The Contractile Ring

Schroeder, Thomas E.

doi:10.1083/jcb.53.2.419

Cited by 361 publications

(186 citation statements)

References 33 publications

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“…In the division furrow, actin filaments accumulated to 1.8-fold of those in the reference cortex. Actin accumulation in the division furrow has been reported frequently including polar body formation using fluorescent phallotoxins (Strome, 1986;Yonemura and Kinoshita, 1986;Cao and Wang, 1990;Shimizu, 1990;Mabuchi, 1994;Li et al, 1997;Crawford et al, 1998;Satoh and Hamaguchi, 2000;Pielak et al, 2004Pielak et al, , 2005 after the contractile ring was described in the division furrow by Schroeder (1968Schroeder ( , 1970Schroeder ( , 1972. Therefore, actin distribution from the animal pole to the equatorial region of the oocyte is minimal at the pole, increases to maximal at the base of the bulge, and then decreases gradually to a constant value.…”

Section: Cortical Actin Distributionmentioning

confidence: 97%

Quantitative Analysis of Cortical Actin Filaments during Polar Body Formation in Starfish Oocytes

Hamaguchi

Numata

Satoh

2007

Cell Struct. Funct.

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ABSTRACT. Polar body formation is an extremely unequal cell division. In order to understand the mechanism of polar body formation, morphological changes at the animal pole were investigated in living oocytes of the starfish, Asterina pectinifera, and the amounts of cortical actin filaments were quantitatively estimated after staining the maturing oocytes with fluorescently-labeled phallotoxins using a computer and image-processing software. Formation of a bulge, which is presumed to become a polar body, and the anaphase separation of chromosomes occurred simultaneously. When the bulge became large, one group of chromatids moved into the bulge. The dividing furrow then formed and finally a polar body formed. Just at the time of bulge formation, the intensity of the fluorescence produced by the actin filaments at the top of the animal pole began to decrease, and subsequently the intensity at the top fell to half of the original value. On the other hand, the fluorescence intensity at the base of the bulge increased gradually. This actin accumulation at the base created a dividing furrow around the top of the animal pole as the bulge grew. Even when the polar body formation was inhibited mechanically, a similar pattern of actin deficiency and accumulation in the cortex near the animal pole was observed. This indicates that such regulation of filamentous actin can take place without bulging. Therefore, polar body formation is initiated by the bulging of the cortex weakened by actin deficiency and followed by contraction of the base of the bulge reinforced by actin accumulation.

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Section: Cortical Actin Distributionmentioning

confidence: 97%

Quantitative Analysis of Cortical Actin Filaments during Polar Body Formation in Starfish Oocytes

Hamaguchi

Numata

Satoh

2007

Cell Struct. Funct.

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“…The cell divisions and later developmental stages of the urchin embryo must involve control mechanisms of this kind. Studies of the cleavage furrow of the sea urchin egg (19) have shown that changes in the form and distribution of fibrous material may occur over relatively short periods of the cell cycle. Amoeboid motion plays a major role in the cell movements at gastrulation of the sea urchin embryo (6), and experimental procedures which induce amoeboid movement in uncleaved marine eggs have been reported (18).…”

Section: Discussionmentioning

confidence: 99%

Actin polymerization and interaction with other proteins in temperature-induced gelation of sea urchin egg extracts.

Kane¹

1976

The Journal of Cell Biology

132

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The gel which forms on warming the extracts of the cytoplasmic proteins of sea urchin eggs has been separated into two fractions, one containing F-actin and the other containing two proteins of 58,000 and 220,000 mol wt. When combined in 0.1 M KCI, even at 0~ these components will form gel material identical to that formed by warming extracts. This gel is a network of laterally aggregated F-actin filaments which are in register and which display a complex cross-banding pattern generated by the presence of the other two proteins. Low concentrations of calcium block the assembly of these proteins to form this complex structure, which may play some cytoskeletal role in the cytoplasm.This association of F-actin with the other proteins to form a gel is very likely the last step of the process occurring in warmed extracts. At low temperatures, gelation of extracts is limited by the relative absence of F-actin, as demonstrated by the inability to sediment it at 100,000 g and also by the fact that gelation occurs immediately if exogenous Foactin is added to cold extracts. The transformation of the G-actin present in the extract to the F-form is apparently repressed at low temperatures. This is shown directly by the failure of added G-actin to polymerize at low temperatures in the presence of extract. These observations resemble those which have been reported on preparations from amoeboid cells and may be significant in the involvement of actin and these other proteins in cell division and later developmental processes.In a previous publication (10) it was demonstrated that warming an extract of the soluble cytoplasmic proteins of the sea urchin egg caused the formation of a gel in the solution, visible in the light microscope as a net of birefringent threads. The extraction medium contained sufficient glycerol to render it isotonic, EGTA to chelate the cell calcium, and buffer to control the pH during homogenization. Dialysis of the extract to remove all small molecular weight components reduced or eliminated this gelation on warming, but gelation could be restored by the addition of ATP and KC1. Gelation was not temperature reversible, as the gels were stable at 0~ once formed, but the material was soluble in high salt (0.5-1 M) solution after centrifugation from the extract. Subsequent reduction of the salt concentration of this dissolved gel solution to approx. 0.1 M by dilution or dialysis caused the reappearance of the gel, a process which does not require warming and which will occur at 0~ Sodium dodecyl sulfate (SDS) gel electrophoresis showed three major components to be present in this dissolved gel: a protein which co-migrated 704

