Unne Stenram

Radioautographic RNA and protein labeling and the nucleolar volume in rats following administration of moderate doses of actinomycin D

Abstract Actinomycin D was administered in moderate doses to rats. On the following day the rats were given 3 H-cytidine, 3 H-methionine or 3 H-leucine and sacrificed 3 or 8 hr later. Radioautographs revealed significant decreases in nucleolar RNA and cytoplasmic RNA labeling in many types of cells, e.g. liver cells. Chromatin RNA labeling was undisturbed at 3 hr in liver parenchymal cells and slightly depressed at 8 hr. Nuclear and cytoplasmic protein labeling were unchanged. The liver and the pancreas also showed a decrease in nucleolar size, total nucleolar volume per nucleus, and the ratio of total nucleolar volume per nucleus to nuclear volume. There was no decrease in nuclear volume. The Purkinje cells of the cerebellum showed no change in nucleolar volume. Nerve cells of the central nervous system, unlike those of the peripheral nervous system, showed no decrease in RNA labeling. This might be explained by an inability of actinomycin D to penetrate the bloodbrain barrier.

ELECTRON-MICROSCOPIC STUDY ON LIVER CELLS OF RATS TREATED WITH ACTINOMYCIN D.

SummaryActinomycin D was administered to rats. The animals were also given either cytidine-3H or leucine-3H. Light microscopic radioautography revealed decreased labelling of nucleolar and cytoplasmic RNA and, after high doses, also of chromatin RNA. The protein labelling was not diminished, except perhaps in the nucleoli. Electron-microscopic investigations revealed pronounced changes in the nucleoli, which became compact. Discrete changes were sometimes seen in other parts of the nuclei.

RNA synthesis in the liver of rats treated with 5-fluorouracil

Abstract The incorporation of cytidine- 3 H into rat liver RNA was completely or almost completely inhibited by high doses of 5-fluorouracil. Low doses gave high incorporation into heavy RNA molecules. Less activity was observed in the ribosomal RNA peaks. The results indicate a block in the ribosomal RNA synthesis and support the hypothesis of an accumulation of ribosomal RNA precursors in the nucleoli.

Nephrocalcinosis in Adolescent Sprague-Dawley Rats Fed Casein and Different Salt Mixtures

Young Sprague-Dawley rats fed on semi-purified casein-containing diets developed nephrocalcinosis. The incidence of renal calculi was higher in females than in males and higher for diets containing 10

The effect of 5-fluorouracil on ultrastructure and RNA labelling in the liver of rats following partial hepatectomy

Abstract Male rats were subjected to partial hepatectomy or sham operation. Half of the animals were treated with 5-fluorouracil (FU) prior to and during the period of regeneration. FU permitted the enlargement of liver-cell nucleoli after partial hepatectomy but prevented the appearance of ribosomes in the cytoplasm which became rich in smooth-surfaced endoplasmic reticulum. FU heavily depressed the labelling of 29 and 18S RNA in both hepatectomized and sham-operated animals. In view of previous observations on the effect of FU, the results suggest that the synthesis of pre-ribosomal RNA in the nucleolus proceeds but that its further processing is impaired.

Biological Quality of a Lipoprotein Concentrate from Sunflower Seed

A lipoprotein concentrate was obtained by extraction from sunflower seeds with a water-ethanol-salt solution. This contained about 50% protein and 20% fat. Chemical score was 51, based on analysis of available lysine. For a 3-week period the protein efficiency ratio (PER) was 2.16 and the productive protein value (PPV) 37.6. After addition of lysine the PER increased to about 3.3 and the PPV to about 58. A 90-day toxicological study was carried out on rats fed a diet containing 11 % protein from the lipoprotein concentrate as the sole source of protein. Histological examinations showed a testicular atrophy but otherwise mainly normal conditions. Hematological findings were normal.

Radioautographic, ultrastructural and biochemical studies on the effect of fluorouracil on the RNA synthesis in the liver of rats

SummaryThe effects of fluorouracil and uracil on the ultrastructure and RNA synthesis in the liver of rats have been studied. High doses of uracil, contrary to fluorouracil, had no effects on nucleolar ultrastructure. Fluorouracil, even in low doses, depressed the RNA synthesis as studied after cytidine-3H administration. In the radioautographs the depression was especially seen to affect the cytoplasmic labelling. The biochemical analysis showed signs of a depression of ribosomal RNA synthesis and a block or delay in the maturation of ribosomal RNA. Repeated, high doses of uracil also depressed the RNA synthesis but there did not seem to be any delay in the maturation of ribosomal RNA. The results suggest that fluorouracil may affect the RNA metabolism in the nucleoli.

Cytological, radioautographic and ultrastructural studies on the effect of actinomycin on the liver of renourished rats

SummaryStarved rats were given saline, or Aminosol+glucose intraperitoneally. Half of the latter animals had previously been given actinomycin. Light microscopic radioautography revealed inter alia a decreased RNA and protein labeling in the liver cells of the actinomycin-treated animals. The animals given Aminosol+glucose showed more glycogen and larger amounts of small, smooth-surfaced, endoplasmic vesicles than the other groups. The actinomycin-treated animals had small, compact liver cell nucleoli.

The ultrastructure of the liver in thyroid-fed rats

SummaryRats were fed on a 25% casein diet or the same diet supplemented with desiccated thyroid. The rats were killed after 16 days. Histological sections of the livers of the control rats show coarse, basophilic inclusions and abundance of glycogen in the cytoplasm. In the thyroid-fed rats there is a diffuse, cytoplasmic basophilia with basophilic rods and no or almost no glycogen. Under the electron microscope large areas of glycogen are to be seen in the cytoplasm of the control animals. Mitochondria and rough-surfaced endoplasmic membranes, often in large stacks, are found together. The liver cells of the thyroid-fed rats have little or no glycogen in their cytoplasm. Mitochondria, endoplasmic reticulum, and free ribosomes and polysomes are evenly distributed all over the cytoplasm. There seems to be an increase in the ratio of free to membrane-bound ribosomes and polysomes in the thyroid-fed rats. The possible significance of this observation in relation to RNA synthesis is discussed.

The effects of fluorouracil and actinomycin, single and combined, on the nucleolar ultrastructure of various tissues of the rat.

Summary5-fluorouracil and actinomycin D were given, single and combined, to rats. The nucleolar ultrastructure was examined in liver, pancreas, spleen, kidney cortex, adrenal cortex, in epithelial and smooth muscle cells of the small intestine and in the Purkinje cells of the cerebellum. 5-fluorouracil, given alone, provoked changes in all tissues examined. Actinomycin D, given alone, gave changes in all tissues examined, except the cerebellum. Treatment with fluorouracil prior to actinomycin delayed and modified the effect of the latter drug in all tissues examined.