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Sample records for amoeba effect

  1. Testing the Effect of Refrigerated Storage on Testate Amoeba Samples.

    Science.gov (United States)

    Mazei, Yuri; Chernyshov, Viktor; Tsyganov, Andrey N; Payne, Richard J

    2015-11-01

    Samples for analysis of testate amoebae and other protists frequently need to be stored for many months before microscopy. This storage commonly involves refrigeration, but we know that testate amoebae can live and reproduce in these conditions. This raises the question: do communities change during storage and how might this effect the data produced? We analysed Sphagnum samples over a 16-week period to address this question. Our results show no evidence for detectable change. This is a reassuring result supporting much current practice although we suggest that frozen storage or the addition of a fixative may be worthwhile precautions where feasible.

  2. Effects of harmful cyanobacteria on the freshwater pathogenic free-living amoeba Acanthamoeba castellanii.

    Science.gov (United States)

    Urrutia-Cordero, Pablo; Agha, Ramsy; Cirés, Samuel; Lezcano, María Ángeles; Sánchez-Contreras, María; Waara, Karl-Otto; Utkilen, Hans; Quesada, Antonio

    2013-04-15

    Grazing is a major regulating factor in cyanobacterial population dynamics and, subsequently, considerable effort has been spent on investigating the effects of cyanotoxins on major metazoan grazers. However, protozoan grazers such as free-living amoebae can also feed efficiently on cyanobacteria, while simultaneously posing a major threat for public health as parasites of humans and potential reservoirs of opportunistic pathogens. In this study, we conducted several experiments in which the freshwater amoeba Acanthamoeba castellanii was exposed to pure microcystin-LR (MC-LR) and six cyanobacterial strains, three MC-producing strains (MC-LR, MC-RR, MC-YR, MC-WR, [Dha7] MC-RR) and three strains containing other oligopeptides such as anabaenopeptins and cyanopeptolins. Although the exposure to high concentrations of pure MC-LR yielded no effects on amoeba, all MC-producing strains inflicted high mortality rates on amoeba populations, suggesting that toxic effects must be mediated through the ingestion of toxic cells. Interestingly, an anabaenopeptin-producing strain caused the greatest inhibition of amoeba growth, indicating that toxic bioactive compounds other than MCs are of great importance for amoebae grazers. Confocal scanning microscopy revealed different alterations in amoeba cytoskeleton integrity and as such, the observed declines in amoeba densities could have indeed been caused via a cascade of cellular events primarily triggered by oligopeptides with protein-phosphatase inhibition capabilities such as MCs or anabaenopeptins. Moreover, inducible-defense mechanisms such as the egestion of toxic, MC-producing cyanobacterial cells and the increase of resting stages (encystation) in amoebae co-cultivated with all cyanobacterial strains were observed in our experiments. Consequently, cyanobacterial strains showed different susceptibilities to amoeba grazing which were possibly influenced by the potentiality of their toxic secondary metabolites. Hence, this

  3. [Effects of dopamine and adenosine on regulation of water-electrolyte exchange in Amoeba proteus].

    Science.gov (United States)

    Bagrov, Ia Iu; Manusova, N B

    2014-01-01

    Dopamine and adenosine both regulate transport of sodium chloride in the renal tubules in mammals. We have studied the effect of dopamine and adenosine on spontaneous activity of contractile vacuole of Amoeba proteous. Both substances stimulated contractile vacuole. The effect of dopamine was suppressed by D2 receptor antagonist, haloperidol, but not by D1 antagonist, SCH 39166. Adenylate cyclase inhibitor, 2.5-dideoxyadenosine, suppressed the effect of dopamine, but not of adenosine. Inhibitor of protein kinase C, staurosporine, in contrast, blocked the effect of adenosine, but not dopamine. Notably, dopamine opposed effect of adenosine and vice versa. These results suggest that similar effects of dopamine and adenosine could be mediated by different intracellulare mechanisms.

  4. Effect of Common Drinking Water Disinfectants, Chlorine and Heat, on Free Legionella and Amoebae-Associated Legionella.

    Science.gov (United States)

    Cervero-Aragó, Sílvia; Rodríguez-Martínez, Sarah; Puertas-Bennasar, Antoni; Araujo, Rosa M

    2015-01-01

    Chlorine and thermal treatments are the most commonly used procedures to control and prevent Legionella proliferation in drinking water systems of large buildings. However, cases of legionellosis still occur in facilities with treated water. The purpose of this work was to model the effect of temperature and free chlorine applied in similar exposure conditions as in drinking water systems on five Legionella spp. strains and two amoebal strains of the genera Acanthamoeba. Inactivation models obtained were used to determine the effectiveness of the treatments applied which resulted more effective against Legionella than Acanthamoeba, especially those in cystic stages. Furthermore, to determine the influence of the relationship between L. pneumophila and Acanthamoeba spp. on the treatment effectiveness, inactivation models of the bacteria-associated amoeba were also constructed and compared to the models obtained for the free living bacteria state. The Legionella-amoeba association did not change the inactivation models, but it reduced the effectiveness of the treatments applied. Remarkably, at the lowest free chlorine concentration, 0.5 mg L-1, as well as at the lowest temperatures, 50°C and 55°C, the influence of the Legionella-amoeba associate state was the strongest in reducing the effectiveness of the treatments compared to the free Legionella state. Therefore, the association established between L. pneumophila and amoebae in the water systems indicate an increased health risk in proximal areas of the system (close to the tap) where lower free chlorine concentrations and lower temperatures are commonly observed.

  5. Effect of Common Drinking Water Disinfectants, Chlorine and Heat, on Free Legionella and Amoebae-Associated Legionella.

    Directory of Open Access Journals (Sweden)

    Sílvia Cervero-Aragó

    Full Text Available Chlorine and thermal treatments are the most commonly used procedures to control and prevent Legionella proliferation in drinking water systems of large buildings. However, cases of legionellosis still occur in facilities with treated water. The purpose of this work was to model the effect of temperature and free chlorine applied in similar exposure conditions as in drinking water systems on five Legionella spp. strains and two amoebal strains of the genera Acanthamoeba. Inactivation models obtained were used to determine the effectiveness of the treatments applied which resulted more effective against Legionella than Acanthamoeba, especially those in cystic stages. Furthermore, to determine the influence of the relationship between L. pneumophila and Acanthamoeba spp. on the treatment effectiveness, inactivation models of the bacteria-associated amoeba were also constructed and compared to the models obtained for the free living bacteria state. The Legionella-amoeba association did not change the inactivation models, but it reduced the effectiveness of the treatments applied. Remarkably, at the lowest free chlorine concentration, 0.5 mg L-1, as well as at the lowest temperatures, 50°C and 55°C, the influence of the Legionella-amoeba associate state was the strongest in reducing the effectiveness of the treatments compared to the free Legionella state. Therefore, the association established between L. pneumophila and amoebae in the water systems indicate an increased health risk in proximal areas of the system (close to the tap where lower free chlorine concentrations and lower temperatures are commonly observed.

  6. Effect of Common Drinking Water Disinfectants, Chlorine and Heat, on Free Legionella and Amoebae-Associated Legionella

    Science.gov (United States)

    Cervero-Aragó, Sílvia; Rodríguez-Martínez, Sarah; Puertas-Bennasar, Antoni; Araujo, Rosa M.

    2015-01-01

    Chlorine and thermal treatments are the most commonly used procedures to control and prevent Legionella proliferation in drinking water systems of large buildings. However, cases of legionellosis still occur in facilities with treated water. The purpose of this work was to model the effect of temperature and free chlorine applied in similar exposure conditions as in drinking water systems on five Legionella spp. strains and two amoebal strains of the genera Acanthamoeba. Inactivation models obtained were used to determine the effectiveness of the treatments applied which resulted more effective against Legionella than Acanthamoeba, especially those in cystic stages. Furthermore, to determine the influence of the relationship between L. pneumophila and Acanthamoeba spp. on the treatment effectiveness, inactivation models of the bacteria-associated amoeba were also constructed and compared to the models obtained for the free living bacteria state. The Legionella-amoeba association did not change the inactivation models, but it reduced the effectiveness of the treatments applied. Remarkably, at the lowest free chlorine concentration, 0.5 mg L-1, as well as at the lowest temperatures, 50°C and 55°C, the influence of the Legionella-amoeba associate state was the strongest in reducing the effectiveness of the treatments compared to the free Legionella state. Therefore, the association established between L. pneumophila and amoebae in the water systems indicate an increased health risk in proximal areas of the system (close to the tap) where lower free chlorine concentrations and lower temperatures are commonly observed. PMID:26241039

  7. Effect of UV irradiation (253.7 nm) on free Legionella and Legionella associated with its amoebae hosts.

    Science.gov (United States)

    Cervero-Aragó, Sílvia; Sommer, Regina; Araujo, Rosa M

    2014-12-15

    Water systems are the primary reservoir for Legionella spp., where the bacteria live in association with other microorganisms, such as free-living amoebae. A wide range of disinfection treatments have been studied to control and prevent Legionella colonization but few of them were performed considering its relation with protozoa. In this study, the effectiveness of UV irradiation (253.7 nm) using low-pressure lamps was investigated as a disinfection method for Legionella and amoebae under controlled laboratory conditions. UV treatments were applied to 5 strains of Legionella spp., 4 strains of free-living amoeba of the genera Acanthamoeba and Vermamoeba, treating separately trophozoites and cysts, and to two different co-cultures of Legionella pneumophila with the Acanthamoeba strains. No significant differences in the UV inactivation behavior were observed among Legionella strains tested which were 3 logs reduced for fluences around 45 J/m(2). UV irradiation was less effective against free-living amoebae; which in some cases required up to 990 J/m(2) to obtain the same population reduction. UV treatment was more effective against trophozoites compared to cysts; moreover, inactivation patterns were clearly different between the genus Acanthamoeba and Vermamoeba. For the first time data about Vermamoeba vermiformis UV inactivation has been reported in a study. Finally, the results showed that the association of L. pneumophila with free-living amoebae decreases the effectiveness of UV irradiation against the bacteria in a range of 1.5-2 fold. That fact demonstrates that the relations established between different microorganisms in the water systems can modify the effectiveness of the UV treatments applied.

  8. Free-living amoebae: Health concerns in the indoor environment

    Energy Technology Data Exchange (ETDEWEB)

    Tyndall, R.L.; Ironside, K.S.

    1990-01-01

    Free-living amoebae are the most likely protozoa implicated in health concerns of the indoor environment. These amoebae can be the source of allergic reactions, eye infections or, on rare occasions, encephalitis. While too large to be effectively aerosolized, free- living amoebae can support the multiplication of pathogens such as Legionella which are easily aerosolized and infectious via the pulmonary route. Traditional detection methods for free-living amoebae are laborious and time consuming. Newer techniques for rapidly detecting and quantitating free-living amoebae such as monoclonal antibodies, flow cytometry, gene probes, and laser optics have or could be employed. 25 refs.

  9. Randomness Of Amoeba Movements

    Science.gov (United States)

    Hashiguchi, S.; Khadijah, Siti; Kuwajima, T.; Ohki, M.; Tacano, M.; Sikula, J.

    2005-11-01

    Movements of amoebas were automatically traced using the difference between two successive frames of the microscopic movie. It was observed that the movements were almost random in that the directions and the magnitudes of the successive two steps are not correlated, and that the distance from the origin was proportional to the square root of the step number.

  10. Endocannabinoids inhibit the growth of free-living amoebae.

    Science.gov (United States)

    Dey, Rafik; Pernin, Pierre; Bodennec, Jacques

    2010-07-01

    The cannabinoid Delta(9)-tetrahydrocannabinol inhibits the growth of some pathogenic amoebae in vitro and exacerbates amoebic encephalitis in animal models. However, the effects of endogenous cannabinoids on amoebae remain unknown. Therefore, we tested several endocannabinoids (N-acyl ethanolamines and 2-O-acyl glycerol) on different genera of amoebae. The results showed that all of the endocannabinoids tested inhibit amoebic growth at subpharmacological doses, with 50% inhibitory concentrations ranging from 15 to 20 microM. A nonhydrolyzable endocannabinoid had similar effects, showing that the inhibition seen results from endocannabinoids per se rather than from a catabolic product.

  11. Deficiency of huntingtin has pleiotropic effects in the social amoeba Dictyostelium discoideum.

    Science.gov (United States)

    Myre, Michael A; Lumsden, Amanda L; Thompson, Morgan N; Wasco, Wilma; MacDonald, Marcy E; Gusella, James F

    2011-04-01

    Huntingtin is a large HEAT repeat protein first identified in humans, where a polyglutamine tract expansion near the amino terminus causes a gain-of-function mechanism that leads to selective neuronal loss in Huntington's disease (HD). Genetic evidence in humans and knock-in mouse models suggests that this gain-of-function involves an increase or deregulation of some aspect of huntingtin's normal function(s), which remains poorly understood. As huntingtin shows evolutionary conservation, a powerful approach to discovering its normal biochemical role(s) is to study the effects caused by its deficiency in a model organism with a short life-cycle that comprises both cellular and multicellular developmental stages. To facilitate studies aimed at detailed knowledge of huntingtin's normal function(s), we generated a null mutant of hd, the HD ortholog in Dictyostelium discoideum. Dictyostelium cells lacking endogenous huntingtin were viable but during development did not exhibit the typical polarized morphology of Dictyostelium cells, streamed poorly to form aggregates by accretion rather than chemotaxis, showed disorganized F-actin staining, exhibited extreme sensitivity to hypoosmotic stress, and failed to form EDTA-resistant cell-cell contacts. Surprisingly, chemotactic streaming could be rescued in the presence of the bivalent cations Ca(2+) or Mg(2+) but not pulses of cAMP. Although hd(-) cells completed development, it was delayed and proceeded asynchronously, producing small fruiting bodies with round, defective spores that germinated spontaneously within a glassy sorus. When developed as chimeras with wild-type cells, hd(-) cells failed to populate the pre-spore region of the slug. In Dictyostelium, huntingtin deficiency is compatible with survival of the organism but renders cells sensitive to low osmolarity, which produces pleiotropic cell autonomous defects that affect cAMP signaling and as a consequence development. Thus, Dictyostelium provides a novel haploid

  12. Deficiency of huntingtin has pleiotropic effects in the social amoeba Dictyostelium discoideum.

    Directory of Open Access Journals (Sweden)

    Michael A Myre

    2011-04-01

    Full Text Available Huntingtin is a large HEAT repeat protein first identified in humans, where a polyglutamine tract expansion near the amino terminus causes a gain-of-function mechanism that leads to selective neuronal loss in Huntington's disease (HD. Genetic evidence in humans and knock-in mouse models suggests that this gain-of-function involves an increase or deregulation of some aspect of huntingtin's normal function(s, which remains poorly understood. As huntingtin shows evolutionary conservation, a powerful approach to discovering its normal biochemical role(s is to study the effects caused by its deficiency in a model organism with a short life-cycle that comprises both cellular and multicellular developmental stages. To facilitate studies aimed at detailed knowledge of huntingtin's normal function(s, we generated a null mutant of hd, the HD ortholog in Dictyostelium discoideum. Dictyostelium cells lacking endogenous huntingtin were viable but during development did not exhibit the typical polarized morphology of Dictyostelium cells, streamed poorly to form aggregates by accretion rather than chemotaxis, showed disorganized F-actin staining, exhibited extreme sensitivity to hypoosmotic stress, and failed to form EDTA-resistant cell-cell contacts. Surprisingly, chemotactic streaming could be rescued in the presence of the bivalent cations Ca(2+ or Mg(2+ but not pulses of cAMP. Although hd(- cells completed development, it was delayed and proceeded asynchronously, producing small fruiting bodies with round, defective spores that germinated spontaneously within a glassy sorus. When developed as chimeras with wild-type cells, hd(- cells failed to populate the pre-spore region of the slug. In Dictyostelium, huntingtin deficiency is compatible with survival of the organism but renders cells sensitive to low osmolarity, which produces pleiotropic cell autonomous defects that affect cAMP signaling and as a consequence development. Thus, Dictyostelium provides a

  13. Amoebas and Instantons

    Science.gov (United States)

    Maeda, Takashi; Nakatsu, Toshio

    We study a statistical model of random plane partitions. The statistical model has interpretations as five-dimensional { N}=1 supersymmetric SU(N) Yang-Mills on ℝ4 × S1 and as Kähler gravity on local SU(N) geometry. At the thermodynamic limit a typical plane partition called the limit shape dominates in the statistical model. The limit shape is linked with a hyperelliptic curve, which is a five-dimensional version of the SU(N) Seiberg-Witten curve. Amoebas and the Ronkin functions play intermediary roles between the limit shape and the hyperelliptic curve. In particular, the Ronkin function realizes an integration of thermodynamical density of the main diagonal partitions, along one-dimensional slice of it and thereby is interpreted as the counting function of gauge instantons. The radius of S1 can be identified with the inverse temperature of the statistical model. The large radius limit of the five-dimensional Yang-Mills is the low temperature limit of the statistical model, where the statistical model is frozen to a ground state that is associated with the local SU(N) geometry. We also show that the low temperature limit corresponds to a certain degeneration of amoebas and the Ronkin functions known as tropical geometry.

