TY - JOUR
T1 - Fasting triggers hypothermia, and ambient temperature modulates its depth in Japanese quail Coturnix japonica
AU - Ben-Hamo, Miriam
AU - Pinshow, Berry
AU - McCue, Marshall D.
AU - McWilliams, Scott R.
AU - Bauchinger, Ulf
N1 - Funding Information:
This project was funded by US–Israel Binational Science Foundation Grant 2005119 to B.P. and S.R.M. M.D.M. and U.B. were funded by a Blaustein fellowship. We would like to thank Michał Wojciechowski, Justin Boyles and an anonymous reviewer for their insightful comments that helped improve our original manuscript. We would also like to thank Andrew McKechnie and Blair Wolf for allowing us to use their energetic model for hypothermia, and Ortal Mizrahy, Sarah Aamidor, Oren Amitai, and Sarah Hasslinger-Frey who helped care for the birds prior to and during the experiments. This study was done under authorization number BGU-R-08-2009 to BP of the Animal Care and Ethics Committee of Ben-Gurion University. This is paper #636 of the Mitrani Department of Desert Ecology.
PY - 2010/1/1
Y1 - 2010/1/1
N2 - We tested three hypotheses regarding the cues that elicit facultative hypothermia in Japanese quail (Coturnix japonica): H1) Ambient temperature (Ta), alone, influences the onset and depth of hypothermia; H2) Fasting, alone, influences the onset and depth of hypothermia; H3) Ta acts synergistically with fasting to shape the use of hypothermia. Eight quail were maintained within their thermoneutral zone (TNZ) at 32.6 ± 0.2 °C, and eight below their lower critical temperature (Tlc) at 12.7 ± 3.0 °C. All quail entered hypothermia upon food deprivation, even quail kept within their TNZ. Body temperature (Tb) decreased more (38.36 ± 0.53 °C vs. 39.57 ± 0.57 °C), body mass (mb) loss was greater (21.0 ± 7.20 g vs.12.8 ± 2.62 g), and the energy saved by using hypothermia was greater (25.18-45.01% vs. 7.98-28.06%) in low the Ta treatment than in TNZ treatment. Interestingly, the depth of hypothermia was positively correlated with mb loss in the low Ta treatment, but not in TNZ treatment. Our data support H3, that both thermoregulatory costs and body energy reserves are proximate cues for entry into hypothermia in quail. This outcome is not surprising below the Tlc. However, the quail kept at their TNZ also responded to food deprivation by entering hypothermia with no apparent dependence on mb loss. Therefore inputs, other than thermoregulatory costs and body condition, must serve as cues to enter hypothermia. Consequently, we address the role that tissue sparing may play in the physiological 'decision' to employ hypothermia.
AB - We tested three hypotheses regarding the cues that elicit facultative hypothermia in Japanese quail (Coturnix japonica): H1) Ambient temperature (Ta), alone, influences the onset and depth of hypothermia; H2) Fasting, alone, influences the onset and depth of hypothermia; H3) Ta acts synergistically with fasting to shape the use of hypothermia. Eight quail were maintained within their thermoneutral zone (TNZ) at 32.6 ± 0.2 °C, and eight below their lower critical temperature (Tlc) at 12.7 ± 3.0 °C. All quail entered hypothermia upon food deprivation, even quail kept within their TNZ. Body temperature (Tb) decreased more (38.36 ± 0.53 °C vs. 39.57 ± 0.57 °C), body mass (mb) loss was greater (21.0 ± 7.20 g vs.12.8 ± 2.62 g), and the energy saved by using hypothermia was greater (25.18-45.01% vs. 7.98-28.06%) in low the Ta treatment than in TNZ treatment. Interestingly, the depth of hypothermia was positively correlated with mb loss in the low Ta treatment, but not in TNZ treatment. Our data support H3, that both thermoregulatory costs and body energy reserves are proximate cues for entry into hypothermia in quail. This outcome is not surprising below the Tlc. However, the quail kept at their TNZ also responded to food deprivation by entering hypothermia with no apparent dependence on mb loss. Therefore inputs, other than thermoregulatory costs and body condition, must serve as cues to enter hypothermia. Consequently, we address the role that tissue sparing may play in the physiological 'decision' to employ hypothermia.
KW - Aves
KW - Body mass
KW - Body temperature
KW - Energetics
KW - Homeothermy
KW - Metabolic rate
KW - Temperature regulation
UR - http://www.scopus.com/inward/record.url?scp=77549088149&partnerID=8YFLogxK
U2 - 10.1016/j.cbpa.2009.12.020
DO - 10.1016/j.cbpa.2009.12.020
M3 - Article
AN - SCOPUS:77549088149
SN - 1095-6433
VL - 156
SP - 84
EP - 91
JO - Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology
JF - Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology
IS - 1
ER -