Mitochondrial Gene Responses to Low Oxygen Stress in Turtle Organs

Abstract

Abstract Effects of anoxic submergence (1, 5, and 20 h at 5 C) and subsequent aerobic recovery (1, 5, and 24 h at 5 C) on gene expression in organs of the anoxia-tolerant turtle Trachemys scripta elegans were examined. Differential screening of a cDNA library from brains of 20 h anoxia-exposed turtles selected two clones from Anoxic Turtle Brains, ATB1.22 and ATB2.4, as potentially up-regulated by anoxia. The insert of clone ATB1.22 had a single open reading frame that encoded a protein of 376 amino acids which was identified as mitochondrial cytochrome b (CYTb); the sequence was 99% complete and showed 72% of nucleotide residues and 76% of amino acid residues identical to those in the human sequences. Clone ATB2.4 contained an open reading frame encoding 322 amino acids with 65% nucleotide and 63% amino acid sequence identity with another mitochondrial protein, NADH-μbiquinone oxidoreductase subunit 4 (ND4). Northern blot analysis of the time course of gene expression in five organs during 20 h anoxia ex...