Effects of cytochalasin B on the cleavage furrow in mouse blastomeres

1986 ◽  
Vol 195 (2) ◽  
pp. 137-141 ◽  
Author(s):  
Jolanta Karasiewicz ◽  
Maria S. Soltyńska
Keyword(s):  
Cytochalasin B ◽  
Cleavage Furrow

The permeability to cytochalasin B of the new unpigmented surface in the first cleavage furrow of the newt's egg

Development ◽  
1976 ◽  
Vol 36 (2) ◽  
pp. 321-341
Author(s):  
G. G. Selman ◽  
J. Jacob ◽  
M. M. Perry
Keyword(s):  
Osmium Tetroxide ◽  
Cytochalasin B ◽  
Specific Activity ◽  
High Specific Activity ◽  
Scintillation Counting ◽  
Cleavage Furrow ◽  
Limited Extent ◽  
Normal Medium ◽  
Cleavage Initiation ◽  
Whole Egg

Two to 10 µg/ml cytochalasin B (CB) caused retraction of the first cleavage furrow in Triturus eggs, a spreading of the unpigmented surface from the furrow region and a flattening of the whole egg. CB appears to act against the contractility of the microfilamentous band at mid-cleavage so as to relax the furrow and also to weaken unpigmented surface to allow the egg to flatten. Uncleaved eggs and the initial formation of the cleavage groove were unaffected by CB. A fully-retracted first cleavage furrow reformed itself on transfer of the egg to normal medium but only at the time of second cleavage. Initiation of second cleavage depended upon there being sufficient of the original pigmented surface on the animal hemisphere. Tritium-labelled CB of high specific activity was prepared and used to study its ability to penetrate the surface of newt eggs during cleavage. Scintillation counting of whole eggs showed that CB was not taken into the newt egg until mid-cleavage (about 17 min after the double stripe stage) when new surface began to spread in the cleavage furrow. Fixation in glutaraldehyde and osmium tetroxide retained radioactivity in the egg, but more CB was retained after fixation in osmium tetroxide alone than after double fixation. Most of the retained radioactivity was in yolk platelets. Autoradiographs were prepared of sectioned eggs whichad been fixed at late cleavage after [3H]CB had flattened the furrow. These showed that CBentered the egg through the unpigmented surface which formed in the furrow but it could not enter through the pigmented surface. The impermeability of the pigmented surface explains the observations that CB does not prevent initial furrowing at cleavage. Once inside the egg CB is transported slowly. CB penetrates to a limited extent beneath the pigmented surface from its border with the unpigmented surface in the first cleavage furrow and this seems insufficient in some circumstances to suppress the contractile phase of second cleavage.

Insensitivity to cytochalasin B of surface contractions keyed to cleavage in the Xenopus egg

Development ◽  
1982 ◽  
Vol 72 (1) ◽  
pp. 143-151
Author(s):  
Kathy Christensen ◽  
R. W. Merriam
Keyword(s):  
Xenopus Laevis ◽  
Internal Pressure ◽  
Cytochalasin B ◽  
Cleavage Furrow ◽  
Initial Appearance ◽  
Xenopus Egg

In fertilized eggs of Xenopus laevis a marked flattening of the pigmented animal hemisphere has been observed. The flattening begins 15–20 minutes before the appearance of the cleavage furrow. As the furrow develops, the pigmented surface relaxes and rounds up. The initial appearance of the furrow is thus shown to be a combination of furrow deepening and rounding up of adjacent pigmented surfaces. It is demonstrated that the flattening is not caused by gravity or osmotic mechanisms and that internal pressure is increased during the flattening. The flattening is interpreted to be an isodiametric contraction of the pigmented surface. The contraction is not inhibited by injected cytochalasin B in sufficient concentrations to completely inhibit cleavage furrow formation. These results are discussed with respect to the presence of two surface contractile systems, distinguishable on the basis of their differing sensitivity to cytochalasin B.

scholarly journals CYTOCHALASIN-B: TIME-LAPSE CINEMATOGRAPHIC STUDIES ON ITS EFFECTS ON CYTOKINESIS

1972 ◽  
Vol 54 (3) ◽  
pp. 657-664 ◽  
Author(s):  
Awtar Krishan
Keyword(s):  
Cytochalasin B ◽  
Normal Development ◽  
Time Lapse ◽  
Cleavage Furrow ◽  
Cellular Motility ◽  
Drug Induced ◽  
Multinucleate Cells ◽  
Daughter Cells ◽  
Cell Divisions ◽  
Induced Changes

L cells exposed to cytochalasin-B (cyto-B) show the normal development of deep cleavage furrows in both bipolar and multipolar cell divisions Due to the drug-induced inhibition of cellular motility, the resulting daughter cells do not move away from each other but reunite to form multinucleate cells. In mitotic cells from cultures exposed to cyto-B for long periods of time, vigorous blebbing and contraction of the cell surface is seen The evidence from time-lapse studies presented suggests that cyto-B-induced multinucleate cells are formed, not by the failure of the cleavage furrow, but by the drug-induced changes in surface activity and motility of cells after division.

scholarly journals THE CONTRACTILE RING

1972 ◽  
Vol 53 (2) ◽  
pp. 419-434 ◽  
Author(s):  
Thomas E. Schroeder
Keyword(s):  
Plasma Membrane ◽  
Sea Urchin ◽  
Cytochalasin B ◽  
Vital Role ◽  
Strict Sense ◽  
Cleavage Furrow ◽  
Contractile Ring ◽  
Cell Cleavage ◽  
Uniform Ring

The first cleavage furrow in eggs of Arbacia (sea urchin) is accompanied by a uniform ring of aligned microfilaments, called the contractile ring. Individual contractile ring filaments measure 35–60 A and occasionally appear "hollow." The contractile ring exists from about 20 sec after anaphase to the end of furrowing activity, i.e., 6–7 min at 20°C. It is closely associated with the plasma membrane at all times, and is probably assembled there. It is about 8 µ wide and 0.2 µ thick throughout cleavage. Its volume decreases, however, suggesting a contraction-related disassembly of contractile ring filaments, rather than a sliding-filament mechanism in the strict sense. Cytochalasin B (>10-6 M) arrests cleavage within 60 sec, by which time contractile ring filaments are no longer visible ultrastructurally. The furrow may be seen to recede within this time. Karyokinesis is unaffected. Simultaneous disruption of furrowing activity and of the contractile ring largely confirms the vital role of the contractile ring as the organelle of cell cleavage.

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).

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