左心房粘液瘤细胞核内张力微丝样的结构

本文首次报导左心房粘液瘤细胞核内发现有直径5—8μm的细丝组成40—80μm的张力微丝样结构[TF]。它分布在瘤细胞核膜尚完整的核内常染色质中,其束排列方向大多和瘤细胞核形方向相一致[图1],瘤细胞核内张力微丝样的结构的形态也很奇特,有者呈丛簇状、扫帚状[图2]或者呈树枝状。在细胞核内TF的数量为1—3束。     

一种新颖SLD减反射区结构的设计

本文用束传播方法研究了具有偏折波导吸收区两段式超辐射发光二极管减反射区结构对激光振荡的抑制作用，提出一种新颖的减反射区结构，这种结构包含一段偏折波导吸收区和一段透明窗口区．本文描述的设计及模拟结果表明：在长度相同的情况下，通过适当选择几何参数，这种结构较单一的一段偏折波导吸收区或透明窗口区，能得到更小的有效反射率，约小一到两个量级．     

用激光在蚕卵上植入染色质引起变异

报道一种移植异种基因的新技术,它是用脉冲微束激光照射到置于显微镜下的活细胞,在细胞上造成微孔损伤,异种基因便被植入。我们在“龙角”蚕卵上植入“黑缟”蚕的某种染色质溶液,经过培育生长,成活率达90%以上,并出现了按预期目的特定变化的变异体。这种变异与用传统的针刺法植入染色质引起的变异完全一致。     

润楠花粉内壁超微结构研究

利用TEM对润楠(MachilusPingii Cheng ex Yang)花粉内壁进行了观察,结果表明:四分体解体后的早期小孢子,胼胝质壁内面有高电子致密度物质组成的球状颗粒沉积(图1)。颗粒粒径约27—35nm,高倍率下可见球状颗粒是由一些更为细小的颗粒集聚而成。有微管同球状颗粒联接。小孢子核贴壁分裂时,花粉内壁迅速增厚(图2),增厚的内壁中有呈辐射排列的微通道形成。通道直径约93nm,具较明显的分层通道壁结构,中央有粒径约40nm的椭园球形电子深染团块,通道壁中层与内侧的胼胝质壁相连,椭园球形电子致密团块呈串珠样排列在通道中央(图3)。这一时期花粉内壁中纤维素微纤丝排     

小鼠肝细胞核凋亡的超微结构观察

用胡萝卜细胞胞浆制备的非细胞体系中 ,加入纯化的小鼠肝细胞核并以细胞色素 C诱导细胞核发生凋亡。在透射电子显微镜和扫描电子显微镜下都观察到凋亡的细胞核呈现典型的凋亡形态学特征 ,例如染色质的凝集及趋边化 ,细胞核表面形成空泡化结构并有大量的凋亡小体结构出现。在此基础上对凋亡小体结构在形成及排出核外的过程进行了详细的观察和分析。     

小鼠肝细胞核调亡的超微结构观察

用胡萝卜细胞胞浆制备的非细胞体系中,加入纯化的小鼠肝细胞核并以细胞色素C诱导细胞核发生调亡。在透射电子显微镜和扫描电子显微镜下都观察到凋亡的细胞核呈现典型的调亡形态学特征,例如染色质的凝集及趋边化,细胞核表面形成空泡化结构并有大量的凋亡小体结构出现。在此基础上对调亡小体结构在形成及排出核外的过程进行了详细的观察和分析。     

一种特殊形态高尔基体内含物的立体观察和研究

本文运用明、暗场互换观察法和样品倾斜法对一种罕见的高尔基体内含物进行了立体结构观察和研究。结果表明,这种高尔基体内含物是由集中于扁囊及囊泡中部的高电子密度物质和其周围的微纤丝样结构组成。在扁囊中,微纤丝样结构以S形结构为中轴呈放射状分布,并与扁囊膜相连。在囊泡中,这些微纤丝样结构结成网状。明暗场互换观察法所得的浮雕象具立体感,能将细胞的膜性结构和纤维状结构显示得更加清晰,但它不能反应出细胞超微结构本身的三维图形,而运用样品倾斜法可以达到这一目的。     