  14. Differential Equations for Morphological Amoebas

    Science.gov (United States)

    Welk, Martin; Breuß, Michael; Vogel, Oliver

    This paper is concerned with amoeba median filtering, a structure-adaptive morphological image filter. It has been introduced by Lerallut et al. in a discrete formulation. Experimental evidence shows that iterated amoeba median filtering leads to segmentation-like results that are similar to those obtained by self-snakes, an image filter based on a partial differential equation. We investigate this correspondence by analysing a space-continuous formulation of iterated median filtering. We prove that in the limit of vanishing radius of the structuring elements, iterated amoeba median filtering indeed approximates a partial differential equation related to self-snakes and the well-known (mean) curvature motion equation. We present experiments with discrete iterated amoeba median filtering that confirm qualitative and quantitative predictions of our analysis.

  15. Application of cattle slurry containing Mycobacterium avium subsp. paratuberculosis (MAP) to grassland soil and its effect on the relationship between MAP and free-living amoeba.

    Science.gov (United States)

    Salgado, M; Alfaro, M; Salazar, F; Badilla, X; Troncoso, E; Zambrano, A; González, M; Mitchell, R M; Collins, M T

    2015-01-30

    Slurry from dairy farms is commonly used to fertilize crops and pastures. This mixture of manure, urine and water can harbor multiple microbial pathogens among which Mycobacterium avium subsp. paratuberculosis (MAP) is a major concern. Persistence of MAP in soil and infection of soil Acanthamoeba was evaluated by culture, real-time IS900 PCR, and by staining of amoeba with acid-fast and vital stains comparing soils irrigated with MAP-spiked or control dairy farm slurry. MAP DNA was detected in soil for the 8 month study duration. MAP was detected by PCR from more soil samples for plots receiving MAP-spiked slurry (n=61/66) than from soils receiving control slurry (n=10/66 samples). Vital stains verified that intracellular MAP in amoeba was viable. More MAP was found in amoeba at the end of the study than immediately after slurry application. There was no relationship between MAP presence in soil and in amoeba over time. Infection of amoeba by MAP provides a protected niche for the persistence and even possibly the replication of MAP in soils. As others have suggested, MAP-infected amoeba may act like a "Trojan horse" providing a means for persistence in soils and potentially a source of infection for grazing animals.

  16. Amoebas and Instantons

    CERN Document Server

    Maeda, T; Maeda, Takashi; Nakatsu, Toshio

    2006-01-01

    We study a statistical model of random plane partitions. The statistical model has interpretations as five-dimensional $\\mathcal{N}=1$ supersymmetric SU(N) Yang-Mills on $\\mathbb{R}^4\\times S^1$ and as K\\"ahler gravity on local SU(N) geometry. At the thermodynamic limit a typical plane partition called the limit shape dominates in the statistical model. The limit shape is linked with a hyperelliptic curve, which is a five-dimensional version of the SU(N) Seiberg-Witten curve. Amoebas and the Ronkin functions play intermediary roles between the limit shape and the hyperelliptic curve. In particular, the Ronkin function realizes an integration of thermodynamical density of the main diagonal partitions, along one-dimensional slice of it and thereby is interpreted as the counting function of gauge instantons. The radius of $S^1$ can be identified with the inverse temperature of the statistical model. The large radius limit of the five-dimensional Yang-Mills is the low temperature limit of the statistical model, w...

  17. Effect of thermal additions on the density and distribution of thermophilic amoebae and pathogenic Naegleria fowleri in a newly created cooling lake

    Energy Technology Data Exchange (ETDEWEB)

    Tyndall, R.L.; Ironside, K.S.; Metler, P.L.; Tan, E.L. (Univ. of Tennessee, Knoxville (USA)); Hazen, T.C.; Fliermans, C.B. (E.I. du Pont de Nemours and Co., Inc., Aiken, SC (USA))

    1989-03-01

    Pathogenic Naegleria fowleri is the causative agent of fatal human amoebic meningoencephalitis. The protozoan is ubiquitous in nature, and its presence is enhanced by thermal additions. In this investigation, water and sediments from a newly created cooling lake were quantitatively analyzed for the presence of thermophilic amoebae, thermophilic Naegleria spp., and the pathogen Naegleria fowleri. During periods of thermal additions, the concentrations of thermophilic amoebae and thermophilic Naegleria spp. increased as much as 5 orders of magnitude, and the concentration of the pathogen N. fowleri increased as much as 2 orders of magnitude. Concentrations of amoebae returned to prior thermal perturbation levels within 30 to 60 days after cessation of thermal additions. Increases in the thermophilic amoeba concentrations were noted in Savannah River oxbows downriver from the Savannah River plant discharge streams as compared with oxbows upriver from the discharges. Concentrations of thermophilic amoebae and thermophilic Naegleria spp. correlated significantly with temperature and conductivity. Air samples taken proximal to the lade during periods of thermal addition showed no evidence of thermophilic Naegleria spp. Isoenzyme patterns of the N. fowleri isolated from the cooling lake were identical to patterns of N. fowleri isolated from other sites in the United States and Belgium.

  18. [Testate amoebas of pine forests in Mexico].

    Science.gov (United States)

    Bobrov, A A; Krasil'nikov, P A

    2011-01-01

    The population of testate amoebas in the soils of pine forests in Mexico has been studied. In total, 68 species, varieties, and types of testate amoebas with cosmopolite distribution were found. The species diversity of the testate population includes hygrophilous species that differ from hygrophilous species with luvisols in higher andosols. Comparative analysis using the results of one available study of soil testate amoebas from Mexico has been carried out [Bonnet, 1977].

  19. Evaluating the use of testate amoebae for palaeohydrological reconstruction in permafrost peatlands

    DEFF Research Database (Denmark)

    Swindles, Graeme T.; Amesbury, Matthew J.; Turner, T. Edward;

    2015-01-01

    analysis confirms that water-table depth and moisture content are the dominant controls on the distribution of testate amoebae, corroborating the results from studies in mid-latitude peatlands. We present a new testate amoeba-based water table transfer function and thoroughly test it for the effects......The melting of high-latitude permafrost peatlands is a major concern due to a potential positive feedback on global climate change. We examine the ecology of testate amoebae in permafrost peatlands, based on sites in Sweden (similar to 200 km north of the Arctic Circle). Multivariate statistical...

  20. Free-living amoebae: Biological by-passes in water treatment.

    Science.gov (United States)

    Loret, Jean-François; Greub, Gilbert

    2010-06-01

    Free-living amoebae constitute reservoirs for many bacteria including not only well-known pathogens but also emerging pathogens responsible for respiratory diseases, and contribute to the protection, survival and dissemination of these bacteria in water systems, despite the application of disinfection or thermal treatments. In this article we review the available information on the presence of free-living amoebae and amoebae-resisting bacteria in drinking water systems, on the factors that contribute to their presence in the water and/or the biofilms, on the possible control measures and their effectiveness, and we identify some gaps in current knowledge needing further research.

  1. Microorganisms resistant to free-living amoebae.

    Science.gov (United States)

    Greub, Gilbert; Raoult, Didier

    2004-04-01

    Free-living amoebae feed on bacteria, fungi, and algae. However, some microorganisms have evolved to become resistant to these protists. These amoeba-resistant microorganisms include established pathogens, such as Cryptococcus neoformans, Legionella spp., Chlamydophila pneumoniae, Mycobacterium avium, Listeria monocytogenes, Pseudomonas aeruginosa, and Francisella tularensis, and emerging pathogens, such as Bosea spp., Simkania negevensis, Parachlamydia acanthamoebae, and Legionella-like amoebal pathogens. Some of these amoeba-resistant bacteria (ARB) are lytic for their amoebal host, while others are considered endosymbionts, since a stable host-parasite ratio is maintained. Free-living amoebae represent an important reservoir of ARB and may, while encysted, protect the internalized bacteria from chlorine and other biocides. Free-living amoebae may act as a Trojan horse, bringing hidden ARB within the human "Troy," and may produce vesicles filled with ARB, increasing their transmission potential. Free-living amoebae may also play a role in the selection of virulence traits and in adaptation to survival in macrophages. Thus, intra-amoebal growth was found to enhance virulence, and similar mechanisms seem to be implicated in the survival of ARB in response to both amoebae and macrophages. Moreover, free-living amoebae represent a useful tool for the culture of some intracellular bacteria and new bacterial species that might be potential emerging pathogens.

  2. [Cultivation of pathogenic free-living amoebae].

    Science.gov (United States)

    Peng, Heng; Zhu, Huai-Min

    2009-08-01

    The isolation and culture of pathogenic free-living amoebae are useful in the diagnosis and research. This review focuses on the methods of isolation and cultivation of pathogenic free-living amoebae, including sample treatment, culture conditions, passage culture, pathogen detection, and maintenance.

  3. Amoebas and coamoebas of linear spaces

    CERN Document Server

    Nisse, Mounir

    2012-01-01

    We give a complete description of the amoebas and coamoebas of $k$-dimensional affine linear spaces in $(\\mathbb{C}^*)^{n}$. We give a lower and an upper bounds of their dimension. and we show that if a $k$-dimensional affine linear space in $(\\mathbb{C}^*)^{n}$ is generic, then the dimension of its (co)amoeba is equal to $\\min \\{2k, n\\}$. We also prove that the volume of its coamoeba is equal $\\pi^{2k}$. Moreover, if the space is real then the volume of its amoeba is equal to $\\frac{\\pi^{2k}}{2^k}$.

  4. On the Volume of Complex Amoebas

    CERN Document Server

    Madani, Farid

    2011-01-01

    The paper deals with amoebas of $k$-dimensional algebraic varieties in the algebraic complex torus of dimension $n\\geq 2k$. First, we show that the area of complex algebraic curve amoebas is finite. Moreover, we give an estimate of this area in the rational curve case in terms of the degree of the rational parametrization coordinates. We also show that the volume of the amoeba of $k$-dimensional algebraic variety in $(\\mathbb{C}^*)^{n}$, with $n\\geq 2k$, is finite.

  5. On the curvature of the real amoeba

    CERN Document Server

    Passare, Mikael

    2011-01-01

    For a real smooth algebraic curve $A \\subset (\\mathhbb{C}^*)^2$, the amoeba $\\mathcal{A} \\subset \\mathbb{R}^2$ is the image of $A$ under the map Log : $(x,y) \\mapsto (\\log |x|, \\log | y |)$. We describe an universal bound for the total curvature of the real amoeba $\\mathcal{A}_{\\mathbb{R} A}$ and we prove that this bound is reached if and only if the curve $A$ is a simple Harnack curve in the sense of Mikhalkin.

  6. Edge detection based on morphological amoebas

    CERN Document Server

    Lee, Won Yeol; Kim, Se Yun; Lim, Jae Young; Lim, Dong Hoon

    2011-01-01

    Detecting the edges of objects within images is critical for quality image processing. We present an edge-detecting technique that uses morphological amoebas that adjust their shape based on variation in image contours. We evaluate the method both quantitatively and qualitatively for edge detection of images, and compare it to classic morphological methods. Our amoeba-based edge-detection system performed better than the classic edge detectors.

  7. Amoebae and Legionella pneumophila in saline environments

    OpenAIRE

    Gast, Rebecca J.; Moran, Dawn M.; Dennett, Mark R.; Wurtsbaugh, Wayne A.; Amaral- Zettler, Linda A.

    2011-01-01

    Amoeboid protists that harbor bacterial pathogens are of significant interest as potential reservoirs of disease-causing organisms in the environment, but little is known about them in marine and other saline environments. We enriched amoeba cultures from sediments from four sites in the New England estuarine system of Mt. Hope Bay, Massachusetts and from sediments from six sites in the Great Salt Lake, Utah. Cultures of amoebae were enriched using both minimal- and non-nutrient agar plates, ...

  8. The cyclic AMP phosphodiesterase RegA critically regulates encystation in social and pathogenic amoebas.

    Science.gov (United States)

    Du, Qingyou; Schilde, Christina; Birgersson, Elin; Chen, Zhi-hui; McElroy, Stuart; Schaap, Pauline

    2014-02-01

    Amoebas survive environmental stress by differentiating into encapsulated cysts. As cysts, pathogenic amoebas resist antibiotics, which particularly counteracts treatment of vision-destroying Acanthamoeba keratitis. Limited genetic tractability of amoeba pathogens has left their encystation mechanisms unexplored. The social amoeba Dictyostelium discoideum forms spores in multicellular fruiting bodies to survive starvation, while other dictyostelids, such as Polysphondylium pallidum can additionally encyst as single cells. Sporulation is induced by cAMP acting on PKA, with the cAMP phosphodiesterase RegA critically regulating cAMP levels. We show here that RegA is deeply conserved in social and pathogenic amoebas and that deletion of the RegA gene in P. pallidum causes precocious encystation and prevents cyst germination. We heterologously expressed and characterized Acanthamoeba RegA and performed a compound screen to identify RegA inhibitors. Two effective inhibitors increased cAMP levels and triggered Acanthamoeba encystation. Our results show that RegA critically regulates Amoebozoan encystation and that components of the cAMP signalling pathway could be effective targets for therapeutic intervention with encystation.

