| effect of ultraviolet radiation on pinocytosis in amoeba proteua. | ultraviolet (uv) irradiation (4 000-10 000 erg x mm(-2) decreased membrane potential and input resistance of amoeba proteus and induced formation of pinocytotic channels. submaximal pinocytosis induced by uv light was additive to pinocytosis induced by k+ or na+ and stimulated in the presence of egta. it was not inhibited by the presence of la+++ or by pretreatment with dibucaine. in these respects and with respect to optimum ph and pca, uv induced pinocytosis. accumulation of k+ in the amoeba m ... | 1976 | 5848 |
| 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 |
| the contractile basis of amoeboid movement iii. structure and dynamics of motile extracts and membrane fragments from dictyostelium discoideum and amoeba proteus. | motile extracts from d, discoideum and a. proteus have been characterized in order to compare the structural dynamics and chemical regulation of movement in 2 different types of amoeboid cells. the structural dynamics of both extracts involve the formation of a nonmotile cytoskeleton followed by the contraction of actin and myosin to generate both direct contractile force and cytoplasmic streaming. the contractions are regulated by calcium ions and a threshold of ca. 1.0 x 10(-6) m calcium induc ... | 1977 | 22087 |
| demonstration of membrane-associated and oriented microfilaments in amoeba proteus by means of a schiff base/glutaraldehyde fixative. | after fixation with a reaction product of glutaraldehyde and spermidine phosphate amoeba proteus cells show a network of cortical microfilaments and oriented bundles of thick and thin filaments. the cortical filament network appears to be membrane-attached and extends beneath the whole cytoplasmic membrane surface. in the uroid region and in retracting pseudopods the cortical layer is thicker than in advancing cell regions. the filament bundles are located predominantly in the ectoplasmic tube w ... | 1978 | 101401 |
| neuraminidase treatment enhances the lysolecithin induced intercellular adhesion of amoeba proteus. | egg lysolecithin induces intercellular adhesion of amoeba proteus. pre-treatment of cells with vibrio cholerae neuraminidase (vcn) increases the adhesive property of cells as was evidenced in their formation of larger cell aggregates than controls. a possible role of vcn exposed receptor sites in cellular adhesion is suggested. | 1975 | 126599 |
| studies on the mechanism of induction of pinocytosis in amoeba proteus. | | 1975 | 181949 |
| [microspectrophotometric study of the crystalline inclusions in different strains of amoeba proteus]. | using microspectrometric technique, integral extinction and extinction spectra of crystalline inclusions of two amoeba strains, c and ct, have been studied. the analysis of extinction spectrum form allowed to suggest that the crystals seen in both amoeba strains have identical chemical composition, whereas the morphological differences between cells in their transparency may be due to different mode of the crystal package. the relative amount of the crystals was measured in both amoeba strains o ... | 1979 | 225850 |
| [effect of neuraminidase on phagocytosis activity in amoeba proteus (author's transl)]. | | 1979 | 421771 |
| [the phagocytic reaction in amoeba proteus. ii. phagocytosis of non-living particles]. | | 1978 | 688109 |
| fine structure of cytoplasmic crystal in amoeba proteus. | | 1978 | 689254 |
| cytoplasmic streaming in amoeba proteus is inhibited by the actin-specific drug phalloidin. | | 1978 | 689103 |
| differences between nucleus and cytoplasm in the degree of actin polymerization. | for purposes of studying the degree of polymerization of actin in nuclei, nuclei from 35s-labeled amoebas (amoeba proteus) were transplanted into unlabeled cells, which were immediately lysed and extracted under conditions considered to stabilize preexisting fibrous actin. the enucleated 35s-donor cells were similarly treated for analysis of cytoplasmic actin. the extraction conditions permitted separation of soluble (unpolymerized or g) actin from pelletable (polymerized or f) actin, and the ra ... | 1978 | 681454 |
| interference reflection microscopy of adhesion of amoeba proteus. | a simple method of observing the adhesive behaviour of large cells by means of interference reflection microscope is described, and some observations of monopodial amoeba proteus are presented. amoebae may contact with the substratum at any point along the long axis of the cells. points of contact are usually few, small and temporary. frequently the cell surface within the contact points oscillates, changing the separation distance from the substratum. | 1978 | 650677 |
| holographic microscopy of glycerination of amoeba proteus. | the process of glycerination of amoeba proteus was observed under the holographic microscope with coherent noise elimination. it was found that during glycerination redistribution of cell material occurs, and is accompanied by reversible deformation of the cell cortex. the rôle of the cortex in shape maintenance in glycerinated models was demonstrated. | 1978 | 641989 |
| electron microscopic visualization of transcribed genes in the nucleus of amoeba proteus. | | 1978 | 631219 |
