Kuwanon W,a natural Diels—Alder type adduct from the root bark of Morus lhou

A natural Diels—Alder type adduct, named kuwanon W, was isolated from ethyl acetate extracts of the root bark of cultivated mulberry tree, and its structure was determined on the basis of spectral and chemical evidence. Kuwanon W is regarded biogenetically as a Diels—Alder adduct of a chalcone derivative and dehydroprenyl-flavone.     

塔里木板块西南依格孜牙剖面上泥盆统—下石炭统地层学

塔里木板块西南英吉莎县依格孜牙出露上泥盆统—下石炭统序列。克里塔格组下段以法门阶牙行刺Icriodus alternatus alternatus为特征,中段的Spathognathodus aciedentatus和Polygnathus inornatus属杜内阶上部,上段的Scaphignathus sp.大致相当于维宪阶,可能还包括部分谢尔普霍夫阶。岩相序列表明,从奇自拉夫组紫红色石英砂岩、含砾石英砂岩相变为克里塔格组台地浅海相碳酸盐岩指示一次海进过程,克里塔格组礁灰岩可视为大灭绝事件之后全球最早的珊瑚礁群落复苏代表实例之一。     

蓝舌病毒HbC株与不同种系细胞相互作用及群特异性抗原特征

BTV-HbC株和蓝舌病毒标准株BTV-10分别接种在不同种系细胞如猴肾传代细胞(Vero)、人宫颈癌细胞(Hela)和小鼠神经胶质瘤细胞(C6)等细胞株上,比较研究了BTV-HbC在不同种系细胞上的增殖特征,BTV-HbC与BTV-10在相同细胞上的复制增殖特征,病毒与细胞相互作用的显微和超微结构特征.用免疫交叉反应研究了BTV-HbC株与BTV-10型标准株之间的血清学关系.本研究结合本室对BTV-HbC株基因组图谱分析和蓝舌病毒群特异性抗原编码基因S7的RT-PCR分析,进一步证实了BTV-HbC株可能是一个新的血清型蓝舌病毒.     

恒河猴外周血及肾组织SV40病毒基因分析

SV40即猿猴病毒40(simian virus 40),是DNA肿瘤病毒的原型代表,其基因结构为共价闭合环状双股DNA分子,标准参考株SV40-776含5243个核甘酸,不同分离株bp数略有差异.     

大豆蚜嗅觉在选择寄主植物中的作用

大豆蚜 Aphis hlycines 有翅和无翅孤雌生殖蚜为其寄主植物大豆叶和鼠李叶气味所引诱,而非寄主植物棉花叶和黄瓜叶气味处于中性,丝瓜叶和南瓜叶气味具有明显的排斥作用。非寄主植物气味可以遮蔽寄主植物气味的引诱作用。大豆蚜触角感受器对植物气味具有嗅觉生理反应,对一些化合物的最小感觉阈值达10-5至10-6体积比浓度,表明大豆蚜触角上存在识别植物气味的嗅觉受体细胞。由此证明,嗅觉在大豆蚜选择寄主植物过程中起重要作用。     

一步法扩增克隆IBDV上海超强毒VP2-4-3基因

分离、纯化了鸡传染性法氏囊病病毒超强毒 (vvIBDV) 上海株SH95的病毒核酸dsRNA,应用随机引物将RNA反转录成cDNA,以此为模板一步扩增出A片段前体融合蛋白基因即VP2-4-3基因,将其克隆入pGEM-T载体,并进行序列分析,其与超强毒株HK46的核苷酸序列的同源性达98%,整个基因有5个氨基酸差异,同源性达99.51%(1007/1012).     

Effect of Tooth Removal on Recaptures of Raccoons

Abstract: Researchers have extensively used mark—recapture techniques to obtain information on demographic parameters of wildlife populations. However, researchers have recognized that a number of factors can influence capture probabilities of wildlife species, which in turn can bias mark—recapture estimates of demographic parameters. Tooth extraction, which is a commonly used technique in studies of mesopredator species to obtain precise age estimates and to monitor the use of vaccine baits, is an aspect of animal handling that clearly might affect the recapture probability of individuals. However, the effect that tooth removal has on the individual recapture probabilities of wildlife species is unknown. During 2005, we trapped and marked 91 raccoons (Procyon lotor) in northern Indiana, USA, as part of a mark—recapture study designed specifically to determine if tooth extractions have an effect on recapture probabilities of individuals. We performed tooth extractions on 50% of the raccoons at the time of capture, and we attempted to balance tooth extractions with respect to sex and age of raccoons. We used logistic regression to model the effects of sex, age, and tooth removal on recapture probabilities, and we used Mann—Whitney U-tests to examine the effect of tooth removal on the number of times we recaptured individuals. The probability of recapture differed between sexes but did not differ as a function of tooth removal or among age classes. In addition, we failed to detect any difference in the mean number of times that we recaptured raccoons between the tooth removed and non—tooth-removed groups. Our results suggest that managers can use tooth extractions as an effective management tool without biasing population estimates or compromising other management objectives.     

The first world swimming championships of roseobacters—Phylogenomic insights into an exceptional motility phenotype

Many marine Alphaproteobacteria of the Roseobacter group show a characteristic swim-or-stick lifestyle, for which motility is a crucial trait. Three phylogenetically distinct flagellar gene clusters (FGCs) have been identified in Rhodobacteraceae that have been named fla1, fla2 and fla3 according to their relative abundance. In addition to the flagellar-dependent swimming and swarming motility, pilus-dependent twitching mediates bacterial locomotion. Furthermore, filament independent modes of motility, namely gliding and sliding, have been described for various microorganisms. However, no mode of motility other than swimming has so far been described for roseobacters. In the present study, we investigated motility, distribution of flagellar systems and the phylogeny of 120 genome-sequenced Rhodobacteraceae. The phylogenetically broad taxon sampling that included 114 type strains revealed the presence of at least ten distinct clades that were statistically well supported. The investigation of the actual physiological capacity for swimming motility on soft agar plates showed that only about half of the 120 tested strains were motile under the tested conditions. Seven strains developed a conspicuous dendritic motility phenotype that was reminiscent of the swarming motility in Pseudomonas aeruginosa. The observed dendritic motility in two strains (i.e. Sulfitobacter pseudonitzschiae DSM 26842 and Roseovarius pacificus DSM 29589) was particularly surprising because they did not harbor any genes of the FGC. Accordingly, it was concluded that this form of dendritic motility was independent of a flagellum. A comparative genomics approach allowed a remarkable number of pilus-related candidate genes to be identified for this novel type of motility in Rhodobacteraceae.