On the differential divisions and preprophase microtubule bands involved in the development of stomata of Vigna sinensis L

1979 ◽  
Vol 37 (1) ◽  
pp. 11-37
Author(s):  
B. Galatis ◽  
K. Mitrakos
Keyword(s):  
Cell Polarity ◽  
Cell Plate ◽  
Equatorial Position ◽  
Anticlinal Wall ◽  
Vigna Sinensis ◽  
Daughter Cells ◽  
Preprophase Microtubule Band ◽  
Dicotyledonous Plants ◽  
Mother Cells ◽  
Dictyosome Vesicles

The manifestation of premitotic cell polarity and the resultant structural asymmetry of the differential divisions participating in the development of stomata of Vigna sinensis vary considerably. However, two morphologically distinct types of differential division were distinguished: (a) ‘asymmetrical differential divisions’, in which the premitotic polarization of the cell, the eccentric position of the nucleus during division and the differences in size and organization of the daughter cells are obvious; and (b) differential divisions in which the above features are inconspicuous or almost absent. The former occur in the ordinary protodermal cells, the latter in some meristemoids. The organization of a sharply demarcated preprophase microtubule band (PMB) precedes, all differential and non-differential divisions. In the first type of differential division the PMB is formed eccentrically, while in the second it may display either an approximately symmetrical or a clearly asymmetrical disposition, always indicating with surprising accuracy the sites where the succeeding cell plate will join the parent walls. The PMB foreshadowing the highly curved cell plates in meristemoids I of the mesoperigenous process, as well as in meristemoids I and II of the mesogenous one, are apposed only on one anticlinal wall and therefore do not encircle the nucleus or traverse the cell. In the symmetrical divisions of guard cell mother cells (GMC), as well as in those of protodermal cells, the PMB runs right round the internal plasmalemma surface in an equatorial position, coinciding with that of the future cell plate. In the former cells the wall abutting the cortical cytoplasm traversed by the band becomes locally thickened. The variability in the pattern of the microtubules of the band along the walls of the GMC is directly mirrored in the pattern of the thickening. It seems that in GMC the PMB mediates a directed exocytosis of dictyosome vesicles. In contrast to what is now generally accepted in dicotyledonous plants, each meristemoid I of both the mesogenous and mesoperigenous stomata in Vigna sinensis leaves does not inhibit but induces the formation of other meristemoids close to it.

Symmetric and Asymmetric Mitosis and Cytokinesis in the Root Tip of Hydrocharis Morsus-Ranae L

1972 ◽  
Vol 11 (3) ◽  
pp. 723-737
Author(s):  
ELIZABETH G. CUTTER ◽  
CHING-YUAN HUNG
Keyword(s):  
Daughter Cell ◽  
Metaphase Plate ◽  
Cell Plate ◽  
Equatorial Region ◽  
Root Tip ◽  
Daughter Cells ◽  
Asymmetric Divisions ◽  
Spindle Microtubules ◽  
Asymmetric Mitosis ◽  
Dictyosome Vesicles

In the roots of Hydrocharis morsus-ranae, certain cells of the protoderm divide asymmetrically to form a small, highly cytoplasmic trichoblast proximally, and a larger, more vacuolate epidermal cell distally. The former develops as a root hair without further division; the latter divides several times to form ordinary epidermal cells. During mitosis, presumed dictyosome vesicles and fragments or sections of reticulated or serrate sheets of ER, aligned with the spindle microtubules, were observed among the chromosomes as early as metaphase, suggesting that the portions of ER were involved in formation of the cell plate or in some other function in the equatorial region. A pre-prophase band of microtubules was not observed. Asymmetric divisions differ from symmetric ones in the skewed orientation of the metaphase plate, the formation of a curved, rather wavy cell wall and the slightly greater vacuolation of one daughter cell. Less difference in the ultrastructure of the daughter cells resulting from an asymmetric division was observed in this rather slowly growing material than in other examples previously described in the literature.

