Cloning and Identification of Four Aquaporin Genes in the Dogfish Shark (Squalus acanthias)

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The Bulletin: Mount Desert Island Biological Laboratory




The first homologue of the aquaporin water and small solute channel gene family isolated from an elasmobranch (aquaporin 1e; AQP1e), was identified in the bullshark (Carcharhinus leucas)1. This gene shared roughly similar levels of amino acid homology with human AQPs 1, 2 and 5 and may represent the progenitor of AQPs 2 and 5. The purpose of this study was to identify 1) the othologue of AQP1e in the dogfish shark (Squalus acanthias) and 2) to use similar techniques to identify, clone and sequence genes encoding other aquaporin isoforms present in dogfish shark osmoregulatory tissues (such as gill, intestine, esophagus, kidney and rectal gland). Attempts to isolate the orthologue of AQP 1e from the dogfish shark (Squalus acanthias) initially met with failure but did result in the isolation of a gene that that had higher levels of homology to human AQP 1 and represents the orthologue of this gene (see Table 1.)2. However, this further sequence data led to a re-design of degenerate oligonucleotide PCR primers, allowing another attempt at the amplification of a portion of the cDNAs’, not only of the Squalus orthologue of AQP1e, but also (using a similar approach) the orthologues of mammalian AQPs 3 and 4.