Duper is a null mutation of Cryptochrome 1 in Syrian hamsters

The duper mutation is a recessive mutation that shortens the period length of the circadian rhythm in Syrian hamsters. These animals show a large phase shift when responding to light pulses. Using two distinct ecotypes and a fast homozygosity mapping strategy, we identified duper as an early nonsense allele of Cryptochrome 1 (Cry1) leading to a short, unstable protein.