Chemical and biological pathways in the bacterial oxidation of arsenopyrite

Abstract: A moderately thermophilic mixed culture of bacteria catalysed the oxidative solubilization of arsenopyrite to give Fe(III), S(VI) and As(V). Toxic effects were observed in a few experiments due to teh build-up of As(III). The bacterial oxidation of arsenopyrite involved direct attack of the bacteria on the mineral to give AS(III). Subsequent oxidation of AS(III) to AS(V) occurred reaction with FE(III), but only in the presence of pyrite, which provide a catalytic surface. Arsenopyrite was unable to act as a catalyst. The pyrite- catalysed oxidation of As(III) to AS(V) by FE(III) usually only went to completion in the presence of bacteria, possibly due to their role in the provision of clean catalytic surfaces. Thus, toxic concentrations of As(III) may accumulate in reactors during the bacterial oxidation of arsenopyrite due to the absence of pyrite or a clean pyrite surface or to low concentrations of the effective oxidizing agent, Fe(III).     

正常菌群对常见致病菌拮抗作用的研究

生物拮抗作用是微生物种群关系研究的一个侧面,实验中我们使用从皮肤上分离的常住菌——痤疮丙酸杆菌(A14-1)和表皮葡萄球菌(F65)对常见致病菌如金黄色葡萄球菌(C189)、绿脓杆菌(C8514)和埃希氏大肠杆菌(C1356)的体外拮抗试验表明,它们具有明显的拮抗作用,拮抗作用一般从48小时开始,72小时明显。而皮肤常住菌间无拮抗作用,相反它们还有协同作用,这对于皮肤的自净以及维持皮肤的微生态平衡具有重要的作用。此外,实验中还进行了乳杆菌和双歧杆菌等正常菌群分离株与上述常见致病菌的体外拮抗试验,结果表明也     

人抑胃肽的研究：合成和性质

人抑胃肽的研究：合成和性质崔大敷,崔恒苒,徐明华,曹蕙婷,朱尚权（中国科学院上海生物化学研究所,２０００３１）陈可靖,邓华云（上海医科大学附属中山医院,２０００３２）关键词人抑胃肽,合成,生物活性抑胃肽（简称ＧＩＰ）最早由Ｂｒｏｗｎ等’”从猪小肠分离...     

酶化学法制备AraA

AraA中文名称为9-β-D-阿拉伯呋喃糖基腺嘌呤,通常简称为阿糖腺苷,是一种广谱嘌呤核苷类抗病毒药,具有抑制病毒和肿瘤细胞生长的能力。目前,我国主要采用化学全盛法生产AraA。然而用化学合成法生产AraA反就步骤多,使用的试剂对人体危     

侵染新疆甜菜的两种病毒分离物的研究

在新疆甜菜的根部和叶片分离到两个球状病毒分离物。从病毒形态、生物学及物化性质等研究结果证明这两个分离物实是一种病毒。病毒粒体力２０面体,直径约２８ｎｍ,回接到甜菜上产生环斑和沿脉线纹最后形成坏死斑。此外还侵染苋色藜,昆诺阿黎,番杏,菠菜等,引起局部坏死斑。在普通烟,心叶烟,菜豆,黄瓜,蕃茄上无症状侵染,病毒致死温度为７０℃,１０分钟。体外存括期１３天以上,冻干病叶７年后仍有侵染力。通过ＰＥＧ沉淀、差速离心、琼脂糖柱层析及蔗糖梯度离心,可得到较高浓度的纯化病毒,病毒的紫外吸收最低值在２４５ｎｍ,最高值在２６０ｎｍ。经ＳＤＳ－ＰＡＧＥ测定,病毒外壳蛋白的分子量为２．７×１０￣４道尔顿,病毒基因组核酸为三个组份,分子量分别为３．０８ｋｂ,１．２８ｋｂ和０．８５ｋｂ。在琼脂双扩散实验中,能与番茄黑环病毒（ＴＢＲＶ）抗血清产生较弱的沉淀线,与黄瓜花叶病毒（ＣＷＶ）、烟草环斑病毒（ＴＲＳＶ）、烟草坏死病毒（ＴＮＶ）、香石竹环斑病毒（ＣａＲＳＶ）的抗血清不发生反应。     

Description of a New Species of Microsporidia from Muscidifurax raptor (Hymenoptera: Pteromalidae), a Pupal Parasitoid of Muscoid Flies

ABSTRACT. A microsporidian parasite, Nosema muscidifuracis n. sp., has been found in Muscidifurax raptor , a parasitoid of muscoid flies. Stages of the parasite developed in direct contact with the host cell cytoplasm and were detected in midgut epithelium, Malpighian tubules, ovaries (including oocytes) and fat body of larvae and adults. Spores were also detected within eggs deposited on the host. Light and electron microscopy revealed a developmental cycle with diplokaryotic stages dividing by binary fission and disporous sporulation sequences producing diplokaryotic spores of three morphological classes, differing significantly only in length of the polar filament. Two of the classes were found in larvae, pupae and adults. One of these, with about five turns in the coiled polar filament, is presumed to be responsible for transmission from cell to cell within the host (autoinfection) and the other, with about 10 turns, responsible for transmission from host to host. A third class, with about 15 turns in the polar filament, was found in eggs of M. raptor . It is, presumably, either involved in initiation and spread of the infection at eclosion or is responsible for horizontal transmission to a new host individual when eggs are cannibalized.     

A deterministic analysis of self-incompatibility alleles

A number of plant species have a self-incompatibility locus that prevents self-fertilization. We 'analyse a deterministic model with an arbitrary number of alleles. We prove that the only polymorphic equilibrium is the one for which all (heterozygous) genotypes are equally frequent, and we prove that all (initially) polymorphic populations converge to this equilibrium.     

番茄种子经激光和咖啡因处理后其当代生物效应的研究

咖啡因具有抑制一些酶的活性,可减弱或消除生物体自身对激光引起的生物效应的修复作用。试验证明咖啡因对番茄种子萌发有强烈的抑制作用,咖啡因和激光复合处理生物效应显著,可降低番茄种子的发芽,并促进番茄果实增大和生长前期速率加快。