| characteristics of the 'life spanning' phenomenon in amoeba proteus. independent nuclear and cytoplasmic ability to impose finite 'life span'. | amoeba proteus given adequate food grows exponentially and clones of amoebae are normally immortal. after periods of food supply restriction to that necessary for maintenance, or food intake restriction by agitation, cells subsequently given a normal growth diet produce clones of finite life span. reciprocal nuclear transfer between maintained and normal cells demonstrated that the nucleus and cytoplasm of maintained cells have acquired the independent ability to impose a finite life span on clo ... | 1978 | 620943 |
| closure of the plasma membrane around microneedle in amoeba proteus. an ultrastructural study. | | 1978 | 620690 |
| nuclear actin: an apparent association with condensed chromatin. | in amoeba proteus the concentration of actin is the same in the nucleus and cytoplasm. certain characteristics, e.g., the ready loss of actin from isolated nuclei, suggest that the association with nuclei is normally not a tight one. here we report, however, that when nuclei are isolated several hours after mitotic amebas are placed in actinomycin d (which allows normal progression of mitosis), the nuclei retain substantial amounts of actin. since this finding correlates with other observations ... | 1977 | 610879 |
| effects of the actin-binding protein dnaase i on cytoplasmic streaming and ultrastructure of amoeba proteus. an attempt to explain amoeboid movement. | microinjection of dnaase i, which is known to form a specific complex with g-actin, induces characteristic changes in cytoplasmic streaming, locomotion and morphology of the contractile apparatus of a. proteus. light microscopical studies show pronounced streaming originating from the uroid and/or the retracting pseudopods, which ceases 10--15 min after injection of dnaase i, at a time when ultrasctructural studies show that the actin filament system is very much reduced. these results suggest t ... | 1979 | 573180 |
| sucrose uptake by pinocytosis in amoeba proteus and the influence of external calcium. | the relationship between ca++ and pinocytosis was investigated in amoeba proteus. pinocytosis was induced with 0.01% alcian blue, a large molecular weight dye which binds irreversibly to the cell surface. the time-course and intensity of pinocytosis was monitored by following the uptake of [3h]sucrose. when the cells are exposed to 0.01% alcian blue, there is an immediate uptake of sucrose. the cells take up integral of 10% of their initial volume during the time-course of pinocytosis. the durat ... | 1979 | 512629 |
| calcium distribution in amoeba proteus. | a preliminary investigation of the distribution of cellular calcium in amoeba proteus was undertaken. total cellular calcium under control conditions was found to be 4.59 mmol/kg of cells. when the external ca++ concentration is increased from the control level of 0.03 to 20 mm, a net ca++ influx results with a new steady-state cellular calcium level being achieved in integral of 3 h. at steady state the amount of calcium per unit weight of cells is higher than the amount of calcium per unit wei ... | 1979 | 512628 |
| naloxone-reversible effect of opioids on pinocytosis in amoeba proteus. | a characteristic feature of induced pinocytosis in amoeba proteus is the formation of broad channels by invagination of the cell membrane. this process, which requires ca2+, occurs in response to depolarising cations. high ca2+ levels reduce pinocytosis induced by cations such as na+ and tris+, whereas pinocytosis induced by k+ is less affected by ca2+ (ref. 4). agents which interfere with the calcium metabolism of the amoeba will therefore either stimulate or inhibit pinocytosis induced by na+ ... | 1979 | 503190 |
| effect of chloramphenicol on bacterial endosymbiotes in a strain of amoeba proteus. | the effect of chloramphenicol (cap) on the bacterial endosymbiotes of a strain of amoeba proteus was studied by growing the symbiotic amebae in media containing 0.5-1.6 mg/ml cap for up to 4 weeks. treatments with cap caused such ultrastructural changes as expansion of the nuclear zone and deformation of symbiotes. the cap treatment also damaged the mitochondria, e.g. disappearance of central and protrusion of peripheral cristae. number of bacteria per ameba decreased to less than 10% of control ... | 1977 | 881653 |
| [relationship of the dna content in the nuclei of amoeba proteus to the food regimen]. | the relative dna content of isolated amoeba proteus nuclei has been measured by cytofluorometry. with the amoeba strain studied, the generation time is roughly equal to 48 hours at 25 degrees c, and with the presence of food in the medium. after the synchronous divisions, amoebae were maintained in the medium either with or without food organisms (tetrahymena pyriformis). dna contents in the nuclei of both the amoebae groups were measured within 4 and 48 hours after division. before 16 hours, th ... | 1979 | 494392 |
| morphological alterations in the mitochondria of amoeba proteus induced by uncoupling agents. | ultrastructural changes in mitochondrial morphology were observed in amoebae exposed to the uncoupling agents dinitrophernol (dnp), pentachlorophenol (pcp), and m-chlorocarbonyl cyanide phenylhydrazone (cccp). these alterations occurred with rapidity and were present before whole-cell activity changes could be detected. they included changes in profile shape and overall dimensions, matrix density changes, and alterations to the cristal membranes, so that distinction between control type i and ty ... | 1979 | 479326 |
