Publication: Life Science Weekly
Date: Tuesday November 1st, 2011
Page: 1094
Summary
Levels of positive regulators of Cdk activity (Cdc25 type A and C) were significantly reduced in both tissues under both stresses, whereas negative regulators of Cdk activity (p16(INK4a) and p27(KIP1)) increased significantly in liver under both anoxia and dehydration stress (but not in muscle),” wrote R. Roufayel and colleagues, Carleton University (see also ).
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According to the authors of recent research from Ottawa, Canada, “The wood frog (Rana sylvatica) exhibits a well-developed natural anoxia and dehydration tolerance. The degree of stress tolerance depends on numerous biochemical adaptations, including stress-induced hypometabolism that helps to preserve long-term viability by reducing ATP demand.”
“We hypothesized that the mechanisms involved in cell cycle control could act to aid in the establishment of the hypometabolic state required for stress survival. Selected proteins involved in the proliferation of cells were evaluated using immunoblotting in liver and skeletal muscle of wood frogs comparing controls with animals subjected to either 24-hr anoxia exposure under a nitrogen gas atmosphere or dehydration to 40% of total body water lost (all at 5 degrees C). Levels of cyclins (type A, B, D, and E) decreased significantly under both stresses in liver and skeletal muscle. Similar reductions were seen for Cyclin-dependant kinases (Cdk) types 2, 4, and 6 in both liver and skeletal muscle; however, an increase in the relative amount of phosphorylated inactive p-Cdk (Thr14/Tyr15) was observed in liver under both stresses. Levels of positive regulators of Cdk activity (Cdc25 type A and C) were significantly reduced in both tissues under both stresses, whereas negative regulators of Cdk activity (p16(INK4a) and p27(KIP1)) increased significantly in liver under both anoxia and dehydration stress (but not in muscle),” wrote R. Roufayel and colleagues, Carleton University (see also ).
The researchers concluded: “This study provides the first report of differential regulation of cell cycle components in an anoxia and dehydration tolerant vertebrate, the wood frog, suggesting that cell cycle suppression is an active part of stress resistance and life extension in hypometabolic states. J. Exp. Zool. 315:487-494, 2011.”
Roufayel and colleagues published their study in the Journal of Experimental Zoology Part A-Ecological Genetics and Physiology (Regulation of Cell Cycle Components During Exposure to Anoxia or Dehydration Stress in the Wood Frog, Rana sylvatica. Journal of Experimental Zoology Part A-Ecological Genetics and Physiology, 2011;315A(8):487-494).
For additional information, contact R. Roufayel, Carleton University, Institute Biochemistry, Ottawa, ON K1S 5B6, Canada.
Publisher contact information for the Journal of Experimental Zoology Part A-Ecological Genetics and Physiology is: Wiley-Blackwell, Commerce Place, 350 Main St., Malden 02148, MA, USA.
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