SARS病毒S和N蛋白抗原表位的基因合成、融合表达及纯化鉴定

通过计算机分析SARS病毒N蛋白和S蛋白的氨基酸序列 ,初步确定含强抗原表位的N蛋白片段和S蛋白片段 ,共 5 6 0个氨基酸。选择真核和原核生物均偏爱的密码子 ,化学合成全新的SARS病毒N蛋白片段和S蛋白片段的基因序列 ,利用基因工程技术将两个基因片段串联 ,克隆至质粒Pet2 8a(+)内的NcoⅠ/EcoRⅠ位点 ,表达S蛋白片段和N蛋白片段的融合蛋白。将重组质粒转化大肠杆菌BL21(DE3) ,筛选获得了高效表达SARS病毒S蛋白片段和N蛋白片段融合蛋白的工程菌 ,表达的SARS病毒的融合蛋白约占菌体蛋白总量的 30 %左右 ,部分以可溶性形式存在。经离子交换柱和反相高压液相纯化获得了表达的融合蛋白 ,经初步鉴定 ,显示该融合蛋白有较好的抗原性和特异性.     

霍乱弧菌生物被膜发育与环境调控

生物被膜状态的霍乱弧菌具有极强的环境适应性和超高的感染性,生物被膜的发育调控研究对霍乱弧菌的宿主感染和环境适应非常重要。本文综述了近年来霍乱弧菌生物被膜研究结果,包括霍乱弧菌生物被膜的组成、发育和环境调控,尤其着重阐述了各种环境因子对霍乱弧菌生物被膜发育的影响,包括细菌自体信号分子、自然环境因子和宿主信号分子。     

Factors and consequences of a non-functional alary polymorphism inPyrrhocoris apterus (Heteroptera: Pyrrhocoridae)

Functional alary polymorphisms have been studied rather extensively in several insect species. This review article deals with factors controlling wing polymorphism in a flightless species,Pyrrhocoris apterus (L.), and discusses its adaptive significance and mechanisms for their persistence under natural conditions. The macropterous morph is determined by a recessive allele whose penetrance depends on photoperiod and temperature. Natural populations of this species contain a small fraction of flightless macropters. The disadvantages of being a macropter (increase of development time, decrease of fecundity) are minimal, while the benefit may consist in the tendency to prereproductive arrest of ovarian development in teneral females. It prevents establishing a second generation which would mostly die during the next winter. The mechanism of alary morph regulation may be an ancestral trait linkingP. apterus with other polymorphic Heteroptera, while its decreased penetrance may be a derivative character. Variation in fitness due to alary morphs is small compared to the one associated with differences in body size. The latter is environmentally determined, and not linked to the genetic basis of wing polymorphism. In the “mosaic” of phenotypes of various size the significance of the genetic macroptery may be close to neutral.     

Seasonal succession,standing crop and determinants of primary productivity of the phytoplankton of Ministik Lake,Alberta, Canada

Ministik Lake (longitude 113°01; latitude 53°21), a well-mixed, shallow (mean depth 1.83 m), eutrophic lake is characterized by eutrophic chlorococcalean and cyanophycean phytoplankton associations, and little change in standing crop size with increasing depth. Standing crops and primary productivity are low during the winter but pronounced spring and late summer/early autumn maxima occur. Mean yearly areal standing crop (B) and primary productivity (A) were 199.2 mg m^–2 chlorophyll a and 319.5 mg C hr^–1 m^–2 respectively. Annual productivity was estimated at 1399,6 g C m^–2yr^–1. The mean increase in the extinction coefficient () per unit increase in standing crop (B) was 0.03 In units m^–1. High non-algal light attenuation (q) occurred averaging 46% which prevented the ratio B from attaining more than 74.2% of the theoretical maximum except once when selfshading occurred. Insignificant relationships existed between B (mg m^–3 chlorophyll a) and A_max (mg C hr^–1 m^–3), A and B and A and B. Close correlations existed between A and A_max/ and A and I₀ (W m^–2). The depth of the euphotic zone (Z_eu) varied between 0.6 and 2.0 m; the average relationship between z_eu and was z_eu = 3.78/_te, and the mean standing crop in the euphotic zone represented 58.3% of the theoritical maximum. The high _q values made the model of Talling (1957) inapplicable to this lake. The Q₁₀ value for the lake was 1.20. _max (mg C chlorophyll a ^–1 hr^–1) was closely related to both temperature and irradiance, and depressed by high pH values.Growth of the cyanophycean algae was correlated with temperature, chlorophycean algae with phosphate-phosphorus and temperature and the diatoms with dissolved silica and phosphate-phosphorus, but only in the case of Chaetoceros elmorii did any nutrient appear limiting. Indirect evidence that free CO₂ limited photosynthetic rates is provided by the _max:pH relationship.     

