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Sample records for cryptomonas paramecium reduction

  1. Paramecium

    SciTech Connect

    Gortz, H.D.

    1988-01-01

    This book presents a survey of the current knowledge and research on Paramecium. Scientists find Paramecium a most useful object for the study of basic biological enigmas. To cover all aspects on the cell biology, cell physiology, genetics, developmental biology, ecology, endocytobiology, and molecular biology of Paramecium, specialists were asked to review their own fields. They have also included quite recent studies on the cytoskeleton, endo- and exocytosis, aging, sensory and membrane physiology, electrophysiology and motility.

  2. Possible reduction of surface charge by a mutation in Paramecium tetraurelia.

    PubMed

    Satow, Y; Kung, C

    1981-04-30

    Under voltage clamp, a mutant of Paramecium tetraurelia (teaB) shows a shift in the positive direction of the voltage sensitivity of the Ca conductance and the depolarization inactivation curve by 10 mV with no change in the total conductance. This effect can be mimicked in the wild type by the addition of external CA2+ or Mg2+. The mutation also shifts the resting potential and the voltage sensitivities of the delayed rectification (depolarization-sensitive) K conductance and the anomalous rectification (hyperpolarization-sensitive) K conductance in the positive direction to a similar extent. This systematic shift of channel voltage sensitivities is best explained by the reduction of the surface negative charges of the membrane due to the mutation. PMID:6264086

  3. Homology-dependent Gene Silencing in Paramecium

    PubMed Central

    Ruiz, Françoise; Vayssié, Laurence; Klotz, Catherine; Sperling, Linda; Madeddu, Luisa

    1998-01-01

    Microinjection at high copy number of plasmids containing only the coding region of a gene into the Paramecium somatic macronucleus led to a marked reduction in the expression of the corresponding endogenous gene(s). The silencing effect, which is stably maintained throughout vegetative growth, has been observed for all Paramecium genes examined so far: a single-copy gene (ND7), as well as members of multigene families (centrin genes and trichocyst matrix protein genes) in which all closely related paralogous genes appeared to be affected. This phenomenon may be related to posttranscriptional gene silencing in transgenic plants and quelling in Neurospora and allows the efficient creation of specific mutant phenotypes thus providing a potentially powerful tool to study gene function in Paramecium. For the two multigene families that encode proteins that coassemble to build up complex subcellular structures the analysis presented herein provides the first experimental evidence that the members of these gene families are not functionally redundant. PMID:9529389

  4. Magnetic field influence on paramecium motility

    SciTech Connect

    Rosen, M.F.; Rosen, A.D. )

    1990-01-01

    The influence of a moderately intense static magnetic field on movement patterns of free swimming Paramecium was studied. When exposed to fields of 0.126 T, these ciliated protozoa exhibited significant reduction in velocity as well as a disorganization of movement pattern. It is suggested that these findings may be explained on the basis of alteration in function of ion specific channels within the cell membrane.

  5. Is paramecium swimming autonomic?

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, Promode R.; Toplosky, Norman; Hansen, Joshua

    2010-11-01

    We seek to explore if the swimming of paramecium has an underlying autonomic mechanism. Such robotic elements may be useful in capturing the disturbance field in an environment in real time. Experimental evidence is emerging that motion control neurons of other animals may be present in paramecium as well. The limit cycle determined using analog simulation of the coupled nonlinear oscillators of olivo-cerebellar dynamics (ieee joe 33, 563-578, 2008) agrees with the tracks of the cilium of a biological paramecium. A 4-motor apparatus has been built that reproduces the kinematics of the cilium motion. The motion of the biological cilium has been analyzed and compared with the results of the finite element modeling of forces on a cilium. The modeling equates applied torque at the base of the cilium with drag, the cilium stiffness being phase dependent. A low friction pendulum apparatus with a multiplicity of electromagnetic actuators is being built for verifying the maps of the attractor basin computed using the olivo-cerebellar dynamics for different initial conditions. Sponsored by ONR 33.

  6. Effects of light intensity and temperature on Cryptomonas ovata (Cryptophyceae) growth and nutrient uptake rates

    USGS Publications Warehouse

    Cloern, James E.

    1977-01-01

    Specific growth rate of Cryptomonas ovata var. palustris Pringsheim was measured in batch culture at 14 light-temperature combinations. Both the maximum growth rate (μm) and optimum light intensity (Iopt) fit an empirical function that increases exponentially with temperature up to an optimum (Topt), then declines rapidly as temperature exceeds Topt. Incorporation of these functions into Steele's growth equation gives a good estimate of specific growth rate over a wide range of temperature and light intensity. Rates of phosphate, ammonium and nitrate uptake were measured separately at 16 combinations of irradiance and temperature and following a spike addition of all starved cells initially took up nutrient at a rapid rate. This transitory surge was followed by a period of steady, substrate-saturated uptake that persisted until external nutrient concentration fell. Substrate-saturated NO3−-uptake proceeded at very slow rates in the dark and was stimulated by both increased temperature and irradiance; NH4+-uptake apparently proceeded at a basal rate at 8 and l4 C and was also stimulated by increased temperature and irradiance. Rates of NH4−-uptake were much higher than NO3−-uptake at all light-temperature combinations. Below 20 C, PO4−3-uptake was more rapid in dark than in light, but was light enhanced at 26 C.

  7. Does Paramecium sense gravity?

    PubMed

    Mogami, Y; Ishii, J; Baba, S A

    1995-03-01

    In order to get an insight into the cellular mechanisms for the integration of the effects of gravity, we investigated the gravitactic behaviour in Paramecium. There are two main categories for the model of the mechanism of gravitaxis; one is derived on the basis of the mechanistic properties of the cell (physical model) and the other of the physiological properties including cellular gravireception (physiological model). In this review article, we criticized the physical models and introduced a new physiological model. Physical models postulated so far can be divided into two; one explaining the negative gravitactic orientation of the cell in terms of the static torque generated by the structural properties of the cell (gravity-buoyancy model by Verworn, 1889 and drag-gravity model by Roberts, 1970), and the other explaining it in terms of the dynamic torque generated by the helical swimming of the cell (propulsion-gravity model by Winet and Jahn, 1974 and lifting-force model by Nowakowska and Grebecki, 1977). Among those we excluded the possibility of dynamic-torque models because of their incorrect theoretical assumptions. According to the passive orientation of Ni(2+)-immobilized cells, the physical effect of the static torque should be inevitable for the gravitactic orientation. Downward orientation of the immobilized cells in the course of floating up in the hyper-density medium demonstrated the gravitactic orientation is not resulted by the nonuniform distribution of cellular mass (gravity-buoyancy model) but by the fore-aft asymmetry of the cell (drag-gravity model). A new model explaining the gravitactic behaviour is derived on the basis of the cellular gravity sensation through mechanoreceptor channels of the cell membrane. Paramecium is known to have depolarizing receptor channels in the anterior and hyperpolarizing receptors in the posterior of the cell. The uneven distribution of the receptor may lead to the bidirectional changes of the membrane

  8. L-glutamate Receptor In Paramecium

    NASA Astrophysics Data System (ADS)

    Bernal-Martínez, Juan; Ortega-Soto, Arturo

    2004-09-01

    Behavioral, electrophysiological and biochemical experiments were performed in order to establish the presence of a glutamate receptor in the ciliate Paramecium. It was found that an AMPA/KA receptor is functionally expressed in Paramecium and that this receptor is immunologically and fillogenetically related to the AMPA/KA receptor present in vertebrates.

  9. Paramecium tetraurelia basal body structure.

    PubMed

    Tassin, Anne-Marie; Lemullois, Michel; Aubusson-Fleury, Anne

    2015-01-01

    Paramecium is a free-living unicellular organism, easy to cultivate, featuring ca. 4000 motile cilia emanating from longitudinal rows of basal bodies anchored in the plasma membrane. The basal body circumferential polarity is marked by the asymmetrical organization of its associated appendages. The complex basal body plus its associated rootlets forms the kinetid. Kinetids are precisely oriented within a row in correlation with the cell polarity. Basal bodies also display a proximo-distal polarity with microtubule triplets at their proximal ends, surrounding a permanent cartwheel, and microtubule doublets at the transition zone located between the basal body and the cilium. Basal bodies remain anchored at the cell surface during the whole cell cycle. On the opposite to metazoan, there is no centriolar stage and new basal bodies develop anteriorly and at right angle from the base of the docked ones. Ciliogenesis follows a specific temporal pattern during the cell cycle and both unciliated and ciliated docked basal bodies can be observed in the same cell. The transition zone is particularly well organized with three distinct plates and a maturation of its structure is observed during the growth of the cilium. Transcriptomic and proteomic analyses have been performed in different organisms including Paramecium to understand the ciliogenesis process. The data have incremented a multi-organism database, dedicated to proteins involved in the biogenesis, composition and function of centrosomes, basal bodies or cilia. Thanks to its thousands of basal bodies and the well-known choreography of their duplication during the cell cycle, Paramecium has allowed pioneer studies focusing on the structural and functional processes underlying basal body duplication. Proteins involved in basal body anchoring are sequentially recruited to assemble the transition zone thus indicating that the anchoring process parallels the structural differentiation of the transition zone. This feature

  10. Swimming behavior regulation by GABAB receptors in Paramecium.

    PubMed

    Ramoino, Paola; Fronte, Paola; Beltrame, Francesco; Diaspro, Alberto; Fato, Marco; Raiteri, Luca; Stigliani, Sara; Usai, Cesare

    2003-12-10

    In Paramecium, internal Ca(2+) concentration increase coupled to membrane depolarization induces a reversal in the direction of ciliary beating and, consequently, a reversal in swimming direction. The ciliary reversal (CR) duration is correlated to Ca(2+) influx, and the addition of drugs that block the Ca(2+) current leads to a reduction in the backward swimming duration. In this study we have examined the possible function of GABA(B) receptors in P. primaurelia swimming control. The presence of GABA(B) immunoanalogue in Paramecium was evidenced using SDS-PAGE, Western blotting, and confocal laser scanning microscopy. By applying the specific GABA(B) receptor agonist baclofen, a dose-dependent inhibition of the membrane depolarization-induced CR duration was observed. This inhibition was antagonized by phaclofen, persisted when K(+) channel blockers were applied, and disappeared after treatment with nifedipine and verapamil. Moreover, the action of baclofen on depolarization-induced CR was suppressed by treatment with pertussis toxin. Therefore, these experiments suggest that baclofen modulates CR by a G protein (G(0) or G(1)) mediated inhibition of dihydropyridine-sensible calcium channels. Finally, synthesis and release of GABA in the environment by Paramecium have been demonstrated by HPLC. Possible correlations between GABA(B) receptor activation and the regulation of intracellular Ca(2+) levels are discussed. PMID:14644161

  11. Calcium channels in Paramecium aurelia.

    PubMed

    Schein, S J

    1977-01-01

    Reversal of swimming direction in paramecium is dependent on the calcium influx through the excitable-membrane calcium channels. Several mutants of Paramecium aurelia have been selected on the basis of their resistance to the paralyzing effect of barium. The mutants have reduced reversal behavior and are in the same three pawn genes as discovered by Kung (16, 17). Also, in barium solutions, the pawns live longer than the wild-type; however, pwB mutants are more resistant to barium toxicity than pwA mutants. These results suggest that the selection picked up mutants in the calcium channel. Electrophysiological studies demonstrate this point directly, showing defective calcium activation in all pawns, but also defective anomalous rectification in pwB mutants. A model is presented which accounts for the differences between pwA and pwB mutants. It ascribes the depolarization-sensitive "gate" function to the pwA gene product and the "pore" function to the pwB gene product. Additionally, the stability of the channel structure is demonstrated, channel half-life being from five to eight days. PMID:928443

  12. Swimming of Paramecium in confined channels

    NASA Astrophysics Data System (ADS)

    Jung, Sunghwan

    2012-02-01

    Many living organisms in nature have developed a few different swimming modes, presumably derived from hydrodynamic advantage. Paramecium is a ciliated protozoan covered by thousands of cilia with a few nanometers in diameter and tens of micro-meters in length and is able to exhibit both ballistic and meandering motions. First, we characterize ballistic swimming behaviors of ciliated microorganisms in glass capillaries of different diameters and explain the trajectories they trace out. We develop a theoretical model of an undulating sheet with a pressure gradient and discuss how it affects the swimming speed. Secondly, investigation into meandering swimmings within rectangular PDMS channels of dimension smaller than Paramecium length. We find that Paramecium executes a body-bend (an elastic buckling) using the cilia while it meanders. By considering an elastic beam model, we estimate and show the universal profile of forces it exerts on the walls. Finally, we discuss a few other locomotion of Paramecium in other extreme environments like gel.

  13. Paramecium swimming in capillary tube

    NASA Astrophysics Data System (ADS)

    Jana, Saikat; Um, Soong Ho; Jung, Sunghwan

    2012-04-01

    Swimming organisms in their natural habitat need to navigate through a wide range of geometries and chemical environments. Interaction with boundaries in such situations is ubiquitous and can significantly modify the swimming characteristics of the organism when compared to ideal laboratory conditions. We study the different patterns of ciliary locomotion in glass capillaries of varying diameter and characterize the effect of the solid boundaries on the velocities of the organism. Experimental observations show that Paramecium executes helical trajectories that slowly transition to straight lines as the diameter of the capillary tubes decreases. We predict the swimming velocity in capillaries by modeling the system as a confined cylinder propagating longitudinal metachronal waves that create a finite pressure gradient. Comparing with experiments, we find that such pressure gradient considerations are necessary for modeling finite sized ciliary organisms in restrictive geometries.

  14. Programmed Rearrangement in Ciliates: Paramecium.

    PubMed

    Betermier, Mireille; Duharcourt, Sandra

    2014-12-01

    Programmed genome rearrangements in the ciliate Paramecium provide a nice illustration of the impact of transposons on genome evolution and plasticity. During the sexual cycle, development of the somatic macronucleus involves elimination of ∼30% of the germline genome, including repeated DNA (e.g., transposons) and ∼45,000 single-copy internal eliminated sequences (IES). IES excision is a precise cut-and-close process, in which double-stranded DNA cleavage at IES ends depends on PiggyMac, a domesticated piggyBac transposase. Genome-wide analysis has revealed that at least a fraction of IESs originate from Tc/mariner transposons unrelated to piggyBac. Moreover, genomic sequences with no transposon origin, such as gene promoters, can be excised reproducibly as IESs, indicating that genome rearrangements contribute to the control of gene expression. How the system has evolved to allow elimination of DNA sequences with no recognizable conserved motif has been the subject of extensive research during the past two decades. Increasing evidence has accumulated for the participation of noncoding RNAs in epigenetic control of elimination for a subset of IESs, and in trans-generational inheritance of alternative rearrangement patterns. This chapter summarizes our current knowledge of the structure of the germline and somatic genomes for the model species Paramecium tetraurelia, and describes the DNA cleavage and repair factors that constitute the IES excision machinery. We present an overview of the role of specialized RNA interference machineries and their associated noncoding RNAs in the control of DNA elimination. Finally, we discuss how RNA-dependent modification and/or remodeling of chromatin may guide PiggyMac to its cognate cleavage sites. PMID:26104450

  15. Orienting Paramecium with intense static magnetic fields

    NASA Astrophysics Data System (ADS)

    Valles, James M., Jr.; Guevorkian, Karine; Quindel, Carl

    2004-03-01

    Recent experiments on cell division suggest the application of intense static magnetic fields as a novel tool for the manipulation of biological systems [1]. The magnetic field appears to couple to the intrinsic anisotropies in the diamagnetic components of the cells. Here, we present measurements of the intrinsic average diamagnetic anisotropy of the whole single celled ciliate, Paramecium Caudatum. Magnetic fields, 2.5 T < B < 8 T were applied to immobilized (non-swimming) Paramecium Caudatum that were suspended in a density matched medium. The organisms align with their long axis parallel to the applied magnetic field. Their intrinsic diamagnetic anisotropy is 3x10-11 in cgs units. We will discuss the implications of these results for employing magnetic fields to probe the behavior of swimming Paramecium. [1] J. M. Valles, Jr. et al., Expt. Cell Res.274, 112-118 (2002).

  16. Locomotion of Paramecium in patterned environments

    NASA Astrophysics Data System (ADS)

    Park, Eun-Jik; Eddins, Aja; Kim, Junil; Yang, Sung; Jana, Saikat; Jung, Sunghwan

    2011-10-01

    Ciliary organisms like Paramecium Multimicronucleatum locomote by synchronized beating of cilia that produce metachronal waves over their body. In their natural environments they navigate through a variety of environments especially surfaces with different topology. We study the effects of wavy surfaces patterned on the PDMS channels on the locomotive abilities of Paramecium by characterizing different quantities like velocity amplitude and wavelength of the trajectories traced. We compare this result with the swimming characteristics in straight channels and draw conclusions about the effects of various patterned surfaces.

  17. Paramecium swimming in a capillary tube

    NASA Astrophysics Data System (ADS)

    Jana, Saikat; Jung, Sunghwan

    2010-03-01

    Micro-organisms exhibit different strategies for swimming in complex environments. Many micro-swimmers such as paramecium congregate and tend to live near wall. We investigate how paramecium moves in a confined space as compared to its motion in an unbounded fluid. A new theoretical model based on Taylor's sheet is developed, to study such boundary effects. In experiments, paramecia are put inside capillary tubes and their swimming behavior is observed. The data obtained from experiments is used to test the validity of our theoretical model and understand how the cilia influence the locomotion of paramecia in confined geometries.

  18. Mutagenicity of fly ash particles in Paramecium

    SciTech Connect

    Smith-Sonneborn, J.; Palizzi, R.A.; Herr, C.; Fisher, G.L.

    1981-01-09

    Paramecium, a protozoan that ingests nonnutritive particulate matter, was used to determine the mutagenicity of fly ash. Heat treatment inactivated mutagens that require metabolic conversion to their active form but did not destroy all mutagenicity. Extraction of particles with hydrochloric acid, but not dimethyl sulfoxide, removed detectable mutagenic activity.

  19. Roll and Yaw of Paramecium swimming in a viscous fluid

    NASA Astrophysics Data System (ADS)

    Jung, Sunghwan; Jana, Saikat; Giarra, Matt; Vlachos, Pavlos

    2012-11-01

    Many free-swimming microorganisms like ciliates, flagellates, and invertebrates exhibit helical trajectories. In particular, the Paramecium spirally swims along its anterior direction by the beating of cilia. Due to the oblique beating stroke of cilia, the Paramecium rotates along its long axis as it swims forward. Simultaneously, this long axis turns toward the oral groove side. Combined roll and yaw motions of Paramecium result in swimming along a spiral course. Using Particle Image Velocimetry, we measure and quantify the flow field and fluid stress around Paramecium. We will discuss how the non-uniform stress distribution around the body induces this yaw motion.

  20. Orientation of Paramecium under the conditions of weightlessness.

    PubMed

    Hemmersbach-Krause, R; Briegleb, W; Hader, D P; Vogel, K; Grothe, D; Meyer, I

    1993-01-01

    A cell culture of Paramecium with a precise negative gravitaxis was exposed to 4 x l0(-6) g during a parabolic flight of a sounding rocket for 6 min. Computer image analysis revealed that without gravity stimulus the individual swimming paths remained straight. In addition, three reactions could be distinguished. For about 30 s, paramecia maintained the swimming direction they had before onset of low gravity. During the next 20 s, an approximate reversal of the swimming direction occurred. This period was followed by the expected random swimming pattern. Similar behavior was observed under the condition of simulated weightlessness on a fast-rotating clinostat. Control experiments on the ground under hyper-gravity on a low-speed centrifuge microscope and on a vibration test facility proved that the observed effects were caused exclusively by the reduction of gravity. PMID:11536536

  1. Effect of confinements: Bending in Paramecium

    NASA Astrophysics Data System (ADS)

    Eddins, Aja; Yang, Sung; Spoon, Corrie; Jung, Sunghwan

    2012-02-01

    Paramecium is a unicellular eukaryote which by coordinated beating of cilia, generates metachronal waves which causes it to execute a helical trajectory. We investigate the swimming parameters of the organism in rectangular PDMS channels and try to quantify its behavior. Surprisingly a swimming Paramecium in certain width of channels executes a bend of its flexible body (and changes its direction of swimming) by generating forces using the cilia. Considering a simple model of beam constrained between two walls, we predict the bent shapes of the organism and the forces it exerts on the walls. Finally we try to explain how bending (by sensing) can occur in channels by conducting experiments in thin film of fluid and drawing analogy to swimming behavior observed in different cases.

  2. A theory of gravikinesis in paramecium

    NASA Astrophysics Data System (ADS)

    Machemer, H.

    The archaic eukaryote unicellular microorganism, Paramecium, is propelled by thousands of cilia, which are regulated by modulation of the membrane potential. Ciliates can successfully cope with gravity, which is the phylogenetically oldest stimulus for living things. One mechanism for overcoming sedimentation is negative gravitaxis, an orientational response antiparallel to the gravity vector. We have postulated the existence of a negative gravikinesis in Paramecium, i.e. a modulation of swimming speed as a function of cellular orientation in space. With negative gravikinesis, an upward oriented cell actively augments the rate of forward swimming and depresses active locomotion during downward orientation. A brief outline of the gravikinesis hypothesis is given on a quantitative basis and experimental data are presented which have confirmed the major assumptions.

  3. A theory of gravikinesis in Paramecium.

    PubMed

    Machemer, H

    1996-01-01

    The archaic eukaryote unicellular microorganism, Paramecium, is propelled by thousands of cilia, which are regulated by modulation of the membrane potential. Ciliates can successfully cope with gravity, which is the phylogenetically oldest stimulus for living things. One mechanism for overcoming sedimentation is negative gravitaxis, an orientational response antiparallel to the gravity vector. We have postulated the existence of a negative gravikinesis in Paramecium, i.e. a modulation of swimming speed as a function of cellular orientation in space. With negative gravikinesis, an upward oriented cell actively augments the rate of forward swimming and depresses active locomotion during downward orientation. A brief outline of the gravikinesis hypothesis is given on a quantitative basis and experimental data are presented which have confirmed the major assumptions. PMID:11538602

  4. Membrane potential changes during chemokinesis in Paramecium.

    PubMed

    Van Houten, J

    1979-06-01

    Intracellular recordings show that (i) paramecia hyperpolarize slightly in attractants and depolarize in repellents that depend on the avoiding reaction (an abrupt change of swimming direction), and (ii) paramecia more strongly hyperpolarize in repellents and more strongly depolarize in attractants that depend on changes of swimming velocity. These membrane potential changes are in agreement with a hypothesis of membrane potential control of chemokinesis in Paramecium. PMID:572085

  5. Somersault of Paramecium in extremely confined environments

    PubMed Central

    Jana, Saikat; Eddins, Aja; Spoon, Corrie; Jung, Sunghwan

    2015-01-01

    We investigate various swimming modes of Paramecium in geometric confinements and a non-swimming self-bending behavior like a somersault, which is quite different from the previously reported behaviors. We observe that Paramecia execute directional sinusoidal trajectories in thick fluid films, whereas Paramecia meander around a localized region and execute frequent turns due to collisions with adjacent walls in thin fluid films. When Paramecia are further constrained in rectangular channels narrower than the length of the cell body, a fraction of meandering Paramecia buckle their body by pushing on the channel walls. The bucking (self-bending) of the cell body allows the Paramecium to reorient its anterior end and explore a completely new direction in extremely confined spaces. Using force deflection method, we quantify the Young’s modulus of the cell and estimate the swimming and bending powers exerted by Paramecium. The analysis shows that Paramecia can utilize a fraction of its swimming power to execute the self-bending maneuver within the confined channel and no extra power may be required for this new kind of self-bending behavior. This investigation sheds light on how micro-organisms can use the flexibility of the body to actively navigate within confined spaces. PMID:26286234

  6. Somersault of Paramecium in extremely confined environments.

    PubMed

    Jana, Saikat; Eddins, Aja; Spoon, Corrie; Jung, Sunghwan

    2015-01-01

    We investigate various swimming modes of Paramecium in geometric confinements and a non-swimming self-bending behavior like a somersault, which is quite different from the previously reported behaviors. We observe that Paramecia execute directional sinusoidal trajectories in thick fluid films, whereas Paramecia meander around a localized region and execute frequent turns due to collisions with adjacent walls in thin fluid films. When Paramecia are further constrained in rectangular channels narrower than the length of the cell body, a fraction of meandering Paramecia buckle their body by pushing on the channel walls. The bucking (self-bending) of the cell body allows the Paramecium to reorient its anterior end and explore a completely new direction in extremely confined spaces. Using force deflection method, we quantify the Young's modulus of the cell and estimate the swimming and bending powers exerted by Paramecium. The analysis shows that Paramecia can utilize a fraction of its swimming power to execute the self-bending maneuver within the confined channel and no extra power may be required for this new kind of self-bending behavior. This investigation sheds light on how micro-organisms can use the flexibility of the body to actively navigate within confined spaces. PMID:26286234

  7. Somersault of Paramecium in extremely confined environments

    NASA Astrophysics Data System (ADS)

    Jana, Saikat; Eddins, Aja; Spoon, Corrie; Jung, Sunghwan

    2015-08-01

    We investigate various swimming modes of Paramecium in geometric confinements and a non-swimming self-bending behavior like a somersault, which is quite different from the previously reported behaviors. We observe that Paramecia execute directional sinusoidal trajectories in thick fluid films, whereas Paramecia meander around a localized region and execute frequent turns due to collisions with adjacent walls in thin fluid films. When Paramecia are further constrained in rectangular channels narrower than the length of the cell body, a fraction of meandering Paramecia buckle their body by pushing on the channel walls. The bucking (self-bending) of the cell body allows the Paramecium to reorient its anterior end and explore a completely new direction in extremely confined spaces. Using force deflection method, we quantify the Young’s modulus of the cell and estimate the swimming and bending powers exerted by Paramecium. The analysis shows that Paramecia can utilize a fraction of its swimming power to execute the self-bending maneuver within the confined channel and no extra power may be required for this new kind of self-bending behavior. This investigation sheds light on how micro-organisms can use the flexibility of the body to actively navigate within confined spaces.

  8. Aligning Paramecium caudatum with static magnetic fields.

    PubMed

    Guevorkian, Karine; Valles, James M

    2006-04-15

    As they negotiate their environs, unicellular organisms adjust their swimming in response to various physical fields such as temperature, chemical gradients, and electric fields. Because of the weak magnetic properties of most biological materials, however, they do not respond to the earth's magnetic field (5 x 10(-5) Tesla) except in rare cases. Here, we show that the trajectories of Paramecium caudatum align with intense static magnetic fields >3 Tesla. Otherwise straight trajectories curve in magnetic fields and eventually orient parallel or antiparallel to the applied field direction. Neutrally buoyant immobilized paramecia also align with their long axis in the direction of the field. We model this magneto-orientation as a strictly passive, nonphysiological response to a magnetic torque exerted on the diamagnetically anisotropic components of the paramecia. We have determined the average net anisotropy of the diamagnetic susceptibility, Deltachi(p), of a whole Paramecium: Deltachi(p) = (6.7+/- 0.7) x 10(-23) m(3). We show how the measured Deltachi(p) compares to the anisotropy of the diamagnetic susceptibilities of the components in the cell. We suggest that magnetic fields can be exploited as a novel, noninvasive, quantitative means to manipulate swimming populations of unicellular organisms. PMID:16461406

  9. Methods for Studying Ciliary-Mediated Chemoresponse in Paramecium.

    PubMed

    Valentine, Megan Smith; Van Houten, Judith L

    2016-01-01

    Paramecium is a useful model organism for the study of ciliary-mediated chemical sensing and response. Here we describe ways to take advantage of Paramecium to study chemoresponse.Unicellular organisms like the ciliated protozoan Paramecium sense and respond to chemicals in their environment (Van Houten, Ann Rev Physiol 54:639-663, 1992; Van Houten, Trends Neurosci 17:62-71, 1994). A thousand or more cilia that cover Paramecium cells serve as antennae for chemical signals, similar to ciliary function in a large variety of metazoan cell types that have primary or motile cilia (Berbari et al., Curr Biol 19(13):R526-R535, 2009; Singla V, Reiter J, Science 313:629-633, 2006). The Paramecium cilia also produce the motor output of the detection of chemical cues by controlling swimming behavior. Therefore, in Paramecium the cilia serve multiple roles of detection and response.We present this chapter in three sections to describe the methods for (1) assaying populations of cells for their behavioral responses to chemicals (attraction and repulsion), (2) characterization of the chemoreceptors and associated channels of the cilia using proteomics and binding assays, and (3) electrophysiological analysis of individual cells' responses to chemicals. These methods are applied to wild type cells, mutants, transformed cells that express tagged proteins, and cells depleted of gene products by RNA Interference (RNAi). PMID:27514921

  10. Bioconvection and front formation of Paramecium tetraurelia

    NASA Astrophysics Data System (ADS)

    Kitsunezaki, So; Komori, Rie; Harumoto, Terue

    2007-10-01

    We have investigated the bioconvection of Paramecium tetraurelia in high-density suspensions made by centrifugal concentration. When a suspension is kept at rest in a Hele-Shaw cell, a crowded front of paramecia is formed in the vicinity of the bottom and it propagates gradually toward the water-air interface. Fluid convection occurs under this front, and it is driven persistently by the upward swimming of paramecia. The roll structures of the bioconvection become turbulent with an increase in the depth of the suspension; they also change rapidly as the density of paramecia increases. Our experimental results suggest that lack of oxygen in the suspension causes the active individual motions of paramecia to induce the formation of this front.

  11. Simulation of Paramecium Chemotaxis Exposed to Calcium Gradients.

    PubMed

    Sarvestani, Ali N; Shamloo, Amir; Ahmadian, Mohammad Taghi

    2016-06-01

    Paramecium or other ciliates have the potential to be utilized for minimally invasive surgery systems, making internal body organs accessible. Paramecium shows interesting responses to changes in the concentration of specific ions such as K(+), Mg(2+), and Ca(2+) in the ambient fluid. Some specific responses are observed as, changes in beat pattern of cilia and swimming toward or apart from the ion source. Therefore developing a model for chemotactic motility of small organisms is necessary in order to control the directional movements of these microorganisms before testing them. In this article, we have developed a numerical model, investigating the effects of Ca(2+) on swimming trajectory of Paramecium. Results for Ca(2+)-dependent chemotactic motility show that calcium gradients are efficient actuators for controlling the Paramecium swimming trajectory. After applying a very low Ca(2+) gradient, a directional chemotaxis of swimming Paramecium is observable in this model. As a result, chemotaxis is shown to be an efficient method for controlling the propulsion of these small organisms. PMID:26983824

  12. Divalent cation affinity sites in Paramecium aurelia.

    PubMed

    Fisher, G; Kaneshiro, E S; Peters, P D

    1976-05-01

    Sites with high calcium affinity in Paramecium aurelia were identified by high calcium (5 mM) fixation and electron microscope methods. Electron-opaque deposits were observed on the cytoplasmic side of surface membranes, particularly at the basal regions of cilia and trichocyst-pellicle fusion sites. Deposits were also observed on some smooth cytomembranes, within the axoneme of cilia, and on basal bodies. The divalent cations, Mg2+, Mn2+, Sr2+, Ni2+, Ba2+, and Zn2+, could be substituted for Ca2+ in the procedure. Deposits were larger with 5 mM Sr2+. Ba2+, and Mn2+ at ciliary transverse plates and the terminal plate of basal bodies. Microprobe analysis showed that Ca and C1 were concentrated within deposits. In some analyses, S and P were detected in deposits. Also, microprobe analysis of 5 mM Mn2+-fixed P. aurelia showed that those deposits were enriched in Mn and C1 and sometimes enriched in P. Deposits were seen only when the ciliates were actively swimming at the time of fixation. Locomotory mutants having defective membrane Ca-gating mechanisms and ciliates fixed while exhibiting ciliary reversal showed no obvious differences in deposition pattern and intensity. Possible correlations between electron-opaque deposits and the locations of intramembranous particles seen by freeze-fracture studied, as well as sites where fibrillar material associate with membranes are considered. The possibility that the action sites of calcium and other divalent cations were identified is discussed. PMID:1262398

  13. Cell proliferation of Paramecium tetraurelia on a slow rotating clinostat

    NASA Astrophysics Data System (ADS)

    Sawai, Satoe; Mogami, Yoshihiro; Baba, Shoji A.

    Paramecium is known to proliferate faster under microgravity conditions, and slower under hypergravity. Experiments using axenic culture medium have demonstrated that hypergravity affected directly on the proliferation of Paramecium itself. In order to assess the mechanisms underlying the physiological effects of gravity on cell proliferation, Paramecium tetraurelia was grown under clinorotation (2.5 rpm) and the time course of the proliferation was investigated in detail on the basis of the logistic analysis. On the basis of the mechanical properties of Paramecium, this slow rate of the rotation appears to be enough to simulate microgravity in terms of the randomization of the cell orientation with respect to gravity. P. tetraurelia was cultivated in a closed chamber in which cells were confined without air bubbles, reducing the shear forces and turbulences under clinorotation. The chamber is made of quartz and silicone rubber film; the former is for the optically-flat walls for the measurement of cell density by means of a non-invasive laser optical-slice method, and the latter for gas exchange. Because of the small dimension for culture space, Paramecium does not accumulate at the top of the chamber in spite of its known negative gravitactic behavior. We measured the cell density at regular time intervals without breaking the configuration of the chamber, and analyzed the proliferation parameters by fitting the data to a logistic equation. As a result, P. tetraurelia showed reduced proliferation under slow clinorotation. The saturation of the cell density as well as the maximum proliferation rate decreased, although we found no significant changes on the half maximal time for proliferation. We also found that the mean swimming velocity decreased under slow clinorotation. These results were not consistent with those under microgravity and fast rotating clinostat. This may suggest that randomization of the cell orientation performed by slow rotating clinostat has

  14. Pb2+ Modulates Ca2+ Membrane Permeability In Paramecium

    NASA Astrophysics Data System (ADS)

    Bernal-Martínez, Juan; Ortega Soto, Arturo

    2004-09-01

    Intracellular recording experiments in current clamp configuration were done to evaluate whether Pb2+ modulates ionic membrane permeability in the fresh water Paramecium tetraurelia. It was found that Pb2+ triggers in a dose-dependent manner, a burst of spontaneous action potentials followed by a robust and sustained after hyper-polarization. In addition, Pb2+ increased the frequency of firing the spontaneous Ca2+-Action Potential and also, the duration of Ca2+-Action Potential, in a dose and reversibly-dependent manner. These results suggest that Pb2+ increases calcium membrane permeability of Paramecium and probably activates a calcium-dependent-potassium conductance in the ciliate.

  15. Graviresponses of Paramecium biaurelia during parabolic flights.

    PubMed

    Krause, Martin; Bräucker, Richard; Hemmersbach, Ruth

    2006-12-01

    The thresholds of graviorientation and gravikinesis in Paramecium biaurelia were investigated during the 5th DLR (German Aerospace Center) parabolic-flight campaign at Bordeaux in June 2003. Parabolic flights are a useful tool for the investigation of swimming behaviour in protists at different accelerations. At normal gravity (1 g) and hypergravity (1 g to 1.8 g), precision of orientation and locomotion rates depend linearly on the applied acceleration as seen in earlier centrifuge experiments. After transition from hypergravity to decreased gravity (minimal residual acceleration of <10(-2) g), graviorientation as well as gravikinesis show a full relaxation with different kinetics. The use of twelve independent cell samples per flight guarantees high data numbers and secures the statistical significance of the obtained data. The relatively slow change of acceleration between periods of microgravity and hypergravity (0.4 g/s) enabled us to determine the thresholds of graviorientation at 0.6 g and of gravikinesis at 0.4 g. The gravity-unrelated propulsion rate of the sample was found to be 874 microm/s, exceeding the locomotion rate of horizontally swimming cells (855 microm/s). The measured thresholds of graviresponses were compared with data obtained from earlier centrifuge experiments on the sounding rocket Maxus-2. Measured thresholds of gravireactions indicate that small energies, close to the thermal noise level, are sufficient for the gravitransduction process. Data from earlier hypergravity experiments demonstrate that mechanosensitive ion channels are functioning over a relative wide range of acceleration. From this, we may speculate that gravireceptor channels derive from mechanoreceptor channels. PMID:17180491

  16. Cell proliferation of Paramecium tetraurelia under simulated microgravity

    NASA Astrophysics Data System (ADS)

    Sawai, S.; Mogami, Y.; Baba, S. A.

    Paramecium is known to proliferate faster under microgravity in space and slower under hypergravity Experiments using axenic culture medium have demonstrated that the hypergravity affected directly on the proliferation of Paramecium itself Kato et al 2003 In order to assess the mechanisms underlying the physiological effects of gravity on cell proliferation Paramecium tetraurelia was grown under simulated microgravity performed by clinorotation and the time course of the proliferation was investigated in detail on the basis of the logistic analysis P tetraurelia was cultivated in a closed chamber in which cells were confined without air babbles reducing the shear stresses and turbulence under the rotation The chamber is made of quartz and silicone rubber film the former is for the optically-flat walls for the measurement of cell density by means of a non-invasive laser optical-slice method and the latter for gas exchange Because the closed chamber has an inner dimension of 3 times 3 times 60 mm Paramecium does not accumulate at the top of the chamber despite its negative gravitactic behavior We measured the cell density at regular time intervals without breaking the configuration of the chamber and analyzed the proliferation parameters by fitting the data to a logistic equation Clinorotation had the effects of reducing the proliferation of P tetraurelia It reduced both the saturation cell density and the maximum proliferation rate although it had little effect on the

  17. Detecting the gravitational sensitivity of Paramecium caudatum using magnetic forces

    NASA Astrophysics Data System (ADS)

    Guevorkian, Karine; Valles, James M., Jr.

