Abstract
An imaging-integrated microfluidic cell volume sensor was used to evaluate the volumetric growth rate of single cells from a Saccharomyces cerevisiae population exhibiting two phenotypic expression states of the PDR5 gene. This gene grants multidrug resistance by transcribing a membrane transporter capable of pumping out cytotoxic compounds from the cell. Utilizing fluorescent markers, single cells were isolated and trapped, then their growth rates were measured in two on-chip environments: rich media and media dosed with the antibiotic cycloheximide. Approximating growth rates to first-order, we assessed the fitness of individual cells and found that those with low PDR5 expression had higher fitness in rich media whereas cells with high PDR5 expression had higher fitness in the presence of the drug. Moreover, the drug dramatically reduced the fitness of cells with low PDR5 expression but had comparatively minimal impact on the fitness of cells with high PDR5 expression. Our experiments show the utility of this imaging-integrated microfluidic cell volume sensor for high-resolution, single-cell analysis, as well as its potential application for studies that characterize and compare the fitness and morphology of individual cells from heterogeneous populations under different growth conditions.
Highlights
A crucial factor in understanding cellular function is the strong coupling to environmental conditions, such as salinity[20], osmotic stress[21], and nutrient availability[22]
We investigate a strain of budding yeast (Saccharomyces cerevisiae) exhibiting two phenotypic expression states of the PDR5 gene, high-expressing (HE) and low-expressing (LE)
Using flow cytometry to characterize the PDR5 expression, we found that for log-phase cells grown in yeast extract-peptone-galactose (YPgal), the majority exists in a low-expressing (LE) state, while a small subpopulation persists in a high-expressing (HE) state with a PDR5 expression level that is about 10 times higher
Summary
A crucial factor in understanding cellular function is the strong coupling to environmental conditions, such as salinity[20], osmotic stress[21], and nutrient availability[22]. The device traps an individual cell in a sensing channel and directly measures its volume and growth rate over time This platform has full microscopy integration and on-chip media exchange, which allows for control of growth conditions and the introduction of drugs. As such, it enables accurate quantification of single-cell reproductive fitness in different environments by measuring cellular volume directly, as opposed to inferring volume by assuming geometries and measuring radii using two-dimensional data acquired by traditional imaging and light scattering methods. Our results demonstrate the applicability of this microfluidic platform for characterizing the growth response and fitness of single cells in different environments
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
