Fluorometric analysis of the green fluorescent protein
The green fluorescent protein (eGFP) concentration in culture medium and in TSP extracts of B. rapa rapa hairy roots was determined by fluorometry. Undiluted spent medium samples coming from different treatments were pipetted in pre-cooled black microtiter plates (Microfluor 2; Thermo Fisher Scientific, Waltham, MA) as triplicates. The fluorescence of the samples was determined at 485/527 nm using a VICTOR2 plate reader (Perkin Elmer, Waltham, MA) at 12 nm bandwidth and 100 ms measurement time. Sample readings were compared to a standard curve constructed with a purified GFP standard with known concentrations. For analyzing remaining intracellular eGFP after induction, TSP was extracted and analyzed as with the abovementioned fluorometric analysis.