Double abdomen induction with low UV-doses inSmittia spec. (Chironomidae, diptera): Sensitive period and complete photoreversibility

Abstract

In embryos of the chironomid midgeSmittia spec., UV-irradiation of anterior pole regions results in double abdomen formation. In this abnormal body pattern, head and thorax are replaced by a mirror image of the abdomen. Irradiation at a particular stage between nuclear migration and blastoderm formation, and with the anterior pole facing the UV-beam, yields 100% double abdomens after a minimum UV-dose (140 J·m at 285 nm wavelength). By subsequent exposure to light of longer wavelength, embryos can be reprogrammed so that they develop normally again. The irradiation procedure described is suitable for programming large numbers of embryos for double abdomen formation, with a minimum of side effects and virtually complete photoreversibility.

Synthesis of a posterior indicator protein in normal embryos and double abdomens of Smittia sp. (Chironomidae, Diptera).

“…A monochromator ap paratus described earlier (6) was used for both UV irradiation (285 nm, 3 W/m2, 47 sec) and photoreversal (440 nm, 3 W/m2, 30 min). Embryos were lined up in a groove between two coverslips and UV irradiated at stage M2-PB (7 hr after egg deposition) with their anterior poles facing the beam (12). Immediately thereafter they were either incubated in the dark or exposed to photoreverting light.…”