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.     

Marine-Derived Chitosan Nanoparticles Improved the Intestinal Histo-Morphometrical Features in Association with the Health and Immune Response of Grey Mullet (Liza ramada)

Marine-derived substances are known for their beneficial influences on aquatic animals’ performances and are recommended to improve intestinal health, immunity, and anti-oxidative status. The present study investigates the role of chitosan nanoparticles on the intestinal histo-morphometrical features in association with the health and immune response of Grey Mullet (Liza ramada). Chitosan nanoparticles are included in the diets at 0, 0.5, 1, and 2 g/kg and introduced to fish in a successive feeding trial for eight weeks. The final body weight (FBW), weight gain (WG), and specific growth rate (SGR) parameters are significantly increased while feed conversion ratio (FCR) decreases by chitosan nanoparticles compared to the control (p < 0.05). The morphometric analysis of the intestines reveals a significant improvement in villus height, villus width, and the number of goblet cells in chitosan-treated groups in a dose-dependent manner. Additionally, there is a positive correlation between the thickness of the enterocyte brush border and the chitosan dose, referring to an increasing absorptive activity. Histologically, the intestinal wall of Grey Mullet consists of four layers; mucosa, sub-mucosa, tunica muscularis (muscular layers), and serosa. The histological examination of the L. ramada intestine shows a normal histo-morphology. The epithelial layer of intestinal mucosa is thrown into elongated finger-like projections, the intestinal villi. The values of hemoglobin, hematocrit, red blood cells (RBCs), total protein (TP), albumin, and globulin are significantly increased in fish fed 1, and 2 g/kg of chitosan nanoparticles compared to fish fed 0 and 0.5 g/kg (p < 0.05). The highest levels of TP and albumin are observed in fish fed 1 g/kg diet (p < 0.05). The lysozyme activity and phagocytic index are significantly enhanced by feeding chitosan nanoparticles at 0.5, 1, and 2 g/kg, whereas the phagocytic activity is improved in fish fed 1 and 2 g/kg (p < 0.05). The highest lysozyme activity and phagocytic index are observed in fish fed 1 g/kg. SOD is significantly activated by feeding chitosan nanoparticles at 1 g/kg. Simultaneously, glutathione peroxidase (GPx) and catalase (CAT) activities also are enhanced by feeding chitosan at 1 and 2 g/kg, compared to fish fed 0 and 0.5 g/kg (p < 0.05). The highest GPx and CAT activities are observed in fish fed 1 g/kg (p < 0.05). Conversely, the malondialdehyde (MDA) levels are decreased by feeding chitosan at 1 and 2 g/kg, with the lowest being in fish fed 1 g/kg (p < 0.05). To summarize, the results elucidate that L. ramada fed dietary chitosan nanoparticles have a marked growth rate, immune response, and anti-oxidative response. These improvements are attributed to the potential role of chitosan nanoparticles in enhancing intestinal histo-morphometry and intestinal health. These results soundly support the possibility of using chitosan nanoparticles at 1–2 g/kg as a feasible functional supplement for aquatic animals.     

重庆地区草地贪夜蛾幼虫肠道真菌的分离鉴定

草地贪夜蛾(Spodoptera frugiperda)是一种洲际迁飞性农业害虫,食谱广泛. 2019年5月已迁飞至重庆地区,对农作物造成严重危害.为了解入侵重庆地区草地贪夜蛾(Spodoptera frugiperda)肠道真菌菌群的组成,本研究以采集自重庆巫山玉米田及重庆江津高粱田中的草地贪夜蛾幼虫为材料,运用传统培养方法分离其粪便中的肠道优势真菌,并对其进行形态学观察和分子生物学鉴定.实验通过分离培养不同地区、不同食物的草地贪夜蛾肠道真菌,结合形态学观察及rDNA ITS测序完成了属水平的鉴定,共分离得到了5个属10个真菌分离株,其中分离自重庆巫山玉米田的草地贪夜蛾肠道真菌归为3个属,分别为念珠菌属(Candida)、掷孢酵母属(Sporobolomyces)和帚枝霉属(Sarocladium);分离自重庆江津高粱田的草地贪夜蛾肠道真菌归为3个属,分别为念珠菌属(Candida)、莫氏黑粉菌属(Moesziomyces)和毛霉属(Mucor).初步分离获得入侵重庆地区的草地贪夜蛾肠道真菌,丰富了对入侵草地贪夜蛾肠道微生物的认识.     

