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

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

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

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 4h versus 12h, 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.

Original languageEnglish (US)
Pages (from-to)731-735
Number of pages5
JournalJournal of Experimental Biology
Volume215
Issue number5
DOIs
StatePublished - Mar 2012

Keywords

  • Lizard
  • Reactive oxygen species
  • Thermoregulation

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