Meeting Abstract

P2.25  Tuesday, Jan. 5  Ionizing irradiation produces a delay in pupation in the hornworm, Manduca sexta. RAMOS, L.; OMONDI, C.; HALME, A.; FUSE, M.**; San Francisco State University ; San Francisco State University ; University of California, Berkeley; San Francisco State University fuse@sfsu.edu

The imaginal discs in Drosophila melanogaster larvae are extremely resilient and are repaired extremely efficiently. Imaginal disc repair is facilitated by an endocrine-induced delay in pupation to accommodate repair of the damaged tissues. Damage within imaginal discs can be produced by the administration of high doses of irradiation during larval development. We have examined whether a similar delay can be induced by larval irradiation in another holometabolous insect, the hornworm Manduca sexta. M. sexta larvae are large and will be a useful model for characterizing the blood-borne factors regulating this developmental delay. We have found that irradiation of M. sexta larvae produces a dose-dependent delay in pupation as well as eclosion, in a manner similar to that seen in Drosophila. At low doses of irradiation, animals eclosed with minimal morphological abnormalities and were viable adults. At higher doses, adults showed significant abnormalities, but only occasionally were unable to eclose fully. Under these conditions tanning and hardening of the cuticle was also delayed. Blood transfer experiments from damaged to control animals appeared to induce delays in pupation, but to a lesser extent than seen in the damaged larvae, suggesting a blood-borne factor delays development.