title: Gut pathology and responses to the microsporidium Nosema ceranae in the honey bee Apis mellifera.
abstract: The microsporidium Nosema ceranae is a newly prevalent parasite of the European honey bee (Apis mellifera). Although this parasite is presently spreading across the world into its novel host, the mechanisms by it which affects the bees and how bees respond are not well understood. We therefore performed an extensive characterization of the parasite effects at the molecular level by using genetic and biochemical tools. The transcriptome modifications at the midgut level were characterized seven days post-infection with tiling microarrays. Then we tested the bee midgut response to infection by measuring activity of antioxidant and detoxification enzymes (superoxide dismutases, glutathione peroxidases, glutathione reductase, and glutathione-S-transferase). At the gene-expression level, the bee midgut responded to N. ceranae infection by an increase in oxidative stress concurrent with the generation of antioxidant enzymes, defense and protective response specifically observed in the gut of mammals and insects. However, at the enzymatic level, the protective response was not confirmed, with only glutathione-S-transferase exhibiting a higher activity in infected bees. The oxidative stress was associated with a higher transcription of sugar transporter in the gut. Finally, a dramatic effect of the microsporidia infection was the inhibition of genes involved in the homeostasis and renewal of intestinal tissues (Wnt signaling pathway), a phenomenon that was confirmed at the histological level. This tissue degeneration and prevention of gut epithelium renewal may explain early bee death. In conclusion, our integrated approach not only gives new insights into the pathological effects of N. ceranae and the bee gut response, but also demonstrate that the honey bee gut is an interesting model system for studying host defense responses.
authors.affiliation: INRA, UR 406 Abeilles et Environnement, Site Agroparc, Avignon, France.
authors.forename: Claudia
authors.initials: C
authors.lastname: Dussaubat
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Brunet
authors.forename: Mariano
authors.initials: M
authors.lastname: Higes
authors.forename: John K
authors.initials: JK
authors.lastname: Colbourne
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Lopez
authors.forename: Jeong-Hyeon
authors.initials: JH
authors.lastname: Choi
authors.forename: Raquel
authors.initials: R
authors.lastname: Martín-Hernández
authors.forename: Cristina
authors.initials: C
authors.lastname: Botías
authors.forename: Marianne
authors.initials: M
authors.lastname: Cousin
authors.forename: Cynthia
authors.initials: C
authors.lastname: McDonnell
authors.forename: Marc
authors.initials: M
authors.lastname: Bonnet
authors.forename: Luc P
authors.initials: LP
authors.lastname: Belzunces
authors.forename: Robin F A
authors.initials: RF
authors.lastname: Moritz
authors.forename: Yves
authors.initials: Y
authors.lastname: Le Conte
authors.forename: Cédric
authors.initials: C
authors.lastname: Alaux
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001516:Bees / Q000201:enzymology / Q000382:microbiology*; D041981:Gastrointestinal Tract / Q000382:microbiology* / Q000473:pathology; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000235:genetics / Q000502:physiology*; D053263:Gene Regulatory Networks / Q000235:genetics; D005979:Glutathione Peroxidase / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D006652:Histological Techniques; D046228:Microarray Analysis; D016818:Nosema; D018384:Oxidative Stress / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D018709:Statistics, Nonparametric; D013482:Superoxide Dismutase / Q000378:metabolism; D059467:Transcriptome / Q000235:genetics / Q000502:physiology*; D060449:Wnt Signaling Pathway / Q000235:genetics / Q000502:physiology
chemical_list: D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D005980:Glutathione Reductase; D005982:Glutathione Transferase; D000469:Alkaline Phosphatase