Ammonia excretion and expression of transport proteins in the gills and skin of the intertidal fish Lipophrys pholis

作者：Souza Bastos Luciana R; Pascoa Maria Ines; Freire Carolina A; Wilson Jonathan M^*

来源：Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology, 2014, 167: 15-24.

DOI：10.1016/j.cbpa.2013.09.009

• Ammonia excretion
• Intertidal fish
• Na+/K+-ATPase
• Rhesus glycoprotein
• Na+/H+-exchanger
• Carbonic anhydrase
• Na+:K+:2Cl(-) cotransporter

Intertidal pools are intensely challenging environments, due to rapid and extreme fluctuations in water conditions during the tidal cycle. Emersion is another challenge intertidal fishes may face. Mechanisms of ammonia excretion and ion regulation were studied in the resident amphibious blennid Lipophrys pholis. The ammonia transporters Rhcg1 and Rhcg2 were cloned and characterized. Fish were challenged for 24 h to 1) emersion, 2) fresh water (FW), and 3) high environmental ammonia (HEA; 1 mM NH4Cl), or 4) ammonia loading (1.5 mu mol/g NH4HCO3). When air exposed, L. pholis maintained aquatic ammonia excretion rates (J(Amm)) while branchial Na+/K+-ATPase (NKA) activity increased, but no changes at the protein or mRNA levels of transporters were noted. In FW,J(Amm) decreased and osmotic problems were encountered. Skin NKA activity decreased, branchial Rhcg2, and skin Rhcg1 and Rhcg2 increased. Exposure to HEA only increased branchial Rhcg2 levels. Although internal ammonia loading only led to a modest non-significant increase in J(Amm), skin NKA (activity and alpha-subunit), carbonic anhydrase protein levels, and branchial Rhcg1 levels increased. In summary, variable responses were observed involving both gill and skin but given the instability of its habitat, the constitutive expression of transporters is likely also of importance.

• 出版日期2014-1