Figure 9

Comparative illustration of genetic organization of nif operon in heterocyst-forming cyanobacteria. The gene organizations of nif operons in heterocyst-forming cyanobacteria are demonstrated in colour as nifH in purple, nifD in green, nifK in yellow and others in blue. Each excision element was indicated by a site-specific recombinase labelled in red and three dots that represent the remaining part of the element. The lengths of the excision elements are shown above