Identification of a birefringent structure which appears and disappears in accordance with the shuttle streaming inPhysarum plasmodia

PROTOPLASMA ◽  
1979 ◽  
Vol 100 (2) ◽  
pp. 167-177 ◽  
Author(s):  
S. Ogihara ◽  
K. Kuroda
Keyword(s):  
Shuttle Streaming

Plasmalemma Invaginations as Characteristic Constituents of Plasmodia of Physarum Polycephalum

1974 ◽  
Vol 16 (1) ◽  
pp. 23-37
Author(s):  
K. E. WOHLFARTH-BOTTERMANN
Keyword(s):  
Physarum Polycephalum ◽  
Close Contact ◽  
Surrounding Medium ◽  
Defined Medium ◽  
Subsequent Paper ◽  
Outer Border ◽  
Shuttle Streaming ◽  
Food Absorption ◽  
Plasmalemma Invaginations

Plasmodia of Physarum polycephalum grown on agar or filter paper and fed with rolled oats as food or with a partially defined medium were morphologically analysed in the living state and after fixation. Observation of the living plasmodium growing on agar reveals plasmalemma indentations in the outer regions of protoplasmic strands, which were studied in more detail by phase-contrast microscopy of unstained 1-µm sections. Plasmodia fixed and embedded in situ, i.e. in close contact to their substrate, exhibit an extensive system of plasmalemma invaginations as characteristic constituents throughout all regions. In plasmodial strands measuring between 40 µm and 1.5 mm in diameter and involved in shuttle streaming, the plasmalemma invaginations are found within the outer ectoplasmic wall. Rounded-up parts of this branched extracellular labyrinth limit the endoplasmic core engaged in the mass transport of protoplasm by shuttle streaming. Despite this clearcut borderline, the central endoplasmic core and the ectoplasmic cortex are connected by occasional protoplasmic bridges. The extracellular phase within the ectoplasmic regions of the strands can be interpreted either as a result of plasmalemma invaginations from the outer border of the strand, or as a consequence of pseudopodial-like processes originating from the central core and extending into the surrounding medium. The invagination system provides an extensive enlargement of the surface area within the multinucleate protoplasmic mass, probably important for food absorption, excretion processes and motility phenomena. In thick protoplasmic strands with diameters between 0.2 and 1.5 mm, there is an intimate connexion between the actomyosin fibrils and the invagination system. The fibrils are attached to the plasmalemma invaginations and/or run parallel to the invaginated plasmalemma sheets. The close relations between the invagination system and actomyosin fibrils will be described in detail in a subsequent paper.

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

1965 ◽  
Vol 25 (2) ◽  
pp. 361-374 ◽  
Author(s):  
Hiromichi Nakajima ◽  
Robert D. Allen
Keyword(s):  
Physarum Polycephalum ◽  
Cytoplasmic Streaming ◽  
Channel Wall ◽  
Polarized Light ◽  
Orthogonal Arrays ◽  
Slime Mold ◽  
Wall Material ◽  
Shuttle Streaming ◽  
Oriented Parallel ◽  
Birefringent Fibrils

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.

scholarly journals Periodic traction in migrating large amoeba of Physarum polycephalum

2015 ◽  
Vol 12 (106) ◽  
pp. 20150099 ◽  
Author(s):  
Jean-Paul Rieu ◽  
Hélène Delanoë-Ayari ◽  
Seiji Takagi ◽  
Yoshimi Tanaka ◽  
Toshiyuki Nakagaki
Keyword(s):  
Physarum Polycephalum ◽  
Traction Force ◽  
Cortical Layer ◽  
Force Distribution ◽  
Locomotory Activity ◽  
Multinucleated Cell ◽  
Force Microscopy ◽  
Giant Multinucleated Cell ◽  
Shuttle Streaming

The slime mould Physarum polycephalum is a giant multinucleated cell exhibiting well-known Ca 2+ -dependent actomyosin contractions of its vein network driving the so-called cytoplasmic shuttle streaming. Its actomyosin network forms both a filamentous cortical layer and large fibrils. In order to understand the role of each structure in the locomotory activity, we performed birefringence observations and traction force microscopy on excised fragments of Physarum . After several hours, these microplasmodia adopt three main morphologies: flat motile amoeba, chain types with round contractile heads connected by tubes and motile hybrid types. Each type exhibits oscillations with a period of about 1.5 min of cell area, traction forces and fibril activity (retardance) when fibrils are present. The amoeboid types show only peripheral forces while the chain types present a never-reported force pattern with contractile rings far from the cell boundary under the spherical heads. Forces are mostly transmitted where the actomyosin cortical layer anchors to the substratum, but fibrils maintain highly invaginated structures and contribute to forces by increasing the length of the anchorage line. Microplasmodia are motile only when there is an asymmetry in the shape and/or the force distribution.

