日前，中國(guó)農(nóng)業(yè)大學(xué)生物學(xué)院趙要風(fēng)教授,、李寧院士在9月份出版的兩期免疫學(xué)雜志（the Journal of Immunology）上連續(xù)發(fā)表文章探討動(dòng)物免疫球蛋白基因的進(jìn)化問(wèn)題,。

通過(guò)與澳大利亞、瑞典科學(xué)家以及云南大學(xué)張亞平院士研究組,、本校生物學(xué)院張子丁教授的合作,，兩位教授研究小組在一種原始哺乳動(dòng)物鴨嘴獸中發(fā)現(xiàn)了一種新的免疫球蛋白類(lèi)型并命名為IgO(the Journal of Immunology,2009,183(5):3285-93)。IgO是近幾十年來(lái)在哺乳動(dòng)物中發(fā)現(xiàn)的除IgM,IgD,IgG,IgA和IgE外的唯一新類(lèi)型,，它包括四個(gè)固定區(qū)結(jié)構(gòu)域和一個(gè)鉸鏈區(qū)結(jié)構(gòu),，在結(jié)構(gòu)表現(xiàn)為低等動(dòng)物IgY與哺乳動(dòng)物IgG的中間體形式而且與兩者均具有基因序列同源性，明確證明了哺乳動(dòng)物IgG來(lái)源于低等動(dòng)物的IgY,。同時(shí)他們發(fā)現(xiàn)鴨嘴獸IgD（包含10個(gè)固定區(qū)結(jié)構(gòu)域,無(wú)鉸鏈區(qū)）與高等哺乳動(dòng)物IgD結(jié)構(gòu)（2到3個(gè)固定區(qū)結(jié)構(gòu)域和一段鉸鏈區(qū)）上具有顯著差異,，但與魚(yú)類(lèi)、兩棲類(lèi)和爬行類(lèi)IgD結(jié)構(gòu)上相同,。這些結(jié)果表明作為最原始的哺乳動(dòng)物,，鴨嘴獸免疫球蛋白基因同時(shí)混合了高等哺乳動(dòng)物與低等脊椎動(dòng)物的特征。

在另外一項(xiàng)研究中(the Journal of Immunology,2009,183(6):3858-64)，兩位教授與瑞典及美國(guó)研究人員合作對(duì)爬行類(lèi)動(dòng)物綠安蜥的免疫球蛋白基因進(jìn)行了詳細(xì)研究,，發(fā)現(xiàn)這類(lèi)爬行類(lèi)動(dòng)物中缺乏負(fù)責(zé)黏膜免疫的IgA基因,。

兩位教授在免疫球蛋白基因方面的研究對(duì)了解基因在脊椎動(dòng)物中的進(jìn)化提供了有意義的線索。

我校在讀博士研究生崔慧婷,、位治國(guó)和吳釬分別是兩篇論文的第一或并列第一作者,。這兩項(xiàng)研究得到了國(guó)家杰出青年科學(xué)基金及自然科學(xué)基金的支持。（生物谷Bioon.com）

生物谷推薦原始出處：

The Journal of Immunology, 2009, 183, 3858 -3864

Expression of IgM, IgD, and IgY in a Reptile, Anolis carolinensis1

Zhiguo Wei2,*, Qian Wu2,*, Liming Ren*, Xiaoxiang Hu*, Ying Guo*, Gregory W. Warr3,, Lennart Hammarstr?m, Ning Li4,* and Yaofeng Zhao4,*

* State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, Peoples Republic of China;   Medical University of South Carolina, Marine Biomedicine and Environmental Sciences Center, Charleston, SC 29425; and   Division of Clinical Immunology, Department of Laboratory Medicine, Karolinska University Hospital Huddinge, Stockholm, Sweden

