B-cell ontogeny in IgM1:eGFP fish. (A) Kidneys were isolated from adult rag2:DsRed;IgM1:eGFP fish and analyzed by flow cytometry. The GFP/DsRed profile of cells in the combined lymphocyte and precursor gates is shown. The indicated populations were sorted from the fish and analyzed by qRT-PCR. (B) Average expression plus SD of rag2, IgM, IgZ, or pax5 relative to ef1α (ΔCt) for the indicated cell populations from 3 individual fish is shown.