| the contractile basis of ameboid movement. ii. structure and contractility of motile extracts and plasmalemma-ectoplasm ghosts. | the role of calcium and magnesium-atp on the structure and contractility in motile extracts of amoeba proteus and plasmalemma-ectoplasm "ghosts" of chaos carolinensis has been investigated by correlating light and electron microscope observations with turbidity and birefringence measurements. the extract is nonmotile and contains very few f-actin filaments and myosin aggregates when prepared in the presence of both low calcium ion and atp concentrations at an ionic strength of i = 0.05, ph 6.8. ... | 1976 | 6480 |
| the self-assembly of synthetic filaments of myosin isolated from chaos carolinensis and amoeba proteus. | synthetic myosin thick filaments were formed from preparations of electrophoretically homogeneous myosin isolated from chaos carolinensis and amoeba proteus when dialysed to physiological ionic strength and ph. myosin dialysed directly against low ionic strength buffers formed native-like thick filaments in the presence and absence of exogenous divalent cations. the average dimensions of the synthetic filaments grown under these conditions were 455 nm long and 16 nm wide with a distinct bare cen ... | 1977 | 19485 |
| n-ethylmaleimide-modified heavy meromyosin. a probe for actomyosin interactions. | treatment of rabbit skeletal muscle heavy meromyosin (hmm) with the sulfhydryl reagent n-ethylmaleimide (nem) produces a species of hmm which remains tightly bound to actin in the presence of mgatp. nem-hmm forms characteristic "arrowhead" complexes with actin which persist despite rinses with mgatp. nem-hmm inhibits the actin activation of native hmm-atpase activity, the superprecipitation of actomyosin, the contraction of glycerinated muscle myofibrils, and the contraction of cytoplasmic stran ... | 1979 | 158029 |
| molecular cytochemistry: incorporation of fluorescently labeled actin into living cells. | actin labeled with 5-iodoacetamidofluorescein has been incorporated into the functional pool of actin in chaos carolinensis and physarum polycephalum by direct microinjection. the functional activity of the labeled actin has been analyzed at three levels of organization as: (a) with the purified actin, (b) in motile extracts of cells, and (c) in living motile cells. the labeled actin exhibited normal polymerization and activated myosin atpase to a similar extent as unlabeled controls. labeled ac ... | 1978 | 345279 |
| crystalloid configuration in the adrenal cortex of the siamese tree shrew (tupaia glis). | crystalloids of what appear to be smooth reticulum have been observed in the zona fasciculata and zona reticularis in both the stressed and nonstressed adrenal gland of the siamese tree shrew (tupaia glis). no crystalloids are observed in the zona glomerulosa. similar crystalloids have been described in other steroid-secreting organs, including the antebrachial organ of the lemur (lemur catta), the parotoid gland of bufo alvarius and in sebaceous gland cells of the galagos and macaques. moreover ... | 1976 | 820215 |
| the isolation of microquantities of myosin from amoeba proteus and chaos carolinensis. | | 1977 | 851213 |
| microfilaments in chaos carolinensis. membrane association, distribution, and heavy meromyosin binding in the glycerinated cell. | | 1973 | 4125372 |
| the protein amino acid compositions of amoeba proteus, a. discoides, a. dubia and pelomyxa carolinensis. | | 1970 | 5449237 |
| the free amino acid levels of pelomyxa carolinensis, amoeba dubia and proteus. | | 1968 | 5643469 |
| acidification of phagosomes is initiated before lysosomal enzyme activity is detected. | we have measured changes of ph in a protein's microenvironment consequent on its binding to the cell surface and incorporation into pinosomes. changes of ph were measured from single, living cells and selected regions of cells by the fluorescence ratio technique using a photon-counting microspectrofluorimeter. the chemotactic agent and pinocytosis inducer, ribonuclease, labeled with fluorescein (ftc-rnase), adsorbed to the surface of amoeba proteus, and was pinocytosed by cells in culture media ... | 1983 | 6885916 |
