GENOME-WIDE ANALYSIS OF GENE EXPRESSION IN HALICEPHALOBUS MEPHISTO (THE DEVIL WORM)

The nematode Halicephalobus mephisto was discovered in an isolated aquifer, 1.3km below ground. H. mephisto thrives under extreme conditions including elevated heat (37.2°C) and minimal oxygen, classifying it as an extremophile. H. mephisto is a vital discovery for evolution and adaptation, with particular interest in its thermophilic abilities. Here we report the full transcriptome and genome of H. mephisto. In the process we identified a unique adaptation: over amplification of AIG1 and Hsp70 genes, with 168 and 142 domains respectively. Hsp70 was over-expressed under elevated heat conditions, along with ARMET and Bax inhibitor-1, suggesting these genes help H. mephisto to survive elevated heat. AIG1 was not upregulated in elevated heat suggesting its use for non-heat abiotic stressors such as hypoxia. This paper sheds light on the genomic adaptations that have evolved in H. mephisto to survive its challenging environment.