| pinocytosis and locomotion of amoebae: xii. dynamics and motive force generation during induced pinocytosis in a. proteus. | the mechanism of induced pinocytosis was investigated in amoeba proteus by light and electron microscopy. the application of nine different inducing substances revealed that pinocytotic channel formation, elongation, vesiculation, shortening and disappearance are the result of the successive or simultaneous action of both traction and pressure forces, which are produced by the contractile activity of a plasma membrane-associated layer of filaments ranging from a few hundred nm to several microme ... | 1979 | 436147 |
| the effects of chemicals and radiations within the cell: an ultrastructural and micrurgical study using amoeba proteus as a single-cell model. | | 1979 | 389869 |
| nuclear transplantation studies in amoeba proteus. | | 1979 | 385539 |
| humidifier-associated extrinsic allergic alveolitis. | three cases of allergic alveolitis due to indoor humdification systems are described. thermoactinomyces vulgaris precipitins were detected in the serum of a 37-year-old female patient who had typical febrile attacks during exposure to cool-mist from a home humidifier. when the cause was detected and eliminated, the symptoms and signs disappeared and the woman's gas transfer factor improved from 56% to normal within six months. in a printing office a 60-year-old woman had had febrile attacks with ... | 1979 | 375386 |
| microfibrillar structures in the nucleus and cytoplasm of amoeba proteus. | the presence of microfibrillar structures in the nucleus and cytoplasm of amoeba proteus has been described after glutaraldehyde and osmium fixation. the possible roles of cytoplasmic microfibrils in the contraction process of amoeba and nuclear microfibrils in the formation of the honeycomb nuclear lamina are discussed. | 1975 | 1133571 |
| amoeba proteus: the nuclear periphery. | this study extends previous work on the nuclear envelope and associated structures. it illustrates that the cylindrical structures of the honeycomb lattice are not attached to the nuclear envelope, although generally perpendicular and closely apposed to it, and that there is a complex arrangement of fibrillar material between the cylinders of the lattice. the relationship of nuclear helices to these structures is described and the possible mode of their transfer from nucleus to cytoplasm is disc ... | 1975 | 1137851 |
| quantation by flow microfluorometry of total cellular dna in acanthamoeba. | the dna content of five species of acanthamoeba was determined by flow microfluorometry. acanthamoeba castellanii (ac-30), acanthamoeba polyphaga (apg and p-23), acanthamoeba rhysodes, acanthamoeba culbertsoni (a-1), and acanthamoeba royreba were grown in a casitone based medium 24-48 hr. the trophozoites were harvested, and evaluated for dna-bound fluorescence. all species tested has dna values between 2.0-5.0 pg/cell. these results placed dna/cell values of acanthamoeba slightly lower than dna ... | 1978 | 361883 |
| inhibition of induced pinocytosis in amoeba proteus by membrane stabilizing drugs. | the effect of membrane stabilizing drugs on cation induced pinocytosis was studied in amoeba proteus. initially the presence of local anesthetic drugs during a pinocytosis cycle had a stimulating effect on channel formation, however, the capacity to develop pinocytotic channels was reversibly inhibited after a period of treatment with these drugs. imipramine, vinblastine and the phenothiazines had effects similar to local anaesthetics. the local anesthetics inhibited pinocytosis in the following ... | 1975 | 242188 |
| the specificity of amino acid uptake by amoeba proteus. | | 1975 | 240626 |
| membrane potential and conductance during pinocytosis induced in amoeba proteus with alkali metal ions. | an investigation of the relationship between the polarized state of the membrane and the onset and the intensity of pinocytosis was made in amoeba proteus. membrane potential and input resistance was in all instances found to decrease in approximate proportion to the number of channels when pinocytosis was induced by a variety of alkali metal ions at varying ph. channels began to appear when the membrane was depolarized to -30 mv by the inducer of pinocytosis. with all inducers the maximum pinoc ... | 1975 | 239524 |
| on the nature of hyaline zones in the cytoplasm of amoeba proteus. | investigations with the nomarski dic (differential interferece contrast) microscope and the electron microscope on the nature of hyaline zones in the cytoplasm of amoeba proteus revealed that these regions represent pure ground cytoplasm. differences between specimens 1) treated with 2% ethanol, 2) released from high hydrostatic pressure or 3) preincubated at 35 degrees c for 30 minutes could not be observed. only dying cells undergoing lysis contained a watery solution within the zones of hyali ... | 1975 | 1196142 |
| ca2+-binding modulator protein in protozoa and myxomycete. | ca2+-binding protein with the properties of brain modulator protein of 3,5-cyclic nucleotide phosphodiesterase was identified in physarum polycephalum plasmodia and in euglena gracilis and amoeba proteus cells by urea polyacrylamide gel electrophoresis and activation of cyclic nucleotide phosphodiesterase and of myosin light chain kinase. | 1979 | 222487 |
| the role of nucleus and cytoplasm in the inheritance of multiplication rates in amoeba proteus cultured at different temperatures. | | 1976 | 1248518 |
