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51.
DOES AUXIN STIMULATE THE ELONGATION OF INTACT PLANT STEMS? 总被引:1,自引:0,他引:1
52.
G. H. Okker-Reitsma I. J. Dziadkowiec C. G. Groot 《In vitro cellular & developmental biology. Plant》1985,21(1):22-25
Summary A short method is described for obtaining a large number of pure vascular smooth muscle cells in culture. The smooth muscle
cells were isolated from human umbilical cord arteries digested twice by an enzyme mixture of collagenase, trypsin, elastase,
and DNAase with addition of α-tosyl-lysyl chloromethane. Primary cell culture and first subculture were not contaminated by
endothelial cells, no Factor VIII being produced. The cultures consisted of smooth muscle cells as appeared from phase contrast
and electron microscopy.
Part of this study was supported by a scholarship from the Dutch Ministry of Education and Science and by the Leyden University
Foundation. 相似文献
53.
Summary The seed coat of soybean (Glycine max L. Merr.) is of physiological interest for synthesis and transport of amino acids and photosynthates during embryo development. A transmission and scanning electron microscopic study to elucidate the structure of the seed coat disclosed a specialized convex area (antipit) appressed to a concave pit in the center of the abaxial surface of the cotyledon. The antipit, which lies on the inner surface of the seed coat at a medial point in the anterior to posterior direction of the seed, contained specialized secretory cells bounded by loose multi-layered cell walls. These cells were rectangular in the developing seed, varied in length, and contributed directly to the convex morphology of the antipit seen on the ventral surface of the seed coat. At maturity these cells assumed the shape of a cone, extending from the aleurone layer in a perpendicular array. The aleurone and cone cells contained numerous Golgi apparatus, laminated rough endoplasmic reticulum, secretory vesicles, and amyloplasts. Secretory vesicles arose directly from tubules of fenestrated trans cisternae of the Golgi apparatus. Mitochondria were clustered with the amyloplasts; stacks of lamellar cisternae of rough endoplasmic reticulum were associated with the nucleus and Golgi apparatus. The cellular contents, the interconnections by plasmodesmata, and the close physical association with the cotyledon suggested that the aleurone and cone cells may be involved in symplastic transport of nutrients for use by the developing embryo.This paper is dedicated to the memory of my parents, Joseph and Theresa Yaklich, who by their example taught me the value of work and the enjoyment of simple things. 相似文献
54.
Dye coupling in the organ of Corti 总被引:3,自引:0,他引:3
Joseph Santos-Sacchi 《Cell and tissue research》1986,245(3):525-529
Summary Dye-coupling in an in vitro preparation of the supporting cells of the guinea-pig organ of Corti was evaluated by use of the fluorescent dyes, Lucifer Yellow, fluorescein and 6 carboxyfluorescein. Despite the presence of good electrical coupling in Hensen cells (coupling ratios >0.6) the spread of Lucifer yellow was inconsistent. Hensen cells are very susceptible to photoinactivation, i.e., cell injury upon illumination of intracellular dye; and this in conjunction with Lucifer Yellow's charge and K+-induced precipitability may account for its variability of spread. Fluorescein and 6 carboxyfluorescein, on the other hand, spread more readily and to a greater extent than Lucifer Yellow, often spreading to cell types other than those of Hensen. Dye spread is rapid, occurring within a few minutes. These results suggest that molecules of metabolic importance also may be shared by the supporting cells of the organ of Corti. 相似文献
55.
A possible phagocytic role for folliculo-stellate cells of anterior pituitary following estrogen withdrawal from primed male rats 总被引:3,自引:0,他引:3
Summary Ultrastructural changes suggesting a phagocytic role for the nongranular folliculo-stellate cells of the anterior pituitary are investigated in estrogen-primed male rats after withdrawal of estrogen. Morphological changes in mammotropes following the removal of a subcutaneous estradiol-containing Silastic implant include the formation of intracellular lipid bodies. These lipid bodies appear to be associated with enhanced estrogen-dependent prolactin secretion in mammotropes. Seven and 24 h after estrogen withdrawal intracellular lipid within mammotropes seems to be released into the intercellular space. Seventy-two h after estrogen withdrawal, lipid droplets are almost entirely cleared from mammotropes while folliculo-stellate cells become packed with lipid globules. Folliculo-stellate cells also undergo dramatic hypertrophy 7 and 24 h after the removal of E2-containing implants. Extensive intercellular junctions including zonulae adhaerentes, desmosomes, and putative gap junctions are formed. Intercellular junctions delineate extravascular channels into which numerous microvilli project. Folliculo-stellate cells appear capable of accumulating many lipid droplets, presumably related to mammotrope metabolism. What appear to be large secondary lysosomes as well as the lipid droplets are observed within folliculostellate cells; lipid, therefore, may be degraded through a lysosomal pathway in folliculo-stellate cells. 相似文献
56.