Positional inconsistency between preprophase microtubule band and final cell plate arrangement during triangular subsidiary cell and atypical hair cell formation in two Triticum species

1984 ◽  
Vol 62 (2) ◽  
pp. 343-359 ◽  
Author(s):  
B. Galatis ◽  
P. Apostolakos ◽  
C. Katsaros
Keyword(s):  
Hair Cell ◽  
Mitotic Spindle ◽  
Cell Plate ◽  
Subsidiary Cell ◽  
Transverse Wall ◽  
Cortical Zone ◽  
Preprophase Microtubule Band ◽  
Mutual Disposition ◽  
Cell Plate Arrangement ◽  
Mother Cells

On the leaf epidermis of two Triticum species examined, an intervening cell of a stomatal or a hair row often flanks on one side two guard cell mother cells (GMC's) and usually functions twice as a subsidiary cell mother cell (SMC). In many of these cells and rarely in SMC's corresponding to one GMC, a triangular subsidiary cell (SC) instead of a lens-shaped one is formed. Some of these SC's in median paradermal sections appear triangular in form, while in internal and (or) external ones they exhibit a lenslike shape. In all SMC's investigated in which a triangular SC was expected to be formed, the preprophase microtubule band (PMB) occupied the usual position adjacent to the inducing GMC, except for instances in which the transverse wall of the SMC intersected the lateral wall of the GMC or was opposite its transverse wall. Therefore, during triangular SC formation a limited portion of the junction region of the cell plate with the parent walls is predicted by the PMB. In such cases the premitotic polarizing process in the SMC's and consequently the mutual disposition between the PMB and the mitotic spindle is disturbed. The PMB's of the hair cell mother cells (HMC's) are not so densely grouped as those of the SMC's, sometimes occupying an extensive portion along the walls. They were localized at the expected positions at the polar end of the cells. Only in few instances were atypical PMB's organized. However, the cell plate separating the hair cells (HC's) sometimes diverges and fuses with the parent walls at unpredictable positions far from the PMB cortical zone, except for a small part of it adjacent to one longitudinal anticlinal wall of the HMC. In addition, the preprophase–prophase nucleus often occupied an eccentric position in relation to the PMB or more rarely was situated outside it. Sometimes it exhibited a particular orientation. Moreover, mitotic spindles inclined in relation to the PMB plane were frequently observed. The above phenomena seem to be the result of the interference of a transverse polarizing stimulus with an axial one or of the establishment of an aberrant polarity in the HMC's for unknown reasons. The observations suggest that the spatial inconsistency between PMB and final cell plate arrangement in the cells investigated is an exception to the rule, caused by the disturbance of the mutual disposition and orientation between PMB cortical zone and mitotic spindle; these phenomena follow the disorder of the polarizing process of the cells. The PMB cortical zone seems to be effective only when the cell plate edges reach a critical distance from it.

scholarly journals Daughter cells of Saccharomyces cerevisiae from old mothers display a reduced life span.

1994 ◽  
Vol 127 (6) ◽  
pp. 1985-1993 ◽  
Author(s):  
B K Kennedy ◽  
N R Austriaco ◽  
L Guarente
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Life Span ◽  
Daughter Cell ◽  
Young Mothers ◽  
Young Mother ◽  
Yeast Saccharomyces Cerevisiae ◽  
Daughter Cells ◽  
Per Se ◽  
Mother Cells ◽  
Maximum Occurrence

