A FIBER APPARATUS IN THE NUCLEUS OF THE YEAST CELL

The structure and mode of division of the nucleus of budding yeast cells have been studied by phase-contrast microscopy during life and by ordinary microscopy after Helly fixation. The components of the nucleus were differentially stained by the Feulgen procedure, with Giemsa solution after hydrolysis, and with iron alum haematoxylin. New information was obtained in cells fixed in Helly's by directly staining them with 0.005% acid fuchsin in 1% acetic acid in water. Electron micrographs have been made of sections of cells that were first fixed with 3% glutaraldehyde, then divested of their walls with snail juice, and postfixed with osmium tetroxide. Light and electron microscopy have given concordant information about the organization of the yeast nucleus. A peripheral segment of the nucleus is occupied by relatively dense matter (the "peripheral cluster" of Mundkur) which is Feulgen negative. The greater part of the nucleus is filled with fine-grained Feulgen-positive matter of low density in which chromosomes could not be identified. Chromosomes become visible in this region under the light microscope at meiosis. In the chromatin lies a short fiber with strong affinity for acid fuchsin. The nucleus divides by elongation and constriction, and during this process the fiber becomes long and thin. Electron microscopy has resolved it into a bundle of dark-edged 150 to 180 A filaments which extends between "centriolar plaques" that are attached to the nuclear envelope.     

甲状腺肿瘤细胞核DNA含量测定对病理诊断的意义

应用真彩色医学图像分析技术, 对９０ 例甲状腺肿瘤（其中甲状腺腺瘤１０ 例, 不典型腺瘤１５ 例,乳头状腺癌２５ 例, 滤泡癌１５ 例, 髓样癌１５ 例, 未分化癌１０ 例） 细胞核ＤＮＡ含量进行了分析。结果显示,甲状腺腺瘤组与各型甲状腺癌比较均有显著性差异（Ｐ＜ ００１）,甲状腺腺瘤组同不典型腺瘤组比较无统计学意义（Ｐ＞ ００５）。甲状腺癌随组织分化程度的不同, ＤＮＡ 含量明显增加, 多为高倍异倍体细胞, ＤＮＡ直方图明显右移, 峰值主要位于≥５Ｃ处; 甲状腺腺瘤组ＤＮＡ含量较低, 多为低倍整倍体细胞, ＤＮＡ 直方图峰值位于２Ｃ－ ４Ｃ处; 不典型腺瘤组ＤＮＡ含量介于上述二者之间, ＤＮＡ 直方图逐渐右移。表明ＤＮＡ倍性程度与肿瘤的增殖程度呈正相关, 高倍异倍体细胞随肿瘤恶性程度的增高而增多。作者认为ＤＮＡ原位图像定量分析可为甲状腺肿瘤的诊断、分级及早期发现癌变趋势提供一个可靠的参考指标     

朱顶红花粉管中营养核和生殖细胞位置的变换

用一种改进的ＦＩＴＣ微管蛋白免疫荧光和ＤＡＰＩ双定位的技术,在紫外光激发下能同时显示花粉管中的生殖细胞（ＧＣ）和营养核（ＶＮ）。在朱顶红（Ａｍ ａｒｙｌｌｉｓ ｖｉｔｔａｔａ Ａｉｔ．）花粉萌发的最初１—２ 小时内,ＧＣ和ＶＮ 都有可能从花粉粒先进入花粉管。然而,在ＧＣ分裂前ＶＮ 总是变为在ＧＣ之前和接近花粉管顶端的位置。因此,在生殖细胞先进入花粉管的情况下,ＶＮ必然越过ＧＣ而使位置发生变换。根据观察的图象可以总结出三种基本的过程。１． 在萌发后约２小时,营养核位于ＧＣ后端延伸的细胞质附近,形成暂时的物理联结。２．ＶＮ 进一步向前更快地移动,以致整个ＶＮ 与ＧＣ并列和紧靠,它们常相互扭结在一起。３．ＶＮ 越过ＧＣ,并变为高度延长,它的后端常部分地插入生殖细胞的细胞质中。观察结果表明：ＶＮ和ＧＣ通过花粉管时移动的速度是明显不同的。这种速度的差别可以认为存在各自独立运动的机制,以及ＶＮ 和ＧＣ本身结构的差别,为它们在花粉管中的移动提供各自运动的动力     

