合成氨基酸对肉鸡肠道功能的改善作用

鸡球虫病、坏死性肠炎等肠道感染可能对消化道内源性氨基酸损失产生较大影响。虽然对这一课题的了解不多，但相关文献报道了这些疾病对氨基酸表观回肠消化率的影响。在确定肠内氨基酸流动时必须考虑多种因素，包括肉鸡的年龄、是否有病原体、肠内氨基酸代谢等。胃肠道和肝脏共同承担向外周血释放氨基酸的任务，这些氨基酸是支持蛋白质合成所必需的。一般来说，肠道是氨基酸代谢反应的一个非常活跃的器官系统，它首先会满足自身对氨基酸的需求，然后才会将氨基酸输送到机体其他部分。因此，本综述旨在讨论影响肠内氨基酸流动的因素及日粮氨基酸和肠道感染对氨基酸利用和代谢的影响。     

瘤胃微生物在木质纤维素价值化利用的研究进展

瘤胃是反刍动物消化的第一个腔室，各种微生物（细菌、真菌和原生动物）相互作用将木质纤维素植物生物降解为易于代谢的化合物。瘤胃也是目前自然界公认的木质纤维素高效降解和利用的天然反应器，其真菌和细菌可分泌多种木质纤维素降解酶，在木质纤维素生产生物燃料和化学用品方面具有潜在的价值。因此，本研究在瘤胃内木质纤维降解的微生物及其降解木质纤维素相关酶的基础上，重点综述了瘤胃微生物在木质纤维素生物转化为乙醇、生物化学（有机酸）及沼气等方面的研究进展，旨在为瘤胃微生物和瘤胃酶在木质纤维素价值化利用方面的研究和应用提供新的方法和思路。     

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.     

轮状病毒感染肠上皮细胞激活宿主先天免疫研究进展

轮状病毒(RV)是引起婴幼儿、幼畜禽急性肠胃炎的人畜共患病原,常与其他病原体混合感染,多以呕吐,严重水样腹泻,脱水为临床症状,感染后具有较高病死率,对人类公共卫生以及养殖业造成极大危害。RV病原相关分子模式(PAMP)可被肠上皮细胞(IECs)中一组可遗传的模式识别受体(PRR)识别,通过IECs、先天免疫细胞与RV互作,激活细胞内信号级联,从而迅速诱导炎症和多种抗病毒基因表达。论文就轮状病毒特性、肠道先天免疫等方面进行综述,探讨RV感染宿主IECs后诱导不同抗病毒信号通路,为利用先天免疫途径预防轮状病毒感染提供了一定的参考。     

Identifying and Characterizing a Novel Peritrophic Matrix Protein (MdPM-17) Associated With Antibacterial Response From the Housefly,Musca domestica (Diptera: Muscidae)

Peritrophic matrix/membrane (PM) critically prevents the midgut of insects from external invasion by microbes. The proteins in the peritrophic membrane are its major structural components. Additionally, they determine the formation and function of this membrane. However, the role of PM proteins in immune regulation is unclear. Herein, we isolated a novel PM protein (MdPM-17) from Musca domestica larvae. Further, the function of MdPM-17 in regulating host innate immunity was identified. Results showed that the cDNA of MdPM-17 full is 635 bp in length. Moreover, it consists of a 477-bp open reading frame encoding 158 amino acid residues. These amino acid residues are composed of two Chitin-binding type-2 domain (ChtBD2) and 19 amino acids as a signal peptide. Moreover, tissue distribution analysis indicates that MdPM-17 was enriched expressed in midgut, and moderate levels in the fat body, foregut, and malpighian tubule. Notably, MdPM-17 recombinant protein showed high chitin-binding capacity, thus belongs to the Class III PM protein group. MdPM-17 protein silencing via RNA interference resulted in the expression of antimicrobial peptide (defensin, cecropins, and diptericin) genes, and this occurred after oral inoculation with exogenous microbes Escherichia coli (Enterobacteriales:Enterobacteriaceae), Staphylococcus aureus (Bacillales:Staphylococcaceae), and Candida albicans (Endomycetales:Saccharomycetaceae)). Therefore, all the antimicrobial peptide (AMP) gene expression levels are high in MdPM-17-depleted larvae during microbial infection compared to controls. Consequently, these findings indicate that MdPM-17 protein is associated with the antibacterial response from the housefly.     

