Lamprey parasitism of sharks and teleosts: high capacity urea excretion in an extant vertebrate relic

Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology
Michael P WilkieJ H Youson

Abstract

We observed 10 sea lampreys (Petromyzon marinus) parasitizing basking sharks (Cetorhinus maximus), the world's second largest fish, in the Bay of Fundy. Due to the high concentrations of urea in the blood and tissues of ureosmotic elasmobranchs, we hypothesized that sea lampreys would have mechanisms to eliminate co-ingested urea while feeding on basking sharks. Post-removal urea excretion rates (J(Urea)) in two lampreys, removed from separate sharks by divers, were initially 450 ( approximately 9000 micromol N kg-1 h-1) and 75 times ( approximately 1500 micromol N kg-1 h-1) greater than basal (non-feeding) rates ( approximately 20 micromol N kg-1 h-1). In contrast, J(Urea) increased by 15-fold after parasitic lampreys were removed from non-ureosmotic rainbow trout (Oncorhynchus mykiss). Since activities of the ornithine urea cycle (OUC) enzymes, carbamoyl phosphate synthetase III (CPSase III) and ornithine carbamoyl transferase (OCT) were relatively low in liver and below detection in intestine and muscle, it is unlikely that the excreted urea arose from de novo urea synthesis. Measurements of arginase activity suggested that hydrolysis of dietary arginine made a minor contribution to J(Urea.). Post-feeding ammonia excretion r...Continue Reading

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Citations

Aug 14, 2012·Genome Biology and Evolution·Shigehiro KurakuAxel Meyer
Aug 25, 2010·Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology·Marvin H Braun, Steve F Perry
Aug 30, 2005·Comparative Biochemistry and Physiology. Part B, Biochemistry & Molecular Biology·Saleh A MohamedSoha M Hamdy
Dec 17, 2014·Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology·Alexander M CliffordMichael P Wilkie
Aug 28, 2020·Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology·Julia SungaMichael P Wilkie
Jan 7, 2005·The Journal of Experimental Biology·J Anne BrownJ Cliff Rankin
Apr 27, 2013·The Journal of Experimental Biology·Carol BuckingPatrick J Walsh
Sep 21, 2021·Frontiers in Microbiology·Prince P MathaiMichael J Sadowsky
May 19, 2009·The Journal of Experimental Biology·Dirk WeihrauchPatrick J Walsh

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