自发性高血压大鼠血管α1肾上腺素受体亚型的改变

本工作在离体与整体条件下比较易卒中型自发性高血压(SHRSP)大鼠与WKY大鼠血管中α_1受体的两种亚型。在离体灌流的主动脉、肾动脉与肠系膜动脉,50μmol/L氯甲基可乐定(CEC)预温育30min可使α_1受体激动时引起的最大收缩张力在SHRSP与WKY大鼠分别降为对照时的31.4±8.3％与35.2±2.9％,68.4±8.2％与80.1±7.3％,68.4±6.3％与55.4±7.0％,两者间均无显著性差别。但10μmol/L硝苯吡啶对α_1受体收缩效应的阻断作用则在SHRSP大鼠大大超过WKY大鼠,最大收缩张力分别降为对照时的3.1±1.5％与56.5±4.8％(P<0.01),9.0±4.1％与23.6±3.5％(P<0.05),5.9±2.5％与28.0±0.8％(P<0.01)。整体动物实验也显示硝苯吡啶的降血压作用及对苯肾上腺素升血压效应的阻断作用在SHRSP大鼠都较WKY大鼠显著增强。离体主动脉a_1受体激动时的快速相与持续相收缩均主要由α_(1B)亚型激动引起,硝苯吡啶对快速相收缩的阻断作用在SHRSP与WKY大鼠无显著性差别,但对持续相收缩的阻断作用则在SHRSP大鼠显著强于WKY大鼠。上述结果提示SHRSP大鼠血管α_1受体两种亚型的分布没有显著改变,但α_(1B)受体激动时继发性细胞外Ca~(2+)进入的途径由非双氢吡啶敏感性钙通道转变为双氢吡啶敏感性钙通道。     

Changes in invertase activities precede ovary growth induced by gibberellic acid in

Developing pods of pea ( Pisum sativum L. cv. Alaska no 7) were used to study the enzymes of sucrose metabolism. Acid and neutral invertase (EC 3.2.1.26). sucrose synthase (SS, EC 2.4.1.13) and sucrose phosphate synthase (SPS, EC 2.4.1.14) have been localized in the soluble fraction. Acid invertase activity was also present in the insoluble fraction and in pea ovary apoplast. In pea pods, sucrose breakdown was dominated by the invertase pathway. SS specific activity only increased at late stages of parthenocarpic pod development, while SPS did so in pods obtained by pollination. Changes in time course of invertase activities have been correlated with the growth rate of fruits induced to develop either by fertilization or by exogenous application of giberellic acid (GA), 2,4-dichloro-phenoxy acetic acid (2,4-D) or 6-benzylaminopurine (6-BAP). The soluble neutral activities might be associated with pod elongation, while the acid ones were rather related to assimilate import by the induced fruits. Application of gibberellic acid to non-pollinated ovaries significantly enhanced the soluble neutral invertase activity before any ovary outgrowth was detected (up to 2 h after treatment). Within the same period of time. GA-treated ovaries showed a decrease in the acid invertase activity of the soluble fraction and an increase of the acid invertase activity in the apopiast. preceding in time the increment of the acid invertase activity associated with the insoluble fraction. Our results suggest that the early GA response may be mediated through a promotion of processes of protein secretion.     

Four cases of direct ion channel gating by cyclic nucleotides

Four different nucleotide-gated ion channels are discussed in terms of their biophysical properties and their importance in cell physiology. Channels activated directly by cGMP are present in vertebrate and invertebrate photoreceptors. In both cases cGMP increases the fraction of time the channel remains in the open state. At least three cGMP molecules are involved in channel opening in vertebrate photoreceptors and the concentration of the cyclic nucleotide to obtain the half maximal effect is about 15 µM. The light-dependent channel of both vertebrates and invertebrates is poorly cation selective. The vertebrate channel allows divalent cations to pass through 10–15-fold more easily than monovalent ions. In agreement with their preference for divalent cations, this channel is blocked byl-cis Dialtazem, a molecule that blocks certain types of calcium channels. In olfactory neurons a channel activated by both cAMP and cGMP is found and, as in the light-dependent channel, several molecules of the nucleotide are needed to open the channel with a half maximal effect obtained in the range of 1–40 µM. The channel is poorly cationic selective. A K⁺ channel directly and specifically activated by cAMP is found inDrosophila larval muscle. At least three cAMP molecules are involved in the opening reaction. Half-maximal effect is obtained at about 50 µM. This channel is blocked by micromolar amount of tetraethylammonium applied internally. Interestingly, this channel has a probability of opening 10–20-fold larger in the mutantdunce, a mutant that possesses abnormally elevated intracellular cAMP level, than in the wild type.     

