Live Yeast ImagingResearch Story

Prof. Sophie Martin

Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland

Vještica, A., Bérard, M., Liu, G., Merlini, L., Nkosi, P. J., & Martin, S. G. (2021) Cell cycle-dependent and independent mating blocks ensure fungal zygote survival and ploidy maintenance. PLoS biology, 19(1), e3001067

Introduction

To ensure genome stability, sexually reproducing organisms require that mating brings together exactly 2 haploid gametes and that meiosis occurs only in diploid zygotes. In the fission yeast Schizosaccharomyces pombe, fertilization triggers a signaling cascade, which represses mating and initiates meiosis.

In this research, Prof. Sophie Martin and the team from the University of Lausanne establish a system to demonstrate that mating blocks not only safeguard zygote ploidy but also prevent cell death caused by aberrant fusion attempts. This was done using long-term imaging and flow cytometry, and we identified previously unrecognized and independent roles for Mei3 and Mei2 in yeast zygotes.

Figure 1: Mei3 promotes G1 exit in stable diploid cells. (A) H1Δ17 diploid cells expressing mCherry and sfGFP from P- and M-cell-specific promoters pmap3 and pmam1 24 hours after removal of nitrogen. Arrows point to shmoo-like projections in mei3Δ and mei2Δ mutants.

Imaging Solution

These long-term fluorescence widefield imaging experiments were performed using a Prime BSI sCMOS camera in combination with a DeltaVision imaging platform and softWoRx software.

By pairing the balanced 6.5 um pixel of the Prime BSI with a 60x oil objective, high spatial resolution and great image quality were achieved. This was maintained over the long-term time-lapse experiments thanks to the reliability of the Prime BSI.

The Prime BSI is highly sensitive thanks to a combination of near-perfect quantum efficiency and low noise levels, and can image over a large field of view at a high speed.