title: Roles of peroxinectin in PGE2-mediated cellular immunity in Spodoptera exigua.
abstract: BACKGROUND
  Prostaglandins (PGs) mediate insect immune responses to infections and invasions. Although the presence of PGs has been confirmed in several insect species, their biosynthesis in insects remains a conundrum because orthologs of the mammalian cyclooxygenases (COXs) have not been found in the known insect genomes. PG-mediated immune reactions have been documented in the beet armyworm, Spodoptera exigua. The purpose of this research is to identify the source of PGs in S. exigua.
  
  
  RESULTS
  Peroxidases (POXs) are a sister group of COX genes. Ten putative POXs (SePOX-A ∼ SePOX-J) were expressed in S. exigua. Expressions of SePOX-F and -H were induced by bacterial challenge and expressed in the hemocytes and the fat body. RNAi of each POX was performed by hemocoelic injection of their specific double-stranded RNAs. dsPOX-F or, separately, dsPOX-H, but not the other eight dsRNA constructs, specifically suppressed hemocyte-spreading behavior and nodule formation; these two reactions were also inhibited by aspirin, a COX inhibitor. PGE2, but not arachidonic acid, treatment rescued the immunosuppression. Sequence analysis indicated that both POX genes were clustered with peroxinectin (Pxt) and their cognate proteins shared some conserved domains corresponding to the Pxt of Drosophila melanogaster.
  
  
  CONCLUSIONS
  SePOX-F and -H are Pxt-like genes associated with PG biosynthesis in S. exigua.
authors.affiliation: Department of Bioresource Sciences, Andong National University, Andong, South Korea.
authors.forename: Jiyeong
authors.initials: J
authors.lastname: Park
authors.affiliation: Biological Control of Insects Research Laboratory, USDA/Agricultural Research Service, Columbia, Missouri, United States of America.
authors.forename: David
authors.initials: D
authors.lastname: Stanley
authors.affiliation: Department of Bioresource Sciences, Andong National University, Andong, South Korea.
authors.forename: Yonggyun
authors.initials: Y
authors.lastname: Kim
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015232:Dinoprostone / Q000378:metabolism* / Q000494:pharmacology; D015870:Gene Expression; D020869:Gene Expression Profiling; D006434:Hemocytes / Q000378:metabolism; D007111:Immunity, Cellular / Q000187:drug effects / Q000235:genetics*; D008969:Molecular Sequence Data; D010544:Peroxidases / Q000737:chemistry / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D018411:Spodoptera / Q000502:physiology*
chemical_list: D012330:RNA, Double-Stranded; D010544:Peroxidases; D015232:Dinoprostone