Fig. 1

VD₃ promotes the granulopoiesis in zebrafish larvae. Zebrafish larvae at 2 dpf were exposed to 100 nM VD₃ for 2 days, GZM was replaced at 4 dpf, and 100 nM VD₃ were added simultaneous. a The merged images of Tg(mpx:gfp) zebrafish (6 dpf) showed the abundance and localization of GFP⁺ neutrophils. White dashed line indicates the intestine. b The size of neutrophil population was represented by neutrophil unit as described in Materials and Methods. Graph shows quantification of neutrophil units in whole zebrafish larva at 6 dpf. c Enumeration of intestinal-associated GFP⁺ cells in 6 dpf larvae. d The gene expression by qRT-PCR of csf3a, csf3b, mpx, lysc, and mmp9 from 6 dpf zebrafish larvae treated with 0 or 100 nM VD₃ for 4 days (results are combined from 2 independent experiments, n = 4 replicates/group/experiment, 10–20 larvae/replicate). Data are represented as mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001. VD₃, vitamin D₃; dpf, days post fertilization; mpx, myeloperoxidase; csf3a, colony-stimulating factor 3a; csf3b, colony-stimulating factor 3b; lysc, lysozyme C; mmp9, matrix metalloproteinase9; GZM, gnotobiotic zebra­fish medium.