Gene expression ratios during the larval development of Senegalese sole illustrating the ontogeny of chromatophores.

<p>The <i>asip/mc1r</i> ratio shows the relationship between these genes and reflects the pigmentation patterning of Senegalese sole during development. Its increase during post-metamorphosis coincided with the switch from the bilateral to the flat symmetry and with the appearance of iridophores in the skin of the ocular side. The <i>cKit</i>/<i>pax3</i> and <i>mitf</i>/<i>pax3</i> ratios indicate the regulation of <i>cKit</i> and <i>mitf</i> transcription by <i>pax3.</i> Note the initial positive regulation of both genes by <i>pax3</i> and the subsequent stabilization during the pro-metamorphosis period. The increase of both ratios at post-metamorphosis shows the activation of melanophore migration and melanin synthesis processes during this period. The <i>tyr/mitf</i> and <i>trp1/tyr</i> ratios display opposite profiles during development and correspond well to the melanin production periods. The peaks of <i>tyr/mitf</i> ratio reveal the activation of the melanin synthesis pathway, whereas those of <i>trp1/tyr</i> ratio show the production of melanin. Grey regions indicate the pro-metamorphosis stage.