蜂毒肽抑杀病原菌的超微结构观察

本研究比较了蜂毒肽对4种不同病原菌生长的影响及其抑杀菌作用的差异,并利用电子显微镜观察了蜂毒肽抑杀菌过程中超微结构的变化.结果表明,蜂毒肽对白菜软腐病菌的杀菌作用最强,而且速效;对酵母菌和番茄叶霉病菌孢子同样具有很强的杀灭作用,但作用时间延长;对金黄葡萄球菌为低浓度抑菌,高浓度杀菌作用.实验中观察到,蜂毒肽在抑杀菌过程中超微结构的变化有3种方式致死细胞：一是膜孔洞式,即蜂毒肽作用后在细胞膜区形成小空泡,随之由内向外扩展穿透细胞壁形成孔洞,引起菌体内容物泄漏死亡,显示了膜孔洞的形成过程;二是质壁分离式,小空泡以横向扩展使细胞产生类似质壁分离样空腔,最后细胞裂解死亡;三是细胞质空腔式,蜂毒肽进入细胞后与细胞质中的类膜系统的膜结合引起解体,细胞质固缩,出现空腔,细胞死亡.值得注意的是蜂毒肽抑杀菌作用的强弱及速效性与其不同杀菌方式相关.综上结果,蜂毒肽各种抑杀菌方式的共同点是蜂毒肽与膜磷脂分子结合相互作用所致.     

Isolation of Lactococcus lactis subsp. cremoris from nature by colony hybridization with rRNA probes.

Lactococcus lactis subsp. cremoris is widely used in the manufacture of fermented milk products. Despite numerous attempts, efforts to isolate new strains by traditional plating and identification methods have not been successful. Previously, we described oligonucleotide probes for 16S rRNAs which could be used to discriminate L. lactis subsp. cremoris from related strains. These probes were used in colony hybridization experiments to screen large numbers of colonies obtained from enrichment cultures. A total of 170 strains of L. lactis were isolated from six milk samples, two colostrum samples, and one corn sample by using oligonucleotide probe 212RLa specific for the species L. lactis. Fifty-nine of these isolates also hybridized to L. lactis subsp. cremoris-specific probe 68RCa, and 26 of the strains which hybridized to the L. lactis subsp. cremoris-specific probe had the L. lactis subsp. cremoris phenotype.     

Effects of pO2 on the activation of skeletal muscle ryanodine receptors by NO: a cautionary note

Eu et al., reported that O2 dynamically controls the redox state of 6-8 out of 50 thiols per skeletal ryanodine receptor (RyR1) subunit and thereby tunes the response of Ca2+-release channels to authentic nitric oxide (NO) [J.P. Eu, J. Sun, L. Xu, J.S. Stamler, G. Meissner, The skeletal muscle calcium release channel: coupled O2 sensor and NO signaling functions, Cell 102 (2000) 499-509]. A role for O2 was based on the observation that RyR1 can be activated by submicromolar NO at physiological ( approximately 10 mmHg) but not ambient (approximately 150 mmHg) pO2. At ambient pO2, these critical thiols were oxidized but incubation at low pO2 reset the redox state of these thiols, closed RyR1 channels and made these thiols available for nitrosation by low NO concentrations. Eu et al., postulated the existence of a redox/O2sensor that couples channel activity to NO and pO2 and explained that "the nature of the 'redox/O2 sensor' that couples channel activity to intracellular redox chemistry is a mystery". Here, we re-examined the effect of pO2 on RyR1 and find that incubation of RyR1 at low pO2 did not alter channel activity and NO (0.5-50 microM) failed to activate RyR1 despite a wide range of pO2 pre-incubation conditions. We show that low levels of NO do not activate RyR1, do not reverse the inhibition of RyR1 by calmodulin (CaM) even at physiological pO2. Similarly, the pre-incubation of SR vesicles in low pO2 (for 10-80 min) did not inhibit channel activity or sensitization of RyR1 to NO. We discuss the significance of these findings and propose that caution should be taken when considering a role for pO2 and nitrosation by NO as mechanisms that tune RyRs in striated muscles.     

14种菊科植物提取物对菜青虫的杀虫活性

用胜红蓟、黄花蒿、青蒿、艾蒿、鬼针草、三叶鬼针草、鱼眼草、小鱼眼草、紫茎泽兰、千里光、希签草、万寿菊、肿柄菊、苍耳等１４种菊科植物的石油醚、氯仿、丙酮、乙醇、甲醇和水提取物对菜青虫５龄幼虫的生测结果表明,黄花蒿、青蒿、艾蒿、鱼眼草、小鱼眼草、紫茎泽兰、万寿菊等７种菊科植物甲醇和乙醇提取物具有较高的杀虫活性。此结果为进一步从菊科植物中提取,分离和筛选高活性杀虫活性成分奠定了基础。     

蓖麻籽提取液对福寿螺毒杀效果及作用机制

采用生物浸泡法,以草本植物蓖麻籽提取液制备植物源毒杀剂,研究不同提取液浓度(0、0.5、1.5、3.0、4.5、6.0 g/L)对福寿螺毒(Pomacea canaliculata Lam)杀作用效果,并通过福寿螺在亚致死浓度1.58(LC25)、3.82(LC50)和6.05 g/L(LC75)处理条件下的肝脏组织生...     

