 In various species of Drosophila, such as "D. virilis" and "D. melanogaster", the initiating methionine for translation of the "timeless" gene into TIM is in different places, with the "D. virilis" start site downstream of the start site in "D. melanogaster".The "timeless" gene is an essential component of the molecular circadian clock in "Drosophila".It acts as part of an autoregulatory feedback loop in conjunction with the period (per) gene product as noted in collaborative studies performed by the labs of Michael W. Young and Amita Sehgal.