A centrosome-associated antibody from Drosophila melanogaster reveals a new microtubule-dependent structure in the equatorial zone of Parascaris univalens embryos

1993 ◽  
Vol 106 (3) ◽  
pp. 719-730
Author(s):  
M. Jimenez ◽  
C. Goday
Keyword(s):  
Drosophila Melanogaster ◽  
Cytochalasin B ◽  
Cell Communication ◽  
Equatorial Zone ◽  
Contractile Ring ◽  
Daughter Cells ◽  
Ring Assembly ◽  
Single Body ◽  
A Cell ◽  
Cycle Dependent

The distribution of antigens to two antibodies (Bx63 and Rb188) that associate to Drosophila melanogaster centrosomes has been investigated in the nematode Parascaris. By western blot analysis both antibodies identify in Parascaris polypeptides of the same molecular mass as in Drosophila (Rb188 a 185 kDa antigen and Bx63 185 kDa and 66 kDa antigens). By immunocytochemistry we show that the centrosomes of Parascaris contain the 185 kDa antigen recognized by polyclonal Rb188 and monoclonal Bx63 antibodies. In addition, Bx63 reveals cytoplasmic midzone structures, not found in Drosophila, that display a cell cycle-dependent organization in embryos. These structures, which most probably contain the 66 kDa antigen revealed by Bx63, appear at the onset of anaphase as fibrillar-like structures that during anaphase form a ring-like structure encircling the equatorial plane of the blastomere. Before furrowing, the antigen participates in the formation of the midbody and associates with convergent polar microtubules. After blastomere division, Bx63 signal persists as a single body between the daughter cells. The analysis of chilled and nocodazole-treated embryos suggests that the localization of the midzone Bx63 antigen is dependent on non-kinetochore microtubules. Inhibition of furrowing by cytochalasin B shows that the antigen persists after the disassembly of microfilaments. Cytological observations of contractile ring and Bx63 ring assembly indicate that both structures do not simultaneously colocalize at the equatorial zone. The data suggest a spindle-dependent distribution of the Bx63 antigen during cytokinesis. We discuss the participation of this antigen in the organization of the midbody before furrowing, and consider the possible relevance of the midbody with respect to cell to cell communication during early development in nematodes.

scholarly journals How cortical waves drive fission of motile cells

2020 ◽  
Vol 117 (12) ◽  
pp. 6330-6338 ◽  
Author(s):  
Sven Flemming ◽  
Francesc Font ◽  
Sergio Alonso ◽  
Carsten Beta
Keyword(s):  
Reaction Diffusion ◽  
Cortical Actin ◽  
Animal Cells ◽  
Contractile Ring ◽  
Daughter Cells ◽  
Reaction Diffusion Model ◽  
Motile Cells ◽  
A Cell ◽  
Actin Waves ◽  
Cell Growth And Proliferation

Cytokinesis—the division of a cell into two daughter cells—is a key step in cell growth and proliferation. It typically occurs in synchrony with the cell cycle to ensure that a complete copy of the genetic information is passed on to the next generation of daughter cells. In animal cells, cytokinesis commonly relies on an actomyosin contractile ring that drives equatorial furrowing and separation into the two daughter cells. However, also contractile ring-independent forms of cell division are known that depend on substrate-mediated traction forces. Here, we report evidence of an as yet unknown type of contractile ring-independent cytokinesis that we termed wave-mediated cytofission. It is driven by self-organized cortical actin waves that travel across the ventral membrane of oversized, multinucleatedDictyostelium discoideumcells. Upon collision with the cell border, waves may initiate the formation of protrusions that elongate and eventually pinch off to form separate daughter cells. They are composed of a stable elongated wave segment that is enclosed by a cell membrane and moves in a highly persistent fashion. We rationalize our observations based on a noisy excitable reaction–diffusion model in combination with a dynamic phase field to account for the cell shape and demonstrate that daughter cells emerging from wave-mediated cytofission exhibit a well-controlled size.

