哺乳动物抗菌肽及其在畜牧生产上的应用前景

抗菌肽是阳离子型活性肽 ,是哺乳动物防御体系的一个重要组成部分 ,具有分子量小 ,热稳定性好 ,无免疫原性 ,抗菌谱广等特点 ,通过改变细菌细胞膜的通透性而发挥抗菌作用 ,这不同于抗生素通过阻断大分子生物合成的作用机理 ,因而致病菌不易对其产生耐药性。本文就几种哺乳动物抗菌肽特性、抗菌机理、基因表达及其研究展望和存在问题进行了综述。     

哺乳动物抗菌肽的研究进展

抗菌肽(antibacterial peptides)是生物体产生的一种具有强抗菌作用的阳离子多肽,是生物先天免疫的重要组成成分[1].迄今为止,已在许多生物包括昆虫、鸟类、动物、植物及原核生物中发现600多种内源性抗菌活性肽[2].这些抗菌肽不仅有广谱抗细菌能力,而且有的对真菌、病毒及癌细胞也有作用.     

抗菌肽家族成员--防御素

抗菌肽是生物天然免疫系统中的重要组成部分@具有杀灭病菌、保护机体的作用.病原微生物入侵机体后,诱导机体产生抗菌肽.有的抗菌肽可预先合成并存储于特定的细胞和颗粒中.目前已发现了近120余种抗菌肽.防御素是其中一大家族,广泛分布于动物、植物和昆虫体内, 具有高效、广谱抗微生物活性,具有不同于抗生素的独特的抗菌机制.因此,防御素的研究成为当今医药学界的一个热点.     

抗菌肽家族成员——防御素

抗菌肽是生物天然免疫系统中的重要组成部分，具有杀灭病菌、保护机体的作用。痛原微生物入侵机体后，诱导机体产生抗菌肽。有的抗菌肽可预先合成并存储于特定的细胞和颗粒中。目前已发现了近120余种抗菌肽。防御素是其中一大家族，广泛分布于动物、植物和昆虫体内，具有高效、广谱抗微生物活性，具有不同于抗生素的独特的抗菌机制。因此，防御素的研究成为当今医药学界的一个热点。     

哺乳动物抗菌肽及其应用前景的研究

抗菌肽在宿主抵御病原微生物感染中起重要作用，是主动免疫的重要介质，是通过改变细菌细胞膜的通透性而发挥抗菌作用，这不同于抗生素通过阻断大分子生物合成的作用机理，因而致病菌不易对其产生耐药性。本文就几种哺乳动物抗菌肽特性、抗菌机理、基因工程研究及其应用前景和存在问题进行了综述。     

哺乳动物防御素生物学作用的研究进展

哺乳动物防御素是一类阳离子型多肽,根据结构差异分为α-防御素、β-防御素、θ-防御素。哺乳动物防御素具有广谱抗菌、抗肿瘤和免疫调节的作用,还参与炎症反应和修复损伤组织的作用。防御素主要通过改变细菌膜的通透性发挥抗菌作用,可以抵抗外来致病微生物的侵袭。此外,防御素还参与调控动物肠道微生态的平衡,在肠道屏障功能、肠黏膜免疫反应以及微生物菌群平衡等方面发挥积极作用。防御素在动物生产中具有促进卵母细胞和胚胎发育、成熟的作用。文章旨在综述哺乳动物防御素的研究进展,以期为哺乳动物防御素后续在饲料添加剂、疾病防治等领域中的应用提供参考。     

防御素在雌性哺乳动物生殖系统中的分布和功能研究进展

防御素(defensin)作为抗菌肽的主要家族,在哺乳动物体内广泛分布,主要表达于中性粒细胞和上皮细胞,具有广谱的抗菌活性和多方面免疫调节功能.近年来,发现防御素广泛在哺乳动物雌性生殖系统中表达,发挥抑菌抗炎的作用,预防微生物对子宫或生殖道等的感染,从而维持雌性生殖系统的环境稳定,同时参与动物生殖.论文结合已有的研究成...     

抗菌肽家族成员——防御素

防御素是一类分子量为3-4KDa的非糖基阿亲(亲水、亲脂)低分子短肽，由29～38个氨基酸组成，一般富含精氨酸，带正电荷。分子中有6个半胱氨酸残基，形成3对二硫键，含有3个     

哺乳动物上皮细胞抗菌肽分离纯化技术研究进展

抗菌肽是在动植物体内发现的氨基酸数目少于100个的一类多肽,是哺乳动物防御体系的一个重要组成部分,具有分子质量小、对热稳定、水溶性好、广谱抗菌和作用机制独特等特点。文章主要综述了几种哺乳动物上皮细胞抗菌肽的分离纯化技术研究概况。     

抗菌肽Protegrins研究进展

抗菌肽广泛存在于自然界,是动物先天免疫的重要组成成分.Protegrins是其中一类由16～18个氨基酸构成的小肽.本文综述了Protegrins在结构、基因表达和调控、作用机理及生物学活性等方面的研究进展,并对其应用前景进行了展望.     