北京鸭中脑脊髓通路的起源和细胞构筑：HRP逆行追踪法研究

在脊髓的颈中部、颈膨大部和腰膨大部单侧注射或包埋HRP(辣根过氧化物酶),逆行追踪了28例北京鸭,对中脑至脊髓的传导通路的起始部位、细胞构筑和机能进行了系统的研究。发现大量标记细胞分布在中脑对侧的红核,双测的Cajal中介核、中央灰质和动眼神经副交感核(即EW核)内。此外,还发现少量标记细胞分布在中脑中缝核和双侧的中脑外侧网状结构。而在顶盖内,没有任何部位出现标记细胞。研究结果表明,北京鸭除具有红核脊髓束外,还存在着Cajal中介核至脊髓的直接传导通路,EW核至脊髓的直接传导通路以及中缝核和网状结构至脊髓的直接传导通路,而不存在与哺乳类相似的顶盖脊髓束。     

壳聚糖饲用微生物制剂对湘黄鸡免疫指标和肠道菌群的影响

在不用药物、不接种疫苗的条件下,于饮水中添加0（CK）,0．5％,1．0％和1．5％的以壳聚糖为培养底物研制的壳聚糖饲用微生物制剂饲喂湘黄鸡,探讨其对湘黄鸡免疫指标和肠道菌群的影响效果．结果表明,试验组脾脏指数有上升趋势（Jp〈0．25）,法氏囊指数和胸腺指数显著提高（p〈0．05）;试验组血液中IgG含量呈上升趋势（P〈0．25）,T3,T4和IgA含量也显著提高（P〈0．05或（p〈0．01）;试验组盲肠中大肠杆菌显著减少,而乳酸杆菌显著增加（P〈0．01）．同时在日增重和育成率上,试验组提高率达9．31％（p〈0．01）和7．01％（p〈O．05）,表明该制剂通过促进免疫器官发育,增强T3,T4,IgA,IgG分泌和改善肠道微生态环境,从而提高试鸡的抗病力和生长性能．     

罗非鱼消化道5-HT内分泌细胞的免疫组织化学研究

用链霉亲和素-生物素化过氧化物酶复合物(Strept Avidin Biotion -peroxidase Complex SABC )免疫细胞化学方法,对罗非鱼消化道内分泌细胞进行了免疫组织化学定位.结果表明:5-羟色胺细胞在消化道各段都有分布,其中胃体部密度最大,其次是幽门和喷门处,后肠的密度最小.本文主要讨论了5-HT内分泌细胞在罗非鱼消化道免疫细胞化学定位,可为鱼类的内分泌学提供主要依据.     

卵形鲳鲹消化道的形态学、组织学和组织化学

采用形态解剖、组织学和组织化学方法,研究了卵形鲳鲹Trachinotus ovatus消化道结构的特点。结果表明：卵形鲳鲹口咽腔较小,上下唇有许多绒毛状突起;上下颌无齿,鳃耙内侧具有绒毛状细齿,口咽腔具有多种类型齿;食道粗短,内表面分布有许多较为宽大的黏膜褶;胃呈＂U＂形,盲囊部明显,贲门部和盲囊部具有丰富的胃小凹和胃腺;前、中、后肠黏膜褶丰富,后肠黏液细胞密度最大,肠长比为0.61;幽门盲囊细长,有25～35条。消化腺为肝胰脏。食道以Ⅰ型黏液细胞为主,贲门部以Ⅰ型和Ⅲ型黏液细胞为主,盲囊部、幽门部、前肠、中肠和幽门盲囊以Ⅲ型黏液细胞为主,后肠以Ⅱ型黏液细胞为主。     

