Protective pigmentation in UVB-screened Antarctic lichens studied by Fourier transform Raman spectroscopy: an extremophile bioresponse to radiation stress

FT-Raman spectra were obtained for two Antarctic extremophiles, the epilithic lichens Xanthoria elegans and Caloplaca sublobulata from the maritime ecological long-term research site on Leonie Island. Twelve specimens from cloches designed for the filtering out and transmission of UVB radiation over a 2 year period and two specimens from the natural habitat outside the cloches were analysed in terms of their characteristic Raman bands from the two photoprotective pigments parietin and beta-carotene. Following chemometric analysis, the specimens inside the UVB-protective cloches exhibited a lower parietin:beta-carotene ratio than specimens from the same habitat that did not have UVB protection. The relative roles of parietin, a passive UVB photoprotectant, and beta-carotene are discussed and a possible duality of biological function is suggested for these pigments.