scholarly journals Spindle-independent condensation-mediated segregation of yeast ribosomal DNA in late anaphase

2005 ◽  
Vol 168 (2) ◽  
pp. 209-219 ◽  
Author(s):  
Félix Machín ◽  
Jordi Torres-Rosell ◽  
Adam Jarmuz ◽  
Luis Aragón
Keyword(s):  
Cell Division ◽  
Ribosomal Dna ◽  
Budding Yeast ◽  
Mitotic Cell ◽  
Yeast Genome ◽  
Daughter Cells ◽  
Late Anaphase ◽  
Mother And Daughter ◽  
The Right ◽  
Chromosome Resolution

Mitotic cell division involves the equal segregation of all chromosomes during anaphase. The presence of ribosomal DNA (rDNA) repeats on the right arm of chromosome XII makes it the longest in the budding yeast genome. Previously, we identified a stage during yeast anaphase when rDNA is stretched across the mother and daughter cells. Here, we show that resolution of sister rDNAs is achieved by unzipping of the locus from its centromere-proximal to centromere-distal regions. We then demonstrate that during this stretched stage sister rDNA arrays are neither compacted nor segregated despite being largely resolved from each other. Surprisingly, we find that rDNA segregation after this period no longer requires spindles but instead involves Cdc14-dependent rDNA axial compaction. These results demonstrate that chromosome resolution is not simply a consequence of compacting chromosome arms and that overall rDNA compaction is necessary to mediate the segregation of the long arm of chromosome XII.

scholarly journals Combined effect of cell geometry and polarity domains determines the orientation of unequal division

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Benoit G Godard ◽  
Remi Dumollard ◽  
Carl-Philipp Heisenberg ◽  
Alex McDougall
Keyword(s):  
Cell Division ◽  
Mitotic Spindle ◽  
Cell Shape ◽  
Daughter Cell ◽  
Cleavage Plane ◽  
Mitotic Cell ◽  
Cell Geometry ◽  
Daughter Cells ◽  
Ascidian Embryos ◽  
Spindle Position

Cell division orientation is thought to result from a competition between cell geometry and polarity domains controlling the position of the mitotic spindle during mitosis. Depending on the level of cell shape anisotropy or the strength of the polarity domain, one dominates the other and determines the orientation of the spindle. Whether and how such competition is also at work to determine unequal cell division (UCD), producing daughter cells of different size, remains unclear. Here, we show that cell geometry and polarity domains cooperate, rather than compete, in positioning the cleavage plane during UCDs in early ascidian embryos. We found that the UCDs and their orientation at the ascidian third cleavage rely on the spindle tilting in an anisotropic cell shape, and cortical polarity domains exerting different effects on spindle astral microtubules. By systematically varying mitotic cell shape, we could modulate the effect of attractive and repulsive polarity domains and consequently generate predicted daughter cell size asymmetries and position. We therefore propose that the spindle position during UCD is set by the combined activities of cell geometry and polarity domains, where cell geometry modulates the effect of cortical polarity domain(s).

scholarly journals Analysis of Cell Cycle Progression in the Budding Yeast S. cerevisiae

2021 ◽  
pp. 265-276
Author(s):  
Deniz Pirincci Ercan ◽  
Frank Uhlmann
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Cell Cycle Progression ◽  
Budding Yeast ◽  
Expression Profiles ◽  
Model Organisms ◽  
Cyclin Dependent Kinase ◽  
Cycle Progression ◽  
Daughter Cells ◽  
Substrate Phosphorylation

AbstractThe cell cycle is an ordered series of events by which cells grow and divide to give rise to two daughter cells. In eukaryotes, cyclin–cyclin-dependent kinase (cyclin–Cdk) complexes act as master regulators of the cell division cycle by phosphorylating numerous substrates. Their activity and expression profiles are regulated in time. The budding yeast S. cerevisiae was one of the pioneering model organisms to study the cell cycle. Its genetic amenability continues to make it a favorite model to decipher the principles of how changes in cyclin-Cdk activity translate into the intricate sequence of substrate phosphorylation events that govern the cell cycle. In this chapter, we introduce robust and straightforward methods to analyze cell cycle progression in S. cerevisiae. These techniques can be utilized to describe cell cycle events and to address the effects of perturbations on accurate and timely cell cycle progression.

scholarly journals Mechanisms for Curing Yeast Prions

2020 ◽  
Vol 21 (18) ◽  
pp. 6536
Author(s):  
Lois E. Greene ◽  
Farrin Saba ◽  
Rebecca E. Silberman ◽  
Xiaohong Zhao
Keyword(s):  
Quality Control ◽  
Cell Division ◽  
Protein Quality ◽  
Prion Proteins ◽  
Amyloid Fibers ◽  
Yeast Prions ◽  
Daughter Cells ◽  
Mother And Daughter ◽  
Infectious Proteins ◽  
Β Sheet