  9. Amoebas of Complex Hypersurfaces in Statistical Thermodynamics

    Science.gov (United States)

    Passare, Mikael; Pochekutov, Dmitry; Tsikh, August

    2013-03-01

    The amoeba of a complex hypersurface is its image under the logarithmic projection. A number of properties of algebraic hypersurface amoebas are carried over to the case of transcendental hypersurfaces. We demonstrate the potential that amoebas can bring into statistical physics by considering the problem of energy distribution in a quantum thermodynamic ensemble. The spectrum \\{\\varepsilon_k\\}subset {Z}^n of the ensemble is assumed to be multidimensional; this leads us to the notions of multidimensional temperature and a vector of differential thermodynamic forms. Strictly speaking, in the paper we develop the multidimensional Darwin-Fowler method and give the description of the domain of admissible average values of energy for which the thermodynamic limit exists.

  10. Amoebas of Complex Hypersurfaces in Statistical Thermodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Passare, Mikael [Stockholm University, Department of Mathematics (Sweden); Pochekutov, Dmitry, E-mail: potchekutov@gmail.com [Siberian Federal University, Institute of Core Undergraduate Programmes (Russian Federation); Tsikh, August, E-mail: atsikh@sfu-kras.ru [Siberian Federal University, Institute of Mathematics (Russian Federation)

    2013-03-15

    The amoeba of a complex hypersurface is its image under the logarithmic projection. A number of properties of algebraic hypersurface amoebas are carried over to the case of transcendental hypersurfaces. We demonstrate the potential that amoebas can bring into statistical physics by considering the problem of energy distribution in a quantum thermodynamic ensemble. The spectrum {l_brace}{epsilon}{sub k}{r_brace} Subset-Of Z{sup n} of the ensemble is assumed to be multidimensional; this leads us to the notions of multidimensional temperature and a vector of differential thermodynamic forms. Strictly speaking, in the paper we develop the multidimensional Darwin-Fowler method and give the description of the domain of admissible average values of energy for which the thermodynamic limit exists.

  11. Amoebas of complex hypersurfaces in statistical thermodynamics

    CERN Document Server

    Passare, Mikael; Tsikh, August

    2011-01-01

    The amoeba of a complex hypersurface is its image under a logarithmic projection. A number of properties of algebraic hypersurface amoebas are carried over to the case of transcendental hypersurfaces. We demonstrate the potential that amoebas can bring into statistical physics by considering the problem of energy distribution in a quantum thermodynamic ensemble. The spectrum ${\\epsilon_k}\\subset \\mathbb{Z}^n$ of the ensemble is assumed to be multidimensional; this leads us to the notions of a multidimensional temperature and a vector of differential thermodynamic forms. Strictly speaking, in the paper we develop the multidimensional Darwin and Fowler method and give the description of the domain of admissible average values of energy for which the thermodynamic limit exists.

  12. Loss of Cln3 function in the social amoeba Dictyostelium discoideum causes pleiotropic effects that are rescued by human CLN3.

    Science.gov (United States)

    Huber, Robert J; Myre, Michael A; Cotman, Susan L

    2014-01-01

    The neuronal ceroid lipofuscinoses (NCL) are a group of inherited, severe neurodegenerative disorders also known as Batten disease. Juvenile NCL (JNCL) is caused by recessive loss-of-function mutations in CLN3, which encodes a transmembrane protein that regulates endocytic pathway trafficking, though its primary function is not yet known. The social amoeba Dictyostelium discoideum is increasingly utilized for neurological disease research and is particularly suited for investigation of protein function in trafficking. Therefore, here we establish new overexpression and knockout Dictyostelium cell lines for JNCL research. Dictyostelium Cln3 fused to GFP localized to the contractile vacuole system and to compartments of the endocytic pathway. cln3- cells displayed increased rates of proliferation and an associated reduction in the extracellular levels and cleavage of the autocrine proliferation repressor, AprA. Mid- and late development of cln3- cells was precocious and cln3- slugs displayed increased migration. Expression of either Dictyostelium Cln3 or human CLN3 in cln3- cells suppressed the precocious development and aberrant slug migration, which were also suppressed by calcium chelation. Taken together, our results show that Cln3 is a pleiotropic protein that negatively regulates proliferation and development in Dictyostelium. This new model system, which allows for the study of Cln3 function in both single cells and a multicellular organism, together with the observation that expression of human CLN3 restores abnormalities in Dictyostelium cln3- cells, strongly supports the use of this new model for JNCL research. PMID:25330233

  13. Loss of Cln3 function in the social amoeba Dictyostelium discoideum causes pleiotropic effects that are rescued by human CLN3.

    Directory of Open Access Journals (Sweden)

    Robert J Huber

    Full Text Available The neuronal ceroid lipofuscinoses (NCL are a group of inherited, severe neurodegenerative disorders also known as Batten disease. Juvenile NCL (JNCL is caused by recessive loss-of-function mutations in CLN3, which encodes a transmembrane protein that regulates endocytic pathway trafficking, though its primary function is not yet known. The social amoeba Dictyostelium discoideum is increasingly utilized for neurological disease research and is particularly suited for investigation of protein function in trafficking. Therefore, here we establish new overexpression and knockout Dictyostelium cell lines for JNCL research. Dictyostelium Cln3 fused to GFP localized to the contractile vacuole system and to compartments of the endocytic pathway. cln3- cells displayed increased rates of proliferation and an associated reduction in the extracellular levels and cleavage of the autocrine proliferation repressor, AprA. Mid- and late development of cln3- cells was precocious and cln3- slugs displayed increased migration. Expression of either Dictyostelium Cln3 or human CLN3 in cln3- cells suppressed the precocious development and aberrant slug migration, which were also suppressed by calcium chelation. Taken together, our results show that Cln3 is a pleiotropic protein that negatively regulates proliferation and development in Dictyostelium. This new model system, which allows for the study of Cln3 function in both single cells and a multicellular organism, together with the observation that expression of human CLN3 restores abnormalities in Dictyostelium cln3- cells, strongly supports the use of this new model for JNCL research.

  14. Burkholderia bacteria infectiously induce the proto-farming symbiosis of Dictyostelium amoebae and food bacteria.

    Science.gov (United States)

    DiSalvo, Susanne; Haselkorn, Tamara S; Bashir, Usman; Jimenez, Daniela; Brock, Debra A; Queller, David C; Strassmann, Joan E

    2015-09-01

    Symbiotic associations can allow an organism to acquire novel traits by accessing the genetic repertoire of its partner. In the Dictyostelium discoideum farming symbiosis, certain amoebas (termed "farmers") stably associate with bacterial partners. Farmers can suffer a reproductive cost but also gain beneficial capabilities, such as carriage of bacterial food (proto-farming) and defense against competitors. Farming status previously has been attributed to amoeba genotype, but the role of bacterial partners in its induction has not been examined. Here, we explore the role of bacterial associates in the initiation, maintenance, and phenotypic effects of the farming symbiosis. We demonstrate that two clades of farmer-associated Burkholderia isolates colonize D. discoideum nonfarmers and infectiously endow them with farmer-like characteristics, indicating that Burkholderia symbionts are a major driver of the farming phenomenon. Under food-rich conditions, Burkholderia-colonized amoebas produce fewer spores than uncolonized counterparts, with the severity of this reduction being dependent on the Burkholderia colonizer. However, the induction of food carriage by Burkholderia colonization may be considered a conditionally adaptive trait because it can confer an advantage to the amoeba host when grown in food-limiting conditions. We observed Burkholderia inside and outside colonized D. discoideum spores after fruiting body formation; this observation, together with the ability of Burkholderia to colonize new amoebas, suggests a mixed mode of symbiont transmission. These results change our understanding of the D. discoideum farming symbiosis by establishing that the bacterial partner, Burkholderia, is an important causative agent of the farming phenomenon.

  15. Evaluating Parametrization Protocols for Hydration Free Energy Calculations with the AMOEBA Polarizable Force Field.

    Science.gov (United States)

    Bradshaw, Richard T; Essex, Jonathan W

    2016-08-01

    Hydration free energy (HFE) calculations are often used to assess the performance of biomolecular force fields and the quality of assigned parameters. The AMOEBA polarizable force field moves beyond traditional pairwise additive models of electrostatics and may be expected to improve upon predictions of thermodynamic quantities such as HFEs over and above fixed-point-charge models. The recent SAMPL4 challenge evaluated the AMOEBA polarizable force field in this regard but showed substantially worse results than those using the fixed-point-charge GAFF model. Starting with a set of automatically generated AMOEBA parameters for the SAMPL4 data set, we evaluate the cumulative effects of a series of incremental improvements in parametrization protocol, including both solute and solvent model changes. Ultimately, the optimized AMOEBA parameters give a set of results that are not statistically significantly different from those of GAFF in terms of signed and unsigned error metrics. This allows us to propose a number of guidelines for new molecule parameter derivation with AMOEBA, which we expect to have benefits for a range of biomolecular simulation applications such as protein-ligand binding studies.

  16. Proteases from Entamoeba spp. and Pathogenic Free-Living Amoebae as Virulence Factors

    Directory of Open Access Journals (Sweden)

    Jesús Serrano-Luna

    2013-01-01

    Full Text Available The standard reference for pathogenic and nonpathogenic amoebae is the human parasite Entamoeba histolytica; a direct correlation between virulence and protease expression has been demonstrated for this amoeba. Traditionally, proteases are considered virulence factors, including those that produce cytopathic effects in the host or that have been implicated in manipulating the immune response. Here, we expand the scope to other amoebae, including less-pathogenic Entamoeba species and highly pathogenic free-living amoebae. In this paper, proteases that affect mucin, extracellular matrix, immune system components, and diverse tissues and cells are included, based on studies in amoebic cultures and animal models. We also include proteases used by amoebae to degrade iron-containing proteins because iron scavenger capacity is currently considered a virulence factor for pathogens. In addition, proteases that have a role in adhesion and encystation, which are essential for establishing and transmitting infection, are discussed. The study of proteases and their specific inhibitors is relevant to the search for new therapeutic targets and to increase the power of drugs used to treat the diseases caused by these complex microorganisms.

  17. Proteases from Entamoeba spp. and Pathogenic Free-Living Amoebae as Virulence Factors.

    Science.gov (United States)

    Serrano-Luna, Jesús; Piña-Vázquez, Carolina; Reyes-López, Magda; Ortiz-Estrada, Guillermo; de la Garza, Mireya

    2013-01-01

    The standard reference for pathogenic and nonpathogenic amoebae is the human parasite Entamoeba histolytica; a direct correlation between virulence and protease expression has been demonstrated for this amoeba. Traditionally, proteases are considered virulence factors, including those that produce cytopathic effects in the host or that have been implicated in manipulating the immune response. Here, we expand the scope to other amoebae, including less-pathogenic Entamoeba species and highly pathogenic free-living amoebae. In this paper, proteases that affect mucin, extracellular matrix, immune system components, and diverse tissues and cells are included, based on studies in amoebic cultures and animal models. We also include proteases used by amoebae to degrade iron-containing proteins because iron scavenger capacity is currently considered a virulence factor for pathogens. In addition, proteases that have a role in adhesion and encystation, which are essential for establishing and transmitting infection, are discussed. The study of proteases and their specific inhibitors is relevant to the search for new therapeutic targets and to increase the power of drugs used to treat the diseases caused by these complex microorganisms.

  18. Co-incubation of Acanthamoeba castellanii with strains of Pseudomonas aeruginosa alters the survival of amoeba.

    Science.gov (United States)

    Cengiz, A M; Harmis, N; Stapleton, F

    2000-06-01

    Enhanced survival of Acanthamoeba castellanii has previously been reported following co-incubation with a single strain of Pseudomonas aeruginosa. The aim of this study was to evaluate the impact of different strains of P. aeruginosa on amoebae survival. Four contact lens solutions were challenged with A. castellanii for between 6 and 24 h, and survival rates of amoeba were calculated. Subsequently, A. castellanii was co-incubated with different strains of P. aeruginosa (strain 6294, an invasive isolate; 6206, a cytotoxic isolate; and Paer 001, a null isolate). Differences in amoeba survival over time between solutions for each bacterial strain were analysed. Non-neutralized hydrogen peroxide was the most effective system against A. castellani at all time points (P<0.05). Survival rates were not different between multipurpose solutions and neutralized hydrogen peroxide. Co-incubation with P. aeruginosa altered amoeba survival, and maximum survival occurred in the presence of the invasive strain of P. aeruginosa. Enhanced amoeba survival may occur in the presence of certain strains of Gram-negative bacteria, and with certain types of contact lens disinfection systems.

  19. Pathogenic amoebae in power-plant cooling lakes. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Tyndall, R.L.; Willaert, E.; Stevens, A.R.

    1981-06-01

    Cooling waters and associated algae and sediments from four northern and four southern/western electric power plants were tested for the presence of pathogenic amoebae. Unheated control waters and algae/sediments from four northern and five southern/western sites were also tested. When comparing results from the test versus control sites, a significantly higher proportion (P less than or equal to 0.05) of the samples from the test sites were positive for thermophilic amoeba, thermophilic Naegleria and pathogenic Naegleria. The difference in number of samples positive for thermophilic Naegleria between heated and unheated waters, however, was attributable predominantly to the northern waters and algae/sediments. While two of four northern test sites yielded pathogenic Naegleria, seven of the eight isolates were obtained from one site. Seasonality effects relative to the isolation of the pathogen were also noted at this site. One pathogen was isolated from a southwestern test site. Pathogens were not isolated from any control sites. Some of the pathogenic isolates were analyzed serologically and classified as pathogenic Naegleria fowleri. Salinity, pH, conductivity, and bacteriological profiles did not obviously correlate with the presence or absence of pathogenic Naegleria. While thermal addition was significantly associated with the presence of thermophilic Naegleria (P less than or equal to 0.05), the data implicate other as yet undefined parameters associated with the presence of the pathogenic thermophile. Until further delineation of these parameters is effected, generalizations cannot be made concerning the effect of thermal impact on the growth of pathogenic amoeba in a particular cooling system.

  20. Experiences with the Amoeba distributed operating system

    NARCIS (Netherlands)

    Tanenbaum, Andrew S.; Renesse, van Robbert; Staveren, van Hans; Sharp, Gregory J.; Mullender, Sape J.; Jansen, Jack; Rossum, van Guido

    1990-01-01

    The Amoeba project is a research effort aimed at understanding how to connect multiple computers in a seamless way [16, 17, 26, 27, 31]. The basic idea is to provide the users with the illusion of a single powerful timesharing system, when, in fact, the system is implemented on a collection of machi

  1. Amoebas of genus at most one

    CERN Document Server

    Theobald, Thorsten

    2011-01-01

    The amoeba of a Laurent polynomial $f \\in \\C[z_1^{\\pm 1},..., z_n^{\\pm 1}]$ is the image of its zero set $\\mathcal{V}(f)$ under the Log-map. Understanding the configuration space of amoebas (i.e., the decomposition of the space of all polynomials, say, with given support or Newton polytope, with regard to the existing complement components) is a widely open problem. In this paper we investigate the class of polynomials $f$ whose Newton polytope $\\New(f)$ is a simplex and whose support $A$ contains exactly one point in the interior of $\\New(f)$. Amoebas of polynomials in this class may have at most one bounded complement component. We provide various results on the configuration space of these amoebas. In particular, we give upper and lower bounds in terms of the coefficients of $f$ for the existence of this complement component and show that the upper bound becomes sharp under some extremal condition. We establish connections from our bounds to Purbhoo's lopsidedness criterion and to the theory of $A$-discrim...

