胁迫处理对林生山黧豆蛋白质多肽及其含量的影响

应用二维电泳技术,分析了经水分胁迫（ＰＥＧ）、盐分胁迫（ＮａＣｌ）和热激（４０℃）处理后林生山黧豆（ＬａｔｈｙｒｕｓｓｙｌｖｅｓｔｒｉｓＬ．）体内蛋白质多肽及其含量的变化。有些蛋白质经ＰＥＧ、ＮａＣｌ和热激处理后可以产生相同的变化。两种不同的胁迫因子对某些蛋白质的影响有一定的共同性。特定的胁迫条件可以造成特定的影响。不同胁迫因子对同一蛋白质多肽可以造成不同的影响。胁迫下蛋白质的变化可能与林生山黧豆抵抗和适应胁迫条件的能力以及体内非蛋白质氨基酸的代谢有关     

Characterization of phospholipase A2 activation by plasmin in cultured bovine endothelial cells

Treatment of cultured bovine carotid artery endothelial cells with 0.1 µM human plasmin has been reported to induce a receptor-mediated short burst of arachidonate release, which is a pertussis toxin-sensitive and extracellular calcium-dependent reaction. Plasmin-induced calcium influx in cells was significantly inhibited by pretreatment with pertussis toxin, indicating that the former was coupled with a pertussis toxin-sensitive guanosine 5-triphosphate (GTP)-binding protein. Plasmin significantly induced the formation of lysophosphatidylcholine but not lysophosphatidylethanolamine. A cellular phospholipase A₂ with an arachidonyl specificity at the sn-2 position of phosphatidylcholine, which required submicromolar calcium, was identified as a cytosolic phospholipase A₂ by immunoblot analysis. By a cell-free enzyme activity assay and immunoblot analysis, plasmin was found to induce a translocation of the cytosolic phospholipase A₂ from the cytosol to the membrane. Taken together, the results suggest that plasmin bound to its putative receptor and activated a GTP-binding protein coupled to calcium influx channel, followed by translocation and activation of cytosolic phospholipase A₂ in endothelial cells.     

Detection of truncated virus particles in a persistent RNA virus infection in vivo.

Infectious hematopoietic necrosis virus (IHNV) is a rhabdovirus which causes devastating epizootics of trout and salmon fry in hatcheries around the world. In laboratory and field studies, epizootic survivors are negative for infectious virus by plaque assay at about 50 days postexposure. Survivors are considered virus free with no sequelae and, thus, are subsequently released into the wild. When adults return to spawn, infectious virus can again be isolated. Two hypotheses have been proposed to account for the source of virus in these adults. One hypothesis contends that virus in the epizootic survivors is cleared and that the adults are reinfected with IHNV from a secondary source during their migration upstream. The second hypothesis contends that IHNV persists in a subclinical or latent form and the virus is reactivated during the stress of spawning. Numerous studies have been carried out to test these hypotheses and, after 20 years, questions still remain regarding the maintenance of IHNV in salmonid fish populations. In the study reported here, IHNV-specific lesions in the hematopoietic tissues of rainbow trout survivors, reared in specific-pathogen-free water, were detected 1 year after the epizootic. The fish did not produce infectious virus. The presence of viral protein detected by immunohistochemistry, in viral RNA by PCR amplification, and in IHNV-truncated particles by immunogold electron microscopy confirmed the presence of IHNV in the survivors and provided the first evidence for subclinical persistence of virus in the tissues of IHNV survivors.     

Predictions of protein backbone bond distances and angles from first principles

A procedure is described, based on a spline-function representation of ab initio peptide conformational geometry maps, that allows one to predict backbone bond distances and angles of proteins as functions of the peptide ?(N-C^α)/Ψ(C^α-C′) torsions with an accuracy comparable to that of high-resolution protein crystallography. For example, for the more than 40 residues of crambin, the rms deviation between predicted and crystallographic values of N-C^α-C′ is 1.9° for the 1.5 Å resolution structure and 1.9° for the 0.83 Å resolution structure, compared with angle variations of < 10°. Accurate information on protein backbone geometries is important for establishing dictionaries of flexible geometry functions for use in empirical peptide and protein modeling. © 1995 John Wiley & Sons, Inc.     

Sucrose consumption in mice: Major influence of two genetic Loci affecting peripheral sensory responses

Individual variability in sucrose consumption is prominent in humans and other species. To investigate the genetic contribution to this complex behavior, we conducted behavioral, electrophysiological, and genetic studies, using male progeny of two inbred mouse strains (C57BL/6ByJ [B6] and 129/J [129]) and their F₂ hybrids. Two loci on Chromosome (Chr) 4 were responsible for over 50% of the genetic variability in sucrose intake. These loci apparently modulated intake by altering peripheral neural responses to sucrose. One locus affected the response threshold, whereas the other affected the response magnitude. These findings suggest that the majority of difference in sucrose intake between male B6 and 129 mice is due to polymorphisms of two genes that influence receptor or peripheral nervous system activity. Received: 27 January 1997 / Accepted: 17 March 1997     

Construction of an ∼2 Mb contig in the region around 80 cM of Arabidopsis thaliana chromosome 2

A method for construction of bacterial artificial chromosome (BAC) contigs from a yeast artifical chromosome (YAC) physical map is described. An ∼2 Mb contig, consisting of two large BAC contigs linked by a small YAC, has been assembled in the region around 80 cM of Arabidopsis thaliana chromosome 2. Clones from this contig will facilitate gene isolation in the region and can be used directly as substrates for DNA sequencing.     

西藏南迦巴瓦峰地区孟加拉虎的初步研究

１９９４年５～６月、９～１０月及１９９５年６～１２月,作者对西藏东南部南迦巴瓦峰和邻近地区的孟加拉虎的分布及生态进行了野外调查,初步弄清了该地区虎的现状。通过在墨脱县格当乡的抽样调查及跟踪观察虎的移动和觅食,查明了金珠藏布江流域内近两年有关虎捕食大型牲畜的报告属实。１９９３年１０月至１９９５年７月,该河谷内因虎捕食共损失牛、马和骡３０２头,估计活体总重量约５９８８１ｋｇ,平均月损失２７２２ｋｇ,相当于自然状态下１１头虎的月进食量。全乡１２个村的牲畜均受到不同程度的影响,受损的户数占该乡总户数的６２％,户牲畜损失率为７．７％～１００％不等。对其它动物的调查表明,虎大量捕食牲畜与低海拔河谷的开发和环境中虎的自然食物缺乏有关     

兔感觉神经特异蛋白的纯化及稳定性观察

以兔脊神经节及背根纤维为材料,通过制备匀浆,DEAE-Sephacel阴离子交换层析,高压液相凝胶过滤层析分离纯化了感觉神经特异蛋白29 ku,并进行了该蛋白的稳定性观察.