| relationships between membranous organelles in amoebae studied by electron microscopic cytochemical staining. | the intracellular location of a variety of enzymes was studied in amoeba proteus with the use of electron microscopic cytochemical methods, in an attempt to assess the relationships between different membranous organelles. one group of enzymes, including nucleoside diphosphatases (idpase, udpase, gdpase, adpase), carbamoyl phosphatase, alkaline phosphatase, and baxd oxidase was localized mainly in the rough endoplasmic reticulum, nuclear envelope, and convex side of the golgi apparatus. esterase ... | 1977 | 194699 |
| ultrastructure of the frontal cap of monotactic forms of amoeba proteus. | the frontal cap of the monotactic form of amoeba proteus is separated from other cell components by a continuous structure defined as the "membrane-like envelope" (mle). it originates from the membranes of cytoplasmic vesicles and vacuoles. the border zone between the cap and the cytoplasm is strongly vacuolized. structural differences between frontal caps, depending on the degree of their development, indicate that the growing cap gradually fills up the whole tip of an advancing pseudopodium, a ... | 1978 | 689256 |
| response to light-shade difference in anucleate and polynucleate specimens of amoeba proteus. | the enucleated specimens of amoeba proteus, the anucleate fragments, and the polynucleate individuals which all are capable of cortical contraction but not of locomotion, may be reactivated by the light-shade difference established across their body. individual cells or fragments migrate toward the shade. the motory polarity and coordinated movement disappear immediately after cessation of the stimulus. the results are interpreted according to the earlier hypothesis that the necessary to maintai ... | 1978 | 689261 |
| identification of the small nuclear rnas associated with the mitotic chromosomes of amoeba proteus. | amebas contain 7 electrophoretically distinct species of small nuclear rnas (snrnas), some of which are known to associate in a striking manner with mitotic chromosomes. these rnas can be divided into 2 classes, one consisting of 4 snrna species that shuttle in a non-random way between nucleus and cytoplasm during interphase and one consisting of 3 snrna species that do not leave the nucleus at all during interphase. in the work reported here we sought to determine which class is associated with ... | 1978 | 710236 |
| 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 ... | 1978 | 710672 |
| diaminobenzidine reactions in control and treated amoeba proteus. | cytochrome oxidase activity was demonstrated in amoeba proteus by diaminobenzidine (dab) cytochemistry. deposition of the reaction product occurred on the inner mitochondrial membranes and the cristae. the reaction was abolished by cyanide incubations. positive reactions were produced with both unfixed and fixed cells: although staining potential was destroyed by any prefixatives which included glutaraldehyde. cells prefixed with 4% formaldehyde, to raise structural preservation, retained staini ... | 1978 | 730555 |
| peculiarities of changes in dna content of amoeba proteus nuclei during interphase. a cytofluorometric study. | | 1979 | 759212 |
| [preparation of biological specimens for the scanning electron microscope (author's transl)]. | three methods usually applied in preparing biological material for the scanning electron microscope were tested by the investigation of two species of amoebae with different content of water (amoeba proteus, vannella simplex). air drying resulted in both the production of cell shrinkage and cell distortion. when the specimens were dryed from media with increasing vapour-pressure, more satisfactory preservation of surface structures could be obtained. the sequence of potency was: ethanol, chlorof ... | 1976 | 794634 |
| the fate and origin of the nuclear envelope during and after mitosis in amoeba proteus. i. synthesis and behavior of phospholipids of the nuclear envelope during the cell life cycle. | the synthesis and behavior of amoeba proteus nuclear envelope (ne) phospholipids were studied. most ne phospholipid synthesis occurs during g2 and little during mitosis or s. (a. proteus has no g1 phase). autoradiographic observations after implantation of [3-h] choline nuclei into unlabeled cells reveal little turnover of ne phospholipid during interphase but during mitosis all the label is dispersed through the cytoplasm. beginning at telophase all the label is dispersed through the cytoplasm. ... | 1975 | 805790 |
| contractility of glycerinated amoeba proteus and chaos-chaos. | immediate contact with large volumes of cold 50% (v/v) buffered glycerol preserved typical ameboid shape of chaos chaos and amoeba proteus with no visible distortions. these technics allowed determination of the contraction sites in these glycerinated models upon applications of atp-ca-mg-solutions. the ectoplasmic tube was the main site of contraction. preliminary em investigations revealed thick and thin filaments, associated with the ectoplasmic tube near the plasma-lemma, which appeared to b ... | 1975 | 807722 |
| the isolation of microquantities of myosin from amoeba proteus and chaos carolinensis. | | 1977 | 851213 |
| small nuclear rna localization during mitosis. an electron microscope study. | the localization of small nuclear ribonucleic acids (snrnas) during mitosis in amoeba proteus was studied by high voltage (1,000 kv) electron microscope autoradiography. by suitable micromanipulations, the snrna's, labeled with [3h]uridine, were made to be the only radioactive molecules in the cell and thus easy to follow autoradiographically. during interphase the snrna label, which is almost exclusively nuclear, is distributed fairly uniformly through the nucleus with a slightly higher amount ... | 1977 | 870500 |
