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

First published online February 27, 2009
Journal of Experimental Biology 212, 808-814 (2009)
Published by The Company of Biologists 2009
doi: 10.1242/jeb.025528

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 Similar articles in this journal 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 Ksiazek, A. Articles by Konarzewski, M. Search for Related Content PubMed Articles by Ksiazek, A. Articles by Konarzewski, M. Social Bookmarking                         What's this?

Phenotypic flexibility of traits related to energy acquisition in mice divergently selected for basal metabolic rate (BMR)

Aneta Ksiek^*, Jan Czerniecki and Marek Konarzewski

Institute of Biology, University of Biaystok, wierkowa 20b, 15-950 Biaystok, Poland

^* Author for correspondence (e-mail: anetak{at}uwb.edu.pl)

Accepted 6 January 2009

Theoretical considerations suggest that one of the main factors determining phenotypic flexibility of the digestive system is the size (mass) of internal organs. To test this, we used mice from two lines selected for high and low levels of basal metabolic rate (BMR). Mice with higher BMRs also have larger internal organs and higher daily food consumption (C) under non-stressful conditions. We exposed animals from both lines to a sudden cold exposure by transferring them (without prior acclimation) from an ambient temperature of 23°C to 5°C. Cold exposure elicited a twofold increase in C and a 25% reduction of apparent digestive efficiency. For the same body mass-corrected C, small intestine, kidneys, heart and liver of cold-exposed low-BMR mice were smaller than those of the high-BMR line. Therefore, the internal organs of low-BMR animals were burdened with substantially higher metabolic loads (defined as C or digestible food intake per total mass of a particular organ). The mass-specific activity of citrate synthase (CS) in the liver and kidneys (but not heart) was also lower in the low-BMR mice. The magnitude of phenotypic flexibility of internal organ size and CS activity was strictly proportional to the organ mass (in the case of kidneys and liver, also mass-specific CS activity) prior to an increased energy demand. Thus, phenotypic flexibility had additive rather than multiplicative dynamics. Our results also suggest that variation in BMR positively correlates with the magnitude of an immediate spare capacity that fuels the initial response of internal organs to a sudden metabolic stress.

Key words: phenotypic flexibility, immediate spare capacity, organ size, organ mass, metabolic load, citrate synthase, artificial selection

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

This article has been cited by other articles:

				A. K. Gebczynski and M. Konarzewski Metabolic correlates of selection on aerobic capacity in laboratory mice: a test of the model for the evolution of endothermy J. Exp. Biol., September 1, 2009; 212(17): 2872 - 2878. [Abstract] [Full Text] [PDF]