复合微生态制剂对异育银鲫肠道菌群和消化机能的影响

为了研究复合微生态制剂对异育银鲫肠道菌群和消化机能的影响,在饲料中添加不同水平的酿酒酵母(0.04%、0.06%、0.08%)、嗜酸乳酸菌(0.01%、0.02%、0.03%)以及枯草芽孢杆菌(0.01%、0.03%、0.05%)3种益生菌制剂,采用L9(34)正交设计法配制成9种复合微生态制剂。结果表明,酿酒酵母对肠道乳酸菌和芽孢杆菌含量的影响达到极显著水平(P<0.01),枯草芽孢杆菌对肠道乳酸菌含量的影响达到显著水平(P<0.05)。3种益生菌对大肠杆菌和气单胞菌含量的影响均显著(P<0.05)。3种试验益生菌对异育银鲫前、中、后肠段的淀粉酶、脂肪酶及蛋白酶均有不同程度的影响,但差异不显著(P>0.05)。酿酒酵母对肠道消化酶和营养物质表观消化率的影响最大,对磷表观消化率影响的极显著(P<0.01),对干物质表观消化率影响显著(P<0.05)。酿酒酵母、嗜酸乳杆菌和枯草芽孢杆菌3菌种适当搭配可改善异育银鲫肠道微生态环境,有益于消化酶的分泌和饲料养分的消化,较优的组合为酿酒酵母0.08%、嗜酸乳杆菌0.03%、枯草芽孢杆菌0.01%。     

热应激环境下育成鸡肠道菌群多样性及黏膜结构的相关性分析

为分析热应激环境下育成鸡肠道菌群以及黏膜结构的变化,揭示热应激下家禽肠道中正常菌群定植与黏膜结构变化的相关性,选取健康状况相似的10周龄日照琅琊鸡96只,设适温对照组((24±1)℃,Ⅰ)和高温组((38±1)℃),随机分在2个人工环境气候舱中饲养,试验期为14d。采用16SrDNA PCR-DGGE技术,分析热应激处理后1d(Ⅱ)、7d(Ⅲ)和14d(Ⅳ)时十二指肠、空肠及回肠部位内容物细菌群落多样性以及组织黏膜形态变化、肠黏膜上皮内杯状细胞数量。结果表明:热应激持续时间越长,对回肠部位菌群影响越大,Ⅲ组十二指肠与回肠部位优势细菌菌群组成分离明显;Ⅳ组十二指肠、空肠与回肠部位优势细菌菌群组成具有明显差异。不同热应激时段在空肠部位可检测到罗伊氏乳杆菌(Lactobacillus reuteri)、螺旋链霉菌(Streptomyces spiralis)、Plebeius杆菌属细菌(Bacteroides plebeius strain)和嗜酸乳杆菌(L.acidophilus),而回肠部位可检测到拟杆菌属(Bacteroidetes)和不可培养的细菌等;Ⅲ组十二指肠、空肠和回肠的绒毛长度、宽度、隐窝深度及绒毛高度/隐窝深度(V/C)均发生了明显的变化,各肠段的绒毛长度均明显下降,其中回肠绒毛长度减少最为显著(P0.05);十二指肠、空肠隐窝深度及V/C均出现明显下降(P0.05),各肠段肠壁厚度均显著比对照组低(P0.05)。Ⅲ组空肠和回肠内杯状细胞的数量明显减少,其中回肠差异显著(P0.05)。结果显示,热应激对育成鸡各肠段细菌菌群组成的影响很大,并且黏膜组织结构发生了明显变化,从而破坏消化道菌群平衡,导致消化吸收功能严重受阻。