RESUMEN
The Y-1 mouse adrenocortical tumor cells secrete into the culture medium some metabolites of pregnenolone. The long term basic steroid secretion was studied for 24 h by high performance liquid chromatography (HPLC). After 6 h incubation, only one chromatographic peak was shown to be quantitatively important. When the cells were incubated with tritium labeled pregnenolone and carrier, the analysis of radioactivity of each HPLC fraction indicated a rapid incorporation of the exogenous precursor and successive secretion/reabsorption kinetics of the metabolites. The final product, accumulated in the medium, was characterized by gas chromatography-mass spectrometry as 11 beta,20 alpha-dihydroxy-4-pregnen-3-one.
Asunto(s)
Glándulas Suprarrenales/metabolismo , Pregnenolona/metabolismo , Animales , Biotransformación , Línea Celular , Cromatografía Líquida de Alta Presión/métodos , Cromatografía de Gases y Espectrometría de Masas/métodos , Cinética , RatonesRESUMEN
In addition to its antiviral effect, interferon, at high concentrations, stimulates steroidogenesis and provokes cell rounding in Y-1 mouse adrenal tumour cells. This stimulation was inhibited by cytochalasin B and colchicine. In contrast, dibutyryl cAMP and cholera toxin, also able to induce steroid production and cell rounding, increased steroid production even in the presence of these cytoskeleton-disrupting agents. The initial trigger for interferon or cholera toxin thus probably involves a distinct receptor organization. However, since both inducers increased cAMP synthesis in this differentiated cell line, the further metabolic steps of ketosteroid production could be the same.
Asunto(s)
Neoplasias de las Glándulas Suprarrenales/metabolismo , Butiratos , Toxina del Cólera/farmacología , Interferón Tipo I/farmacología , Cetosteroides/biosíntesis , Animales , Arginina/análogos & derivados , Arginina/farmacología , Bucladesina/farmacología , Línea Celular , Colchicina/farmacología , Citocalasina B/farmacología , Citoesqueleto/efectos de los fármacos , RatonesRESUMEN
Analysis of the staining of cholera enterotoxin on the surface of cells with specific antibodies against each subunit of cholera enterotoxin, using a fluorescence-activated cell sorter and electron microscopy, showed that not only subunit A but also subunit B penetrates the cell membrane. The detection of subunits inside the cell was facilitated by the use of saponin, an agent that increases membrane permeability.
Asunto(s)
Enterotoxinas/metabolismo , Timo/metabolismo , Animales , Cólera , Histocitoquímica , Ratones , Microscopía Electrónica , Microscopía Fluorescente , Saponinas , Timo/ultraestructuraRESUMEN
Quantitative analysis of the staining of cholera enterotoxin on the surface of cells with specific antibodies against each subunit of cholera toxin, using a Fluorescence-Activated Cell Sorter, showed that not only subunit A but also subunit B penetrates the cell membrane. The detection of each subunit inside the cell was facilitated by the use of saponin, an agent which increases membrane permeability.
Asunto(s)
Membrana Celular/metabolismo , Toxina del Cólera/metabolismo , Animales , Separación Celular , Células Cultivadas , Citometría de Flujo , Ratones , Pinocitosis , Saponinas/farmacología , TimoRESUMEN
Miller's technique (microcentrifuge method) of visualizing transcriptional events at the molecular level is introduced with a review on the work that applied this technique, and followed by presentation of an article describing one such application in which the modes of replication and transcription are electronmicroscopically demonstrated in an adenovirus-infected cell nucleus. Adenovirus is chosen owing to its character of multiplying in a mammalian cell nucleus. Recently, there have been many important discoveries on the modes of DNA replication and RNA transcription through biochemical probes. It is confirmed by Miller's technique that large primary precursor messenger RNA is first transcribed at a late stage in a cell nucleus productively infected with adenovirus. Evidence is shown that a replicating viral DNA molecule can be simultaneously transcribed.
Asunto(s)
Adenoviridae/genética , Adenovirus de los Simios/genética , Centrifugación/métodos , Replicación del ADN , ADN Viral/genética , Transcripción Genética , Animales , Células Cultivadas , Haplorrinos , Riñón , Micromanipulación/métodos , ARN de Transferencia/genéticaRESUMEN
Miller's technique of spreading DNA was applied to monkey cells productively infected with simian adenovirus 7. This permitted the visualization of cellular DNA transcription, both nucleolar and non-nucleolar, and of late transcription and replication of virus. Virus double-stranded DNA, thin fibres with very few nucleosome-like particles, were observed carrying either transcription or replication complexes. In addition, both RNP transcripts and replication forks were found on some virus duplex DNA. Virus single-stranded DNA replicative intermediates were identified on the basis of their increased thickness and contrast which results from the presence of a DNA binding protein.
Asunto(s)
Adenoviridae/metabolismo , Adenovirus de los Simios/metabolismo , Replicación del ADN , ADN Viral/biosíntesis , Transcripción Genética , Animales , Línea Celular , Cercopithecus , Haplorrinos , Riñón , Microscopía ElectrónicaRESUMEN
A bacteriocin produced by strain 100052 of Shigella sonnei (shigellacin 52) was purified about 80-fold from a mitomycin C-induced culture supernatant. The purified preparation gave a single band on sodium dodecyl sulfate-gel electrophoresis with an approximate molecular weight of 10,000. The negatively stained electron micrograph of the purified bacteriocin preparation revealed the existence of three different particles. They were a small cylindrical tube (4.2 by 6.0 nm), a ring-shaped particle and a filamentous structure. The molecular weight calculated from the shape of the small tube was approximately 50,000. The latter two particles appeared to be constructed from subunits which were morphologically similar to the cylindrical tube. These results suggested that the morphological subunit of shigellacin 52 consisted of five chemical subunits with molecular weights of 10,000 each, and it assembled into two types of polymers, a ring-shaped particle and a filamentous structure, which seemed to be the main components of the purified shigellacin 52 preparation.