139.6 Monday, Jan. 7 High contents of methylamines and scyllo-inositol as potential piezolytes (pressure counteractants) in muscles of amphipods from the Mariana Trench YANCEY, P.H.*; GERRINGER, M.E.; CAMERON, J.; HARDY, K.; CHASTAIN, R.; BARTLETT, D.H.; Whitman College; Whitman College; DEEPSEA CHALLENGE; Scripps Institution of Oceanography; Scripps Institution of Oceanography; Scripps Institution of Oceanography firstname.lastname@example.org
One hypothesis to explain how life adapts to the deep sea involves piezolytes, small organic solutes (first discovered as osmolytes) that counteract perturbations of proteins by hydrostatic pressure. Trimethylamine oxide (TMAO) is a prime candidate. 1) It counteracts pressure effects on protein activity and stability in vitro, better than other osmolytes. 2) Muscle TMAO contents increase with depth in marine bony fishes (analyzed to 7 km depth). 3) In marine decapods (osmoconformers with a fixed osmolyte total), muscles in shallow species are dominated by the non-piezolyte glycine, but TMAO increases and glycine decreases with depth in species down to 3 km. 4) Muscle TMAO contents increase with depth (to 1.4 km) in freshwater Lake Baikal amphipods, which do not need osmolytes. Here we report organic osmolytes in amphipods (Hirondellea sp.) from 10.9 km in the Mariana Trench. They were caught with a lander with bait (tuna, chicken) inside a 30 L Niskin sampler that rested on the seafloor. On the ship, animals were deep-frozen and later shipped on dry ice to Whitman College, where metasomal muscles (n=5) were analyzed for osmolyte-type solutes. We found no glycine but instead a predominance of the methylamines TMAO, glycerophosphocholine and dimethylglycine, plus the polyol scyllo-inositol (SI). Though only TMAO has been tested with pressure, all are potential piezolytes as each is a protein stabilizer (e.g., SI stabilizes the non-toxic form of beta amyloid). These results represent a record depth for such analyses of animals and support the piezolyte hypothesis. Funding by the National Science and Blue Planet Marine Research Foundations.