Precocious development of glucuronidating and hydroxylating enzymes in chick embryos treated with pituitary grafts.
1. Initiation of precocious development of UDP-glucuronyltransferase by an endogenous factor is reported for the first time. 2. This development occurs in chick embryo liver and kidney after grafting of the cephalic lobe of chicken pars-distalis pituitary tissue on to the chorioallantoic membrane, and in liver results in a rise in the enzyme activity from virtually zero to ;adult' values. Aniline hydroxylase also precociously develops in the liver of grafted embryos, its activity rising from one-third to the full adult value. Specific activities of glucose 6-phosphatase, cytochrome P-450 and NADPH-cytochrome c reductase did not significantly change. 3. The response of the transferase does not require the presence of host pituitary gland nor, apart from 1 day's necessary initiation, the presence of the graft itself. 4. The host becomes competent to respond on the 14th day of incubation; response continues for at least 3 days after removal of the graft, and for 2 days in the isolated liver. Grafting of embryonic pars distalis younger than 17 days does not evoke a response in the host liver. 5. Secretion of the pituitary factor increases suddenly some 24-48h before the naturally developing surge in liver UDP-glucuronyltransferase activity and may be responsible for initiating this rise in vivo. 6. The factor is probably not a growth or luteinizing hormone; its nature and the likelihood of a secondary hormone acting directly on the liver are discussed.
D000311:Adrenal Glands / Q000378:metabolism; D000375:Aging; D000815:Aniline Hydroxylase / Q000378:metabolism*; D000818:Animals; D002642:Chick Embryo / Q000201:enzymology* / Q000378:metabolism; D004790:Enzyme Induction; D014453:Glucuronosyltransferase / Q000378:metabolism*; D006602:Hexosyltransferases / Q000378:metabolism*; D007668:Kidney / Q000196:embryology / Q000201:enzymology; D008099:Liver / Q000196:embryology / Q000201:enzymology / Q000378:metabolism; D008862:Microsomes, Liver / Q000201:enzymology; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D010902:Pituitary Gland / Q000378:metabolism / Q000637:transplantation*; D013961:Thyroid Gland / Q000378:metabolism
D006899:Mixed Function Oxygenases; D000815:Aniline Hydroxylase; D006602:Hexosyltransferases; D014453:Glucuronosyltransferase