Abstract
We have developed a method to target gene expression in the
Drosophila
embryo to a specific cell without having a promoter that directs expression in that particular cell. Using a digitally enhanced imaging system to identify single cells within the living embryo, we apply a heat shock to each cell individually by using a laser microbeam. A 1- to 2-min laser treatment is sufficient to induce a heat-shock response but is not lethal to the heat-shocked cells. Induction of heat shock was measured in a variety of cell types, including neurons and somatic muscles, by the expression of β-galactosidase from an
hsp26-lacZ
reporter construct or by expression of a UAS target gene after induction of
hsGAL4
. We discuss the applicability of this technique to ectopic gene expression studies, lineage tracing, gene inactivation studies, and studies of cells
in vitro
. Laser heat shock is a versatile technique that can be adapted for use in a variety of research organisms and is useful for any studies in which it is desirable to express a given gene in only a distinct cell or clone of cells, either transiently or constitutively, at a time point of choice.
