title: Characterization of silk gland ribosomes from a bivoltine caddisfly, Stenopsyche marmorata: translational suppression of a silk protein in cold conditions.
abstract: Larval Stenopsyche marmorata constructs food capture nets and fixed retreats underwater using self-produced proteinaceous silk fibers. In the Chikuma River (Nagano Prefecture, Japan) S. marmorata has a bivoltine life cycle; overwintering larvae grow slowly with reduced net spinning activity in winter. We recently reported constant transcript abundance of S. marmorata silk protein 1 (Smsp-1), a core S. marmorata silk fiber component, in all seasons, implying translational suppression in the silk gland during winter. Herein, we prepared and characterized silk gland ribosomes from seasonally collected S. marmorata larvae. Ribosomes from silk glands immediately frozen in liquid nitrogen (LN2) after dissection exhibited comparable translation elongation activity in spring, summer, and autumn. Conversely, silk glands obtained in winter did not contain active ribosomes and Smsp-1. Ribosomes from silk glands immersed in ice-cold physiological saline solution for approximately 4 h were translationally inactive, despite summer collection and Smsp-1 expression. The ribosomal inactivation occurs because of defects in the formation of 80S ribosomes, presumably due to splitting of 60S subunits containing 28S rRNA with central hidden break, in response to cold stress. These results suggest a novel-type ribosome-regulated translation control mechanism.
authors.affiliation: Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, Ueda 386-8567, Japan. Electronic address: nomurat@shinshu-u.ac.jp.
authors.forename: Takaomi
authors.initials: T
authors.lastname: Nomura
authors.affiliation: Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, Ueda 386-8567, Japan.
authors.forename: Miho
authors.initials: M
authors.lastname: Ito
authors.affiliation: Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, Ueda 386-8567, Japan.
authors.forename: Mai
authors.initials: M
authors.lastname: Kanamori
authors.affiliation: Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, Ueda 386-8567, Japan.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Shigeno
authors.affiliation: Department of Biology, Faculty of Science, Niigata University, Niigata 950-2181, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Uchiumi
authors.affiliation: Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, Ueda 386-8567, Japan; Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Matsumoto 390-8621, Japan.
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Arai
authors.affiliation: Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, Ueda 386-8567, Japan.
authors.forename: Masuhiro
authors.initials: M
authors.lastname: Tsukada
authors.affiliation: Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, Ueda 386-8567, Japan; Institute of Mountain Science, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Minamiminowa, Nagano 399-4598, Japan.
authors.forename: Kimio
authors.initials: K
authors.lastname: Hirabayashi
authors.affiliation: Institute for Fiber Engineering, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Ueda 386-8567, Japan.
authors.forename: Kousaku
authors.initials: K
authors.lastname: Ohkawa
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D003080:Cold Temperature; D005088:Exocrine Glands / Q000502:physiology; D019476:Insect Proteins / Q000235:genetics*; D014176:Protein Biosynthesis / Q000235:genetics*; D012270:Ribosomes / Q000235:genetics*; D047011:Silk / Q000235:genetics*; D013489:Suppression, Genetic / Q000235:genetics*
chemical_list: D019476:Insect Proteins; D047011:Silk
keywords: Annupalpia; Hidden break; Ribosome; Stenopsyche marmorata; Translation control; Trichoptera