Skip to main content

Research Repository

Advanced Search

Two closely related ureotelic fish species of the genus Alcolapia express different levels of ammonium transporters in gills

White, Lewis J.; Rose, Matthew; Lawson, Michael; Joyce, Domino; Smith, Alan M.; Thomas, Gavin H.; Dasmahapatra, Kanchon K.; Pownall, Mary E.


Lewis J. White

Matthew Rose

Michael Lawson

Alan M. Smith

Gavin H. Thomas

Kanchon K. Dasmahapatra

Mary E. Pownall


Most fish excrete their nitrogenous waste across the gills as ammonia through the activity of the Rhesus glycoprotein ammonium transporters. In contrast, fish of the subgenus Alcolapia (Oreochromis) are the only vertebrates that survive the extreme conditions of the soda lakes of Natron and Magadi in East Africa and have evolved adaptations to the highly alkaline waters including the ability to excrete their nitrogenous waste as urea. Nevertheless, Alcolapia retain the Rhesus glycoprotein genes in their genomes and using two heterologous expression systems, we demonstrate that Alcolapia Rhbg is capable of moving ammonia. Comparing ammonia and urea excretion from two closely related Alcolapia species from the same aquarium, we found that while Alcolapia grahami remains fully ureotelic after many generations in lab conditions, Alcolapia alcalica excretes some of its nitrogenous waste as ammonia. Using in situ hybridisation, we demonstrate robust, localised gene expression of Rhbg, rhcg1 and rhcg2 in the gill tissue in both A. alcalica embryos and adults, similar to that in other ammoniotelic fish. In contrast, the expression of these genes in A. grahami gills is much lower than in A. alcalica, suggesting the rapid evolution of a molecular mechanism underlying the complete ureotelism of A. grahami.


White, L. J., Rose, M., Lawson, M., Joyce, D., Smith, A. M., Thomas, G. H., …Pownall, M. E. (2022). Two closely related ureotelic fish species of the genus Alcolapia express different levels of ammonium transporters in gills. Biology Open, 11(11), Article bio059575.

Journal Article Type Article
Acceptance Date Oct 10, 2022
Online Publication Date Nov 7, 2022
Publication Date 2022-11
Deposit Date Dec 21, 2022
Publicly Available Date Jan 3, 2023
Journal Biology open
Electronic ISSN 2046-6390
Publisher The Company of Biologists
Peer Reviewed Peer Reviewed
Volume 11
Issue 11
Article Number bio059575
Keywords Extremophile; Ureotelic; Rhesus proteins; Amt/Mep; Rhbg
Public URL


Published article (5.4 Mb)

Publisher Licence URL

Copyright Statement
© 2022. Published by The Company of Biologists Ltd<br /> This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed.

You might also like

Downloadable Citations