| effect of lanthanum on pinocytosis induced by cations in amoeba proteus. | lanthanum chloride (greater than or equal to 10(-5) m) induced pinocytosis in normal and at greater than or equal to 10(-4) m in ca++-deficient amoeba. with respect to the ca++-requirement of the pinocytotic response low and high concentrations of la+++ had effects like na+ and k+, respectively. the concentration of la+++ stimulated or inhibited other types of pinocytosis. thus all concentrations of la+++ inhibited sodium induced pinocytosis while high concentrations (greater than 10(-3) m) stim ... | 1976 | 818877 |
| binding of [125i]concanavalin a by interspecific amoeba hybrids. | two types of interspecific amoeba hybrids, viz. pnic (amoeba proteus nucleus in a. indica cytoplasm) and inpc (a. indica nucleus in a. proteus cytoplasm), were tested for their [125i]concanavalin a (con a) binding activity at different periods of time. the cell surface binding of the labelled con a was reduced to approx. 40 and 75% in the pnic and inpc cells, respectively, 96 h after the cells were made hybrids. a significant increase in the binding of radioactive con a was observed after the ho ... | 1977 | 890742 |
| [stable inheritable increase in the level of cell mortality (experiments on amoeba proteus exposed to heat and radiation)]. | amoeba proteus cultivated as individual lines qt 24 degrees c were exposed to heating at 29 degrees c during three days or to x-rays of 200 kv at a dose of 5 kh or to combination of both. the original method -- periodical resumption of individual lines from sister-cells -- was used to observe the offspring of amoebae during 8 months. it is found that not only radiation but slight heating as well induce unusual hereditary effect in amoebae: stable increase of cell mortality level. the effect was ... | 1977 | 914032 |
| relations between the nuclear activity and the variable 3h-amino acid incorporation pattern in amoeba proteus. | tracer kinetic studies have revealed the existence of a variable pattern of 3h-amino acid incorporation into amoeba proteins during the early g2 phase of the cell cycle. two peaks of incorporation of [3h]leucine were found to occur at 19 and 22 h, whereas a single peak at 17 h was noticed in the amoebae labelled with [3h]lysine. an almost 2-fold increase of the labelled amino acid incorporation occurred during the peak periods, while the other periods showed a more or less steady state of incorp ... | 1976 | 932109 |
| [different types of hereditary changes in cell survival caused by x-rays in different dosage (experiments conducted on amoeba proteus)]. | | 1976 | 968003 |
| timing of nucleolar dna replication in amoeba proteus. | light- and electron-microscope autoradiography have been used to follow the incorporation of [3h]thymidine at different stages during the interphase of synchronously growing populations of amoeba proteus. two main patterns were found for tritiated thymidine incorporation, i.e. dna synthesis. the major incorporation was in the central region of the nucleus, but a lesser degree of incorporation occurred in the nucleolar region. the bulk of this nucleolar dna was found to be late replicating, i.e. ... | 1976 | 1018044 |
| prostaglandins may play a signal-coupling role during phagocytosis in amoeba proteus. | phagocytosis in amoeba proteus can be induced with prostaglandins (pg). in addition, arachidonic acid (the fatty acid precursor to the pg-2 series) also induces phagocytosis. the induction of phagocytosis with arachidonic acid can be partially inhibited by the cyclooxygenase inhibitor indomethacin. phagocytosis in the amoeba can also be induced with the chemotactic peptide n-formylmethionyl-leucylphenylalanine (nfmlp). the peptide presumably induces phagocytosis by interacting with receptors on ... | 1989 | 2495854 |
| effects of induced pinocytotic activity and extreme temperatures on the morphology of golgi bodies in amoeba proteus. | the morphology of the golgi apparatus of amoeba proteus can be influenced by substances inducing pinocytotic activity as well as by extreme temperatures. during the ingestion of a solution of 0.5% egg white the number of golgi bodies decreases from 100% measured in control cells to 82% measured in cells showing induced pinocytosis. simultaneously the ratio of the surface area of the cisternae at the proximal face to that of the vesicles at the distal face of single dictyosomes remains constant ... | 1975 | 1131858 |
| antigenic reactivity of a monoclonal antibody against amoeba proteus actin. | the reactivity of a monoclonal antibody against actin of amoeba proteus with actins from other sources was examined. the monoclonal antibody cross-reacted with actins from vertebrate muscles, human erythrocytes, and acanthamoeba castellanii, but it did not react with naegleria gruberi actin. the amoeba actin was resolved into 3 bands with isoelectric points of 5.96, 6.03 and 6.10 in electrofocusing gels and they corresponded to 3 peptide spots reacting with the antibody on 2-dimensional immunobl ... | 1989 | 2600879 |
| oriented thick and thin filaments in amoeba proteus. | actin and myosin filaments as a foundation of contractile systems are well established from ameba to man (3). wolpert et al. (19) isolated by differential centrifugation from amoeba proteus a motile fraction composed of filaments which moved upon the addition of atp. actin filaments are found in amebas (1, 12, 13) which react with vertebrate heavy meromyosin (hmm), forming arrowhead complexes as vertebrate actin (3, 9), and are prominent within the ectoplasmic tube where some of them are attache ... | 1975 | 1141376 |
