Position-dependent changes in phycobilisome abundance in multicellular cyanobacterial filaments revealed by Raman spectral analysis

The one-dimensional filamentous cyanobacterium, Anabaena sp. PCC 7120, shows a simple pattern consisting of two types of cells under the nitrogen-deprived conditions. We found that the microbial pigment composition in differentiated (heterocyst) and undifferentiated cells (vegetative cells) were distinguished by using a Raman microscope. The Raman bands of phycocyanin and allophycocyanin were higher in the vegetative cells than those in the heterocysts. However, these bands were statistically lower in a part of vegetative cells, which were located far from a nearby heterocyst. That is, the pigment composition in the individual cells was affected by a locational information in a filament.