Structure (5´-3´) of the Horizontal Gene Transfer (HGT)-GIs representative of four marine bacteria. Genomes belonged to Cyanobacteria, Gammaproteobacteria, Alphaproteobacteria and marine Bacteroidetes. The hypothetical origin of HGT (via prophage, transposon or other MGE), the length of the GI (in kb) and the number of genes integrated are shown in brackets. Colors indicate the variety of genes observed within the GIs. Numbers in brackets under the genes indicate the HPs and other genes not considered for the figure.