Monitoring of L-arabinose-induced bacterial lysis by a non-invasive <i>in vivo</i> imaging system (IVIS) and release of β-galactosidase from <i>Salmonellae</i> carrying pLYS<i>P_BAD</i>::<i>lacZ</i> or pBAD24<i>P_BAD::lacZ</i> targeted to implanted tumor tissue (CT26) in BalB/c mice.

<p>Each time point represents the mean for n = 3 animals. (A) Bioluminescent bacteria (SKS003) carrying pLYS were injected intravenously into CT26 tumor-bearing mice. After three days, the bioluminescence signal from the <i>Salmonellae</i> was monitored by a non-invasive <i>in vivo</i> imaging system (IVIS) at the indicated times after intraperitoneal injection of L-arabinose (60 mg) in the induced group. The Y-axis indicates photons ×10^5·s^−1·cm^−2·sr⁻¹. The ROI was selected manually for quantification of photon flux. The ROI area was kept constant, and the intensity was recorded as a maximum (photons ×10^5·s^−1·cm^−2·sr⁻¹) within the ROI. (B) Photons from each mouse at 0 time was calculated 100% and compared. Data represent mean ± S.D., and asterisks (*) indicate a significant difference compared between uninduced and induced group (***, P<0.0001). (C) The number of live bacteria in the tumor tissue 8 hrs after the addition of L-arabinose was determined by CFU counting. (D) The tumor tissues were analyzed for the expression and distribution of β-galactosidase by histochemical staining with X-gal.