Hypoxia depresses CYP1A induction and enhances DNA damage, but has minimal effects on antioxidant responses in sheepshead minnow (Cyprinodon variegatus) larvae exposed to dispersed crude oil.
The growing incidence of hypoxic regions in coastal areas receiving high volumes of anthropogenic discharges requires more focused risk assessment of multiple stressors. One area needing further study is the combined effect of hypoxia and oil exposure. This study examined the short-term sublethal effects of co-exposure to hypoxia and water accommodated fractions (WAF) and chemically enhanced WAFs (CEWAFs) of Southern Louisiana Crude oil on detoxification, antioxidant defenses and genotoxicity in early life stage sheepshead minnow (Cyprinodon variegatus). CYP1A induction (evaluated by measuring EROD activity), activity of a number of key antioxidant enzymes (GST, GR, GPx, SOD, CAT, and GCL), levels of antioxidants (tGSH, GSH, and GSSG), evidence of lipid peroxidation (evaluated using the TBARS assay), and DNA damage (evaluated using the comet assay) provided a broad assessment of responses. Contaminant detoxification pathways induced by oil exposure were inhibited by co-exposure to hypoxia, indicating a maladaptive response. The interactive effects of oil and hypoxia on antioxidant defenses were mixed, but generally indicated less pronounced alterations, with significant increases in lipid peroxidation not observed. Hypoxia significantly enhanced DNA damage induced by oil exposure indicating the potential for significant deleterious effects post exposure. This study demonstrates the importance of considering hypoxia as an enhanced risk factor in assessing the effects of contaminants in areas where seasonal hypoxia may be prevalent.
School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, 11790, New York, United States.
Subham
S
Dasgupta
Nicholas School of Environment, Duke University, Durham, NC 27708, United States.
Richard T
RT
DiGiulio
School of Engineering & Applied Science, Yale University, New Haven, CT 06520, United States.
Brian D
BD
Drollette
School of Engineering & Applied Science, Yale University, New Haven, CT 06520, United States.
Desire
D
L Plata
School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, 11790, New York, United States.
Bruce J
BJ
Brownawell
School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, 11790, New York, United States. Electronic address: anne.mcelroy@stonybrook.edu.
Anne E
AE
McElroy
D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D020552:Comet Assay; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism*; D004249:DNA Damage / Q000187:drug effects* / Q000502:physiology; D000860:Hypoxia / Q000503:physiopathology*; D008658:Inactivation, Metabolic; D007695:Killifishes / Q000502:physiology*; D007814:Larva / Q000187:drug effects / Q000502:physiology; D015227:Lipid Peroxidation / Q000187:drug effects / Q000502:physiology; D010578:Petroleum / Q000633:toxicity*; D013312:Stress, Physiological / Q000187:drug effects / Q000502:physiology; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D000975:Antioxidants; D015415:Biomarkers; D010578:Petroleum; D014874:Water Pollutants, Chemical; D019363:Cytochrome P-450 CYP1A1
Comet assay; Fish larvae; Hypoxia; Metabolism; Oil; ROS