Genetic key to salt-tolerance discovered in tilapia fish

March 13, 2017, UC Davis

Most fish live either in fresh water or salt water, but others, including tilapia, have the remarkable ability to physiologically adjust to varying salinity levels—a trait that may be critically important as climate change begins to alter the salinity of ocean and coastal waters as well as the water in desert lakes and creeks.

To better understand such environmental flexibility, researchers at the University of California, Davis, have now identified short DNA segments in tilapia that influence the expression of the genes that regulate the fish's internal body chemistry in response to salinity stress.

Additionally, the researchers developed an assay to identify similar regulatory DNA segments in the genomes of other fish species.

The study will be published online during the week of March 13 in the Early Edition of the Proceedings of the National Academy of Sciences.

"This work represents a critical milestone in our efforts to understand how highly stress-tolerant fish convert environmental signals and cues into very beneficial biochemical and physiological outcomes that enable them to adapt to an extremely wide salinity range that is deadly for most species," said evolutionary biochemist and senior author Dietmar Kueltz.

"If we know these mechanisms, then we can target them in situations when fish would benefit from enhanced stress tolerance, such as in aquaculture and for conservation purposes," Kueltz said.

Climate change and water salinity

Unlike humans and other land animals, fish and other aquatic animals are in a constant battle to maintain a balance between the within their bodies and the water in which they live—a process known as osmoregulation. Salt plays a key role in this balancing act. If there is too much or too little salt in the surrounding water, cell membranes, tissues and organs are damaged, and the fish or animal dies, unless it compensates for the difference.

Climate change threatens to make osmoregulation even more difficult for marine and freshwater creatures. As the polar ice caps melt, sea levels rise. This decreases the salt content of ocean water but increases salinity in . Moreover, global warming increases salinization of desert lakes and creeks. Developing an understanding of the genetic mechanisms governing osmoregulation could one day be the key for management practices that prevent extinction of a species.

New developments

In the newly published study, the researchers studied cells from the Mozambique tilapia, one of four tilapia species that readily interbreed, producing hybrids that are used worldwide in aquaculture operations. Growing rapidly, these tilapia hybrids are easy to raise and have a high tolerance for salinity stress.

The researchers identified five DNA sequences, each containing a common segment that they named OSRE1, as being enhancers of the osmoregulation and salinity-response processes.

They also laid the groundwork for manipulating the OSRE1 enhancers, paving the way for future targeted studies aimed at identifying gene regulatory networks that confer responsiveness to .

Explore further: Study sheds new light on how some fish adapt to saltwater

More information: Osmolality/salinity-responsive enhancers (OSREs) control induction of osmoprotective genes in euryhaline fish, PNAS,

Related Stories

Study sheds new light on how some fish adapt to saltwater

October 8, 2013

( —Tilapia fish readily adapt to fresh or salty water, making them both good candidates for aquaculture and potential invasive pests. New work at the University of California, Davis, shows how tilapia can change ...

Gut feeling essential for migrating fish

February 14, 2017

Why do trout spend so much time in potentially dangerous estuaries before migrating to sea? In a new thesis published at University Gothenburg, Jeroen Brijs reveals that the answer may lie in the gut.

River salinisation an urgent ecological issue

January 31, 2013

(—A just published review by Australian and European researchers has highlighted the growing global environmental problem of increasing salt levels in the world's rivers. Co-author, Dr Ben Kefford from the University ...

A crab's eye view of rising tides in a changing world

January 25, 2017

Coastal ecosystems and aquifers will be greatly affected by climate change, not only from rising temperatures and more volatile weather, including changes in precipitation patterns, but also from sea level rise.

Global warming's next surprise: Saltier beaches

August 11, 2016

Batches of sand from a beach on the Delaware Bay are yielding insights into the powerful impact of temperature rise and evaporation along the shore that are in turn challenging long-held assumptions about what causes beach ...

Recommended for you

The powerful meteor that no one saw (except satellites)

March 19, 2019

At precisely 11:48 am on December 18, 2018, a large space rock heading straight for Earth at a speed of 19 miles per second exploded into a vast ball of fire as it entered the atmosphere, 15.9 miles above the Bering Sea.

Revealing the rules behind virus scaffold construction

March 19, 2019

A team of researchers including Northwestern Engineering faculty has expanded the understanding of how virus shells self-assemble, an important step toward developing techniques that use viruses as vehicles to deliver targeted ...

OSIRIS-REx reveals asteroid Bennu has big surprises

March 19, 2019

A NASA spacecraft that will return a sample of a near-Earth asteroid named Bennu to Earth in 2023 made the first-ever close-up observations of particle plumes erupting from an asteroid's surface. Bennu also revealed itself ...

Nanoscale Lamb wave-driven motors in nonliquid environments

March 19, 2019

Light driven movement is challenging in nonliquid environments as micro-sized objects can experience strong dry adhesion to contact surfaces and resist movement. In a recent study, Jinsheng Lu and co-workers at the College ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.