scholarly journals Unconventional cell division cycles from marine-derived yeasts

2019 ◽  
Author(s):  
Lorna M.Y. Mitchison-Field ◽  
José M. Vargas-Muñiz ◽  
Benjamin M. Stormo ◽  
Ellysa J.D. Vogt ◽  
Sarah Van Dierdonck ◽  
...  
Keyword(s):  
Cell Division ◽  
Cell Polarity ◽  
Stress Resistance ◽  
Size Control ◽  
Time Lapse ◽  
Model System ◽  
Black Yeasts ◽  
Differential Interference Contrast ◽  
Marine Habitat ◽  
Unique Species

AbstractFungi have been found in every marine habitat that has been explored, however, the diversity and functions of fungi in the ocean are poorly understood. In this study, fungi were cultured from the marine environment in the vicinity of Woods Hole, MA, USA including from plankton, sponge and coral. Our sampling resulted in 36 unique species across 20 genera. We observed many isolates by time-lapse differential interference contrast (DIC) microscopy and analyzed modes of growth and division. Several black yeasts displayed highly unconventional cell division cycles compared to those of traditional model yeast systems. Black yeasts have been found in habitats inhospitable to other life and are known for halotolerance, virulence, and stress-resistance. We find that this group of yeasts also shows remarkable plasticity in terms of cell size control, modes of cell division, and cell polarity. Unexpected behaviors include division through a combination of fission and budding, production of multiple simultaneous buds, and cell division by sequential orthogonal septations. These marine-derived yeasts reveal alternative mechanisms for cell division cycles that seem likely to expand the repertoire of rules established from classic model system yeasts.

scholarly journals Cell size control driven by the circadian clock and environment in cyanobacteria

2017 ◽  
Author(s):  
Bruno M. C. Martins ◽  
Amy K. Tooke ◽  
Philipp Thomas ◽  
James C. W. Locke
Keyword(s):  
Cell Division ◽  
Circadian Clock ◽  
Cell Size ◽  
Size Control ◽  
Time Lapse ◽  
Complex Interactions ◽  
Light Levels ◽  
Subjective Night ◽  
In The Wild ◽  
Cell Size Control

AbstractHow cells maintain their size has been extensively studied under constant conditions. In the wild, however, cells rarely experience constant environments. Here, we examine how the 24-hour circadian clock and environmental cycles modulate cell size control and division timings in the cyanobacteriumSynechococcus elongatususing single-cell time-lapse microscopy. Under constant light, wild type cells follow an apparent sizer-like principle. Closer inspection reveals that the clock generates two subpopulations, with cells born in the subjective day following different division rules from cells born in subjective night. A stochastic model explains how this behaviour emerges from the interaction of cell size control with the clock. We demonstrate that the clock continuously modulates the probability of cell division throughout day and night, rather than solely applying an on-off gate to division as previously proposed. Iterating between modelling and experiments, we go on to show that the combined effects of the environment and the clock on cell division are explained by an effective coupling function. Under naturally graded light-dark cycles, this coupling shifts cell division away from dusk and dawn, when light levels are low and cell growth is reduced. Our analysis allows us to disentangle, and predict the effects of, the complex interactions between the environment, clock, and cell size control.

scholarly journals Cell size control driven by the circadian clock and environment in cyanobacteria

2018 ◽  
Vol 115 (48) ◽  
pp. E11415-E11424 ◽  
Author(s):  
Bruno M. C. Martins ◽  
Amy K. Tooke ◽  
Philipp Thomas ◽  
James C. W. Locke
Keyword(s):  
Cell Division ◽  
Circadian Clock ◽  
Cell Size ◽  
Time Window ◽  
Size Control ◽  
Time Lapse ◽  
Time Of Day ◽  
Division Rate ◽  
Cell Size Control ◽  
And Shifts

How cells maintain their size has been extensively studied under constant conditions. In the wild, however, cells rarely experience constant environments. Here, we examine how the 24-h circadian clock and environmental cycles modulate cell size control and division timings in the cyanobacteriumSynechococcus elongatususing single-cell time-lapse microscopy. Under constant light, wild-type cells follow an apparent sizer-like principle. Closer inspection reveals that the clock generates two subpopulations, with cells born in the subjective day following different division rules from cells born in subjective night. A stochastic model explains how this behavior emerges from the interaction of cell size control with the clock. We demonstrate that the clock continuously modulates the probability of cell division throughout day and night, rather than solely applying an on−off gate to division, as previously proposed. Iterating between modeling and experiments, we go on to identify an effective coupling of the division rate to time of day through the combined effects of the environment and the clock on cell division. Under naturally graded light−dark cycles, this coupling narrows the time window of cell divisions and shifts divisions away from when light levels are low and cell growth is reduced. Our analysis allows us to disentangle, and predict the effects of, the complex interactions between the environment, clock, and cell size control.

Markers of cell polarity during and after nitrogen starvation in Schizosaccharomyces pombe

1997 ◽  
Vol 75 (6) ◽  
pp. 697-708 ◽  
Author(s):  
Ivan Rupes ◽  
Jana Jochová ◽  
Paul G Young
Keyword(s):  
Cell Division ◽  
Schizosaccharomyces Pombe ◽  
Cell Polarity ◽  
Nitrogen Starvation ◽  
Size Control ◽  
Starvation Period ◽  
Wild Type ◽  
Small Deviations ◽  
Cell Wall Deposition

In Schizosaccharomyces pombe, nitrogen starvation induces transient acceleration of cell division and reduction in cell size with a final arrest in G1. The division size control appears to be impaired by mutations in cdr1/nim1 and cdr2, genes that encode protein kinases mediating nutritional control over the mitotic cycle. cdr- cells arrest after fewer rounds of division and are larger than the wild type. Recent work suggests that long-term nitrogen starvation causes S. pombe wild-type cells to become spherical, which suggests loss of cell polarity. cdr mutants retain the elongated shape, indicating a potential difference in cell polarity control relative to the wild type. We examined several markers related to maintenance of cell polarity in S. pombe following nitrogen starvation including cell division scar pattern and actin and microtubule cytoskeleton. Wild-type cells as well as cdr mutants maintained a normal cell division scar pattern throughout nitrogen starvation but cells dividing under these conditions developed a wall malformation in the center of the septum. In cells arrested by nitrogen starvation, actin patches, normally associated with sites of cell wall deposition, were larger and distributed randomly along the cell surface. Cytoplasmic arrays of microtubules, which are thought to be involved in control of the polarity signal, were not visibly affected. The effects were similar in wild-type cells and in cdr- mutants. Upon refeeding, the new growth always reoccurred at the tip zones and there were only small deviations of its direction from the original axis. The results indicate that cell polarity is preserved both in wild-type cells, which arrest in G1 and appear spherical, and in cdr1/nim1 and cdr2 mutants, which arrest in G2 and appear polarized throughout the starvation period. Key words: cell polarity, fission yeast, nitrogen starvation, actin, microtubules, cdr1/nim1, cdr2.

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