RNA polymerase in normal avian erythrocytes

Significant RNA polymerase activity was demonstrated in isolated nuclei from mature avian erythrocytes. This activity was shown to have characteristics common to mammalian systems, including sensitivity to α-amanatin. A crude fraction of RNA polymerase was solubilized from these nuclei and characterized to provide further support for the existence of the enzyme in these cells.     

DNA-dependent RNA polymerases from normal mouse liver

Three forms of DNA-dependent RNA polymerase from adult mouse liver are separable by DEAE-Sephadex A-25 chromatography. Two of the forms (IA and IB) are insensitive to inhibition by α-amanitin, while the third form is completely inhibited by 0.3 μg/ml of α-amanitin. The three enzyme forms are compared to the enzymes found in adult rat liver, and to the enzymes found in several other mouse tissues.     

Secretion of RNA by normal and transformed cells

3T3 and SV-40 transformed 3T3 cells in culture secrete RNA into their culture media. This medium RNA is predominantly 5s in size as measured by sucrose gradient and Sephadex gel filtration. Medium RNA is metabolically stable and is heavily methylated in comparison with other major cytoplasmic species. Analysis of the radioactively labeled methylated bases of medium RNA by paper chromatography after formic acid hydrolysis shows a very simple pattern of two peaks in contrast to the very complex patterns seen in rRNA and tRNA. Mycoplasma and mouse leukemia virus contamination have been excluded. The source of this RNA is discussed.     

Alterations in myocardial RNA synthesis and RNA polymerase activity during normal growth

The effect of normal growth (hypertrophy) on myocardial nuclear activity was investigated using male Wistar rats at 21, 50, and 100 days of age. Cardiac mass increased sevenfold during this age range. The concentration of RNA (mg X g-1) was the highest at 21 days and decreased 48% by 50 days of age and 68% after 100 days of development. RNA synthesis, corrected for alterations in the specific activity of the cytoplasmic nucleotide pool, was the highest at 21 days of age. After 50 days of growth, uridine incorporation was decreased fivefold. With continual growth (100 days), RNA synthesis was still reduced compared with the 21-day animals. RNA polymerase activity in myocyte nuclei showed little change in activity from 21 to 100 days of age. However, in the nonmyocyte fraction, RNA polymerase decreased threefold after 50 days of development. Collectively, these data suggest that the large decrease in myocardial RNA synthesis cannot be accounted for by a change in nuclear RNA polymerase activity and that an alteration in chromatin template capacity may be involved during this form of cardiac growth.     

A yeast small nuclear RNA is required for normal processing of pre-ribosomal RNA.

In Saccharomyces cerevisiae, seven snRNAs (snR3, 4, 5, 8, 9, 10 and 17) are retained in the nucleus under conditions in which nucleoplasmic RNAs are lost, and may be nucleolar. All of these snRNAs show properties consistent with hydrogen bonding to pre-ribosomal RNAs; snR5 and 8 with 20S pre-rRNA, snR3, 4, 10 and 17 with 35S pre-rRNA and snR9 with 20-35S RNA. Strains lacking snR10 are impaired in growth and specifically defective in the processing of 35S RNA. Processing is slowed, leading to 35S RNA accumulation and most cleavage occurs, not at the normal sites, but at sites which in wild-type strains are used for subsequent steps in rRNA maturation.     

Uptake of immune RNA by normal mouse spleen cells

Summary Normal mouse spleen cells take up in vitro radioactively labeled immune RNA. RNA taken up is present in nuclei, polysomes, membranes and cytoplasm. About 20–40% of immune RNA is nonspecifically associated with cell surface. 45% of RNA taken up is degraded and reutilized inside the cells within 2 hours.This work was supported by the Polish Academy of Sciences within the project 09.7.4.1.1.     

Studies of interaction of immune RNA with normal spleen cells

Summary Normal mouse spleen cells incorporate in vitro radioactively labeled immune RNA. At saturation, 10⁶ cells incorporate about 6×10¹⁶ daltons of this RNA. Immune RNA is incorporated in two times greater amounts than control RNA. Maximum incorporation is observed in the first few minutes of incubation. Immune RNA incorporated by spleen cells is present both in cytoplasm and nuclei. Protamine sulphate has stimulatory effect on immune RNA incorporation. Actinomycin D does not affect incorporation of immune RNA.This work was supported by the Polish Academy of Sciences within the project 09.7.4.1.1.     

