Mexican cavefish in a tank

The Mexican cavefish lacks eyes but has adapted to thrive on a meagre diet. Credit: Zachary Zakibe

Metabolism

Blind and hungry cavefish reveal survival secrets in their genes

A mutation in Mexican cavefish helps them to gain weight on a skimpy menu.

Mexican cavefish survive starvation with the help of a genetic mutation that makes them gain weight.

Despite prolonged food shortages in their subterranean homes, some Mexican cavefish (Astyanax mexicanus) live just as long as close relatives that dwell in rivers above ground. To endure isolation so well, the cavefish must make the most of every morsel that drops into their caves.

Searching the fish’s genome, Nicolas Rohner at the Stowers Institute for Medical Research in Kansas City, Missouri, Clifford Tabin at Harvard Medical School in Boston, Massachusetts, and their colleagues found a genetic mutation linked to high blood-sugar levels. Lab experiments showed that the mutation caused cavefish to gain twice as much weight as river fish on identical diets.

High blood sugar and excess body fat are harbingers of diabetes in humans. The authors suggest that cavefish could be a useful model for investigating resistance to such diseases.

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