title: Functional conservation and divergence of BMP ligands in limb development and lipid homeostasis of holometabolous insects.
abstract: Bone morphogenetic protein (BMP) ligands play key roles in regulating morphological and physiological traits. To investigate how the functions of BMP ligands have evolved among insects, the roles of two key BMP ligands, decapentaplegic (dpp) and glass bottom boat (gbb), were studied in the flour beetle, Tribolium castaneum. RNA interference-mediated knockdown revealed that the role of dpp in establishing limb segmentation is conserved among insects. Based on the expression pattern of dpp in the presumptive leg tarsal segments, we propose that the function of dpp has evolved through heterochronic changes during the evolution of complete metamorphosis. Gbb1 was found to be necessary for sculpting the tarsal segment morphology characteristic of beetles. Knockdown of Dpp and Gbb1 expression also resulted in transparent larvae and reduced triglyceride levels, indicating their critical roles in maintaining lipid homeostasis. Both knockdown phenotypes were mediated by larval translucida. Because only Gbb regulates lipid metabolism in Drosophila, regulation of lipid homeostasis appears to have evolved by developmental systems drift. Thus, developmental systems drift may underlie evolution of both morphology and physiological processes.
authors.affiliation: Department of Biological Sciences, Wellesley College, 106 Central St., Wellesley, MA 02481, USA.
authors.forename: Erica K O
authors.initials: EK
authors.lastname: Namigai
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Suzuki
mesh_terms: D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D019143:Evolution, Molecular; D005121:Extremities / Q000033:anatomy & histology / Q000254:growth & development*; D015870:Gene Expression; D006706:Homeostasis; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D007814:Larva / Q000235:genetics / Q000378:metabolism; D008024:Ligands; D034741:RNA, Small Interfering; D014231:Tribolium / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D014280:Triglycerides / Q000378:metabolism*
chemical_list: D019485:Bone Morphogenetic Proteins; D019476:Insect Proteins; D008024:Ligands; D034741:RNA, Small Interfering; D014280:Triglycerides