scholarly journals TRANSCRIPTION SITES IN SPREAD MEIOTIC PROPHASE CHROMOSOMES FROM MOUSE SPERMATOCYTES

1974 ◽  
Vol 63 (3) ◽  
pp. 923-935 ◽  
Author(s):  
A. L. Kierszenbaum ◽  
Laura L. Tres
Keyword(s):  
Gene Expression ◽  
Meiotic Prophase ◽  
Rna Synthesis ◽  
Sex Chromosome ◽  
Nucleolar Organizer ◽  
Structural Elements ◽  
Autosomal Bivalents ◽  
Whole Mount ◽  
Nuclear Rna ◽  
Transcription Sites

Mouse spermatocytes at pachytene stage have been examined by whole-mount electron microscope techniques complemented with autoradiography as an approach for visualizing their transcriptive activity. Structural elements of meiotic bivalents, such as synaptonemal complexes and chromatin fibers, have been satisfactorily displayed in the total set of autosomal and sexual bivalents in single spermatocytes. Adequate preservation of the entire set of bivalents has provided a basis for recognition of sites where presumptive preribosomal RNA and heterogeneous nuclear RNA species are being transcribed at different segments of autosomal bivalents. Nucleoli attached to the basal knob region where nucleolar organizer cistrons are assumed to be located and ribonucleoprotein fibrils associated with distinct chromatin loops have been recognized. These structural findings have been correlated with display of [3H]uridine incorporation sites in thin-section and whole-mount electron microscopy autoradiographic preparations. A low transcriptive activity of the sexual bivalent contrasted with extensive gene expression in autosomal bivalents. Each sex chromosome shows a double axial core. A short region of pairing with a synaptonemal complex joins the two chromosomes at one end. We conclude that variations in the rate of RNA synthesis throughout meiotic prophase stages in the mouse are expressed as fluctuations in the amount and distribution of distinct RNA species at specific segments of the bivalents.

scholarly journals RNA transcription in myocardial-cell nuclei during postnatal development. A study establishing an assay system for transcription in vitro

1988 ◽  
Vol 256 (2) ◽  
pp. 441-445 ◽  
Author(s):  
J D McCully ◽  
C C Liew
Keyword(s):  
Gene Expression ◽  
Rna Synthesis ◽  
Myocardial Cell ◽  
Assay System ◽  
Specific Gene ◽  
Cell Nuclei ◽  
Rna Transcription ◽  
Nuclear Rna ◽  
Transcription In Vitro

A system for RNA transcription in vitro was established in order to determine the relative rate of RNA synthesis in neonatal and adult rat myocardial cells. This assay system optimizes the incorporation of [3H]UMP into RNA by using 3.5 x 10(7) myocardial-cell nuclei, and minimizes RNA degradation for at least 1 h in transcription in vitro, by the addition of human placental RNAase inhibitor. A 100% increase in the incorporation of [3H]UMP into myocardial-cell RNA was found on addition of this inhibitor. Myocardial-cell nuclei derived from 5-, 10-, 15-, 20-, and greater than 100-day-old rat hearts indicated that there is a progressive decrease in RNA synthesis with age. A 3-fold increase in RNA synthesis in 5-day-old myocardial cell nuclei as compared with 20-day-old rat heart was found. RNA synthesis in the adult myocardial cell nuclei decreased more than 10-fold in comparison with the 5-day-old newborn. The incorporation of [3H]UMP into rat liver nuclear RNA was 3-fold greater than in the myocardial-cell nuclear RNA, even when compared with the highly active transcription of 12-day-old heart nuclei. In order to determine the relationship between total RNA synthesis and the extent of specific gene expression in myocardial-cell nuclei during development, two distinct cDNA probes were used for Northern-blot analysis. Our results indicate that myosin-heavy-chain gene expression is remarkably decreased with age, whereas the ‘housekeeping’ gene is continually expressed independently of age.

scholarly journals Primary microRNA transcript retention at sites of transcription leads to enhanced microRNA production

2008 ◽  
Vol 182 (1) ◽  
pp. 61-76 ◽  
Author(s):  
Jan M. Pawlicki ◽  
Joan A. Steitz
Keyword(s):  
Gene Expression ◽  
Noncoding Rnas ◽  
Mature Mirnas ◽  
Splicing Factor ◽  
Mirna Biogenesis ◽  
Nuclear Rna ◽  
Transcription Sites ◽  
Cleavage And Polyadenylation ◽  
Precursor Mirnas ◽  
Nuclear Levels

