{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,28]],"date-time":"2026-03-28T09:13:54Z","timestamp":1774689234671,"version":"3.50.1"},"reference-count":42,"publisher":"Oxford University Press (OUP)","issue":"4","license":[{"start":{"date-parts":[[2020,2,1]],"date-time":"2020-02-01T00:00:00Z","timestamp":1580515200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/pages\/standard-publication-reuse-rights"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2020,2,15]]},"abstract":"<jats:title>Abstract<\/jats:title>\n               <jats:p>Cartilaginous fishes, or chondrichthyans, are the oldest jawed vertebrates that have an adaptive immune system based on the MHC and Ig superfamily\u2013based AgR. In this basal group of jawed vertebrates, we identified a third nonclassical MHC class I lineage (UDA), which is present in all species analyzed within the two major cartilaginous subclasses, Holocephali (chimaeras) and Elasmobranchii (sharks, skates, and rays). The deduced amino acid sequences of UDA have eight out of nine typically invariant residues that bind to the N and C termini of bound peptide found in most vertebrae classical class I (UAA); additionally, the other predicted 28 peptide-binding residues are perfectly conserved in all elasmobranch UDA sequences. UDA is distinct from UAA in its differential tissue distribution and its lower expression levels and is mono- or oligomorphic unlike the highly polymorphic UAA. UDA has a low copy number in elasmobranchs but is multicopy in the holocephalan spotted ratfish (Hydrolagus colliei). Using a nurse shark (Ginglymostoma cirratum) family, we found that UDA is MHC linked but separable by recombination from the tightly linked cluster of UAA, TAP, and LMP genes, the so-called class I region found in most nonmammalian vertebrates. UDA has predicted structural features that are similar to certain nonclassical class I genes in other vertebrates, and, unlike polymorpic classical class I, we anticipate that it may bind to a conserved set of specialized peptides.<\/jats:p>","DOI":"10.4049\/jimmunol.1901025","type":"journal-article","created":{"date-parts":[[2020,1,13]],"date-time":"2020-01-13T20:45:14Z","timestamp":1578948314000},"page":"892-902","source":"Crossref","is-referenced-by-count":16,"title":["An Ancient, MHC-Linked, Nonclassical Class I Lineage in Cartilaginous Fish"],"prefix":"10.1093","volume":"204","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8540-8301","authenticated-orcid":false,"given":"Tereza","family":"Almeida","sequence":"first","affiliation":[{"name":"CIBIO-InBIO, Centro de Investigac\u00e3o em Biodiversidade e Recursos Gen\u00e9ticos, Universidade do Porto , 4485-661 Vair\u00e3o, Porto ,","place":["Portugal"]},{"name":"Departamento de Biologia, Faculdade de Ci\u00eancias da Universidade do Porto , 4169-007 Porto ,","place":["Portugal"]},{"name":"Department of Microbiology and Immunology, University of Maryland , Baltimore, Baltimore, MD 21201"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6055-8298","authenticated-orcid":false,"given":"Pedro J","family":"Esteves","sequence":"additional","affiliation":[{"name":"CIBIO-InBIO, Centro de Investigac\u00e3o em Biodiversidade e Recursos Gen\u00e9ticos, Universidade do Porto , 4485-661 Vair\u00e3o, Porto ,","place":["Portugal"]},{"name":"Departamento de Biologia, Faculdade de Ci\u00eancias da Universidade do Porto , 4169-007 Porto ,","place":["Portugal"]}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2792-5084","authenticated-orcid":false,"given":"Martin F","family":"Flajnik","sequence":"additional","affiliation":[{"name":"Department of Microbiology and Immunology, University of Maryland , Baltimore, Baltimore, MD 21201"}]},{"given":"Yuko","family":"Ohta","sequence":"additional","affiliation":[{"name":"Department of Microbiology and Immunology, University of Maryland , Baltimore, Baltimore, MD 21201"}]},{"given":"Ana","family":"Ver\u00edssimo","sequence":"additional","affiliation":[{"name":"CIBIO-InBIO, Centro de Investigac\u00e3o em Biodiversidade e Recursos Gen\u00e9ticos, Universidade do Porto , 4485-661 Vair\u00e3o, Porto ,","place":["Portugal"]},{"name":"Virginia Institute of Marine Science, William & Mary , Gloucester Point, VA 23062"}]}],"member":"286","published-online":{"date-parts":[[2020,2,15]]},"reference":[{"key":"2025030417510745000_r1","first-page":"15","article-title":"The adaptive immune system of fish","volume":"90","author":"Warr","year":"1997","journal-title":"Dev. 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