豆腐渣为什么不能直接喂奶牛

1豆腐渣中含有外源凝集素 外源凝集素又称植物性血细胞凝集素，是植物合成的一类对红细胞有凝聚作用的糖蛋白，可专一性结合碳水化合物。当外源凝集素结合牛肠道上皮细胞内的碳水化合物时，可造成消化道对营养成分吸收能力的下降。外源凝集素广泛存在于800多种植物（主要是豆科植物）的种子和荚果类中，如大豆、菜豆、刀豆、豌豆、小扁豆、蚕豆和花生等。     

半乳糖凝集素-3的结构特征及对糖脂代谢调控研究进展

半乳糖凝集素-3(Galectin-3)是半乳糖凝集素家族(Galectins)的核心成员之一,具有多种生物学功能,如调节炎性因子表达、细胞增殖、分化、凋亡、黏附及mRNA剪接等。研究表明,Galectin-3对葡萄糖代谢和脂肪代谢具有重要的调节作用。但关于Galectin-3的作用方式和分子机制却有不同的研究报道。论文综述了Galectin-3的结构特征及其调控糖脂代谢的作用和分子机制,以期为肥胖、糖尿病等代谢性疾病的防治提供参考。     

鸡甘露糖结合凝集素研究进展

鸡甘露糖结合凝集素是天然免疫防御系统中一种重要的免疫因子,具有识别病原微生物、介导调理吞噬、激活补体等功能。研究发现,鸡体内甘露糖结合凝集素的水平变化与疾病的易感性相关,表明甘露糖结合凝集素在抗病育种方面具有重要的研究价值。本文对鸡甘露糖结合凝集素的分子结构、功能、遗传特性及其与疾病的相关性进行了系统的分析和阐述。     

鸡甘露糖结合凝集素的研究进展

甘露糖结合凝集素（mannan-binding lectin，MBL）又称甘露糖结合蛋白（mannam-bindng protein．MBP），是一种广泛存在于人和动物体内的胶凝素（collagen）．属C型凝集素（Ca2＋依赖型）超家族。MBL由肝细胞产生并分泌至血液中．能特异性地与多种细菌、病毒、真菌以及恶性细胞表面具有的甘露糖、N-乙酰甘露糖胺、N-乙酰葡糖胺糖类结构结合。     

马铃薯凝集素的凝集作用及其影响因素

凝集素(STA)是生命体内广泛分布的一种天然的非免疫性蛋白或糖蛋白，具有众多的生物活性，在农业、生物技术、医学等领域有着广泛的应用前景。近10年来，对凝集素的研究发展较快，焦点集中在其生理生化功能方面。目前，研究最多的是豆科植物和禾本科植物的凝集素，茄目中茄科如马铃薯的凝集素、旋花科如甘薯的凝集素的研究，国内仅有少量的文     

凝集素在甲壳类动物免疫学方面的研究进展

凝集素属于一种糖蛋白或结合糖的模式识别分子蛋白,存在于植物、动物、微生物中,按物种来源可分为植物凝集素、动物凝集素、原生生物凝集素、细菌凝集素和病毒凝集素。甲壳类动物凝集素可以同时参与多项免疫反应,在维持甲壳类动物机体稳态、免疫防御以及免疫监视中发挥重要作用。本文基于凝集素的定义、分类及功能,介绍了甲壳类动物凝集素的两种主要类型——C型凝集素（C-type lectins,CTLs）和纤维蛋白原样结构域免疫凝集素（fibrinogen-like domain immunolectins,FBGLs）,旨在提升对甲壳类动物先天性免疫的认识水平,为甲壳类动物疾病防治提供新的思路和方法。     

猪甘露聚糖结合凝集素的研究进展

猪甘露聚糖结合凝集素作为猪机体重要的天然免疫因子,在抗感染机制中发挥重要的作用。本文对猪甘露聚糖结合凝集素的遗传特性,生物学作用及与疾病发生的相关性等几个方面的研究进行了概括总结。     

家蚕体液性防御因子—凝集素

为了维持生命和延续物种,家蚕在长期的生物进化过程中,逐渐形成了独特的防御体系.家蚕的防御功能主要包括体壁的防御功能、消化管的防御功能、细胞性的防御功能和体液性的防御功能.其中,体液性防御功能是通过抗菌蛋白、凝集素、溶菌酶、酚氧化酶系统及某些干扰素类物质等多种因子来实现的.凝集素作为家蚕识别外源物质的关键因子和免疫进化研究中的重要物质,被许多国内外学者所关注.本文主要就其基本概念、生理特性和作用机理等作一简述.     