Relation of cytoplasmic calcium to contractility in Physarum polycephalum

1982 ◽  
Vol 53 (1) ◽  
pp. 37-48 ◽  
Author(s):  
R. Kuroda ◽  
H. Kuroda
Keyword(s):  
Electron Microscopy ◽  
Physarum Polycephalum ◽  
Motive Force ◽  
Cytoplasmic Calcium ◽  
Shuttle Streaming ◽  
The Asymmetry ◽  
Plasmodium Of Physarum Polycephalum ◽  
Potassium Pyroantimonate ◽  
Cellular Organelles

In a dumbbell-shaped plasmodium of Physarum polycephalum showing active shuttle streaming Ca was precipitated with potassium pyroantimonate (K[Sb(OH)6]), and the distribution of Ca between the cytoplasm and cellular organelles, especially vacuoles, was examined by electron microscopy. The contracting half-mass, where many empty vacuoles were present, was rich in the small Ca precipitates located in the cytoplasm. The relaxing half-mass, where many Ca-containing vacuoles were present, was poor in the cytoplasmic Ca precipitates. One half-mass of a dumbbell-shaped plasmodium was treated with Ca ionophore, X-537A, and its effect on the motive force for endoplasmic streaming and the distribution of Ca was investigated. The motive force was increased by X-537A, but the period of shuttle streaming was not changed. X-537A also induced a significant increase in the number of the cytoplasmic Ca precipitates in the X-537A-treated contracting half-mass, so that the asymmetry of the distribution of cytoplasmic Ca precipitates was enhanced. A large portion of the vacuoles were empty in the contracting half-mass, and Ca-containing in the relaxing one as in the case of the untreated plasmodium.

Synchrony in the rhythm of the contraction-relaxation cycle in two plasmodial strands of Physarum polycephalum

1977 ◽  
Vol 26 (1) ◽  
pp. 151-160
Author(s):  
Y. Takeuchi ◽  
M. Yoneda
Keyword(s):  
Control System ◽  
Physarum Polycephalum ◽  
Isometric Tension ◽  
Entire Body ◽  
Periodic Activity ◽  
Relaxation Cycle ◽  
Shuttle Streaming

Rhythmicity of contraction of plasmodial strands of Physarum polycephalum was studied, by measuring the isometric tension exerted by isolated segments of the strands. When 2 strands were connected by way of a plasmodial mass, the contraction-relaxation cycle of the 2 strands synchronized. Such cycle activity of the strand was found to be well coordinated with shuttle streaming in the plasmodial mass which had been in connection with the strand. The presence of a control system which induces synchrony of periodic activity over the entire body of a plasmodium is discussed.

scholarly journals Ca++ regulation in caffeine-derived microplasmodia of Physarum polycephalum.

1977 ◽  
Vol 72 (2) ◽  
pp. 502-505 ◽  
Author(s):  
L M Matthews
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Physarum Polycephalum ◽  
Storage System ◽  
Shuttle Streaming ◽  
Intracellular Storage

Caffeine-derived microplasmodia possess a Ca++-sequestering system which can initiate motility. The experiments presented here suggest that this system is membranous and nonmitochondrial in nature. Therefore, it is proposed that the shuttle streaming in the plasmodium is controlled by the localized release and uptake of free Ca++ from an intracellular storage system analogous to the sarcoplasmic reticulum.

Shuttle-Streaming: Synchronization with Heat Production in Slime Mold

Science ◽  
1963 ◽  
Vol 142 (3598) ◽  
pp. 1485-1487 ◽  
Author(s):  
R. D. Allen ◽  
W. R. Pitts ◽  
D. Speir ◽  
J. Brault
Keyword(s):  
Heat Production ◽  
Slime Mold ◽  
Shuttle Streaming
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