Circadian rhythm and theper ACNGGN repeat in the mole rat,Spalax ehrenbergi

Individual variability in circadian locomotor activity has recently been discovered in the blind mole rat,Spalax ehrenbergi. An interesting association was found between different circadian activity types and two DNA fragments, 5.6 and 5.9 kb long, that contain the ACNGGN repeat sequence, homologous to a part of theperiod gene ofDrosophila. Nine of 12 arrythmic animals showed the 5.6-kb band, while 13 of 17 circadian rhythmic animals had the 5.9-kb band. This repeat exists also in the brain RNA of the mole rat, apparently in higher quantities during the sleeping phase, suggesting that an unusual protein(s), composed of a poly-Thr-Gly segment, affects its circadian rhythm.