title: Identification and expression analysis of toll-like receptor genes (TLR8 and TLR9) in mucosal tissues of turbot (Scophthalmus maximus L.) following bacterial challenge.
abstract: Mucosal immune system is one of the most important components in the innate immunity and constitutes the front line of host defense against infection, especially for teleost, which are living in the pathogen-rich aquatic environment. The pathogen recognition receptors (PRRs), which can recognize the conserved pathogen-associated molecular patterns (PAMPs) of bacteria, are considered as one of the most important component for pathogen recognition and immune signaling pathways activation in mucosal immunity. In this regard, we sought to identify TLR8 and TLR9 in turbot (Scophthalmus maximus), as well as their mucosal expression patterns following different bacterial infection in mucosal tissues for the first time. The full-length TLR8 transcript consists of an open reading frame (ORF) of 3108 bp encoding the putative peptide of 1035 amino acids. While the TLR9 was 6730 bp long, containing a 3168 bp ORF that encodes 1055 amino acids. The phylogenetic analysis revealed both TLR8 and TLR9 showed the closest relationship to large yellow croaker. Moreover, both TLR8 and TLR9 could be detected in all examined healthy turbot tissues, with the lowest expression level in liver and a relatively moderate expression pattern in healthy mucosal tissues. Distinct expression patterns of TLR8 and TLR9 were comparatively observed in the mucosal tissues (intestine, gill and skin) following Vibrio anguillarum and Streptococcus iniae infection, suggesting their different roles for mucosal immunity. Further functional studies are needed to better characterize TLR8 and TLR9 and their family members, to better understand the ligand specificity and to identify their roles in different mucosal tissues in protecting fish from the pathogenically hostile environment.
authors.affiliation: Marine Science and Engineering College, Qingdao Agricultural University, Qingdao 266109, China.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Dong
authors.affiliation: Ministry of Agriculture Key Laboratory of Freshwater Aquatic Biotechnology and Breeding, Heilongjiang Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China; National and Local Joint Engineering Laboratory of Freshwater Fish Breeding, Heilongjiang Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China.
authors.forename: Baofeng
authors.initials: B
authors.lastname: Su
authors.affiliation: Marine Science and Engineering College, Qingdao Agricultural University, Qingdao 266109, China.
authors.forename: Shun
authors.initials: S
authors.lastname: Zhou
authors.affiliation: Ministry of Agriculture Key Laboratory of Freshwater Aquatic Biotechnology and Breeding, Heilongjiang Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China; National and Local Joint Engineering Laboratory of Freshwater Fish Breeding, Heilongjiang Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China.
authors.forename: Mei
authors.initials: M
authors.lastname: Shang
authors.affiliation: Ministry of Agriculture Key Laboratory of Freshwater Aquatic Biotechnology and Breeding, Heilongjiang Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China; College of Fisheries and Life Science, Shanghai Ocean University, Shanghai 201306, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Yan
authors.affiliation: Marine Science and Engineering College, Qingdao Agricultural University, Qingdao 266109, China.
authors.forename: Fengqiao
authors.initials: F
authors.lastname: Liu
authors.affiliation: Marine Science and Engineering College, Qingdao Agricultural University, Qingdao 266109, China.
authors.forename: Chengbin
authors.initials: C
authors.lastname: Gao
authors.affiliation: School of International Education and Exchange, Qingdao Agricultural University, Qingdao, 266109, China.
authors.forename: Fenghua
authors.initials: F
authors.lastname: Tan
authors.affiliation: Marine Science and Engineering College, Qingdao Agricultural University, Qingdao 266109, China. Electronic address: leoochao@163.com.
authors.forename: Chao
authors.initials: C
authors.lastname: Li
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D005393:Fish Diseases / Q000235:genetics / Q000276:immunology* / Q000382:microbiology; D029941:Fish Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005412:Flatfishes / Q000145:classification / Q000235:genetics / Q000276:immunology*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D007113:Immunity, Innate / Q000235:genetics; D009092:Mucous Membrane / Q000276:immunology; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013290:Streptococcal Infections / Q000235:genetics / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D000070058:Streptococcus iniae / Q000502:physiology; D051200:Toll-Like Receptor 8 / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D051217:Toll-Like Receptor 9 / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014733:Vibrio / Q000502:physiology; D014735:Vibrio Infections / Q000235:genetics / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*
chemical_list: D018076:DNA, Complementary; D029941:Fish Proteins; D012333:RNA, Messenger; D051200:Toll-Like Receptor 8; D051217:Toll-Like Receptor 9
keywords: Mucosal tissues; Scophthalmus maximus; Streptococcus iniae; TLR8; TLR9; Vibrio anguillarum