  2. Streaming instability of aggregating slime mold amoebae

    Science.gov (United States)

    Levine, Herbert; Reynolds, William

    1991-05-01

    We propose a new model of aggregation in the cellular slime mold D. Discoideum. Our approach couples the excitable signaling system to amoeba chemotaxis; the resultant system of equations is tractable to analytical and numerical approaches. Using our model, we derive the existence of a streaming instability for the concentric target aggregation pattern.

  3. Seasonal distribution of air-borne pathogenic and free-living amoebae in Mexico City and its suburbs

    Energy Technology Data Exchange (ETDEWEB)

    Rivera, F.; Bonilla, P.; Ramirez, E.; Calderon, A.; Gallegos, E.; Rodriguez, S.; Ortiz, R.; Hernandez, D.; Rivera, V. (ENEP-Iztacala, Tlalnepantla (Mexico). Lab. of Environmental Microbiology)

    1994-03-01

    A survey was carried out over a one-year period to isolate amoebae suspended in the air of Mexico City and its suburbs. Sampling stations were placed at the four cardinal points of the metropolitan area. Selective media were used to culture the amoebae isolated. Specialized taxonomic keys and physical and physiological tests were used for identification, and a statistical analysis was performed to determine the correlations between physico-chemical and biological parameters. 108 strains were isolated, of which 19 were pathogenic via intracerebral inoculation and 9 via intranasal inoculation. Species of the genera Acanthamoeba, Vahlkampfia and Hartmannella were most abundant. Acanthamoeba polyphaga showed the highest abundance. Several times during the period of the study SO[sub 2], O[sub 3], CO NO and NO[sub 2] exceeded the permissible levels established by the Mexican government. The ability of amoebae to form cysts and cyst size were important factors for their presence, survival, abundance and diversity in the atmosphere. The main source of air-borne amoebae was the soil. Factors that favored the incidence and diversity of the isolates were wind speed and direction, low relative humidity, generation of frequent dust-storms, resuspension of amoebae by vehicular traffic, proximity to garbage dumps and large extensions of bare soil. Soil cover was a factor associated with a reduction in the incidence and diversity of the aerial amoebae. This study demonstrates that there are viable cysts of amoebae in the atmosphere of Mexico City, that may have potential importance in the case of certain kinds of human allergies and diseases. Further research is needed to find out the aerial presence of viable cysts of obligatory, amphizoic or opportunistic amoebic parasites, and to clarify the qualitative and quantitative effects of the local meteorological and physico-chemical environment on the free-living amoebae present in the atmosphere. 48 refs., 11 figs., 4 tabs.

  4. Approximating amoebas and coamoebas by sums of squares

    CERN Document Server

    Theobald, Thorsten

    2011-01-01

    Amoebas and coamoebas are the logarithmic images of algebraic varieties and the images of algebraic varieties under the arg-map, respectively. We present new techniques for computational problems on amoebas and coamoebas, thus establishing new connections between (co-)amoebas, semialgebraic and convex algebraic geometry and semidefinite programming. Our approach is based on formulating the membership problem in amoebas (respectively coamoebas) as a suitable real algebraic feasibility problem. Using the real Nullstellensatz, this allows to tackle the problem by sums of squares techniques and semidefinite programming. Our method yields polynomial identities as certificates of non-containedness of a point in an amoeba or comaoeba. As main theoretical result, we establish some degree bounds on the polynomial certificates. Moreover, we provide some actual computations of amoebas based on the sums of squares approach.

  5. Analytic varieties with finite volume amoebas are algebraic

    CERN Document Server

    Madani, Farid

    2011-01-01

    In this paper, we study the amoeba volume of a given $k-$dimensional generic analytic variety $V$ of the complex algebraic torus $(\\C^*)^n$. When $n\\geq 2k$, we show that $V$ is algebraic if and only if the volume of its amoeba is finite. In this precise case, we establish a comparison theorem for the volume of the amoeba and the coamoeba. Examples and applications to the $k-$linear spaces will be given.

  6. Evaluation of AMOEBA: a spectral-spatial classification method

    Science.gov (United States)

    Jenson, Susan K.; Loveland, Thomas R.; Bryant, J.

    1982-01-01

    Muitispectral remotely sensed images have been treated as arbitrary multivariate spectral data for purposes of clustering and classifying. However, the spatial properties of image data can also be exploited. AMOEBA is a clustering and classification method that is based on a spatially derived model for image data. In an evaluation test, Landsat data were classified with both AMOEBA and a widely used spectral classifier. The test showed that irrigated crop types can be classified as accurately with the AMOEBA method as with the generally used spectral method ISOCLS; the AMOEBA method, however, requires less computer time.

  7. Combinatorial Optimization by Amoeba-Based Neurocomputer with Chaotic Dynamics

    Science.gov (United States)

    Aono, Masashi; Hirata, Yoshito; Hara, Masahiko; Aihara, Kazuyuki

    We demonstrate a computing system based on an amoeba of a true slime mold Physarum capable of producing rich spatiotemporal oscillatory behavior. Our system operates as a neurocomputer because an optical feedback control in accordance with a recurrent neural network algorithm leads the amoeba's photosensitive branches to search for a stable configuration concurrently. We show our system's capability of solving the traveling salesman problem. Furthermore, we apply various types of nonlinear time series analysis to the amoeba's oscillatory behavior in the problem-solving process. The results suggest that an individual amoeba might be characterized as a set of coupled chaotic oscillators.

  8. Pack hunting by a common soil amoeba on nematodes.

    Science.gov (United States)

    Geisen, Stefan; Rosengarten, Jamila; Koller, Robert; Mulder, Christian; Urich, Tim; Bonkowski, Michael

    2015-11-01

    Soils host the most complex communities on Earth, including the most diverse and abundant eukaryotes, i.e. heterotrophic protists. Protists are generally considered as bacterivores, but evidence for negative interactions with nematodes both from laboratory and field studies exist. However, direct impacts of protists on nematodes remain unknown. We isolated the soil-borne testate amoeba Cryptodifflugia operculata and found a highly specialized and effective pack-hunting strategy to prey on bacterivorous nematodes. Enhanced reproduction in presence of prey nematodes suggests a beneficial predatory life history of these omnivorous soil amoebae. Cryptodifflugia operculata appears to selectively impact the nematode community composition as reductions of nematode numbers were species specific. Furthermore, we investigated 12 soil metatranscriptomes from five distinct locations throughout Europe for 18S ribosomal RNA transcripts of C. operculata. The presence of C. operculata transcripts in all samples, representing up to 4% of the active protist community, indicates a potential ecological importance of nematophagy performed by C. operculata in soil food webs. The unique pack-hunting strategy on nematodes that was previously unknown from protists, together with molecular evidence that these pack hunters are likely to be abundant and widespread in soils, imply a considerable importance of the hitherto neglected trophic link 'nematophagous protists' in soil food webs.

  9. Intersecting Solitons, Amoeba and Tropical Geometry

    CERN Document Server

    Fujimori, Toshiaki; Ohta, Kazutoshi; Sakai, Norisuke; Yamazaki, Masahito

    2008-01-01

    We study generic intersection (or web) of vortices with instantons inside, which is a 1/4 BPS state in the Higgs phase of five-dimensional N=1 supersymmetric U(Nc) gauge theory on R_t \\times (C^\\ast)^2 \\simeq R^{2,1} \\times T^2 with Nf=Nc Higgs scalars in the fundamental representation. In the case of the Abelian-Higgs model (Nf=Nc=1), the intersecting vortex sheets can be beautifully understood in a mathematical framework of amoeba and tropical geometry, and we propose a dictionary relating solitons and gauge theory to amoeba and tropical geometry. A projective shape of vortex sheets is described by the amoeba. Vortex charge density is uniformly distributed among vortex sheets, and negative contribution to instanton charge density is understood as the complex Monge-Ampere measure with respect to a plurisubharmonic function on (C^\\ast)^2. The Wilson loops in T^2 are related with derivatives of the Ronkin function. The general form of the Kahler potential and the asymptotic metric of the moduli space of a vort...

  10. [Free-living amoebae as vehicles of pathogenic bacteria].

    Science.gov (United States)

    Derda, Monika; Sułek-Stankiewicz, Anna; Hadaś, Edward

    2006-01-01

    The free-living amoebae are ubiquitous organisms. They are found in humid soil and all water reservoirs, i.e. fresh, sea, freezing and hot water. They mainly feed on bacteria. Pathogenic properties of amoebae and the mechanisms underlying pathological changes induced during human infection have not yet been fully elucidated. They are the causative agents of primary amoebic meningo-encephalitis (PAM), granulomatous amebic encephalitis (GAE), a chronic progressive disease of the central nervous system, amebic keratitis (AK), a chronic eye infection; amebic pneumitis (AP), a chronic lung infection, and skin infection. Only a few isolates are strongly and permanently pathogenic to humans. Some isolates lose their pathogenic properties after one passage. It has been assumed that such "temporary", unstable pathogenic properties of the amoebae may be caused by internal factors carried by them. It is generally known that the free-living amoebae may be naturally infected with pathogenic bacteria, which have the ability to survive for a long time and to proliferate in the amoebae cells. The role of the amoeba in the process of maintaining, propagating and transmitting human pathogens has not been well recognized. It has been suggested that some infections can be acquired by inhaling aerosols containing amoebae cells filled with bacteria. The presence of bacteria inside the free-living amoebae possess a great challenge to organisations responsible for testing and inspecting the quality and cleanliness of surface waters, swimming pools and drinking water intakes.

  11. Sucker-like structures on the pathogenic amoeba Naegleria fowleri.

    OpenAIRE

    John, D T; Cole, T B; Marciano-Cabral, F M

    1984-01-01

    Using scanning electron microscopy, we observed sucker-like structures on amoebae of 13 human isolates of Naegleria fowleri. The number of suckers per amoeba seemed to vary according to the virulence of the strain. We propose the term amoebastome to describe this unique sucker-like structure of N. fowleri.

  12. Sucker-like structures on the pathogenic amoeba Naegleria fowleri.

    Science.gov (United States)

    John, D T; Cole, T B; Marciano-Cabral, F M

    1984-01-01

    Using scanning electron microscopy, we observed sucker-like structures on amoebae of 13 human isolates of Naegleria fowleri. The number of suckers per amoeba seemed to vary according to the virulence of the strain. We propose the term amoebastome to describe this unique sucker-like structure of N. fowleri. Images PMID:6696410

  13. Cocultivation of Legionella pneumophila and free-living amoebae

    Energy Technology Data Exchange (ETDEWEB)

    Tyndall, R.L.; Domingue, E.L.

    1982-10-01

    Studies of the interaction of Legionella pneumophila with free-living amoebae showed that Naegleria lovaniensis and Acanthamoeba royreba could use L. pneumophia as a sole food source. However, growth of the amoebae on nonnutrient agar plates seeded with L. pneumophila was slower than growth on nonnutrient agar plates seeded with Escherichia coli. On inoculation of L. pneumophila into axenic cultures of N. lovaniensis and A. roryba, 99.9% of the L. pneumophila was destroyed within 24 h. After several weeks, however, some amoeba cultures became chronically infected and supported the growth of L. pneumophila. Amoebae exposed to L. pneumophila and containing adhered L. pneumophila, L. pneumophila antigens, or both, showed no increased pathogenic potential on intranasal inoculation of weanling mice. Similarly, L. pneumophila propagated in chronically infected amoeba cultures showed no increase in virulence on intraperitoneal inoculation of guinea pigs relative to L. pneumophila grown in yeast extract broth. 20 references, 1 figure, 4 tables.

  14. Free-living amoebae, Legionella and Mycobacterium in tap water supplied by a municipal drinking water utility in the USA.

    Science.gov (United States)

    Marciano-Cabral, Francine; Jamerson, Melissa; Kaneshiro, Edna S

    2010-03-01

    Legionella and Mycobacterium can proliferate within free-living amoebae (FLA) where they are protected from disinfectants at concentrations that can kill bacteria but not protozoa. Despite effective treatment of drinking water, microbes can enter water utility distribution systems (DS) and hence the plumbing within building premises. Additionally, biofilm formation may account for the persistence of microbes in the DS. In the present study a domestic water tap in north-central United States (USA) was sampled in March and September 2007 and analysed for FLA, Legionella and Mycobacterium. Identification of organisms was determined by growth on specific culture media, light and electron microscopy, and amplification of DNA probes specific for each organism. In both the spring and fall samples, amoebae, Legionella and Mycobacterium were detected. However, Acanthamoeba was prominent in the spring sample whereas Vahlkampfia and Naegleria were the amoebae detected in the autumn. Bacterial proliferation in laboratory cultures was noticeably enhanced in the presence of amoebae and biofilms rapidly formed in mixed amoebae and bacteria cultures. It is hypothesized that temperature affected the dynamics of FLA species population structure within the DS and that pathogenic bacteria that proliferate within FLA, which are themselves opportunistic pathogens, pose dual public health risks.

  15. New Multiplier Sequences via Discriminant Amoebae

    CERN Document Server

    Passare, Mikael; Rojas, J Maurice

    2010-01-01

    In their classic 1914 paper, Polya and Schur introduced and characterized two types of linear operators acting diagonally on the monomial basis of R[x], sending real-rooted polynomials (resp. polynomials with all nonzero roots of the same sign) to real-rooted polynomials. Motivated by fundamental properties of amoebae and discriminants discovered by Gelfand, Kapranov, and Zelevinsky, we introduce two new natural classes of polynomials and describe diagonal operators preserving these new classes. A pleasant circumstance in our description is that these classes have a simple explicit description, one of them coinciding with the class of log-concave sequences.

