A novel RNA species from the turtle mitochondrial genome: induction and regulation of transcription and processing under anoxic and freezing stresses.
The present study identifies a previously cloned cDNA, pBTaR914, as homologous to the mitochondrial WANCY (tryptophan, alanine, asparagine, cysteine, and tyrosine) tRNA gene cluster. This cDNA clone has a 304-bp sequence and its homologue, pBTaR09, has a 158-bp sequence with a long poly(A)+ tail (more than 60 adenosines). RNA blotting analysis using pBTaR914 probe against the total RNA from the tissues of adult and hatchling turtles revealed five bands: 540, 1800, 2200, 3200, and 3900 nucleotides (nt). The 540-nt transcript is considered to be an intact mtRNA unit from a novel mtDNA gene designated WANCYHP that overlaps the WANCY tRNA gene cluster region. This transcript was highly induced by both anoxic and freezing stresses in turtle heart. The other transcripts are considered to be the processed intermediates of mtRNA transcripts with WANCYHP sequence. All these transcripts were differentially regulated by anoxia and freezing in different organs. The data suggest that mtRNA processing is sensitive to regulation by external stresses, oxygen deprivation, and freezing. Furthermore, the fact that the WANCYHP transcript is highly induced during anoxic exposure suggests that it may play an important role in the regulation of mitochondrial activities to coordinate the physiological adaptation to anoxia.
Cai
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Institute of Biochemistry, Carleton University, Ottawa, ON, Canada.
Storey
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D000222:Adaptation, Physiological / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics*; D004734:Energy Metabolism / Q000235:genetics; D005615:Freezing; D005786:Gene Expression Regulation; D007035:Hypothermia / Q000150:complications / Q000235:genetics / Q000378:metabolism*; D000860:Hypoxia / Q000235:genetics / Q000378:metabolism*; D007511:Ischemia / Q000209:etiology / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000502:physiology; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism; D009928:Organ Specificity; D012343:RNA, Transfer / Q000235:genetics*; D013312:Stress, Physiological / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D014426:Turtles / Q000235:genetics* / Q000502:physiology
D018076:DNA, Complementary; D004272:DNA, Mitochondrial; D012343:RNA, Transfer