Cytokinesis in the Heliozoan Actinophrys Sol

1974 ◽  
Vol 16 (3) ◽  
pp. 499-517
Author(s):  
C. D. OCKLEFORD
Keyword(s):  
Electron Microscopy ◽  
Daughter Cell ◽  
Culture Medium ◽  
Cytochalasin B ◽  
Pole Model ◽  
Contractile Ring ◽  
Daughter Cells ◽  
Antimitotic Drugs ◽  
Actinophrys Sol ◽  
Low Temperature Treatments

A study of cytokinesis in the heliozoan Actinophrys sol has been made using low-temperature treatments, antimitotic drugs, cytochalasin B, light microscopy and electron microscopy. It reveals that microtubular axopodia remain extended during cell division and play a major role in it. Data indicate that when organisms are attached to the bases of culture dishes the normal locomotive mechanism of the presumptive daughter cells pulls them apart. However, when Actinophrys are floating freely in their culture medium, they are still able to undertake division. In this situation interactions between axopodia from opposite daughter cell bodies appear to facilitate the movement apart of the prospective daughter cells. The present study and other published accounts indicate that a type of cytokinesis exists which is not explicable in terms of the ‘contractile ring’ or ‘fusing vesicle’ theories. To account for these observations a ‘barge pole’ model of division is suggested.

scholarly journals Australin: a chromosomal passenger protein required specifically for Drosophila melanogaster male meiosis

2008 ◽  
Vol 180 (3) ◽  
pp. 521-535 ◽  
Author(s):  
Shan Gao ◽  
Maria Grazia Giansanti ◽  
Graham J. Buttrick ◽  
Sharada Ramasubramanyan ◽  
Adam Auton ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Male Meiosis ◽  
Cell Cortex ◽  
Dependent Manner ◽  
Spindle Formation ◽  
Chromatid Cohesion ◽  
Chromosome Alignment ◽  
Chromosomal Passenger ◽  
A Cell ◽  
Cycle Dependent

The chromosomal passenger complex (CPC), which is composed of conserved proteins aurora B, inner centromere protein (INCENP), survivin, and Borealin/DASRA, localizes to chromatin, kinetochores, microtubules, and the cell cortex in a cell cycle–dependent manner. The CPC is required for multiple aspects of cell division. Here we find that Drosophila melanogaster encodes two Borealin paralogues, Borealin-related (Borr) and Australin (Aust). Although Borr is a passenger in all mitotic tissues studied, it is specifically replaced by Aust for the two male meiotic divisions. We analyzed aust mutant spermatocytes to assess the effects of fully inactivating the Aust-dependent functions of the CPC. Our results indicate that Aust is required for sister chromatid cohesion, recruitment of the CPC to kinetochores, and chromosome alignment and segregation but not for meiotic histone phosphorylation or spindle formation. Furthermore, we show that the CPC is required earlier in cytokinesis than previously thought; cells lacking Aust do not initiate central spindle formation, accumulate anillin or actin at the cell equator, or undergo equatorial constriction.

scholarly journals Diverse mechanisms regulate contractile ring assembly for cytokinesis in the two-cell C. elegans embryo

2022 ◽  
Author(s):  
Imge Ozugergin ◽  
Karina Mastronardi ◽  
Chris Law ◽  
Alisa Piekny
Keyword(s):  
Cell Types ◽  
Somatic Tissue ◽  
Ring Closure ◽  
Contractile Ring ◽  
C Elegans ◽  
Daughter Cells ◽  
The Core ◽  
Ring Assembly ◽  
Different Cell Types ◽  
Ring Position

Cytokinesis occurs at the end of mitosis due to the ingression of a contractile ring that cleaves the daughter cells. The core machinery regulating this crucial process is conserved among metazoans. Multiple pathways control ring assembly, but their contribution in different cell types is not known. We found that in the C. elegans embryo, AB and P1 cells fated to be somatic tissue and germline, respectively, have different cytokinesis kinetics supported by distinct myosin levels and organization. Through perturbation of RhoA or polarity regulators and the generation of tetraploid strains, we found that ring assembly is controlled by multiple fate-dependent factors that include myosin-levels, and mechanisms that respond to cell size. Active Ran coordinates ring position with the segregating chromatids in HeLa cells by forming an inverse gradient with importins that control the cortical recruitment of anillin. We found that the Ran pathway regulates anillin in AB cells, but functions differently in P1 cells. We propose that ring assembly delays in P1 cells caused by low myosin and Ran signaling coordinate the timing of ring closure with their somatic neighbours.

