scholarly journals Drosophila centrocortin is dispensable for centriole duplication but contributes to centrosome separation

2021 ◽  
Author(s):  
Dipen S Mehta ◽  
Hala Zein-Sabatto ◽  
Pearl V Ryder ◽  
Jina Lee ◽  
Dorothy A Lerit
Keyword(s):  
Mitotic Spindle ◽  
Time Lapse ◽  
Prior Work ◽  
Microtubule Organizing Centers ◽  
Centriole Duplication ◽  
Centrosome Separation ◽  
Kinetics Of

Abstract Centrosomes are microtubule-organizing centers that duplicate exactly once to organize the bipolar mitotic spindle required for error-free mitosis. Prior work indicated that Drosophila centrocortin (cen) is required for normal centrosome separation, although a role in centriole duplication was not closely examined. Through time-lapse recordings of rapid syncytial divisions, we monitored centriole duplication and the kinetics of centrosome separation in control vs. cen null embryos. Our data suggest that although cen is dispensable for centriole duplication, it contributes to centrosome separation.

scholarly journals Drosophila centrocortin is dispensable for centriole duplication but contributes to centrosome separation

2021 ◽  
Author(s):  
Dipen S. Mehta ◽  
Pearl V. Ryder ◽  
Jina Lee ◽  
Hala Zein-Sabatto ◽  
Dorothy A. Lerit
Keyword(s):  
Mitotic Spindle ◽  
Time Lapse ◽  
Prior Work ◽  
Microtubule Organizing Centers ◽  
Centriole Duplication ◽  
Centrosome Separation ◽  
Control Versus ◽  
Kinetics Of

Centrosomes are microtubule-organizing centers that duplicate exactly once to organize the bipolar mitotic spindle required for error-free mitosis. Prior work indicated that Drosophila centrocortin ( cen ) is required for normal centrosome separation, although a role in centriole duplication was not closely examined. Through time-lapse recordings of rapid syncytial divisions, we monitored centriole duplication and the kinetics of centrosome separation in control versus cen null embryos. Our data suggest that although cen is dispensable for centriole duplication, it contributes to centrosome separation.

scholarly journals Albatross/FBF1 contributes to both centriole duplication and centrosome separation

2018 ◽  
Vol 23 (12) ◽  
pp. 1023-1042 ◽  
Author(s):  
Akihito Inoko ◽  
Tomoki Yano ◽  
Tatsuo Miyamoto ◽  
Shinya Matsuura ◽  
Tohru Kiyono ◽  
...  
Keyword(s):  
Centriole Duplication ◽  
Centrosome Separation

scholarly journals THE TIME OF SYNTHESIS AND THE CONSERVATION OF MITOSIS-RELATED PROTEINS IN CULTURED HUMAN AMNION CELLS

1967 ◽  
Vol 34 (1) ◽  
pp. 97-110 ◽  
Author(s):  
Jesse E. Sisken ◽  
Elaina Wilkes
Keyword(s):  
Time Lapse ◽  
Major Effect ◽  
Human Amnion ◽  
Daughter Cells ◽  
Low Concentrations ◽  
Associated Proteins ◽  
A Cell ◽  
Quantitative Analyses ◽  
Related Proteins ◽  
Kinetics Of

p-Fluorophenylalanine (PFPA), an analogue of phenylalanine which may be incorporated into proteins, increases the duration of mitosis. In the present experiments, based upon quantitative analyses of time-lapse cinemicrographic films, brief treatments of cells with PFPA are shown to affect the duration of metaphase in only those cells which enter division during or shortly after treatment. The offspring of cells with prolonged metaphases also tend to have prolonged metaphases. Analyses of the kinetics of the appearance of prolonged metaphases indicate that some protein specifically associated with mitosis is synthesized primarily during a period which corresponds closely to G2. The manner in which the defect is passed on to daughter cells indicates that the protein involved is conserved and reutilized by daughter cells for their subsequent divisions. Comparable experiments performed with low concentrations of puromycin indicate that the major effect of PFPA is due to its incorporation into protein rather than its ability to inhibit protein synthesis. The fact that puromycin-induced effects can also be passed on to daughter cells is interpreted to mean that cells make only specific amounts of some mitosis-associated proteins and that if a cell "inherits" a deficiency in such protein it is not able to compensate for the deficiency.

