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Biomedical subjects

D J Osborne

Publications and source records attributed to D J Osborne.

At least 73 records · Page 4Linked to original sources
PubMed1973

Protein synthesis and loss of viability in rye embryos. The lability of transferase enzymes during senscence.

Poor germination and eventual loss of viability of rye grains on storage reflects a decreasing ability of embryos to synthesize protein in vivo. Cell-free protein-synthesizing systems from low viability embryo stocks exhibit lesions in the soluble components of the post-ribosomal supernatant fractions. tRNA and aminoacyl-tRNA synthetases are not impaired. The activity of enzymes concerned with transfer of phenylalanyl-tRNA from the aminoacyl to the peptidyl site on the ribosome is slightly decreased. The transfer enzymes (transferase I) involved in the binding of phenylalanyl-tRNA to the aminoacyl site show a loss of activity that closely reflects the loss of viability and the decline of protein synthesis of the embryo in vivo. The inactivation of labile transferase I components may be a major factor leading to senescence and loss of viability in rye grains.

Acyltransferases↗
PubMed1973

The effect of ethylene on (1-14C)glycerol incorporation into phospholipids of etiolated pea stems.

The effect of ethylene (10 p.p.m.) on the rate of incorporation of [1-(14)C]glycerol into phospholipids of etiolated pea stems was studied. After 2-3h treatment with ethylene, incorporation was decreased by 50%. It remained at this value for as long as ethylene was supplied (8h). Handling the plants also caused a temporary decrease in incorporation, which we attribute to the production of endogenous ;wound' ethylene. The percentage decrease in incorporation was the same in four major phospholipid fractions, i.e. phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylinositol.

Carbon Radioisotopes↗
PubMed1969

Ethylene: a factor in defoliation induced by auxins.

Aerial sprays of synthetic auxins defoliate many species of tropical trees. Treatment of Euonymus japonica leaves with the n-butyl ester of 2,4-dichlorophenoxyacetic acid causes premature senescence and leaf fall and stimulates ethylene production by the blade 5-to 25-fold. Exposure to ethylene alone similarly accelerates senescence and leaf fall. Evidence indicates that the defoliant action of auxin is mediated through the enhanced amounts of ethylene in the blade.

Ethylenes↗
PubMed1966

Transport of the Auxin 2,4-Dichlorophenoxyacetic Acid Through Absiccion Zones, Pulvini, and Petioles of Phaseolus vulgaris.

Measurements were made of the transport of 2,4-dichlorophenoxyacetic acid-(14)C (2,4-D) through segments cut from the region of the distal abscission zone in young and old primary leaves of Phaseolus vulgaris L. When old leaves were used basipetal transport of 2,4-D in segments including pulvinar tissue, abscission zone, and petiolar tissue was much less than in wholly petiolar segments. In both young and old plants, segments consisting entirely of pulvinar tissue transported 2,4-D basipetally at a velocity about half that in petiolar tissue. At both ages the flux of 2,4-D through pulvinar tissue was less than that through petiolar tissue. In segments from old leaves the flux through pulvinar tissue was much less than in young plants; the flux through petiolar tissue changed little with age. There was no change with age in the velocity of basipetal transport. The distribution of (14)C along segments including the abscission zone showed no marked discontinuity. It was concluded that the pulvinus limited the basipetal movement of 2,4-D through segments from old leaves which included both pulvinar and petiolar tissue, but there was no evidence that the abscission zone itself was a barrier to auxin transport.

Journal Article↗