Dynamical structure of transfer RNA studied by normal mode analysis

The internal motion of yeast phenylalanine transfer RNA is studied by normal mode analysis in extended dihedral angle space, in which the flexibility of five-membered ribose rings is treated faithfully by introducing a variable for its pseudo-rotational motion. Analysis of global molecular motions reveals that the molecule is very soft. We show that this softness comes not from the property of the “material” comprising the molecule but from its slender shape. Analysis of thermal distance fluctuations reveals that this molecule can be regarded as consisting dynamically of three blocks. Thermal fluctuations of the mainchain dihedral angles show rigidity of the anticodon region. They also show flexibility of regions around nonstacking bases. Base-stacking interactions cause suppression of the correlated functions of mainchain dihedral angles beyond a ribose ring. We analyze the thermal fluctuation of parameters describing the positions of two adjacent bases. Fluctuations of relative translational parameters in the anticodon and acceptor stem regions are found to be larger than those in other stem regions. The relative translational motions cause the two stem regions to undergo global twisting and bending motions. We show that the role of pseudo-rotational motion of sugars is important in regions around bases which are involved in nonregular interactions. Received: 29 October 1998 / Revised version: 8 February 1999 / Accepted: 11 February 1999     

Antisense RNA p53 inhibits proliferation of normal and transformed cells

p53 anti-sense sequences were introduced into normal NIH3T3 and transformed CMS 4 cells by infection with the recombinant retrovirus carrying a repeat of the 5'-terminal fragment of p53 cDNA. Clones selected for G418 resistance showed a marked inhibition of proliferative capacity and a reduced ability to enter DNA replication after stimulation of quiescent cells with serum. Clones showing moderate inhibition of proliferation were shown to contain truncated anti-sense DNA integrated into the genome. The anti-sense DNA was transcribed and it correlated with the reduction of the p53 protein level in the cell clones studied. We conclude that the appropriate expression of p53 appears to be required for cell proliferation.     

Transfer RNA methylase activity in normal and dystrophic chicken muscle

Adult-dystrophic chicken muscle had 30% higher tRNA methylase activity and 42% higher tRNA methylating capacity than normal-adult chicken muscle. Eighty percent of the tRNA methylase activity of the dystrophic muscle resulted in the synthesis of N²-methylguanine, and 9% in the formation of N²,N²-dimethylguanine. From adult-normal muscle extracts, 33% of the tRNA methylase activity was due to the synthesis of N²-methylguanine, and 45% to the formation of N²,N²-dimethylguanine. Eight other methylated bases accounted for 5–15% of the enzyme activity in both tissues. Dialyzed and nondialyzed adult-normal muscle extracts had equivalent tRNA methylase activity. However, the dialyzed extracts synthesized 22% more N²-methylguanine and 18% less N²,N²-dimethylguanine than the nondialyzed extracts. Dialysis had no effect on the tRNA methylase activity or tRNA methylation pattern produced by adult-dystrophic muscle.     

Cytokinins in transfer RNA of normal and crown-gall tissue of Vinca rosea

cis-Zeatin riboside was identified in transfer-RNA hydrolysates from both normal and crown-gall tissue of Vinca rosea L. The trans-isomer was associated exclusively with the crowngall transfer-RNA. The importance of these observations is discussed in relation to biosynthesis of free cytokinins.Abbreviations GC-MS gas chromatography-mass spectrometry - HPLC high-performance liquid chromatography - TLC thin-layer chromatography - TMSi trimethylsilyl - tRNA transfer RNA - ZR zeatin riboside     

Quantitative aspects of RNA synthesis in normal and lithium-treated embryos ofXenopus laevis

Summary The treatment ofXenopus early embryos with lithium chloride produces exogastruale — embryos which fail to gastrulate normally and in which the rates of cell division are reduced. In the present study estimations of incorporations of (5-³H) uridine and the specific activities of the 5-ribonucleotide precursor pools showed that exogastrulae have higher rates of RNA synthesis per cell than control neurulae. Sub-cellular fractionations showed that a greater proportion of labelled RNA was retained in the nuclei of exogastrulae than of neurulae, while neurulae showed a greater incorporation into polysomes.     

Cellular retinol-binding protein messenger RNA levels in normal and retinoid-deficient rats

A study was conducted to determine the levels of cellular retinol-binding protein (CRBP) mRNA and protein in various tissues of the rat, to explore relationship between CRBP mRNA and protein levels in different tissues, and to examine the effects of changes in retinol nutritional status on the tissue distribution and levels of CRBP mRNA. Previous studies have shown that tissue CRBP protein levels are reduced in totally retinoid-deficient rats, but are otherwise minimally affected by changes in retinoid status. Three groups of male rats were compared: normal controls, retinoid-deficient, and retinol-repleted deficient rats. CRBP mRNA levels were measured by RNase protection assay and CRBP protein levels by radioimmunoassay in seven tissues. High levels of both CRBP mRNA and CRBP protein were found in the proximal epididymis, kidney, and liver; lower levels were seen in lung, testis, spleen, and small intestine. Tissue CRBP mRNA and protein levels were highly correlated (P less than 0.01) with each other. Retinoid deficiency did not alter the levels of CRBP mRNA found in the proximal epididymis, kidney, and liver. In contrast, CRBP mRNA levels in the lung, testis, spleen, and small intestine were reduced substantially in retinoid-deficient rats, to values that were only 23% to 50% of the corresponding values in the tissues of control rats. After oral repletion with retinol (4-18 h earlier), CRBP mRNA levels for these latter four tissues were found to have risen to control or near-control levels. The suggestion is raised that retinol repletion may have directly induced the expression of the CRBP gene in these particular tissues.(ABSTRACT TRUNCATED AT 250 WORDS)