The yeast Saccharomyces cerevisiae typically divides asymmetrically to give a large mother cell and a smaller daughter cell. As mother cells become old, they enlarge and produce daughter cells that are larger than daughters derived from young mother cells. We found that occasional daughter cells were indistinguishable in size from their mothers, giving rise to a symmetric division. The frequency of symmetric divisions became greater as mother cells aged and reached a maximum occurrence of 30% in mothers undergoing their last cell division. Symmetric divisions occurred similarly in rad9 and ste12 mutants. Strikingly, daughters from old mothers, whether they arose from symmetric divisions or not, displayed reduced life spans relative to daughters from young mothers. Because daughters from old mothers were larger than daughters from young mothers, we investigated whether an increased size per se shortened life span and found that it did not. These findings are consistent with a model for aging that invokes a senescence substance which accumulates in old mother cells and is inherited by their daughters.

scholarly journals FACT and Ash1 promote long-range and bidirectional nucleosome eviction at the HO promoter

2020 ◽  
Vol 48 (19) ◽  
pp. 10877-10889 ◽  
Author(s):  
Yaxin Yu ◽  
Robert M Yarrington ◽  
David J Stillman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Regulatory System ◽  
High Concentration ◽  
Long Distance ◽  
Mothers And Daughters ◽  
Daughter Cells ◽  
Dna Binding Factors ◽  
Mother Cells ◽  
Promoter Recruitment ◽  
Ho Gene

Abstract The Saccharomyces cerevisiae HO gene is a model regulatory system with complex transcriptional regulation. Budding yeast divide asymmetrically and HO is expressed only in mother cells where a nucleosome eviction cascade along the promoter during the cell cycle enables activation. HO expression in daughter cells is inhibited by high concentration of Ash1 in daughters. To understand how Ash1 represses transcription, we used a myo4 mutation which boosts Ash1 accumulation in both mothers and daughters and show that Ash1 inhibits promoter recruitment of SWI/SNF and Gcn5. We show Ash1 is also required for the efficient nucleosome repopulation that occurs after eviction, and the strongest effects of Ash1 are seen when Ash1 has been degraded and at promoter locations distant from where Ash1 bound. Additionally, we defined a specific nucleosome/nucleosome-depleted region structure that restricts HO activation to one of two paralogous DNA-binding factors. We also show that nucleosome eviction occurs bidirectionally over a large distance. Significantly, eviction of the more distant nucleosomes is dependent upon the FACT histone chaperone, and FACT is recruited to these regions when eviction is beginning. These last observations, along with ChIP experiments involving the SBF factor, suggest a long-distance loop transiently forms at the HO promoter.

scholarly journals The equatorial position of the metaphase plate ensures symmetric cell divisions

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Chia Huei Tan ◽  
Ivana Gasic ◽  
Sabina P Huber-Reggi ◽  
Damian Dudka ◽  
Marin Barisic ◽  
...  
Keyword(s):  
Spindle Assembly Checkpoint ◽  
Metaphase Plate ◽  
Spindle Assembly ◽  
Equatorial Position ◽  
Asymmetric Cell Divisions ◽  
Daughter Cells ◽  
Cell Divisions ◽  
Microtubule Stability ◽  
Chromosome Alignment ◽  
Metazoan Cell

Chromosome alignment in the middle of the bipolar spindle is a hallmark of metazoan cell divisions. When we offset the metaphase plate position by creating an asymmetric centriole distribution on each pole, we find that metaphase plates relocate to the middle of the spindle before anaphase. The spindle assembly checkpoint enables this centering mechanism by providing cells enough time to correct metaphase plate position. The checkpoint responds to unstable kinetochore–microtubule attachments resulting from an imbalance in microtubule stability between the two half-spindles in cells with an asymmetric centriole distribution. Inactivation of the checkpoint prior to metaphase plate centering leads to asymmetric cell divisions and daughter cells of unequal size; in contrast, if the checkpoint is inactivated after the metaphase plate has centered its position, symmetric cell divisions ensue. This indicates that the equatorial position of the metaphase plate is essential for symmetric cell divisions.

scholarly journals Cell cycle phases in the unequal mother/daughter cell cycles of Saccharomyces cerevisiae.