Nuclear genome characterization of the carrageenophyteAgardhiella subulata (Rhodophyta)

DNA reassociation kinetics were used to determine nuclear genome organization and complexity inAgardhiella subulata (Gigartinales, Rhodophyta). Results indicate the presence of three second-order components corresponding to fast (22%), intermediate (68%) and slow (10%) fractions. Thus, the genome consists of 90% repetitive sequences. Microspectrophotoometry with the DNA-localizing fluorochrome DAPI was used to confirm ploidy level differences in the gametophytic and tetrasporophytic phases. Results indicate that meiosis occurs during tetrasporogenesis. Comparison of mean nuclear DNA (I_f) values to chicken erythrocytes (RBC) resulted in an estimate of 0.9 pg/2C genome forAgardhiella. Karyological studies using aceto-orcein revealed a chromosome complement of 2N = 44 in carposporangia and the presence of 22 bivalents during diakinesis of tetraspore mother cells.     

青海省角叶蚤属一新种：（蚤目：角叶蚤科）

本文报告青海省贵南县角叶蚤属 Ceratophyllus Curtis,1832 一新种,命名为贵南角叶蚤Ceratophyllus (Ceratophyllus) guinanensis sp.nov.     

大仓鼠肥满度的研究

本文依公式K=100W/L~3计算了大仓鼠肥满度。统计结果表明,雌性肥满度大于雄性肥满度。肥满度随年龄增长而减小。不同作物类型样地中大仓鼠的肥满度变化不明显。不同季节肥满度有一定的变化,主要与繁殖和气候有关。肥满度与种群密度之间不存在明显的对应关系。     

Identification of the nuclear matrix and chromosome scaffold in dinoflagellate Crypthecodinium cohnii~1

Dinoflagellate is one of the primitive eukaryotes,whosenucleus may represent one of the transition stages fromprokaryotic nucleoid to typical eukaryotic nucleus.Usingselective extraction together with embeddment-free sectionand whole mount electron microscopy,a delicate nuclearmatrix filament network was shown,for the first time,indinoflagellate Crypthecodinium cohnii nucleus.Chromosomeresidues are connected with nuclear matrix filaments to forma complete network spreading over the nucleus.Moreover,we demonstrated that the dinoflagellate chromosome retainsa protein scaffold after the depletion of DNA and solubleproteins.This scaffold preserves the characteristic mor-phology of the chromosome.Two dimensional elec-trophoreses indicated that the nuclear matrix and chromo- some scaffold are mainly composed of acidic proteins.Ourresults demonstrated that a framework similar to the nuclearmatrix and chromosome scaffold in mammalian cells appearsin this primitive eukaryote,suggesting that these structuresmay have been originated from the early stages of eukaryoteevolution.     

云南所麻蝇属一新种记述：双翅目：麻蝇科

作者在整理1985年采集的麻蝇科标本中,发现所麻蝇属(SarcosolomoniaBaranov)1新种。模式标本分别保存于云南省卫生防疫站和军事医学科学院微生物流行病研究所。     

长苞铁杉的核型分析及其分类学意义

本文首次分析了特产我国的长苞铁杉亚属(Subgen. Paleotsuga)的代表种长苞铁杉Tsuga longibracteata的核型,它全由中部和近中部着丝粒染色体组成,核型公式为K(2n)=24=22m 2sm,属“lA”类型。第12号染色体具“长着丝点区域”。染色体相对长度组成为2n=12M_2 10M_1 2S。作者发现铁杉亚属(Subgen. Tsuga)植物的核型全为“2A”类型。胞核学资料支持对长苞铁杉亚属和铁杉亚属的划分并表明前者(长苞铁杉)较为原始。长苞铁杉应隶于长苞铁杉亚属、长苞铁杉组。     

人参根系发育形态学的研究

人参(Panax qinseng C. A. Meyer)属于直根系植物,有次生构造。一年生苗只具有主根和侧根。二年以上的人参常在根状茎上长出不定根,即人参根系包括主根和不定根及其各级分枝。主根初生木质部为三原型,侧根和不定根及其分枝多为二原型,偶见三原型。根系随参龄的增加而增大。每年末级分枝自基部于休眠前萎缩、脱落,并在萎缩部分的上一级支根内部产生越冬根原基,越冬根原基是翌年形成全部吸收根的基础。一年生人参由中柱鞘产生一圈初生树脂道,由形成层产生一圈(或二圈)次生树脂道,以后次生树脂道的圈数随参龄的增加而每年增加一圈,自第五年开始渐缓。根内淀粉粒含量随发育时期的变化而相应变化,其积累高峰出现在果后期。研究人参根系发育形态学不仅对全面正确认识人参根系具有理论意义,而且对改进人参栽培管理和评价人参质量具有指导意义。