Pacemaker Properties of Completely Isolated Neurones in <Emphasis Type="Italic">Aplysia californica</Emphasis>

SINGLE-CELL pacemaker activity is interesting because of its function in temporal organization and information processing in the nervous system. Many invertebrate neurones are regularly and autonomously active^1,2. Although the pacemaker rhythm probably originates within the recorded neurone, it is not clear whether it originates in the axonal tree or in the cell soma. Alving³ approached this question by studying pacemaker activity in the soma of Aplysia nerve cells, after ligaturing the axonal stem with fine sutures. The study described here presents evidence that nerve cell somata which are completely dissociated from all surrounding tissue and with or without axons, are able to maintain regular autorhythmic activity for periods of more than 24 h. The method of complete isolation of cells represents some progress over Alving's method because it is easier to accomplish, has a larger yield of viable neurones and allows longer recording periods.     

四川跳之一新属新种

本文记述跳(虫甲)亚科(Alticinae,Chrysomelidae)的新属Omeisphaera,系以新种O.anticata为模式种,产于四川峨眉山。模式标本保存在中国科学院北京动物研究所。 峨眉球跳(虫甲)Omeisphaera新属 本新属与Sphaeroderma Stephen及Argopus Fischer两属最接近,外形更酷似Argopus属的种类,但唇基正常(图3),不若该属种类之向前叉开而分为两叶。它的主要区别特征在于后胸腹板的前部,即介于中足基节之间的部分显著隆起,向前突出,与前胸腹板相遇,遮盖了中胸腹板(图4);前突的端末钝圆,不具边框。在Sphaeroderma、Argopus等属,后胸腹板前部并不隆起,端末具边框,与中胸腹板嵌合,处于同一水平。     

Carbohydrate Metabolism in the Narcissus Leaf

Carbohydrate contents of both the photosynthetic and the storageorgans of Narcissus tazetta L. were determined at four stagesin their development under both ‘natural’ growingconditions and under conditions of varying light intensities. Starch was abundantly stored in all the storage organs, particularlyin the bases of the photosynthetic organs under high light intensityand also at the second dormant stage. However, its level remainedrelatively stable in the green part of the foliage leaf andthe scape at different stages and appeared not to be affectedby light except at very high intensity. It was found in boththe bundle sheaths and guard cells. Sucrose, which is the first sugar of photosynthesis, was continuouslyexported from the green parts of the blade and the scape totheir bases where it was also stored. In the dark the sucroselevel became low in the green blade and the green scape butit rose with increase of light intensity. The hexose level was very low at the dormant stage in all organsexamined but rose as they matured and exceeded that of sucrosein the green organs except in high light intensity. Hexose isformed presumably as a result of sucrose hydrolysis and is constantlylost, presumably through respiration. At senescence sugar disappeared almost completely from all theorgans, while nearly 10 per cent of residual dry weight of starchremained in the dead tissues. The interrelationship betweenthe carbohydrates and their movement in the leaf is discussed.     

地里恙螨幼虫形态变异的研究

我们在研究甲乙两型地里恙螨子代的形态和两型地里恙螨的杂交实验中,发现这两者子代幼虫中有出现形态变异的现象。 1.后侧毛基的移位:从沿海某县采回的甲型地里恙螨(以下简称“C甲”)在实验室饲养繁殖的F_1标本中,出现一只左边后侧毛位置正常而右边后侧毛向上移位至感毛基的前侧(见图1)。左边A-P为27.6     

我国恙虫蚴的三个新种(蜱螨目, 恙虫科)

近几年来,我国科学家们在恙虫方面的研究工作巳经取得了显著的成就。然而,这对于拥有辽阔疆土的我国来说,实在只不过是一个开始。我们在这方面的工作也做得很少,虽然从1953年开始收集标本,由于各种条件所限制,未能及时整理,以致大量标本散失或霉烂,十分可惜。本文内容,仅仅是将我站恙虫病调研工作组1957年在本省各地所采集的材料中的三种恙虫蚴加以描述,该三种恙虫蚴均系文献上未曾记载过的种类。     

水稻不育花药中H_2O_2的积累与膜脂过氧化的加剧

水稻7017、二九矮细胞质雄性不育系及其保持系花药的POD,CAT和SOD活性研究的结果表明,单核早期时不育及可育花药的酶活性差异不明显,单核晚期、二核及三核期的不育花药显著低于可育花药。在不育花药中缺少两条Cu-Zn SOD同工酶带,而且O_2~ 产生效率为可育的4.1～5.5倍,并有H_2O_2和MDA的积累。不育花药中H_2O_2的积累和膜脂过氧化的加剧可能与花粉败育有关。     

水分胁迫对甘蔗叶片线粒体膜流动性的影响及其与膜脂过氧化的关系

用荧光探剂ANS对抗旱性不同的甘蔗品种在水分胁迫下叶片线粒体膜流动性的变化进行的研究表明,水分胁迫降低了线粒体膜的流动性,抗旱性强的甘蔗品种Co 617和F.Y.79-9的下降幅度分别小于抗旱性弱的Co 740和M.T.77-208;水分胁迫下线粒体膜流动性的下降与膜脂过氧化产物丙二醛含量的增加有密切关系。外源自由基处理试验也表明,甘蔗叶片线粒体膜流动性的下降与膜脂过氧化作用有关。     

香蕉低温酶促褐变

7℃低温导致香蕉果皮变褐,褐变程度可用提取液的OD_(450)值表示。随低温处理时间的延长,OD_(450)增大;还原性物质抗坏血酸、谷胱甘肽含量迅速下降;多酚氧化酶底物多巴胺先有增加,接着降低。 低温下,多酚氧化酶(PPO)、过氧化物酶(POD)和过氧化氢酶(CAT)活性较常温低,PPO和POD的游离态酶活性增高。此外,H_2O_2处理加速果皮变褐,刺激PPO及POD活性;棓酸丙酯处理起相反的效应。故认为香蕉低温褐变是低温损伤、酶促褐变引起的一个复杂过程。     

酵母鉴定程序在酵母分类鉴定中的应用

本文介绍了Barnett等1985年编制并由剑桥大学发行的计算机软件《酵母鉴定程序》,以及如何使用该程序在IBM PC DOS操作系统上进行酵母菌的分类鉴定。我们使用该程序对从云南鸡足山和紫金山两地森林土壤中分离到的82株酵母菌进行了分类鉴定,其中:鉴定到种的有47株,占总株数的57.3％;鉴定到属但未能直接定到种的有21株,占总株数的25.6％;暂未定名的有14株,占总株数的17.1％。