| contractile basis of ameboid movement. vii. the distribution of fluorescently labeled actin in living amebas. | the technique of molecular cytochemistry has been used to follow the distribution of fluorescently labeled actin in living chaos carolinensis and amoeba proteus during ameboid movement and various cellular processes. the distribution of 5-iodoacetamidofluorescein-labeled actin was compared with that of lissamine rhodamine b sulfonyl chloride-labeled ovalbumin microinjected into the same cell and recorded with an image intensification microscope system. actively motile cells demonstrated a rather ... | 1980 | 6893200 |
| ph changes in pinosomes and phagosomes in the ameba, chaos carolinensis. | changes in ph are measured in pinosomes and phagosomes of single specimens of the giant, free-living ameba, chaos carolinensis. measurements of ph are made microfluorometrically, as previously described (heiple and taylor. 1980. j. cell biol. 86:885-890.) by quantitation of fluorescence intensity ratios (ex489nm,/ex452nm, em520-560nm from ingested fluorescein thiocarbamyl (ftc)-ovalbumin. after 1 h of pinocytosis (induced in acid solution), ftc-ovalbumin is found in predominantly small ( less th ... | 1982 | 7119011 |
| intracellular ph in single motile cells. | cytoplasmic ph in single living specimens of chaos carolinensis is determined microfluorometrically by measuring the ratio of fluorescence intensity of microinjected fluorescein-thiocarbamyl (ftc)-ovalbumin at two different excitation wavelengths. the probe is evenly distributed throughout, and confined to, the cytoplasm, and the fluorescence intensity ratio depends only upon ph. it is independent of pathlength, concentration of probe, divalent cations, and ionic strength. ratios are calibrated ... | 1980 | 7410485 |
| signal-mediated nuclear transport in the amoeba. | the evolutionary changes that occur in signal-mediated nuclear transport would be expected to reflect an increasing need to regulate nucleocytoplasmic exchanges as the complexity of organisms increases. this could involve changes in both the composition and structure of the pore complex, as well as the cytosolic factors that mediate transport. in this regard, we investigated the transport process in amoebae (amoeba proteus and chaos carolinensis), primitive cells that would be expected to have l ... | 1999 | 10341221 |
| ssu rrna-based phylogenetic position of the genera amoeba and chaos (lobosea, gymnamoebia): the origin of gymnamoebae revisited. | naked lobose amoebae (gymnamoebae) are among the most abundant group of protists present in all aquatic and terrestrial biotopes. yet, because of lack of informative morphological characters, the origin and evolutionary history of gymnamoebae are poorly known. the first molecular studies revealed multiple origins for the amoeboid lineages and an extraordinary diversity of amoebae species. molecular data, however, exist only for a few species of the numerous taxa belonging to this group. here, we ... | 2001 | 11719580 |
| mitochondria. ii. the nuclear-mitochondrial relationship in pelomyxa carolinensis wilson (chaos chaos l.). | this study has demonstrated that in the ameba, pelomyxa carolinensis wilson (chaos chaos l.) the limiting membranes of mitochondria and postdivision nuclei are often continuous. the morphological relationship may be functional in that it permits an exchange of material resulting directly or indirectly in an increased enzyme content of the mitochondria. it is suggested that through a series of progressive foldings of its envelope, the nucleus may be a site of formation of mitochondria. | 1959 | 13673053 |
| limits of transplantation tolerance in large amoebae. i. microfusion studies using amoeba proteus, pelomyxa illinoisensis, and three strains of pelomyxa carolinensis. | | 1962 | 13883405 |
| electron microscopy of mitosis in a radiosensitive giant amoeba. | various aspects of the ultrastructure of the dividing nuclei in the large radiosensitive amoeba pelomyxa illinoisensis are demonstrated. evidence of nuclear envelope breakdown is presented, and membrane fragments are traced throughout metaphase to envelope reconstruction in anaphase and telophase. annuli in the nuclear envelope and its fragments are shown throughout mitosis. during metaphase and anaphase some 15 to 20 mitochondria are aligned at each end of the spindle, and are called polar mito ... | 1964 | 14105218 |
