Urea excretion by the gulf toadfish (Opsanus beta) has been shown in previous studies to be a highly pulsatile facilitated transport, with excretion probably occurring at the gill. The present study reports the isolation of an 1800 base pair (kb) cDNA from toadfish gill with one open reading frame putatively encoding a 475-residue protein, the toadfish urea transporter (tUT). tUT, the first teleostean urea transporter cloned, has high homology with UTs (facilitated urea transporters) cloned from mammals, an amphibian and a shark, and most closely resembles the UT-A subfamily. When expressed in Xenopus laevis oocytes, tUT increased urea permeability (as measured by [(14)C]urea uptake) five- to sevenfold, and this permeability increase was abolished by phloretin, a common inhibitor of other UTs. Northern analysis using the 1.8 kb clone was performed to determine the tissue distribution and dynamics of tUT mRNA expression. Of six tissues examined (gill, liver, red blood cells, kidney, skin and intestine), only gill showed expression of tUT mRNA, with a predominant band at 1.8 kb and a minor band at 3.5 kb. During several points in the urea pulse cycle of toadfish (0, 4, 6, 12 and 18 h post-pulse), measured by excretion of [(14)C]urea into the water, gill mRNA samples were obtained. Expression of tUT mRNA was found to be largely invariant relative to expression of beta-actin mRNA over the pulse cycle. These results further confirm the gill localization of urea transport in the toadfish and suggest that tUT regulation (and the regulation of pulsatile urea excretion) is probably not at the level of mRNA control. The results are discussed in the context of the mechanisms of vasopressin-regulated UT-A in mammalian kidney and morphological data for the toadfish gill.
Celebrating 100 years of discovery
We are proud to be celebrating 100 years of discovery in Journal of Experimental Biology. Visit our centenary webpage to find out more about how we are marking this historic milestone.
Craig Franklin launches our centenary celebrations
Editor-in-Chief Craig Franklin reflects on 100 years of JEB and looks forward to our centenary celebrations, including a supplementary special issue, a new early-career researcher interview series and the launch of our latest funding initiatives.
Looking back on the first issue of JEB
Journal of Experimental Biology launched in 1923 as The British Journal of Experimental Biology. As we celebrate our centenary, we look back at that first issue and the zoologists publishing their work in the new journal.
Webinar: Increasing the visibility and impact of your research
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Would you like to increase the visibility and impact of your research and raise your profile internationally? If so, register for the very practical webinar we are running in association with HUBS on 23 February 2023.
Biology Communication Workshop: Engaging the world in the excitement of research
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We are delighted to be sponsoring a Biology Communication Workshop for early-career researchers as part of JEB’s centenary celebrations. The workshop focuses on how to effectively communicate your science to other researchers and the public and takes place the day before the CSZ annual meeting, on 14 May 2023. Find out more and apply here.
Mexican fruit flies wave for distraction
Dinesh Rao and colleagues have discovered that Mexican fruit flies vanish in a blur in the eyes of predatory spiders when they wave their wings at the arachnids, buying the flies time to make their escape.
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