Protein Biosynthesis In Liver Research Articles

Evaluating the Nutritional Condition of an Indian Climbing Perch, Anabas Testudineus Fingerlings by the RNA/DNA, Ca/P Ratio and Protein Bio-Synthesis in Liver and Muscle

Early fingerlings of Anabas testudineus were nurtured in the laboratory for six weeks under altered nutritional status (different dietary protein level and source) and feeding regimes (ad libitum, ‘limited’, and ‘starvation’ intervals). Their RNA/DNA, Ca/P ratios and protein biosynthesis were determined with highly sensitive fluorescence technique, spectrophotometer and liquid scintillation system respectively. Well-fed early fingerlings (4-6 weeks age group) having higher RNA/DNA (2.11), Ca/P (1.82) ratio and protein biosynthesis rates both in muscle and liver have significantly differs from fingerlings with ‘limited’ food supply and 'starvation' intervals. Rate of protein biosynthesis >244.33 & 603.24 in muscle & liver respectively (count per minute mg protein-1) when compared with well-fed fingerlings and reared under 'limited' food supply and 'starvation' intervals. At ‘starvation’ interval no significant differences were recorded due to different diet treatment. However, fingerlings showed higher mortalities, decreased growth, RNA/DNA, Ca/P ratio and protein biosynthesis rate that may be caused by malnutrition. Fingerlings (early) sampled after 42 days in nearby areas during late monsoon (September) showed RNA/DNA, Ca/P ratio and protein biosynthesis rate were surprisingly low almost as low as ‘starved’ fingerlings, when judged on the basis of mean body weight as compared to well fed fish. It was also observed under microscope that some of these fingerlings were seriously affected by an intestinal disease and this may be due to the ingestion of unsuitable copepods. The low RNA/DNA, Ca/P ratio and protein biosynthesis rate in field samples and ‘starved’ fish are, therefore, interpreted as a sub-lethal result of this disease and malnutrition respectively.

Inhibition of protein biosynthesis in mouse liver by salicylate

The incorporation of l-[U- 14C]leucine and l-[ring-2- U14C]histidine into the protein of a post-mitochondrial supernatant fraction from mouse liver is inhibited by salicylate concentrations of 1 mM and above. The intraperitoneal injection of 500–600 mg/kg of salicylate in the mouse causes the following: an increase in the liver concentration of leucine but not that of histidine; a decrease in the incorporation of radioactive leucine and histidine into liver protein in vitro; an inhibition of the incorporation of radioactivity from intraperitoneally injected leucine into liver protein in vivo; a decrease in the transfer of α-aminoisobutyrate from the peritoneum to the blood but not from the circulation to the tissues and an inhibition of protein biosynthesis in the liver after the intravenous administration of radioactive leucine and histidine. It is concluded that salicylate interferes with protein synthesis in mouse liver both in vitro and in vivo.