草鱼PRL基因多态性与幼鱼生长性状和肌肉成分的关联分析

为了探索草鱼(Ctenopharyngodon idella)PRL(prolactin)基因多态性与草鱼生长性状和肌肉成分的关联性,通过测序法从10尾草鱼的PRL基因中筛选到6个突变率高于30%的变异位点,包括5个单核苷酸变异位点和1个插入型突变(–/CACTCACTA),分别命名为2551GA、2639GC、3247AG、5197TG、5897GA和3391–+。利用AS-PCR(allele-specific PCR)和基因分型技术对192尾4月龄草鱼的PRL基因变异位点进行检测;基于一般线性模型对变异位点多态性与草鱼生长性状和肌肉成分进行相关性分析。研究发现,2639GC、3391–+和5197TG对体长和体重具有显著影响(P0.05),2639GC对肌肉粗蛋白含量具有显著影响(P0.05)。单个位点基因型比较发现,3391–+的突变型(–+和++)个体的体长和体重均显著高于野生型(––)个体(P0.05);2639GC的GC及5197TG的突变型(TG和GG)个体的体长和体重分别显著低于2639GC的GG和5197TG的TT野生型(P0.05);2639GC突变型(CC)个体的粗蛋白含量显著高于2639GC其他基因型(GG和GC)个体(P0.05)。两位点组合比较发现,含3391–+突变型(–+和++)的组合对应体长和体重普遍高于其他组,含2639GC的CC突变型的组合对应粗脂肪含量和粗蛋白含量普遍较高,其中粗蛋白含量显著高于其他组(P0.05)。研究表明,草鱼PRL基因多态性与草鱼生长性状和肌肉成分间存在显著关联,推测相关变异位点可作为草鱼生长和肉质改良的候选辅助标记。

Polymorphisms of the PRL gene and their associations with growth traits and flesh components in juvenile grass carp, Ctenopharyngodon idella

We analyzed the associations between the polymorphisms of thePRL (prolactin) gene and the growth traits and flesh components of the grass carp,Ctenopharyngodon idella. Six variable sites with mutation rates exceeding 30% were detected in 10 individuals by sequencing the full length of thePRL gene. These included five single-nucleotide polymorphic loci and one insert mutation (–/CACTCACTA), designated2551G>A,2639G/C,3247A>G,5197T>G, 5897G>A, and3391–/+, respectively. The polymorphisms at the variable sites were examined in 192 juvenileC. idella using allele-specific PCR and genotyping. The associations between the polymorphisms at these loci and the growth traits and flesh components of the fish were analyzed with general linear models. The polymorphisms at three loci (2639G>C,3391–>+, and5197T>G) and one locus (2639G>C) were significantly associated with growth traits and the flesh protein content (P<0.05), respectively. Multiple comparisons of the traits were made with the genotypes at each locus. The standard length and bodyweight of individuals with the mutant genotypes (?+ and ++) at3391–>+ were significantly higher than those of individuals with the wild-type genotype (– –)(P< 0.05). In contrast, the stan-dard length and bodyweight of individuals with the mutant genotypes at2639G>C (GC) and5197T>G (TG and GG) were significantly lower than those of individuals with the wild-type genotypes at2639G>C (GG) and5197T>G (TT) (P<0.05). For the, Individuals with the mutant genotype CC at2639G>C had significantly higher flesh protein content than individuals with the other genotypes (GG and GC) (P<0.05). Similar results were found in multiple comparisons for the traits of two loci groups. The standard length and bodyweight of individuals that contained mutant genotypes (–+ and ++) at3391–>+ were generally higher than those of individuals with the wild-type genotype (– –). The fat and pro-tein contents of individuals that contained the mutant genotype CC at2639G>C were generally higher than those of individuals with the other genotypes (GG or GC), and the protein contents were significantly different (P<0.05). Overall, there were significant associations between the polymorphisms of thePRL gene and the growth traits and flesh compo-nents ofC. idella. Therefore, the different variable sites in thePRL gene might have utility as markers for practical breeding programs for growth traits and flesh components inC. idella.