Enhanced thermotolerance by hydrostatic pressure in the deep-sea hyperthermophile Pyrococcus strain ES4

Abstract: The combined effect of hydrostatic pressure and heat shock on thermotolerance was examined in the deep-sea hyperthermophilic archaeon Pyrococcus strain ES4. Pressure equivalent to the depth of isolation (22 MPa) enhanced ES4's survival at super-optimal temperatures (101–108°C) relative to low pressure (3 MPa). Pressure also raised the temperature at which a putative heat-shock protein (98 kDa) accumulated. ES4 grown at 95°C and 3 MPa displayed immediate enhanced thermotolerance to 105°C after being shifted to 22 MPa. Cultures grown at 95°C and 22 MPa and then heat shocked at 105°C and 3 MPa retained enhanced thermotolerance after decompression. These results suggest that this deep-sea hyperthermophile has developed pressure-induced responses that include increased survival to hyperthermal conditions.     

重要生物恐怖病原及其医学防护对策

生物恐怖问题由来已久,但直到美国“9.11”事件后的炭疽芽孢袭击才引起人们广泛关注。生物恐怖已成为21世纪全人类的威胁,防范生物恐怖病原袭击已成为各国政府的当务之急。本文主要介绍了对生物恐怖的定义、生物恐怖病原种类和致病特征,以及医学防护对策。     

Bitrophic toxicity of Cry1Ac to Cycloneda sanguinea,a predator in Brazilian cotton

Insect predators are exposed to the Cry1Ac toxin in Bt cotton fields through several pathways. In this study, we investigated the effects of activated Cry1Ac added to a diet on Cycloneda sanguinea (L.) (Coleoptera: Coccinellidae), which is one of the main predators of non‐target pests in Brazilian cotton. Direct bitrophic exposure of C. sanguinea to Cry1Ac was done by feeding beetles with Aphis gossypii (Glover) (Hemiptera: Aphidae) sprayed with 500 μg per ml Cry1Ac solution. Larval and pupal survival, development time, aphid consumption, and adult longevity were recorded daily. Couples within the same experimental treatment were paired and numbers of eggs laid and hatched per female were recorded daily. Net replacement rate was calculated for each female. During development, a C. sanguinea larva consumed on average 1.8 μg of activated Cry1Ac. No significant differences due to Cry1Ac were observed for any of the response variables, except aphid consumption. Larvae receiving Cry1Ac consumed more aphids than larvae receiving distilled water alone. Additional statistical analyses were conducted to evaluate independence of responses, and for the independent responses, a simple meta‐analysis was conducted to test the null hypothesis that all responses were zero. Nearly all of the response variables were statistically independent. Two pairs of responses were not independent, but the associated multivariate tests were not significant. The meta‐analysis suggested that all effects were not different from random variation around zero and no cumulative effects could be detected. Our results indicated that bitrophic exposure to activated Cry1Ac is likely to have little or no adverse ecological effect on C. sanguinea.     

一种载样简单的多重可视化PCR微芯片

在核酸检测领域急需一种能够经济、快速、操作简便且同时检测多个靶标的新技术。常规多重PCR能够同时扩增多个靶标,但由于在一个试管中引物间的相互作用和竞争,重数往往受到限制。本研究设计了一种操作简单的多重PCR芯片,可以同时进行54个靶标的扩增。芯片结构简单,一条微通道将正下方平行排列的多个微孔连接在一起,微通道只留加样口和出样口。同时整个微通道呈疏水状态,微孔呈亲水状态。将不同的引物对和低溶点琼脂糖提前固定于不同的微孔中,通过一次加入PCR mix,并加入矿物油推动PCR mix进入到每个微腔室中,同时微孔也被矿物油相互隔离避免交叉反应。加样后将芯片放置于平板PCR仪上进行扩增,在整个反应过程中低溶点琼脂糖呈液态,反应结束后凝固成固体,便可引入核酸染料进行染色,最后利用自制小型的紫外照射仪上进行可视化检测和拍照记录。利用此平台成功实现了对7种非常重要和常用的转基因作物靶标的并行检测,结果显示此平台具有较高的灵活性和特异性。此技术经过进一步优化可应用于包括转基因检测在内的多重核酸检测领域。     

Overproduction and one-step purification of the N 5,N 10-methenyltetrahydro-methanopterin cyclohydrolase (Mch) from the hyperthermophilic Methanopyrus kandleri

N ⁵,N ¹⁰-Methenyltetrahydromethanopterin cyclohydrolase (Mch) is an enzyme involved in methanogenesis from CO₂ and H₂ which represents the energy metabolism of Methanopyrus kandleri, a methanogenic Archaeon growing at a temperature optimum of 98°C. The gene mch from M. kandleri was cloned, sequenced, and expressed in Escherichia coli. The overproduced enzyme could be purified in yields above 90% in one step by chromatography on phenyl Sepharose in 80% ammonium sulfate. From 3.5 g cells (250 mg protein), approximately 18 mg cyclohydrolase was obtained. The purified enzyme showed essentially the same catalytic properties as the enzyme purified from M. kandleri cells. The primary structure and properties of the cyclohydrolase are compared with those of the enzyme from Methanococcus jannaschii (growth temperature optimum 85°C), from Methanobacterium thermoautotrophicum (65°C), and from Methanosarcina barkeri (37°C). Of the four enzymes, that from M. kandleri has the lowest isoelectric point (3.8) and the lowest hydrophobicity of amino acid composition. Besides, it has the highest relative content of glutamate, leucine, and valine and the lowest relative content of isoleucine, serine, and lysine. Some of these properties are unusual for enzymes from hyperthermophilic organisms. They may reflect the observation that the cyclohydrolase from M. kandleri is not only adapted to hyperthermophilic conditions but also to the high intracellular concentrations of lyotrophic salts prevailing in this organism. Received: July 14, 1997 / Accepted: August 28, 1997     

生物多样性的几个问题（续）

从生物多样性的现状、存在的问题及应采取的措施等三个方面比较全面地叙述了我国生物多样性的情况。“生物安全”是《生物多样性公约《签订后每次缔约国会议都要讨论的中心议题之一。为之本文也用一定的篇幅作了较详细的介绍。     

Characterization of thermostable native alkaline phosphatase from an aerobic hyperthermophilic archaeon, <Emphasis Type="Italic">Aeropyrum pernix</Emphasis> K1

This paper reports the characterization of an alkaline phosphatase (AP) from an aerobic hyperthermophilic Archaeon Aeropyrum pernix K1. The native AP was purified into homogeneity. The enzyme is predicted as a homodimeric structure with a native molecular mass of about 75 kDa and monomer of about 40 kDa. Apparent optimum pH and temperature were estimated at 10.0 and above 95°C, respectively. Magnesium ion increased both the stability and the activity of the enzyme. A. pernix AP has been demonstrated as a very thermostable AP, retaining about 76% of its activity after being incubated at 90°C for 5.5 h and 67% of its activity after being incubated at 100°C for 2.5 h, respectively, under the presence of Mg(II). Enzyme activity was increased in addition of exogenous Mg(II), Ca(II), Zn(II), and Co(II).