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Mitotic Exit and Separation of Mother and Daughter Cells

Mitotic Exit and Separation of Mother and Daughter Cells

Synthesis of b1–3 glucan by Fks1/glucan synthase is critical for this process (Cabib et al. 2001; Lesage et al. 2004, 2005; Lesage and Bussey 2006). The chitin synthase Chs3 also localizes to the site of secondary septum formation, provid- ing additional structural reinforcement with chitin (Ziman et al. 1998; Cabib et al. 2001; Schmidt et al. 2002; Cabib and Schmidt 2003; Ortiz and Novick 2006). Delivery of other wall components by secretion is probably important, as there is a strong concentration of exocytic machinery to the site (Dobbelaere and Barral 2004; Zhang et al. 2006). For example, the “exocyst” component Sec3 (reviewed in Heider and Munson 2012; Liu and Guo 2012) acts in septa- tion parallel to actomyosin ring contraction, suggesting that delivery of material through the secretory system promotes secondary septum formation (Dobbelaere and Barral 2004). Budding yeast septation is robust and can occur in the absence of either primary septum synthesis or actomyosin ring contraction. This occurs via synthesis of a “remedial septum,” which is essentially a secondary septum deposited at the bud neck in a way that is disorganized yet sufficient to separate mother and daughter cells (Cabib and Schmidt 2003; Tolliday et al. 2003). In fact, complete absence of chitin in both the primary and secondary septa can be com- pensated by deposition of other polymers in this remedial structure, albeit poorly (Schmidt 2004). Intriguingly, elimi- nation of the primary septum synthesis machinery selects for whole chromosome aneuploidies that enhance remedial sep- tum formation (Rancati et al. 2008).
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A Mutation in the ATP2 Gene Abrogates the Age Asymmetry Between Mother and Daughter Cells of the Yeast Saccharomyces cerevisiae

A Mutation in the ATP2 Gene Abrogates the Age Asymmetry Between Mother and Daughter Cells of the Yeast Saccharomyces cerevisiae

distinguish between mutants of age asymmetry and such A deletion of ATP2 was generated in strain YPK9. The mutants of synthesis, a modified life-span determination atp2⌬ strains failed to grow on nonfermentable carbon experiment was performed. Virgin yeast cells produced sources such as glycerol, as expected. These strains also at 30⬚ were moved to 36⬚ and allowed to divide seven failed to grow under anaerobic conditions. However, times on average. The first six buds produced by these on 2% glucose media, growth and cell morphology of mother cells were removed and discarded by microman- these strains appeared normal at 30⬚. At 37⬚, the atp2⌬ ipulation. The seventh buds and their mother cells were strains displayed the clonal-senescence phenotype simi- then moved back to 30⬚, and their remaining life spans lar to CS16 on serial streaking (Figure 1). However, the at 30⬚ were determined. In a mutant of synthesis, growth phenotype was more severe. The end-point colony sizes arrest results from disruption of specific synthetic activ- were usually smaller than that of CS16, and a dramatic ity. Upon temperature shift-down, the disrupted syn- reduction in the number of colonies occurred one or thetic activity recovers and both mother and daughter two sectors earlier. In contrast to the severe clonal-senes- cells resume normal growth. Since daughter cells are
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MITOCHONDRIAL GENETIC ANALYSIS BY ZYGOTE CELL LINEAGES IN SACCHAROMYCES CEREVISIAE

MITOCHONDRIAL GENETIC ANALYSIS BY ZYGOTE CELL LINEAGES IN SACCHAROMYCES CEREVISIAE

of a bacteriophage cross with the potential for repeated interaction among multi- ple genomes, the products in this case being transmitted to daughter cells. A powerful tool o[r]

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Following the fate of individual T cells throughout activation and clonal expansion  Signals from T cell receptor and CD28 differentially regulate the induction and duration of a proliferative response

