Arsenic precipitation in the bioleaching of enargite by Sulfolobus BC at 70 °C

Enargite (Cu₃AsS₄) was leached at 70°C by Sulfolobus BC in shake-flasks. The highest copper dissolution (52% after 550 h of leaching) was obtained with bacteria and 1 g l^–1 ferric ion. In the absence of ferric ion, Sulfolobus BC catalyzes the bioleaching of enargite through a direct mechanism after adhesion onto the mineral surface. In ferric bioleaching, arsenic precipitated as ferric arsenate and arsenic remained associated to the solid residues, preventing the presence of a high dissolved arsenic concentration in the leaching solution. About 90% inhibition of bacterial growth rate and activity was observed for dissolved arsenic concentrations above 600 mg l^–1 for As(III) and above 1000 mg l^–1 for As(V). Arsenic-bearing copper ores and concentrates could be leached by Sulfolobus BC in the presence of ferric iron due to the favourable precipitation of arsenic ion as ferric arsenate, avoiding significant bacterial inhibition.     

Changes in Water Soluble Protein Profile of Antarctic Cyanobacterium Nostoc Commune under Temperature Downshift from 25° to 5 °C

The cyanobacterium Nostoc commune (Nostocales) is an isolate from the Schirmacher Oasis Antarctica. The cyanobacterium is psychrotropic in nature; and maintained in laboratory at 25?°C temperature, in unialgal form. Here, we studied the change in protein profile of water soluble proteins from exponentially growing N. commune upon downshift from its optimum growth temperature (25?°C) to a low temperature (5?°C). Experimental set up used to analyze the proteome were- a sudden shift to low temperature (i.e., cold shock), after short- (8?days) and long-term acclimation (7?weeks) to low temperature (5?°C). Cold-shock resulted in an increase in Low molecular weight proteins (LMWPs) with clouding of diffused proteins. Further increase in the duration of incubation period (short- and long-term acclimation) caused dissociation of proteins, indicated by NaCl (50–600mM) induced dissociation of proteins. That is, high molecular weight proteins (HMWPs) dissociated into LMWPs resulting in an increased number of protein bands. This was further confirmed by addition of LMWPs (≤10KDa) resulting in re-association of proteins into HMWPs. Hence, we report that the cold-induced synthesis of LMWPs (≤10kDa) is a strategy adopted by the N. commune to survive at low temperature of Antarctica.     

Isolation and characterization of a thermophilic bacillus strain,that degrades phenol and cresols as sole carbon source at 70 °C

A phenol-degrading thermophilic bacterium, designated Bacillus sp. A2, was isolated from a water and mud sample from a hot spring in Iceland. The aerobic isolate grew optimally on phenol at 65 °C. At 70 °C, 85% of the optimal growth rate was still observed. No growth was observed at 40 °C and 75 °C. Bacillus sp. A2 is a gram-positive spore-forming rod. According to 16S rDNA analysis Bacillus sp. A2 is closely related to Bacillus stearothermophilus, Bacillus kaustophilus and Bacillus thermoleovorans. Bacillus sp. A2 degraded phenol completely in concentrations up to 5 mM. In addition, all three isomers of cresol were utilized as sole carbon and energy sources. The degradation of phenols proceeds via the meta-cleavage pathway and the enzymes involved in its degradation are constitutively expressed. Received: 13 May 1996 / Received revision: 29 July 1996 / Accepted: 12 August 1996     

蛋白质C

血液中的蛋白质C被激活后,通过多种方式促进凝血因子Xa和Ⅱa的形成．起到抗血液凝固、抗血栓形成的作用。蛋白质C功能异常,是一些血栓形成的原因。     

Molecular properties of phosphoenolpyruvate carboxylase from C3, C3−C4 intermediate,and C4 Flaveria species

