Figure 7. Selective effects of diapause conditions on expression of innate immune genes.

The relative expression of four immune genes was determined in six groups of female Canton S flies: virgin 3–6 h old flies (C0), one week old uninfected and non-diapausing flies (C1), uninfected flies kept for 3 weeks either at 11°C and 10L:14D (diapause, D3) or at 25°C and 12L:12D, (normal conditions, N3) and infected flies (cross hatched bars) kept under diapause (D3) or non-diapause conditions (N3) for 3 weeks. Infected flies were injected with a suspension of Micrococcus luteus and Escherichia coli and kept for an additional 3 hours before freezing and RNA extraction. Data are presented as means ± S.E.M, n = 3–4 replicates with 10–15 flies in each. Significance compared to the newly hatched control (C1) which was set at one, or as indicated by connectors: * p<0.05, ** p<0.01, *** p<0.001, N.S. – not significant (ANOVA followed with Tukey test) or ^# p<0.05, ^## p<0.01 (Kruskal–Wallis test followed by pairwise comparisons using Wilcoxon rank sum test). A The Drosomycin expression was significantly upregulated in flies diapausing for 3 weeks (D3) in both infected and uninfected flies compared to non-diapausing 1-week old (C1) and 3-week old flies (N3). Infection further increased transcripts in both N3 and D3 flies. B Cecropin A1 was significantly upregulated during diapause (D3) versus normal conditions (C1), but not N3, in uninfected flies only if comparing C1 to D3. Infection drastically increased transcripts in both diapausing and nondiapausing flies. C The peptidoglycan recognition protein SB1 (PGRP-SB1) transcript level are not affected by diapause, only infection increased it. D Diptericin also increased only due to infection. For the investigated immune genes we did not find a differences in expression levels between 1-week old (C1) and newly eclosed (C0) flies. Similar results were obtained with flies that were reared on food supplemented with antibiotics (see Fig. S2 in File S1).