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SULFIDE OXIDATION OCCURS IN THE ANIMAL TISSUE OF THE GUTLESS CLAM, SOLEMYA REIDI

1985; Marine Biological Laboratory (MBL); Volume: 169; Issue: 1 Linguagem: Inglês

10.2307/1541396

1939-8697

Mark A. Powell, George N. Somero,

Physiological and biochemical adaptations

A gutless clam, Solemya reidi, from sulfide-rich habitats has gills containing symbiotic, chemoautolithotrophic bacteria that are presumed to oxidize sulfide to provide a major energy source for the symbiosis. Sulfide oxidation was studied for S. reidi; activity of gill and foot extracts displayed Michaelis-Menten kinetics and was presumably due to sulfide oxidase enzymes. The activity of S. reidi gill extracts was protease sensitive and heat sensitive and was 10 to 20 times higher than in tissues from bivalves not living in sulfide-rich environments. The site of sulfide oxidation was studied by cytochemistry, 35S-sulfide autoradiography, cell fractionation methods, and by X-ray microanalysis. In gills of S. reidi, the sulfide-oxidizing activity was detected not in the symbiotic bacteria, but within organelles of the gill cells we have named sulfide oxidizing bodies. In foot tissue of S. reidi, sulfide oxidation activity was distributed diffusely throughout the superficial cell layers of the foot. The discussion considers the roles of sulfide oxidation in protection of aerobic respiration from sulfide inhibition and in exploitation of the energy contained in sulfide.