Advances in microscopy: microautoradiography of single cells.

Microautoradiography (MAR) is an efficient method to obtain reliable information about the ecophysiology of microorganisms at the single cell level in mixed communities. Data obtained by the traditional MAR method can now be improved significantly when MAR is combined with fluorescence in situ hybridization (FISH) with oligonucleotide probes for the identification of target organisms. This chapter discusses how to use MAR-FISH in various ecosystems with emphasis on the type of information to be obtained, incubation conditions, and detailed protocols for the MAR technique. It also discusses new MAR applications and the type of information that can be obtained, e.g., the use of dual labeling to investigate the simultaneous uptake of several substrates by individual prokaryotes.