Genetic analysis of dauer formation in Caenorhabditis briggsae.
Molecular changes that underlie evolutionary changes in behavior and physiology are not well understood. Dauer formation in Caenorhabditis 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 C. 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 degrees). C. elegans is strongly induced to form dauers at temperatures above 26 degrees, 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.
HHMI and Division of Biology, California Institute of Technology, Pasadena, California 91125, USA.
Takao
T
Inoue
Michael
M
Ailion
Shirley
S
Poon
Hannah K
HK
Kim
James H
JH
Thomas
Paul W
PW
Sternberg
D000222:Adaptation, Physiological / Q000235:genetics*; D000818:Animals; D002107:Caenorhabditis / Q000235:genetics* / Q000254:growth & development* / Q000502:physiology; D017173:Caenorhabditis elegans / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D029742:Caenorhabditis elegans Proteins; D007814:Larva / Q000254:growth & development; D008018:Life Cycle Stages / Q000235:genetics*; D009154:Mutation; D009475:Neurons, Afferent; D011972:Receptor, Insulin; D018125:Receptors, Transforming Growth Factor beta; D015398:Signal Transduction / Q000235:genetics* / Q000502:physiology; D051785:Smad Proteins; D013045:Species Specificity; D013696:Temperature
D029742:Caenorhabditis elegans Proteins; C108738:DAF-3 protein, C elegans; D018125:Receptors, Transforming Growth Factor beta; D051785:Smad Proteins; C083704:daf-4 protein, C elegans; C107483:DAF-2 protein, C elegans; D011972:Receptor, Insulin