乙型肝炎表面抗原亚型“y”决定簇抗原性研究

用免疫扩散法(ID)对新疆、内蒙、西藏三地区的维吾尔族、蒙古族及藏族37份ayw/HBsAg阳性标本进行分型,36份为ayw2亚型,1份ayw4亚型,后者为我国ayw2优势亚型区首次发现的另一种新亚型,用y单克隆抗体酶标电泳法对ayw1、ayw2、ayw3和ayw4进行了抗原性研究,结果证明,ayw2和ayw4与ayw1和ayw3两组中的y为两种抗原性不完全相同的决定簇,本研究结果对乙型肝炎流行病学调查和乙肝疫苗抗原的合理组成有一定参考价值。     

Phenotypic typing, technological properties and safety aspects of Lactococcus garvieae strains from dairy environments

AIMS: To characterize Lactococcus garvieae strains of dairy origin and to determine their technological properties and safety for their possible use in starter culture preparation. METHODS AND RESULTS: Forty-seven L. garvieae isolates, recovered from two artisanal Italian cheeses were studied, in comparison with 12 fish isolates and the type strain of the species. Phenotypic typing revealed that the strains could be differentiated on the basis of their ecological niche of origin in lactose positive strains (all isolated from dairy sources) and lactose negative strains (all isolated from fish). Furthermore, the strains exhibited a high degree of physiological variability, showing the presence of 26 different biotypes. The strains possessed moderate acidifying and proteolytic activities and did not produce bacteriocins. A safety investigation revealed that all strains were sensitive to vancomycin and moderately resistant to kanamycin; some biotypes were tetracycline resistant. Production of biogenic amines or presence of genes encoding virulence determinants occurred in some isolates. CONCLUSIONS: The prevalence of L. garvieae in some artisanal Italian cheeses can be linked to the typicity of the products. Although in a few cases an antimicrobial resistance or a presence of virulence determinants may imply a potential hygienic risk, most of the strains showed positive properties for their possible adjunction in a starter culture preparation, to preserve the natural bacterial population responsible for the typical sensorial characteristics of the traditional raw milk cheeses. SIGNIFICANCE AND IMPACT OF THE STUDY: L. garvieae strains can be considered an important part of the microbial population associated with the natural fermentation of artisanal Italian cheeses. A deepened characterization of the strains may aid in understanding the functional and ecological significance of their presence in dairy products and in selecting new strains for the dairy industry.     

Physiological significance of pedospheric nitric oxide for root growth,development and organismic interactions

Nitric oxide (NO) is essential for plant growth and development, as well as interactions with abiotic and biotic environments. Its importance for multiple functions in plants means that tight regulation of NO concentrations is required. This is of particular significance in roots, where NO signalling is involved in processes, such as root growth, lateral root formation, nutrient acquisition, heavy metal homeostasis, symbiotic nitrogen fixation and root–mycorrhizal fungi interactions. The NO signal can also be produced in high levels by microbial processes in the rhizosphere, further impacting root processes. To explore these interesting interactions, in the present review, we firstly summarize current knowledge of physiological processes of NO production and consumption in roots and, thereafter, of processes involved in NO homeostasis in root cells with particular emphasis on root growth, development, nutrient acquisition, environmental stresses and organismic interactions.     

Long‐term and contemporary environmental conditions as determinants of the species composition of bog organisms

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Multiple Wolbachia determinants control the evolution of cytoplasmic incompatibilities in Culex pipiens mosquito populations

Wolbachia are maternally inherited endosymbionts that can invade arthropod populations through manipulation of their reproduction. In mosquitoes, Wolbachia induce embryonic death, known as cytoplasmic incompatibility (CI), whenever infected males mate with females either uninfected or infected with an incompatible strain. Although genetic determinants of CI are unknown, a functional model involving the so-called mod and resc factors has been proposed. Natural populations of Culex pipiens mosquito display a complex CI relationship pattern associated with the highest Wolbachia (wPip) genetic polymorphism reported so far. We show here that C. pipiens populations from La Réunion, a geographically isolated island in the southwest of the Indian Ocean, are infected with genetically closely related wPip strains. Crossing experiments reveal that these Wolbachia are all mutually compatible. However, crosses with genetically more distant wPip strains indicate that Wolbachia strains from La Réunion belong to at least five distinct incompatibility groups (or crossing types). These incompatibility properties which are strictly independent from the nuclear background, formally establish that in C. pipiens, CI is controlled by several Wolbachia mod/resc factors.