Han Binyue, Li Yan, Han Haitang, Zhao Yaofeng, Pan Qingjie, Ren Liming
State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing, P. R. China.
Key Laboratory of Animal Reproduction and Germplasm Enhancement in Universities of Shandong, Qingdao Agricultural University, Qingdao, P. R. China.
PLoS One. 2017 Apr 12;12(4):e0173334. doi: 10.1371/journal.pone.0173334. eCollection 2017.
Previous studies on a limited number of birds suggested that the IgD-encoding gene was absent in birds. However, one of our recent studies showed that the gene was definitely expressed in the ostrich and emu. Interestingly, we also identified subclass diversification of IgM and IgY in these two birds. To better understand immunoglobulin genes in birds, in this study, we analyzed the immunoglobulin heavy chain genes in the zebra finch (Taeniopygia guttata) and Gentoo penguin (Pygoscelis papua), belonging respectively to the order Passeriformes, the most successful bird order in terms of species diversity and numbers, and Sphenisciformes, a relatively primitive avian order. Similar to the results obtained in chickens and ducks, only three genes encoding immunoglobulin heavy chain isotypes, IgM, IgA and IgY, were identified in both species. Besides, we detected a transcript encoding a short membrane-bound IgA lacking the last two CH exons in the Gentoo penguin. We did not find any evidence supporting the presence of IgD gene or subclass diversification of IgM/IgY in penguin or zebra finch. The obtained data in our study provide more insights into the immunoglobulin heavy chain genes in birds and may help to better understand the evolution of immunoglobulin genes in tetrapods.
先前对数量有限的鸟类进行的研究表明，鸟类中不存在编码IgD的基因。然而，我们最近的一项研究表明，该基因在鸵鸟和鸸鹋中确实有表达。有趣的是，我们还在这两种鸟类中鉴定出了IgM和IgY的亚类多样化。为了更好地了解鸟类的免疫球蛋白基因，在本研究中，我们分析了斑胸草雀（Taeniopygia guttata）和巴布亚企鹅（Pygoscelis papua）的免疫球蛋白重链基因，它们分别属于雀形目（就物种多样性和数量而言是最成功的鸟类目）和企鹅目（一个相对原始的鸟类目）。与在鸡和鸭中获得的结果相似，在这两个物种中均仅鉴定出三个编码免疫球蛋白重链同种型的基因，即IgM、IgA和IgY。此外，我们在巴布亚企鹅中检测到一个转录本，其编码一种缺少最后两个CH外显子的短膜结合型IgA。我们没有发现任何证据支持企鹅或斑胸草雀中存在IgD基因或IgM/IgY的亚类多样化。我们研究中获得的数据为鸟类免疫球蛋白重链基因提供了更多见解，并可能有助于更好地理解四足动物免疫球蛋白基因的进化。
