Some biological and genomic properties of rice tungro bacilliform badnavirus and rice tungro spherical waikavirus from Nepal

A survey of rice fields during the main growing seasons in 81 locations from 21 districts of the Southern Terai region of Nepal indicated that rice tungro was primarily restricted to the Hardinath (Janakpur) and Parwanipur (Bara) regions. The tungro incidence in Hardinath ranged from 17% to 51% and in Parwanipur from 6% to 61% causing about 89% grain yield loss in Hardinath. Both rice tungro bacilliform badnavirus (RTBV) and rice tungro spherical picornavirus (RTSV) were found in tungro isolates collected from Hardinath and Parwanipur. These isolates were transmitted by Nephotettix virescens and leaf extracts reacted to antisera against RTBV and RTSV. In a dot blot hybridisation assay, leaf extracts of 12 weed species collected from the tungro-affected area in Hardinath and Parwanipur also reacted with RTBV DNA probes. On mass inoculation of 15 popular rice cultivars most became more than 50% infected and only cv. Radha 9 had low (22.2%) infection. RTBV DNA and the coat protein region of RTSV from the Hardinath isolate were cloned and partially characterised. A comparative analyses by restriction endonuclease digestion, cross hybridisation, the polymerase chain reaction and partial sequencing indicated that the Nepalese RTBV DNA clone and the cDNA clones of the RTSV RNA were more similar to the various tungro isolates from the Indian subcontinent than to those from the Philippines.     

羟泰米酚的抗着床作用及其对小鼠子宫雌二醇和孕酮受体含量的影响

经雌激素拮抗剂－羟泰米酚处理后的怀孕小鼠,胚泡着床受到明显抑制;同时,着床前子宫细 胞质雌二醇受体和孕酮受体明显减少,细胞核受体明显增加;拮抗剂还使血清雌激素和孕酮含量显 著降低。结果表明：羟泰米酚的抗着床作用效应与子宫雌二醇受体和孕酮受体的正常功能受到干扰 可能是有密切关系的。     

青海花蝇科一新种（双翅目）

本文记述采自青海省花蝇科泉种蝇属一新种。单锥泉种蝇Ｐｅｇｏｈｙｌｅｍｙｉａ ｍｏｎｏｃｏｎｉｃａ ｓｐ．ｎｏｖ．模式标本保存在中国科学院上海昆虫研究所。     

鸡肝二氢叶酸还原酶在盐酸胍溶液中构象的序变与激活

用蛋白质内源荧光、疏水荧光探针TNS及蛋白酶K限制性酶解等方法研究了二氢叶酸还原酶在盐酸胍变性过程中的构象变化及动力学,并与活力变化进行了比较.TNS可以监测到与激活同步的构象变化;盐酸胍浓度大于0.75mol/L时,二氢叶酸还原酶被蛋白酶K水解速度增大;当盐酸胍浓度大于1.2mol/L时,才能监测到酶分子整体构象的变化.以上结果表明二氢叶酸还原酶在盐酸胍溶液中的变性并不符合标准的二态模型,而是先经历构象逐步松散的序变过程,然后发生协同的构象伸展.二氢叶酸还原酶在低浓度盐酸胍溶液中的激活是由于酶活性部位构象的微小变化引起的.酶活性部位构象的变化虽然降低了酶与废物的结合能力,但加快了酶促反应限速步骤,即底物解离速度而使酶活力升高.     

Functional expression of opioid receptor—like receptor and its endogenous specific agonist nociceptin／orphanin FQ during mouse embryogenesis

INTRODUCTIONOpioidreceptorsbelongtotheG-protein-coupledreceptorfamilythatischaracterizedbytheseventransmembranespanningdomainsinstructure.Threesubtypesoftheopioidreceptors(H,6,andK)havebeenclonedandcharacterizedthroughtheir1.CorrespondingauthorFunctionalexpressionofORLIandN/OFQduringmouseembryogenesisdistinctaffinitiesfordifferentopioidligands.TheseopioidreceptorsareallcoupledtotheinhibitoryGprotein(Gi)andnegativelyregulateadenylatecyclase[1].Opioidreceptor--likereceptor(ORLI),anew…     

棉蝗的病原真菌新种——棉蝗簇孢霉

采自广东的簇孢霉属Sporothrix一新种,棉蝗簇孢霉SporothrixchondracisB.Huang,M．Z．FanetZ．．Z．Li。该种产孢细胞齿突不再育或多次再育呈给节状间生,其分生孢子在该属中最小,呈油滴状或倒拟卵形,（1．7～）2．5（～3．1）×（1．0～）1．3（～2．0）μm。     

视网膜电图振荡电位参数的稳定性

用系列强度１１档刺激闪光记录２０例３０只眼的视网膜电图（ＥＲＧ）振荡电位（ＯＰ）,研究ＯＰ的光强特性和参数稳定性。结果表明,ＯＰ各子波峰时和刺激光强呈指数曲线相关,相关性很高;而振幅和光强的函数关系的变异很大,相关性较低,不同对象间ＯＰ各子波振幅的变异系数较大,而峰时的变异系数较小,ＯＰ的峰时改变比振幅改变更为稳定。     

心室内和心外膜应用腺苷对延髓PGL神经元电活动的影响

在35只切断两侧缓冲神经和迷走神经的麻醉大鼠,观察心室内注射腺苷和心外膜涂布腺苷对延髓腹外侧头端区PGL神经元自发电活动的影响。结果如下：（1）35只大鼠共记录到121个自发放电单位,平均放电频率为22．5±1．9spikes／s。（2）心室内冲击注射腺苷（0．5μmol/kg,0．1ml）时,BP先升（△1．7±0．2kPa,P＜0.001）后降（△4.6土0.5kPa,P＜0．001）,HR减慢（△126．5±12.3bpm,P＜0.001）;35个PGL神经元自发放电单位中,30个单位的放电频率由21．9士2．6增至29．2土3．4spikes／s（P＜0．001）,3个单位不变,2个单位减少。（3）心外膜涂布腺苷（20mmol/L）,动脉血压和心率的变化不明显,22个PGL神经元自发放电频率由18．8土1．9增至26．9土2．8spikes／s（P＜0．001）,3个单位的放电频率无变化。（4）静脉注射选择性腺苷A1受体拮抗8－cyclopentyl-1,3－dipropylxanthine（DPCPX,500μg／kg）可完全阻断腺苷对PGL神经元的兴奋效应。（5）在左右房室沟涂布85％酚或切除双侧星状神经节后,腺苷激活PGL神经元的效应即行消失。结果提示,腺苷可通过人受体激活心交感神经传入纤维,进而兴奋PGL神经元。