一种新型吡唑酰胺类衍生物对小菜蛾肌细胞超微结构的影响

采用透射电子显微镜技术,研究了新型吡唑酰胺类衍生物WJ-H7对小菜蛾(Plutella xylostella)体壁肌细胞超微结构的影响。电镜观察发现,化合物WJ-H7对小菜蛾幼虫体壁肌细胞具有明显毒性;中毒幼虫肌细胞,特别是质膜和内膜系统以及肌原纤维发生明显病变,表现为核膜部分消解,细胞核固缩或核质溶出,核与肌原纤维的间距增大,肌原纤维间间距增大,肌丝部分消失,线粒体消失;结果表明,肌细胞可能是化合物WJ-H7的一个作用部位。     

Coxsackie B-3病毒对BALB/C小鼠心肌超微结构的影响

ＢＡＬＢＣ小鼠腹腔注射柯萨奇Ｂ—３病毒后，第三天心肌呈现轻度弥散性病变，大多数细胞结构正常，少数细胞发生病变，心肌闰盘局部扩张，部分线粒体的嵴分解，基质内有少量细小的絮状物质，Ｚ线扭曲．第五天病灶增大，少数心肌细胞结构正常，大部分心肌细胞发生病变．闰盘双膜间隙加宽区域增多，线粒体中絮状高电子密度物质增加，肌原纤维出现肌节病变．至第七天，病灶进一步扩大，整个线粒体遍布钙化的絮状物，肌丝大面积溶解，且细胞间质明显增加．     

脉红螺（Rapanavenosa）心肌纤维的形态学研究

作者从１９９０年３月至１９９３年６月，通过光镜和电镜，观察了脉红螺心肌纤维的形态结构，并与其它软体动物和脊椎动物进行了比较。脉红螺心肌纤维细长，无肌节和周期性横纹，排列不规则，纵横交错，在两条心肌纤维连接处有类似闰盘的结构。肌原纤维由粗丝和细丝构成，两者平行相间排列，对位不整齐．线粒体发达，成簇分布在肌膜下或肌原纤维间，其间有脂褐素颗粒存在，肌质网不甚发达，成泡状结构，分布在肌膜下．大量糖元颗粒存在于线粒体周围或肌原纤维之间。脉红螺心肌纤维的肌微丝直径处于河蚌和金乌贼的之间。     

螯虾腹屈肌快,慢肌肌原纤维的蛋白质差异

测定螯虾腹屈肌的快、慢肌肌原纤维的蛋白质组成，结果表明，快、慢肌的副肌球蛋白、肌球蛋白轻链和肌鲈蛋白有较大差异。结果提示甲壳动物快、慢肌原纤维蛋白质的差异是造成、慢肌形态与功能差异的原因之一。     

Leigh综合征肌肉超微结构观察

目的：研究Leigh综合征肌肉的超微结构。方法：取1例Leigh综合征患儿腓肠肌组织，经常规样品制备后进行电镜观察。结果：部分肌纤维出现下列超微结构改变：(1)局灶性肌原纤维、线粒体和肌浆网消失。(2)肌膜下柱状同心圆板层体聚集。(3)细胞核两端线粒体聚集，线粒体内晶格状包涵体常见。结论：本病例出现的形态学改变提示Leigh综合征不仅是一种中枢神经系统疾病，而且是一种线粒体肌病。     

贵州小型猪心肌细胞超微结构的观察

观察贵州小型猪心肌细胞的形态和结构。方法应用透射电镜进行观察。结果贵州小型猪心肌细胞的肌丝有规律排列形成的周期性横纹明显可见,可分辨出Z线I、带、A带、H带和M线;在肌丝周围有丰富的线粒体;肌浆网不丰富,横小管十分细小,未见二联体;在Z线处,可见心肌细胞之间含有3种连接方式的特有连接结构——润盘。结论贵州小型猪心肌细胞的超微结构与人类极为相似,但也有其自身的特点。     

