糖蛋白及其在动物精卵识别中的作用

糖蛋白是指由比较短 ,往往带分支的寡糖与多肽链共价连接而成的一类结合蛋白质。其中 ,糖部分所占比例较小。糖蛋白作为生物体内重要的生物大分子 ,其种类繁多 ,并且以各种形式广泛存在于细胞膜、细胞间质、血浆以及粘液中 ,具有开关、调谐、作为激素、胞内转运、保护、促进物质吸收、参与血液凝固、参与细胞识别等多方面的重要生理活性。1糖蛋白的组成糖蛋白分子是由多肽链和糖两部分组成的 ,糖和多肽链之间通过糖苷键相连接。其中的蛋白质是生理功能的主要担负者 ,糖链起到维持蛋白质结构稳定 ,抵抗蛋白酶水解 ,防止抗体识别及参与多肽链…     

运用酶法降解褐藻胶研究糖链序列结构的展望

多糖是一种生命的基础物质 ,其功能和作用日益受到重视 ,糖生物学与糖工程的研究必将成为基因工程、蛋白质工程及糖链结构分析技术之后新的研究热点。探讨多糖的研究方法、解决糖链的测序问题成为该研究领域的关键。褐藻胶是一种重要的海藻工业产品 ,是由古罗糖醛酸 (G)和甘露糖醛酸 (M)组成的一种典型的多糖类 ,广泛应用于工业、农业、医药、食品等各个领域。研究发现 ,不同的褐藻酸酶可以作用于褐藻酸的不同位点 ,形成不同的糖片段或寡糖 ,经过分离、纯化 ,应用电泳、色谱、质谱、核磁共振等方法可以确定糖链的结构、组成及取代基的位置…     

外源凝集素──水产动物御敌的有力兵器

外源凝集素是非免疫起源的热敏蛋白质或糖蛋白，由于其多价构型及对持定细胞多糖具结合亲和力，它们选择凝集某些细胞（包括脊椎动物血球及一些病原微生物）和沉淀某些复杂碳水化合物；其凝集活动常被单糖所抑制，有的却需某些二糖、三糖或多糖。外源凝集素分离自广泛的低等和较高等的生物。一些地区水产养殖业受挫，因素较多，但对发病机理认识之缺乏和调动养殖对象本身防病积极性之不足，是其重要原因。外源凝集素可在诸如凝集外来细胞，调理作用等的防御活动中扮演识别因子，协助一些生理活性物发挥作用，参与吞噬、胞囊、凝固、止血及创伤修复等作用。在生物学、细胞学、生物化学、医学和食品科技上有广泛用途。迄今外源凝集素的许多性能并未全清，在自然界中的精细生理作用仍是个谜。本文论述外源凝集素的定义、性能及用途，以提请有关人士重视。     

糖类化合物的化学修饰及其生物活性的研究进展

糖类物质是自然界存在的一大类具有广谱化学结构和生物学功能的有机化合物 ,在体内具有重要的和复杂的生理作用和生理活性。研究发现 ,许多糖类化合物本身具有抗菌、抗病毒、抗肿瘤活性 ,但由于其在治疗疾病的同时也会给身体带来毒副作用 ,因而限制了其作为药物的应用。对糖及其衍生物进行化学修饰可以提高生物活性 ,降低毒副作用 ,因此引起了高度重视。海洋生物如各种藻类和甲壳动物等是糖类及其衍生物的重要来源。长期以来 ,我国对海洋糖类化合物的研究还只停留在提取分离技术和简单的分子修饰上 ,一些具有活性的混合提取物和非单一多糖及…     

甲壳纲动物凝集素的结构特征和分离纯化方法

凝集素(Lectin)是指所有非免疫原的能凝集细胞或沉淀含糖大分子的蛋白质或糖蛋白,一般具有糖结合专一性,能与糖蛋白或糖脂分子中的糖相结合。早在1888年,俄国的Herman发现蓖麻籽的蛋白质提取物能凝集血红细胞,从而开始了凝集素的研究。目前人们分离纯化的凝集素已经超过了1 000     

无机氮和磷对海带配子体生长发育的影响

氮(N)是蛋白质和核酸等重要有机物的成份。磷（P）是核酸等重要有机物的成份。它们在细胞代谢中发生重要的作用。海带或其他生物在代谢过程中都必须有一定数量的氮和磷的供应，才能正常地生长和发育。Drew(1910)的实验指出，在天然海水中加入一些无机盐的氮和磷可以促进糖海带配子体的生长，     

P糖蛋白及其在水生生物多型异源物质抗性中的研究进展

多型异源物质抗性机制(multixenobiotic resistance mechanism,MXR)是在水生生物中广泛存在的1种对外源毒性物质的重要防御机制,其分子基础与哺乳动物细胞系的多药抗性机制非常相似,ABC(ATP binding cassette,ABC)转运蛋白超家族中的P糖蛋白(p-glycoprotein,P-gp)参与并介导了该抗性机制。本文从P糖蛋白活性和组织分布,P糖蛋白的诱导和抑制,P糖蛋白的表达和调控,多型异源物质抗性机制中P糖蛋白的可能作用模式等几个方面综述了异源物质存在条件下水生生物多型异源物质抗性机制中P糖蛋白的研究现状。大量研究表明,多型异源物质抗性机制是水生生物体的一个重要细胞防御机制。P糖蛋白作为能量依赖性的外排泵,通过水解ATP或与ATP结合将广谱的异源物质(如毒素、重金属、有机污染物等)泵出胞外或促进异源物质在特定的细胞或细胞器内滞留或隔离,从而防止异源物质与细胞内的靶分子结合,降低异源物质对细胞造成的伤害,提高生物体的抗性和耐受性。     

