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PubMed1976

A study of protoplasmic streaming in Nitella by laser Doppler spectroscopy.

Laser light scattered from particles in the streaming protoplasm of a living cell is shifted in frequency by the Doppler effect. The spectrum of the scattered light can be measured and interpreted to infer details of the velocity distribution in the protoplasm. We have developed this approach to study the protoplasmic streaming in the fresh-water alga Nitella. Our results indicate a characteristic flow pattern to which diffusion makes a negligible contribution. No difference in the velocity of particles of different size is indicated. The streaming velocity linearly with temperature with a supraoptimal temperature of 34 degrees C, and the velocity distribution becomes narrower at high temperatures. The protoplasmic streaming can be inhibited by laser light, and this effect has been used to study the photoresponse of the algae. Using beam diameters of about 50 mum, we have shown that the inhibition is very local, becoming minimal at a displacement of about 200 mum in the upstream direction and 400 mum in the downstream direction. Prolonged exposure produces a bleached area free of chloroplasts, which is three orders of magnitude less sensitive to photoinhibition.

Chlorophyta↗
PubMed1995

Protoplasmic astrocytoma. A clinicopathologic study of 16 tumors.

UNLABELLED: Protoplasmic astrocytomas, composed of process-poor astrocytic cells and a microcystic background, are rare variants of low grade astrocytoma. Three hundred eight low grade astrocytomas over a 23-year period were reviewed. Sixteen (5.2%) were classified as pure protoplasmic astrocytoma. Patients (12 males, 4 females) ranged in age from 2.5 to 41 years (mean, 20.7 years). All patients presented with seizures and three had headaches. Duration of symptoms ranged from 7 months to 28 years (mean, 6.6 years). Nine tumors (56%) were left-sided and seven right-sided (44%). Seven (44%) occurred in the temporal lobe, six (37%) in the frontal lobe, two (13%) in the parietal lobe, and one (6%) in the thalamus. Surgery consisted of partial lobectomy with total tumor resection in nine and biopsy alone in seven. Five patients received adjuvant therapy with no apparent effect on survival. At frozen section, protoplasmic astrocytoma was most confused with fibrillary low grade astrocytoma (n = 6). Follow-up revealed 10 patients with no evidence of disease 2 to 108 months postoperatively (mean, 41 months), 5 patients were alive with disease 10 to 84 months postoperatively (mean, 56 months) and 1 patient died with disease at 36 months. Of patients with total tumor resection, eight had no evidence of disease and one died with disease. IN CONCLUSION: (1) protoplasmic astrocytomas in this study were more frequently observed in males at a younger mean age than fibrillary low grade astrocytomas as reported in literature; (2) temporal and frontal lobes were the most likely site of origin; and (3) complete excision may be beneficial, whereas adjuvant therapy appeared to have no effect on outcome.

Adolescent↗
PubMed1969

Occult endotoxin in bacterial protoplasm.

Protoplasm separated from disrupted cells of gram-negative bacteria was extracted with hot phenol-water or was precipitated with ethyl alcohol after digestion with Pronase. These methods recovered about 10 times more endotoxin than was detectable in the untreated protoplasm. Inactivation of endotoxin by protoplasm also occurred in vitro when the endotoxin was first dissociated into subunits before reaction with protoplasm. Despite this increased yield from another source, the major proportion of endotoxin was still found in the cell walls.

Animals↗
PubMed2002

Protoplasmic astrocytes in CA1 stratum radiatum occupy separate anatomical domains.

Protoplasmic astrocytes are increasingly thought to interact extensively with neuronal elements in the brain and to influence their activity. Recent reports have also begun to suggest that physiologically, and perhaps functionally, diverse forms of these cells may be present in the CNS. Our current understanding of astrocyte form and distribution is based predominantly on studies that used the astrocytic marker glial fibrillary acidic protein (GFAP) and on studies using metal-impregnation techniques. The prevalent opinion, based on studies using these methods, is that astrocytic processes overlap extensively and primarily share the underlying neuropil. However, both of these techniques have serious shortcomings for visualizing the interactions among these structurally complex cells. In the present study, intracellular injection combined with immunohistochemistry for GFAP show that GFAP delineates only approximately 15% of the total volume of the astrocyte. As a result, GFAP-based images have led to incorrect conclusions regarding the interaction of processes of neighboring astrocytes. To investigate these interactions in detail, groups of adjacent protoplasmic astrocytes in the CA1 stratum radiatum were injected with fluorescent intracellular tracers of distinctive emissive wavelengths and analyzed using three-dimensional (3D) confocal analysis and electron microscopy. Our findings show that protoplasmic astrocytes establish primarily exclusive territories. The knowledge of how the complex morphology of protoplasmic astrocytes affects their 3D relationships with other astrocytes, oligodendroglia, neurons, and vasculature of the brain should have important implications for our understanding of nervous system function.