    2006-03-01

    Under normal conditions, Paramecium cells regulate their swimming speed in response to the pN level mechanical force of gravity. This regulation, known as gravikinesis, is more pronounced when the external force is increased by methods such as centrifugation. Here we present a novel technique that simulates gravity fields using the interactions between strong inhomogeneous magnetic fields and cells. We are able to achieve variable gravities spanning from 10xg to -8xg; where g is earth's gravity. Our experiments show that the swimming speed regulation of Paramecium caudatum to magnetically simulated gravity is a true physiological response. In addition, they reveal a maximum propulsion force for paramecia. This advance establishes a general technique for applying continuously variable forces to cells or cell populations suitable for exploring their force transduction mechanisms.

  18. Cytotoxicity assessment of monocrotophos in Paramecium caudatum and Oxytricha fallax.

    PubMed

    Amanchi, Nageswara Rao; Hussain, Mohd Masood

    2010-09-01

    Experiments were conducted to evaluate the toxic effects ofmonocrotophos in ciliate models Paramecium caudatum and Oxytricha fallax. In acute toxicity studies higherconcentrations of monocrotophos caused marked increase in mobility of cells exhibiting rocking movements within two mins of exposure but were decreased after 30 mins. LC50 value by mortality curve for 3 hr acute toxicity test of Oxytricha fallax and Paramecium caudatum was found 307.744 +/- 33.27 mg l(-1) and 332.284 +/- 57.52 mg l(-1) respectively. Oxytricha fallax was found sensitive than Paramecium caudatum to monocrotophos. In acute exposure cells showed deformities such as swelling, oval shaped deformity and in higher concentrations shortening of longitudinal axis with blackening of cytoplasm occurred. The length of paramecia was reduced prominently. Similarly enlargement of contractile vacuole and stress egestion of food vacuoles was also observed. The morphological studies showed the changes in shape, size, colour and width of Paramecia and Oxytricha. Frequencies of macronuclear aberrations were significant showing deformities such as rod shaped, elongation, fragmentation, diffusion and total absence of nucleus and were concentration dependent. The data provided in the present study on interaction of pesticides with nuclear structure can be of immense value because most of these pesticides have been reported to have carcinogenic, mutagenic and teratogenic properties. PMID:21387909

  19. Transitions between three swimming gaits in Paramecium escape.

    PubMed

    Hamel, Amandine; Fisch, Cathy; Combettes, Laurent; Dupuis-Williams, Pascale; Baroud, Charles N

    2011-05-01

    Paramecium and other protists are able to swim at velocities reaching several times their body size per second by beating their cilia in an organized fashion. The cilia beat in an asymmetric stroke, which breaks the time reversal symmetry of small scale flows. Here we show that Paramecium uses three different swimming gaits to escape from an aggression, applied in the form of a focused laser heating. For a weak aggression, normal swimming is sufficient and produces a steady swimming velocity. As the heating amplitude is increased, a higher acceleration and faster swimming are achieved through synchronized beating of the cilia, which begin by producing oscillating swimming velocities and later give way to the usual gait. Finally, escape from a life-threatening aggression is achieved by a "jumping" gait, which does not rely on the cilia but is achieved through the explosive release of a group of trichocysts in the direction of the hot spot. Measurements through high-speed video explain the role of trichocysts in defending against aggressions while showing unexpected transitions in the swimming of microorganisms. These measurements also demonstrate that Paramecium optimizes its escape pattern by taking advantage of its inertia. PMID:21464291

  20. Ciliary heterogeneity within a single cell: the Paramecium model.

    PubMed

    Aubusson-Fleury, Anne; Cohen, Jean; Lemullois, Michel

    2015-01-01

    Paramecium is a single cell able to divide in its morphologically differentiated stage that has many cilia anchored at its cell surface. Many thousands of cilia are thus assembled in a short period of time during division to duplicate the cell pattern while the cell continues swimming. Most, but not all, of these sensory cilia are motile and involved in two main functions: prey capture and cell locomotion. These cilia display heterogeneity, both in their length and their biochemical properties. Thanks to these properties, as well as to the availability of many postgenomic tools and the possibility to follow the regrowth of cilia after deciliation, Paramecium offers a nice opportunity to study the assembly of the cilia, as well as the genesis of their diversity within a single cell. In this paper, after a brief survey of Paramecium morphology and cilia properties, we describe the tools and the protocols currently used for immunofluorescence, transmission electron microscopy, and ultrastructural immunocytochemistry to analyze cilia, with special recommendations to overcome the problem raised by cilium diversity. PMID:25837404

  1. Effects of perfluorinated amphiphiles on backward swimming in Paramecium caudatum

    SciTech Connect

    Matsubara, Eriko; Harada, Kouji; Inoue, Kayoko; Koizumi, Akio . E-mail: koizumi@pbh.med.kyoto-u.ac.jp

    2006-01-13

    PFOS and PFOA are ubiquitous contaminants in the environment. We investigated the effects of fluorochemicals on calcium currents in Paramecium caudatum using its behavioral changes. Negatively charged amphiphiles prolonged backward swimming (BWS) of Paramecium. PFOS significantly prolonged BWS, while PFOA was less potent (EC{sub 5}: 29.8 {+-} 4.1 and 424.1 {+-} 124.0 {mu}M, respectively). The BWS prolongation was blocked by cadmium, indicating that the cellular calcium conductance had been modified. The positively charged amphiphile FOSAPrTMA shortened BWS (EC{sub 5}: 19.1 {+-} 17.3). Nonionic amphiphiles did not affect BWS. The longer-chain perfluorinated carboxylates PFNA and PFDA were more potent than PFOA (EC{sub 5}: 98.7 {+-} 20.1 and 60.4 {+-} 10.1 {mu}M, respectively). However, 1,8-perfluorooctanedioic acid and 1,10-perfluorodecanedioic acid did not prolong BWS. The critical micelle concentration (CMC) and BWS prolongation for negatively charged amphiphiles showed a clear correlation (r {sup 2} = 0.8008, p < 0.001). In summary, several perfluorochemicals and PFOS and PFOA had similar effects in Paramecium, while chain length, CMC, and electric charge were major determinants of BWS duration.

  2. Fine oral filaments in Paramecium: a biochemical and immunological analysis.

    PubMed

    Clerot, J; Iftode, F; Budin, K; Jeanmaire-Wolf, R; Coffe, G; Fleury-Aubusson, A

    2001-01-01

    In Paramecium, several kinds of the oral networks of fine filaments are defined at the ultrastructural level. Using the sodium chloride-treated oral apparatus of Paramecium as an antigen to produce monoclonal antibodies, we have begun to identify the proteins constituting these networks. Immunoblotting showed that all positive antibodies were directed against three bands (70-, 75-and 83-kD), which corresponded to quantitatively minor components of the antigen; there was no antibody specific for the quantitatively major components (58- and 62-kD). Immunolocalization with four of these antibodies directed against one or several of these three bands showed that these proteins are components of the fine filaments supporting the oral area; a decoration of the basal bodies and the outer lattice was also observed on the cortex. Immunofluorescence on interphase cells suggested that the three proteins colocalized on the left side of the oral apparatus, whereas only the 70-kD band was detected on the right side. During division, the antigens of the antibodies were detected at different stages after oral basal body assembly. The antibodies cross-reacted with the tetrins, which are oral filament-forming proteins in Tetrahymena, demonstrating that tetrin-related proteins are quantitatively minor components of the oral and the somatic cytoskeleton of Paramecium. PMID:12095113

  3. Species Identity of Commercial Stocks of Paramecium in the U.S.

    ERIC Educational Resources Information Center

    Cole, Thomas A.; And Others

    1992-01-01

    Describes how paramecium can be identified through the use of DNA-binding fluorescent compounds. The authors used these techniques to test the paramecium stocks from 12 commercial sources. The details of the staining procedures and the results of the commercial tests are presented in this article. (PR)

  4. An UPF3-based nonsense-mediated decay in Paramecium.

    PubMed

    Contreras, Julia; Begley, Victoria; Macias, Sandra; Villalobo, Eduardo

    2014-12-01

    Nonsense-mediated decay recognises mRNAs containing premature termination codons. One of its components, UPF3, is a molecular link bridging through its binding to the exon junction complex nonsense-mediated decay and splicing. In protists UPF3 has not been identified yet. We report that Paramecium tetraurelia bears an UPF3 gene and that it has a role in nonsense-mediated decay. Interestingly, the identified UPF3 has not conserved the essential amino acids required to bind the exon junction complex. Though, our data indicates that this ciliate bears genes coding for core proteins of the exon junction complex. PMID:25463387

  5. Analysis of amino acid and codon usage in Paramecium bursaria.

    PubMed

    Dohra, Hideo; Fujishima, Masahiro; Suzuki, Haruo

    2015-10-01

    The ciliate Paramecium bursaria harbors the green-alga Chlorella symbionts. We reassembled the P. bursaria transcriptome to minimize falsely fused transcripts, and investigated amino acid and codon usage using the transcriptome data. Surface proteins preferentially use smaller amino acid residues like cysteine. Unusual synonymous codon and amino acid usage in highly expressed genes can reflect a balance between translational selection and other factors. A correlation of gene expression level with synonymous codon or amino acid usage is emphasized in genes down-regulated in symbiont-bearing cells compared to symbiont-free cells. Our results imply that the selection is associated with P. bursaria-Chlorella symbiosis. PMID:26341535

  6. Longevity of a Paramecium cell clone in space: Hypergravity experiments as a basis for microgravity experiments

    NASA Astrophysics Data System (ADS)

    Kato, Yuko; Mogami, Yoshihiro; Baba, Shoji A.

    We proposed a space experiment aboard International Space Station to explore the effects of microgravity on the longevity of a Paramecium cell clone. Earlier space experiments in CYTOS and Space Lab D-1 demonstrated that Paramecium proliferated faster in space. In combination with the fact that aging process in Paramecium is largely related to the fission age, the results of the proliferation experiment in space may predict that the longevity of Paramecium decreases when measured by clock time. In preparation of the space experiment, we assessed the aging process under hypergravity, which is known to reduce the proliferation rate. As a result, the length of autogamy immaturity increased when measured by clock time, whereas it remained unchanged by fission age. It is therefore expected that autogamy immaturity in the measure of the clock time would be shortened under microgravity. Since the length of clonal life span of Paramecium is related to the length of autogamy immaturity, the result of hypergravity experiment supports the prediction that the clonal longevity of Paramecium under microgravity decreases. Effects of gravity on proliferation are discussed in terms of energetics of swimming during gravikinesis and gravitaxis of Paramecium.

  7. Cytoplasmic streaming direction reverses in dividing Paramecium bursaria.

    PubMed

    Sikora, J; Wasik, A; Zajaczkowska, M

    1991-11-29

    Using the interference-contrast videomicroscopy the speed of cytoplasmic streaming was measured during the sequence of division stages in thigmotactically settled specimens of Paramecium bursaria. The speed of cytoplasmic flow gradually decreased during the first stages of binary fission and movement became indistinguishable at stage D(3). Almost at the same time cytoplasm started to move in the opposite direction, pushing or pulling the dividing micronucleus into the prospective posterior daughter cell and eventually stopped at stage D(5)-D(6). Further cell division events proceeded without detectable movement of cytoplasmic components. Cytoplasmic streaming in the normal interphase route was gradually restored in daughter cells about 30-40 min after cell separation. During the whole period of binary fission phagocytosis was arrested. Transportation and participation in the positioning of prospective micronuclei in daughter cells seems to be the main function of cytoplasmic streaming activity in cell division of Paramecium bursaria. The possible relationship between the stages of cytoskeleton transitions and the kinetics of cytoplasmic streaming associated with cell divison is discussed. PMID:23194845

  8. Structural and functional characterization of paramecium dynein: initial studies.

    PubMed

    Larsen, J; Barkalow, K; Hamasaki, T; Satir, P

    1991-01-01

    Dynein arms and isolated dynein from Paramecium tetraurelia ciliary axonemes are comparable in structure, direction of force generation, and microtubule translocation ability to other dyneins. In situ arms have dimensions and substructure similar to those of Tetrahymena. Based on spoke arrangement in intact axonemes, arms translocate axonemal microtubules in sliding such that active dynein arms are (-) end directed motors and the doublet to which the body and cape of the arms binds (N) translocates the adjacent doublet (N + 1) tipward. After salt extraction, based on ATPase activity, paramecium dynein is found as a 22S and a 14S species. The 22S dynein is a three-headed molecule that has unfolded from the in situ dimensions; the 14S dynein is single headed. Both dyneins can be photocleaved by UV light (350 nm) in the presence of Mg2+, ATP and vanadate; the photocleavage pattern of 22S dynein differs from that seen with Tetrahymena. Both isolated dyneins translocate taxol-stabilized, bovine brain microtubules in vitro. Under standard conditions, 22S dynein, like comparable dyneins from other organisms, translocates at velocities that are about three times faster than 14S dynein. PMID:1825507

  9. Hydrostatic pressure reversibly blocks membrane control of ciliary motility in Paramecium.

    PubMed

    Otter, T; Salmon, E D

    1979-10-19

    A hydrostatic pressure of only 68 atmospheres prevented swimming Paramecium caudatum from "avoiding" or reversing direction; 170 atmospheres stopped or decreased forward velocity by more than 75 percent. A decompression of 40 atmospheres invoked a single reversal, even at ,80 atmospheres. In contrast, 170 atmospheres did not significantly affect swimming behavior of paramecium "models" that were reactivated in a solution containing adenosine triphosphate and magnesium ions after their membrane had been disrupted by Triton X-100. PMID:482945

  10. Longevity of Paramecium Cell Clone under Microgravity in Space: Hypergravity Experiment as a Ground Simulation

    NASA Astrophysics Data System (ADS)

    Kato, Y.; Mogami, Y.; Baba, S. A.

    We proposed a space experiment aboard International Space Station to explore the effects of the stay under microgravity on the longevity of Paramecium cell clone (Mogami et al., 1999, Adv. Space Res., 23/12, 2087-2090). Former space experiments in CYTOS and Space Lab D-1 demonstrated that Paramecium proliferated faster in space. In combination with the fact that aging process in Paramecium is largely related to the fission age, the results of the proliferation experiment in space may predict that the longevity of Paramecium decreases when measured by clock time. As a ground simulation of the space experiment, we made an experiment to assess the aging process under hypergravity, which is known to reduce the proliferation rate. As a result, the length of autogamy immaturity increased when measured by clock time, whereas it remained unchanged by fission age (Kato et al., 2003, Zool. Sci., 1373-1380). It is therefore expected that autogamy immaturity in the measure of the clock time would be shortened under microgravity. Since the length of clonal life span of Paramecium is related to the length of autogamy immaturity, the result of hypergravity experiment may support the prediction above; i.e. a decrease in the clonal longevity of Paramecium under microgravity in space.

  11. Hierarchical organization of noise generates spontaneous signal in Paramecium cell.

    PubMed

    Ooyama, Shunsuke; Shibata, Tatsuo

    2011-08-21

    In many cellular processes, spontaneous activities are often the basis for their functioning. Paramecium cells change their swimming direction under a homogeneous environment, which is induced by a spontaneous signal generation in the membrane electric potential. For such a spontaneous activity, a theoretical model has been proposed by Oosawa (2007) [Biosystems 88, 191-201.], in which intracellular noise is hierarchically organized from thermal fluctuations to spike-like large fluctuations, which induces a signal to change spontaneously the swimming direction. Our analysis of the model shows that the system is a kind of excitable media, in which a spike is induced by a stochastic fluctuation. We show conditions of channels properties to have a spike train. PMID:21620864

  12. Ionic mechanisms controlling behavioral responses of paramecium to mechanical stimulation.

    PubMed

    Naitoh, Y; Eckert, R

    1969-05-23

    A mechanical stimulus applied to the anterior part of Paramecium causes a transient increase in membrane permeability to calcium. This permits a calcium current to flow into the cell, causing the membrane potential to approach the equilibrium level for calcium. The transient depolarization which results elicits a reversal in the direction of ciliary beat. When the organisms are free-swimming this is seen as the reversed locomotion of Jennings' "avoiding reaction." In contrast, a mechanical stimulus applied to the posterior part results in increased permeability to potassium ions, and hence an outward potassium current. The hyperpolarization which results causes an increase in the frequency of ciliary beat in the normal direction. In free-swimming specimens this is seen as an increase in the velocity of forward locomotion. PMID:5768366

  13. Sex recombination, and reproductive fitness: an experimental study using Paramecium

    SciTech Connect

    Nyberg, D.

    1982-08-01

    The effect of sex and recombination on reproductive fitness are measured using five wild stocks of Paramecium primaurelia. Among the wild stocks there were highly significant differences in growth rates. No hybrid had as low a fitness as the least fit parental stock. Recombination produced genotypes of higher fitness than those of either parent only in the cross between the two stocks of lowest fitness. The increase in variance of fitness as a result of recombination was almost exclusively attributable to the generation lines with low fitness. The fitness consequences of sexuality and mate choice were stock specific; some individuals leaving the most descendants by inbreeding, others by outcrossing. For most crosses the short-term advantage of sex, if any, accrue from the fusion of different gametes (hybrid vigor) and not from recombination. Since the homozygous genotype with the highest fitnes left the most progeny by inbreeding (no recombination), the persistence of conjugation in P. primaurelia is paradoxical. (JMT)

  14. Restoration of Nucleo-Mitochondrial Compatibility in Paramecium

    PubMed Central

    Sainsard-Chanet, Annie; Knowles, Jonathan

    1979-01-01

    In Paramecium, as previously described, the nuclear mutation cl1 is incompatible with wild-type mitochondria (M+); however, all cl1/cl1M+ cells eventually overcome this incompatibility (Sainsard, Claisse and Balmefrezol 1974). We have studied the kinetics and genetic basis of the spontaneous restoration of harmony between nucleus and mitochondria. We also studied the modification of these kinetics following microinjection of compatible mutant mitochondria into cl1/cl1M+ cells. We demonstrate that nucleo-mitochondrial readjustment is always achieved by mitochondrial changes that fall into two classes. The first class corresponds to spontaneous mitochondrial mutations affecting the amount of cytochrome aa3 and is similar to the previously described Mcl and Msu mutations (Sainsard-Chanet 1978; Sainsard 1975). The nature of the second class of modification is not yet understood; it may correspond either to a mitochondrial "adaptation" or to an unusual type of mutation arising and reverting at high frequency. PMID:17248983

  15. Biophysical effects of the natural product euplotin C on the Paramecium membrane.

    PubMed

    Ramoino, Paola; Dini, Fernando; Bianchini, Paolo; Diaspro, Alberto; Guella, Graziano; Usai, Cesare

    2009-11-01

    The effect of euplotin C--a cytotoxic secondary metabolite produced by the protist ciliate Euplotes crassus--on the voltage-dependent Ca(2+) channel activity was studied in a single-celled system by analyzing the swimming behavior of Paramecium. When the intraciliary Ca(2+) concentration associated with plasma membrane depolarization increases, a reversal in the direction of ciliary beating occurs, and consequently the swimming direction changes. The ciliary reversal duration is correlated with the amount of Ca(2+) influx. The present study demonstrates that the duration of continuous ciliary reversal (CCR), triggered by high external KCl concentrations, is longer in euplotin C-treated cells. Using selective Ca(2+) channel blockers, we demonstrate that euplotin C modulates Ca(2+) channels similar to the T- and L-types that occur in mammalian cells. Indeed, the increase of CCR duration significantly decreased when flunarizine and nimodipine-verapamil blockers were employed. Membrane fluidity measurements using a fluorescent dye, 6-lauroyl-2-dimethylaminonaphtalene (laurdan), indicated that membranes in euplotin C-treated cells are more tightly packed and ordered than membranes in control cells. Our data suggest that euplotin C enhances backward swimming in our unicellular model system by interacting with the ciliary Ca(2+) channel functions through the reduction of cell membrane fluidity. PMID:19777247

  16. Behavior of Paramecium sp. in solutions containing Sr and Pb: Do Paramecium sp. alter chemical forms of those metals?

    NASA Astrophysics Data System (ADS)

    Kozai, Naofumi; Ohnuki, Toshihiko; Koka, Masahi; Satoh, Takahiro; Kamiya, Tomihiro

    2011-10-01

    The behavior of Paramecium sp. (Paramecium bursaria) in aqueous solutions containing Sr and Pb was investigated to determine the role of protozoa in the migration of radionuclides in the environment. Precultured living cells of P. bursaria were exposed to aqueous solutions containing 0.01 or 0.05 mM Sr or Pb at pH 7 for 24 h. For comparison, pre-killed cells were treated with the metal solutions in the same way. Two-dimensional elemental mappings of cells were obtained by micro-PIXE. Aquatic species of Sr and Pb were analyzed by size exclusion chromatography (SEC) coupled online to ultraviolet (UV) spectroscopy and inductivity coupled plasma mass spectroscopy (ICP-MS). The amounts of Sr adsorbed or taken up by the cells surviving for 24 h and adsorbed on pre-killed cells were below the detection limit. Cells of P. bursaria adsorbed or took up a fraction of Pb. The Pb adsorbed or taken up by the cells surviving for 24 h in the Pb solution was barely detectable, while the Pb adsorbed on pre-killed cells was clearly mappable. These findings suggest that living cells of P. bursaria have functions that reduce adsorption or uptake of Pb on the cells. Quantitative and SEC-UV-ICP-MS analyses of the Sr and Pb in aqueous phases showed no clear evidences that living cells of P. bursaria alter the chemical form of Sr or Pb remaining in the aqueous phases after the cell-solution contact.

  17. A comparison of the polycation receptors of Paramecium tetraurelia and Tetrahymena thermophila.

    PubMed

    Robinette, Eric D; Gulley, Kevin T; Cassity, Katherine J; King, Erin E; Nielsen, Amber J; Rozelle, Cristine L; Warren, Timothy J; Morrow, James M; Kuruvilla, Heather G

    2008-01-01

    Chemorepellents are compounds that cause ciliated protozoans to reorient their swimming direction. A number of chemorepellents have been studied in the ciliated protozoans, Paramecium and Tetrahymena. Chemorepellents, such as polycations, cause the organism to exhibit "avoidance behavior," a swimming behavior characterized by jerky movements and other deviations from normal forward swimming, which result from ciliary reversal. One well-characterized chemorepellent pathway in Tetrahymena is that of the proposed polycation receptor that is activated by lysozyme and pituitary adenylate cyclase activating polypeptide (PACAP). In this study, we compare the response of Paramecium to the chemorepellents lysozyme, vasoactive intestinal peptide (VIP), and PACAP to the previously studied polycation response in Tetrahymena. Our results indicate that lysozyme, VIP, and PACAP are all chemorepellents in Paramecium, just as they are in Tetrahymena. However, the signaling pathways involved appear to be different. While previous pharmacological characterization indicates that G-proteins are involved in polycation signaling in Tetrahymena, we present evidence that similar reception in Paramecium involves activation of a tyrosine kinase pathway in order for lysozyme avoidance to occur. Polycation responses of both organisms are inhibited by neomycin sulfate. While PACAP is the most effective of the three chemorepellents in Tetrahymena, lysozyme is the most effective chemorepellent in Paramecium. PMID:18318860

  18. 3'-modified antisense oligodeoxyribonucleotides complementary to calmodulin mRNA alter behavioral responses in Paramecium.

    PubMed Central

    Hinrichsen, R D; Fraga, D; Reed, M W

    1992-01-01

    The calcium-binding protein calmodulin has been shown to modulate the Ca(2+)-dependent ion channels of Paramecium tetraurelia. Mutations in the calmodulin gene of Paramecium result in an altered pattern of behavioral responses. Antisense oligodeoxyribonucleotides (ODNs), complementary to calmodulin mRNA in Paramecium, were synthesized from a modified solid support that introduced a 3'-hydroxyhexyl phosphate. These 3'-modified ODNs were tested for their ability to alter the behavioral response of Paramecium. The microinjection of antisense ODNs temporarily reduced the backward swimming behavior of the cells in test solutions containing Na+. The injection of sense and random 3'-modified ODNs, or unmodified antisense ODNs, had no effect. The antisense ODN-induced effect was reversed by the injection of calmodulin protein. The pattern of response of the injected cells in various behavioral test solutions indicated that the calmodulin antisense ODNs reduce the Ca(2+)-dependent Na+ current. Antisense ODNs, complementary either to the 5' start site or to an internal sequence of the calmodulin mRNA, were similarly effective in altering behavior. These results show that antisense ODNs may be utilized in ciliated protozoa as a tool for reducing the expression of specific gene products. In addition, Paramecium represents a powerful model system with which to study and develop antisense ODN technology. PMID:1528867

  19. COMPARISON BETWEEN THERMORECEPTOR AND MECHANORECEPTOR CURRENTS IN PARAMECIUM CAUDATUM

    PubMed

    Tominaga; Naitoh

    1994-04-01

    1. A voltage-clamped Paramecium produced an inward membrane current upon thermal or mechanical stimulation of its anterior region, whereas it produced an outward membrane current upon similar stimulation of its posterior region. 2. Anterior thermo- and mechanoreceptor currents decreased when the membrane potential was shifted in a positive direction, showing sign reversal at a positive membrane potential, whereas posterior thermo- and mechanoreceptor currents decreased when the membrane potential was shifted in a negative direction, showing sign reversal at a membrane potential more negative than the resting potential. 3. The reversal potential for both anterior receptor currents shifted in a positive direction when external [Ca2+] was increased, whereas those for both posterior receptor currents shifted in a positive direction when external [K+] was increased. 4. External [Mg2+], [Mn2+], [Na+], [Rb+] and [TEA+] had similar effects on the thermo- and mechanoreceptor currents. 5. Thermoreceptor currents decreased whereas mechanoreceptor currents increased as the ambient temperature was raised. 6. When a mechanical stimulus was applied to the membrane where a thermoreceptor current was being produced, an algebraic summation of these receptor currents occurred. 7. It is concluded that thermoreceptor currents are dependent on ion channels different from those responsible for the mechanoreceptor currents, although the ionic pores for the channels are similar to each other in various respects. 8. A possibility that a thermoreceptor mechanism exclusively shares a Ca2+ pore in the anterior membrane, or a K+ pore in the posterior membrane, with a mechanoreceptor mechanism is discussed. PMID:9317455

  20. Ciliate Paramecium is a natural reservoir of Legionella pneumophila.

    PubMed

    Watanabe, Kenta; Nakao, Ryo; Fujishima, Masahiro; Tachibana, Masato; Shimizu, Takashi; Watarai, Masahisa

    2016-01-01

    Legionella pneumophila, the causative agent of Legionnaires' disease, replicates within alveolar macrophages and free-living amoebae. However, the lifestyle of L. pneumophila in the environment remains largely unknown. Here we established a novel natural host model of L. pneumophila endosymbiosis using the ciliate Paramecium caudatum. We also identified Legionella endosymbiosis-modulating factor A (LefA), which contributes to the change in life stage from endosymbiosis to host lysis, enabling escape to the environment. We isolated L. pneumophila strains from the environment, and they exhibited cytotoxicity toward P. caudatum and induced host lysis. Acidification of the Legionella-containing vacuole (LCV) was inhibited, and enlarged LCVs including numerous bacteria were observed in P. caudatum infected with L. pneumophila. An isogenic L. pneumophila lefA mutant exhibited decreased cytotoxicity toward P. caudatum and impaired the modification of LCVs, resulting in the establishment of endosymbiosis between them. Our results suggest that L. pneumophila may have a mechanism to switch their endosymbiosis in protistan hosts in the environment. PMID:27079173

  1. Ciliate Paramecium is a natural reservoir of Legionella pneumophila

    PubMed Central

    Watanabe, Kenta; Nakao, Ryo; Fujishima, Masahiro; Tachibana, Masato; Shimizu, Takashi; Watarai, Masahisa

    2016-01-01

    Legionella pneumophila, the causative agent of Legionnaires’ disease, replicates within alveolar macrophages and free-living amoebae. However, the lifestyle of L. pneumophila in the environment remains largely unknown. Here we established a novel natural host model of L. pneumophila endosymbiosis using the ciliate Paramecium caudatum. We also identified Legionella endosymbiosis-modulating factor A (LefA), which contributes to the change in life stage from endosymbiosis to host lysis, enabling escape to the environment. We isolated L. pneumophila strains from the environment, and they exhibited cytotoxicity toward P. caudatum and induced host lysis. Acidification of the Legionella-containing vacuole (LCV) was inhibited, and enlarged LCVs including numerous bacteria were observed in P. caudatum infected with L. pneumophila. An isogenic L. pneumophila lefA mutant exhibited decreased cytotoxicity toward P. caudatum and impaired the modification of LCVs, resulting in the establishment of endosymbiosis between them. Our results suggest that L. pneumophila may have a mechanism to switch their endosymbiosis in protistan hosts in the environment. PMID:27079173

  2. Proliferation kinetics of paramecium tetraurelia in balloon-borne experiments

    SciTech Connect

    Croute, F.; Soleilhavoup, J.P.; Vidal, S.; Rousseille, R.; Planel, H.

    1982-06-01

    Experiments were carried out to demonstrate the effect of cosmic radiation, at a balloon-flight ceiling of about 36,500 m (120,000 ft) on single-cell organism proliferation. Paramecium tetraurelia were placed in air-tight containers and maintained at 25 degrees +/- 0.1 degrees C. Cellular growth was determined by cell count, either after recovery or during the flight, by means of an automatic fixation device. Dosimetry was performed by a tissue equivalent proportional counter and was of about 0.5 mrad/h. Flight ceiling duration ranged from 48 min - 22 h. A secondary stimulating effect of growth rate, preceded by a temporary decrease, was observed after recovery. Because of the high bacterial concentration in the trans-Mediterranean flight culture medium, the temporary drop of the growth rate, due to the radiolysis products, disappears. Researchers consider that the stimulating effect can be the result of enzymatic intracellular scavenging of radiolysis products generated in the cell.

  3. Ciliate Paramecium is a natural reservoir of Legionella pneumophila

    NASA Astrophysics Data System (ADS)

    Watanabe, Kenta; Nakao, Ryo; Fujishima, Masahiro; Tachibana, Masato; Shimizu, Takashi; Watarai, Masahisa

    2016-04-01

    Legionella pneumophila, the causative agent of Legionnaires’ disease, replicates within alveolar macrophages and free-living amoebae. However, the lifestyle of L. pneumophila in the environment remains largely unknown. Here we established a novel natural host model of L. pneumophila endosymbiosis using the ciliate Paramecium caudatum. We also identified Legionella endosymbiosis-modulating factor A (LefA), which contributes to the change in life stage from endosymbiosis to host lysis, enabling escape to the environment. We isolated L. pneumophila strains from the environment, and they exhibited cytotoxicity toward P. caudatum and induced host lysis. Acidification of the Legionella-containing vacuole (LCV) was inhibited, and enlarged LCVs including numerous bacteria were observed in P. caudatum infected with L. pneumophila. An isogenic L. pneumophila lefA mutant exhibited decreased cytotoxicity toward P. caudatum and impaired the modification of LCVs, resulting in the establishment of endosymbiosis between them. Our results suggest that L. pneumophila may have a mechanism to switch their endosymbiosis in protistan hosts in the environment.

  4. Mechanics of membrane-cytoskeleton attachment in Paramecium

    NASA Astrophysics Data System (ADS)

    Campillo, C.; Jerber, J.; Fisch, C.; Simoes-Betbeder, M.; Dupuis-Williams, P.; Nassoy, P.; Sykes, C.

    2012-12-01

    In this paper we assess the role of the protein MKS1 (Meckel syndrome type 1) in the cortical membrane mechanics of the ciliated protist Paramecium. This protein is known to be crucial in the process of cilium formation, and we investigate its putative role in membrane-cytoskeleton attachment. Therefore, we compare cells where the gene coding for MKS1 is silenced to wild-type cells. We found that scanning electron microscopy observation of the cell surface reveals a cup-like structure in wild-type cells that is lost in silenced cells. Since this structure is based on the underlying cytoskeleton, one hypothesis to explain this observation is a disruption of membrane attachment to the cytoskeleton in the absence of MKS1 that should affect plasma membrane mechanics. We test this by probing the mechanics of wild-type and silenced cells by micropipette aspiration. Strikingly, we observe that, at the same aspiration pressure, the membrane of silenced cells is easily aspirated by the micropipette whereas that of wild-type cells enters only at a moderate velocity, an effect that suggests a detachment of the membrane from the underlying cytoskeleton in silenced cells. We quantify this detachment by measuring the deformation of the cell cortex and the rate of cell membrane entry in the micropipette. This study offers a new perspective for the characterization of membrane-cytoskeleton attachment in protists and paves the way for a better understanding of the role of membrane-cortex attachment in cilium formation.

  5. Paramecium bursaria Chlorella Virus 1 Encodes a Polyamine Acetyltransferase*

    PubMed Central

    Charlop-Powers, Zachary; Jakoncic, Jean; Gurnon, James R.; Van Etten, James L.; Zhou, Ming-Ming

    2012-01-01

    Paramecium bursaria chlorella virus 1 (PBCV-1), a large DNA virus that infects green algae, encodes a histone H3 lysine 27-specific methyltransferase that functions in global transcriptional silencing of the host. PBCV-1 has another gene a654l that encodes a protein with sequence similarity to the GCN5 family histone acetyltransferases. In this study, we report a 1.5 Å crystal structure of PBCV-1 A654L in a complex with coenzyme A. The structure reveals a unique feature of A654L that precludes its acetylation of histone peptide substrates. We demonstrate that A654L, hence named viral polyamine acetyltransferase (vPAT), acetylates polyamines such as putrescine, spermidine, cadaverine, and homospermidine present in both PBCV-1 and its host through a reaction dependent upon a conserved glutamate 27. Our study suggests that as the first virally encoded polyamine acetyltransferase, vPAT plays a possible key role in the regulation of polyamine catabolism in the host during viral replication. PMID:22277659

  6. Simultaneous Evaluation of Life Cycle Dynamics between a Host Paramecium and the Endosymbionts of Paramecium bursaria Using Capillary Flow Cytometry.

