AbstractBackgroundSome organisms can survive extreme desiccation by entering a state of suspended animation known as anhydrobiosis. The free-living mycophagous nematodeAphelenchus avenaecan be induced to enter anhydrobiosis by pre-exposure to moderate reductions in relative humidity (RH) prior to extreme desiccation. This preconditioning phase is thought to allow modification of the transcriptome by activation of genes required for desiccation tolerance.ResultsTo identify such genes, a panel of expressed sequence tags (ESTs) enriched for sequences upregulated inA. avenaeduring preconditioning was created. A subset of 30 genes with significant matches in databases, together with a number of apparently novel sequences, were chosen for further study. Several of the recognisable genes are associated with water stress, encoding, for example, two new hydrophilic proteins related to the late embryogenesis abundant (LEA) protein family. Expression studies confirmed EST panel members to be upregulated by evaporative water loss, and the majority of genes was also induced by osmotic stress and cold, but rather fewer by heat. We attempted to use RNA interference (RNAi) to demonstrate the importance of this gene set for anhydrobiosis, but foundA. avenaeto be recalcitrant with the techniques used. Instead, therefore, we developed a cross-species RNAi procedure usingA. avenaesequences in another anhydrobiotic nematode,Panagrolaimus superbus, which is amenable to gene silencing. Of 20A. avenaeESTs screened, a significant reduction in survival of desiccation in treatedP. superbuspopulations was observed with two sequences, one of which was novel, while the other encoded a glutathione peroxidase. To confirm a role for glutathione peroxidases in anhydrobiosis, RNAi with cognate sequences fromP. superbuswas performed and was also shown to reduce desiccation tolerance in this species.ConclusionsThis study has identified and characterised the expression profiles of members of the anhydrobiotic gene set inA. avenae. It also demonstrates the potential of RNAi for the analysis of anhydrobiosis and provides the first genetic data to underline the importance of effective antioxidant systems in metazoan desiccation tolerance.



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Publication Title

BMC Molecular Biology





Organisational Unit

School of Biomedical Sciences