Organisation and evolution of the major histocompatibility complex class I genes in cetaceans

Grace Day; Kate Robb; Andrew Oxley; Marina Telonis-Scott; Beata Ujvari

doi:10.1016/j.isci.2024.109590

Organisation and evolution of the major histocompatibility complex class I genes in cetaceans

iScience. 2024 Mar 27;27(4):109590. doi: 10.1016/j.isci.2024.109590. eCollection 2024 Apr 19.

Authors

Grace Day^{1

2}, Kate Robb², Andrew Oxley¹, Marina Telonis-Scott³, Beata Ujvari¹

Affiliations

¹ School of Life and Environmental Sciences, Deakin University, Geelong 3216, VIC, Australia.
² Marine Mammal Foundation, Melbourne 3194, VIC, Australia.
³ School of Life and Environmental Sciences, Deakin University, Melbourne 3125, VIC, Australia.

Abstract

A quarter of marine mammals are at risk of extinction, with disease and poor habitat quality contributing to population decline. Investigation of the Major Histocompatibility Complex (MHC) provides insight into species' capacity to respond to immune and environmental challenges. The eighteen available cetacean chromosome level genomes were used to annotate MHC Class I loci, and to reconstruct the phylogenetic relationship of the described loci. The highest number of loci was observed in the striped dolphin (Stenella coeruleoalba), while the least was observed in the pygmy sperm whale (Kogia breviceps) and rough toothed dolphin (Steno bredanensis). Of the species studied, Mysticetes had the most pseudogenes. Evolutionarily, MHC Class I diverged before the speciation of cetaceans. Yet, locus one was genomically and phylogenetically similar in many species, persisting over evolutionary time. This characterisation of MHC Class I in cetaceans lays the groundwork for future population genetics and MHC expression studies.

Keywords: evolutionary biology; immune system evolution.