酶对饲粮养分消化率的贡献虽然相对较少,但也可以引起消化率显著性差异(P<0.05)。在猪的小肠模拟消化阶段,淀粉酶、糜蛋白酶、胰蛋白酶及补充消化酶对饲粮养分的消化程度均有显著性贡献。     

一例山羊胰阔盘吸虫病的诊治

胰阔盘吸虫病主要由胰阔盘吸虫寄生于牛、羊等反刍动物的胰脏及胰管内,引起机体的胰腺坏死或胰管阻塞的一类疾病。动物感染此病后,主要表现出消瘦、贫血、水肿及消化功能障碍等一系列临床症状。在本次诊治过程中,通过临床症状与病理剖解相结合的方式确定该病病原为胰阔盘吸虫。我们采用吡喹酮+氯氰碘柳胺+安乃近+林可霉素等四种药物对羊群进行驱虫,该养殖场的病情得到基本控制。     

Kaempferol alleviates the reduction of developmental competence during aging of porcine oocytes

Kaempferol (KAE) is a natural flavonoid present in different plant species and exhibits anti‐inflammatory, antioxidant, and anticancer therapeutic properties. In the present study, we investigated the influence and underlying mechanisms of KAE supplementation on porcine oocytes during in vitro aging. The results show that KAE treatment can alleviate the aging‐related reduction of developmental competence. We observed that the blastocyst production rate in aged oocytes treated with 0.1 μM KAE was significantly higher than in untreated aging oocytes (36.78 ± 0.86% vs. 27.55 ± 2.60%, respectively, p < .05). The KAE‐treated aging oocytes had significantly reduced levels of reactive oxygen species (p < .05). Furthermore, the mRNA levels of the embryonic pluripotency‐related genes Oct4, NANOG, and ITGA5 were significantly increased in blastocysts derived from KAE‐treated oocytes (p < .05). During excessive oocyte culture, KAE treatment maintained the mitochondrial membrane potential and reduced apoptosis; however, this was not observed in untreated aging oocytes. In conclusion, our results suggest that KAE treatment can alleviate the aging of porcine oocytes by reducing oxidative stress and improving mitochondrial function.     

Dynamics of methanogenesis,ruminal fermentation and fiber digestibility in ruminants following elimination of protozoa: a meta-analysis

Background: Ruminal microbes are vital to the conversion of lignocellulose-rich plant materials into nutrients for ruminants.Although protozoa play a key role in linking ruminal microbial networks,the contribution of protozoa to rumen fermentation remains controversial; therefore,this meta-analysis was conducted to quantitatively summarize the temporal dynamics of methanogenesis,ruminal volatile fatty acid(VFA) profiles and dietary fiber digestibility in ruminants following the elimination of protozoa(also termed defaunation).A total of 49 studies from 22 publications were evaluated.Results: The results revealed that defaunation reduced methane production and shifted ruminal VFA profiles to consist of more propionate and less acetate and butyrate,but with a reduced total VFA concentration and decreased dietary fiber digestibility.However,these effects were diminished linearly,at different rates,with time during the first few weeks after defaunation,and eventually reached relative stability.The acetate to propionate ratio and methane production were increased at 7 and 11 wk after defaunation,respectively.Conclusions: Elimination of protozoa initially shifted the rumen fermentation toward the production of more propionate and less methane,but eventually toward the production of less propionate and more methane over time.     

猪蛋白质二硫化物异构酶A4基因克隆及密码子偏好性分析

试验旨在研究猪蛋白质二硫化物异构酶(protein disulfide isomerase A4,PDIA4)基因的密码子使用特性及其与其他物种密码子使用的差异。试验以香猪子宫组织为试验材料,采用RT-PCR方法扩增获得猪PDIA4基因,参考从NCBI数据库中下载的18个不同物种PDIA4基因序列,对猪PDIA4基因的密码子使用特性及其与其他物种密码子的使用差异和进化关系进行分析,同时对猪PDIA4基因与4个模式生物密码子使用偏性进行比较。结果表明,猪PDIA4基因编码区长1 941 bp,共编码646个氨基酸。与NCBI数据库公布的野猪PDIA4基因(GenBank登录号:NM_001267834.1)的相似性达99%。猪PDIA4基因偏好使用G/C结尾的密码子,27种密码子为猪PDIA4基因的偏好密码子(RSCU>1),其中使用频率最高的前3个密码子分别为CTG(RSCU=3.69)、GCC(RSCU=2.31)和CGC(RSCU=2.29)。比较19个物种PDIA4基因发现,不同物种间PDIA4基因的有效密码子数(ENc)、密码子适应指数(CAI)、GC含量以及T、C、A、G、G+C在密码子第3位含量(T3s、C3s、A3s、G3s、GC3s)均存在差异,且密码子偏好以G/C结尾;聚类分析发现,基于CDS序列的系统进化树更符合19个物种的真实分类系统。在密码子使用频率上,猪PDIA4基因与小鼠基因组间密码子使用偏好程度更为接近,故小鼠更适合作为猪PDIA4基因的遗传转化和异源表达的受体系统。