title: Key patterning genes contribute to leg elongation in water striders.
abstract: BACKGROUND
  How adaptive phenotypes are shaped by the action of key developmental genes during ontogeny remains poorly understood. Water striders, a group of hemipteran insects, present a unique example of adaptation to life on the fluid water surface substrate. The group has undergone a set of leg modifications allowing them to efficiently move on the water surface and hence invade a variety of niches from ponds to open oceans. The elongated legs of water striders play a key role in generating efficient movement on the fluid by acting as propelling oars.
  
  
  RESULTS
  To determine the developmental mechanisms underlying leg elongation, we examined the function of the key developmental genes decapentaplegic (dpp), wingless (wg), epidermal growth factor receptor (egfr), and hedgehog (hh) during embryonic development in the water strider Limnoporus dissortis. By analyzing expression patterns and RNAi knockdown phenotypes, we uncover the role of these genes in leg growth and patterning during embryogenesis. Our results indicate that wg and egfr contribute to the elongation of all the three segments of all thoracic legs, whereas hh specifies distal leg segments.
  
  
  CONCLUSIONS
  Together, our results suggest that key patterning genes contribute to the dramatic elongation of thoracic appendages in water striders.
authors.affiliation: Institut de Génomique Fonctionnelle de Lyon, CNRS-UMR5242, Ecole Normale Supérieure de Lyon, Université de Lyon, Université Claude Bernard Lyon 1, 46 Allée d'Italie, 69364 Lyon, Cedex 07 France.
authors.forename: Peter Nagui
authors.initials: PN
authors.lastname: Refki
authors.affiliation: Institut de Génomique Fonctionnelle de Lyon, CNRS-UMR5242, Ecole Normale Supérieure de Lyon, Université de Lyon, Université Claude Bernard Lyon 1, 46 Allée d'Italie, 69364 Lyon, Cedex 07 France.
authors.forename: Abderrahman
authors.initials: A
authors.lastname: Khila
keywords: Developmental genes; Growth; Leg length; Pattern formation; Water striders