天敌对麦长管蚜和麦二叉蚜种群数量影响程度的分析

通过对１９９３～１９９６年两种麦蚜种群数量及其天敌数量的系统调查,并采用灰色关联分析法,研究各种天敌对两种麦蚜种群数量的影响程度,得出对麦长管蚜种群数量影响最大的是龟纹瓢虫、蚜茧蜂和食蚜蝇;对麦二叉蚜种群数量影响最大的是草间小黑蛛,其次是龟纹瓢虫．     

Monitoring vegetation recovery after China’s May 2008 Wenchuan earthquake using Landsat TM time-series data: a case study in Mao County

The Wenchuan earthquake (Richter scale 8) on 12 May 2008 in southwestern China caused widespread ecosystem damage in the Longmenshan area. It is important to evaluate natural vegetation recovery processes and provide basic information on ecological aspects of the recovering environment after the earthquake. To circumvent the weather limits of remote sensing in the Wenchuan earthquake-hit areas, and to meet the need for regional observation analyses, three Landsat TM images pre- and post-earthquake in Mao County were used for analysis. Post-earthquake normalized difference vegetation index (NDVI) values were compared to pre-earthquake values with an NDVI-based index differencing method to determine the extent to which the vegetation was damaged in relation to the pre-earthquake pattern, and the rate of recovery was evaluated. The spatial characteristics of vegetation loss and natural recovery patterns were analyzed in relation to elevation, slope and aspect. The results indicated that severely damaged sites occurred mainly in river valleys, within a range of 1,500?C2,500?m elevation and on slopes of 25?C55°. The distance from rivers, rather than the distance from active faults, controls the damage patterns. After 1?year of natural regeneration, 36?% of the destroyed areas showed a decrease in NDVI value, 28.8?% showed very little change, 19.1?% showed an increase, and 16.1?% also increased with a recovery rate greater than 100?%. Moreover, there is a good correlation between recovery rate and both slope and elevation, but recovery patterns in the damaged area are complicated. Our results indicate that natural recovery in this arid valley is a slow process.     

Neutrophil recognition requires a Ca(2+)-induced conformational change in the lectin domain of GMP-140.

GMP-140, a receptor for myeloid cells that is expressed on surfaces of thrombin-activated platelets and endothelial cells, is a member of the selectin family of adhesion molecules that regulate leukocyte interactions with the blood vessel wall. Each selectin contains an N-terminal domain homologous to Ca(2+)-dependent lectins and mediates cell-cell contact by binding to oligosaccharide ligands in a Ca(2+)-dependent manner. The mechanisms by which Ca2+ promotes selectin-dependent cellular interactions have not been defined. We demonstrate that purified GMP-140 contains two high affinity binding sites for Ca2+ as measured by equilibrium dialysis (Kd = 22 +/- 2 microM). Occupancy of these sites by Ca2+ alters the conformation of the protein as detected by a reduction in intrinsic fluorescence emission intensity (Kd = 4.8 +/- 0.2 microM). This Ca(2+)-dependent conformational change exposes an epitope spanning residues 19-34 of the lectin domain that is recognized by a monoclonal antibody capable of blocking neutrophil adhesion to GMP-140 (half-maximal antibody binding at approximately 20 microM Ca2+). Furthermore, a synthetic peptide encoding this epitope, CQNRYTDLVAIQNKNE, inhibits neutrophil binding to GMP-140. Mg2+ also alters the conformation of the protein, but not in a manner that will support leukocyte recognition in the absence of Ca2+. There is a strong correlation between the Ca2+ levels required for neutrophil adhesion to GMP-140, for occupancy of the two Ca(2+)-binding sites, for the fluorescence-detected conformational change, and for exposure of the antibody epitope in the lectin domain. We conclude that binding of Ca2+ to high affinity sites on GMP-140 modulates the conformation of the lectin domain in a manner that is essential for leukocyte recognition.     

抗HIV-1 gp160独特型阳性抗体的序列分析及表达

为了确定从噬菌体抗体文库中筛选出的抗体的属性和方便目的基因的表达及其产物的纯化,对两株具有“１Ｆ７”独特型的抗ＨＩＶ－１ｇｐ１６０抗体基因进行了序列分析并构建了可溶性表达载体．发现３Ｂ株含有完整的Ｆａｂ段,１Ｄ株只有重链Ｆｄ段．序列测定表明两株克隆的Ｆｄ段基因完全相同,其可变区ＶＨ属于ＶＨⅠ亚群,而３Ｂ株的“轻链”序列与已知的人的κ和λ轻链无同源性．用从另外的Ｆａｂ抗体文库中筛选出来的３株抗乙肝表面抗原抗体的轻链与３Ｂ的重链重组,并选择一个ＨＩＶ－１ｇｐ１６０特异性较好的重组抗体株,命名为３Ｂｓ．构建了１Ｄ株与３Ｂｓ株的可溶性表达载体,免疫印迹实验证实了具有“１Ｆ７”独特型的抗ｇｐ１６０独特型阳性抗体的表达．     

