Lens crystallins may be moonlighting.

Lens crystallins may be moonlighting

After 25 million years of blindness, why do mole rats, with their evolutionarily atrophied eyes, still have ocular lenses? A novel experiment sheds new light on alpha-crystallin--the eye lens protein that has already impressed scientists as a model of structural and functional elegance (SN: 6/27/87, p.409).

Wiljan Hendriks and his colleagues at the University of Nijmegen, the Netherlands, report that they have determined the nucleotide sequence for the gene that codes for mole rat crystallin. They compared that sequence to the crystallin code in rodents that have evolved with normal vision. Mole rat crystallin has remained remarkably unchanged, they found-- despite the fact that, being blind, mole rats are under no apparent selective pressure to keep making the protein. The researchers suggest that crystallin may serve other, less obvious, selective advantages.

Crystallin seems to be involved, for example, in the embryological development of the rudimentary retina that mole rats retain. And there is good evidence, the researchers say, that the mole rat's retina, "though not able to detect light anymore, is still of vital importance for photoperiod perception, which is required for the physiological adaptations of the animal to seasonal changes.' The researchers published their findings in the August PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES (Vol.84, No.15).