Variations in heavy metal concentrations among trophic levels of the food webs in two agroecosystems

Excessive accumulation of trace metal in soil represents a growing environmental problem posing severe risks to biota, humans and ecosystems. Concentrations of Cd, Pb, Cu and Zn were determined in soil, as well as in representatives of some trophic levels in the terrestrial food webs in two Egyptian agroecosystems; El-Manzala (a rural area located in the northeast of the River Nile Delta) and El-Tebbin (an industrial area located in South Cairo). Representatives of trophic levels included arthropods, amphibians, reptiles, birds and small mammals. Metal concentrations were determined in the leaves of wild plants, bodies of arthropods and livers of vertebrates. Levels of metals in the soil, plants and most animal species were higher in El-Tebbin than El-Manzala. Minimal concentrations of metals were detected more often in plants and in the cattle egret, whereas maximum values were common in the soil, amphibians and a mantid. Accumulation of metals was more frequent in arthropods and other taxa at lower trophic levels of food webs, suggesting that the transfer of metals along the vertebrate food web may be of relatively minor importance. However, of all the metals examined, only Pb was bioaccumulated to any appreciable extent in some of the higher trophic levels. A significant increase in liver mass and relative liver mass of the Norway rat from the polluted site was observed.     

微生物发酵粗饲料在反刍动物生产中的应用研究进展

粗饲料是指天然水分含量小于45%,干物质中粗纤维含量大于或等于18%,并以风干物质为饲喂形式的饲料。利用微生物发酵处理粗饲料,可以改变其适口性差、消化率不高等缺点,降低粗饲料中的抗营养因子,改变其微观结构,提高反刍动物消化率及免疫力。文章就粗饲料原料种类、处理方法、微生物发酵粗饲料作用机理、菌种种类、生产工艺贮存方式以及其在反刍动物生产当中的应用等进行综述。     

精原干细胞移植在家畜生产中的应用

本文阐述了精原干细胞的分离纯化、冷冻保存、移植等一系列相关研究技术 ,同时围绕国内外最新研究进展展望了精原干细胞在家畜生产上的潜在应用     

野生动物分离菌耐药基因多重PCR检测及序列分析

调查来源于16种四川地区野生动物粪样的24株革兰氏阴性肠杆菌中氨基糖苷类抗生素四种修饰酶基因(am inoglycosides-mod ifying en-zym es,AMEs)的分布情况。应用K-B法进行常规药敏试验,采用多重PCR技术检测分离菌中四种AMEs(aphA3、aacC4、aadA、aacC2)基因并进行序列分析。药敏试验显示分离菌对链霉素的耐药率最高(8/24),对新霉素的耐药率最低(1/24%);多重PCR检测结果显示,aphA3、aa-dA、aacC2基因的检出率分别为:7/24、3/24和2/24,而所有菌株中均未检出aacC4基因;序列分析表明扩增产物与Genbank中的相应序列有很高的同源性(≥97.8%)。     

中草药提取物对水生动物常见病原菌的体外抑菌试验

采用两倍试管稀释法测定了中药提取物对水生动物常见病原菌的体外抑菌效果,试验结果表明,大黄、黄芩和板蓝根提取物对水生动物常见病原菌有较强的抑菌效果,五倍子的抑菌作用较弱。采用水煮、醇提和微波法得到的大黄、黄芩和板蓝根提取物较散剂的抑菌效果明显,但黄莲经水煮、醇提和微波提取后药效降低,五倍子的药效受提取方法影响较小。     

可遗传与非可遗传构件应用与转基因动物食品安全评价介绍

近年来基因工程技术不断发展,转基因生物及其产品如雨后春笋般不断涌现,随之而来的转基因食品安全问题也逐渐引起关注和重视。可遗传与非可遗传构件的应用作为生产转基因动物的方法,其存在的潜在风险与巨大的发展前景共存。作者就可遗传与非可遗传构件应用及与转基因动物食品安全评价的关系进行了介绍和讨论,并对其未来的发展做出展望。     

诱导多功能干细胞在畜牧业生产中应用的研究进展

诱导多功能干细胞（induced pluripotent stem cells, iPS细胞）的研究是当前生物技术领域研究的热点之一,如果家畜的iPS细胞诱导成功,将iPS细胞诱导技术、转基因技术和细胞核移植技术相结合,在家畜的遗传育种,尤其是在转基因育种、转基因生物反应器等方面具有极大的科研及应用价值。笔者就iPS细胞的研究概况、生物学特性、及其在畜牧业生产中的应用前景作了阐述,同时初步探讨了尚需解决的学术及技术问题。     

Emergence of penicillin-macrolide-resistant Streptococcus pyogenes among pet animals: An ongoing public health threat

Macrolide-resistant Streptococcus pyogenes is an emerging problem with a great public health concern throughout the world. The current study was carried out in order to investigate the possible role of pet animals in the epidemiology of such pathogen. For this purpose, nasal or oral swabs were collected from 115 pets (40 dogs and 75 cats) with respiratory illness. The collected swabs were cultured for isolation and identification of S. pyogenes. Macrolide-resistant S. pyogenes strains were initially identified after antibiotic susceptibility testing of the all obtained S. pyogenes isolates, then the phenotypic and molecular identification were done using the double-disk test and the detection of macrolide resistance genes, respectively. Of the 115 examined pet animals, S. pyogenes was recovered from 11 (9.6 %), from which, the isolation rates among dogs and cats were 15 % and 6.7 %, respectively. Macrolide-resistant S. pyogenes was isolated from dogs and cats in the following rates 10 % and 5.3 %, respectively. All macrolide-resistant S. pyogenes strains were assigned to cMLS resistance phenotype while all of them carried ermB gene only, except one strain from a cat possessed both ermB and ermTR genes. The phylogenetic analysis of 4 ermB gene sequences showed high genetic relatedness with those carried by bacteria isolated from human cases to underline the public health impact of such strains. Seriously, all macrolide-resistant S. pyogenes strains were resistant to penicillin. The emergence of penicillin-macrolide resistant S. pyogenes among pet animals underscores not only an emerging veterinary pathogen, but also an ongoing public health threat.     

养殖场中动物源大肠杆菌blaCTX-M-27基因的传播特征探究

从2014年和2016年保存的来自河南、广东、山东和湖北4个省1 100株食品动物肠道大肠杆菌中筛选出58株blaCTX-M-27阳性菌株,采用药敏试验测定产blaCTX-M-27的大肠杆菌对20种抗生素的敏感性,并用PCR的方法检测其所携带的其他耐药基因;通过脉冲场凝胶电泳分析各菌株之间的亲缘关系,通过接合或转化试验、复制子分型和Southern blot对携带blaCTX-M-27的质粒特征进行分析。结果显示,58株blaCTX-M-27阳性大肠杆菌对除了β-内酰胺类外的其他抗生素,尤其氟喹诺酮类呈现高水平耐药;大多数菌株还同时携带2~3种编码其他抗生素的耐药基因。PFGE分型结果表明,来源于同一采样地及不同省的菌株存在克隆现象,但不同省或来自于同一省份的不同采样地之间的菌株亲缘关系较远;菌株携带的blaCTX-M-27基因全部定位在质粒上,其中38株位于可接合的IncFIB质粒,另外20株位于不可分型的质粒。