    PubMed

    Takahashi, Toshiyuki

    2016-01-01

    Endosymbioses are driving forces underlying cell evolution. The endosymbiosis exhibited by Paramecium bursaria is an excellent model with which to study symbiosis. A single-cell microscopic analysis of P. bursaria reveals that endosymbiont numbers double when the host is in the division phase. Consequently, endosymbionts must arrange their cell cycle schedule if the culture-condition-dependent change delays the generation time of P. bursaria. However, it remains poorly understood whether endosymbionts keep pace with the culture-condition-dependent behaviors of P. bursaria, or not. Using microscopy and flow cytometry, this study investigated the life cycle behaviors occurring between endosymbionts and the host. To establish a connection between the host cell cycle and endosymbionts comprehensively, multivariate analysis was applied. The multivariate analysis revealed important information related to regulation between the host and endosymbionts. Results show that dividing endosymbionts underwent transition smoothly from the division phase to interphase, when the host was in the logarithmic phase. In contrast, endosymbiont division stagnated when the host was in the stationary phase. This paper explains that endosymbionts fine-tune their cell cycle pace with their host and that a synchronous life cycle between the endosymbionts and the host is guaranteed in the symbiosis of P. bursaria. PMID:27531180

  7. Simultaneous Evaluation of Life Cycle Dynamics between a Host Paramecium and the Endosymbionts of Paramecium bursaria Using Capillary Flow Cytometry

    PubMed Central

    Takahashi, Toshiyuki

    2016-01-01

    Endosymbioses are driving forces underlying cell evolution. The endosymbiosis exhibited by Paramecium bursaria is an excellent model with which to study symbiosis. A single-cell microscopic analysis of P. bursaria reveals that endosymbiont numbers double when the host is in the division phase. Consequently, endosymbionts must arrange their cell cycle schedule if the culture-condition-dependent change delays the generation time of P. bursaria. However, it remains poorly understood whether endosymbionts keep pace with the culture-condition-dependent behaviors of P. bursaria, or not. Using microscopy and flow cytometry, this study investigated the life cycle behaviors occurring between endosymbionts and the host. To establish a connection between the host cell cycle and endosymbionts comprehensively, multivariate analysis was applied. The multivariate analysis revealed important information related to regulation between the host and endosymbionts. Results show that dividing endosymbionts underwent transition smoothly from the division phase to interphase, when the host was in the logarithmic phase. In contrast, endosymbiont division stagnated when the host was in the stationary phase. This paper explains that endosymbionts fine-tune their cell cycle pace with their host and that a synchronous life cycle between the endosymbionts and the host is guaranteed in the symbiosis of P. bursaria. PMID:27531180

  8. Pdsg1 and Pdsg2, novel proteins involved in developmental genome remodelling in Paramecium.

    PubMed

    Arambasic, Miroslav; Sandoval, Pamela Y; Hoehener, Cristina; Singh, Aditi; Swart, Estienne C; Nowacki, Mariusz

    2014-01-01

    The epigenetic influence of maternal cells on the development of their progeny has long been studied in various eukaryotes. Multicellular organisms usually provide their zygotes not only with nutrients but also with functional elements required for proper development, such as coding and non-coding RNAs. These maternally deposited RNAs exhibit a variety of functions, from regulating gene expression to assuring genome integrity. In ciliates, such as Paramecium these RNAs participate in the programming of large-scale genome reorganization during development, distinguishing germline-limited DNA, which is excised, from somatic-destined DNA. Only a handful of proteins playing roles in this process have been identified so far, including typical RNAi-derived factors such as Dicer-like and Piwi proteins. Here we report and characterize two novel proteins, Pdsg1 and Pdsg2 (Paramecium protein involved in Development of the Somatic Genome 1 and 2), involved in Paramecium genome reorganization. We show that these proteins are necessary for the excision of germline-limited DNA during development and the survival of sexual progeny. Knockdown of PDSG1 and PDSG2 genes affects the populations of small RNAs known to be involved in the programming of DNA elimination (scanRNAs and iesRNAs) and chromatin modification patterns during development. Our results suggest an association between RNA-mediated trans-generational epigenetic signal and chromatin modifications in the process of Paramecium genome reorganization. PMID:25397898

  9. The Use of Paramecium to Observe the Toxic Effect of Cigarette Smoke.

    ERIC Educational Resources Information Center

    Bardell, David

    1986-01-01

    Describes a laboratory experiment in which Paramecium caudatum was used to demonstrate the toxic effect of cigarette smoke on the cilia of epithelium cells lining the trachea and bronchi of smokers. Provides background information and explains the procedure, including how to make a simple mechanical smoking device. (TW)

  10. Pressure-induced changes in Ca2+-channel excitability in Paramecium.

    PubMed

    Otter, T; Salmon, E D

    1985-07-01

    The behaviour of swimming Paramecium is markedly affected by hydrostatic pressure (50-200 atm, 1 atm = 101 325 Pa). To investigate whether pressure might alter behaviour by acting directly on specific ion channels that mediate the behavioural responses, we examined the effects of K+, Na+ and Ba2+ ions on swimming speed and the reversal response during pressurization and decompression. If pressure acted on the channels that transport these ions, then the pressure-induced responses of swimming Paramecium should be exaggerated or diminished, according to which ions were present in the experimental buffer. Pressurization to 100 atm in standard buffer inhibited the brief reversal of swimming direction that occurred at atmospheric pressure when a paramecium encountered the wall of the pressure chamber. To determine whether pressure impaired mechanoreceptor function or directly blocked the Ca2+-channels that control ciliary reversal, we added Ba2+ or Na+ to standard buffer to induce multiple spontaneous reversals. Pressurization blocked these reversals, suggesting that channel opening is directly inhibited by pressure. Decompression in standard buffer elicited momentary ciliary reversal and backward swimming. Buffers with a high ratio of K+ to Ca2+ suppressed this response, and the decompression-induced reversal was exaggerated in the presence of Ba2+ or Na+, consistent with the effects that these ions are known to have on Paramecium's reversal response. These data imply that, upon decompression, the Ca2+-channels that mediate ciliary reversal open transiently. In addition to blocking the reversal response, pressurization slowed forward swimming. By examining the response to pressurization of Paramecium immobilized by Ni2+, we found that hydrostatic pressure apparently slows swimming by reorientating the direction of ciliary beat. PMID:2415653

  11. Genetic Differentiation of the Mitochondrial Cytochrome Oxidase c Subunit I Gene in Genus Paramecium (Protista, Ciliophora)

    PubMed Central

    Zhao, Yan; Gentekaki, Eleni; Yi, Zhenzhen; Lin, Xiaofeng

    2013-01-01

    Background The mitochondrial cytochrome c oxidase subunit I (COI) gene is being used increasingly for evaluating inter- and intra-specific genetic diversity of ciliated protists. However, very few studies focus on assessing genetic divergence of the COI gene within individuals and how its presence might affect species identification and population structure analyses. Methodology/Principal findings We evaluated the genetic variation of the COI gene in five Paramecium species for a total of 147 clones derived from 21 individuals and 7 populations. We identified a total of 90 haplotypes with several individuals carrying more than one haplotype. Parsimony network and phylogenetic tree analyses revealed that intra-individual diversity had no effect in species identification and only a minor effect on population structure. Conclusions Our results suggest that the COI gene is a suitable marker for resolving inter- and intra-specific relationships of Paramecium spp. PMID:24204730

  12. Regulation of ciliary motility by membrane potential in Paramecium: a role for cyclic AMP.

    PubMed

    Bonini, N M; Gustin, M C; Nelson, D L

    1986-01-01

    The membrane potential of Paramecium controls the frequency and direction of the ciliary beat, thus determining the cell's swimming behavior. Stimuli that hyperpolarize the membrane potential increase the ciliary beat frequency and therefore increase forward swimming speed. We have observed that 1) drugs that elevate intracellular cyclic AMP increased swimming speed 2-3-fold, 2) hyperpolarizing the membrane potential by manipulation of extracellular cations (e.g., K+) induced both a transient increase in, and a higher sustained level of cyclic AMP compared to the control, and 3) the swimming speed of detergent-permeabilized cells in MgATP was stimulated 2-fold by the addition of cyclic AMP. Our results suggest that the membrane potential can regulate intracellular cAMP in Paramecium and that control of swimming speed by membrane potential may in part be mediated by cAMP. PMID:2427226

  13. Propulsive force of Paramecium as revealed by the video centrifuge microscope.

    PubMed

    Kuroda, K; Kamiya, N

    1989-09-01

    Using the video centrifuge microscope we constructed, we observed the behavior of Paramecium cells in a solution of graded densities under centrifugal acceleration. Beyond 300g, they not only gather in the zone where the density is closest to theirs, but also orient themselves with their longitudinal axis parallel to the direction of centrifugation turning their anterior ends toward either centripetal or centrifugal direction. Since all of them retain still active swimming capacity, it is possible to calculate their propulsive force from the difference in density between theirs (1.04 g cm-3) and that of the upper or lower layer which they can reach. The propulsive force of single Paramecium cells thus obtained was calculated to be about 7 x 10(-4) dyn. PMID:2792228

  14. Using Magnetic Forces to Probe the Gravi-response of Swimming Paramecium

    NASA Astrophysics Data System (ADS)

    Guevorkian, Karine; Valles, James M., Jr.

    2004-03-01

    Paramecium Caudatum, a single celled ciliate, alters its swimming behavior when subjected to different gravity environments (e.g. centrifugation and micro-gravity). To dissect the mechanisms behind this gravi-response and that of other biological systems, we are developing the use of magnetic body forces as a means of creating a rapidly tunable, simulated variable gravity environment. Since biological materials are weakly diamagnetic, we must subject them to intense inhomogeneous magnetic fields with characteristic field-field gradient products on the order of 16 T^2/cm. We will describe experiments on Paramecium Caudatum in which we adjust their net buoyancy with magnetic forces and measure the resulting changes in their swimming behavior.

  15. [Comparative study of the proliferation of Paramecium tetraurelia aboard a satellite and aboard a stratospheric balloon].

    PubMed

    Tixador, R; Richoilley, G; Gasset, G; Planel, H

    1982-05-17

    A possible effect of cosmic rays on cell proliferation was investigated in cultures of Paramecium tetraurelia during a stratospheric balloon flight, with the techniques already used for the CYTOS experiments, performed aboard the orbital station Salyut 6. The results show that the stimulating effect of space on cell proliferation, reported in the CYTOS experiments, also occurs in the balloon flight. The respective roles of cosmic rays and weightlessness in the biological response are discussed. PMID:6814711

  16. Effects of autogamy in Paramecium tetraurelia on catalase activity and on radiosensitivity to natural ionizing radiations

    SciTech Connect

    Croute, F.; Dupouy, D.; Charley, J.P.; Soleilhavoup, J.P.; Planel, H.

    1980-02-01

    Catalase activity of Paramecium tetraurelia decreased during autogamy and recovered to normal 5 days later. Autogamy also caused changes in the ciliate's sensitivity sensitivity to natural ionizing radiations - the decrease in cell growth rate previously described in shielded cultures did not occur when autogamous cells were used. Maximum effect of shielding was observed in 11-day-old postautogamous cells. The role of the catalase in the mechanism of natural irradiation effect is discussed.

  17. Optical Manipulation of Symbiotic Chlorella in Paramecium Bursaria Using a Fiber Axicon Microlens

    NASA Astrophysics Data System (ADS)

    Taguchi, K.; Hirota, S.; Nakayama, H.; Kunugihara, D.; Mihara, Y.

    2012-03-01

    In this paper, chemically etched axicon fiber was proposed for laser trapping of symbiotic chlorella from paramecium bursaria. We fabricated axicon micro lenses on a single-mode bare optical fiber by selective chemical etching technique. The laser beam from fiber axicon microlens was strongly focused and optical forces were sufficient to move a symbiotic chlorella. From experimental results, it was found that our proposed fiber axicon microlens was a promising tool for cell trapping without physical contact.

  18. A new approach for the assessment of acrylamide toxicity using a green paramecium.

    PubMed

    Takahashi, Toshiyuki; Yoshii, Masanobu; Kawano, Tomonori; Kosaka, Toshikazu; Hosoya, Hiroshi

    2005-02-01

    Exposure to acrylamide induces neurotoxic effects in humans. In addition, it induces genotoxic, reproductive and carcinogenic effects in laboratory animals. However, no convenient bioassay system for assessing acrylamide toxicity to animal and plant cells has been proposed to date. The present study aims to evaluate acrylamide toxicity to a green paramecium, Paramecium bursaria, bearing many endosymbiotic algae, because some chemicals are highly toxic to paramecia or microalgae, and some protozoa are already used for evaluation of environmental contaminations. Results showed that high acrylamide concentrations (> or = 1500 mg/l) have a lethal effect on P. bursaria. Although low acrylamide concentrations (< or = 150 mg/l) induced less change on the paramecium growth, the number of endosymbiotically growing algal cells drastically decreased. The acrylamide concentration required to induce a 50% decrease in the cell number (IC(50)) was determined to be 7.8 mg/l for endosymbiotic algae, indicating that the algal sensitivity to acrylamide was 7 and 15 times higher than that of Syrian hamster embryo (SHE) cells and the host cells, respectively. Here, we propose the use of P. bursaria being a convenient and sensitive bioindicator as a new approach for the assessment of acrylamide toxicity. PMID:15582361

  19. Morphological and molecular characterization of Paramecium (Viridoparamecium nov. subgen.) chlorelligerum Kahl (Ciliophora).

    PubMed

    Kreutz, Martin; Stoeck, Thorsten; Foissner, Wilhelm

    2012-01-01

    We redescribe Paramecium chlorelligerum, a forgotten species, which Kahl (Tierwelt Dtl., 1935, 30:651) briefly but precisely described in the addendum to his ciliate monographs as a Paramecium with symbiotic green algae. The redescription is based on classical morphological methods and the analysis of the small subunit (SSU) rDNA. Morphologically, P. chlorelligerum differs from P. (C.) bursaria, the second green species in the genus, by having a special swimming shape, the length of the caudal cilia, the size of the micronucleus, the size of the symbiotic algae, the contractile vacuoles (with collecting vesicles vs. collecting canals), and the number of excretory pores/contractile vacuole (1 vs. 2-3). The molecular investigations show that P. chlorelligerum forms a distinct branch distant from the P. (Chloroparamecium) bursaria clade. Thus, we classify P. chlorelligerum in a new subgenus: Paramecium (Viridoparamecium) chlorelligerum. The symbiotic alga belongs to the little-known genus Meyerella, as yet recorded only from the plankton of a North American lake. PMID:22827482

  20. The role of cortical orientation in the control of the direction of ciliary beat in Paramecium.

    PubMed

    Tamm, S L; Sonneborn, T M; Dippell, R V

    1975-01-01

    The swimming behavior of many ciliate protozoans depends on graded changes in the direction of the ciliary effective stroke in response to depolarizing stimuli (i.e., the avoiding reaction of Paramecium). We investigated the problem of whether the directional response of cilia with a variable plane of beat is related to the polarity of the cell as a whole or to the orientation of the cortical structures themselves. To do this, we used a stock of Paramecium aurelia with part of the cortex reversed 180 degrees. We determined the relation of the orientation of the kineties (ciliary rows) to the direction of beat in these mosaic paramecia by cinemicrography of particle movements near living cells and by scanning electron microscopy of instantaneously fixed material. We found that the cilia of the inverted rows always beat in the direction opposite to that of normally oriented cilia during both forward and backward swimming. In addition, metachronal waves of ciliary coordination were present on the inverted patch, travelling in the direction opposite to those on the normal cortex. The reference point for the directional response of Paramecium cilia to stimuli thus resides within the cilia or their immediate cortical surroundings. PMID:45847

  1. Effect of novel phosphoramidate on growth and respiratory metabolism of Paramecium aurelia.

    PubMed

    Houneida, Benbouzid; Berrebah, H; Berredjem, M; Djebar, M R

    2012-01-01

    The continuous increase in the number of new chemicals as well as the discharges of solid and liquid wastes triggered the need for simple and inexpensive bioassays for routine testing. In recent years, there has been increasing development of methods (particularly rapid tests) for testing environmental samples. This paper describes the quick toxic evaluation of a novel synthetic compound: Phosphoramidate derivative B at different concentrations (2, 4 and 8 μM) for 72 h on Paramecium aurelia. We showed that B concentrations affect the growth of Paramecium in concentration- dependent manner; also it decreases the growth rate and increases response percentage in concentration- dependent manner. The value of LC50 obtained for these protozoa was estimated at 4.9693 μM after 24 hours of exposure. The respiratory metabolism of protozoan is perturbed at three concentrations, noting that the oxygen consumption was significantly increased at high concentrations after 18 hours of exposure. The results indicate that the Paramecium toxicity assay could be used as a complementary system to rapidly elucidate the cytotoxic potential of insecticides. The major advantages associated with these tests are: inexpensive, simple, rapid and seem to be attractive alternatives to conventional bioassays. PMID:22690051

  2. Jump if you can't take the heat: three escape gaits of Paramecium swimming

    NASA Astrophysics Data System (ADS)

    Baroud, Charles N.; Hamel, Amandine; Fisch, Cathy; Combettes, Laurent; Dupuys-Williams, Pascale

    2010-11-01

    Paramecium is able to swim at velocities reaching several times its body size per second, by beating its thousands of cilia in an organized fashion. Here we show that Paramecium has in fact three distinct swimming gaits to escape from an aggression in the form of localized heating, depending on the magnitude of the aggression: For a weak agression, normal swimming is sufficient and produces a steady swimming velocity through cilia beating. As the heating amplitude is increased, a higher acceleration and faster swimming are achieved through synchronized beating of the cilia, which later give way to the usual metachronal waves. The synchronized beating yields high initial accelerations but requires the cell to coast through the synchrnized recovery. Finally, escape from a life-threatening agression is achieved by a "jumping" gait which does not rely on the cilia but is achieved from the explosive release of a rod-like organelles in the direction of the hot spot. Measurements through high-speed video explain the role of these rods in defending Paramecium. They also show that the zero-Reynolds number assumption is unverified in most cases.

  3. Feeding of swimming Paramecium with fore-aft asymmetry in viscous fluid

    NASA Astrophysics Data System (ADS)

    Zhang, Peng; Jana, Saikat; Giarra, Matthew; Vlachos, Pavlos; Jung, Sunghwan

    2013-11-01

    Swimming behaviours and feeding efficiencies of Paramecium Multimicronucleatum with fore-aft asymmetric body shapes are studied experimentally and numerically. Among various possible swimming ways, ciliates typically exhibit only one preferred swimming directions in favorable conditions. Ciliates, like Paramecia, with fore-aft asymmetric shapes preferably swim towards the slender anterior while feeding fluid to the oral groove located at the center of the body. Since both feeding and swimming efficiencies are influenced by fluid motions around the body, it is important to reveal the fluid mechanics around a moving object. Experimentally, μ-PIV methods are employed to characterize the source-dipole streamline patterns and fluid motions around Paramecium. Numerical simulations by boundary element methods are also used to evaluate surface stresses and velocities, which give insights into the efficiencies of swimming and feeding depending on body asymmetry. It is concluded that a slender anterior and fat posterior increases the combined efficiency of swimming and feeding, which matches well with actual shapes of Paramecium. Discrepancies between experiments and simulations are also discussed.

  4. The influence of hypergravity on the Paramecium bursaria-Chlorella sp. symbiotic association.

    PubMed

    Bator, Tomasz; Pado, Ryszard

    2009-01-01

    The aim of the research was to determine the influence of strong hypergravity on the Paramecium bursaria-Chlorella sp. symbiotic association, which is considered to be a model example of symbiosis between a heterotroph and an autotroph. The paramecia cells were exposed to 1073 x g, 4293 x g, and 9658 x g hypergravity for 15 min. Then they were incubated for 21 d on a standard lettuce medium. The experiments were conducted in parallel under constant white light and in the dark. The changes in the number of paramecia cells during incubation were determined. Measurements of the number of Chlorella sp. endosymbionts inside host cells were also made. The results showed that a 15-min exposure to hypergravity attenuates the subsequent growth of Paramecium bursaria in the dark, but it may stimulate the growth of paramecia under constant light. Moreover, it causes an increase in the number of algae inside the paramecia cells. Presumably, the influence of hypergravity on the studied symbiotic complex is connected with its effect on the endosymbiotic Chlorella sp. cells. This subject requires further research, focused on the influence of hypergravity on the physiology and growth of the Chlorella sp. endosymbionts living inside the Paramecium bursaria cells. PMID:19957445

  5. Delimiting Species Boundaries within a Paraphyletic Species Complex: Insights from Morphological, Genetic, and Molecular Data on Paramecium sonneborni (Paramecium aurelia species complex, Ciliophora, Protozoa).

    PubMed

    Przyboś, Ewa; Tarcz, Sebastian; Rautian, Maria; Sawka, Natalia

    2015-09-01

    The demarcation of boundaries between protist species is often problematic because of the absence of a uniform species definition, the abundance of cryptic diversity, and the occurrence of convergent morphology. The ciliates belonging to the Paramecium aurelia complex, consisting of 15 species, are a good model for such systematic and evolutionary studies. One member of the complex is P. sonneborni, previously known only from one stand in Texas (USA), but recently found in two new sampling sites in Cyprus (creeks running to Salt Lake and Oroklini Lake near Larnaca). The studied Paramecium sonneborni strains (from the USA and Cyprus) reveal low viability in the F1 and F2 generations of interstrain hybrids and may be an example of ongoing allopatric speciation. Despite its molecular distinctiveness, we postulate that P. sonneborni should remain in the P. aurelia complex, making it a paraphyletic taxon. Morphological studies have revealed that some features of the nuclear apparatus of P. sonneborni correspond to the P. aurelia spp. complex, while others are similar to P. jenningsi and P. schewiakoffi. The observed discordance indicates rapid splitting of the P. aurelia-P. jenningsi-P. schewiakoffi group, in which genetic, morphological, and molecular boundaries between species are not congruent. PMID:26277215

  6. Pharmacological characterization of NMDA-like receptors in the single-celled organism Paramecium primaurelia.

    PubMed

    Ramoino, Paola; Candiani, Simona; Pittaluga, Anna Maria; Usai, Cesare; Gallus, Lorenzo; Ferrando, Sara; Milanese, Marco; Faimali, Marco; Bonanno, Giambattista

    2014-02-01

    Paramecium primaurelia is a unicellular eukaryote that moves in freshwater by ciliary beating and responds to environmental stimuli by altering motile behaviour. The movements of the cilia are controlled by the electrical changes of the cell membrane: when the intraciliary Ca(2+) concentration associated with plasma membrane depolarization increases, the ciliary beating reverses its direction, and consequently the swimming direction changes. The ciliary reversal duration is correlated with the amount of Ca(2+) influx. Here, we evaluated the effects due to the activation or blockade of N-methyl-d-aspartic acid (NMDA) receptors on swimming behaviour in Paramecium. Paramecia normally swim forward, drawing almost linear tracks. We observed that the simultaneous administration of NMDA and glycine induced a partial ciliary reversal (PaCR) leading to a continuous spiral-like swim. Furthermore, the duration of continuous ciliary reversal (CCR), triggered by high external KCl concentrations, was longer in NMDA+glycine-treated cells. NMDA action required the presence of Ca(2+), as the normal forward swimming was restored when the ion was omitted from the extracellular milieu. The PaCR and the enhancement of CCR duration significantly decreased when the antagonists of the glutamate site D-AP5 or CGS19755, the NMDA channel blocker MK-801 or the glycine site antagonist DCKA was added. The action of NMDA+glycine was also abolished by Zn(2+) or ifenprodil, the GluN2A and the GluN2B NMDA-containing subunit blockers, respectively. Searches of the Paramecium genome database currently available indicate that the NMDA-like receptor with ligand-binding characteristics of an NMDA receptor-like complex, purified from rat brain synaptic membranes and found in some metazoan genomes, is also present in Paramecium. These results provide evidence that functional NMDA receptors similar to those typical of mammalian neuronal cells are present in the single-celled organism Paramecium and thus

  7. Hierarchical paramecium-like hollow and solid Au/Pt bimetallic nanostructures constructed using goethite as template

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Repo, Eveliina; Heikkilä, Mikko; Leskelä, Markku; Sillanpää, Mika

    2010-10-01

    Novel hollow and solid paramecium-like hierarchical Au/Pt bimetallic nanostructures were constructed using goethite as template via a seed-mediated growth method. Transmission electron microscopy (TEM), ξ-potential measurement, UV-vis spectroscopy, energy dispersive x-ray spectroscopy (EDS), ICP-AES measurement, x-ray powder diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) were utilized to systematically characterize the bimetallic nanostructures. It is found that the core structure of the paramecium-like bimetallic nanomaterial is closely related to reducing agent. When ascorbic acid is used as reducing agent, goethite serves as in situ sacrificed template and hollow paramecium-like bimetallic structure is obtained. When NH2OH·HCl is used, solid nanostructure with preserved goethite core is produced. Heating the reaction solution is necessary to obtain the paramecium-like morphology with rough interconnected Pt cilia shell. The thickness of Pt cilia layer can be controlled by adjusting the molar ratio of H2PtCl6 to Au nanoseeds. The overgrowth of the rough Pt cilia is proposed to be via an autocatalytic and three-dimensional heterogeneous nucleation process first through flower-like morphology. Both the hollow and solid hierarchical paramecium-like Au/Pt bimetallic nanostructures show good catalytic activities.

  8. Protein phosphatase 2C is involved in the cAMP-dependent ciliary control in Paramecium caudatum.

    PubMed

    Noguchi, Munenori; Sasaki, Jun-Ya; Kamachi, Hiroyuki; Inoue, Hiroshi

    2003-02-01

    Forward swimming of the Triton-extracted model of Paramecium is stimulated by cAMP. Backward swimming of the model induced by Ca(2+) is depressed by cAMP. Cyclic AMP and Ca(2+) act antagonistically in setting the direction of the ciliary beat. Some ciliary axonemal proteins from Paramecium caudatum are phosphorylated in a cAMP-dependent manner. In the presence of cAMP, axonemal 29- and 65-kDa polypeptides were phosphorylated by endogenous A-kinase in vitro. These phosphoproteins, however, were not dephosphorylated after in vitro phosphorylation, presumably because of the low endogenous phosphoprotein phosphatase activity associated with isolated axonemes. We purified the protein phosphatase that specifically dephosphorylated the 29- and 65-kDa phosphoproteins from Paramecium caudatum. The molecular weight of the protein phosphatase was 33 kDa. The protein phosphatase had common characteristics as protein phosphatase 2C (PP2C). The characteristics of the protein phosphatase were the same as those of the PP2C from Paramecium tetraurelia (PtPP2C) [Grothe et al., 1998: J. Biol. Chem. 273:19167-19172]. We concluded that the phosphoprotein phosphatase is the PP2C from Paramecium caudatum (PcPP2C). The PcPP2C markedly accelerated the backward swimming of the Triton-extracted model in the presence of Ca(2+). On the other hand, the PcPP2C slightly depressed the forward swimming speed. This indicates that the PP2C plays a role in the cAMP-dependent regulation of ciliary movement in Paramecium caudatum through dephosphorylation of 29- and/or 65-kDa regulatory phosphoproteins by terminating the action of cAMP. PMID:12529856

  9. The Ciliate Paramecium Shows Higher Motility in Non-Uniform Chemical Landscapes

    PubMed Central

    Giuffre, Carl; Hinow, Peter; Vogel, Ryan; Ahmed, Tanvir; Stocker, Roman; Consi, Thomas R.; Strickler, J. Rudi

    2011-01-01

    We study the motility behavior of the unicellular protozoan Paramecium tetraurelia in a microfluidic device that can be prepared with a landscape of attracting or repelling chemicals. We investigate the spatial distribution of the positions of the individuals at different time points with methods from spatial statistics and Poisson random point fields. This makes quantitative the informal notion of “uniform distribution” (or lack thereof). Our device is characterized by the absence of large systematic biases due to gravitation and fluid flow. It has the potential to be applied to the study of other aquatic chemosensitive organisms as well. This may result in better diagnostic devices for environmental pollutants. PMID:21494596

  10. Reactivated triton-extracted models o paramecium: modification of ciliary movement by calcium ions.

    PubMed

    Naito, Y; Kaneko, H

    1972-05-01

    Triton-extracted models of Paramecium were reactivated to swim in solutions of adenosine triphosphate and magnesium ions. The cilia beat in the normal direction (toward the rear) when the calcium ion concentration was less than 10-(6)M, and they beat in the "reversed" direction (toward the front) when calcium ion concentration was raised above 10-(6)M. These results support the proposal that ciliary reversal, hence backward swimming, of live paramecia is mediated by an increased cytoplasmic calcium concentration around the ciliary system by calcium-dependent membrane responses to external stimuli. PMID:5032354

  11. Calcium channel stability measured by gradual loss of excitability in pawn mutants of Paramecium aurelia.

    PubMed

    Schein, S J

    1976-12-01

    Mutants of Paramecium aurelia that are unable to reverse swimming direction are called pawns. They lack the inward ionic (calcium) current required for the upstroke of the electrically excitable membrane response. By following the progressive loss of reversal response and excitability in cells that are suddenly changed from a heterozygous (wild-type) state to a homozygous mutant state, an estimate of the stability and mean lifetime of the calcium channel has been obtained. During rapid growth, channel dilution due to division occurred, but no channel decay was observed. Under conditions of slow growth, decay could also be observed; channel lifetime was found to be from 5 to 8 days. PMID:1035256

  12. Paramecium tetraurelia pre-screen for hazardous chemicals: a rapid detector system for health hazards. 1977-1983 report

    SciTech Connect

    Smith-Sonneborn, J.

    1983-01-01

    The purpose was to develop and validate a new eukaryotic bioassay system applicable to rapid identification of environmental toxins, mutagens, and carcinogens. The ability of Paramecium to detect potential health hazards, associated with complex environmental mixtures, was demonstrated in association with the finest coal fly ash particles and aqueous waste streams from both oil shale and coal gasification developing technologies. In Paramecium, the cytotoxicity of an agent was determined by altering the survival and/or growth rate of single cells in test agents. Genotoxicity was assayed by a two-tiered approach, utilizing both the Paramecium system and the more established Ames Salmonella assay for mutagen/carcinogen detection. An agent was considered genotoxic in Paramwecium if altered phenotypes were induced in the fertilization progeny of treated parent cells. Since others had shown a significant correlation between agents which were photodynamically active in Paramecium and carcinogenic in mammals, the photodynamic activity versus carcinogenicity of agents was reviewed. Photodynamically active compounds are defined by the immobilization of cells when exposed to both the test agent and black light; neither the agent alone nor light alone affects swimming activity.

  13. Paramecium tetraurelia. Pre-screen for hazardous chemicals: a rapid-detector system for health hazards. Progress report

    SciTech Connect

    Smith-Sonneborn, J.

    1981-01-01

    Genotoxic and cytotoxic effects of dilutions of oil shale process waters from three different retorting processes were evaluated using the Paramecium tetraurelia and the Salmonella assays. Process waters from above-ground, true in situ, and modified retorting process were analyzed. Significant mutagenicity was detected in waste water from both the above-ground and true in situ retorting processes in both the Salmonella and Paramecium bioassays. The Salmonella assay required the addition of the rat liver S9 fraction; the Paramecium bioassay was more sensitive to genotoxic effects from an above-ground retort water without the addition of the rat liver fraction. Mutagenicity of the dilutions tested from the modified retort process was detected only in the Paramecium system. The waste water from the above-ground retort process was the most toxic to both the protozoan and bacteria. Since the chemical composition of oil shale process waters can vary with: 1) the retorting process used, 2) the temperature of the retorting, 3) the composition of the shale rock, and 4) the sampling and storage procedures, the differences in biological activity observed between water can reflect differences in water contamination.

  14. Multiple lines of evidence shed light on the occurrence of paramecium (ciliophora, oligohymenophorea) in bromeliad tank water.

    PubMed

    Buosi, Paulo R B; Cabral, Adalgisa F; Simão, Taiz L L; Utz, Laura R P; Velho, Luiz F M

    2014-01-01

    Phytotelmata are vegetal structures that hold water from the rain, and organic matter from the forest and the soil, resulting in small, compartmentalized bodies of water, which provide an essential environment for the establishment and development of many organisms. These microenvironments generally harbor endemic species, but many organisms that are found in lakes and rivers, are also present. Here, we report, for the first time, the occurrence of the ciliate genus Paramecium in the tank of the bromeliad species Aechmaea distichantha. The identification of the Paramecium species was performed based on live observations, protargol impregnation, scanning electronic microscopy, and sequencing of the 18s rRNA. The absence of Paramecium from bromeliad tank water was highlighted in several earlier investigations, and may be due to the fact that this species is unable to make cysts. The occurrence of Paramecium multimicronucleatum in our samples may be explained by the proximity between the bromeliads and the river, a potential source of the species. Further, we also believe that the counting methodology used in our study provides a more accurate analysis of the species diversity, since we investigated all samples within a maximum period of 6 h after sampling, allowing minimum loss of specimens. PMID:24011017

  15. Molecular identification of a SNAP-25-like SNARE protein in Paramecium.

    PubMed

    Schilde, Christina; Lutter, Kaya; Kissmehl, Roland; Plattner, Helmut

    2008-08-01

    Using database searches of the completed Paramecium tetraurelia macronuclear genome with the metazoan SNAP-25 homologues, we identified a single 21-kDa Qb/c-SNARE in this ciliated protozoan, named P. tetraurelia SNAP (PtSNAP), containing the characteristic dual heptad repeat SNARE motifs of SNAP-25. The presence of only a single Qb/c class SNARE in P. tetraurelia is surprising in view of the multiple genome duplications and the high number of SNAREs found in other classes of this organism. As inferred from the subcellular localization of a green fluorescent protein (GFP) fusion construct, the protein is localized on a variety of intracellular membranes, and there is a large soluble pool of PtSNAP. Similarly, the PtSNAP that is detected with a specific antibody in fixed cells is associated with a number of intracellular membrane structures, including food vacuoles, the contractile vacuole system, and the sites of constitutive endo- and exocytosis. Surprisingly, using gene silencing, we could not assign a role to PtSNAP in the stimulated exocytosis of dense core vesicles (trichocysts), but we found an increased number of food vacuoles in PtSNAP-silenced cells. In conclusion, we identify PtSNAP as a Paramecium homologue of metazoan SNAP-25 that shows several divergent features, like resistance to cleavage by botulinum neurotoxins. PMID:18552286

  16. An ultradian clock controls locomotor behaviour and cell division in isolated cells of Paramecium tetraurelia.

    PubMed

    Kippert, F

    1996-04-01

    An ultradian clock operates in fast growing cells of the large ciliate, Paramecium tetraurelia. The period of around 70 minutes is well temperature-compensated over the temperature range tested, i.e. between 18 degrees C and 33 degrees C. The Q10 between 18 degrees C and 27 degrees C is 1.08; above 27 degrees C there is a slight overcompensation. The investigation of individual cells has revealed that two different cellular functions are under temporal control by this ultradian clock. First, locomotor behaviour, which is an alternation between a phase of fast swimming with only infrequent turning, and a phase of slow swimming with frequent spontaneous changes of direction. In addition, the ultradian clock is involved in the timing of cell division. Generation times are not randomly distributed, but occur in well separated clusters. At all of the six temperatures tested, the clusters are separated by around 70 minutes which corresponds well to the period of the locomotor behaviour rhythm at the respective temperatures. Whereas the interdivision times were gradually lengthened both above and below the optimum growth temperature, the underlying periodicity remained unaffected. Also cells of different clonal age had identical periods, suggesting that neither the differences in DNA content, not other changes associated with ageing in Paramecium have an effect on the clock. A constant phase relationship was observed between the rhythm in locomotor behaviour and the time window for cell division; this strongly suggests that the same ultradian clock exerts temporal control over both processes. PMID:8718678

  17. Super-helix model: a physiological model for gravitaxis of Paramecium.

    PubMed

    Mogami, Y; Baba, S A

    1998-01-01

    A new model explaining the gravitactic behavior of Paramecium is derived on the basis of its mechanism of gravity sensing. Paramecium is know to have depolarizing mechanoreceptor ion channels in the anterior and hyperpolarizing channels in the posterior of the cell. This arrangement may lead to bidirectional changes of the membrane potential due to the selective deformation of the anterior and posterior cell membrane responding to the orientation of the cell with respect to the gravity vector; i.e., negative- and positive-going shifts of the potential due to the upward and downward orientation, respectively. The orientation dependent changes in membrane potential, in combination with the close coupling between the membrane potential and ciliary locomotor activity, may allow the changes in swimming direction along the otherwise simple helical swimming path in the following manner: an upward shift of the axis of helical swimming occurs by decreasing the pitch angle due to channel-dependent hyperpolarization in upward-orienting cells, and an upward shift of the swimming helix occurs by increasing the cell's pitch angle due to depolarization in downward-orienting cells. Computer simulation of the model demonstrated that the cell can swim upward along the "super-helical" trajectory consisting of a small helix winding helically along an axis parallel to the gravity vector. PMID:11541384

  18. Epigenetic regulation of serotype expression antagonizes transcriptome dynamics in Paramecium tetraurelia

    PubMed Central

    Cheaib, Miriam; Dehghani Amirabad, Azim; Nordström, Karl J. V.; Schulz, Marcel H.; Simon, Martin

    2015-01-01

    Phenotypic variation of a single genotype is achieved by alterations in gene expression patterns. Regulation of such alterations depends on their time scale, where short-time adaptations differ from permanently established gene expression patterns maintained by epigenetic mechanisms. In the ciliate Paramecium, serotypes were described for an epigenetically controlled gene expression pattern of an individual multigene family. Paradoxically, individual serotypes can be triggered in Paramecium by alternating environments but are then stabilized by epigenetic mechanisms, thus raising the question to which extend their expression follows environmental stimuli. To characterize environmental adaptation in the context of epigenetically controlled serotype expression, we used RNA-seq to characterize transcriptomes of serotype pure cultures. The resulting vegetative transcriptome resource is first analysed for genes involved in the adaptive response to the altered environment. Secondly, we identified groups of genes that do not follow the adaptive response but show co-regulation with the epigenetically controlled serotype system, suggesting that their gene expression pattern becomes manifested by similar mechanisms. In our experimental set-up, serotype expression and the entire group of co-regulated genes were stable among environmental changes and only heat-shock genes altered expression of these gene groups. The data suggest that the maintenance of these gene expression patterns in a lineage represents epigenetically controlled robustness counteracting short-time adaptation processes. PMID:26231545

  19. Directional change of ciliary beat effected with Mg2+ in Paramecium.

    PubMed

    Nakaoka, Y; Toyotama, H

    1979-12-01

    Two types of Triton X-100 extracted model of Paramecium caudatum were prepared and effects of the ionic compositions of the reactivating medium on the swimming behaviour of the extracted models were examined. Type I, prepared by the method of Naitoh and Keneko, did not change swimming direction depending on the concentrations of Mg2+ and K+ in the reactivating medium. Type II, prepared by a different method, however, reversed the swimming direction depending on the concentrations of Mg2+ and K+ in the reactivating medium, even when the concentration of Ca2+ was kept at an extremely low level (below 10-8M). Decreasing the concentration of Mb2+ induced the type II model to swim backwards. Intracellular injection of EDTA into a live paramecium cell induced reversal of the direction of ciliary beat. The concentration of Mg2+ at which the reversal of swimming direction occurred varied with the concentration of adenosine triphosphate (ATP) in a manner which suggested that the concentration of free ATP4- might be the critical determinant of swimming direction. PMID:119789

  20. Calcium regulates independently ciliary beat and cell contraction in Paramecium cells.

    PubMed

    Iwadate, Yoshiaki; Nakaoka, Yasuo

    2008-08-01

    Intracellular Ca(2+) concentration is a well-known signal regulator for various physiological activities. In many cases, Ca(2+) simultaneously regulates individual functions in single cells. How can Ca(2+) regulate these functions independently? In Paramecium cells, the contractile cytoskeletal network and cilia are located close to each other near the cell surface. Cell body contraction, ciliary reversal, and rises in ciliary beat frequency are regulated by intracellular Ca(2+) concentration. However, they are not always triggered simultaneously. We injected caged calcium into Paramecium caudatum cells and continuously applied weak ultraviolet light to the cells to slowly increase intracellular Ca(2+) concentration. The cell bodies began to contract just after the start of ultraviolet light application, and the degree of contraction increased gradually thereafter. On the other hand, cilia began to reverse 1.4s after the start of ultraviolet application and reversed completely within 100ms. Ciliary beat frequency in the reverse direction was significantly higher than in the normal direction. These results indicate that cell body contraction is regulated by Ca(2+) in a dose-dependent manner in living P. caudatum. On the other hand, ciliary reversal and rise in ciliary beat frequency are triggered by Ca(2+) in an all-or-none manner. PMID:18179819

  1. Local trichocyst exocytosis provides an efficient escape mechanism for Paramecium cells.

    PubMed

    Knoll, G; Haacke-Bell, B; Plattner, H

    1991-11-29

    More than 1000 secretory organelles (trichocysts) are docked at the plasma membrane of Paramecium cells. After stimulation, the trichocyst contents are expelled as needle-like structures in an exocytotic response. Neither the function nor the natural stimulus of trichocyst exocytosis are known in this well established system. Several hypotheses have been put forward during the last 100 years, but as yet, none has withstood critical experimental testing. Using video-aided light microscopic evaluation of the explosive trichocyst exocytosis we have obtained conclusive evidence for a defensive mechanism. When stimulated locally by a non-cytotoxic chemical secretagogue, cells were rapidly propelled in the opposite direction by vigorous local trichocyst discharge. The same phenomenon was observed during encounter with a predatory ciliate, Dileptus. Whereas exocytosis-competent paramecia escaped by rapid propulsion away from the attacking predator, cells non-competent for exocytosis were paralysed and engulfed. Thus, oriented locomotion by locally stimulated trichocyst exocytosis serves as a rapid escape mechanism of Paramecium. PMID:23194850

  2. Super-helix model: a physiological model for gravitaxis of paramecium

    NASA Astrophysics Data System (ADS)

    Mogami, Y.; Baba, S. A.

