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SUMMARY:An inorganic antioxidant in a living system impacting atmospheric 
 and marine chemistry: Iodide in seaweeds (kelp)  - Prof. Frithjof C. Kuepp
 er from Oceanlab\, University of Aberdeen
DTSTART:20180717T120000Z
DTEND:20180717T130000Z
UID:TALK107980@talks.cam.ac.uk
CONTACT:71116
DESCRIPTION:Brown algae of the Laminariales (kelps) are the strongest accu
 mulators of iodine among living organisms. They represent a major pump in 
 the global biogeochemical cycle of iodine and in particular\, the major so
 urce of iodocarbons in the coastal atmosphere. Nevertheless\, the chemical
  state and biological significance of accumulated iodine have remained unk
 nown. Elucidation of these questions was the objective of this study. Usin
 g an interdisciplinary array of techniques\, chiefly relying on synchrotro
 n X-ray absorption spectroscopy\, we show that the accumulated form is iod
 ide\, which readily scavenges a variety of reactive oxygen species (ROS). 
 We propose here that its biological role is that of an inorganic antioxida
 nt\, the first ever to be described in a living system. Upon oxidative str
 ess\, iodide is effluxed. On the thallus surface and in the apoplast\, iod
 ide detoxifies both aqueous oxidants and ozone\, the latter resulting in t
 he release of high levels of molecular iodine and consequent formation of 
 hygroscopic iodine oxides leading to particles\, which are precursors to c
 loud condensation nuclei. When kelp thalli are submerged\, this process im
 pacts iodine speciation in seawater. In several aspects\, iodide is unique
  as a biological antioxidant. Among the halides\, it has by far the best a
 ntioxidant properties\; yet\, bromide complements it for the detoxificatio
 n of superoxide.
LOCATION:Department of Plant Sciences\, Large Lecture Theatre
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