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M G Ord

Publications and source records attributed to M G Ord.

47 records · Page 3Linked to original sources
PubMed1969

Further studies on phosphorylation and the thiol-disulphide ratio of histones in growth and development.

1. The proportion of thiol groups in the total thiol+disulphide of histone extracts from fertilized eggs from Echinus and Psammechinus was increased during periods of structural alterations in the nucleus. 2. The probable start of DNA synthesis in the fertilized eggs coincided with periods of maximum thiol content. 3. Histone extracts from rat liver and regenerating liver were predominantly in the thiol form and no significant variations could be detected during the first 30hr. after partial hepatectomy. 4. An assay system was developed to follow the phosphorylation believed to be associated with the arginine-rich histone F3. Phosphorylation increased by 50% at 1 and 2hr. after partial hepatectomy. The phosphate content also increased during the period of DNA synthesis. 5. The increased phosphorylation found 1hr. after partial hepatectomy was not prevented by actinomycin or prior irradiation. 6. The phosphate content of histone F1 was very high in livers from foetal rats and declined in neonatal rats similarly to the decline in DNA synthesis.

Animals↗
PubMed1968

Variations in the phosphate content and thiołdisulphide ratio of histones during the cell cycle. Studies with regenerating rat liver and sea urchins.

1. In regenerating rat liver the phosphate content of the lysine-rich histone F1, but not that of the more arginine-rich histone F3-1, increases during the period of DNA synthesis. 2. The phosphorylation of histone F1 in this ;S period' is decreased by gamma-irradiation, but, like phosphate uptake into DNA, is affected to an even greater extent if the irradiation is given in the presynthetic period. 3. Histones from three species of sea-urchin eggs show similarities to the F2 and F3 groups of histones from mammalian thymus gland. 4. The proportion of thiol to total thiol plus disulphide in acid extracts from sea-urchin eggs varies from less than 20% in mature unfertilized eggs to 59% just before cleavage. 5. The phosphorylated forms of histones F1 and F3 are less effective in decreasing DNA synthesis by DNA polymerase than the non-phosphorylated forms. 6. Oxidation of thiol groups on histone F3-1 does not affect its capacity to decrease DNA synthesis in vitro.

Acrylic Resins↗
PubMed1967

Phosphate and thiol groups in histone f3 from rat liver and thymus nuclei.

1. Differences in washing procedures and conditions of dialysis affected the type of histone f3 obtained from rat liver and thymus nuclei. 2. Sulphur-rich preparations of f3 contained phosphate and had SH+SS: phosphorus ratio 1:2. 3. Sulphur-rich f3 from livers of [(14)C]adenine-labelled rats gave counts indicating a phosphorus: adenine ratio 1:1. 4. Evidence was presented that histones f3 and f1 exist in nuclei as families of proteins, differing with respect to their sulphur or phosphorus content or both. 5. The significance of the different states of phosphorylation and oxidation of histones f1 and f3 was discussed.

Animals↗
PubMed1966

Metabolic properties of histones from rat liver and thymus gland.

1. The incorporation of (14)C-labelled amino acids into acid-extractable proteins from rat-liver and -thymus nuclei confirmed the existence of a protein component with a higher uptake than that into the major histone components. 2. This rapidly labelled component appeared to contain the thiol groups detectable in the acid extracts. 3. Histone f1 contained 1mol. of serine phosphate/mol. of mol.wt. of 42000-43000. 4. Phosphate was present in other components of the 50mm-hydrochloric acid extract from liver and thymus nuclei, and was probably associated with the thiol-containing component. 5. The difference in amino acid uptake into the histones of diffuse and dense chromatin was confirmed. Dense chromatin was found to have a higher proportion of disulphide than did diffuse chromatin.

Adenine↗