马占相思林冠蜘蛛群落的结构分析

用杀灭菊酯喷洒林冠,收集得蜘蛛２６种,１９９只。群落组成以不结网为为主,全年均保持较高数量水平。结网类从４月至１０月成指数曲数下降。４个相似样地上的群落结构显著差异。以ＭａｃＡｒｔｈａｒ分布模型为基础,求出每个种在群落中的数量－时间－空间的重要值。结果以斜蛛的ＮＴＤ为最,斑络新妇幼体为次。蜘蛛－昆虫群落的营养结构在各样地上是一致的。蜘蛛作为捕食者,占总数１２－１５％。     

上调基因4与癌症

上调基因4（up-regulated gene-4,URG4）是受乙肝病毒X蛋白（hepatitis B virus X protein,HBx）激活的下游基因之一,最初在转染HBx的HepG2细胞中被克隆,因其上调细胞增殖效应而得名。与未转染的细胞相比,URG4在HBx转染后的HepG2细胞中表达明显增加,证实了URG4与乙肝病毒相关的肝细胞癌发生相关。近年来,人们发现URG4不仅在肝癌细胞中高表达,还与胃癌、骨肉瘤、非小细胞肺癌、神经母细胞瘤等多种癌症相关。本文结合近年来对URG4的研究成果,包括URG4基因及其蛋白质的结构与功能,URG4在癌症发生发展中的作用,以及在癌症早期诊断和预后中的意义进行综述,可望为后续深入地开展URG4与癌症的研究提供参考。     

Biometric variations and oxidative stress responses in juvenile Clarias gariepinus exposed to Termex®

The current study investigated the effects of termite insecticide, Termex® (imidacloprid 35.50% SC), on biometric variations and oxidative stress biomarkers in Clarias gariepinus. Fish were exposed to 4.00 and 6.00 µg l^–1 sublethal Termex® concentrations in 2017. The gill and liver tissues were sampled on days 7, 14, 21 and 28 and the results indicated that hepatosomatic index (HSI) decreased significantly when compared with the control on days 14, 21 and 28. The condition factor (CF) and viscera-somatic index (VSI) also decreased during the study period. The decrease was greater at 6.00 µg l^–1 Termex® concentration on days 21 and 28 for CF and days 14 to 28 for VSI, respectively. The lipid peroxidation (LPO) in both tissues was highest in the 6.00 µg l^?1 Termex® and increased with the duration. There was significant decrease (p < 0.05) in superoxide dismutase and glutathione peroxidase values, but significant increase in catalase activity in both tissues. The values of glutathione reductase in both tissues were comparable to the control, except on days 21 and 28 in the liver. There was negative correlation between the LPO in tissues and the HSI, CF and VSI values. The use of Termex® in the environment should be monitored to safeguard the health of aquatic organisms.     

Fast evolutionary genetic differentiation during experimental colonizations

Founder effects during colonization of a novel environment are expected to change the genetic composition of populations, leading to differentiation between the colonizer population and its source population. Another expected outcome is differentiation among populations derived from repeated independent colonizations starting from the same source. We have previously detected significant founder effects affecting rate of laboratory adaptation among Drosophila subobscura laboratory populations derived from the wild. We also showed that during the first generations in the laboratory, considerable genetic differentiation occurs between foundations. The present study deepens that analysis, taking into account the natural sampling hierarchy of six foundations, derived from different locations, different years and from two samples in one of the years. We show that striking stochastic effects occur in the first two generations of laboratory culture, effects that produce immediate differentiation between foundations, independent of the source of origin and despite similarity among all founders. This divergence is probably due to powerful genetic sampling effects during the first few generations of culture in the novel laboratory environment, as a result of a significant drop in N _e. Changes in demography as well as high variance in reproductive success in the novel environment may contribute to the low values of N _e. This study shows that estimates of genetic differentiation between natural populations may be accurate when based on the initial samples collected in the wild, though considerable genetic differentiation may occur in the very first generations of evolution in a new, confined environment. Rapid and significant evolutionary changes can thus occur during the early generations of a founding event, both in the wild and under domestication, effects of interest for both scientific and conservation purposes.     

Organization of fusicoccin receptor in higher plant plasma membrane: relationship between affinity and molecular mass

Higher plant plasma membranes carry receptors of different affinity for the phytotoxin fusicoccin. Reception of fusicoccin involves proteins belonging to the highly conserved 14-3-3 family, but the complete structure of the fusicoccin receptor (FCR) is unknown. Using radiation inactivation analysis, we estimated the molecular masses of low-affinity and high-affinity FCR at 63 +/- 7 and 130 +/- 15 kD, respectively. The dose dependences of receptor inactivation indicate that microsomal specimens contain "silent" FCRs of 420 +/- 90 kD in amounts commensurate with that of the active FCRs. Both low- and high-affinity FCRs are inactivated by hydrolytic enzymes from the outer surface of the plasma membrane, and impairment of protoplast integrity causes an irreversible transition of the low-affinity binding site into the high-affinity one. A scheme is proposed for the organization of different types of FCR in the plasma membrane, implying that the membrane affinity for fusicoccin reflects the interaction between proteins in the FCR complex.     

几种念珠菌DNA总含量的流式细胞分析

应用流式细胞术(FCM)对处于稳定生长阶段的念珠菌属(Candida)的7种8株念珠菌进行了DNA总含量的流式细胞(FCM)分析。这8株念珠菌是:白念珠菌(C.albicans)2株,热带念珠菌(C.tropicalis),克柔念珠菌(C.krusei),近平滑念珠菌(C.parapsiolosis),乳酒念珠菌(C.kefyr),白念珠菌星形变种(C.stellatoidea),即血清B型白念珠菌,季也蒙念珠菌(C.guilliermondii)各一株。应用EB一步插入法染色,用鸡红细胞(CRBC)作为内参标准进行DNA总含量测定。分析结果表明:稳定生长阶段的组方图上,大多数念珠菌细胞处于DNA合成周期的G_0/G_1期;DNA总含量有明显的种间和种内差异。     

环境对沼泽红假单胞菌基因型的影响

<正>紫色光合细菌是不产氧光合细菌的一个重要分支,包括紫色非硫细菌和紫色硫细菌。其中紫色非硫细菌具有极其丰富的代谢模式,可进行光能异养、光能自养和化能异养生长,其代谢的多样性使得它们广泛存活于不同的生态系统中,如土壤、湖泊、海洋及底泥等[1-2]。沼泽红假单胞菌(Rhodopseudomonas palustris)是紫