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“…This sea urchin egg actin was first identified and separated through its combination with rabbit muscle myosin (8,18,19), and the protein was later prepared directly from egg extracts by salting out with ammonium sulfate (17). These preparative methods gave no information concerning the localization of the actin within the egg, but there is good evidence lor its presence in the cleavage furrow during cytokinesis, where it was seen first in the electron microscope as bundles of microfilaments (28,30,37). Actin has been localized in the cleavage furrow in a variety of other cell types ( 1,21,27,29,34) and this actin has been specifically labeled with heavy meromyosin (31).…”

mentioning

confidence: 99%

Preparation and purification of polymerized actin from sea urchin egg extracts.

Kane¹

1975

The Journal of Cell Biology

219

145

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Isotonic extracts of the soluble cytoplasmic proteins of sea urchin eggs, containing sufficient EGTA to reduce the calcium concentration to low levels, form a dense gel on warming to 35 40~ Although this procedure is similar to that used to polymerize tubulin from mammalian brain, sodium dodecyl sulfate-polyacrylamide gel electrophoresis shows this gel to have actin as a major component and to contain no tubulin. If such extracts are dialyzed against dilute salt solution, they no longer respond to warming, but gelation will occur if they are supplemented with 1 mM ATP and 0.020 M KC1 before heating. Gelation is not temperature reversible, but the gelled material can be dissolved in 0.6-1 M J~C1 and these solutions contain F-actin filaments. These filaments slowly aggregate to microscopic, birefringent fibrils when l mM ATP is added to the solution, and this procedure provides a simple method for preparing purified actin. The supernate remaining after actin removal contains the other two components of the gel, proteins of approximately 58,000 and 220,000 mol wt. These two proteins plus actin recombine to form the original gel material when the ionic strength is reduced. This reaction is reversible at 0~ and no heating is required.Following the demonstration of an actin-like protein, similar in properties to muscle actin, in myxomycete plasmodium (9, 10), similar methods revealed the presence of a cytoplasmic actin in unfertilized sea urchin eggs. This sea urchin egg actin was first identified and separated through its combination with rabbit muscle myosin (8,18,19), and the protein was later prepared directly from egg extracts by salting out with ammonium sulfate (17). These preparative methods gave no information concerning the localization of the actin within the egg, but there is good evidence lor its presence in the cleavage furrow during cytokinesis, where it was seen first in the electron microscope as bundles of microfilaments (28,30,37). Actin has been localized in the cleavage furrow in a variety of other cell types ( 1,21,27,29,34) and this actin has been specifically labeled with heavy meromyosin (31). The investigations reported here were begun with the aim of determining whether the methods developed for the polymerization of tubulin to microtubules in mammalian brain (2, 39) could be used to prepare tubulin from the sea urchin egg. Marine eggs are an excellent source of isolated mitotic apparatuses for the investigation of the role of microtubules in chromosome movement, but up to this time only the interaction of mammalian brain tuhulin with such isolated mitotic apparatuses has been reported (12, 25). Our attempts to prepare tubulin from extracts of sea urchin eggs with the methods developed for mammalian material were unsuccessful, and a number of modifications of this method were made to adapt it to the

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The Contractile Ring

Cited by 361 publications

References 33 publications

Quantitative Analysis of Cortical Actin Filaments during Polar Body Formation in Starfish Oocytes

Quantitative Analysis of Cortical Actin Filaments during Polar Body Formation in Starfish Oocytes

Actin polymerization and interaction with other proteins in temperature-induced gelation of sea urchin egg extracts.

Preparation and purification of polymerized actin from sea urchin egg extracts.

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