牛蛙(Rana catesbeiana)蛙皮抗菌肽基因的克隆、测序及其表达

利用RT—PCR的方法从牛蛙皮肤组织中克隆到大小为270bp的片段RCABP，将其克隆到pGEM—T载体，测序获得1个新的碱基序列。将此基因克隆到原核表达载体pQE一80L，获得融合表达质粒pQE一80L／DHFR／ABP，在1％IPTG诱导下进行表达。SDS—PAGE检测表明，重组蛙皮抗菌肽蛋白的表达量占菌体总蛋白的24％，以包涵体形式存在。体外抑菌试验表明，所构建的质粒能在大肠杆菌中表达具有体外抑菌活性的蛙皮抗菌肽，该融合蛋白具有良好的应用前景。     

抗菌肽及其基因表达体系研究进展

抗菌肽是上个世纪70年代由瑞典科学家Boman H G首次发现的,其具有优良的光谱抗菌性能,无残留,不会导致耐药菌株的出现,是目前抗生素类较有潜力的替代品。早在上世纪80年代,人们就试图通过转基因等生物工程技术改良物种或大量表达该类物质,目前已有众多的表达体系和转基因动植物研究成功,并有一些抗菌肽类药物投入临床使用。文中综述了近年来国内外关于抗菌肽的分离提取、体外表达和转基因动植物技术,主要论述该物质在基因和生物工程方面研究进展,从而为其规模化生产利用提供参考和借鉴。     

A review of antimicrobial peptides: defensins and related cationic peptides

Cationic antimicrobial peptides are present throughout the plant and animal kingdoms and bear striking structural and functional similarities across species lines. They provide primitive, nonspecific means of combating a variety of bacteria, fungi, enveloped viruses, and protozoa. Some are also cytotoxic against host cells, including neoplastic cells. Cationic antimicrobial peptides may play various roles in inflammation and tissue repair. Antimicrobial peptides are found in epithelial tissues regularly exposed to microbial attack as well as in cells whose primary function is defense against potential pathogens. They constitute an important part of the nonoxidative antimicrobial arsenal of leukocytes. They are preformed and/or readily synthesized when the cells are stimulated by exposure to pathogens. They exert their effects directly by inserting into membranes of target cells and forming ion channels which increase membrane permeability; however, antimicrobial peptides can also act as opsonins to facilitate phagocytosis. Resistance to defensins is a virulence factor for organisms such as Salmonella sp. The study of cationic antimicrobial peptides is increasing our understanding of innate immunity, inflammation, and the pathogenesis of genetic diseases such as specific granule disease in humans. Therapeutic applications of antimicrobial peptides are currently under investigation.     

抗菌脂肽对肉鸡抗氧化能力及血清生化指标的影响

为研究不同水平抗菌脂肽对肉鸡抗氧化能力及血清生化指标的影响,将1日龄健康AA肉鸡600只,随机分为5组:对照组(不含抗菌脂肽及抗生素)、抗生素对照组及在基础日粮中分别添加4 000、8 000和12 000 U/kg抗菌脂肽组,试验期为42 d。结果发现:4 000 U/kg抗菌脂肽能显著提高血清T-AOC及肝脏SOD水平,8 000 U/kg抗菌脂肽能显著提高血清SOD水平,同时能显著降低肝脏MDA水平。4 000 U/kg抗菌脂肽能显著提高血清TP及GLOB水平,而12 000 U/kg抗菌脂肽能提高血清GOT及GPT水平,但差异不显著。抗菌脂肽对血清UN及TC含量无明显影响。结果表明适宜的抗菌脂肽添加量(4 000 U/kg)能提高肉鸡抗氧化机能,且能促进蛋白质的代谢。     

抗菌肽V13KL原核表达载体的构建及其表达产物的鉴定

将V13KL编码基因片段克隆到原核表达载体pET30b（＋）,并在目的蛋白N端设计肠激酶酶切位点,构建出pET30b（＋）-VK13L重组质粒,转化大肠杆菌表达菌株BL21（DE3）,优化诱导条件,使得抗菌肽得到了高效表达。经Tricine-SDS-PAGE和Westernblotting鉴定,目的蛋白的相对分子质量与预期一致。结果表明,V13KL基因成功克隆并且获得表达,在诱导体系中加入1mmol／LIPTG诱导6h便可检测到蛋白表达。     