Regulation of Mitosis

1969 ◽  
Vol 5 (3) ◽  
pp. 745-755
Author(s):  
W. T. JACKSON
Keyword(s):  
Mitotic Spindle ◽  
Time Lapse ◽  
Polarization Microscopy ◽  
Animal Cells ◽  
Higher Plant ◽  
Competitive Antagonism ◽  
Dividing Cells ◽  
Spindle Microtubules ◽  
Giant Nuclei

Earlier studies on the effects of the herbicide isopropyl N-phenylcarbamate (IPC) on mitosis revealed blocked metaphases, multinucleate cells, giant nuclei and an increase in number of partly contracted chromosomes. It was assumed that IPC, like colchicine, was causing these effects by disruption of the spindle apparatus by destroying the spindle microtubules. The animal hormone melatonin causes an increase in birefringence of the mitotic spindle in animal cells, presumably by increasing the number of microtubules. We have studied the effects of IPC, melatonin, and combinations of the two on mitosis in dividing endosperm cells of the African blood lily (Haemanthus katherinae Baker) in vivo by phase-contrast and polarization microscopy. Both qualitative and quantitative data are presented. Interpretation of these results has been aided materially by a time-lapse cinemicrographic analysis of dividing cells subjected to 1 and 10 p.p.m. IPC (unpublished) and by an accompanying fine-structural analysis of untreated and IPC-treated cells. Mitosis was disrupted by 0.01-10 p.p.m. IPC, the severity of the effect depending on both concentration and stage of mitosis of the cell at the time of treatment. Concentrations of IPC that caused cessation of chromosome movement also caused loss of birefringence of the mitotic spindle. Melatonin increased birefringence of the mitotic spindle in these plant cells and partly nullified the adverse effects of IPC. The results of this study demonstrate that the herbicide IPC, under our conditions, causes disruption of mitosis and loss of birefringence of the spindle. And it has been established that an animal hormone is capable of increasing the birefringence, and presumably the number of microtubules, of the mitotic spindle in dividing endosperm cells of a higher plant. Although melatonin is capable of partly nullifying the effects of IPC, a competitive antagonism is not postulated.

Boursin, a sea urchin bimC kinesin protein, plays a role in anaphase and cytokinesis

2001 ◽  
Vol 114 (3) ◽  
pp. 481-491 ◽  
Author(s):  
I. Touitou ◽  
G. Lhomond ◽  
G. Pruliere
Keyword(s):  
Cell Division ◽  
Sea Urchin ◽  
Paracentrotus Lividus ◽  
Time Lapse ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Early Prophase ◽  
Immunofluorescence Analysis ◽  
Centrosome Separation ◽  
Late Stages

We have isolated and characterized Boursin, a kinesin-related protein of the bimC family, from Paracentrotus lividus sea urchin eggs. Boursin is expressed at high levels in eggs and embryos during early cleavage stages. Boursin was found to be associated with different parts of the mitotic spindle from early prophase to telophase. Expression of a form of the protein predicted to act as a dominant negative mutant caused severe defects in cell division and resulted in the formation of embryos with polyploid and multiastral blastomeres. Immunofluorescence analysis indicated that these defects did not arise from failure in either centrosome separation or bipolar spindle formation. Time-lapse observations showed rather that these perturbations in cell division resulted from abnormal anaphase and failure to complete cytokinesis. These phenotypes differ from the phenotype described following perturbation of the function of bimC family members in other organisms. Our study has thus uncovered roles for a bimC kinesin in late stages of cell division.

