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E S Chang

Publications and source records attributed to E S Chang.

50 records · Page 3Linked to original sources
PubMed1980

Juvenile hormone-binding protein from the cytosol of Drosophila Kc cells.

Insect cells of an established line, Drosophila Kc cells, take up and metabolize juvenile hormone (JH). The cytoplasm of these cells contains a protein that binds JH with specificity, saturability, and high affinity (K(d) = 1.56 x 10(-8) M). The kinetics for the specific binding and dissociation of JH I were independently measured, and the rate constants were found to be k(a) = 1.3 x 10(6) M(-1) min(-1), k(d) = 1.3 x 10(-2) min(-1), respectively. All three juvenile hormones bind to the protein with comparable affinities; the corresponding acid or diol metabolites of JH I are not bound. About 2500 hormone-binding protein molecules are present per cell. The protein has a molecular weight of 80,000 as estimated by gel permeation chromatography and by sucrose gradient sedimentation. The properties of this protein suggest that it functions as a cytoplasmic receptor for juvenile hormone.

Journal Article↗
PubMed1977

Secretion of alpha-ecdysone by crab Y-organs in vitro.

The cultured molting glands (Y-organs) from two species of crabs secrete a product whose behavior in several chromatographic systems and whose mass spectrum are identical with those of authentic alpha-ecdysone. It appears that alpha-ecdysone is the only molting hormone secreted by the Y-organ, and that the Y-organ is the sole source of alpha-ecdysone in these animals.

Animals↗
PubMed1975

Effect of chlorinated hydrocarbons on shell gland carbonic anhydrase and egg shell thickness in Japanese quail.

Japanese quail (Coturnix japonica) were fed different levels of pesticide in their diets for 15 weeks. The levels of pesticide used were 25, 50, 100, 200 p.p.m. DDE 25, 50, 100, 200 p.p.m. DDT and 50 p.p.m. PCB. Carbonic anhydrase activities were analyzed in the shell glands and blood; pesticide concentration in the eggs of the first experiment was measured; egg weight, shell weight and shell thickness were also measured. No depression in growth was observed at any levels of pesticides used. Quail fed 200 p.p.m. DDE showed a high mortality rate after 10--12 weeks on the diet, while other levels produced no increase in death rate. Lower levels of DDT and DDE (25 and 50 p.p.m.) had no significant effect on egg shell weight or thickness. Higher levels (100 and 200 p.p.m) of DDT and DDE produced a small increase in shell weight and a 5 per cent decrease in shell thickness and were associated with increased shell breakage. At levels of 25 p.p.m. and 50 p.p.m. DDE, the activity of carbonic anhydrase in the shell gland was significantly increased. At levels of 200 p.p.m. DDE and 100 p.p.m. DDT in the diet, the activity of carbonic anhydrase was decreased by 12--15 per cent. A 50 per cent reduction in carbonic anhydrase activity in the shell gland seemed to be necessary for an increased production of soft shelled eggs when it was induces by sulfanilamide. Pesticide residues in the eggs of Japanes quail up to about 300 p.p.m. DDE and 150 p.p.m. DDT were not associated with any change in egg shell thickness. At about 600 p.p.m. DDE and 500 p.p.m. DDT in the eggs, corresponding to 100 and 200 p.p.m. in the diet, the egg shell thickness was reduced by 5 per cent. PCB at 50 p.p.m. produced a small decrease (4.5 per cent) in shell thickness and an increase in the percentage of cracked eggs.

Animals↗