Following the fate of individual T cells throughout activation and clonal expansion Signals from T cell receptor and CD28 differentially regulate the induction and duration of a proliferative response

proaches that measure the bulk response of a cell population, without distinguishing the responses of individual cells. As a consequence, it has been difficult to determine whether modu- lations in T cell responses with changing TCR or costimulatory signals were due to recruitment of more cells into the re- sponse, a more vigorous output by responding cells, or both. It has also not been clear if this balance would vary in a kinetic fashion. We have developed an experimental system in which the fate of individual T cells can be followed throughout acti- vation and clonal expansion. By monitoring the generation of daughter cells during a T cell response using the fluorescent dye CFSE (18), we are able to ascertain the proportion of the original T cells that have responded to stimulation by dividing, and to provide an accurate estimate of the absolute number of cell divisions which have occurred. Furthermore, because this method of monitoring cell division employs flow cytometry, we are able to examine multiple parameters of an immune re- sponse on a single cell basis, such as the expression of CD25 or CD69 as a function of mitotic number in a mixed population. This approach allows for an in-depth analysis of the dynamics of a T cell response.
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Stable Preanaphase Spindle Positioning Requires Bud6p and an Apparent Interaction between the Spindle Pole Bodies and the Neck

Stable Preanaphase Spindle Positioning Requires Bud6p and an Apparent Interaction between the Spindle Pole Bodies and the Neck

Faithful partitioning of genetic material during cell division requires accurate spatial and temporal positioning of nuclei within dividing cells. In Saccharomyces cerevisiae, nuclear positioning is regulated by an elegant interplay between components of the actin and microtubule cytoskeletons. Regulators of this process include Bud6p (also referred to as the actin-interacting protein Aip3p) and Kar9p, which function to promote contacts between cytoplasmic microtubule ends and actin-delimited cortical attachment points. Here, we present the previously undetected association of Bud6p with the cytoplasmic face of yeast spindle pole bodies, the functional equivalent of metazoan centrosomes. Cells lacking Bud6p show exaggerated movements of the nucleus between mother and daughter cells and display reduced amounts of time a given spindle pole body spends in close association with the neck region of budding cells. Furthermore, overexpression of BUD6 greatly enhances interactions between the spindle pole body and mother-bud neck in a spindle alignment-defective dynactin mutant. These results suggest that association of either spindle pole body with neck components, rather than simply entry of a spindle pole body into the daughter cell, provides a positive signal for the progression of mitosis. We propose that Bud6p, through its localization at both spindle pole bodies and at the mother-bud neck, supports this positive signal and provides a regulatory mechanism to prevent excessive oscillations of preanaphase nuclei, thus reducing the likelihood of mitotic delays and nuclear missegregation.
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Developmental stratification of the mammary epithelium occurs through symmetry breaking vertical divisions of apically positioned luminal cells

Developmental stratification of the mammary epithelium occurs through symmetry breaking vertical divisions of apically positioned luminal cells

Mammary ducts are elongated during development by stratified epithelial structures, known as terminal end buds (TEBs). TEBs exhibit reduced apicobasal polarity and extensive proliferation. A major unanswered question concerns the mechanism by which the simple ductal epithelium stratifies during TEB formation. We sought to elucidate this mechanism using real-time imaging of growth factor- induced stratification in 3D cultures of mouse primary epithelial organoids. We hypothesized that stratification could result from vertical divisions in either the apically positioned luminal epithelial cells or the basally positioned myoepithelial cells. Stratification initiated exclusively from vertical apical cell divisions, both in 3D culture and in vivo. During vertical apical divisions, only the mother cell retained tight junctions and segregated apical membranes. Vertical daughter cells initiated an unpolarized cell population located between the luminal and myoepithelial cells, similar to the unpolarized body cells in the TEB. As stratification and loss of apicobasal polarity are early hallmarks of cancer, we next determined the cellular mechanism of oncogenic stratification. Expression of activated ERBB2 induced neoplastic stratification through analogous vertical divisions of apically positioned luminal epithelial cells. However, ERBB2-induced stratification was accompanied by tissue overgrowth and acute loss of both tight junctions and apical polarity. Expression of phosphomimetic MEK (MEK1DD), a major ERBB2 effector, also induced stratification through vertical apical cell divisions. However, MEK1DD-expressing organoids exhibited normal levels of growth and retained apicobasal polarity. We conclude that both normal and neoplastic stratification are accomplished through receptor tyrosine kinase signaling dependent vertical cell divisions within the luminal epithelial cell layer.
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4AP Review Meiosis and Heredity.pdf

4AP Review Meiosis and Heredity.pdf

During another round of cell division, the sister chromatids finally separate; four haploid daughter cells result, containing single chromosomes Two haploid cells.. form; chromosomes are[r]

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Development of Melanoma and Cancer without Decreasing of Cambial Cells Number in Morphofunctional Zones

Development of Melanoma and Cancer without Decreasing of Cambial Cells Number in Morphofunctional Zones

