四倍体鱼促性腺激素α亚基cDNA的克隆与序列分析

Cloning and Sequencing of Gonadotropin Alpha Subunit cDNA from the Tetraploid Fish

从四倍体鱼脑垂体中提取总RNA,用RT-PCR方法扩增并克隆了四倍体鱼GTH-α亚基4种不同的cD-NA,分别命名为GTH-α1、GTH-α2、GTH-α3和GTH-α4.其中,GTH-α1和GTH-α2的cDNA都由363个核苷酸组成,编码117个氨基酸;而GTH-α3和GTH-α4都由366个核苷酸组成,编码118个氨基酸.分析表明,四倍体鱼4种不同的GTH-α亚基之间的核苷酸和氨基酸的同源性非常高,均在96%以上;四倍体鱼和原始亲本红鲫和鲤鱼GTH-α亚基氨基酸序列之间的同源性也非常高,如四倍体鱼GTH-α1和原始母本红鲫GTH-α1氨基酸的同源性为99.2%,四倍体鱼GTH-α3和原始父本鲤鱼GTH-α1氨基酸的同源性达到了100%.

Total RNA is isolated from the tetraploid fish pituitary. The first strand cDNA is synthesized using oligo （dT）18 asa primer, the total RNA as a template, and AMV reverse transcriptase. Four types of cDNA encoding the α subunit of gonadotropin （GTH） are amplified and cloned by polymerase chain reactin （PCR） for the first strand cDNA of the tetraploid fishes. The tetraploid fishes GTH-α subunit cDNAs are named as α1, α2, α3, and α4. The nucleotide sequences of GTH-α1 and α2 cDNA are 363 bp in length, encoding 117 amino acids, and those of GTH-α3 and α4 are 366 bp in length, encoding 118 amino acids. These four types of GTH α subunits show higher homology （more than 96.0 % ） including the nucleotide and the amino acids. Moreover, high homology is observed by amino acids sequence alignment and identity comparison of the tetraploid fishes GTH-α subunit cDNAs with that of their original parents. For example, the homology of the amino acids sequenees between the tetraploid fishes GTH-α1 and their maternal red crucian carp GTH-α1 is 99.2 %, and that of the amino acids sequences between the tetraploid fishes GTH-α3 and their paternal common carp GTH-α1 is 100%.