温度休克法诱导草履虫的同步分裂

运用细胞周期原理,采用温度休克法,对尾草履虫进行分裂周期同步化的研究,实验中草履虫经过3－5h的处理后,就能观察到大量不同阶段的无性生殖横分裂状态,并获得了大量处于分裂阶段的草履虫。运用这种技术取材容易,获取率稳定,可达61％,可为细胞生理学等领域的研究提供大量的同步分裂个体。     

硒对金黄滴虫生长谷胱甘肽过氧化物酶及超微结构的影响

金黄滴虫在含硒1ppm的培养液中的生长情况和超微结构与对照组的细胞基本相同。在含硒6ppm的培养液中,前48小时细胞生长正常,以后容器中出现类似硫化氢的气味,细胞数量急剧下降,细胞变圆,运动缓慢,叶绿体变小并且绿色减退,金藻糖泡增大,在干涉显微镜下可见核仁中央下陷,成一小凹。在电镜下,核仁的中央区电子密度很低,这一区域可能相当于干涉镜下所见的小凹。在另一切面上可以看出这一区域是有开口与核基质相通的。电镜照片还揭示叶绿体结构松散,类囊体减少,在稀薄的基质中出现一些直径约为0.4—0.5μ的核仁样小体。部分细胞的线粒体形态异常,内质网及管状纤维增多。此外,作者测定了细胞谷胱甘肽过氧化物酶的活性的变化,并对硒的作用、核仁和叶绿体的变化以及核仁样小体的性质进行了讨论。     

温度休克法诱导草履虫的同步分裂

运用细胞周期原理,采用温度休克法,对尾草履虫进行分裂周期同步化的研究,实验中草履虫经过3～5 h的处理后,就能观察到大量不同阶段的无性生殖横分裂状态,并获得了大量处于分裂阶段的草履虫.运用这种技术取材容易,获取率稳定,可达61%,可为细胞生理学等领域的研究提供大量的同步分裂个体.     

细胞的无丝分裂

无丝分裂(amitosis)又称直接分裂,是雷马克(Remak 1841)在鸡胚血球细胞中首先见到的,随即有人在哺乳类胚胎的血细胞中也有发现,是细胞分裂三种方式中最早发现的一种最简单的分裂方式。     

细胞不对称分裂

细胞不对称分裂是多细胞生物发育的基础。细胞不对称分裂的重要特征是细胞命运决定子在细胞分裂期间的不对称分离。细胞不对称分裂一般要经历4个步骤：在细胞中建立一个极性轴;沿此轴定向并形成纺锤体;细胞命运决定子沿极性轴作极性分布;细胞分裂后,不同的细胞命运决定子指导决定细胞的不同命运。     

B细胞不对称分裂

细胞的不对称分裂对于细胞多样性产生的重要性已经被大部分人所认识。B细胞的不对称分裂首先是在抗体类别转换的研究中发现的。最近,美国5科学家对B细胞在免疫发生中心中不对称分裂的原因进行了探索。结果发表在2012年1月20日出版的《Science》中。B细胞的不对称分裂参与体液免疫的抗体类别转换和抗体亲和力成熟过程。对于其机制仍不清楚,但目前研究初步提示细胞内分子的不对称分布是其发生的上游因素。并且B细胞的不对称分裂可能与不对称抗原分离可能在抗体亲和力成熟过程中具有独立协同作用。     

非编码RNACARL抑制缺氧诱导的心肌细胞线粒体分裂以及细胞凋亡

正越来越多的研究发现线粒体的形态和功能异常与许多疾病的发病过程紧密相关,并且长链非编码RNA(lncRNA)也能够调节基因的表达。在正常细胞中,线粒体不断的发生分裂和融合,形成一个功能性的动态网络结构,维持细胞的生理功能。心脏是体内唯一的泵血器官,通过心肌细胞的不断收缩和舒张推动全身血液循环。心肌细胞对能量有大量的需求,因而细胞内主要的供能器官线粒体是否正常运转对线粒体形态的     

线粒体分裂、融合与细胞凋亡

线粒体是高度动态变化的细胞器,其在细胞内不断分裂、融合并形成网状结构。线粒体的分裂和融合是由多种蛋白质精确调控完成的。Drp1／Dnm1p,Fis1／Fis1p,Caf4p和Mdv1p参与线粒体分裂的调控;Mfn1／2／Fzo1p控制线粒体外膜的融合,而Mgm1p／OPA1则参与线粒体内膜的融合。在细胞凋亡过程中线粒体片段化,网状结构被破坏,线粒体嵴发生重构,抑制这一过程可以部分抑制细胞色素c的释放和细胞凋亡。线粒体形态对于细胞维持正常生理代谢和机体发育起着重要的作用,一旦出现障碍会导致严重的疾病。     

