/* DATA DESCRIPTION: Citation: Thomsen, Jörn; Himmerkus, Nina; Holland, Nicolas; Sartoris, Franz-Josef; Bleich, Markus; Tresguerres, Martin (2017): Principles of ammonia excretion in mussels. PANGAEA, https://doi.org/10.1594/PANGAEA.871717, Supplement to: Thomsen, J et al. (2016): Ammonia excretion in mytilid mussels is facilitated by ciliary beating. Journal of Experimental Biology, 219(15), 2300-2310, https://doi.org/10.1242/jeb.139550 Abstract: The excretion of nitrogenous waste products in the form of ammonia (NH3) and ammonium (NH4+) is a fundamental process in aquatic organisms. For mytilid bivalves little is known about the mechanisms and sites of excretion. This study investigated the localization and the mechanisms of ammonia excretion in mytilid mussels. A Rh protein was found to be abundantly expressed in the apical cell membrane of the plicate organ which was previously described as a solely respiratory organ. The Rh protein was also expressed in the gill, although at significantly lower concentrations, but was not detectable in mussel kidney. Furthermore, NH3/NH4+ was not enriched in the urine suggesting that kidneys are not involved in active NH3/NH4+ excretion. Exposure to elevated seawater pH of 8.5 transiently reduced NH3/NH4+ excretion rates, but they returned to control values following 24h acclimation. This mussels had increased abundance of V-type H+-ATPase in the apical membranes of plicate organ cells: however, NH3/NH4+ excretion rates were not affected by the V-type H+-ATPase specific inhibitor concanamycin A (100 nM). On the other hand, inhibition of ciliary beating with dopamine and increased seawater viscosity significantly reduced NH3 excretion rates under control pH (8.0). These results suggest that NH3/NH4+ excretion in mytilid mussels takes place by passive NH3 diffusion across respiratory epithelia via the Rh protein, facilitated by the water current produced for filter feeding which prevents accumulation of NH3 in the boundary layer. This mechanism would be energy efficient for sessile organisms, since they already generate water currents for filter feeding. Project(s): Biological Impacts of Ocean Acidification (BIOACID) (URI: https://www.bioacid.de/) Parameter(s): Figure (Fig) * PI: Thomsen, Jörn (https://orcid.org/0000-0001-5109-7728, jthomsen@geomar.de) Species (Species) * PI: Thomsen, Jörn (https://orcid.org/0000-0001-5109-7728, jthomsen@geomar.de) Treatment (Treat) * PI: Thomsen, Jörn (https://orcid.org/0000-0001-5109-7728, jthomsen@geomar.de) Description (Description) * PI: Thomsen, Jörn (https://orcid.org/0000-0001-5109-7728, jthomsen@geomar.de) Mean, statistical (Mean) * PI: Thomsen, Jörn (https://orcid.org/0000-0001-5109-7728, jthomsen@geomar.de) Standard error [±] (Std e) * PI: Thomsen, Jörn (https://orcid.org/0000-0001-5109-7728, jthomsen@geomar.de) License: Creative Commons Attribution 3.0 Unported (CC-BY-3.0) (URI: https://creativecommons.org/licenses/by/3.0/) Size: 315 data points */ Fig Species Treat Description Mean Std e [±] 3 Mytilus californianus Conrad VHA relative protein abundance in gill 1.00 0.17 3 Mytilus californianus Conrad Rh relative protein abundance in gill 1.00 0.40 3 Mytilus californianus Conrad CA II relative protein abundance in gill 1.00 0.27 3 Mytilus californianus Conrad NKA relative protein abundance in gill 1.00 0.21 3 Mytilus californianus Conrad VHA relative protein abundance in plicate organ 2.79 0.63 3 Mytilus californianus Conrad Rh relative protein abundance in plicate organ 3.09 0.79 3 Mytilus californianus Conrad CA II relative protein abundance in plicate organ 0.43 0.07 3 Mytilus californianus Conrad NKA relative protein abundance in plicate organ 1.90 0.52 4 Mytilus edulis Linnaeus 390 µatm pCO2 pH, Haemolymph 7.56 0.04 4 Mytilus edulis Linnaeus 