Fig. 2.

Fluorescence microscopy and quantitative assessment of hydrolysis of compounds 1–6 catalyzed by endogenous cellular esterases. Substrates 1–6 (10 μM) were applied to Drosophila S2 cells, human embryonic kidney cells (HEK 293), human uterus carcinoma cells (HeLa), Chinese hamster ovary carcinoma cells (CHO), dissociated rat hippocampal primary neuronal culture, mouse fibroblast cells (CCL-1), and mouse cortical brain slice for 1 h and imaged live. (A) Substrate 1. (B) Substrate 2. (C) Substrate 3. (D) Substrate 4. (E) Substrate 5. (F) Substrate 6. Cultured cells were counterstained with Hoechst 33342 and imaged using wide-field fluorescence microscopy. Brain slices were imaged using two-photon microscopy. Magnification was adjusted to ensure several cells were within the imaging field. (Scale bars: 10 μm.) (G) Quantification of background-subtracted average cellular fluorescence (relative fluorescence units, RFU) after incubation with substrates 1–6. Error bars show mean ± SD.