Fig 4. Parasite distribution in the mosquito midgut.

Parasite positions within the cellular layer calculated relative to the distance of each parasites to the nuclei of surrounding midgut cells. a. Calculations of the distance of parasites from the nuclei of the nearest neighboring midgut cell. The score (s) determine whether the parasite is intercellular (0.45 ≤ s ≤ 0.55), extracellular (s < 0.45), or intracellular (s>0.55). Example images from a z stack, scale bar = 20 μm: (I) s = 0.74, the parasite (green arrow) is intracellular; (II) s = 0.45 (red arrow) the parasite is intercellular and (III) s = 0.36, the parasite is extracellular (blue arrow). b. Schematic representation of parasite (red) and nuclei (blue) positions with distances (green lines) used to calculate distances from the nuclei. c. Positions of parasites within the cell layer in A. stephensi (As), A. gambiae (Ag) and A. gambiae mosquitoes silenced for TEP1 (A. gambiae^TEP1KD). The table indicates the percentage of parasites at each position for each mosquito. The number (n) indicates the number of midguts analyzed for each mosquito genotype. d. Comparison of the proportion of intercellular parasites between As, Ag and Ag^TEP1KD. Each dot represents the proportion of parasites detected between cells in a single midgut. Midguts (n) with at least six parasites within the cellular layer were used for analyses. Statistically significant differences between As and Ag and between Ag and Ag^TEP1KD revealed by a non-parametric Mann-Whitney t-test are indicated by asterisks (*—P = 0.03; **—P = 0.003). The table details the mean proportions of parasites in each midgut and for each position for n mosquitoes.