Active Ammonia excretion in the giant mudskipper, Periophthalmodon schlosseri (Pallas), during emersion

Abstract

The main objective of this study was to determine whether active NH(4) (+) excretion occurred in the giant mudskipper, Periophthalmodon schlosseri, during emersion. Our results demonstrated that continual ammonia excretion in P. schlosseri during 24 hr of emersion resulted in high concentrations ( approximately 30 mmol l(-1)) of ammonia in fluid collected from the branchial surface. For fish injected intraperitoneally with 8 mumol g(-1) ammonium acetate (CH3COONH4) followed by 24 hr of emersion, the cumulative ammonia excreted was significantly greater than that of the control injected with sodium acetate. More importantly, the ammonia excretion rate at hour 2 in fish injected with CH3COONH4 followed by emersion was greater than that in fish immersed in water as reported elsewhere, with the greatest change in the ammonia excretion rate occurring at hour 2. Assuming that the rate of endogenous ammonia production remained unchanged, 33% of the exogenous ammonia was excreted through the head region, presumably through the gills, during the first 6 hr of emersion. Indeed, at hour 6, the ammonia concentration in the branchial fluid increased to an extraordinarily high concentration of >90 mmol l(-1). Therefore, our results confirm for the first time that P. schlosseri can effectively excrete a high load of ammonia on land, and corroborate the proposition that active NH(4) (+) excretion through its gills contributes in part to its high tolerance of aerial exposure. Only 4.6% of the exogenous ammonia was detoxified to urea. The glutamate contents in the muscle and liver also increased significantly, but the glutamine contents remained unchanged.

A Fish Out of Water: Gill and Skin Remodeling Promotes Osmo- and Ionoregulation in the Mangrove KillifishKryptolebias marmoratus

“…The physiological significance of these changes in the FW gill is unknown. Fish in our experiments had no opportunity to gulp water when in aerial conditions, and to our knowledge, there are no reports in the literature of this behavior, but it has been observed in amphibious mudskippers, P. cantonensis and Periophthalamus schlosseri (Chew et al 2007). It is still possible, however, that the gills have access to water in some terrestrial habitats.…”

Both seawater acclimation and environmental ammonia exposure lead to increases in mRNA expression and protein abundance of Na+:K+:2Cl− cotransporter in the gills of the climbing perch, Anabas testudineus

“…It can survive for many days in 100 mmol l ¡1 NH 4 Cl (pH 7), a concentration at which many Wshes would succumb within minutes of exposure. Anabas testudineus has the uncommon ability to actively excrete ammonia against inwardly directed P NH3 and NH 4 + electrochemical gradient (Tay et al 2006), a feat which is shared by only two other teleosts, the stenohaline freshwater African sharptooth catWsh (Clarias gariepinus; Ip et al 2004) and the euryhaline brackish giant mudskipper (Periophthalmodon schlosseri; Peng et al 1998;Randall et al 1999;Chew et al 2003Chew et al , 2007Ip et al 2005). In the case of the giant mudskipper, the ouabain and amiloride sensitivities of the transport process led Randall et al (1999) to suggest that NH 4 + was transported from the blood into the MRCs by the basolateral Nka with NH 4 + substituting for K + , and from the MRCs to the external medium by the apical Na + / H + (NH 4 + ) exchanger.…”

Adaptations of a deep sea scavenger: High ammonia tolerance and active NH 4 + excretion by the Pacific hagfish ( Eptatretus stoutii )

“…However, some teleosts either live in or are transiently exposed to environments that do not favor ammonia excretion such as the Lake Magadi tilapia (Oreocrhomis alcalicus graham) which lives in highly alkaline (~pH 10) water (Randall et al, 1989), and certain air breathing fishes including the lungfishes (Smith, 1930;Janssens and Cohen, 1968;Wood et al, 2005). Strategies for detoxification include increases in glutamine production to detoxify ammonia as employed by the swamp eel Monopterus albus (Ip et al, 2004), ammonia volatilization as used by mangrove killifish (Kryptolebias marmoratus) during air exposure (Frick and Wright, 2002), and even active NH 4 + transport, as proposed for the mudskipper (Periophthalmodon schlosseri) and the climbing perch (Anabas testudineus) during exposure to air or exposure to high environmental ammonia (Randall et al, 1999;Wilson et al, 2000;Tay et al, 2006;Chew et al, 2007;Ip et al, 2012). The swamp eel and weatherloach (Misgurnus anguillacaudatus) are also able to withstand millimolar increases in plasma ammonia (Chew et al, 2001;Tsui et al, 2002;Ip et al, 2004).…”