Molecular Characterization of Branchial aquaporin 1aa and Effects of Seawater Acclimation, Emersion or Ammonia Exposure on Its mRNA Expression in the Gills, Gut, Kidney and Skin of the Freshwater Climbing Perch, Anabas testudineus

10.1371/journal.pone.0061163PLoS ONE84

Molecular characterization of aquaporin 1aa (Aqp1aa) from the gills of <i>Anabas testudineus</i>.

<p>Multiple amino acid alignment of Aqp1aa from the gills of <i>A. testudineus</i>, with five other known Aqp1/Aqp1a from <i>Sparus aurata</i> (seabream Aqp1a; ABM26907.1), <i>Takifugu obscurus</i> (pufferfish Aqp1; ADG86337.1), <i>Protopterus annectens</i> (lungfish Aqp1; BAI48049.1), <i>Xenopus laevis</i> (frog AQP1; NP_001085391.1), and <i>Homo sapiens</i> (human AQP1; CAQ51480.2). Identical amino acids are indicated by shaded residues. Substrate discrimination sites at the aromatic/arginine (ar/R) constriction are indicated with arrows. Central pore-lining residues are indicated with open triangles. The binding site for AQP1-inhibitor HgCl₂ is indicated by an asterisk. The Asn-Pro-Ala (NPA) motifs are underlined. P denotes phosphorylation sites and N denotes <i>N</i>-glycosylation sites. The predicted transmembrane domains (TM) are underlined. The transmembrane domains of Aqp1 of <i>A. testudineus</i> were predicted using MEMSATS & MEMSAT-SVA provided by PSIPRED protein structure prediction server.</p

Tissue expression of <i>aquaporin 1aa</i> (<i>aqp1aa</i>) of <i>Anabas testudineus</i> in freshwater.

<p>Tissue expression of <i>aqp1aa</i> was examined in gills, accessory breathing organs (ABO), brain, liver, kidney, anterior gut (AG), posterior gut (PG) and skin of <i>A. testudineus</i> kept in freshwater.</p

<i>Aquaporin 1aa</i> (<i>aqp1aa</i>) mRNA expression in <i>Anabas testudineus</i> kept in freshwater or exposed to ammonia.

<p>Absolute quantification (×10² copies of transcript per ng cDNA; <i>N</i> = 5) of <i>aqp1aa</i> mRNA expression from (A) the gills, (B) the anterior gut, (C) the posterior gut, (D) the kidney and (E) the skin of <i>A. testudineus</i> kept in freshwater (FW) or exposed to 100 mmol l⁻¹ NH₄Cl for 1 or 6 days. Results represent means ± S.E.M. Means not sharing the same letter are significantly different (<i>P</i><0.05).</p

Phylogenetic analysis of aquaporin 1aa (Aqp1aa) of <i>Anabas testudineus</i>.

<p>The phylogenetic tree illustrates the relationship between Aqp1aa of <i>A. testudineus</i> and AQP1/Aqp1 of selected vertebrates.</p

The percentage sequence identity, arranged in a descending order of similarity, between the deduced amino acid sequence of aquaporin 1aa (Aqp1aa) of <i>Anabas testudineus</i> and Aqp sequences of other fish species obtained from GenBank (accession numbers in brackets).

<p>The percentage sequence identity, arranged in a descending order of similarity, between the deduced amino acid sequence of aquaporin 1aa (Aqp1aa) of <i>Anabas testudineus</i> and Aqp sequences of other fish species obtained from GenBank (accession numbers in brackets).</p

<i>Aquaporin 1aa</i> (<i>aqp1aa</i>) mRNA expression in <i>Anabas testudineus</i> kept in freshwater or seawater.

<p>Absolute quantification (×10² copies of transcript per ng cDNA; <i>N</i> = 5) of <i>aqp1aa</i> mRNA expression from (A) the gills, (B) the anterior gut, (C) the posterior gut, (D) the kidney and (E) the skin of <i>A. testudineus</i> kept in freshwater (FW) or exposed to seawater (SW; salinity 30) for 1 or 6 days after a progressive increase in salinity. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0061163#s3" target="_blank">Results</a> represent means ± S.E.M. Means not sharing the same letter are significantly different (<i>P</i><0.05).</p

<i>Aquaporin 1aa</i> (<i>aqp1aa</i>) mRNA expression in <i>Anabas testudineus</i> kept in freshwater or exposed to terrestrial conditions.

<p>Absolute quantification (×10² copies of transcript per ng cDNA; <i>N</i> = 5) of <i>aqp1aa</i> mRNA expression from (A) the gills, (B) the anterior gut, (C) the posterior gut, (D) the kidney and (E) the skin of <i>A. testudineus</i> kept in freshwater (FW) or exposed to terrestrial conditions for 1 day. Results represent means ± S.E.M. ^*Significantly different from the FW control (<i>P</i><0.05).</p