藻类对微量元素的生物富集及其应用

生物富集（bioenrichment）又04生物浓缩（bioconcentration）或生物积聚（bioacct－unulahon）,是指生物体从周围环境中蓄积某种元素或难分解的化合物,从而使该物质浓度超过环境中其浓度的现象,富集的程度可以用富集系数即生物体中某富集物浓度与环境中该物质浓度之比来表示［l］藻类对许多微量元素具有较强的生物富集能力,可作为生物吸附剂广泛应用于污水处理、水质净化［2.3］;稀有、贵重金属和放射性物质的回收［4］;痕量、超痕量元素分析［5.6］;高附加值生物的培养等方面［7~9］。利用藻类富集微量元素具有经济、高效、选择性…     

高必需氨基酸转基因马铃薯的研究

８０年代以来,马铃薯遗传转化系统日趋成熟,转基因工程植株已被广泛应用于基础科学研究［１］。作为食物蛋白和能量主要来源的马铃薯,提高其蛋白质含量及质量的遗传工程研究正受到人们的普遍关注［２］。Ｙａｎｇ等［２］将旨在改善氨基酸平衡的ＣＡＴ－ＨＥＡＡＥ（氯酶素乙酰转移酶－高含量人体必需氨基酸）融合基因导入马铃薯,获得了Ｓｏｕｔｈｅｒｎｂｌｏｔ、Ｎｏｒｔｈｅｒｎｂｌｏｔ、Ｗｅｓｔｅｒｎｂｌｏｔ的证据,但尚缺少氨基酸分析的资料。玉米醇溶蛋白（ｚｅｉｎ）［３］是一个富含甲硫氨酸的贮存蛋白,它和人工合成的ＨＥ…     

［B3－Lys］－胰岛素的研究：受体结合及生物活性

本文用１２５Ｔ－［Ｂ３－Ｌｙｓ］－胰岛素和１２５Ⅰ－胰岛素研究了［Ｂ３－Ｌｙｓ］－胰岛素和胰岛素与人胎盘细胞膜（ＨＰＭ）胰岛素受体结合特性并进行了比较。实验结果表明［Ｂ３－Ｌｙｓ］－胰岛素与ＥＰＭ胰岛素受体结合能力比天然猪胰岛素高。由竞争取代曲线得到的［Ｂ３－Ｌｙｓ］－胰岛素和猪胰岛素的ＩＣ（５０）值分别为０．６５和１．１１ｎｍｏｌ／Ｌ。经Ｓｃａｔｃｈａｒｄ分析得出［Ｂ３－Ｌｙｓ］－胰岛素与ＨＰＭ胰岛素受体中高亲和位点和低亲和位点结合的亲和常数分别为１．７２×１０９和２．２７×１０６Ｌ／ｍｏｌ,而猪胰岛素分别为１．２６×１０９和１．４７×１０６／ｍｏｌ。促脂肪细胞合成脂肪实验结果表明［Ｂ３－Ｌｙｓ］－胰岛素也同样具有比天然猪胰岛素更高的离体生物活力,ＥＣ（５０）分别为０．１７５和０．３０１ｎｍｏｌ／Ｌ。可见［Ｂ３－Ｌｙｓ］－胰岛素的受体结合能力和高体生物活力都为猪胰岛素的１．７倍。     

甜菜碱合成代谢基因工程的研究进展

甜菜碱（Betaine）是生物体内氨基酸代谢的中间产物［1］,可作为甲基供体,参与“一碳单位”的活化的甲基循环［2］。许多生物,特别是依赖环境条件而代谢类型多样化的植物、细菌和水生低等生物,在干旱、盐渍、深冻等低水势的逆境中,为了维持细胞的渗透势,合成和积累有机小分子,如脯氨酸［3］、甜菜碱［4］等氨基酸类,岩藻糖［5］、甘露醇［6］等单糖、双糖、三糖及糖醇类物质。LeRudalier［1］等（1984）法国和美国科学家合作,用150种代谢中间产物作体外渗透胁迫实验,发现只有甘氨酸甜菜碱和脯氨酸甜菜碱能有效地促进细胞生长,…     

巯基修饰对中华仓鼠二氢叶酸还原酶的激活

脊椎动物二氢叶酸还原酶（ＤＨＦＲ,Ｅ．Ｃ．１．５．１．３）可被多种因素激活,如中性无机盐［１］、蛋白质变性剂［１～４］、巯基修饰剂［１,４～７］等．来源于鸡肝［５］、猪肝［６］、鼠肝［７］及鼠Ｌ１２１０细胞［４］二氢叶酸还原酶的巯基修饰激活已有报道．...     

