In order to further characterize the Drosophila bioassay for screening developmental toxicants, l-phenylalanine (LPA; CAS 63-91-2), a documented human and animal teratogen, was evaluated using our published protocol (Teratogenesis, Carcinogenesis, and Mutagenesis 11:147-173, 1-91). Drosophila were exposed throughout development (egg through third instar larva) in culture vials to medium containing 0-140 mg/vial LPA. Each vial contained 1g of powered medium and 5ml of distilled deionized water or a solution of test chemical in water. A mated, untreated, Oregon-R wild-type female (MidAmerican Drosophila Stock Center) was added to each culture vial and allowed to oviposit for 20 hours, then removed. Emerging offspring were collected over 10 days, and examined microscopically (25 X ) for bent humeral bristles and wing blade notches, morpohological defects shown to occur with an increased incidence in files exposed to developmental toxicants. Mortality ranged from 33% in the controls to 7S% in the 140 mg/vial LPA group. The incidence of bent bristles was statistically increased (p<0.05) compared to concurrent controls (chi-square) at all LPA concentrations, and ranged from 1.0% (2/209) in the controls to 8.4% (10/119) in the 123 mg/vial group, the estimated LC. No wing blade notches were observed. These results provide additional support for increased utilization of this test as a prescreen for developmental toxicants.
The Toxicologist. Society of Toxicology 36th Annual Meeting, March 9-13, 1997, Cincinnati, Ohio