Avian forms of cytochrome P450

Walker, C.H.

doi:10.1016/s0742-8413(98)10030-0

Cited by 38 publications

(32 citation statements)

References 33 publications

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“…The activity of the enzymes are often induced by pollutants in residential areas and environmental contaminants in animal habitats (Harris et al, 1998;Walker 1998;Whitlock 1999). Our data show that tire-leachate compounds in the habitat of Ae.…”

Section: Discussionmentioning

confidence: 73%

Induction of microsomal cytochrome P450s by tire‐leachate compounds, habitat components of Aedes albopictus mosquito larvae

Suwanchaichinda

Brattsten

2002

Arch Insect Biochem Physiol

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Benzothiazole (BZT) and its derivatives are the major leachate compounds of automobile tires, the principal breeding habitat of Aedes albopictus, particularly in the United States. Effects of the compounds on insecticide toxicity, and activities and expression of microsomal cytochrome P450s (P450s) in the mosquito larvae were examined. Mosquito larvae were more tolerant to carbaryl, rotenone, and temephos when they were pre-exposed to tire-leachate compounds, particularly BZT. There was no change in toxicity from the aldrin treatment by BZT. The effect of BZT was reversed when a P450 inhibitor, piperonyl butoxide, was applied in admixture with the insecticides. Microsomes from BZT-treated larvae had increased peroxidation activity of tetramethylbenzidine. This correlated with increased intensity of SDS-PAGE protein bands corresponding to molecular weights of 59 and 62 kD, which were detected as heme-containing proteins, a characteristic of P450s. The results suggest that BZT induces P450s, which detoxify insecticides and thus cause insecticide tolerance in the mosquito larvae. Arch.

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Section: Discussionmentioning

confidence: 73%

Induction of microsomal cytochrome P450s by tire‐leachate compounds, habitat components of Aedes albopictus mosquito larvae

Suwanchaichinda

Brattsten

2002

Arch Insect Biochem Physiol

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Section: Introductionmentioning

confidence: 99%

“…CYP isoforms are also involved in the first oxidative step of contaminant biotransformation (Walker, 1998). The presence and activity of CYP isoforms determine an organism's ability and capacity to biotransform contaminants and, thus, its contaminant levels and patterns (Murk et al, 1994;Walker, 1998). Based on PCB patterns in tissues, birds are suggested to eliminate congeners with chlorine (Cl) unsubstituted meta-para positions (through CYP2B/ 3A-like enzymes) to a higher extent than congeners with Cl-unsubstituted ortho-meta positions (through CYP1A-like enzymes) (Braune and Norstrom, 1989;Borlakoglu et al, 1990).…”

Section: Introductionmentioning

confidence: 99%

Bioaccumulation of PCBs in Arctic seabirds: influence of dietary exposure and congener biotransformation

Borgå¹,

Wolkers²,

Skaare³

et al. 2005

Environmental Pollution

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Four seabird species and their prey (zooplankton or fish) were collected in the Barents Sea to determine how dietary exposure, cytochrome P450 (CYP) enzyme activities and sex influenced their hepatic PCB concentrations and accumulation patterns. Five males and five females from each seabird species (little auk (Alle alle), Bru¨nnich's guillemot (Uria lomvia), black guillemot (Cepphus grylle) and black-legged kittiwake (Rissa tridactyla)) were analysed. PCB concentrations could not be explained directly by carbon source (d 15 N, migratory pattern, age) and contaminant metabolism. Contrary to previous studies, the PCB pattern differed among seabirds, with a higher proportion of persistent congeners (% of PCB-153, R PCB-153 ) in black-legged kittiwake than in auks. The PCB pattern also differed among auks, with little auk as the most efficient biotransformer (highest R PCB-153 values of persistent congeners). Based on high R PCB-153 values, Bru¨nnich's guillemot poorly metabolised ortho-meta-unsubstituted congeners, whereas black guillemot poorly metabolised meta-para unsubstituted congeners. Species-specific differences in PCB biotransformation were confirmed by metabolic indices, where PCB patterns in seabirds were adjusted for PCB pattern in prey. The relative contribution of ortho-meta-unsubstituted congeners to P PCBs decreased with increasing EROD activity. There were no differences in PCB concentrations, PCB patterns or cytochrome P450 enzyme activities between males and females. CYP P450 activities (CYP1A-and CYP2B/3A-like: EROD and testosterone 6b-hydroxylation, respectively) were low and did not correlate with concentrations of non-or mono-ortho Cl-substituted PCBs (NO-and MO-PCBs), or with total toxic equivalent concentrations (TEQs) for dioxin-like effects of NO-and MO-PCBs.

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“…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). For example, among the limited data available on substrate specificity of avian CYPs, that of CYP1A4 in the domestic chicken (Gallus gallus domesticus) is notably different from its mammalian counterpart, CYP1A1.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2008

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Cytochrome P450 (CYP) enzymes catalyse the oxidative metabolism of various xenobiotics including environmental pollutants. We investigated liver microsomal CYP marker activities in 60 paradise shelducks (Tadorna variegata; herbivore) and 77 southern black-backed gulls (Larus dominicanus; omnivore) collected at three sites with putatively different levels of pollution in the South Island of New Zealand. Ethoxyresorufin O-deethylase (EROD) activity was high in birds at an urban landfill site compared to those at a relatively pristine and an agricultural site. Analysis of p-nitrophenol hydroxylase and erythromycin demethylase activities indicated the presence of two additional CYP isoforms in shelducks but no additional form in gulls. Total polychlorinated biphenyl (PCB) concentrations (ranges: shelducks, 0.073-6.2; gulls, 8.2-330 ng/g wet weight) were high in landfill samples suggesting a link to EROD induction and, in landfill shelducks, EROD was independently associated with Hg and Pb concentration. PCB congener-specific assessments indicated the metabolism of at least two congeners (#28 and #74) is induced in shelducks. DDE concentrations (ranges: shelducks, 0.85-320; gulls, 44-4800 ng/g) were high in birds at the landfill and agricultural sites. Body weight tended to be lower in landfill birds, but whether this reflects the greater energetic demands of pollutant detoxification remains to be investigated.

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Avian forms of cytochrome P450

Cited by 38 publications

References 33 publications

Induction of microsomal cytochrome P450s by tire‐leachate compounds, habitat components of Aedes albopictus mosquito larvae

Induction of microsomal cytochrome P450s by tire‐leachate compounds, habitat components of Aedes albopictus mosquito larvae

Bioaccumulation of PCBs in Arctic seabirds: influence of dietary exposure and congener biotransformation

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

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