Phosphoenolpyruvate carboxylase (PEPCase; EC 4.1.1.31) from Flaveria trinervia Mohr (C₄), F. floridana Johnston (C₃–C₄), and F. cronquistii Powell (C₃) leaves were compared by electrotransfer blotting/enzyme-linked immunoassay (Western-blot analysis), mobility of the native enzyme in polyacrylamide gels and in isoelectric focusing (IEF) gels, peptide mapping, and in-vitro translation of RNA isolated from each plant. The PEPCases from the C₃ and C₃–C₄ plants were very similar to each other in terms of electrophoretic mobilities on gels and isoenzyme patterns on IEF gels, and identical in peptide mapping. Quantitative differences were noted, however, in that the C₃–C₄ intermediate plant contained more PEPCase overall and that the relative activity of individual isoenzymes shifted between the C₃ and C₃–C₄ intermediate PEPCases. The PEPCase from the C₄ plant had a different isoenzyme pattern, a different peptide map, and was far more abundant than the other two enzymes. Western blot analysis demonstrated the cross-reactivity of PEPCases from all three Flaveria species with antibody raised against maize PEPCase. The results provide evidence, at the molecular level, that supports the view of C₃–C₄ intermediate species as C₃-like plants with some C₄-like photosynthetic characteristics, but there are differences from the C₃ plant in the quantity and properties of the PEPCase from the C₃–C₄ intermediate plant.Abbreviations IEF isoelectric focusing - kDa kilodalton - PEPCase phosphoenolpyruvate carboxylase - Rubisco Ribulose-1,5-bisphosphate carboxylase/oxygenase     

C3植物中C4途径的研究进展

综述了C3植物中C4途径的发现及研究现状;阐述了C3植物中C4途径的几种作用机理;根据C3植物中C4途径的存在,探讨了改造C3植物的遗传特性;并展望了这一领域的研究前景。     

3C胰岛素泵

2012年5月19日,美敦力宣布722实时动态胰岛素泵系统在中国上市,这是国内首款3C整合系统的胰岛素泵。所谓3C整合系统,即同时实现实时动态血糖监测（CGM）、胰岛素持续输注（CSII）与糖尿病信息管理（CareLink）。     

C3植物中C4途径的研究进展

综述了Ｃ３植物中Ｃ４途径的发现及研究现状：阐述了Ｃ３植物中Ｃ４途径的几种作用机理;根据Ｃ３植物中Ｃ４途径的存在,探讨了改造Ｃ３植物的遗传特性;并展望了这一领域的研究前景。     

如何快速鉴别C3与C4植物

在农业实践和科学研究中经常需要知道某种植物是C_3植物还是C_4植物,例如在干旱少雨的地区种植C_4作物就易获得较高的产量;用甲醇喷洒植物能使植物增产,但这种技术只适用于C_3植物而不适用于C_4植物等。从理论上讲,C_3植物光合作用固定CO_2的最初产物是三碳的3—磷酸甘油酸,C_4植物光合作用固定CO_2的最初产物是四碳的苹果酸或天冬氨酸。我们在研究农田杂草光合碳同化途径时,摸索了一些快速区分C_3植物与C_4植物的经验,介绍如下。 从植物进化方面区分 我们知道,C_3植物较原始,C_4植物较进化,实际上较原始的蕨类植物和裸子植物就没有C_4植物,只有较进化     

蛋白C,蛋白C激活剂和血栓性疾病

蛋白C(ProteinC,PC)系统是存在于人血浆中的天然抗凝系统,由蛋白C、蛋白S(PS)、血栓调节蛋白(TM)和蛋白C抑制剂(PCI)组成。许多研究结果表明:PC的病理改变与血栓性疾病的发生发展密切相关,PC可作为血栓性疾病诊断、疗效观察和预后评价的参考指标;PC和蛇毒PC激活剂有显著的抗凝溶栓效果,有应用于临床的可能性。现就这方面的进展作一简要综述。1　PC的生理功能和生物学特性　　PC是维生素K依赖性糖蛋白,以无活性的酶原形式存在于血浆中,由肝脏合成。PC是机体的一种重要的抗凝因子,约占血液抗凝活力的20%～30%,PC在微循环中的抗凝…     

C3、C4和C3-C4中间型植物的进化

介绍了有关C3、C4和C3-C4中间型植物进化的形态学、生理学、分子生物学、遗传学等方面的证据;推断地球上首先出现C3植物,然后是C3-C4中间类型植物,最后出现C4植物.     

