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Net superoxide levels: steeper increase with activity in cooler female and hotter male lizards

Author

  • Cissy Ballen
  • Mo Healey
  • Mark Wilson
  • Michael Tobler
  • Erik Wapstra
  • Mats Olsson

Summary, in English

Ectotherms increase their body temperature in response to ambient heat, thereby elevating their metabolic rate. An often inferred consequence of this is an overall upregulation of gene expression and energetic expenditure, and a concomitant increased production of reactive oxygen species (e.g. superoxide) and, perhaps, a shortened lifespan. However, recent work shows that this may be a superficial interpretation. For example, sometimes a reduced temperature may in fact trigger up-regulation of gene expression. We studied temperature and associated activity effects in male and female Australian painted dragon lizards (Ctenophorus pictus) by allowing the lizards to bask for 4 h versus 12 h, and scoring their associated activity (inactive versus active basking and foraging). As predicted, long-basking lizards (hereafter ‘hot’) showed heightened activity in both sexes, with a more pronounced effect in females. We then tested for sex-specific effects of basking treatment and activity levels on the increase in net levels of superoxide. In males, short-baskers (hereafter ‘cold’) had significantly more rapidly decreasing levels of superoxide per unit increasing activity than hot males. In females, however, superoxide levels increased faster with increasing activity in the cold than in the hot basking treatment, and females earlier in the ovarian cycle had lower superoxide levels than females closer to ovulation. In short, males and females differ in how their levels of reactive oxygen species change with temperature-triggered activity.

Publishing year

2012

Language

English

Pages

731-735

Publication/Series

Journal of Experimental Biology

Volume

215

Issue

16

Document type

Journal article

Publisher

The Company of Biologists Ltd

Topic

  • Biological Sciences

Keywords

  • reactive oxygen species
  • thermoregulation
  • lizard

Status

Published

Project

  • Immunoecology

Research group

  • Molecular Ecology and Evolution Lab

ISBN/ISSN/Other

  • ISSN: 1477-9145