通过筛选随机多肽文库研究ZO-1中PDZ1结构域的配体结合特点

选择ZO-1的PDZ1结构域作为研究对象,以酵母双杂交为筛选系统,筛选随机多肽文库和与其它PDZ结构域的配体进行相互作用,阐明ZO-1 PDZ1的配体结合特性.ZO-1 PDZ1识别配体C末端保守的氨基酸序列通式可以表示为：［S/T］［F/Y/W］［V/I/L/C］-COOH、［S/T］［K/R］V-COOH、V［F/Y/W］［L/C］-COOH、EYV-COOH.研究发现ZO-1 PDZ1的配体同时具有3种传统PDZ结构域配体的特点,不同的是其结合配体-1位对芳香族氨基酸具有强烈的偏好性.并且某些PDZ结构域配体的-1位和-3位对结构域与配体相互作用的特异性和亲和力有重要的作用.随后通过生物信息学的方法在Swiss-Prot数据库找到与此识别规律相符合的天然人类蛋白质.根据蛋白质的功能和细胞定位等性质选择10个配体用酵母双杂交验证相互作用.证实的相互作用配体有4个.本研究希望用这样的研究策略建立一种有效的研究蛋白质相互作用的方法,通过在全蛋白质组规模上对含有结合配体保守氨基酸序列的蛋白质的查询,理论上可以找到现有数据库中所有可能与目的结构域结合的潜在配体蛋白,特别是那些筛选cDNA文库不容易获得的低丰度配体.     

［B1－Ala，B2－Ala］－胰岛素：受体结合特性及生物活力研究

本文报道了［Ｂ１～Ａｌａ,Ｂ２－Ａｌａ］－胰岛素与人胎盘细胞膜胰岛素受体结合的特性和体外生物活力,并与胰岛素进行比较。在３７℃和杆菌肽存在下,１２５Ｉ－［Ｂ１－Ａｌａ,Ｂ２－Ａｌａ］－胰岛素和１２５Ｉ－胰岛素与人胎盘细胞膜作用依赖于反应时间,反应６分钟到达平衡,此时,［Ｂ１－Ａｌａ,Ｂ２－Ａｌａ］－胰岛素和胰岛素与胰岛素受体的最大结合分别为每毫克膜蛋白结合６．４４ｆｍｏｌ和３．４７ｆｍｏｌ：达到平衡一半所需时间（Ｔ１／２）分别为１９秒和２５秒。用１２５Ｉ－［Ｂ１－Ａｌａ,Ｂ２－Ａｌａ］－胰岛素作为放射配体进行竞争性结合研究,从ＩＣ（５０）得［Ｂ１－Ａｌａ,Ｂ２－Ａｌａ］胰岛素的受体结合活力为胰岛素的１３９．６％。Ｓｃａｔｏｈａｒｄ分析求得;［Ｂ１－Ａｌａ,Ｂ２－Ａｌａ］－胰岛素与高亲和和低亲和结合位点的结合常数在４℃时分别为５．８８×１０８Ｌ／ｍｏｌ和７．６３×１０５Ｌ／ｍｏｌ,而胰岛素分别为４．８３×１０８Ｌ／ｍｏｌ和３．３９×１０５Ｌ／ｍｏｌ。促脂肪细胞生成脂的实验表明：［Ｂ１－Ａｌａ,Ｂ２－Ａｌａ］－胰岛素的活力为胰岛素的１３０％。     

紫杉醇诱导的细胞凋亡信号转导

紫杉醇为新型抗微管药物,对许多肿瘤都有明显疗效,尤其是晚期卵巢癌和乳腺癌［１］。它的作用目标是细胞骨架的微管系统,其结合位点在β－微管蛋白Ｎ－端第３１位氨基酸和第２１７～２３１位氨基酸位点上,结合后促进微管蛋白聚合并稳定微管结构,抑制其解聚,进而影响...     

短杆菌肽S与脂膜结合前后的H／D交换动力学的研究

短杆菌肽Ｓ（ＧＳ）是一个十肽分子（环－（Ｌ－Ｖａｌ－Ｌ－Ｏｒｎ－Ｌ－Ｌｅｕ－Ｄ－Ｐｈｅ－Ｌ－Ｐｒｏ）２）,是由两个β转角和两个β片层结构所构成［１］。ＧＳ的功能是通过破坏葛兰氏阴性菌的膜结构来完成其抗菌活性。迄今为止,人们对ＧＳ与膜结合特点的研究结果还不一致。Ｄａｔｅｍａｎ等人利用２Ｈ－ＮＭＲ,３１Ｐ－ＮＭＲ和ＤＳＣ等技术研究了ＧＳ与ＤＰＰＣ多层脂膜的相互作用,指出肽仅仅作用于膜表面［２］;而Ｈｉｇａｓｈｉｊｉｍａ等［３］及张凤立等用２Ｄ－ＮＭＲ的研究结果［４］表明,ＧＳ的疏水部分应插入膜内。蛋白质及多肽的Ｈ／Ｄ交换动力学受其分子内氢键,分子空间结构的致密度及其周边环境如膜环境［５］的影响。我们利用衰减全反射红外光谱（ＡＴＲ－ＦＴＩＲ）对与脂膜结合前后的短杆菌肽Ｓ的Ｈ／Ｄ交换动力学进行了研究,实验结果提示ＧＳ插入了脂膜双层。     