MicroRNAs (miRNAs) are noncoding RNAs with important roles in regulating gene expression. In studying the earliest nuclear steps of miRNA biogenesis, we observe that primary miRNA (pri-miRNA) transcripts retained at transcription sites due to the deletion of 3′-end processing signals are converted more efficiently into precursor miRNAs (pre-miRNAs) than pri-miRNAs that are cleaved, polyadenylated, and released. Flanking exons, which also increase retention at transcription sites, likewise contribute to increased levels of intronic pri-miRNAs. Consistently, efficiently processed endogenous pri-miRNAs are enriched in chromatin-associated nuclear fractions. In contrast, pri-miRNAs that accumulate to high nuclear levels after cleavage and polyadenylation because of the presence of a viral RNA element (the ENE of the Kaposi's sarcoma–associated herpes virus polyadenylated nuclear RNA) are not efficiently processed to precursor or mature miRNAs. Exogenous pri-miRNAs unexpectedly localize to nuclear foci containing splicing factor SC35; yet these foci are unlikely to represent sites of miRNA transcription or processing. Together, our results suggest that pri-miRNA processing is enhanced by coupling to transcription.

scholarly journals A STUDY OF THE NUCLEOLAR MATERIAL IN SCIARA COPROPHILA

1966 ◽  
Vol 29 (2) ◽  
pp. 347-359 ◽  
Author(s):  
Natalia Gabrusewycz-Garcia ◽  
Ruth G. Kleinfeld
Keyword(s):  
Rna Synthesis ◽  
Polytene Chromosomes ◽  
Nucleolar Organizer ◽  
Prepupal Stage ◽  
Large Numbers ◽  
Nucleolar Material ◽  
Wide Range ◽  
Nuclear Rna ◽  
Dna Puffs ◽  
Range Of Variation

In the polytene chromosomes of Sciara coprophila, in addition to a nucleolus, large numbers of nucleolarlike structures or micronucleoli are formed. A detailed mapping localized the nucleolar organizer at one end of the X chromosome and revealed that approximately 18% of the bands of each chromosome are potentially capable of producing micronucleoli. Most of these sites are in regions known from a previous study to show asynchronous DNA replication: DNA puffs and certain heterochromatic regions. Micronucleoli are rarely found in association with bulbs. The RNA metabolism of the polytene chromosomes during late fourth instar was studied using radioautographic techniques. Isolated glands were incubated in tritiated uridine for 10 to 30 min, and radioautographs were made of squash preparations. Despite the wide range of variation found among different larval cultures, the following pattern was observed. Just prior to and at the beginning of DNA puff formation, a period of intense extrachromosomal nucleolar and micronucleolar RNA synthesis occurs. After maximal development of the DNA puffs, the synthesis of extrachromosomal RNA is at a low point, while incorporation into bulbs and DNA puffs remains high. With the onset of the prepupal stage, all nuclear RNA synthesis ceases.

THE NUCLEAR RNA-SYNTHESIS IN THE ANTERIOR PITUITARY OF RATS

1965 ◽  
Vol 49 (3_Suppl) ◽  
pp. S160 ◽  
Author(s):  
E. Stöcker ◽  
G. Dhom
Keyword(s):  
Anterior Pituitary ◽  
Rna Synthesis ◽  
Nuclear Rna Synthesis ◽  
Nuclear Rna

scholarly journals INHIBITING EFFECT OF THE NEW CYTOTOXIC ANTIBIOTIC DAUNOMYCIN ON NUCLEIC ACIDS AND MITOTIC ACTIVITY OF HELA CELLS

1965 ◽  
Vol 27 (3) ◽  
pp. 545-550 ◽  
Author(s):  
A. Di Marco ◽  
R. Silvestrini ◽  
S. Di Marco ◽  
T. Dasdia
Keyword(s):  
Mitotic Activity ◽  
Rna Synthesis ◽  
Thymidine Incorporation ◽  
Acid Synthesis ◽  
Acetyl Derivative ◽  
Total Inhibition ◽  
Nuclear Rna ◽  
Nucleolar Rna ◽  
Higher Doses

The effect has been studied of Actinomycin D, Daunomycin (Da.), and Da. N acetyl derivative on mitotic activity and on the nucleic acid synthesis of in vitro HeLa cell cultures. The experiments were carried out by means of the radioautographic technique using stripping films. The relative uptake of thymidine-H3 and uridine-H3 was determined by means of the reduced silver grain count present in the nuclei of controls and treated cells. The mitotic activity and thymidine incorporation were noticeably reduced by Daunomycin and Actinomycin, whereas both processes appeared less affected by Da. N acetyl derivative. As regards nuclear RNA synthesis, all three antibiotics at low doses chiefly inhibit nucleolar RNA synthesis. On the other hand, whilst Actinomycin at higher doses causes an almost total inhibition of the synthesis of the whole nuclear RNA, in Daunomycin- and Da. N acetyl derivative-treated cells extranucleolar RNA synthesis is less susceptible to inhibition.

