Evolutionary history of aquaporin-10 pseudogenization in Cetartiodactyla
Aquaporin-10 (AQP10) is an aquaglyceroporin that transports small, uncharged molecules, such as water and glycerol. In some species, such as mice and cattle, the AQP10 gene (Aqp10) is pseudogenized. In rodents, pseudogenization of Aqp10 is limited to the Myomorpha suborder, while Aqp10 remains intact in other rodent lineages. The order Cetartiodactyla encompasses diverse species, including Suina, Tylopoda, Ruminantia, and Whippomorpha. The distribution of intact Aqp10 across the entire Cetartiodactyla and analyses estimating the timing of Aqp10 pseudogenization have not been sufficiently investigated. In this study, we identified species within Cetartiodactyla that retain intact Aqp10 and analyzed the detailed patterns of pseudogenization to elucidate the specifics of pseudogenization within this order. We collected Aqp10 loci by BLAST and synteny analyses of publicly available genome databases of 51 cetartiodactyl species from 17 families. Dot plot and alignment analyses revealed that seudogenization of Aqp10 occurred in 42 Cetartiodactyla species, including the Camelidae, warthog (Suidae), Antilocapridae, okapi (Giraffidae), Cervidae, Bovidae, Hippopotamidae, and Cetacea. In contrast, nine species retained an intact Aqp10: pig and babirusa (Suidae), peccary (Tayassuidae), mouse deeres (Tragulidae), giraffes (Giraffidae), and musk deers (Moschidae). The timing of pseudogenization was estimated by comparing patterns of exon deletions, frameshifts, and nonsense mutations in Aqp10 pseudogenes. RT-PCR analysis of cattle and sheep tissues revealed that these species express Aqp3 and Aqp7 in their intestines, but not Aqp10. Collectively, these findings indicate that Aqp10 pseudogenization occurred independently in multiple cetartiodactyl lineages and provide new insights into the evolutionary history of Aqp10 loss within this order.