So, in age groups of 20 - 40, 41 - 60 years old at normal quantity of cambial cells (12 cells) tyrosinase synthe- sis can increase under the influence of any factors. Therefore in these conditions Src utilization will be increased for tyrosinase phosphorylation that will reduce participation of Src SH2 domain in cytoskeleton formation. If the portion of this domain decreases to critical level, the differentiation will be absent and there will be a malignant tumor. The effect will be the same, as well as at decrease in cambial cells number. It happens more often at people with constitutional low level of Src kinase activity. At these people the strengthening of tyrosinase activ- ity will lead to decrease the participation of initially not high level of SH2 domain in the cell differentiation. Therefore people at whom prevails pheomelanin, get sick with a melanoma and a cancer of skin more often. If the factor activating tyrosinase is very strong (for example, powerful UF radiation), then at considerable de- crease of the SH2 domain, the RhoA expression will sharply increase in the cell cytoskeleton. It is shown above that increase in certain range of RhoA in relation to Src in a cell leads to strengthening of the proliferation, Thus, at powerful UF radiation when the portion of Src SH2 domain considerably decreases, and RhoA raises, daugh- ter cells, having very weak differentiation, will begin to proliferate actively at the earliest stages of the develop- ment (melanocyte), that will lead to melanoma development (Figure 7). If action of activating factors not strong and long, activity of the SH2 domain gradually decreases. Therefore, the malignancy and active proliferation will appear in more remote descendants of daughter cells, which have no the tyrosinase activity already, and there will be a cancer. Thus, daughter cells (melanocytes), turned out at once after cambial cells division and having tyrosinase activity, actively proliferate in melanoma. At a cancer more remote descendants of the daugh- ter cells (epithelial cells) which have lost tyrosinase activity, intensively divide. But in both cases a source of malignant regeneration are the daughter cells having tyrosinase activity which represent so-called tumor stem cells.
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cell reproduction review revised 2009.doc

cell reproduction review revised 2009.doc

1. Cell division in eukaryotes consists of two parts: M __ __ __ __ __ __ which divides the chromosomes and C __ __ __ __ __ __ __ __ __ __ which divides the cytoplasm. 2. Bacteria divide using B __ __ __ __ __ F __ __ __ __ __ __ instead of mitosis. 3. In M __ __ __ __ __ __ a cell divides once to produce two daughter cells that are

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Capsular Localization of the Cryptococcus neoformans Polysaccharide Component Galactoxylomannan

Capsular Localization of the Cryptococcus neoformans Polysaccharide Component Galactoxylomannan

In summary, we have made two new reagents for the study of C. neoformans capsular polysaccharides in the form of a hy- perimmune serum to GalXM and an scFv that binds to oxi- dized carbohydrates. Using these reagents, we established that GalXM was found in the C. neoformans capsule in discrete pockets amid the GXM layers and was abundant in the cap- sules of nascent buds. Furthermore, isolated vesicle fractions contained galactose, consistent with secretion of GalXM by trans-cell-wall vesicular transport, as has been proposed for GXM (31). Given the association of GalXM with vesicles and the partial colocalization with DiI, this punctate distribution could reflect vesicular transport. The strong staining of GalXM-PA immune sera for the capsules of budding daughter cells also reflects increased vesicular transport at sites of nas- cent capsule formation or a role in capsular remodeling. Our results are most easily interpreted as indicating that GalXM is primarily an exopolysaccharide, with a possible role in capsule formation during budding, rather than functioning as a struc- tural component of mature capsule. Given the strong immu- nomodulatory activity of GalXM, one is tempted to speculate that this material is exported for fungal cell defense and could serve an important role for cryptococcal survival in various ecologic niches, including mammalian hosts.
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_08_Lecture_Presentation_PC.ppt

_08_Lecture_Presentation_PC.ppt

Figure 8.3B Sister chromatids Chromosomes Centromere Chromosome duplication Sister chromatids Chromosome distribution to the daughter cells DNA molecules... Figure 8.3B_2.[r]

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Candida albicans VAC8 Is Required for Vacuolar Inheritance and Normal Hyphal Branching

Candida albicans VAC8 Is Required for Vacuolar Inheritance and Normal Hyphal Branching

