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Cartilaginous fishes offer unique insights into the evolution of the nuclear receptor gene repertoire in gnathostomes

2020; Elsevier BV; Volume: 295; Linguagem: Inglês

10.1016/j.ygcen.2020.113527

1095-6840

Elza Fonseca, André M. Machado, Nair Vilas-Arrondo, André Gomes‐dos‐Santos, Ana Veríssimo, Pedro J. Esteves, Tereza Almeida, Gonçalo Espregueira Themudo, Raquel Ruivo, Montse Pérez, Rute R. da Fonseca, Miguel M. Santos, Elsa Froufe, E. Román-Marcote, Byrappa Venkatesh, L. Filipe C. Castro,

Aquaculture Nutrition and Growth

Nuclear receptors (NRs) are key transcription factors that originated in the common ancestor of metazoans. The vast majority of NRs are triggered by binding to either endogenous (e.g. retinoic acid) or exogenous (e.g. xenobiotics) ligands, and their evolution and expansion is tightly linked to the function of endocrine systems. Importantly, they represent classic targets of physiological exploitation by endocrine disrupting chemicals. The NR gene repertoire in different lineages has been shaped by gene loss, duplication and mutation, denoting a dynamic evolutionary route. As the earliest diverging class of gnathostomes (jawed vertebrates), cartilaginous fishes offer an exceptional opportunity to address the early diversification of NR gene families and the evolution of the endocrine system in jawed vertebrates. Here we provide an exhaustive analysis into the NR gene composition in five elasmobranch (sharks and rays) and two holocephalan (chimaeras) species. For this purpose, we generated also a low coverage draft genome assembly of the chimaera small-eyed rabbitfish, Hydrolagus affinis. We show that cartilaginous fish retain an archetypal NR gene repertoire, similar to that of mammals and coincident with the two rounds of whole genome duplication that occurred in the gnathostome ancestor. Furthermore, novel gene members of the non-canonical NR0B receptors were found in the genomes of this lineage. Our findings provide an essential view into the early diversification of NRs in gnathostomes, paving the way for functional studies.