Thyroid hormone action: in vitro demonstration of putative receptors in isolated nuclei and soluble nuclear extracts

Saturable binding activities for triiodothyronine were demonstrated in vitro with isolated nuclei and soluble nuclear extracts of rat liver, kidney, and cultured GH(1) cells. The binding activity can be extracted from nuclei in soluble form with no significant change in hormone affinity and has properties of a nonhistone protein.     

Synthesis of RNA-polyadenylic acid by isolated brain nuclei

Nuclei, isolated from mouse brain tissue at various stages of postnatal development and incubated under cell-free conditions, synthesized RNA molecules that were associated with polyadenylic acid [poly(A)]. The RNA synthesized by these nuclei was similar to the poly(A)-associated products described for intact eukaryotic cells. The brain nuclei synthesized a similar proportion of RNA-poly(A) in the presence either of Mg(2+) or of Mn(2+) with (NH(4))(2)So(4). The RNA from neonatal brain nuclei appeared to have a greater proportion of poly(A)-containing RNA than nuclear products obtained from more mature neural tissue.     

Antibody to nuclear material eluted from isolated spleen vessels in systemic lupus erythematosus

Splenic blood vessels were isolated from surrounding cells by treatment with trypsin and the use of ultrasound. This procedure retained vascular-bound immunoglobulins which were recovered by acid elution of vessels isolated from a patient with systemic lupus erythematosus. These eluted immunoglobulins reacted with material from cell nuclei as demonstrated by immunofluorescence.     

Identification of nuclear receptors for VIP on a human colonic adenocarcinoma cell line

Vasoactive intestinal peptide (VIP) is a neuropeptide with broad tissue distribution. Although its precise function is unknown, it is thought to exert its effect, at least in part, by interacting with cell surface receptors. Nuclear receptors for VIP have now been identified by specific binding of 125I-labeled VIP to nuclei of a human colonic adenocarcinoma cell line (HT29) and by cross-linking of 125I-labeled VIP to its receptor on intact nuclei. In contrast, 125I-labeled transferrin shows only background binding to nuclei but significant binding to intact cells. Purity of the isolated nuclei was further substantiated by electron microscopy. The apparent molecular sizes of the VIP--cross-linked nuclear and cell surface receptors are similar but not identical.     

Participation of c-myc protein in DNA synthesis of human cells

The protein product of oncogene c-myc is believed to be important in regulation of the cell cycle. However, its direct role in DNA synthesis has not been explored. Experiments presented here show that the addition of affinity-purified antibodies against the human c-myc protein to nuclei isolated from several types of human cells reversibly inhibited DNA synthesis and DNA polymerase activity of these nuclei. This suggests that c-myc encodes a protein that is functionally involved in DNA synthesis.     

猪链球菌2型溶菌酶释放蛋白诱导血管内皮细胞融合

 猪链球菌2型（SS2）主要引起人和猪的脑膜炎，但其毒力因子溶菌酶释放蛋白(MRP)对构成血脑屏障的微血管内皮细胞有何致病作用迄今不明。为此分离仔兔脾微血管内皮细胞（SMEC），纯化后用SV40-T抗原转化后用作试验的细胞模型。将单层SMEC和电泳纯MRP溶液共孵育，染色后，光镜观察，发现MRP可诱导SMEC发生两种典型形态学变化：致密细胞单层中出现巨大空洞而呈网状；空洞内有细胞融合，形成多核巨细胞，随后巨细胞核极度浓缩释出，巨细胞消失。研究结果表明， MRP单独足以破坏大脑的血管内皮细胞屏障。     

Estrogen-receptor interaction

The interaction of estradiol with uterine cells involves the association of the hormone with an extranuclear receptor protein, followed by temperature dependent translocation of the resulting complex to the nucleus. During this process, the steroid binding unit of the protein undergoes an alteration, called "receptor transformation," that can be recognized by an increase in its sedimentation rate from 3.8S to 5.2S, and by its acquisition of the ability to bind to isolated uterine nuclei and to alleviate a tissue specific deficiency in the RNA synthesizing capacity of such nuclei. Receptor transformation can be effected in the absence of nuclei by warming uterine cytosol with estradiol. This preparation of transformed complex resembles that extracted from nuclei both in its sedimentation rate (5.3S) and in its ability to bind to uterine nuclei and augment RNA synthesis, properties that are not shown by the native complex. It is proposed that receptor transformation is an important step in estrogen action and that a principal role of the hormone is to induce conversion of the receptor protein to a biochemically functional form.     

