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Lineage-restricted retention of a primitive immunoglobulin heavy chain isotype within the Dipnoi reveals an evolutionary paradox

Ota, Tatsuya and Rast, Jonathan P. and Litman, Gary W. and Amemiya, Chris T. (2003) Lineage-restricted retention of a primitive immunoglobulin heavy chain isotype within the Dipnoi reveals an evolutionary paradox. Proceedings of the National Academy of Sciences of the United States of America, 100 (5). pp. 2501-2506. ISSN 0027-8424. http://resolver.caltech.edu/CaltechAUTHORS:OTApnas03

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Abstract

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.


Item Type:Article
Additional Information:Copyright © 2003 by the National Academy of Sciences. Communicated by Francis H. Ruddle, Yale University, New Haven, CT, December 31, 2002 (received for review December 9, 2002). Published online before print February 26, 2003, 10.1073/pnas.0538029100. We thank Mary West and Barbara Pryor for editorial assistance and Ronda Litman, Asaf Halevi, and Wendy Lippmann for technical assistance. This work was funded, in part, by National Science Foundation Grants IBN-9614940 and IBN-9905408 (to C.T.A.), National Institutes of Health Grants R37-AI23338 (to G.W.L.) and R24-RR14085 (to C.T.A.), the Center for Human Genetics (Boston University School of Medicine), and the Benaroya Research Institute at Virginia Mason.
Subject Keywords:RNA PROCESSING PATHWAYS, PRIMORDIAL IMMUNOGLOBULIN, CARTILAGINOUS FISH, MOUSE IGM, SEQUENCE, DOMAINS, MULTIPLICITY, MOLECULES, PHYLOGENY, TETRAPODS
Record Number:CaltechAUTHORS:OTApnas03
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:OTApnas03
Alternative URL:http://dx.doi.org/10.1073/pnas.0538029100
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1425
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:18 Jan 2006
Last Modified:26 Dec 2012 08:44

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