title: Functional analysis of insect molting fluid proteins on the protection and regulation of ecdysis.
abstract: Molting fluid accumulates between the old and new cuticles during periodical ecdysis in Ecdysozoa. Natural defects in insect ecdysis are frequently associated with melanization (an immunity response) occurring primarily in molting fluids, suggesting that molting fluid may impact immunity as well as affect ecdysis. To address this hypothesis, proteomic analysis of molting fluids from Bombyx mori during three different types of ecdysis was performed. Many proteins were newly identified, including immunity-related proteins, in each molting fluid. Molting fluids inhibited the growth of bacteria in vitro. The entomopathogenic fungi Beauveria bassiana, which can escape immune responses in feeding larvae, is quickly recognized by larvae during ecdysis, followed by melanization in molting fluid and old cuticle. Fungal conidia germination was delayed, and no hyphae were detected in the hemocoels of pharate instar insects. Molting fluids protect the delicate pharate instar insects with extremely thin cuticles against microorganisms. To explore the function of molting fluids in ecdysis regulation, based on protein similarity, 32 genes were selected for analysis in ecdysis regulation through RNAi in Tribolium castaneum, a model commonly used to study integument development because RNAi is difficult to achieve in B. mori. We identified 24 molting proteins that affected ecdysis after knockdown, with different physiological functions, including old cuticle protein recycling, molting fluid pressure balance, detoxification, and signal detection and transfer of molting fluids. We report that insects secrete molting fluid for protection and regulation of ecdysis, which indicates a way to develop new pesticides through interrupting insect ecdysis in the future.
authors.affiliation: From the Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China and.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.affiliation: From the Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China and.
authors.forename: Anrui
authors.initials: A
authors.lastname: Lu
authors.affiliation: the College of Agriculture and Biology, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China.
authors.forename: Lulu
authors.initials: L
authors.lastname: Kong
authors.affiliation: From the Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China and.
authors.forename: Qiaoli
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: From the Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China and erjunling@sippe.ac.cn ejling@sibs.ac.cn.
authors.forename: Erjun
authors.initials: E
authors.lastname: Ling
mesh_terms: D000818:Animals; D001412:Bacillus subtilis / Q000254:growth & development; D001826:Body Fluids / Q000502:physiology; D012831:Bombyx / Q000502:physiology*; D004156:Catechol Oxidase / Q000378:metabolism; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000378:metabolism; D004926:Escherichia coli / Q000254:growth & development; D007113:Immunity, Innate / Q000235:genetics; D019476:Insect Proteins / Q000502:physiology*; D007814:Larva / Q000502:physiology; D008543:Melanins / Q000378:metabolism; D018978:Molting; D010858:Pigmentation; D017382:Reactive Oxygen Species / Q000378:metabolism; D014231:Tribolium / Q000502:physiology
chemical_list: D004792:Enzyme Precursors; D019476:Insect Proteins; D008543:Melanins; D017382:Reactive Oxygen Species; C038451:pro-phenoloxidase; D004156:Catechol Oxidase
keywords: Bacteria; Epidermis; Fungi; Gene Silencing; Innate Immunity; Insect; Proteomics; Shedding