Characterization of the Blood-Brain Barrier: Protein Composition of the Capillary Endothelial Cell Membrane 总被引:7,自引:4,他引:3
Microvessels were isolated from canine cerebral cortex, and the composition of the endothelial cell membrane was investigated. Endothelial cell membranes were separated from the surrounding basement membrane, solubilized, and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis in 12% gels. Staining with Coomassie Blue revealed a characteristic banding pattern of at least 12 major proteins with apparent molecular weights between 14,000 and 250,000. When proteins from red blood cell ghosts were run simultaneously, no similarities were observed, except for proteins at apparent molecular weights of 43,000 (band 3) and 35,000 (band 4). These two proteins migrated exactly to the positions of the erythrocyte proteins actin and glyceraldehyde 3-phosphate dehydrogenase, respectively. Membrane glycoproteins in gels were also examined by the use of fluorescent lectins. Of the fluorescein isothiocyanate-conjugated (FITC) lectins tested, only FITC-concanavalin A had an affinity for any membrane components. Diazotized [125I]iodosulfanilic acid, a membrane-impermeable reagent, was used to label the internal (lumen) cell surface and the external (antilumen) cell surface. Autoradiography and determination of radioactivity levels in gel slices showed that several proteins were specifically labeled, and that major differences in radioactivity of proteins existed in internal and external labeling experiments. It is concluded that the protein composition of the luminal membrane is different from that of the antiluminal membrane. 相似文献
57.
J. -P. Mourier 《Cell and tissue research》1970,106(2):232-250
Résumé Pendant la période de reproduction, les néphrons du rein de l'Epinoche mâle subissent d'importantes modifications de structure sous l'action des hormones sexuelles. Au niveau de chacun d'entre eux, se différencient deux segments distincts par leur fonction et par leur cytologie. Le segment urinaire, très court, est formé de cellules identiques à celles du jeune, qui remplissent leur fonction d'excrétion. Le segment glandulaire, plus volumineux, subit une transformation muqueuse et élabore une sécrétion qui sert à construire le nid. L'évolution de ces deux segments est étudiée au cours de la période de reproduction et les modifications cytologiques correspondantes sont décrites.
Fine structure of the kidney of the three-spined-stickleback (Gasterosteus aculeate L.) during its mucous transformation
Summary Under the action of sexual hormones the nephrons of the kidney of the male three-spined-stickleback undergo considerable transformations during the breeding period. They differentiate into two segments which differ from one another in function and cytology. The cells of the urinary segment are identical to those of the young fish. They have an excretory function. The glandular segment undergoes a mucous transformation and synthesizes a secretion which is used for the building of the nest. The cytological transformations occuring at the level of these two segments during the breeding period are described with special attention to the mucous cells.相似文献
58.
Retinoic acid (RA) inhibited the in vitro growth of the mouse mast cell tumor line P815 in a dose- and time-dependent manner. The inhibition was accompanied by an increase in the amount of neutral intracellular mucopolysaccharides. Study of cell cycle kinetics showed that exposure to retinoic acid led to a slowing-down of the cell-cycle progression possibly related to a more differentiated cell population disclosed by microscopy with a lower proliferative capacity.
In vivo, delays in both tumor appearance and mouse mortality were observed after injecting RA into mice bearing mastocytomas. These results suggest that RA could be of interest in the treatment of human malignant systemic mastocytosis with proliferation of immature mast cells. 相似文献
59.
Pierre Broquet Hélèna Baubichon-Cortay Pascal George Marie-Jo Peschard Pierre Louisot 《Journal of neurochemistry》1990,54(2):388-394
The tricyclic antidepressant desipramine, when added to culture medium, gave rise in C6 rat glioma cells to a decrease of the activity of the enzyme asialofetuin sialyltransferase. The inhibition was dose and time dependent and was observed in both multiplying cells and cells blocked with 2 mM thymidine or depletion of amino acids. This inhibition was rather specific to the sialyltransferase, as under the conditions where this enzyme was inhibited up to 70%, other enzymes such as dolichol phosphate mannose synthetase, glutamine synthetase, and glycerol phosphate dehydrogenase remained unaffected. This inhibition was not reversed after removal of desipramine from the medium and was not observed by direct addition of desipramine to the sialyltransferase incubation assay. Under the same conditions, W-7 [N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide], which is known to be a potent calmodulin antagonist and an inhibitor of calmodulin-dependent kinases, gave the same concentration-dependent inhibition profile of sialyltransferase as desipramine, whereas H-7 [1-(5-isoquinolinylsulfonyl)-2-methylpiperazine], which is an inhibitor of protein kinase C and cyclic nucleotide-dependent kinases, had no effect. So, it is suggested that desipramine inhibits the sialyltransferase activity in C6 glioma cells through a calmodulin-dependent system. 相似文献
60.
A. C. Passaquin G. Coupin W. A. Schreier P. Poindron R. A. Cole J. de Vellis 《Neurochemical research》1989,14(10):987-993
We investigated the effect of rat interferon-/ (IFN) on the expression of glycerol phosphate dehydrogenase (E.C.1.1.1.8; GPDH), in both C6 cells and pure cultures of oligodendrocytes. IFNs are naturally produced inhibitors of cell growth that can also affect differentiated cell functions. GPDH is a biochemical marker for oligodendrocytes and is known to be developmentally regulated and steroid inducible. GPDH activity is induced by hydrocortisone (HC) 3.5 fold in C6 cells and 5 fold in oligodendrocytes compared to untreated cultures. A pretreatment of these cells with 75 U/ml of rat IFN-/ resulted in an inhibition of the HC induction of GPDH enzymatic activity by 50% and 40% in C6 cells and oligodendrocytes respectively. We also found that IFN impaired the accumulation of GPDH mRNA in both cell types. These results demonstrate that IFNs are capable of modifying the cellular response to hormones in cells of neuroepithelial origin, and suggest the possibility that IFNs may be able to influence the development and function of the brain.Special issue dedicated to Dr. Paola S. Timiras 相似文献