title: Free radicals and chemiluminescence as products of the spontaneous oxidation of sulfide in seawater, and their biological implications.
abstract: The discovery of symbioses between marine invertebrates and sulfide-oxidizing bacteria at deep-sea hydrothermal vents and in other high-sulfide marine environments has stimulated research into the adaptations of metazoans to potentially toxic concentrations of sulfide. Most of these studies have focused on a particular action of sulfide--its disruption of aerobic metabolism by the inhibition of mitochondrial respiration--and on the adaptations of sulfide-tolerant animals to avoid this toxic effect (1). We propose that sulfidic environments impose another, hitherto over-looked type of toxicity: exposure to free radicals of oxygen, which may be produced during the spontaneous oxidation of sulfide, thus imposing an oxidative stress. Here we present evidence that oxygen- and sulfur-centered free radicals are produced during the oxidation of sulfide in seawater, and we propose a reaction pathway for sulfide oxidation that is consistent with our observations. We also show that chemiluminescence at visible wavelengths occurs during sulfide oxidation, providing a possible mechanism for the unexplained light emission from hydrothermal vents (2, 3).
authors.affiliation: Department of Zoology and Center for Marine Studies, University of Maine, Orono, Maine 04469-5751.
authors.forename: D W
authors.initials: DW
authors.lastname: Tapley
authors.affiliation: Department of Zoology and Center for Marine Studies, University of Maine, Orono, Maine 04469-5751.
authors.forename: G R
authors.initials: GR
authors.lastname: Buettner
authors.affiliation: Department of Zoology and Center for Marine Studies, University of Maine, Orono, Maine 04469-5751.
authors.forename: J M
authors.initials: JM
authors.lastname: Shick