Asunto(s)
Genes env , Proteína gp120 de Envoltorio del VIH/genética , Infecciones por VIH/virología , VIH-1/genética , Fragmentos de Péptidos/genética , Abuso de Sustancias por Vía Intravenosa/complicaciones , Secuencia de Bases , Codón , Grecia/epidemiología , Infecciones por VIH/complicaciones , Infecciones por VIH/epidemiología , VIH-1/clasificación , Humanos , Datos de Secuencia Molecular , Análisis de Secuencia de ADNAsunto(s)
Genes env/genética , Infecciones por VIH/virología , VIH-1/clasificación , VIH-1/aislamiento & purificación , ADN Viral/análisis , Femenino , Grecia/epidemiología , Infecciones por VIH/epidemiología , VIH-1/genética , Análisis Heterodúplex , Homosexualidad Masculina , Humanos , Masculino , Datos de Secuencia Molecular , Filogenia , Reacción en Cadena de la Polimerasa/métodos , Abuso de Sustancias por Vía IntravenosaRESUMEN
The position of centrosomes in endothelial cells (EC) lining the aorta was examined in rabbits at different ages, using en face preparations and immunofluorescent staining with a serum that specifically labels centrioles. The results obtained show that in young rabbits (4 h-6 weeks) the great majority of the EC (61%) had centrosomes on the heart side of the nucleus, whereas in older rabbits (6-156 weeks) only 41% of the EC had centrosomes oriented toward the heart. The results suggest that the orientation of structures normally associated with centrosomes such as the microtubule organizing centers and the Golgi apparatus also change with age. The change in the orientation of centrosomes and associated structures along the longitudinal axis of the cell with age could affect the function and behaviour of EC and their ability to respond to injury.
Asunto(s)
Envejecimiento , Aorta/ultraestructura , Endotelio Vascular/ultraestructura , Orgánulos/ultraestructura , Animales , Polaridad Celular , Centriolos/ultraestructura , Microscopía Fluorescente , ConejosRESUMEN
Fluorescence staining with rhodamine phalloidin specific for F-actin was employed to examine the effects of delta-9-tetrahydrocannabinol (THC) on the distribution of microfilaments in kangaroo rat epithelial cells (PtK2) and rabbit aortic endothelial cells (RAE). PtK2 cells were more sensitive to THC treatment than RAE cells. Exposure of PtK2 cells to 10 microM THC for 2 h disrupted the microfilament network. After treatment with 20 microM THC for 2 h there was a loss of cell-to-cell contact between PtK2 cells, and at 30 microM THC, the cells started to detach from the substratum. In contrast, microfilament disorganization but not cell detachment was observed in RAE cells at THC concentrations of 80 and 100 microM. The possible mechanisms which may account for the changes in the microfilament system are discussed.
Asunto(s)
Citoesqueleto de Actina/efectos de los fármacos , Dronabinol/farmacología , Citoesqueleto de Actina/metabolismo , Actinas/metabolismo , Animales , Células Cultivadas , Endotelio Vascular/efectos de los fármacos , Microscopía Fluorescente , ConejosRESUMEN
Embryonic chick myoblasts possess an extensive network of cytoplasmic microtubules which emanate from a single, perinuclear centrosome containing a microtubule-organizing center (MTOC) and the centrioles. However, after myoblasts fuse into myotubes the centrosome is no longer apparent, and instead long parallel arrays of microtubules are seen. From ultrastructural studies on developing muscle tissue, it has been proposed that centrioles are present in myoblasts but are absent from fused muscle fibers. We have examined this hypothesis in vitro in cultures of chick embryonic muscle cells using sera which specifically label centrioles. Almost all (90-97%) mononucleated cells in these cultures, including myoblasts aligned just prior to fusion, contain a pair of centrioles in close proximity to the nucleus. However, in newly fused multinucleated myotubes as well as in older myotubes that had developed myofibrils, centrioles were rarely found (1-10% positive cells). This study thus provides direct evidence for a loss of centrioles from muscle cells soon after they fuse to form myotubes.