Striated microfilament bundles attaching to the plasma membrane of cytoplasmic bridges connecting spermatogenic cells in the black snail, Semisulcospira libertina (Mollusca, Mesogastropoda).

Striated microfilament bundles attaching to the plasma membrane of cytoplasmic bridges between spermatogenic cells are described in the black snail, Semisulcospira libertina. The bundles were occasionally observed in bridges connecting spermatogonia, spermatocytes and typical spermatids. Relations between bundles and centrioles could not be detected. The bundle had electron dense cross bands with a periodicity of approximately 200 nm, and attached to the membrane with almost right angle at the cross linker level. Phalloidin cytochemistry revealed that the bundle contained F-actin. In a case, a bundle connected two cytoplasmic bridges.

Approach to ex vivo gene therapy in the treatment of Parkinson's disease.

Approaches to ex vivo gene therapy hold great promise for the treatment of central nervous system disorders where there is currently no care or enough treatment for suffering patients. In this review we have focused on the application of ex vivo gene therapy techniques in Parkinson's disease models, however, the issues and approaches are applicable to other neurodegenerative disorders. In utilizing the ex vivo strategy two considerations are critical for delivery of therapeutic levels of transgene product to the target organ: (i) the vector system and (ii) the cell type for grafting. We describe different vector systems that are currently available and review the various cell types that have been genetically modified and grafting into the striatum of animal models with experimental Parkinson's disease. The strategies for application of gene therapy techniques to the treatment for Parkinson's disease have expanded beyond the classical dopamine replacement toward the use of neurotrophic factors in enhancing cell function or preventing cell death. In addition, we explore the utility of autologus primary skin fibroblasts as alternative cell type for ex vivo gene therapy in the animal model of Parkinson's disease. These results have general implications for the application of ex vivo gene therapy to human neurological diseases and specific implications for Parkinson's disease.

Lipid and fatty acid composition of brush border membrane of rat intestine during starvation.

Alterations in the lipid and fatty acid composition of brush border membrane (BBM) of small intestine were studied in well-fed, starved, and refed rats. The ratios of cholesterol/phospholipid (mol/mol), sphingomyelin/phosphatidylcholine (mol/mol), protein/lipid (w/w), and free fatty acids (w/w) decreased whereas the total phospholipid (w/w) ratio and the double-bond index increased in BBM of the intestine of the starved rat compared to that of the well-fed rat. Analyses of fatty acids showed higher percentage of stearic and arachidonic acids whereas oleic and linoleic acids decreased under starvation. The acyl chain of starved rat BBM was less ordered compared with that of well-fed rat BBM. On refeeding, these changes were restored to well-fed levels. The change in membrane state under starvation is associated with alterations in the lipid and fatty acid composition of BBM and may be responsible for functional changes that occur under nutritional stress.

Decreased densities of intramembranous particles and cytochemically detectable cholesterol in microvilli of starved rat enterocytes.

The densities of intramembranous particles (IMPs) and of sterol complexes induced by treatment of filipin were studied by freeze-fracture replication of intact intestine and/or isolated brush border membranes (BBM) of well-fed and starved rats. The density of IMPs and filipin-sterol complexes (FSCs) decrease considerably during starvation. Biochemical estimations show a decrease in the levels of cholesterol and proteins with respect to phospholipids during starvation which is in agreement with morphological findings. It is suggested that these changes may play a role in regulating membrane fluidity which in turn affects absorption of nutrients through BBM.

Morphological and functional reconsideration of the cytoplasmic bridges which connect male germ cells in snails.

Cytoplasmic bridges (CB) between male germ cells of three fresh-water snails have been examined by electron microscopy, using ultrathin sections and freeze-fracture replicas prepared by ordinary methods and after use of filipin for indicating the presence of membrane cholesterol. The bridge plasma membrane, which was formerly considered to be smooth, was found in these snails to be corrugated. The corrugations were periodically parallel and oriented parallel to the axis of the bridge. The mature bridges showed very low densities of intramembranous particles. No filipin-sterol complexes formed on either the P face or the E face of the bridge plasma membrane, in contrast to plasma membranes elsewhere. The numbers of corrugations in each CB varied with the species. The membrane corrugations overlie bundles of electron dense fibers measuring approximately 30 nm in diameter and 60 nm in center-to-center distance, fitting into convexities of the plasma membrane. The present observations lead us to the necessity of reconsidering the morphological and functional aspects of cytoplasmic bridges in vertebrate as well as in invertebrate germ cells.

A comparative study of the innervation of the choroid plexus in amphibia.

The aminergic and cholinergic innervation of choroid plexuses in three species of amphibia was investigated. Plexuses of the Japanese toad and the bullfrog had poor innervation by adrenergic nerves of sympathetic origin, but in the clawed toad, these plexuses were heavily innervated by adrenergic axons from ganglion cells located in the plexus stroma. Nerve fibers positive for acetylcholinesterase were not found in the plexuses, except for a few fibers with very weak enzyme activity in the clawed toad.

Gap junctions between microvilli of an oocyte and follicle cells in the teleost (Plecoglossus altivelis).

In the teleost, Plecoglossus altivelis, intercellular junctions between microvilli of an oocyte and follicle cells were studied by electron microscopy. Microvilli, which were radiated from an oocyte and arrived at the surface of follicle cells, established contact with follicle cells. These contact areas appeared to be a seven-layered membrane with an overall thickness of about 18 microns by standard fixation. In freeze-fracture replicas, many small aggregates of intramembraneous particles were revealed on the cleavage faces of cytoplasmic membranes of follicle cells. These morphological evidences suggest that in the teleost gap junctions exist between the oocyte and follicle cells, especially on the surface of follicle cells.

Effects of bleomycin on human tongue carcinoma cells as revealed by electron microscopy.

Five patients with tongue carcinoma were treated for 20 days with bleomycin, 15 mg/day, given by one-shot infusion through the superficial temporal artery. Specimens were taken 7, 14, and 20 days after the initial administration for light and electron microscope observations. The first alterations observed were the decrease of electron-dense chromatin clumps in nuclei and, simultaneously, the segregation of nucleolar components, i.e., amorphous protein component segregated from fibrillar and granular components. Subsequently, numerous nuclear bodies appeared in the nucleoplasm, which were observed for the first time in human tongue carcinoma cell nuclei in cases of bleomycin treatment. On the other hand, the cytoplasmic alterations were recognized by the decrease in number of mitochondria and by the appearance of numerous free ribosomes followed by the formation of tonofilaments. The cells enlarged because tonofilaments flocked together to make cancer cell nests, which were gradually together to make cancer cell nests, which were gradually transformed into a keratinic structure showing the so-called cancer pearl pattern. Finally, cancer cells were degenerated nearly to necrosis; there was no evidence of recurrence of cancer. Although the precise mechanism of the effect of bleomycin on nuclear activities of human tongue cancer cells remains unsettled because of the lack of cytochemical analysis, it is believed that bleomycin inhibits DNA synthesis and might also activate ribosomal RNA synthesis.