Presence of a cerebral factor showing summer-morph-producing hormone activity in the brain of the seasonal non-polyphenic butterflies Vanessa cardui, V. indica and Nymphalis xanthomelas japonica (Lepidoptera: Nymphalidae) |
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Authors: | Ayuki Tanaka Moeko Inoue Katsuhiko Endo Chisato Kitazawa Akira Yamanaka |
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Affiliation: | Laboratory of Environmental Biology, Department of Physics, Biology and Informatics, Faculty of Science, Yamaguchi University, Yamaguchi, Japan;;Laboratory of Environmental Biology, Graduate School of Medicine, Yamaguchi University, Yamaguchi 753-8512, Japan;;Biological Institute, Faculty of Education, Yamaguchi University, Yamaguchi 753-8513, Japan |
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Abstract: | Three species of nymphalid butterflies, Vanessa cardui, V. indica and Nymphalis xanthomelas japonica , do not exhibit seasonal polyphenism in wing coloration. To determine whether seasonal non-polyphenic butterflies possess a cerebral factor affecting wing coloration, we used a Polygonia c-aureum female short-day pupal assay for detection of summer-morph-producing hormone (SMPH) activity in P. c-aureum. When 2% NaCl extracts of 25 brain-equivalents prepared from the pupal brains of V. cardui, V. indica or N. xanthomelas japonica were injected into Polygonia female short-day pupae, all recipients developed into summer-morph adults with dark-yellow wings, and the average grade score (AGS) of summer morphs showing SMPH activity was 3.8, 3.7 and 4.0, respectively. In contrast, when acetone or 80% ethanol extracts prepared from pupal brains were injected into Polygonia pupae, all recipients developed into autumn-morph adults with a dark-brown coloration and each exhibited an AGS of less than 0.5. Our results indicate that a cerebral factor showing SMPH activity is present in the pupal brain of seasonal non-polyphenic nymphalid butterflies, suggesting that a SMPH and cerebral factor showing SMPH activity occur widely among butterfly species. This finding will improve our understanding of the presence of cerebral factors showing interspecific actions of SHPH. |
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Keywords: | Nymphalis xanthomelas japonica seasonal non-polyphenic butterfly seasonal polyphenism summer-morph-producing hormone Vanessa cardui wing coloration |
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