Hyphal growth is prevalent during most Candida albicans infections. Current cell division models, which are based on cytological analyses of C. albicans, predict that hyphal branching is intimately linked with vacuolar inheritance in this fungus. Here we report the molecular validation of this model, showing that a specific mutation that disrupts vacuolar inheritance also affects hyphal division. The armadillo repeat-containing protein Vac8p plays an important role in vacuolar inheritance in Saccharomyces cerevisiae. The VAC8 gene was identified in the C. albicans genome sequence and was resequenced. Homozygous C. albicans vac8 ⌬ deletion mutants were generated, and their phenotypes were examined. Mutant vac8 ⌬ cells contained fragmented vacuoles, and minimal vacuolar material was inherited by daughter cells in hyphal or budding forms. Normal rates of growth and hyphal extension were observed for the mutant hyphae on solid serum-containing medium. However, branching frequencies were significantly increased in the mutant hyphae. These observations are consistent with a causal relationship between vacuolar inheritance and the cell division cycle in the subapical compartments of C. albicans hyphae. The data support the hypothesis that cytoplasmic volume, rather than cell size, is critical for progression through G 1 .
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Modeling epigenetic regulation of PRC1 protein accumulation in the cell cycle

Modeling epigenetic regulation of PRC1 protein accumulation in the cell cycle

In the current paper, we used a mathematical model to reproduce experimental trajectories of the PRC1 protein published in [9] and extend the results to model long-range dynamics of the cell population. The main question we ad- dress is whether the regulatory feedbacks deduced from single cell cycle data provide epigenetic regulation of cell characteristics in long run. PRC1 protein is regulated by the cell cycle. This protein is absolutely required in cytokinesis, without it cell cannot divide to form two daughter cells [26]. PRC1 is a good candidate because of its role in setting timing of division. Findings of the current paper include tight regulation of the cell cycle (particularly the timing of the cell cycle) even that PRC1 is only one of the players in cell dynamics. Understanding that association, even close, does not necessarily imply causation, we consider this an interesting and important result.
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The number of polyploid giant cancer cells and epithelial-mesenchymal transition-related proteins are associated with invasion and metastasis in human breast cancer

The number of polyploid giant cancer cells and epithelial-mesenchymal transition-related proteins are associated with invasion and metastasis in human breast cancer

oxic mimic and can induce the formation of PGCCs by selectively killing regular diploid cells; flow cytometry and fluorescence in situ hybridization (FISH) reveal the presence of multiple copies of DNA in single PGCC [7]. We have successfully isolated, purified, and cultured PGCCs from 22 cancer cell lines, including HEY, SKOV3, and MDA-MB-231 [8]. PGCCs express normal and cancer stem cell markers, and can be induced to differentiate into other tissues, such as adipose, cartilage, erythrocytes, fibro- blasts, and bone [3, 4, 9, 10]. In addition, they generate daughter cells (regular-sized diploid cancer cells) via asym- metric cell divisions, a process of reductive division known as depolyploidization [11, 12]. Asymmetric cell division, in- cluding splitting, budding, and burst-like, usually occurs in the division of low-level eukaryotes, plants, and viruses [3]. Compared to diploid cancer cells, PGCCs with budding daughter cells and PGCCs alone express lower levels of cytokeratin and higher levels of vimentin, indicating that PGCCs and their budding daughter cells have undergone epithelial-mesenchymal transition (EMT) [10].
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AP Bio_Cell Cycle.pptx

AP Bio_Cell Cycle.pptx

Life of a cell from the time it is first formed until its own division into two daughter cells.. The Cell Cycle.[r]

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How different is Venus from Mars? The genetics of germ line stem cells in
Drosophila females and males

How different is Venus from Mars? The genetics of germ line stem cells in Drosophila females and males

The last few years have seen a surge in stem cell research, and our incentive to understand stem cell biology is only increased by the exciting promise of stem cell-based therapies. The definition of a stem cell is still under debate, but a general view is that stem cells are cells that have an unlimited (or an especially high) capacity for self-renewal, and that can produce at least one type of differentiated progeny. Accordingly, the two main questions that concern stem cell biology are how stem cells preserve their unique, undifferentiated identity through many rounds of divisions, and how their daughter cells choose and activate a differentiation program. Stem cell maintenance and differentiation is dependent on the microenvironment provided by surrounding cells, the ‘niche’ (Spradling et al., 2001; Watt and Hogan, 2000). Stem cells and niche cells must thus be regarded as a functional unit, and a better understanding of stem cell biology will be achieved by studying stem cells in vivo, within their natural surroundings. The study of stem cells in many systems is hampered by several factors. In some cases, a set of markers to define stem cells and to distinguish them from their immediate daughter cells has not been found. In others, although the stem cells are defined, they constitute a very small percentage of the tissue, and are therefore hard to find and to study in their natural environment. Only lately have niches been identified for the important mammalian stem cells of the hematopoietic system and the epithelium (Calvi et al., 2003; Tumbar et al., 2004; Zhang et al., 2003). By contrast, the location of germ-line stem cells (GSCs) in both the male and female fruit fly, Drosophila melanogaster, is clearly defined and has long been studied. This, along with the power of genetic analysis, makes both spermatogenesis and oogenesis in fruit flies ideal systems in which to study stem cell maintenance and differentiation. The field of GSC biology in Drosophila has reached the stage where the analysis of the degree of similarity, and the nature
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A dynamic cell adhesion surface regulates tissue architecture in growth plate cartilage