Prions are infectious proteins that self-propagate by changing from their normal folded conformation to a misfolded conformation. The misfolded conformation, which is typically rich in β-sheet, serves as a template to convert the prion protein into its misfolded conformation. In yeast, the misfolded prion proteins are assembled into amyloid fibers or seeds, which are constantly severed and transmitted to daughter cells. To cure prions in yeast, it is necessary to eliminate all the prion seeds. Multiple mechanisms of curing have been found including inhibiting severing of the prion seeds, gradual dissolution of the prion seeds, asymmetric segregation of the prion seeds between mother and daughter cells during cell division, and degradation of the prion seeds. These mechanisms, achieved by using different protein quality control machinery, are not mutually exclusive; depending on conditions, multiple mechanisms may work simultaneously to achieve curing. This review discusses the various methods that have been used to differentiate between these mechanisms of curing.

scholarly journals A novel factor essential for unconventional secretion of chitinase Cts1

2020 ◽  
Author(s):  
Michèle Reindl ◽  
Janpeter Stock ◽  
Kai P. Hussnaetter ◽  
Aycin Genc ◽  
Andreas Brachmann ◽  
...  
Keyword(s):  
Cell Division ◽  
Underlying Mechanism ◽  
Yeast Cells ◽  
Subcellular Targeting ◽  
Uv Mutagenesis ◽  
Daughter Cells ◽  
Secretion Pathway ◽  
Unconventional Secretion ◽  
Mother And Daughter ◽  
Two Hybrid

AbstractSubcellular targeting of proteins is essential to orchestrate cytokinesis in eukaryotic cells. During cell division of Ustilago maydis, for example, chitinases must be specifically targeted to the fragmentation zone at the site of cell division to degrade remnant chitin and thus separate mother and daughter cells. Chitinase Cts1 is exported to this location via an unconventional secretion pathway putatively operating in a lock-type manner. The underlying mechanism is largely unexplored. Here, we applied a forward genetic screen based on UV mutagenesis to identify components essential for Cts1 export. The screen revealed a novel factor termed Jps1 lacking known protein domains. Deletion of the corresponding gene confirmed its essential role for Cts1 secretion. Localization studies demonstrated that Jps1 colocalizes with Cts1 in the fragmentation zone of dividing yeast cells. While loss of Jps1 leads to exclusion of Cts1 from the fragmentation zone and strongly reduced unconventional secretion, deletion of the chitinase does not disturb Jps1 localization. Yeast-two hybrid experiments suggest that the two proteins interact. In essence, we identified a novel component of unconventional secretion that functions in the fragmentation zone to enable export of Cts1. We hypothesize that Jps1 acts as an anchoring factor, supporting the proposed novel lock-type mechanism of unconventional secretion.

scholarly journals Systematic analysis of asymmetric partitioning of yeast proteome between mother and daughter cells reveals “aging factors” and mechanism of lifespan asymmetry

2015 ◽  
Vol 112 (38) ◽  
pp. 11977-11982 ◽  
Author(s):  
Jing Yang ◽  
Mark A. McCormick ◽  
Jiashun Zheng ◽  
Zhengwei Xie ◽  
Mitsuhiro Tsuchiya ◽  
...  
Keyword(s):  
Cell Division ◽  
Asymmetric Cell Division ◽  
Asymmetric Distribution ◽  
Systematic Analysis ◽  
Daughter Cells ◽  
Yeast Proteome ◽  
Mother And Daughter ◽  
Asymmetric Partitioning ◽  
Mother Cells ◽  
Aging Factors

Budding yeast divides asymmetrically, giving rise to a mother cell that progressively ages and a daughter cell with full lifespan. It is generally assumed that mother cells retain damaged, lifespan limiting materials (“aging factors”) through asymmetric division. However, the identity of these aging factors and the mechanisms through which they limit lifespan remain poorly understood. Using a flow cytometry-based, high-throughput approach, we quantified the asymmetric partitioning of the yeast proteome between mother and daughter cells during cell division, discovering 74 mother-enriched and 60 daughter-enriched proteins. While daughter-enriched proteins are biased toward those needed for bud construction and genome maintenance, mother-enriched proteins are biased towards those localized in the plasma membrane and vacuole. Deletion of 23 of the 74 mother-enriched proteins leads to lifespan extension, a fraction that is about six times that of the genes picked randomly from the genome. Among these lifespan-extending genes, three are involved in endosomal sorting/endosome to vacuole transport, and three are nitrogen source transporters. Tracking the dynamic expression of specific mother-enriched proteins revealed that their concentration steadily increases in the mother cells as they age, but is kept relatively low in the daughter cells via asymmetric distribution. Our results suggest that some mother-enriched proteins may increase to a concentration that becomes deleterious and lifespan-limiting in aged cells, possibly by upsetting homeostasis or leading to aberrant signaling. Our study provides a comprehensive resource for analyzing asymmetric cell division and aging in yeast, which should also be valuable for understanding similar phenomena in other organisms.

scholarly journals Existence, Transition, and Propagation of Intermediate Silencing States in Ribosomal DNA