鹅颈藤壶多糖提取、理化性质及N-糖链表达谱分析研究

本文以南海海域鹅颈藤壶(Lepas anatifera)为原料,提取鹅颈藤壶背甲与肌肉质柄中的多糖,基于其基本理化性质的分析,比较不同生长时期鹅颈藤壶N-糖链表达谱的差异性。经过脱脂、碱水解/蛋白酶解、乙醇沉淀方法提取得到粗多糖;利用高效液相色谱法、高效凝胶渗透色谱法、苯酚-硫酸法、考马斯亮蓝法对其单糖组成、分子量分布、总糖含量及蛋白质含量进行分析;采用液质分析(PGC-ESI-MS/MS)方法对鹅颈藤壶成体(A-GB)与幼体(L-GB)肌肉质柄中N-糖链进行分析并比较。表明肌肉质柄中多糖分子量为18.40 kDa;总糖含量为11.99%,蛋白质含量60.14%,富含甘露糖、葡萄糖、氨基半乳糖,其中甘露糖的含量高达80%以上。在鹅颈藤壶成体与幼体中均鉴定得到26条N-糖链,成体中高甘露糖型N-糖链占总糖链的20.81%,且相对丰度较高的糖型组成为F₁H₃N₂(39.06%)、F₁H₃N₃(24.44%)、H₃N₃...     

细菌膜囊泡在海洋生态系统中的研究现状及展望

膜囊泡是一类由细菌释放并携带复杂蛋白质、核酸、信号分子等重要信息物质的生物纳米颗粒,参与了水平基因转移、群体感应、生物膜形成等多种生理生化活动.海洋中的细胞膜囊泡可能是除噬菌体和细菌之外的第三大生物实体,其介导的跨越物种的细胞间通讯对海洋生态系统而言有重要意义.然而,我们对膜囊泡在海洋生物圈中具体的生态角色与生物功能所...     

无机氮和磷对海带配子体生长发育的影响

氮(N)是蛋白质和核酸等重要有机物的成份。磷(P)是核酸等重要有机物的成份。它们在细胞代谢中发生重要的作用。海带或其他生物在代谢过程中都必须有一定数量的氮和磷的供应,才能正常地生长和发育。Drew(1910)的实验指出,在天然海水中加入一些无机盐的氮和磷可以促进糖海带配子体的生长。Harries(1932)的实验指出:磷促进海带配子体的细胞分裂。当磷的含量超过氮时,配子体会生长成为多细胞分枝体,结果不能发育为孢子体,当氮的含量过多时,配子体的生长延缓,发育推迟。木下     

几种海藻功能寡糖的结构、制备、活性与应用研究进展

海洋来源的功能寡糖具有多种生物活性,如抗炎、抗氧化、抗病毒、抗肿瘤和免疫调节等,因此在医药、农业、化工及环境等领域有着广泛的应用.然而,不同聚合度、不同结构的寡糖所具有的活性差异很大,因此有必要深入研究和探讨不同种类的海洋功能寡糖的结构与功能的关系及其应用潜力.本文对几种研究较多的海藻功能寡糖的来源、制备、纯化及应用进...     

低分子质量褐藻寡糖的高效酶法制备及其抗氧化活性评价

褐藻寡糖具有多种生理活性,本研究通过酶解与分级条件的优化,获得了低分子质量褐藻寡糖的酶法制备工艺,并在体外模型上评价了不同分子质量组分的抗氧化活性。结果表明,优化后的褐藻寡糖制备条件为:底物浓度1.20%,酶底比4.35 U/mg,酶解时间4 h。进一步采用乙醇沉淀和超滤分离后,获得了重均分子质量分别为0.84、1.40、2.25和34.56 k Da的4种组分,其得率分别为50.82%、5.15%、11.48%和12.00%。各组分均具有一定的还原能力,可有效清除DPPH和羟自由基,其中低分子质量组分A的抗氧化活性最为显著,其清除羟自由基的能力与维生素C相近。     

辽河口沉积物中参与主要生物地化循环的微生物功能基因分析

辽河口区域丰富的生物多样性在生物地球化学循环和维持生态系统功能等方面发挥着极其重要的作用.研究辽河口表层沉积物中参与常见地球化学循环的功能基因及其关键影响因子,对揭示和预测辽河口沉积物微生物的功能代谢潜力和受环境变化的影响具有重要意义.应用功能基因芯片(GeoChip 4.0)技术开展微生物功能基因多样性研究.结果 表...     

