Is the dendritic organ of the striped eel catfish Plotosus lineatus an ammonia excretory organ?

Is the dendritic organ of the striped eel catfish Plotosus lineatus an ammonia excretory organ? Comp Biochem Physiol A Mol Integr Physiol. 2019 Dec 20;:110640 Authors: Kolbadinezhad SM, Coimbra J, Wilson JM Abstract The dendritic organ (DO) is a salt secretory organ in the Plotosidae marine catfishes. The potential role of the DO in ammonia excretion was investigated by examining the effects of salinity [brackishwater (BW 3‰), seawater (SW 34‰) and hypersaline water (HSW 60‰)] acclimation and DO ligation on ammonia excretion and ammonia transporter expression by immunohistochemistry (IHC), immunoblotting (IB) and qPCR. Ammonia flux rates (JAmm) were significantly lower in BW compared to SW and HSW. DO ligation resulted in a significantly lower JAmm in SW but not BW fish. IHC demonstrated apical and basolateral localization of Rhesus-associated glycoprotein (Rhag-like) and Rhbg-like proteins, respectively, in parenchymal cells of the DO acini. In the gills, which are the primary site of ammonia excretion in teleost fishes, IHC showed an apical localization of Rhag-like in some Na+/K+-ATPase (NKA) immunoreactivity (IR) cells limited to a few interlamellar regions of the filament and, in both apical and basolateral membranes of pillar cells irrespective of treatment group. In gills, the distribution of NKA-IR cells showed no salinity and/or ligation dependency. IB of Rhag and Rhbg-like proteins was found only in the gills and expr...
Source: Comparative Biochemistry and Physiology. Part A, Molecular and integrative physiology. - Category: Physiology Authors: Tags: Comp Biochem Physiol A Mol Integr Physiol Source Type: research