Dmc1(disrupted meiotic cDNA)基因是一个在减数分裂前期Ⅰ表达的特异基因,其产物是减数分裂前期Ⅰ同源染色体配对所必需的.根据据酵母菌、小鼠以及人的DMC1中保守的氨基酸基序设计简并引物,PCR扩增克隆获得了第四代雌核发育二倍体鲫鲤( G4) Dmc1基因部分cDNA序列.在此基础上,通过RACE获得了G4Dmc1基因全长cDNA序列,长度为1369 bp,其中开放阅读框为1029 bp,编码含342个氨基酸的蛋白质.同时,系统进化分析表明,在进化过程中Dmc1基因在鱼类中保持着高度保守的进化特征.RT-PCR结果表明,Dmc1基因只在G4性腺中表达,在其他组织中不表达.通过实时荧光定量PCR,对Dmc1基因在G4和普通鲤鱼的早期卵巢的表达进行分析,发现G4表达比鲤鱼高.由此可见,雌核发育二倍体鲫鲤Dmc1基因也是减数分裂特异基因,而且其高表达暗示雌核发育二倍体鲫鲤具有正常的减数分裂过程并且其早期性腺存在着多倍体卵原细胞.%Dmcl ( disrupted meiotic cDNA) is a functionally specific gene, which encodes a protein required for homologous chromosome synapsis during the prophase of meiosis I . In this investigation, we cloned the partial cDNA of Dmcl of the fourth diploid gynogenetic generation hybrid of red crucian carp × common carp ( G4 ) by using a pair of degenerate primers based on the conservative sequence of amino acids of the DMC1 protein in yeast, mouse and human. The full length cDNA containing 1 369 bp were then obtained by RACE, which contained an ORF of 1 029 bp that encoded a protein of 342 amino acid residues. Sequence alignment and phylogenetic analysis revealed that Dmcl of fishes is conservative in evolution. A comparative study of the expression pattern of Dmcl was carried out by RT-PCR using specific primers, from which it was showed that Dmcl was expressed only in gonads. The expression pattern of Dmcl in early-stage gonads of G4 and Cyprinus carpio (L. ) was also studied by Real-time PCR, which showed higher expression of Dmcl in G4. Furthermore, the high expression of Dmcl in G4 suggested that G4 could have normal meiosis and existence of polyploidy oogonia in early-stage gonads of G4.
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