天然纤维素超显微结构的扫描隧道显微镜研究

本文用扫描隧道显微镜（ＳＴＭ）对天然纤维素脱脂棉的超显微结构进行了研究，结果表明用ＳＴＭ可直接观察到脱脂棉的微纤丝和基原纤丝。另外，还直接观察到了脱脂棉中纤维素分子的结果区和非结晶区以及分叉状结构，从而表明棉花纤维素是一种结晶不完全的多聚物。     

杨树花粉内生殖细胞的发育和雄性生殖单位的形成

已经证明,在具双细胞的杨树花粉内,会形成营养核包围生殖细胞结构形式的雄性生殖单位,这是双细胞花粉粒中观察到雄性生殖单位的唯一例证。本工作利用透射电子显微镜,对杨树花粉内雄性生殖单位的形成过程进行了研究,结果发现,这一形成过程经历了三个阶段:(1)生殖细胞贴壁阶段。第一次证实生殖细胞与营养细胞之间的弧形壁具三层结构,中间的纤丝层和两侧的电子透明区,分别与花粉内壁和外壁内层相连。(2)生殖细胞离壁阶段。包围生殖细胞的营养细胞质膜内陷,产生大量液泡。由于液泡具溶酶体的功能,弧形壁内纤丝层溶失。进入了营养细胞内的生殖细胞,周围仍具狭窄的电子透明区,     

四种中药卷柏孢子微形态结构及元素成分分析

用扫描电镜观察了四种中药卷柏小孢子结构 ,并用 X射线微区分析法分析其化学元素成分。小孢子结构因种而异 ,差别较大 ,我们认为小孢子形状和表面纹饰完全可以作为种分类指标之一。小孢子元素含量存在一定差异 ,四种卷柏均含 Si、S、K、Ca元素 ,其中 Si含量最高 ,其次为K、Ca、S,只有中华卷柏特殊 ,它的 Ca含量高于 K含量。四种孢子中中华卷柏和深绿卷柏 Si含量低 ,另外两种含量相当高。Ca和 S含量中华卷柏最高 ,依次为深绿卷柏和卷柏 ,垫状卷柏最低。K含量深绿卷柏最高 ,依次为中华卷柏和卷柏 ,垫状卷柏也最低。中药孢子的药用作用和…     

Comparative structural biology of the genome: nano-scale imaging of single nucleus from different kingdoms reveals the common physicochemical property of chromatin with a 40 nm structural unit

Genome function is closely linked to the higher-order chromatin structures. To reveal a structural basis for the interphase chromatin organization, the 'on-substrate' lysis procedure was applied to nuclei isolated from human HeLa cells, chicken erythrocyte cells and yeast Schizosaccharomyces pombe, which possessed different intrinsic properties of the genomes such as histone composition and inter-nucleosomal distance. The isolated nuclei on a coverslip were successively treated with a detergent and a high-salt solution to extract the nuclear membrane and the nucleoplasm, and therefore, atomic force microscopy (AFM) visualized the structural changes in response to the lysis procedure. After the nucleoplasm was extracted, AFM clarified that chromatin fibers, approximately 40 nm in width, were partially released out of the nuclei and that the other chromatin still remaining in the nuclei was composed of granular structures with diameter of 80-100 nm. Thus, these results suggest that the approximately 40 nm fiber would be a stable structural unit and fold the 80-100 nm granules into a one-step higher unit. A common mechanism could be implied regardless of the intrinsic properties of the eukaryotic genomes.     

银杏小孢子和花粉发育过程的超微结构观察

利用透射电子显微镜技术对银杏(Ginkgo bilobaL.)小孢子发生与花粉发育过程进行超微结构观察.结果表明:(1)在小孢子母细胞减数分裂期间,细胞内发生了“细胞质改组”,主要表现在核糖体数量在历经不同发育时期逐渐减少,质体和线粒体形状与结构发生了规律性变化.第一次减数分裂完成后,两子核间无胼胝质壁沉积,而是被内质...     