Fine Structure of Cytochalasin Induced Polyploid Cells

1968 ◽  
Vol 26 ◽  
pp. 122-123
Author(s):  
Awtar Krishan ◽  
Nestor Bohonos
Keyword(s):  
Fine Structure ◽  
Cytochalasin B ◽  
Present Report ◽  
Cell Monolayer ◽  
Polyploid Cell ◽  
Specific Cell ◽  
Nuclear Surface ◽  
Unsuccessful Attempt ◽  
Daughter Cells ◽  
Polyploid Cells

Cytochalasin B, a mould metabolite from Helminthosporium dermatioideum has been shown to interfere with specific cell activities such as cytoplasmic cleavage and cell movement. Cells undergoing nuclear division in the presence of cytochalasin B are unable to complete the separation of the resulting daughter cells. In time-lapse studies, the daughter cells coalesce after an initial unsuccessful attempt at separation and form large multinucleate polyploid cells. The present report describes the fine structure of the large polyploid cells induced in Earle's L-cell monolayer cultures by exposure to cytochalasin B (lγ/ml) for 92 hours.In the present material we have seen as many as 7 nuclei in these polyploid cells. Treatment with cytochalasin B for longer periods of time (6 to 7 days, with one medium change on the 3rd day) did not increase the number of nuclei beyond the 7 nuclei stage. Figure 1 shows a large polyploid cell with four nuclei. These nuclei are indistinguishable in their fine structure from those of the cells from control cultures but often show unusually large numbers of cytoplasmic invaginations and extensions of the nuclear surface (Figure 2).

The locomotory behaviour of small groups of fibroblasts

1965 ◽  
Vol 162 (988) ◽  
pp. 289-302 ◽  
Keyword(s):  
Small Groups ◽  
Control Groups ◽  
Isolated Cells ◽  
Daughter Cells ◽  
A Cell ◽  
Locomotory Behaviour ◽  
Chick Embryo Heart ◽  
Embryo Heart ◽  
Random Nature ◽  
Chemotactic Gradient

Small groups of two to four fibroblasts at the periphery of outgrowths from cultured explants of chick embryo heart were isolated from their neighbours by sweeping away the nearby cells. The groups and the explants were left attached to the glass substrate, undisturbed. The behaviour of the isolated cells was photographically recorded during about 8 h of further culture. The cells of these groups dispersed, though not as a rule so far as to lose all mutual contacts, the dispersal being counterbalanced by the addition of new cells through mitosis. The accompanying changes in speed of locomotion, and the non-random nature of the spreading, are interpreted in terms of the effects of contacts between the cells. During the first four hours after isolation, but not thereafter, the cells of the groups on the average moved slowly away from the explant. Control groups in an intact outgrowth moved away faster and with no diminution of speed during the period of observation. The movement of the isolated groups can be partly accounted for by the tendency of cells to conserve for a time the direction of their movement before isolation; and by a strong reluctance of the isolated cells to move across the area, from which cells had been scraped away, that lay between the group and the explant. A new outgrowth of the residual sheet of cells still connected to the explant, however, advanced across this area, approaching and in most cases overhauling the isolated group. It is concluded that a chemotactic gradient around the explant is unlikely to play any significant part in the outward movement of fibroblasts from an explant in tissue culture. The cells of the isolated groups underwent an outburst of mitosis about 3 h after isolation. Mitoses in these relatively free cells are oriented in relation to the polarity of the cell before division. Locomotion of the daughter-cells tends to be faster than usual for at least 2 h after a cell divides.

scholarly journals Truncated APC regulates the transcriptional activity of β-catenin in a cell cycle dependent manner

2006 ◽  
Vol 16 (2) ◽  
pp. 199-209 ◽  
Author(s):  
Jean Schneikert ◽  
Annette Grohmann ◽  
Jürgen Behrens
Keyword(s):  
Cell Cycle ◽  
Transcriptional Activity ◽  
Dependent Manner ◽  
A Cell ◽  
Cycle Dependent
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