Meeting Abstract

47.8  Jan. 6  Signal Transduction in the Cyanobacteria Lyngbya confervoides and L. polychroa: Ecological Implications of Reactive Oxygen Species ROSS, C.R.**; PAUL, V.J.; Smithsonian Marine Station at Ft. Pierce; Smithsonian Marine Station at Ft. Pierce ross@sms.si.edu

The ecological significance of reactive oxygen species (ROS) and the emerging role of reactive nitrogen species (RNS) as defense response compounds as well as signal transduction agents in higher plant physiology have been well documented. While substantial chemical and enzymatic responses are known to be affected by ROS, the biochemical mechanisms of ROS/RNS production in marine cyanobacteria remain elusive. Furthermore, the ecological implications of ROS/RNS production have not been identified. Specimens of L. confervoides and L. polychroa responded to mechanical injury, changes in seawater osmolarity, and UV irradiation with a transient release of hydrogen peroxide and nitric oxide. By use of selected pharmacological probes, our results indicate that H₂O₂ production was based on the initial activation of an NADPH oxidase complex as demonstrated by pharmacological inhibition. The exogenous addition of millimolar concentrations of H₂O₂ promoted programmed cell death. The production and putative signaling roles of ROS/RNS will be discussed with emphasis on the ecology of marine cyanobacteria.