Animals↗
PubMed1975

[Heat resistance of 2 types of protoplasmic movement in Physarum polycephalum plasmodia].

The thermostabilities of the "unordered" and shuttle protoplasmic streamings in myxomycete Physarum polycephalum plasmodia was studied. A comparison of these thermostabilities has revealed that the cessation of the former streaming occurs at temperatures higher than those required for arresting the shuttle streaming. The difference between the two types of protoplasmic streamings is better seen in the rate of repair of protoplasmic streaming halted by a 10 minutes heating at 38-41 degrees C. For example, the unordered streaming is restored 2 minutes after heating plasmodia at 39 degrees for 10 min., while the shuttle streaming is resumed in 24 minutes. It is supposed that the two protoplasmic streamings are independent to an appreciable extent, and that the shuttle streaming, being more complex and coordinated, has appeared in the evolution at later stages than the unordered one. The higher heat sensitivity of the shuttle streaming substantiates a view of the lower stability to injury in regulatory mechanisms if compared to the stability of motile mechanisms.

Acclimatization↗
PubMed1958

Rhythmicity in the protoplasmic streaming of a slime mold, Physarum polycephalum. I. A statistical analysis of the electric potential rhythm.

The electric potential difference (1 to 15 mv.) between two loci of the slime mold connected with a strand of protoplasm changes rhythmically with the same period (60 to 180 seconds) as that of the back and forth protoplasmic streaming along the strand. Generally some phase difference is observed between them. Periods of the electric potential rhythm show a Gaussian distribution. Amplitudes give a somewhat different distribution curve. Wave forms are not always simple harmonic ones, but are distorted more or less. However, auto-correlation analysis proves that there is a dominant rhythm of a nearly constant period which coincides with the mean period of the Gaussian distribution curve. Calculations made on an assumption that the electric potential rhythm is the result of many elementary rhythms (i.e., same periodicity, arbitrary phase angles) distributed throughout the plasmodium, give a satisfactory coincidence with the observed distribution for the amplitude. The predominance of a rhythm of a nearly constant periodicity suggests the existence of well organized interactions among components of a contractile protein network, the rhythmic deformation of which is supposed to be responsible for the protoplasmic streaming and for the electric potential rhythm.

Cytoplasm↗
PubMed1954

Apparent violations of the all-or-none law in relation to potassium in the protoplasm.

The protoplasm of Nitella forms a thin layer surrounding a large central vacuole filled with sap. At the inner surface of the protoplasm is a non-aqueous layer called Y and at the outer surface is a similar layer called X. At each of these layers there is a potential due to the diffusion of KCl in contact with the layer. We thus have P = P(X) + P(Y) in which P is the total potential, P(X) is the potential at X, and P(Y) the potential at Y. We assume that when stimulation occurs P(Y) disappears and P(X) remains unaltered. The loss of part of the potential therefore involves no violation of the all-or-none law since the Y layer loses all of its potential and the X layer loses nothing. If the concentration of KCl in the external solution and in the sap is known the concentration in the protoplasm can be calculated at each stimulation by measuring the height of the spike.

Cytoplasm↗
PubMed2006

Mathematical model for rhythmic protoplasmic movement in the true slime mold.

The plasmodium of the true slime mold Physarum polycephalum is a large amoeboid organism that displays "smart" behavior such as chemotaxis and the ability to solve mazes and geometrical puzzles. These amoeboid behaviors are based on the dynamics of the viscoelastic protoplasm and its biochemical rhythms. By incorporating both these aspects, we constructed a mathematical model for the dynamics of the organism as a first step towards understanding the relation between protoplasmic movement and its unusual abilities. We tested the validity of the model by comparing it with physiological observation. Our model reproduces fundamental characteristics of the spatio-temporal pattern of the rhythmic movement: (1) the antiphase oscillation between frontal tip and rear when the front is freely extending; (2) the asynchronous oscillation pattern when the front is not freely extending; and (3) the formation of protoplasmic mounds over a longer time scale. Both our model and physiological observation suggest that cell stiffness plays a primary role in plasmodial behaviors, in contrast to the conventional theory of coupled oscillator systems.

Algorithms↗
PubMed2004

Cyclooxygenase-2, Bcl-2, and chromosome 1p analysis in protoplasmic astrocytomas.

