"First, the kinds of mutations weren't related to the loss of Hsp90, and they weren't totally random – instead, they were related to the 'genetic background' of the stock from which the parents of the mutant flies came. This suggests that the lack of Hsp90 was releasing a Pandora's Box of mutations acquired by particular fly lineages, but which remained hidden until such time as the control exercised by Hsp90 was relaxed.

Second, mutant flies could be bred to maintain the mutations in the population, and the mutations would persist even in progeny in which Hsp90 was, once again, functional. In other words, once the mutations were out of Pandora's Box, they could not always be coaxed back in again. An episode in which Hsp90 was removed from the picture resulted in the irrevocable change of the body form of the fly."

More articles on this research is at the BBC and the Indian Academy of Sciences. Plus, if you have access to offline research papers, there's a huge bibliography