Figure 1.

Bioluminescent imaging allows precise sampling of Giardia foci in the proximal small intestine for transcriptomic analyses. A cohort of four mice were infected with one million trophozoites by gavage of the P_GDH-FLuc Giardia strain (Barash et al., 2017b). Whole body images were non-invasively collected for parasite bioluminescence from the constitutive P_GDH-FLuc bioreporter (A), and mice were subsequently sacrificed at 3 or 7 days post-infection (p.i.). Image overlays display the P_GDH-FLuc bioluminescence intensity, with the highest signal intensity shown in red and the lowest in blue. The colored radiance scale indicates the photon flux (p/s/cm²/sr) for each intestinal segment. Ex vivo imaging defined four foci in the proximal small intestine (yellow numbered boxed regions) subsequently excised for transcriptomic sequencing and analysis (A). In the schematic, regions of the gastrointestinal tract are marked as: S, stomach; pSI, proximal small intestine; dSI, distal small intestine; CEC, cecum; and LI, large intestine, with the positions of the Giardia foci (ROI1-ROI4) within the excised fragments in red. In (B), the enrichment of Giardia trophozoites (white arrows) in a representative bioluminescent small intestinal sample was verified using light microscopy of histological sections. (C) Summarizes the total transcriptomic reads for each in vitro culture replicate (TYDK) and for each transcriptomic sample (ROI1-ROI4) from the proximal small intestine (pSI). The total reads include those from the host (mouse) before the Giardia reads were computationally mapped to the Giardia genome. The total flux (p/s/cm²/sr) was quantified for that particular sample. The overall transcriptomic analysis is summarized in (D) (DE = differentially expressed).