银杏精原细胞和精细胞的初步研究

0　引　言由于银杏(ＧｉｎｋｇｏｂｉｌｏｂａＬ.)独特的系统学地位及精子结构的特殊性,对银杏生殖生物学的研究工作一直是裸子植物胚胎学研究的热点之一[1～12]。这些研究表明,银杏精原细胞从产生到最后形成精子历时3个月左右[1～5]。在此期间,其体积增大数倍,结构发生了...     

Effect of acetylhomocysteine thiolactone on nucleolar cytology and lipofuscinogenesis in electric lobe neurons

Summary Treatment with acetylhomocysteine thiolactone significantly reduces the cellular level of lipofuscin in neurons of the electric lobe ofTorpedo marmorata. At the same time, this drug produces a 45% decrease in nucleolar volume in these neurons, reflecting decreased cellular synthetic activity.     

高温高压下煤的岩石学特征变化及其与天然状态下煤的对比

根据在河南禹县—荥巩煤田贫煤和无烟煤带存在气孔和镶嵌结构这一事实,对南部平顶山煤田的肥煤进行了高温高压实验。从1.5Kbar压力,不同温度下恒温一周后的产物特征得出:煤中的气孔形成于250—350℃;镶嵌结构形成于350—500℃;随着温度增高,煤的各向异性指数略有增高;并且,与天然状态下的煤相比,其具有气孔及镶嵌结构煤的反射率值要低得多。     

甜菊不同叶龄叶片细胞ATPase活性的定位

在甜菊幼叶细胞中,ATPase活性定位于质膜、液泡、胞间连丝、细胞间隙及细胞壁的某些部位上。成熟叶细胞的液泡ATPase活性增强,而质膜ATPase活性减弱。当叶片接近衰老时,除叶绿体片层膜上表现较弱的ATPase活性外,其它部位的ATPase活性丧失。     

Primary observations of the existence of Fas-like cytoplasmic death factor in plant cells

The main activity of Fas is to trigger cytoplasm death program in animal cells. In G2 pea, vacuole plays a pivotal role in inducing cell death in the cytoplasm of longday (LD) grown apical meristem cells. Expression patterns of the Fas in G2 pea cells revealed that the Fas is mainly localized in the vacuole of cells undergoing programmed cell death (PCD). The Fas expression is corresponding to the initiation of menadione-induced PCD in tobacco protoplasts.The results suggest the existence of the Fas-like mediated cytoplasmic death pathway in plant cells.``     

Effects of the disaggregation of high—polymerized particles in guard cell vacuoles on osmoregulation of stomatal aperture（stomata opening）

Observation under an electron microscope reveals that in closed and open stomata of V.faba,the average volume of particles in guard cell vacuoles(GCV) reduces about 3 orders in magnitude,while the distribution density of the particles increases about 2 orders of magnitude.By using the method of the ration of fluorescent emissions with laser scanning confocal microscopy,the monitoring to stomata opening shows that during 10 to 30 s before the first distinguishable aperture of stomata,there is a change of pH in GCV about-0.5 units.A quick stomatal opening immediately follows the changes of pH in GCV to reach a steady aperture about 12μm in 100-200s.This work proposes a model for the osmoregulation in GCV for stomatal opening.The proposed osmoregulation is related to the disaggregation of some polymerized particles inside GCV,which is probably induced by a-ΔpH in the vacuole.This model describes a process of osmoregulation that avoids the massive energy consuming transportation across cell membranes,which is a foundation of the current chemiosmotic hypothesis.This model is a supplement to the multiple controlling hypothesis for the stomatal movement,which widens research principle ideas for other quick movements in plants.     

Vacuolation induced by unfavorable pH in cyanobacteria

Six species or strains of cyanobacteria, Anabaena sp. 595, Plectonema boryanum 246, Scytonema hofmanni 248, Nostoc sp. 96, Oscillatoria animlis 284 and Spirulina maxima 438, were cultured in unfavorable pH conditions for vacuole induction. At pH 5.0, 6.5, or 7.0, vacuoles were observed to form in both Anabaena sp. 595 and Plectonema boryanum 246, especially in the former. The vacuolation took place with some morphological changes, such as the cells being inflated, spherical and vacuolated, and with unequalized division. The induced vacuoles in An- abaena sp. 595 and Plectonema boryanum 246 were in spherical shape and in rather transparent appearance under a phase microscope. For Scytonema hofmanni 248, it was less sensitive to pH, its vacuole formation was found only at pH 6.5. No vacuolization occurred in the cells of Nostoc sp. 96, Oscillatoria animlis 284 and Spirulina maxima 438 at all pH conditions we used. Vacuolization under unfavorable pH provides a new proof for the existence of vacuole in cells of cyanobacteria and reflects the prokaryote's function in ecological environment.