鳋科（寄生桡足类）胸板的扫描电镜比较研究

本文利用扫描电镜观察了我国鳋科的5个属的种类。首次发现在它们的胸部腹面游泳足连接板之下均有一板状结构,其形状与栉齿的着生情况在不同属之间存在着明显的差异,同属不同种之间也不尽相同,这是一个过去未曾被注意过的结构,权且称之为胸板。它是一个独立的结构,不与连接板相连。胸板上的栉齿从形态-功能-适应三位一体分析,它与附着寄主有夭,以免被水流冲走,与无栉齿的相比,应是一个进步性状。     

武陵山地区的淡水软体动物

1988—1989年在我国西南武陵山地区对乌江、清江、澧水及沅江四大水系进行了资源考察。共采集到标本53种,隶属2纲12科27属,其中腹足纲41种,瓣鳃纲12种,内有7个新种(另外发表)。淡水软体动物的区系组成以东洋界种类占优势,有29种,占总数的54.8％;种类组成以沅江水系最多,有44种,其中22种仅采于沅江。田螺属(Viviparus Montfort,1810)的种类首次在东洋界境内被发现。文章对淡水软体动物的资源作了评价,并对寄生虫媒介贝类进行了叙述。     

白鹇距长与年龄的关系

注意到白鹧雄鸟距长在一定时期内随年龄增长的事实,本文根据相邻2年同一月龄之间有12个月的间隔,距长数据除有较为集中外一定又有组间明显差别的特点,推测估计部分标本之年龄,加上确知年龄的部分标本,共测定89个个体120个距长样本数据,得到距长随年(月)龄增长的关系式:SL=am/1+bm,用此式可以实测距长初步估计野外采集到的白鹇个体的年龄     

中国特产雉类—褐马鸡,藏马鸡和蓝马鸡卵壳的电镜观察

迄今为止,在国内有关野生鸟类卵壳的超微结构报道尚少。我们对中国特产鸡类——三种马鸡卵壳的表皮、气孔、木栅层、锥体层、乳头结、壳膜和基帽进行了扫描巨镜观察,并对结果进行了比较、讨论。认为三种马鸡不同结构的形态,对研究它们的亲缘关系提供了新的价值。     

Two-dimensional NMR, circular dichroism, and fluorescence studies of PP-50, a synthetic ATP-binding peptide from the beta-subunit of mitochondrial ATP synthase.

PP-50, a peptide based on residues 141-190 of the beta-subunit of mitochondrial F1-ATPase, contains the GX4GKT consensus region for nucleoside triphosphate binding and has been shown to bind ATP [Garboczi, D.N., Shenbagamurthi, W.K., Hullihen, J., & Pedersen, P.L. (1988) J. Biol. Chem. 263, 812-816]. At pH 4.0, appropriate for NMR studies, PP-50 retains the ability to bind ATP tightly (KD = 17.5 microM) with a 1:1 stoichiometry as shown by titrations measuring the partial quenching of ATP fluorescence by PP-50. CD spectra of PP-50 at pH 4.0 and at low ionic strength show 5.8% helix, 30.2% beta-structure, and 64% coil. ATP binding increases the structure of PP-50, changing the CD to 7.5% helix, 44.5% beta-structure, and 48% coil. Increasing the ionic strength to 50 mM KCl also increases the structure, changing the CD to 7.4% helix, 64.4% beta-structure, and 28.2% coil. The 600-MHz proton NMR spectrum of PP-50, at pH 4.0 and low ionic strength, has been assigned by 2D methods (TOCSY, DQF-COSY, and NOESY with jump-return water suppression). Based on strong d alpha N NOEs, J alpha N values, and NH chemical shifts differing from random coil values, regions of extended structure are detected from residues 1-7 and 43-48. Based on dNN, dNN(i,i+2), and d alpha N(i,i+2) NOEs and 3J alpha N values, possible type I' and type I turns are found from residues 11-14 and 31-34, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Production of ethylene by gravistimulation: a potential problem with the interpretation of data from some experimental techniques

Abstract. Gravistimulation was investigated as a potential and unwanted component in the interpretation of physiological investigations on plants. Using both seedlings and mature sunflower plants, two situations are described where gravistimulation contributes significantly to the outcome of an experiment not initially designed to include this parameter. The number of adventitious roots formed in derooted seedings decreased when the tops of the plants were allowed to bend over under their own weight, and the effect correlated positively with the rate of ethylene production by non-vertical stems. In droughted mature plants, and increase in leaf and stem ethylene caused by water stress was supplemented by additional ethylene produced in the lower halves of stems. Drought had caused these stem tissues to wilt, become gravistimulated, and thus produce more ethylene. Other situations in which gravistimulated ethylene production and its physiological consequences are likely to be complicating factors in experiments are discussed. It is concluded that procedures that unnecessarily place experimental material in non-vertical orientations should be avoided.     