  16. Trophic structure of amoeba communities near roots of Medicago sativa after contamination with fuel oil no. 6.

    Science.gov (United States)

    Cortés-Pérez, Sandra; Rodríguez-Zaragoza, Salvador; Mendoza-López, Ma Remedios

    2014-02-01

    Root exudation increases microbial activity, selecting bacterial and fungal communities that metabolize organic matter such as hydrocarbons. However, a strong contamination pulse of hydrocarbons around plant roots may reorganize the soil's microbial trophic structure toward amoebae feeding on bacteria. We conducted a microcosm experiment to elucidate the effect of Medicago sativa on the trophic structure of naked amoebae after a strong pulse of pollution (50,000 ppm of fuel oil no. 6, which is a mixture of long chains ranging from C10 to C28). Plants were seeded 24 h after contamination and species of amoebae in the microcosms were identified at 1, 30, and 60 days after pollution. Several species from three trophic groups of naked amoeba were still alive 24 h after the hydrocarbon pulse. Non-planted microcosms harbored three trophic groups after 60 days, while planted ones nourished four groups. The bacterivore group was the most diverse in all microcosms, followed by protist-eaters and omnivores. The quantity of amoebae was significantly higher (3.4×10(3) organisms/g soil) in the planted pots than in the non-planted ones (1.3×10(3) organisms/g soil after 30 days of pollution (P ≤ 0.01). The shortest hydrocarbon chains (C10-C14) disappeared or diminished in all microcosms, and the longest ones increased in the planted ones. M. sativa thus exerted a positive effect on species richness, quantity, and the composition of amoebae trophic groups in contaminated soil. This indirect effect on bacterial predators is another key factor underlying hydrocarbon assimilation by living organisms during phytoremediation.

  17. Free-living amoebae as vectors of cryptosporidia.

    Science.gov (United States)

    Scheid, Patrick L; Schwarzenberger, Rafael

    2011-08-01

    In the present article, the study to examine the ability of free-living amoebae (FLA) to serve as vectors of cryptosporidia is presented. Ten strains of different free-living amoebae of the FLA collection of the Parasitology Lab at Koblenz were cultivated in the presence of Cryptosporidium parvum oocysts. After phagocytosis and ingestion, the oocysts could be found in food vacuoles within the cytoplasm of the trophozoites of two different FLA strains. The uptake and the transport of the oocysts within the trophozoites could be demonstrated in an Acanthamoeba sp. (group II) strain (maximum, three oocysts; average, one oocyst) as well as in a Thecamoeba quadrilineata strain (maximum, 15 oocysts; average, eight oocysts), with the help of light microscopy. We found that these free-living amoebae can temporarily harbour cryptosporidia, thus supporting the suggestion that FLA may act as carriers and vehicles for cryptosporidia. However, proliferation did not take place within the host amoebae. No cryptosporidium oocysts were found within the cysts of the amoebae. To our knowledge, this is the first study to determine the "host range" of free-living amoebae as vectors and vehicles of cryptosporidia. Free-living amoebae appear able to act as carriers or vectors of the oocysts and thus may play a certain role in the transmission of cryptosporidia.

  18. Pathogenic free-living amoebae: epidemiology and clinical review.

    Science.gov (United States)

    Trabelsi, H; Dendana, F; Sellami, A; Sellami, H; Cheikhrouhou, F; Neji, S; Makni, F; Ayadi, A

    2012-12-01

    Free-living amoebae are widely distributed in soil and water. Small number of them was implicated in human disease: Acanthamoeba spp., Naegleria fowleri, Balamuthia mandrillaris and Sappinia diploidea. Some of the infections were opportunistic, occurring mainly in immunocompromised hosts (Acanthamoeba and Balamuthia encephalitis) while others are non opportunistic (Acanthamoeba keratitis, Naegleria meningoencephalitis and some cases of Balamuthia encephalitis). Although, the number of infections caused by these amoebae is low, their diagnosis was still difficult to confirm and so there was a higher mortality, particularly, associated with encephalitis. In this review, we present some information about epidemiology, ecology and the types of diseases caused by these pathogens amoebae.

  19. Anticipation of periodic environmental changes in an amoeba

    Science.gov (United States)

    Saigusa, Tetsu; Nakagaki, Toshiyuki

    2007-07-01

    The amoeboid organism of true slime mold, the plasmodium of Physarum polycephalum, had capacity of memorizing a periodic event. The organism showed vigorous locomotion in the favorite conditions. When stimulation of the unfavorable conditions was given in a pulse-like regime and was repeated three times at interval of 60 minutes, the amoeba reduced the locomotion speed in response to each pulse. Even though the favorite conditions were kept to be constant after the periodic pulses, the amoeba spontaneously reduced the locomotion speed at the timing of next pulse (after 60 minutes). This means that the amoeba anticipated the next environmental change.

  20. Additive partitioning of testate amoeba species diversity across habitat hierarchy within the pristine southern taiga landscape (Pechora-Ilych Biosphere Reserve, Russia).

    Science.gov (United States)

    Tsyganov, Andrey N; Komarov, Alexander A; Mitchell, Edward A D; Shimano, Satoshi; Smirnova, Olga V; Aleynikov, Alexey A; Mazei, Yuri A

    2015-02-01

    In order to better understand the distribution patterns of terrestrial eukaryotic microbes and the factors governing them, we studied the diversity partitioning of soil testate amoebae across levels of spatially nested habitat hierarchy in the largest European old-growth dark coniferous forest (Pechora-Ilych Biosphere Reserve; Komi Republic, Russia). The variation in testate amoeba species richness and assemblage structure was analysed in 87 samples from six biotopes in six vegetation types using an additive partitioning procedure and principal component analyses. The 80 taxa recorded represent the highest value of species richness for soil testate amoebae reported for taiga soils so far. Our results indicate that testate amoeba assemblages were highly aggregated at all levels and were mostly controlled by environmental factors rather than dispersal processes. The variation in species diversity of testate amoebae increased from the lowest to the highest hierarchical level. We conclude that, similarly to macroscopic organisms, testate amoeba species richness and community structure are primarily controlled by environmental conditions within the landscape and suggest that metacommunity dynamics of free-living microorganisms are driven by species sorting and/or mass effect processes.

  1. An electronic implementation of amoeba anticipation

    Science.gov (United States)

    Ziegler, Martin; Ochs, Karlheinz; Hansen, Mirko; Kohlstedt, Hermann

    2014-02-01

    In nature, the capability of memorizing environmental changes and recalling past events can be observed in unicellular organisms like amoebas. Pershin and Di Ventra have shown that such learning behavior can be mimicked in a simple memristive circuit model consisting of an LC (inductance capacitance) contour and a memristive device. Here, we implement this model experimentally by using an Ag/TiO2- x /Al memristive device. A theoretical analysis of the circuit is used to gain insight into the functionality of this model and to give advice for the circuit implementation. In this respect, the transfer function, resonant frequency, and damping behavior for a varying resistance of the memristive device are discussed in detail.

  2. Vibrational mode assignment of finite temperature infrared spectra using the AMOEBA polarizable force field.

    Science.gov (United States)

    Thaunay, Florian; Dognon, Jean-Pierre; Ohanessian, Gilles; Clavaguéra, Carine

    2015-10-21

    The calculation of infrared spectra by molecular dynamics simulations based on the AMOEBA polarizable force field has recently been demonstrated [Semrouni et al., J. Chem. Theory Comput., 2014, 10, 3190]. While this approach allows access to temperature and anharmonicity effects, band assignment requires additional tools, which we describe in this paper. The Driven Molecular Dynamics approach, originally developed by Bowman, Kaledin et al. [Bowman et al. J. Chem. Phys., 2003, 119, 646, Kaledin et al. J. Chem. Phys., 2004, 121, 5646] has been adapted and associated with AMOEBA. Its advantages and limitations are described. The IR spectrum of the Ac-Phe-Ala-NH2 model peptide is analyzed in detail. In addition to differentiation of conformations by reproducing frequency shifts due to non-covalent interactions, DMD allows visualizing the temperature-dependent vibrational modes.

  3. Interaction of Pasteurella multocida with free-living amoebae.

    Science.gov (United States)

    Hundt, Matthew J; Ruffolo, Carmel G

    2005-09-01

    Pasteurella multocida is a highly infectious, facultative intracellular bacterium which causes fowl cholera in birds. This study reports, for the first time, the observed interaction between P. multocida and free-living amoebae. Amoebal trophozoites were coinfected with fowl-cholera-causing P. multocida strain X-73 that expressed the green fluorescent protein (GFP). Using confocal fluorescence microscopy, GFP expressing X-73 was located within the trophozoite. Transmission electron microscopy of coinfection preparations revealed clusters of intact X-73 cells in membrane-bound vacuoles within the trophozoite cytoplasm. A coinfection assay employing gentamicin to kill extracellular bacteria was used to assess the survival and replication of P. multocida within amoebae. In the presence of amoebae, the number of recoverable intracellular X-73 cells increased over a 24-h period; in contrast, X-73 cultured alone in assay medium showed a consistent decline in growth. Cytotoxicity assays and microscopy showed that X-73 was able to lyse and exit the amoebal cells approximately 18 h after coinfection. The observed interaction between P. multocida and amoebae can be considered as an infective process as the bacterium was able to invade, survive, replicate, and lyse the amoebal host. This raises the possibility that similar interactions occur in vivo between P. multocida and host cells. Free-living amoebae are ubiquitous within water and soil environments, and P. multocida has been observed to survive within these same ecosystems. Thus, our findings suggest that the interaction between P. multocida and amoebae may occur within the natural environment.

  4. [Non-pathogenic intestinal amoebae: a clinical-analytical overview].

    Science.gov (United States)

    Sard, Bárbara Gomila; Navarro, Rafael Toledo; Esteban Sanchis, J Guillermo

    2011-03-01

    Human beings can be parasitized by various species of intestinal amoebae. Entamoeba histolytica is the only intestinal amoeba recognized to be pathogenic, while other amoeba species, E. dispar, E. moshkovskii, E. hartmanni, E. coli, E. polecki, Endolimax nana and Iodamoeba buetschlii are considered to be non-pathogenic. The aim of this review is to synthesize the main morphological characteristics of the trophozoite and cyst stages of each amoeba as the basis for precise microscopical diagnosis. The difficulty of morphological differentiation among species included in the so-called "Entamoeba complex" entails the use of immunological and molecular diagnoses. In addition, a summary of basic epidemiological, therapeutic and prophylactic aspects of these non-pathogenic amoebae is provided. All of these aspects are crucial since these amoebae are usually found to be present in human coproparasitological analyses and must be differentiated from the pathogenic species E. histolytica. Furthermore, they can be used as suitable biological tags of the hygienic state of the environment and the health and hygiene measures of the population. PMID:21458707

  5. Differential growth of Legionella pneumophila strains within a range of amoebae at various temperatures associated with in-premise plumbing

    Science.gov (United States)

    The potential effect of in-premise plumbing temperatures (24, 32, 37 and 41 °C) on the growth of five different L. pneumophila strains within free-living amoebae (Acanthamoeba polyphaga, Hartmannella vermiformis and Naegleria fowleri) was examined. Compared to controls only fed E...

  6. Identification of free-living amoebae and amoeba-associated bacteria from reservoirs and water treatment plants by molecular techniques.

    Science.gov (United States)

    Garcia, Alicia; Goñi, Pilar; Cieloszyk, Joanna; Fernandez, Maria Teresa; Calvo-Beguería, Laura; Rubio, Encarnacion; Fillat, Maria Francisca; Peleato, Maria Luisa; Clavel, Antonio

    2013-04-01

    The occurrence of free-living amoebae (FLA) was investigated in 83 water samples from reservoirs and water treatment plants, with culture positive in 64 of them (77.1%). Polymerase chain reaction (PCR) of partial 18S rRNA gene and ITS region was performed in order to identify amoeba isolates, and the presence of Legionella pneumophila , Mycobacterium spp., Pseudomonas spp., and Microcystis aeruginosa was investigated in 43 isolates of amoebae by multiplex PCR. Of the isolated amoebae, 31 were Acanthamoeba spp., 21 were Hartmannella vermiformis, 13 were Naegleria spp., and one was Vanella spp. T2, T4, and T5 genotypes of Acanthamoeba have been identified, and T4 isolates were grouped into five subgenotypes and graphically represented with a Weblog application. Inside amoebae, L. pneumophila was detected in 13.9% (6/43) of the isolates, and Pseudomonas spp. and Mycobacterium spp. were detected in 32.6% (14/43) and 41.9% (18/43), respectively. No statistical correlation was demonstrated between FLA isolation and seasonality, but the presence of intracellular bacteria was associated with warm water temperatures, and also the intracellular presence of Mycobacterium spp. and Pseudomonas spp. were associated. These results highlight the importance of amoebae in natural waters as reservoirs of potential pathogens and its possible role in the spread of bacterial genera with interest in public and environmental health.

  7. Significance testing testate amoeba water table reconstructions

    Science.gov (United States)

    Payne, Richard J.; Babeshko, Kirill V.; van Bellen, Simon; Blackford, Jeffrey J.; Booth, Robert K.; Charman, Dan J.; Ellershaw, Megan R.; Gilbert, Daniel; Hughes, Paul D. M.; Jassey, Vincent E. J.; Lamentowicz, Łukasz; Lamentowicz, Mariusz; Malysheva, Elena A.; Mauquoy, Dmitri; Mazei, Yuri; Mitchell, Edward A. D.; Swindles, Graeme T.; Tsyganov, Andrey N.; Turner, T. Edward; Telford, Richard J.

    2016-04-01

    Transfer functions are valuable tools in palaeoecology, but their output may not always be meaningful. A recently-developed statistical test ('randomTF') offers the potential to distinguish among reconstructions which are more likely to be useful, and those less so. We applied this test to a large number of reconstructions of peatland water table depth based on testate amoebae. Contrary to our expectations, a substantial majority (25 of 30) of these reconstructions gave non-significant results (P > 0.05). The underlying reasons for this outcome are unclear. We found no significant correlation between randomTF P-value and transfer function performance, the properties of the training set and reconstruction, or measures of transfer function fit. These results give cause for concern but we believe it would be extremely premature to discount the results of non-significant reconstructions. We stress the need for more critical assessment of transfer function output, replication of results and ecologically-informed interpretation of palaeoecological data.

  8. Cellular Response of the Amoeba Acanthamoeba castellanii to Chlorine, Chlorine Dioxide, and Monochloramine Treatments ▿

    OpenAIRE

    Mogoa, Emerancienne; Bodet, Charles; Morel, Franck; Rodier, Marie-Hélène; Legube, Bernard; Héchard, Yann

    2011-01-01

    Acanthamoeba castellanii is a free-living amoebae commonly found in water systems. Free-living amoebae might be pathogenic but are also known to bear phagocytosis-resistant bacteria, protecting these bacteria from water treatments. The mode of action of these treatments is poorly understood, particularly on amoebae. It is important to examine the action of these treatments on amoebae in order to improve them. The cellular response to chlorine, chlorine dioxide, and monochloramine was tested o...

  9. Shedding light on vampires: the phylogeny of vampyrellid amoebae revisited.

    Directory of Open Access Journals (Sweden)

    Sebastian Hess

    Full Text Available With the advent of molecular phylogenetic techniques the polyphyly of naked filose amoebae has been proven. They are interspersed in several supergroups of eukaryotes and most of them already found their place within the tree of life. Although the 'vampire amoebae' have attracted interest since the middle of the 19th century, the phylogenetic position and even the monophyly of this traditional group are still uncertain. In this study clonal co-cultures of eight algivorous vampyrellid amoebae and the respective food algae were established. Culture material was characterized morphologically and a molecular phylogeny was inferred using SSU rDNA sequence comparisons. We found that the limnetic, algivorous vampyrellid amoebae investigated in this study belong to a major clade within the Endomyxa Cavalier-Smith, 2002 (Cercozoa, grouping together with a few soil-dwelling taxa. They split into two robust clades, one containing species of the genus Vampyrella Cienkowski, 1865, the other containing the genus Leptophrys Hertwig & Lesser, 1874, together with terrestrial members. Supported by morphological data these clades are designated as the two families Vampyrellidae Zopf, 1885, and Leptophryidae fam. nov. Furthermore the order Vampyrellida West, 1901 was revised and now corresponds to the major vampyrellid clade within the Endomyxa, comprising the Vampyrellidae and Leptophryidae as well as several environmental sequences. In the light of the presented phylogenetic analyses morphological and ecological aspects, the feeding strategy and nutritional specialization within the vampyrellid amoebae are discussed.

