title: Up-regulated expression of AOS-LOXa and increased eicosanoid synthesis in response to coral wounding.
abstract: In octocorals, a catalase-like allene oxide synthase (AOS) and an 8R-lipoxygenase (LOX) gene are fused together encoding for a single AOS-LOX fusion protein. Although the AOS-LOX pathway is central to the arachidonate metabolism in corals, its biological function in coral homeostasis is unclear. Using an acute incision wound model in the soft coral Capnella imbricata, we here test whether LOX pathway, similar to its role in plants, can contribute to the coral damage response and regeneration. Analysis of metabolites formed from exogenous arachidonate before and after fixed time intervals following wounding indicated a significant increase in AOS-LOX activity in response to mechanical injury. Two AOS-LOX isoforms, AOS-LOXa and AOS-LOXb, were cloned and expressed in bacterial expression system as active fusion proteins. Transcription levels of corresponding genes were measured in normal and stressed coral by qPCR. After wounding, AOS-LOXa was markedly up-regulated in both, the tissue adjacent to the incision and distal parts of a coral colony (with the maximum reached at 1 h and 6 h post wounding, respectively), while AOS-LOXb was stable. According to mRNA expression analysis, combined with detection of eicosanoid product formation for the first time, the AOS-LOX was identified as an early stress response gene which is induced by mechanical injury in coral.
authors.affiliation: Department of Chemistry, Tallinn University of Technology, Tallinn, Estonia.
authors.forename: Helike
authors.initials: H
authors.lastname: Lõhelaid
authors.affiliation: Department of Chemistry, Tallinn University of Technology, Tallinn, Estonia.
authors.forename: Tarvi
authors.initials: T
authors.lastname: Teder
authors.affiliation: Department of Chemistry, Tallinn University of Technology, Tallinn, Estonia.
authors.forename: Kadri
authors.initials: K
authors.lastname: Tõldsepp
authors.affiliation: Sessile Marine Invertebrates, Queensland Museum, Brisbane, Queensland, Australia.
authors.forename: Merrick
authors.initials: M
authors.lastname: Ekins
authors.affiliation: Department of Chemistry, Tallinn University of Technology, Tallinn, Estonia.
authors.forename: Nigulas
authors.initials: N
authors.lastname: Samel
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000201:enzymology* / Q000235:genetics*; D016718:Arachidonic Acid / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D056148:Chromatography, Reverse-Phase; D015971:Gene Expression Regulation, Enzymologic; D019746:Intramolecular Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D008084:Lipoxygenase / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D020539:Sequence Analysis, Protein; D013312:Stress, Physiological; D015854:Up-Regulation
chemical_list: D012333:RNA, Messenger; D016718:Arachidonic Acid; D008084:Lipoxygenase; D019746:Intramolecular Oxidoreductases; C021377:hydroperoxide isomerase