Protoplasmic astrocytomas are rare gliomas whose nosology remains enigmatic. This study retrospectively reviews the clinicopathologic features of eight tumors, including evaluation of these neoplasms for chromosome 1p loss, Bcl-2 immunoreactivity, and cyclooxygenase-2 immunoreactivity. Patients ranged in age from 3 to 49 years (median 25.5 years) and included six males and two females. All patients presented with a period of seizures (median duration of period, 54 months) before surgery. Five tumors were either totally or partially based in the temporal lobe. In the six patients for whom follow-up information was available, there was no evidence of recurrence at last known follow-up (range 5 to 171 months; median 134 months). Histologically, all tumors were marked by a proliferation of cells with rounded to oval nuclear contours and a paucity of cytoplasmic processes, arranged against a microcystic background. A rare mitotic figure was observed in only one tumor. Vascular proliferative changes and necrosis were not seen in any of the tumors. None of the tumors showed allelic loss on chromosome 1p by fluorescent in situ hybridization (FISH) analysis. Cyclooxygenase-2 (an enzyme involved in the conversion of arachidonate to prostaglandin H2 and G2) immunoreactivity was observed in two tumors. Bcl-2 (an anti-apoptotic protein) immunoreactivity was also confined to two tumors. In conclusion, protoplasmic astrocytomas appear to be low-grade neoplasms, as evidenced by their relatively benign clinical course. Although they histologically resemble microcystic oligodendrogliomas, none of the tumors showed allelic loss on chromosome 1p, a finding that has been described in the majority of low-grade oligodendrogliomas. This suggests that the protoplasmic astrocytoma is a distinct entity from low-grade oligodendroglioma. Similar to other low-grade astrocytomas, only a minority of tumors show evidence of cyclooxygenase-2 and Bcl-2 immunoreactivity.

Adult↗
PubMed1954

Photosynthesis by protoplasm extruded from Chara and Nitella.

(a) Photosynthesis with protoplasm isolated from Chara or Nitella as measured by C(14) fixation has been obtained at a rate 12 to 15 per cent of that of the whole cells. (b) Photosynthesis by cut cells of Chara or Nitella with the vacuolar sap removed was at a rate comparable to that of the whole cells. (c) Both the protoplasm and the cut cells reduced CO(2) in the light to sucrose and hexose phosphates. Other products formed were also detected by paper chromatography. In contrast, dark controls fixed the C(14) into products associated with plant respiration. (d) An important difference in the products from the extruded protoplasm was the absence of C(14)-labelled pentoses or sedoheptulose which were formed, however, by the whole or cut cells. This suggests that the most sensitive site affected by disruption of the cells may be the steps involved in the regeneration of the "C-2 acceptor" for CO(2) fixation in photosynthesis.

Chara↗
PubMed2003

Clathrin sheets on the protoplasmic surface of ventral membranes of osteoclasts in culture.

Physical cell-shearing resulted in various degrees of disruption of the basolateral (upper) membranes, cytoskeletons or cell organelles and exposed the protoplasmic surface of ventral (adhesion) membranes of osteoclasts that were attached to the underlying substratum, such as coverslips, mica or synthetic apatite plates. Freeze-dried replicas of the ventral membranes left behind on the substratum after cell-shearing provided three-dimensional information on the ultrastructure of the protoplasmic membrane surface of cultured osteoclasts. An extensive area of the protoplasmic surface and various amounts of cytoskeletal structures attached to the adherent ventral surface of the plasma membrane were visible. In particular, the most characteristic finding of the present study is that numerous clathrin sheets displaying various sizes, shapes and curvature were revealed on the ventral membrane. The polygon substructures of the clathrin lattices appeared to be composed of hexagons with a few pentagons interspersed. They were seen at the peripheral membranes where they were situated at the sites of close contact with the underlying substratum. In addition, clathrin lattices were never observed on the basolateral (upper) membranes. In favourable stereo views, most cytoskeletons were not in direct contact with the clathrin sheets. However, a few observations indicated possible remnants of cytoskeletons attached to clathrin lattices. Podosomes did not have a direct structural relationship to clathrin lattices. Although it is generally accepted that cytoskeletal podosomes in motile cells, such as osteoclasts, play a major role in cell adhesion, the present study indicates that membrane-associated clathrin might also function during attachment to the substrate. In this regard, clathrin is thought to be required for receptor-mediated endocytosis, but whether it might also function in cell attachment is still a matter for debate. This type of clathrin-related adhesion appears to be a previously unrecognized site of cell/substrate adhesion in osteoclasts. To assess this possible function, we focused on clathrin and related cytoskeletal elements on the ventral membranes of cultured osteoclasts.