  10. Amoebas as mimivirus bunkers: increased resistance to UV light, heat and chemical biocides when viruses are carried by amoeba hosts.

    Science.gov (United States)

    Boratto, Paulo V M; Dornas, Fábio P; Andrade, Kétyllen R; Rodrigues, Rodrigo; Peixoto, Felipe; Silva, Lorena C F; La Scola, Bernard; Costa, Adriana Oliveira; de Almeida, Gabriel Magno Freitas; Kroon, Erna G; Abrahão, Jônatas S

    2014-05-01

    Amoebas of the genus Acanthamoeba are protists that are associated with human disease and represent a public health concern. They can harbor pathogenic microorganisms, acting as a platform for pathogen replication. Acanthamoeba polyphaga mimivirus (APMV), the type species of the genus Mimivirus, family Mimiviridae, represents the largest group of amoeba-associated viruses that has been described to date. Recent studies have demonstrated that APMV and other giant viruses may cause pneumonia. Amoebas can survive in most environments and tolerate various adverse conditions, including UV light irradiation, high concentrations of disinfectants, and a broad range of temperatures. However, it is unknown how the amoebal intracellular environment influences APMV stability and resistance to adverse conditions. Therefore, in this work, we evaluated the stability of APMV, either purified or carried by the amoeba host, under extreme conditions, including UV irradiation, heat and exposure to six different chemical biocides. After each treatment, the virus was titrated in amoebas using the TCID50 method. APMV was more stable in all resistance tests performed when located inside its host. Our results demonstrate that Acanthamoeba acts as a natural bunker for APMV, increasing viral resistance to extreme physical and chemical conditions. The data raise new questions regarding the survival of APMV in nature and in hospital environments.

  11. Amoeba-resisting bacteria found in multilamellar bodies secreted by Dictyostelium discoideum: social amoebae can also package bacteria.

    Science.gov (United States)

    Paquet, Valérie E; Charette, Steve J

    2016-03-01

    Many bacteria can resist phagocytic digestion by various protozoa. Some of these bacteria (all human pathogens) are known to be packaged in multilamellar bodies produced in the phagocytic pathway of the protozoa and that are secreted into the extracellular milieu. Packaged bacteria are protected from harsh conditions, and the packaging process is suspected to promote bacterial persistence in the environment. To date, only a limited number of protozoa, belonging to free-living amoebae and ciliates, have been shown to perform bacteria packaging. It is still unknown if social amoebae can do bacteria packaging. The link between the capacity of 136 bacterial isolates to resist the grazing of the social amoeba Dictyostelium discoideum and to be packaged by this amoeba was investigated in the present study. The 45 bacterial isolates displaying a resisting phenotype were tested for their capacity to be packaged. A total of seven isolates from Cupriavidus, Micrococcus, Microbacterium and Rathayibacter genera seemed to be packaged and secreted by D. discoideum based on immunofluorescence results. Electron microscopy confirmed that the Cupriavidus and Rathayibacter isolates were formally packaged. These results show that social amoebae can package some bacteria from the environment revealing a new aspect of microbial ecology.

  12. Naegleria fowleri: a free living amoeba of emerging medical importance.

    Science.gov (United States)

    Parija, S C; Jayakeerthee, S R

    1999-09-01

    Naegleria fowleri, a free-living amoeba is ubiquitous and word-wide in distribution. Infection is due to inhalation or aspiration of aerosols containing cysts found in the environment. Of late, the amoeba is emerging as a pathogen of medical importance causing primary amoebic meningoencephalitis (PAM) in humans. The diagnosis of the condition is mainly parasitic which depends on the detection and identification of Naegleria trophozoites in the cerebro-spinal fluid (CSF) or biopsied brain tissue. Serological tests are not useful in the diagnosis of PAM. Most cases are fatal and various amoebicidal agents have been tried unsuccessfully. The present paper provides a review of the recent information on the biology and epidemiology of the disease caused by the amoeba Approaches in the diagnosis, pathophysiology and treatment of the condition are also discussed.

  13. Identifying endosymbiont bacteria associated with free-living amoebae.

    Science.gov (United States)

    Goñi, Pilar; Fernández, María Teresa; Rubio, Encarnación

    2014-02-01

    The association between free-living amoebae and pathogenic bacteria is an issue that has gained great importance due to the environmental and health consequences that it implies. In this paper, we analyse the techniques to follow an epidemiological study to identify associations between genera, species, genotypes and subgenotypes of amoebae with pathogenic bacteria, analysing their evolution and considering their usefulness. In this sense, we highlight the combination of microscopic and molecular techniques as the most appropriate way to obtain fully reliable results as well as the need to achieve the standardization of these techniques to allow the comparison of both environmental and clinical results.

  14. Methodology to Implement an Amoeba Complex Object Server

    NARCIS (Netherlands)

    Teeuw, Wouter B.; Blanken, Henk M.

    1992-01-01

    The paper describes the methodology used in the design of a complex object server application for the Amoeba distributed operating system. It uses the top-down design that was suggested by Parnas, in which a model is turned into an implementation by gradually adding details. The paper also describes

  15. Molecular epidemiology of human intestinal amoebas in iran.

    Science.gov (United States)

    Hooshyar, H; Rostamkhani, P; Rezaian, M

    2012-01-01

    Many microscopic-based epidemiological surveys on the prevalence of human intestinal pathogenic and non-pathogenic protozoa including intestinal amoeba performed in Iran show a high prevalence of human intestinal amoeba in different parts of Iran. Such epidemiological studies on amoebiasis are confusing, mainly due to recently appreciated distinction between the Entamoeba histolytica, E. dispar and E. moshkovskii. Differential diagnosis can be done by some methods such as PCR-based methods, monoclonal antibodies and the analysis of isoenzyme typing, however the molecular study of these protozoa in Iran is low. Based on molecular studies, it seems that E. dispar is predominant species especially in the central and northern areas of Iran and amoebiasis due to E. histolytica is a rare infection in the country. It is suggested that infection with E. moshkovskii may be common among Iranians. Considering the importance of molecular epidemiology of amoeba in Iran and also the current data, the present study reviews the data currently available on the molecular distribution of intestinal human amoeba in Iran.

  16. Shifts in soil testate amoeba communities associated with forest diversification.

    Science.gov (United States)

    Bobrov, Anatoly A; Zaitsev, Andrei S; Wolters, Volkmar

    2015-05-01

    We studied changes of testate amoeba communities associated with the conversion of spruce monocultures into mixed beech-fir-spruce forests in the Southern Black Forest Mountains (Germany). In this region, forest conversion is characterized by a gradual development of beech undergrowth within thinned spruce tree stands leading to multiple age continuous cover forests with a diversified litter layer. Strong shifts in the abundance of testate amoeba observed in intermediate stages levelled off to monoculture conditions again after the final stage of the conversion process had been reached. The average number of species per conversion stage (i.e., local richness) did not respond strongly to forest conversion, but the total number of species (i.e., regional richness) was considerably higher in the initial stage than in the mixed forests, due to the large number of hygrophilous species inhabiting spruce monocultures. Functional diversity of the testate amoeba community, however, significantly increased during the conversion process. This shift was closely associated with improved C and N availability as well as higher niche diversity in the continuous cover stands. Lower soil acidity in these forests coincided with a higher relative abundance of eurytopic species. Our results suggest that testate amoeba communities are much more affected by physicochemical properties of the soil than directly by litter diversity.

  17. Counting Legionella cells within single amoeba host cells

    Science.gov (United States)

    Here we present the first attempt to quantify L. pneumophila cell numbers within individual amoebae hosts that may be released into engineered water systems. The maximum numbers of culturable L. pneumophila cells grown within Acanthamoeba polyphaga and Naegleria fowleri were 134...

  18. Diagnosis of Infections Caused by Pathogenic Free-Living Amoebae

    Directory of Open Access Journals (Sweden)

    Bruno da Rocha-Azevedo

    2009-01-01

    Full Text Available Naegleria fowleri, Acanthamoeba spp., Balamuthia mandrillaris, and Sappinia sp. are pathogenic free-living amoebae. N. fowleri causes Primary Amoebic Meningoencephalitis, a rapidly fatal disease of the central nervous system, while Acanthamoeba spp. and B. mandrillaris cause chronic granulomatous encephalitis. Acanthamoeba spp. also can cause cutaneous lesions and Amoebic Keratitis, a sight-threatening infection of the cornea that is associated with contact lens use or corneal trauma. Sappinia pedata has been identified as the cause of a nonlethal case of amoebic encephalitis. In view of the potential health consequences due to infection with these amoebae, rapid diagnosis is critical for early treatment. Microscopic examination and culture of biopsy specimens, cerebral spinal fluid (CSF, and corneal scrapings have been used in the clinical laboratory. For amoebic keratitis, confocal microscopy has been used to successfully identify amoebae in corneal tissue. More recently, conventional and real-time PCR assays have been developed that are sensitive and specific for the amoebae. In addition, multiplex PCR assays are available for the rapid identification of these pathogens in biopsy tissue, CSF, and corneal specimens.

  19. Diagnosis of infections caused by pathogenic free-living amoebae.

    Science.gov (United States)

    da Rocha-Azevedo, Bruno; Tanowitz, Herbert B; Marciano-Cabral, Francine

    2009-01-01

    Naegleria fowleri, Acanthamoeba spp., Balamuthia mandrillaris, and Sappinia sp. are pathogenic free-living amoebae. N. fowleri causes Primary Amoebic Meningoencephalitis, a rapidly fatal disease of the central nervous system, while Acanthamoeba spp. and B. mandrillaris cause chronic granulomatous encephalitis. Acanthamoeba spp. also can cause cutaneous lesions and Amoebic Keratitis, a sight-threatening infection of the cornea that is associated with contact lens use or corneal trauma. Sappinia pedata has been identified as the cause of a nonlethal case of amoebic encephalitis. In view of the potential health consequences due to infection with these amoebae, rapid diagnosis is critical for early treatment. Microscopic examination and culture of biopsy specimens, cerebral spinal fluid (CSF), and corneal scrapings have been used in the clinical laboratory. For amoebic keratitis, confocal microscopy has been used to successfully identify amoebae in corneal tissue. More recently, conventional and real-time PCR assays have been developed that are sensitive and specific for the amoebae. In addition, multiplex PCR assays are available for the rapid identification of these pathogens in biopsy tissue, CSF, and corneal specimens.

  20. Inactivation and Removal of Free-Living Amoebae.

    Science.gov (United States)

    Free-living amoebae (FLA) are ubiquitous protozoan that are predominantly harmless to humans. There are a few genera that cause disease in humans, Balamuthia, Naegleria, and Acanthamoeba. These organisms are not easily removed by physical means or inactivated by chemic...

  1. The genome of the social amoeba Dictyostelium discoideum

    DEFF Research Database (Denmark)

    Eichinger, L; Pachebat, J A; Glöckner, G;

    2005-01-01

    The social amoebae are exceptional in their ability to alternate between unicellular and multicellular forms. Here we describe the genome of the best-studied member of this group, Dictyostelium discoideum. The gene-dense chromosomes of this organism encode approximately 12,500 predicted proteins,...

  2. Molecular Epidemiology of Human Intestinal Amoebas in Iran

    Directory of Open Access Journals (Sweden)

    M Rezaian

    2012-09-01

    Full Text Available Many microscopic-based epidemiological surveys on the prevalence of human intestinal pathogenic and non-pathogenic protozoa including intestinal amoeba performed in Iran show a high prevalence of human intestinal amoeba in different parts of Iran. Such epidemiological studies on amoebiasis are confusing, mainly due to recently appreciated distinction between the Entamoeba histolytica, E. dispar and E. moshkovskii. Differential diagnosis can be done by some methods such as PCR-based methods, monoclonal antibodies and the analysis of isoenzyme typing, however the molecular study of these protozoa in Iran is low. Based on molecular studies, it seems that E. dispar is predominant species especially in the central and northern areas of Iran and amoebiasis due to E. histolytica is a rare infection in the country. It is suggested that infection with E. moshkovskii may be common among Iranians. Considering the importance of molecular epidemiology of amoeba in Iran and also the current data, the present study reviews the data currently available on the molecular distribution of intestinal human amoeba in Iran.

  3. Amoebae-Based Screening Reveals a Novel Family of Compounds Restricting Intracellular Legionella pneumophila.

    Science.gov (United States)

    Harrison, Christopher F; Chiriano, Gianpaolo; Finsel, Ivo; Manske, Christian; Hoffmann, Christine; Steiner, Bernhard; Kranjc, Agata; Patthey-Vuadens, Ophelie; Kicka, Sébastien; Trofimov, Valentin; Ouertatani-Sakouhi, Hajer; Soldati, Thierry; Scapozza, Leonardo; Hilbi, Hubert

    2015-07-10

    The causative agent of Legionnaires' disease, Legionella pneumophila, grows in environmental amoebae and mammalian macrophages within a distinct compartment, the 'Legionella-containing vacuole' (LCV). Intracellular bacteria are protected from many antibiotics, and thus are notoriously difficult to eradicate. To identify novel compounds that restrict intracellular bacterial replication, we previously developed an assay based on a coculture of amoebae and GFP-producing L. pneumophila. This assay was used to screen a pathway-based, highly diverse chemical library, referred to as the Sinergia library. In this work, we chose to focus on a group of 11 hit compounds, the majority of which originated from the query molecule CN585, a compound that targets the protein phosphatase calcineurin. Further studies on 78 related compound variants revealed crucial structural attributes, namely a triple-ring scaffold with a central triazine moiety, substituted in positions 3 and 5 by two piperidine or pyrrolidine rings, and in position 1 by an amine group bearing a single aliphatic chain moiety. The most effective compound, ZINC00615682, inhibited intracellular replication of L. pneumophila with an IC50 of approximately 20 nM in Acanthamoeba castellanii and slightly less efficiently in Dictyostelium discoideum or macrophages. Pharmacological and genetic attempts to implicate calcineurin in the intracellular replication of L. pneumophila failed. Taken together, these results show that the amoebae-based screen and structure-activity relationship analysis is suitable for the identification of novel inhibitors of the intracellular replication of L. pneumophila. The most potent compound identified in this study targets (an) as yet unidentified host factor(s). PMID:27622823

  4. Surveillance of parasitic Legionella in surface waters by using immunomagnetic separation and amoebae enrichment.

    Science.gov (United States)

    Hsu, Tsui-Kang; Wu, Shu-Fen; Hsu, Bing-Mu; Kao, Po-Min; Tao, Chi-Wei; Shen, Shu-Min; Ji, Wen-Tsai; Huang, Wen-Chien; Fan, Cheng-Wei

    2015-01-01

    Free-living amoebae (FLA) are potential reservoirs of Legionella in aquatic environments. However, the parasitic relationship between various Legionella and amoebae remains unclear. In this study, surface water samples were gathered from two rivers for evaluating parasitic Legionella. Warmer water temperature is critical to the existence of Legionella. This result suggests that amoebae may be helpful in maintaining Legionella in natural environments because warmer temperatures could enhance parasitisation of Legionella in amoebae. We next used immunomagnetic separation (IMS) to identify extracellular Legionella and remove most free Legionella before detecting the parasitic ones in selectively enriched amoebae. Legionella pneumophila was detected in all the approaches, confirming that the pathogen is a facultative amoebae parasite. By contrast, two obligate amoebae parasites, Legionella-like amoebal pathogens (LLAPs) 8 and 9, were detected only in enriched amoebae. However, several uncultured Legionella were detected only in the extracellular samples. Because the presence of potential hosts, namely Vermamoeba vermiformis, Acanthamoeba spp. and Naegleria gruberi, was confirmed in the samples that contained intracellular Legionella, uncultured Legionella may survive independently of amoebae. Immunomagnetic separation and amoebae enrichment may have referential value for detecting parasitic Legionella in surface waters.

