title: Molting-associated suppression of symbiont population and up-regulation of antimicrobial activity in the midgut symbiotic organ of the Riptortus-Burkholderia symbiosis.
abstract: The majority of insects possess symbiotic bacteria. Since symbiont titers can affect host phenotypes of biological importance, host insects are expected to evolve some mechanisms for regulating symbiont population. Here we report that, in the Riptortus-Burkholderia gut symbiosis, titers of the beneficial symbiont transiently decrease at the pre-molt stages in host development. This molting-associated suppression of the symbiont population is coincident with the increase of antimicrobial activity in the symbiotic midgut, which is observed in both symbiotic and aposymbiotic insects. Two genes, pyrrhocoricin-like antimicrobial peptide and c-type lysozyme, exhibit significantly increased expression in the symbiotic midgut at the pre-molt stages. These results suggest that the molting-associated up-regulation of antimicrobial activity in the symbiotic midgut represents a physiological mechanism of the host insect to regulate symbiosis, which is presumably for defending molting insects against injury and infection and/or for allocating symbiont-derived energy and resources to host molting.
authors.affiliation: Global Research Laboratory of Insect Symbiosis, College of Pharmacy, Pusan National University, Pusan 609-735, South Korea.
authors.forename: Jiyeun Kate
authors.initials: JK
authors.lastname: Kim
authors.affiliation: Global Research Laboratory of Insect Symbiosis, College of Pharmacy, Pusan National University, Pusan 609-735, South Korea.
authors.forename: Sang Heum
authors.initials: SH
authors.lastname: Han
authors.affiliation: Global Research Laboratory of Insect Symbiosis, College of Pharmacy, Pusan National University, Pusan 609-735, South Korea.
authors.forename: Chan-Hee
authors.initials: CH
authors.lastname: Kim
authors.affiliation: Division of Plant Biotechnology, College of Agriculture and Life Science, Chonnam National University, Gwangju 500-757, South Korea.
authors.forename: Yong Hun
authors.initials: YH
authors.lastname: Jo
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8566, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Futahashi
authors.affiliation: National Institute of AIST, Hokkaido Center, Sapporo 062-8517, Japan.
authors.forename: Yoshitomo
authors.initials: Y
authors.lastname: Kikuchi
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8566, Japan.
authors.forename: Takema
authors.initials: T
authors.lastname: Fukatsu
authors.affiliation: Global Research Laboratory of Insect Symbiosis, College of Pharmacy, Pusan National University, Pusan 609-735, South Korea. Electronic address: brlee@pusan.ac.kr.
authors.forename: Bok Luel
authors.initials: BL
authors.lastname: Lee
mesh_terms: D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000235:genetics / Q000378:metabolism*; D005075:Biological Evolution; D019117:Burkholderia / Q000502:physiology*; D019121:Burkholderia Infections / Q000276:immunology*; D041981:Gastrointestinal Tract / Q000276:immunology* / Q000382:microbiology*; D006430:Hemiptera / Q000502:physiology*; D007109:Immunity; D018978:Molting / Q000276:immunology; D013559:Symbiosis; D015854:Up-Regulation / Q000276:immunology
chemical_list: D023181:Antimicrobial Cationic Peptides
keywords: Antimicrobial activity; Burkholderia symbiont; Gut symbiosis; Insect molting; Riptortus pedestris