Genetics. Published Articles Ahead of Print: July 29, 2007, Copyright © 2007
doi:10.1534/genetics.107.078857


A more recent version of this article appeared on October 1, 2007.

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Genetic analysis of dauer formation in Caenorhabditis briggsae

Takao Inoue 1, Michael Ailion 2, Shirley Poon 3, Hannah K Kim 1, James H. Thomas 2 and Paul W Sternberg 1*

1 California Institute of Technology
2 University of Washington
3 Alhambra High School

* To whom correspondence should be addressed. E-mail: pws{at}caltech.edu.

Submitted on July 13, 2007
Revised on July 18, 2007
Accepted on 18 July 2007


Abstract

Molecular changes that underlie evolutionary changes in behavior and physiology are not well understood. Dauer formation in C. elegans is a temperature-sensitive process controlled through a network of signaling pathways associated with sensory neurons, and is potentially an excellent system in which to investigate molecular changes in neuronal function during evolution. To begin to investigate the evolution of dauer formation in the genus Caenorhabditis at the molecular level, we isolated dauer-formation mutations in Caenorhabditis briggsae, a species closely related to the model organism C. elegans. We identified mutations in orthologs of C. elegans genes daf-2 (insulin receptor), daf-3 (Smad) and daf-4 (TGF-{beta} type 2 receptor), as well as genes required for formation of sensory cilia. Phenotypic analyses revealed that functions of these genes are conserved between C. elegans and C. briggsae. Analysis of C. briggsae mutations also revealed a significant difference between the two species in their responses to high temperatures (>26°). C. elegans is strongly induced to form dauers at temperatures above 26°, near the upper limit for growth of C. elegans. In contrast, C. briggsae, which is capable of growth at higher temperatures than C. elegans, lacks this response.

Key Words: behavior, dauer, evolution, life span, temperature