Cartilaginous fish class II genes reveal unprecedented old allelic lineages and confirm the late evolutionary emergence of DM

• Type: Article in International Scientific Journal
• Date: 2020

Authors

Almeida, T (Author) Other; Gaigher, A (Author) Other; Munoz Merida, A (Author) Other; Neves, F (Author) Other; Filipe F C Castro (Author) FCUP; Flajnik, MF (Author) Other; Ohta, Y (Author) Other; Esteves, PJ (Author) FCUP; Verissimo, A (Author) FCUP

Journal

Title: Molecular Immunology

Vol. 128

Pages: 125-138

ISSN: 0161-5890

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 7 Citations

Scopus - 7 Citations

Other information

Authenticus ID: P-00S-YXX

DOI: 10.1016/j.molimm.2020.10.003

Abstract (EN): Cartilaginous fish (chimaeras, rays and sharks) are the most basal extant jawed vertebrates with an adaptive immune system based on the Major Histocompatibility Complex (MHC). Despite being a key taxon in the evolution of vertebrate adaptive immunity, no comprehensive characterization of MHC class II genes has been undertaken for the group. We performed extensive bioinformatic searches on a taxonomically diverse dataset of transcriptomes and genomes of cartilaginous fish targeting MHC class II sequences. Class II alpha and II beta sequences were retrieved from all taxa analyzed and showed typical features of classical class II genes. Phylogenetic trees of the immunoglobulin superfamily domain showed two divergent and remarkably ancient lineages of class II genes in Selachians (sharks), originating >350 million years ago. Close linkage of lineage-specific pairs of II alpha and II beta genes was found, confirming previous results, with genes from distinct lineages segregating as alleles. Nonclassical class II DM sequences were not retrieved from these data and classical class II sequences lacked the conserved residues shown to interact with DM molecules, supporting claims that the DM system arose only in the lobe-finned fish lineage leading to tetrapods. Based on our search methods, other divergent class II genes are unlikely in cartilaginous fish.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 14