Characterization of gamma-aminobutyric acid and dopamine overflow following acute implantation of a microdialysis probe

The present study characterized the voltage and calcium dependence of gamma-aminobutyric acid and dopamine overflow after the acute implantation of a microdialysis probe. Probes were implanted in dorsolateral striatum and globus pallidus. Experiments were performed under light halothane anesthesia. Basal, extracellular levels of GABA were not affected by tetrodotoxin (TTX) and were increased to 140 percent of basal values by calcium free Ringer. Basal, extracellular levels of dopamine were reduced to 14 percent of basal values by the addition of TTX and to 30 percent of basal values by the removal of calcium from the Ringer solution. The results suggest that in this in vivo preparation basal extracellular dopamine is largely of vesicular origin while GABA is not.     

1,1-Organoboration of tri-1-alkynyltin compounds: novel triorganotin cations, stannoles, 3-stannolenes and 1-stanna-4-bora-2,5-cyclohexadienes

Tri-1-alkynyltin compounds [R²Sn(CCR¹)₃ (1), R² = Me, R¹ = Me (a), ⁿBu (b), ^tBu (c), Me₃Si (d), 1-(1-cyclohexenyl) (e); R² = Et, R¹ = Me (a(Et)), ⁿBu (b(Et)), ^tBu (c(Et)), SiMe₃ (d(Et)); R² = ⁿBu, R¹ = Me (a(Bu)), ⁿBu (b(Bu))] were prepared, and their reactivity towards trialkylboranes Et₃B (2) and ⁱPr₃B (3) in 1,1-organoboration reactions was studied. The first step in each reaction is an intermolecular 1,1-alkytoboration. Afterwards, intramolecular 1,1-vinyloboration or 1,1-alkyloboration compete with further intermolecular 1,1-alkyloboration. Various triorganotin cations (4-7), stabilized by intramolecular side-on coordination to the CC bond of an alkynylborate moiety, were detected as highly fluxional intermediates prior to rearrangement into heterocyclic systems such as stannoles (9-11), 1-stanna-4-bora-2, 5-cyclohexadienes (8, 12). The reactions between 1a or 1a(Bu) and an excess of Et₃B (2) afford the tris(alkenyl)tin compounds 13 via threefold intermolecular 1, 1-ethyloboration. 13 rearrange to the 3-stannolenes (14a or 14a(Bu)). The intermediates and final products were characterized by multinuclear one- and two-dimensional ¹H, ¹¹B, ¹³C, ²⁹Si and ¹¹⁹Sn NMR.     

17个建兰品种光合特性分析

以17个建兰(Cymbidium ensifolium)品种为材料,采用改良的丙酮法提取叶绿素,再通过Arnon丙酮法公式计算光合色素含量,利用捷克FluorCam开放式叶绿素荧光仪测定不同品种的叶绿素荧光参数。结果表明,17个建兰品种的光合色素和叶绿素荧光参数具有不同程度的差异,其中‘铁骨素’(C. ensifolium ‘Tiegusu’)、‘逸红双娇’(C. ensifolium ‘Yihongshuangjiao’)和‘闽南黄蝶’(C. ensifolium ‘Minnanhuangdie’)的光合色素含量高于其他品种,表明这3个品种具有良好的光合效率,吸收光能的能力较强;‘铁骨素’最大荧光产量(Fm)、Kautsky诱导效应最大荧光(Fp)、PS Ⅱ原初光能转化效率(Fv/Fm)和非光化荧光淬灭系数(NPQ)均为最高。综上可知,‘铁骨素’的光合生理特性优于其他品种,可作为优良建兰品种进行种植推广。     

小叶锦鸡儿天然居群叶形态性状变异研究

为揭示小叶锦鸡儿(Caragana microphylla)天然居群叶形态性状的变异规律及其生态适应性特征,该研究以10个小叶锦鸡儿天然居群为对象,通过多重比较、巢式方差分析、相关性分析、聚类分析和主成分分析等方法,对7个叶形态性状进行分析。结果表明：(1)小叶锦鸡儿叶形态性状在居群内和居群间均存在极显著差异(P < 0.01),平均变异系数为10.13%,不同性状的变异幅度为6.23%~12.78%;平均叶形态性状的表型分化系数为43.62%,居群内变异(30.09%)大于居群间变异(24.91%),说明居群内是其叶形态性状变异的主要来源。(2)相关性分析表明,环境因子对小叶锦鸡儿的叶形态性状变异有很大的影响,在地理空间上主要呈现出沿海拔梯度的变异模式;主成分分析的结果显示,小叶宽、叶柄宽和叶柄长对小叶锦鸡儿叶形态变异起主导作用;利用欧式距离对小叶锦鸡儿居群进行UPGMA聚类分析结果显示,基于叶形态性状和环境因子可分别将小叶锦鸡儿10个居群分为3类和2类,Mantel检验结果表明,小叶锦鸡儿的叶形态性状变异不存在地理连续性。研究结果为小叶锦鸡儿的适应性进化和开发利用提供了理论依据。     

