scholarly journals Androgenic regulation of elongation of polyribonucleotide chains on rat ventral-prostate chromatin

1978 ◽  
Vol 170 (2) ◽  
pp. 211-218 ◽  
Author(s):  
P Thomas ◽  
P Davies ◽  
K Griffiths
Keyword(s):  
Rna Polymerase ◽  
Reaction Rate ◽  
The Other ◽  
Ventral Prostate ◽  
Chain Elongation ◽  
Nucleoside Triphosphate ◽  
Receptor Complexes ◽  
Rat Ventral Prostate ◽  
Androgenic Regulation ◽  
Kinetics Of

The kinetics of polyribonucleotide-chain elongation by rat ventral-prostate RNA polymerase B with homologous chromatin as a template were investigated. Chain elongation was measured under conditions wherein all initiation had occurred, no reinitiation took place and the reaction rate was constant. The kinetic behaviour of prostate RNA polymerase B was consistent with a mathematical model formulated for the multisubstrate enzyme. The addition of each nucleoside triphosphate was independent of the other three. The overall rate of chain elongation was lower when prostate chromatin from castrated rats was used than with prostate chromatin from normal rats. The inclusion of dihydrotestosterone-receptor complexes stimulated the rate of elongation. Androgenic effects did not appear to be directed towards the addition of individual nucleoside triphosphates, but probably towards one of the other major events in RNA-chain elongation, i.e., unwinding of DNA or movement of the enzyme along the template.

DISTRIBUTION OF ACCEPTOR SITES FOR ANDROGEN-RECEPTOR COMPLEXES BETWEEN TRANSCRIPTIONALLY ACTIVE AND INACTIVE FRACTIONS OF RAT VENTRAL PROSTATE CHROMATIN

1980 ◽  
Vol 87 (2) ◽  
pp. 225-240 ◽  
Author(s):  
P. DAVIES ◽  
P. THOMAS ◽  
N. M. BORTHWICK ◽  
M. G. GILES
Keyword(s):  
Androgen Receptor ◽  
Rna Polymerase ◽  
Transcriptional Activity ◽  
Nuclear Dna ◽  
Intact Cell ◽  
Micrococcal Nuclease ◽  
Ventral Prostate ◽  
Receptor Complexes ◽  
Rat Ventral Prostate ◽  
Nascent Rna

Rat ventral prostate chromatin was separated into two main fractions by controlled digestion with micrococcal nuclease. The soluble fraction obtained after lysis of digested nuclei with EDTA (1 mmol/l), the S2 fraction, represented approximately 17% of the original nuclear DNA, and showed properties consistent with transcriptional activity, i.e. enrichment in nascent RNA, non-histone protein and endogenous RNA polymerase B activity as well as depletion in histones. The fraction sedimented after lysis of nuclei, fraction P, comprised approximately 60% of nuclear DNA, was depleted in nascent RNA, non-histone proteins and endogenous RNA polymerase B activity, but had a higher content of histones. In an attempt to relate the concentration of acceptor sites for androgen-receptor complexes with transcriptional activity, it was shown that the S2 fraction was enriched in these acceptor sites. However, if measurements were based on the intact cell the transcriptionally inactive portion contained 2·5–3 times as many 'acceptor' sites, although these sites had lower affinity for androgen-receptor complexes than had those in the transcriptionally active fraction.

scholarly journals Initiation and elongation of polyribonucleotide chains on rat ventral-prostate chromatin transcribed by homologous ribonucleic acid polymerase B.

