山东淄博第四纪裂隙动物群

简要记述产自山东淄博孙家山裂隙群的主要哺乳动物化石,将之分为A、B、C三个动物群。A动物群时代与周口店第18地点相当,为早更新世早期;B动物群时代与周口店第9地点相当,为早更新世晚期;C动物群则可能与周口店第1地点中上部层位的时代相当,为中更新世中晚期。分析不同种类的生态类型并依据最小个体数的统计结果,认为早更新世早期本区为相对温湿的草原环境,附近可能有荒漠化现象;早更新世晚期气候较为温湿,无荒漠化现象;中晚更新世主要为林缘—灌丛环境,气候更为湿润。A动物群是华北地区早更新世早期特有的动物群,略具南北过渡区的特征;B动物群初具现代动物区系的面貌;C动物群基本与现代动物区系一致。     

nfi, the gene for endonuclease V in Escherichia coli K-12.

Endonuclease V is specific for single-stranded DNA or for duplex DNA that contains uracil or that is damaged by a variety of agents (B. Demple and S. Linn, J. Biol. Chem. 257:2848-2855, 1982). Thus, it may be a versatile DNA repair enzyme. The protein was purified to apparent homogeneity, and from its N-terminal sequence, its gene, nfi, was identified. nfi is immediately downstream of hemE, at kb 4208 (90.4 min) on the current chromosomal map of Escherichia coli K-12. This region was cloned, and plasmid insertion and deletion mutants were used to study its molecular organization. Although nfi is the third of four closely spaced, codirectional genes, it is expressed independently.     

Sequential action of six virus-encoded DNA-packaging RNAs during phage phi29 genomic DNA translocation.

A 120-base pRNA encoded by bacteriophage b29 has a novel and essential role in genomic DNA packaging. Six DNA-packaging RNAs (pRNAs) were bound to the sixfold symmetrical portal vertex of procapsids during the DNA translocation process and left the procapsid after the DNA-packaging reaction was completed, suggesting that the pRNA participated in the translocation of genomic DNA into procapsids. To further investigate the mechanism of DNA packaging, it is crucial to determine whether these six pRNA molecules work as an integrated entity or each pRNA acts as a functional individual. If pRNAs work individually, then do they work in sequence with communication or in random order without interaction? Results from compensation and complementation analysis did not support the integrated model. Computation of the probability of combination between wild-type and mutant pRNAs and experimental data of competitive inhibition excluded the random model while favoring the proposal that the six pRNAs functioned sequentially. Sequential action of the pRNA also explains why the pRNA is so sensitive to mutation, since the effect of a pRNA mutation will be amplified by 6 orders of magnitude after six consecutive steps, resulting in the observed complete loss of DNA-packaging activity caused by small alterations. When any one of the six pRNAs was replaced with an inactive one, complete blockage of DNA packaging resulted, strongly supporting the speculation that individual pRNAs, presumably together with other components such as the packaging ATPase gp16, take turns mediating successive steps of packaging. Although the data provided here could not exclude the integrated model completely, there is no evidence so far to argue against the model of sequential action.     

Two distinct CCR5 domains can mediate coreceptor usage by human immunodeficiency virus type 1.

The chemokine receptor CCR5 is the major fusion coreceptor for macrophage-tropic strains of human immunodeficiency virus type 1 (HIV-1). To define the structures of CCR5 that can support envelope (Env)-mediated membrane fusion, we analyzed the activity of homologs, chimeras, and mutants of human CCR5 in a sensitive gene reporter cell-cell fusion assay. Simian, but not murine, homologs of CCR5 were fully active as HIV-1 fusion coreceptors. Chimeras between CCR5 and divergent chemokine receptors demonstrated the existence of two distinct regions of CCR5 that could be utilized for Env-mediated fusion, the amino-terminal domain and the extracellular loops. Dual-tropic Env proteins were particularly sensitive to alterations in the CCR5 amino-terminal domain, suggesting that this domain may play a pivotal role in the evolution of coreceptor usage in vivo. We identified individual residues in both functional regions, Asp-11, Lys-197, and Asp-276, that contribute to coreceptor function. Deletion of a highly conserved cytoplasmic motif rendered CCR5 incapable of signaling but did not abrogate its ability to function as a coreceptor, implying the independence of fusion and G-protein-mediated chemokine receptor signaling. Finally, we developed a novel monoclonal antibody to CCR5 to assist in future studies of CCR5 expression.     

Experimental study and mechanism analysis on bioeffects by nanosecond electromagnetic pulses

The athermal bioeffects caused by nanosecond electromagnetic pulses with body cells was studied by using a broad band transverse EM-wave cell (BTEM CELL). The experimental system and preliminary mechanism analysis were presented.     

标志技术在研究小皱蝽成虫种群特征中的应用

应用标志－释放－回收技术研究小皱蝽成虫的主要种群特征,结果如下：（１）成虫扩散的偏离度Ｋｕ＝２．４,为一阶峻开曲线;（２）分别用Ｐｅｔｅｒｓｏｎ和Ｊａｃｋｓｏｎ方法对种群蜜度进行了估计,结果表明,Ｊａｃｋｓｏｎ的方法较好;（３）雄虫平均寿命４０－４５,虫平均寿命１２０－１３０。天。     

云南西部不同生境区域革螨群落的模糊聚类分析

云南西部10个不同生境区域小兽体表革螨群落经用模糊聚类分析,归并为4种群落类型：华南区室内生境型、华南区室外农耕地生境型、西南区室内生境型及西南区室外农耕地生境型。研究表明,生境的不同或在动物地理上位置的不同导致了革螨群落的差异。     

濒危植物——长喙毛茛泽泻的雌雄配子体发育

长喙毛茛泽泻 Ranalisma rostratum stapf 小孢子母细胞的减数分裂过程为连续型,四分体为左右对称型。成熟花粉为三胞花粉。花药绒毡层为变形绒毡层。雌蕊由多数单室子房构成,每子房中含一具双珠被、薄珠心的倒生胚珠。胚囊发育为葱型。成熟胚囊中三个反足细胞退化;二个极核分别位于中央细胞的两端,其体积相差明显。这种极核分布可能与反足细胞过早退化有关。     

河南新乡地区儿童头面部测量

本文对河南省新乡地区汉族儿童（４－１３岁）头面部进行了测量,比较和分析了儿童体质发育与年龄增长的关系,据儿童头面部各指数数值大小分型,确定该地区汉族儿童面部的形态为：圆头型、高头型、狭头型、狭面型、狭鼻型。     

鳗鲡爱德华氏菌病的组织病理学研究

鳗鲡爱德华氏菌病病变性质为化脓性炎症。症理分型主要有两种：化脓性肝炎型、混合型。较早发生病变部位主要在肝脏,其化脓性病杜按病程分为初、中、晚期。肾脏、脾脏、胃粘膜、体表出现散在的脓肿、脓性溃疡、炎性血栓及血斑。此外,肝脏、肾脏实质细胞均出现变性和坏列、血管充血、出血等。本文详细报告了肝脏、脾脏、肾脏的超微结构变化并初步讨论了细胞、组织损伤的过程及细胞病理学、超微病理学意义。