    A new model explaining the gravitactic behavior of Paramecium is derived on the basis of its mechanism of gravity sensing. Paramecium is known to have depolarizing mechanoreceptor ion channels in the anterior and hyperpolarizing channels in the posterior of the cell. This arrangement may lead to bidirectional changes of the membrane potential due to the selective deformation of the anterior and posterior cell membrane responding to the orientation of the cell with respect to the gravity vector; i.e., negative- and positive-going shifts of the potential due to the upward and downward orientation, respectively. The orientation dependent changes in membrane potential, in combination with the close coupling between the membrane potential and ciliary locomotor activity, may allow the changes in swimming direction along the otherwise simple helical swimming path in the following manner: an upward shift of the axis of helical swimming occurs by decreasing the pitch angle due to channel-dependent hyperpolarization in upward-orienting cells, and an upward shift of the swimming helix occurs by increasing the cell's pitch angle due to depolarization in downward-orienting cells. Computer simulation of the model demonstrated that the cell can swim upward along the ``super-helical'' trajectory consisting of a small helix winding helically along an axis parallel to the gravity vector.

  3. Effect of horizontal strong static magnetic field on swimming behaviour of Paramecium caudatum

    NASA Astrophysics Data System (ADS)

    Fujiwara, Yoshihisa; Tomishige, Masahiko; Itoh, Yasuhiro; Fujiwara, Masao; Shibata, Naho; Kosaka, Toshikazu; Hosoya, Hiroshi; Tanimoto, Yoshifumi

    2006-05-01

    Effect of horizontal strong static magnetic field on swimming behaviour of Paramecium caudatum was studied by using a superconducting magnet. Around a centre of a round vessel, random swimming at 0 T and aligned swimming parallel to the magnetic field (MF) of 8 T were observed. Near a wall of the vessel, however, swimming round and round along the wall at 0 T and aligned swimming of turning at right angles upon collision with the wall, which was remarkable around 1-4 T, were detected. It was experimentally revealed that the former MF-induced parallel swimming at the vessel centre was caused physicochemically by the parallel magnetic orientation of the cell itself. From magnetic field dependence of the extent of the orientation, the magnetic susceptibility anisotropy (χ ∥-χ ⊥) was first obtained to be 3.4× 10-23 emu cell-1 at 298 K for Paramecium caudatum. The orientation of the cell was considered to result from the magnetic orientation of the cell membrane. On the other hand, although mechanisms of the latter swimming near the vessel wall regardless of the absence and presence of the magnetic field are unclear at present, these experimental results indicate that whether the cell exists near the wall alters the magnetic field effect on the swimming in the horizontal magnetic field.

  4. New Stands of Species of the Paramecium aurelia Complex in Yakutia, Russia.

    PubMed

    Rautian, Maria; Przyboś, Ewa; Beliavskaia, Alexandra

    2015-01-01

    Paramecium is one of the most studied genera among ciliates. In particular, it is a model organism for investigation of the sibling species problem (also known as the cryptic species problem), spatial distribution, and its role in speciation. The global distribution of Paramecium species and of sibling species belonging to the P. aurelia species complex (Ciliophora, Protista) still need study, e.g. sampling in some territories has been quite limited, while Europe has been investigated for years with the majority of the P. aurelia species isolated from here. The large territory of Yakutia (republic Sakha in the Russian Federation), known for its climate extremes and continuous permafrost that extended over several glacial and interglacial cycles of the Pleistocene, has not been studied before. In the present study we collected paramecia in the central part of Yakutia. Newly established strains were identified to species according to morphology and, in case of the P. aurelia complex, by crossing with the test strains (the reference strains for the particular species). New stands of P. primaurelia, P. biaurelia and P. novaurelia were described from the territory of Yakutia. PMID:26975144

  5. Ciliary metachronal wave propagation on the compliant surface of Paramecium cells.

    PubMed

    Narematsu, Naoki; Quek, Raymond; Chiam, Keng-Hwee; Iwadate, Yoshiaki

    2015-12-01

    Ciliary movements in protozoa exhibit metachronal wave-like coordination, in which a constant phase difference is maintained between adjacent cilia. It is at present generally thought that metachronal waves require hydrodynamic coupling between adjacent cilia and the extracellular fluid. To test this hypothesis, we aspirated a Paramecium cell using a micropipette which completely sealed the surface of the cell such that no fluid could pass through the micropipette. Thus, the anterior and the posterior regions of the cell were hydrodynamically decoupled. Nevertheless, we still observed that metachronal waves continued to propagate from the anterior to the posterior ends of the cell, suggesting that in addition to hydrodynamic coupling, there are other mechanisms that can also transmit the metachronal waves. Such transmission was also observed in computational modeling where the fluid was fully decoupled between two partitions of a beating ciliary array. We also imposed cyclic stretching on the surface of live Paramecium cells and found that metachronal waves persisted in the presence of cyclic stretching. This demonstrated that, in addition to hydrodynamic coupling, a compliant substrate can also play a critical role in mediating the propagation of metachronal waves. PMID:26616106

  6. Epigenetic regulation of serotype expression antagonizes transcriptome dynamics in Paramecium tetraurelia.

    PubMed

    Cheaib, Miriam; Dehghani Amirabad, Azim; Nordström, Karl J V; Schulz, Marcel H; Simon, Martin

    2015-08-01

    Phenotypic variation of a single genotype is achieved by alterations in gene expression patterns. Regulation of such alterations depends on their time scale, where short-time adaptations differ from permanently established gene expression patterns maintained by epigenetic mechanisms. In the ciliate Paramecium, serotypes were described for an epigenetically controlled gene expression pattern of an individual multigene family. Paradoxically, individual serotypes can be triggered in Paramecium by alternating environments but are then stabilized by epigenetic mechanisms, thus raising the question to which extend their expression follows environmental stimuli. To characterize environmental adaptation in the context of epigenetically controlled serotype expression, we used RNA-seq to characterize transcriptomes of serotype pure cultures. The resulting vegetative transcriptome resource is first analysed for genes involved in the adaptive response to the altered environment. Secondly, we identified groups of genes that do not follow the adaptive response but show co-regulation with the epigenetically controlled serotype system, suggesting that their gene expression pattern becomes manifested by similar mechanisms. In our experimental set-up, serotype expression and the entire group of co-regulated genes were stable among environmental changes and only heat-shock genes altered expression of these gene groups. The data suggest that the maintenance of these gene expression patterns in a lineage represents epigenetically controlled robustness counteracting short-time adaptation processes. PMID:26231545

  7. Swimming Paramecium in magnetically simulated enhanced, reduced, and inverted gravity environments

    PubMed Central

    Guevorkian, Karine; Valles, James M.

    2006-01-01

    Earth's gravity exerts relatively weak forces in the range of 10–100 pN directly on cells in biological systems. Nevertheless, it biases the orientation of swimming unicellular organisms, alters bone cell differentiation, and modifies gene expression in renal cells. A number of methods of simulating different strength gravity environments, such as centrifugation, have been applied for researching the underlying mechanisms. Here, we demonstrate a magnetic force-based technique that is unique in its capability to enhance, reduce, and even invert the effective buoyancy of cells and thus simulate hypergravity, hypogravity, and inverted gravity environments. We apply it to Paramecium caudatum, a single-cell protozoan that varies its swimming propulsion depending on its orientation with respect to gravity, g. In these simulated gravities, denoted by fgm, Paramecium exhibits a linear response up to fgm = 5 g, modifying its swimming as it would in the hypergravity of a centrifuge. Moreover, experiments from fgm = 0 to −5 g show that the response is symmetric, implying that the regulation of the swimming speed is primarily related to the buoyancy of the cell. The response becomes nonlinear for fgm >5 g. At fgm = 10 g, many paramecia “stall” (i.e., swim in place against the force), exerting a maximum propulsion force estimated to be 0.7 nN. These findings establish a general technique for applying continuously variable forces to cells or cell populations suitable for exploring their force transduction mechanisms. PMID:16916937

  8. A large multigene family codes for the polypeptides of the crystalline trichocyst matrix in Paramecium.

    PubMed Central

    Madeddu, L; Gautier, M C; Vayssié, L; Houari, A; Sperling, L

    1995-01-01

    The secretory granules (trichocysts) of Paramecium are characterized by a highly constrained shape that reflects the crystalline organization of their protein contents. Yet the crystalline trichocyst content is composed not of a single protein but of a family of related polypeptides that derive from a family of precursors by protein processing. In this paper we show that a multigene family, of unusually large size for a unicellular organism, codes for these proteins. The family is organized in subfamilies; each subfamily codes for proteins with different primary structures, but within the subfamilies several genes code for nearly identical proteins. For one subfamily, we have obtained direct evidence that the different members are coexpressed. The three subfamilies we have characterized are located on different macronuclear chromosomes. Typical 23-29 nucleotide Paramecium introns are found in one of the regions studied and the intron sequences are more variable than the surrounding coding sequences, providing gene-specific markers. We suggest that this multigene family may have evolved to assure a microheterogeneity of structural proteins necessary for morphogenesis of a complex secretory granule core with a constrained shape and dynamic properties: genetic analysis has shown that correct assembly of the crystalline core is necessary for trichocyst function. Images PMID:7579685

  9. Viruses of symbiotic Chlorella-like algae isolated from Paramecium bursaria and Hydra viridis

    PubMed Central

    Van Etten, James L.; Meints, Russel H.; Kuczmarski, Daniel; Burbank, Dwight E.; Lee, Kit

    1982-01-01

    We previously reported that isolation of symbiotic Chlorella-like algae from the Florida strain of Hydra viridis induced replication of a virus (designated HVCV-1) in the algae. We now report that isolation of symbiotic Chlorella-like algae from four other sources of green hydra and one source of the protozoan Paramecium bursaria also induced virus synthesis. Algae from one of these hydra contained a virus identical to HVCV-1 (based on its rate of sedimentation, buoyant density, reaction to HVCV-1 antiserum, and DNA restriction fragments) whereas algae from the other three hydra contained another similar, but distinct, virus (designated HVCV-2). The virus from the paramecium algae (designated PBCV-1) was distinct from both HVCV-1 and HVCV-2. The symbiotic algae in the hydra could also be distinguished ultrastructurally. Chloroplasts of both algae that produced HVCV-1 lacked a pyrenoid whereas chloroplasts of the other three symbiotic algae contained pyrenoids. Since all symbiotic eukaryotic algae we have examined have had virus, a potential viral role in symbiosis is suggested. Images PMID:16593198

  10. Microtubules and control of macronuclear 'amitosis' in Paramecium.

    PubMed

    Tucker, J B; Beisson, J; Roche, D L; Cohen, J

    1980-08-01

    The 'amitotic' division of the macronucleus during binary fission in P. tetraurelia includes a detailed sequence of shape changes that are temporally coordinated with the adoption of a series of well-defined positions and orientations inside the cell. The deployment of nucleoplasmic microtubules that is spatially correlated with the shaping ritual is more complex and precise than has been reported previously. Macronuclear division is not amitotic. It is not a simple constriction into two halves. As a dividing macronucleus starts to elongate it becomes dorsoventrally flattened against the dorsal cortex of the organism and assumes an elliptical shape. Concurrently, an elliptical marginal band of intranuclear microtubules assembles that has the same spatial relationship to nuclear shape as the marginal microtubules assembles that has the same spatial relationship to nuclear shape as the marginal microtubule bands of certain elliptical vertebrate blood cells have to cell shape. The band breaks down as further elongation occurs and the nucleus adopts the shape of a straight and slender sausage. Most of the intranuclear microtubules assemble as elongation starts and break down shortly after elongation is completed; the majority are oriented parallel to the longitudinal axis of the nucleus throughout elongation. Some of them are attached to nucleoli and are coated with granules which are almost certainly derived from the cortices of nucleoli. The peripheral concentration, interconnexion, orientation, and overlapping arrangement of microtubules, and the reduction in microtubule number per nuclear cross-section as elongation proceeds at a rate of about 40 micrometers min-1, are all compatible with the provision of a microtubule sliding mechanism as the main skeletal basis for elongation. There are indications that this mechanism is augmented by anchorage and/or active propulsion of nucleoli that may perhaps facilitate fairly equitable segregation of chromosomal material to

  11. Attempts to retreat from a dead-ended long capillary by backward swimming in Paramecium

    PubMed Central

    Kunita, Itsuki; Kuroda, Shigeru; Ohki, Kaito; Nakagaki, Toshiyuki

    2014-01-01

    We have observed how the ciliate Paramecium attempts to retreat from the dead-end of a long capillary that is too narrow for turning. After many trial-and-error episodes of short-term backward swimming (SBS), which is the conventional avoidance behavior exhibited in free swimming when an obstacle is faced, long-term backward swimming (LBS) that lasted five to ten times longer was developed. LBS may have a beneficial effect for complete withdrawal from the capillary space, although in our experiment it was impossible for the organism to do so due to the capillary length. In order to identify a physically possible mechanism for LBS, we propose model equations for the membrane potential of Hodgkin–Huxley type, which describe the control of ciliary movement. The physiological implications and physical mechanism of the development of LBS are discussed. PMID:24966852

  12. Ca2+-dependent regulation of beat frequency of cilia in Paramecium.

    PubMed

    Nakaoka, Y; Tanaka, H; Oosawa, F

    1984-01-01

    Triton-extracted models of Paramecium cells prepared in the presence of Mg2+ and EGTA showed Ca2+ sensitivity not only in the direction of beat but also in the beat frequency of cilia. The beat frequency increased over a range of concentration of Ca2+ from 2 X 10(-7) to 4 X 10(-7) M, in which the model swam forwards. The frequency increased also above 10(-6)M-Ca2+, in which the model swam backwards. The increase in frequency was inhibited by calmodulin antagonists. Intracellular injection of a Ca2+ buffer giving a free Ca2+ concentration of 2 X 10(-7) to 5 X 10(-7) M in intact cells induced an increase in the beat frequency. Therefore, it is very likely that the beat frequency of cilia is regulated by the intracellular concentration of Ca2+. PMID:6715425

  13. Calcium and microtubule sliding in ciliary axonemes isolated from Paramecium caudatum.

    PubMed

    Mogami, Y; Takahashi, K

    1983-05-01

    Microtubule sliding was induced in axonemes obtained from isolated cilia of Paramecium caudatum when they were exposed to a reactivating solution containing ATP after mild treatment with trypsin. Over a very wide range of concentrations (1 nM-4 mM), Ca2+ in the reactivating solution had no effect on the proportion of axonemes that disintegrated as the result of microtubule sliding. Also, the velocity of sliding, determined by cinematography, and the polarity of the direction of sliding-force generation, determined by electron microscopy with regards to the base-to-tip axis of the cilium, were not affected by Ca2+. The results indicate that the Ca sensitivity, which is responsible for the ciliary reversal response, was removed from the axoneme, possibly as the result of trypsin treatment. It is thus unlikely that Ca sensitivity is attributable to the basic sliding machinery that powers ciliary movement. PMID:6885936

  14. Differential regulation of Paramecium ciliary motility by cAMP and cGMP.

    PubMed

    Bonini, N M; Nelson, D L

    1988-05-01

    cAMP and cGMP had distinct effects on the regulation of ciliary motility in Paramecium. Using detergent-permeabilized cells reactivated to swim with MgATP, we observed effects of cyclic nucleotides and interactions with Ca2+ on the swimming speed and direction of reactivated cells. Both cAMP and cGMP increased forward swimming speed two- to threefold with similar half-maximal concentrations near 0.5 microM. The two cyclic nucleotides, however, had different effects in antagonism with the Ca2+ response of backward swimming and on the handedness of the helical swimming paths of reactivated cells. These results suggest that cAMP and cGMP differentially regulate the direction of the ciliary power stroke. PMID:2836435

  15. Mutational Analysis of Mating Type Inheritance in Syngen 4 of PARAMECIUM AURELIA.

    PubMed

    Byrne, B C

    1973-05-01

    Six genic mutations restricting clones to mating type VII (O) were isolated in syngen 4, Paramecium aurelia. The only three extensively tested were neither allelic nor closely linked. A second type of mutation, allelic to one of the O restricted mutants, was also found. Clones homozygous for this mutant gene were selfers, producing both O and E (VIII) mating types, but only when they were progeny of mating type E parental clones. While all seven mutant genes behaved as recessives in monohybrid crosses, clones heterozygous at two different loci often demonstrated an unanticipated phenotype: selfing. The significance of the findings is discussed in relation to mating type determination and the evolution of mating type systems. PMID:17248611

  16. Performance Analysis of Chemotaxis Controllers: Which has Better Chemotaxis Controller, Escherichia coli or Paramecium caudatum?

    PubMed

    Azuma, Shun-Ichi; Owaki, Katsuya; Shinohara, Nobuhiro; Sugie, Toshiharu

    2016-01-01

    Chemotaxis is the biological phenomenon in which organisms move to a more favorable location in an environment with a chemical attractant or repellent. Since chemotaxis is a typical example of the environmental response of organisms, it is a fundamental topic in biology and related fields. We discuss the performance of the internal controllers that generate chemotaxis. We first propose performance indices to evaluate the controllers. Based on these indices, we evaluate the performance of two controller models of Escherichia coli and Paramecium caudatum. As a result, it is disclosed that the E. coli-type controller achieves chemotaxis quickly but roughly, whereas the P. caudatum-type controller achieves it slowly but precisely. This result will be a biological contribution from a control theoretic point of view. PMID:26336141

  17. Effect of Cypermethrin on the Growth of Ciliate Protozoan Paramecium caudatum

    PubMed Central

    Dutta, Joydeep

    2015-01-01

    Objective: The objective of this study is to assess the effect of cypermethrin on the growth of ciliate protozoan Paramecium caudatum. Materials and Methods: Monoxenic culture of P. caudatum, were exposed to different doses (0.01, 0.05, 0.1, 0.15, and 0.2 µg/L) of cypermethrin along with control for 24, 48, 72, and 96 h time interval. The total numbers of live and dead cells were counted after trypan blue staining in Neubauer hemocytometer. Results: Marked decrease in the number of living cells with the increase in the concentration of cypermethrin and with increasing exposure time intervals was recorded. Conclusion: The results indicate that cypermethrin is toxic to P. caudatum even at low concentrations when it enters in the aquatic system through runoff. PMID:26862268

  18. Mutational Analysis of Mating Type Inheritance in Syngen 4 of PARAMECIUM AURELIA

    PubMed Central

    Byrne, Bruce C.

    1973-01-01

    Six genic mutations restricting clones to mating type VII (O) were isolated in syngen 4, Paramecium aurelia. The only three extensively tested were neither allelic nor closely linked. A second type of mutation, allelic to one of the O restricted mutants, was also found. Clones homozygous for this mutant gene were selfers, producing both O and E (VIII) mating types, but only when they were progeny of mating type E parental clones. While all seven mutant genes behaved as recessives in monohybrid crosses, clones heterozygous at two different loci often demonstrated an unanticipated phenotype: selfing. The significance of the findings is discussed in relation to mating type determination and the evolution of mating type systems. PMID:17248611

  19. Temporal variation in temperature determines disease spread and maintenance in Paramecium microcosm populations

    PubMed Central

    Duncan, Alison B.; Fellous, Simon; Kaltz, Oliver

    2011-01-01

    The environment is rarely constant and organisms are exposed to temporal and spatial variations that impact their life histories and inter-species interactions. It is important to understand how such variations affect epidemiological dynamics in host–parasite systems. We explored effects of temporal variation in temperature on experimental microcosm populations of the ciliate Paramecium caudatum and its bacterial parasite Holospora undulata. Infected and uninfected populations of two P. caudatum genotypes were created and four constant temperature treatments (26°C, 28°C, 30°C and 32°C) compared with four variable treatments with the same mean temperatures. Variable temperature treatments were achieved by alternating populations between permissive (23°C) and restrictive (35°C) conditions daily over 30 days. Variable conditions and high temperatures caused greater declines in Paramecium populations, greater fluctuations in population size and higher incidence of extinction. The additional effect of parasite infection was additive and enhanced the negative effects of the variable environment and higher temperatures by up to 50 per cent. The variable environment and high temperatures also caused a decrease in parasite prevalence (up to 40%) and an increase in extinction (absence of detection) (up to 30%). The host genotypes responded similarly to the different environmental stresses and their effect on parasite traits were generally in the same direction. This work provides, to our knowledge, the first experimental demonstration that epidemiological dynamics are influenced by environmental variation. We also emphasize the need to consider environmental variance, as well as means, when trying to understand, or predict population dynamics or range. PMID:21450730

  20. Temporal variation in temperature determines disease spread and maintenance in Paramecium microcosm populations.

    PubMed

    Duncan, Alison B; Fellous, Simon; Kaltz, Oliver

    2011-11-22

    The environment is rarely constant and organisms are exposed to temporal and spatial variations that impact their life histories and inter-species interactions. It is important to understand how such variations affect epidemiological dynamics in host-parasite systems. We explored effects of temporal variation in temperature on experimental microcosm populations of the ciliate Paramecium caudatum and its bacterial parasite Holospora undulata. Infected and uninfected populations of two P. caudatum genotypes were created and four constant temperature treatments (26°C, 28°C, 30°C and 32°C) compared with four variable treatments with the same mean temperatures. Variable temperature treatments were achieved by alternating populations between permissive (23°C) and restrictive (35°C) conditions daily over 30 days. Variable conditions and high temperatures caused greater declines in Paramecium populations, greater fluctuations in population size and higher incidence of extinction. The additional effect of parasite infection was additive and enhanced the negative effects of the variable environment and higher temperatures by up to 50 per cent. The variable environment and high temperatures also caused a decrease in parasite prevalence (up to 40%) and an increase in extinction (absence of detection) (up to 30%). The host genotypes responded similarly to the different environmental stresses and their effect on parasite traits were generally in the same direction. This work provides, to our knowledge, the first experimental demonstration that epidemiological dynamics are influenced by environmental variation. We also emphasize the need to consider environmental variance, as well as means, when trying to understand, or predict population dynamics or range. PMID:21450730

  1. Mendelian and non-mendelian mutations affecting surface antigen expression in Paramecium tetraurelia

    SciTech Connect

    Epstein, L.M.; Forney, J.D.

    1984-08-01

    A screening procedure was devised for the isolation of X-ray-induced mutations affecting the expression of the A immobilization antigen (i-antigen) in Paramecium tetraurelia. Two of the mutations isolated by this procedure proved to be in modifier genes. The two genes are unlinked to each other and unlinked to the structural A i-antigen gene. These are the first modifier genes identified in a Paramecium sp. that affect surface antigen expression. Another mutation was found to be a deletion of sequences just downstream from the A i-antigen gene. In cells carrying this mutation, the A i-antigen gene lies in close proximity to the end of a macronuclear chromosome. The expression of the A i-antigen is not affected in these cells, demonstrating that downstream sequences are not important for the regulation and expression of the A i-antigen gene. A stable cell line was also recovered which shows non-Mendelian inheritance of a macronuclear deletion of the A i-antigen gene. This mutant does not contain the gene in its macronucleus, but contains a complete copy of the gene in its micronucleus. In the cytoplasm of wild-type animals, the micronuclear gene is included in the developing macronucleus; in the cytoplasm of the mutant, the incorporation of the A i-antigen gene into the macronucleus is inhibited. This is the first evidence that a mechanism is available in ciliates to control the expression of a gene by regulating its incorporation into developing macronuclei.

  2. Paramecium caudatum enhances transmission and infectivity of Mycobacterium marinum and Mycobacterium chelonae in zebrafish (Danio rerio)

    PubMed Central

    Peterson, Tracy S.; Ferguson, Jayde A.; Watral, Virginia G.; Mutoji, K. Nadine; Ennis, Don G.; Kent, Michael L.

    2014-01-01

    Mycobacterial infections in laboratory zebrafish (Danio rerio) are common and widespread in research colonies. Mycobacteria within free living amoebae have been shown to be transmission vectors for mycobacteriosis. Paramecium caudatum are commonly used as a first food for zebrafish, and we investigated this ciliate’s potential to serve as a vector of Mycobacterium marinum and M. chelonae. The ability of live P. caudatum to transmit these mycobacteria to larval, juvenile and adult zebrafish was evaluated. Infections were defined by histologic observation of granulomas containing acid-fast bacteria in extraintestinal locations. In both experiments, fish fed paramecia containing mycobacteria became infected at a higher incidence than controls. Larvae (exposed at 4 days post hatch) fed paramecia with M. marinum exhibited an incidence of 30% (24/80) and juveniles (exposed at 21 days post hatch) showed 31% incidence (14/45). Adult fish fed a gelatin food matrix containing mycobacteria within paramecia or mycobacteria alone for 2 wk resulted in infections when examined 8 wk after exposure as follows: M. marinum OSU 214 47% (21/45), M. marinum CH 47% (9/19), M. chelonae 38% (5/13). In contrast, fish feed mycobacteria alone in this diet did not become infected, except for 2 fish (5%) in the M. marinum OSU 214 low dose group. These results demonstrate that Paramecium caudatum can act as a vector for mycobacteria. This provides a useful animal model for evaluation of natural mycobacterial infections and demonstrates the possibility of mycobacterial transmission in zebrafish facilities via contaminated paramecia cultures. PMID:24192000

  3. Novel Insights into the Development and Function of Cilia Using the Advantages of the Paramecium Cell and Its Many Cilia

    PubMed Central

    Yano, Junji; Valentine, Megan S.; Van Houten, Judith L.

    2015-01-01

    Paramecium species, especially P. tetraurelia and caudatum, are model organisms for modern research into the form and function of cilia. In this review, we focus on the ciliary ion channels and other transmembrane proteins that control the beat frequency and wave form of the cilium by controlling the signaling within the cilium. We put these discussions in the context of the advantages that Paramecium brings to the understanding of ciliary motility: mutants for genetic dissections of swimming behavior, electrophysiology, structural analysis, abundant cilia for biochemistry and modern proteomics, genomics and molecular biology. We review the connection between behavior and physiology, which allows the cells to broadcast the function of their ciliary channels in real time. We build a case for the important insights and advantages that this model organism continues to bring to the study of cilia. PMID:26230712

  4. Novel Insights into the Development and Function of Cilia Using the Advantages of the Paramecium Cell and Its Many Cilia.

    PubMed

    Yano, Junji; Valentine, Megan S; Van Houten, Judith L

    2015-01-01

    Paramecium species, especially P. tetraurelia and caudatum, are model organisms for modern research into the form and function of cilia. In this review, we focus on the ciliary ion channels and other transmembrane proteins that control the beat frequency and wave form of the cilium by controlling the signaling within the cilium. We put these discussions in the context of the advantages that Paramecium brings to the understanding of ciliary motility: mutants for genetic dissections of swimming behavior, electrophysiology, structural analysis, abundant cilia for biochemistry and modern proteomics, genomics and molecular biology. We review the connection between behavior and physiology, which allows the cells to broadcast the function of their ciliary channels in real time. We build a case for the important insights and advantages that this model organism continues to bring to the study of cilia. PMID:26230712

  5. Influence on cell proliferation of background radiation or exposure to very low, chronic gamma radiation. [Paramecium tetraurelia; Synechococcus lividus

    SciTech Connect

    Planel, H.; Soleilhavoup, J.P.; Tixador, R.; Richoilley, G.; Conter, A.; Croute, F.; Caratero, C.; Gaubin, Y.

    1987-05-01

    Investigations carried out on the protozoan Paramecium tetraurelia and the cyanobacteria Synechococcus lividus, which were shielded against background radiation or exposed to very low doses of gamma radiation, demonstrated that radiation can stimulate the proliferation of these two single-cell organisms. Radiation hormesis depends on internal factors (age of starting cells) and external factors (lighting conditions). The stimulatory effect occurred only in a limited range of doses and disappeared for dose rates higher than 50 mGy/y.

  6. 808-nm laser therapy with a flat-top handpiece photobiomodulates mitochondria activities of Paramecium primaurelia (Protozoa).

    PubMed

    Amaroli, Andrea; Ravera, Silvia; Parker, Steven; Panfoli, Isabella; Benedicenti, Alberico; Benedicenti, Stefano

    2016-05-01

    Photobiomodulation is proposed as a non-linear process, and only low-level laser therapy (LLLT) is assumed to stimulate exposed cells, whereas high powered laser and fluences can cause negative effects, exhausting the cell's energy reserve as a consequence of excessive photon-based stimulation. In our work, we investigated and compared the effects of 808-nm diode laser (CW) with a new flat-top handpiece. To this purpose, we tested the photobiomodulation effects of 1 and 3 J/cm(2) fluence, both generated by 100 mW or 1 W of laser power and of 64 J/cm(2) of fluence generated by 100 mW, 1 W, 1.5 W or 2 W, as expressed through oxygen consumption and ATP synthesis of Paramecium. Data collected indicates the incremental consumption of oxygen through irradiation with 3 J/cm(2)-100 mW or 64 J/cm(2)-1 W correlates with an increase in Paramecium ATP synthesis. The Paramecium respiration was inhibited by fluences 64 J/cm(2)-100 mW or 64 J/cm(2)-2 W and was followed by a decrease in the endogenous ATP concentration. The 1 J/cm(2)-100 mW or 1 W and 3 J/cm(2)-1 W did not affect mitochondrial activity. The results show that the fluence of 64 J/cm(2)-1 W more than the 3 J/cm(2)-100 mW causes greater efficiency in Paramecium mitochondria respiratory chain activity. Our results suggest that thanks to flat-top handpiece we used, high fluences by high-powered laser have to be reconsidered as an effective and non-invasive therapy. Possible associated benefits of deeper tissue penetration would increase treatment effectiveness and reduced irradiation time. PMID:26984347

  7. Cross-study analysis of genomic data defines the ciliate multigenic epiplasmin family: strategies for functional analysis in Paramecium tetraurelia

    PubMed Central

    Damaj, Raghida; Pomel, Sébastien; Bricheux, Geneviève; Coffe, Gérard; Viguès, Bernard; Ravet, Viviane; Bouchard, Philippe

    2009-01-01

    Background The sub-membranous skeleton of the ciliate Paramecium, the epiplasm, is composed of hundreds of epiplasmic scales centered on basal bodies, and presents a complex set of proteins, epiplasmins, which belong to a multigenic family. The repeated duplications observed in the P. tetraurelia genome present an interesting model of the organization and evolution of a multigenic family within a single cell. Results To study this multigenic family, we used phylogenetic, structural, and analytical transcriptional approaches. The phylogenetic method defines 5 groups of epiplasmins in the multigenic family. A refined analysis by Hydrophobic Cluster Analysis (HCA) identifies structural characteristics of 51 epiplasmins, defining five separate groups, and three classes. Depending on the sequential arrangement of their structural domains, the epiplasmins are defined as symmetric, asymmetric or atypical. The EST data aid in this classification, in the identification of putative regulating sequences such as TATA or CAAT boxes. When specific RNAi experiments were conducted using sequences from either symmetric or asymmetric classes, phenotypes were drastic. Local effects show either disrupted or ill-shaped epiplasmic scales. In either case, this results in aborted cell division. Using structural features, we show that 4 epiplasmins are also present in another ciliate, Tetrahymena thermophila. Their affiliation with the distinctive structural groups of Paramecium epiplasmins demonstrates an interspecific multigenic family. Conclusion The epiplasmin multigenic family illustrates the history of genomic duplication in Paramecium. This study provides a framework which can guide functional analysis of epiplasmins, the major components of the membrane skeleton in ciliates. We show that this set of proteins handles an important developmental information in Paramecium since maintenance of epiplasm organization is crucial for cell morphogenesis. PMID:19493334

  8. An automated assay for quantifying the swimming behavior of Paramecium and its use to study cation responses.

    PubMed

    Clark, K D; Nelson, D L

    1991-01-01

    Paramecium tetraurelia is a ciliated protist that alters its swimming behavior in response to various stimuli. Like the sensory responses of many organisms, these responses in Paramecium show adaptation to continued stimulation. For quantitative studies of the initial response to stimulation, and of the time course of adaptation, we have developed a computerized motion analysis assay that can detect deviations from the normal swimming pattern in a population of cells. The motion of an average of ten cells was quantified during periods ranging from 15 to 60 seconds, with a time resolution of 1/15 seconds. During normal forward swimming, the maximum deviation from a straight-line path was less than 17 degrees. Path deviations above this threshold value were defined as changes in swimming direction. The percentage of total path time that cells spent deviating from forward swimming was defined as percent directional changes (PDC). This parameter was used to construct dose-response curves for the behavioral effects of various externally added cations known to induce behavioral changes and also to show the time course of adaptation to a depolarizing K+ stimulus. This assay is a valuable tool for studies of chemoeffectors or mutations that alter the swimming behavior of Paramecium and may also be applicable to other motile organisms. PMID:1878982

  9. Different polyamine pathways from bacteria have replaced eukaryotic spermidine biosynthesis in ciliates Tetrahymena thermophila and Paramecium tetaurelia.

    PubMed

    Li, Bin; Kim, Sok Ho; Zhang, Yang; Hanfrey, Colin C; Elliott, Katherine A; Ealick, Steven E; Michael, Anthony J

    2015-09-01

    The polyamine spermidine is absolutely required for growth and cell proliferation in eukaryotes, due to its role in post-translational modification of essential translation elongation factor eIF5A, mediated by deoxyhypusine synthase. We have found that free-living ciliates Tetrahymena and Paramecium lost the eukaryotic genes encoding spermidine biosynthesis: S-adenosylmethionine decarboxylase (AdoMetDC) and spermidine synthase (SpdSyn). In Tetrahymena, they were replaced by a gene encoding a fusion protein of bacterial AdoMetDC and SpdSyn, present as three copies. In Paramecium, a bacterial homospermidine synthase replaced the eukaryotic genes. Individual AdoMetDC-SpdSyn fusion protein paralogues from Tetrahymena exhibit undetectable AdoMetDC activity; however, when two paralogous fusion proteins are mixed, AdoMetDC activity is restored and spermidine is synthesized. Structural modelling indicates a functional active site is reconstituted by sharing critical residues from two defective protomers across the heteromer interface. Paramecium was found to accumulate homospermidine, suggesting it replaces spermidine for growth. To test this concept, a budding yeast spermidine auxotrophic strain was found to grow almost normally with homospermidine instead of spermidine. Biosynthesis of spermidine analogue aminopropylcadaverine, but not exogenously provided norspermidine, correlated with some growth. Finally, we found that diverse single-celled eukaryotic parasites and multicellular metazoan Schistosoma worms have lost the spermidine biosynthetic pathway but retain deoxyhypusine synthase. PMID:25994085

  10. The membrane skeleton in Paramecium: Molecular characterization of a novel epiplasmin family and preliminary GFP expression results.

    PubMed

    Pomel, Sébastien; Diogon, Marie; Bouchard, Philippe; Pradel, Lydie; Ravet, Viviane; Coffe, Gérard; Viguès, Bernard

    2006-02-01

    Previous attempts to identify the membrane skeleton of Paramecium cells have revealed a protein pattern that is both complex and specific. The most prominent structural elements, epiplasmic scales, are centered around ciliary units and are closely apposed to the cytoplasmic side of the inner alveolar membrane. We sought to characterize epiplasmic scale proteins (epiplasmins) at the molecular level. PCR approaches enabled the cloning and sequencing of two closely related genes by amplifications of sequences from a macronuclear genomic library. Using these two genes (EPI-1 and EPI-2), we have contributed to the annotation of the Paramecium tetraurelia macronuclear genome and identified 39 additional (paralogous) sequences. Two orthologous sequences were found in the Tetrahymena thermophila genome. Structural analysis of the 43 sequences indicates that the hallmark of this new multigenic family is a 79 aa domain flanked by two Q-, P- and V-rich stretches of sequence that are much more variable in amino-acid composition. Such features clearly distinguish members of the multigenic family from epiplasmic proteins previously sequenced in other ciliates. The expression of Green Fluorescent Protein (GFP)-tagged epiplasmin showed significant labeling of epiplasmic scales as well as oral structures. We expect that the GFP construct described herein will prove to be a useful tool for comparative subcellular localization of different putative epiplasmins in Paramecium. PMID:16427359

  11. Trichocyst ribbons of a cryptomonads are constituted of homologs of R-body proteins produced by the intracellular parasitic bacterium of Paramecium.

