鸡生长激素cDNA及其5'端调控区的克隆分析

从肉用品种鸡构建的垂体文库中克隆分离了鸡生长激素ｃＤＮＡ，并作了核苷酸序列测定。克隆的鸡生长激素ｃＤＮＡ序列全长为７８９个碱基对，其中５＇非转译区为４０个碱基对，３’非转译区为１０１个碱基对，编码区为６４８个碱基对。通过序列比较分析，克隆的鸡生长激素ｃＤＮＡ序列与已报道的蛋用品种鸡生长激素ｃＤＮＡ序列的同源性为９６％，与鸭生长激素序列的同源性为８７％，但与火鸡生长激素序列的同源性只有５２％。通过ＰＣＲ技术，本研究还扩增了６个鸡品种的生长激素基因５’端调控区。尽管这些鸡品种的生产性能差异显著，但序列分析表明鸡生长激素基因５’端调控区十分保守。因而，鸡生长激素基因表达的差异可能受到内含子或３’端侧翼序列的影响。另外，鸡生长激素对多人数量性状的影响也在本文中进行了讨论。

Molecular Cloning and Analysing of Growth Hormone Complementary DNA and the 5'Regulation Domain of Growth Hormone Gene in Chicken

The chicken growth hormone ( GH ) complementary DNA ( cDNA ) has been isolated from a cDNA library , which is constructed with meat-type chicken's pitu- itary. The complete nucleotide sequence of the chicken GH cDNA determined in this study is 789 base pairs (bp) and consists of 40 bp in the 5' untranslated region , 101 bp in the 3' untranslated region and an open reading frame of 648 bp that encodes a 25 amino acid lead- er polypeptide segment as well as 191 amino acid mature chicken GH protein. The compari- son of the sequence of the chicken GH cDNA cloned in this study with the previously re- ported Leghorn chicken (egg-type ) GH cDNA and duck GH cDNA as well as turkey GH cDNA shows the homology to be 96% , 87% and 52% respectively. The 760 bp fragments containing the 5' regulation domain of GH geate are amplified by PCR techotique from the getnomes of 6 chicken breeds. The sequences of amplified fragments are very conservative although these chicken breeds significantly differ in many production traits. Thus , the re- sults indicate that variation of GH expression between chicken breeds could be due to the differences in the introns and/or the 3' flanking sequence in GH gene. Moreover ,the effect of chicken GH on some quantitative traits has also been discussed in the paper.