Prophenoloxidase Activation Is Required for Survival to Microbial Infections in Drosophila
Figure 5
Increase of PO activity in absence of PPO2.
(A) Hemolymph PO activity in unchallenged and wounded adult flies. Spontaneous PO activity is abolished in PPO1Δ, PPO2Δ double mutant flies (***, p<0.0005) and strongly reduced in PPO1Δ mutants (**, p<0.005) compared to wild-type. In PPO2Δ deficient flies, a stronger PO activity is observed even in the absence of wounding (*, p<0.05). Adult flies were punctured and 3 h later their hemolymph was examined for PO activity. Hemolymph of wounded Bc flies and unchallenged Spn27A1 flies was used as control. Data were analyzed by t test and values represent the mean±s.e. of three independent experiments. (B) A representative Western Blot analysis using Drosophila anti-PPO1 (top) and anti-PPO2 (bottom) antibodies. Hemolymph samples were collected from adult flies subjected to injury contaminated with a mixture of Gram-positive Micrococcus luteus and Gram-negative Erwinia carotovora carotovora 15 (E. carotovora) bacteria. Absence of PPO1 and PPO2 in the respective single and double mutant flies is confirmed. Of note, higher levels of the mature form of PPO1 were observed in PPO2Δ mutants consistent with the notion that PPO2 negatively impacts PPO1. Hemolymph was extracted from flies 3 h post wounding.