QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in JEB Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Bicudo, J. E. P. W. Articles by Vianna, C. R. Search for Related Content PubMed PubMed Citation Articles by Bicudo, J. E. P. W. Articles by Vianna, C. R. Social Bookmarking                         What's this?

The Journal of Experimental Biology 205, 2267-2273 (2002)
© 2002 The Company of Biologists Limited

Review

Adaptive thermogenesis in hummingbirds

José Eduardo P. W. Bicudo^1,*, Antonio C. Bianco² and Cláudia R. Vianna^1,3

¹ Department of Physiology, Biosciences Institute, University of São Paulo, SP, Brazil
² Thyroid Division, Department of Medicine, Brigham & Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
³ Division of Endocrinology, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02115, USA
^* Present address: Departmento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, 05508-900 São Paulo, SP, Brazil

(e-mail: jebicudo{at}usp.br )

Accepted 13 May 2002

The occurrence of non-shivering thermogenesis in birds has long been a controversial issue. Although birds are endothermic vertebrates, sharing with mammals (placental mammals and marsupials) a common ancestor, they do not possess brown adipose tissue or a similar type of tissue, unlike their mammalian counterparts. Some bird species are, however, able to withstand very low ambient temperatures (-70 °C) or undergo periods of heterothermia, and there is now good experimental evidence showing that non-shivering thermogenesis may indeed occur in birds under such conditions. The skeletal muscles of birds, particularly the flight muscles, occupy a significant fraction (approximately 30 %) of the total body mass, and recent results have shown that they are likely to be the main sites for non-shivering thermogenesis. The precise mechanisms involved in adaptive thermogenesis in birds are still not fully understood. The translocation of Ca²⁺ between intracellular compartments and the cystosol mediated by the sarcoplasmic reticulum Ca²⁺-ATPase, uncoupled from ATP synthesis, is one mechanism whereby chemi-osmotic energy can be converted into heat, and it has been proposed as one of the possible mechanisms underlying non-shivering thermogenesis in birds on the basis of data obtained mainly from ducklings acclimatized to cold conditions. The recent characterization of an uncoupling protein homolog in avian skeletal muscle and the expression of its mRNA at different stages of the torpor/rewarming cycle of hummingbirds indicate that it has the potential to function as an uncoupling protein and could play a thermogenic role during rewarming in these birds.

Key words: non-shivering thermogenesis, brown adipose tissue, Ca²⁺-ATPase, uncoupling protein, bird, hummingbird

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

Related articles in JEB:

Muscles Function, Whatever the Temperature

Kathryn Phillips
JEB 2002 205: i. [Full Text]  

This article has been cited by other articles:

				B. Wentworth, J. Cigan, and T. Schaaf Tolerance of Japanese quail embryos and young chicks to hypothermia Poult. Sci., May 1, 2009; 88(5): 1040 - 1043. [Abstract] [Full Text] [PDF]

				P. Wiersma, M. A. Chappell, and J. B. Williams Cold- and exercise-induced peak metabolic rates in tropical birds PNAS, December 26, 2007; 104(52): 20866 - 20871. [Abstract] [Full Text] [PDF]

				M. Hirabayashi, D. Ijiri, Y. Kamei, A. Tajima, and Y. Kanai Transformation of Skeletal Muscle from Fast- to Slow-Twitch during Acquisition of Cold Tolerance in the Chick Endocrinology, January 1, 2005; 146(1): 399 - 405. [Abstract] [Full Text] [PDF]