Comparative study of thermal tolerance and other physiological characteristics inC. briggsaeandC. elegans

Abstract

ABSTRACTThe nematodeCaenorhabditis briggsae(C. briggsae) is routinely used in genetic and evolutionary studies involving its well-known cousin,C. elegans. The two species are morphologically almost identical but exhibit significant developmental, genetic, and genomic differences. The AF16 isolate ofC. briggsaeis an established reference strain. We used additional wild isolates from tropical and temperate regions to perform a comparative study of phenotypic characters. The analysis revealed both intra (betweenC. briggsaeisolates) and inter (compared toC. elegansN2) species variability in dimensions and opacity. Our data also showed thatC. briggsaeisolates prefer higher temperatures for growth, reproduction, and survival thanC. elegansN2. The preference for higher temperatures further translated into a higher tolerance for heat stress, as evidenced by its survival at temperatures lethal to N2. Interestingly, we found that whileC. briggsaeis more resistant to heat and shows greater sensitivity to other forms of stress, namely oxidative and osmotic, compared toC. elegans. The heat resistance ofC. briggsaewas correlated with efficient upregulation of the cytosolic chaperonhsp-16.2. Overall, this work has revealed significant differences in stress sensitivities between the two nematodes and forms the basis to investigate changes in underlying mechanisms that affect their stress responses.