The contractile basis of ameboid movement. II. Structure and contractility of motile extracts and plasmalemma-ectoplasm ghosts.

Taylor, D. Lansing; Rhodes, James A.; Hammond, Scott A.

doi:10.1083/jcb.70.1.123

Cited by 72 publications

(86 citation statements)

References 35 publications

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“…In common with Acantharnoeba (22, 23), macrophages (28,29), leukemic cells (4), sea urchin eggs (15,16), and giant amebas (31), suitable extracts of HeLa cells can form a gel. In all cases, gelation can be related to a polymerization of actin induced by warming, but the generality of the role of the other proteins which have been isolated with gels is less well established.…”

Section: Discussionmentioning

confidence: 99%

“…The gels formed by three of these cytoplasmic extracts can shrink spontaneously (4,22,29), and the incorporation of myosin into the shrunken gels has suggested that interactions of actin and myosin induce gel shrinkage. These newer observations on gelation and shrinkage seem to be related to the older observations on consistency changes and movement of ameba extracts by the observation of a gel-like consistency for the ameba cytoplasm un-der certain conditions (31) and the apparent involvement of actin and myosin in both sorts of systems. I previously reported that suitable extracts of HeLa cells undergo a gelation reaction, which can be related to actin and a high molecular weight protein (HMWP) (34,35).…”

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confidence: 97%

“…Gel electrophoresis of gels shrunken by added myosin or electrophoresis of the proteins which can be sedimented from extract after incubation in the presence of HMM indicate that both myosin and HMM interfere with the changes in sedimentability of the high molecular weight protein (HMWP) thought to participate (together with actin) in gel formation in HeLa cell extracts (R. R. It has been recognized since 1960 that the cytoplasm of giant amebas can carry out lifelike movements after release from the cell (2). Since that time, studies on fractionation and ultrastructure of the cytoplasm and on the Ca ++ and ATP requirements for movement and consistency changes (24,30,31,32) have shown that rapid changes in the organization and interactions of actin and myosin most likely provide the molecular machinery for these changes. Recently, the studies on control of movement and consistency change by Ca ++ and ATP have been extended to cultured mammalian cells (14).…”

mentioning

confidence: 99%

“…Since that time, studies on fractionation and ultrastructure of the cytoplasm and on the Ca ++ and ATP requirements for movement and consistency changes (24,30,31,32) have shown that rapid changes in the organization and interactions of actin and myosin most likely provide the molecular machinery for these changes. Recently, the studies on control of movement and consistency change by Ca ++ and ATP have been extended to cultured mammalian cells (14).…”

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Effects of myosin and heavy meromyosin on actin-related gelation of HeLa cell extracts.

Weihing¹

1977

The Journal of Cell Biology

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The gelation induced by warming (to 25~ the 100,000 g supernatant fraction (extract) of HeLa cells lysed in a buffer containing sucrose, ATP, DTE, EGTA, imidazole, and Triton X-100 was studied in the presence of myosin and heavy meromyosin (HMM). Myosin mixed with extract induces shrinkage of the gel, but jelled extract or myosin alone does not shrink. In the concentration range, 0.14-1.04 mg/ml of myosin, the degree of shrinkage is roughly proportional to the concentration of myosin. Supplemental MgClz also promotes shrinkage. HMM (0.4-0.8 mg/ml) can inhibit gel formation by extract in tubes or floated on a sucrose cushion. Gel electrophoresis of gels shrunken by added myosin or electrophoresis of the proteins which can be sedimented from extract after incubation in the presence of HMM indicate that both myosin and HMM interfere with the changes in sedimentability of the high molecular weight protein (HMWP) thought to participate (together with actin) in gel formation in HeLa cell extracts (R. R. It has been recognized since 1960 that the cytoplasm of giant amebas can carry out lifelike movements after release from the cell (2). Since that time, studies on fractionation and ultrastructure of the cytoplasm and on the Ca ++ and ATP requirements for movement and consistency changes (24,30,31,32) have shown that rapid changes in the organization and interactions of actin and myosin most likely provide the molecular machinery for these changes. Recently, the studies on control of movement and consistency change by Ca ++ and ATP have been extended to cultured mammalian cells (14).The ability of cytoplasmic extracts to jell was recognized more recently, and it has been related to actin (22), actin and a high molecular weight actin-binding protein (4,29,34,35), actin and two other proteins (15, 16), or actin and several low molecular weight proteins (20). The gels formed by three of these cytoplasmic extracts can shrink spontaneously (4,22,29), and the incorporation of myosin into the shrunken gels has suggested that interactions of actin and myosin induce gel shrinkage. These newer observations on gelation and shrinkage seem to be related to the older observations on consistency changes and movement of ameba extracts by the observation of a gel-like consistency for the ameba cytoplasm unThE JOURNAL OF CELL BIOLOGY 9 VOLUME 75, 1977 9 pages 95-103 95 on

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 97%

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confidence: 99%

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Effects of myosin and heavy meromyosin on actin-related gelation of HeLa cell extracts.

