Chen, S., Department of Nematology, ARO, Volcani Center, Bet Dagan 50250, Israel
Gollop, N., Department of Food Science, ARO, Volcani Center, Bet Dagan 50250, Israel
Glazer, I., Department of Nematology, ARO, Volcani Center, Bet Dagan 50250, Israel

Infective juveniles (IJs) of the entomopathogenic nematode (EPN) Steinernema feltiae IS-6 can survive exposure to 24% glycerol solution by entering an osmotically desiccated state. Exposure of osmotically desiccated nematodes to extreme temperature assays (40°C for 10 h and -20°C for 360 h) resulted in gradual reduction in survival, whereas non-desiccated IJs died within a short exposure to the assay conditions. Through SDS-PAGE, a stress-related protein UNC-87 was found in osmotically desiccated IJs exposed to 40°C for 3, 6, and 8 h, whose survival rates were 98·9± 1·43, 78·5±5·87 and 20·9±4·93%, respectively. The protein was not found in IJs following exposure of osmotically desiccated individuals to 40°C for 10 h, in which none of the IJs survived. After exposure to -20°C for 360 h, the survival of osmotically desiccated EPNs with a weak band of UNC-87 was 13·0±3·32%. To identify other responsive proteins that are required for osmotic stress, we used 2-dimensional electrophoresis to analyse the proteins in osmotically desiccated EPNs. The results revealed that 10 novel protein spots and 10 up-regulated protein spots in osmotically desiccated IJs were detected by digital image analysis. Mass spectrometry analysis of 7 significant spots indicated that osmotic stress in desiccated IJs was associated with the induction of actin, Proteasome regulatory particle (ATPase-like), GroEL chaperonin, GroES co-chaperonin and transposase family member. It seems to show actin, UNC-87 and Proteasome regulatory particle may play distinct roles in specific aspects of organization of macromolecular structures under desiccation stress. GroEL and GroES are members of the Hsp60 family of chaperons. © 2005 Cambridge University Press.