| Mirror carp, a variety of common carp, accounts for an increasingly larger proportion of production due to its faster growth, better disease resistance, higher meat conversion rate and near absence of scales on the body surface. In our study, the F1progenies that came from the parents selected randomly with the differences in performance traits from different family of mirror carp were used as mapping panel. With992microsatellite polymorphic markers,192individuals were genetyped, and the results of linkage maps, QTLs and the Blastn with zebrafish genome were showed below:(1) Phenotypic values of SOD traits in the F1progeny at400days post-hatch were measured. The average SOD values of the190F1individuals were179.56±5.49,27.51±0.81and50.61±1.31U in liver, anterior intestine and posterior intestine, respectively. SPSS13.0sofeware were used for normal distribution of the date.(2) A total of992microsatellite markers were mapped to51linkage groups using JoinMap4.0software (Van Ooijen2006), spanning a recombination distance of5183.9cM with an average marker spacing of5.226cM. The largest, with the lowest resolution, was linkage group (LG)51, consisting of nine markers and covering148.8cM, with a mean marker distance of16.53cM. The smallest linkage group was LG9, which contained nine markers and covered42.2cM. LG1had the highest resolution, consisting of40markers and covering72.4cM, with a mean marker interval of1.81cM.(3) Composite interval mapping (CIM) of Superoxide Dismutase (SOD) trait of three tissues, liver, anterior intestine and posterior intestine were conducted for QTL location using Map QTL6.0software. Results shows:1) Seven suggestive significant QTLs influencing the SOD trait were detected (P<0.05).In LG2, a suggestive QTL is HLJ3794-HLJ3663ering7.6cM and explaining 10.4’s phenotypic variation. In LG8, a QTL is HLJ1244-HLJ1897, covering9.4cM and explaining8.3-18.5%of the variation. In LG23, three QTLs are HLJ3022-HLJ2217,HLJ2218-HLJ3387, HLJ2108-HLJE27, spanning3.9cM,4.6cM,4.0cM respectively, and explaining8.1-12.4%of the variations. In LG49, two QTLs CA227-HLJ3369, CA2238-HLJ2463, covering4.1cM and5.1cM respectively, and explained10.9-12.6%of the variations.2) Five significant QTLs were detected for SOD traits in anterior intestine (P<0.05). In LG8, a QTL (HLJ1897-E623) covered4.4cM and accounted for8.7%of the variation in the SOD trait. In LG10, a QTL (HLJ1690-HLJ1147) covering7.8cM explained7.9-10.9%of the variation. In LG14, a QTL (CA2152-CA2299) covered2.9cM and explained8.7%of the variation. In LG36, two QTLs (CA1873-HLJ3751, CA1623-HLJ3451) covered9.6and5.0cM, respectively, and explained8.0-11.1%of the variation3) Six significant QTLs were detected for SOD traits in posterior intestine (P<0.05). In LG6, five QTLs (HLJ3697-CA1568, CA1340-CA1915, HLJ534-HLJ639, HLJ1275-HLJ2170, CA1808-HLJ370) covered5.0,0.7,4.5,3.8and10cM, respectively, and explained6.2-15.8%of the variation. In LG10, a QTL(HLJ2389—HLJ763) covering0.7cM explained7.4%of the variation.(4) Microsatellite markers from the zebrafish genome, for which whole genome sequences are available, provided an opportunity to compare similarities in genome organization between common carp with zebrafish. To identify syntenic regions between the respective genomes, SSR sequences containing mapped microsatellites were used as queries for NCBI BLASTn software (Johnson etc.2008) analysis against the zebrafish DNA databases in ENSEMBL with genome location information and the significance threshold (E-value<E-6). The results showed below: In Liver1) The marker sequence in the QTL located in LG2was highly homologous to zebrafish eosinophil peroxidase mRNA, located in zebrafish chromosome10.2) The marker sequence in the QTL located in LG8was homologous to zebrafish leucine-rich repeat-containing protein mRNA, which was located in zebrafish chromosome13.3) The marker sequences in the two QTLs located in LG23were homologous to zebrafish phosphorylase kinase and trimethyllysine dioxygenase mRNA, which were located in zebrafish chromosome21.4) The marker sequence in the QTLs located in LG49was homologous to zebrafish immune-associated nucleotide-binding protein mRNA, which were located in zebrafish chromosome11. Anterior intestine1) The marker sequence in the QTL located in LG8was homologous to zebrafish leucine-rich repeat-containing protein mRNA located in zebrafish chromosome13. The location was identical to that of the QTL of liver SOD trait.2) The marker sequence in the QTL located in LG10was homologous to a zebrafish sequence which was very close to SOD mRNA located in zebrafish chromosome1.3) The marker sequence in the QTL located in LG14was homologous to a zebrafish transmembrane protein mRNA, which was located in zebrafish chromosome18.4) The markers sequences in the two QTLs located in LG36were homologous to a zebrafish cell division cycle5-like protein mRNA and lysosomal-associated protein transmembrane mRNA, respectively, which were located in zebrafish chromosome17. Posterior intestines1) The marker sequences in the five QTLs located in LG6were homologous to zebrafish CCAAT/enhancer binding protein, RNA-binding protein MEX3B, transmembrane protein88, NEDD4-binding protein1and neurexin-2-beta mRNAs, respectively, which were located in zebrafish chromosome7.2) The marker sequence in the QTL located in LG10was homologous to a zebrafish CACCC-box-binding protein mRNA, located in zebrafish chromosome1.So it is convinced that these QTLs are high likely the main effect regions that conduct SOD expression and the date support the value of forward genetic studies on the organism development and serving as a basis for selection. |
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