Ultrastructural features of erythropoiesis disorder in Rauscher virus leukemia

The population of leukemic cells (beginning from the precursor cells) has been identified by electron-microscopy methods. Ultrastructural changes typical of the erythropoiesis alteration are determined. Peculiarities in the formation of a leukemic cells population in different hemopoietic organs and changes in erythroid islands (the main morphofunctional unit of erythropoiesis) are revealed. Data obtained show the significant disturbances in differentiation of erythroid cells in the virus leukoses and are very important form the further study of the leukemogenesis mechanisms.     

Abnormal formation of the glucan network from regenerating protoplasts in Schizosaccharomyces pombe cps8 actin point mutant

To study the close relationship between the actin cytoskeleton and cell wall formation, the process of cell wall formation in reverting protoplasts of the fission yeast, Schizosaccharomyces pombe, cps8 actin point mutant was investigated by ultra-high-resolution low-voltage scanning electron microscopy (UHR-LVSEM) and transmission electron microscopy (TEM). The protoplast of the cps8 mutant began to form a glucan network in a unipolar manner and to secrete alpha-galactomannan. The site of cell wall formation grew in a cylindrical shape in the wild-type protoplast. The alpha-galactomannan did not fill in the intrafibrillar spaces completely, however, and the fibrils were exposed on the cell surface. UHR-LVSEM images indicated that the glucan fibrils were thin and rope-shaped, forming a looser network than the wild-type. TEM images indicated the finest fibrils were approximately 1.5 nm in diameter, the same diameter as the wild-type. These results suggest that the cps8 mutant was insufficient in developing cross-linkage with the glucan fibrils up to the wide ribbon shape as found in the wild-type [Osumi M et al. (1989) J. Electron Microsc. 38: 457-468; Osumi M (1998) Micron 29: 207-233]. These findings appear to indicate that the actin cytoskeleton controls formation of the glucan network and secretion of beta-1,6-glucan, and confirm the close relationship of the actin cytoskeleton and glucan formation.     

Ultrastructure and behavior of actin cytoskeleton during cell wall formation in the fission yeast Schizosaccharomyces pombe

Fluorescence microscopy has shown that F-actin of the fission yeast Schizosaccharomyces pombe forms patch, cable and ring structures. To study the relationship between cell wall formation and the actin cytoskeleton, the process of cell wall regeneration from the protoplast was investigated by transmission electron microscopy (TEM), immunoelectron microscopy (IEM) and three-dimensional reconstruction analysis. During cell wall regeneration from the protoplast, localization of F-actin patches was similar to that of the newly synthesized cell wall materials, as shown by confocal laser scanning microscopy (CLSM). In serial sectioned TEM images, filasomes were spherical, 100-300 nm in diameter and consisted of a single microvesicle (35-70 nm diameter) surrounded by fine filaments. Filasomes were adjacent to the newly formed glucan fibrils in single, cluster or rosary forms. By IEM analysis, we found that colloidal gold particles indicating actin molecules were present in the filamentous area of filasomes. Three-dimensional reconstruction images of serial sections clarified that the distribution of filasomes corresponded to the distribution of F-actin patches revealed by CLSM. Thus, a filasome is one of the F-actin patch structures appearing in the cytoplasm at the site of the initial formation of the cell wall and it may play an important role in this action.     

大鼠失血性休克所致肠道菌移位的超微形态观察

严重创伤、烧伤、休克、肝切除、胰腺炎、应用免疫抑制剂等多种因素均可引发肠源性感染 ,而肠道菌移位的机制至今尚未完全清楚 ,本实验利用大鼠失血性休克模型 ,观察肠道中细菌移位的过程 ,为探讨肠道菌的移位机制提供形态学基础。材料与方法清洁级雄性Ｓ .Ｄ .大鼠 ,体重 32 9.6± 36ｇ ,参照Ｂａｋｅｒ的方法复制失血性休克 ,通过放出和回输血液使大鼠血压保持在 30ｍｍＨｇ ,持续 70ｍｉｎ ,以回输所有放出血液的方法使动物复苏。在复苏后 0、2、6、1 2、2 4和 48ｈ各处死 1 0只动物 ,对照组不放出和回输血液 ,于插管 70ｍｉｎ后处死 ,分…     

Ultrastructural basis for the transition of cell death mode from apoptosis to necrosis in menadione-treated osteosarcoma 143B cells

