Evolution

Redox Dragonflies

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Science  10 Aug 2012:
Vol. 337, Issue 6095, pp. 624
DOI: 10.1126/science.337.6095.624-a
CREDIT: EJATGC/WIKIMEDIA COMMONS

Animals exhibit beautiful and varied color patterns that assist in species and gender recognition and avoiding detection. Sexual maturity is also signaled by color change in insects, birds, and mammals. In dragonflies of the genera Crocothemis and Sympetrum, the male displays yellow body coloration when young but is bright red when sexually mature. Futahashi et al. reveal that the redox state of epidermal ommochrome pigments confers this sex-related change. When the ratio of the reduced form to the oxidized form is higher, as in adult males, red color results. Females and immature males, which are yellow, have a lower ratio. When reductant or oxidant was added to extracted dragonfly pigments in vitro, color transitions were observed. In addition, reductant injected into immature males and mature females resulted in a change to the vivid red seen in adult males. These results extend our knowledge of the role of oxidants and reductants in regulating animal pigmentation, as previously shown in fruit flies and butterflies.

Proc. Natl. Acad. Sci. U.S.A. 109, 10.1073/pnas.1207114109 (2012).

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