近红外反射光谱研究光透明剂渗透特性对胃组织光学透明的影响

为了解高渗溶液渗透特性对生物组织的光学透明进程的影响，探索光透明剂的安全有效浓度，用近红外反射光谱和相干光断层成像(OCT)研究了两种光透明剂丙三醇(甘油)和二甲亚砜(DMSO)以及二者的混合溶液[体积分数为80％的甘油水溶液，50％的DMSO水溶液，50％的甘油 20％的DMSO水溶液(GD1)和50％的甘油 30％的DMSO水溶液(GD2)]对胃黏膜组织的光学透明作用。结果表明，这四种溶液都能显著增强近红外光在胃黏膜组织中的穿透能力，光学透明的能力由低到高依次为体积分数为50％的DMSO，80％的甘油，GD1和GD2。发现生物组织光透明进程的快慢和效果与光透明剂的渗透所导致的组织的失水速率和程度成正比。     

Polarized light scattering of nucleosomes and polynucleosomes--in situ and in vitro studies

Nucleosomes, chromatin and nuclei, extracted from rat hepatocytes, are studied by a new "in house" experimental configuration which measures circular intensity differential scattering (CIDS) and other elements of the polarized light scattering matrix. The Mueller matrix elements, S14 and S34, that are related to the geometric parameters of the superhelical arrangement of polynucleosomes point to the existence of a quaternary structure at low ionic strength for chromatin prepared by the cold-water method, which is lost by shearing, and is not found in the soluble chromatin prepared through the nuclease method. Only salt addition to a final concentration of 5 mM MgCl2, 150 mM NaCl and 10 mM Tris HCl (pH 7) yields a sizeable (S14 + S34) signal in the latter chromatin, which is however still different from the corresponding signal of native nuclei and of "cold-water" chromatin. Comfortingly, the (S14 + S34) signal from isolated nucleosomes is consistently very low (nearly zero) as predicted by multiple dipole simulation within the framework of classical electrodynamics. Results are discussed in terms of the topological constraints present in the native long chromatin fiber, which are lost after limited nuclease digestion and after shearing.     

Systematic design of double-sampling /spl Sigma//spl Delta/ A/D converters with a modified noise transfer function

Double-sampling /spl Sigma//spl Delta/ analog-digital converters (ADCs) are sensitive to path mismatch which causes quantization noise to fold into the signal band. A recent solution for this problem consists of modifying the noise transfer function (NTF) of the modulator such that it has one or several zeros at the Nyquist frequency, next to those in the baseband. In this brief, we present a systematic design strategy for such ADCs. It consists of finding optimal pole positions for the modified NTF. This can be combined with optimizing the zeros as well. Next, we introduce several efficient structures that have enough degrees of freedom to realize the optimized pole positions.     

Solutions to spherical anisotropic antennas

An exact solution is found for the fields of a spherical antenna with an anisotropic surface. The surface, for which a rather simple solution is found, conducts perfectly only along spiral lines which go from pole to pole, and is otherwise nonconducting. The antenna is either excited by fields at a gap around the equator or at low frequencies between adjacent spirals. The method of solution is described, and results of several representative cases are presented.     

Computer simulation of electric field variations due to movements of electric charges

Simulations were carried out for the orbit of electron-induced secondary electrons around a charged microfibril of a sciatic nerve tissue. In order to set the parameters for the simulation, the shape of the microfibril was determined from a transmission electron microscopy image, while the electric potential on the surface of the charged microfibril was evaluated from a reconstructed phase image obtained with electron holography. On the other hand, the passing point and the angle of secondary electrons at the microfibril surface were determined from a reconstructed amplitude image. Eventually, simulation of orbits of secondary electrons was carried out by changing the kinetic energy of the secondary electrons. Under the given conditions, the orbit of secondary electrons with a kinetic energy of 29.6?eV fits the observations. If there are thin layers of electrons, the secondary electrons do not reach the surface but they go over it due to the repulsive Coulomb force resulting in successive revolving motion around the charged microfibril. Furthermore, the electric field variation due to the movement of the electric charges resulting from the specimen drift is also discussed briefly comparing it with electron holography data.     

Nuclear Morphometry in Normal and SV-40 Transformed Human Diploid Fibroblasts

These experiments were designed to compare the densitometric, morphometric, and texture characteristics of intact nuclei from stationary WI-38 human diploid fibroblasts and their stationary SV40-transformed counterparts (2RA cells) by means of automated image analysis and to compare the differences in template activity of the chromatins isolated from the two cell lines. While the frequency distributions of directly measured parameters as area and IOD show a substantial overlap between WI-38 and 2RA cells, average optical density parameter derived as IOD per unit area, yields two distinctly separated distributions, which permit objective identifications of individual SV40 transformed cells. Chromatin of the stationary 2RA cells appears more condensed than that of the confluent WI-38 cells, quite compatible with the decreased template activity of chromatin from transformed cells.