| i. the relation between attachment to the substratum and ingestion by ameba in strychnine sulfate solution and conditioned media : ii. biological assay of conditioned media. | 1. strychnine sulfate 0.000069 m decreased percentage attachment to the substratum by amoeba proteus in 0.0029 m nacl from 77.3 to 1.3, in 0.0029 m kcl from 40.8 to 2.5, in 0.002 m cacl(2) from 73.3 to 68.0, in 0.002 m mgcl(2) from 85.5 to 83.3. 2. frequency of ingestion of chilomonads by amoeba proteus is increased by adding strychnine sulfate to solutions of nacl, kcl, or cacl(2). frequency of ingestion is increased in nacl solution from 1.3 to 2.3, in kcl from 0.75 to 2.25, and in cacl(2) fro ... | 1944 | 19873390 |
| weightlessness experiments on biosatellite ii. | four experiments in the aft compartment of biosatellite ii investigated the broad question of the effect of nearly zero gravity on the development, morphology and metabolism of plants and animals. the fertilization and development of the egg of a vertebrate (the frog, rana pipiens), the feeding and growth of a protozoan (the giant amoeba, pelomyxa carolinensis), the orientation of leaves and petioles of a young dicotyledon (pepper plants, capsicum annuum) and the morphogenesis, orientation, hist ... | 1969 | 11949691 |
| the three dimensionality of cell membranes: lamellar to cubic membrane transition as investigated by electron microscopy. | biological membranes are generally perceived as phospholipid bilayer structures that delineate in a lamellar form the cell surface and intracellular organelles. however, much more complex and highly convoluted membrane organizations are ubiquitously present in many cell types under certain types of stress, states of disease, or in the course of viral infections. their occurrence under pathological conditions make such three-dimensionally (3d) folded and highly ordered membranes attractive biomar ... | 2012 | 22325609 |
| cubic membrane formation supports cell survival of amoeba chaos under starvation-induced stress. | cubic membranes (cm) are highly organized membrane structures found in biological systems. they are mathematically well defined and reveal a three-dimensional nano-periodic structure with cubic symmetry. these membrane arrangements are frequently induced in cells under stress, disease conditions, or upon viral infection. in this study, we investigated cm formation in the mitochondria of amoeba chaos carolinense and observed a striking correlation between the organism's ability to generate cm and ... | 2017 | 28914376 |
| evaluation of radical scavenging system in amoeba chaos carolinense during nutrient deprivation. | the frequent appearance of non-lamellar membrane arrangements such as cubic membranes (cms) in cells under stressed or pathological conditions points to an intrinsic cellular response mechanism. cm represents highly curved, three-dimensional nano-periodic structures that correspond to mathematically well-defined triply periodic minimal surfaces. specifically, cellular membrane may transform into cm organization in response to pathological, inflammatory and oxidative stress conditions. cm organiz ... | 2017 | 28630667 |
| evolution of cubic membranes as antioxidant defence system. | possibly the best-characterized cubic membrane transition has been observed in the mitochondrial inner membranes of free-living giant amoeba (chaos carolinense). in this ancient organism, the cells are able to survive in extreme environments such as lack of food, thermal and osmolarity fluctuations and high levels of reactive oxygen species. their mitochondrial inner membranes undergo rapid changes in three-dimensional organization upon food depletion, providing a valuable model to study this su ... | 2015 | 26464785 |
| isolation of mitochondria with cubic membrane morphology reveals specific ionic requirements for the preservation of membrane structure. | biological membranes with cubic symmetry are a hallmark of virus-infected or diseased cells. the mechanisms of formation and specific cellular functions of cubic membranes, however, are unclear. the best-documented cubic membrane formation occurs in the free-living giant amoeba chaos carolinense. in that system, mitochondrial inner membranes undergo a reversible structural change from tubular to cubic membrane organization upon starvation of the organism. as a prerequisite to further analyze the ... | 2015 | 25226828 |