1984 ◽  
Vol 4 (11) ◽  
pp. 2529-2531 ◽  
Author(s):  
B J Brewer ◽  
E Chlebowicz-Sledziewska ◽  
W L Fangman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cycle Phase ◽  
Cell Cycle Time ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cell Cycles ◽  
Daughter Cells ◽  
Mother And Daughter ◽  
Cell Cycle Phases ◽  
Mother Cells

During cell division in the yeast Saccharomyces cerevisiae mother cells produce buds (daughter cells) which are smaller and have longer cell cycles. We performed experiments to compare the lengths of cell cycle phases in mothers and daughters. As anticipated from earlier indirect observations, the longer cell cycle time of daughter cells is accounted for by a longer G1 interval. The S-phase and the G2-phase are of the same duration in mother and daughter cells. An analysis of five isogenic strains shows that cell cycle phase lengths are independent of cell ploidy and mating type.

scholarly journals Key events during the transition from rapid growth to quiescence in budding yeast require posttranscriptional regulators

2013 ◽  
Vol 24 (23) ◽  
pp. 3697-3709 ◽  
Author(s):  
Lihong Li ◽  
Shawna Miles ◽  
Zephan Melville ◽  
Amalthiya Prasad ◽  
Graham Bradley ◽  
...  
Keyword(s):  
Cell Walls ◽  
Posttranscriptional Regulation ◽  
Cell Formation ◽  
Cell Types ◽  
G1 Arrest ◽  
Quiescent State ◽  
Diauxic Shift ◽  
Cell Wall Assembly ◽  
Daughter Cells ◽  
Mother Cells

Yeast that naturally exhaust the glucose from their environment differentiate into three distinct cell types distinguishable by flow cytometry. Among these is a quiescent (Q) population, which is so named because of its uniform but readily reversed G1 arrest, its fortified cell walls, heat tolerance, and longevity. Daughter cells predominate in Q-cell populations and are the longest lived. The events that differentiate Q cells from nonquiescent (nonQ) cells are initiated within hours of the diauxic shift, when cells have scavenged all the glucose from the media. These include highly asymmetric cell divisions, which give rise to very small daughter cells. These daughters modify their cell walls by Sed1- and Ecm33-dependent and dithiothreitol-sensitive mechanisms that enhance Q-cell thermotolerance. Ssd1 speeds Q-cell wall assembly and enables mother cells to enter this state. Ssd1 and the related mRNA-binding protein Mpt5 play critical overlapping roles in Q-cell formation and longevity. These proteins deliver mRNAs to P-bodies, and at least one P-body component, Lsm1, also plays a unique role in Q-cell longevity. Cells lacking Lsm1 and Ssd1 or Mpt5 lose viability under these conditions and fail to enter the quiescent state. We conclude that posttranscriptional regulation of mRNAs plays a crucial role in the transition in and out of quiescence.

scholarly journals Epigenetic Regulation of Plant Gametophyte Development

2019 ◽  
Vol 20 (12) ◽  
pp. 3051 ◽  
Author(s):  
Vasily V. Ashapkin ◽  
Lyudmila I. Kutueva ◽  
Nadezhda I. Aleksandrushkina ◽  
Boris F. Vanyushin
Keyword(s):  
Mother Cell ◽  
Female Gametophyte ◽  
Male Gametophyte ◽  
Endosperm Development ◽  
Epigenetic Changes ◽  
Gametophyte Development ◽  
Daughter Cells ◽  
Second Stage ◽  
Somatic Tissues ◽  
Mother Cells

