title: Identification of a Serum amyloid A gene and the association of SNPs with Vibrio-resistance and growth traits in the clam Meretrix meretrix.
abstract: Serum amyloid A (SAA), an acute response protein as well as an apolipoprotein, is considered to play crucial roles in both innate immunity and lipid metabolism. In this study, a SAA gene (MmSAA) was identified in the clam Meretrix meretrix. The full length DNA of MmSAA was 1407bp, consisting of three exons and two introns. The distribution of MmSAA in clam tissues was examined with the highest expression in hepatopancreas. In response to the Vibrio parahaemolyticus challenge, MmSAA mRNA showed significantly higher expression at 24 h post-challenge in experimental clams (P < 0.05). Forty-eight single nucleotide polymorphisms (SNPs) in the DNA partial sequence of MmSAA were discovered and examined for their association with Vibrio-resistance and growth traits, respectively. The single SNP association analysis indicated that five single SNPs (g.42, g.72, g.82, g.147 and g.165) were significantly associated with Vibrio-resistance (P < 0.05). Haplotype analysis produced additional support for association with the Chi-square values 6.393 (P = 0.012). Among the five selected SNPs, the effect of a missense mutation (g.82, A → G) was detected by site-directed mutagenesis with fusion expression of protein assay, and the result showed that the recombinant plasmids containing wild-type pET30a-MmSAA had more inhibition effect than the mutant ones on the growth rate of the host bacteria. In addition, four growth traits of the clams in 09G3SPSB population were recorded and the SNP g.176 was found to be significantly associated with the growth traits with the Global score value 0.790 (P = 0.015). Our findings suggested that common genetic variation in MmSAA might contribute to the risk of susceptibility to Vibrio infection and might be associated with the growth traits in the clams M. meretrix, and more works are still needed to validate these SNPs as potential markers for actual selective breeding.
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Linhu
authors.initials: L
authors.lastname: Zou
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China. Electronic address: bzliu@qdio.ac.cn.
authors.forename: Baozhong
authors.initials: B
authors.lastname: Liu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D049872:Bivalvia / Q000235:genetics* / Q000254:growth & development / Q000276:immunology / Q000382:microbiology*; D007113:Immunity, Innate; D008969:Molecular Sequence Data; D009928:Organ Specificity; D020641:Polymorphism, Single Nucleotide; D016415:Sequence Alignment; D000685:Serum Amyloid A Protein / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014736:Vibrio parahaemolyticus / Q000502:physiology*
chemical_list: D000685:Serum Amyloid A Protein
keywords: Growth trait; Meretrix meretrix; Serum amyloid A; Single nucleotide polymorphism; Vibrio-resistance