Histone synthesis in vitro by cytoplasmic microsomes from HeLa cells

HeLa cell microsomes incorporate labeled amino acids in vitro into acid-soluble proteins which have the same electrophoretic mobility as histones isolated from tile purified HeLa cell nuclei. The capacity to Svnthesize histones in vitro is dependent on deoxyribonucleic acid synthesis in the cells from which the microsonal fraction is prepared.     

Release of nuclear DNA template restrictions by specific polyribonucleotides

Certain synthetic homo- and copolyribonucleotide polymers are capable of releasing the DNA template restriction of isolated nuclei of rat liver cells when assayed with an excess of or in the absence of exogenous DNA polymerase. The purine homopolyribonucleotides are far more effective than are the pyrimidine polymers.     

玉米、胡萝卜核DNA的提取和鉴定

以胡萝卜、玉米悬浮细胞为材料,酶解后获得大量的原生质体并从原生质体中分离出大量纯净的细胞核。通过核裂解,热变性除蛋白等步骤提取到分子量大于50kb 的 DNA,DNA 制品纯度好,能满足分子克隆和遗传转化研究的要求。     

Nuclear factors in B lymphoma enhance splicing of mouse membrane-bound mu mRNA in Xenopus oocytes

Regulation of the synthesis of membrane-bound and secreted immunoglobulin mu heavy chains at the level of RNA processing is an important element for B cell development. The precursor mu RNA is either polyadenylated at the upstream poly(A) site (for the secreted form) or spliced (for the membrane-bound form) in a mutually exclusive manner. When the mouse mu gene linked to the SV40/HSV-TK hybrid promoter was microinjected into Xenopus oocytes, the mu messenger RNA (mRNA) was altered by coinjection of nuclei of mouse surface IgM-bearing B-lymphoma cells to include the synthesis of the membrane-bound form. An increase in the membrane-bound form was not observed when nuclei of IgM-secreting hybridoma cells or fibroblast cells were coinjected. Deletion of the upstream poly(A) site did not eliminate the effect of B-lymphoma nuclei suggesting that membrane-specific splicing is stimulated. Further, splicing of other mu gene introns was not affected by coinjection of B-lymphoma nuclei. These results suggest that mature B cells contain one or more transacting nuclear factors that stimulate splicing specific for membrane-bound mu mRNA.     

成熟木材细胞中存在细胞核的研究

本文详细观察了茶属（Ｃａｍｅｌｉａ）及蝴蝶果属（Ｃｌｅｉｄｉｏｃａｒｐｏｎ）次生木质部细胞核,并经改良石碳酸品红染色鉴定,确认其存在。研究发现,射线薄壁细胞的细胞核比较丰富,尤其以横卧射线细胞最明显,多呈圆形或椭圆形。而轴向薄壁细胞的细胞核较少,多在解体之中,呈椭圆形或纺锤形。细胞核还存在于大戟科（Ｅｕｐｈｏｒｂｉａｃｅａｅ）的乌桕属（Ｓａｐｉｕｍ）、血桐属（Ｍａｃａｒａｎｇａ）、野桐属（Ｍａｌｏｔｕｓ）及柿树科（Ｅｂｅｎａｃｅａｅ）的柿树属（Ｄｉｏｓｐｙｒｏｓ）等属木材中。成熟木材细胞中的细胞核是一个原始的特征,均出现在植物系统发育上较为原始的科属木材中。越原始的属或组,其木材中的细胞核越丰富,大而圆。较进化的属或组,其细胞核少而小,多呈纺锤形或弯月形。成熟木材细胞中的细胞核属于营养核,是一个稳定的特征。细胞核的存在,有利于树木养分在木薄壁组织细胞中运输或贮藏,生理功能旺盛。在成熟木材细胞中发现细胞核是木材解剖学的新发现。     

大白菜延伸DNA纤维的制备和检测(英文)

[目的]制备和检测大白菜延伸DNA纤维。[方法]以大白菜幼叶为材料,采用刀切分离细胞核、SDS释放DNA、盖玻片滑动牵拉DNA的方法,首次获得大白菜DNA延伸纤维。[结果]以基因组DNA和25SrDNA为探针进行原位杂交检测,该DNA纤维长度大约为1.93Mb,25SrDNA在大白菜基因组中的拷贝数在258-687之间。该方法获得的DNA延伸纤维平行、清晰、适合FISH分析。[结论]该研究将会促进大白菜基因图谱的构建和组织分析。     

