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At least 307 records · Page 17Linked to original sources
PubMed1982

Nucleic acid synthesis in proliferating peroxisomes of rat liver as revealed by electron microscopical radioautography.

Thirty albino rats were fed with a diet containing 1, 2 or 4% di-(2-ethylhexyl)-phthalate (DEHP), a peroxisome-proliferating agent. Others were fed with normal diet as controls. Both groups were sacrificed at varying intervals from 3 days to 4 weeks. The livers were either removed and fixed in glutaraldehyde and osmium tetroxide or fixed in glutaraldehyde, incubated in a diaminobenzidine (DAB) medium, postfixed, embedded in Epon, and sectioned. Other tissues were incubated in Eagle's MEM containing either [P3H-thymidine or [3H]uridine, fixed, embedded in Epon, sectioned, and radioautographed. Specimens were observed in a Hitachi H-700 electron microscope. The number of peroxisomes showing DAB reactivity increased in DEHP-fed animals as compared with normal controls. In radioautograms of normal rats labelled with [3H]thymidine, no silver grains were observed, whereas grains were observed overt some nuclei, mitochondria and peroxisomes of DEHP-fed animals. In contrast, radioautograms of tissue labelled with [3H]uridine revealed a few grains in nuclei and mitochondria or endoplasmic reticulum of normal rats, although grains appeared in nuclei, mitochondria, endoplasmic reticulum and peroxisomes of DEHP-fed animals more frequently. From these results, it is concluded that [3H]thymidine and [3H]uridine were incorporated in the proliferating peroxisomes, suggesting that nucleic acid synthesis had taken place.

Animals↗
PubMed1979

Light and electron microscopic radioautography of rat stomach G-cells labeled with 3H-amino acids.

This paper reports light and electron microscope radioautographic studies of the sites of gastrin synthesis and the paths of intracellular migration of secretory granules in G-cells of rat glandular stomach incubated in vitro with 3H-glutamic acid and/or 3H-glycine at pH 8.2 or 2.5. Although the ultrastructural preservation of tissues maintained in pH 2.5 medium deteriorated within 30 minutes after beginning incubation, morphological observation was possible at least 60 minutes in the pH 8.2 medium. At 5 minutes, silver grains were few, and located chiefly over granular endoplasmic reticulum. After 30 minutes of labeling, silver grains were more numerous and found over the cytoplasm rich in secretory granules and over the nucleus. After incubation for 60 minutes, the distribution of silver grains was the same as at 30 minutes incubation but the labeling was heavier. Secretory granules of different sizes and electron densities were not differentially labeled. The following conclusions are drawn: (1) glutamic acid and/or glycine are incorporated in G-cells, synthesized into proteins and/or polypeptides in the rough surfaced endoplasmic reticulum and formed into secretory granules probably in the Golgi area: (2) the secretory granules thus formed migrate from the Golgi zone to the peripheral cytoplasm and are stored there; and (3) the kinetics of secretion in G-cells are fairly speedy under certain conditions.

Animals↗
PubMed1977

Sites of sulfatation in the chondrocytes of the articular cartilage of the rabbit. A study by quantitative radioautography of high resolution.

35S sulfate uptake by the articular cartilage chondrocytes, from biopsies of rabbit, have been studied by high resolution autoradiography. The Golgi apparatus, rough endoplasmic reticulum, cytosol, cytoplasmic membrane and extracellular space were considered as cell compartments in the quantitative analysis of the autoradiograms. The results obtained show: 1) a high activity of radiosotope incorporation in the Golgi apparatus; 2) a fast rhythm of transfer of the substances labelled in the Golgi apparatus to the cell membrane; 3) significant labelling of the rough endoplasmic reticulum, throughout the experiment. It is concluded: 1) The grains observed in the rough endoplasmic reticulum show a significant radioisotope uptake on this level, and this evidence some sulfotransferase activity. 2) The high 35S sulfate uptake level which is observed in the Golgi apparatus demonstrates that the highest sulfotransferase enzyme activity is located in this cell area, thus showing that the "early" sulfation that began in the rough endoplasmic reticulum was completed by a "late" sulfation in the Golgi apparatus. It is here that complete chondromucoprotein building takes place before being excreted. 3) The high transfer level of the labelled substances from the Golgi apparatus shows that the sulfated product secretion for building the cartilage matrix takes place rapidly since a great label increase can be already observed at the beginning of the chase period in the outer surrounding area of the chondrocyte membrane.

Animals↗