Counteracting role of Ctl24 to LysC.
(A) Expression profiles of 34 C-type lectins in the intestines after oral treatment with muropeptides. Muropeptides (10 μg) were introduced into intestines. Gene expression was detected by qRT-PCR 6 h later. (B) Influence of the abundance of intestinal total bacteria by knockdown of responsive Ctls. The bacterial abundance was determined by detecting 16S rDNA using qPCR 4 d after RNAi. (C) Influence of the abundance of intestinal total bacteria by Ctl24 knockdown. The abundance was determined using the plate-counting method. (D) Facilitating colonization of commensal bacteria P. damselae by rCtl24 in axenic intestines. Antibiotic-treated shrimp were orally delivered with a mixture containing 2 μg of rCtl24 and 1 × 105 CFU of P. damselae. The bacterial amount was quantified 48 h later by detecting the ToxR gene using qPCR. (E) Influence of the abundance of intestinal bacteria by overexpression of rLysC, or rLysC and rCtl24. The bacterial abundance in intestine was determined by detecting 16 S rDNA using qPCR 3 d later protein (2 μg) administration. (F) Regulation of Ctl24 expression by LysC overexpression or knockdown. Ctl24 expression in intestine was detected 12 h after rLysC (2 μg) administration, or 24 h after LysC RNAi. (G) Expression of Ctl24 after FoxO or Relish knockdown and muropeptides challenge. Muropeptides (5μg) were introduced into intestines at 24 h after dsRNA application. Gene expression was detected another 6 h later. All bar charts show the mean ± SD from three replicates. The images are representative of three repeats. One dot represents one shrimp in the scatter graphs. Statistical analysis was performed using the Students’ t test. *, 0.01 < p < 0.05; **, 0.001 < p < 0.01; ***, p < 0.001.