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.     

腐霉属分类性状评价及其中国的种

本文对腐霉属Pythium Pringsheim的研究历史作了简单的回顾,对该属的分类性状和系统进行了论述和评价,最后对中国已发现的55种腐霉,以检索表的方式进行了分类、检索。     

Evidence that Glyceraldehyde-3-Phosphate Dehydrogenase Is Involved in Age-Induced Apoptosis in Mature Cerebellar Neurons in Culture

Abstract: Under typical culture conditions, cerebellar granule cells die abruptly after 17 days in vitro. This burst of neuronal death involves ultrastructural changes and internucleosomal DNA fragmentations characteristic of apoptosis and is effectively arrested by pretreatment with actinomycin-D and cycloheximide. The level of a 38-kDa protein in the particulate fraction is markedly increased during age-induced cell death and by pretreatment with NMDA, which potentiates this cell death. Conversely, the age-induced increment of the 38-kDa particulate protein is suppressed by actinomycin-D and cycloheximide. N-terminal microsequencing of the 38-kDa protein revealed sequence identity with glyceraldehyde-3-phosphate dehydrogenase (GAPDH). A GAPDH antisense oligodeoxyribonucleotide blocks age-induced expression of the particulate 38-kDa protein and effectively inhibits neuronal apoptosis. In contrast, the corresponding sense oligonucleotide of GAPDH was completely ineffective in preventing the age-induced neuronal death and the 38-kDa protein overexpression. Moreover, the age-induced expression of the 38-kDa protein is preceded by a pronounced increase in the GAPDH mRNA level, which is abolished by actinomycin-D, cycloheximide, or the GAPDH antisense, but not sense, oligonucleotide. Thus, our results suggest that overexpression of GAPDH in the particulate fraction has a direct role in age-induced apoptosis of cerebellar neurons.     

Inhibition of Excitatory Amino Acid-Induced Phosphoinositide Hydrolysis as a Possible Mechanism of Nitroprusside Neurotoxicity

Abstract: Inclusion of sodium nitroprusside {Na₂[Fe²⁺-(CN)₅NO]} into the culture medium is toxic to cultured rat cerebellar granule neurons. A possible underlying mechanism may be the inhibition of phosphoinositide (PI) response to excitatory amino acids (EAAs) because activation of glutamate receptors can be neuroprotective and neurotrophic in differentiating neurons. Sodium nitroprusside selectively inhibited the PI response to EAAs (NMDA > glutamate = quisqualate > kainate) without affecting that to carbachol or KCI. In contrast, S-nitroso-N-acetylpenicillamine (SNAP), another nitric oxide (NO) donor, potentiated NMDA-induced PI hydrolysis. Hemoglobin reversed the effects of nitroprusside and SNAP. However, NO may not be involved because NO solution was without effect and N-acetylpenicillamine, a SNAP analogue that does not contain a NO moiety, also potentiated NMDA-induced PI hydrolysis in a hemoglobin-sensitive manner. Furthermore, the metabolites of NO (nitrate and nitrite), l -arginine, reduced glutathione, 8-bromo-cyclic guanosine 3′:5′-cyclic monophosphate (8-Br-cGMP), and atrial natriuretic peptide, which accelerates the production of cGMP independent of NO, were ineffective as modulators. However, potassium ferrocyanide {K₄[Fe²⁺(CN)₆]}, but not potassium ferricyanide {K₃[Fe³⁺(CN)₆]}, inhibited NMDA-induced PI hydrolysis as effectively as nitroprusside, but this inhibition was not reversed by hemoglobin. Cyanide, a product from the disintegration of nitroprusside, potentiated rather than inhibited NMDA-induced PI hydrolysis. Taken together, these results suggest that the parent molecule itself, nitroprusside, contributes primarily in inhibiting EAA-induced PI hydrolysis. Inhibition of EAA-induced PI hydrolysis may in part mediate the mechanisms of nitroprusside toxicity in primary cultures of differentiating cerebellar granule neurons.