| [change of the hereditary properties of amoeba proteus during micrurgic intervention at the time of mitosis (metaphase ane early anaphase)]. | studies have been made on viability and hereditary properties of the progeny of amoebae after micrurgical coercions (sectioning of cells, suction of cytoplasm) during metaphase and early anaphase. the progeny of the fragments as well as of the cells with the reduced bulk of the cytoplasm exhibits unusual methionine resistance. possible mechanism of the observed phenomemon are discussed. | 1975 | 1145767 |
| selective effects of enucleation and transfer of heterologous nuclei on cytoplasmic organelles in amoeba proteus. | the ultrastructural changes in the cytoplasm of lethal hybrids obtained by nuclear transplantation between different strains of amoeba proteus were compared with those of enucleated amebae. it was found that, whereas the golgi complex and glycocalyx degenerated first in enucleated cells, mitochondria and endosymbiotes became abnormal first in the hybrids. the selective effects are attributed to the presence of nucleic acids in the mitochondria and endosymbiotes and hence to the different inter ... | 1975 | 1159642 |
| cytoplasmic filaments and cellular wound healing in amoeba proteus. | the flexibility and self-healing properties of animal cell surface membranes are well known. these properties have been best exploited in various micrurgical studies on living cells (2, 3), especially in amoebae (7, 20). during nuclear transplantation in amoebae, the hole in the membrane through which a nucleus passes can have a diameter of 20-30 mum, and yet such holes are quickly sealed, although some cytoplasm usually escapes during the transfer. while enucleating amoebae in previous studies, ... | 1975 | 1176533 |
| [incompatibility during transplantation of nuclei in amoeba. iv. transplantation compatibility in different strains of amoeba proteus]. | seven laboratory amoeba proteus strains of different origin were tested for their transplantation compatibility (i.e. viability of artificially produced heterokaryons) in all possible pair combinations. incompatible combinations (14) as well as completely compatible ones (7) were found. compatibility was distributed among strain combinations non-randomly. all the strains studied could be classified into three groups with respect to compatibility ("compatibility groups") involving 1, 2 and 4 stra ... | 1975 | 1218727 |
| graphs of contracting glycerinated amoeba proteus. | | 1976 | 1264207 |
| inhibition of cell division in amoebae: the incorporation of tritiated precursors into amoeba proteus after the injection of non-homologous cytoplasm. | the injection of non-homologous cytoplasm into any strain of large free-living amoebae leads to a 60% inhibition of division amongst recipient cells. when the post-microsomal supernatant fraction of amoeba discoides was injected into a. proteus, this inhibition of division was as high as 95%. the incorporation of tritiated precursors, either [3h]uridine or 3h-amino acids, into these inhibited amoebae was studied at various times after the injection of the inhibitory material using autoradiograph ... | 1976 | 1270528 |
| scanning electron microscope observations of amoeba proteus during phagocytosis. | phagocytosing amoeba proteus at different stages of forming foodcups have been observed by scanning electron microscopy. a nonphagocytosing ameba is characterized by dorsal and lateral ridges running longitudinally over the posterior half of the cell and its attachment to the substrate over small areas. when stimulated by prey organisms, the ameba loses polarity and ridges, and adheres to the substrate more firmly over a wider area of contact. then it forms broad pseudopods to surround its prey ... | 1976 | 1271309 |
| [cytofluorimetric research on the changes in the dna content in the nuclei of amoeba proteus during prolonged starvation and after refeeding]. | dividing amoebae were manually selected from the culture of amoeba proteus, and so groups of synchronously dividing (synchronized) amoebae were obtained. these synchronized amoebae were maintained without food. in spite of starvation, individual amoebae in some particular groups were seen to divide, whereas in other groups of amoebae there was no division at all. the starving amoebae died not earlier than 2 weeks after the last division. a relative dna content in isolated nuclei has been determi ... | 1992 | 1302398 |
| lysosomal membrane proteins of amoeba proteus, as studied with monoclonal antibodies. | monoclonal antibodies were prepared against lysosomal membrane proteins of amoebae and used to follow lysosome-phagosome fusion after induced phagocytosis. the specificity of antibodies was checked by indirect immunofluorescence microscopy, immunoelectron microscopy, and localization of the antigen in subcellular fractions. the antibody-recognized proteins started to appear on the membranes of phagolysosomes about 5 min after phagocytosis as detected by indirect immunofluorescence, and the inten ... | 1992 | 1453355 |
| virotoxins polymerize actin and induce membrane fragmentation in cytoplasmic preparations of amoeba proteus. | virotoxins and phalloidin are peptides that induce actin polymerization in vitro. we have compared the effect of five virotoxins and phalloidin on the ultrastructure of spread preparations of amoeba proteus cytoplasm. like phalloidin, the five virotoxins induce polymerization of cytoplasmic actin. moreover, the virotoxins, but not phalloidin, induce membrane fragmentation in small spherical vesicles. we, therefore, conclude that these virotoxins may have another membrane-bound target besides act ... | 1992 | 1476708 |
