An aging-independent replicative lifespan in a symmetrically dividing eukaryote

Abstract

The replicative lifespan (RLS) of a cell-defined as the number of cell divisions before death-has informed our understanding of the mechanisms of cellular aging. However, little is known about aging and longevity in symmetrically dividing eukaryotic cells because most prior studies have used budding yeast for RLS studies. Here, we describe a multiplexed fission yeast lifespan micro-dissector (multFYLM) and an associated image processing pipeline for performing high-throughput and automated single-cell micro-dissection. Using the multFYLM, we observe continuous replication of hundreds of individual fission yeast cells for over seventy-five generations. Surprisingly, cells die without the classic hallmarks of cellular aging, such as progressive changes in size, doubling time, or sibling health. Genetic perturbations and drugs can extend the RLS via an aging-independent mechanism. Using a quantitative model to analyze these results, we conclude that fission yeast does not age and that cellular aging and replicative lifespan can be uncoupled in a eukaryotic cell.

R-loops and regulatory changes in chronologically ageing fission yeast cells drive non-random patterns of genome rearrangements

“…Thus, if anything, we underestimated the prevalence of the global hotspots as sites for age-associated junction formation. Work in other systems has shown that copy numbers of rDNA repeats decrease with age, and instability in this region is linked with ageing and longevity (Spivey et al 2017;Kobayashi 2014;Lu et al 2018). The decrease of rDNA copy numbers with age could be linked to junction formation in these regions: work in primate kidney cells has demonstrated differential repair of cellular DNA sequences (Zolan et al 1982), reminiscent of the heterogeneity we observe for age-associated rearrangements.…”

“…Ribosomal RNA genes are highly transcribed and common sites of transcription and replication stress (Gaillard and Aguilera 2016; Aguilera and García-Muse 2013). Moreover, rDNA repeats can become unstable during ageing and cause cell death (Spivey et al 2017;Lu et al 2018;Kobayashi 2014).…”

A Microfluidic Device for Massively Parallel, Whole-lifespan Imaging of Single Fission Yeast Cells

“…Information on how data collected using this methodology is analyzed can be found in these references ( Greenstein et al ., 2017 ; Spivey et al ., 2017 ).…”

“…However, the low-throughput and laborious nature of this assay limits our current understanding of replicative aging. Most recently, removal of progeny cells has been automated in microfluidic devices that capture and retain individual aging cells ( Wang et al ., 2010 ; Lee et al ., 2012 ; Xie et al ., 2012 ; Zhang et al ., 2012 ; Tian et al ., 2013 ; Crane et al ., 2014 ; Nobs and Maerkl, 2014 ; Jo et al ., 2015 ; Liu et al ., 2015 ; Nakaoka and Wakamoto, 2017 ; Spivey et al ., 2017 ). Using such devices, relatively large cohorts of individual cells (100 s to 1,000 s of cells) can then be tracked independently from one another.…”

“…Here, we describe the fabrication and assembly of a microfluidic device for capturing and imaging thousands of fission yeast cells over their entire replicative lifespans. The multiplexed fission yeast lifespan microdissector (multFYLM) enables the experimentalist to track the lifespan of over a thousand fission yeast cells ( Spivey et al ., 2017 ). The cells may be continuously imaged for up to six independent populations for over a week, yielding high-resolution imaging over each cell’s replicative lifespan.…”