Multiple amino acid alignment of the deduced amino acid sequence of gulonolactone oxidase (Gulo) from the kidney of <i>Himantura signifer</i>, with eight other known sequences of Gulo from GenBank; <i>Scyliorhinus torazame</i> (cloudy catshark Gulo; Q90YK3.1), <i>Triakis scyllium</i> (banded houndshark Gulo; ABO15547.1), <i>Mustelus manazo</i> (starspotted smooth-hound Gulo; ABO15548.1), <i>Acipenser transmontanus</i> (sturgeon Gulo; ABO15549.1), <i>Xenopus laevis</i> (frog GULO; NM_001095065), <i>Pelodiscus sinensis</i> (turtle GULO; AET14634.1), <i>Gallus gallus</i> (chicken GULO; XM_001234313), and <i>Mus musculus</i> (mouse GULO; P58710.3).

<p>Identical amino acids are indicated by shaded residues. The FAD-binding and ALO domains are underlined in bold and dotted lines respectively. P denotes potential phosphorylation sites. O denotes potential O-GlcNAcylation sites. The predicted transmembrane domains are underlined. The transmembrane domains (TM) of Gulo of <i>H. signifer</i> were predicted using MEMSATS & MEMSAT-SVA provided by PSIPRED protein structure prediction server.</p

Specific activity of gulonolactone oxidase (Gulo; µg ascorbic acid formed h⁻¹ g⁻¹) from the kidney of <i>Himantura signifer</i> kept in freshwater (FW) on day 0 (control), or exposed to brackish water (salinity 20) for 1 or 6 days after a 4-day progressive increase in salinity.

<p>Results represent mean ± S. E. M. (N = 4). Means not sharing the same letter are significantly different (<i>P</i><0.05).</p

Concentrations (µg g⁻¹ wet mass) of ascorbate (AA; ▪), dehydroascorbate (DA; ▪) or AA+DA (TAA; □) in the brain of <i>Himantura signifer</i> kept in freshwater (FW) on day 0 (control), or exposed to brackish water (salinity 20) for 1 or 6 days after a 4-day progressive increase in salinity.

<p>Results represent mean ± S. E. M. (N = 4). Means not sharing the same letter are significantly different (<i>P</i><0.05).</p

Concentrations (µg g⁻¹ wet mass) of ascorbate (AA; ▪), dehydroascorbate (DA; ▪) or AA+DA (TAA; □) in the kidney of <i>Himantura signifier</i> kept in freshwater (FW) on day 0 (control), or exposed to brackish water (salinity 20) for 1 or 6 days after a 4-day progressive increase in salinity.

<p>There was no statistical difference between different groups. Results represent mean ± S. E. M. (N = 4).</p

Absolute quantification (copies of transcript per ng cDNA) of mRNA expression of <i>gulonolactone oxidase</i> (<i>gulo</i>) from the kidney of <i>Himantura signifer</i> kept in freshwater (FW; control) or exposed to brackish water (salinity 20) for 1 or 6 days after a 4-day progressive increase in salinity.

<p>Results represent mean ± S. E. M. (N = 5). Means not sharing the same letter are significantly different (<i>P</i><0.05).</p

Concentrations (µg g⁻¹ wet mass) of ascorbate (AA; ▪), dehydroascorbate (DA; ▪) or AA+DA (TAA; □) in the gills of <i>Himantura signifer</i> kept in freshwater (FW) on day 0 (control), or exposed to brackish water (salinity 20) for 1 or 6 days after a 4-day progressive increase in salinity.

<p>Results represent mean ± S. E. M. (N = 4). Means not sharing the same letter are significantly different (<i>P</i><0.05).</p

mRNA expression of <i>gulonolactone oxidase</i> (<i>gulo</i>) from the brain, heart, eye, spleen, stomach, intestine, kidney, gills, skin, liver and muscle of <i>Himantura signifer</i> kept in freshwater.

<p>mRNA expression of <i>gulonolactone oxidase</i> (<i>gulo</i>) from the brain, heart, eye, spleen, stomach, intestine, kidney, gills, skin, liver and muscle of <i>Himantura signifer</i> kept in freshwater.</p

Methyl–hydride metathesis between [Zr(cp)2Me2] and [HAl(μ3-NBut)]4: molecular structures of [Me1−xHxAl(μ 3-NBut)]4 (x = 0, 0.78 or 1) and [(cp)2ZrMe(μ-H)]2 (cp = η5-C5H5)

<p>Absolute quantification (copies of transcript per ng of cDNA) of <i>scn2b</i> transcripts in the main EO, the Hunter’s EO, the Sach’s EO and the SM of (a) adult or (b) juvenile <i>E</i>. <i>electricus</i> kept in fresh water. Results represent means ± S.E.M. (<i>N</i> = 4). Means not sharing the same letter are significantly different (<i>P</i><0.05).</p

mRNA expression levels of the <i>voltage-gated Na</i>^<i>+</i> <i>channel type IV α-subunit a isoform</i> (<i>scn4aa</i>) in the electric organs (EOs) and the skeletal muscle (SM) of <i>Electrophorus electricus</i>.

<p>Absolute quantification (×10³ copies of transcript per ng of cDNA) of <i>scn4aa</i> transcripts in the main EO, the Hunter’s EO, the Sach’s EO and the SM of (a) adult or (b) juvenile <i>E</i>. <i>electricus</i> kept in fresh water. Results represent means ± S.E.M. (<i>N</i> = 4). Means not sharing the same letter are significantly different (<i>P</i><0.05).</p

Protein abundances of voltage-gated Na⁺ channel β-subunit 4 isoform (Scn4b) in the electric organs (EOs) and the skeletal muscle (SM) of <i>Electrophorus electricus</i>.

<p>Representative immunoblots and protein abundances of Scn4b in the main EO, the Hunter’s EO, the Sach’s EO and the SM of (a) adult or (b) juvenile <i>E</i>. <i>electricus</i>. Protein abundance is expressed as arbitrary densitometric units per 20 μg protein. Results represent mean ± S.E.M (<i>N</i> = 3). Means not sharing the same letter are significantly different (<i>P</i> < 0.05).</p