Format

Send to

Choose Destination
Physiol Biochem Zool. 2007 Sep-Oct;80(5):491-9. Epub 2007 Jul 13.

Anatomic and molecular correlates of divergent selection for basal metabolic rate in laboratory mice.

Author information

1
Institute of Biology, University of Białstok, Swierkowa 20B,15-950 Białystok,Poland. pbrzek2@wisc.edu

Abstract

Proximal mechanisms describing the evolution of high levels of basal metabolic rate (BMR) in endotherms are one of the most intriguing problems of evolutionary physiology. Because BMR mostly reflects metabolic activity of internal organs, evolutionary increase in BMR could have been realized by an increase in relative organ size and/or mass-specific cellular metabolic rate. According to the "membrane pacemaker" theory of metabolism, the latter is mediated by an increase in the average number of double bonds (unsaturation index) in cell membrane fatty acids. To test this, we investigated the effect of divergent artificial selection for body-mass-corrected BMR on the mass of internal organs and the fatty acid composition of cell membranes in laboratory mice (Mus musculus). Mice from the high-BMR line had considerably larger liver, kidneys, heart, and intestines. In contrast, the unsaturation index of liver cell membranes was significantly higher in low-BMR mice, mainly because of the significantly higher content of highly polyunsaturated 22 : 6 docosahexanoic fatty acid. Thus, divergent selection for BMR did not affect fatty acyl composition of liver and kidney phospholipids in the direction predicted by the membrane pacemaker theory. We conclude that an intraspecific increase in BMR may rapidly evolve mainly as a result of the changes in size of internal organs, without simultaneous increase of the unsaturation index in cell membrane lipids.

PMID:
17717812
DOI:
10.1086/520617
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for University of Chicago Press
Loading ...
Support Center