Comparative transcriptomics suggests conserved mechanisms of anhydrobiosis in the entomopathogenic nematode...

Anhydrobiosis is an evolutionarily conserved phenomenon observed across a diverse range of organisms. We have deployed a cross-species search to identify the homologs for anhydrobiosis-specific transcripts from Heterorhabditis indica. It revealed that H. indica transcriptome shares 14-53% homology with other EPNs, ∼27% with PPNs, ∼45% with Caenorhabditis elegans, and ∼6.5% with unrelated organisms like Drosophila melanogaster and Saccharomyces cerevisiae, which exhibit varying desiccation tolerance. Notably, the unfolded protein response (a prominent stress-related pathway) was shared across nematodes, indicating a conserved stress response mechanism regardless of the feeding behavior. We also performed the standalone BLASTx searches for the differentially expressed transcripts from anhydrobiotic H. indica against manually curated stress-specific protein databases like, DisProt, LEAPDB, HSPIR, sHSPdb, and DroughtDB. Significant matches were identified, with 15 upregulated transcripts in H. indica showing similarity against the DisProt database, 4 transcripts (2 upregulated and 2 downregulated) aligned with LEAPDB, 76 transcripts aligning with HSPIR, 14 with sHSPdb, and 76 with DroughtDB. The findings suggest that these homologs may perform analogous functions during anhydrobiosis in H. indica. Further, we characterized the intrinsically disordered proteins (IDPs) and late embryogenesis abundant (LEA) proteins using bioinformatic tools such as PONDR, localCIDER, and DEPP and found that the disorderness ranges from ∼ 8-100%. This study provides valuable insights into the molecular basis of anhydrobiosis and highlights conserved stress-response mechanisms that could inform broader applications in stress biology.