Interphase studies with a simplified method of silver staining of nucleoli.

A simple silver staining method is presented providing a rapid and reliable technique for the selective staining of nuclear structures synthesizing ribosomal RNA (18S and 28S RNA).     

Serum-induced stimulation of snRNA synthesis in mouse 3T3 fibroblasts

Small nuclear RNAs (snRNAs) from quiescent and serum-stimulated 3T3 cultures, labeled with [3H]uridine [( 3H]U), were electrophoresed in polyacrylamide-urea slab gels and revealed by staining with ethidium bromide and by fluorography. Judged by labeling with [3H]U, synthesis of 7S and U1-U6 RNAs was very low or absent in quiescent cultures. The serum-induced transition of 3T3 cells from a resting to a growing state was accompanied by an early, apparently sequential stimulation of snRNA synthesis; stimulated synthesis of 7S, U1, U2, U3, U4 and U6 RNAs coincided in time with serum-induced stimulation of 45S pre-ribosomal RNA (pre-rRNA) and heterogeneous nuclear RNA (hnRNA) synthesis.     

Serum-induced stimulation of snRNA synthesis in mouse 3T3 fibroblasts

Summary Small nuclear RNAs (snRNAs) from quiescent and serum-stimulated 3T3 cultures, labeled with [³H]uridine ([³H]U), were electrophoresed in polyacrylamide-urea slab gels and revealed by staining with ethidium bromide and by fluorography, Judged by labeling with [³H]U, synthesis of 7S and U1-U6 RNAs was very low or absent in quiescent cultures. The serum-induced transition of 3T3 cells from a resting to a growing state was accompanied by an early, apparently sequential stimulation of snRNA synthesis; stimulated synthesis of 7S, U1, U2, U3, U4 and U6 RNAs coincided in time with serum-induced stimulation of 45S pre-ribosomal RNA (pre-rRNA) and heterogeneous nuclear RNA (hnRNA) synthesis.     

Morphology of ribosomal RNA in chicken fibroblasts]

It is shown with the electron microscope that the 28 S RNA component of the ribosomal RNA extracted from Chicken fibroblasts contains secondary structures which are not present in the 18S component.     

Die Isolierung von Ribonukleinsäuren aus menschlichen Knochenmarkzellen

Summary By use of bentonite and sodium dodecylsulfate, which bind or inhibit ribonucleases, pure RNA preparations were obtained from human bone marrow. Phenol extraction at 4 °C yielded cytoplasmic RNA, which could be separated into 3 main peaks by sucrose density gradient centrifugation. Sedimentation coefficients of these peaks were about 30S, 19S, and 5S, respectively. Re-extraction of the phenolic interphase at 65° gave a polydisperse ribonucleic acid, sedimenting between 2S and 19S. This RNA is characterized by template activity and is supposed to be biologically active m-RNA.     

Ultrastructural localization of 5-methylcytosine on DNA and RNA

DNA methylation is the major epigenetic modification and it is involved in the negative regulation of gene expression. Its alteration can lead to neoplastic transformation. Several biomolecular approaches are nowadays used to study this modification on DNA, but also on RNA molecules, which are known to play a role in different biological processes. RNA methylation is one of the most common RNA modifications and 5-methylcytosine presence has recently been suggested in mRNA. However, an analysis of nucleic acid methylation at electron microscope is still lacking. Therefore, we visualized DNA methylation status and RNA methylation sites in the interphase nucleus of HeLa cells and rat hepatocytes by ultrastructural immunocytochemistry and cytochemical staining. This approach represents an efficient alternative to study nucleic acid methylation. In particular, this ultrastructural method makes the visualization of this epigenetic modification on a single RNA molecule possible, thus overcoming the technical limitations for a (pre-)mRNA methylation analysis.     

Distribution of 5 S RNA in the liver of the South American rattlesnake,Crotalus durissus terrificus

Résumé Nous avons étudié la distribution du RNA 5S dans le foie du serpent sud-américainCrotalus durissus terrificus. Nos résultats ont montré que le RNA 5S de ce reptile est associé à la sous-unité ribosomique 60 S. D'autre part, la mobilité electrophorétique de ce RNA de faible poids moléculaire est la même que celle d'Escherichia coli et de pupe d'Apis mellifera L.

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Acknowledgment. We are greatly indebted to Dr.T. Yamane for a supply of 5S RNA ofEscherichia coli.     

Nucleotide sequence of the gene for the mitochondrial 15S ribosomal RNA of yeast

We have determined the nucleotide sequence of a DNA segment carrying the entire 15S ribosomal RNA gene of yeast mitochondrial genome. Many stretches of sequence are present which are homologous to the E. coli 16S ribosomal RNA gene. The gene sequence can be folded into a secondary structure according to the [1] model on bacterial ribosomal RNAs. The structure reveals a striking similarity between the two RNAs despite the large difference in their base compositions. In the middle of the gene, we found a guanine-cytosine rich sequence that is also present in several other regions of the mitochondrial genome.     

