title: Branchial nitrogen cycle symbionts can remove ammonia in fish gills.
abstract: Knowledge of the mechanisms by which fish excrete their metabolic nitrogenous waste and insights into nitrogen cycling in aquaculture systems is of utmost importance to improve the sustainable commercial production of fish. In fish, most nitrogenous waste is excreted via the gills as ammonia, a potentially toxic nitrogenous compound. In this study; activity assays, physiological experiments, molecular analysis and microscopy were used to show that the gills of fish harbor a unique combination of hitherto overlooked nitrogen-cycle microorganisms that can theoretically detoxify excreted ammonia by converting it into inert dinitrogen gas. By doing so, these microorganisms may benefit from the ammonia supply by the host and prevent the build-up of this compound to toxic concentrations. This novel relationship between vertebrates and microorganisms may shed new light on nitrogen handling by ammonotelic fish species.
authors.affiliation: Departments of Microbiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525, AJ, Nijmegen, The Netherlands.|Organismal Animal Physiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525, AJ, Nijmegen, The Netherlands.
authors.forename: Maartje A H J
authors.initials: MAHJ
authors.lastname: van Kessel
authors.affiliation: Departments of Microbiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525, AJ, Nijmegen, The Netherlands.
authors.forename: Rob J
authors.initials: RJ
authors.lastname: Mesman
authors.affiliation: Departments of Microbiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525, AJ, Nijmegen, The Netherlands.
authors.forename: Arslan
authors.initials: A
authors.lastname: Arshad
authors.affiliation: Organismal Animal Physiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525, AJ, Nijmegen, The Netherlands.
authors.forename: Juriaan R
authors.initials: JR
authors.lastname: Metz
authors.affiliation: Organismal Animal Physiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525, AJ, Nijmegen, The Netherlands.
authors.forename: F A Tom
authors.initials: FAT
authors.lastname: Spanings
authors.affiliation: Organismal Animal Physiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525, AJ, Nijmegen, The Netherlands.
authors.forename: Stephanie C M
authors.initials: SCM
authors.lastname: van Dalen
authors.affiliation: Departments of Microbiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525, AJ, Nijmegen, The Netherlands.
authors.forename: Laura
authors.initials: L
authors.lastname: van Niftrik
authors.affiliation: Organismal Animal Physiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525, AJ, Nijmegen, The Netherlands.
authors.forename: Gert
authors.initials: G
authors.lastname: Flik
authors.affiliation: Ecology and Ecophysiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525, AJ, Nijmegen, The Netherlands.
authors.forename: Sjoerd E
authors.initials: SE
authors.lastname: Wendelaar Bonga
authors.affiliation: Departments of Microbiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525, AJ, Nijmegen, The Netherlands.
authors.forename: Mike S M
authors.initials: MSM
authors.lastname: Jetten
authors.affiliation: Organismal Animal Physiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525, AJ, Nijmegen, The Netherlands.
authors.forename: Peter H M
authors.initials: PHM
authors.lastname: Klaren
authors.affiliation: Departments of Microbiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525, AJ, Nijmegen, The Netherlands.
authors.forename: Huub J M
authors.initials: HJM
authors.lastname: Op den Camp