Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1973944 | Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology | 2006 | 11 Pages |
Rapidly growing African catfish yolk sac larvae were investigated during the first 22 h after hatching. Body compartment protein concentration increased fourfold yet oxygen consumption remained constant (mean = 21.3 ± 3.2 nmol O2 mg− 1 protein h− 1), suggesting fast growth results mainly from yolk sac protein absorption. The protein synthesis rates at 1–2 and 5–6 h also equaled the highest conceivable rates of muscle protein synthesis; 11.6–11.9% and 7.4–7.9% day− 1, respectively. Therefore the corresponding energetic costs of protein synthesis were almost the theoretical minimum; 13.0 ± 1.7–16.3 ± 2.8 μmol O2 mg− 1 protein synthesised. Total protein synthesis expenditure (74.5–77.7 μmol O2 g− 1 protein h− 1) was also less than other yolk sac larvae. These protein synthesis rates resulted from high RNA concentrations (113.2 ± 3.4 μg RNA mg− 1 protein) and were also correlated with RNA translational efficiency. High translational efficiency (1 h; 1.2 ± 0.1 mg protein synthesised μg− 1 RNA day− 1) equaled high synthesis rate (36.8 ± 5.4 μg RNA μg− 1 DNA day− 1) and both declined over 22 h. This investigation suggests rapid growth combines growth efficiency and compensatory energy partitioning. This accommodates the ontogenetic and phylogenetic standpoints imposed by energy budget limitations.