Ed transposable regions for 20 of the genes, significantly lower than the 70 found in Nostoc sp. PCC7120 (2). This is partly because of the vast disparity in transposable elements in the two similarly sized genomes, with nearly 1,300 detected in Nostoc and only 500 in A. marina. Surprisingly, a large number of transposases and integrases in A. marina cluster together in regions with no detectabl