基底膜促细胞分化

个体发育取决于细胞分化。在细胞分化中,基因按一定的时间和空间次序选择地表达,通过基因的开启或关闭,最终表达特定的蛋白质。细胞分化受多种因素的影响,其中,基底膜是细胞分化的影响因素之一。基底膜中的主要成分有胶原、层黏连蛋白、蛋白聚糖,它们分别在细胞分化中起到一定作用。该文主要阐述基底膜及其主要成分在促细胞分化的作用和参与细胞分化的机制,为研究细胞分化提供新的思路。     

细胞分化与基因表达调控

细胞分化与基因表达调控刘德培,梁植权（中国医学科学院基础医学研究所）（医学分子生物学国家重点实验室）（北京东单三条五号１００００５）从单细胞受精卵发育成不同种类的细胞称为分化,细胞分化是基因选择性表达的结果。一系列的细胞分化、增殖与有序排列形成发育的个体。细胞分化过程体现个体发育的规律,同时也反映生物进化的信息。     

组蛋白赖氨酸的脱甲基化

组蛋白甲基化修饰调节染色质结构与基因转录,影响细胞分化与个体发育。2004年Shi等鉴定了第一个组蛋白脱甲基酶:赖氨酸特异性脱甲基酶1(lysinespecificdemethylase1,LSD1)。这个发现是“组蛋白密码”学说的重要进展,标志着组蛋白脱甲基化研究的开始。     

发育重演律与生物进化

发育重演律是生物个体发育的一般规律,该规律认为生物个体的发育是类囊胚不断形成和演化的过程,并认为生物进化亦是类囊胚不断形成和演化的过程.因类囊胚层级不断增加而导致的生物体结构复杂程度提高的演化为纵向进化,而不能提高生物体复杂程度的演化为横向演化,生物的纵向进化具有周期性.生物种系进化与个体发育之间具有严格的对应关系,一个物种经历的纵向进化的周期数与该物种所属个体完成发育所经历的细胞分化的周期数相等.     

核孔复合体的结构组装及其生理功能

核孔复合体(nuclear pore complex,NPC)介导了大分子物质在细胞质与细胞核之间的穿梭运动。NPC定位于核膜,形成一个疏水通道,使得蛋白质等大分子物质与转运受体结合,进行跨膜转运。这种经核孔复合体进行的跨核膜转运在细胞增殖、细胞分化以及个体发育等生命活动中发挥了重要的生理功能。     

动物中microRNA 的保守性和进化历程

microRNA 是一类长度约为22 个核苷酸的内源性非编码单链RNA, 在后生动物中普遍存在, 在转录后过程调控基因表达. miRNA 在个体发育过程中发挥着各种功能, 如发育时序调控和细胞分化、神经发育等. miRNA 在各种后生动物中具有保守性, 而且多个关键类群的出现皆伴随着大量新miRNA 的产生, 这些现象都表明miRNA 与动物的系统发生密切相关. 本文从miRNA 的产生和作用机制、在后生动物中的分布格局及其在个体发育中的调控功能3 个方面论述了miRNA 的保守性, 并结合miRNA 的发生和发展历程, 探讨了miRNA 在动物进化中起到的重要作用.     

胡子鲶的胚胎发育

用无膜卵的培养方法,比较详细地观察了胡子鲶胚胎发育的过程,并从早期个体发育的本质着眼提出了卵裂、细胞分化和器官分化三个主要胚胎发育阶段。分析了胚胎发育与环境条件的适应性。根据胡子鲶胚胎发育的特点,初步讨论了苗种生产中应该注意的几个问题,同时提出胡子鲶可以作为鱼类细胞工程研究的一个比较理想的实验鱼材料。       

癌细胞的诱导分化

专一性诱导物质的发现给研究细胞分化提供了一个有利的工具。诱导正常细胞分化的诱导物能否引起癌细胞正常分化?近年来,以色列 Sachs 教授为首的实验室对不同来源的髓性白血病作了广泛的研究。发现未成熟的正常髓细胞分化为巨噬细胞和粒细胞需要巨噬细胞——粒细胞诱导物(MGI)。而髓性白血病细胞亚株     

端粒相关蛋白TIN2

TIN2（TRFI相互作用核蛋白2）是一重要的端粒相关蛋白。人TIN2蛋白包括N端,TRF1交互作用区（TRF1—Int）和C端3个结构域。它在TRF1复合物、TRF2复合物和Sheherin的功能中扮演关键角色,协同其它端粒蛋白维持端粒长度、结构和功能。TIN2与个体发育、细胞分化和肿瘤发生密切相关。     

