Fig. 11.

Model for ATP- and GTP-specific developmental pathways during zebrafish embryogenesis. IMP feeds into the ATP and GTP pathways. The ATP pathway facilitates retinoblast proliferation and S-phase exit. The GTP pathway facilitates pigment synthesis: guanine in iridophores, sepiapterin in xanthophores and eumelanin in melanosomes/melanocytes (Le Guyader et al., 2005; Ziegler, 2003). Iridophore pathways are shaded light gray, xanthophore pathways are shaded yellow and melanophore/RPE pathways are shaded dark gray. Enzymes are in red, except those targeted by morpholinos, which are green.