    PubMed

    Yamagishi, Takahiro; Kai, Atsushi; Kawai, Hiroshi

    2012-04-01

    Trichocysts are ejectile organelles found in cryptomonads, dinoflagellates, and peniculine ciliates. The fine structure of trichocysts differs considerably among lineages, and their evolutionary relationships are unclear. The biochemical makeup of the trichocyst constituents has been studied in the ciliate Paramecium, but there have been no investigations of cryptomonads and dinoflagellates. Furthermore, morphological similarity between the contents of cryptomonad trichocysts and the R-bodies of the endosymbiotic bacteria of Paramecium has been reported. In this study, we identified the proteins of the trichocyst constituents in a red cryptomonad, Pyrenomonas helgolandii, and found their closest relationships to be with rebB that comprises the R-bodies of Caedibacter taeniospiralis (gammaproteobacteria), which is an endosymbiont of Paramecium. In addition, the biochemical makeups of the trichocysts are entirely different between cryptomonads and peniculine ciliates, and therefore, cryptomonad trichocysts have an evolutionary origin independent from the peniculine ciliate trichocysts. PMID:22447322

  12. Spliced DNA Sequences in the Paramecium Germline: Their Properties and Evolutionary Potential

    PubMed Central

    Catania, Francesco; McGrath, Casey L.; Doak, Thomas G.; Lynch, Michael

    2013-01-01

    Despite playing a crucial role in germline-soma differentiation, the evolutionary significance of developmentally regulated genome rearrangements (DRGRs) has received scant attention. An example of DRGR is DNA splicing, a process that removes segments of DNA interrupting genic and/or intergenic sequences. Perhaps, best known for shaping immune-system genes in vertebrates, DNA splicing plays a central role in the life of ciliated protozoa, where thousands of germline DNA segments are eliminated after sexual reproduction to regenerate a functional somatic genome. Here, we identify and chronicle the properties of 5,286 sequences that putatively undergo DNA splicing (i.e., internal eliminated sequences [IESs]) across the genomes of three closely related species of the ciliate Paramecium (P. tetraurelia, P. biaurelia, and P. sexaurelia). The study reveals that these putative IESs share several physical characteristics. Although our results are consistent with excision events being largely conserved between species, episodes of differential IES retention/excision occur, may have a recent origin, and frequently involve coding regions. Our findings indicate interconversion between somatic—often coding—DNA sequences and noncoding IESs, and provide insights into the role of DNA splicing in creating potentially functional genetic innovation. PMID:23737328

  13. Variety of serotypes of Paramecium primaurelia: single epitopes are responsible for immunological differentiation.

    PubMed

    Simon, Martin C; Schmidt, Helmut J

    2005-01-01

    Paramecium primaurelia expresses three major types of surface antigens. We report here the identification of the gene for serotype S, which completes the sequence data of expressed serotypes of P. primaurelia. The complete open reading frame of surface antigen S was identified using a novel technique, based upon the presence of conservative regions in the non-coding areas of the multigene family. We were able to isolate the 7194-bp-long open reading frame from the macronuclear DNA for Serotype 156S. The corresponding mRNA was detected in the two serotype S-expressing stocks, 60 and 156, of P. primaurelia, which clarifies that both stocks are using the same S allele. Comparisons of the nucleic acid and the deduced amino-acid sequence showed high identity to surface antigen 51B of P. tetraurelia, sufficient to cause an immunological cross-reaction in vivo. Immunologically relevant epitopes in vivo were identified in the central regions of the genes, constructed of nearly perfect tandem repeats. PMID:16014009

  14. Physical and physiological components of the graviresponses of wild-type and mutant Paramecium Tetraurelia.

    PubMed

    Nagel, U; Machemer, H

    2000-03-01

    Wild-type and the morphological mutant kin 241 of Paramecium tetraurelia showed improved orientation away from the centre of gravity (negative gravitaxis) when accelerations were increased from 1 to 7 g. Gravitaxis was more pronounced in the mutant. A correlation between the efficiency of orientation and the applied g value suggests a physical basis for gravitaxis. Transiently enhanced rates of reversal of the swimming direction coincided with transiently enhanced gravitaxis because reversals occurred more often in downward swimmers than in upward swimmers. The results provide evidence of a physiological modulation of gravitaxis by means of the randomizing effect of depolarization-dependent swimming reversals. Gravity bimodally altered propulsion rates of wild-type P. tetraurelia so that sedimentation was partly antagonized in upward and downward swimmers (negative gravikinesis). In the mutant, only increases in propulsion were observed, although the orientation-dependent sensitivity of the gravikinetic response was the same as in the wild-type population. Observed swimming speed and sedimentation rates in the wild-type and mutant cells were linearly related to acceleration, allowing the determination of gravikinesis as a linear (and so far non-saturating) function of gravity. PMID:10683165

  15. Control of the ciliary beat by cyclic nucleotides in intact cortical sheets from Paramecium.

    PubMed

    Noguchi, Munenori; Kurahashi, Shotaro; Kamachi, Hiroyuki; Inoue, Hiroshi

    2004-12-01

    The locomotor behavior of Paramecium depends on the ciliary beat direction and beat frequency. Changes in the ciliary beat are controlled by a signal transduction mechanism that follows changes in the membrane potential. These events take place in cilia covered with a ciliary membrane. To determine the effects of second messengers in the cilia, cortical sheets were used with intact ciliary membrane as a half-closed system in which each cilium is covered with a ciliary membrane with an opening to the cell body. Cyclic nucleotides and their derivatives applied from an opening to the cell body affected the ciliary beat. cAMP and 8-Br-cAMP increased the beat frequency and the efficiency of propulsion and acted antagonistically to the action of Ca(2+). cGMP and 8-Br-cGMP increased the efficiency of propulsion accompanying clear metachronal waves but decreased the beat frequency. These results indicate that the cyclic nucleotides affect target proteins in the ciliary axonemes surrounded by the ciliary membrane without a membrane potential and increase the efficiency of propulsion of the ciliary beat. In vitro phosphorylation of isolated ciliary axonemes in the presence of cyclic nucleotides and their derivatives revealed that the action of cAMP was correlated with the phosphorylation of 29-kDa and 65-kDa proteins and that the action of cGMP was correlated with the phosphorylation of a 42-kDa protein. PMID:15613797

  16. Amphipathic amines affect membrane excitability in paramecium: role for bilayer couple.

    PubMed

    Browning, J L; Nelson, D L

    1976-02-01

    Amphipathic amines and local anesthetics stimulated reversal of the ciliary beating direction in wild-type Paramecium. Ca++ influx across the surface membrane and the consequent increase in internal Ca++ causes ciliary reversal and backward swimming. Mutant cells of the "Pawn" class, which lack a "gating" mechanism for regulating Ca++ influx, did not swim backwards in the presence of local anesthetics. Local anesthetics stimulated the passive efflux of K+ but had no effect on the active transport of K+ or Ca++. Apparently passive influx of Ca++ also was stimulated by local anesthetics as evidenced by their effects on swimming direction. These data can be interpreted in terms of the "bilayer couple" hypothesis of Sheetz and Singer [(1974) Proc. Nat. Acad. Sci. USA 71, 4457-4461]: amphipathic drugs affect cells by asymmetric insertion into one face of the lipid bilayer. As predicted by this hypothesis, the drugs' effects were seen only after a short time lag, and quaternary amines were less effective than tertiary amines. The effect on behavior was caused by any of several amphipathic cations, and the relative potency was a function of their hydrophobicity. Amphipathic anions, which according to the hypothesis would insert into the opposite face of the lipid bilayer, had little effect on ciliary reversal. Asymmetric perturbation of the lipid bilayer with amphipathic cations may trigger the opening of the Ca++ gate. PMID:1061147

  17. The native structure of cytoplasmic dynein at work translocating vesicles in Paramecium.

    PubMed

    Ishida, Masaki; Aihara, Marilynn S; Allen, Richard D; Fok, Agnes K

    2011-01-01

    In Paramecium multimicronucleatum, the discoidal vesicles, the acidosomes and the 100-nm carrier vesicles are involved in phagosome formation, phagosome acidification and endosomal processing, respectively. Numerous cross bridges link these vesicles to the kinetic side of the microtubules of a cytopharyngeal microtubular ribbon. Vesicles are translocated along these ribbons in a minus-end direction towards the cytopharynx. A monoclonal antibody specific for the light vanadate-photocleaved fragment of the heavy chain of cytoplasmic dynein was used to show that this dynein is located between the discoidal vesicles and the ribbons as well as on the cytosolic surface of the acidosomes and the 100-nm carrier vesicles. This antibody inhibited the docking of the vesicles to the microtubular ribbons so that the transport of discoidal vesicles and acidosomes were reduced by 60% and 70%, respectively. It had little effect on the dynein's velocity of translocation. These results show that cytoplasmic dynein is the motor for vesicle translocation and its location, between the vesicles and the ribbons, indicates that the cross bridges seen at this location in thin sections and in quick-frozen, deep-etched replicas are apparently the working dyneins. Such a working dynein cross bridge, as preserved by ultra-rapid freezing, is 54 nm long and has two legs arising from a globular head that appears to be firmly bound to its cargo vesicle and each leg consists of ≥3 beaded subunits with the last subunit making contact with the microtubular ribbon. PMID:20837374

  18. Interactions of membrane potential and cations in regulation of ciliary activity in Paramecium.

    PubMed

    Machemer, H

    1976-10-01

    Ciliary activity in Paramecium was investigated in different external solutions using techniques of voltage clamp and high frequency cinematography. An increase in the external concentration of K, Ca or Mg ions decreased the resting potential. It had no effect on ciliary activity. When the membrane potential was fixed, an increase in external Ca or Mg and, to a lesser extent, an increase in K concentration, raised the frequency of normal beating or decreased the frequency of reversed beating of the cilia. Similar effects resulted from membrane hyperpolarization with constant ionic conditions. Increase in concentration of Ca, but not of Mg or K, enhanced hyperpolarization-induced augmentation of ciliary frequency. Increase in Ca concentration also specifically augmented the delayed increase in inward current during rapid hyperpolarizing clamp. The results support the view that [Ca]i regulates the frequency and direction of ciliary beating. It is suggested that the insensitivity of the ciliary motor system to elevations of the external concentrations of ions results from compensation of their effects on [Ca]i. Depolarization itself appears to increase [Ca]i while elevation of the external ion concentrations at a fixed membrane potential appears to decrease [Ca]i. PMID:1003088

  19. RECONSTITUTION OF METACHRONAL WAVES IN CILIATED CORTICAL SHEETS OF PARAMECIUM - ASYMMETRY OF THE CILIARY MOVEMENTS

    PubMed

    Okamoto; Nakaoka

    1994-07-01

    In conditions in which ciliated cortical sheets prepared from detergent-extracted Paramecium multimicronucleatum cells adhered to glass coverslips on a microscope stage, perfusion of a reactivation medium containing ATP plus cyclic AMP or cyclic GMP generated metachronal waves. An analysis of the ciliary movements that generate these metachronal waves yielded the following results. During the generation of metachronal waves, there were phase differences in the ciliary orientation of adjacent cilia in the direction of wave propagation. Addition of cyclic AMP or cyclic GMP increased the rotational angular velocities during the effective stroke of ciliary beating, but did not increase the rotational angular velocity of the recovery stroke. When the ATP concentration in the cyclic GMP reactivation medium was increased, the rotational angular velocity during the effective stroke rose steeply and saturated at 0.8 mmol l-1 ATP, whereas that during the recovery stroke rose gradually. Addition of cyclic nucleotides caused a single cilium isolated from neighbouring cilia on the cortical sheet to incline almost parallel to the cortical surface during the recovery stroke. Addition of cyclic GMP increased the amplitude of bending of cilia detached from the cortical sheet. From these results, it was concluded that increases in the asymmetrical movement of individual cilia, caused by the addition of cyclic nucleotides, create the ciliary interaction that generates the metachronal waves. PMID:9317363

  20. Ionic control of the reversal response of cilia in Paramecium caudatum. A calcium hypothesis.

    PubMed

    Naitoh, Y

    1968-01-01

    The duration of ciliary reversal of Paramecium caudatum in response to changes in external ionic factors was determined with various ionic compositions of both equilibration and stimulation media. The reversal response was found to occur when calcium ions bound by an inferred cellular cation exchange system were liberated in exchange for externally applied cations other than calcium. Factors which affect the duration of the response were (a) initial amount of calcium bound by the cation exchange system, (b) final amount of calcium bound by the system after equilibration with the stimulation medium, and (c) concentration of calcium ions in the stimulation medium. An empirical equation is presented which relates the duration of the response to these three factors. On the basis of these and previously published data, the following hypothesis is proposed for the mechanism underlying ciliary reversal in response to cationic stimulation: Ca(++) liberated from the cellular cation exchange system activates a contractile system which is energized by ATP. Contraction of this component results in the reversal of effective beat direction of cilia by a mechanism not yet understood. The duration of reversal in live paramecia is related to the time course of bound calcium release. PMID:4966766

  1. Delayed degradation of parental macronuclear DNA in programmed nuclear death of Paramecium caudatum.

    PubMed

    Kimura, Naomi; Mikami, Kazuyuki; Endoh, Hiroshi

    2004-09-01

    In the ciliated protozoan Paramecium caudatum, a parental macronucleus that is fragmented into some 40-50 pieces during conjugation does not degenerate immediately, but persists until the eighth cell cycle after conjugation. Here we demonstrate that the initiation of the parental macronuclear degeneration occurs at about the fifth cell cycle. The size of parental macronuclear fragments continued to increase between the first and fourth cell cycle, but gradually decreased thereafter. By contrast, a new macronucleus grew and reached a maximum size by the fourth cell cycle, suggesting that the new macronucleus matured by that stage. Southern blot analysis revealed that parental macronuclear DNA was degraded at about the fifth cell cycle. The degradation was supported by acridine orange staining, indicating degeneration of the macronuclear fragments. Prior to the degradation, the fragments once attached to the new macronucleus were subsequently liberated from it. These observations lead us to conclude that once a new macronucleus has been fully formed by the fourth cell cycle, the parental macronuclear fragments are destined to degenerate, probably through direction by new macronucleus. Considering the long persistence of the parental macronucleus during the early cell cycles after conjugation, the macronuclear fragments might function in the maturation of the imperfect new macronucleus. Two possible functions, a gene dosage compensation and adjustment of ploidy level, are discussed. PMID:15354289

  2. Photolysis of caged calcium in cilia induces ciliary reversal in Paramecium caudatum.

    PubMed

    Iwadate, Yoshiaki

    2003-04-01

    Intracellular Ca(2+) concentration controls both the pattern and frequency of ciliary and flagellar beating in eukaryotes. In Paramecium, it is widely accepted that the reversal of the direction of ciliary beating (ciliary reversal) is induced by an increase in intra-ciliary Ca(2+) levels. Despite this, the Ca(2+)-sensitive region of the cilium that initiates ciliary reversal has not been clearly identified. We injected caged calcium into living P. caudatum cells and applied ultraviolet (UV) light to portions of the injected cells to raise artificially the intracellular Ca(2+) level ([Ca(2+)](i)). UV application to the upper ciliary region above the basal body induced ciliary reversal in injected cells. Furthermore, UV application to the tips of cilia induced weak ciliary reversal. Larger areas of photolysis in the cilium gave rise to greater angles of ciliary reversal. These results strongly suggest that the Ca(2+)-sensitive region for ciliary reversal is distributed all over the cilium, above the basal body. PMID:12604576

  3. Spontaneous fluctuation of the resting membrane potential in Paramecium: amplification caused by intracellular Ca2+.

    PubMed

    Nakaoka, Yasuo; Imaji, Takafumi; Hara, Masahiro; Hashimoto, Noboru

    2009-01-01

    The ciliated protozoan Paramecium spontaneously changes its swimming direction in the absence of external stimuli. Such behavior is based on resting potential fluctuations, the amplitudes of which reach a few mV. When the resting potential fluctuation is positive and large, a spike-like depolarization is frequently elicited that reverses the beating of the cilia associated with directional changes during swimming. We aimed to study how the resting potential fluctuation is amplified. Simultaneous measurements of the resting potential and intracellular Ca(2+) ([Ca(2+)](i)) from a deciliated cell showed that positive potential fluctuations were frequently accompanied by a small increase in [Ca(2+)](i). This result suggests that Ca(2+) influx through the somatic membrane occurs during the resting state. The mean amplitude of the resting potential fluctuation was largely decreased by either an intracellular injection of a calcium chelater (BAPTA) or by an extracellular addition of Ba(2+). Hence, a small increase in [Ca(2+)](i) amplifies the resting potential fluctuation. Simulation analysis of the potential fluctuation was made by assuming that Ca(2+) and K(+) channels of surface membrane are fluctuating between open and closed states. The simulated fluctuation increased to exhibit almost the same amplitude as the measured fluctuation using the assumption that a small Ca(2+) influx activates Ca(2+) channels in a positive feedback manner. PMID:19112146

  4. Cis-acting signals modulate the efficiency of programmed DNA elimination in Paramecium tetraurelia.

    PubMed

    Ferro, Diana; Lepennetier, Gildas; Catania, Francesco

    2015-09-30

    In Paramecium, the regeneration of a functional somatic genome at each sexual event relies on the elimination of thousands of germline DNA sequences, known as Internal Eliminated Sequences (IESs), from the zygotic nuclear DNA. Here, we provide evidence that IESs' length and sub-terminal bases jointly modulate IES excision by affecting DNA conformation in P. tetraurelia. Our study reveals an excess of complementary base pairing between IESs' sub-terminal and contiguous sites, suggesting that IESs may form DNA loops prior to cleavage. The degree of complementary base pairing between IESs' sub-terminal sites (termed Cin-score) is positively associated with IES length and is shaped by natural selection. Moreover, it escalates abruptly when IES length exceeds 45 nucleotides (nt), indicating that only sufficiently large IESs may form loops. Finally, we find that IESs smaller than 46 nt are favored targets of the cellular surveillance systems, presumably because of their relatively inefficient excision. Our findings extend the repertoire of cis-acting determinants for IES recognition/excision and provide unprecedented insights into the distinct selective pressures that operate on IESs and somatic DNA regions. This information potentially moves current models of IES evolution and of mechanisms of IES recognition/excision forward. PMID:26304543

  5. Virus-host interactions: insights from the replication cycle of the large Paramecium bursaria chlorella virus.

    PubMed

    Milrot, Elad; Mutsafi, Yael; Fridmann-Sirkis, Yael; Shimoni, Eyal; Rechav, Katya; Gurnon, James R; Van Etten, James L; Minsky, Abraham

    2016-01-01

    The increasing interest in cytoplasmic factories generated by eukaryotic-infecting viruses stems from the realization that these highly ordered assemblies may contribute fundamental novel insights to the functional significance of order in cellular biology. Here, we report the formation process and structural features of the cytoplasmic factories of the large dsDNA virus Paramecium bursaria chlorella virus 1 (PBCV-1). By combining diverse imaging techniques, including scanning transmission electron microscopy tomography and focused ion beam technologies, we show that the architecture and mode of formation of PBCV-1 factories are significantly different from those generated by their evolutionary relatives Vaccinia and Mimivirus. Specifically, PBCV-1 factories consist of a network of single membrane bilayers acting as capsid templates in the central region, and viral genomes spread throughout the host cytoplasm but excluded from the membrane-containing sites. In sharp contrast, factories generated by Mimivirus have viral genomes in their core, with membrane biogenesis region located at their periphery. Yet, all viral factories appear to share structural features that are essential for their function. In addition, our studies support the notion that PBCV-1 infection, which was recently reported to result in significant pathological outcomes in humans and mice, proceeds through a bacteriophage-like infection pathway. PMID:26248343

  6. Maintenance of algal endosymbionts in Paramecium bursaria: a simple model based on population dynamics.

    PubMed

    Iwai, Sosuke; Fujiwara, Kenji; Tamura, Takuro

    2016-09-01

    Algal endosymbiosis is widely distributed in eukaryotes including many protists and metazoans, and plays important roles in aquatic ecosystems, combining phagotrophy and phototrophy. To maintain a stable symbiotic relationship, endosymbiont population size in the host must be properly regulated and maintained at a constant level; however, the mechanisms underlying the maintenance of algal endosymbionts are still largely unknown. Here we investigate the population dynamics of the unicellular ciliate Paramecium bursaria and its Chlorella-like algal endosymbiont under various experimental conditions in a simple culture system. Our results suggest that endosymbiont population size in P. bursaria was not regulated by active processes such as cell division coupling between the two organisms, or partitioning of the endosymbionts at host cell division. Regardless, endosymbiont population size was eventually adjusted to a nearly constant level once cells were grown with light and nutrients. To explain this apparent regulation of population size, we propose a simple mechanism based on the different growth properties (specifically the nutrient requirements) of the two organisms, and based from this develop a mathematical model to describe the population dynamics of host and endosymbiont. The proposed mechanism and model may provide a basis for understanding the maintenance of algal endosymbionts. PMID:26625979

  7. The Evolutionary Relationships between Endosymbiotic Green Algae of Paramecium bursaria Syngens Originating from Different Geographical Locations.

    PubMed

    Zagata, Patrycja; Greczek-Stachura, Magdalena; Tarcz, Sebastian; Rautian, Maria

    2016-01-01

    Paramecium bursaria (Ehrenberg 1831), a freshwater ciliate, typically harbors hundreds of green algal symbionts inside the cell. The aim of present study was the molecular identification of newly analyzed P. bursaria symbionts. The second aspect of the present survey was testing a hypothesis whether endosymbionts prefer the specified syngen of the host, and the specified geographical distribution. Ten strains of endosymbionts isolated from strains of P. bursaria originating from different geographical locations were studied. We analyzed for the first time, both the fragment of plastid genome containing 3'rpl36-5' infA genes and a fragment of a nuclear gene encoding large subunit ribosomal RNA (LSU rDNA). The analysis of the LSU rDNA sequences showed the existence of 3 haplotypes and the haplotype diversity of 0.733, and 8 haplotypes for the 3'rpl36-5' infA gene fragment and haplotype diversity of 0.956. The endosymbionts isolated from P. bursaria strains were identified as Chlorella vulgaris, Ch. variabilis and Micractinium conductrix. There was no correlation between the syngen of P. bursaria and the species of endosymbiont. PMID:27172712

  8. A Ca sup 2+ influx associated with exocytosis is specifically abolished in a Paramecium exocytotic mutant

    SciTech Connect

    Kerboeuf, D.; Cohen, J. )

    1990-12-01

    A Paramecium possesses secretory organelles called trichocysts which are docked beneath the plasma membrane awaiting an external stimulus that triggers their exocytosis. Membrane fusion is the sole event provoked by the stimulation and can therefore be studied per se. Using 3 microM aminoethyl dextran as a vital secretagogue, we analyzed the movements of calcium (Ca{sup 2+}) during the discharge of trichocysts. We showed that (a) external Ca{sup 2+}, at least at 3 X 10(-7) M, is necessary for AED to induce exocytosis; (b) a dramatic and transient influx of Ca{sup 2+} as measured from {sup 45}Ca uptake is induced by AED; (c) this influx is independent of the well-characterized voltage-operated Ca{sup 2+} channels of the ciliary membranes since it persists in a mutant devoid of these channels; and (d) this influx is specifically abolished in one of the mutants unable to undergo exocytosis, nd12. We propose that the Ca{sup 2+} influx induced by AED reflects an increase in membrane permeability through the opening of novel Ca{sup 2+} channel or the activation of other Ca{sup 2+} transport mechanism in the plasma membrane. The resulting rise in cytosolic Ca{sup 2+} concentration would in turn induce membrane fusion. The mutation nd12 would affect a gene product involved in the control of plasma membrane permeability to Ca{sup 2+}, specifically related to membrane fusion.

  9. Selection of the germinal micronucleus in Paramecium caudatum: nuclear division and nuclear death.

    PubMed

    Taka, Noriko; Kurokawa, Koya; Araki, Takako; Mikami, Kazuyuki

    2006-01-01

    Each cell of Paramecium caudatum has a germinal micronucleus. When a bi-micronucleate state was created artificially by micronuclear transplantation, both micronuclei divided for at least 2 cell cycles after nuclear transplantation. However, this bi-micronucleate state was unstable and reduced to a uni-micronucleate state after several fissions. Although the number of micronuclei was usually 1 during the vegetative phase, 4 presumptive micronuclei differentiated after conjugation. At the first post-conjugational fission, only 1 of the 4 micronuclei divided, indicating that there is tight regulation of micronuclear number in exconjugants. Micronuclei that did not divide at the first post-conjugational fission may persist through the first and second post-conjugational cell cycles. The decision to divide appears to be separate from the decision to degenerate, as evidenced by division of a remaining micronucleus upon removal of the dividing micronucleus at the first division. Degeneration of micronuclei in exconjugants differs from that of haploid nuclei after meiosis. Nutritional state affected micronuclear degeneration. Under well-fed conditions, the micronuclei destined to degenerate lost the ability to divide earlier than after starvation treatment, suggesting that micronuclear degeneration is an "apoptotic" phenomenon, probably under the control of the new macronuclei (macronuclear anlagen). PMID:16677339

  10. Silencing-associated and meiosis-specific small RNA pathways in Paramecium tetraurelia.

    PubMed

    Lepère, Gersende; Nowacki, Mariusz; Serrano, Vincent; Gout, Jean-François; Guglielmi, Gérard; Duharcourt, Sandra; Meyer, Eric

    2009-02-01

    Distinct small RNA pathways are involved in the two types of homology-dependent effects described in Paramecium tetraurelia, as shown by a functional analysis of Dicer and Dicer-like genes and by the sequencing of small RNAs. The siRNAs that mediate post-transcriptional gene silencing when cells are fed with double-stranded RNA (dsRNA) were found to comprise two subclasses. DCR1-dependent cleavage of the inducing dsRNA generates approximately 23-nt primary siRNAs from both strands, while a different subclass of approximately 24-nt RNAs, characterized by a short untemplated poly-A tail, is strictly antisense to the targeted mRNA, suggestive of secondary siRNAs that depend on an RNA-dependent RNA polymerase. An entirely distinct pathway is responsible for homology-dependent regulation of developmental genome rearrangements after sexual reproduction. During early meiosis, the DCL2 and DCL3 genes are required for the production of a highly complex population of approximately 25-nt scnRNAs from all types of germline sequences, including both strands of exons, introns, intergenic regions, transposons and Internal Eliminated Sequences. A prominent 5'-UNG signature, and a minor fraction showing the complementary signature at positions 21-23, indicate that scnRNAs are cleaved from dsRNA precursors as duplexes with 2-nt 3' overhangs at both ends, followed by preferential stabilization of the 5'-UNG strand. PMID:19103667

  11. Epiplasmins and epiplasm in paramecium: the building of a submembraneous cytoskeleton.

    PubMed

    Aubusson-Fleury, Anne; Bricheux, Geneviève; Damaj, Raghida; Lemullois, Michel; Coffe, Gérard; Donnadieu, Florence; Koll, France; Viguès, Bernard; Bouchard, Philippe

    2013-07-01

    In ciliates, basal bodies and associated appendages are bound to a submembrane cytoskeleton. In Paramecium, this cytoskeleton takes the form of a thin dense layer, the epiplasm, segmented into regular territories, the units where basal bodies are inserted. Epiplasmins, the main component of the epiplasm, constitute a large family of 51 proteins distributed in 5 phylogenetic groups, each characterized by a specific molecular design. By GFP-tagging, we analyzed their differential localisation and role in epiplasm building and demonstrated that: 1) The epiplasmins display a low turnover, in agreement with the maintenance of an epiplasm layer throughout the cell cycle; 2) Regionalisation of proteins from different groups allows us to define rim, core, ring and basal body epiplasmins in the interphase cell; 3) Their dynamics allows definition of early and late epiplasmins, detected early versus late in the duplication process of the units. Epiplasmins from each group exhibit a specific combination of properties. Core and rim epiplasmins are required to build a unit; ring and basal body epiplasmins seem more dispensable, suggesting that they are not required for basal body docking. We propose a model of epiplasm unit assembly highlighting its implication in structural heredity in agreement with the evolutionary history of epiplasmins. PMID:23837920

  12. Photoreactivation in Paramecium tetraurelia under conditions of various degrees of ozone layer depletion.

    PubMed

    Takahashi, Akihisa; Kumatani, Toshihiro; Usui, Saori; Tsujimura, Ryoko; Seki, Takaharu; Morimoto, Kouichi; Ohnishi, Takeo

    2005-01-01

    Photoreactivation (PR) is an efficient survival mechanism that helps protect cells against the harmful effects of solar-ultraviolet (UV) radiation. The PR mechanism involves photolyase, just one enzyme, and can repair DNA damage, such as cyclobutane-pyrimidine dimers (CPD) induced by near-UV/blue light, a component of sunlight. Although the balance of near-UV/blue light and far-UV light reaching the Earth's surface could be altered by the atmospheric ozone layer's depletion, experiments simulating this environmental change and its possible effects on life have not yet been performed. To quantify the strength of UVB in sunlight reaching the Earth's surface, we measured the number of CPD generated in plasmid DNA after UVB irradiation or exposure to sunlight. To simulate the increase of solar-UV radiation resulting from the ozone layer depletion, Paramecium tetraurelia was exposed to UVB and/or sunlight in clear summer weather. PR recovery after exposure to sunlight was complete at a low dose rate of 0.2 J/m2 x s, but was less efficient when the dose rate was increased by a factor of 2.5 to 0.5 J/m2 x s. It is suggested that solar-UV radiation would not influence the cell growth of P. tetraurelia for the reason of high PR activity even when the ozone concentration was decreased 30% from the present levels. PMID:15839754

  13. The cloning and molecular analysis of pawn-B in Paramecium tetraurelia.

    PubMed Central

    Haynes, W J; Ling, K Y; Preston, R R; Saimi, Y; Kung, C

    2000-01-01

    Pawn mutants of Paramecium tetraurelia lack a depolarization-activated Ca(2+) current and do not swim backward. Using the method of microinjection and sorting a genomic library, we have cloned a DNA fragment that complements pawn-B (pwB/pwB). The minimal complementing fragment is a 798-bp open reading frame (ORF) that restores the Ca(2+) current and the backward swimming when expressed. This ORF contains a 29-bp intron and is transcribed and translated. The translated product has two putative transmembrane domains but no clear matches in current databases. Mutations in the available pwB alleles were found within this ORF. The d4-95 and d4-96 alleles are single base substitutions, while d4-662 (previously pawn-D) harbors a 44-bp insertion that matches an internal eliminated sequence (IES) found in the wild-type germline DNA except for a single C-to-T transition. Northern hybridizations and RT-PCR indicate that d4-662 transcripts are rapidly degraded or not produced. A second 155-bp IES in the wild-type germline ORF excises at two alternative sites spanning three asparagine codons. The pwB ORF appears to be separated from a 5' neighboring ORF by only 36 bp. The close proximity of the two ORFs and the location of the pwB protein as indicated by GFP-fusion constructs are discussed. PMID:10880473

  14. Action of Penicillin G on Endosymbiote Lambda Particles of Paramecium aurelia

    PubMed Central

    Soldo, Anthony T.; Musil, George; Godoy, Gustavo A.

    1970-01-01

    The kinetics of loss from the cytoplasm and changes in ultrastructure of symbiont lambda particles after treatment of axenically cultivated lambda-bearing Paramecium aurelia with penicillin G was investigated. Low concentrations (1 to 2 unit/ml) of the antibiotic caused many particles within the cell to become filamentous; high concentrations (2,000 unit/ml) caused lysis of the particles without noticeably affecting the protozoan. The ED50 value (2 to 3 unit/ml) was within the range of values found to cause lysis of many gram-negative bacteria. Rapidly dividing lambda were more vulnerable to the action of the antibiotic than slowly dividing particles. Nondividing particles were not affected by exposure to the antibiotic. Ultrastructural changes observed in lambda during lysis by penicillin G were consistent with the view that penicillin interferes with the synthesis of a vital component of the cell envelope of the particle, possibly a peptidoglycan similar to that found in the cell walls of bacteria. The deoxyribonucleic acid of lambda was dispersed throughout the particle as electron dense fibers enclosed within electron transparent areas. The cell envelope appeared to consist of at least two morphologically distinguishable layers, an inner layer homologous to the plasma membrane of bacteria and an outer layer homologous to the bacterial cell wall. Lambda may be regarded as a randomly distributed population of bacteria growing and dividing synchronously within the collective cytoplasm of its protozoan host. Images PMID:4099102

  15. [The route of a bacterium Holospora in the cell of Paramecium (Ciliophora, Protista) from phagosome to the nucleus].

    PubMed

    Sabaneeva, E V; Fokin, S I; Kornilova, E S

    2002-01-01

    Problems encountered at the initial stages of stable symbiotic system formation are discussed in the review. The most studied models for interaction between pathogenic bacteria and metazoan cells are compared with a similar system including Paramecium (a ciliatte)--Holospora (a bacterium). Literary and our own data on the infection of P. caudatum with specific endocytobionts inhabiting the nuclear apparatus (H. obtusa in the macronucleus), and H. undulata (in the micronucleus) are analysed with respect to the modern understanding of the intracellular vesicle trafficking. PMID:12561729

  16. Structure of the recombinant Paramecium tetraurelia calmodulin at 1.68 A resolution.

    PubMed

    Ban, C; Ramakrishnan, B; Ling, K Y; Kung, C; Sundaralingam, M

    1994-01-01

    The crystal structure of the recombinant calmodulin from Paramecium tetraurelia (rPCaM, M(r) = 16 700, 148 residues) has been determined at 1.68 A resolution. X-ray intensity data were collected at 263 K using a Siemens-Nicolet area detector and Cu Kalpha radiation from a rotating-anode source. A total of 35 936 observations were processed with XENGEN1.3 and scaled to yield 16 255 unique reflections with R(symm)(I) of 4.1%. The crystals are triclinic, with unit-cell dimensions a = 29.89, b = 53.42, c = 25.35 A, alpha = 93.67, beta = 96.88, gamma = 89.24 degrees, space group P1, with one molecule in the unit cell. The atomic coordinates of the wild-type Paramecium calmodulin (PCaM) studied in our laboratory provided the starting model. Refinement of the structure by X-PLOR and refitting it into omit maps yielded an R value of 0.194 for 15 965 reflections greater than 3sigma(F) in the 6.0-1.68 A resolution range. The final model contained 1165 protein atoms for all of the 148 residues, four Ca(2+) ions, and 172 water molecules. The dumbbell structure has seven alpha-helices including a long 7.8 turn central helix connecting the two terminal domains each containing two EF-hand (helix-loop-helix motif) calcium-binding sites. The loops within each pair of EF-hand motifs in the N- and C-terminal domains are brought into juxtaposition to form a pair of hydrogen-bonded antiparallel beta-sheets which are extended at either ends by water bridges. The four calcium-binding EF-hands are superposable with r.m.s. deviations of 0.31-0.79 A. The best agreement is between site 1 and site 3 and the worst agreement is between site 1 and 4. The largest differences are in the ninth and tenth residues of the calcium-binding loops probably because of their involvement in the mini beta-sheets. The calcium coordination distances vary between 2.04 and 2.69 A, average 2.34 A. The rPCaM and wild-type PCaM have an r.m.s. deviation of 0.36 A for equivalent C(alpha) atoms. The side chains of Lys

  17. Chromosomal and extrachromosomal deoxyribonucleic acid from four bacterial endosymbionts derived from stock 51 of Paramecium tetraurelia.

    PubMed Central

    Dilts, J A

    1977-01-01

    Four variant lines of stock 51 kappa (Paramecium tetraurelia) were screened for the presence of covalently closed circular (CCC) deoxyribonucleic acid (DNA). Stock 51m43 kappa, a nonkiller resistant to 51 killing, contained four classes of CCC DNA: 2.9 X 10(7), 9.7 X 10(7), and 11.8 X 10(7) daltons. The buoyant densities of 51m43 kappa chromosomal and CCC DNA were 1.700 and 1.698 g/cm3, respectively. Stock 51m43 pi, a sensitive nonkiller, contained two CCC species: 0.3 X 10(7) and 4.4 X 10(7) daltons. The buoyant densities of both the chromosomal and CCC DNA were 1.694 to 1.695 g/cm3. Three sizes of CCC DNA were found in 51m1 pi: 0.3 X 10(7), 2.3 X 10(7), and 4.5 X 10(7) daltons. The buoyant densities of both the chromosoaml DNA and the CC DNA were 1.694 to 1.695 g/cm3. It is not known whether 51m1 kappa, a sensitive spinner killer, contains CCC DNA. The buoyant density of its chromosomal DNA was 1.703 g/cm3. Of the four variant lines, only 51m43 kappa appears to be a mutant of 51 kappa. The chromosomal and CCC DNAs of 51m43 kappa have the same buoyant densities as those of 51 kappa; in addition 51m43 kappa contain a CCC molecule the same size as that found in 51 kappa (2.8 x 10(7) daltons). The three other lines are probably bacterial species that are distinct from 51 kappa and which, at one time, were co-inhabitants with 51 kappa in stock 51 paramecia. PMID:838691

  18. Calmodulin localization and its effects on endocytic and phagocytic membrane trafficking in Paramecium multimicronucleatum.

