scholarly journals Choice between 1- and 2-furrow cytokinesis in Caenorhabditis elegans embryos with tripolar spindles

2018 ◽  
Author(s):  
Tomo Kondo ◽  
Akatsuki Kimura
Keyword(s):  
Caenorhabditis Elegans ◽  
Cell Shape ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Embryonic Cells ◽  
Normal Cells ◽  
Multipolar Mitosis ◽  
Multipolar Spindles ◽  
Pulling Forces ◽  
Mutant Cells

AbstractExcess numbers of centrosomes often lead to multipolar spindles, and thus probably to multipolar mitosis and aneuploidy. In Caenorhabditis elegans, approximately 70% of the paternal emb-27APC6 mutant embryonic cells contained more than 2 centrosomes and formed multipolar spindles. However, only 30% of the cells with tripolar spindles formed 2 cytokinetic furrows. The rest formed 1 furrow, like normal cells. To investigate the mechanism how the cells avoided to form 2 cytokinetic furrows even with a tripolar spindle, we conducted live-cell imaging in emb-27APC6 mutant cells. We found that the chromatids were aligned only on 2 of the 3 sides of the tripolar spindle, and the angle of the tripolar spindle relative to the long axis of the cell correlated with the number of cytokinetic furrow. Our numerical modeling showed that the combination of cell shape, cortical pulling forces, and heterogeneity of centrosome size determines whether cells with tripolar spindle form 1 or 2 cytokinetic furrows.

scholarly journals Choice between 1- and 2-furrow cytokinesis in Caenorhabditis elegans embryos with tripolar spindles

2019 ◽  
Vol 30 (16) ◽  
pp. 2065-2075 ◽  
Author(s):  
Tomo Kondo ◽  
Akatsuki Kimura
Keyword(s):  
Caenorhabditis Elegans ◽  
Cell Shape ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Embryonic Cells ◽  
Normal Cells ◽  
Multipolar Mitosis ◽  
Multipolar Spindles ◽  
Pulling Forces ◽  
Mutant Cells

Excessive centrosomes often lead to multipolar spindles, and thus probably to multipolar mitosis and aneuploidy. In Caenorhabditis elegans, ∼70% of the paternal emb-27APC6 mutant embryonic cells contained more than two centrosomes and formed multipolar spindles. However, only ~30% of the cells with tripolar spindles formed two cytokinetic furrows. The rest formed one furrow, similar to normal cells. To investigate the mechanism via which cells avoid forming two cytokinetic furrows even with a tripolar spindle, we conducted live-cell imaging in emb-27APC6 mutant cells. We observed that the chromatids were aligned on only two of the three sides of the tripolar spindle, and the angle of the tripolar spindle relative to the long axis of the cell correlated with the number of cytokinetic furrows. Our numerical modeling showed that the combination of cell shape, cortical pulling forces, and heterogeneity of centrosome size determines whether cells with a tripolar spindle form one or two cytokinetic furrows.

scholarly journals Live-cell Imaging and Quantitative Analysis of Meiotic Divisions in Caenorhabditis elegans Males

BIO-PROTOCOL ◽  
2020 ◽  
Vol 10 (20) ◽  
Author(s):  
Gunar Fabig ◽  
Falko Löffler ◽  
Christian Götze ◽  
Thomas Müller-Reichert
Keyword(s):  
Quantitative Analysis ◽  
Caenorhabditis Elegans ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Live Cell

scholarly journals Carcinogen treatment leads to mitotic defects and arrest in cancer and noncancer cells

2018 ◽  
Author(s):  
Rebecca G Hartling ◽  
Christian J Pacheco ◽  
Emily A Bystrak ◽  
Nicholas J Quintyne
Keyword(s):  
Estrogen Receptor ◽  
Mitotic Index ◽  
Cell Lines ◽  
Mitotic Spindle ◽  
Chromosomal Instability ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Chromosomal Rearrangements ◽  
Anaphase Bridges ◽  
Multipolar Spindles

Genomic instability can manifest due to both chromosomal rearrangements and gain and loss of entire chromosomes. One mechanism by which a carcinogen acts is by increasing the rate of mitotic spindle defects during proliferation. These defects can lead to chromosomal instability that manifest as lagging chromosomes, anaphase bridges, or multipolar spindles. While several mechanisms exist to rectify these errors prior to completion of mitosis, some cells will escape repair, while others will prematurely exit mitosis. Here we examine the effects of two carcinogenic molecules: Fulvestrant, a chemotherapeutic that functions as a selective estrogen receptor degrader, and vinyl chloride, a hydrocarbon used to produce PVC. We exposed two cancer lines, A549 and UPCI:SCC103, and one noncancer line, GM03349, to increasing concentrations of the carcinogen for increasing durations, up to 48 hours exposure. We found that exposure to the carcinogen lowered the mitotic index in the cancer cell lines, while raising it in the noncancer line. Concurrently, we observed massive increases in the frequency of mitotic defects, with the most significant increases seen in prevalence of lagging chromosomes in prometaphase and metaphase and anaphase bridges. Live cell imaging showed that the occurrence of either of these defects had the strongest correlation with the likelihood that the cell would fail to complete mitosis. We also show that washing out the carcinogen decreases the frequency of mitotic defects in all three cell lines, but the mitotic index does not recover in the cancer cells. These findings demonstrate that carcinogen-induced mitotic defects have marked effects on the proliferative population of cells in terms of potential for contributing to chromosomal instability or removal from that population.

scholarly journals Trade-off between Plasticity and Velocity in Mycelial Growth

mBio ◽  
2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Sayumi Fukuda ◽  
Riho Yamamoto ◽  
Naoki Yanagisawa ◽  
Naoki Takaya ◽  
Yoshikatsu Sato ◽  
...  
Keyword(s):  
Cell Polarity ◽  
Cell Shape ◽  
Mycelial Growth ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Tip Growth ◽  
Animal Cells ◽  
Trade Off ◽  
Hyphal Tip Growth ◽  
Hyphal Tip

