Characterization of bovine ileal epithelial cell line for lectin binding,susceptibility to enteric pathogens,and TLR mediated immune responses

In this study, primary and immortalized bovine intestinal epithelial cells (BIECs) were characterized for the expression of surface carbohydrate moieties. Primary BIEC-c4 cells showed staining greater than 90 % for 16 lectins but less than 50 % staining for four lectins. Immortalized BIECs showed significantly different lectin binding profile for few lectins compared to BIEC-c4 cells. BIEC-c4 cells were studied for infectivity to E. coli, Salmonella enterica, bovine rotavirus, bovine coronavirus, and bovine viral diarrhea virus. Bovine strain E. coli B41 adhered to BIEC-c4 cells and Salmonella strains S. Dublin and S. Mbandaka showed strong cell invasion. BIEC-c4 cells were susceptible to bovine rotavirus. LPS stimulation upregulated IL-10, IL-8, and IL-6 expression and Poly I:C upregulated TLR 8 and TLR 9 expression. This study provides important knowledge on the glycoconjugate expression profile of primary and immortalized BIECs and infectivity and immune responses of primary BIECs to bacterial and viral pathogens or ligands.     

Effect of miRNA-33 on ABCA1/ABCG1 expression in RAW264.7 macrophage-derived foam cells after Hcy treatment

AIM:To study whether homocysteine (Hcy) inhibits the expression of ATP-binding cassette transporter A1 (ABCA1) and ATP-binding cassette transporter G1 (ABCG1) by microRNA-33 (miRNA-33) signaling, and reduces the efficiency of reverse cholesterol transport (RCT).METHODS:RAW264.7 macrophages were induced by oxidized low-density lipoprotein (ox-LDL) to establish foam cell model. Oil red O staining was used to determine whether the model was established successfully. miRNA-33 mimics and miRNA-33 inhibitor were transfected into the cells by Lipofectamine 2000, and the cells were exposed to Hcy at concentration of 5 mmol/L for 24 h. The intracellular lipid droplets were observed by Oil red O staining. The expression of ABCA1 and ABCG1 at mRNA and protein levels was determined by real-time PCR and Western blot. The cellular cholesterol content was analyzed by HPLC, and effluent rate of cholesterol was detected by the method of liquid scintillation counting.RESULTS:Compared with blank control group, the lipid content in miRNA-33 mimics group was increased, and the expression of ABCA1 and ABCG1 at mRNA and protein levels was decreased (P<0.05). The intracellular cholesterol content was increased gradually (P<0.05), and the cellular cholesterol efflux rate was gradually decreased (P<0.05) in miRNA-33 mimics group. Compared with blank control group, the testing results in miRNA-33 inhibitor group were the opposition of those in miRNA-33 mimics group (P<0.05). No diffe-rence of the above indexes among blank control group, miRNA-33 mimics-NC group and miRNA-33 inhibitor-NC group was observed.CONCLUSION:Hcy inhibits the mRNA and protein expression of ABCA1 and ABCG1 through miRNA-33 signaling, and reduces the efficiency of RCT in RAW264.7 macrophage-derived foam cells.     

鸡源株与人源株H9N2流感病毒血凝素受体结合位点氨基酸比较与分析

H19N2病毒可以感染多种禽类和哺乳动物，包括人类。流感病毒血凝素受体结合位点的氨基酸可以影响受体结合特性。为了解鸡源株与人源株H19N2病毒受体结合部氨基酸的差异，作者对二者进行了比较与分析，结果表明，鸡源株与人源株血凝素受体结合部位氨基酸的第137、183、190、226位点存在差异，鸡源株在这些位点分别为K、N、AorVorT、LorQ而人源株则分别为R、H、E、L。虽然尚不清楚这些位点的改变对病毒与细胞亲和力及宿主范围的影响，但由于H9N2在我国养鸡业的普遍存在，加强H9N2病毒的分子流行病学监测有重要意义。     

