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Effects of Temperature Extremes on Protein Synthesis in Liver of Toadfish, Opsanus tau, in vivo

Audrey E. V. Haschemeyer and Rita W. Mathews
Biological Bulletin
Vol. 162, No. 1 (Feb., 1982), pp. 18-27
DOI: 10.2307/1540966
Stable URL: http://www.jstor.org/stable/1540966
Page Count: 10
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Effects of Temperature Extremes on Protein Synthesis in Liver of Toadfish, Opsanus tau, in vivo
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Abstract

Amino acid incorporation and polypeptide chain elongation rates were determined in toadfish at the upper and lower ends of their range of temperature tolerance. The method was based on pulse injection of radioactive amino acids into the hepatic portal vein and analysis of ribosome-bound and completed chains at various times after injection. Elongation rates at low temperatures were obtained from the rate of completion and release of polypeptide chains pre-labeled at 20°C. Average polypeptide chain assembly time at 4°C was 6 h; that at 37°C was 1 min. Comparison with rates of total protein synthesis obtained in previous studies indicate a coordinated slowing of all protein synthetic reactions at low temperatures. A 10-fold decline in elongation rate from 7°C to 4°C suggests a specific temperature sensitivity in elongation factors or in formation of aminoacyl-tRNA. At high temperatures (32°-40°C) protein synthetic reactions show a loss of coordination, with elongation rate increasing normally ( Q10 about 2) while amino acid incorporation declines. The results indicate a close correlation between behavior of the protein synthetic system and observations on temperature tolerance and winter dormancy in this species.

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