Functional Testing of a Stress Adaptation Biosignature Observed in the Devil Worm
Halicephalobus mephisto was discovered nearly 1.3 kilometers below Earth's surface in the Beatrix Gold Mine of South Africa. When underground, the organism was found to be residing in extreme environmental conditions that could prove to be very strenuous on the organism, such as heated (37 °C), methane-rich, hypoxic water. Genome sequencing of the nematode indicated that there were expansions of the 70 kilodalton heat shock protein (Hsp70) and avrRpt2 -induced genes (AIG1), with both gene families having been previously identified as cellular survival genes. This expansion of both Hsp70 and AIG1 gene families were also found to be convergently expanded in distantly related Mollusks, with expansion specifically present in bivalves. The presence of these convergently expanded gene families within two distantly related animal phylum that both routinely endure environmental stressors such as hypoxia and elevated temperatures can indicate a biosignature response to environmental stress. However, to identify if the unique gene family expansion is truly a biosignature of environmental stress, the survival of the organism must be tested with the inactivation of the expanded gene families. In this work we are exploring the function of these genes, starting with a proposed master regulator gene: ARMET/MANF (Arginine-Rich Mutated in Early State Tumors / Mesencephalic Astrocyte Derived Neurotrophic Factor). RNA interference will allow the inactivation of suspected intermediate regulator proteins such as ARMET, which could then cause a change in either AIG1 or Hsp70 expression and ultimately lead to organismal impairment or death.