Animals↗
PubMed1976

The molecular mechanism of protoplasmic incompatibility and its relationship to the formation of protoperithecia in Podospora anserina.

In Podospora anserina, protoplasmic incompatibility due to interactions between non-allelic genes was suppressed by the effect of mutations in two modifier genes, mod-I and mod-2. It is shown that mod-I and mod-2 are involved in the production of three specific proteins, a phenoloxidase and two previously identified proteases (Bégueret & Bernet 1973 a) which are associated with the phenomenon of protoplasmic disintegration. These enzymes, whose messengers are normallly latent during vegetative growth, appear at this stage of the life cycle only as a consequence of incompatible gene interactions. The mode-I and mod-2 genes and each of the five incompatibility loci involved in non-allelic incompatibility systems also participate in the formation of the protoperithecia. This pleiotropic effect suggests that protoplasmic incompatibility is a deviation in the normal physiological processes of protoperithecial formation.

Ascomycota↗
PubMed1996

MIB1 and p53 immunoreactivity in protoplasmic astrocytomas.

Pure protoplasmic astrocytomas are a group of rarely encountered low grade astrocytic neoplasms. Relatively few studies have specifically examined this subset of tumors. A series of 18 protoplasmic astrocytomas in 14 males and four females (age range 2.5-52, mean 22 years) were studied in order to examine MIB1 (a marker of cell proliferation) and p53 (a tumor suppressor gene) immunoreactivity. All patients presented with seizures (mean duration 94 months) and three with headaches also. Eight tumors were located in the temporal lobe and six in the frontal lobe. All tumors were characterized by a proliferation of astrocytes with round nuclear contours arranged against a microcystic background. Only rare foci of mild vascular proliferation (3 tumors), rare mitotic figures (1 tumor), and mild nuclear atypia (3 tumors) were observed. Most tumors were primarily cortical in location. Necrosis was not seen in any of the tumors. MIB1 indices (number of MIB1 positive tumor cells/1000 tumor cells evaluated x 100) ranged from 0 to 4.3 (mean 0.7); in five tumors, no MIB1 staining was observed. p53 immunoreactivity was noted in 5 of 18 tumors (28%). Five patients received adjuvant radiation therapy and one adjuvant chemotherapy. At last known follow-up, 11 patients are alive with no evidence of residual tumor (mean 70 months), six patients are alive with evidence of residual tumor (mean 58 months), and one patient died of complications unrelated to the tumor (36 months) postoperatively. Based on these findings, the conclusions presented are as follows: (i) MIB1 indices are generally low in these tumors, corroborating the clinical impression of a slow growing neoplasm; and (ii) p53 immunoreactivity is observed in a minority of protoplasmic astrocytomas.

Adolescent↗
PubMed1987

Light and electron microscopic localization of a cell surface antigen (NG2) in the rat cerebellum: association with smooth protoplasmic astrocytes.

Immunofluorescence and immunoperoxidase techniques were used to localize a cell surface chondroitin-sulfate proteoglycan antigen, termed NG2, in the developing and adult rat cerebellum. In the adult, both polyclonal and monoclonal anti-NG2 antibodies labeled cells throughout the cerebellar cortex, with the labeled cells being especially prominent in the molecular layer. The labeled cells had small, irregularly shaped cell bodies from which thin highly branched processes radiated in a stellate array. The NG2-labeled cells were not labeled with antibodies against glial fibrillary acidic protein (GFAP), vimentin, or S-100 protein, intracellular markers for astrocytes. However, electron microscopic immunocytochemical analysis of NG2 immunoreactive cells revealed a cell morphology consistent with that of protoplasmic astrocytes. Labeled cell bodies contained a thin rim of organelle-poor cytoplasm surrounding a euchromatic nucleus. Thick processes originating from the cell soma tapered to form thin branches with highly irregular surface contours that extended between adjacent neuronal elements. The labeled processes did not form synapses in the neuropil, and no synaptic profiles onto anti-NG2-labeled cell bodies or processes were observed. Thus, we conclude that the NG2 antigen is a cell surface marker for a class of smooth protoplasmic astrocytes. Immunoreactive cells were seen in the developing cerebellum beginning at embryonic day 16. The number of labeled cells increased during the early stages of cerebellar development, reaching a peak at about postnatal day (PND) 4 or 5 and declining thereafter. In the developing cerebellum, labeled cells lying within the forming molecular layer resembled the cells seen in the adult, whereas cells lying deeper within the folia had an immature appearance with fewer processes and less branching. This apparent gradient of morphological maturation suggests that an interaction with parallel fibers in the developing molecular layer may play a role in the terminal cytodifferentiation of the NG2-labeled smooth protoplasmic astrocytes.

