Figure 1. Injected E. coli are recognised and engulfed by embryonic hemocytes.

(A) An embryo expressing GFP specifically in the hemocytes shows their characteristic pattern of distribution whereby the cells are arranged into three parallel lines running along the ventral surface of a stage 15 embryo (arrows). (B) Embryo injected with fluorescently labelled E. coli in the anterior region of the embryo (asterisk). 20 minutes after injection hemocytes become labelled as they bind the injected bacteria (arrows). (C) Hemocytes within dscam⁰⁵⁵¹⁸ mutant embryos are able to recognize E. coli and can be seen to bind the fluorescently labelled bacteria (arrows) in a pattern indistinguishable from the wildtype. (D) Confocal images showing a series of optical slices taken through GFP expressing hemocytes. Images clearly show that the cells have internalised injected RFP labelled E .coli (arrows). (E) A projection of the slices shown in (D) highlight the two hemocytes (green) containing E .coli (red). (F) Z section taken through the region depicted by the dotted line on (E) clearly shows that the bacteria (red) are contained within the hemocyte (green). Arrows mark the cell extremities and correspond to the position of the arrows in (E). Scale bars represent 50 µm (A–C) and 10 µm (D and E).