秸秆复合有机酿热物对大棚土壤环境的影响

为解决黑龙江省早春大棚土壤温度低及设施土壤环境恶化问题,以‘千禧’番茄为材料,研究秸秆+牛粪(NGH)、秸秆+马粪(MGH)、秸秆+羊粪(YGH)、单一秸秆(JG),以未进行反应堆技术为对照(CK),对早春大棚‘千禧’番茄土壤温度、土壤理化性状、酶活性及微生物群落结构的影响。结果表明,与对照相比,各处理降低了土壤pH,提高了土壤温度、土壤EC、碱解氮、速效钾、有机质含量及土壤蔗糖酶、脲酶、磷酸酶、过氧化氢酶活性。经过秸秆生物反应堆处理的20 cm土层温度有明显的提升,其中秸秆+羊粪处理在反应启动后提升土壤温度效果最好;秸秆+羊粪(YGH)处理提高了土壤速效磷含量,是对照的2倍;秸秆+羊粪(YGH)处理土壤中4种酶活性均处于最高水平,分别比对照提高了91.9%、220%、18.5%、7.3%。各处理微生物多样性指数均显著高于对照,变化规律一致为秸秆+羊粪(YGH)>秸秆+牛粪(NGH)>秸秆+马粪(MGH)>秸秆(JG)>对照(CK);秸秆+羊粪(YGH)及秸秆+牛粪(NGH)处理对糖类、氨基酸类、酯类、醇类、胺类、酸类6类碳源的利用能力最强,显著高于其他处理和对照。应用主成分分析和聚类分析方法将大棚番茄土壤分为4个等级,秸秆+羊粪(YGH)处理为第一级,秸秆+牛粪(NGH)处理为第二级,秸秆+马粪(MGH)及单一秸秆(JG)处理为第三级,对照(CK)为第四级。应用秸秆复合有机酿热物生物反应堆促进了土壤环境的改善,以秸秆+羊粪(YGH)作为复合有机酿热物效果最佳。     

巨菌草对七彩山鸡生长性能、免疫器官以及肠绒毛形态的影响

试验旨在探究日粮中添加巨菌草(Pennisetum giganteum)对七彩山鸡(Phasianus colchicus)生长性能、免疫器官以及肠绒毛形态的影响。试验选取1周龄健康的七彩山鸡(母)210只,随机分为1个对照组(0%组)和4个饲料处理组,每组3个平行。4个饲料处理组配制时,分别添加4%、8%、12%、16%的巨菌草添加剂于基础饲料中。结果表明,与0%组相比,12%组七彩山鸡的平均体重和平均日采食量显著增加(P<0.05);4%、8%、12%组平均日增重显著大于16%组(P<0.05);8%组料重比显著降低(P<0.05);饲料处理组免疫器官指数中肝脏、脾脏指数均在0%组的基础上有所增加,但差异不显著(P>0.05);8%的巨菌草添加剂可显著增加七彩山鸡肠道的绒毛长度(P<0.05),隐窝深度显著降低(P<0.05),扩大肠道黏膜吸收面积。说明日粮中添加巨菌草可以提高七彩山鸡肠道对营养的吸收能力,一定程度上改善七彩山鸡生长性能和免疫性能。     

船舶噪声声压级对大黄鱼幼鱼游泳、摄食行为及免疫生理指标的影响

通过录制大黄鱼(Larimichthys crocea)产卵场附近船舶航行时的噪声,并以此为刺激源,以大黄鱼幼鱼为实验对象,研究了船舶噪声声压级对大黄鱼幼鱼游泳、摄食行为及免疫生理指标的影响。研究发现,当噪声声压级<60 dB时,幼鱼趋避游泳行为不强烈;但随着声压级增大,开始呈现出不同强度的趋避行为,依次表现出:游泳速度加快、鱼与鱼之间及鱼与桶壁之间发生碰撞、瞬间反应无序、跳跃等行为;当声压级>200 dB时,刺激2 min后就出现了死亡个体。在120 dB和150 dB短期单次和多次刺激下,幼鱼血浆中的皮质醇、血糖、血红蛋白和乳酸这4个与应激相关的生理指标均显著上升,其中皮质醇、血糖和乳酸上升幅度尤为明显。另外,皮质醇单次刺激后即达到峰值,而多次刺激后反而较单次刺激有所下降;血糖、血红蛋白和乳酸则具有累加效益,多次刺激要高于单次刺激。在120 dB长期(30 d)刺激下,幼鱼生长明显减缓,血浆中部分免疫指标(免疫球蛋白M,干扰素-α,白介素-1β和肿瘤坏死因子-α)明显降低,肠道菌群也发生显著变化,突出表现为部分益生菌如芽孢杆菌、乳杆菌等相对丰度明显降低。摄食行为影响方面,研究发现幼鱼能准确识别噪声源的位置,并具有一定的记忆性。研究结果揭示了船舶噪声对大黄鱼幼鱼的危害,可为今后制定大黄鱼产卵场的保护措施提供数据支撑。     

