Long-Range Activation of Systemic Immunity through Peptidoglycan Diffusion in Drosophila
Figure 5
TCT is sufficient to induce an immune response and is translocated into the haemolymph.
(A–C) RT-qPCR analysis of Dpt expression following deposition on the genital plate of live or dead Ecc15 (A), PGN and TCT compared to Ecc15 (B) or PGN extracted from various bacterial species compared to PBS (C). Data are means of three repeats, error bars are standard errors. UC: Unchallenged, M.lut.: M. luteus, B.sub.: B. subtilis, Ecc15: E. carotovora, P.ent. : P. entomophila. The Dpt/rpL32 ratio is shown normalised to expression in flies 6h after genital challenge with either live Ecc15 (A,B) or with Ecc15 PGN (C). Wild-type (Oregon R) flies were used, except in B, where the flies used were the progeny of da-Gal4 crossed to w1118. (D) [14C] labelled TCT was deposited on the genital plates of flies and haemolymph extracted two hours later. This experiment was repeated three times. Depicted is a representative scan of a phosphor-imager screen exposed to filter papers containing: Upper panel: 1µL drops of serial 1/10 dilutions of the [14C]-TCT solution deposited on the flies. There is signal saturation in the 10−1 drop. Lower panel: Haemolymph of unchallenged flies (UC) or flies where [14C]-TCT was deposited on the genital plate (TCT). The dashed lines represent the form of the filter papers. (E) Quantification of [14C] present in extracted haemolymph. Raw data were obtained as a percentage of the intensity of the 10−2 drop, and are presented here as the quantity of TCT (pmol) calculated from the known concentration of the [14C]-TCT source and the volume used to infect flies. Data shown are the mean of 3 repeats, error bars show standard error.