麻黄碱抑制小鼠输精管电场刺激致收缩的机制

麻黄碱(10 nmol/L~(-0.1) mmol/L)对电场刺激所致输精管收缩的浓度依赖性抑制作用可被育亨宾(0.1 μmol/L)减弱。去甲肾上腺素(0.1 nmol/L~(-10)μmol/L )和酪胺(0.1 μmol/L~(-0.1) mmol/L)也有类似麻黄碱的作用,去氧肾上腺素则缺乏此种作用。利血平处理和可卡因(10 μmol/L)可减弱麻黄碱和酪胺的抑制效应,但能增敏去甲肾上腺素的作用。高 Ca~( )和4-氨基吡啶(50 μmol/L)明显减弱甚至取消麻黄碱对电场刺激的抑制效应。以上结果提示麻黄碱抑制电场刺激所引起的输精管收缩。至少部分通过促进神经末梢释放去甲肾上腺素间接作用,后者激动突触前α_2-肾上腺素受体,从而抑制去甲肾上腺素的进一步释放。麻黄碱和其释放的去甲肾上腺素的作用,又可能与阻遏 Ca~( )内流有关。     

在北纬24°以南的云南永德县发现白蜡虫自然种群

白蜡虫Ericerus pela Chavannes是我国温带重要的林业资源昆虫,其雄虫所产的蜡是轻、重工业,医药等不可缺少的原料,它又是我国传统的出口物资。 关于中国白蜡虫的分布,王辅(1963,1978)认为:在北纬26°以南地区白蜡虫不适其生存。我们于1982年12月—1983年9月,对云南省永德县进行了考察,其结果如下。     

Resonance Raman spectra of the heme in leghemoglobin. Evidence for the absence of ruffling and the influence of the vinyl groups

Resonance Raman spectra of deoxy and carbonmonoxy leghemoglobin (Lb) are compared to the corresponding forms of human adult hemoglobin (HbA). It is found that the heme "core size" indicator line has nearly the same frequency for the two deoxyhemoglobins and the pi-electron density-sensitive line also falls at the same frequency. However, several other modes occur at very different frequencies in the spectra of the two proteins. From an examination of the spectrum of an HbA derivative in which the beta-carbon atoms of the heme vinyl groups were deuterated, it appears that the major differences between deoxy-HbA and -Lb may result from conformational changes in the vinyl groups. No evidence for the suggested ruffling (Irwin, M. J., Armstrong, R. S., and Wright, P. E. (1981) FEBS Lett. 133, 239-243) in deoxy-Lb was found. The spectra of carbonmonoxy-Lb and -HbA were also found to be very different. As in the deoxy case, some of these frequency differences could be attributed to vinyl group conformational differences. However, from the large difference in the pi-electron density-sensitive line, it appears that the vinyl pi-conjugation into the porphyrin in Lb(CO) may be different than it is in HbA(CO). The vinyl conformational differences may be a consequence of the looser heme pocket in Lb than in HbA. The difference in pi-conjugation could make a significant contribution to the difference in ligand binding affinity for these two globins.     

蚕豆叶片发育与衰老过程中超氧物歧化酶活性与丙二醛含量变化

蚕豆植株叶片随茎节自上而下表现出明显的发育与衰老顺序,可作为衰老特征的是叶绿素和蛋白质含量明显下降。蚕豆叶中SOD活性主要定位于12 000× g离心后所得的上清液和叶绿体组分。衰老叶片的SOD总活性和叶绿体组分的相对活性都有所下降,SOD同工酶谱也发生了改变。O_2~ 产生速率随叶龄增大而稍上升;而MDA含量在叶片外观表现枯黄衰老征兆前就急剧上升。可能因为衰老叶片过氧化氢酶活性大幅度下降与SOD之间的不平衡,致使O_2~ 代谢中间产物累积而引起膜的损伤.     

