Citation:

jeb.139550

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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)

Parameter(s):

#	Name	Short Name	Unit	Principal Investigator
1	Figure	Fig		Thomsen, Jörn
2	Species	Species		Thomsen, Jörn
3	Treatment	Treat		Thomsen, Jörn
4	Description	Description		Thomsen, Jörn
5	Mean, statistical	Mean		Thomsen, Jörn
6	Standard error	Std e	±	Thomsen, Jörn

License:

Creative Commons Attribution 3.0 Unported (CC-BY-3.0)

Size:

315 data points

Data

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1 Fig	2 Species	3 Treat	4 Description	5 Mean	6 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