捕食动物线虫性真菌凝集素的研究进展

凝集素是广泛存在于生物体内的一类糖蛋白，对生物体有着重要作用，近年来凝集素的研究取得了重要成果。笔者主要对捕食动物线虫性真菌凝集素的生物学特性、功能、作用机制及其在分子生物学方面的研究进展作了较详细的阐述。     

兔小肠组织大豆凝集素特异性结合蛋白分布的研究

本实验采用凝集素组织化学染色技术,以生物素标记的大豆凝集素为探针,研究了大豆凝集素特异性结合蛋白在兔的十二指肠,空肠,回肠的分布规律。结果表明大豆凝集素特异性结合位点主要分布在小肠上皮柱状细胞,杯状细胞和少量淋巴细胞上。兔肠道各部的分布规律呈如下趋势:各部阳性细胞类型主要为柱状上皮细胞,杯状细胞仅在空肠有着色;阳性区面积表现为:在空肠特别是空肠前段最深,十二指肠、回肠较浅。     

Recombinant galectins of male and female Haemonchus contortus do not hemagglutinate erythrocytes of their natural host

Recombinant galectins of female and male adult worms of Haemonchus contortus were expressed in Escherichia coli and their hemagglutinating activities to human and different animal erythrocytes were analyzed. The results showed that female and male galectins could be highly expressed in E. coli using a temperature-sensitive plasmid, with the recombinant protein being mainly appeared in inclusion bodies. Hemagglutinating activity assays showed that both of the galectins hemagglutinated human A, B, O type, dog, rabbit, chicken and mouse erythrocytes at the high concentration of 40 microg/well, but did not hemagglutinate erythrocytes of the natural host of H. contortus, the goat. Sugar inhibition assays confirmed that, out of eight sugars tested, only lactose was effective to inhibit agglutination of human type B erythrocytes by the recombinant galectins.     

The second glutamic acid in the C-terminal CRD affects the carbohydrate-binding properties of recombinant galectins of Haemonchus contortus

The effects of the second glutamic acid (E) in the C-terminal CRDs on the hemagglutination and lactose-binding characteristics of the recombinant galectins of nematode Haemonchus contortus were observed using two isoforms of recombinant galectins as models, and the sugar-binding abilities of the N-terminal and C-terminal CRDs of the galectins were also compared. The second E in the CRD, WGNEER, of Hco-GAL-m was mutated to glycine acid (G) and resulted in a recombinant galectin (MG mutate) with a CRD of WGNEGR, identical to that of Hco-GAL-f. The G in Hco-GAL-f CRD, WGNEGR, was mutated to E and produced a recombinant galectin (FE mutate) equal to that of Hco-GAL-m. At the same time, the CRDs of the N-terminal (FNh,MNh) and C-terminal (FCh,MCh) of Hco-GAL-f, Hco-GAL-m were amplified by PCR. The abilities of carbohydrate binding and hemagglutination of the four galectins and the four CRDs were analysed, respectively, by alpha-lactose-agarose affinity chromatography and hemagglutination assay. The results showed that Hco-GAL-m and FE mutate bound effectively to alpha-lactose-agarose compared to Hco-GAL-f and MG mutate, which almost could not bind to the conjugate column. The hemagglutinating abilities of the Hco-GAL-m and FE mutate to human B type red blood cells were similar and were nearly two times higher than that of the Hco-GAL-f and MG mutate. The hemagglutinating ability of the MCh was five times to that of the MNh and FNh and almost two times to that of the FCh. The binding ability of the MCh and FCh were significantly reduced compared to that of the Hco-GAL-m and FE mutate, but still remained. As for the MNh and FNh, no elution peak was observed in the lactose-agarose affinity chromatography. These results suggested that the second amino acid E in the C-terminal CRD motif of H. contortus galectin was involved in carbohydrate binding and hemagglutination, and C-terminal CRDs had stronger carbohydrate ability than N-terminal CRDs.     

Galectin secretion and binding to adult Fasciola hepatica during chronic liver fluke infection of sheep

Galectins are increasingly recognised as important mediators of immune homeostasis and disease regulation, but comparatively little is known about their role in parasite infection. This study investigates the interaction between two ovine galectins, galectin-11 and galectin-14, and the parasitic liver fluke, F. hepatica. Galectin-14 was found in eosinophils infiltrating the tissue surrounding infected bile ducts and secreted in the connective tissue, while galectin-11 was specifically induced in epithelial cells of bile ducts from infected sheep. Strong nuclear staining was observed for galectin-11. Both galectins were found to be secreted into the bile fluid of parasite infected sheep, and were also detected in the excretory/secretory products of adult flukes, following their removal from the ovine host. Recombinant galectin-14, but not recombinant galectin-11, was found to bind specifically to the surface tegument of adult flukes in a carbohydrate dependent manner. This study shows for the first time that both galectin-14 and galectin-11 are produced in liver tissue after chronic liver fluke infection and that they can directly interact with the parasite in the bile ducts. Galectin-11 may also be involved in epithelial cell turnover and cancerogenesis.     

