Identification of two major histocompatibility (MH) class II A genes and their association to Vibrio anguillarum infection in half-smooth tongue sole (Cynoglossus semilaevis)

Major histocompatibility complex class II antigens are important in vertebrate immune system.In the present study,the full cDNA sequence of class II A gene was synthesized by RACE-PCR from half-smooth tongue sole(Cynoglossus semilaevis),and its open reading frame(ORF) polymorphism was studied.The whole cDNA sequence was 992 bp in length,including the ORF with 717 bp.Twenty-five alleles were identified and clustered into two distinct groups according to the specific nucleotides/amino acids in specific positions.Eleven alleles belonged to Cyse-DAA while fourteen alleles belonged to Cyse-DBA.Four Cyse-DAA alleles were observed in one individual,and three to five Cyse-DBA alleles were observed in each of the three detected individuals,which indicated that at least two loci existed in each gene.Moreover,in order to study the function of the alleles in resistance to infection,200 individuals were intraperitoneally injected with Vibrio anguillarum and the first 20 dead individuals and 20 surviving ones were selected for genotype analysis.Fifty-six alleles were identified among the 40 individuals.Twenty-nine alleles belonged to Cyse-DAA and the other 27 alleles belonged to Cyse-DBA.Eighteen alleles were selected for studying their function in resistance to infection.Alleles Cyse-DAA*0201,Cyse-DAA*1101,Cyse-DBA*0401,Cyse-DBA*1102,Cyse-DBA*1801 and Cyse-DBA*2201 were identi-fied only in surviving individuals,while alleles Cyse-DAA*0901,Cyse-DBA*1101 and Cyse-DBA*1401 occurred more frequently in dead individuals.This study confirmed the existence and polymorphism of two class II A genes as well as the relationship between alleles of class II A genes and disease susceptibility/resistance in half-smooth tongue sole.     

Location of Vibrio anguillarum resistance-associated trait loci in half-smooth tongue sole Cynoglossus semilaevis at its microsatellite linkage map

A cultured female half-smooth tongue sole(C ynoglossus semilaevis) was crossed with a wild male, yielding the fi rst fi lial generation of pseudo-testcrossing from which 200 fi sh were randomly selected to locate the V ibrio anguillarum resistance trait in half-smooth tongue sole at its microsatellite linkage map. In total, 129 microsatellites were arrayed into 18 linkage groups, ≥4 each. The map reconstructed was 852.85 c M in length with an average spacing of 7.68 c M, covering 72.07% of that expected(1 183.35 cM). The V. anguillarum resistance trait was a composite rather than a unit trait, which was tentatively partitioned into Survival time in Hours After V. anguillarum Infection(SHAVI) and Immunity of V. A nguillarum Infection(IVAI). Above a logarithm of the odds(LOD) threshold of 2.5, 18 loci relative to SHAVI and 3 relative to IVAI were identifi ed. The 3 loci relative to IVAI explained 18.78%, 5.87% and 6.50% of the total phenotypic variation in immunity. The microsatellites bounding the 3 quantitative trait loci(QTLs) of IVAI may in future aid to the selection of V. anguillarum-immune half-smooth tongue sole varieties, and facilitate cloning the gene(s) controlling such immunity.     

Development of 57 novel polymorphic microsatellite markers in half-smooth tongue sole (Cynoglossus semilaevis)

Half-smooth tongue sole (Cynoglossus semilaevis) is a promising species for aquaculture in China.The wild population of C. semilaevis is under threat from environmental factors. Microsatellite markers are very suitable for assessing genetic diversity. Four microsatellite-enriched libraries of half smooth tongue sole (Cynoglossus semilaevis) were constructed,from which 57 polymorphic microsatellites were isolated and characterized.The polymorphism of these microsatellites was assessed by genotyping in 30 ind...     

Genome-wide identification and prediction of long non-coding RNAs in half-smooth tongue sole Cynoglossus semilaevis

Journal of Oceanology and Limnology - At present, the function and profile of long noncoding RNAs (IncRNAs) in half-smooth tongue soles Cynoglossus semilaevis remain poorly understood. Lherefore,...     

Isolation,characterization and expression analysis of TRPV4 in half-smooth tongue sole Cynoglossus semilaevis

Journal of Oceanology and Limnology - The transient receptor potential vanilloid 4 (TRPV4), another Ca2+ entry channel, belongs to the vanilloid subfamily and responds to a number of different...     

Effects of BPA and E2 on expression profiles of genes related to hypothalamic-pituitary-gonadal axis of half-smooth tongue sole Cynoglossus semilaevis

Endocrine disrupting chemicals (EDCs) are increasingly viewed as persistent pollutants, similar to natural hormones in function. This paper describes the expression profiles of 7 genes (DMRT, VTG, GnRHR, FSHR, CYP17A, CYP19A, and CYP19B) involved in sex steroid synthesis and action as well as sexual development in adult male and female Cynoglossus semilaevis, after exposure to different concentrations of Bisphenol A (BPA) and 17β-estradiol (E2). Both BPA (1, 10, 50, 125, and 250 mg/kg) and E2 (0.5, 5, and 10 mg/kg) induced changes in target gene expression, although the estrogenic effects of E2 as a model estrogen were stronger. Among the 7 genes, VTG, CYP17A and CYP19 responded strongly to BPA or E2 exposure and can thus serve as reference biomarkers for estrogenic EDCs exposure in marine teleosts. These data will provide a window to establish a hypothalamic-pituitary-gonadal model in C. semilaevis to better understand the effect pathways of EDCs.     

Analysis of DNA methylation level by methylation-sensitive amplification polymorphism in half smooth tongue sole (<Emphasis Type="Italic">Cynoglossus semilaevis</Emphasis>) subjected to salinity stress

Increasingly arisen environmental constraints may contribute to heritable phenotypic variation including methylation changes, which can help the animals with development, growth and survival. In this study, we assessed the DNA methylation levels in three tissues (gonad, kidney and gill) of half smooth tongue sole under the salinity stress. The methylation-sensitive amplification polymorphism (MSAP) technique was applied to illustrate the regulation of epigenetic mechanism in environmental stimuli. Fish were subjected to 15 salinity treatment for 7 and 60 days, respectively. A total of 11259 fragments were amplified with 8 pairs of selective primers. The levels of methylated DNA in different tissues of females and males without salinity stress were analyzed, which were 32.76% and 47.32% in gonad; 38.13% and 37.69% in kidney; 37.58% and 34.96% in gill, respectively. In addition, the significant difference was observed in gonad between females and males, indicating that discrepant regulation in gonadal development and differentiation may involve sex-related genes. Further analysis showed that total and hemi-methylation were significantly decreased under 15 salinity for 7 days, probably resulting in up-regulating salt-tolerance genes expression to adjust salt changing. With the adjustment for 60 days, total and hemi-methylation prominently went back to its normal levels to obtain equilibrium. Particularly, full methylation levels were steady along with salinity stress to maintain the stability of gene expression. Additionally, the data showed that gonads in females and gills in males were superior in adaptability. As a result, DNA methylation regulates tissue- specific epiloci, and may respond to salinity stress by regulating gene expression to maintain animal survival and activity.