H2S作为下游信号参与SA对低温弱光下黄瓜幼苗光合作用的调控

水杨酸(SA)和硫化氢(H₂S)在调控非生物胁迫下植物生长发育和生理代谢中均起着非常重要的作用,但二者作为信号分子在调控低温弱光下黄瓜光合作用中的互作关系还不清楚。本试验以黄瓜幼苗为试材,分别用SA和硫氢化钠(NaHS,H₂S供体)及其清除剂或抑制剂喷撒叶面,以适宜温光下去离子水处理为对照(CK),研究低温(8 ℃/5 ℃,昼/夜)弱光(100 μmol·m^-2·s^-1)下SA和H₂S对黄瓜幼苗光合作用的调控及互作关系。结果表明: SA可明显增强L-/D-半胱氨酸脱巯基酶(LCD、DCD)活性及其mRNA表达,促进内源H₂S产生;NaHS对苯丙氨酸解氨酶和异分支酸合成酶活性、mRNA表达量及内源SA含量影响不大。SA和NaHS可使低温弱光下黄瓜幼苗的光合速率、气孔导度和蒸腾速率明显提高,胞间CO₂浓度显著降低;同时增强核酮糖-1,5-二磷酸羧化酶、Rubisco活化酶、景天庚酮糖-1,7-二磷酸酯酶和果糖-1,6-二磷酸醛缩酶活性及其mRNA表达,促进光合碳同化;提高光下PSⅡ实际光化学效率和暗下PSⅡ最大光化学效率,从而减轻低温弱光胁迫对黄瓜幼苗的光合机构的损伤和生长量的影响。H₂S清除剂次牛磺酸(HT)可使SA对低温弱光下黄瓜幼苗的光合作用和生长促进效应明显减弱,而SA抑制剂多效唑和氨基茚磷酸对H₂S诱导的黄瓜幼苗光合机构对低温弱光的耐受性无显著影响,说明H₂S作为SA的下游信号,参与调控低温弱光下黄瓜幼苗的光合作用。     

Concurrent modulation of extracellular levels of noradrenaline and cAMP during stress and by anxiogenic- or anxiolytic-like neuropeptides in the prefrontal cortex of awake rats

The purpose of this study was to examine the effects of stress and the role of locally infused anxiogenic-like neuropeptides galanin, CCK-8, vasopressin, substance P and neurokinin A, and anxiolytic-like peptides NPY, nociceptin/orphanin FQ, somatostatin and neurotensin, on modulation of noradrenaline (NA) and cAMP efflux monitored simultaneously by microdialysis in the medial prefronatal cortex of awake rats. Concentrations of cAMP were determined by a newly developed method based on derivatization of cAMP with 2-chloroacetaldehyde followed by HPLC with fluorescence detection. Local infusion of forskolin (10 and 30 μM) dose-dependently increased the cAMP levels to 417% and 1050% of the control group, respectively. Similarly, local infusion of NA (10 μM) increased the cAMP to the peak level of 168%. A 5-min tail pinch and a 10-min swim stress rapidly increased the NA and cAMP levels to 167% and 203% (NA) and 141% and 161% (cAMP), respectively. Infusion of galanin and CCK-8 (0.5 nmol, and 1.5 nmol/0.5 μl) dose-dependently increased NA to the peak levels of 191% and 179% and cAMP levels to 174% and 166%, respectively. The peak levels following infusions of vasopressin, substance P and neurokinin A were 91%, 135% and 86% for NA and 131%, 83% and 76% for cAMP, respectively. Infusions of anxiolytic-like peptides at highest concentrations significantly increased (NPY, 136%) or decreased (nociceptin, 71%; somatostatin, 86%) the NA levels, whereas neurotensin had no effect. The cAMP levels decreased to 86% (NPY, neurotensin), 78% (nociceptin), somatostatin infusion was without effect. The present findings confirmed a close correlation between the stress-induced increases in prefrontal cortical NA and cAMP levels, as well as, concurrent changes in NA and cAMP levels following infusions of galanin and CCK-8 (increased levels) and nociceptin/orphanin FQ (decreased levels). Infusions of other neuropeptides showed a more complex pattern of NA and cAMP responses.     

马铃薯实生群体遗传多样性的SSR分析

以云南马铃薯品种‘剑川红’植株1个浆果中的天然实生种子产生的70个单株以及B20[CIP010(♀)×CIP004(♂)]杂交组合后代100个实生苗单株为材料,采用12对SSR引物对自交种和杂交实生群体的遗传差异性进行分析,旨在从后代群体中找到与母本(亲本)在分子水平上表现一致的植株,为种质资源的长期保存提供依据。结果表明:(1)‘剑川红’自交群体的多态性比率为81.6%,比杂交组合B20实生群体的多态性比率72.8%略高,说明2个群体的多态性比率均较高。(2)聚类分析结果显示,自交后代和杂交后代群体的遗传相似系数均较高,变化范围均在0.74~0.96之间,说明2个群体均发生了不同程度的遗传分离,但分离的程度较小,绝大多数条带表现一致。(3)在所有供试材料中,同一浆果中均未发现与‘剑川红’母株在分子水平上表现完全一致的单株。研究认为,在分子水平上寻找完全不分离的实生群体难度非常大,需进一步评价与母株(亲本)在分子水平上相似株系的田间表现,从而确定是否可以通过相近或极相近株系来恢复种源。     

Surface glycoprotein of Borna disease virus mediates virus spread from cell to cell

Borna disease virus (BDV) is a non‐segmented negative‐stranded RNA virus that maintains a strictly neurotropic and persistent infection in affected end hosts. The primary target cells for BDV infection are brain cells, e.g. neurons and astrocytes. The exact mechanism of how infection is propagated between these cells and especially the role of the viral glycoprotein (GP) for cell–cell transmission, however, are still incompletely understood. Here, we use different cell culture systems, including rat primary astrocytes and mixed cultures of rat brain cells, to show that BDV primarily spreads through cell–cell contacts. We employ a highly stable and efficient peptidomimetic inhibitor to inhibit the furin‐mediated processing of GP and demonstrate that cleaved and fusion‐active GP is strictly necessary for the cell‐to‐cell spread of BDV. Together, our quantitative observations clarify the role of Borna disease virus‐glycoprotein for viral dissemination and highlight the regulation of GP expression as a potential mechanism to limit viral spread and maintain persistence. These findings furthermore indicate that targeting host cell proteases might be a promising approach to inhibit viral GP activation and spread of infection.