Dynamic distribution of Salmonella in mouse gastrointestinal tracts. The wild type (WT, including OU5045 and OU5046 strains) and sipB-deletion mutants (including OU5045△sipB and OU5046△sipB strains) of S. Typhimurium were orally administrated into Balb/c mice. The bioluminescence signals from living mice as well as from their anatomic organs in parallel (lower part of each panel) were monitored at the first- (A), second- (B), fourth- (C), and 48th-hour (D) periods after Salmonella inoculations. The pictures were taken with 3-minute exposures via IVIS. The color bar is indicated beside each IVIS image.