家禽动眼神经副交感核和Cajal中介核至脊髓的直接投射——HRP法研究

采用微电泳导入法和微量注射法,将HRP分别引入脊髓的颈中部、颈膨大部和腰膨大部,逆行追踪了北京鸭、麻鸭、鹅、鸡、鸽子和鹌鹑6种家禽的上位神经元。结果发现：大量标记细胞不仅分布于中脑对侧红核,还分布于双侧的动眼神经副交感核（EW核）,Cajal中介核和中央灰质,少量标记细胞分布于中脑网状结构和中缝核。标记细胞分布数量的规律是：颈中部引入HRP后,出现的标记细胞最多;颈膨大部引入HRP者次之;腰膨大部引入HRP后,出现的标记细胞最少。两种方法的实验结果没有明显的差异。6种动物之间的差异也不显著。各组实验中,在中脑的顶盖没有任何部位出现标记细胞。研究结果表明：家禽的中脑脊髓通路中,除了具有红核脊髓束、网状脊髓束和中缝脊髓束外,还存在着EW核至脊髓的直接传导通路和Cajal中介核至脊髓的直接传导通路。     

稻麦胚乳游离核的分裂

用整体解剖法和树脂切片法观察了水稻、小麦和大麦胚乳游离核结构和分裂过程。结果表明，（１）胚乳游离核和胚乳细胞的分裂有２种形式：无丝分裂与有丝分裂，其中麦类以有丝分裂为主，水稻则以无丝分裂所占的比例很大；（２）核期结束时，游离核之间产生成膜体，由成膜体形成细胞壁；（３）胚乳核的分裂受多种因素影响，温度对胚乳核分裂影响最显著，气温高时分裂加快，核期缩短；（４）种间的胚乳核差异较大。通常细胞核小的种，核分裂的周期短。     

猪大脑皮质十字前回和后回的传入联系

用辣根过氧化物酶法研究了４只仔猪大脑皮质十字前回和后回传入神经的来源，将ＨＲＰ注入十字前回，在蓝斑，中缝背核，中脑中央灰质，丘脑背内侧核，腹前核，腹外侧核和板内核，十字前回和薛氏回等诸多结构内出现标记细胞。将ＨＲＰ注入十字后回，在蓝斑，中脑中央灰质，中缝背核，丘脑外侧核群，背内侧核，板内核，十字前回和后回，冠状回和扣带回等处出现标记细胞，结果表明，此二回均接受广泛的传入纤维，在丘脑皮质联系中，十字     

The Fos protein complex is associated with DNA in isolated nuclei and binds to DNA cellulose

The properties of the viral and cellular fos proteins (Fos) were investigated as a first step toward understanding the function of the fos gene. Treatment of nuclei with salt and nonionic detergents solubilized a complex that contained Fos together with several other cellular proteins. The majority of the Fos protein complex was released from isolated nuclei incubated in the presence of deoxyribonuclease I or micrococcal nuclease but not with ribonuclease A, suggesting that Fos is associated with chromatin. This hypothesis is supported by the finding that Fos protein from native or denatured nuclear extracts exhibited DNA-binding activity in vitro. These results suggest that Fos is involved in the regulation of gene expression.     

两个不同株系大豆花叶病毒侵染大豆细胞的超微病变比较研究

以大豆品种冀豆7号和大豆花叶病毒(SMV)株系SC-8、N3分别组成感病和抗病组合,运用电子显微镜比较观察了不同组合中大豆叶片细胞的超微结构变化。结果显示:在抗病组合的叶肉细胞中,侵染早期(接种8～12h),叶绿体膨胀,叶绿体片层结构轻微零乱,核染色质发生凝集现象;接种后24h,叶绿体继续膨胀变形,线粒体结构清晰完整,核变形严重;侵染后期(接种后72 h),细胞核近乎衰败,双层核膜已基本辨认不清,叶绿体结构基本解体。此时线粒体嵴突已发生退化,只有双层膜结构,内部出现空虚状态。细胞中的病毒粒子很少,也没发现柱状内含体结构。在此过程中,叶绿体和细胞核是最早做出反应的细胞器,而线粒体是最后解体的细胞器。感病组合中叶肉细胞超微结构的变化比抗病组合晚了10 h以上,细胞器的结构变化特征与抗病组合相似,但在所观察的整个互作过程中,核、叶绿体和线粒体的衰退是同步的,显示出了细胞被动死亡的特征;且在细胞死亡的整个过程中叶绿体上均有淀粉粒的积累,另外还观察到线粒体的异常增加现象,这可能是为了病毒粒子的增殖和柱状内含体的产生提供能量所致。