In-situ disintegration of egg white gels by pepsin and kinetics of nutrient release followed by time-lapse confocal microscopy

2020 ◽  
Vol 98 ◽  
pp. 105228 ◽  
Author(s):  
Geeshani Somaratne ◽  
Francoise Nau ◽  
Maria J. Ferrua ◽  
Jaspreet Singh ◽  
Aiqian Ye ◽  
...  
Keyword(s):  
Confocal Microscopy ◽  
Nutrient Release ◽  
Time Lapse ◽  
Egg White ◽  
Kinetics Of

scholarly journals Microtubule Cytoskeleton Remodeling by Acentriolar Microtubule-organizing Centers at the Entry and Exit from Mitosis in Drosophila Somatic Cells

2009 ◽  
Vol 20 (11) ◽  
pp. 2796-2808 ◽  
Author(s):  
Sara Moutinho-Pereira ◽  
Alain Debec ◽  
Helder Maiato
Keyword(s):  
Cell Cycle ◽  
Mitotic Spindle ◽  
De Novo ◽  
Animal Cell ◽  
Somatic Cells ◽  
Spindle Assembly ◽  
Entry And Exit ◽  
Down Regulation ◽  
Microtubule Organizing Centers ◽  
Cytoskeleton Remodeling

Cytoskeleton microtubules undergo a reversible metamorphosis as cells enter and exit mitosis to build a transient mitotic spindle required for chromosome segregation. Centrosomes play a dominant but dispensable role in microtubule (MT) organization throughout the animal cell cycle, supporting the existence of concurrent mechanisms that remain unclear. Here we investigated MT organization at the entry and exit from mitosis, after perturbation of centriole function in Drosophila S2 cells. We found that several MTs originate from acentriolar microtubule-organizing centers (aMTOCs) that contain γ-tubulin and require Centrosomin (Cnn) for normal architecture and function. During spindle assembly, aMTOCs associated with peripheral MTs are recruited to acentriolar spindle poles by an Ncd/dynein-dependent clustering mechanism to form rudimentary aster-like structures. At anaphase onset, down-regulation of CDK1 triggers massive formation of cytoplasmic MTs de novo, many of which nucleated directly from aMTOCs. CDK1 down-regulation at anaphase coordinates the activity of Msps/XMAP215 and the kinesin-13 KLP10A to favor net MT growth and stability from aMTOCs. Finally, we show that microtubule nucleation from aMTOCs also occurs in cells containing centrosomes. Our data reveal a new form of cell cycle–regulated MTOCs that contribute for MT cytoskeleton remodeling during mitotic spindle assembly/disassembly in animal somatic cells, independently of centrioles.

scholarly journals Rapid Intermittent Movement of Axonal Neurofilaments Observed by Fluorescence Photobleaching

2001 ◽  
Vol 12 (10) ◽  
pp. 3257-3267 ◽  
Author(s):  
Lei Wang ◽  
Anthony Brown
Keyword(s):  
Time Lapse ◽  
Cytoskeletal Proteins ◽  
Cultured Neurons ◽  
Neurofilament Proteins ◽  
Neurofilament Protein ◽  
Slow Axonal Transport ◽  
Fluorescent Intensity ◽  
Naturally Occurring ◽  
Time Lapse Imaging ◽  
Kinetics Of

Observations on naturally occurring gaps in the axonal neurofilament array of cultured neurons have demonstrated that neurofilament polymers move along axons in a rapid, intermittent, and highly asynchronous manner. In contrast, studies on axonal neurofilaments using laser photobleaching have not detected movement. Here, we describe a modified photobleaching strategy that does permit the direct observation of neurofilament movement. Axons of cultured neurons expressing GFP-tagged neurofilament protein were bleached by excitation with the mercury arc lamp of a conventional epifluorescence microscope for 12–60 s. The length of the bleached region ranged from 10 to 60 μm. By bleaching thin axons, which have relatively few neurofilaments, we were able to reduce the fluorescent intensity enough to allow the detection of neurofilaments that moved in from the surrounding unbleached regions. Time-lapse imaging at short intervals revealed rapid, intermittent, and highly asynchronous movement of fluorescent filaments through the bleached regions at peak rates of up to 2.8 μm/s. The kinetics of movement were very similar to our previous observations on neurofilaments moving through naturally occurring gaps, which indicates that the movement was not impaired by the photobleaching process. These results demonstrate that fluorescence photobleaching can be used to study the slow axonal transport of cytoskeletal polymers, but only if the experimental strategy is designed to ensure that rapid asynchronous movements can be detected. This may explain the failure of previous photobleaching studies to reveal the movement of neurofilament proteins and other cytoskeletal proteins in axons.

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