决定绿壳蛋鸡壳色的Oocyan(O)基因座位位于一号染色体。绿色蛋壳的色素主要有原卟啉、胆绿素以及胆绿素的锌络合物,将上述色素代谢途径中的酶对应的基因在家鸡基因组序列中进行比对,没有发现与O基因座位相符的位点。基于ALEVI周围微卫星标记较少,在家鸡一号染色体基因组序列上选取距离ALEVI上游3.5cM的位点设计引物进行PCR-SSCP分析,寻找与绿壳基因座位紧密连锁的SNP标记位点,并且分析标记位点基因型与O位点不同基因型之间的相关性。结果表明,一个标记与绿壳基因位点紧密连锁,该标记上发生2个点突变,分别是家鸡Chrl:61754089T-〉A与Chrl:61754175A.〉T上的颠换。在纯合绿壳蛋鸡群体中,81%的个体在2个位点均发生突变,标为AA型,杂合绿壳群体中AB型为89%,粉壳蛋鸡群体中93%的个体与红色原鸡序列一致,标为BB型。在绿壳蛋鸡育种中,建议以AA型作为分子标记提高绿壳蛋鸡育种工作的效率。
Oocyan (O) gene determines blue shell pigmentation of domesticated chicken. O locus is closely linked to ALEVI on chromosomel with a genetic distance of 2.3 cM. Blue eggshells contain protoporphyrin, biliverdin and zink biliverdin chelatate, which belong to the porphyrin metabolic pathway. A bioinformatic approach was first used to blast the genes for enzymes of porphyrin pathway and no gene was detected to specify O locus. Due to limited number of SSR markers around O locus, PCR-SSCP was then employed to search for candidate SNP markers. The sequence beating a marker was found to be consisted of two transversions at Chr1:61754089T-〉A and Chr1:61754175A-〉T, respectively. Population screening showed that 81% of homozygous blue-shelled layers(OO) were classified as AA genotype at the SNP loci, while 89% of heterozygous blue-shelled layers(Oo) were AB genotype and 93% of tinted layers (oo) were BB genotype. The results indicated that there was a close association between O locus and SNP locus, which suggests that the marker locus can be used as a molecular marker in breeding for blue-shelled chickens.