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Fig. 3 | BMC Biology

Fig. 3

From: The Toll pathway underlies host sexual dimorphism in resistance to both Gram-negative and Gram-positive bacteria in mated Drosophila

Fig. 3

Phagocytosis, melanization, and the Imd pathway do not explain the sexual dimorphism. a The sexual dimorphism in survival to P. rettgeri is still present when hosts are not able to phagocytose bacteria. i Survival of flies lacking phagocytes compared to their genetic control after infection by P. rettgeri (OD = 0.1). Females of both lines were more susceptible than males and the lack of phagocytes did not affect the probability of surviving the infection (Cox-ph: Line: df = 1, χ2 = 1.01, P = 0.32; Sex: df = 1, χ2 = 18.41, P = 0.02; Line*Sex: df = 1, χ2 = 0.45, P = 0.50). ii P. rettgeri growth in flies lacking phagocytes and in their genetic control. Even if P. rettgeri was phagocytized, the bacterial growth was not significantly affected by this immune response neither in early time points (Linear regression: Line: df = 1, F = 0.28, P = 0.59; Time: df = 1, F = 577.82, P < 0.0001; Sex: df = 1, F = 3.63, P = 0.05; Time*Sex: df = 1, F = 0.0003, P = 0.99; Line*Sex: df = 1, F = 0.039, P = 0.84), nor at 10 days post-injection (Linear regression: Line: df = 1, F = 0.62, P = 0.43; Sex: df = 1, F = 20.36, P < 0.0001; Line*Sex: df = 1, F = 1.07, P = 0.3). b The sexual dimorphism in survival to P. rettgeri is still present when hosts are not able to melanize bacteria. i Black cell loss-of-function mutant (Cox-ph: Sex: df = 1, χ2 = 5.15, P = 0.02). ii Triple mutant PPO1Δ, 2Δ,31 loss-of-function (Cox-ph: Sex: df = 1, χ2 = 4.46, P = 0.03). c The sexual dimorphism in survival to P. rettgeri is still present when hosts are not able to induce an Imd response against bacteria. Females were more susceptible to P. rettgeri than males for the four mutants tested. i Imd loss-of-function mutant (Cox-ph: Sex: df = 1, χ2 = 156.24, P < 0.0001). ii Relish loss-of-function mutant (Cox-ph: Sex: df = 1, χ2 = 230.99, P < 0.0001). iii Double loss-of-function mutant PGRP-LC, PGRP-LE (Cox-ph: Sex: df = 1, χ2 = 71.9, P < 0.0001). iv P. rettgeri growth in Relish loss-of-function mutant. The infection started with the same number of bacteria in both sexes (Linear regression: Sex: df = 1, F = 1.02, P = 0.32). The bacterial populations have grown over time (Time: df = 1, F = 766.96, P < 0.0001) but the growth was significantly different between sexes (Time*Sex: df = 1, F = 5.32, P = 0.02). Imd response does not explain the sexual dimorphism in susceptibility to P. rettgeri

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