| cubic membranes: a structure-based design for dna uptake. | cubic membranes are soft three-dimensional crystals found within cell organelles in a variety of living systems, despite the aphorism of fedorov: 'crystallization is death'. they consist of multi-bilayer lipid-protein stacks, folded onto anticlastic surfaces that resemble triply periodic minimal surfaces, forming highly swollen crystalline sponges. although cubic membranes have been observed in numerous cell types and under different pathophysiological conditions, knowledge about the formation a ... | 2008 | 18270148 |
| fasting induces cyanide-resistant respiration and oxidative stress in the amoeba chaos carolinensis: implications for the cubic structural transition in mitochondrial membranes. | large free-living amoeba (chaos carolinensis) can survive in spring water without food intake for several weeks. starvation is associated with a dramatic change in mitochondrial cristae from random tubular to ordered (paracrystalline) cubic morphology. whole-cell polarography was used to monitor changes in respiratory activity during fasting. basal respiration per cell decreased progressively during starvation, while the cyanide-resistant fraction increased. spectrofluorometric assay of h2o2 and ... | 2002 | 12099216 |
| cubic membrane structure in amoeba (chaos carolinensis) mitochondria determined by electron microscopic tomography. | cubic membranes occur in a variety of membrane-bound organelles in many cell types. by transmission electron microscopy (tem) these membrane systems appear to consist of highly curved periodic surfaces that fit mathematical models analogous to those used to describe lipidic cubic phases. for the first time, a naturally occurring cubic membrane system has been reconstructed in three dimensions by electron microscopic tomography, and its periodicity directly characterized. double-tilt tomographic ... | 1999 | 10544048 |
| some effects of chemical irritants on the membrane of the giant amoeba. | 1 the effects of chemical irritants on the membrane potential and input resistance of the giant amoeba, chaos carolinense, have been investigated. the membrane potential and input resistance were -111.5 mv and 8.6 m pi respectively. 2 in the resting state the cell membrane of chaos carolinense was found to be impermeable to na+ but permeable to k+. the distribution of k+ across the cell membrane conformed to a donnan equilibrium with the resting membrane potential being the k+ equilibrium potent ... | 1981 | 6797494 |
| structural responses of amoebae to the injection of heterologous cytoplasm. | responses to the introduction of heterologous cytoplasm and the fate of foreign organelles were investigated in amoebae. heterologous cytoplasm was transferred by microinjection from pelomyxa carolinensis to amoeba discoides. in control experiments, homologous cytoplasm was transferred from one a. discoides to another. recipient cells were observed by light microscopy, and samples were prepared for ultrastructural study at intervals between 15 min nad 3 days after operation. recipients of hetero ... | 1980 | 7462341 |
| contractile basis of ameboid movement. vii. aequorin luminescence during ameboid movement, endocytosis, and capping. | aequorin luminescence has been utilized to determine the spatial and temporal fluctuations of the free calcium ion concentration [ca++] in chaos carolinensis during ameboid movement, pinocytosis, and capping. the [ca++] increases above approximately 10(-7) m during normal ameboid movement. three types of luminescent signals are detected in cells: continuous luminescence, spontaneous pulses, and stimulated pulses. continuous luminescence is localized in the tails of actively motile cells, and spo ... | 1980 | 6893201 |
| cytoplasmic free calcium and amoeboid movement. | measurements with the ca2+ -sensitive photoprotein aequorin show that locomotion in the amoeba chaos carolinense occurs without changes in the aequorin signal and that not more than 0.025% of the cytoplasm can exist at the micromolar threshold concentration for contraction. the results do not support the hypothesis that cytoplasmic streaming is under the control of changes in the cytoplasmic free ca2+ concentration. | 1980 | 6772956 |