植物细胞多倍体诱导实验方法的改进

从植物多倍体诱导实验材料处理的方法上,介绍了改进植物多倍体诱导实验的技术,提高了多倍体细胞的分裂指数。实验用0．1％和0．01％浓度的秋水仙素溶液分别处理大蒜根尖24h、36h、48h、72h,进行多倍体诱导,再在清水中分别培养0h、12h、24h、36h,结果表明经清水培养的多倍体细胞分裂指数高于对照：0．01％浓度的秋水仙素处理的多倍体细胞分裂指数高于0．1％多倍体细胞分裂指数。     

一氧化氮诱导细胞调亡

一氧化氮(NO)参与体内众多的生理病理过程,最近发现NO与细胞凋亡关系密切,可诱发多种细胞发生凋亡,并与其他活性氧自由基(ROS)的凋亡传导途径之间存在对话效应,NO诱导凋亡促进p53基因表达,其分子作用机理正是目前的研究重点。     

金黄滴虫叶绿体拟核的荧光镜检及电镜观察

金黄滴虫细胞在用DNA特异的荧光染料DAPI处理后,在荧光显微镜下细胞核和叶绿体拟核均散发蓝色荧光,穗晰可见。每一叶绿体有一拟核,拟核沿叶绿体的周缘排列,形状相当于叶绿体的轮廓,成不规则的两叶形环。环的全长约在20—30υm之间。 拟核环大多是单线的,有些拟核环出现或短或长的双线部分,有时甚至几乎整个拟核环都可变为双线。这表明拟核环通过“纵裂”而形成双环,在叶绿体分裂时,分别进入两个子叶绿体。这一情况在电镜照片上得到了证实。 叶绿体分裂和细胞分裂之间似乎不存在严格的相关性,这是导致细胞中叶绿体数目多于1个的原因。     

金黄滴虫粘液泡的研究

用酸性粘多糖特异性染料(阿利新蓝或阿利新蓝 甲基绿)和脂肪特异性染料(如苏丹Ⅲ等)同时染活细胞,粘液泡染成蓝色,脂肪滴染成红色。活细胞的粘液泡有自发的蓝色荧光。脂肪滴无荧光。用含有阿利新蓝的戊二醛固定样品,再用O_s真O_4后固定,进行电镜观察,粘液泡呈电子致密的深黑色小泡,而脂肪滴呈灰色小泡,粘液泡的表面常盖有毛状的附属物,其形态反映了粘液泡的液体性质。在同泽的固定材料中,细胞表膜也常存在一厚层与粘液泡表面相似的毛状物质。二者应含有相同的成分,即都含有酸性粘多糖。表膜的粘多糖外被可能主要是由粘液泡向外释放的物质所形成的。电镜细胞化学的检定还表明粘液泡的表面有酸性磷酸酶的活性。粘液泡和盘状泡是同源的细胞器。     

NOVEL PROTEINS COMPRISING THE STRAMENOPILE TRIPARTITE MASTIGONEME IN OCHROMONAS DANICA (CHRYSOPHYCEAE)1

Two‐dimensional (2‐D) protein analysis of the mastigoneme fraction of the chromophyte alga Ochromonas danica E. G. Pringsh. showed the presence of several component proteins of the tubular mastigoneme. Adding to the reported gene Ocm1, three new genes (Ocm2, Ocm3, and Ocm4) belonging to the Ocm gene family were isolated using degenerate primers designed from predicted Ocm1 amino acid sequences. The predicted polypeptides encoded by Ocm2, Ocm3, and Ocm4 were smaller in size than Ocm1. However, they shared four highly conserved, cysteine‐rich, epithelial growth factor (EGF)‐like motifs, potentially involved in protein–protein interaction. In addition, Ocm2, Ocm3, and Ocm4 showed homology to the SIG protein family in the centric diatom Thalassiosira weissflogii (Grunow) Fryxell et Hasle, which is up‐regulated during early stages of sexual reproduction. Immunofluorescence analysis with a polyclonal antibody against the partial amino acid sequences of Ocm2, Ocm3, and Ocm4 showed that Ocm2 and Ocm3 were located in the basal segment region of mastigonemes attached on the surface of the anterior flagellum, and that Ocm4 was located within the tubular shaft portion similar to Ocm1.     

THE FINE STRUCTURE OF MITOSIS AND CELL DIVISION IN THE CHRYSOPHYCEAN ALGA OCHROMONAS DANICA1

At the ultrastructural level, cell division in Ochromonas danica exhibits several unusual features. During interphase, the basal bodies of the 2 flagella replicate and the chloroplast divides by constriction between its 2 lobes. The rhizoplast, which is a fibrous striated root attached to the basal body of the long flagellum, extends under the Golgi body to the surface of the nucleus in interphase cells. During proprophase, the Golgi body replicates, apparently by division, and a daughter rhizoplast, appears. During prophase, the 2 pairs of flagellar basal bodies, each with their accompanying rhizoplast and Golgi body, begin to separate. Three or 4 flagella are already present at this stage. At the same time, there is a proliferation of microtubules outside the nuclear envelope. Gaps then appear in the nuclear envelope, admitting the microtubules into the nucleus, where they form a spindle. A unique feature of mitosis in O. danica is that the 2 rhizoplasts form the poles of the spindle, spindle microtubules inserting directly onto the rhizoplasts. Some of the spindle microtubules extend from pole to pole; others appear to attach to the chromosomes. Kinetochores, however, are not present. The nuclear envelope breaks down, except, in the regions adjacent, to the chloroplasts; chloroplast ER remains intact throughout mitosis. At late anaphase the chromosomes come to lie against part of the chloroplast ER. This segment of the chloroplast ER appears to be incorporated as part of the reforming nuclear envelope, thus reestablishing the characteristic nuclear envelope—chloroplast ER association of the interphase cell.     

