Nuclear Transplantation in Drosophila melanogaster

Abstract

IT has been known for some time that factors in the cytoplasm of many eggs can influence the development of the cells, part of which they eventually constitute. This is most clearly seen in the case of the germ cell determinants. The removal of a particular region of the egg (the “pole plasm”) results in the absence of germ cells in the resulting animals¹. We have begun an analysis of nuclear and cytoplasmic interactions in the egg of Drosophila melanogaster by means of nuclear transplantations. The advantages of Drosophila are its well described genetics and development; its disadvantages are the small size of the egg, its extreme sensitivity to minor damage to the egg membranes and the high turgor of the egg cell. Although nuclear transplantations in other animals have been fruitful², two earlier attempts with Drosophila^3,4 yielded a few differentiated larvae, but no adults. This was probably because injected eggs usually develop abnormalities which lead to early death of the embryo. We have tried to bypass this difficulty by culturing early embryonic stages in adult females and then causing them to metamorphose, a procedure developed independently by Hadorn et al.⁵ and Gateff and Schneiderman⁶. This made it possible to assess the developmental capacities of embryos from nuclear transplantations which underwent a great deal of development but would never have hatched.