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W I Mainwaring

Publications and source records attributed to W I Mainwaring.

54 records · Page 3Linked to original sources
PubMed1971

Studies on the solubilized ribonucleic acid polymerase from rat ventral prostate gland.

1. By using ultrasonic treatment in media of high ionic strength, the RNA polymerase activities associated with prostatic nuclei and nucleoli can be completely solubilized. Such enzyme preparations are entirely dependent on the provision of added DNA for full activity. 2. The solubilized enzymes from the nucleolar and extranucleolar regions can be separated by ion-exchange chromatography. 3. Based on differences in the optimum DNA templates, pH optima and the effects of ammonium sulphate on the activities in vitro, Mn(2+)- and Mg(2+)-specific enzymes are associated with both the nucleolar and extranucleolar regions of prostatic nuclei. 4. Androgenic hormones administered in vivo have a particularly pronounced effect on the activity of Mg(2+)-dependent enzyme associated with the isolated prostatic nucleolus. 5. Time-course experiments in vivo show that androgens induce a rapid stimulation of the solubilized Mg(2+)-dependent nucleolar enzyme before a pronounced activation of nucleolar chromatin can be measured. 6. The implications of these findings to the mechanism of action of androgenic steroids are discussed.

Ammonium Sulfate↗
PubMed1971

A reconstituted cell-free system for the specific transfer of steroid--receptor complexes into nuclear chromatin isolated from the rat ventral prostate gland.

1. A system has been developed for the specific transfer of [(3)H]dihydrotestosterone-receptor complexes into prostatic chromatin in vitro. 2. Under optimum conditions the overall transfer of [(3)H]dihydrotestosterone into purified chromatin in this reconstituted system is entirely consistent with the results obtained in whole tissue both in vivo and in vitro. 3. The transfer of [(3)H]dihydrotestosterone into chromatin is tissue-specific and maximal into chromatin isolated from androgen-dependent tissues. 4. The tissue specificity is maintained at two levels: first, in the presence of specific cytoplasmic androgen-receptor proteins; secondly, by the nature and composition of the chromatin itself. 5. Evidence is presented that androgenic steroids in vivo may maintain the tissue-specific nature of chromatin in androgen-dependent tissues by the selective induction of nuclear protein synthesis. 6. The relevance of these findings to the mechanism of action of androgenic steroids is discussed.

Animals↗
PubMed1969

The effect of age on protein synthesis in mouse liver.

1. A system of microsomes and 105000g supernatant from livers of old mice is less able to promote the incorporation of [(14)C]phenylalanine into protein than a similar system from livers of young animals. 2. The decrease in [(14)C]phenylalanine incorporation is attributable to changes in microsomes from old animals rather than in the cell-sap fraction. 3. Decreased synthetic ability is found in various classes of microsomes from older animals, namely unfractionated, light and heavy microsomes, but not in detergent-washed ribonucleoprotein particles. 4. Deletions of certain detergent-soluble microsomal proteins accompany the decreased synthetic ability of microsomes from older animals. 5. Microsomes from old mice are less responsive to a synthetic messenger RNA, polyuridylic acid, and this is partly due to a higher rate of hydrolysis in the presence of cell sap from animals of extreme age. 6. Other more direct evidence, from the priming of a cell-free protein-synthesizing system from bacteria and the examination of ribonucleoprotein particles on sucrose density gradients, suggests that senescence is accompanied by a decrease in messenger RNA content.

Aging↗
PubMed1968

Changes in the ribonucleic acid metabolism of aging mouse tissues with particular reference to the prostate gland.

1. The synthesis of RNA in purified nuclei of tissues from aged mice is substantially diminished. 2. As judged by the recovery of RNA in 105000g supernatants of tissue homogenates, the synthesis of ribosomal RNA may be particularly affected. 3. The decrease in RNA synthesis may be due to changes in the composition of the nuclear-associated protein with age, which result in changes in the priming ability of tissue chromatin. 4. Aging is accompanied by marked changes in the sedimentation profiles of ribonucleoprotein particles. These can be attributed to an age-associated depletion in messenger RNA or to an increased susceptibility to enzymic disaggregation.

Aging↗
PubMed1966

The effect of castration on the ribonucleic acid metabolism of an experimental prostatic tumour.

1. The incorporation of [(14)C]phenylalanine into the protein of microsomes obtained from an androgen-dependent transplantable prostatic tumour has been investigated. 2. The incorporation of [(14)C]ATP into the RNA of the nuclei from the same tumour has also been examined. 3. The castration of the host animal depresses the incorporation of both labelled compounds on subsequent incubation in vitro. 4. The uptake of phenylalanine can be markedly stimulated by polyuridylic acid only in tumours obtained from castrated host animals. 5. The tumour RNA-polymerase activity appears to be dependent on the concentrations of androgens in the host animal.

Adenosine Triphosphate↗
PubMed1965

The effect of oophorectomy on the ribonucleic acid metabolism of a transplantable uterine tumour.

1. The incorporation of [(14)C]phenylalanine and of [(3)H]uridine into the Guerin T8 uterine carcinoma has been examined. 2. The addition in vitro of polyuridylic acid caused an increase in the incorporation of labelled phenylalanine into tumour microsomes obtained from both oophorectomized and intact animals. 3. Oophorectomy of tumour-bearing animals decreased the specific activity due to the uptake in vivo of [(3)H]uridine into both the soluble and insoluble RNA of the tumour. 4. Actinomycin D caused a decrease in specific activity of RNA in the tumour in vivo, and puromycin inhibited uptake in vitro into tumour microsomes.

Animals↗