Yeast autofluorescence

A direct comparison of some representative sensors to estimate biomass in bacterial and yeast cultures was made by Nipkow et al. [309], by Fehrenbach et al. [107], by Konstantinov et al. [219] and, more recently, by Wu et al. [465]. These studies are of importance because the sensors were mounted in situ and used in parallel. Most of the sensors measured the optical density (OD), one the autofluorescence of the cultures (fluorosensor) and another was a capacitance sensor (Cugmeter). 

Analyze (i.e. acquire data but do not sort) -50,000 unstained cells to create a gate containing yeast cells on the basis of forward scatter and side scatter properties, as well as to control for autofluorescence. (If compensation is needed, analyze the singly-stained cells and compensate for emission overlap (see Note 12))... 

Since increased 02 generation appeared to correlate with increased carotenoid biosynthesis, we examined the effect of DQ exposure on carotenoid levels and composition. Exposure of cultures to DQ increased the levels of carotenoid produced by about 40%, and also increased the relative proportion of xanthophylls and diminished the levels of carotene precursors (31). In addition to producing more carotenoids, the increased proportion of xanthophylls would provide greater resistance to oxidative stress since xanthophylls are generally more effective antioxidants than carotenes (2). This pattern of increased levels of carotenoids and a higher proportion of xanthophylls also takes place as cultures age. The astaxanthin pathway may function in part to prevent aging of yeast and possibly to supply antioxidant capacity to their progeny. Microscopic examination of autofluorescence supported that carotenoids are... 

FIGURE 21.6 Chemical cytometry of a single yeast cell expressing the GFP-Gal4 fusion protein. The autofluorescence signal is similar in amplitude to the signal due to the fluorescent protein without electrophoresis, accurate quantiflcation of fluorescence due to the fusion protein would be difficult. 

Damage to the respiratory chain is correlated with a decrease in ATP production and a lack of certain enzymes and cytochromes. These defects can be detected by measuring the autofluorescence of flavine molecules in intact and respiratory-deficient yeast strains with advanced microscopic techniques [1527a]. 

Damage to the respiratory chain is correlated with a decrease in ATP production and a lack of certain enzymes and cytochromes. These defects can be detected by measuring the autofluorescence of flavin molecules in intact and respiratory deficient yeast strains with advanced microscopic techniques [15.114]. The combination of time-resolved laser spectroscopic techniques with a laser scanning microscope opens new possibilities for the investigation of dynamical processes with high spatial resolution. This is demonstrated in [15.114b] by time-resolved fluorescence measurements of carcinoma cells compared with normal cells. 

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