Fig. 6. Carbamoyl phosphate synthetase II (CPSase II) (A) and CPSase III (B) activity in whole-animal crude extracts during early development and in selected adult tissues (columns) of Clarias gariepinus. Filled triangles, whole embryos and yolk-sac larvae; filled circles, larvae fed Artemia; open circles, starved larvae.Values are means ± S.D. of assays on 3–4 samples, except for fed larvae at 79 and 119h post-fertilization (N=2, ± range). CPSase II activity was calculated from the rate obtained with glutamine (Gln) only in the reaction mix, while CPSase III was calculated from the rate with Gln + N-acetyl-L-glutamate (AGA) minus the rate with Gln only. The relative capacities of the two CPSases in total carbamoyl phosphate formation in vitro are shown in C (% UTP inhibition calculated as described in Table1, high values: mostly CPSase II) and D (AGA activation factor, rate with Gln + AGA/rate with Gln only, high values: mostly CPSase III). CYA, complete yolk absorption; ND, not detectable.
