SENSITIVE AND RAPID DETECTION OF BETA-GALACTOSIDASE EXPRESSION IN INTACT-CELLS BY MICROINJECTION OF FLUORESCENT SUBSTRATE

Bacterial beta-galactosidase, coded by lacZ, is a widely used reporter for studies of transcriptional activity of eukaryotic promoters at th e single cell level. Unfortunately, current detection methods, Like X- gal cytochemistry, are slow, have suboptimal sensitivity, and are inco mpatible with cell survival. By a novel approach based on microinjecti on into cells of the fluorogenic substrate 5-chloromethylfluorescein d i-beta-D-galactopyranoside lacZ gene expression was detected without a ffecting cell viability or proliferative capacity. The method was far more sensitive than the conventional X-gal cytochemistry in all cell s ystems tested (primary hepatocytes, fibroblasts, and glioma cells). Re sults were obtained within seconds to minutes after injection, and cel ls remained fluorescent for hours. (C) 1995 Academic Press, Inc.