TIMELESS
Timeless (gene) - Wikipedia
Timeless (tim) is a gene in multiple species but is most notable for its role in Drosophila for encoding TIM, an essential protein that regulates circadian rhythm.
Timeless mRNA and protein oscillate rhythmically with time as part of a transcription-translation negative feedback loop involving the period (per) gene and its protein.
Discovery
In 1994, timeless was discovered through forward genetic screening performed by Jeffery L. Price while working in the lab of Michael W. Young.[1]
This gene was found when they noticed an arrhythmic tim01 mutant via a P element screen.[2][3]
The tim01 mutation caused arrhythmic behavior, defined by the lack of ability to establish proper circadian rhythms.[1] In 1995, the timeless gene was cloned by Amita Sehgal and partners in the lab of Michael W. Young.[4]
Unlike the Drosophila timeless gene, homologs have been discovered in other species that are non-essential for circadian rhythm.[5]
The discovery of timeless followed the discovery of the period mutants in 1971 through forward genetic screening, the cloning of per in 1984, and an experiment determining that per is circadian in 1990.
This occurred during a period of rapid expansion in the field of chronobiology in the 1990s.