Genomic characterization and sequence diversity of the β2-microglobulin gene in the miiuy croaker, Miichthys miiuy

Abstract

ABSTRACT. b 2 -Microglobulin (β 2 m) is related to major histocompatibility complex class I alpha chains, and forms cellsurface glycoproteins that mediate a variety of functions in immune defense. In general, β 2 m has no isoforms and is not polymorphic in higher vertebrates, but polymorphisms between different alleles have been found in some fish species. In this study, full-length β 2 m cDNA and genomic sequences were cloned from the miiuy croaker (Miichthys miiuy). The miiuy croaker β 2 m gene shares many of the same characteristics as other fish species. Three exons and two introns were identified in the miiuy croaker β 2 m gene; these genomic structural features are similar to those present in other fish. The deduced β 2 m amino acid sequence exhibited 34.7-90.1% identity with mammal and teleost β 2 m amino acid sequences. Sequence polymorphism analysis in six individuals identified three alleles that encoded two proteins, confirming that β 2 m polymorphisms exist in this species. Phylogenetic analysis elucidated the evolutionary history of the β 2 m protein among warm-blooded vertebrates and bony fish.

Genome and Phylogenetic Analysis of Genes Involved in the Immune System of Solea senegalensis – Potential Applications in Aquaculture

“…MHC molecules are members of the immunoglobulin superfamily that present pathogen peptides of infected cells and thus initiate the generation of adaptive immunity to pathogens (Zhu et al, 2013). The b2m gene codifies for the beta subunit of the MHC class I and different paralog copies have been observed in several fish species (Kondo et al, 2010; Sun et al, 2015). Two types of b2m genes have been found in S. senegalensis and adjacent to each other.…”