RNA and purine metabolism during development of the normal and dystrophic chicken

Abstract

1. RNA content of control breast muscle increased between 19 days en ovo and 1 week after hatching and then declined. In dystrophic muscle RNA content did not decrease until 2 weeks after hatching and at all ages from 2 weeks to 3–5 months was greater than that of corresponding controls. The dystrophic condition did not affect the RNA or DNA content of other tissues investigated. 2. AMP deaminase (adenylate aminohydrolase, EC 3.5.4.6) activity of control breast muscle increased 4-fold between 19 days en ovo and 1–2 months after hatching. In the dystrophic group there was a delayed, temporary increase in enzyme activity at one month and values were always less than those of corresponding controls from 1 week old and older chickens. 3. Inosine phosphorylase (purine nucleoside:orthophosphate ribosyltransferase, EC 2.4.2.1) activity of control breast muscle decreased after the first week ex ovo, while in dystrophic muscle activity remained at essentially embryonic levels. Enzyme activity in pancreas and liver increased during development and was unaffected by the dystrophic condition. 4. Xanthine dehydrogenase activity in liver and pancreas from control chickens increased during development. In pancreas from the dystrophic group enzyme activity did not increase appreciably and was significantly less than that of adult (3–5 months) controls. The dystrophic condition did not affect the development of enzyme activity in liver or activity in adult kidney. 5. Hypoxanthine phosphoribosyltransferase (EC 2.4.2.8) activity decreased in control muscle after hatching while remaining at essentially embryonic levels in breast muscle from the dystrophic group. 6. Incorporation in vivo of [8- 14C]hypoxanthine into breast muscle RNA was greater in 1–6-week-old dystrophic chickens than in comparable controls.