Figure 3
Bacterial genomes contain very few RT genes. A total of 96 completely sequenced bacterial genomes were searched by BLASTp on the comprehensive microbial resource at www.tigr.org. The two queries used were the LtrA RT from a Lactobacillus lactis group II intron (Q57005) and a retron RT from Escherichia coli (P23070). The number of BLAST hits with an E value <0.001 was tabulated for both queries, and the higher number was taken as the measure of RT gene number (visual inspection showed that this modestly inflated the number of RT genes as some of the low-scoring hits were false positives).