中国对虾PENAEUS CHINENSIS（O′SBECK）肌肉系统的研究…

中国对虾肌肉含有快肌Ｉ、快肌Ⅱ和慢肌等三类型肌纤维，其主要区别之处有：肌节长度、粗／细肌丝排列与比率、线粒体和二联体含量多寡以及ＡＴＰ酶活性等特征，文中已作详细描述。     

脉红螺心肌纤维的形态学研究

作者从１９９０年３月至１９９３年６月，通过光镜和电镜，观察了脉红螺心肌纤维的形态结构，并与其它软体动物和脊椎动物进行了比较。脉红螺心肌纤维细长，无肌节和周期性横纹，排列不规则，纵横交错，在两条心肌纤维连接处有类似闰盘的结构。肌原纤维由粗丝和细丝构成，两者平行相间排列，对位不整齐。线粒体发达，成簇分布在肌膜下或肌原纤维间，其间有脂褐素颗粒存在，肌质网不甚发达，成泡状结构，分布在肌膜下。大量糖元颗粒存     

三唑磷蓄积对日本(虫寻)4种组织超微结构的影响

首先根据急性毒性试验确定了三唑磷对日本?的安全浓度为 0.27 mg/L,然后采用透射电镜技术研究了该浓度下三唑磷蓄积对日本(虫寻)4种组织细胞(肌肉、鳃、肝胰脏和心脏)超微结构的影响.结果表明 :三唑磷对肌肉损伤的主要靶部位是线粒体和肌原纤维,表现为线粒体内嵴肿胀、空泡化,线粒体溶解,肌原纤维断裂,明暗带不清楚;鳃细胞的损害表现为鳃丝水肿,细胞器溶解,角质层变薄,线粒体、内质网的肿胀、解体,细胞核不规则,核膜肿胀突起;肝胰脏细胞的主要损害特征为肝管微绒毛减少、线粒体水肿解体、内质网扩张、脂肪滴增加;心脏细胞的毒理变化为线粒体内嵴肿胀、瓦解,肌原纤维不规则,细胞核膜肿胀、突起,内质网溶解.鳃和肝胰脏中的变化要比肌肉和心脏明显.     

三唑磷蓄积对日本是4种组织超微结构的影响

首先根据急性毒性试验确定了三唑磷对日本?的安全浓度为 0.27 mg/L,然后采用透射电镜技术研究了该浓度下三唑磷蓄积对日本(虫寻)4种组织细胞(肌肉、鳃、肝胰脏和心脏)超微结构的影响.结果表明 三唑磷对肌肉损伤的主要靶部位是线粒体和肌原纤维,表现为线粒体内嵴肿胀、空泡化,线粒体溶解,肌原纤维断裂,明暗带不清楚;鳃细胞的损害表现为鳃丝水肿,细胞器溶解,角质层变薄,线粒体、内质网的肿胀、解体,细胞核不规则,核膜肿胀突起;肝胰脏细胞的主要损害特征为肝管微绒毛减少、线粒体水肿解体、内质网扩张、脂肪滴增加;心脏细胞的毒理变化为线粒体内嵴肿胀、瓦解,肌原纤维不规则,细胞核膜肿胀、突起,内质网溶解.鳃和肝胰脏中的变化要比肌肉和心脏明显.     

Influence of Manufacturing Process of Warp-knitted Vascular Prosthesis on the Wall Homogeneity

This paper reports the evolution of textile structure and mechanical properties of vascular prosthesis in the level of the whole prosthesis and the constituent filaments with respect to the manufacturing process. The tubular wall of the prosthesis is divided circumferentially into three zones; basic line (BL), remeshing line ( RL) and guide line ( GL). Some heterogeneity has been observed on the tubular wall in terms of stitch structure of the prosthesis and linear density of the constituent filaments. The breaking position of the prosthesis under circumferential tensile localizes preferentially in remeshing line that is the weakest zone by warp knitting with double needle bed. Furthermore, the statistical differences of the mechanical properties of the filaments of zone RL, GL and BL have been confirmed too. It is predictable that the deterioration of prosthesis, under physiological loads (periodical pulse blood pressure etc.), could happen firstly in the weaker zone in vivo.     