| reversal by concanavalin a of the inhibitory effects of extracellular ca2+ on pinocytosis in amoeba proteus. | when concanavalin a, 1-20 micrograms ml-1 binds to the surface of amoeba proteus the cell's response to ca2+ and to cationic inducers of pinocytosis is strikingly altered. separately, concanavalin a and ca2+ are weak inducers but their combined effects are intense pinocytosis and suppression of the normal inhibitory effect of ca2+ on cation-induced pinocytosis. at high concentrations (greater than 25 micrograms ml-1) the lectin increases cellular uptake and binding of 45ca in the cell surface bu ... | 1992 | 1595356 |
| use of an amoeba proteus model for in vitro cytotoxicity testing in phytochemical research. application to euphorbia hirta extracts. | amoeba proteus is proposed as a low-cost multi-purpose biochemical tool for screening and standardizing cytotoxic plant extracts with possible application in the laboratories of developing countries. advantages and limitations of this test are examined and different mathematical treatments (probit analysis versus curve fitting to von bertalanffy and hill functions) are investigated. known anti-cancer (doxorubicin, daunorubicin, dacarbazine, 5-fluorouracil) and antiparasitic (emetine, dehydroemet ... | 1991 | 1686625 |
| direct membrane effects of morphine and endorphins on amoeba proteus. | morphine, leu-enkephalinamide, met-enkephalin, alpha-neoendorphin and its arg8 1-8 fragment increase contractile vacuole output in the freshwater amoeba proteus at 18 microm. significant effects of leu-enkephalin and naloxone are obtained at 180 microm. all compounds have reached their maximal activity at 720 microm. alpha-neoendorphin and leu-enkephalin are inactive in the presence of isotonic, non-penetration sucrose, hence these compounds increase plasma membrane permeability to water. result ... | 1992 | 1731168 |
| localization of ionic calcium in amoeba proteus. | | 1970 | 4099167 |
| visualization and measurement of calcium transients in amoeba proteus by fura-2 fluorescence. | a fura-2 microspectrofluorimeter was used to visualize and measure intracellular calcium transients in normal locomoting and experimentally treated amoeba proteus. the results show that subcellular heterogeneities of cytosolic free calcium, [ca2+]i, correlate in time and distribution with characteristic patterns of protoplasmic streaming and ameboid movement. in detail, calcium ions have a dual effect by regulating both the contractile activities of the actomyosin cortex and the rheological prop ... | 1991 | 1935991 |
| role of spectrin in amoeba proteus, as studied by microinjection of anti-spectrin monoclonal antibodies. | spectrin is a major protein accounting for about 5% of whole-cell proteins in amoeba proteus, and the precipitation of spectrin by intracellular injection of purified anti-spectrin monoclonal antibodies has a profound effect on cell morphology, motility, and movement-related cell activities in amoebae. thus, amoebae injected with anti-spectrin antibodies show drastic changes in their shape and movement, suggesting that amoeba spectrin plays an important structural role, unlike nonerythroid spect ... | 1992 | 1735457 |
| cytochemical staining of the golgi apparatus in amoeba proteus. | | 1970 | 4121487 |
| structure of synthetic and native myosin filaments from amoeba proteus. | | 1974 | 4138977 |
| elevated levels of stress proteins associated with bacterial symbiosis in amoeba proteus and soybean root nodule cells. | obligatory bacterial endosymbionts of amoeba proteus and symbiotic bradyrhizobium japonicum bacteroids in soybean-root nodules contained large amounts of 67-kda and 65-kda proteins, respectively, antigenically related to groel of e. coli and the 58-kda heat-shock protein of tetrahymena. monoclonal antibodies against the 67-kda protein recognized groel analogs from several different organisms. the quantity of the stress protein in symbiotic b. japonicum bacteroids was augmented seven times that i ... | 1991 | 1912387 |
| the negatively charged protein extracted from tetrahymena pyriformis as an attractant in amoeba proteus chemotaxis. | | 1974 | 4210774 |
| a study of the change in dna synthesis of s phase cells treated with n-methyl-n-nitrosourethane: a study using amoeba proteus as a single cell model. | the present experiments using amoeba proteus as a single cell model show that dna synthesis continues during and after exposure of s phase cell to n-methyl-n'-nitrosourethane (mnu). at sublethal dose levels which caused long division delays, division and growth abnormalities and mutations, the amount of [3h] thymidine ([3h]tdr) incorporated was decreased by 20-30%; at dose levels which killed all s phase cells it was inhibited by up to 90%. there was a direct correlation between the dose of mnu ... | 1976 | 1253334 |
| [pinocytosis and locomotion of amoebae. 3. the function of the golgi apparatus of amoeba proteus and chaos chaos]. | | 1969 | 4241748 |
| the biochemical composition of the free-living amoebae chaos chaos, amoeba dubia and amoeba proteus. | | 1968 | 4249055 |
| [effect of colchicine and vinblastine on amoeba proteus atpase]. | | 1972 | 4261823 |
