title: Ultraviolet-absorbing scytonemin and mycosporine-like amino acid derivatives in exposed, rock-inhabiting cyanobacterial lichens.
abstract: The occurrence of ultraviolet (UV)-absorbing substances like scytonemin and mycosporine-glycine is reported for the first time from cyanobacterial lichens of the genera Collema, Gonohymenia and Peltula, all coming from high-light-intensity habitats. Except for Collema with the filamentous Nostoc, all other cyanobionts belong to the unicellular genera Chroococcidiopsis, Cyanosarcina, Gloeocapsa or Myxosarcina. From transmission electron microscope studies it is evident that the pigmentation (scytonemin) is located extracellularly in the sheath of the outer thallus parts. Fluorescence microscopy and microprobe measurements clearly show UV radiation into the lichen thallus and hence the relevance of UV sunscreens for the protection of the organism.
authors.affiliation: Universität Kaiserslautern, FB Biology, P.O. Box 3049, D-67653 Kaiserslautern, Germany Fax: (0)631-205-2998; e-mail: buedel@rhrk.uni-kl.de, , , , , , DE.
authors.forename: B
authors.initials: B
authors.lastname: Büdel
authors.affiliation: Alfred-Wegener-Institut for Polar and Marine Research, Am Handelshafen 12, D-27570 Bremerhaven, Germany, , , , , , DE.
authors.forename: U
authors.initials: U
authors.lastname: Karsten
authors.affiliation: Max-Planck-Institute for Marine Microbiology, Celsiusstrasse 1, D-28359 Bremen, Germany, , , , , , DE.
authors.forename: F
authors.initials: F
authors.lastname: Garcia-Pichel
keywords: Cyanobacterial lichens; Key words Ultraviolet light; Mycosporine-glycine; Scytonemin; Sunscreens