Fig. 4: Imaging ARG expression by EcN in the GI tract in response to L-arabinose and thiosulfate.
From: Probiotic acoustic biosensors for noninvasive imaging of gut inflammation
a Experimental design for testing L-arabinose-inducible bARGSer expression in EcN in vivo. b Colony forming units (CFU) per gram of feces 1 day before and 1 and 3 days after administration of the EcN. LOD = limit of detection. c Representative 2-D images from scanning a mouse colonized by pBAD-bARGSer EcN where the BURST* image (hot scale) was thresholded and overlaid onto the B-mode image (greyscale). See Fig. S8a for the imaging setup. d Representative 3-D projection of the BURST*/B-mode images of a mouse colonized by pBAD-bARGSer EcN. See Supplementary Videos 1-2 for more views of the 3-D images. e Representative BURST*/B-mode images integrated over the depth on day 1. See Fig. S9a for images of all mice. f Integrated BURST* signal versus the distance from the ribs on day 1. g Representative ex vivo 2-D BURST*/B-mode images from scanning the GI tract of a mouse colonized by pBAD-bARGSer EcN. See Fig. S8b for the imaging setup. h Representative BURST*/B-mode images integrated over the width of intestines on day 3. Note that the pixels are not isotropic. See Fig. S9b for images of all intestines. i Integrated BURST* signal versus the length of the intestines relative to the cecum on day 3. j Experimental design for testing thiosulfate-sensing EcN strains in vivo. k Representative integrated BURST*/B-mode images of mice colonized by thiosulfate-sensing EcN one day after oral gavage of thiosulfate, or without any external thiosulfate for control mice. See Fig. S11 for images of all mice and colonization data. l Total BURST* ultrasound signal in mice colonized by L-arabinose-sensing (pBAD) or thiosulfate-sensing (thsSR) EcN strains with either bARGSer or GFP as the output. Asterisks represent statistical significance by two-tailed, unpaired Student’s t-tests (** = p < 0.01, *** = p < 0.001). p-values from left to right: 0.00120628, 0.0026301, 0.00078501. For b, f, i, and l, each point represents a biological replicate (N = 4 for all except N = 3 for thsSR-GFP in l) and lines represent the mean.
