文章采用PCR方法从建鲤 (Cyprinus carpio var. jian) 基因组分离到2个肠型脂肪酸结合蛋白基因 (Fatty acid binding protein 2, FABP2), ORF长度均为399 bp, 相似度为92.2%, 分别记为jlFABP2a、jlFABP2b, 和斑马鱼 (Danio rerio) FABP2 ORF的相似度分别为88.0%和90.5%。jlFABP2s基因结构与FABPs家族其他成员一致, 由4个外显子和3个内含子组成, 2a和2b间内含子序列和长度差异明显。系统树显示这2个基因对应斑马鱼的1个FABP2基因, 和鲤鱼染色体数是斑马鱼的2倍一致。实时荧光定量PCR结果显示, jlFABP2a、2b在建鲤肠中的表达量极显著高于脑、肝脏、肌肉、肾脏、心脏、性腺等其他组织 (P<0.01), 且2a表达量显著 (雄鱼, P<0.05) 或极显著 (雌鱼, P<0.01) 高于2b, 但在其他组织则2b表达量稍高, 暗示2a为肠特异性表达, 2b则为广谱表达。通过比对8尾建鲤的2a和2b基因序列, 在2a和2b上分别找到12个和4个SNP, 均位于内含子上。使用PCR-RFLP 法检测jlFABP2a 上4个SNP 位点I1-A15G、I1-A99G、I2-C487T和I3-A27T在建鲤选育群体中的基因型分布, 并进行了基因型与个体增重的关联分析, 结果表明, 4个位点与雌、雄成鱼阶段增重分别有极显著或显著相关。同时考虑4个位点的基因型与增重的关系, 结果基因型AGGGCCXX 和AGGGXXAT的个体平均增重比其他个体快15%, 这两种基因型个体在选育群中占了9%, 具有较大的选育空间, 可用于建鲤分子育种计划中。
Two replicate intestine fatty acid binding protein genes (jlFABP2a and jlFABP2b) were cloned from Cyprinus carpio var. jian using PCR. Both ORFs were 399 bp in length sharing 92.2% similarity with each other, and 88.0% and 90.5% with their counterpart in zebrafish, respectively. The gene structure of jlFABP2s was same as other FABPs, which contained four exons and three introns. Sequences and lengths of introns between 2a and 2b. were obviously different Phylogenetic tree displayed that two jlFABP2s corresponded to one zebrafish FABP2 which matches the fact that the chromosome number of common carp was twice of zebrafish. Real time-PCR showed that jlFABP2 genes mainly expressed in intestine and the expression level was very significantly higher than other tissues such as brain, liver, muscle, kidney, and gonad (P<0.01). The expression level of jlFABP2a was significantly (male, P<0.05) or very significantly (females, P<0.01) higher than 2b in intestine; and 2b was expressed slightly higher than 2a in other tissues. It seemed that 2a expressed specifically in intestine, while 2b expressed ubiquitously. Twelve and four SNP loci were found at jlFABP2a and 2b introns through comparison sequences from 8 individuals, respectively. Geno-types of I1-A15G, I1-A99G, I2-C487T, and I3-A27T on jlFABP2a were detected using PCR-RFLP in selection population of C. carpio var. jian. The SNP genotypes and individual weight gain correlation indicated that four SNPs were significantly (P<0.05 or P<0.01) associated with adult weight gain. Diplotype analysis displayed that individuals with genotype AGGGCCXX or AGGGXXAT grew faster than other individuals by 15%. The individuals with these two genotypes only occupied 9% in total selection populations, indicating the presence of large selec-tion space. The 4 SNPs detected in this experiment can be used in C. carpio var. Jian growth selection breeding plan.
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