In Situ Cellular and Enzymatic Investigations of Saxicolous LIchens Using Correlative Microscopical and Microanalytical Techniques

Abstract

Direct in situ microscopy visualization is strongly recommended in studies of saxicolous lichen ecology and endolithic microorganisms. With this in mind, lithobiontic microorganisms were detected, localizad and determined at the cytological level. A range of microscopy techniques and a number of procedures for preparing lichen colonizad rock samples were applied. Scanning Electron Microscopy operating in Back Scattered Electron mode (SEM-BSE), Confocal Láser Scanning Microscopy ,(CLSM) and occasionally Energy Dispersión Spectroscopy (EDS) were used to study the same sample zones. This observation strategy, called "Correlative Microscopy", allowed us to obtain important information on the physico-chemical state of the mineral substrate, deposition processes of calcium ' oxalate and the in situ ultrastructural determination of lithobiontic microorganisms. Moreover, the observation of the three dimensional organization of living endolithic cells was also possible. On occasions, when cytological discernment was not sufficient, the SEM-BSE signal was used to detect immunolabeled gold particles which had previously been linked to proteins in order