title: Repertoire and evolution of TNF superfamily in Crassostrea gigas: implications for expansion and diversification of this superfamily in Mollusca.
abstract: Tumor necrosis factor superfamily (TNFSF) members represent a group of cytokines participating in diverse immunological, pathological and developmental pathways. However, compared with deuterostomia and cnidaia, the composition and evolution of TNF homologous in protostomia are still not well understood. In the present study, a total of 81 TNF superfamily (TNFSF) genes from 15 mollusk species, including 23 TNFSF genes from Crassostrea gigas, were surveyed by genome-wide bioinformatics analysis. The phylogenetic analysis showed that 14 out of 23 C. gigas TNFSF genes in five clades exhibited orthologous relationships with Pinctada fucata TNFSF genes. Moreover, there were 15 C. gigas TNFSF genes located in oyster-specific clusters, which were contributed by small-scaled tandem and/or segmental duplication events in oyster. By comparing the sequences of duplicated TNFSF pairs, exon loss and variant in exon/intron length were revealed as the major modes of divergence in gene structure. Most of the duplicated C. gigas TNFSF pairs were evolved under purifying selection with consistent tissue expression patterns, implying functional constraint shaped diversification. This study demonstrated the expansion and early divergence of TNF superfamily in C. gigas, which provides potential insight into revealing the evolution and function of this superfamily in mollusk.
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7th Nanhai Road, Qingdao 266071, China.
authors.forename: Dahai
authors.initials: D
authors.lastname: Gao
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7th Nanhai Road, Qingdao 266071, China.
authors.forename: Limei
authors.initials: L
authors.lastname: Qiu
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7th Nanhai Road, Qingdao 266071, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Gao
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7th Nanhai Road, Qingdao 266071, China.
authors.forename: Zhanhui
authors.initials: Z
authors.lastname: Hou
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7th Nanhai Road, Qingdao 266071, China.
authors.forename: Lingling
authors.initials: L
authors.lastname: Wang
authors.affiliation: Dalian Ocean University, Dalian 116023, China. Electronic address: lshsong@dlou.edu.cn.
authors.forename: Linsheng
authors.initials: L
authors.lastname: Song
mesh_terms: D000818:Animals; D005075:Biological Evolution; D019295:Computational Biology / Q000379:methods; D049896:Crassostrea / Q000276:immunology*; D005091:Exons / Q000235:genetics*; D020440:Gene Duplication; D005786:Gene Expression Regulation; D016678:Genome; D007438:Introns / Q000235:genetics*; D010802:Phylogeny; D011110:Polymorphism, Genetic; D012641:Selection, Genetic; D013045:Species Specificity; D048069:Tumor Necrosis Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D048069:Tumor Necrosis Factors
keywords: Crassostrea gigas; Diversification; Gene duplication; Phylogenetic analysis; TNFSF gene