Comparative study and expression analysis of the interferon gamma gene locus cytokines in Xenopus tropicalis

Using bioinformatics approach, the genome locus containing interleukin (IL)-22, IL-26, and interferon gamma (IFN-gamma) genes has been identified in the amphibian, Xenopus tropicalis. Like that in other vertebrates such as fish, birds, and mammals, the Xenopus IL-22, IL-26, and IFN-gamma are clustered in the same chromosome and the adjacent genes are conserved. The genomic structures of the Xenopus IL-22, IL-26, and IFN-gamma gene were identical to that of their mammalian counterparts. The Xenopus IL-22 and IL-26 genes contained five exons and four introns while the Xenopus IFN-gamma gene consisted of four exons and three introns. The Xenopus IL-22, IL-26, and IFN-gamma share 14.1-41.6%, 14.6-31.2%, and 23.7-36.5% identity to their counterparts in other species, respectively. Reverse-transcription polymerase chain reaction (PCR) and real-time quantitative PCR analyses revealed that the expression of IL-22, IL-26, and IFN-gamma genes was significantly upregulated after simulation with bacterial polyliposaccharide and/or synthetic double-stranded poly(I:C), suggesting these cytokines like those in other vertebrates play an important role in regulating immune response in Xenopus.

猎物条件对七星瓢虫(Coccinella septempunctata L.)捕食作用的影响

研究表明不同猎物种类对七星瓢虫的捕食作用具有不同的影响。七星瓢虫捕食效率对桃纵卷叶蚜(Myzus tropicalis)密度的依赖性较大, 对苹果绵蚜(Eriosoma lanigerum)的依赖性较小; 七星瓢虫-苹果绵蚜系统中, 七星瓢虫自身密度的干扰作用较大, 七星瓢虫-高蚜系统中的干扰作用较小。图5表2参8

酵母在石油烃代谢过程中胞外乳化物质的形成及作用研究

本文研究了热带假丝酵母（C. tropicalis���和解脂假丝酵母（C. lipolytica）利用混和正烷烃（C_(10)-C_(18)）生长过程中胞外乳化物的产生及作用。结果表明胞外乳化物质的大量产出现于对数生长后期和生长平衡期，热水抽提菌体所得细胞表面物质具有乳化性能，其乳化性能与细胞生长密切相关，生长旺盛细胞表面具有较高乳化性能。以冷丙酮（3：1）沉淀发酵上清液，获得胞外主要乳化物质，经反复沉淀、透析及冷冻干燥，初步纯化乳化物产率为0.5 g/L，C. tropicslis胞外主要乳化物为脂蛋白-多糖复合物，其中，糖46%、脂40%、蛋白3%。脂由多种中性脂组成，糖单元为果糖及两种未知单糖，蛋白中80%为极性氨基酸，C. lipolytica胞外乳化物质主要是脂-糖蛋白复合物，主要组成：糖66%、脂17%、蛋白6%。脂由中性脂和极性脂组成，糖蛋白组成：糖95、蛋白5%。糖单元为甘露糖、果糖，蛋白中80%为极性氨基酸（主要为成糖氨基酸）。两种胞外乳化物均为水溶性大分子复合物，在低浓度（<10mg/L）即具有良好乳化性能。去除蛋白后的胞外乳化物对烷烃的乳化性能降低90%，pH在中性时，乳化性能最佳。CaCl_2(10-50 mM)，NaCl(1-20%)， EDTA(2.5-10 mM)对C. lipolytica胞外乳化物质的乳化性能影响较大，而对C. tropiclis胞外乳化物影响较小，两种胞外提取物对产生菌利用烃生长有刺激作用。槐糖脂、C. lipolytica胞包提取乳化物对C. tropicalis���用烃的生长有刺激作用，鼠李糖脂、吐温80则表现出抑制作用。胞外生物乳化剂对酵母菌利用烷烃的生长有着重要作用。