牦牛瘤胃微生物抗生素抗性基因对3种外源性刺激因子的响应

通过给牦牛投喂硫酸头孢喹肟(CEF)、盐酸二氟沙星(DIF)和黄曲霉毒素B1(AFB1),并进行瘤胃微生物宏基因组测序,旨在揭示这3种外源性刺激因子对抗生素抗性基因(ARGs)种类、抗性类型、抗性机制等的影响,对于深入研究微生物抗性组特征和抗性机制具有重要价值。选取15头牦牛,随机分5组。Cef组和Dif组分别根据说明书推荐剂量按体重计算、灌服CEF 1 mg·kg^-1和DIF 1 mL·kg^-1;E1组和E2组分别按采食量投喂AFB120、60μg·kg^-1;C组为对照组。处理7 d后,采集瘤胃液,提取DNA,Illumina HiSeq测序,对reads counts进行标准化得到TPM值,并进行方差分析。结果显示,对照组共获得132种ARGs,分属30种抗性类型,其中,四环素类tetQ和tetW基因丰度较高;Cef组tetW基因丰度增加(P<0.05),Dif组tetQ丰度增加(P<0.05);Cef组四环素类和头孢菌素类抗性基因丰度增加(P<0.05),Dif组四环素类和氨基香豆素类抗性基因丰度增加(P<0.05),E1组氨基香豆素和青霉烯类抗性基因丰度增加(P<0.05),E2组青霉烯类、头孢菌素类等9类抗性基因丰度均增多(P<0.05);Dif组Erm基因23S核糖体RNA甲基转移酶丰度增加(P<0.05),E2组中ATP结合盒超家族等3种抗性机制相关基因的丰度增加(P<0.05);3种因子均显著增加四环素类ARGs宿主的种类。结论:瘤胃是蕴含丰富ARGs的储藏库,其中,四环素类抗生素抗性基因tetQ和tetW是主要的ARGs。不仅CEF和DIF使部分ARGs的种类、抗性类型以及耐药机制相关酶等的丰度升高,增加瘤胃微生物的耐药性,而且AFB1也具有类似作用,且高剂量AFB1对抗性类型的影响范围较抗生素大。这3种因子还导致携带四环素类ARGs宿主微生物的种类数量增加,从而强化横向转移机制,加快ARGs传播,增强微生物对四环素类的耐药性。     

Seaweed polysaccharide mitigates intestinal barrier dysfunction induced by enterotoxigenic Escherichia coli through NF-κB pathway suppression in porcine intestinal epithelial cells

This study aimed to investigate the protective effects and underlying mechanism of seaweed polysaccharide (SWP) on intestinal epithelial barrier dysfunction induced by E. coli in an IPEC-J2 model. A preliminary study was done to screen optimum SWP concentrations by cell viability, cytotoxicity, apoptosis and proliferation evaluation. The regular study was conducted to evaluate the protective effects of SWP against E. coli challenge via the analysis of transepithelial electrical resistance (TEER), tight junction proteins, NF-κB signalling pathway, proinflammatory cytokines and the E. coli adhesion and invasion. Our results show that 4 h E. coli challenge down-regulated tight junction proteins expression, decreased TEER, activated NF-κB signalling pathway and increased proinflammatory response, which indicates that the E. coli infection model was well-established. Pre-treatment with 240 μg/ml SWP for 24 h alleviated the 4 h E. coli -induced intestinal epithelial barrier dysfunction, as evidenced by the up-regulated expression of Occludin, Claudin-1 and ZO-1 at both mRNA and protein level and the increased TEER of IPEC-J2 cells. Pre-incubation with 240 μg/ml SWP for 24 h inhibited the activation of the NF-κB signalling pathway by 4 h E. coli challenge, including the decreased mRNA expression of TLR-4, MyD88, IκBα, p-65, as well as the reduced ratio of protein expression of p-p65/p65. Also, pre-treatment with 240 μg/ml SWP for 24 h decreased proinflammatory response (IL-6 and TNF-α) induced by 4 h E. coli challenge and decreased the E. coli adhesion and invasion. In conclusion, SWP mitigated intestinal barrier dysfunction caused by E. coli through NF-κB pathway in IPEC-J2 cells and 240 μg/ml SWP exhibited better effect. Our results also provide a fundamental basis for SWP in reducing post-weaning diarrhoea of weaned piglets, especially under E. coli -infected or in-feed antibiotic-free conditions.