title: Distal-less induces elemental color patterns in Junonia butterfly wings.
abstract: BACKGROUND
  The border ocellus, or eyespot, is a conspicuous color pattern element in butterfly wings. For two decades, it has been hypothesized that transcription factors such as Distal-less (Dll) are responsible for eyespot pattern development in butterfly wings, based on their expression in the prospective eyespots. In particular, it has been suggested that Dll is a determinant for eyespot size. However, functional evidence for this hypothesis has remained incomplete, due to technical difficulties.
  
  
  RESULTS
  Here, we show that ectopically expressed Dll induces ectopic elemental color patterns in the adult wings of the blue pansy butterfly, Junonia orithya (Lepidoptera, Nymphalidae). Using baculovirus-mediated gene transfer, we misexpressed Dll protein fused with green fluorescent protein (GFP) in pupal wings, resulting in ectopic color patterns, but not the formation of intact eyespots. Induced changes included clusters of black and orange scales (a basic feature of eyespot patterns), black and gray scales, and inhibition of cover scale development. In contrast, ectopic expression of GFP alone did not induce any color pattern changes using the same baculovirus-mediated gene transfer system.
  
  
  CONCLUSIONS
  These results suggest that Dll plays an instructive role in the development of color pattern elements in butterfly wings, although Dll alone may not be sufficient to induce a complete eyespot. This study thus experimentally supports the hypothesis of Dll function in eyespot development.
authors.affiliation: The BCPH Unit of Molecular Physiology, Department of Chemistry, Biology and Marine Science, University of the Ryukyus, Okinawa, 903-0213 Japan.
authors.forename: Bidur
authors.initials: B
authors.lastname: Dhungel
authors.affiliation: The BCPH Unit of Molecular Physiology, Department of Chemistry, Biology and Marine Science, University of the Ryukyus, Okinawa, 903-0213 Japan.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Ohno
authors.affiliation: The BCPH Unit of Molecular Physiology, Department of Chemistry, Biology and Marine Science, University of the Ryukyus, Okinawa, 903-0213 Japan.
authors.forename: Rie
authors.initials: R
authors.lastname: Matayoshi
authors.affiliation: The BCPH Unit of Molecular Physiology, Department of Chemistry, Biology and Marine Science, University of the Ryukyus, Okinawa, 903-0213 Japan.
authors.forename: Mayo
authors.initials: M
authors.lastname: Iwasaki
authors.affiliation: The BCPH Unit of Molecular Physiology, Department of Chemistry, Biology and Marine Science, University of the Ryukyus, Okinawa, 903-0213 Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Taira
authors.affiliation: The BCPH Unit of Molecular Physiology, Department of Chemistry, Biology and Marine Science, University of the Ryukyus, Okinawa, 903-0213 Japan.
authors.forename: Kiran
authors.initials: K
authors.lastname: Adhikari
authors.affiliation: The BCPH Unit of Molecular Physiology, Department of Chemistry, Biology and Marine Science, University of the Ryukyus, Okinawa, 903-0213 Japan.
authors.forename: Raj
authors.initials: R
authors.lastname: Gurung
authors.affiliation: The BCPH Unit of Molecular Physiology, Department of Chemistry, Biology and Marine Science, University of the Ryukyus, Okinawa, 903-0213 Japan.
authors.forename: Joji M
authors.initials: JM
authors.lastname: Otaki
keywords: Butterfly wing; Color pattern; Distal-less; Eyespot; GFP; Junonia orithya