Lineage-restricted retention of a primitive immunoglobulin heavy chain isotype within the Dipnoi reveals an evolutionary paradox
Lineage-restricted retention of a primitive immunoglobulin heavy chain isotype within the Dipnoi reveals an evolutionary paradox
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DOI：
10.1073/pnas.0538029100
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发表时间：
2003-03-04
影响因子：
11.1
通讯作者：
Amemiya, CT
中科院分区：
文献类型：
--
作者：
Ota, T;Rast, JP;Amemiya, CT
肺鱼的谱系是少数几个主要的有颌脊椎动物类群之一，其中IG重链同种型结构尚未在遗传水平上进行研究。在这项研究中，我们的特点是三种不同的IG重链同种型的非洲肺鱼，原鳍鱼aethiopicus，包括IgM型重链和短和长形式的非IgM重链。北方印迹分析以及V-H利用模式表明IgM和非IgM同种型可能在不同的基因座中编码。在原鳍鱼中鉴定的两种非IgM同种型与IgX/W/NARC的短形式和长形式（下文称为IgW）共享结构特征，其先前被认为仅限于软骨鱼。似乎IgW同种型具有比最初考虑的更广泛的系统发育分布，并提出了关于IgM和IgW的起源和进化分歧的问题。此外，它在其他有颌类谱系中的缺失意味着自相矛盾的是，IgW型基因在硬骨鱼和四足动物谱系中丢失。
The lineage leading to lungfishes is one of the few major jawed vertebrate groups in which Ig heavy chain isotype structure has not been investigated at the genetic level. In this study, we have characterized three different Ig heavy chain isotypes of the African lungfish, Protopterus aethiopicus, including an IgM-type heavy chain and short and long forms of non-IgM heavy chains. Northern blot analysis as well as patterns Of V-H utilization suggest that the IgM and non-IgM isotypes are likely encoded in separate loci. The two non-IgM isotypes identified in Protopterus share structural features with the short and long forms of IgX/W/NARC (referred to hereafter as IgW), which were previously considered to be restricted to the cartilaginous fish. It seems that the IgW isotype has a far broader phylogenetic distribution than considered originally and raises questions with regard to the origin and evolutionary divergence of IgM and IgW. Moreover, its absence in other gnathostome lineages implies paradoxically that the IgW-type genes were lost from teleost and tetrapod lineages.