The Isolation of Myxomyosin, an Atp-Sensitive Protein From the Plasmodium of a Myxomycete

Ts’o, Paul O. P.; Eggman, Luther; Vinograd, Jerome

doi:10.1085/jgp.39.5.801

Cited by 60 publications

(7 citation statements)

References 12 publications

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“…He believes that this reconciles morphological findings with the physiological studies of Loewy (30). Kamiya (24,25), and Ts'o et al (68) and that the fibrils contract to produce a local pressure which is active streaming, but these were also found in some plasmodia in which streaming could not be seen.…”

Section: + + +supporting

confidence: 58%

“…In a later study, Dugas and Bath (10) mention the question of the presence of fibrils, but in discussing their electron microscopic observations on sec- tions of the plasmodium of P. polycephalum they do not refer to fibrils. Others who have studied protein extracts of the plasmodium of this same species have reported network arrangements or rigid rods (68), but Stewart and Stewart (63) could find no such structures in sections of plasmodia fixed from the living state. They suggest that, since fibril formation often occurs as a post mortem change, these fibrils might not be present in vivo.…”

Section: Contractile Component and Fibrils In Myxomycete Plasmodiamentioning

confidence: 96%

“…In 1952, Loewy (30) extracted from the proto-plasm of the plasmodium of P. polycephalum a protein that behaved like muscle myosin B, and Ts'o et al (68) later named it "myxomyosin." A contractile protein isolated from the same source by Nakajima (39) has slightly different physicochemical properties; he has called it "plasmodial myosin B."…”

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confidence: 99%

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Fibrillar Differentiation in Myxomycete Plasmodia

McManus

Roth

1965

The Journal of Cell Biology

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Myxomycete plasmodia of four different types (not including Physarum polycephalum) were studied in thin sections viewed in the electron microscope. In the cytoplasm of the protoplasmodia of Clastoderma debaryanum and the phaneroplasmodia of Fuligo septica fixed in situ, fibrillar differentiations of three rather distinct kinds were observed. One of these is filamentous and closely resembles the filaments (or "microtubules") of the mitotic apparatus of other species. The larger phaneroplasmodia of two species belonging to the Physarales and the plasmodium of Hemitrichia vesparium showed fewer and less well defined fibrils, and no fibrils were seen in the aphanoplasmodium of Stemonitis fusca. Good stabilization of such fibrils in larger plasmodia may require fixation methods more rigidly controlled than those which succeed with microscopic protoplasmodia. The function of the observed fibrils cannot yet be determined. Their presence in cytoplasm fixed in situ, however, lends support to those theories of protoplasmic movement which are dependent on integral cross-bonding of one or a few molecular species.

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Section: + + +supporting

confidence: 58%

Section: Contractile Component and Fibrils In Myxomycete Plasmodiamentioning

confidence: 96%

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Fibrillar Differentiation in Myxomycete Plasmodia

McManus

Roth

1965

The Journal of Cell Biology

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“…These fibrils have been shown histochemically to contain ATPase, the enzyme which biochemical studies of the actomyosin and myxomyosin (or plasmodial myosin B) systems would lead us to expect to find in the fibrils. Furthermore, Wohlfarth-Bottermann's electron microscopic studies have revealed filamentous structures within the microscopically observable fibrils which are apparently made up of elongated molecules similar in size to those in myxomyosin studied by Ts'o et al (25)(26)(27)(28). Thus, there are good grounds for believing that the birefringent fibrils described here are composed of "contractile pro-H1ROMICHI NAKAJI~ AND ROBERT D. ALLEN Birefringence in Plasmodia tein" similar to that of the fractions prepared from plasmodia by Ts'o et al and by Nakajima (15)(16)(17).…”

