Use of Mixed-Function Oxygenases to Monitor Contaminant Exposure in Wildlife

Abstract

This overview examines the utility of mixed-function oxygenase (MFO) enzymes as a bioeffects monitor for wildlife (amphibians, reptiles, birds and mammals) i n view of their widespread use as indicators of contaminant exposure in aquatic invertebrates and fish. Phylogenetic trends i n MFO activity, toxicological implications of induction and the relationship between contaminant exposure and MFO activity are discussed. Field studies using avian embryos and hatchlings suggest that MFO induction has utility for documenting contaminant exposure; however, findings in adult birds and mammals are equivocal. Age, sex and season are sources of variation that require consideration when undertaking field trials. Further understanding of MFO inducibility among species and application of recently developed analytical techniques including quantification of specific cytochrome P-450 isozymes are warranted.

Reproduction and environmental contamination in tree swallows nesting in the Fox River Drainage and Green Bay, Wisconsin, USA

“…Limited data are available on the relationship between P450 monooxygenases in wild avian species [43], although the database is growing. Monooxygenases are part of the avian detoxication system and are induced when exposed to certain chemicals [44].…”

Effects‐based marine ecological risk assessment at a polychlorinated biphenyl‐contaminated site in Saglek, Labrador, Canada

“…These latter indicators include fish body condition (condition factor), lipid content, relative liver mass (hepatosomatic index), and activity of a cytochrome P450 1A (CYP1A) enzyme (ethoxyresorufin-Odeethylase [EROD]) in sculpin liver tissue. Condition measurements and activity of inducible liver enzymes, such as mixed function oxygenase (MFO or CYP1A), have been used in previous studies as overall indicators of exposure to PCBs and fish health [32]. Induction of MFO enzymes can alter the metabolism of important compounds such as vitamins and steroid hormones, which may have secondary effects on development, growth, and reproduction.…”

“…Chem. 32,2013transferred through the food web via the diet, biomagnifying to higher concentrations with each successive step in the food web [16]. Thus, the extent to which organisms are associated with contaminated sediment, either directly or indirectly (via the food web), is important in determining PCB exposure, as is the trophic level of the organism.…”

Hepatic cytochrome P450 activity and pollutant concentrations in paradise shelducks and southern black-backed gulls in the South Island of New Zealand

“…In wildlife, studies on CYPs have focussed on CYP1A induction as a biomarker of exposure to harmful hydrocarbons, typically polychlorinated dibenzo-p-dioxin/furans (PCDD/Fs) and polychlorinated biphenyls (PCBs) (Hahn 2002). Although the sensitivity of this aryl hydrocarbon receptor (AhR)-mediated response and the ubiquity of AhR agonists in the environment (Rattner et al 1989) may justify this bias, there is a need to recognise the role of other CYPs to understand how different species respond to environmental pollutants (Rifkind 2006). The CYP enzyme system is well-conserved yet exhibits many species-specific properties (Hahn 2002;Walker 1998).…”