Sammendrag
Arctic animals utilize periods with high food availability for feeding and
lipid deposition, whereas they rely on stored lipids during unfavorable
periods. Hence, many arctic inhabitants exhibit profound seasonal cycles of
fattening and emaciation. In the Arctic, feeding is associated with fat
deposition and contaminant accumulation. When lipids are mobilized,
accumulated contaminants are released into the circulation. Consequently,
blood contaminant concentrations may increase markedly and result in a
redistribution of the contaminant(s) from "insensitive", adipose tissues to
sensitive organs, and increased contaminant bioavailability. Such variations
complicate interpretations of pollutant toxicity, both in effect studies and
in monitoring programs, and remains an important future research area. In the
present study, we will use arctic fox (Alopex lagopus) as a model species for
investigating tissue distribution and bioavailability of organochlorine
contaminants (OCs) in relation to natural variations in lipid status (field
study). These data will be supplemented and validated through a contamination
study with blue fox (A. lagopus), where the seasonal changes in lipid status
of wild fox are simulated in the laboratory. In both the field and laboratory
study, possible effects of OCs on steroid hormone synthesis, and plasma levels
of hormones, vitamin E and retinol will also be assessed.
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Vitenskapelig sammendrag
Arctic animals utilize periods with high food availability for feeding and
lipid deposition, whereas they rely on stored lipids during unfavorable
periods. Hence, many arctic inhabitants exhibit profound seasonal cycles of
fattening and emaciation. In the Arctic, feeding is associated with fat
deposition and contaminant accumulation. When lipids are mobilized,
accumulated contaminants are released into the circulation. Consequently,
blood contaminant concentrations may increase markedly and result in a
redistribution of the contaminant(s) from "insensitive", adipose tissues to
sensitive organs, and increased contaminant bioavailability. Such variations
complicate interpretations of pollutant toxicity, both in effect studies and
in monitoring programs, and remains an important future research area. In the
present study, we will use arctic fox (Alopex lagopus) as a model species for
investigating tissue distribution and bioavailability of organochlorine
contaminants (OCs) in relation to natural variations in lipid status (field
study). These data will be supplemented and validated through a contamination
study with blue fox (A. lagopus), where the seasonal changes in lipid status
of wild fox are simulated in the laboratory. In both the field and laboratory
study, possible effects of OCs on steroid hormone synthesis, and plasma levels
of hormones, vitamin E and retinol will also be assessed.
Vis fullstendig beskrivelse