The use of photoactivatable reagents for the study of cell lineage in Drosophila embryogenesis.

Photoactivatable lineage tracers represent a major advance for clonal analysis in the early embryo and the study of cell movements. Any cell in the blastoderm can be marked, and the nuclear localization of the signal allows excellent resolution in identifying the daughters of individual cells. Although the technique is limited by the availability of the water-soluble caged fluorescein and its derivatives for synthesis of the complete tracer, these may become commercially available in the future. The use of caged rhodamine derivatives or antibody amplification of the signal may greatly extend the developmental period over which marked clones can be identified.