2019 ◽  
Vol 39 (23) ◽  
Author(s):  
Fan Zou ◽  
Manyu Du ◽  
Hengye Chen ◽  
Lu Bai
Keyword(s):  
Cell Cycle ◽  
Ribosomal Dna ◽  
Time Lapse ◽  
Dynamic Activity ◽  
Gene Expression Noise ◽  
Daughter Cells ◽  
Mother And Daughter ◽  
Cell Cycle Dependence ◽  
Highly Correlated ◽  
Cycle Dependence

ABSTRACT The MET3 promoter (MET3pr) inserted into the silenced chromosome in budding yeast can overcome Sir2-dependent silencing upon induction and activate transcription in every single cell among a population. Despite the fact that MET3pr is turned on in all the cells, its activity still shows very high cell-to-cell variability. To understand the nature of such “gene expression noise,” we followed the dynamics of the MET3pr-GFP expression inserted into ribosomal DNA (rDNA) using time-lapse microscopy. We found that the noisy “on” state is comprised of multiple substable states with discrete expression levels. These intermediate states stochastically transition between each other, with “up” transitions among different activated states occurring exclusively near the mitotic exit and “down” transitions occurring throughout the rest of the cell cycle. Such cell cycle dependence likely reflects the dynamic activity of the rDNA-specific RENT complex, as MET3pr-GFP expression in a telomeric locus does not have the same cell cycle dependence. The MET3pr-GFP expression in rDNA is highly correlated in mother and daughter cells after cell division, indicating that the silenced state in the mother cell is inherited in daughter cells. These states are disrupted by a brief repression and reset upon a second activation. Potential mechanisms behind these observations are further discussed.

Morphogenetic observations on the marine ciliate Euplotes vannus during cell division (Protozoa: Ciliophora)

2009 ◽  
Vol 90 (4) ◽  
pp. 683-689 ◽  
Author(s):  
Jiamei Jiang ◽  
Chen Shao ◽  
Henglong Xu ◽  
Khaled A.S. Al-Rasheid
Keyword(s):  
Cell Division ◽  
De Novo ◽  
Marine Ciliate ◽  
Daughter Cells ◽  
Euplotes Vannus ◽  
Protozoa Ciliophora ◽  
The Right ◽  
Primary Pattern

Morphogenetic events during the division of the marine ciliate, Euplotes vannus (Müller, 1786) Diesing, 1850 were investigated using protargol impregnation: (1) the opisthe's oral primordium develops de novo in a subsurface pouch above the marginal cirri; (2) the cirral anlagen for the frontal, ventral and transverse cirri in both dividers develop separately on the surface epi-apokinetally, cirrus I/1 and marginal anlagen for daughter cells are formed de novo separately; (3) the dorsal kinety anlagen occur in a non-typical primary pattern within the parental structures at mid-body, of which the 3 right-most ones produce the 3 caudal cirri for the proter; and (4) the opisthe acquires 2 caudal cirri from the end of the right-most 2 kineties. Based on the data available, the reasons for the variation in the number of caudal cirri in E. vannus are discussed.

scholarly journals Proteomics analysis for asymmetric inheritance of preexisting proteins between mother and daughter cells in budding yeast

2017 ◽  
Vol 22 (6) ◽  
pp. 591-601 ◽  
Author(s):  
Mitsuhiro Okada ◽  
Shunta Kusunoki ◽  
Yuko Ishibashi ◽  
Keiji Kito
Keyword(s):  
Budding Yeast ◽  
Proteomics Analysis ◽  
Daughter Cells ◽  
Mother And Daughter

scholarly journals Reproductive Isolation from Incompatible Hybrid Mitotic Networks (HyMEN)

2021 ◽  
Author(s):  
Pierre Hutter
Keyword(s):  
Mitotic Exit ◽  
Hybrid Incompatibility ◽  
Daughter Cells ◽  
Late Anaphase ◽  
Temporal Cues ◽  
Hybrid Genome ◽  
Mitotic Exit Network ◽  
Mother And Daughter ◽  
Spindle Disassembly ◽  
Entire Cell

At the end of mitosis the Mitotic Exit Network (MEN) pathway triggers complex tasks which mainly include the spindle disassembly and the nuclear envelopes assembly. In the course of telophase, which often lasts less than an hour and corresponds to only about 2% of the entire cell cycle’s duration, spatial and temporal cues are integrated to ensure that cytokinesis occurs after the genome has partitioned between mother and daughter cells. From the end of anaphase through telophase, sequential components of a Ras-like GTPase signaling pathway are controlled by a set of different spatial and temporal signals. Successful propagation of these signals through multi-step transduction requires a remarkable sequential coordination. By considering that cells lacking proper MEN function fail to exit from mitosis, I argue that in a hybrid genome impaired coordination between two diverged MENs is prone to result in critical mitotic defects, from late anaphase through telophase. The so-called HyMEN model of hybrid incompatibility depicted here can be regarded as an extension of the Bateson-Dobzhansky-Muller model of speciation, centered on the MEN.

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