title: Bmdelta phenotype implies involvement of Notch signaling in body segmentation and appendage development of silkworm, Bombyx mori.
abstract: The domesticated silkworm, Bombyx mori, belongs to the intermediate germband insects, in which the anterior segments are specified in the blastoderm, while the remaining posterior segments are sequentially generated from the cellularized growth zone. The pattern formation is distinct from Drosophila but somewhat resembles a vertebrate. Notch signaling is involved in the segmentation of vertebrates and spiders. Here, we studied the function of Notch signaling in silkworm embryogenesis via RNA interference (RNAi). Depletion of Bmdelta, the homolog of the Notch signaling ligand, led to severe defects in segment patterning, including a loss of posterior segments and irregular segment boundaries. The paired appendages on each segment were symmetrically fused along the ventral midline in Bmdelta RNAi embryos. An individual segment seemed to possess only one segmental appendage. Segmentation in prolegs could be observed. Our results show that Notch signaling is employed in not only appendage development but also body segmentation. Thus, conservation of Notch-mediated segmentation could also be extended to holometabolous insects. The involvement of Notch signaling seems to be the ancestral segmentation mechanism of arthropods.
authors.affiliation: Department of Pharmaceutical and Biological Engineering, School of Chemical Engineering, Sichuan University, No. 24 South Section 1, Yihuan Road, Chengdu 610065, PR China. wbliu@scu.edu.cn
authors.forename: Wenbin
authors.initials: W
authors.lastname: Liu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019521:Body Patterning; D012831:Bombyx / Q000196:embryology* / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D034622:RNA Interference; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction
chemical_list: D019476:Insect Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D051880:Receptors, Notch; C064045:delta protein