Comparison of the four predicted transcription unit collections of Buchnera. Four-way Venn diagram of the pairs classified as STUs (Same Transcription Unit, see Methods) by the different methods. No Buchnera gene pair was classified as STU by the MicrobesOnline and DOOR methods but as DTU (Different Transcription Units, see Methods) by the other two. Nor was any Buchnera gene pair classified as STU by the DisTer and BioCyc methods and as DTU by the other two. The number shown below the method name indicates the total number of Buchnera gene pairs classified as STU by the method.