TY - JOUR
T1 - Net superoxide levels
T2 - Steeper increase with activity in cooler female and hotter male lizards
AU - Ballen, Cissy
AU - Healey, Mo
AU - Wilson, Mark
AU - Tobler, Michael
AU - Wapstra, Erik
AU - Olsson, Mats
PY - 2012/3
Y1 - 2012/3
N2 - 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.
AB - 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.
KW - Lizard
KW - Reactive oxygen species
KW - Thermoregulation
UR - http://www.scopus.com/inward/record.url?scp=84863418656&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84863418656&partnerID=8YFLogxK
U2 - 10.1242/jeb.062257
DO - 10.1242/jeb.062257
M3 - Article
C2 - 22323195
AN - SCOPUS:84863418656
SN - 0022-0949
VL - 215
SP - 731
EP - 735
JO - Journal of Experimental Biology
JF - Journal of Experimental Biology
IS - 5
ER -