Cross-bridge interaction with oppositely polarized actin filaments in double-overlap zones of insect flight muscle

An unresolved problem in understanding muscular contraction is why the internal resistance to sarcomere shortening increases progressively during contraction. We have addressed this problem here by investigating the movement of detached acting filaments in the sarcomeres of insect flight muscle. The final position of the detached actin filaments shows that they were able to slide freely into regions where they have the wrong polarity to interact actively with myosin (double-overlap zones) but where they prevent the exertion of force by cross-bridges between myosin and the correctly polarized acting filaments. These observations indicate that the isometric tension at all sarcomere lengths is directly proportional to the number of cross-bridges in the region of single-overlap of correctly polarized actin and myosin filaments. The decrease in tension as sarcomeres shorten is thus the result of the decrease in the number of effective cross-bridges as actin filaments slide into regions where they are of the wrong polarity to form cross-bridges, and where they inhibit the existing cross-bridges.     

Magnetic support of the optical emission line filaments in NGC 1275

The giant elliptical galaxy NGC 1275, at the centre of the Perseus cluster, is surrounded by a well-known giant nebulosity of emission-line filaments, which are plausibly in excess of 10(8) years old. The filaments are dragged out from the centre of the galaxy by radio-emitting 'bubbles' rising buoyantly in the hot intracluster gas, before later falling back. They act as markers of the feedback process by which energy is transferred from the central massive black hole to the surrounding gas. The mechanism by which the filaments are stabilized against tidal shear and dissipation into the surrounding extremely hot (4 x 10(7) K) gas has been unclear. Here we report observations that resolve thread-like structures in the filaments. Some threads extend over 6 kpc, yet are only 70 pc wide. We conclude that magnetic fields in the threads, in pressure balance with the surrounding gas, stabilize the filaments, so allowing a large mass of cold gas to accumulate and delay star formation.     

锦鲤和胡子鲶鳃丝及鳃小片亚微结构特征扫描电镜比较研究

应用扫描电镜对锦鲤和胡子鲶鳃丝及鳃小片亚微形态结构进行详细的观察比较研究,结果表明：锦鲤和胡子鲶的鳃丝及鳃小片结构具有很大的差异．锦鲤鳃丝上皮细胞表面有环形隆嵴、连续不断的线纹、短纹和点纹,而鳃小片上皮细胞表面凹凸不平,不具有沟、回等结构．胡子鲶鳃丝上皮细胞表面也生有环形隆嵴、短纹和点纹,而鳃小片上皮细胞表面没有隆嵴和刻纹．这些形态结构特征与鳃功能机理密切相关．     

气体成分对介质阻挡放电中超四边形斑图的影响

采用介质阻挡放电装置,研究了1.01×105Pa下空气和氩气的混合气体中气体成分对超四边形斑图的影响.实验发现,随着空气体积分数的增大,产生超四边形斑图所需要的驱动电压也随之升高,同时,超四边形斑图越来越不稳定,放电丝直径逐渐变小,当空气体积分数大于4%时放电丝个数由每行6个增加到7个.     

