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Welman, S.* ; Jastroch, M. ; Mzilikazi, N.*

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)
DOI PMC
Open Access Green möglich sobald Postprint bei der ZB eingereicht worden ist.
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
Korrespondenzautor
Schlagwörter Basal Metabolism ; Climate Unpredictability ; Phenotypic Plasticity ; Seasonality ; Summit Metabolism ; Non-shivering Thermogenesis
ISSN (print) / ISBN 0022-0949
e-ISSN 1477-9145
Zeitschrift The journal of experimental biology
Quellenangaben Band: 225, Heft: 13, Seiten: , Artikelnummer: jeb243860 Supplement: ,
Verlag Company of Biologists
Verlagsort Cambridge
Nichtpatentliteratur Publikationen
Begutachtungsstatus Peer reviewed
Institut(e) Institute of Diabetes and Obesity (IDO)
Förderungen Nelson Mandela University
National Research Foundation