Cyclical transformations of the actin cytoskeleton of hyacinth pollen subjected to recurrent vapour-phase hydration and dehydration

Summary— Transformations of the actin cytoskeleton of the pollen of Hyacinthus orientalis during cycles of vapour-phase hydration and dehydration have been examined using a non-fixation, DMSO permeabilisation method for TRITC-phalloidin staining, coupled with microwave stabilisation. In freshly shed pollen actin appears: a) at the plasmalemma in the form of extended, thin fibrils co-oriented with the cellulosic microfibrils of the contiguous intine; b) as a sheath investing the generative cell; c) as spicules around the vegetative nucleus; and d) in scattered spicules in the cytoplasm. During hydration in 85–95% relative humidity (RH), actin from all of these sites is progressively translated into a system of extended fibrils in the vegetative cell, concurrently with the onset of movement in the cytoplasm. Dehydration at 5–7% RH reverses this process, actin accumulating in rodlets, spicules or larger fusiform bodies in close association with the generative cell and vegetative nucleus, and also in the cytoplasm. The fibril system initially present at the plasmalemma is not restored. After ten cycles of hydration and dehydration 3.6% of the grains remained germinable. The ecological significance of the findings is noted, and the possibility that the observed transformations result from variation in the Ca²⁺ concentration in the cytosol as the water content of the cytosol changes is considered.     

东方杯叶吸虫体被的超微结构

扫描电镜显示东方杯叶吸虫体被有许多族生棘,具纤毛乳突和无纤毛窝状乳突,附着器皮层特化为微毛。透射电镜观察表明,皮层是由合胞体、基膜和肌肉层组成,合胞体通过细胞通道与皮层细胞相连。文中详细描述了这些结构,揭示无纤毛窝状乳突为腺乳突,皮层细胞间存在线粒体细胞和附着器皮层形成微毛,探讨了这些结构的生理功能。体外培养成虫皮层结构的某些不正常变化,如皮层细胞的空虚松散,可作为评价吸虫体外培养的一种指标。     

红羊新蚤的地理分布、宿主关系和鉴别特征的研究(蚤目：多毛蚤科)

自从红羊新蚤Neopsylla hopgyangensis Li,Bai & chen,1986从宁夏回族自治区的海原和贺兰山林区发现并报道(四川动物5(2)：1-3)以后,青海、甘肃和陕西均先后发现他们以往鉴定为二齿新蚤的大多数为红羊新蚤。本文报道红羊新蚤的地理分布、海拔、主要宿主及鉴别特征的应用。     

关于有尾类胚胎的表皮及非典型表皮的兴奋性

蝾螈胚胎表皮的兴奋性及传导能力在分期26出现,到分期37末结束,某些部位甚至更晚些消失。为了查明表皮细胞兴奋性的产生是否受到来自其它组织的影响,还是仅依赖于表皮细胞自身的分化状态,我们曾用非典型表皮进行过研究。当时曾报道,离体培养的表皮细胞,即使达到了产生兴奋性的分化状态,用电生理技术在刺激强度为1—2伏时,测试不到动作电位。然而,如果这样的非典型表皮被     

二齿新蚤的吸血活动

本文在实验室内研究了二齿新蚤吸血活动与环境温度、蚤龄、性别的关系。实验证明,幼蚤吸血最适温度为25℃左右,该温度下吸血率最高;成蚤在各种温度下,吸血率均接近100%。成蚤吸血率高于幼蚤。幼蚤雌蚤吸血率高于雄蚤,成蚤吸血率雄雌均接近100%。蚤吸血量与吸血时温度无关,威蚤吸血量大于幼蚤。雌蚤吸血量大于雄蚤。蚤的血液消化速度,高温时较低温时为快。在温度25℃以下时,成蚤消化速度较幼蚤为快;30℃以上时,成蚤与幼蚤消化速度相近。消化速度与性别无关。     

特新蚤指名亚种幼虫的形态(英文)

本文详细描述了尚未报道的特新蚤指名亚种Neopsyllaspecialisspecialis幼虫形态。它与新蚤属已描述的5种或亚种幼虫的鉴别特征是：1-3胸节腹板上后排主鬃列长鬃外侧有2个小鬃;破卵器的长宽比例,大颚的齿数和齿形,前后头刚毛的数目和长度,肛梳刚毛和支柱毛的数目。作者观察到特新蚤指名亚种幼虫第10背板上有感器一对,并又观察了4科9种或亚种蚤幼虫和Bartkowska（1965,1972）,Kirjakova（1968）的描述,认为该特征可能是多毛蚤科幼虫的鉴别恃征之一。     

Optimization of fermentation conditions for the production of ethylene-diamine-disuccinic acid by Amycolatopsis orientalis

The production of EDDS (ethylene-diamine-disuccinic acid), a potential substitute for EDTA, has been optimized up to a product concentration of 20 grams per litre in fermentations of Amycolatopsis orientalis. Decisive steps for the increase in productivity were variation of the synthetic medium composition, investigation of the influence of metal ions on product formation, controlled feeding of carbon and nitrogen sources in fed-batch fermentations and improvement of the downstream processing steps. Received 05 May 1997/ Accepted in revised form 13 August 1997     

山东侧柏林生长生态特性的数值分析

应用多元分析方法研究了26个生态因子对山东侧柏林的3个生长指标的影响．结果表明影响林分生长的主要因子是：温度、土壤厚度、海拔和密度,排出了生态因子对林分生长指标的重要性序列,给出了林分生长指标的优化数学模型．