濒危植物蒙古扁桃花粉活力和柱头可授性研究

用过氧化氢酶法测定蒙古扁桃花粉的活力和寿命,用联苯胺-过氧化氢法测定柱头可授性。结果表明,蒙古扁桃花粉活力在散粉后第2天最高,3d后活力迅速下降,三种类型的植株的花粉活力下降速度存在差异,其活力可持续30d左右。短柱头植株柱头在开花后1d可分泌黏液,长柱头和中柱头花植株的柱头在开花后2d才分泌黏液,短柱头分泌黏液的持续时间较后者长。柱头可授性持续时间同种之间也存在差异,长柱头和中柱头植株可达6d,而短柱头花植株可持续10d左右。     

肠道病毒71型灭活疫苗免疫恒河猴在攻毒实验中的感染动力学

本文旨在根据前期研究建立的恒河猴感染动物模型,对同期研制的肠道病毒71型(EV71)实验性灭活疫苗免疫动物进行全面的免疫保护性评价。评价指标包括病毒攻击后动物体内病毒载量及病理学变化,根据所得结果进行实验性疫苗免疫后动物在病毒攻击中的感染动力学分析。3个疫苗剂量(20、80、320EU)免疫的恒河猴均出现不同效价的中和抗体,80EU和320EU剂量组在二次免疫后第6周抗体效价达1∶128～1∶256,经104.5CCID50病毒鼻腔攻击后均未检出阳性病毒载量。20EU剂量组中,淋巴器官、中枢神经系统及其他主要脏器均出现比对照组低但仍为阳性的病毒增殖现象。病理学方面,各剂量组免疫恒河猴的中枢神经系统以及肺等器官均未出现相关病理损伤。本实验在确定该疫苗对恒河猴有效保护性的同时,亦为明确EV71灭活疫苗免疫剂量提供了直接的实验依据。     

电晕电场对沙生植物愈伤组织诱导及分化的影响

用不同电场剂量处理花棒和杨柴的下胚轴后进行愈伤组织诱导及分化培养,以探讨电晕电场对其愈伤组织诱导与分化的影响.结果表明,电场处理可以显著提高愈伤组织诱导率和分化率,并有效降低愈伤组织的褐化率.花棒在电场强度为5 kV/m下处理60 min时,出愈率可达90.5%,分化率可达88.7%;杨柴在电场强度为3 kV/m下处理100 min时,出愈率可达95.8%,分化率可达78.9%.     

MAGE-A1,A2,A3,A4在膀胱移行细胞癌组织及细胞株中基因表达的研究

目的研究膀胱移行细胞癌(TCC)中黑色素瘤抗原(MAGE)基因表达。方法逆转录聚合酶链反应(RT-PCR)技术检测20例膀胱TCC患者癌组织和3株膀胱TCC细胞株T24、EJ、BIU87中MAGE-A1、A2、A3、A4基因mRNA表达。结果20例膀胱TCC癌组织中19例(95%)至少表达一种MAGE-A基因,12例MAGE-A1阳性(60%),16例MAGE-A2阳性(80%),11例MAGE-A3阳性(55%),18例MAGE-A4阳性(90%),MAGE-A1-4均阳性8例(40%)。膀胱TCC细胞株T24中MAGE-A1-4基因均表达,EJ中MAGE-A3、A4基因表达,BIU87中MAGE-A2、A3、A4基因表达。结论MAGE基因在膀胱TCC中有较高表达,可望成为膀胱TCC免疫治疗的靶基因。     

Effect of colchicine on the carbohydrate metabolism of mycelial felts of cunninghamella Sp.

Summary An experiment is reported in which 5 days old Cunninghamella spec. mats were incubated at 25°C over Richard's medium alone or together with colchicine. The results show that, up to 20 p.p.m., colchicine had no effect on dry weight and soluble sugar content of the fungal mats but caused an acceleration in the rate of sugar absorption and utilisation and polysaccharide accumulation especially the glucosans. 10 p.p.m. concentration further induced an increase in CO₂ production and synthesis of mononucleotides and nucleoproteins as indicated by excessive accumulation of conjugated pentoses and the pentosan fraction of polysaccharides.