The potentialities of transplanted early gastrula nuclei ofDrosophila melanogaster. Production of their imago descendants by germ-line transplantation

Abstract

Wild-type nuclei, taken out of cells from five regions of early gastrula embryos, were implanted singly into unfertilizedy w sn ³lz^50e eggs ofDrosophila melanogaster. The different types of nuclei initiated development with nearly equal frequencies of about 60%. 2.9% of the 1073 nuclear transfers developed as far as one of the three larval instars, and one reached the pupal stage. All individuals showed stage-specific patterns of defect. Most of these abnormalities were probably due to some inevitable damage caused by the implantation procedure such as disarrangement of the internal egg morphology and loss of peripheral egg substance. The proportions of individuals arrested at different embryonic and larval stages were similar for the five nuclear groups. Fertile imagos, descendants of all five types of donor nuclei, were produced via germ-line mosaics in two ways: (1) Pole cells of nuclear-transplant blastoderm stages were implanted into the pole cell region of host blastoderm eggs. (2) Gonads were taken from nuclear-transplant larvae and implanted into host larvae. In both cases gametes developed from the transplants as could be recognized from the genotypes of their progeny. By means of suitable crosses it was possible to get clones of flies whose large chromosomes were descended from the chromosomes of only one transplanted nucleus, that is, each clone was the descendant of one somatic nucleus. The data presented show that the nuclei remain omnipotent until the early gastrula stage.