近期，中国农业大学动物科技学院研究者近期在PLOS Genetics发表了"An EAV-HP Insertion in 5' Flanking Region of SLCO1B3 Causes Blue Eggshell in the Chicken"一文，揭示了绿壳鸡蛋形成的遗传机制。
鸡蛋壳之所以会呈现绿色，是由于蛋壳中沉积了较多的胆绿素。我国的地方鸡品种中，有一些具有产绿壳蛋的特性，后经过选育形成了东乡绿壳蛋鸡，卢氏绿壳蛋鸡等品种。至于鸡蛋为绿壳的遗传机制一直未被人们所理解。
中国农业大学的研究者以中国的绿壳蛋鸡为实验材料，发现母鸡1号染色体的SLCO1B3基因启动子区域存在EAV-HP的插入，使得SLCO1B3基因在母鸡的卵壳腺中特异表达，因而导致母鸡产绿壳蛋。EVA-HP为一种鸟类的逆转率病毒，广泛存在鸟类的基因组中，而非产绿壳蛋的母鸡的SLCO1B3基因由于不含EAV-HP插入而不表达。SLCO1B3基因属于有机阴离子转运蛋白（OATP）家族，能帮助胆盐类的跨膜运输至卵壳腺，卵壳腺将胆绿素分泌至蛋壳中，使得最终的蛋壳呈现绿色。
南美安克拉鸡也具有产绿壳蛋的性状，研究发现其与中国的绿壳蛋鸡相比，EVA-HP在SLCO1B3插入位置略有差异，可能是因为该突变在两地绿壳蛋鸡进化中为独立的事件。研究控制蛋壳绿色基因也为研究家鸡进化提供了一些素材。（生物谷Bioon.com）
doi:10.1371/journal.pgen.1003183
An EAV-HP Insertion in 5′ Flanking Region of SLCO1B3 Causes Blue Eggshell in the Chicken.
Wang Z, Qu L, Yao J, Yang X, Li G, et al.
The genetic determination of eggshell coloration has not been determined in birds. Here we report that the blue eggshell is caused by an EAV-HP insertion that promotes the expression ofSLCO1B3 gene in the uterus (shell gland) of the oviduct in chicken. In this study, the genetic map location of the blue eggshell gene was refined by linkage analysis in an F2 chicken population, and four candidate genes within the refined interval were subsequently tested for their expression levels in the shell gland of the uterus from blue-shelled and non-blue-shelled hens. SLCO1B3 gene was found to be the only one expressed in the uterus of blue-shelled hens but not in that of non-blue-shelled hens. Results from a pyrosequencing analysis showed that only the allele of SLCO1B3 from blue-shelled chickens was expressed in the uterus of heterozygous hens (O*LC/O*N). SLCO1B3 gene belongs to the organic anion transporting polypeptide (OATP) family; and the OATPs, functioning as membrane transporters, have been reported for the transportation of amphipathic organic compounds, including bile salt in mammals. We subsequently resequenced the whole genomic region of SLCO1B3 and discovered an EAV-HP insertion in the 5′ flanking region of SLCO1B3. The EAV-HP insertion was found closely associated with blue eggshell phenotype following complete Mendelian segregation. In situ hybridization also demonstrated that the blue eggshell is associated with ectopic expression of SLCO1B3 in shell glands of uterus. Our finding strongly suggests that the EAV-HP insertion is the causative mutation for the blue eggshell phenotype. The insertion was also found in another Chinese blue-shelled breed and an American blue-shelled breed. In addition, we found that the insertion site in the blue-shelled chickens from Araucana is different from that in Chinese breeds, which implied independent integration events in the blue-shelled chickens from the two continents, providing a parallel evolutionary example at the molecular level.