4000 µatm pCO2 pH, Haemolymph 7.20 0.04 4 Mytilus edulis Linnaeus HEA (2 mM NH4Cl) pH, Haemolymph 7.49 0.06 4 Mytilus edulis Linnaeus 390 µatm pCO2 pH, Urine 7.54 0.07 4 Mytilus edulis Linnaeus 4000 µatm pCO2 pH, Urine 7.28 0.05 4 Mytilus edulis Linnaeus HEA (2 mM NH4Cl) pH, Urine 7.55 0.05 4 Mytilus edulis Linnaeus 390 µatm pCO2 total ammonia, Haemolymph 1.00 0.09 4 Mytilus edulis Linnaeus 4000 µatm pCO2 total ammonia, Haemolymph 1.07 0.08 4 Mytilus edulis Linnaeus HEA (2 mM NH4Cl) total ammonia, Haemolymph 2.53 0.15 4 Mytilus edulis Linnaeus 390 µatm pCO2 total ammonia, Urine 1.14 0.14 4 Mytilus edulis Linnaeus 4000 µatm pCO2 total ammonia, Urine 1.14 0.06 4 Mytilus edulis Linnaeus HEA (2 mM NH4Cl) total ammonia, Urine 2.43 0.17 5 Mytilus californianus Conrad control pH total ammonia, Haemolymph 386.20 35.40 5 Mytilus californianus Conrad control pH total ammonia, seawater 8.40 5 Mytilus californianus Conrad high pH total ammonia, Haemolymph 452.40 88.70 5 Mytilus californianus Conrad high pH total ammonia, seawater 8.40 5 Mytilus californianus Conrad HEA total ammonia, Haemolymph 2099.20 83.30 5 Mytilus californianus Conrad HEA total ammonia, seawater 1870.40 6 Mytilus californianus Conrad control ammonia excretion 1.00 0.06 6 Mytilus californianus Conrad 1 µM dopamine ammonia excretion 0.78 0.03 6 Mytilus californianus Conrad 10 µM dopamine ammonia excretion 0.65 0.06 6 Mytilus californianus Conrad 4g PVP ammonia excretion 0.73 0.08 6 Mytilus californianus Conrad 7g PVP ammonia excretion 0.69 0.06 7 Mytilus californianus Conrad control Relative Ammonia excretion following exposure to elevated pH/HCO3-, 0-2 h after exposure 100.00 16.20 7 Mytilus californianus Conrad high Relative Ammonia excretion following exposure to elevated pH/HCO3-, 0-2 h after exposure 44.90 4.50 7 Mytilus californianus Conrad control Relative Ammonia excretion following exposure to elevated pH/HCO3-, 24 h after exposure 100.00 9.50 7 Mytilus californianus Conrad high Relative Ammonia excretion following exposure to elevated pH/HCO3-, 24 h after exposure 103.30 17.30 8 Mytilus californianus Conrad control gill VHA, Relative abundance of VHA 1.00 0.18 8 Mytilus californianus Conrad high gill VHA, Relative abundance of VHA 1.47 0.29 8 Mytilus californianus Conrad VHA plicate organ, Relative abundance of VHA 1.00 0.20 8 Mytilus californianus Conrad Rh plicate organ, Relative abundance of VHA 1.00 0.31 8 Mytilus californianus Conrad CA II plicate organ, Relative abundance of VHA 1.00 0.29 8 Mytilus californianus Conrad NKA plicate organ, Relative abundance of VHA 1.00 0.26 8 Mytilus californianus Conrad VHA plicate organ, Relative abundance of VHA 3.20 0.47 8 Mytilus californianus Conrad Rh plicate organ, Relative abundance of VHA 0.73 0.16 8 Mytilus californianus Conrad CA II plicate organ, Relative abundance of VHA 0.72 0.08 8 Mytilus californianus Conrad NKA plicate organ, Relative abundance of VHA 0.65 0.26 9 Mytilus californianus Conrad control ammonia excretion, control pH 1.00 0.24 9 Mytilus californianus Conrad Concanamycin ammonia excretion, control pH 0.81 0.17 9 Mytilus californianus Conrad control ammonia excretion, return from high pH treatment 3.65 0.21 9 Mytilus californianus Conrad Concanamycin ammonia excretion, return from high pH treatment 3.26 0.24 10 Mytilus californianus Conrad control a) relative Ammonia excretion, following 3h 2 mM ammonia load 1.00 0.07 10 Mytilus californianus Conrad control b) Hameolymph total ammonia concentration, following 3h 2 mM ammonia load 623.40 50.10 10 Mytilus californianus Conrad high pH/HCO3- a) relative Ammonia excretion, following 3h 2 mM ammonia load 0.72 0.05 10 Mytilus californianus Conrad high pH/HCO3- b) Hameolymph total ammonia concentration, following 3h 2 mM ammonia load 479.10 32.60