Abstract
It has been repeatedly reported that transposable elements (TE) become active and/or mobile in the genomes of replicatively and stress-induced senescent mammalian cells. However, the biological role of senescence-associated transposon activation and its occurrence and relevance in other eukaryotic cells remain to be elucidated. In the present study, Candida albicans, a prevalent opportunistic fungal pathogen in humans, was used to analyze changes in gene copy number of selected TE, namely Cirt2, Moa and Cmut1 during long-term culture (up to 90 days). The effects of stress stimuli (fluconazole, hydrogen peroxide, hypochlorite) and ploidy state (haploid, diploid, tetraploid cells) were also considered. An increase in copy number of Cirt2 and Moa was the most accented in tetraploid cells after 90 days of culture that was accompanied by changes in karyotype patterns and slightly more limited growth rate compared to haploid and diploid cells. Stress stimuli did not potentiate TE activity. Elevation in chromosomal DNA breaks was also observed during long-term culture of cells of different ploidy, however this was not correlated with increased TE activity. Our results suggest that increased TE activity may promote genomic diversity and plasticity, and cellular heterogeneity during long-term culture of C. albicans cells.
Highlights
The budding yeast Saccharomyces cerevisiae has become the most popular unicellular and genetically tractable aging model system, playing a key role in the discovery of Sir2, TOR, RAS, adenylate cyclase, PKA and S6 kinase as conserved modulators of longevity in eukaryotes (Kaeberlein 2010; Longo et al 2012)
We have used a model of longterm culture of C. albicans cells and started the culture at relatively high cell density (1 9 108 cells/ml) to mimic stationary phase conditions during chronological aging (CA) in yeast that is measured by monitoring the survival of a non-dividing population (Longo et al 2012; Hu et al 2013)
Rich medium (YPD medium) was considered instead of a classical CA medium, namely synthetic complete (SC) medium and yeast extract peptone dextrose (YPD) medium was replaced by a fresh one every 48 h of culture to avoid starvation and related stress responses that are common during CA in yeast (Longo et al 2012; Hu et al 2013)
Summary
The budding yeast Saccharomyces cerevisiae has become the most popular unicellular and genetically tractable aging model system, playing a key role in the discovery of Sir, TOR, RAS, adenylate cyclase, PKA and S6 kinase as conserved modulators of longevity in eukaryotes (Kaeberlein 2010; Longo et al 2012). There are two assays for yeast aging, namely the evaluation of replicative lifespan (RLS) and chronological lifespan (CLS) (Kaeberlein 2010; Longo et al 2012). A new distinctive microbial model for cellular aging has been established, namely Candida albicans, a polymorphic fungus and a prevalent opportunistic fungal pathogen in humans (Fu et al 2008). Both RLS as well as CLS assays have been adapted to C. albicans aging studies (Fu et al 2008; Chen et al 2012; Lin and Austriaco 2014). C albicans as a Crabtree negative fungus that prefers respiration to fermentation even in the presence of glucose may be considered as a good model for providing complimentary comparisons to aging and calorie restriction studies in a Crabtree positive S. cerevisiae (Lin and Austriaco 2014)
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 call