视黄酸对胃癌细胞NM—IF系统变化的影响

选择性抽提整装扫描与透射电镜观察显示,人胃腺癌ＭＧｃ８０－３细胞核骨架纤维和中间纤维数量较少、分布不均匀,核纤层为厚薄不一结构,与两类纤维联系不密切．经１０－６ｍｏｌ／ＬＲＡ处理后,细胞核骨架纤维和中间纤维数量增多、结构层次丰富,分布均匀并相互交织成规则网络,两类纤维通过薄层均一的核纤层发生密切联系,形成贯穿整个细胞核质区域的完整体系．表明经ＲＡ诱导处理后ＭＧｃ８０－３细胞的核骨架－中间纤维系统产生了与正常细胞相似的恢复性改变．这种变化是癌细胞恶性表型逆转的重要形态特征和功能表现．     

织物漫反射光分布曲线的模拟计算

利用较为接近实际的织物模型,在余弦漫射和均匀漫射假设下对织物的漫反射光分布曲线进行了模拟计算.结合织物的结构因素进行了分析,并对织物的漫反射性质以及反光分布曲线中镜面反射成分和漫反射成分的划分方法进行了讨论.     

Disruption of the actin cytoskeleton in yeast capping protein mutants

Capping protein controls the addition of actin subunits to the barbed end of actin filaments and nucleates actin polymerization in vitro. Capping protein has been identified in all eukaryotic cells examined so far; it is a heterodimer with subunits of relative molecular masses 32,000-36,000 (alpha-subunit) and 28,000-32,000 (beta-subunit). In skeletal muscle, capping protein (CapZ) probably binds the barbed ends of actin filaments at the Z line. The in vivo role of this protein in non-muscle cells is not known. We report here the characterization of CAP2, the single gene encoding the beta-subunit of capping protein in Saccharomyces cerevisiae. Yeast cells in which the CAP2 gene was disrupted by an insertion or a deletion had an abnormal actin distribution, including the loss of actin cables. The mutant cells were round and large, with a heterogeneous size distribution, and, although viable, grew more slowly than congenic wild-type cells. Chitin, a cell wall component restricted to the mother-bud junction in wild-type budding yeast, was found on the entire mother cell surface in the mutants. The phenotype of CAP2 disruption resembled that of temperature-sensitive mutations in the yeast actin gene ACT1, indicating that capping protein regulates actin-filament distribution in vivo.     

Dependence of the mechanical properties of actin/alpha-actinin gels on deformation rate

The cortical cytoplasm, including the cleavage furrow, is largely composed of a network of actin filaments that is rigid even as it is extensively deformed during cytokinesis. Here we address the question of how actin-filament networks such as those in the cortex can be simultaneously rigid (solid-like) and fluid-like. Conventional explanations are that actin filaments rearrange by some combination of depolymerization and repolymerization; fragmentation and annealing of filaments; and inactivation and reestablishment of crosslinks between filaments. We describe the mechanical properties of a model system consisting of actin filaments and Acanthamoeba alpha-actinin, one of several actin crosslinking proteins found in amoeba and other cells. The results suggest another molecular mechanism that may account for the paradoxical mechanical properties of the cortex. When deformed rapidly, these mixtures are 40 times more rigid than actin filaments without alpha-actinin, but when deformed slowly these mixtures were indistinguishable from filaments alone. These time-dependent mechanical properties can be explained by multiple, rapidly rearranging alpha-actinin crosslinks between the actin filaments, a mechanism proposed by Frey-Wyssling to account for the behaviour of cytoplasm long before the discovery of cytoplasmic actin or alpha-actinin. If other actin-filament crosslinking proteins behave like Acanthamoeba alpha-actinin, this mechanism may explain how the cortex recoils elastically from small rapid insults but deforms extensively when minute forces are applied over long periods of time.     

Intensification of the 5.9-nm actin layer line in contracting muscle

According to the cross-bridge model of muscle contraction, an interaction of myosin heads with interdigitating actin filaments produces tension. Although X-ray equatorial diffraction patterns of active (contracting) muscle show that the heads are in the vicinity of the actin filaments, structural proof of actual attachment of heads to actin during contraction has been elusive. We show here that during contraction of frog skeletal muscle, the 5.9-nm layer line arising from the genetic helix of actin is intensified by as much as 56% of the change which occurs when muscle enters rigor, using a two-dimensional X-ray detector. This provides strong structural evidence that myosin heads do in fact attach during contraction.