  5. A QM/MM Approach Using the AMOEBA Polarizable Embedding: From Ground State Energies to Electronic Excitations.

    Science.gov (United States)

    Loco, Daniele; Polack, Étienne; Caprasecca, Stefano; Lagardère, Louis; Lipparini, Filippo; Piquemal, Jean-Philip; Mennucci, Benedetta

    2016-08-01

    A fully polarizable implementation of the hybrid quantum mechanics/molecular mechanics approach is presented, where the classical environment is described through the AMOEBA polarizable force field. A variational formalism, offering a self-consistent relaxation of both the MM induced dipoles and the QM electronic density, is used for ground state energies and extended to electronic excitations in the framework of time-dependent density functional theory combined with a state specific response of the classical part. An application to the calculation of the solvatochromism of the pyridinium N-phenolate betaine dye used to define the solvent ET(30) scale is presented. The results show that the QM/AMOEBA model not only properly describes specific and bulk effects in the ground state but it also correctly responds to the large change in the solute electronic charge distribution upon excitation.

  6. Survival of Campylobacter jejuni in co-culture with Acanthamoeba castellanii: role of amoeba-mediated depletion of dissolved oxygen

    DEFF Research Database (Denmark)

    Bui, Thanh Xuan; Winding, Anne; Qvortrup, Klaus;

    2012-01-01

    Campylobacter jejuni is a major cause of infectious diarrhoea worldwide but relatively little is known about its ecology. In this study, we examined its interactions with Acanthamoeba castellanii, a protozoan suspected to serve as a reservoir for bacterial pathogens. We observed rapid degradation...... of intracellular C. jejuni in A. castellanii 5 h post gentamicin treatment at 25°C. Conversely, we found that A. castellanii promoted the extracellular growth of C. jejuni in co-cultures at 37°C in aerobic conditions. This growth-promoting effect did not require amoebae – bacteria contact. The growth rates......, the dissolved oxygen levels of co-cultures with or without amoebae – bacteria contact were much lower than those observed with culture media or with C. jejuni alone incubated in aerobic conditions, and were comparable with levels obtained after 24 h of growth of C. jejuni under microaerophilic conditions. Our...

  7. A QM/MM Approach Using the AMOEBA Polarizable Embedding: From Ground State Energies to Electronic Excitations.

    Science.gov (United States)

    Loco, Daniele; Polack, Étienne; Caprasecca, Stefano; Lagardère, Louis; Lipparini, Filippo; Piquemal, Jean-Philip; Mennucci, Benedetta

    2016-08-01

    A fully polarizable implementation of the hybrid quantum mechanics/molecular mechanics approach is presented, where the classical environment is described through the AMOEBA polarizable force field. A variational formalism, offering a self-consistent relaxation of both the MM induced dipoles and the QM electronic density, is used for ground state energies and extended to electronic excitations in the framework of time-dependent density functional theory combined with a state specific response of the classical part. An application to the calculation of the solvatochromism of the pyridinium N-phenolate betaine dye used to define the solvent ET(30) scale is presented. The results show that the QM/AMOEBA model not only properly describes specific and bulk effects in the ground state but it also correctly responds to the large change in the solute electronic charge distribution upon excitation. PMID:27340904

  8. Raman spectroscopic study on the excystation process in a single unicellular organism amoeba (Acanthamoeba polyphaga).

    Science.gov (United States)

    Lin, Yu-Chung; Perevedentseva, Elena; Cheng, Chia-Liang

    2015-05-01

    An in vivo Raman spectroscopic study of amoeba (Acanthamoeba polyphaga) is presented. The changes of the spectra during the amoeba cyst activation and excystation are analyzed. The spectra show the changes of the relative intensities of bands corresponding to protein, lipid, and carotenoid components during cyst activation. The presence of carotenoids in the amoeba is observed via characteristic Raman bands. These signals in the Raman spectra are intense in cysts but decrease in intensity with cyst activation and exhibit a correlation with the life cycle of amoeba. This work demonstrates the feasibility of using Raman spectroscopy for the detection of single amoeba microorganisms in vivo and for the analysis of the amoeba life activity. The information obtained may have implications for the estimation of epidemiological situations and for the diagnostics and prognosis of the development of amoebic inflammations.

  9. Raman spectroscopic study on the excystation process in a single unicellular organism amoeba (Acanthamoeba polyphaga)

    Science.gov (United States)

    Lin, Yu-Chung; Perevedentseva, Elena; Cheng, Chia-Liang

    2015-05-01

    An in vivo Raman spectroscopic study of amoeba (Acanthamoeba polyphaga) is presented. The changes of the spectra during the amoeba cyst activation and excystation are analyzed. The spectra show the changes of the relative intensities of bands corresponding to protein, lipid, and carotenoid components during cyst activation. The presence of carotenoids in the amoeba is observed via characteristic Raman bands. These signals in the Raman spectra are intense in cysts but decrease in intensity with cyst activation and exhibit a correlation with the life cycle of amoeba. This work demonstrates the feasibility of using Raman spectroscopy for the detection of single amoeba microorganisms in vivo and for the analysis of the amoeba life activity. The information obtained may have implications for the estimation of epidemiological situations and for the diagnostics and prognosis of the development of amoebic inflammations.

  10. Methodology to Implement an Amoeba Complex Object Server

    OpenAIRE

    Teeuw, Wouter B.; Blanken, Henk M.

    1992-01-01

    The paper describes the methodology used in the design of a complex object server application for the Amoeba distributed operating system. It uses the top-down design that was suggested by Parnas, in which a model is turned into an implementation by gradually adding details. The paper also describes the abstraction levels that show up if going from a specification of the behaviour towards an implementation, and shows the methodology in which performance will be measured (instead of estimated)...

  11. On the Swimming of \\textit{Dictyostelium} amoebae

    CERN Document Server

    Bae, Albert

    2010-01-01

    Traditionally, the primary mode for locomotion of amoeboid cells was thought to be crawling on a substrate. Recently, it has been experimentally shown that \\textit{Dictostelium} amoeba and neutrophils can also swim in a directed fashion. The mechanisms for amoeboid crawling and swimming were hypothesized to be similar. In this letter, we show that the shape changes generated by a crawling \\textit{D. discoideum} cell are consistent with swimming.

  12. Complement sensitivity of Entamoeba histolytica and various nonpathogenic amoeba species.

    Science.gov (United States)

    Förster, B; Ebert, F; Horstmann, R D

    1994-12-01

    Culture forms of the potentially pathogenic Entamoeba histolytica were compared to those of the nonpathogenic species of E. dispar, E. hartmanni, E. coli, Endolimax nana, and E. moshkovskii regarding the sensitivity to lysis by human complement activated through the alternative pathway. E. dispar was found unique in its complement resistance; all other nonpathogenic isolates resembled E. histolytica in that they were complement sensitive. Thus, a state of complement sensitivity is not a particular property of potentially pathogenic amoebae. PMID:7716404

  13. TINKTEP: A fully self-consistent, mutually polarizable QM/MM approach based on the AMOEBA force field

    Science.gov (United States)

    Dziedzic, Jacek; Mao, Yuezhi; Shao, Yihan; Ponder, Jay; Head-Gordon, Teresa; Head-Gordon, Martin; Skylaris, Chris-Kriton

    2016-09-01

    We present a novel quantum mechanical/molecular mechanics (QM/MM) approach in which a quantum subsystem is coupled to a classical subsystem described by the AMOEBA polarizable force field. Our approach permits mutual polarization between the QM and MM subsystems, effected through multipolar electrostatics. Self-consistency is achieved for both the QM and MM subsystems through a total energy minimization scheme. We provide an expression for the Hamiltonian of the coupled QM/MM system, which we minimize using gradient methods. The QM subsystem is described by the onetep linear-scaling DFT approach, which makes use of strictly localized orbitals expressed in a set of periodic sinc basis functions equivalent to plane waves. The MM subsystem is described by the multipolar, polarizable force field AMOEBA, as implemented in tinker. Distributed multipole analysis is used to obtain, on the fly, a classical representation of the QM subsystem in terms of atom-centered multipoles. This auxiliary representation is used for all polarization interactions between QM and MM, allowing us to treat them on the same footing as in AMOEBA. We validate our method in tests of solute-solvent interaction energies, for neutral and charged molecules, demonstrating the simultaneous optimization of the quantum and classical degrees of freedom. Encouragingly, we find that the inclusion of explicit polarization in the MM part of QM/MM improves the agreement with fully QM calculations.

  14. Free living amoebae in water sources of critical units in a tertiary care hospital in India

    Directory of Open Access Journals (Sweden)

    S Khurana

    2015-01-01

    Full Text Available Background: Isolation of free-living amoebae (FLA is reported sparsely from water taps, ventilators, air conditioners, haemodialysis units and dental irrigation systems of hospitals worldwide. Their prevalence in hospital environment especially in wards having immunocompromised patients may pose a risk to this group of susceptible population as they may cause disease themselves or may carry pathogens inside them. No study from India has performed such surveillance. Objective: To evaluate extent of FLA contamination in water sources of bone marrow transplant (BMT intensive care unit (ICU, transplant ICU, haemodialysis unit and high dependency unit in a tertiary care hospital in India. Materials and Methods: A total of hundred samples including fifty each of tap water samples and swabs from mouth of taps used for drinking, bathing and hand washing purposes in these units were collected according to standard procedure. Samples were inoculated onto non-nutrient agar plates at room temperature followed by morphological confirmation. Molecular identification including polymerase chain reaction (PCR and sequencing was performed in culture positive samples. Results: Four tap water samples and ten swab samples showed growth of trophozoites and cyst formation. Morphologically, four amoebae resembled Acanthamoeba spp. which was further confirmed by PCR and sequencing showed them to be of T3 and T4 genotypes. Conclusion: The presence of these FLA in hospital water sources emphasises the urgent need of implementing effective preventive measures. Further studies are required to estimate the true prevalence of FLA in Indian hospitals by taking larger number of samples.

  15. Screening of Swiss hot spring resorts for potentially pathogenic free-living amoebae.

    Science.gov (United States)

    Gianinazzi, Christian; Schild, Marc; Zumkehr, Beatrice; Wüthrich, Fritz; Nüesch, Irina; Ryter, Regula; Schürch, Nadia; Gottstein, Bruno; Müller, Norbert

    2010-09-01

    Free-living amoebae (FLA) belonging to Acanthamoeba spp., Naegleria fowleri, Balamuthia mandrillaris, and Sappinia pedata are known to cause infections in humans and animals leading to severe brain pathologies. Worldwide, warm aquatic environments have been found to be suitable habitats for pathogenic FLA. The present study reports on screening for potentially pathogenic FLA in four hot spring resorts in Switzerland. Water samples were taken from water filtration units and from the pools, respectively. Amoebae isolated from samples taken during, or before, the filtration process were demonstrated to be morphologically and phylogenetically related to Stenoamoeba sp., Hartmannella vermiformis, Echinamoeba exundans, and Acanthamoeba healyi. With regard to the swimming pools, FLA were isolated only in one resort, and the isolate was identified as non-pathogenic and as related to E. exundans. Further investigations showed that the isolates morphologically and phylogenetically related to A. healyi displayed a pronounced thermotolerance, and exhibited a marked in vitro cytotoxicity upon 5-day exposure to murine L929 fibroblasts. Experimental intranasal infection of Rag2-immunodeficient mice with these isolates led to severe brain pathologies, and viable trophozoites were isolated from the nasal mucosa, brain tissue, and lungs post mortem. In summary, isolates related to A. healyi were suggestive of being potentially pathogenic to immunocompromised persons. However, the presence of these isolates was limited to the filtration units, and an effective threat for health can therefore be excluded.

  16. Spontaneous deadlock breaking on amoeba-based neurocomputer.

    Science.gov (United States)

    Aono, Masashi; Hara, Masahiko

    2008-01-01

    Any artificial concurrent computing system involves a potential risk of "deadlock" that its multiple processes sharing common computational resources are stuck in starved conditions, if simultaneous accesses of the processes to the resources were unconditionally permitted. To avoid the deadlock, it is necessary to set up some form of central control protocol capable of appropriately regulating the resource allocation. On the other hand, many decentralized biological systems also perform concurrent computing based on interactions of components sharing limited amounts of available resources. Despite the absence of a central control unit, they appear to be free from the deadlock implying their death, as long as they are alive. Should we consider that biological computing paradigms are essentially different from artificial ones? Here we employ a photosensitive amoeboid cell known as a model organism for studying cellular information processing and construct an experimental system to explore how the amoeba copes with deadlock-like situations induced by optical feedback control. The feedback control is implemented by a recurrent neural network algorithm for leading the amoeba to solve a particular constraint satisfaction problem. We show that the amoeba is capable of breaking through the deadlock-like situations because its oscillating cellular membrane spontaneously produces a wide variety of spatiotemporal patterns. The result implies that our system can be developed to a neurocomputer that works as logical circuit, associative memory device, combinatorial optimization problem solver, and chaotic computer capable of spontaneous transition among multiple solutions.

  17. Cellular microbiology and molecular ecology of Legionella-amoeba interaction.

    Science.gov (United States)

    Richards, Ashley M; Von Dwingelo, Juanita E; Price, Christopher T; Abu Kwaik, Yousef

    2013-05-15

    Legionella pneumophila is an aquatic organism that interacts with amoebae and ciliated protozoa as the natural hosts, and this interaction plays a central role in bacterial ecology and infectivity. Upon transmission to humans, L. pneumophila infect and replicate within alveolar macrophages causing pneumonia. Intracellular proliferation of L. pneumophila within the two evolutionarily distant hosts is facilitated by bacterial exploitation of evolutionarily conserved host processes that are targeted by bacterial protein effectors injected into the host cell by the Dot/Icm type VIB translocation system. Although cysteine is semi-essential for humans and essential for amoeba, it is a metabolically favorable source of carbon and energy generation by L. pneumophila. To counteract host limitation of cysteine, L. pneumophila utilizes the AnkB Dot/Icm-translocated F-box effector to promote host proteasomal degradation of polyubiquitinated proteins within amoebae and human cells. Evidence indicates ankB and other Dot/Icm-translocated effector genes have been acquired through inter-kingdom horizontal gene transfer.