双滴虫与细胞核起源问题的探索──庆祝潘清华老师八十寿辰

分析了可能用作研究原始性细胞核的模型的涡鞭毛虫与双滴虫核,发现实际上只有后者是适用的。以蓝氏贾第虫（Ｇｉａｒｉｄｉａｌａｍｂｌｉａ）作为双滴虫类的代表,对其核作了多方面的考察,发现其核中确实还没有核仁;核被膜上有天然的缺口;但核内已经有了核骨架及５种组蛋白。比较的免疫印迹检查表明,在检查到的各种原生生物中,蓝氏贾第虫的着丝粒／动粒蛋白最接近于原细菌的相应蛋白。有人怀疑蓝氏贾第虫缺少线粒体及典型高尔基氏器等原始性特征实际上不过是由于过寄生生活所致。本文针对这种怀疑进行了多方面的分析。其实所有过自由生活的双滴虫类都没有线粒体及典型高尔基氏器,看来也全都没有核仁,核被膜全都有缺口。依据上述的发现,对真核细胞发生之初原始性细胞核的特性进行了推断,进而对细胞核的整个起源过程进行了分析：认为在真核细胞的原细菌祖先体内就已经有了核骨架;多个类核体的ＤＮＡ结合在其上而构成了核区。我们关于组蛋白的分子进化研究表明,核小体组蛋白的共同祖先在极早的时候就已经分化成了４种。因此可以相信,真核细胞的原细菌祖先很早就有了４种核小体组蛋白和核小体。本文着重分析了染色体的起源过程并进一步发展了过去已经提出的核被膜起源于原始性内质网的学说（     

AgNORs异型颗粒在乳腺癌细胞核中的观察分析

本文报道了核仁组成区嗜银蛋白（ＡｇＮＯＲｓ）在乳腺癌细胞核中的一组异型颗粒——字母样结构“ＣＥＩＪＲＳＴＵＲＹＸ”等,乳腺良性病变无此结构。研究结果表明,字母样结构在浸润性导管癌中多见,在乳头状癌中未见。结合乳腺癌的临床分期分析,临床分期越高,有字母样结构的乳腺癌所占比分也越高。同时,有字母样结构的乳腺癌组其ＡｇＮＯＲｓ含量和颗粒形态的异型性均明显高于无字母样结构的乳腺癌组。在讨论中认为,ＡｇＮＯＲｓ字母样结构对鉴别诊断乳腺癌可能有一定的形态学参考价值     

中缝背核对猫小脑浦肯野细胞电活动的影响

在麻醉并麻痹的猫上观察到:刺激中缝背核(DR)可引起小脑皮层浦肯野细胞(PC)兴奋或抑制(主要是抑制);由被动性腕关节屈伸运动刺激引起的外周本体传入可以增强或减速PC对DR刺激的反应。这些结果表明中缝-小脑5-HT能纤维的传入活动可以调制PC的放电活动,并与外周传入有相互作用。     

土麦冬离体萌发花粉管中生殖细胞与营养核的动态变化

主要报道了土麦冬人工培养萌发花粉管中生殖细胞与营养核的动态变化。多数花粉管中,生殖细胞与营养核贴合后,开始进行有丝分裂,贴合时,营养核略呈弥散状态。在分裂早中期,生殖细胞与营养核分开,从贴合到分开大约经历３－５ｈ,精子形成后,不与营养核连接。ＤＡＰＩ对生殖细胞的有丝分裂有抑制作用。少数花粉管中,生殖细胞核进行无丝分裂,有缢裂和劈裂两种方式。生殖细胞核发生缢裂的花粉管中,未观察到生殖细胞与营养核的贴     

THE DISTRIBUTION OF THE WATER-SOLUBLE INORGANIC ORTHOPHOSPHATE IONS WITHIN THE CELL: ACCUMULATION IN THE NUCLEUS : Electron Probe Microanalysis

Lead acetate treatment of unfixed cells immobilizes the intracellular water-soluble, inorganic orthophosphate ions as microcrystalline lead hydroxyapatite precipitates (see reference 1). These precipitates have been analyzed with the electron microprobe. A much higher concentration of phosphorus has been found in the nucleoli of maize root tip cells fixed in lead acetate-glutaraldehyde (organic phosphorus plus inorganic orthophosphate), as compared to the nucleoli of roots fixed in glutaraldehyde alone (organic phosphorus). The concentration of the inorganic orthophosphate pool in these nucleoli is three to five times as high as the concentration of the macromolecular organic phosphate. Since nearly all of the latter is in RNA, the concentration of inorganic phosphate in the nucleolus is calculated to be roughly 0.5–0.8 M. About 30%—and up to 50%—of the total cellular inorganic phosphate is accumulated in the nucleolus since the mean concentration per cell is about 10^-2 M. In the extranucleolar part of the nucleus the mean concentration was estimated by densitometry to be roughly six times less than in the nucleolus (⩽ 0.1 M), and appears more concentrated in the nucleoplasm than in the condensed chromatin. While there is no direct evidence for the concentration in the cytoplasm, it certainly must be much lower than the mean cellular level (i.e., < 10^-2 M) since the nucleus is about 10% of the total cell volume. The implications of this compartmentation in the intact cell are discussed in connection with (A) the availability of orthophosphate ions for the cytoplasm in those processes in which these ions affect the rate of enzymatic reactions, and (B) protein nucleic acid interactions within the nucleus and nucleolus.     