Purification of RNA from animal cells using diethyl-pyrocarbonate

Summary Extraction of RNA from animal cells by a method using diethyl-pyrocarbonate yielded 50–60% of the total RNA. RNA purified by a hot phenol-SDS method from adenovirus 2 infected cells showed about 9% homology with adenovirus DNA, and RNA purified by diethyl-pyrocarbonate-SDS showed over 7% hybridization. Profiles of RNA prepared by both methods were identical when studied by polyacrylamide gel electrophoresis.Acknowledgment. This investigation was supported by U.S. Public Health Services research grant No. 5R01-CA10724-03 from the National Cancer Institute.     

Differences in RNA related to the intersterility of wild type strains of Ascobolus immersus (author's transl)]

Fractionation of total RNA prepared from intersterile wild type strains of Ascobolus immersus revealed the existence of differences at the 4S and 5S levels which may be related to the polymorphism of these species or sub-species, bearing the same name and coasting along in nature.     

Nachweis pflanzlicher Ribonukleasen in Polyacrylamid-Gelen nach Disk-Elektrophorese

Summary Detection of ribonucleases in polyacrylamide gels after disc-electrophoresis is possible by incubation of the gels in a solution of low molecular RNA followed by staining with methylene blue. Application of this method to protein extracts of wheat leaves, sugar beet leaves and roots of different bean varieties as well as callus cultures and roots of the same bean variety shows differences in number and position of RNase zones.     

Ribosomal gene numbers in Microseridinae (Compositae: Cichorieae)

Summary 8 species of the subtribe Microseridinae contain between 1100 and 3400 genes for 25 and 18 S ribosomal RNA. The gene numbers seem to evolve by discrete steps. Their trend follows a general reduction in genome size during the evolution of the annual species ofMicroseris, but numbers remain high in one of them and inAgoseris grandiflora. 2 species ofPyrrhopappus differ by a duplication of the ribosomal gene numbers; 5 S ribosomal RNA genes in 4 species are repeated roughly 10,000 times.We thank Miss S. Werner, Miss A. Roth and Miss U. Krehan for help with some of the experiments. This paper is part of a project supported by grant Ba 536/1-5 from the Deutsche Forschungsgemeinschaft.     

Simultaneous syntheses of cytoplasmic and chloroplastic ribosomal RNA during the cell cycle ofDunaliella

Summary Chloroplastic and cytoplasmic ribosomal RNA syntheses were analyzed in synchromous culteres. All 4 rRNA species are simultaneously accumulated during the light period of the cell cycle. Cytoplasmic rRNA synthesis is repressed only during the later part of the S phase.     

Metabolic status of temperature induced swollen conidia ofAspergillus nidulans

Summary There is an active synthesis of DNA, RNA, protein, and carbohydrate in conidia incubated at 48°C. DNA increases more or less 3 times; while RNA, protein and carbohydrate are synthesized at a much faster rate. Conidia do not germinate at this temperature.Acknowledgments. Grateful thanks are due to Professor B. M. Johri for valuable suggestions. R. K. S. acknowledges with thanks a Senior Research Fellowship of the Council of Scientific and Industrial Research, New Delhi.     

Secondary and topographic structure of ribosomal RNA 16S of Escherichia coli

We present a model for the secondary structure of 16S ribosomal RNA from E. coli. This model has been deduced by restricting the total number of theoretical base pairings using the following criteria: (1) susceptibility of residues towards enzymatic probes that are specific for either paired or single stranded regions; (2) reactivity of certain residues to chemical modification; (3) evidence for medium and long range interactions; (4) comparative analysis of ribosomal RNA sequences from other organisms.     

Sexually dimorphic response of the mouse submandibular gland to fasting

Summary The submandibular gland of male mice contained 18% more DNA, 34% more RNA and 63% more protein than that of female mice. After a 48-h fasting, the percent loss of gland weight, protein, RNA and DNA was greater in the female than in the male.This study was supported by the U.S. Public Health Service Research Grant CA 17038. The authors are indebted to Mr I. Borcsanyi for his technical assistance.     

Induction of dolykaryocytes by vesicular stomatitis virus in XC rat cells]

V.S.V. induced polycaryocytes in rat embryonic fibroblasts, transformed by the Prague strain of Sarcoma Rous (XC cells). This fusion is strictly dependent on the expression of the viral genome and is probably due to the incorporation of viral antigens in the cell membrane. The integrity of cellular RNA synthesis is however not required. The fusion is probably due to a membrane structure characteristic of these transformed cells.     

Autoradiographic studies on RNA synthesis and transport in the ovary ofHydrophilus olivaceus fabr. (Hydrophilidae,Polyphaga, Coleoptera)

Summary Autoradiographic studies using³H-uridine in the ovary ofHydrophilus olivaceus Fabr. show that nurse cells, the germinal vesicle and follicular nuclei play an important role in contributing RNA whereby the major portion of RNA comes from the nurse cells.I am grateful to Prof. P. S. Ramamurty, School of Life Sciences, University of Hyderabad, Hyderabad, India, for his constant inspiration during the tenure of the present investigation.