[B3—Lys]—胰岛素的研究：受体结合及生物活性

本文用＾１２５Ｉ－［Ｂ３－Ｌｙｓ］－胰岛素和＾１２５Ｉ－胰岛素研究了［Ｂ３－Ｌｙｓ］－胰岛素和胰岛素与人胎盘细胞膜胰岛素受体结合物性并进行了比较。实验结果表明［Ｂ３－Ｌｙｓ］－胰岛素与ＨＰＭ胰岛素受体结合能力比天然猪胰岛素高。由竞争取代曲线得到的［Ｂ３－Ｌｙｓ］－胰岛素和猪胰岛素的ＩＣ（５０）值分另为０．６５和１．１１ｎｍｏｌ／Ｌ。经Ｓｃａｔｃｈａｒｄ分别得出［Ｂ３－Ｌｙｓ］－胰岛素与ＨＰＭ胰岛素     

Acetylene as a suicide substrate and active site probe for methane monooxygenase from Methylococcus capsulatus (Bath)

Abstract Acetylene was shown to be an inhibitor of cell-free methane monooxygenase (MMO) activity in Methylococcus capsulatus (Bath). Inhibition was demonstrated for both the soluble and particulate forms of the enzyme and was dependent on the presence of both NADH and oxygen. Inactivation of the enzyme complex was irreversible and was due to binding of the acetylene to specific proteins of the enzyme complex. The use of radiolabelled [¹⁴C]acetylene provided a method for visualisation of the bound inhibitor: protein complex on sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE). Acetylene was shown to bind to proteins which are associated with methane-oxidising activity and it is proposed that acetylene acts as a suicide substrate.     

Cu2+污染土壤接种AM真菌对紫云英生长的影响

通过5个土壤Cu2 水平(0,20,50,100,150mgkg-1)的盆栽试验,研究了不同土壤Cu2 水平接种AM真菌对紫云英生长的影响。结果表明:(1)随着土壤Cu2 水平升高,紫云英生物量下降,与未接种相比,接种AM真菌明显提高了紫云英的生物量,接种G.intraradices对紫云英生物量的提高比接种G.mosseae更为明显,两者间呈显著性差异。(2)随着土壤Cu2 水平升高,紫云英根段浸染率下降,菌丝琥珀酸脱氢酶、碱性磷酸酶活性也下降。(3)在相同土壤Cu2 水平接种不同的AM真菌,紫云英根段浸染率有显著差异,接种G.intraradices的紫云英根段浸染率显著高于接种G.mosseae的处理,其菌丝琥珀酸脱氢酶活性及碱性磷酸酶活性也显著高于接种G.mosseae的处理。(4)接种G.intraradices能显著抑制Cu2 从紫云英地下部分向地上部分的运转,降低Cu2 的毒害,接种G.mosseae相对促进了Cu2 的运转。以上结果显示,Cu2 污染土壤中接种G.intraradices对紫云英生长具有促进作用。     

Role of interneuronal systems in the formation of main patterns of field electrical activity in the hippocampus

Studies on the cellular and subcellular levels promote elucidation of the fundamental principles of formation of effective neuronal systems from cell units. To estimate the interrelations between electrical activity of neuronal networks and processes realized on the cellular level, we need to adequately understand the general patterns of behavior of populations of interneurons, which are components of these networks, under different physiological conditions. In this review, we describe and discuss the relations between the electrical activity of single hippocampal neurons and different components of the field electrical activity, as well as modern concepts on the mode of involvement of the system of hippocampal interneurons in the formation of physiologically important patterns of efferent activity of the above-mentioned structure (in particular in encoding of information on the neuronal level). Neirofiziologiya/Neurophysiology, Vol. 40, No. 1, pp. 58–68, January–February, 2008.     