CHROMOSIN,A DESOXYRIBOSE NUCLEOPROTEIN COMPLEX OF THE CELL NUCLEUS

A desoxyribose nucleoprotein complex, which we have referred to as a chromosin, has been prepared from a great variety of cells, mainly animal but also plant and bacterial. A chromosin is derived from the cell nucleus. In the course of preparation precautions have been taken to prevent contamination by cytoplasmic constituents. To assure the nuclear origin of all components of chromosin, nuclei have in several instances been isolated before extraction was begun. Because of the precautions taken, chromosins do not contain detectable quantities of ribose nucleoproteins; but, incidentally, extraction of ribose nucleoproteins, free of desoxyribose compounds, has also been described in this paper. A typical chromosin contains 3 components: desoxyribose nucleic acid, histone, and non-histone protein. The nucleic acid, being highly polymerized, is exceedingly viscous when dissolved and fibrous when precipitated. Histone and non-histone protein differ from each other in a number of ways, of which one of the most definite is that whereas a histone contains no more than traces of tryptophane, the non-histone protein of chromosin contains nearly 1 per cent of tryptophane. In neutral physiological saline both proteins can combine with nucleic acid. With the isolation of chromosins from so many different kinds of cells, it can now be seen that (contrary to the view expressed by Kossel) histones are present in most animal cells and at least in some plant and bacterial cells. Chromosin prepared from the Type III pneumococcus is active in transforming the type of a pneumococcus culture. It has been pointed out that it is not yet known whether or not protein is a necessary constituent of the transforming agent. To extract chromosin from a cell M NaCl is used. When dissolved in M NaCl the nucleic acid and histone components of a chromosin are to a considerable extent dissociated. They are not dissociated when the chromosin is dissolved in 0.02 M NaCl, but in this medium a partial depolymerization of the nucleic acid occurs. A chromosin should certainly not be considered to be a definite chemical compound. It is a complex extracted from chromatin, which is itself a complicated nuclear structure. And in the course of extraction, it need hardly be said, the structure of chromatin has been considerably changed. To avoid complications it has been considered an advantage in this work to begin with isolated nuclei, and it would clearly be a further simplification to begin chemical procedures only after the chromosomes themselves have been isolated. This is now being accomplished, and it is found that the methods described in this paper are of value in learning how the substances present in a chromosin are put together in a chromosome.     

MULTIPLE OSCILLATORS IN THE SUPRACHIASMATIC NUCLEUS

The suprachiasmatic nucleus (SCN) of the hypothalamus is the site of the pacemaker that controls circadian rhythms of a variety of physiological functions. Data strongly indicate the majority of the SCN neurons express self-sustaining oscillations that can be detected as rhythms in the spontaneous firing of individual neurons. The period of single SCN neurons in a dissociated cell culture is dispersed in a wide range (from 20h to 28h in rats), but that of the locomotor rhythm is close to 24h, suggesting individual oscillators are coupled to generate an averaged circadian period in the nucleus. Electrical coupling via gap junctions, glial regulation, calcium spikes, ephaptic interactions, extracellular ion flux, and diffusible substances have been discussed as possible mechanisms that mediate the interneuronal rhythm synchrony. Recently, GABA (γ-aminobutyric acid), a major neurotransmitter in the SCN, was reported to regulate cellular communication and to synchronize rhythms through GABA_A receptors. At present, subsequent intracellular processes that are able to reset the genetic loop of oscillations are unknown. There may be diverse mechanisms for integrating the multiple circadian oscillators in the SCN. This article reviews the knowledge about the various circadian oscillations intrinsic to the SCN, with particular focus on the intercellular signaling of coupled oscillators. (Chronobiology International, 18(3), 371–387, 2001)     

THE EFFECTS OF ACTINOMYCIN D ON THE ULTRASTRUCTURE OF THE NUCLEUS OF THE AMPHIBIAN EMBRYONIC CELL

Observations have been made of ultrastructural modifications induced in the nuclei of differentiating amphibian embryonic cells cultured in the presence of Actinomycin D. Of particular interest are regions within the nucleus (regions otherwise rather empty) containing loose groupings of uniform threads having a diameter of around 200 A. These threads have been observed in continuous lengths up to 0.5 µ, and appear to be composed of subfilaments. It is suggested, after taking account of some recent work on lampbrush chromosomes, that these threads are lengths of uncoiled chromosome in a condition of heterosynthetic inhibition. It is further suggested that active and inactive portions of the genome may be distinguishable by the facility with which they can be induced to undergo this ultrastructural modification.     

