Researchers at the University of California, Davis, have identified short DNA segments in tilapia that influence the expression of the genes regulating the fish's response to salinity stress. Most fish live either in freshwater or saltwater, but  tilapia has a remarkable ability to adjust to varying salinity levels.

Salt plays a major role in osmoregulation, a process that fishes and other aquatic animals do to maintain a balance between the water within their bodies and the water in which they live. Climate change continues to threathen osmoregulation. As polar ice caps melt, salt in ocean water decreases, but increases in coastal waters, increasing salinization of desert lakes and creeks.

To understand the genetic mechanisms governing osmoregulation, the researchers studied cells from the rapidly growing Mozambique tilapia. They 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, for future targeted studies aimed at identifying gene regulatory networks that confer salinity responsiveness to fish.

For more details, read the article at the UC Davis website.

Figure: Studying Mozambique tilapia, the researchers found that short DNA segments enhance expression of genes that regulate the fish's internal body chemistry in response to salinity stress. (Photo by Greg Hume/Creative Commons)