A TUBULAR MASTIGONEME‐RELATED PROTEIN,OCM1, ISOLATED FROM THE FLAGELLUM OF A CHROMOPHYTE ALGA,OCHROMONAS DANICA1

The phylogenetic group stramenopiles refers to the systematic groups that possess tripartite tubular hairs (stramenopiles) on their flagella. There have been a number of studies describing the fine structure of these mastigonemes and a few studies isolating the component proteins; however, these proteins and their gene sequences have not yet been identified. In the present study, we identified a mastigoneme protein (Ocm1) of the chrysophycean alga Ochromonas danica Pringsh. (UTEX LB1298). Its corresponding gene, Ocm1, was identified by using degenerate primers that correspond to the partial amino acid sequences of a protein (85 kDa) obtained from a mastigoneme‐rich fraction of isolated flagella. The polypeptide encoded by Ocm1 has four cysteine‐rich, epithelial growth factor (EGF)–like motifs, potentially involved in protein–protein interactions. It lacks obvious hydrophobic regions characteristic of transmembrane domains, suggesting that this polypeptide is not likely a protein for anchoring the mastigoneme. In addition, a polyclonal antibody against Ocm1 labeled the area where the tubular shafts of the mastigonemes are located, but not the basal portion or the terminal filaments.     

EFFECTS OF CHLORAMPHENICOL ON CHLOROPLAST AND MITOCHONDRIAL ULTRASTRUCTURE IN OCHROMONAS DANICA

The effect of chloramphenicol (CAP) on cell division and organelle ultrastructure was studied during light-induced chloroplast development in the Chrysophyte alga, Ochromonas danica. Since the growth rate of the CAP-treated cells is the same as that of the control cells for the first 12 hr in the light, CAP is presumed to be acting during that interval solely by inhibiting protein synthesis on chloroplast and mitochondrial ribosomes. CAP markedly inhibits chloroplast growth and differentiation. During the first 12 hr in the light, chlorophyll synthesis is inhibited by 93%, the formation of new thylakoid membranes is reduced by 91%, and the synthesis of chloroplast ribosomes is inhibited by 81%. Other chloroplast-associated abnormalities which occur during the first 12 hr and become more pronounced with extended CAP treatment are the presence of prolamellar bodies and of abnormal stacks of thylakoids, the proliferation of the perinuclear reticulum, and the accumulation of dense granular material between the chloroplast envelope and the chloroplast endoplasmic reticulum. CAP also causes a progressive loss of the mitochondrial cristae, which is paralleled by a decline in the growth rate of the cells, but it has no effect on the synthesis of mitochondrial ribosomes. We postulate that one or more chloroplast ribosomal proteins are synthesized on chloroplast ribosomes, whereas mitochondrial ribosomal proteins are synthesized on cytoplasmic ribosomes.     

Cryopreservation of Ochromonas in Liquid Nitrogen with Reproducibility of Thiamin Assay

The first successful cryopreservation of Ochromonas danica and Ochromonas malhamensis is reported. The freezing method was consistently reproducible for the former, but not for the latter. Ochromonas danica cultures established from frozen material still could be used as test organisms for assay of thiamin. This is the first report of a protozoon retaining its assay property after being frozen to -196 C.     

REPRODUCTIVE SYNCHRONY AND THE ESTIMATION OF MEAN DATE OF BIRTH FROM DAILY COUNTS OF NORTHERN FUR SEAL PUPS

Two methods for estimating the mean date of birth from daily counts of northern fur seal pups ( Callorhinus ursinus ) are presented and applied to data collected on the Pribilof Islands in 1951, 1962, 1963 and 1983. The mean date of birth over the four years was July 9. Reproduction is highly synchronized and consistent from one year to the next. Pupping occurs over a five week period with over 50% of the pups being born during the first two weeks of July.     

用MNNG体外诱发人胚肺成纤维细胞的肿瘤性转化

本实验用直接致癌物MNNG处理体外培养的人胎儿肺成纤维细胞的早代培养物,诱发了肿瘤性转化,包括形态改变,转化灶的形成、较高的饱和密度,半固体琼脂培养基中较高的集落形成率,染色体畸变,寿命延长,鸡胚皮肤浸润以及异种接种形成了肿瘤。在实验中,通过不同剂量,不同次数的处理,在一定的范围内得到了剂量、处理次数与肿瘤性转化的正相关。