| capacity of enucleated amoebae to recognize and respond to heterologous cytoplasm. | when amoebae are injected with heterologous cytoplasm from another type of amoeba, cellular organelles are segregated and degenerate within membrane-bounded spaces in the host's cytoplasm. in the present study, the role of the nucleus in this response was tested by injecting heterologous cytoplasm from pelomyxa carolinensis into enucleate and enucleate amoeba discoides. samples were prepared for ultrastructural study at intervals between 15 min and 2d after the operation. in enucleate recipients ... | 1980 | 7407845 |
| a continuum theory of allen's frontal contraction model of amoeboid pseudopodium extension. | a continuum theory is proposed for the chemically controlled cytoplasmic streaming observed in pseudopodium extension in chaos carolinensis. amoeboid cytoplasm is assumed to consist of submicroscopic contractile fibers bathed by viscous fluid. the fiber constituent models the actin-like and myosin-like contractile machinery known to be present in chaos carolinensis cytoplasm. a "trigger chemical", produced at the pseudopodium tip, moves by diffusion in, and convection by, the viscous fluid, and ... | 1977 | 753896 |
| effects of high gravity on amoebae, ii. organelle distribution and division inhibition in pelomyxa carolinensis. | | 1975 | 1120503 |
| low frequency electric field induced changes in the shape and motility of amoebas. | perpendicular and parallel elongation of the giant amoeba, chaos chaos (chaos carolinensis), have been observed in alternating electric fields over a wide frequency range (from about 1 hertz to about 10 megahertz). the characteristics change as a function of frequency. simple dielectric forces may be important in the production of these effects. | 1975 | 1111109 |
| effects of high gravity on amoebae (pelomyxa carolinensis). i. division rates. | | 1974 | 4847656 |
| the contractile basis of amoeboid movement. i. the chemical control of motility in isolated cytoplasm. | cytoplasm has been isolated from single amoeba (chaos carolinensis) in physiological solutions similar to rigor, contraction, and relaxation solutions designed to control the contractile state of vertebrate striated muscle. contractions of the isolated cytoplasm are elicited by free calcium ion concentrations above ca. 7.0 x 10(-7) m. amoeba cytoplasmic contractility has been cycled repeatedly through stabilized (rigor), contracted, and relaxed states by manipulating the exogenous free calcium a ... | 1973 | 4805006 |
| pattern of birefringence in the giant amoeba, chaos carolinensis. | | 1972 | 4337146 |
| nucleopores of the giant amoeba, pelomyxa carolinensis. | | 1969 | 4900454 |
| contractile vacuole in the amoeba pelomyxa carolinensis. | | 1968 | 5671014 |
| electron microscopy of mitosis in amebae. 3. cold and urea treatments: a basis for tests of direct effects of mitotic inhibitors on microtubule formation. | the mitotic apparatus (ma) of the giant ameba, chaos carolinensis, has characteristic sequences of microtubule arrays and deployment of nuclear envelope fragments. if mitotic organisms are subjected to 2 degrees c for 5 min, the ma microtubules are completely degraded, and the envelope fragments are released from the chromosomes which remain condensed but lose their metaphase-plate orientation. on warming, microtubules reform but show partial loss of their parallel alignment; displacement of the ... | 1967 | 6040537 |
| extension of the distribution of the giant amoeba, pelomyxa carolinensis. anl-7409. | | 1967 | 5308235 |
| cyclic birefringence changes in pseudopods of chaos carolinensis revealing the localization of the motive force in pseudopod extension. | | 1965 | 5219823 |
| an electron microscopic study of pinocytosis in ameba. ii. the cytoplasmic uptake phase. | this report is devoted principally to a consideration of the fate of the pinocytotic vacuole and its content in the ameba pelomyxa carolinensis (chaos chaos). high resolution micrographs of the plasmalemma have shown it to consist of three layers, i.e., an outermost filamentiferous zone, a middle homogeneous zone, and an inner zone which appears to be a unit membrane. the three zones can be identified in the membranes lining the pinoyctotic tunnels and vacuoles of amebas fixed shortly after pino ... | 1962 | 14014970 |