Weihing¹

1977

The Journal of Cell Biology

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“…Motile extracts of these cells exhibit viscosity changes in vitro (23,33,35,37) and have been used to advantage in studying structural transformations at a molecular level. Experimental evidence linking consistency changes in vitro with the assembly and interaction of contractile protein filaments (11,23,24,33,34) has suggested that the J. CELL BIOLOGY 9 The Rockefeller University Press 9 0021-9525/78…”

Section: Abstract Actin Gelation Contraction Calciummentioning

confidence: 99%

Actin in Xenopus oocytes

Clark¹,

Merriam²

1978

The Journal of Cell Biology

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It has been found that a high-speed supernatant fraction from Xenopus oocytes extracted in the cold will form a clear, solid gel upon warming. Gel formation occurs within 60 min at 18~176and is, at least initially, temperature reversible. Gelation is strictly dependent upon the addition of sucrose to the extraction medium. When isolated in the presence of ATP, the gel consists principally of a 43,000-dalton protein which co-migrates with Xenopus skeletal muscle actin on SDS-polyacrylamide gels, and a prominent high molecular weight component of approx. 250,000 daltons. At least two minor components of intermediate molecular weight are also found associated with the gel in variable quantities. Actin has been identified as the major constituent of the gel by ultrastructural and immunological techniques, and comprises roughly 47% of protein in the complex. With time, the gel spontaneously contracts to form a small dense aggregate. Contraction requires ATP. In the absence of exogenous ATP, a polypeptide which co-migrates with the heavy chain of Xenopus skeletal muscle myosin becomes a prominent component of the gel. This polypeptide is virtually absent from gels which have contracted in ATPocontaining extracts. It has also been found that Ca ++ is required for gelation in oocyte extracts. At both low and high concentrations of Ca ++ (defined as a ratio of Ca++/EGTA in the extraction medium), gelation is inhibited. KEY WORDS actin gelation contraction calciumXenopus 9 oocytes Variations in cytoplasmic consistency often accompany important cellular events. For example, during fertilization and cleavage, eggs of several marine invertebrates undergo distinct changes in consistency (9). Similarly, consistency changes are known to occur during the hormonally induced meiotic maturation of amphibian oocytes (21). Our interest in oocyte maturation in Xenopus laevis has led us to seek a molecular and functional understanding of these cytoplasmic changes.The dynamic structural properties of the cytoplasm are evident in a number of other cell types, as well. In particular, amoebae and slime molds undergo reversible sol-gel transformations in localized regions of the cytoplasm during movement (for review, see references 1 and 14). Motile extracts of these cells exhibit viscosity changes in vitro (23,33,35,37) and have been used to advantage in studying structural transformations at a molecular level. Experimental evidence linking consistency changes in vitro with the assembly and interaction of contractile protein filaments (11,23,24,33,34) has suggested that the J. CELL BIOLOGY 9 The Rockefeller University Press 9 0021-9525/78

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Cell mechanics and stress: from molecular details to the ‘universal cell reaction’ and hormesis

Agutter¹

2007

BioEssays

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The 'universal cell reaction' (UCR), a coordinated biphasic response to external (noxious and other) stimuli observed in all living cells, was described by Nasonov and his colleagues in the mid-20th century. This work has received no attention from cell biologists in the West, but the UCR merits serious consideration. Although it is non-specific, it is likely to be underpinned by precise mechanisms and, if these mechanisms were characterized and their relationship to the UCR elucidated, then our understanding of the integration of cellular function could be improved. As a step towards identifying such mechanisms, I review some recent advances in understanding cell mechanics and the stress response and I suggest potentially testable hypotheses. There is a particular need for time-course studies of cellular responses to different stimulus doses or intensities. I also suggest a correspondence with hormesis; re-investigation of the UCR using modern biophysical and molecular-biological techniques might throw light on this much-discussed phenomenon.

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The contractile basis of ameboid movement. II. Structure and contractility of motile extracts and plasmalemma-ectoplasm ghosts.

Cited by 72 publications

References 35 publications

Effects of myosin and heavy meromyosin on actin-related gelation of HeLa cell extracts.

Effects of myosin and heavy meromyosin on actin-related gelation of HeLa cell extracts.

Actin in Xenopus oocytes

Cell mechanics and stress: from molecular details to the ‘universal cell reaction’ and hormesis

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