A cell-autonomous, ubiquitous marker for the analysis of Drosophila genetic mosaics.

Mosaic analysis, the study of animals containing cells of two different genotypes, has been used to address a wealth of questions in developmental biology. Up to now, the cell markers used to distinguish cells of the two genotypes have only been applicable to specific experimental situations (e.g., only in adult wings). We have designed a general purpose cell marker for mosaic analysis. It consists of the bacterial LacZ gene expressed under the control of the constitutive promoter of the Drosophila armadillo gene. Transformants carrying this fusion gene express beta-galactosidase in all tissue and at all stages analyzed. Zygotic expression is detectable as early as gastrulation. In mosaics obtained by nuclear transplantation, cells carrying the transgene are easily distinguished from beta-galactosidase-negative host cells. The marker should also be useful for mosaics generated with the "Flp technique."