金黄滴虫细胞核微丝系统的初步观察

金黄滴虫细胞核内经常存在着许多直径约为7nm的微丝。这些徽丝大多组合成走向不定的徽丝束,微丝束交织而成遍布核内的网架。核被下面微丝束较多,它们的存在常使核被外凸而成隆脊。核内微丝与核内结构如核仁、染色质等似乎都是相连的。有些微丝横跨核被,一端位于核内,另一端位于核周腔中,并靠近叶绿体。核周腔和内质网腔中也存在着微丝和另一种纤维,印管状纤维。用细胞松弛素B处理后,细胞核、核周腔和内质网腔中的微丝均消失,细胞核的形态也发生变化,似乎微丝网架有支持细胞核的作用。核内微丝可能是在内质网中组装,然后经核周腔进入核内的。     

家鸽圆核和峡核的免疫细胞化学分析

应用组织化学和免疫细胞化学方法发现,位于家鸽间脑的圆核（Ｎ．Ｒｔ）含有大约６０％的ＣｈＡＴ免疫阳性神经元,而中脑峡核大细胞部（Ｉｍｃ）所有细胞呈ＣｈＡＴ免疫阳性反应。     

大白鼠脚内核的传入性联系

众所周知,肉食动物和大白鼠的脚内核,相当于灵长类的内侧苍白球(Nagy et al.1978;Fox and Schmitz 1944);它们的细胞形态、传入及传出均相同。早期以及近年来的一些研究工作者,虽然在研究其他核团的投射时,联系到一些本核团的传入,但是尚缺乏对本核团传人的系统研究。本实验即是应用辣根过氧化物酶的逆行传递法来研究大白鼠脚内核的传入性联系。     

猫丘脑腹后外侧核的超微结构

采用电镜技术观察了猫丘脑腹后外侧核的超微结构。该核内的神经元可分为大小两种类型，大型直径在１５—４０μｍ，小型小于１５μｍ，其胞质内容无明显差别。树突较多见，直径从１—１０μｍ不等。轴突可分为三种类型：含圆形小泡的小终末、终末及扁平小泡的终末。突触类型主要为轴树突触，此外还可见到轴体、轴轴、轴轴树、树树突触以及以树突为中心的突触复合体。在树突之间、树突与胞体之间还存在有非突触的丝状连接。     

THE PERMEABILITY OF THE AMPHIBIAN OOCYTE NUCLEUS, IN SITU

Ultralow temperature radioautography, suitable for the quantitative localization of diffusible solutes, was used to study the permeability of the nuclear envelope in the intact amphibian oocyte Sucrose-³H solutions were injected into mature oocytes, in volumes of 0 016–0 14% of that of the cell, and the subsequent movement of the solute was recorded. The resultant radioautographs show diffusion gradients in the cytoplasm and nucleus, and concentration gradients across the nuclear envelope Analysis of these gradients discloses that the nuclear envelope is as permeable as a comparable structure composed of cytoplasm, and is about 10⁸ times more permeable than the oocyte plasma membrane The diffusion coefficient of sucrose in cytoplasm is 2 x 10^-6 cm²/sec, or about one-third its diffusivity in pure water. This reduction can probably be accounted for by an effective lengthening of the diffusional path because of obstruction by cytoplasmic inclusions. The nuclear: cytoplasmic sucrose concentration ratio at diffusional equilibrium is about 3 05, or 1.6 times as great as expected from the water content of the two compartments This asymmetry is attributed to an unavailability of 36% of the cytoplasmic water as solvent Finally, sucrose entry into oocytes from a bathing solution was monitored by whole cell analysis and radioautography. These and the microinjection results are consistent with a model in which sucrose entry into the cell is entirely limited by the permeability of the plasma membrane. The results are inconsistent with cell models that hypothesize a short-circuit transport route from the extracellular compartment to the nucleus, and with models in which cytoplasmic diffusion is viewed as limiting the rate of solute permeation.     

两栖类峡核的顶盖外投射

用辣根过氧化物酶法研究了中华大蟾蜍峡核的顶盖外投射。结果指出：（１）中脑脚盖前背核、中脑深核和表层峡网核投向双侧峡核,对侧投射经过Ｖｅｌｉ交叉;（２）这些脚盖核投向整个峡核,其间没有区域对应关系,讨论了这些投射的可能功能意义。