AUTHOR=Banerjee Tirtha Das , Finet Cédric , Seah Kwi Shan , Monteiro Antónia 

TITLE=Optix regulates nanomorphology of butterfly scales primarily via its effects on pigmentation

JOURNAL=Frontiers in Ecology and Evolution

VOLUME=12

YEAR=2024

URL=https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2024.1392050

DOI=10.3389/fevo.2024.1392050

ISSN=2296-701X

ABSTRACT=<p>Previous studies have shown that <italic>Optix</italic> regulates lower lamina thickness and the type of pigment that is produced in wing scales of a few butterfly species. However, the role of <italic>Optix</italic> in regulating pigment production across species, and in regulating additional aspects of scale morphology remains to be investigated. By combining microspectrophotometry, scanning electron microscopy, and focused ion beam technology on wild-type and <italic>Optix Bicyclus anynana</italic> crispants, we show that <italic>Optix</italic> regulates the production of orange pigments (ommochromes), represses the production of brown pigments (melanins), and regulates the morphology of the lower and upper surface of orange scales. Our findings suggest a conserved role of <italic>Optix</italic> as a switch gene that activates ommochrome and represses melanin synthesis across butterflies. By comparing these effects with other mutations, where only melanin is removed from scales, we propose that pigmentary changes, alone, affect the way that chitin polymerizes within a scale, changing lower lamina thickness as well as multiple intricate structures of the upper surface.</p>