Modulation of branchial ion transport protein expression by salinity in glass eels (Anguilla anguilla L.)

Increased renal ammonia excretion in response to metabolic acidosis is thought to be a conserved response in vertebrates. We tested the hypothesis that Rhesus (Rh) glycoproteins in the kidney of the freshwater common carp, Cyprinus carpio, play a crucial role in regulating renal ammonia excretion during chronic metabolic acidosis. Exposure to water pH 4.0 (72 h) resulted in a classic metabolic acidosis with reduced plasma arterial pH and , no change in P CO2 and large changes in renal function. Urine [NH 4 + ] as well as [titratable acidity-HCO 3 -] rose significantly over the acid exposure, but the profound reduction (fivefold) in urine flow rates eliminated the expected elevations in renal ammonia excretion. Low urine flow rates may be a primary strategy to conserve ions, as urinary excretion rates of Na + , Cl -and Ca 2+ were significantly lower during the acid exposure relative to the control period. Interestingly, renal Rhcg1 mRNA and protein levels were elevated in acid-exposed relative to control groups, along with mRNA levels of several ion transporters, including the Na + /H + exchanger, H + -ATPase and NaImmunofluorescence microscopy showed a strong apical Rhcg1 signal in distal tubules. Taken together, these data show that renal Rh glycoproteins and associated ion transporters are responsive to metabolic acidosis, but conservation of ions through reduced urine flow rates takes primacy over renal acid-base regulation in the freshwater C. carpio. We propose that an 'acid/base-ion balance' compromise explains the variable renal responses to metabolic acidosis in freshwater teleosts.

Section: Analytical Techniquesmentioning

confidence: 99%

Rh vs pH: the role of Rhesus glycoproteins in renal ammonia excretion during metabolic acidosis in a freshwater teleost fish

Wright

Wood

Wilson³

2014

“…Although the expression and activity of NKA is often directly correlated with ambient salinity in fishes (Lin et al, 2004;Bystriansky et al, 2007;Wilson et al, 2007;Kang et al, 2008), other studies have shown that NKA abundance does not correlate well with NKA activity (Lin et al, 2006;Sardella and Kultz, 2009). For example, Sardella and Kultz reported a significant increase in NKA abundance within gill MRCs of green sturgeon, Acipenser medirostris, acclimated to saline water, but no corresponding increase in NKA activity (Sardella and Kultz, 2009).…”

Section: Plasma Osmolality Urea and Electrolytesmentioning

confidence: 99%

“…This antibody was a gift from Dr (Witters et al, 1996;Choe et al, 1999;Piermarini and Evans, 2000;Catches et al, 2006). To detect VHA, an affinity-purified rabbit polyclonal antibody was made against the B subunit of eel (Anguilla anguilla) VHA (see Wilson et al, 2007;Reis-Santos et al, 2008). Rabbit polyclonal antibodies were also made against a synthetic peptide of the same conserved region (amino acid #630-643) of mammalian PDN (Royaux et al, 2000) used by Piermarini et al in D. sabina.…”

Section: Antibodiesmentioning

confidence: 99%

Branchial osmoregulation in the euryhaline bull shark, Carcharhinus leucas: a molecular analysis of ion transporters

Reilly

Cramp

Wilson

et al. 2011

SUMMARYBull sharks, Carcharhinus leucas, are one of only a few species of elasmobranchs that live in both marine and freshwater environments. Osmoregulation in euryhaline elasmobranchs is achieved through the control and integration of various organs (kidney, rectal gland and liver) in response to changes in environmental salinity. However, little is known regarding the mechanisms of ion transport in the gills of euryhaline elasmobranchs and how they are affected by osmoregulatory challenges. This study was conducted to gain insight into the branchial ion and acid-base regulatory mechanisms of C. leucas by identifying putative ion transporters and determining whether their expression is influenced by environmental salinity. We hypothesised that expression levels of the Na

“…Immunohistochemistry was performed as described in Laurent et al and Wilson et al (Wilson et al, 2007) for HRP-DAB (horse radish peroxidase, 3,3′-diaminobenzidine) and fluorescence detection, respectively. Using immunofluorescence, some sections were also double-labeled for Rh glycoproteins with Na + ,K + -ATPase α subunit using the panspecific α5 monoclonal antibody.…”

Section: The Journal Of Experimental Biology 216 (16)mentioning

confidence: 99%

“…Branchial ionocytes can be identified by high Na + ,K + -ATPase expression . Immunoblotting was performed according to Wilson et al (Wilson et al, 2007) using a Bio-Rad Mini-Protean 3 system and semi-dry transfer apparatus (Bio-Rad Laboratories, Hercules, CA, USA) with enhanced chemiluminescent detection (LAS 4000mini, FujiFilm, Tokyo, Japan). Only control fish were available for immunoblotting.…”

Section: The Journal Of Experimental Biology 216 (16)mentioning

confidence: 99%

Rh proteins and NH4+-activated Na+-ATPase in the Magadi tilapia (Alcolapia grahami), a 100% ureotelic teleost fish

Wood

Nawata

Wilson³

et al. 2013

SUMMARYThe small cichlid fish Alcolapia grahami lives in Lake Magadi, Kenya, one of the most extreme aquatic environments on Earth (pH 10, carbonate alkalinity ~300mequivl −1). The Magadi tilapia is the only 100% ureotelic teleost; it normally excretes no ammonia. This is interpreted as an evolutionary adaptation to overcome the near impossibility of sustaining an NH 3 diffusion gradient across the gills against the high external pH. In standard ammoniotelic teleosts, branchial ammonia excretion is facilitated by Rh glycoproteins, and cortisol plays a role in upregulating these carriers, together with other components of a transport metabolon, so as to actively excrete ammonia during high environmental ammonia (HEA) exposure. In Magadi tilapia, we show that at least three Rh proteins (Rhag, Rhbg and Rhcg2) are expressed at the mRNA level in various tissues, and are recognized in the gills by specific antibodies. During HEA exposure, plasma ammonia levels and urea excretion rates increase markedly, and mRNA expression for the branchial urea transporter mtUT is elevated. Plasma cortisol increases and branchial mRNAs for Rhbg, Rhcg2 and Na Supplementary material available online at