A 5-bromodeoxyuridine-sensitive interval during drosophila myogenesis.

Drosophila myogenesis was monitored in vitro and the cells were treated with 5-bromodeoxyuridine (BrdU) or with thymidine at certain intervals. Muscle cells were scored for survival, contractility, and the uptake of thymidine and BrdU. Results indicated that the final S period for myoblasts takes place in vitro between 1.3 and 3.3 h following the initiation of gastrulation in the donor embryos. Treatment with 10(-4) M BrdU during this internal inhibited myogenesis, but later treatment did not. Thymidine reversed or prevented the BrdU effect if given before the final myoblast division, but not if given after wards. All results support the hypothesis that BrdU inhibits Drosophila myogenesis through its incorporation into DNA.