title: Joint morphology in the insect leg: evolutionary history inferred from Notch loss-of-function phenotypes in Drosophila.
abstract: Joints permit efficient locomotion, especially among animals with a rigid skeleton. Joint morphologies vary in the body of individual animals, and the shapes of homologous joints often differ across species. The diverse locomotive behaviors of animals are based, in part, on the developmental and evolutionary history of joint morphogenesis. We showed previously that strictly coordinated cell-differentiation and cell-movement events within the epidermis sculpt the interlocking ball-and-socket joints in the adult Drosophila tarsus (distal leg). Here, we show that the tarsal joints of various insect species can be classified into three types: ball-and-socket, side-by-side and uniform. The last two probably result from joint formation without the cell-differentiation step, the cell-movement step, or both. Similar morphological variations were observed in Drosophila legs when Notch function was temporarily blocked during joint formation, implying that the independent acquisition of cell differentiation and cell movement underlay the elaboration of tarsal joint morphologies during insect evolution. These results provide a framework for understanding how the seemingly complex morphology of the interlocking joint could have developed during evolution by the addition of simple developmental modules: cell differentiation and cell movement.
authors: Laboratory for Morphogenetic Signaling, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan. rtajiri1@gmail.com
authors: Reiko
authors: R
authors: Tajiri
authors: Kazuyo
authors: K
authors: Misaki
authors: Shigenobu
authors: S
authors: Yonemura
authors: Shigeo
authors: S
authors: Hayashi
mesh_terms: D000818:Animals; D001181:Arthropods / Q000033:anatomy & histology* / Q000145:classification / Q000502:physiology; D005075:Biological Evolution; D002454:Cell Differentiation / Q000502:physiology; D004330:Drosophila / Q000033:anatomy & histology* / Q000145:classification / Q000502:physiology; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D005121:Extremities; D007313:Insecta / Q000033:anatomy & histology* / Q000145:classification / Q000502:physiology; D007596:Joints / Q000033:anatomy & histology / Q000502:physiology; D010641:Phenotype; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism*
chemical_list: D029721:Drosophila Proteins; C497759:N protein, Drosophila; D051880:Receptors, Notch