The role of biocrusts in nitrogen cycling on the tropical reef islands,South China Sea

Harboring polyextremotolerant microbial topsoil communities, biological soil crusts(biocrusts) occur across various climatic zones, and have been well studied in the terrestrial drylands. However, little is known about the functional metabolic potential of microbial communities involved in the biogeochemical processes during the early succession of biocrusts on the tropical reef islands. We collected 26 biocrusts and bare soil samples from the Xisha Islands and Nansha Islands, and applied a functional gene array(GeoChip 5.0) to reveal nitrogen(N)cycling processes involved in these samples. Both physicochemical measurement and enzyme activity assay were utilized to characterize the soil properties. Results revealed the composition of N-cycling functional genes in biocrusts was distinct from that in bare soil. Additionally, microorganisms in biocrusts showed lower functional potential related to ammonification, denitrification, N assimilation, nitrification, N fixation, and dissimilatory nitrate reduction to ammonium compared to bare soils. Although the abundance of nifH gene was lower in biocrusts, nitrogenase activity was significantly higher compared to that in bare soils. Precipitation, soil physicochemical properties(i.e., soil available copper, soil ammonia N and pH) and soil biological properties(i.e., β-glucosidase, fluorescein diacetate hydrolase, alkaline protease, urease, alkaline phosphatase, catalase and chlorophyll a) correlated to the N-cycling functional genes structure. Nitrate N and ammonia N were more abundant in biocrusts than bare soil, while pH value was higher in bare soil. Our results suggested biocrusts play an important role in N-cycling in coral sand soil, and will be helpful in understanding the development and ecological functions of biocrusts on tropical reef islands.     

无乳链球菌(Streptococcus agalactiae) 荚膜多糖合成基因研究进展

无乳链球菌是一种人畜鱼共患的重要病原菌,菌体表面的荚膜多糖是公认的毒力因子,其合成过程受荚膜多糖合成基因的调控.荚膜多糖合成基因存在于荚膜多糖操纵子中,参与无乳链球菌荚膜多糖的合成启动、寡糖和多糖的聚合以及外输并锚定于菌体表面,在新型诊断技术和减毒突变株的构建方面取得良好的应用.本文首次就cps基因的基本属性、转录调节、编码蛋白及其生物功能、对荚膜多糖合成的调控机理、在血清分型和突变株构建的应用这六个方面进行深入分析和讨论,以期为GBS cps基因的新功能研究和创新应用提供理论参考.     

The Epibiotic and Endolithic Species Associated with the Gastropod Shells inhabited by the Hermit Crabs Paguristes Oculatus and Pagurus Cuanensis

Abstract. Over 120 species, including epizoites, endolithic organisms, and an epiflora are associated with the gastropod shells inhabited by the hermit crabs Paguristes oculatus and Pagurus cuanensis in the North Adriatic Sea (Gulf of Trieste). The symbiotic organisms include members of three trophic levels - primary producers (rhodophytes), primary consumers (active and passive filter feeders), and secondary consumers (carnivorous species). Many of the invertebrates show a preferred distribution on the shells. The shells are a mobile substratum for a specific community. They are a sediment- and predator-free surface, and for their size are extremely stable substrates in terms of both time and orientation.
The hermit crab microbiocoenosis is a dynamic phenomenon that can be studied as a functional unit. The symbionts are responsible for two simultaneous processes - a constructive and a destructive process on the shells. Shell deterioration is due primarily to biological processes, not to mechanical destruction. The more frequently occurring species were classified according to their role in reinforcing or weakening shell structure. These developments are related to hermit crab activity. Epizoites grow through several shell changes by hermit crabs, and a number of forms are capable of surviving the final deposition of the shells.     

Effects of coastal orientation and depth on the distribution of subtidal benthic assemblages

A better understanding of biological systems can only be gained if we understand what processes are important and how they operate to determine the distribution of organisms. Coastal orientation and depth can influence environmental conditions, including the degree of water motion and availability of light, which in turn may influence the horizontal and vertical patterns of organism distribution. Here, we used a mixed‐model design to examine the effects of coastal orientation and depth on the structure of benthic assemblages by comparing the abundance and distribution of macroalgae and invertebrates in shallow and deep waters on the opposing coasts of São Miguel. Generally, coastal orientation had little influence on the distribution of most taxa. In contrast, significant differences were generally associated with depth, although patterns were spatially variable at the scale of locations. This study suggests that depth, and processes operating at the scale of location, but not at the scale of the coast, have an important influence on these assemblages, and that failure to recognise such a scale of variability may hamper our ability to better understand the processes that structure these communities.     

SCOPIX: A new X-ray imaging system for core analysis

SCOPIX is a new digital X-ray imaging system for core analysis that uses an X-ray source coupled to a high-energy brightness amplifier and a CCD camera. SCOPIX’s numerical files are images in 256 gray levels equal in value to X-ray densities. Possible data processing approaches include: core logging using grayscale profiles to define the characteristics of sedimentary sequences and image processing to define and quantify lithologic facies and the geometry of physical and biological structures. Applications are: recognition of facies and sedimentary processes, study of sedimentary rhythms and geological cycles, and study of biological and geochemical processes.