基于多种描述参数的嗜盐古菌Haloarcula hispanica基因组密码子偏好性分析

进化是生物最本质的特征,一直以来,密码子偏好分析是基因组进化研究领域的热点命题之一.文中以极端嗜盐古菌Haloarcula hispanica基因组为研究对象,基于不同密码子偏好描述参数对该基因组大、小染色体及质粒的蛋白质编码基因中密码子使用特点进行了系统研究.结果表明Haloarcula hispanica基因组各组分蛋白质编码基因倾向使用以G/C结尾的密码子,在偏好的26个密码子中只有两个密码子的使用在大、小染色体和质粒之间存在差异.进一步基于多种描述参数的对应分析发现大、小染色体中各参数的相关系数存在相似性,而与质粒则出现了较大的差异,这可能与三者之间的进化关系有关,因而该工作为今后原核生物大小染色体与质粒之间进化关系的研究提供了可靠依据.     

SARS及其他几种冠状病毒密码子使用偏性的位点差异

分析了SARS冠状病毒以及其他5种冠状病毒基因编码起始区与终止区的密码子使用偏性.结果表明,冠状病毒基因组的稀有密码子倾向于出现在编码起始区和终止区附近.起始区的这种倾向性对冠状病毒基因的表达具有负性调控作用,可以用"稀有密码子调控假说"解释.终止区的这种倾向性表明,这些出现在终止区的稀有密码子对基因的表达也有负性调节作用.研究结果同时暗示了"稀有密码子调控假说"不仅适用于细菌,而且还适用于某些病毒基因组.     

Accumulation of 1-deoxynojirimycin in silkworm, <Emphasis Type="Italic">Bombyx mori</Emphasis> L.

1-deoxynojirimycin (1-DNJ) contents in the silkworm,Bombyx mori,at different developmental stages and tissues were investigated by using reverse-phase high-performance liquid chromatography. The 1-DNJ contents of silkworm larvae change significantly with their developmental stages. The male larvae showed higher accumulation efficiency of 1-DNJ than the females and also a significant variation was observed among the silkworm strains. The present results show that tissue distribution of 1-DNJ was significantl...     

Effect of serum concentration on adhesion of monocytic THP-1 cells onto cultured EC monolayer and EC-SMC co-culture

Background:The adhesion of monocytes to the endothelium following accumulation oflow-density lipoprotein(LDL) in subendothelial spaces is an important step in the development of intimal hyperplasia in arterially implanted vein grafts and atherosclerosis in both animals and humans.However.it iS not well known how serum factors affect the adhesion of monocytes.Methods:We have studied the efrect of fetal calf serum(FCS).which we considered a source of LDL.on the adhesion of monocytes to endothelial cells(Ecs)by using human monocytic THP-1 cells and both a monolayer of cultured bovine aortic endothelial cells(EC monoculture)and a co-culture with bovine aortic smooth muscle cells(EC-SMC co-culture).Results:It was found that the addition of FCS to the medium greatly affected the adhesion of THP-1 cells,and the higher the concentration of FCS in the medium,the greater the adhesion of THP-1 cells to endothelial cells.Adhesion of THP-1 cells to an EC-SMC co-culture Was approximately twofold greater than that to an EC monoculture,and after adhering to endothelial cells,many THP-1 cells transmigrated into the layer of smooth muscle cells.Conclusion:The results suggest that the elevation of the LDL(cholesterol)level in blood provides a favorable condition for the development of intimal hyperplasia and atherosclerosis by promoting the adhesion of monocytcs to the endothelium and their subsequent migration into subendothelial spaces.