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Abstract

Larvae of the clade IV parasitic nematode genus Strongyloides spp. can switch between rapidly developing L3 that will develop into free-living adults and infective larvae that pause development until they found and invaded a new host. This switch is considered to be homologous to the dauer switch in P. pacificus and C. elegans (dauer hypothesis) and comparative studies have been conducted attempting to study the evolution of parasitism. While the signaling pathways involved in dauer formation in C. elegans are clearly present in Strongyloides and some regulatory modules, i.e. DAF- 12 appear to have conserved functions, the roles of the other pathways and in the logics of their regulatory interactions appear to differ. However, any difference found between C. elegans and Strongyloides spp. is much more likely to be due to the large phylogenetic distance than the fact that one is free-living and the other is a parasite. Therefore, we plan to conduct comparative studies between Strongylodes spp. and its closely related facultatively parasitic and dauer forming free living relatives, Parastrongyloides trichosuri and Rhabditophanes spp., respectively. To this end we are in the process of establishing forward and reverse genetic tools, i.e. transgenics, RNAi and CRISPR, for these nematodes.