LP小鼠突变基因的定位及鉴定

目的以卷尾突变C57BL/6J小鼠为研究对象,通过微卫星定位以及候选基因测序分析确定突变基因位点。方法将LP小鼠与正常C57BL/6J及C3H小鼠交配,记录了后代中卷尾与正常小鼠的数目,确定卷尾突变表型的遗传模式。微卫星D1Mit113和D1Mit149对突变基因进行了精确定位,确定候选基因。PCR扩增候选基因片段直接测序并进行序列分析。用Fsp BI(Bfa I)内切酶鉴定LP小鼠杂交后代的基因型。结果 LP突变呈单基因不完全显性遗传,在不同的遗传背景中存在表型差异;Vangl2基因编码区1345bp处碱基由C→T。结论 Vangl2基因C→T的突变是一种无义突变,导致蛋白编码提前终止,是引起卷尾突变的原因;杂交LP小鼠后代中未出现纯合子小鼠,证明Vangl2基因突变纯合子致死。

Location and identification of the mutant gene in loop-tail mouse

Objective To define the loci of the mutant gene in the loop-tail mouse.Methods To study the heredity pattern, loop-tail mice were mated with normal C57BL/6J and C3H mice. Their offsprings with loop-tail or normal phenotype were registered respectively. Microsatellite marker D1Mit113 and D1Mit149 were used to locate the mutant gene. Based on fine mapping, the candidate gene Vangl2 was found. Vangl2 gene from the loop-tail mice was amplified by PCR followed by sequencing. Incision enzyme FspBI(BfaI)identified the genotype of offspring from loop-tail mice intercrossing. Results Heredity test indicated that the loop-tail phenotype was controlled by a single dominant gene not with 100% penetrance but was affected by genetic background. A C-to-T transversion was at the 1345bp in Vangl2 gene of the loop-tail mice.Conclusions The C-to-T transversion introduces a pre-termination codon of amino acids and causes the phenotype of loop-tail phenotype. None homozygous mice were found in the offsprings, suggesting that the homozygous mice are lethal.