Experimental manipulations of early Drosophila embryos. I. Adult and embryonic defects resulting from microcautery at nuclear multiplication and blastoderm stages.

Abstract

Localized regions of Drosophila eggs were damaged at both nuclear multiplication and blastoderm stages, using the technique of microcautery. The resulting defects in embryos and adults were recorded in order to study the effects of microcautery on determination of larval and adult structures. Using 70 °C microcautery, few specific defects were found in either embryos or adults. Sensitivity maps relating embryonic mortality to sites of damage were prepared for both egg stages and compared. Microcautery at 75 °C was used to check experimentally the putative localization in the egg of adult disc cells, as indicated by genetic mosaic studies. Although some of the expected adult defects were found, there was also evidence for regulation. Localized embryonic defects were found using this higher temperature, such that anterior damage produced anterior defects and posterior damage led to posterior defects. Mid-region microcautery resulted in both anterior and mid-region defects, the latter being most common after damage to the blastoderm. Comparisons are made with results obtained using other experimental manipulations and with the development of some embryonic lethal mutants.