Protein synthesis, nitrogen excretion and long-term growth of juvenile Pleuronectes flesus |
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Authors: | C G Carter D F Houlihan S F Owen |
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Institution: | School of Aquaculture, University of Tasmania, P.O. Box 1214, Launceston, Tasmania 7250, Australia;Department of Zoology, University of Aberdeen, Tillydrone Avenue, Aberdeen, AB9 2TN, Scotland, U.K. |
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Abstract: | This study aimed to measure protein synthesis using a stable isotope method, investigate protein-nitrogen flux in a flatfish Pleuronectes flesus , and use the data to test the hypothesis that individual differences in growth efficiency were related to individual differences in protein-nitrogen flux mediated through differences in protein synthesis and degradation. Three measurements of protein-nitrogen flux via consumption, protein synthesis and nitrogenous excretion were made for individual flounder during a 212-day period and fractional rates of protein-nitrogen flux were scaled for a 50–g flounder to provide mean values for protein consumption (2·11 ± 0·21% day?1), protein synthesis (2·08±0·23% day?1), protein growth (0·71±0·06% day?1) and protein degradation (1·37±0·24% day?1). Mean rates of nitrogenous excretion were 0·142 mg N g?1 day?1 and 0·047 mg N g?1 day?1 for ammonia and urea, respectively. Individual flounder had different protein growth efficiencies and this was correlated negatively and significantly with mean rates of protein synthesis ( r - 0·70; P <0·05) and degradation ( r - 0·67; P < 0·05) and correlated positively and significantly with the efficiency of retaining synthesized protein ( r +0·63, P <0·05). This supported the proposed hypothesis that flounder which grow more efficiently achieve this through adopting a low protein turnover strategy. |
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Keywords: | flounder protein synthesis stable isotope growth efficiency excretion |
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