    PubMed

    Fok, Agnes K; Aihara, Marilynn S; Ishida, Masaki; Allen, Richard D

    2008-01-01

    In ciliates, calmodulin (CaM), as in other cells, has multiple functions, such as activation of regulatory enzymes and modulating calcium-dependent cellular processes. By immunogold localization, CaM is concentrated at multiple sites in Paramecium. It is seen scattered over the cytosol, but bound to its matrix, and is concentrated at the pores of the contractile vacuole complexes and with at least three microtubular arrays. It was localized peripheral to the nine-doublet microtubules of the ciliary axonemes. The most striking localization was on the akinetic side only of the cytopharyngeal microtubular ribbons opposite the side where the discoidal vesicles, acidosomes and the 100-nm carrier vesicles bind and move. CaM was also present at the periphery of the postoral microtubular bundles along which the early vacuole moves and was associated with the cytoproct microtubules that guide the spent digestive vacuoles to the cytoproct. It was not found on the membranes of, or in the interior of nuclei, mitochondria, phagosomes, and trichocysts, and was only sparsely scattered over the cytosolic sides of discoidal vesicles, acidosomes, lysosomes, and digestive vacuoles. Together the associations with specific microtubular arrays and the effects of trifluoperazine and calmidazolium indicate that CaM is involved (i) in vesicle transport to the cytopharynx area for vacuole formation and subsequent vacuole acidification, (ii) in early vacuole transport along the postoral fiber, and (iii) in transporting the spent vacuole to the cytoproct. Higher CaM concentrations subjacent to the cell's pellicle and close to the decorated tubules of the contractile vacuole complex may support a role for CaM in ion traffic. PMID:19120793

  19. FORWARD MOVEMENT OF PARAMECIUM AS A FUNCTION OF THE HYDROGEN ION CONCENTRATION.

    PubMed

    Chase, A M; Glaser, O

    1930-07-20

    1. At constant temperatures, and within physiological limits, changes of pH in either direction from the neutral point result in immediate increases in speed of movement of Paramecium. 2. These increases are temporary. In 30 to 45 minutes a minimum of speed is reached. This is followed by a period of recovery lasting about an hour. Finally an equilibrium is found. With inorganic acids (HCl or H(2)SO(4)) the final speed after 3 or 4 hours is that characteristic of prolonged exposure to pH 7.0; on the other hand, 3 or 4 hours after the application of either valeric or carbonic acid, speed is proportional to the [H;prime;] of the external and, probably, of the internal medium. 3. These facts become explicable if we assume that the ionization of an ampholyte superficially localized is essential for the execution of the ciliary stroke. Valeric and carbonic acid, in time, demonstrably penetrate the cell. As a working hypothesis we postulate that internal increase of the [H'] accelerates the rate at which this ampholyte is synthetized; but without actually penetrating the cell, hydrogen or hydroxyl ions in the external medium could also increase the degree to which this ampholyte dissociates. 4. Increased ionization of a fixed quantity of ampholyte and an increase in the rate of its production are in these experiments practically indistinguishable. Hence we assume that immediate and temporary increases of speed resulting from any change of pH, as well as final and permanently higher speed levels manifest only after prolonged exposures to organic acids, involve essentially the same mechanism. PMID:19872552

  20. Biochemical studies of the excitable membrane of paramecium tetraurelia. IX. Antibodies against ciliary membrane proteins.

    PubMed

    Eisenbach, L; Ramanathan, R; Nelson, D L

    1983-11-01

    The excitable ciliary membrane of Paramecium regulates the direction of the ciliary beat, and thereby the swimming behavior of this organism. One approach to the problem of identifying the molecular components of the excitable membrane is to use antibodies as probes of function. We produced rabbit antisera against isolated ciliary membranes and against partially purified immobilization antigens derived from three serotypes (A, B, and H), and used these antisera as reagents to explore the role of specific membrane proteins in the immobilization reaction and in behavior. The immobilization characteristics and serotype cross-reactivities of the antisera were examined. We identified the antigens recognized by these sera using immunodiffusion and immunoprecipitation with 35S-labeled ciliary membranes. The major antigen recognized in homologous combinations of antigen-antiserum is the immobilization antigen (i-antigen), approximately 250,000 mol wt. Several secondary antigens, including a family of polypeptides of 42,000-45,000 mol wt, are common to the membranes of serotypes A, B, and H, and antibodies against these secondary antigens can apparently immobilize cells. This characterization of antiserum specificity has provided the basis for our studies on the effects of the antibodies on electrophysiological properties of cells and electron microscopic localization studies, which are reported in the accompanying paper. We have also used these antibodies to study the mechanism of cell immobilization by antibodies against the i-antigen. Monovalent fragments (Fab) against purified i-antigens bound to, but did not immobilize, living cells. Subsequent addition of goat anti-Fab antibodies caused immediate immobilization, presumably by cross-linking Fab fragments already bound to the surface. We conclude that antigen-antibody interaction per se is not sufficient for immobilization, and that antibody bivalency, which allows antigen cross-linking, is essential. PMID:6415066

  1. Regulation of ciliary reversal in triton-extracted Paramecium by calcium and cyclic adenosine monophosphate.

    PubMed

    Nakaoka, Y; Ooi, H

    1985-08-01

    A Triton-extracted model of Paramecium swims forwards when the Ca2+ concentration in the reactivation medium containing ATP is below 10(-6) M and swims backwards when Ca2+ concentration is above 10(-6) M. We found that cAMP (adenosine 3':5'-cyclic monophosphoric acid) inhibited Ca-induced backward swimming of the model and caused forward swimming even when the [Ca2+] was above 10(-6) M. This effect of cAMP was abolished by an inhibitor of cAMP-dependent protein kinase. In order to study the possible role of phosphorylation in the regulation of ciliary orientation, ATP in the reactivation medium was replaced by an ATP analogue, ARP gamma S (adenosine 5'-O-3-thiotriphosphate), which irreversibly thiophosphorylates proteins. In ATP gamma S medium, the model ceased both swimming and ciliary beating, but the orientation of cilia was dependent on [Ca2+]. At low [Ca2+], cilia were perpendicular to the cell surface and, with increase in [Ca2+], their orientation gradually changed towards the cell anterior. Such a change in ciliary orientation corresponds roughly to the change in the swimming direction observed in ATP medium. The ciliary orientation towards the anterior of the cell in ATP gamma S medium at high [Ca2+] was maintained when [Ca2+] was decreased. In contrast, in ATP medium, the swimming direction was reversibly changed with changes in [Ca2+]. These results suggest that the ciliary orientation is regulated not only by Ca2+ but also by cAMP, probably via protein phosphorylation. PMID:3003129

  2. Identification and functional characterization of an uncharacterized antimicrobial peptide from a ciliate Paramecium caudatum.

    PubMed

    Cui, Pengfei; Dong, Yuan; Li, Zhijian; Zhang, Yubo; Zhang, Shicui

    2016-07-01

    The global ever-growing concerns about multi-drug resistant (MDR) microbes leads to urgent demands for exploration of new antibiotics including antimicrobial peptides (AMPs). Here we demonstrated that a cDNA from Ciliata Paramecium caudatum, designated Pcamp1, coded for a protein with features characteristic of AMPs, which is not homologous to any AMPs currently known. Both the C-terminal 91 amino acid residues of PcAMP1, cPcAMP1, expressed in Escherichia coli and the C-terminal 26 amino acid residues (predicted mature AMP), cPcAMP1/26, synthesized, underwent a coil-to-helix transition in the presence of TFE, SDS or DPC. Functional assays revealed that cPcAMP1 and cPcAMP1/26 were both able to kill Aeromonas hydrophila and Staphylococcus aureus. ELISA showed that cPcAMP1 and cPcAMP1/26 were able to bind to microbe-associated molecular pattern molecules LPS and LTA, which was further corroborated by the observations that cPcAMP1 could deposit onto the bacterial membranes. Importantly, both cPcAMP1 and cPcAMP1/26 were able to induce bacterial membrane permeabilization and depolarization, and to increase intracellular ROS levels. Additionally, cPcAMP1 and cPcAMP1/26 were not cytotoxic to mammalian cells. Taken together, our results show that PcAMP1 is a potential AMP with a membrane selectivity towards bacterial cells, which renders it a promising template for the design of novel peptide antibiotics against MDR microbes. It also shows that use of signal conserved sequence of AMPs can be an effective tool to identify potential AMPs across different animal classes. PMID:26883426

  3. The ts111 Mutation of Paramecium tetraurelia Affects a Member of the Protein Palmitoylation Family.

    PubMed

    Prajer, Małgorzata; Tarcz, Sebastian

    2015-01-01

    The thermosensitive ts111 mutant of Parameciun tetraurelia carries a recessive mutation which causes cell death after 2-8 divisions at the restrictive temperature of 35 degrees C. Expression at 35 degrees C induces disassembly of the infraciliary lattice (ICL). In this study, we found that the ts111 mutation also results in significant abnormalities in the number and structure of contractile vacuole complexes (CVCs) and in their functioning at the restrictive temperature. In order to characterize the ts111 gene, the complementation cloning was performed by microinjection into the macronucleus of an indexed genomic DNA library. The mutation was complemented by a sequence of 852 bp, which differed from the mutant sequence by a single nucleotide substitution. The deduced protein sequence is 284 amino acids long. It contains a domain referred to as the DHHC domain, associated with 2 trans-membrane helices. The DHHC proteins belong to the Palmitoyl-Acyl Transferases (PATs) protein family, which is implicated in the protein palmitoylation process playing the role in protein addressing. The ts111 mutation induces the amino acid change, localized before the first membrane helix. Transformation of ts111 mutant cells with the TS111-GFP gene fusion showed the expected reparation restoring thermoresistance and also demonstrated a localization of the protein in contractile vacuoles, but not in the ICL. The entire gene silencing in wild type cells at restrictive temperature caused the same effect as the expression of a point mutation in ts111 mutant. The authors propose the following hypotheses: (i) function of CVCs at the restrictive temperature depends in Paramecium on the TS111 protein--a member of the PAT family, and the primary effect of the termosensitive ts111 mutation are morphological abnormalities and dysfunction of CVCs, (ii) disassembly of the ICL is a secondary effect of the ts111 mutation, which results from disturbed regulation of the intracellular concentration

  4. Three-dimensional reconstruction of paramecium primaurelia oral apparatus through confocal laser scanning optical microscopy

    NASA Astrophysics Data System (ADS)

    Beltrame, Francesco; Ramoino, Paola; Fato, Marco; Delmonte Corrado, Maria U.; Marcenaro, Giampiero; Crippa Franceschi, Tina

    1992-06-01

    Studies on the complementary mating types of Paramecium primaurelia (Protozoa, Ciliates) have shown that cell lines which differ from each other in mating type expression are characterized by different cell contents, organization, and physiology. Referring to these differences and to the differential rates of food vacuole formation, oral apparatuses of the two mating type cells are assumed to possibly differ from each other in some traits, such as, for instance, in their lengths. In our work, the highly organized oral structures are analyzed by means of a laser scanning confocal optical microscope (CLSM), which provides their 3-D visualization and measurement. The extraction of the 3-D intrinsic information related to the biological objects under investigation can be in turn related to their functional state, according to the classical paradigm of structure to function relationships identification. In our experiments, we acquired different data sets. These are optical slices of the biological sample under investigation, acquired in a confocal situation, through epi-illumination, in reflection, and, for comparison with conventional microscopy, 2-D images acquired via a standard TV camera coupled to the microscope itself. Our CLSM system is equipped with a laser beam at 488 and 514 nm and the data have been acquired with various steps of optical slicing, ranging from .04 to .25 micrometers. The volumes obtained by piling-up the slices are rendered through different techniques, some of them directly implemented on the workstation controlling the CLSM system, some of them on a SUN SPARC station 1, where the original data were transferred via an Ethernet link. In this last instance, original software has been developed for the visualization and animation of the 3-D structures, running under UNIX and X-Window, according to a ray-tracing algorithm.

  5. Characterization of multigene families in the micronuclear genome of Paramecium tetraurelia reveals a germline specific sequence in an intron of a centrin gene.

    PubMed Central

    Vayssié, L; Sperling, L; Madeddu, L

    1997-01-01

    In Paramecium, as in other ciliates, the transcriptionally active macronucleus is derived from the germline micronucleus by programmed DNA rearrangements, which include the precise excision of thousands of germline-specific sequences (internal eliminated sequences, IESs). We report the characterization of micronuclear versions of genes encoding Paramecium secretory granule proteins (trichocyst matrix proteins, TMPs) and Paramecium centrins. TMP and centrin multigene families, previously studied in the macronuclear genome, consist of genes that are co-expressed to provide mixtures of related polypeptides that co-assemble to form respectively the crystalline trichocyst matrix and the infraciliary lattice, a contractile cytoskeletal network. We present evidence that TMP and centrin genes identified in the macronucleus are also present in the micronucleus, ruling out the possibility that these novel multigene families are generated by somatic rearrangements during macronuclear development. No IESs were found in TMP genes, however, four IESs in or near germline centrin genes were characterized. The only intragenic IES is 75 bp in size, interrupts a 29 bp intron and is absent from at least one other closely related centrin gene. This is the first report of an IES in an intron in Paramecium. PMID:9023115

  6. Deletion endpoint allele-specificity in the developmentally regulated elimination of an internal sequence (IES) in Paramecium.

    PubMed

    Dubrana, K; Le Mouël, A; Amar, L

    1997-06-15

    Ciliated protozoa undergo thousands of site-specific DNA deletion events during the programmed development of micronuclear genomes to macronuclear genomes. Two deletion elements, W1 and W2, were identified in the Paramecium primaurelia wild-type 156 strain. Here, we report the characterization of both elements in wild-type strain 168 and show that they display variant deletion patterns when compared with those of strain 156. The W1 ( 168 ) element is defective for deletion. The W2 ( 168 ) element is excised utilizing two alternative boundaries on one side, both are different from the boundary utilized to excise the W2156 element. By crossing the 156 and 168 strains, we demonstrate that the definition of all deletion endpoints are each controlled by cis -acting determinant(s) rather than by strain-specific trans-acting factor(s). Sequence comparison of all deleted DNA segments indicates that the 5'-TA-3'terminal sequence is strictly required at their ends. Furthermore the identity of the first eight base pairs of these ends to a previously established consensus sequence correlates with the frequency of the corresponding deletion events. Our data implies the existence of an adaptive convergent evolution of these Paramecium deleted DNA segment end sequences. PMID:9171098

  7. Identification, localization, and functional implications of the microdomain-forming stomatin family in the ciliated protozoan Paramecium tetraurelia.

    PubMed

    Reuter, Alexander T; Stuermer, Claudia A O; Plattner, Helmut

    2013-04-01

    The SPFH protein superfamily is assumed to occur universally in eukaryotes, but information from protozoa is scarce. In the Paramecium genome, we found only Stomatins, 20 paralogs grouped in 8 families, STO1 to STO8. According to cDNA analysis, all are expressed, and molecular modeling shows the typical SPFH domain structure for all subgroups. For further analysis we used family-specific sequences for fluorescence and immunogold labeling, gene silencing, and functional tests. With all family members tested, we found a patchy localization at/near the cell surface and on vesicles. The Sto1p and Sto4p families are also associated with the contractile vacuole complex. Sto4p also makes puncta on some food vacuoles and is abundant on vesicles recycling from the release site of spent food vacuoles to the site of nascent food vacuole formation. Silencing of the STO1 family reduces mechanosensitivity (ciliary reversal upon touching an obstacle), thus suggesting relevance for positioning of mechanosensitive channels in the plasmalemma. Silencing of STO4 members increases pulsation frequency of the contractile vacuole complex and reduces phagocytotic activity of Paramecium cells. In summary, Sto1p and Sto4p members seem to be involved in positioning specific superficial and intracellular microdomain-based membrane components whose functions may depend on mechanosensation (extracellular stimuli and internal osmotic pressure). PMID:23376944

  8. Identification, Localization, and Functional Implications of the Microdomain-Forming Stomatin Family in the Ciliated Protozoan Paramecium tetraurelia

    PubMed Central

    Stuermer, Claudia A. O.; Plattner, Helmut

    2013-01-01

    The SPFH protein superfamily is assumed to occur universally in eukaryotes, but information from protozoa is scarce. In the Paramecium genome, we found only Stomatins, 20 paralogs grouped in 8 families, STO1 to STO8. According to cDNA analysis, all are expressed, and molecular modeling shows the typical SPFH domain structure for all subgroups. For further analysis we used family-specific sequences for fluorescence and immunogold labeling, gene silencing, and functional tests. With all family members tested, we found a patchy localization at/near the cell surface and on vesicles. The Sto1p and Sto4p families are also associated with the contractile vacuole complex. Sto4p also makes puncta on some food vacuoles and is abundant on vesicles recycling from the release site of spent food vacuoles to the site of nascent food vacuole formation. Silencing of the STO1 family reduces mechanosensitivity (ciliary reversal upon touching an obstacle), thus suggesting relevance for positioning of mechanosensitive channels in the plasmalemma. Silencing of STO4 members increases pulsation frequency of the contractile vacuole complex and reduces phagocytotic activity of Paramecium cells. In summary, Sto1p and Sto4p members seem to be involved in positioning specific superficial and intracellular microdomain-based membrane components whose functions may depend on mechanosensation (extracellular stimuli and internal osmotic pressure). PMID:23376944

  9. Primary and secondary siRNA synthesis triggered by RNAs from food bacteria in the ciliate Paramecium tetraurelia.

    PubMed

    Carradec, Quentin; Götz, Ulrike; Arnaiz, Olivier; Pouch, Juliette; Simon, Martin; Meyer, Eric; Marker, Simone

    2015-02-18

    In various organisms, an efficient RNAi response can be triggered by feeding cells with bacteria producing double-stranded RNA (dsRNA) against an endogenous gene. However, the detailed mechanisms and natural functions of this pathway are not well understood in most cases. Here, we studied siRNA biogenesis from exogenous RNA and its genetic overlap with endogenous RNAi in the ciliate Paramecium tetraurelia by high-throughput sequencing. Using wild-type and mutant strains deficient for dsRNA feeding we found that high levels of primary siRNAs of both strands are processed from the ingested dsRNA trigger by the Dicer Dcr1, the RNA-dependent RNA polymerases Rdr1 and Rdr2 and other factors. We further show that this induces the synthesis of secondary siRNAs spreading along the entire endogenous mRNA, demonstrating the occurrence of both 3'-to-5' and 5'-to-3' transitivity for the first time in the SAR clade of eukaryotes (Stramenopiles, Alveolates, Rhizaria). Secondary siRNAs depend on Rdr2 and show a strong antisense bias; they are produced at much lower levels than primary siRNAs and hardly contribute to RNAi efficiency. We further provide evidence that the Paramecium RNAi machinery also processes single-stranded RNAs from its bacterial food, broadening the possible natural functions of exogenously induced RNAi in this organism. PMID:25593325

  10. Synchronous induction of detachment and reattachment of symbiotic Chlorella spp. from the cell cortex of the host Paramecium bursaria.

    PubMed

    Kodama, Yuuki; Fujishima, Masahiro

    2013-09-01

    Paramecium bursaria harbor several hundred symbiotic Chlorella spp. Each alga is enclosed in a perialgal vacuole membrane, which can attach to the host cell cortex. How the perialgal vacuole attaches beneath the host cell cortex remains unknown. High-speed centrifugation (> 1000×g) for 1min induces rapid detachment of the algae from the host cell cortex and concentrates the algae to the posterior half of the host cell. Simultaneously, most of the host acidosomes and lysosomes accumulate in the anterior half of the host cell. Both the detached algae and the dislocated acidic vesicles recover their original positions by host cyclosis within 10min after centrifugation. These recoveries were inhibited if the host cytoplasmic streaming was arrested by nocodazole. Endosymbiotic algae during the early reinfection process also show the capability of desorption after centrifugation. These results demonstrate that adhesion of the perialgal vacuole beneath the host cell cortex is repeatedly inducible, and that host cytoplasmic streaming facilitates recovery of the algal attachment. This study is the first report to illuminate the mechanism of the induction to desorb for symbiotic algae and acidic vesicles, and will contribute to the understanding of the mechanism of algal and organelle arrangements in Paramecium. PMID:23912150

  11. Parafusin, an exocytic-sensitive phosphoprotein, is the primary acceptor for the glucosylphosphotransferase in Paramecium tetraurelia and rat liver.

    PubMed

    Satir, B H; Srisomsap, C; Reichman, M; Marchase, R B

    1990-09-01

    Parafusin, the major protein in Paramecium tetraurelia to undergo dephosphorylation in response to secretory stimuli, appears to be the primary acceptor for the glucosylphosphotransferase in this species based on five independent criteria: identical molecular size of 63 kD; identical isoelectric points in the phosphorylated state of pH 5.8 and 6.2; identical behavior in reverse-phase chromatography; immunological cross-reactivity with an affinity-purified anti-parafusin antibody; the presence of a phosphorylated sugar after acid hydrolysis. It appears likely that the dephosphorylation observed with secretion reflects the removal of alpha Glc-1-P from parafusin's oligosaccharides and is consistent, therefore, with a regulatory role for this cytoplasmic glycosylation event. The glucosylphosphotransferase acceptor in rat liver is also immunoprecipitated by the anti-parafusin antibody and is very similar in physical characteristics to the paramecium protein. This conservation suggests a role for parafusin in mammalian exocytosis as well, at a step common to both the regulated and constitutive secretory pathways. PMID:2167899

  12. An electrophysiological study of the regulation of ciliary beating frequency in Paramecium.

    PubMed

    Brehm, P; Eckert, R

    1978-10-01

    1. The role of the surface membrane in the control of ciliary beat frequency in Paramecium was examined by intracellular electrophysiological techniques and pressure injection of Ca2+ and EGTA. Experiments were done on wild type P. caudatum and on both the wild type and a pawn mutant of P. tetraurelia. 2. The increased frequency of beating that accompanies reversal of power stroke orientation in response to depolarization in the wild type fails to occur during depolarization in the mutant pawn, which also fails to exhibit ciliary reversal upon depolarization. 3. Injection of moderate amounts of EGTA blocked the frequency increase without interfering with reversal of the beat in response to depolarization of the wild type. Larger injection of EGTA also prevented reversed beating. 4. The beat frequency in the normal (forward-swimming) direction increased during hyperpolarization in pawn. The hyperpolarizing frequency-voltage relations were quantitatively similar to those of the wild type. 5. Injection of EGTA to a final concentration of 10 mM into wild type cells neither modified the resting frequency nor blocked the frequency increase which normally accompanies hyperpolarization. 6. Transient ciliary reversal in both pawn and wild type produced by injection of Ca2+ could be terminated by the passage of inward current. The power stroke returned to the normal forward-swimming direction and the ciliary beating frequency increased. Upon termination of the inward current the cilia of Ca2+-injected cells again beat in reverse for many seconds. 7. The results support previous reports that increased frequency of beating and ciliary reversal seen in response to depolarization both require the entry of Ca2+ through the surface membrane. On the other hand, the results indicate that frequency increase with hyperpolarization is independent of an altered rate of Ca2+ entry. 8. Increased frequency during hyperpolarization appears to be related more closely to electrotonic membrane

  13. Tolerance of ciliated protozoan Paramecium bursaria (Protozoa, Ciliophora) to ammonia and nitrites

    NASA Astrophysics Data System (ADS)

    Xu, Henglong; Song, Weibo; Lu, Lu; Alan, Warren

    2005-09-01

    The tolerance to ammonia and nitrites in freshwater ciliate Paramecium bursaria was measured in a conventional open system. The ciliate was exposed to different concentrations of ammonia and nitrites for 2h and 12h in order to determine the lethal concentrations. Linear regression analysis revealed that the 2h-LC50 value for ammonia was 95.94 mg/L and for nitrite 27.35 mg/L using probit scale method (with 95% confidence intervals). There was a linear correlation between the mortality probit scale and logarithmic concentration of ammonia which fit by a regression equation y=7.32 x 9.51 ( R 2=0.98; y, mortality probit scale; x, logarithmic concentration of ammonia), by which 2 h-LC50 value for ammonia was found to be 95.50 mg/L. A linear correlation between mortality probit scales and logarithmic concentration of nitrite is also followed the regression equation y=2.86 x+0.89 ( R 2=0.95; y, mortality probit scale; x, logarithmic concentration of nitrite). The regression analysis of toxicity curves showed that the linear correlation between exposed time of ammonia-N LC50 value and ammonia-N LC50 value followed the regression equation y=2 862.85 e -0.08 x ( R 2=0.95; y, duration of exposure to LC50 value; x, LC50 value), and that between exposed time of nitrite-N LC50 value and nitrite-N LC50 value followed the regression equation y=127.15 e -0.13 x ( R 2=0.91; y, exposed time of LC50 value; x, LC50 value). The results demonstrate that the tolerance to ammonia in P. bursaria is considerably higher than that of the larvae or juveniles of some metozoa, e.g. cultured prawns and oysters. In addition, ciliates, as bacterial predators, are likely to play a positive role in maintaining and improving water quality in aquatic environments with high-level ammonium, such as sewage treatment systems.

  14. An electrophysiological study of the regulation of ciliary beating frequency in Paramecium.

    PubMed Central

    Brehm, P; Eckert, R

    1978-01-01

    1. The role of the surface membrane in the control of ciliary beat frequency in Paramecium was examined by intracellular electrophysiological techniques and pressure injection of Ca2+ and EGTA. Experiments were done on wild type P. caudatum and on both the wild type and a pawn mutant of P. tetraurelia. 2. The increased frequency of beating that accompanies reversal of power stroke orientation in response to depolarization in the wild type fails to occur during depolarization in the mutant pawn, which also fails to exhibit ciliary reversal upon depolarization. 3. Injection of moderate amounts of EGTA blocked the frequency increase without interfering with reversal of the beat in response to depolarization of the wild type. Larger injection of EGTA also prevented reversed beating. 4. The beat frequency in the normal (forward-swimming) direction increased during hyperpolarization in pawn. The hyperpolarizing frequency-voltage relations were quantitatively similar to those of the wild type. 5. Injection of EGTA to a final concentration of 10 mM into wild type cells neither modified the resting frequency nor blocked the frequency increase which normally accompanies hyperpolarization. 6. Transient ciliary reversal in both pawn and wild type produced by injection of Ca2+ could be terminated by the passage of inward current. The power stroke returned to the normal forward-swimming direction and the ciliary beating frequency increased. Upon termination of the inward current the cilia of Ca2+-injected cells again beat in reverse for many seconds. 7. The results support previous reports that increased frequency of beating and ciliary reversal seen in response to depolarization both require the entry of Ca2+ through the surface membrane. On the other hand, the results indicate that frequency increase with hyperpolarization is independent of an altered rate of Ca2+ entry. 8. Increased frequency during hyperpolarization appears to be related more closely to electrotonic membrane

  15. X-ray microanalysis in cryosections of natively frozen Paramecium caudatum with regard to ion distribution in ciliates

    SciTech Connect

    Schmitz, M.; Meyer, R.; Zierold, K.

    1985-01-01

    Cells of Paramecium caudatum were shock-frozen without pretreatment for cryoultramicrotomy and freeze-dried for subsequent X-ray microanalysis. Na, Mg, P, S, Cl, K, and Ca were detected in different amounts in several subcellular compartments. In particular, calcium was localized below the cell surface (pellicle). Trichocysts were found to contain significant amounts of Na in their base but not in the tip. Na, Mg, P, S, Cl, K, Ca were found in electron dense deposits within the lumen of the contractile vacuole. A small K concentration was found in the cytoplasm and in the mitochondria. X-ray microanalysis of the element distribution in different subcellular compartments provides information for the understanding of cellular functions such as exocytosis, locomotion, and ion regulation.

  16. Three Group-I introns in 18S rDNA of Endosymbiotic Algae of Paramecium bursaria from Japan

    NASA Astrophysics Data System (ADS)

    Hoshina, Ryo; Kamako, Shin-ichiro; Imamura, Nobutaka

    2004-08-01

    In the nuclear encoded small subunit ribosomal DNA (18S rDNA) of symbiotic alga of Paramecium bursaria (F36 collected in Japan) possesses three intron-like insertions (Hoshina et al., unpubl. data, 2003). The present study confirmed these exact lengths and insertion sites by reverse transcription-PCR. Two of them were inserted at Escherichia coli 16S rRNA genic position 943 and 1512 that are frequent intron insertion positions, but another insertion position (nearly 1370) was the first finding. Their secondary structures suggested they belong to Group-I intron; one belongs to subgroup IE, others belong to subgroup IC1. Similarity search indicated these introns are ancestral ones.

  17. Molecular Identification of Paramecium bursaria Syngens and Studies on Geographic Distribution using Mitochondrial Cytochrome C Oxidase Subunit I (COI).

    PubMed

    Zagata, Patrycja; Greczek-Stachura, Magdalena; Tarcz, Sebastian; Rautian, Maria

    2015-01-01

    Paramecium bursaria is composed of five syngens that are morphologically indistinguishable but sexually isolated. The aim of the present study was to confirm by molecular methods (analyses of mitochondrial COI) the identification of P. bursaria syngens originating from different geographical locations. Phylograms constructed using both the neighbor-joining and maximum-likelihood methods based on a comparison of 34 sequences of P. bursaria strains and P. multimicronucleatum, P. caudatum and P.calkinsi strains used as outgroups revealed five clusters which correspond to results obtained previously by mating reaction. Our analysis shows the existence of 24 haplotypes for the COI gene sequence in the studied strains. The interspecies haplotype diversity was Hd = 0.967. We confirmed genetic differentiation between strains of P. bursaria and the occurrence of a correlation between geographical distribution and the correspondent syngen. PMID:26103689

  18. Protein substrates for cGMP-dependent protein phosphorylation in cilia of wild type and atalanta mutants of Paramecium.

    PubMed

    Ann, K S; Nelson, D L

    1995-01-01

    In the ciliated protozoan Paramecium, swimming direction is regulated by voltage-gated Ca2+ channels in the ciliary membrane. In response to depolarizing stimuli, intraciliary Ca2+ rises, triggering reversal of the ciliary power stroke and backward swimming. One class of Ca(2+)-unresponsive behavioral mutants of Paramecium, atalanta mutants, cannot swim backward even though they have functional Ca2+ channels in their ciliary membrane. Several atalanta mutants were characterized with regard to several Ca(2+)-dependent activities, but no significant difference between wild type and the mutants was detected. However, one allelic group, atalanta A (initially characterized by Hinrichsen and Kung [1984: Genet. Res. Camb. 43:11-20]), showed a helical swimming path of opposite handedness from that of wild-type cells when detergent-permeabilized cells ("models") were reactivated with MgATP. When cGMP-dependent protein kinase purified from wild-type cells was added to atalanta A models, the handedness of the swimming path was reversed. Cyclic GMP stimulated in vitro phosphorylation of several proteins in isolated cilia, and the pattern of phosphoproteins was very similar for wild type and atalanta mutants, with one exception: a protein of 59 kDa was phosphorylated much less in the mutant ata A. When ciliary proteins were separated by gel electrophoresis and then phosphorylated "on blot" by purified cGMP-dependent protein kinase, phosphoprotein patterns were similar in wild type and ata mutants except that a 48 kDa protein (p48) from ata A3 was more heavily phosphorylated. This difference in p48 phosphorylation was also observed with cGMP-dependent protein kinase purified from ata A3 mutant cells.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7796456

  19. The Role of Macronuclear DNA Sequences in the Permanent Rescue of a Non-Mendelian Mutation in Paramecium Tetraurelia

    PubMed Central

    You, Y.; Scott, J.; Forney, J.

    1994-01-01

    The Paramecium tetraurelia mutant called d48 has a complete copy of the A surface protein gene in its micronuclei, but lacks the A gene in the macronucleus. Previous experiments have shown that microinjection of a plasmid containing the entire A gene or a large portion of the gene into the macronucleus of d48 rescued the cell line after formation of a new macronucleus (autogamy). Here we show that several different regions of the A gene can rescue d48, but 100% of the activity cannot be localized to a single, defined region. Inversion of a sequence contained within an A gene plasmid had no measurable effect on rescue efficiency and co-injection of two different plasmids results in enhancement of rescue activity despite the non-contiguous form of the DNA sequences. Both these results suggest that no specific product (RNA or protein) with defined end points is made from the rescuing fragment. A unique restriction site was created in the A gene and used to demonstrate that the injected DNA does not serve as a direct template for the synthesis of the new macronuclear DNA. Models to explain the action of the injected DNA are discussed. PMID:8013908

  20. Augmented ciliary reorientation response and cAMP-dependent protein phosphorylation induced by glycerol in triton-extracted Paramecium.

    PubMed

    Noguchi, Munenori; Kitani, Takayuki; Ogawa, Tokushige; Inoue, Hiroshi; Kamachi, Hiroyuki

    2005-01-01

    In the presence of 30% glycerol, the cilia of a permeabilized cell model from Paramecium exhibit dynamic orientation changes while displaying only a restricted cyclic beating with a very small amplitude. The direction of cilia under these conditions corresponds to the direction of the effective power stroke of cilia beating in the absence of glycerol, i.e., pointing posteriorly in the absence of Ca2+ and anteriorly at > 10(-6) M Ca2+. Ciliary reorientation toward the posterior in response to the removal of Ca2+ is particularly conspicuous; all the cilia become predominantly pointing to the posterior end all through their beating phases. Previous studies suggested that the effect of glycerol is caused through modification of cAMP-dependent protein phosphorylation. To determine whether glycerol in fact affects ciliary reorientation through changes in protein phosphorylation, here we examined protein phosphorylation in the axonemes. Glycerol stimulated cAMP-induced phosphorylation of 29-kDa and 65-kDa proteins. The stimulation of phosphorylation was found to be partly due to the inhibition of endogenous phosphodiesterase (PDE), and partly due to the inhibition of the dephosphorylation of the 29-kDa and 65-kDa phosphoproteins within the axoneme. Thus glycerol appears to cause predominant posterior orientation of cilia by stimulating cAMP-dependent phosphorylation on those proteins. In addition, glycerol appears to inhibit ciliary beating through inhibition of dynein ATPase. PMID:15684582

  1. Paramecium tetraurelia growth stimulation under low-level chronic irradiation: investigations on a possible mechanism. [/sup 60/Co

    SciTech Connect

    Croute, F.; Soleilhavoup, J.P.; Vidal, S.; Dupouy, D.; Planel, H.

    1982-12-01

    Experiments were carried out to demonstrate the effects of low-level chronic irradiation on Paramecium tetraurelia proliferation. Biological effects were strongly dependent on the bacterial density of culture medium and more exactly on the catalase content of the medium. Significant growth stimulation was found under /sup 60/Co chronic irradiation at a dose rate of 2 rad/year when paramecia were grown in a medium containing a high bacterial concentration (2.5 x 10/sup 2/ cells/m) or supplemented with catalase (300 U/ml). In a medium with a low bacterial density (1 x 10/sup 6/ cell/ml) or supplemented with a catalase activity inhibitor, growth simulation was preceded by a transitory inhibiting effect which could be correlated with extracellularly radioproduced H/sub 2/O/sub 2/. H/sub 2/O/sub 2/ addition appeared to be able to simulate the biological effects of chronic irradiation. A possible mechanism is discussed.We proposed that the stimulating effects were the result of intracellular enzymatic scavenging of radioproduced H/sub 2/O/sub 2/.

  2. New Stands of Species of the Paramecium aurelia Complex; is the Occurrence of Particular Species Limited by Temperature Barriers?

    PubMed

    Przyboś, Ewa; Prajer, Małgorzata

    2015-01-01

    The occurrence of ciliates, especially the Paramecium aurelia complex, has not yet been studied in many parts of the world, or sampling was done only occasionally. Generally, the southern hemisphere still awaits investigation. In North America only the USA was studied in greater detail; the majority of species of the complex were there recorded. In Asia, more frequent sampling was performed only in Japan and Asiatic Russia. Europe was studied more carefully, however, a different number of habitats was studied in particular zones of Europe, the least in the southern zone. New stands of P. tetraurelia , P. sexaurelia, P. octaurelia, and P. novaurelia were revealed as a result of the present investigations carried out in Africa (Mozambique--P. tetraurelia, P. sexaurelia), Asia (Indonesia--P. sexaurelia), borderland of Asia and Europe (Georgia--P. octaurelia), and Europe (Macedonia--P. tetraurelia and Romania--P. novaurelia). Are climatic zones the main factor limiting the occurrence of species of the P. aurelia complex? Analysis of data on the distribution of the P. aurelia species complex in warm "tropical" zones on different continents may suggest such preferences for some species, including P. sexaurelia, P. octaurelia, P. tredecaurelia, P. quadecaurelia. The first two of these species were recorded herein in warm or "tropical" zone. PMID:26462333

  3. Glycosylinositol-phosphoceramide in the free-living protozoan Paramecium primaurelia: modification of core glycans by mannosyl phosphate.

    PubMed Central

    Azzouz, N; Striepen, B; Gerold, P; Capdeville, Y; Schwarz, R T

    1995-01-01

    Glycolipids synthesized in a cell-free system prepared from the free-living protozoan Paramecium primaurelia and labelled with [3H]mannose and [3H]glucosamine using GDP-[3H]mannose and UDP-[3H]N-acetyl glucosamine, respectively, were identified and structurally characterized as glycosylinositol-phosphoceramides (GIP-ceramides). The ceramide-based lipid was also found in the GIP membrane anchor of the G surface antigen of P.primaurelia, strain 156. Using a combination of in vitro labelling with GDP-[3H]mannose and in vivo labelling with 33P, we found that the core glycans of the P.primaurelia GIP-ceramides were substituted with an acid-labile modification identified as mannosyl phosphate. The modification of the glycosylinositol-phospholipid core glycan by mannosyl phosphate has not been described to date in other organisms. The biosynthesis of GIP-ceramide intermediates in P.primaurelia was studied by a pulse-chase analysis. Their structural characterization is reported. We propose the following structure for the putative GIP-ceramide membrane anchor precursor of P.primaurelia surface proteins: ethanolamine phosphate-6Man-alpha 1-2Man-alpha 1-6Man-(mannosyl phosphate)-alpha 1-4glucosamine-inositol-phosphoceramide. PMID:7556085

  4. A virus-encoded potassium ion channel is a structural protein in the chlorovirus Paramecium bursaria chlorella virus 1 virion.

