Obligatory homeothermy of mesic adapted African striped mice, Rhabdomys pumilio, is governed by seasonal basal metabolism and year-round "thermogenic readiness" of brown adipose tissue.
J. Exp. Biol. 225:jeb243860 (2022)
Small mammals undergo thermoregulatory adjustments in response to changing environmental conditions. Whereas small heterothermic mammals can employ torpor to save energy in the cold, homeothermic species must increase heat production to defend normothermia through the recruitment of brown adipose tissue (BAT). Here, we studied thermoregulatory adaptation in an obligate homeotherm, the African striped mouse (Rhabdomys pumilio), captured from a subpopulation living in a mesic, temperate climate with marked seasonal differences. Basal metabolic rate (BMR), non-shivering thermogenesis (NST) and summit metabolic rate (MSUM) increased from summer to winter, with NST and MSUM already reaching maximal rates in autumn, suggesting seasonal preparation to the cold. Typical of rodents, cold-induced metabolic rates positively correlate with BAT mass. Analysis of cytochrome c oxidase (COX) activity and UCP1 content, however, demonstrate that thermogenic capacity declines with BAT mass. This resulted in seasonal differences in NST being driven by changes in BMR. The increase in BMR is supported by a comprehensive anatomical analysis of metabolically active organs, revealing increased mass proportions in the cold season. The thermoregulatory response of R. pumilio is associated with the maintenance of body weight throughout the year (48.3±1.4 g), contrasting large summer-winter mass reductions often observed in Holarctic rodents. Collectively, bioenergetic adaptation of this Afrotropical rodent involves seasonal organ adjustments influencing BMR, combined with a constant thermogenic capacity dictated by trade-offs in thermogenic properties of BAT. Arguably, this high degree of plasticity was a response to unpredictable cold spells throughout the year. Consequently, the reliance on such a resource intensive thermoregulatory strategy may expose more energetic vulnerability in changing environments of food scarcity and extreme weather conditions due to climate change, with major ramifications for survival of the species.
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Publikationstyp
Artikel: Journalartikel
Dokumenttyp
Wissenschaftlicher Artikel
Typ der Hochschulschrift
Herausgeber
Schlagwörter
Basal Metabolism ; Climate Unpredictability ; Phenotypic Plasticity ; Seasonality ; Summit Metabolism ; Non-shivering Thermogenesis
Keywords plus
Sprache
englisch
Veröffentlichungsjahr
2022
Prepublished im Jahr
HGF-Berichtsjahr
2022
ISSN (print) / ISBN
0022-0949
e-ISSN
1477-9145
ISBN
Bandtitel
Konferenztitel
Konferzenzdatum
Konferenzort
Konferenzband
Quellenangaben
Band: 225,
Heft: 13,
Seiten: ,
Artikelnummer: jeb243860
Supplement: ,
Reihe
Verlag
Company of Biologists
Verlagsort
Cambridge
Tag d. mündl. Prüfung
0000-00-00
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Gutachter
Prüfer
Topic
Hochschule
Hochschulort
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Veröffentlichungsdatum
0000-00-00
Anmeldedatum
0000-00-00
Anmelder/Inhaber
weitere Inhaber
Anmeldeland
Priorität
Begutachtungsstatus
Peer reviewed
POF Topic(s)
90000 - German Center for Diabetes Research
Forschungsfeld(er)
Helmholtz Diabetes Center
PSP-Element(e)
G-501900-221
Förderungen
Nelson Mandela University
National Research Foundation
Copyright
Erfassungsdatum
2022-09-22