| studies on changes in the nuclear helices of amoeba proteus during the cell cycle. | the fine structure of the nuclei of synchronously growing cell population of amoeba proteus was studied at i-h intervals during the interphase. this study showed that the nuclear helices undergo increases in their number at certain stages during interphase. these changes were found to correlate with ultrastructural changes occurring in the nucleoli. | 1976 | 1262409 |
| preparation of cultured and isolated cells for x-ray microanalysis. | various electron microscopical preparation techniques are compared with regard to the preservation of the intracellular element distribution as determined by x-ray microanalysis in scanning and scanning transmission electron microscopy. by use of chemical agents for fixation and dehydration ions are redistributed and washed out. this is also true for freeze-substitution. whole cells are prepared by cryofixation followed by freeze-drying. interference of intracellular measurements by extracellula ... | 1988 | 3201205 |
| [a comparative cytochemical study of amoeba proteus adapted to different temperatures]. | | 1967 | 4295270 |
| the rna base composition of amoeba proteus, amoeba discoides and their heterospecific hybrids. | | 1974 | 4425534 |
| dissociation of membrane-cortex contacts in the hyalospheres of amoeba proteus exposed to light-shade differences. | the hyalospheres produced by a heat shock spontaneously separated successive sheets of the cortical actin layer from the plasma membrane and retracted them inward. this phenomenon was hampered or completely inhibited by 10(4) lux white light and restored in shade. the frequency of detaching the consecutive submembrane sheets was much higher in the shade than in full light. if the light-shade difference has been applied across a single hyalosphere, the detachment of cortical layer was initiated a ... | 1988 | 3224372 |
| electron probe analysis of refractive bodies in amoeba proteus. | | 1973 | 4630106 |
| possible regulation of cation-induced pinocytosis in amoeba proteus by phospholipase a. | we have studied the effects of exogenous phospholipids and compounds which are known to alter the activity of phospholipase a (pla) on ca2+-dependent, na+-induced pinocytosis in amoeba proteus. the pla-inhibitors mepacrine, p-bromophenacyl bromide (pbpb) and rosenthal's inhibitor depressed pinocytosis. normal pinocytotic intensity was restored by the addition of ca2+ or picomolar concentrations of lysolecithin. very low concentrations of lysophospholipids and different molecular species of lecit ... | 1988 | 3396589 |
| evidence of rna in the helices of amoeba proteus. | | 1972 | 4644248 |
| phosphorylation of amoeba g-actin and its effect on actin polymerization. | mass culture of amoeba proteus enabled us to do biochemical studies on this organism. actin and profilin were purified from amoeba to examine actin phosphorylation and polymerization. the apparent molecular weight of amoeba actin was 44,000, and its isoelectric point was 5.8. the apparent molecular weight of amoeba profilin was 12,000, and its isoelectric point was 4.9. it reduced the rate of actin polymerization as reported in the cases of profilins from other organisms. a protein of mr = 44,00 ... | 1986 | 3771554 |
| membrane recycling: vesiculation of the amoeba contractile vacuole at systole. | ultrastructural data on the protozoan amoeba proteus support a model of membrane recycling. at systole the amoeba contractile vacuole fuses with the cell surface and expels its contents. observations by electron microscopy indicate that, as the vacuole empties, its bounding membrane transforms into tiny (35 nanometers in diameter) vesicles, identical to the vesicles that segregate fluid and contribute to the diastolic vacuole. | 1973 | 4682134 |
| [pinocytosis and locomotion of amoebae. iv. quantitative studies on permanent and induced endocytosis of amoeba proteus]. | | 1973 | 4685107 |
| isolation and characterization of some of the proteins that shuttle between cytoplasm and nucleus in amoeba proteus. | | 1973 | 4694739 |
| [osmotic homeostasis in the freshwater ameba]. | structural and physiological osmotic adaptations of freshwater protozoa are reviewed using amoeba proteus as an example. a particular emphasis is given to the contractile vacuole. recent results on the effects of exogenous atp and vasopressin on the contractile vacuole are also presented. | 1986 | 3772815 |
| two-directional pattern of movements on the cell surface of amoeba proteus. | particles of latex, glass and precipitated alcian blue were studied cinematographically on the surface of migrating amoeba proteus and in the surrounding medium. the majority of the attached and all unattached particles flow steadily forward in the direction of the endoplasmic streaming and cell locomotion. flow on the surface is faster than in suspension. some particles stuck on the membrane move backwards from the frontal region. this retrograde transport is slower than the anterograde flow, a ... | 1986 | 3805143 |
| oscillations in cell shape and size during locomotion and in contractile activities of physarum polycephalum, dictyostelium discoideum, amoeba proteus and macrophages. | changes in cell shape and size were measured during locomotion, together with the motive force of the protoplasmic streaming, in various amoeboid cells in different stages of their life cycle, and under various environmental conditions. the variations in these measurements with time were examined by fourier spectral analysis. notwithstanding a change in cell type in the life cycle of p. polycephalum, myxamoebae and tiny plasmodia showed a similar time pattern of locomotion, exhibiting oscillatio ... | 1985 | 3965294 |