Induction of maggot antimicrobial peptides and treatment effect inSalmonella pullorum-infected chickens

Antimicrobial peptides (AMP) are important components of the host innate immune response, as they exert broad-spectrum antimicrobial activities against pathogenic microbes. The AMP allow housefly larva (maggots) to live in harsh environments filled with pathogenic bacteria. In this study, maggot AMP were induced by incubation with inactivatedSalmonella pullorum and crudely extracted. The concentration and antimicrobial activity of the maggot AMP were then measured. In bird experiments, chickens were artificially infected withS. pullorum, and the maggot AMP extracts were used to treat the infected chickens. The expression level of AMP was significantly enhanced byS. pullorum stimulation, and the antibiotic activity of theS. pullorum-induced AMP was significantly stronger than that of the noninduced AMP, especially againstS. pullorum. In the bird experiments, based on survival rate, blood indicators, and intestinal bacterial changes, maggot AMP and antibiotics were successful in treating theS. pullorum-infected chickens. In conclusion, AMP have the potential for further development as a convenient, alternative antibiotic strategy to reduce the use of antibiotics and disease resistance.     

Effects of oral administration of colostrum whey in peripartum goat on antimicrobial peptides in postpartum milk

The present study was conducted to examine whether colostrum supplementation in peripartum goats increases the antimicrobial peptides in their milk. Goats were orally administered 2 ml of colostrum whey products (colostrum group) or water (control group) daily, from 2 weeks before until 2 weeks after kidding. Body weights of mothers and kids were measured. Blood, milk, and fecal samples were collected from the mothers, and blood samples were collected from the kids. Concentrations of milk antimicrobial peptides (beta‐defensin, cathelicidin, lactoferrin, S100A7, lactoperoxidase, and immunoglobulin A [IgA]) were determined. IgA and nutritional parameters (glucose, total cholesterol, triglyceride, ketone bodies, and non‐esterified fatty acids) were also determined in the blood of mothers and kids. Milk IgA and lactoferrin concentrations were higher in the colostrum group than in the control group. Conversely, lower milk concentrations of S100A7 were observed in the colostrum group than that in the control group. Plasma IgA concentrations were higher for kids from the colostrum group than for those from the control group. These results suggest that oral administration of colostrum in pregnant goats increases IgA concentration in postpartum milk, which can subsequently improve the health of their kids.     

毕赤酵母重组表达抗菌肽Fowlicidins的研究进展

文章主要介绍了Fowlicidins的抗菌特性和机制,以及其在毕赤酵母中的表达。     

微小牛蜱一个抗菌多肽编码基因的克隆和表达

为了进行抗蜱及蜱传病疫苗的研究,本研究根据微小牛蜱巴西株报道的一种抗菌多肽核苷酸序列设计引物,从微小牛蜱中国安徽株克隆到该抗菌多肽基因,全长383bp,编码110个氨基酸残基,该蛋白预测的分子量为12.2ku,等电点为4.87.经同源性比较,该微小牛蜱巴西株抗菌多肽基因有100%的相同性.经RT-PCR分析表明,该基因在微小牛蜱卵、幼蜱、半饱血雌蜱、饱血雌蜱和雄蜱这几个阶段均有表达.将该基因亚克隆到pET-28a( )表达载体,转化BL21(DE3)宿主菌,经IPTG诱导,可成功表达.重组融合蛋白大小为15ku左右,与预期大小一致.初步体外抗菌试验表明,重组蛋白具有一定的抗菌活性.Western-blot显示,兔抗微小牛蜱唾液抗体能够识别重组表达蛋白.     

抗菌肽重组逆转录病毒载体的构建、重组病毒的包装及其在牛奶中的稳定表达

将含有双抗菌肽基因的表达盒插入到逆转录病毒载体pLN-bcp-LK(R)中,获得了含有双抗菌肽基因的重组逆转录病毒载体pLN-bcp-LfcinB-CE-MA(R),利用脂质体转染PA317包装细胞,G418进行筛选得到了阳性细胞克隆,克隆扩大培养后,用病毒上清感染NIH3T3细胞进行滴度测定,最高滴度为1×104CFU/mL,用病毒上清转染妊娠中后期奶牛乳腺组织,产犊后采集的奶样经琼脂板溶圈法和Tricine-SDS-PAGE检测,结果表明乳汁中表达的抗菌肽对大肠杆菌和金黄色葡萄球菌均具有明显地抑菌活性,并能实现相对稳定的表达,表达可持续30~45 d。