一组试题评析

[考查目标]本题以胰岛A、B细胞为载体，考查学生多个方面的知识点。①记忆胰岛A细胞、胰岛B细胞分泌的激素。②理解协同作用、拮抗作用，并根据两种激素各自的功能分析两种激素间的关系。③掌握基因控制蛋白质的合成过程。④熟悉个体发育的过程．知道体细胞都是受精卵有丝分裂产生的，都含有该生物的全套遗传信息。⑤理解细胞分化是基因选择性表达的结果，其遗传物质并没有改变。     

温州不同区域泽蛙染色体组型比较研究

本文报道温州四个不同区域泽蛙（ Ｒａｎａｌｉｍｎｏｃｈａｒｉｓ Ｂｏｉｅ） 的染色体组型。结果表明四处泽蛙均为２ｎ＝２６ （５ ＋８） , ＮＦ＝５２ 。温州市区、乐清、洞头泽蛙在６ｐ 上有一对次缢痕, 文成泽蛙在７ｐ 上有一对次缢痕。洞头、文成泽蛙ｎｏｓ－４、９、１１ 为ＳＭ 染色体, 其余均为Ｍ 染色体; 温州泽蛙ｎｏｓ－３、４、８ 为ＳＭ, 其余均为Ｍ 染色体;乐清泽蛙ｎｏｓ－４、９ 为ＳＭ 染色体, 其余均为Ｍ 染色体。通过温州不同区域以及国内外其它地区泽蛙染色体组型的比较, 结果差异明显, 显示泽蛙核型的多样性。     

金线蛙早期胚胎发育的初步观察

报道了金线蛙的早期胚胎发育。自受精卵期至鳃盖完成期共分为 2 6个时期 ,其发育历程及各时期胚胎外形特征与黑斑蛙基本相似 ,但孵化期比黑斑蛙推迟三个胚期而早于泽蛙 ,在水温 ( 2 0± 0 5)℃及常温 ( 2 1 5～ 2 4℃ )条件下 ,其胚胎发育的全时程分别为 2 1 2 94小时和 1 70 95小时。     

单套染色体组在泽蛙雌核单倍体发育中的作用

本文比较了泽蛙(Rana limnocharis Boie)单倍体和二倍体的胚胎发育。结果表明:泽蛙单倍体的生活力低下,器官发生异常,自原肠胚起发育速度减慢。据此,作者讨论了单套染色体组在个体发育中的作用。     

泽蛙单倍体细胞RNA含量对胚胎发育和成活的影响

对两栖类单倍体的综合症以及死亡原因,前人有许多不同认识,本文用实验说明,单倍体细胞的RNA含量不及二倍体的一半,并认为,单倍体泽蛙的死亡原因与其细胞中RNA含量不足密切相关。     

Inter- and intraspecific evolutionary relationships of the rice frog Rana limnocharis and the allied species R. cancrivora inferred from crossing experiments and mitochondrial DNA sequences of the 12S and 16S rRNA genes

The rice frog Rana limnocharis is widely distributed in Southeast Asia and the rest of the Asian region extending from India to Japan. In Japan, the Sakishima-island populations of this species were regarded as a distinct species based on morphological and genetic divergences. The main purposes of this study were to confirm the presence of intraspecific reproductively isolating mechanisms in the Sakishima-island populations of R. limnocharis, and to clarify molecular inter- and intraspecific relationships of R. limnocharis and an allied species, Rana cancrivora. The hybridization experiments revealed that there were no reproductively isolating mechanisms between the Sakishima-island populations and other populations of R. limnocharis. The molecular evolutionary relationships were investigated by analyzing nucleotide sequences of the mitochondrial 12S and 16S rRNA genes using 12 populations of R. limnocharis from Japan and Taiwan, and two populations of R. cancrivora from Thailand and the Philippines. The phylogenetic trees constructed by the NJ method showed that the two populations of R. cancrivora were clearly separated from the 12 populations of R. limnocharis, and that the 12 populations of R. limnocharis were broadly divided into three clades; the first comprising eight populations from the main islands of Japan, the second comprising the Sakishima-island populations, and the third comprising the Okinawa-island and Taiwan populations. Interestingly, the Okinawa-island and Taiwan populations of R. limnocharis showed a close relationship that possibly reflected a secondary contact between the two populations. Based on the present crossing experiments and molecular data, it seems reasonable to regard the Sakishima-island populations as a single subspecies of R. limnocharis.     

