Spatial distribution of perylenequinones in lichens and extended quinones in quincyte using confocal fluorescence microscopy

The application of confocal fluorescence microscopy and microspectrofluorim etry to the characterization of the distribution of organic compounds in bu lk lichens and mineral structures is demonstrated. Perylenequinones and ext ended quinones were chosen as both model compounds and as the naturally occ urring fluorophores. These molecules occur, respectively, in corticolous mi crolichens and in a pink-colored mineral called quincyte. The structures of quincyte and of the lichens Cryptothelium rhodotitton and Graphis hematite s are described, and the possibilities of energy dissipation and photoprote ction mechanisms in these lichens are discussed. This study also illustrate s how, for a wide range of specimens, naturally occurring quinone fluoropho res in the specimen can be exploited directly to yield chemical and structu ral information without using fluorescent labelling. These intrinsic quinon oid compounds have molecular fluorescence yields and laser damage threshold s comparable or superior to common microscopy dyes, and can therefore be us ed to obtain high-contrast 3D fluorescence imaging without the complication s introduced by dye labelling. (C) 2000 Elsevier Science Ltd. All rights re served.