Polymorphism in heat shock protein gene (hsp70) in entomopathogenic nematodes (Rhabditida)

1. All organisms tested respond to a sudden increase of temperature by synthesizing heat-shock proteins, which helps organisms to survive high temperature. A correlation with increased thermotolerance and production of major: 70 kDa protein has been observed in many organisms. 2. Many studies have been designed on a large number of animal species to assess their adaptation to different thermal environments. Genetic analysis of the hsp70 gene in entomopathogenic nematodes inhabiting different environments may provide insight into the physiological roles of hsps in these nematodes and could be useful for ecological studies. 3. To assess variation among species of entomopathogenic nematodes for thermotolerance, we initiated a search for the molecular organization of heat-inducible hsp70 genes in these nematodes. Five Heterorhabditis species/isolates with different temperature optima for survival and one warm-adapted species of Steinernema were tested. 4. PCR and RFLP analyses of hsp70 in Heterorhabditis species and S. scapterisci demonstrated a putative homology with the Caenorhabditis elegans hsp70 A gene, thus indicating evolutionary conserved nature among different nematode species. 5. RFLPs with the hsp70 A gene probe revealed different banding patterns for Heterorhabditis species and isolates. 6. This is the first report on the identification of any hsp70 gene in entomopathogenic nematodes. 7. Our observation establishes a unique correlation between geographical distribution and polymorphisms for hsp70 A gene in these nematodes.