Journal: bioRxiv
Article Title: Development of a dual fluorescent reporter system in Clostridioides difficile reveals a division of labor between virulence and transmission gene expression
doi: 10.1101/2022.03.03.482933
Figure Lengend Snippet: (A) Fluorescence microscopy analyses of fixed bacterial cells after overnight growth in TY liquid media. Dual reporter strains contain P sipL::mScarlet and P tcdA::mNeonGreen. Dual reporter analyses were visualized in WT, Δ tcdR , Δ spo0A and Δ rstA strain backgrounds. Phase-contrast microscopy was used to visualize all bacterial cells. The merge of mNeonGreen (yellow) with mScarlet (magenta) signals are shown. Cells expressing both P sipL::mScarlet and P tcdA::mNeonGreen are highlighted with blue arrows. (B-C) SuperSegger-based quantification of P tcdA::mNG and P sipL::mSc reporters shows the mean fluorescent intensity of each cell as a black dot on the scatterplot for the indicated reporters. Individual cell intensities were quantified from three biological replicates, with at least two fields of view per strain per replicate. The magenta, yellow, and blue dots represent the median intensity for the first, second, and third biological replicates, respectively. The gray line represents the mean value of each replicate’s median value. Percentage “Toxin-ON” is displayed ± the standard deviation. “Toxin-ON” cells were calculated using the 99 th percentile of the Δ tcdR signal as a cutoff (value displayed as a pink dotted line). Percentage “Sporulation-ON” was calculated using 1000 RFU signal as a cutoff (value displayed as a pink dotted line; green dotted line represents the 500 RFU cut-off for “Sporulation-ON” cells for Δ tcdR and Δ spo0A ). This cut-off was determined using the histogram analyses in . A minority of points (<1%) are outside the limits of the scatterplot; axes were adjusted to provide an optimal view of the scatterplot trends. Statistical significance was determined relative to wild type using a one-way ANOVA and Tukey’s test. ***p<0.001, ** p < 0.01. (D) Scatterplot analyses show single cell mean fluorescent intensities with P sipL::mSc on the x-axis and PtcdA::mNG on the y-axis. “Toxin-ON” cutoff is represented by the yellow dotted line which indicates 99 th percentile of the Δ tcdR signal. “Sporulation-ON” cutoff is represented by the magenta dotted line at 1000 RFU based on the histogram bimodal distribution analyses. Percentages indicate Toxin-ON/Sporulation-OFF in the top left quadrant, Toxin-ON/Sporulation-ON in the top right quadrant, Toxin-OFF/Sporulation-OFF in the bottom left quadrant and Toxin-OFF/Sporulation-ON in the bottom right quadrant. A minority of points (<1%) are outside the limits of the scatterplot; axes were adjusted to provide an optimal view of the scatterplot trends.
Article Snippet: Images were quantitatively analyzed using the SuperSegger pipeline ( ) in MATLAB with the supplied ‘60x’ analysis settings.
Techniques: Fluorescence, Microscopy, Expressing, Standard Deviation