Animals↗
PubMed1981

Silver staining of protoplasmic astrocytes by physical development.

The protoplasmic astrocytes adsorb complex Ag(SCN)2- ions from a 40% sodium rhodanide solution containing 1% silver nitrate. The complex is decomposed during a subsequent washing with 5% sodium carbonate, by the excess of rhodanide ions being removed from the sections. Thus, colloid AgSCN grains are made to deposit in the protoplasmic astrocytes. These grains will be reduced first to metallic silver, then enlarged to microscopic dimensions by means of a special physical developer, rendering the protoplasmic astrocytes visible. A pretreatment with 0.01% iodine dissolved in 5% potassium iodide is used to suppress the simultaneous staining of some unwanted tissue elements.

Astrocytes↗
PubMed1983

Isolation of specific peptides from Mycobacterium paratuberculosis protoplasm and their use in an enzyme-linked immunosorbent assay for the detection of paratuberculosis (Johne's disease) in cattle.

An antigen was isolated from the protoplasm of Mycobacterium paratuberculosis by a combination of gel filtration, ion exchange, and affinity chromatography. The purified antigen constituted 7.8% of the total protein in the protoplasm. The specificity and sensitivity of the enzyme-linked immunosorbent assay (ELISA) for paratuberculosis, using the purified antigen, were evaluated with sera from 104 cattle which were examined (surveyed) for M paratuberculosis infection by fecal cultural technique. The ELISA was positive in 50 of 60 infected animals. Five of 44 noninfected animals were also test-positive. When a crude protoplasmic extract was used as antigen in the ELISA, sera from 37 infected and from 18 noninfected animals were test-positive. Cross-reactions were encountered in both complement-fixation test and the ELISA between crude or partially purified M paratuberculosis antigens and antisera to Nocardia asteroides, M avium, M phlei, and M fortuitum. The purified antigen gave no complement-fixation reaction with any of these antisera. In the ELISA, cross-reaction was not found when purified antigen was used and the sera were screened at 1:40 dilution.

Animals↗
PubMed1978

The influence of microinjected phalloidin on locomotion, protoplasmic streaming and cytoplasmic organization in Amoeba proteus and Physarum polycephalum.

Microinjected phalloidin induces both time and concentration-dependent changes in morphology and motility of amoebae and acellular slime moulds. In A. proteus injection of a 10(-3)M solution of the drug causes a separation of cortical hyaline plasma from central granular plasma. Simultaneously protoplasmic streaming and cellular locomotion are lost irreversibly. Lowering the concentration of phalloidin to 2 x 10(-4)M results in a reversible disturbance; amoebae recover after 30 to 60 minutes and show normal movement. In Ph. polycephalum the injection of a 10(-3)M solution of phalloidin into single veins induces a local gelation of the protoplasm followed by the separation of hyalo- and granuloplasm. In semi-thin and ultrathin sections the hyaline plasma regions contain a fine granular groundplasm rich in ribosomes but free of cellular organelles. The central granular plasma consists mainly of membrane-surrounded cellular compartments. The two morphologically distinct plasma regions are separated by a 0.5 to 1.0 micrometer layer of filamentous material. In A. proteus the filamentous layer is found shortly after phalloidin injection in close proximity to the plasma membrane, and consists of thin 5 to 6 nm filaments. With increasing time this layer contracts, separates from the inner plasma membrane and moves to the interior of the cell. During contraction thicker filaments with diameters of 10 to 30 nm and lengths of 300 to 500 nm are formed. The results indicate that the display and contraction of the phalloidin-induced filament layer can account for the changes observed in cellular movement and cytoplasmic organization. The resulting phenomena i.e. separation of hyaline plasma from granular plasma and changes in both the protoplasmic streaming pattern and locomotory activity of the cells, are discussed in terms of a general understanding of amoeboid movement.

Amoeba↗
PubMedDate not supplied

[Mathematical model of protoplasm flow in a viscous-elastic active strand of a myxomycete plasmodium].

A mathematical model is plotted of protoplasmic flow in long strands of Myxomycete plasmodium. An analytical relationship was obtained between the characteristics of protoplasmic flow: amplitude and contour of velocity in the strand channel with the amplitude and wave length of pressure developed by contractile filaments of the strand cortical layer. The model permitted a comparison to be made between the experimental data of protoplasmic flow obtained by optical methods and the evidence on contractile apparatus obtained by tensiometric measurements. A conclusion is drawn on the consistency of the basic hypothesis concerning an autowave pattern of the motive force of the cortical layer filaments.

Elasticity↗