Section: Discussionmentioning

confidence: 91%

THE CHANGING PATTERN OF BIREFRINGENCE IN PLASMODIA OF THE SLIME MOLD, PHYSARUM POLYCEPHALUM

Nakajima

Allen

1965

The Journal of Cell Biology

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Plasmodia of the acellular slime mold, Physarum polycephalum, reveal a complex and changing pattern of birefringence when examined with a sensitive polarizing microscope. Positively birefringent fibrils are found throughout the ectoplasmic region of the plasmodium. In the larger strands they may be oriented parallel to the strand axis, or arranged circularly or spirally along the periphery of endoplasmic channels. Some fibrils exist for only a few minutes, others for a longer period. Some, particularly the circular fibrils, undergo changes in birefringence as they undergo cyclic deformations. In the ramifying strand region and the advancing margin there is a tendency for fibrils of various sizes to become organized into mutually orthogonal arrays. In some plasmodia the channel wall material immediately adjacent to the endoplasm has been found to be birefringent. The sign of endoplasmic birefringence is negative, and its magnitude is apparently constant over the streaming cycle. The pattern of plasmodial birefringence and its changes during the shuttle streaming cycle of Physarum are considered in the light of several models designed to explain either cytoplasmic streaming alone or the entire gamut of plasmodial motions. The results of this and other recent physical studies suggest that both streaming and the various other motions of the plasmodium may very likely be explained in terms of coordinated contractions taking place in the fibrils which are rendered visible in polarized light.

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“…There is also evidence, in slime mould at least, that the fibrils involved in streaming have aftinities with the actomyosin of muscle. Thus protein fractions have been isolated from slime moulds by various authors, and shown to have chemical and physical properties similar to muscle actin or muscle myosin (Loewy, 1952;Ts'o, Eggmann & Vinograd, 1956, 1957aNakajima, 1960;Hatano & Oosawa, 1966a, b: Hatano & Tazawa, 1968. Wohlfarth-Bottermann (1963 has shown that the slime mould fibrils have ATP-ase activity.…”

Section: B Streaming In the Slime Mould Physarum Polycephalummentioning

confidence: 99%

Facts and Mechanisms: A Comparative Survey

Macrobbie

1971

Biological Reviews

141

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Summary 1. This review aims to survey the process of translocation of solutes in the phloem, including the experimental observations of the process, hypothetical mechanisms with their consequences, and the compatibility of these mechanisms with the experimental information. 2. Some properties of the sieve elements are summarized. The characteristic constituent of the sieve elements is a fibrillar protein, P‐protein, of 60–120 A. filaments, whose function and distribution in intact sieve elements are still the subject of debate. 3. Apart from the very high levels of sucrose (0.3–0.9 m) and of specific amino acids and amides (10–100 mm), the contents of the sieve elements are characterized by close regulation of the ionic content; thus K (20–85 mM) and Mg (2.3–23 mM) are very high relative to Na (0.06–0.3 mM) and Ca (0.25–0.5 mM) respectively; the pH is also very high. 4. Convective movement (mass flow) is demanded by the very high rates of mass transfer. The longitudinal sucrose flux is about 2.5 times 106 pmoles cm.‐2 sec.‐1 in petioles, and several times higher in fruits or trees; this is about 105 times any reasonable transmembrane flux, and demands very large loading areas for each file of sieve elements. It also renders unlikely any mechanism demanding an associated trans‐membrane flux of any solute which approaches within several orders of magnitude of the sucrose flow. 5. The evidence from tracer measurements (of 14C or of heat) favour a mass flow of some kind in the sieve tube, with only restricted exchange between the flowing stream and other sucrose pools in the phloem (or out of it). It is not consistent with ready equilibration with a large stationary reservoir of sucrose, or with reverse flows. There is close correspondence between the input and output kinetics of a length of the trans‐location path, or of build‐up curves at different distances; hence lateral exchange from the moving stream is relatively minor. 6. Tracer measurements show that loading into the translocation stream is relatively slow, and is the main determining factor in the time course of appearance of tracer down the stem, or in the profile of radioactivity against distance in the stem. This applies not only to the initial steep front of radioactivity in the stem, but also to the error function profiles found at longer times in some plants; those do not arise as has been suggested, by exchange in a two‐way system of transcellular strands, but are a reflexion of the loading kinetics. 7. The evidence for or against bidirectional movement is equivocal. In conditions in which there is a strong source/sink gradient imposed, the movement of both labelled carbon and heat is consistent with a one‐way system, and is difficult to reconcile with two‐way movement. However, in the absence of any strong gradient there is evidence for bidirectional movement. It is suggested that the pattern of flow, as well as the direction and rate of flow, may be controlled by the source/sink relations along the path. 8. Electro‐osmosis as a mechanism for transl...

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The Isolation of Myxomyosin, an Atp-Sensitive Protein From the Plasmodium of a Myxomycete

Cited by 60 publications

References 12 publications

Fibrillar Differentiation in Myxomycete Plasmodia

Fibrillar Differentiation in Myxomycete Plasmodia

THE CHANGING PATTERN OF BIREFRINGENCE IN PLASMODIA OF THE SLIME MOLD, PHYSARUM POLYCEPHALUM

Facts and Mechanisms: A Comparative Survey

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