Comparison of a New Wild-Type Caenorhabditis Briggsae With Laboratory Strains of C. Briggsae and C. Elegans

Abstract

The hermaphroditic nematode strain G16, isolated from soil in Gujarat, India was identified as Caenorhabditis briggsae by genetic and morphological criteria. By contrast with the Dougherty strain of C. briggsae, in culture since 1944, the behavior of G 16 resembles that of the wild-type C. elegans strain N2. The Gujarat population does not exhibit uncoordinated movement, it produces males which mate efficiently, it exhibits chemotaxis, and it forms dauer larvae in response to crowding or starvation. The G16 animals grow bigger, have a shorter generation time (1.6 days at 25°C) and produce larger broods than the Dougherty strain. We conclude that the Dougherty strain has accumulated genetic defects during the years of laboratory cultivation. Genetic analysis using G16-Dougherty hybrids demonstrates that the defects in movement, chemotaxis, and dauer larva formation are all X-linked but genetically separable, while morphological differences in the male copulatory bursa are inherited autosomally. A Caenorhabditis-specific pheromone, which enhances entry into the dauer larva stage, is produced by the N2, G16, and Dougherty strains, but the Dougherty strain does not respond to the pheromone. The new wild-type C. briggsae may be more appropriate than the Dougherty strain for genetic study of C. briggsae or for future comparative studies with wild-type C. elegans.