| two methods for determining the water content of the giant amoeba pelomyxa carolinensis. | | 1962 | 14492103 |
| electron microscopic studies of mitosis in amebae. ii. the giant ameba pelomyxa carolinensis. | dividing nuclei from the giant ameba pelomyxa carolinensis were fixed in osmium tetroxide solutions buffered with veronal acetate to ph 8.0. if divalent cations (0.002 m calcium, magnesium, or strontium as chlorides) were added to the fixation solution, fibrils that are 14 mmicro in diameter and have a dense cortex are observed in the spindle. if the divalent ions were omitted, oriented particles of smaller size are present and fibrils are not obvious. the stages of mitosis were observed and spi ... | 1962 | 14494393 |
| an electron microscopic study of pinocytosis in ameba : i. the surface attachment phase. | the attachment to the surface of the ameba (chaos chaos l. (pelomyxa carolinensis, wilson)) of two proteins, ribonuclease and ferritin, and two colloidal suspensions, thorium dioxide and gold, was studied in the electron microscope. the initial step in the pinocytosis of ferritin and thorium dioxide particles by amebas is shown to be the attachment of these substances to the "hairlike" extensions of the plasmalemma. ribonuclease caused alterations in the structure of the plasmalemma, but on acco ... | 1960 | 19866575 |
| mitochondria. i. fine structure of the complex patterns in the mitochondria of pelomyxa carolinensis wilson (chaos chaos l.). | some of the mitochondria in the free-living giant ameba pelomyxa carolinensis (chaos chaos) exhibit unusual and strikingly complex morphological patterns. a study of serial sections of these mitochondria reveals that the patterns are formed by the organization and packing of minute villi (cristae mitochondriales). the form of the individual villus is a regular soft zigzag (or wave) with a bulbous enlargement at each point of inflection ("elbow") on the wave. the pattern of the mitochondria may b ... | 1959 | 13673052 |
| effects of low concentration of cyanide on growth and respiration in pelomyxa carolinensis-wilson. | | 1951 | 14816427 |
| observations on the reaction of pelomyxa carolinensis subjected to a direct-current electric field. | | 1950 | 15440326 |
| pelomyxa carolinensis wilson; further observations on plasmotomy. | | 1949 | 18135698 |
| the effects of low concentration of potassium cyanide on growth and respiration in pelomyxa carolinensis wilson. | | 1948 | 18932984 |
| the effects of ethylalcohol on growth and respiration in pelomyxa carolinensis and upon conjugation in paramecium caudatum. | | 1948 | 18884196 |
| the experimental estimation of the latent period in reaction to light of pelomyxa carolinensis. | | 1947 | 18935489 |
| factors affecting encystment in pelomyxa carolinensis. | | 1947 | 18935479 |
| pelomyxa carolinensis wilson; nuclear division and plasmotomy. | | 1947 | 20281548 |
| concerning the correct name of the rhizopod, pelomyxa carolinensis. | | 1947 | 20242308 |
| lipid metabolism in the rhizopod, pelomyxa carolinensis. | | 1946 | 20341478 |
| the presence of lipase in pelomyxa carolinensis. | | 1946 | 20341144 |
| the lipids in pelomyxa carolinensis. | | 1946 | 20275370 |
| notes on locomotion in pelomyxa carolinensis. | | 1946 | 20244095 |
| relation between metabolic activity and cyanide inhibition in pelomyxa carolinensis wilson. | | 1946 | 20993175 |
| some physical properties of the vacuolar membranes in pelomyxa carolinensis. | | 1946 | 20990875 |
| pelomyxa carolinensis wilson; general observation on the illinois stock. | | 1946 | 20985550 |
| relation between type of metabolism and effect of cyanide on pelomyxa carolinensis. | | 1946 | 21066189 |
| the composition of the refractive bodies in the rhizopod pelomyxa carolinensis. | | 1945 | 21006500 |
| correction. | i am indebted to eugene s. mccartney for calling attention to an error in my article on "the use of generic names as common nouns," science, vol. 96, p. 252. "pelomyxa carolinensis," line 13, should be omitted, for "carolinensis" is not a noun in the genitive case, but an adjective in the nominative case. | 1942 | 17833232 |