Complete suppression of protein synthesis during anoxia with no post-anoxia protein synthesis debt in the red-eared slider turtle Trachemys scripta elegans.
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.
Fraser
K P
KP
Department of Zoology, University of Aberdeen, Tillydrone Avenue, Aberdeen AB24 3TZ, UK. kppf@pcmail.nerc-bas.ac.uk
Houlihan
D F
DF
Lutz
P L
PL
Leone-Kabler
S
S
Manuel
L
L
Brechin
J G
JG
D000818:Animals; D001921:Brain / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D008168:Lung / Q000378:metabolism; D009132:Muscles / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D010100:Oxygen / Q000008:administration & dosage*; D010649:Phenylalanine / Q000008:administration & dosage; D014176:Protein Biosynthesis; D012313:RNA / Q000032:analysis; D014316:Tritium; D014426:Turtles / Q000378:metabolism*
D014316:Tritium; D010649:Phenylalanine; D012313:RNA; D010100:Oxygen