scRNA-seq analysis of zebrafish kidney marrow. A UMAP plot of 57,094 kidney marrow cells from four adult zebrafish. B Heatmap showing specific marker genes in each cell cluster. C Dot plot of average expression of selected markers and the respective percentages of cluster-expressing cells. Dot size represents the percentage of cells in the cluster expressing a given marker gene and dot color reflects the average expression of the gene in the respective cluster. D Fraction of each cell cluster in WT and creg1−/− fish. E Tissue preference for each cell cluster estimated by Ro/e

Comparative analysis of B cells between WT and creg1−/− fish. A Volcano diagram showing the DEGs in B cells between WT and creg1−/− fish. B KEGG pathway enrichment analysis of DEGs in B cells between WT and creg1−/− fish. C FACS analysis of U2932 cell apoptosis via Annexin V/PI staining. D Quantification of the percentage of Annexin V-positive U2932 cells of C. E FACS analysis of U2932 cell endocytosis via TRITC-dextran staining. F Quantitative analysis of TRITC-dextran mean fluorescence intensity (MFI) of E. G FACS analysis of U2932 cell lysosomal activity via LysoTracker Red staining. H Quantitative analysis of LysoTracker Red MFI of G. I UMAP plot showing unsupervised subclustering of B cells from both WT and creg1−/− kidney marrow. J, K Pseudotime trajectory analysis of B subclusters. L Fraction of each subcluster of B cells between WT and creg1−/− fish. Data shown are the mean ± SEM. Statistical significance was calculated using the Student's t-test. ***p < 0.001; ****p < 0.0001

Comparative analysis of T/NK cells between WT and creg1−/− fish. A Volcano diagram showing the DEGs in T/NK cells between WT and creg1−/− fish. B KEGG pathway enrichment analysis of DEGs in T/NK cells between WT and creg1−/− fish. C FACS analysis of Jurkat cell apoptosis via Annexin V/PI staining. D Quantification of the percentage of Annexin V-positive Jurkat cells of C. E FACS analysis of Jurkat cell endocytosis via TRITC-dextran staining. F Quantitative analysis of TRITC-dextran MFI of E. G UMAP plot showing unsupervised subclustering of T/NK cells from both WT and creg1−/− kidney marrow. H Fraction of each subcluster of T/NK cells between WT and creg1−/− fish. I, J Pseudotime trajectory analysis of T/NK subclusters. K Violin plot showing the expression of ptprc in T/NK cells between WT and creg1−/− fish. Data shown are the mean ± SEM. Statistical significance was calculated using the Student's t-test. **p < 0.01; ***p < 0.001; ****p < 0.0001

Comparative analysis of erythroid cells between WT and creg1−/− fish. A Volcano diagram showing the DEGs in erythroid cells between WT and creg1−/− fish. B Violin plots showing the expression of alas2, slc4a1a, hbba1, hbba2, hbaa1, and hbaa2 in erythroid cells between WT and creg1−/− fish. C KEGG pathway enrichment analysis of DEGs in erythroid cells between WT and creg1−/− fish. D UMAP plot showing unsupervised subclustering of erythroid cells from both WT and creg1−/− kidney marrow. E, F Pseudotime trajectory analysis of erythroid cell subclusters. G Fraction of each subcluster of erythroid cells between WT and creg1−/− fish