Genome Wide Identification, Phylogeny, and Expression of <i>Aquaporin</i> Genes in Common Carp (Cyprinus carpio)

<div><p>Background</p><p>Aquaporins (Aqps) are integral membrane proteins that facilitate the transport of water and small solutes across cell membranes. Among vertebrate species, Aqps are highly conserved in both gene structure and amino acid sequence. These proteins are vital for maintaining water homeostasis in living organisms, especially for aquatic animals such as teleost fish. Studies on teleost Aqps are mainly limited to several model species with diploid genomes. Common carp, which has a tetraploidized genome, is one of the most common aquaculture species being adapted to a wide range of aquatic environments. The complete common carp genome has recently been released, providing us the possibility for gene evolution of <i>aqp</i> gene family after whole genome duplication.</p><p>Results</p><p>In this study, we identified a total of 37 <i>aqp</i> genes from common carp genome. Phylogenetic analysis revealed that most of <i>aqp</i>s are highly conserved. Comparative analysis was performed across five typical vertebrate genomes. We found that almost all of the <i>aqp</i> genes in common carp were duplicated in the evolution of the gene family. We postulated that the expansion of the <i>aqp</i> gene family in common carp was the result of an additional whole genome duplication event and that the <i>aqp</i> gene family in other teleosts has been lost in their evolution history with the reason that the functions of genes are redundant and conservation. Expression patterns were assessed in various tissues, including brain, heart, spleen, liver, intestine, gill, muscle, and skin, which demonstrated the comprehensive expression profiles of <i>aqp</i> genes in the tetraploidized genome. Significant gene expression divergences have been observed, revealing substantial expression divergences or functional divergences in those duplicated <i>aqp</i> genes post the latest WGD event.</p><p>Conclusions</p><p>To some extent, the gene families are also considered as a unique source for evolutionary studies. Moreover, the whole set of common carp <i>aqp</i> gene family provides an essential genomic resource for future biochemical, toxicological, physiological, and evolutionary studies in common carp.</p>