| The dendritic organ of the Plotosidae marine catfishes an ammonia excretory organ |
| Paper ID : 1019-ICIAQUA |
| Authors |
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Salman MalakpourKolbadinezhad *1, Jonathan Wilson2 1Iranian Fisheries Science Research Institute (IFSRI), Cold-Water Fishes Research Center (CFRC), Tonekabon, Mazandaran, Iran 2Department of Biology, Wilfrid Laurier University, Waterloo, Canada, Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR/CIMAR), Universidade do Porto, Porto, Portugal |
| Abstract |
| The unique Plotosidae marine catfishes Plotosus lineatus possess dendritic organ (DO) a salt secretory organ. The potential role of the DO in ammonia excretion was investigated by examining the effects of different salinity acclimation [brackishwater (BW 3‰), seawater (SW 34‰) and hypersaline water (HSW 60‰)] and DO ligation on ammonia excretion and ammonia transporter expression using immunoblotting (IB), immunohistochemistry (IHC) and qPCR. Ammonia flux rates (JAmm) were significantly lower in BW compared to other groups. DO ligated fish showed a significantly lower JAmm in SW. The apical and basolateral localization of Rhesus-associated glycoprotein (Rhag/ Rhbg-like) proteins, respectively, detected in parenchymal cells of the DO. In the gills, 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 expression levels did not change with salinity but ligation in BW decreased Rhbg-like levels. Although Rhcg was not detected with heterologous antibodies, rhcg1 mRNA expression was detected in both gills and DO. HSW was associated with the lowest expression in DO and ligations in SW and BW were without effect on branchial expression levels. Taken together these results indicate the DO potentially has a physiological role in ammonia excretion under SW conditions. |
| Keywords |
| Plotosus lineatus, DO, Ammonia excretion, Rhesus-associated glycoprotein |
| Status: Abstract Accepted (Oral Presentation) |