A dynamic cell adhesion surface regulates tissue architecture in growth plate cartilage

Fig. 1. Experimental design for a novel application of time-lapse confocal microscopy. (A) In long bone growth plate, the transition between the first two maturation states (resting zone to proliferative zone) is accompanied by the establishment of clonal columns of flattened, disc-like chondrocytes. (B) This column formation occurs via planar cytokinesis followed by a ∼ 90° rearrangement of the daughter cells. (C) An endochondral growth plate amenable to confocal microscopy is the presphenoidal synchondrosis (PSS) on the ventral side of the mouse cranium (arrow). (D) The PSS contains a mirror image growth plate with a central resting zone flanked by two sets of maturation zones, creating bone growth in two opposing directions simultaneously. The zones, in order of increasing maturity, are the resting [R], proliferative [P], prehypertrophic [PH] and hypertrophic [H] zones. This is confirmed with histology and fluorescence in situ hybridization against collagen type 2, collagen 10, indian hedgehog (IHH) and prelp. (E) In order to create mosaic expression of myristoylated eGFP, the tdTomato reporter line was crossed with a tissue-specific, tamoxifen-inducible Cre recombinase line, Col2CreERT. (F) Injection of a single 4 mg dose at E13.5-14.5 resulted in 30-40% recombination, allowing individual dividing chondrocytes to be optically resolved.
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C.8 Intro Cell Division & Mitosis ppt

C.8 Intro Cell Division & Mitosis ppt

Figure 8.6b-0 Cytokinesis Cell wall of the parent cell Daughter nucleus Cell plate forming Cell wall New cell wall Vesicles containing cell wall material. Cell plate Daughter cells.[r]

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Maternal inheritance and stage-specific variation of the apicoplast in Toxoplasma gondii during development in the intermediate and definitive host

Maternal inheritance and stage-specific variation of the apicoplast in Toxoplasma gondii during development in the intermediate and definitive host

for the apicoplast during schizogony in Plasmodium falciparum within erythrocytes (36). In the present semiquantitative study, the size and level of signal appear greater than required to provide a single small apicoplast to each daughter. It is possible that the increase in size and level of ENR signal is related to an increased physiological function of the apicoplast during the initial growth phase. It was noted that the increase in size of the apicoplast coincided with an increase in the size of the mitochondrion, representing evidence of increased metabolic activity. However, the growth phase during microgametogony does not appear to be associated with the marked increase in ENR signal. Since the microgametes lack an apicoplast, there is no need for the apicoplast to replicate, and this may explain the reduced size and signal. This also means that apicoplasts can only be inherited via the female (macrogamete) lineage, consistent with observations for Plasmodium sp. (3). The find- ing of an enlarged, strongly positive ENR apicoplast adjacent to the nucleus during the development of the macrogamete is consistent with the ultrastructural observations of multimem- branous vacuoles. This is formal confirmation that these vacu- oles are apicoplasts that contain ENR in this life cycle stage. The present study shows for the first time that the developing macrogametocyte has an enlarged apicoplast with what ap- pears to be a highly elevated ENR signal. In this situation, the changes to the apicoplast are unrelated to nuclear division since none occurs within the macrogamete. However, mac-
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Mentoring My Daughter: Contradictions and Possibilities

Mentoring My Daughter: Contradictions and Possibilities

Mentoring M y Daughter Contradictions and BY SHARON ABBEY L kuteureconJ;onte&saszomptionsau sujetdu tutorat maternel et met f k c e n t sur kz suprkmacic de kz rksistance, f'indi viduulisation et la r[.]

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