    PubMed

    Romani, Giulia; Piotrowski, Adrianna; Hillmer, Stefan; Gurnon, James; Van Etten, James L; Moroni, Anna; Thiel, Gerhard; Hertel, Brigitte

    2013-11-01

    Most chloroviruses encode small K(+) channels, which are functional in electrophysiological assays. The experimental finding that initial steps in viral infection exhibit the same sensitivity to channel inhibitors as the viral K(+) channels has led to the hypothesis that the channels are structural proteins located in the internal membrane of the virus particles. This hypothesis was questioned recently because proteomic studies failed to detect the channel protein in virions of the prototype chlorovirus Paramecium bursaria chlorella virus 1 (PBCV-1). Here, we used a mAb raised against the functional K(+) channel from chlorovirus MA-1D to search for the viral K(+) channel in the virus particle. The results showed that the antibody was specific and bound to the tetrameric channel on the extracellular side. The antibody reacted in a virus-specific manner with protein extracts from chloroviruses that encoded channels similar to that from MA-1D. There was no cross-reactivity with chloroviruses that encoded more diverse channels or with a chlorovirus that lacked a K(+) channel gene. Together with electron microscopic imaging, which revealed labelling of individual virus particles with the channel antibody, these results establish that the viral particles contain an active K(+) channel, presumably located in the lipid membrane that surrounds the DNA in the mature virions. PMID:23918407

  5. Photosynthetic Shutdown in Chlorella NC64A Associated with the Infection Cycle of Paramecium bursaria Chlorella Virus-1.

    PubMed Central

    Seaton, GGR.; Lee, K.; Rohozinski, J.

    1995-01-01

    The effects of the algal virus Paramecium bursaria Chlorella virus-1 on the photosynthetic physiology of its host, Chlorella NC64A, was studied by observing changes in Chl fluorescence quenching and O2 exchange. Metabolic changes were calibrated against electron microscopic analysis of the morphological changes that occur during the infection cycle. It takes approximately 10 h from attachment of the virus to final lysis of the host cell, so a complete infection cycle can be observed continuously in one experiment. During the early stages of the infection cycle many rapid changes occurred in the host cell's metabolism and these were reflected in changes of photosynthetic and respiratory rates. The dramatic inhibition of photosynthesis in Chlorella NC64A cells by P. bursaria Chlorella virus-1 has facilitated the use of fluorescence quenching as an accurate measure of the first phase of viral infection (attachment and penetration of the host cell) and the extent to which a population of host cells is infected. Effects of temperature and cation requirement of the infection cycle are described. The relevance of our observations to the events observed during viral infection of higher plants is discussed. PMID:12228553

  6. Symbiotic ciliates receive protection against UV damage from their algae: a test with Paramecium bursaria and Chlorella.

    PubMed

    Summerer, Monika; Sonntag, Bettina; Hörtnagl, Paul; Sommaruga, Ruben

    2009-05-01

    We assessed the photoprotective role of symbiotic Chlorella in the ciliate Paramecium bursaria by comparing their sensitivity to UV radiation (UVR) with Chlorella-reduced and Chlorella-free (aposymbiotic) cell lines of the same species. Aposymbiotic P. bursaria had significantly higher mortality than the symbiotic cell lines when exposed to UVR. To elucidate the protection mechanism, we assessed the algal distribution within the ciliate using thin-sections and transmission electron microscopy and estimated the screening factor by Chlorella based on an optical model. These analyses evidenced a substantial screening factor ranging, from 59.2% to 93.2% (320nm) for regular algal distribution. This screening efficiency reached up to approximately 100% when Chlorella algae were dislocated to the posterior region of the ciliate. The dislocation was observed in symbiotic ciliates only under exposure to UV plus photosynthetically active radiation (PAR) or to high PAR levels. Moreover, under exposure to UVB radiation and high PAR, symbiotic P. bursaria aggregated into dense spots. This behavior could represent an efficient avoidance strategy not yet described for ciliates. Analyses of the intact symbiosis and their algal symbionts for UV-screening compounds (mycosporine-like amino acids and sporopollenin) proved negative. Overall, our results show that photoprotection in this ciliate symbiosis represents an additional advantage to the hitherto postulated nutritional benefits. PMID:19195930

  7. Purification, in vitro reassembly, and preliminary sequence analysis of epiplasmins, the major constituent of the membrane skeleton of Paramecium.

    PubMed

    Coffe, G; Le Caer, J P; Lima, O; Adoutte, A

    1996-01-01

    The epiplasmic layer, a continuous rigid granulo-fibrillar sheet directly subtending the surface membranes of Paramecium, is one of the outermost of the various cytoskeletal networks that compose it cortex. We have previously shown that the epiplasm consists of a set of 30 to 50 protein bands on SDS-PAGE in the range 50 to 33 kDa, the epiplasmins. We report a purification procedure for the set of epiplasmic proteins, a description of their physicochemical and reassembly properties, and a preliminary characterization of their sequence. The conditions for solubilization of the epiplasm and for in vitro reassembly of its purified constituents ar described. Reassembly of the entire set of proteins and of some (but not all) subsets are shown to yield filamentous aggregates. Microsequences of two purified bands of epiplasmins reveal a striking amino acid sequence consisting of heptad repeats of only three main amino acids, P, V, and Q. These repeats were confirmed by DNA sequencing of polymerase chain reaction products. The motif is QPVQ-h, in which h is a hydrophobic residue. This may constitute the core of the epiplasmin sequence and, in view of the tendency of such a sequence to form a coiled-coil, may account for the remarkable self-aggregation properties of epiplasmins. PMID:8769725

  8. Evidence for the presence of a mammalian-like cholinesterase in Paramecium primaurelia (Protista, Ciliophora) developmental cycle.

    PubMed

    Delmonte Corrado, M U; Politi, H; Trielli, F; Angelini, C; Falugi, C

    1999-01-01

    By histochemical and immunohistochemical methods, the presence of cholinergic-like molecules has previously been demonstrated in Paramecium primaurelia, and their functional role in mating-cell pairing was suggested. In this work, both true acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activities were electrophoretically investigated, and the presence of molecules immunologically related to BuChE was checked by immunoblotting. The AChE activity, shown in the membrane protein fraction of mating-competent cells and in the cytoplasmic fraction of immature cells, is due to a 260-kDa molecular form, similar to the membrane-bound tetrameric form present in human erythrocytes. This AChE activity does not appear in either the cytoplasmic fraction of mating-competent cells or in the membrane protein fraction of immature cells. No evidence was found for the presence or the activity of BuChE-like molecules. The role of AChE in P. primaurelia developmental cycle is discussed. PMID:9990739

  9. Evolution of the α-Subunit of Na/K-ATPase from Paramecium to Homo sapiens: Invariance of Transmembrane Helix Topology.

    PubMed

    Morrill, Gene A; Kostellow, Adele B; Liu, Lijun; Gupta, Raj K; Askari, Amir

    2016-05-01

    Na/K-ATPase is a key plasma membrane enzyme involved in cell signaling, volume regulation, and maintenance of electrochemical gradients. The α-subunit, central to these functions, belongs to a large family of P-type ATPases. Differences in transmembrane (TM) helix topology, sequence homology, helix-helix contacts, cell signaling, and protein domains of Na/K-ATPase α-subunit were compared in fungi (Beauveria), unicellular organisms (Paramecia), primitive multicellular organisms (Hydra), and vertebrates (Xenopus, Homo sapiens), and correlated with evolution of physiological functions in the α-subunit. All α-subunits are of similar length, with groupings of four and six helices in the N- and C-terminal regions, respectively. Minimal homology was seen for protein domain patterns in Paramecium and Hydra, with high correlation between Hydra and vertebrates. Paramecium α-subunits display extensive disorder, with minimal helix contacts. Increases in helix contacts in Hydra approached vertebrates. Protein motifs known to be associated with membrane lipid rafts and cell signaling reveal significant positional shifts between Paramecium and Hydra vulgaris, indicating that regional membrane fluidity changes occur during evolution. Putative steroid binding sites overlapping TM-3 occurred in all species. Sites associated with G-protein-receptor stimulation occur both in vertebrates and amphibia but not in Hydra or Paramecia. The C-terminus moiety "KETYY," necessary for the Na(+) activation of pump phosphorylation, is not present in unicellular species indicating the absence of classical Na(+)/K(+)-pumps. The basic protein topology evolved earliest, followed by increases in protein domains and ordered helical arrays, correlated with appearance of α-subunit regions known to involve cell signaling, membrane recycling, and ion channel formation. PMID:26961431

  10. Identification of Two Nickel Ion-Induced Genes, NCI16 and PcGST1, in Paramecium caudatum

    PubMed Central

    Haga, Nobuyuki; Nakano, Takanari; Ikeda, Masaaki; Katayama, Shigehiro; Awata, Takuya

    2014-01-01

    Here, we describe the isolation of two nickel-induced genes in Paramecium caudatum, NCI16 and PcGST1, by subtractive hybridization. NCI16 encoded a predicted four-transmembrane domain protein (∼16 kDa) of unknown function, and PcGST1 encoded glutathione S-transferase (GST; ∼25 kDa) with GST and glutathione peroxidase (GPx) activities. Exposing cells to cobalt chloride also caused the moderate upregulation of NCI16 and PcGST1 mRNAs. Both nickel sulfate and cobalt chloride dose dependently induced NCI16 and PcGST1 mRNAs, but with different profiles. Nickel treatment caused a continuous increase in PcGST1 and NCI16 mRNA levels for up to 3 and 6 days, respectively, and a notable increase in H2O2 concentrations in P. caudatum. NCI16 expression was significantly enhanced by incubating cells with H2O2, implying that NCI16 induction in the presence of nickel ions is caused by reactive oxygen species (ROS). On the other hand, PcGST1 was highly induced by the antioxidant tert-butylhydroquinone (tBHQ) but not by H2O2, suggesting that different mechanisms mediate the induction of NCI16 and PcGST1. We introduced a luciferase reporter vector with an ∼0.42-kb putative PcGST1 promoter into cells and then exposed the transformants to nickel sulfate. This resulted in significant luciferase upregulation, indicating that the putative PcGST1 promoter contains a nickel-responsive element. Our nickel-inducible system also may be applicable to the efficient expression of proteins that are toxic to host cells or require temporal control. PMID:25001407

  11. A set of SNARE proteins in the contractile vacuole complex of Paramecium regulates cellular calcium tolerance and also contributes to organelle biogenesis.

    PubMed

    Schönemann, Barbara; Bledowski, Alexander; Sehring, Ivonne M; Plattner, Helmut

    2013-03-01

    The contractile vacuole complex (CVC) of freshwater protists serves the extrusion of water and ions, including Ca(2+). No vesicle trafficking based on SNAREs has been detected so far in any CVC. SNAREs (soluble NSF [N-ethylmaleimide sensitive factor] attachment protein receptors) are required for membrane-to-membrane interaction, i.e. docking and fusion also in Paramecium. We have identified three v-/R- and three t/Q-SNAREs selectively in the CVC. Posttranscriptional silencing of Syb2, Syb6 or Syx2 slows down the pumping cycle; silencing of the latter two also causes vacuole swelling. Increase in extracellular Ca(2+) after Syb2, Syb6 or Syx2 silencing causes further swelling of the contractile vacuole and deceleration of its pulsation. Silencing of Syx14 or Syx15 entails lethality in the Ca(2+) stress test. Thus, the effects of silencing strictly depend on the type of the silenced SNARE and on the concentration of Ca(2+) in the medium. This shows the importance of organelle-resident SNARE functions (which may encompass the vesicular delivery of other organelle-resident proteins) for Ca(2+) tolerance. A similar principle may be applicable also to the CVC in widely different unicellular organisms. In addition, in Paramecium, silencing particularly of Syx6 causes aberrant positioning of the CVC during de novo biogenesis before cytokinesis. PMID:23280185

  12. Distinct RNA-dependent RNA polymerases are required for RNAi triggered by double-stranded RNA versus truncated transgenes in Paramecium tetraurelia

    PubMed Central

    Marker, Simone; Le Mouël, Anne; Meyer, Eric; Simon, Martin

    2010-01-01

    In many eukaryotes, RNA-dependent RNA polymerases (RdRPs) play key roles in the RNAi pathway. They have been implicated in the recognition and processing of aberrant transcripts triggering the process, and in amplification of the silencing response. We have tested the functions of RdRP genes from the ciliate Paramecium tetraurelia in experimentally induced and endogenous mechanisms of gene silencing. In this organism, RNAi can be triggered either by high-copy, truncated transgenes or by directly feeding cells with double-stranded RNA (dsRNA). Surprisingly, dsRNA-induced silencing depends on the putatively functional RDR1 and RDR2 genes, which are required for the accumulation of both primary siRNAs and a distinct class of small RNAs suggestive of secondary siRNAs. In contrast, a third gene with a highly divergent catalytic domain, RDR3, is required for siRNA accumulation when RNAi is triggered by truncated transgenes. Our data further implicate RDR3 in the accumulation of previously described endogenous siRNAs and in the regulation of the surface antigen gene family. While only one of these genes is normally expressed in any clonal cell line, the knockdown of RDR3 leads to co-expression of multiple antigens. These results provide evidence for a functional specialization of Paramecium RdRP genes in distinct RNAi pathways operating during vegetative growth. PMID:20200046

  13. Distinct RNA-dependent RNA polymerases are required for RNAi triggered by double-stranded RNA versus truncated transgenes in Paramecium tetraurelia.

    PubMed

    Marker, Simone; Le Mouël, Anne; Meyer, Eric; Simon, Martin

    2010-07-01

    In many eukaryotes, RNA-dependent RNA polymerases (RdRPs) play key roles in the RNAi pathway. They have been implicated in the recognition and processing of aberrant transcripts triggering the process, and in amplification of the silencing response. We have tested the functions of RdRP genes from the ciliate Paramecium tetraurelia in experimentally induced and endogenous mechanisms of gene silencing. In this organism, RNAi can be triggered either by high-copy, truncated transgenes or by directly feeding cells with double-stranded RNA (dsRNA). Surprisingly, dsRNA-induced silencing depends on the putatively functional RDR1 and RDR2 genes, which are required for the accumulation of both primary siRNAs and a distinct class of small RNAs suggestive of secondary siRNAs. In contrast, a third gene with a highly divergent catalytic domain, RDR3, is required for siRNA accumulation when RNAi is triggered by truncated transgenes. Our data further implicate RDR3 in the accumulation of previously described endogenous siRNAs and in the regulation of the surface antigen gene family. While only one of these genes is normally expressed in any clonal cell line, the knockdown of RDR3 leads to co-expression of multiple antigens. These results provide evidence for a functional specialization of Paramecium RdRP genes in distinct RNAi pathways operating during vegetative growth. PMID:20200046

  14. The protozoan, Paramecium primaurelia, as a non-sentient model to test laser light irradiation: The effects of an 808nm infrared laser diode on cellular respiration.

    PubMed

    Amaroli, Andrea; Ravera, Silvia; Parker, Steven; Panfoli, Isabella; Benedicenti, Alberico; Benedicenti, Stefano

    2015-07-01

    Photobiomodulation (PBM) has been used in clinical practice for more than 40 years. Unfortunately, conflicting literature has led to the labelling of PBM as a complementary or alternative medicine approach. However, past and ongoing clinical and research studies by reputable investigators have re-established the merits of PBM as a genuine medical therapy, and the technique has, in the last decade, seen an exponential increase in the numbers of clinical instruments available, and their applications. This resurgence has led to a clear need for appropriate experimental models to test the burgeoning laser technology being developed for medical applications. In this context, an ethical model that employs the protozoan, Paramecium primaurelia, is proposed. We studied the possibility of using the measure of oxygen consumption to test PBM by irradiation with an infrared or near-infrared laser. The results show that an 808nm infrared laser diode (1W; 64J/cm²) affects cellular respiration in P. primaurelia, inducing, in the irradiated cells, a significantly (p < 0.05) increased oxygen consumption of about 40%. Our findings indicate that Paramecium can be an excellent tool in biological assays involving infrared and near-infrared PBM, as it combines the advantages of in vivo results with the practicality of in vitro testing. This test represents a fast, inexpensive and straightforward assay, which offers an alternative to both traditional in vivo testing and more expensive mammalian cellular cultures. PMID:26256394

  15. An ion-current mutant of Paramecium tetraurelia with defects in the primary structure and post-translational N-methylation of calmodulin

    SciTech Connect

    Wallen-Friedman, M.A.

    1988-01-01

    My work on pantophobiac A{sup 2} (pntA{sup 2}), a behavioral mutant of Paramecium tetraurelia, suggest that the Ca{sup ++}-binding protein calmodulin (CaM), and post-translation N-methylation of CaM, are important for Ca{sup ++}-related ion-current function. Calmodulin from wild-type Paramecium has two sites of lysine-N-methylation. Both of these sites are almost fully methylated in vivo; thus wild-type calmodulin is a poor substrate for N-methylation in vitro. In contrast, pntA/{sup 2} CaM can be heavily N-methylated in vitro, suggesting that the mutant calmodulin is under-methylated in vivo. Amino-acid composition analysis showed that CaM lysine 115 is undermethylated in pntA{sup 2}. Once pntA{sup 2} CaM is N-methylated, the (methyl-{sup 3}H) group does not turn over in either wild-type or pntA{sup 2} cytoplasmic fractions. The methylating enzymes in pntA{sup 2} high-speed supernatant fractions are active, but may be less robust than those of the wild type, suggesting a possible control of these enzymes by CaM.

  16. Effect of 808 nm Diode Laser on Swimming Behavior, Food Vacuole Formation and Endogenous ATP Production of Paramecium primaurelia (Protozoa).

    PubMed

    Amaroli, Andrea; Ravera, Silvia; Parker, Steven; Panfoli, Isabella; Benedicenti, Alberico; Benedicenti, Stefano

    2015-01-01

    Photobiomodulation (PBM) has been used in clinical practice for more than 40 years. To clarify the mechanisms of action of PBM at cellular and organism levels, we investigated its effect on Paramecium primaurelia (Protozoa) irradiated by an 808 nm infrared diode laser with a flat-top handpiece (1 W in CW). Our results led to the conclusion that: (1) the 808 nm laser stimulates the P. primaurelia without a thermal effect, (2) the laser effect is demonstrated by an increase in swimming speed and in food vacuole formation, (3) the laser treatment affects endogenous adenosine triphosphate (ATP) production in a positive way, (4) the effects of irradiation dose suggest an optimum exposure time of 50 s (64 J cm(-2) of fluence) to stimulate the Paramecium cells; irradiation of 25 s shows no effect or only mild effects and irradiation up to 100 s does not increase the effect observed with 50 s of treatment, (5) the increment of endogenous ATP concentration highlights the positive photobiomodulating effect of the 808 nm laser and the optimal irradiation conditions by the flat-top handpiece. PMID:26118482

  17. Isolation and characterization of a virus (CvV-BW1) that infects symbiotic algae of Paramecium bursaria in Lake Biwa, Japan

    PubMed Central

    2010-01-01

    Background We performed an environmental study of viruses infecting the symbiotic single-celled algae of Paramecium bursaria (Paramecium bursaria Chlorella virus, PBCV) in Lake Biwa, the largest lake in Japan. The viruses detected were all Chlorella variabilis virus (CvV = NC64A virus). One of them, designated CvV-BW1, was subjected to further characterization. Results CvV-BW1 formed small plaques and had a linear DNA genome of 370 kb, as judged by pulsed-field gel electrophoresis. Restriction analysis indicated that CvV-BW1 DNA belongs to group H, one of the most resistant groups among CvV DNAs. Based on a phylogenetic tree constructed using the dnapol gene, CvV was classified into two clades, A and B. CvV-BW1 belonged to clade B, in contrast to all previously identified virus strains of group H that belonged to clade A. Conclusions We conclude that CvV-BW1 composes a distinct species within C. variabilis virus. PMID:20831832

  18. Dynamic chromatin remodelling of ciliate macronuclear DNA as determined by an optimized chromatin immunoprecipitation (ChIP) method for Paramecium tetraurelia.

    PubMed

    Cheaib, Miriam; Simon, Martin

    2013-03-01

    We report the detailed evaluation of crucial parameters for chromatin immunoprecipitation (ChIP) of macronuclear DNA in the unicellular eukaryote Paramecium tetraurelia. Optimized parameters include crosslinking conditions, chromatin sonication and antibody titration thus providing a detailed protocol for successful ChIP in P. tetraurelia. As this ciliate is bacterivorous and RNAi by feeding represents a powerful tool for analysis of gene function, we moreover determined the effects of ingested nucleic acids by food bacteria. Feasibility of our protocol is demonstrated by characterisation of chromatin remodelling at promoters of cytosolic HSP70 isoforms during transcriptional activation under heat shock conditions by analyzing RNA abundance, nucleosome occupancy and levels of H3 lysine 9 acetylation. PMID:23385475

  19. Molecular aspects of calcium signalling at the crossroads of unikont and bikont eukaryote evolution--the ciliated protozoan Paramecium in focus.

    PubMed

    Plattner, Helmut

    2015-03-01

    The ciliated protozoan, Paramecium tetraurelia has a high basic Ca(2+) leakage rate which is counteracted mainly by export through a contractile vacuole complex, based on its V-type H(+)-ATPase activity. In addition Paramecium cells dispose of P-type Ca(2+)-ATPases, i.e. a plasmamembrane and a sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase (PMCA, SERCA). Antiporter systems are to be expected, as inferred from indirect evidence. Among the best known cytosolic Ca(2+)-binding proteins, calmodulin activates Ca(2+) influx channels in the somatic cell membrane, but inactivates Ca(2+) influx channels in cilia, where it, thus, ends ciliary reversal induced by depolarization via channels in the somatic cell membrane. Centrin inactivates Ca(2+) signals after stimulation by its high capacity/low affinity binding sites, whereas its high affinity sites regulate some other functions. Cortical Ca(2+) stores (alveolar sacs) are activated during stimulated trichocyst exocytosis and thereby mediate store-operated Ca(2+) entry (SOCE). Ca(2+) release channels (CRCs) localised to alveoli and underlying SOCE are considered as Ryanodine receptor-like proteins (RyR-LPs) which are members of a CRC family with 6 subfamilies. These also encompass genuine inositol 1,4,5-trisphosphate receptors (IP3Rs) and intermediates between the two channel types. All IP3R/RyR-type CRCs possess six carboxyterminal transmembrane domains (TMD), with a pore domain between TMD 5 and 6, endowed with a characteristic selectivity filter. There are reasons to assume a common ancestor molecule for such channels and diversification further on in evolution. The distinct distribution of specific CRCs in the different vesicles undergoing intracellular trafficking suggests constitutive formation of very locally restricted Ca(2+) signals during vesicle-vesicle interaction. In summary, essential steps of Ca(2+) signalling already occur at this level of evolution, including an unexpected multitude of CRCs. For dis

  20. Cellular membranes that undergo cyclic changes in tension: Direct measurement of force generation by an in vitro contractile vacuole of Paramecium multimicronucleatum.

    PubMed

    Tani, T; Allen, R D; Naitoh, Y

    2001-02-01

    The contractile vacuole of the fresh water protozoan Paramecium is a membrane-bound vesicle that expels excess cytosolic water, acquired osmotically, through its periodic exocytotic activity. The in vitro contractile vacuole, isolated in a small amount of cytosol from the Paramecium cell and confined under mineral oil, showed periodic rounding and slackening at regular intervals for an extended time. The contractile vacuole rounded against the cytosol-mineral oil boundary tension. The tension at the surface of the contractile vacuole is, therefore, assumed to increase during the rounding phase. We first estimated the tension relative to the boundary tension from the degree of compression of the contractile vacuole by the boundary. We then determined the absolute value for the tension at the surface of the contractile vacuole from the degree of bending of an elastic carbon fiber microcantilever (8 microm thick; 2 mm long), whose free end was placed at the surface of an in vitro contractile vacuole. The tension was found to increase to its maximum value of approximately 5 mN m(-)(1) when the contractile vacuole rounded. This value was more than 35 times higher than that for the slackened contractile vacuole. Electron micrographs of conventional thin sections of chemically fixed in vitro contractile vacuoles as well as those of in vivo contractile vacuoles obtained from rapid frozen and cryosubstituted cells revealed the lack of any ultrastructural evidence for the presence of a fibrous network system surrounding the contractile vacuole. Thus we conclude that the mechanism(s) by which tension is developed at the surface of the contractile vacuole membrane resides in the contractile vacuole membrane itself. We propose a hypothesis that periodic changes in the spontaneous curvature of the contractile vacuole's lipid bilayer membrane is involved in the periodic development of higher contractile vacuole membrane tension. The isolated CV promises to be an excellent model

  1. An Sfi1p-like centrin-binding protein mediates centrin-based Ca2+ -dependent contractility in Paramecium tetraurelia.

    PubMed

    Gogendeau, Delphine; Beisson, Janine; de Loubresse, Nicole Garreau; Le Caer, Jean-Pierre; Ruiz, Françoise; Cohen, Jean; Sperling, Linda; Koll, France; Klotz, Catherine

    2007-11-01

    The previous characterization and structural analyses of Sfi1p, a Saccharomyces cerevisiae centrin-binding protein essential for spindle pole body duplication, have suggested molecular models to account for centrin-mediated, Ca2+-dependent contractility processes (S. Li, A. M. Sandercock, P. Conduit, C. V. Robinson, R. L. Williams, and J. V. Kilmartin, J. Cell Biol. 173:867-877, 2006). Such processes can be analyzed by using Paramecium tetraurelia, which harbors a large Ca2+ -dependent contractile cytoskeletal network, the infraciliary lattice (ICL). Previous biochemical and genetic studies have shown that the ICL is composed of diverse centrin isoforms and a high-molecular-mass centrin-associated protein, whose reduced size in the démaillé (dem1) mutant correlates with defective organization of the ICL. Using sequences derived from the high-molecular-mass protein to probe the Paramecium genome sequence, we characterized the PtCenBP1 gene, which encodes a 460-kDa protein. PtCenBP1p displays six almost perfect repeats of ca. 427 amino acids (aa) and harbors 89 potential centrin-binding sites with the consensus motif LLX11F/LX2WK/R, similar to the centrin-binding sites of ScSfi1p. The smaller (260-kDa) protein encoded by the dem1 mutant PtCenBP1 allele comprises only two repeats of 427 aa and 46 centrin-binding sites. By using RNA interference and green fluorescent protein fusion experiments, we showed that PtCenBP1p forms the backbone of the ICL and plays an essential role in its assembly and contractility. This study provides the first in vivo demonstration of the role of Sfi1p-like proteins in centrin-mediated Ca2+-dependent contractile processes. PMID:17675401

  2. An Sfi1p-Like Centrin-Binding Protein Mediates Centrin-Based Ca2+-Dependent Contractility in Paramecium tetraurelia▿ †

    PubMed Central

    Gogendeau, Delphine; Beisson, Janine; de Loubresse, Nicole Garreau; Le Caer, Jean-Pierre; Ruiz, Françoise; Cohen, Jean; Sperling, Linda; Koll, France; Klotz, Catherine

    2007-01-01

    The previous characterization and structural analyses of Sfi1p, a Saccharomyces cerevisiae centrin-binding protein essential for spindle pole body duplication, have suggested molecular models to account for centrin-mediated, Ca2+-dependent contractility processes (S. Li, A. M. Sandercock, P. Conduit, C. V. Robinson, R. L. Williams, and J. V. Kilmartin, J. Cell Biol. 173:867-877, 2006). Such processes can be analyzed by using Paramecium tetraurelia, which harbors a large Ca2+-dependent contractile cytoskeletal network, the infraciliary lattice (ICL). Previous biochemical and genetic studies have shown that the ICL is composed of diverse centrin isoforms and a high-molecular-mass centrin-associated protein, whose reduced size in the démaillé (dem1) mutant correlates with defective organization of the ICL. Using sequences derived from the high-molecular-mass protein to probe the Paramecium genome sequence, we characterized the PtCenBP1 gene, which encodes a 460-kDa protein. PtCenBP1p displays six almost perfect repeats of ca. 427 amino acids (aa) and harbors 89 potential centrin-binding sites with the consensus motif LLX11F/LX2WK/R, similar to the centrin-binding sites of ScSfi1p. The smaller (260-kDa) protein encoded by the dem1 mutant PtCenBP1 allele comprises only two repeats of 427 aa and 46 centrin-binding sites. By using RNA interference and green fluorescent protein fusion experiments, we showed that PtCenBP1p forms the backbone of the ICL and plays an essential role in its assembly and contractility. This study provides the first in vivo demonstration of the role of Sfi1p-like proteins in centrin-mediated Ca2+-dependent contractile processes. PMID:17675401

  3. Genomic Characterization of Variable Surface Antigens Reveals a Telomere Position Effect as a Prerequisite for RNA Interference-Mediated Silencing in Paramecium tetraurelia

    PubMed Central

    Baranasic, Damir; Oppermann, Timo; Cheaib, Miriam; Cullum, John; Schmidt, Helmut

    2014-01-01

    ABSTRACT Antigenic or phenotypic variation is a widespread phenomenon of expression of variable surface protein coats on eukaryotic microbes. To clarify the mechanism behind mutually exclusive gene expression, we characterized the genetic properties of the surface antigen multigene family in the ciliate Paramecium tetraurelia and the epigenetic factors controlling expression and silencing. Genome analysis indicated that the multigene family consists of intrachromosomal and subtelomeric genes; both classes apparently derive from different gene duplication events: whole-genome and intrachromosomal duplication. Expression analysis provides evidence for telomere position effects, because only subtelomeric genes follow mutually exclusive transcription. Microarray analysis of cultures deficient in Rdr3, an RNA-dependent RNA polymerase, in comparison to serotype-pure wild-type cultures, shows cotranscription of a subset of subtelomeric genes, indicating that the telomere position effect is due to a selective occurrence of Rdr3-mediated silencing in subtelomeric regions. We present a model of surface antigen evolution by intrachromosomal gene duplication involving the maintenance of positive selection of structurally relevant regions. Further analysis of chromosome heterogeneity shows that alternative telomere addition regions clearly affect transcription of closely related genes. Consequently, chromosome fragmentation appears to be of crucial importance for surface antigen expression and evolution. Our data suggest that RNAi-mediated control of this genetic network by trans-acting RNAs allows rapid epigenetic adaptation by phenotypic variation in combination with long-term genetic adaptation by Darwinian evolution of antigen genes. PMID:25389173

  4. Time-variant analysis of organelle and vesicle movement during phagocytosis in Paramecium primaurelia by means of fluorescence confocal laser scanning microscopy.

    PubMed

    Ramoino, P; Beltrame, F; Diaspro, A; Fato, M

    1996-12-01

    Vital fluorescent dyes (FITC-albumin, Texas Red-albumin, and acridine orange) were used together with a confocal laser scanning optical microscope (CLSM) to display and analyze formation, movement, and fusion of vesicles during the phagocytosis of Paramecium primaurelia, in the x-y-z-t space. By immobilizing living cells pulsed with a food vacuole marker at successive times after chasing in unlabeled medium, the intracellular movement of food vacuoles from their formation at the cytostome to their egestion at the cytoproct was visualized, and food vacuoles were selected in a specific digestion stage. Small pinocytic vesicles are shown to evaginate from the vacuoles and move in the cytoplasm. These vesicles are transported toward the cytopharynx where they enlarge the membrane of the nascent food vacuoles or fuse with stage II food vacuoles, when the vacuoles of stage II increase their size, changing from an acidic to an alkaline status. A multimodal analysis of confocal fluorescence images and the false-color technique were used to visualize vesicle movement vs. time. Starting from three images of the same cell at succeeding time points, a composite image was generated by associating with each originally acquired image a different color corresponding to each sampling point in time. The composite image shows that vesicles move away from the food vacuole in a scattered manner exhibiting changes in direction. PMID:8989767

  5. One-way calcium spill-over during signal transduction in Paramecium cells: from the cell cortex into cilia, but not in the reverse direction.

    PubMed

    Husser, Marc R; Hardt, Martin; Blanchard, Marie-Pierre; Hentschel, Joachim; Klauke, Norbert; Plattner, Helmut

    2004-11-01

    We asked to what extent Ca(2+) signals in two different domains of Paramecium cells remain separated during different stimulations. Wild-type (7S) and pawn cells (strain d4-500r, without ciliary voltage-dependent Ca(2+)-channels) were stimulated for trichocyst exocytosis within 80 ms by quenched-flow preparation and analysed by energy-dispersive X-ray microanalysis (EDX), paralleled by fast confocal fluorochrome analysis. We also analysed depolarisation-dependent calcium signalling during ciliary beat rerversal, also by EDX, after 80-ms stimulation in the quenched-flow mode. EDX and fluorochrome analysis enable to register total and free intracellular calcium concentrations, [Ca] and [Ca(2+)], respectively. After exocytosis stimulation we find by both methods that the calcium signal sweeps into the basis of cilia, not only in 7S but also in pawn cells which then also perform ciliary reversal. After depolarisation we see an increase of [Ca] along cilia selectively in 7S, but not in pawn cells. Opposite to exocytosis stimulation, during depolarisation no calcium spill-over into the nearby cytosol and no exocytosis occurs. In sum, we conclude that cilia must contain a very potent Ca(2+) buffering system and that ciliary reversal induction, much more than exocytosis stimulation, involves strict microdomain regulation of Ca(2+) signals. PMID:15451619

  6. Timing of initiation of macronuclear DNA synthesis is set during the preceding cell cycle in Paramecium tetraurelia: analysis of the effects of abrupt changes in nutrient level

    SciTech Connect

    Ching, A.S.L.; Berger, J.D.

    1986-11-01

    In many eukaryotic organisms, initiation of DNA synthesis is associated with a major control point within the cell cycle and reflects the commitment of the cell to the DNA replication-division portion of the cell cycle. In paramecium, the timing of DNA synthesis initiation is established prior to fission during the preceding cell cycle. DNA synthesis normally starts at 0.25 in the cell cycle. When dividing cells are subjected to abrupt nutrient shift-up by transfer from a chemostat culture to medium with excess food, or shift-down from a well-fed culture to exhausted medium, DNA synthesis initiation in the post-shift cell cycle occurs at 0.25 of the parental cell cycle and not at either 0.25 in the post-shift cell cycle or at 0.25 in the equilibrium cell cycle produced under the post-shift conditions. The long delay prior to initiation of DNA synthesis following nutritional shift-up is not a consequence of continued slow growth because the rate of protein synthesis increases rapidly to the normal level after shift-up. Analysis of the relation between increase in cell mass and initiation of DNA synthesis following nutritional shifts indicates that increase in cell mass, per se, is neither a necessary nor a sufficient condition for initiation of DNA synthesis, in spite of the strong association between accumulation of cell mass and initiation of DNA synthesis in cells growing under steady-state conditions.

  7. "Candidatus Sonnebornia yantaiensis", a member of candidate division OD1, as intracellular bacteria of the ciliated protist Paramecium bursaria (Ciliophora, Oligohymenophorea).

    PubMed

    Gong, Jun; Qing, Yao; Guo, Xiaohong; Warren, Alan

    2014-02-01

    An intracellular bacterium was discovered in an isolate of Paramecium bursaria from a freshwater pond in Yantai, China. The bacteria were abundant and exclusively found in the cytoplasm of the host which, along with the green alga Chlorella, formed a three-partner consortium that could survive in pure water for at least one week. Cloning, sequencing and phylogenetic analysis of the bacterial 16S rRNA gene showed that the bacterium belonged to the uncultured candidate division OD1, which usually forms part of the rare biosphere. Transmission electron microscopy and fluorescence in situ hybridization (FISH) with specific probes showed that the bacteria were usually located close to the perialgal membranes of endosymbiotic Chlorella cells, and occasionally irregularly distributed throughout the host cytoplasm. The name "Candidatus Sonnebornia yantaiensis" gen. nov., sp. nov. is proposed for the new bacterium. A strongly supported monophyletic subclade, OD1-p, which included the new species, was recognized and this study highlights that protists can be important hosts for rare bacterial taxa. PMID:24231291

  8. Genetic evidence for a role of centrin-associated proteins in the organization and dynamics of the infraciliary lattice in Paramecium.

    PubMed

    Klotz, C; Garreau de Loubresse, N; Ruiz, F; Beisson, J

    1997-01-01

    Within the superfamily of "EF-hand Ca2+-modulated proteins," centrins constitute a family of cytoskeletal proteins that are highly conserved from lower eukaryotes to man. Their cytoskeletal specialization is manifest in their capacity to form filamentous contractile arrays of various shapes and functions and by their association with microtubule organizing centres (MTOCs). While the latter property has been conserved throughout the evolution of eukaryotes, centrin-based contractile structures are only found in protists where they form arrays of widely diverse organization and function. In the ciliate Paramecium tetraurelia, three centrin genes have been characterized, which may be part of a larger centrin gene family [Madeddu et al., 1996: Eur J. Biochem. 238:121-128]. The products of these genes were originally identified as components of the infraciliary lattice, a contractile cytoskeletal network [Garreau de Loubresse et al., 1991: Biol. Cell 71:217-225]. We show here that centrins are localized not only in this lattice but also in basal bodies and in the cord, a filamentous structure associated with the oral apparatus. We demonstrate that in the infraciliary lattice, but not in basal bodies, centrins are associated with high-molecular-weight proteins (ca. 350 kD). Their role in the biogenesis of the infraciliary lattice is documented by cytological and biochemical properties of the mutant "démaillé" (dem1) characterized by altered centrin-associated proteins and abnormal organization and dynamics of the infraciliary lattice. PMID:9331221

  9. Molecular characterization of a sarco(endo)plasmic reticulum Ca2+-ATPase gene from Paramecium tetraurelia and localization of its gene product to sub-plasmalemmal calcium stores.

