...Tamara M. Rodela; M. Danielle McDonald; Patrick J. Walsh; Kathleen M. Gilmour SUMMARY In their native environment, gulf toadfish excrete equal quantities of ammonia and urea. However, upon exposure to stressful conditions in the laboratory (i.e. crowding, confinement or air exposure), toadfish...

... the movement of NH 3 across cell membranes. This study examines the effects of crowding and feeding on ammonia excretion in gulf toadfish ( Opsanus beta ) within the context of Rh glycoproteins and the ammonia-fixing enzyme, glutamine synthetase (GS). Four Rh isoforms (Rhag, Rhbg, Rhcg1 and Rhcg2) were...

...Josi R. Taylor; Martin Grosell SUMMARY Experiments on Gulf toadfish Opsanus beta demonstrate how feeding impacts osmoregulation in the marine teleost intestine. A high Ca 2+ diet of pilchards Sardina pilchardus ([Ca 2+ ]=404.2 mmol kg -1 ) was compared to a low Ca 2+ diet of common squid Loligo...

...Patrick J. Walsh; Molly J. Heitz; Catherine E. Campbell; Gordon J. Cooper; Monica Medina; Yuxiang S. Wang; Greg G. Goss; Vladimir Vincek; Chris M. Wood; Craig P. Smith ABSTRACT Urea excretion by the gulf toadfish ( Opsanus beta ) has been shown in previous studies to be a highly pulsatile...

...M. Danielle McDonald; Chris M. Wood; Yuxiang Wang; Patrick J. Walsh ABSTRACT The possible presence of a urea transporter in the kidney of the gulf toadfish ( Opsanus beta ) and further characterization of the pulsatile facilitated transporter previously identified in its gills were investigated...

...Haiyan Kong; Natalie Kahatapitiya; Kyle Kingsley; Wilmar L. Salo; Paul M. Anderson; Yuxiang S. Wang; Patrick J. Walsh ABSTRACT Gulf toadfish ( Opsanus beta ) rapidly switch to excretion of urea as their main nitrogenous waste product under several laboratory conditions, including confinement...

...Todd E. Hopkins; Chris M. Wood; Patrick J. Walsh ABSTRACT We examined the relationship between plasma cortisol levels, hepatic glutamine synthetase (GNS) activity and the form of nitrogen excreted (e.g. urea, ammonia) in undisturbed versus confined/crowded (acutely stressed) gulf toadfish...

...Patrick J. Walsh; C. Louise Milligan ABSTRACT In order to elucidate further the cues for, and the biochemical mechanisms of, the transition to ureogenesis in the gulf toadfish Opsanus beta , experiments on the effects of feeding (i.e. nitrogen loading) were carried out. Baseline nitrogen excretion...