Abstract Many experimental approaches rely on controlling gene expression in select subsets of cells within an individual animal. However, reproducibly targeting transgene expression to specific fractions of a genetically-defined cell-type is challenging. We developed S parse P redictive A ctivity through R ecombinase C ompetition (SPARC), a generalizable toolkit that can express any effector in precise proportions of post-mitotic cells in Drosophila . Using this approach, we demonstrate targeted expression of many effectors and apply these tools to calcium imaging of individual neurons and optogenetic manipulation of sparse cell populations in vivo .

SPARC: a method to genetically manipulate precise proportions of cells