C3和C4植物的氮素利用效率

Ｃ＿３和Ｃ＿４植物的氮素利用效率何新华,ＡｎｎＯａｋｓ,李明启（云南师范大学生物系,昆明６５００９２）（圭尔夫大学植物系,加拿大ＮＩＧ２Ｗ１）（华南农业大学农业生物系,广州５１０６４２）关键词Ｃ＿３和Ｃ＿４植物,ＮＯ吸收与积累,硝酸还原酶酶蛋白,硝酸...     

C型凝集素

C型凝集素（C-type lectin）代表一个识别碳水化合物配体依赖于钙离子（Ca2＋）参与的糖原结合蛋白家族,含有一个或多个一级结构和二级结构同源的碳水化合物识别结构域。随着研究的深入,越来越多的C型凝集素能够识别体内的非糖类的配体,包括蛋白质和脂类等。这些C型凝集素在维持机体稳态、免疫防御以及免疫监视等重要生理病理过程中发挥着重要作用。就C型凝集素的结构、分类和在免疫系统中的功能作一介绍。     

蛋白激酶C研究进展

蛋白激酶C(protein kinase C,PKC)是丝氨酸/苏氨酸激酶与蛋白激酶A和蛋白激酶G共同组成AGC家族。PKC广泛存在于哺乳动物组织和细胞当中,是信号转导途径的主要介质,同时也是细胞的增殖、分化、凋亡、转换等生理过程的关键调节因子。机体的许多疾病如糖尿病、心力衰竭、神经退行性疾病和癌症等都与PKC相关。本文主要从蛋白激酶C的结构、功能与分布及相关疾病的研究进展作一综述。     

Ecotypic differences in the C3 and C4 photosynthetic activity in Mollugo verticillata,a C3−C4 intermediate

Four populations of Mollugo verticillata L. were compared on the basis of their photosynthetic products, photosynthetic rates, enhancement under low oxygen concentration, and CO₂ compensation points. In addition, pulse-chase labeling experiments were conducted using one of the four populations. Depending on the plant population, C₄ acids ranged from 40% to 11% of the primary products under short-term exposure to ¹⁴CO₂. These compounds were also metabolized during pulse-chase experiments. All four populations had significantly different photosynthetic rates and those rates were correlated with the amounts of labelled C₄ acids produced and C₄-acid turnover. Three populations of M. verticillata had similar compensation points (40 l/l) and degrees of photosynthetic enhancement under low [O₂] (20%), the fourth population was much lower in both characteristics (CO₂ compensation, 25 l/l; low-O₂ enhancement, 12%). The results verify the intermediate nature of photosynthesis in this species, and illustrate populational differences in its photosynthetic and photorespiratory carbon metabolism.Abbreviations PGA 3-phosphoglyceric acid - Kan Kansas - Mass Massachusetts - Mex Mexico     

C3和C4禾本科作物的氮素利用效率

Ｃ＿３和Ｃ＿４禾本科作物的氮素利用效率何新华安·奥克斯（云南师范大学生命科学系,昆明６５００９２）（加拿大圭尔夫大学植物系圭尔夫ＮｌＧ．ＺＡ１）李明启（华南农业大学农业生物系广州５１０６４２）ＴＨＥＥＦＦＣＩＥＮＣＹＯＦＮＩＴＲＯＧＥＮＵＴＩＬＩＺＡ...     

北京地区随机人群C6、C7多态性研究

补体第六、七成分（C6、C7）具有遗传多态性。本文研究了北京地区随机人群115人的C6及137人的C7多态性分布,共检出C6等位基因有C6^*A、B、B2、M91、M1等5种。其中C6^*A和B为常见型。多态性共4种,即C7^*1、2、3、4,其中C7^*1为常见型。