Cells, cytokines and other molecules associated with rejection of gastrointestinal nematode parasites

Infections with gastrointestinal nematodes represent a major problem for human health and animal health and production. The physical size of the parasite, its changing life-cycle stages and the relative inaccessibility to host cells pose unique challenges to the immune system, which has evolved specialized strategies for parasite control. This paper reviews the work performed in the authors' laboratories to identify components that are involved in the natural rejection response against ruminant gastrointestinal nematode parasites, in particular Haemonchus contortus in sheep. The results of these studies indicate that stage-specific antibodies act in concert with effector cells, in particular globular leukocytes (intraepithelial mast cells) and eosinophils, appropriately activated/primed by type 2 (T2) cytokines, to initiate different mechanisms of parasite expulsion and killing. In addition, other molecules, in particular carbohydrate binding galectins, may be involved in strengthening the final effector phase of the rejection response.     

Single nucleotide polymorphisms in collagenous lectins and other innate immune genes in pigs with common infectious diseases

Innate immune recognition of pathogens involves various surface receptors and soluble proteins that precede agglutination, complement activation, phagocytosis, and the adaptive immune response. Mannan-binding lectins (MBLs), ficolins (FCNs) and surfactant protein A (SP-A) are soluble collagenous lectins that bind surface structures of various bacteria, viruses and fungi. Some single nucleotide polymorphisms (SNPs) in collagenous lectin genes of humans and other species, including pigs, have been implicated in variation in susceptibility to infectious and inflammatory diseases. In this study we determined the frequencies of 13 SNP alleles of MBL-A, MBL-C, ficolin-α, ficolin-β, and SP-A in 1324 healthy pigs and 461 pigs diagnosed with common infectious diseases at necropsy. For comparison, we also analyzed 12 other SNP alleles in several other innate immune genes, including galectins and TLRs. Several SNPs within genes encoding porcine MBL-A, MBL-C and SP-A were more frequent in pigs diagnosed at necropsy with various diseases or pathogens. These findings suggest that several collagenous lectin SNPs are associated with disease susceptibility and therefore might be genetic markers of impaired innate immune function.     

Characterization of a galectin-like activity from the parasitic nematode, Haemonchus contortus, which modulates ovine eosinophil migration in vitro

The development of eosinophilia is a characteristic feature of helminth infection, although the exact nature of the interaction between eosinophils and parasites remains to be fully defined. Previously, it has been reported that Haemonchus contortus and other nematodes produce eosinophil-specific chemoattractants. This paper describes studies aimed at isolating and identifying the factor(s) responsible. Initial studies showed that soluble extracts of infective larvae (L3) of H. contortus provoked a chemokinetic, rather than chemotactic, response in ovine bone marrow eosinophils in vitro. This activity was inhibited by lactose to a markedly greater extent than sucrose suggesting a galectin-like identity. Lactose affinity chromatography of soluble H. contortus extracts resulted in the isolation a specific bound fraction which retained biological activity. SDS-PAGE gel electrophoresis indicated a single Coomassie-stained band at between 31 and 41kDa. Subsequent, mass spectrometric analysis confirmed that the bound fraction contained a mixture of nematode galectins. The results confirm that H. contortus larvae produce several galectin-like proteins, at least one of which demonstrates eosinophil chemokinetic activity in vitro. The possibility of the parasite-derived factor mimicking the mammalian galectin-9, a known eosinophil chemokine, is discussed.     

中国建立“冷冻动物园”浅析

生物多样性保护和野生动物保护是目前人类普遍关注的问题。野生动物多样性保护有多种形式,＂冷冻动物园＂是其中的一个重要手段。该手段具有现代化、高容量等优点。目前已有多个国家建立了＂冷冻动物园＂。中国物种资源丰富,有许多特有物种,但很多物种已经濒临灭绝。本文根据我国动物资源的现状,针对建立＂冷冻动物园＂所需的技术条件、物质资源等方面进行了分析,提出了建立国家级的＂冷冻动物园＂的必要性和可行性。     

青海省禾本科优良牧草种质资源

位于青藏高原的青海天然草地,是世界上高寒类牧草的种质资源库。天然草地上野生牧草的优良品质,如抗寒、抗旱等抗逆基因和特殊种性是在世界其他地区所无法寻觅的,也是弥足珍贵的种质资源。据2007年调查统计,青海省有禾本科植物59属257种32个亚种及变种,并且已经有不少引进种和栽培种,已成为高寒牧区适宜种植的当家品种。因此,保护青海天然草地上极具挖掘潜力的牧草种质资源,深入研究和合理开发利用牧草资源是十分必要的。     

牛奶风味影响因素的研究进展

牛奶风味的影响因素包括多个方面,其主要取决于复杂的风味活性物质。一些风味活性物质直接来源于奶牛的饲料成分,但有些风味活性物质的来源还不确定。介于风味活性物质的复杂性,一些相关的信息较少,主要有两个假设,一是来源于动物所采食的饲料成分,一是消化产物的衍生物。     

RAPD技术及其在动物医学中的应用

RAPD技术即随机扩增多态性DNA技术，是一种建立在PCR基础上的新的DNA多态性检测技术，其主要特点是利用随机寡核苷酸引物扩增基因组DNA片段，通过凝胶电泳分析其指纹图谱特征。该技术具有快速灵敏，程序简便等优点，现已经广泛应用于多个领域，此文综述了RAPD技术的原理、优缺点、影响因素及其在动物医学中的应用。