The reptiles are the last major group of jawed vertebrates in which the organization of the IGH locus and its encoded Ig H chain isotypes have not been well characterized. In this study, we show that the green anole lizard (Anolis carolinensis) expresses three Ig H chain isotypes (IgM, IgD, and IgY) but no IgA. The presence of the  gene in the lizard demonstrates an evolutionary continuity of IgD from fishes to mammals. Although the germline  gene contains 11 CH exons, only the first 4 are used in the expressed IgD membrane-bound form. The μ chain lacks the cysteine in CH1 that forms a disulfide bond between H and L chains, suggesting that (as in IgM of some amphibians) the H and L polypeptide chains are not covalently associated. Although conventional IgM transcripts (four CH domains) encoding both secreted and membrane-bound forms were detected, alternatively spliced transcripts encoding a short membrane-bound form were also observed and shown to lack the first two CH domains (VDJ-CH3-CH4-transmembrane region). Similar to duck IgY, lizard IgY H chain () transcripts encoding both full-length and truncated (IgYFc) forms (with two CH domains) were observed. The absence of an IgA-encoding gene in the lizard IGH locus suggests a complex evolutionary history for IgA in the saurian lineage leading to modern birds, lizards, and their relatives.

1 This work was supported by National Science Fund for Distinguished Young Scholars Grant 30725029, Program for New Century Excellent Talents in University of China, National Key Basic Research Program Grant 2006CB102100, and National Natural Science Foundation of China Grant 30671497.
This material is based in part on work supported by the National Science Foundation. Any opinion, finding, and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the National Science Foundation.
2 Z.W. and Q.W. contributed equally to this work.
3 Current address: Division of Molecular and Cellular Biosciences, National Science Foundation, 4201 Wilson Boulevard, Arlington, VA 22230.
4 Address correspondence and reprint requests to Dr. Yaofeng Zhao, State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, Peoples Republic of China.  or Dr. Ning Li, State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, Peoples Republic of China.
5 Abbreviations used in this paper: IGH, Ig H chain gene; IGL, Ig L chain gene; BLAST, basic local alignment search tool; NCBI, National Center for Biotechnology Information; IgSF, Ig superfamily; TM, transmembrane region; sIg, secretory Ig.
6 The online version of this article contains supplemental material.

The Journal of Immunology, 2009, 183, 3285 -3293

Ornithorhynchus anatinus (Platypus) Links the Evolution of Immunoglobulin Genes in Eutherian Mammals and Nonmammalian Tetrapods1,2

Yaofeng Zhao3,4,*, Huiting Cui3,*, Camilla M. Whittington, Zhiguo Wei*, Xiaofeng Zhang, Ziding Zhang, Li Yu?, Liming Ren*, Xiaoxiang Hu*, Yaping Zhang?, Lars Hellman||, Katherine Belov, Ning Li4,* and Lennart Hammarstr?m4,#

* State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, People’s Republic of China;   Faculty of Veterinary Science, University of Sydney, Sydney, Australia;   Centre for Structural Biochemistry, Karolinska Institutet at Novum, Huddinge, Sweden;   Bioinformatics Center, College of Biological Sciences, China Agricultural University, Beijing, People’s Republic of China; ? Laboratory for Conservation and Utilization of Bio-resources, Yunnan University, Kunming, China; || Department of Cell and Molecular Biology, Biomedical Center, Uppsala, Sweden; and # Division of Clinical Immunology, Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden

The evolutionary origins of mammalian immunoglobulin H chain isotypes (IgM, IgD, IgG, IgE, and IgA) are still incompletely understood as these isotypes differ considerably in structure and number from their counterparts in nonmammalian tetrapods. We report in this study that the platypus (Ornithorhynchus anatinus) Ig H chain constant region gene locus contains eight Ig encoding genes, which are arranged in an μ--o-2-1-1--2 order, spanning a total of 200 kb DNA, encoding six distinct isotypes. The o (o for Ornithorhynchus) gene encodes a novel Ig H chain isotype that consists of four constant region domains and a hinge, and is structurally different from any of the five known mammalian Ig classes. This gene is phylogenetically related to  () and , and thus appears to be a structural intermediate between these two genes. The platypus  gene encodes ten heavy chain constant region domains, lacks a hinge region and is similar to IgD in amphibians and fish, but strikingly different from that in eutherian mammals. The platypus Ig H chain isotype repertoire thus shows a unique combination of genes that share similarity both to those of nonmammalian tetrapods and eutherian animals and demonstrates how phylogenetically informative species can be used to reconstruct the evolutionary history of functionally important genes.