持续性内切纤维素酶高效催化的研究进展

持续性内切纤维素酶(Processive endoglucanase)是一类新发现的双功能纤维素水解酶,既符合内切酶的作用特征,又具有外切酶的持续催化能力,可高效降解纤维素生成小分子寡糖。这类酶通常具有模块化结构,碳水化合物结合模块(CBM)对酶的持续催化活性及底物结合能力表现出不同的影响。综述了该领域相关研究的最新进展,分析了持续性内切酶潜在的研究方向及工业化应用的前景。     

苦楝果实活性物质研究

本文报道苦楝果实中的生物活性物质。发现果实的抽提物和单体化合物不仅具有防治作物害虫的作用,而且,还对植物有生长调节作用。通过生物活性鉴定结果表明:果实种仁的水抽提物对水稻早期萌动、发芽与秧苗的生长均有促进作用。其中,处理稻种第2天(48h),其发芽率比对照高出24.67％～42.86％;第4天秧苗的根长在1cm以上占56.5％～65.0％,而对照组只有15.5％。尤其是抽提液浓度在6000ppm时处理的稻种,测得生长10d的秧苗总长为对照的120.27％,胚根长为对照的121.54％;以及叶片中的叶绿素总含量比对照高8.5％。还证明了从果实中提取分离的几种三萜类化合物和在果实中发现的一种新化合物对苯二甲酸二甲酯,均对菜青虫有拒食和胃毒活性。     

The comparative persistence of toxicity of Bacillus sphaericus strain 1593 and Bacillus thuringiensis serotype H-14 against mosquito larvae in different kinds of environments

Bacillus sphaericus strain 1593 and B. thuringiensis serotype H-14 were evaluated for persistence of toxicity against two species of mosquito larvae, Culex quinquefasciatus and Aedes aegypti, in a selected simulating plot in Bangkok. Both strains of bacteria demonstrated larvicidal activity towards both species of mosquito larvae. In tap water, the toxicity of B. sphaericus strain 1593 was found to be greater towards C. quinquefasciatus larvae than A. aegypti larvae, whereas the toxicity of B. thuringiensis serotype H-14 was found to be greater towards A. aegypti larvae than C. quinquefasciatus larvae. The persistence of toxicity of these two bacteria was found to be different. The lethal concentration of B. thuriengiensis H-14 against A. aegypti decreased from LC₉₀ to below LC₅₀ in about 15 weeks when tested in tap water. The decrease was faster in polluted water. The toxicity of B. sphaericus 1593 towards C. quinquefasciatus larvae persisted for at least 9 months in tap water and 6 months in polluted water. The multiplication of bacteria was indicated only in populations of B. sphaericus 1593 tested with C. quinquefasciatus larvae.     

Temporal Markers in Plant Morphogenesis

In plants as well as in animals, time may be registered in permanent structures at all organization levels. In this brief review, some examples of spatial rhythmic patterns related to plant morphogenesis and as far as possible the underlying mechanisms will be described. In conclusion, the practical interest of these structures will be emphazised.     

Induction of antibacterial activity in the blood of the migratory locust Locusta migratoria L.

Injections of low doses of living cells of Bacillus thuringiensis into larvae or adults of Locusta migratoria (Orthoptera) induce an in vivo protection against lethal doses of this pathogen (‘immunisation’). In the present paper we show that concomitant with the induction of the in vivo protection, an antibacterial activity appears in the plasma of the immunised insects. This activity is maintained for 10 days and disappears at the time the protective mechanism loses its efficiency. Antibacterial activity in the plasma of experimental insects is induced by injections of bacteria other than B. thuringiensis (Escherichia coli, Pseudomonas aeruginosa) and non-bacterial substances (ovalbumine, iron saccharate): it reduces growth of cultures of B. thuringiensis and also of E. coli or P. aeruginosa under in vitro conditions. Repeated immunising injections increase the level of plasma antibacterial activity. Preliminary biochemical studies indicate that the antibacterial activity is linked to the presence in the plasma of a low molecular weight (<5000 daltons), heat-stable, polar bacteriostatic compound which is not inactivated by use of conventional proteolytic or glycolytic enzymes.     

Regulators of complement activity mediate inhibitory mechanisms through a common C3b‐binding mode

Regulators of complement activation (RCA) inhibit complement‐induced immune responses on healthy host tissues. We present crystal structures of human RCA (MCP, DAF, and CR1) and a smallpox virus homolog (SPICE) bound to complement component C3b. Our structural data reveal that up to four consecutive homologous CCP domains (i–iv), responsible for inhibition, bind in the same orientation and extended arrangement at a shared binding platform on C3b. Large sequence variations in CCP domains explain the diverse C3b‐binding patterns, with limited or no contribution of some individual domains, while all regulators show extensive contacts with C3b for the domains at the third site. A variation of ~100° rotation around the longitudinal axis is observed for domains binding at the fourth site on C3b, without affecting the overall binding mode. The data suggest a common evolutionary origin for both inhibitory mechanisms, called decay acceleration and cofactor activity, with variable C3b binding through domains at sites ii, iii, and iv, and provide a framework for understanding RCA disease‐related mutations and immune evasion.