Modulation of Mixed-Function Oxidase Activity in Black-Headed Gulls Living in Anthropic Environments: Biochemical Acclimatization or Adaptation?

Abstract

This study was conducted to explore the role of the mixed-function oxidase (MFO) detoxication system in the "biochemical acclimatization" or adaptation of gulls to anthropic environments. In three different populations of black-headed gull (Larus ridibundus) feeding in a lagoon, in municipal and industrial landfills, MFO microsomal hepatic activities (aldrin epoxidase, 7-ethoxyresorufin-0-deethylase, NADPH-cytochrome c reductase, NADH-cytochrome c reductase, and NADH-ferricyanide reductase), microsomal a-naphthylacetate esterase activity, cytochrome P-450 forms, and chlorinated hydrocarbon residues were determined. Induction tests and in vitro comparative kinetics studies were completed between the different populations of gulls. The detoxicant activities of the MFO system were much higher in the landfill gulls, especially those of the industrial landfill, than in lagoon gulls. Lineweaver-Burk plots for aldrin epoxidase show an apparent K, four to five times lower in the gulls of the industrial landfill than in the other two populations.The origin of the potentiated detoxication activities in landfill gulls is investigated and the hypotheses of biochemical acclimatization and genetic adaptation are discussed.

Urbanization is associated with modifications in DNA methylation in a small passerine bird

“…Since the liver is a major site of lipid biosynthesis and metabolism, and transport of cholesterol and lipoproteins to and from other tissues, we would not necessarily expect to see the same patterns in the blood. (Fossi et al, 1991;Isaksson, 2010). In turn, increased oxidative stress could be the driver of accelerated erosion of telomeres (Reichert & Stier, 2017), as has been observed in urban bird nestlings (Salmón et al, 2016).…”

“…Oxidative stress is considered to be almost ubiquitous in underlying the negative effects of many pollutants and stressors. The urban environment abounds with pro‐oxidant‐generating pollutants, and pollutant‐induced oxidative stress has been demonstrated in urban birds (Fossi et al., 1991; Isaksson, 2010). In turn, increased oxidative stress could be the driver of accelerated erosion of telomeres (Reichert & Stier, 2017), as has been observed in urban bird nestlings (Salmón et al., 2016).…”

Transcriptome analysis of a wild bird reveals physiological responses to the urban environment

“…The environmental toxicological literature abounds with studies demonstrating oxidative stress induced by exposure to pollutants in both terrestrial and aquatic environments 45 50 . While there is evidence for pollutant-induced oxidative stress in urban birds, our knowledge concerning the impacts and capacity for modulating detoxification pathways in birds is limited 28 51 . Our results suggest that the expression of genes involved in metal detoxification pathways could be important in underlying the functional differences between urban and rural birds.…”

Hepatic ethoxyresorufin‐O‐deethylase activity and inducibility in wild populations of double‐crested cormorants (Phalacrocorax auritus)

“…The possibility that evolution of increased capacity for metabolism could occur in bird populations inhabiting contaminated environments has been raised previously [35,44,45]. This study represents the first attempt to examine this question through manipulative experiments with cultured avian hepatocytes, an approach that greatly reduces the number of individual birds needed to support statistically based conclusions.…”