HORAK, R.V.; ROSENBERG, N.K.; HUDSON, H.A.; LEE, R.W.; YANCEY, P.H.; Whitman College; Whitman College; Whitman College; Washington State University; Whitman College: Occurrence of thiotaurine and hypotaurine in hydrothermal vent and cold seep species without endosymbionts

Marine invertebrates use organic osmolytes to balance intracellular osmotic pressure with their environment. Studies show abyssal marine animals contain unique osmolytes with uses beyond handling osmotic stress. Particularly, marine species with sulfide oxidizing endosymbionts contain substantial levels of thiotaurine and hypotaurine, proposed to be used in sulfide exposure protection and/or sulfide metabolism. To test these roles, we analyzed the major solutes in a variety of species without endosymbionts from various depths and sulfide concentrations. Cucumbers, Pannychia mosleyi and an unknown species X, were from 0.95 km (Monterey Bay, CA) within 100m of seeps. The snail, Depressigyra globulus and limpet, Lepetodrilus fucensis were collected at vents at 1.53 km (Juan de Fuca Ridge) depth. Anemones, Anthomastus ritteri and shrimp, Rimicaris exoculata were collected at seeps at 0.51 km (Eel River, CA) and at vents at 2.85 km (Mid-Atlantic Ridge) respectively. Osmolytes were analyzed in the longitudinal muscles of the cucumbers, the tail muscles in shrimp, the internal septa of anemones and the whole bodies of limpets and snails. All species contained thiotaurine and hypotaurine, except P. mosleyi. The limpets and snails both had substantial amounts, the anemones contained moderate amounts and the shrimp and unknown cucumbers contained small amounts of thiotaurine. The occurrence of thiotaurine and hypotaurine in species without endosymbionts suggests thiotaurine and hypotaurine may play a role in sulfide detoxification or these species may contain undiscovered endosymbionts and use these solutes in sulfide metabolism.