Abstract
Anabaena, a kind of cyanobacteria, can grow heterotrophically under dark conditions by sugar addition as well as autotrophycally with light illumination. Early studies by electron microscopy revealed that some cyanobacteria show changes in morphology of thylakoid membrane and composition of pigment-protein complexes in cases of heterotrophic incubation. Microscopic fluorescence spectral analysis, which provides us fluorescence spectra of thylakoid membrane with high spatial resolution, will help us understand changes in properties and morphology of thylakoid membrane. Our two-photon excitation line-scanning fluorescence spectral microscopy can record fluorescence spectra with nearly diffraction-limited spatial resolution and wavelength resolution of 2 nm. We studied how thylakoid membrane of anabaena depends on nutritional environment. We have confirmed durability of Anabaena thylakoid membrane after obtaining a few tens of z-sections of spectral imaging. We have acquired highly accurate fluorescence spectra and intensity distribution of heterotrophically incubated anabaena cells, which exhibit characteristic features in comparison to autotrophic ones.
