Abstract: With confocal microscopy and grating spectrograph, the absorption and fluorescence emission spectra of single Anabaena strain PCC 7120 cells have been studied in intact filaments in situ. The different spectra between vegetative cells and heterocysts are observed. The evident heterogeneities in heterocysts that have not been reported previously are attributed to the different stages of the evolution of phycobilisomes and photosystems in heterocysts.

Key words: Cyanobacteria, Single cell, Heterocyst, Confocal microscopy, 　Absorption spectra, Fluorescence emission spectra