Distribution of stress hormone receptors in immune cells. This figure is derived from single-cell RNA sequencing data from adult zebrafish kidney samples, publicly available at https://molpath.shinyapps.io/zebrafishblood/#pltly (Tang et al., 2017). A) Clustering of single-cell RNA-seq data using tSNE2, shows distinct populations of immune cells, where macrophage populations express macrophage-expressed gene 1.1 (mpeg1.1) and neutrophil populations express myeloid-specific peroxidase (mpx). B) The gr (nr3c1) gene is globally expressed in all detected cells, while crhr1 is also expressed in neutrophils, macrophages, and T-cells, and mr (nr3c2), mc2r and crhr2 are expressed most highly in myeloid cells/macrophages, and in small amounts in other cell types.

Common zebrafish models to study stress and immune interactions. A. Knockout mutants exist in key receptors of the HPI axis, including a CRISPR-Cas9-generated (pink flags) mutant in the crhr1 gene, aTALEN-generated (purple flags) mutants in the mc2r gene, and 8 mutants in gr (nr3c1; ENU-(green flag), CRISPR-Cas9-, and TALEN-generated) and 7 mutants in mr (nr3c2; CRISPR-Cas9-/TALEN-generated) as well as an MR mutant in medaka (grey flag) (See also Table 1). B. Transgenic zebrafish lines with fluorescently labeled cell types of the innate and adaptive immune systems in zebrafish, in which a variety of fluorescent proteins are expressed under tissue-specific promoters for macrophages (mpeg/mfap4), neutrophils (mpx/lyz), and lymphocytes (lck).This figure was created using Biorender.com.