1977 ◽  
Vol 166 (2) ◽  
pp. 189-198 ◽  
Author(s):  
P Thomas ◽  
P Davies ◽  
K Griffiths
Keyword(s):  
Rna Polymerase ◽  
Rna Synthesis ◽  
Prostate Gland ◽  
Ventral Prostate ◽  
Control Of Gene Expression ◽  
Rat Ventral Prostate ◽  
Associated Proteins ◽  
Ribonucleoside Triphosphate ◽  
Androgenic Steroids ◽  
Transcriptional Process

The characteristics of initiation of RNA synthesis and the elongation of RNA chains on rat ventral-prostate chromatin by RNA polymerase B were investigated by two methods. 1. Initiation was carried out under low-salt conditions with three ribonucleoside triphosphates, and elongation was begun in the absence of reinitiation by the addition of the fourth ribonucleoside triphosphate and increasing the salt concentration. 2. Stable initiation complexes were formed by preincubation of enzyme with template at 37 degrees C, elongation was started by the addition of all four ribonucleoside triphosphates and reinitiation or spurious RNA synthesis was prevented by rifamycin AF/013. The latter method gave more reliable results. The dependence of those parameters on the androgenic status of the animal was studied. During the first 24h after castration, elongation was mainly affected, whereas after 72h a smaller number of initiation sites for RNA polymerase B on chromatin was evident. Considerable diurnal variations in the various parameters were observed. Changes in the relative concentrations of the chromatin-associated proteins were also observed after castration. In the rat ventral-prostate gland androgenic steroids may not only influence one stage of the transcriptional process, but may affect many factors involved in the control of gene expression.

THE KINETICS OF THE DECOMPOSITION REACTIONS OF THE LOWER PARAFFINS: I. n-BUTANE

1938 ◽  
Vol 16b (5) ◽  
pp. 176-193 ◽  
Author(s):  
E. W. R. Steacie ◽  
I. E. Puddington
Keyword(s):  
Reaction Rate ◽  
High Pressures ◽  
The Other ◽  
First Order ◽  
Decomposition Reactions ◽  
Temperature And Pressure ◽  
Products Of Reaction ◽  
Kinetics Of ◽  
Good Agreement ◽  
Mechanism Of The Reaction

The kinetics of the thermal decomposition of n-butane has been investigated at pressures from 5 to 60 cm. and temperatures from 513 to 572 °C. The initial first order rate constants at high pressures are given by[Formula: see text]The results are in good agreement with the work of Frey and Hepp, but differ greatly from that of Paul and Marek. The reaction rate falls off strongly with diminishing pressure; this is rather surprising for a molecule as complex as butane. The first order constants in a given run fall rapidly as the reaction progresses. The last two facts suggest that chain processes may be involved.A large number of analyses of the products of reaction have been made at various pressures, temperatures, and stages of the reaction, the method being that of low-temperature fractional distillation. The products are virtually independent of temperature and pressure over the range investigated. The initial products, obtained by extrapolation to zero decomposition, are:—H2, 2.9; CH4, 33.9; C3H6, 33.9; C2H4, 15.2; C2H6, 14.1%. The mechanism of the reaction is discussed, and the results are compared with those of the other paraffin decompositions.

scholarly journals The androgenic regulation of superhelical-DNA nicking-closing enzyme in rat ventral prostate

1981 ◽  
Vol 196 (1) ◽  
pp. 195-202 ◽  
Author(s):  
J D Filipenko ◽  
P S Rennie ◽  
N Bruchovsky
Keyword(s):  
Enzyme Activity ◽  
Dna Synthesis ◽  
Chromatin Structure ◽  
Structural Organization ◽  
Time Course ◽  
Ventral Prostate ◽  
Rat Ventral Prostate ◽  
Dna Nicking ◽  
Androgenic Regulation

The activity of superhelical-DNA nicking-closing enzyme (NC enzyme) was measured in nuclei from rat ventral prostate by a fluorimetric assay based on the binding of ethidium bromide to supercoiled phage-PM2 DNA. The nuclear concentration of NC-enzyme activity declined rapidly after castration, although this response could be prevented by daily administration of dihydrotestosterone. The low NC-enzyme activity in involuted prostates (10% of normal) was restored to normal after 8-10 days of treatment with androgen. In the regenerating prostate the time course of restoration of NC-enzyme activity was not in phase with that of DNA synthesis. Examination of nucleosome repeat lengths and the arrangement of nucleosomes along the chromatin fibre revealed no differences in the structural organization of chromatin in prostates with high or low NC-enzyme activity. Together, these results suggest that the major role of NC enzyme is related to the onset and maintenance of differentiation in the prostate and that the activity of this enzyme is not expressed through gross alterations in chromatin structure.