酪氨酸对人离体滋养层细胞孕酮与hCG分泌的影响

本文观察三种剂量(2×10~(-5)mol/L,2×10~(-4)mol/L和2×10~(-3)mol/L)的酪氮酸对离体培养的滋养层细胞孕酮及hCG分泌的影响,并对其抑制效应的机理作了初步探讨。实验结果表明,三种剂量的酪氨酸均可抑制滋养层细胞孕酮分泌(P<0.01),但是,在孕酮分泌受酪氨酸抑制的同时,未见对hCG分泌发生影响(P>0.05),进一步观察了酪氨酸对滋养层细胞3β-羟甾脱氢酶活性的影响,结果表明,酪氨酸能显著抑制3β-羟甾脱氢酶活性,提示酪氨酸对滋养层细胞孕酮生成的抑制作用与抑制3β-羟甾脱氢酶活性有关。     

Tyrosine-7 is an essential residue for the catalytic activity of human class PI glutathione S-transferase: chemical modification and site-directed mutagenesis studies.

The glutathione (GSH)-conjugating activity of human class Pi glutathione S-transferase (GST pi) toward 1-chloro-2,4-dinitrobenzene (CDNB) was significantly lowered by reaction with N-acetylimidazole, an O-acetylating reagent for tyrosine residues. Further, the replacement of Tyr7 in GST pi, which is conserved in all cytosolic GSTs, with phenylalanine by site-directed mutagenesis also lowered the activities toward CDNB and ethacrynic acid. The Km values of the mutant for both GSH and CDNB were almost equivalent to those of the wild type, while the Vmax of the former was about 55-fold smaller than that of the latter. Therefore, Tyr7 is considered to be an essential residue for the catalytic activity of GST pi.     

四节金小蜂科在我国的首次发现并记述一新种(膜翅目:小蜂总科)

四节金小蜂科Tetracampidae是小蜂总科中的1个小科。1968年统计,全世界只有2亚科6属18种(Boucek and Askew,1968)。1971年,苏联的Sugonjaev根据在蒙古和苏联的哈萨克加盟共和国采到的标本描述了3新属1新亚科。Boucek于1988年又记述了澳大利亚的1个新属。这样,四节金小蜂科现在共包括3亚科10属31种(不含化石种)。我国迄今还未见有本科昆虫分布的报道。     

内蒙古草蛉研究Ⅱ.五新种及二新记录种(脉翅目:草蛉科)

内蒙古地处我国北部边疆,全境以高原为主,西部为戈壁沙漠,东部为宽阔草原,绝大多数地区属于温带大陆性气候;动物地理区划属于古北区中亚细亚区的内蒙河西干草原区。该区现已知草蛉3属16种(包括本文所记述的5新种和2新记录种),其分布特点是以狭义的草蛉属Chrysopa为主,而且以广布于华北地区的叶色草蛉Chrysopaphyllochroma Wesmeal为代表种,新种的模式标本分别保存在中国科学院动物研究所及北京农业大学昆虫标本室。     

Construction and packaging of pseudotype retrovirus containing human N—ras cDNA antisense sequence and its biological effects on human hepatoma cells

N-ras is one of the transforming genes in human hepatic cancer cells.It has been found that N-ras was overexpressed at the mRNA and protein level in hepatoma cells.In order to explore the biological roles of N-ras in human hepatic carcinogenesis and the potential application in control of cancer cell growth,a preudotype retrovirus containing antisense sequence of human N-ras was constructed and packaged.A recombinant retrovirus vector containing antisense or sense sequences of N-ras cDNA was constructed by pZIP-NeoSV(X)1.The pseudotype virus was packaged ang rescued by transfection and infection in PA317 and ψ 2 helper cells.It has been demonstrated that the pseudotype retrovirus containing antisense N-ras sequence did inhibit the growth of human PLC/PRF/5 hepatoma cells accompanied with inhibition of p21 expression,while the retrovirus containing sense sequence had none.The pseudotype virus had no effect on human diploid fibroblasts.     

萝卜离体子叶衰老与膜脂过氧化的关系

萝卜离体子叶在光下或暗中衰老及激素调节衰老过程中,作为叶片衰老指标的叶绿素和蛋白质含量的降低,发生在MDA含量增高之前,更早于SOD活性的下降。表明由SOD活性降低所导致的膜脂过氧化的增强,并非衰老的原初反应,而是叶片衰老到一定程度的生理变化。因此,至少在萝卜离体子叶上,不能将其衰老的启动归因于受SOD控制的膜脂过氧化作用导致的膜累积性质变。