The extended life span of Drosophila melanogaster eye-color (white and vermilion) mutants with impaired formation of kynurenine

Animal and human studies suggest that aging is associated with increased formation of kynurenine (KYN) from tryptophan (TRY). The rate-limiting factors of TRY-KYN metabolism are transmembrane transport of TRY, and activity of enzyme, TRY 2,3-dioxygenase (TDO2). Eye-color mutants, white (w1118) (impaired TRY transport) and vermilion (v48a and v2) (deficient TDO activity), were compared with wild-type Oregon-R (Ore-R) strain of Drosophila melanogaster. Female 1-day-old adult flies maintained on a standard medium, and acclimatized to 12-h light:12-h dark cycle were collected, and then regularly transferred to fresh medium every 3-4 days. The number of dead flies was recorded at the time of transfer. Forty flies were studied in each experimental group. The life span of w1118 (mean = 45.5 days), and v48a (mean = 47.6 days) and v2 (mean = 43.8 days), were significantly longer than of wild-type Ore-R flies (27.1 days) (p < 0.001, Logrank test). There were no differences in life span between w1118 and v48a and v2 mutants. Present results suggest that prolongation of life span may be associated with slow rate of KYN formation from TRY.