云南南部3产地泽蛙核型比较研究

对采自云南个旧、绿春、江城3地的泽蛙进行染色体核型分析。结果表明,3地的泽蛙核型均为2n=26（5L＋0M＋8S）,NF=52,染色体次缢痕均出现在6p上。个旧大屯泽蛙的No．3为SM染色体,其余染色体均为M染色体;绿春大黑山的泽蛙No．2、6、7为SM染色体,其余均为M染色体;江城康平的泽蛙No．2、9均为SM染色体,其余为M染色体,显示出不同地区泽蛙核型的差异性。比较了滇南3地和国内外不同地区泽蛙染色体核型变化,结果显示,染色体核型模式及其大型染色体组比较稳定,但次缢痕位置不稳定,小型染色体组变异较大。根据泽蛙次缢痕的地理演化趋势,推测次缢痕位于7p上是一种原始类型,位于6p上是一种较为进化的类型,位于9p上是一种特化的类型。泽蛙的分布及核型分化与第三纪欧亚大陆边缘断裂形成日本海有关,也与第四纪冰期气候变化和随之产生的泽蛙南迁北移有关。     

上海农田泽蛙蛰眠状况初步调查

于2004～2005年冬季对上海农田泽蛙的蛰眠状况进行了初步调查。结果表明,农田中的路径、田埂和沟渠岸边地下洞穴是泽蛙的主要越冬场所。蛰眠洞穴共用率高达34.0%,超过62.2%的泽蛙与其它个体共用洞穴蛰眠,各共用洞穴内的泽蛙只数为2～6只不等。泽蛙主要利用已有的地下洞穴蛰眠。86.6%蛰眠期的泽蛙为1龄个体。     

Back-transfer of late gastrula nuclei of nucleocytoplasmic hybrids

Late gastrula-early neurula endoderm nuclei from nucleocytoplasmic hybrids consisting of Rana pipiens nuclei and Rana palustris cytoplasm were back-transferred into enucleated eggs of Rana pipiens. Approximately half of the normally cleaved back-transfer embryos developed normally. A similar result was obtained with nuclear transfer controls. As expected, the development of the nucleocytoplasmic hybrid donors, at the time the back-transfers were carried out, was clearly abnormal. Consequently, a significant proportion of endoderm nuclei from these embryos undergo no irreversible changes in their developmental capacity even after the nucleocytoplasmic incompatibility between these two amphibian species is expressed.     

泽蛙原蛙片虫的形态学研究

对采自湖北省洪湖地区的泽蛙(Fejervarya limnocharis)肠道内寄生的泽蛙原蛙片虫进行了形态学再描述, 包括活体形态、固定染色标本形态及扫描电镜下超微结构。样本形态特征参数值与Nie(倪达书)首次发现并命名时所记述标本参数值颇为相符(包括体长、体宽, 核长、核宽)。此外, 本文对2个重要的分类特征进行了补充和修正: (1)缝线位于虫体顶端, 贯穿背腹侧; 所有体动基列均从缝线两侧发出。(2)胞核分裂时在两新核间产生的连接细丝, 在虫体整个生活周期一直存在。并针对这2点特征与其他已知的原蛙片虫属种类进行了比较和讨论: 认为缝线结构是较为稳定的分类特征之一, 体动基列均由此处生发并与虫体纵轴平行延伸; 推测泽蛙原蛙片虫子代虫体中的2个胞核均来自于母体中同一个核, 而其2核间的连接细丝可能是胞核分裂进化历程中比较原始的残迹。     

Nuclear ribonucleoprotein complexes of amphibian liver. II. Changes in the protein moiety during development.

Ribonucleoprotein complexes composed of small molecular weight nuclear RNA (4--9 S) and proteins were isolated from hepatic nuclei of Rana catesbeiana (bullfrog) and the protein moiety of this nuclear ribonucleoprotein complex compared during different stages of development. SDS-polyacrylamide gel analysis of premetamorphic tadpoles and adult frog nuclear ribonucleoprotein complexes revealed that while the protein profiles of these two particles were very similar polypeptides of 47,000, 70,000, and 11,000 molecular weight were present in significantly higher concentrations in the frog ribonucleoprotein complexes. Comparison of the chromatin proteins isolated from these two developmental stages demonstrated that these three polypeptides of frog ribonucleoprotein were not contaminants from chromatin. Since these three polypeptides could not be preferentially extracted from the frog ribonucleoprotein complex by 0.5 M KCl or 1 M urea, it was unlikely that these polypeptides were bound nonspecifically to the ribonucleoprotein particle. Polypeptide analysis of the nuclear ribonucleoprotein complexes isolated from tadpoles immersed in the thyroid hormone L-thyroxine revealed an increase in two polypeptides of 37,000 and 45,000 molecular weight during metamorphosis. The absence of reduced amount of these two polypeptides in either the premetamorphic tadpole or adult frog demonstrated that their presence in Rana catesbeiana nuclear ribonucleoprotein was transient during development and specifically associated with tadpole metamorphosis. We conclude from these experiments that the nuclear ribonucleoprotein complex is a dynamic structure during Rana catesbeiana development and that specific changes in its protein composition are associated with discrete stages of amphibian development.