Animal Osmoregulation Group

Convenor: Jehan-herve Lignot (University of Montpellier, France)

This group is interested in a broad spectrum of research that encompasses the field of animal osmoregulation. Ion-transport, acid–base balance, links between feeding and osmoregulation, toxicological effects on osmoregulation, endocrine and neuroendocrine control of osmoregulation are just some of the topics that have been recently covered at sessions organised by our group at the Annual Meetings. These areas are investigated at a variety of different levels including in vitro techniques, gene expression, ion fluxes of whole animals and – central to our interests – the integration of other aspects of physiology with osmoregulation.

Examples of animals studies within our group include the Lake Magadi tilapia (Oreochromis alcalicus grahami), which lives in environments with pH as high as 9.9, a condition that would be fatal to almost all teleost fish. Oreochromis alcalicus grahami show a severe metabolic acidosis when placed in water of neutral pH, which interferes with their ability to produce urea. When drinking large quantities of the alkaline water in which it lives, Oreochromis alcalicus grahami protects its stomach with an anatomical side-pocketing of the stomach.

Environmental influences on osmoregulation are a major focus of our group. For example, the Amazonian cichlid, Astronotus ocellatus, is extremely resistant to hypoxia and has an amazing ability to regulate ion homeostasis during periods of low oxygen. During hypoxia, these animals avoid a marked disturbance of internal ion status by simultaneously reducing sodium pumping and leak rates at the gills.