Time-dependent ultrastructural changes of menadione-treated human osteosarcoma 143B cells were correlated with those in their stainability to Annexin V and propidium iodide (PI). Populations of both apoptotic (Annexin V(+)/PI(-)) and necrotic (Annexin V(+)/PI(+)) cells, judged by flow cytometry, began to increase at 2 h after menadione treatment. The former reached a maximum at 6 h followed by abrupt decreases thereafter, while the latter continued to increase. Electron microscopically, cells obtained at 6 h after the menadione treatment consisted of mixed populations of cells with typical apoptotic features and those with a mixture of apoptotic and necrotic features, while cells obtained at 8-24 h consisted exclusively of cells with a mixture of apoptotic and necrotic features. Thus, necrotic cells, as judged by flow cytometry, were in a transitional state of cell death mode from apoptosis to necrosis and are thus designated as 'intermediate cells'. Lack of apoptotic bodies, judged by flow cytometric analysis on sub-G1 nuclei and by electron microscopy in menadione-treated cells, suggested that the transition of cell death mode from apoptosis to necrosis occurred before the apoptotic processes were completed. Effects of N-acetylcysteine and Z-VAD-fmk on menadione-induced ultrastructural changes were also studied.     

Ultrastructural and functional changes of the proximal tubular epithelial cells in the renal cortex from spontaneously diabetic KKAy mice.

To investigate the morphological and functional changes of epithelial cells of proximal tubules in the early stage of diabetic nephropathy, we examined the ultrastructural changes of proximal convoluted tubular cells in spontaneously diabetic KKAy mice. KKAy mice already showed significant elevation of urinary albumin excretion at 16 weeks of age. Examination revealed that lysosomes were increased in number and conspicuous in the epithelial cells of the proximal convoluted tubules from KKAy mice at 40 weeks of age when compared to control C57BL mice. Furthermore, endogenous IgG was detected in the lysosomes of proximal tubular cells from KKAy mice. These findings suggested that reabsorption activity was elevated in the proximal tubules of KKAy mice at 40 weeks of age.     

扇贝多肽减轻中波紫外线诱导人真皮成纤维细胞损伤的超微结构研究

目的：观察扇贝多肽(polypeptide from Chlamys farreri,PCF)对中波紫外线(ultraviolet B,UVB)辐射损伤体外培养的人真皮成纤维细胞超微结构的影响。方法：建立单次UVB辐射损伤体外培养的人真皮成纤维细胞的病理模型,应用透射电镜观察细胞超微结构的变化。结果：模型组成纤维细胞超微结构在2h后即出现变化．包括胞内空泡形成、线粒体嵴断裂、基质空泡化、粗面内质网扩张、核异染色质浓缩及边集,呈现早期细胞凋亡改变。而用0．25％～l％的PCF预处理细胞30min,可减轻成纤维细胞受损的程度,且呈量效关系。结论：扇贝多肽可有效地保护人真皮成纤维细胞对抗UVB的辐射损伤。     

Ultrastructural transformation of gastric parietal cells reverting from the active to the resting state of acid secretion revealed in isolated rat gastric mucosa model processed by high-pressure freezing

To elucidate a functional transformation of gastric parietal cells, we have newly developed an isolated rat gastric mucosa model whose parietal cells exhibited a reverting process from the active to the resting state of acid secretion. Briefly, the parietal cells were treated with cimetidine following prior stimulation of acid secretion in the model, and cryofixed by plunge freezing for light microscopy or high-pressure freezing for electron microscopy. As a result, immunohistochemistry of H(+)/K(+)-ATPase demonstrated a progressive translocation of H(+)/K(+)-ATPase from the apical to the cytoplasmic region. The ultrastructure of parietal cells at 5 min in the reverting phase was quite similar to that of maximally stimulated one. However, the apical microvilli of intracellular canaliculi (IC) changed bulbous by degrees, resulted in complete occlusion of IC at 60 min in the reverting phase. The apical membranes were subsequently internalized into the cytoplasm forming unique penta-laminar membranes. Interestingly, at 90 min in the reverting phase, the penta-laminar membranes formed a number of multilamellar autophagosomes that were intensely labeled for H(+)/K(+)-ATPase. Then, the parietal cells exhibited well-developed Golgi apparatus and lysosomal compartments involving the multilamellar membranes at 105 min, and mostly reverted to their resting conformation at 120 min in the reverting phase. Corresponding to the ultrastructural changes of microvilli, the immunohistochemistry of ezrin showed a dissociation of ezrin from the apical region at 30 min in the reverting phase. The present findings provide new insights into the functional transformation in gastric parietal cells reverting to their resting conformation.