Changes in mitochondrial gene and protein expression in grass shrimp, Palaemonetes pugio, exposed to chronic hypoxia.
Spatial and temporal increases of hypoxia in estuaries are of major environmental concern. Since mitochondria consume most of the oxygen in the cell, we examined the potential role of mitochondrial gene and protein expression in adaptation to chronic hypoxia in the grass shrimp Palaemonetes pugio. Grass shrimp were exposed to DO levels slightly above and below the critical pO(2), 1.8 mg/L, for P. pugio, and hypoxia-induced alterations in gene expression were screened using custom cDNA macroarrays. Mitochondrial gene expression was not affected by exposure to moderate hypoxia (2.5mg/L DO). However, chronic exposure to severe hypoxia (1.5mg/L DO) for 7 days resulted in an increase of transcription of genes present in the mitochondrial genome (including 16S rRNA and Ccox 1), together with up-regulation of genes involved in Fe/heme metabolism. This pattern was completely reversed by day 14, when a significant down-regulation of these genes was observed. Separating mitochondrial proteins in two dimensions by IEF and reverse phase chromatography, followed by LC/MS/MS of differentially expressed proteins, showed cytochrome c oxidase subunit 2, encoded by Ccox 2, was down-regulated after 12d exposure to severe hypoxia. It appears therefore that decreases in mitochondrial Ccox gene transcription result in decreased mitochondrial Ccox protein synthesis. These results suggest that mitochondrial genes and proteins show promise as molecular indicators of exposure to hypoxia.
Brouwer
Marius
M
Department of Coastal Sciences, The University of Southern Mississippi, PO Box 7000, Ocean Springs, MS 39566, USA. marius.brouwer@usm.edu
Brown-Peterson
Nancy J
NJ
Hoexum-Brouwer
Thea
T
Manning
Steve
S
Denslow
Nancy
N
D000693:Anaerobiosis / Q000502:physiology; D000818:Animals; D005786:Gene Expression Regulation; D050259:Genes, Mitochondrial / Q000235:genetics*; D024101:Mitochondrial Proteins / Q000235:genetics*; D010100:Oxygen / Q000378:metabolism* / Q000494:pharmacology; D033541:Palaemonidae / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D013997:Time Factors
D024101:Mitochondrial Proteins; D010100:Oxygen