ABSTRACT Tip-growing fungal cells maintain cell polarity at the apical regions and elongate by de novo synthesis of the cell wall. Cell polarity and tip growth rate affect mycelial morphology. However, it remains unclear how both features act cooperatively to determine cell shape. Here, we investigated this relationship by analyzing hyphal tip growth of filamentous fungi growing inside extremely narrow 1 μm-width channels of microfluidic devices. Since the channels are much narrower than the diameter of hyphae, any hypha growing through the channel must adapt its morphology. Live-cell imaging analyses revealed that hyphae of some species continued growing through the channels, whereas hyphae of other species often ceased growing when passing through the channels, or had lost apical polarity after emerging from the other end of the channel. Fluorescence live-cell imaging analyses of the Spitzenkörper, a collection of secretory vesicles and polarity-related proteins at the hyphal tip, in Neurospora crassa indicates that hyphal tip growth requires a very delicate balance of ordered exocytosis to maintain polarity in spatially confined environments. We analyzed the mycelial growth of seven fungal species from different lineages, including phytopathogenic fungi. This comparative approach revealed that the growth defects induced by the channels were not correlated with their taxonomic classification or with the width of hyphae, but, rather, correlated with the hyphal elongation rate. This report indicates a trade-off between morphological plasticity and velocity in mycelial growth and serves to help understand fungal invasive growth into substrates or plant/animal cells, with direct impact on fungal biotechnology, ecology, and pathogenicity. IMPORTANCE Cell morphology, which is controlled by polarity and growth, is fundamental for all cellular functions. However how polarity and growth act cooperatively to control cell shape remains unclear. Here we investigated their relationship by analyzing hyphal tip growth of filamentous fungi growing inside extremely narrow 1 μm-width channels of microfluidic devices. We found that most fast growing hyphae often lost the cell polarity after emerging from the channels, whereas slow growing hyphae retained polarity and continued growing, indicating a trade-off between plasticity and velocity in mycelial growth. These results serve to understand fungal invasive growth into substrates or plant/animal cells, with direct impact on fungal biotechnology, ecology and pathogenicity.

scholarly journals Live cell imaging of meiosis in Arabidopsis thaliana

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Maria A Prusicki ◽  
Emma M Keizer ◽  
Rik P van Rosmalen ◽  
Shinichiro Komaki ◽  
Felix Seifert ◽  
...  
Keyword(s):  
Cell Shape ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Imaging System ◽  
Chromatin Condensation ◽  
Live Cell ◽  
Meiotic Progression ◽  
Cohesin Subunit ◽  
Nucleus Position ◽  
Imaging Setup

To follow the dynamics of meiosis in the model plant Arabidopsis, we have established a live cell imaging setup to observe male meiocytes. Our method is based on the concomitant visualization of microtubules (MTs) and a meiotic cohesin subunit that allows following five cellular parameters: cell shape, MT array, nucleus position, nucleolus position, and chromatin condensation. We find that the states of these parameters are not randomly associated and identify 11 cellular states, referred to as landmarks, which occur much more frequently than closely related ones, indicating that they are convergence points during meiotic progression. As a first application of our system, we revisited a previously identified mutant in the meiotic A-type cyclin TARDY ASYNCHRONOUS MEIOSIS (TAM). Our imaging system enabled us to reveal both qualitatively and quantitatively altered landmarks in tam, foremost the formation of previously not recognized ectopic spindle- or phragmoplast-like structures that arise without attachment to chromosomes.

scholarly journals Carcinogen treatment leads to mitotic defects and arrest in cancer and noncancer cells

2018 ◽  
Author(s):  
Rebecca G Hartling ◽  
Christian J Pacheco ◽  
Emily A Bystrak ◽  
Nicholas J Quintyne
Keyword(s):  
Estrogen Receptor ◽  
Mitotic Index ◽  
Cell Lines ◽  
Mitotic Spindle ◽  
Chromosomal Instability ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Chromosomal Rearrangements ◽  
Anaphase Bridges ◽  
Multipolar Spindles

Genomic instability can manifest due to both chromosomal rearrangements and gain and loss of entire chromosomes. One mechanism by which a carcinogen acts is by increasing the rate of mitotic spindle defects during proliferation. These defects can lead to chromosomal instability that manifest as lagging chromosomes, anaphase bridges, or multipolar spindles. While several mechanisms exist to rectify these errors prior to completion of mitosis, some cells will escape repair, while others will prematurely exit mitosis. Here we examine the effects of two carcinogenic molecules: Fulvestrant, a chemotherapeutic that functions as a selective estrogen receptor degrader, and vinyl chloride, a hydrocarbon used to produce PVC. We exposed two cancer lines, A549 and UPCI:SCC103, and one noncancer line, GM03349, to increasing concentrations of the carcinogen for increasing durations, up to 48 hours exposure. We found that exposure to the carcinogen lowered the mitotic index in the cancer cell lines, while raising it in the noncancer line. Concurrently, we observed massive increases in the frequency of mitotic defects, with the most significant increases seen in prevalence of lagging chromosomes in prometaphase and metaphase and anaphase bridges. Live cell imaging showed that the occurrence of either of these defects had the strongest correlation with the likelihood that the cell would fail to complete mitosis. We also show that washing out the carcinogen decreases the frequency of mitotic defects in all three cell lines, but the mitotic index does not recover in the cancer cells. These findings demonstrate that carcinogen-induced mitotic defects have marked effects on the proliferative population of cells in terms of potential for contributing to chromosomal instability or removal from that population.

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