β-Lactamase as a Marker for Gene Expression in Live Zebrafish Embryos

Abstract

In this report we describe the development of a sensitive assay for gene expression in zebrafish embryos using β-lactamase as a reporter gene. We show that injection of a green fluorescent substrate for β-lactamase allows the detection of reporter gene expression in live embryos. The β-lactamase enzyme catalyzes the hydrolysis of the substrate, thereby disrupting fluorescence resonance energy transfer from the donor to the acceptor dye in the molecule. As a result, a blue fluorescent product is produced and retained specifically in cells within which the enzyme is expressed. β-Lactamase is therefore suitable for monitoring spatially restricted patterns of gene expression in the early embryo. We suggest that this new reporter system provides a major advancement in sensitivity over the existing methods for monitoring gene expressionin vivoduring early embryogenesis.