Heat shock protein 90 (HSP90) helps keep proteins in the body folded properly and is thought to compensate for variations that occur in proteins over time. In a study published in Science magazine, Dr. Nicolas Rohner and colleagues showed that stress can affect the ability for HSP90 to do its job thereby unmasking these alternative versions of proteins which may lead to adaptation in some cases.
The theory was tested in fish called Mexican tetra (above), some of which adapted to life in caves leading to eventual loss of, or diminished, eyesight. The team of researchers blocked HSP90 in a group of surface dwelling fish and found that the fish developed wide variations in the size of their eyes and eye-sockets. Exposing surface dwelling fish to water similar to that found in caves also caused the variations in eyes to develop. These findings led the researchers to hypothesize that HSP90 may be an “evolutionary capacitor” that helped the fish adapt to life in caves.
N Rohner, DF Jarosz, JE Kowalko, M Yoshizawa, WR Jeffery, RL Borowsky, S Lindquist, CJ Tabin. Cryptic Variation in Morphological Evolution: HSP90 as a Capacitor for Loss of Eyes in Cavefish. Science 1372-1375, 2013.