Unlike in animals, the reproductive lineage cells in plants differentiate from within somatic tissues late in development to produce a specific haploid generation of the life cycle—male and female gametophytes. In flowering plants, the male gametophyte develops within the anthers and the female gametophyte—within the ovule. Both gametophytes consist of only a few cells. There are two major stages of gametophyte development—meiotic and post-meiotic. In the first stage, sporocyte mother cells differentiate within the anther (pollen mother cell) and the ovule (megaspore mother cell). These sporocyte mother cells undergo two meiotic divisions to produce four haploid daughter cells—male spores (microspores) and female spores (megaspores). In the second stage, the haploid spore cells undergo few asymmetric haploid mitotic divisions to produce the 3-cell male or 7-cell female gametophyte. Both stages of gametophyte development involve extensive epigenetic reprogramming, including siRNA dependent changes in DNA methylation and chromatin restructuring. This intricate mosaic of epigenetic changes determines, to a great extent, embryo and endosperm development in the future sporophyte generation.

scholarly journals Myosin-driven peroxisome partitioning in S. cerevisiae

2009 ◽  
Vol 186 (4) ◽  
pp. 541-554 ◽  
Author(s):  
Andrei Fagarasanu ◽  
Fred D. Mast ◽  
Barbara Knoblach ◽  
Yui Jin ◽  
Matthew J. Brunner ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Molecular Motors ◽  
Cell Cycle Progression ◽  
Cycle Progression ◽  
Class V ◽  
Daughter Cells ◽  
Mother And Daughter ◽  
Specific Receptors ◽  
Cycle Dependent ◽  
Mother Cells

In Saccharomyces cerevisiae, the class V myosin motor Myo2p propels the movement of most organelles. We recently identified Inp2p as the peroxisome-specific receptor for Myo2p. In this study, we delineate the region of Myo2p devoted to binding peroxisomes. Using mutants of Myo2p specifically impaired in peroxisome binding, we dissect cell cycle–dependent and peroxisome partitioning–dependent mechanisms of Inp2p regulation. We find that although total Inp2p levels oscillate with the cell cycle, Inp2p levels on individual peroxisomes are controlled by peroxisome inheritance, as Inp2p aberrantly accumulates and decorates all peroxisomes in mother cells when peroxisome partitioning is abolished. We also find that Inp2p is a phosphoprotein whose level of phosphorylation is coupled to the cell cycle irrespective of peroxisome positioning in the cell. Our findings demonstrate that both organelle positioning and cell cycle progression control the levels of organelle-specific receptors for molecular motors to ultimately achieve an equidistribution of compartments between mother and daughter cells.

scholarly journals Characterization of the Saccharomyces Golgi complex through the cell cycle by immunoelectron microscopy.

1992 ◽  
Vol 3 (7) ◽  
pp. 789-803 ◽  
Author(s):  
D Preuss ◽  
J Mulholland ◽  
A Franzusoff ◽  
N Segev ◽  
D Botstein
Keyword(s):  
Cell Cycle ◽  
Immunoelectron Microscopy ◽  
Early Stage ◽  
Secretory Vesicles ◽  
Wild Type ◽  
Daughter Cells ◽  
Bud Emergence ◽  
Membrane Compartments ◽  
Mother Cells

The membrane compartments responsible for Golgi functions in wild-type Saccharomyces cerevisiae were identified and characterized by immunoelectron microscopy. Using improved fixation methods, Golgi compartments were identified by labeling with antibodies specific for alpha 1-6 mannose linkages, the Sec7 protein, or the Ypt1 protein. The compartments labeled by each of these antibodies appear as disk-like structures that are apparently surrounded by small vesicles. Yeast Golgi typically are seen as single, isolated cisternae, generally not arranged into parallel stacks. The location of the Golgi structures was monitored by immunoelectron microscopy through the yeast cell cycle. Several Golgi compartments, apparently randomly distributed, were always observed in mother cells. During the initiation of new daughter cells, additional Golgi structures cluster just below the site of bud emergence. These Golgi enter daughter cells at an early stage, raising the possibility that much of the bud's growth might be due to secretory vesicles formed as well as consumed entirely within the daughter. During cytokinesis, the Golgi compartments are concentrated near the site of cell wall synthesis. Clustering of Golgi both at the site of bud formation and at the cell septum suggests that these organelles might be directed toward sites of rapid cell surface growth.

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