Adaptive evolution of primate TRIM5 alpha, a gene restricting HIV-1 infection

Recent studies showed that nonhuman primate TRIM5 alpha can efficiently block HIV-1 infection in human cell lines. It can also restrict other retroviruses, therefore, suggested as a general defender against retrovirus infection. Here, we present an evolutionary analysis of TRIM5 alpha in primates. Our results demonstrated that TRIM5a has been evolving rapidly in primates, which is likely caused by Darwinian positive selection. The SPRY domain of TRM5 alpha, which may be responsible for recognition of incoming viral capsids showed higher nonsynonymous/synonymous substitution ratios than the non-SPRY domain, indicating that the adaptive evolution of TRIM5a ill primates might be an innate strategy developed in defending retrovirus infection during primate evolution. In addition, the comparative protein sequence analysis suggested that the amino acid substitution pattern at a single site (344R/Q/P) located in the SPRY domain may explain the differences in Susceptibilities of HIV-1 infection in diverse primate species. (c) 2005 Elsevier B.V. All rights reserved.

The role of glutathione metabolism in tolerance of tobacco BY-2 suspension cells to microcystin-RR

This study was undertaken to investigate the role of the glutathione-involved detoxifying mechanism in defending the tobacco BY-2 suspension cells against microcystin-RR (MC-RR). Analysis showed that exposure of the cells to different concentrations of MC-RR (0.1, 1 and 10 mu g/mL) for 0-6 days resulted in a time and concentration-dependent decrease in cell viability and increase in reactive oxygen species (ROS) content. Reduced glutathione (GSH) and total glutathione (tGSH) content as well as glutathione reductase (GR), glutathione peroxidase (GPX) and glutathione-S-transferase (GST) activities significantly increased after 3-4 days exposure in the highest two concentration treated groups, while decreased until reaching the control values except for GPX at day 6. Oxidized glutathione (GSSG) content markedly increased compared with control in high concentration MC-RR treated group after 6 days exposure. The GSH/GSSG ratio was much higher than control in 10 mu g/mL MC-RR treated group at day 4, but after 6 days exposure, the ratios in all treated groups were lower than that of the control group.

浑太流域洪涝灾害及其治理方略

Hunhe, Taizihe rivers originating from the east mountain areas of Liaoning Province are the biggest tributaries of the left bank of Liaohe River. From the initial stage of New China to the early 1990s, the frequency of flood damage had decreased, but recently the disasters have upgraded and changed from trunk stream to tributary basins. In July 1995, Dongzhouhe, a tributary of Hunhe River, suffered from a heaviest flood since establishing the document of floods in Hunhe basin. Meanwhile, a peak discharge, almost beyond double defending ability, occurred at Dadongshanpu Station of Beishahe River, a tributary of Taizihe River. Besides the continued heavy rainstorm, no controllable water conservancy projects and ecological damages caused by quickly decreasing forest cover and water and soil loss are the two main causes of flood damage. In addition, the low flood protection standard is also one of causes. According to the above analyses, some strategies of synthetic controlling for flood damages were put forward: 1) Establishing the system of ecological engineering to defend floods and reduce disasters; 2)Setting up storage and detention areas; 3) Establishing flood controlling information system; 4) Improving the accuracy of media short period and short period rainstorm forecast and flood forecast; 5) Insurance of flood protection.

21世纪中国灾害警钟急鸣

我国地域辽阔 ,各种自然灾害的频繁发生 ,人为活动诱发的灾害日趋严重。由于乱砍滥伐 ,使森林资源锐减 ,严重破坏了生态环境 ,特别引起注意的是我国在 50～ 60年代已得到控制的蝗灾 ,近年因干旱已有所复活 ,除此以外 ,各种自然灾害和人为活动诱发的各类灾害 ,造成每年数千人至数万人的死亡 ,直接经济损失约 1 0 0 0～ 2 50 0亿元 ,对国民经济持续、稳定、协调发展造成严重威胁。本文根据上述情况分析了中国灾害的特点 ,列举了近年数起灾害实例 ,以引起人们对生态环境的重视。严峻的现实提醒大家 ,减灾工作已是 2 1世纪的当务之急 !

Morphological and reproductive response of Caragana microphylla to different stocking rates

Understanding the effect on host plants of defending against herbivores is important in grazing ecology and grassland management. In this study, the morphological and reproductive responses of Caragana microphylla Lam. to grazing sheep were investigated using a 15-year grazing experiment with six stocking rates in the Inner Mongolia steppe of China. Plant height, rachis length, leaflet size, and number of pods decreased significantly, whereas spine density and length increased significantly with increased stocking rate. Significant negative correlations were observed between production of vegetative and reproductive organs and defensive organs, indicating that it is costly for C. microphylla to defend against herbivores and that morphological miniaturization and a tradeoff between production and defense were main responses of C. microphylla to herbivores. (c) 2006 Elsevier Ltd. All rights reserved.

抽水引起岩溶塌陷的机理及非线性预测研究

Karst collapse is one of the most important engineering geology hazards in Karst district, which seriously endangers the living of humankind and the environment around us, as well as the natural resources. Generally speaking, there exist three processes of overburden karst collapse:the formation of soil cavity, the expansion of soil cavity and the fall of the cavity roof. During these processes, groundwater is always the most active factor and plays a key role. Pumping will bring into the great change of groundwater in flow state, flowrate, frequency of fluctuation as well as hydraulic gradient and will speed the fall. Statistics shows that most of the man-made karst collapse are induced by pumping, so studying the mechanism of Karst collapse induced by pumping will provide theoretical base for the prediction and precaution of collapse. By theoretically studying the initial condition for the forming and expanding of a soil cavity, Spalling step by step the essential mechanism of Karst collapse induced by pumping is put forward. The catastrophe model for the collapse induced by pumping is set up to predict the fall probability of a cavity roof, and the criterion for the collapse is determined. Simultaneously, Karst collapse induced by pumping is predicted with manmade neural network theory. Finally, the appropriate precaution measurements for the collapse induced by pumping are provided. The creative opinions of the paper is following: The initial condition of forming a soil cavity is put forwarded as formula (4-1-5), (4-1-24),(4-1-25) and (4-1-27); which provide theoretical base for foreclosing the formation of a soil cavity and defending collapse. Spaliing step by step as the essential mechanism of Karst collapse induced by pumping is put forward. The spaliing force is defined as formula (4-2-15). The condition for the expanding of a soil cavity is that spaliing force is greater than tensile strength of soil. The stability of a soil cavity is first studied with catastrophe theory. It is concluded that the process of development up to ground collapse of a small cavity is continuous, however, the process of a big cavity is catastrophic. It is feasibility that the Karst collapse be predicted with manmade neural network theory as a new way.