scholarly journals The androgenic regulation of the activities of enzymes engaged in the synthesis of deoxyribonucleic acid in rat ventral prostate gland

1975 ◽  
Vol 152 (1) ◽  
pp. 1-16 ◽  
Author(s):  
P S Rennie ◽  
E K Symes ◽  
W J Mainwaring
Keyword(s):  
Dna Replication ◽  
Dna Polymerase ◽  
Hormonal Regulation ◽  
Prostate Gland ◽  
Experimental System ◽  
Physicochemical Characteristics ◽  
Ventral Prostate ◽  
Receptor System ◽  
Rat Ventral Prostate ◽  
Androgenic Regulation

1. The restoration of mitosis and growth of the prostate gland of castrated animals by androgens provides a favourable experimental system for studying the hormonal regulation of enzymes engaged in DNA replication. 2. Many DNA polymerase activities were identified in the prostate gland, but only a 9S form with a particular preference for denatured DNA as template was conspicuously enhanced by androgenic stimulation. 3. Thymidine kinase also provided a sensitive indicator of the hormonal regulation of DNA replication, and on electrophoretic criteria, one discrete form of the enzyme appeared precisely with the onset of mitoris. 4. Evidence is presented to support the view that DNA ligase activity is intimately associated in the process of DNA replication in the prostate gland. 5. A spectrum of deoxyribonuclease activities is present in the prostate gland, but only one form (pI7.0) can safely be said to be implicated in the process of DNA replication. 6. Androgenic stimulation of the prostate gland leads to the appearance of a component capable of denaturing or unwinding prostate DNA. This component is seemingly distinct from RNA or DNA polymerase activities on the basis of several distince physicochemical characteristics. 7. The conspicuous feature of all the changes in enzyme activities evoked by androgens in the prostate gland is their acute tissue- and steroid-specificity. Such changes could not be mimicked in liver or spleen and the regulatory role of androgens could not be simulated by other classes of steroid hormones. Particularly on the basis of studies with the anti-androgen cyproterone acetate, it is concluded that the changes are initially mediated by the androgen-receptor system and the high-affinity binding of 5α-dihydrotestosterone in the prostate gland. 8. The results are discussed in the context of the mechanism of action of androgens.

EFFECT OF SOME SYNANDROGENS AND ANTIANDROGENS ON THE CONVERSION OF TESTOSTERONE TO DIHYDROTESTOSTERONE IN THE CULTURED RAT VENTRAL PROSTATE

1976 ◽  
Vol 81 (2) ◽  
pp. 398-408 ◽  
Author(s):  
Risto Johansson
Keyword(s):  
Culture Medium ◽  
The Other ◽  
Ventral Prostate ◽  
Testosterone Metabolism ◽  
Other Hand ◽  
Rat Ventral Prostate ◽  
Target Organs

ABSTRACT The actions of prolactin, insulin and cortisol on the conversion of testosterone to dihydrotestosterone in the cultured rat ventral prostate were examined in conditions in which they have been demonstrated to act synergistically with testosterone on the macromolecule synthesis of the prostate. On the other hand oestradiol, progesterone and cyproterone were tested similarly in conditions where they have been shown to be effective antiandrogens. The metabolism of testosterone to dihydrotestosterone was found to be extremely rapid and approximately 70 % of the radioactive steroids in the tissue was dihydrotestosterone from 5 min onwards, but only insignificant amounts of dihydrotestosterone were found in the culture medium during the first hour. Physiological concentrations of the synandrogens did not alter the metabolism of testosterone or the accumulation of the steroids into the tissue. Oestradiol, progesterone and unlabelled testosterone in a 500-fold concentration markedly reduced the conversion of tritiated testosterone to dihydrotestosterone while cyproterone and dihydrotestosterone had no effect. The possible role of other hormones in the alteration of testosterone metabolism in the target organs as the mechanism of synandrogenic or antiandrogenic action is discussed.

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