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J Neurochem. 2009 Jun;109(5):1413-26. doi: 10.1111/j.1471-4159.2009.06068.x. Epub 2009 Mar 26.

Modulation of stress proteins and apoptotic regulators in the anoxia tolerant turtle brain.

Author information

1
Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida 33431, USA. skesaraj@fau.edu

Abstract

Freshwater turtles survive prolonged anoxia and reoxygenation without overt brain damage by well-described physiological processes, but little work has been done to investigate the molecular changes associated with anoxic survival. We examined stress proteins and apoptotic regulators in the turtle during early (1 h) and long-term anoxia (4, 24 h) and reoxygenation. Western blot analyses showed changes within the first hour of anoxia; multiple stress proteins (Hsp72, Grp94, Hsp60, Hsp27, and HO-1) increased while apoptotic regulators (Bcl-2 and Bax) decreased. Levels of the ER stress protein Grp78 were unchanged. Stress proteins remained elevated in long-term anoxia while the Bcl-2/Bax ratio was unaltered. No changes in cleaved caspase 3 levels were observed during anoxia while apoptosis inducing factor increased significantly. Furthermore, we found no evidence for the anoxic translocation of Bax from the cytosol to mitochondria, nor movement of apoptosis inducing factor between the mitochondria and nucleus. Reoxygenation did not lead to further increases in stress proteins or apoptotic regulators except for HO-1. The apparent protection against cell damage was corroborated with immunohistochemistry, which indicated no overt damage in the turtle brain subjected to anoxia and reoxygenation. The results suggest that molecular adaptations enhance pro-survival mechanisms and suppress apoptotic pathways to confer anoxia tolerance in freshwater turtles.

PMID:
19476552
PMCID:
PMC2735444
DOI:
10.1111/j.1471-4159.2009.06068.x
[Indexed for MEDLINE]
Free PMC Article

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