Repetitive Transcranial Magnetic Stimulation Applications Normalized Prefrontal Dysfunctions and Cognitive-Related Metabolic Profiling in Aged Mice

Chronic high-frequency repetitive transcranial magnetic stimulation (rTMS) is a noninvasive brain stimulation technique that has recently received increasing interests as a therapeutic procedure for neurodegenerative diseases. To identify the metabolism mechanism underlying the improving effects of rTMS, we observed that high frequency (25Hz) rTMS for 14 days could reverse the decline of the performance of the passive avoidance task in aged mice. We further investigated the metabolite profiles in the prefrontal cortex (PFC) in those mice and found that rTMS could also reverse the metabolic abnormalities of gamma-aminobutyric acid, N-acetyl aspartic, and cholesterol levels to the degree similar to the young mice. These data suggested that the rTMS could ameliorate the age-related cognitive impairment and improving the metabolic profiles in PFC, and potentially can be used to improve cognitive decline in the elderly.     

背角无齿蚌晶杆的扫描电镜观察

本文应用扫描电镜的方法,对背角无齿蚌的晶杆进行了研究。结果表明：晶杆外形似圆柱状,可分为二部分,即前端膨大的头部和其后渐细的杆状部。前者分左右两瓣,略弯曲,与杆状部形成一个锐角,表面呈“蜂窝状”,似一种膜性结构,其上吸附有大量的消化酶和粘液;后者两侧有凹槽,表面具许多凹陷小坑,多为圆形或卵圆形,大小不一,深浅不同,且排列不规则。未凹陷处也粗糙不平。晶杆的功能主要是搅拌和消化食物。同时,本文对晶杆结构与功能的关系也进行了讨论。     

噬菌体抗体文库的构建及人源抗HIV-1 gp 160抗体的筛选

构建人源噬菌体抗体文库如下：ＨＩＶ感染者脾细胞中提取ｍＲＮＡ,经反转录再以人ＩｇＧ重链Ｆｄ两端及轻链“通用”引物分别扩增Ｆａｂ基因片段,依次插入到噬菌粒载体ｐＣｏｍｂ３中,电转化大肠杆菌ＸＬ１－Ｂｌｕｅ,经辅助噬菌体救助,重组噬菌体得以溶源裂解,Ｆａｂ表达于噬菌体包膜蛋白Ⅲ的Ｎ端．此噬菌体抗体库的容量为５×１０５．筛选抗ＨＩＶ－１同时又具有能被抗独特型抗体“ＩＦ７”所识别的独特型的阳性抗体：以重组包膜糖蛋白ｇｐ１６０及ｇｐ４１多肽对噬菌体抗体文库进行三次淘选,使抗ｇｐ１６０的特异性抗体得到１００倍的富集．然后通过直接ＥＬＩＳＡ和竞争性ＥＬＩＳＡ实验筛选出两株结合性较好的特异性抗ｇｐ１６０抗体－３Ｂ株与１Ｄ株．直接ＥＬＩＳＡ实验表明这两株克隆均能被“１Ｆ７”所识别,为抗独特型多肽的筛选奠定了基础．     

蜜蜂寿命可塑性研究进展

蜜蜂是一种完全社会化的昆虫,它们在寿命方面表现出了显著的级型差异.蜂王的平均寿命是1～2年,而工蜂在生产季节平均寿命是30～40 d,越冬季节平均寿命是90～200d,显然蜜蜂寿命有可塑性.这种可塑性是由环境因素控制,因为蜂王和工蜂的遗传基础是一致的.另外工蜂任务可以发生逆转,这意味着老化的逆转.本文综述了近年来一些老...     

神经细胞粘附分子与硫酸化氨基聚糖在神经发育、轴突生长、突触可塑性及学习和记忆中的作用

神经细胞粘附分子（neural cell adhesion molecule,NCAM)是一种主要表达于神经系统的糖蛋白,通过亲同性及亲异性结合介导细胞与细胞与细胞外基质间的相互作用,参与细胞的识别,迁移,轴突生长,细胞信号转导,学习和记忆等过程。硫酸化氨基聚糖可调节脑发育中的细胞分化,轴突生长及中枢神经系统中神经元的再生,可能参与了与学习和记忆相关的神经结构功能的调节。这些作用可能与神经细胞粘附分子的亲异性结合有关。     

The interaction between viral protein and host actin facilitates the virus infection to host

Although the virus-host interaction has attracted extensive studies, the host proteins essential for virus infection remain largely unknown. To address this issue, the shrimp Penaeus stylirostris densovirus (PstDNV), belonging to the family Parvoviridae, was characterized. PstDNV, a single-stranded DNA virus with a 3.9-kb genome, encoded only three open reading frames (ORFs). Among the three viral proteins, the PstDNV ORF2-encoded protein was discovered to interact with the shrimp actin, suggesting that the host actin played a very important role in virus infection. The RNAi assays revealed that the ORF2-encoded protein was required for the PstDNV infection. The confocal evidence demonstrated that the interaction between the ORF2-encoded protein and actin was essential for the virus infection. Therefore our study indicated that the manipulation of the host actin cytoskeleton was a necessary strategy for viral pathogens to invade host cells.