scholarly journals FISHing for chick genes: Triple-label whole-mount fluorescence in situ hybridization detects simultaneous and overlapping gene expression in avian embryos

2004 ◽  
Vol 229 (3) ◽  
pp. 651-657 ◽  
Author(s):  
Nathaniel Denkers ◽  
Pilar García-Villalba ◽  
Christopher K. Rodesch ◽  
Kandice R. Nielson ◽  
Teri Jo Mauch
Keyword(s):  
Gene Expression ◽  
In Situ Hybridization ◽  
Fluorescence In Situ Hybridization ◽  
Avian Embryos ◽  
Overlapping Gene ◽  
Whole Mount

scholarly journals ELECTRON MICROSCOPIC EXAMINATION OF THE SITES OF NUCLEAR RNA SYNTHESIS DURING AMPHIBIAN EMBRYOGENESIS

1965 ◽  
Vol 26 (3) ◽  
pp. 937-958 ◽  
Author(s):  
Shuichi Karasaki
Keyword(s):  
Rna Synthesis ◽  
Developmental Stages ◽  
Early Embryo ◽  
Tail Bud ◽  
Electron Microscopic ◽  
Electron Microscopic Autoradiography ◽  
Nuclear Rna Synthesis ◽  
Nuclear Rna ◽  
Chromatin Material ◽  
Labeled Rna

The site of H3-uridine incorporation and the fate of labeled RNA during early embryo-genesis of the newt Triturus pyrrhogaster were studied with electron microscopic autoradiography. Isolated ectodermal and mesodermal tissues from the embryos were treated in H3-uridine for 3 hours and cultured in cold solution for various periods before fixation with OsO4 and embedding in Epon. At the blastula stage, the only structural component of the nucleus seen in electron micrographs is a mass of chromatin fibrils. At the early gastrula stage, the primary nucleoli originate as small dense fibrous bodies within the chromatin material. These dense fibrous nucleoli enlarge during successive developmental stages by the acquisition of granular components 150 A in diameter, which form a layer around them. Simultaneously larger granules (300 to 500 A) appear in the chromatin, and they fill the interchromatin spaces by the tail bud stage. Autoradiographic examination has demonstrated that nuclear RNA synthesis takes place in both the nucleolus and the chromatin, with the former consistently showing more label per unit area than the latter. When changes in the distribution pattern of radioactivity were studied 3 to 24 hours after immersion in isotope at each developmental stage, the following results were obtained. Labeled RNA is first localized in the fibrous region of the nucleolus and in the peripheral region of chromatin material. After longer culture in non-radioactive medium, labeled materials also appear in the granular region of the nucleolus and in the interchromatin areas. Further incubation gives labeling in cytoplasm.

Accumulation of U14 small nuclear RNA in Saccharomyces cerevisiae requires box C, box D, and a 5', 3' terminal stem

1992 ◽  
Vol 12 (10) ◽  
pp. 4456-4463
Author(s):  
G M Huang ◽  
A Jarmolowski ◽  
J C Struck ◽  
M J Fournier
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Binding ◽  
Essential Elements ◽  
Structural Elements ◽  
Small Nuclear Rna ◽  
Small Nuclear Rnas ◽  
Nuclear Rna ◽  
Compensatory Base Changes ◽  
Normal Processing ◽  
Intragenic Suppressor

U14 is one of several nucleolar small nuclear RNAs required for normal processing of rRNA. Functional mapping of U14 from Saccharomyces cerevisiae has yielded a number of mutants defective in U14 accumulation or function. In this study, we have further defined three structural elements required for U14 accumulation. The essential elements include the U14-conserved box C and box D sequences and a 5', 3' terminal stem. The box elements are coconserved among several nucleolar small nuclear RNAs and have been implicated in binding of the protein fibrillarin. New mutational results show that the first GA bases of the box C sequence UGAUGA are essential, and two vital bases in box D have also been identified. An intragenic suppressor of a lethal box C mutant has been isolated and shown to contain a new box C-like PyGAUG sequence two bases upstream of normal box C. The importance of the terminal stem was confirmed from new compensatory base changes and the finding that accumulation defects in the box elements can be complemented by extending the terminal stem. The results suggest that the observed defects in accumulation reflect U14 instability and that protein binding to one or more of these elements is required for metabolic stability.

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