Figure 1
From: Development and use of a quantum dot probe to track multiple yeast strains in mixed culture
A quantum dot (QD) method to track multiple S. cerevisiae strains in mixed culture.
Conceptual diagram of quantum dot-glutathione (QD-GSH) conjugates (a) and their corresponding reference spectra after being taken up by yeast cells during 24 h of incubation (b). The blue line references QD-GSH (495 nm emission) within D254 and the red line references QD-GSH (631 nm emission) within RC212. (c) Spectral scans were collected from each fermentation, sorbel filtered and analyzed as a two-channel image; where color corresponds to the emission fingerprint associated with each QD-GSH-labelled strain. Spectral scans were collected from 470–670 nm at 5 nm intervals using an Olympus FV1000 confocal microscope. Scale bar is 25 µm. (d) Confocal laser scans of the QD-GSH probe being transferred from mother cell to daughter cell via the cytosol and vacuole. From left to right: bright field image of RC212; QD-GSH fluorescence within the yeast cell; and a superimposed image of the two. Each strain was able to transfer the QD-GSH probe from mother cell to daughter cell throughout the entire course of fermentation. Scale bars are 5 µm. (e) Uptake of QD-GSH by different S. cerevisiae knockout strains. There were five QD-GSH treatments comprised of four knockouts (opt1, ycf1, gex2, adp1) and their analogous wild type BY4743 (WT); which served as a positive control. Knockout strains lacking ADP1 transporters displayed significantly less QD-GSH uptake in comparison to every other strain, including the wild type control (p < 0.0001; n = 4). Consequently, QD-GSH was most likely acquired by yeast cells via an ADP1-mediated transport mechanism. All non-spectral confocal laser scans (535 ± 10 nm emission fluorescence) were collected at 40x using an Olympus FV1000 confocal microscope. Values are average means ± S.E.