棉花黄萎病菌毒素结合位点初探

以纯化的棉花黄萎病菌毒素(PLPC)免疫新西兰白兔制备了PLPC特异性抗血清。将PLPC(15μg·ml 1)用不同浓度的抗体(1～20μg·ml 1IgG)吸附后处理泗棉3号的切根苗,毒素所引起的症状都有不同程度的减轻。表明所制备的抗体在与毒素发生特异性免疫学反应的同时,可部分封闭毒素分子上与毒素受体结合的位点。利用竞争ELISA测定了泗棉3号幼苗子叶的质膜制剂与PLPC的结合活性。结果表明,质膜制剂与毒素结合后能部分阻断毒素与其抗体的免疫学反应,即质膜制剂中含有毒素的结合位点。分别用胰蛋白酶和煮沸处理质膜制剂后,质膜制剂对毒素与其抗体的反应的抑制作用消失,初步表明质膜制剂中与毒素结合的是蛋白质。     

肽在瘤胃内的代谢和利用

微生物蛋白降解作用形成的多肽经过一系列肽酶最终转化为氨基酸,其速度取决于多肽的化学组成和N端结构.大多数情况下,瘤胃肽在栖瘤胃拟杆菌分泌的二肽基肽酶作用下,从多肽N未端释放二肽而不是游离氨基酸.通过抑制栖瘤胃拟杆菌的二肽基肽酶活性或该菌对肽吸收率可以减慢混合瘤胃群落对肽的水解速率.肽和氨基酸刺激瘤胃微生物的生长,并且对许多种菌的最佳生长是必需的.纤维分解菌是个例外.当然,细菌蛋白质合成时利用氨与肽和氨基酸的比例也取决于它们的浓度.     

抗菌肽与抗生素的体外抗菌效果比较

应用由 Hancock实验室改进的微量肉汤稀释法测定了 cecropin P1、cecropin A、magainin 2、defensin 1、bactenecin、lactoferricin和 indolicidin等 7种抗菌肽和盐酸金霉素、去甲万古霉素、土霉素、强力霉素等 4种抗生素的体外抗菌活性 ,并且使用薄层琼脂糖孔穴扩散法比较了抗菌肽中 cecropin P1和 cecropin A与土霉素和呋喃唑酮对大肠杆菌 K88的抑菌效果。结果发现 ,抗菌肽与抗生素一样对几种革兰氏阳性菌和阴性菌都有不同程度的抗菌效果。其中 cecropin A、cecropin P1和 defensin1对大肠杆菌的 2个菌株 ATCC2 5 92 2和 K88的抗菌活性高于抗生素 ,defensin1是各种抗菌肽中对金黄色葡萄球菌抗菌效果最好的。抗生素对试验用金黄色葡萄球菌的抑制活性总体上要好于抗菌肽。与抗生素相比 ,cecropin A、cecropin P1和 indolicidin对猪霍乱沙门氏菌和鼠伤寒沙门氏菌具有更好的抗菌效果。另外 ,抗菌肽的抑菌圈边缘十分清晰 ,而抗生素的整个抑菌圈都比较模糊且界线不明。因此 ,从抗菌效果方面考虑 ,抗菌肽可以代替抗生素用于疾病的预防和治疗     

昆虫抗菌肽生物学活性及其应用前景

昆虫抗菌肽是昆虫免疫后存在于血淋巴中的一类活性肽 ,具有广谱的抗菌、抗病毒、抑制肿瘤的生物活性 ,具有很高的应用潜力。本文主要介绍昆虫抗菌肽的类型、生理活性、基因的克隆与表达及在动物科学中的应用前景     

油菜籽来源抗氧化物质研究进展

油菜籽中含有多种具有抗氧化活性的物质，为抵御机体的氧化损伤起到了积极作用。本文综述了油菜籽来源的诸多抗氧化活性成分及抗氧化活性的评价方法。油菜籽主要的抗氧化成分有肽类、多酚类、多糖类、生育酚和其它抗氧化成分，其中的肽类主要有三种产生方式：非消化酶酶解、消化酶酶解和发酵。针对油菜籽来源的活性物质抗氧化活性的评价方法，包括体外测定方法（化学检测）和细胞内抗氧化实验和动物实验。综述还探讨了油菜籽抗氧化活性成分研究中存在的问题和解决方法，旨在为油菜籽活性成分的开发和利用提供参考。