Relative changes in F-actin during the first cell cycle: Evidence for two distinct pools of F-actin in the sea urchin egg

Heil‐Chapdelaine, Richard A.; Otto, Joann J.

doi:10.1002/(sici)1097-0169(1996)34:1<26::aid-cm3>3.0.co;2-g

Cited by 8 publications

(5 citation statements)

References 37 publications

(24 reference statements)

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“…Since several other potential signaling and cytoskeletal proteins were not represented in the egg lipid rafts, this suggests that the raft material was not an aggregation or cytoskeletal complex artifact. As expected (Otto et al, 1980;Bonder and Fishkind, 1995;Heil-Chapdelaine and Otto, 1996), actin recruited into the egg cytoskeleton is highly enriched in the TX-100 insoluble fraction following fertilization. However, actin was never detected in the egg lipid raft fractions either before or after fertilization.…”

Section: Evidence For the Existence Of Eggsupporting

confidence: 76%

Isolation and characterization of sea urchin egg lipid rafts and their possible function during fertilization

Belton

Adams

Foltz

2001

Molecular Reproduction Devel

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Specialized membrane microdomains called rafts are thought to play a role in many types of cell-cell interactions and signaling. We have investigated the possibility that sea urchin eggs contain these specialized membrane microdomains and if they play a role in signal transduction at fertilization. A low density, TX-100 insoluble membrane fraction, typical of lipid rafts, was isolated by equilibrium gradient centrifugation. This raft fraction contained proteins distinct from cytoskeletal complexes. The fraction was enriched in tyrosine phosphorylated proteins and contained two proteins known to be involved in signaling during egg activation (an egg Src-type kinase and PLC gamma). This fraction was further characterized as a prototypical raft fraction by the release of proteins in response to in vitro treatment of the rafts with the cholesterol binding drug, methyl-beta-cyclodextrin (M beta CD). Furthermore, treatment of eggs with M beta CD inhibited fertilization, suggesting that egg lipid rafts play a physiological role in fertilization. Mol. Reprod. Dev. 59:294-305, 2001.

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Section: Evidence For the Existence Of Eggsupporting

confidence: 76%

Isolation and characterization of sea urchin egg lipid rafts and their possible function during fertilization

Belton

Adams

Foltz

2001

Molecular Reproduction Devel

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“…While this article was in review, two studies appeared that examined changes in the amount and organi-zation of filamentous actin in the sea urchin egg during early development [Terasaki, 1996;Heil-Chapdelaine and Otto, 1996]. Confocal microscopy of living, fertilized Lytechinus pictus eggs microinjected with rhodamine phalloidin or rhodamine phalloidin-labeled actin filaments revealed the transient assembly of bundles of actin filaments in the fertilization cone and rootlet-like bundles of actin filaments in the egg cortex [Terasaki, 1996], similar to those described in this report.…”

Section: Changes In Cortical Actin Content During the Cell Cyclesupporting

confidence: 65%

Dynamics of filamentous actin organization in the sea urchin egg cortex during early cleavage divisions: Implications for the mechanism of cytokinesis

Wong

Allen

Begg

1997

Cell Motil. Cytoskeleton

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We have used confocal laser scanning microscopy in conjunction with BODIPY‐phallacidin staining of filamentous actin to investigate changes in the quantity and organization of cortical actin during the first two cell cycles following fertilization in eggs of the sea urchin Strongylocentrotus purpuratus. Quantification of fluorescent phallacidin staining reveals that the amount of filamentous actin (F‐actin) in the cortex undergoes cyclical increases and decreases during early cleavage divisions, peaking near the beginning of the cell cycle and decreasing to a minimum at cytokinesis. Changes in the content of cortical F‐actin are accompanied by the growth and disappearance of rootlet‐like bundles of actin filaments which extend from the bases of microvilli that cover the surface of the egg. Actin rootlets reach their maximum degree of development by 20 min postfertilization, and then gradually decrease in number and length over the next 40 min. Small actin rootlets persist until cleavage, disappear during cytokinesis, and reform following division. The formation of actin rootlets requires cytoplasmic alkalization and is inhibited by cytochalasin D. Cytochalasin D washout experiments demonstrate that assembly of the cortical actin cytoskeleton can be blocked until 5 min before the onset of cleavage and still allow normal cytokinesis. These results illustrate the dynamic nature of cortical actin organization during early development and demonstrate that cytokinesis occurs at the point of minimum cortical F‐actin content. They further demonstrate that cytokinesis can occur in embryos in which the normal developmental sequence of changes in cortical actin organization has been blocked by treatment with cytochalasin D, suggesting that these changes do not function in the establishment of the contractile apparatus for cytokinesis, but rather serve other developmental functions. Cell Motil. Cytoskeleton 36:30–42, 1997. © 1997 Wiley‐Liss, Inc.

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“…Importantly, in contrast to fertilized eggs, unfertilized eggs do not feature any large-scale cytoskeletal organization, with F-actin and microtubule filaments distributed throughout the cytoplasm, and no detectable thick actin cortex ( SI Appendix , Fig. S1 A and B ) ( 29 ). In addition, particle imaging velocimetry (PIV) of relatively large granules did not reveal any persistent cytoplasm flows, suggesting that the cytoplasm material may be considered at rest in these cells ( SI Appendix , Fig.…”

Section: Resultsmentioning

confidence: 99%

Size- and position-dependent cytoplasm viscoelasticity through hydrodynamic interactions with the cell surface

Najafi

Dmitrieff

Minc

2023

Proc. Natl. Acad. Sci. U.S.A.

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Many studies of cytoplasm rheology have focused on small components in the submicrometer scale. However, the cytoplasm also baths large organelles like nuclei, microtubule asters, or spindles that often take significant portions of cells and move across the cytoplasm to regulate cell division or polarization. Here, we translated passive components of sizes ranging from few up to ~50 percents of the cell diameter, through the vast cytoplasm of live sea urchin eggs, with calibrated magnetic forces. Creep and relaxation responses indicate that for objects larger than the micron size, the cytoplasm behaves as a Jeffreys material, viscoelastic at short timescales, and fluidizing at longer times. However, as component size approached that of cells, cytoplasm viscoelastic resistance increased in a nonmonotonic manner. Flow analysis and simulations suggest that this size-dependent viscoelasticity emerges from hydrodynamic interactions between the moving object and the static cell surface. This effect also yields to position-dependent viscoelasticity with objects initially closer to the cell surface being harder to displace. These findings suggest that the cytoplasm hydrodynamically couples large organelles to the cell surface to restrain their motion, with important implications for cell shape sensing and cellular organization.

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Relative changes in F-actin during the first cell cycle: Evidence for two distinct pools of F-actin in the sea urchin egg

Cited by 8 publications

References 37 publications

Isolation and characterization of sea urchin egg lipid rafts and their possible function during fertilization

Isolation and characterization of sea urchin egg lipid rafts and their possible function during fertilization

Dynamics of filamentous actin organization in the sea urchin egg cortex during early cleavage divisions: Implications for the mechanism of cytokinesis

Size- and position-dependent cytoplasm viscoelasticity through hydrodynamic interactions with the cell surface

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