    PubMed Central

    Hauser, K; Pavlovic, N; Kissmehl, R; Plattner, H

    1998-01-01

    A cDNA encoding the gene for a sarco(endo)plasmic reticulum-type Ca2+-ATPase (SERCA) was isolated from a cDNA library of Paramecium tetraurelia by using degenerated primers according to conserved domains of SERCA-type ATPases. The identified nucleotide sequence (PtSERCA) is 3114 nucleotides in length with an open reading frame of 1037 amino acids. An intron of only 22 nucleotides occurs. Homology searches for the deduced amino acid sequence revealed 38-49% similarity to SERCA-type ATPases from organisms ranging from protozoans to mammals, with no more similarity to some parasitic protozoa of the same phylum. The calculated molecular mass of the encoded protein is 114.7 kDa. It contains the typical 10 transmembrane domains of SERCA-type ATPases and other conserved domains, such as the phosphorylation site and the ATP binding site. However, there are no binding sites for phospholamban and thapsigargin present in the PtSERCA. Antibodies raised against a cytoplasmic loop peptide between the phosphorylation site and the ATP binding site recognize on Western blots a protein of 106 kDa, exclusively in the fraction of sub-plasmalemmal calcium stores ('alveolar sacs'). In immunofluorescence studies the antibodies show labelling exclusively in the cell cortex of permeabilized cells in a pattern characteristic of the arrangement of alveolar sacs. When alveolar sacs where tested for phosphoenzyme-intermediate formation a phosphoprotein of the same molecular mass (106 kDa) could be identified. PMID:9693098

  10. Paramecium bursaria Chlorella virus 1 encodes two enzymes involved in the biosynthesis of GDP-L-fucose and GDP-D-rhamnose.

    PubMed

    Tonetti, Michela; Zanardi, Davide; Gurnon, James R; Fruscione, Floriana; Armirotti, Andrea; Damonte, Gianluca; Sturla, Laura; De Flora, Antonio; Van Etten, James L

    2003-06-13

    At least three structural proteins in Paramecium bursaria Chlorella virus (PBCV-1) are glycosylated, including the major capsid protein Vp54. However, unlike other glycoprotein-containing viruses that use host-encoded enzymes in the endoplasmic reticulum-Golgi to glycosylate their proteins, PBCV-1 encodes at least many, if not all, of the glycosyltransferases used to glycosylate its structural proteins. As described here, PBCV-1 also encodes two open reading frames that resemble bacterial and mammalian enzymes involved in de novo GDP-L-fucose biosynthesis. This pathway, starting from GDP-D-mannose, consists of two sequential steps catalyzed by GDP-D-mannose 4,6 dehydratase (GMD) and GDP-4-keto-6-deoxy-D-mannose epimerase/reductase, respectively. The two PBCV-1-encoded genes were expressed in Escherichia coli, and the recombinant proteins had the predicted enzyme activity. However, in addition to the dehydratase activity, PBCV-1 GMD also had a reductase activity, producing GDP-D-rhamnose. In vivo studies established that PBCV-1 GMD and GDP-4-keto-6-deoxy-D-mannose epimerase/reductase are expressed after virus infection and that both GDP-L-fucose and GDP-D-rhamnose are produced in virus-infected cells. Thus, PBCV-1 is the first virus known to encode enzymes involved in nucleotide sugar metabolism. Because fucose and rhamnose are components of the glycans attached to Vp54, the pathway could circumvent a limited supply of GDP sugars by the algal host. PMID:12679342

  11. Simulation model of Cryptomonas ovata population dynamics in southern Kootenay Lake, British Columbia

    USGS Publications Warehouse

    Cloern, James E.

    1978-01-01

    The model simulates well the timing and magnitude of all observed population changes and, more importantly, it gives insight into the important mechanisms which regulate population density of C. ovata in this natural system.

  12. Application of fluorescence resonance energy transfer techniques to the study of lectin-binding site distribution on Paramecium primaurelia (Protista, Ciliophora) cell surface.

    PubMed

    Locatelli, D; Delmonte Corrado, M U; Politi, H; Bottiroli, G

    1998-01-01

    Fluorescence resonance energy transfer (FRET) is a photophysical phenomenon occurring between the molecules of two fluorochromes with suitable spectral characteristics (donor-acceptor dye pair), and consisting in an excitation energy migration through a non-radiative process. Since the efficiency of the process is strictly dependent on the distance and reciprocal orientation of the donor and acceptor molecules, FRET-based techniques can be successfully applied to the study of biomolecules and cell component organisation and distribution. These techniques have been employed in studying Paramecium primaurelia surface membrane for the reciprocal distribution of N-acetylneuraminic acid (NeuAc) and N-acetylglucosamine (GlcNAc) glycosidic residues, which were found to be involved in mating cell pairing. NeuAc and GlcNAc were detected by their specific binding lectins, Limulus polyphemus agglutinin (LPA) and wheat germ agglutinin (WGA), respectively. Microspectrofluorometric analysis afforded the choice of fluorescein isothiocyanate and Texas red conjugated with LPA and WGA, respectively, as a suitable donor-acceptor couple efficiently activating FRET processes. Studies performed both in solution and in cells allowed to define the experimental conditions favourable for a FRET analysis. The comparative study carried out both on the conjugating-region and the non conjugating region of the surface membrane, indicates that FRET distribution appears quite homogeneous in mating-competent mating type (mt) I, whereas, in mating-competent mt II cells, FRET distribution seems to be preferentially localised on the conjugating-region functionally involved in mating cell pairing. This difference in the distribution of lectin-binding sites is suggested to be related to mating-competence acquisition. PMID:9857246

  13. Synthesis of the signal molecule acetylcholine during the developmental cycle of Paramecium primaurelia (Protista, Ciliophora) and its possible function in conjugation.

    PubMed

    Delmonte Corrado, M U; Politi, H; Ognibene, M; Angelini, C; Trielli, F; Ballarini, P; Falugi, C

    2001-06-01

    We recently discovered, in mating-competent Paramecium primaurelia, the presence of functionally related molecules of the cholinergic system: the neurotransmitter acetylcholine (ACh), both its nicotinic and muscarinic receptors and its lytic enzyme acetylcholinesterase (AChE). Our results on the inhibition of mating-cell pairing in vivo in mating-competent cells treated with cholinomimetic drugs support the hypothesis that the cholinergic system plays a role in cell-to-cell adhesion. To investigate the possible function of the signal molecule ACh in conjugation in P. primaurelia, we attempted to detect the intracellular sites of ACh synthesis by localizing the ACh biosynthetic enzyme choline acetyltransferase (ChAT). Using immunocytochemical and histochemical methods, we have demonstrated the presence and activity of ChAT principally on the surface membrane of mating-competent cells and of mature but non-mating-competent cells. No evidence for ChAT activity was found in immature cells. Immunoblot analysis revealed the presence of immunoreactive bands, ranging in molecular mass from 42 to 133 kDa, as reported for ChAT isolated from higher organisms. In vivo experiments showed that inhibition of ChAT activity by Congo Red, known to be a potent competitive inhibitor of acetyl coenzyme A, did not affect mating-cell pairing. Conversely, inhibition of AChE with BW 284c51 or eserine, which block enzyme activity by reacting with a specific serine within the catalytic centre, significantly inhibited mating-cell pairing. Our results suggest that ACh has a negative modulating effect on conjugation in P. primaurelia. PMID:11441032

  14. Electrical properties and fusion dynamics of in vitro membrane vesicles derived from separate parts of the contractile vacuole complex of Paramecium multimicronucleatum.

    PubMed

    Sugino, Kazuyuki; Tominaga, Takashi; Allen, Richard D; Naitoh, Yutaka

    2005-10-01

    The contractile vacuole complex of Paramecium multimicronucleatum transforms into membrane-bound vesicles on excision from the cell. The I-V relationship was linear in a voltage range of -80 to +80 mV in all vesicles, despite being derived from different parts of the contractile vacuole complex. No voltage-gated unit currents were observed in membrane patches from the vesicles. Vesicles derived from the radial arm showed a membrane potential of >10 mV, positive with reference to the cytosol, while those derived from the contractile vacuole showed a residual (<5 mV) membrane potential. The electrogenic V-ATPases in the decorated spongiome are responsible for the positive potential, and Cl- leakage channels are responsible for the residual potential. The specific resistance of the vesicle membrane (approximately 6 kOmega cm2) increased, while the membrane potential shifted in a negative direction when the vesicle rounded. An increase in the membrane tension (to approximately 5 x 10(-3) N m(-1)) is assumed to reduce the Cl- leakage conductance. It is concluded that neither voltage- nor mechano-sensitive ion channels are involved in the control of the fluid segregation and membrane dynamics that govern fluid discharge cycles in the contractile vacuole complex. The membrane vesicles shrank when the external osmolarity was increased, and swelled when the osmolarity was decreased, implying that the contractile vacuole complex membrane is water permeable. The water permeability of the membrane was 4-20 x 10(-7) microm s(-1) Pa(-1). The vesicles containing radial arm membrane swelled after initially shrinking when exposed to higher external osmolarity, implying that the V-ATPases energize osmolyte transport mechanisms that remain functional in the vesicle membrane. The vesicles showed an abrupt (<30 ms), slight, slackening after rounding to the maximum extent. Similar slackening was also observed in the contractile vacuoles in situ before the opening of the contractile

  15. Effects of diuron and carbofuran pesticides in their pure and commercial forms on Paramecium caudatum: The use of protozoan in ecotoxicology.

    PubMed

    Mansano, Adrislaine S; Moreira, Raquel A; Pierozzi, Mayara; Oliveira, Thiessa M A; Vieira, Eny M; Rocha, Odete; Regali-Seleghim, Mirna H

    2016-06-01

    Toxic effects of diuron and carbofuran on Paramecium caudatum were evaluated. Acute and chronic tests were conducted with diuron and carbofuran active ingredients and their commercial formulations, Diuron Nortox(®) 500 SC and Furadan(®) 350 SC, respectively. The sensitivity range of P. caudatum to reference substance sodium chloride was established. A preliminary risk assessment of diuron and carbofuran for Brazilian water bodies was performed. The tests indicated that toxicity of pure diuron and its commercial formulation was similar, while the commercial product carbofuran was more toxic than its pure form. In acute tests, readings were carried out at 2, 3, 4 and 6 h and showed an increase of mortality with increasing exposure time. The sensitivity of P. caudatum to NaCl ranged from 3.31 to 4.44 g L(-1), averaging 3.88 g L(-1). For diuron, the 6 h LC50 was 64.6 ± 3.3 mg L(-1) for its pure form and 62.4 ± 2.5 mg L(-1) for its commercial formulation. Carbofuran active ingredient was less toxic than that of diuron, presenting a 6 h LC50 of 142.0 ± 2.4 mg L(-1) for its pure form and 70.4 ± 2.2 mg L(-1) for its commercial product. Chronic tests showed that these pesticides cause significant decrease on population growth, generation number and biomass of P. caudatum. The 24 h IC50 was 7.10 ± 0.58 mg L(-1) for pure diuron, 6.78 ± 0.92 mg L(-1) for commercial diuron, 22.95 ± 3.57 mg L(-1) for pure carbofuran and 4.98 ± 0.62 mg L(-1) for commercial carbofuran. Preliminary risk assessment indicated that diuron and carbofuran present potential ecological risks for Brazilian water bodies. P. caudatum was a suitable and sensitive test organism to evaluate diuron and carbofuran toxicity to freshwater protozooplankton and, taking into account the relevant role of protozoans in aquatic environments, we strongly recommend its inclusion in ecotoxicological studies. PMID:26890484

  16. Site-Directed Mutagenesis, in Vivo Electroporation and Mass Spectrometry in Search for Determinants of the Subcellular Targeting of Rab7b Paralogue in the Model Eukaryote Paramecium Octaurelia

    PubMed Central

    Wyroba, E.; Kwaśniak, P.; Miller, K.; Kobyłecki, K.; Osińska, M.

    2016-01-01

    Protein products of paralogous genes resulting from whole genome duplication may acquire new functions. The role of post-translational modifications (PTM) in proper targeting of Paramecium Rab7b paralogue (distinct from that of Rab7a directly involved in phagocytosis) was studied using point mutagenesis, proteomic analysis and double immunofluorescence after in vivo electroporation of the mutagenized protein. Here we show that substitution of Thr200 by Ala diminished the incorporation of [P32] by 37% and of [C14-]UDP-glucose by 24% into recombinant Rab7b_200 in comparison to the non-mutagenized control. Double confocal imaging revealed that Rab7b_200 was mistargeted upon electroporation into living cells in contrast to non-mutagenized recombinant Rab7b correctly incorporated in the cytostome area. Using nano LC-MS/MS to compare the peptide map of Rab7b with that after deglycosylation with a mixture of five enzymes of different specificity we identified a peptide ion at m/z=677.63+ representing a glycan group attached to Thr200. Based on its mass and quantitative assays with [P32] and [C14]UDP-glucose, the suggested composition of the adduct attached to Thr200 is (Hex)1(HexNAc)1(Phos)3 or (HexNAc)1 (Deoxyhexose)1 (Phos)1 (HexA)1. These data indicate that PTM of Thr200 located in the hypervariable C-region of Paramecium octaurelia Rab7b is crucial for the proper localization/function of this protein. Moreover, the two Rab7 paralogues differ also in another PTM: substantially more phosphorylated amino acid residues are in Rab7b than in Rab7a. PMID:27349314

  17. Site-directed mutagenesis, in vivo electroporation and mass spectrometry in search for determinants of the subcellular targeting of Rab7b paralogue in the model eukaryote Paramecium octaurelia.

    PubMed

    Wyroba, E; Kwaśniak, P; Miller, K; Kobyłecki, K; Osińska, M

    2016-01-01

    Protein products of the paralogous genes resulting from the whole genome duplication may acquire new function. The role of post-translational modifications (PTM) in proper targeting of Paramecium Rab7b paralogue - distinct from that of Rab7a directly involved in phagocytosis - was studied using point mutagenesis, proteomic analysis and double immunofluorescence after in vivo electroporation of the mutagenized protein. Here we show that substitution of Thr200 by Ala200 resulted in diminished incorporation of [P32] by 37.4% and of 32 [C14-]UDP-glucose by 24%, respectively, into recombinant Rab7b_200 in comparison to the non-mutagenized control. Double confocal imaging revealed that Rab7b_200 was mistargeted upon electroporation into living cells contrary to non- mutagenized recombinant Rab7b correctly incorporated in the cytostome area. We identified the peptide ion at m/z=677.63+ characteristic for the glycan group attached to Thr200 in Rab7b using nano LC-MS/MS and comparing the peptide map of this protein with that after deglycosylation with the mixture of five enzymes of different specificity. Based on the mass of this peptide ion and quantitative radioactive assays with [P32]and  [C14-]UDP- glucose, the suggested composition of the adduct attached to Thr200 might be (Hex)1(HexNAc)1(Phos)3 or (HexNAc)1 (Deoxyhexose)1 (Phos)1 (HexA)1. These data indicate that PTM of Thr200 located in the hypervariable C-region of Rab7b in Paramecium is crucial for the proper localization/function of this protein. Moreover, these proteins differ also in other PTM: the number of phosphorylated amino acids in Rab7b is much higher than in Rab7a. PMID:27349314

  18. Nitrate reduction

    DOEpatents

    Dziewinski, Jacek J.; Marczak, Stanislaw

    2000-01-01

    Nitrates are reduced to nitrogen gas by contacting the nitrates with a metal to reduce the nitrates to nitrites which are then contacted with an amide to produce nitrogen and carbon dioxide or acid anions which can be released to the atmosphere. Minor amounts of metal catalysts can be useful in the reduction of the nitrates to nitrites. Metal salts which are formed can be treated electrochemically to recover the metals.

  19. Radon reduction

    SciTech Connect

    Hamilton, M.A. )

    1990-11-01

    During a radon gas screening program, elevated levels of radon gas were detected in homes on Mackinac Island, Mich. Six homes on foundations with crawl spaces were selected for a research project aimed at reducing radon gas concentrations, which ranged from 12.9 to 82.3 pCi/l. Using isolation and ventilation techniques, and variations thereof, radon concentrations were reduced to less than 1 pCi/l. This paper reports that these reductions were achieved using 3.5 mil cross laminated or 10 mil high density polyethylene plastic as a barrier without sealing to the foundation or support piers, solid and/or perforated plastic pipe and mechanical fans. Wind turbines were found to be ineffective at reducing concentrations to acceptable levels. Homeowners themselves installed all materials.

  20. Differences in infectivity between endosymbiotic Chlorella variabilis cultivated outside host Paramecium bursaria for 50 years and those immediately isolated from host cells after one year of reendosymbiosis

    PubMed Central

    Kodama, Y.; Fujishima, M.

    2016-01-01

    ABSTRACT Chlorella variabilis strain NC64A is an intracellular photobiont of the ciliate Paramecium bursaria. NC64A was isolated from P. bursaria nearly 50 years ago and was thereafter cultivated outside the host. This study was undertaken to detect changes in its infectivity to P. bursaria and its auxotrophy for growth outside the host induced during long-term cultivation. NC64A can grow in Modified Bold's Basal Medium but not in C medium, whereas another symbiotic Chlorella variabilis strain, 1N, that was recently isolated from the host grew in C medium but not in Modified Bold's Basal Medium. With regards infectivity, NC64A in the logarithmic phase of growth showed low infectivity to alga-removed P. bursaria cells, whereas those in the early stationary phase showed high infectivity of about 30%. Those in the decay phase of growth showed no infectivity. Results show that NC64A has infectivity, but the infection rate depends on their culture age in the growth curve. Furthermore, NC64A that had been re-infected to P. bursaria for more than one year and isolated from the host showed a nearly 100% infection rate, which indicates that NC64A can recover its infectivity by re-infection to P. bursaria. PMID:26718931

  1. Differences in infectivity between endosymbiotic Chlorella variabilis cultivated outside host Paramecium bursaria for 50 years and those immediately isolated from host cells after one year of reendosymbiosis.

    PubMed

    Kodama, Y; Fujishima, M

    2015-01-01

    Chlorella variabilis strain NC64A is an intracellular photobiont of the ciliate Paramecium bursaria. NC64A was isolated from P. bursaria nearly 50 years ago and was thereafter cultivated outside the host. This study was undertaken to detect changes in its infectivity to P. bursaria and its auxotrophy for growth outside the host induced during long-term cultivation. NC64A can grow in Modified Bold's Basal Medium but not in C medium, whereas another symbiotic Chlorella variabilis strain, 1N, that was recently isolated from the host grew in C medium but not in Modified Bold's Basal Medium. With regards infectivity, NC64A in the logarithmic phase of growth showed low infectivity to alga-removed P. bursaria cells, whereas those in the early stationary phase showed high infectivity of about 30%. Those in the decay phase of growth showed no infectivity. Results show that NC64A has infectivity, but the infection rate depends on their culture age in the growth curve. Furthermore, NC64A that had been re-infected to P. bursaria for more than one year and isolated from the host showed a nearly 100% infection rate, which indicates that NC64A can recover its infectivity by re-infection to P. bursaria. PMID:26718931

  2. Reductive dissolution of goethite by phenolic reductants

    NASA Astrophysics Data System (ADS)

    LaKind, Judy S.; Stone, Alan T.

    1989-05-01

    The reductive dissolution of goethite (α-FeOOH) and hematite (α-Fe 2O 3) by phenolic reductants has been examined in order to improve the understanding of iron transformations in soils, sediments and aquifers. Rates of goethite reductive dissolution by hydroquinone increased as the pH was increased from pH 1.8 to 4.65, arid the following reaction stoichiometry was obeyed: 2 α- FeOOH + QH2 = 2 Fe2+ + Q + 4 OH-. As the pH was increased from pH 4.5 to 6.0, the reductive dissolution rate decreased to below the detection limit. At pH 3.4, the reductive dissolution of hematite was two orders of magnitude slower than goethite. The relationship between structure and reactivity was examined for a series of mono-, di-, and tri-hydroxybenzene reductants. Rates of reductive dissolution decreased in the following order: catechol ˜- hydroquinone > 3,4-dihydroxybenzoic acid > resorcinol-phenol-4-hydroxybenzoic acid.

  3. Drag reduction in nature

    NASA Technical Reports Server (NTRS)

    Bushnell, D. M.; Moore, K. J.

    1991-01-01

    Recent studies on the drag-reducing shapes, structures, and behaviors of swimming and flying animals are reviewed, with an emphasis on potential analogs in vehicle design. Consideration is given to form drag reduction (turbulent flow, vortex generation, mass transfer, and adaptations for body-intersection regions), skin-friction drag reduction (polymers, surfactants, and bubbles as surface 'additives'), reduction of the drag due to lift, drag-reduction studies on porpoises, and drag-reducing animal behavior (e.g., leaping out of the water by porpoises). The need for further research is stressed.

  4. Drag reduction in nature

    NASA Astrophysics Data System (ADS)

    Bushnell, D. M.; Moore, K. J.

    Recent studies on the drag-reducing shapes, structures, and behaviors of swimming and flying animals are reviewed, with an emphasis on potential analogs in vehicle design. Consideration is given to form drag reduction (turbulent flow, vortex generation, mass transfer, and adaptations for body-intersection regions), skin-friction drag reduction (polymers, surfactants, and bubbles as surface 'additives'), reduction of the drag due to lift, drag-reduction studies on porpoises, and drag-reducing animal behavior (e.g., leaping out of the water by porpoises). The need for further research is stressed.

  5. Does Source Reduction Work?

    ERIC Educational Resources Information Center

    Allaway, David

    1992-01-01

    Suggests that quantification is essential to establish the cost-effectiveness of source reduction (SR). Presents case studies of monitoring methods for seven different kinds of SR efforts: (1) packaging changes, (2) SR businesses, (3) waste exchanges, (4) individual nonresidential efforts, (5) variable garbage rates, (6) yard waste reduction, and…

  6. Intelligent Data Reduction (IDARE)

    NASA Technical Reports Server (NTRS)

    Brady, D. Michael; Ford, Donnie R.

    1990-01-01

    A description of the Intelligent Data Reduction (IDARE) expert system and an IDARE user's manual are given. IDARE is a data reduction system with the addition of a user profile infrastructure. The system was tested on a nickel-cadmium battery testbed. Information is given on installing, loading, maintaining the IDARE system.

  7. Footprint reduction's 'multiple paybacks'.

    PubMed

    2010-06-01

    Some of the measures that EFM personnel can take to further reduce their estates' carbon footprint at a time when pressure to cut energy consumption must be balanced both against the requirement to create the best possible patient environment, and new medical technology that may require substantial energy to operate, were the focus of a recent IHEEM carbon reduction seminar in London. The one-day event, "Planning to achieve Carbon Reduction Commitment targets for healthcare premises", also included a look at the key steps affected healthcare organisations, and especially their estates teams, need to be taking already to ensure compliance with the new Carbon Reduction Commitment scheme. PMID:20597381

  8. AMD NOX REDUCTION IMPACTS

    EPA Science Inventory

    This is the first phase of a potentially multi-phase project aimed at identifying scientific methodologies that will lead to the development of innnovative analytical tools supporting the analysis of control strategy effectiveness, namely. accountabilty. Significant reductions i...

  9. Reduction of bone strength

    NASA Technical Reports Server (NTRS)

    Bingham, Cindy

    1990-01-01

    Viewgraphs on reduction of bone strength are presented. WEHI 231 B growth rates, experimental chambers used to apply the electric field to the cell cultures, and a mouse suspended by rotating cuff in electromagnetic field are shown.

  10. Stress and stress reduction.

    PubMed

    Straub, Heather; Qadir, Sameen; Miller, Greg; Borders, Ann

    2014-09-01

    Chronic stress contributes to preterm birth (PTB), through direct physiological mechanisms or behavioral pathways. This review identified interventions to prevent PTB through decreased maternal stress. Studies were grouped according to intervention: group prenatal care (11 studies), care coordination (8 studies), health insurance expansion (4 studies), expanded prenatal education/support in the clinic (8 studies), home visitation (9 studies), telephone contact (2 studies), or stress-reduction strategies (5 studies). Group prenatal care had the most evidence for PTB prevention. Comparative studies of PTB prevention through different models of prenatal care and maternal support, education, empowerment, stress-reduction, and coping strategies are needed. PMID:24979355

  11. Time, Chance, and Reduction

    NASA Astrophysics Data System (ADS)

    Ernst, Gerhard; Hüttemann, Andreas

    2010-01-01

    List of contributors; 1. Introduction Gerhard Ernst and Andreas Hütteman; Part I. The Arrows of Time: 2. Does a low-entropy constraint prevent us from influencing the past? Mathias Frisch; 3. The part hypothesis meets gravity Craig Callender; 4. Quantum gravity and the arrow of time Claus Kiefer; Part II. Probability and Chance: 5. The natural-range conception of probability Jacob Rosenthal; 6. Probability in Boltzmannian statistical mechanics Roman Frigg; 7. Humean mechanics versus a metaphysics of powers Michael Esfeld; Part III. Reduction: 8. The crystallisation of Clausius's phenomenological thermodynamics C. Ulises Moulines; 9. Reduction and renormalization Robert W. Batterman; 10. Irreversibility in stochastic dynamics Jos Uffink; Index.

  12. REDUCTIONS WITHOUT REGRET: SUMMARY

    SciTech Connect

    Swegle, J.; Tincher, D.

    2013-09-16

    This paper briefly summarizes the series in which we consider the possibilities for losing, or compromising, key capabilities of the U.S. nuclear force in the face of modernization and reductions. The first of the three papers takes an historical perspective, considering capabilities that were eliminated in past force reductions. The second paper is our attempt to define the needed capabilities looking forward in the context of the current framework for force modernization and the current picture of the evolving challenges of deterrence and assurance. The third paper then provides an example for each of our undesirable outcomes: the creation of roach motels, box canyons, and wrong turns.

  13. Discrete reductive perturbation technique

    SciTech Connect

    Levi, Decio; Petrera, Matteo

    2006-04-15

    We expand a partial difference equation (P{delta}E) on multiple lattices and obtain the P{delta}E which governs its far field behavior. The perturbative-reductive approach is here performed on well-known nonlinear P{delta}Es, both integrable and nonintegrable. We study the cases of the lattice modified Korteweg-de Vries (mKdV) equation, the Hietarinta equation, the lattice Volterra-Kac-Van Moerbeke equation and a nonintegrable lattice KdV equation. Such reductions allow us to obtain many new P{delta}Es of the nonlinear Schroedinger type.

  14. Financing Class Size Reduction

    ERIC Educational Resources Information Center

    Achilles, C. M.

    2005-01-01

    Class size reduction has been shown to, among other things, improve academic achievement for all students and particularly for low-income and minority students. With the No Child Left Behind Act's heavy emphasis on scientifically based research, adequate yearly progress, and disaggregated results, one wonders why all children aren't enrolled in…

  15. Reduction in Force.

    ERIC Educational Resources Information Center

    Wood, R. Craig

    This chapter of "Principles of School Business Management" reviews several concerns that must be addressed by school business administrators in districts facing declining enrollments and the need for reductions in force. The chapter first looks at the business administrator's significant role in planning for retrenchment. The chapter then…

  16. Reduction in Force.

    ERIC Educational Resources Information Center

    Phay, Robert

    Chapter 2 in a book on school law discusses the reasons for reduction in force (RIF) and presents a set of model regulations for school districts as the best means of minimizing legal problems resulting from RIF. The reasons for RIF include declining student enrollments; reduced turnover among teachers; changes in programs; and more constrained…

  17. Adolescent Prejudice Reduction Conference.

    ERIC Educational Resources Information Center

    Ketroser, Heidi

    1988-01-01

    Discusses the fifth annual Dr. Curtis C. Melnick Adolescent Prejudice Reduction Conference sponsored by the Greater Chicago (Illinois) Regional Office of the Anti-Defamation League of the B'nai B'rith. The day-long conference addressed issues of prejudice and allowed students and staff from various high schools to explore their concerns with…

  18. Exercise and Fat Reduction.

    ERIC Educational Resources Information Center

    Clarke, H. Harrison, Ed.

    1975-01-01

    This document analyzes the problems encountered by the obese individual and the effects of regular exercise on weight loss and fat reduction. Part one compares the psychological traits of obese children with age groups of normal weight and discusses the organic disorders and social attitudes which plague the overweight individual. Part two states…

  19. Hadamard speckle contrast reduction

    NASA Astrophysics Data System (ADS)

    Trisnadi, Jahja I.

    2004-01-01

    The condition for a diffuser to produce the maximum speckle contrast reduction with the minimum number of distinct phase patterns is derived. A binary realization of this optimum diffuser is obtained by mapping the rows or columns of a Hadamard matrix to the phase patterns. The method is experimentally verified in the Grating Light Valve laser projection display.

  20. Industrial Waste Reduction Program

    SciTech Connect

    Not Available

    1991-10-24

    US industry generates over 12 billion tons of wastes each year. These wastes consist of undesirable by-products of industrial production that are discarded into our environment. Energy is an integral part of these wastes; it is found in the embodied energy of industrial feedstocks not optimally used, in the energy content of the wastes themselves, and in the energy needed to transport, treat, and dispose of wastes. Estimates of the potential energy savings from reducing industrial wastes range from three to four quadrillion Btu per year -- enough to meet the annual energy needs of 30 million American homes. This document presents a plan for the Industrial Waste Reduction Program, which has been designed to help achieve national goals for energy efficiency and waste minimization. The objective of the program is to improve the energy efficiency of industrial processes through cost-effective waste reduction. The initial program focus is on waste reduction opportunities in the production and use of chemicals, due to the significant amount of energy used in these activities and the large amounts of hazardous and toxic wastes they generate. The chemical industry will be the initial subject of a series of waste reduction opportunity assessments conducted as part of the program. Assessments of other industries and waste problems will follow.

  1. Nagel on reduction.

    PubMed

    Sarkar, Sahotra

    2015-10-01

    This paper attempts a critical reappraisal of Nagel's (1961, 1970) model of reduction taking into account both traditional criticisms and recent defenses. This model treats reduction as a type of explanation in which a reduced theory is explained by a reducing theory after their relevant representational items have been suitably connected. In accordance with the deductive-nomological model, the explanation is supposed to consist of a logical deduction. Nagel was a pluralist about both the logical form of the connections between the reduced and reducing theories (which could be conditionals or biconditionals) and their epistemological status (as analytic connections, conventions, or synthetic claims). This paper defends Nagel's pluralism on both counts and, in the process, argues that the multiple realizability objection to reductionism is misplaced. It also argues that the Nagel model correctly characterizes reduction as a type of explanation. However, it notes that logical deduction must be replaced by a broader class of inferential techniques that allow for different types of approximation. Whereas Nagel (1970), in contrast to his earlier position (1961), recognized the relevance of approximation, he did not realize its full import for the model. Throughout the paper two case studies are used to illustrate the arguments: the putative reduction of classical thermodynamics to the kinetic theory of matter and that of classical genetics to molecular biology. PMID:26386529

  2. Teaching Reductive Thinking

    ERIC Educational Resources Information Center

    Armoni, Michal; Gal-Ezer, Judith

    2005-01-01

    When dealing with a complex problem, solving it by reduction to simpler problems, or problems for which the solution is already known, is a common method in mathematics and other scientific disciplines, as in computer science and, specifically, in the field of computability. However, when teaching computational models (as part of computability)…

  3. Imino Transfer Hydrogenation Reductions.

    PubMed

    Wills, Martin

    2016-04-01

    This review contains a summary of recent developments in the transfer hydrogenation of C=N bonds, with a particularly focus on reports from within the last 10 years and asymmetric transformations. However, earlier work in the area is also discussed in order to provide context for the more recent results described. I focus strongly on the Ru/TsDPEN class of asymmetric transfer hydrogenation reactions originally reported by Noyori et al., together with examples of their applications, particularly to medically valuable target molecules. The recent developments in the area of highly active imine-reduction catalysts, notably those based on iridium, are also described in some detail. I discuss diastereoselective reduction methods as a route to the synthesis of chiral amines using transfer hydrogenation. The recent development of a methodology for positioning reduction complexes within chiral proteins, permitting the generation of asymmetric reduction products through a directed modification of the protein environment in a controlled manner, is also discussed. PMID:27573139

  4. Injury reduction at Fermilab

    SciTech Connect

    Griffing, Bill; /Fermilab

    2005-06-01

    In a recent DOE Program Review, Fermilab's director presented results of the laboratory's effort to reduce the injury rate over the last decade. The results, shown in the figure below, reveal a consistent and dramatic downward trend in OSHA recordable injuries at Fermilab. The High Energy Physics Program Office has asked Fermilab to report in detail on how the laboratory has achieved the reduction. In fact, the reduction in the injury rate reflects a change in safety culture at Fermilab, which has evolved slowly over this period, due to a series of events, both planned and unplanned. This paper attempts to describe those significant events and analyze how each of them has shaped the safety culture that, in turn, has reduced the rate of injury at Fermilab to its current value.

  5. Bacterial reduction of chromium

    SciTech Connect

    Schmieman, E.A.; Yonge, D.R.; Johnstone, D.L.

    1997-12-31

    A mixed culture was enriched from surface soil obtained from an eastern United States site highly contaminated with chromate. Growth of the culture was inhibited by a chromium concentration of 12 mg/L. Another mixed culture was enriched from subsurface soil obtained from the Hanford reservation, at the fringe of a chromate plume. The enrichment medium was minimal salts solution augmented with acetate as the carbon source, nitrate as the terminal electron acceptor, and various levels of chromate. This mixed culture exhibited chromate tolerance, but not chromate reduction capability, when growing anaerobically on this medium. However, this culture did exhibit chromate reduction capability when growing anaerobically on TSB. Growth of this culture was not inhibited by a chromium concentration of 12 mg/L. Mixed cultures exhibited decreasing diversity with increasing levels of chromate in the enrichment medium. An in situ bioremediation strategy is suggested for chromate contaminated soil and groundwater. 16 refs., 5 figs., 1 tab.

  6. Reduction/Transformation Operators

    SciTech Connect

    Bartlett, Roscoe A.

    2006-09-01

    RTOp (reduction/transformation operators) is a collection of C++ software that provides the basic mechanism for implementinig vector operations in a flexible and efficient manner. This is the main interface utilized by Thyra to allow for the specification of specific vector reduction and/or transformation operations. The RTOp package contains three different types of software. (a) a small number of interoperability interfaces. (b) support software including code for the parallel SPMD mode based on only Teuchos::Comm(and not MPl directly(, and (c) a library of pre-implemented RTOp subclasses for everything from simple AXPYs and norms, to more specialized vector operations. RTOp allows an algorithm developer to implement their own RTOp subclasses in a way that is independent from any specific serial, parallel, out-of-core or other type of vector implementation. RTOp is a required package by Thyra and MOOCHO. (c)

  7. Reduction/Transformation Operators

    Energy Science and Technology Software Center (ESTSC)

    2006-09-01

    RTOp (reduction/transformation operators) is a collection of C++ software that provides the basic mechanism for implementinig vector operations in a flexible and efficient manner. This is the main interface utilized by Thyra to allow for the specification of specific vector reduction and/or transformation operations. The RTOp package contains three different types of software. (a) a small number of interoperability interfaces. (b) support software including code for the parallel SPMD mode based on only Teuchos::Comm(and notmore » MPl directly(, and (c) a library of pre-implemented RTOp subclasses for everything from simple AXPYs and norms, to more specialized vector operations. RTOp allows an algorithm developer to implement their own RTOp subclasses in a way that is independent from any specific serial, parallel, out-of-core or other type of vector implementation. RTOp is a required package by Thyra and MOOCHO. (c)« less

  8. Reduction of astrographic catalogues

    NASA Technical Reports Server (NTRS)

    Stock, J.; Prugna, F. D.; Cova, J.

    1984-01-01

    An automatic program for the reduction of overlapping Carte du Ciel plates is described. The projection and transformation equations are given and the RAA subprogram flow is outlined. The program was applied to two different sets of data, namely to nine overlapping plates of the Cape Zone of the CdC, and to fifteen plates taken with the CIDA-refractor of the open cluster Tr10.

  9. Aluminum reduction cell electrode

    DOEpatents

    Goodnow, Warren H.; Payne, John R.

    1982-01-01

    The invention is directed to cathode modules comprised of refractory hard metal materials, such as TiB.sub.2, for an electrolytic cell for the reduction of alumina wherein the modules may be installed and replaced during operation of the cell and wherein the structure of the cathode modules is such that the refractory hard metal materials are not subjected to externally applied forces or rigid constraints.

  10. Television noise reduction device

    NASA Technical Reports Server (NTRS)

    Gordon, B. L.; Stamps, J. C. (Inventor)

    1975-01-01

    A noise reduction system that divides the color video signal into its luminance and chrominance components is reported. The luminance component of a given frame is summed with the luminance component of at least one preceding frame which was stored on a disc recorder. The summation is carried out so as to achieve a signal amplitude equivalent to that of the original signal. The averaged luminance signal is then recombined with the chrominance signal to achieve a noise-reduced television signal.