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The Journal of Experimental Biology 204, 4353-4360 (2001)
© 2001 The Company of Biologists Limited

Complete suppression of protein synthesis during anoxia with no post-anoxia protein synthesis debt in the red-eared slider turtle Trachemys scripta elegans

Keiron P. P. Fraser^1,*, Dominic F. Houlihan¹, Peter L. Lutz², Sandra Leone-Kabler², Liscia Manuel² and James G. Brechin¹

¹ Department of Zoology, University of Aberdeen, Tillydrone Avenue, Aberdeen AB24 3TZ, UK and
² Department of Biological Sciences, Florida Atlantic University, Boca Raton, FL 33141, USA

*Present address: Biological Sciences Division, British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK (e-mail: kppf{at}pcmail.nerc-bas.ac.uk)

Accepted 1 October 2001

Two previous studies of the effects of anoxia on protein synthesis in anoxia-tolerant turtles (Trachemys scripta elegans, Chrysemys picta bellii) have generated opposing results. Using the flooding-dose method, we measured the rate of protein synthesis following injection and incorporation of a large dose of radiolabelled phenylalanine to resolve the question of whether anoxia results in a downregulation of protein synthesis. After 1 h of anoxia, levels of protein-incorporated radiolabel indicated that protein synthesis rates in the intestine, heart, liver, brain, muscle and lungs were not significantly different from those of normoxic controls. However, from 1 to 6 h of anoxia, quantities of protein-incorporated radiolabel did not increase, suggesting that protein synthesis had ceased or had decreased below a measurable level. There was also no significant post-anoxia increase in protein synthesis rates above normoxic control levels during 3 h of recovery from anoxia. RNA-to-protein ratios did not change significantly in any tissue except the heart, in which RNA levels decreased below normoxic control levels after 6 h of anoxia. Except in the heart, downregulation of protein synthesis during anoxia does not appear to be mediated by changes in tissue RNA concentration.

Key words: RNA, metabolic downregulation, facultative anaerobe, turtle, red-eared slider, Trachemys scripta elegans.

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