Fig. 4

Serotonin biosynthesis in response to gut bacteria in B. dorsalis. a, b The efficacy of elimination of gut bacteria confirmed by culturing B. dorsalis gut homogenates on LB agar plates (a) and by performing PCR analysis (b) on gut homogenates using universal 16S rRNA gene primers. c–e Relative expression levels of BdTPH, BdTRH, and BdDuox in the gut of nonaxenic and axenic flies. f, g Gene abundance of BdTPH and BdDuox after the bacteria were introduced into the guts of antibiotic-treated flies. Two-tailed unpaired t-test was performed for c–g. Error bars indicate ± s.e.m., **p < 0.01, *p < 0.05, and ns means no significant difference. All results were repeated in at least two independent experiments, with three biological replicates