中文摘要：

采用PCR—SSCP技术检测胰岛素样生长因子Ⅰ（insulin like growth factorⅠ，IGF-Ⅰ）基因外显子在性早熟、高繁殖力品种（济宁青山羊）和性晚熟、中等繁殖力（波尔山羊）以及性晚熟、低繁殖力品种（安哥拉山羊和内蒙古绒山羊）中的单核苷酸多态性，分析该基因对济宁青山羊性早熟和高繁殖力的影响；并对济宁青山羊IGF-Ⅰ基因扩增片段进行克隆测序，拼接出山羊IGF—Ⅰ基因4个外显子序列，将济宁青山羊IGF-Ⅰ基因外显子核苷酸序列和推导的氨基酸序列与绵羊、牛、人、大鼠、小鼠和鸡6个物种的序列进行比较。结果表明，IGF—Ⅰ基因4个外显子在所检测的4个山羊品种中均不存在多态性；这7个物种的核苷酸和氨基酸序列同源性分别为79．6％-99．3％和77．8％～99．4％：与牛、人等6物种相比，济宁青山羊IGF—Ⅰ基因氨基酸序列不存在特有变化。可见，物种间IGF-Ⅰ基因保守性强，1GF-Ⅰ基因可能不是影响济宁青山羊性早熟和高繁殖力的主效基因。

英文摘要：

The insulin like growth factorⅠ （IGF-Ⅰ ） gene was studied as a candidate gene for sexual precocity and high prolificacy in some goat （ Capra hircus） breeds. Single nucleotide polymorphisms （SNPs） of all exons of IGF- Ⅰ gene were detected in sexual precocity and high prolificacy breed （Jining Grey goat） and sexual late-maturing and moderate fecundity breed （Boer goat） and sexual late-maturing and low fecundity breeds （Angora and Inner Mongolia Cashmere goats） by polymerase chain reaction-single strand conformation polymorphism （PCR-SS- CP）. No polymorphism was detected in the amplified region in the four goat breeds tested. DNA fragments amplified in this research were cloned into pGM-T vector. The positive clones were further identified by PCR. The nucleotide sequences of four exons in goat IGF-Ⅰ were spliced and the corresponding amino acid sequences were deduced. The comparison of the fragments of all four exons of Jining Grey goat IGF- Ⅰ gene with those of human, cattle, sheep, rat, mouse and chicken showed that the homologies of the nucleotide sequences and amino acid sequences of the fragments among these seven species were from 79.6% to 99.3% and from 77.8% to 99.4% respectively. No special variation was found in amino acid sequence of Jining Grey goat. The results indicated that the IGF- Ⅰ gene was highly conserved among mammals, and may not be a major gene that affects the sexual precocity and high prolificacy in Jining Grey goats.