Selective changes in the protein-turnover rates and nature of growth induced in trout liver by long-term starvation followed by re-feeding |
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Authors: | Peragón Juan Barroso Juan B García-Salguero Leticia Aranda Fermín de la Higuera Manuel Lupiáñez José A |
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Institution: | (1) Department of Biochemistry and Molecular Biology, Centre of Biological Sciences, University of Granada, Granada, E-1800, Spain;(2) Department of Experimental Biology, Biochemistry and Molecular Biology Section, University of Jaén, E-2307 Jaén, Spain;(3) Department of Animal Biology and Ecology, Centre of Biological Sciences, University of Granada, Granada, E-1800, Spain |
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Abstract: | We report upon the effects of a cycle of long-term starvation followed by re-feeding on the liver-protein turnover rates and nature of protein growth in the rainbow trout (Oncorhynchus mykiss). We determined the protein-turnover rate and its relationship with the nucleic-acid concentrations in the livers of juvenile trout starved for 70 days and then re-fed for 9 days. During starvation the total hepatic-protein and RNA contents decreased significantly and the absolute protein-synthesis rate (AS) also fell, whilst the fractional protein-synthesis rate (KS) remained unchanged and the fractional protein-degradation rate (KD) increased significantly. Total DNA content, an indicator of hyperplasia, and the protein:DNA ratio, an indicator of hypertrophy, both fell considerably. After re-feeding for 9 days the protein-accumulation rates (KG, AG) rose sharply, as did KS, AS, KD, protein-synthesis efficiency (KRNA) and the protein-synthesis rate/DNA unit (KDNA). The total hepatic protein and RNA contents increased but still remained below the control values. The protein:DNA and RNA:DNA ratios increased significantly compared to starved fish. These changes demonstrate the high response capacity of the protein-turnover rates in trout liver upon re-feeding after long-term starvation. Upon re-feeding hypertrophic growth increased considerably whilst hyperplasia remained at starvation levels. |
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Keywords: | hyperplasia hypertrophy liver nucleic-acid concentration protein-growth rate protein-turnover rate rainbow trout (Oncorhynchus mykiss) starvation/re-feeding cycle |
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