Effects of cyclic hypoxia on gene expression and reproduction in a grass shrimp, Palaemonetes pugio.
Cyclic changes in dissolved oxygen occur naturally in shallow estuarine systems, yet little is known about the adaptations and responses of estuarine organisms to cyclic hypoxia. Here we examine the responses of Palaemonetes pugio, a species of grass shrimp, to cyclic hypoxia (1.5-8 mg/l dissolved oxygen; 4.20-22.42 kPa) at both the molecular and organismal levels. We measured alterations in gene expression in hepatopancreas tissue of female grass shrimp using custom cDNA macroarrays. After short-term (3-d) exposure to cyclic hypoxia, mitochondrial manganese superoxide dismutase (MnSOD) was upregulated and 70-kd heat shock proteins (HSP70) were downregulated. After 7-d exposure, nuclear genes encoding mitochondrial proteins (ribosomal protein S2, ATP synthase, very-long-chain specific acyl-CoA dehydrogenase [VLCAD]) were downregulated, whereas mitochondrial phosphoenol pyruvate carboxykinase (PEP Cbk) was upregulated. After 14 d, vitellogenin and apolipoprotein A1 were upregulated. Taken together, these changes suggest a shift in metabolism toward gluconeogenesis and lipid export. Long-term (77-d) exposure to hypoxia showed that profiles of gene expression returned to pre-exposure levels. These molecular responses differ markedly from those induced by chronic hypoxia. At the organismal level, cyclic hypoxia reduces the number of broods and eggs a female can produce. Demographic analysis showed a lower estimated rate of population growth in grass shrimp exposed to both continuous and short-term cyclic hypoxia, suggesting population-level impacts on grass shrimp.
Brown-Peterson
Nancy J
NJ
Department of Coastal Sciences, The University of Southern Mississippi, 703 East Beach Dr., Ocean Springs, Mississippi 39564, USA.
Manning
C Steve
CS
Patel
Vishal
V
Denslow
Nancy D
ND
Brouwer
Marius
M
D000818:Animals; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000502:physiology*; D000860:Hypoxia / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D033541:Palaemonidae / Q000378:metabolism*; D010507:Periodicity; D012098:Reproduction / Q000502:physiology
D010100:Oxygen