Abstract
Anabaena sp. PCC 7120 develops specialized cells called heterocysts for nitrogen fixation. Heterocysts are terminally differentiated cells, which do not divide. In previous studies, it was considered that the cell division is necessary for the process of heterocyst development and that the decision of heterocyst is random. In the present study, we followed the process of heterocyst differentiation in single filaments of Anabaena sp. PCC 7120. We analyzed the time-dependent change of heterocyst pattern, the relationship between heterocyst differentiation and phycobilisome fluorescence and the positioning of the heterocysts at initial stage of heterocyst induction. These results suggested that a set of 4 cells at initiation of heterocyst induction was important for the decision of the cell that became heterocyst early during the induction. We propose a model of initial heterocyst pattern formation at early stage.
