Fluorescence intensity in Early Cambrian acritarchs from Estonia

Fluorescence properties of Early Cambrian acritarchs were investigated using Leica DM IRBE Laser Scanning Confocal Microscopy (LSCM) with a mercury lamp attached. Well-preserved autofluorescence properties were observed in Early Cambrian acritarch cell walls (more than 540 millions years old) using both direct and computerized microscopy. Fluorescence images and fluorescence intensity graphics, together with transmitted light microscopy, showed a strong correlation between acritarch morphology and the intensity of the emitted fluorescence signal of their sporopollenin-like walls. In accordance with the fluorescence intensity of organic cell walls three groups of microfossils from the Lükati Formation of Estonia are distinguished. The first group includes specimens of the prasinophycean Tasmanites sp., the second and third contain acritarchs which show different fluorescence intensity depending on their morphology. The difference in the autofluorescence among Early Cambrian acritarchs from the Lükati Formation supports previous suggestions that acritarch walls could be built of different polymers of the sporopollenin-like material. Two acritarch species Leiosphaeridia pelucida Schepeleva, 1963 and Archaeodiscina umbonulata Volkova, 1968 are separated from other species within the studied acritarch assemblage on the basis of the fluorescence intensity.