  18. Control of Branchionus sp. and Amoeba sp. in cultures of Arthrospira sp. Control de Branchionus sp. y Amoeba sp. en cultivos de Arthrospira sp.

    Directory of Open Access Journals (Sweden)

    Carlos Méndez

    2012-09-01

    Full Text Available Cultivation of cyanobacterium Arthrospira sp. has been developed in many countries for the production of proteins, pigments and other compounds. Outdoor mass cultures are often affected by biological contamination, drastically reducing productivity as far as bringing death. This study evaluates the control of Branchionus sp. and Amoeba sp. with two chemical compounds: urea (U and ammonium bicarbonate (AB, in laboratory conditions and outdoor mass culture of Arthrospira sp. The lethal concentration 100 (LC100 at 24 h for Branchionus sp. and Amoeba sp. determined was of 60-80 mg L-1 (U and 100-150 mg L-1 (AB. The average effective inhibition concentration for 50% of the population (IC50 in Arthrospira sp., after 72 h, was 80 mg L-1 (U and 150 mg L-1 (AB. The application of doses of 60 mg L-1 (U or 100 mg L-1 (AB in the outdoor mass culture of this contaminated microalga, completely inhibited grazing and did not affect the growth of Arthrospira sp. but rather promoted rapid recovery of algal density at levels prior to infestation. These compounds provided an economical and effective control of predators in cultures of Arthrospira sp.El cultivo de la cianobacteria Arthrospira sp. ha sido desarrollado en muchos países para la obtención de proteínas, pigmentos y otros compuestos. Cultivo que a nivel industrial se ve afectado frecuentemente por contaminación biológica, reduciendo drásticamente la productividad hasta causar la muerte. Este estudio evalúa el control de Branchionus sp. y de Amoeba sp. con dos compuestos químicos, la urea (U y bicarbonato de amonio (AB en cultivos de Arthrospira sp. La concentración letal 100 (LC100 determinada a las 24 h para Branchionus sp. y Amoeba sp. fue de 60-80 mg L-1 (U y 100-150 mg L-1 (AB. La concentración media de inhibición efectiva, después de 72 h, para el 50% de la población (IC50 en Arthrospira fue de 80 mg L-1 (U y 150 mg L-1 (AB. La aplicación de dosis de 60 mg L-1 (U ó 100 mg L-1 (AB en

  19. AMOEBA: Designing for Collaboration in Computer Science Classrooms through Live Learning Analytics

    Science.gov (United States)

    Berland, Matthew; Davis, Don; Smith, Carmen Petrick

    2015-01-01

    AMOEBA is a unique tool to support teachers' orchestration of collaboration among novice programmers in a non-traditional programming environment. The AMOEBA tool was designed and utilized to facilitate collaboration in a classroom setting in real time among novice middle school and high school programmers utilizing the IPRO programming…

  20. Biofilms augment the number of free-living amoebae in dental unit waterlines.

    Science.gov (United States)

    Barbeau, J; Buhler, T

    2001-10-01

    Freshwater amoebae are ubiquitous. Some species can cause infections in humans while others can ingest and protect opportunistic bacteria. Although the presence of free-living amoebae in various water sources has been reported, few studies have looked at their concentration, which may be clinically relevant, especially if they are present in healthcare devices. A simple technique was used to detect, observe, and evaluate the concentration of free-living amoebae in dental unit and tap water samples. Fifty-three water samples were collected from 35 dental units (air/water syringes) and 18 water taps. The technique was based on the ability of waterborne bacteria to create a biofilm and serve as substratum for the development of amoebae naturally present in the water samples. Laboratory-grown freshwater biofilms support the proliferation of a wide variety of free-living amoebae. All the dental unit water samples tested contained amoebae at concentrations up to 330/mL, or more than 300 times the concentration in tap water from the same source. Hartmanella, Vanella, and Vahlkampfia spp. were the most frequently encountered. Naegleria and Acanthamoeba spp. were also present in 40% of the samples. Four of the samples collected from dental units, but none from water taps, contained amoebae able to proliferate at 44 degrees C. Biofilms that form inside some dental instruments can considerably increase the concentration of free-living amoebae, some of which are potential human pathogens.

  1. Diversity of free-living amoebae in a dual distribution (potable and recycled) water system

    Science.gov (United States)

    Free-living amoebae are known to facilitate the growth of water associated pathogens. This study, for the first time, explored the diversity of free-living amoebae in a dual distribution (potable and recycled) water system in Rouse Hill NSW, Australia. Water and biofilm samples w...

  2. Pathogenic Free-Living Amoebae Isolated From Contact Lenses of Keratitis Patients

    Directory of Open Access Journals (Sweden)

    Elham HAJIALILO

    2015-12-01

    Full Text Available Background: Free-living amoeba (FLA-related keratitis is a progressive infection of the cornea with poor prognosis. The present study aimed to investigates the con­tact lenses of patients with keratitis for pathogenic free-living amoebae.Methods: Overall, 62 contact lenses and their paraphernalia of patients with kerati­tis cultured and tested for the presence of free-living amoebae using morphological criteria. Unusual plates including plates containing mix amoebae and Vermamoeba were submitted to molecular analysis. Results: Out of 62 plates, 11 revealed the outgrowth of free living amoeba of which 9 were Acanthamoeba, one plates contained mix amoebae including Acan­thamoeba and Vermamoeba and one showed the presence of Vermamoeba. These two latter plates belonged to patients suffered from unilateral keratitis due to the mis­used of soft contact lenses. One of the patients had mix infection of Acanthamoeba (T4 and V. vermiformis meanwhile the other patient was infected with the V. vermiformis. Conclusion: Amoebic keratitis continues to rise in Iran and worldwide. To date, various genera of free-living amoebae such as Vermamoeba could be the causative agent of keratitis. Soft contact lens wearers are the most affected patients in the country, thus awareness of high-risk people for preventing free-living amoebae re­lated keratitis is of utmost importance.

  3. IDENTIFICATION OF Pseudomonas spp. AS AMOEBA-RESISTANT MICROORGANISMS IN ISOLATES OF Acanthamoeba

    Directory of Open Access Journals (Sweden)

    Vinicius José Maschio

    2015-02-01

    Full Text Available Acanthamoeba is a “Trojan horse” of the microbial world. The aim of this study was to identify the presence of Pseudomonas as an amoeba-resistant microorganism in 12 isolates of Acanthamoeba. All isolates showed the genus Pseudomonas spp. as amoeba-resistant microorganisms. Thus, one can see that the Acanthamoeba isolates studied are hosts of Pseudomonas.

  4. IDENTIFICATION OF Pseudomonas spp. AS AMOEBA-RESISTANT MICROORGANISMS IN ISOLATES OF Acanthamoeba

    OpenAIRE

    Vinicius José Maschio; Gertrudes Corção; Marilise Brittes Rott

    2015-01-01

    Acanthamoeba is a “Trojan horse” of the microbial world. The aim of this study was to identify the presence of Pseudomonas as an amoeba-resistant microorganism in 12 isolates of Acanthamoeba. All isolates showed the genus Pseudomonas spp. as amoeba-resistant microorganisms. Thus, one can see that the Acanthamoeba isolates studied are hosts of Pseudomonas.

  5. 仿阿米巴机器人结构设计与转弯机理分析%Amoeba-like robot mechanism designing and turning method analyzing

    Institute of Scientific and Technical Information of China (English)

    孙恒辉; 骆敏舟; 董翔; 钱荣荣

    2011-01-01

    The situations of motions and forces to amoeba were analyzed when it were moving. The kinematics characteristics of amoeba under the effect of tail contracting force were got. Based on the kinematics characteristics of amoeba-like robot including the movement of tail contracting and skin turning over, a new mechanism for Amoeba-like robot was designed, which was applied with the spring and damping systems. To reach the turning movement, the velocities of the two strip-skins of Amoeba-like robot, which contact to the same plane outside, should be different. A way to achieve the different velocities of the different strip-skins were discussed at last.%对阿米巴变形虫运动以及其中的受力情况进行了分析,得到了变形虫在尾部收缩力作用下的运动规律.基于仿阿米巴机器人尾部收缩和皮肤翻转的运动特征,采用弹簧和阻尼系统,设计了一种仿阿米巴机器人的运动机构.分析了仿阿米巴机器人与外界某一平面同时接触的2条带状皮肤应具有不同的速度,以实现转弯运动,并讨论了一种不同带状皮肤具有不同速度的实现方法.

  6. From amoeba to macrophages: exploring the molecular mechanisms of Legionella pneumophila infection in both hosts.

    Science.gov (United States)

    Escoll, Pedro; Rolando, Monica; Gomez-Valero, Laura; Buchrieser, Carmen

    2013-01-01

    Legionella pneumophila is a Gram-negative bacterium and the causative agent of Legionnaires' disease. It replicates within amoeba and infects accidentally human macrophages. Several similarities are seen in the L. pneumophila-infection cycle in both hosts, suggesting that the tools necessary for macrophage infection may have evolved during co-evolution of L. pneumophila and amoeba. The establishment of the Legionella-containing vacuole (LCV) within the host cytoplasm requires the remodeling of the LCV surface and the hijacking of vesicles and organelles. Then L. pneumophila replicates in a safe intracellular niche in amoeba and macrophages. In this review we will summarize the existing knowledge of the L. pneumophila infection cycle in both hosts at the molecular level and compare the factors involved within amoeba and macrophages. This knowledge will be discussed in the light of recent findings from the Acanthamoeba castellanii genome analyses suggesting the existence of a primitive immune-like system in amoeba.

  7. Microbiome of free-living amoebae isolated from drinking water.

    Science.gov (United States)

    Delafont, Vincent; Brouke, Amélie; Bouchon, Didier; Moulin, Laurent; Héchard, Yann

    2013-12-01

    Free-living amoebae (FLA) are protozoa that can be found in water networks where they prey on bacteria within biofilms. Most bacteria are digested rapidly by phagocytosis, however some are able to survive within amoebae and some are even able to multiply, as it is the case for Legionella pneumophila. These resisting bacteria are a potential health problem as they could also resist to macrophage phagocytosis. Several publications already reported intra-amoebal bacteria but the methods of identification did not allow metagenomic analysis and are partly based on co-culture with one selected amoebal strain. The aim of our study was to conduct a rRNA-targeted metagenomic analysis on amoebae and intra-amoebal bacteria found in drinking water network, to provide the first FLA microbiome in environmental strains. Three sites of a water network were sampled during four months. Culturable FLA were isolated and total DNA was prepared, allowing purification of both amoebal and bacterial DNA. Metagenomic studies were then conducted through 18S or 16S amplicons sequencing. Hartmannella was by far the most represented genus of FLA. Regarding intra-amoebal bacteria, 54 genera were identified, among which 21 were newly described intra-amoebal bacteria, underlying the power of our approach. There were high differences in bacterial diversity between the three sites. Several genera were highly represented and/or found at least in two sites, underlying that these bacteria could be able to multiply within FLA. Our method is therefore useful to identify FLA microbiome and could be applied to other networks to have a more comprehensive view of intra-amoebal diversity.

  8. Viruses in close associations with free-living amoebae.

    Science.gov (United States)

    Scheid, Patrick

    2015-11-01

    As both groups of organisms, free-living amoebae (FLA) and viruses, can be found in aquatic environments side by side, it appears obvious that there are multiple interactions with respect to host-endocytobiont relationships. Several relationships between viruses and protozoan hosts are described and it was the discovery of the so called "giant viruses," associated with amoebae, which gave another dimension to these interactions. Mimiviruses, Pandoraviruses and Pithoviruses are examples for interesting viral endocytobionts within FLA. In the Mimivirus viral factories, viral DNA undergoes replication and transcription, and the DNA is prepared to be packed in procapsids. Theses Mimivirus factories can be considered as efficient "production lines" where, at any given moment, all stages of viral generation including membrane biogenesis, capsid assembly and genome encapsidation, are occurring concomitantly. There are some hints that similar replication factories are involved as well during the Pandoravirus development. Some scientists favour the assumption that the giant viruses have received many of their genes from their hosts or from sympatric occurring endocytobionts via lateral gene transfer. This hypothesis would mean that this type of transfer has been an important process in the evolution of genomes in the context of the intracellular parasitic or endocytobiotic lifestyle. In turn, that would migitate against hypothesizing development of a new branch in the tree of life. Based on the described scenarios to explain the presence of genes related to translation, it is also possible that earlier ancestors of today's DNA viruses were involved in the origin of eukaryotes. That possibly could in turn support the idea that cellular organisms could have evolved from viruses with growing autarkic properties. In future we expect the discovery of further (giant) viruses within free-living amoebae and other protozoa through genomic, transcriptomic and proteomic analyses.

  9. Examination of thermally polluted water for free living amoebae and testing for their possible pathogenic properties

    Energy Technology Data Exchange (ETDEWEB)

    Janitschke, K.; Lichy, S.; Westphal, C.

    1982-05-01

    Water and mud samples were collected from canals and rivers which were adjacent to outlets discharging warm water of 3 power plants in Berlin. Downstream samples from 1 bathing resort were also collected. Free living amoebae were isolated from 138 water and 69 mud samples. From these respectively 156 and 73 strains could be cultured and were administered intranasally to mice for pathogenicity tests. Two Acanthamoeba strains from water and 7 from mud could be reisolated from mouse brain and or lungs, although no pathological disorders could be observed. Five Naegleria strains were negative in mouse inoculation tests. Four Acanthamoeba strains which were positive in mice were cultured at + 45 degrees C; no cytopathogenic effects were observed in tissue cultures. Acanthamoeba infective for mice could also be isolated from samples at low water temperatures. Further investigations have to show, whether changes in virulence of amoebic strains are of significance and therefore for epidemiology and pathogenicity in man.

  10. Amoebae as Potential Environmental Hosts for Mycobacterium ulcerans and Other Mycobacteria, but Doubtful Actos in Buruli Ulcer Epidemiology

    DEFF Research Database (Denmark)

    Gryseels, Sophie; Amissah, Diana; Durnez, Lies;

    2012-01-01

    in Ghana, from which we cultivated amoeboid protozoa and mycobacteria. M. ulcerans was not isolated, but other mycobacteria were as frequently isolated from intracellular as from extracellular sources, suggesting that they commonly infect amoebae in nature. We screened the samples as well as the amoeba...... cultures for the M. ulcerans markers IS2404, IS2606 and KR-B. IS2404 was detected in 2% of the environmental samples and in 4% of the amoeba cultures. The IS2404 positive amoeba cultures included up to 5 different protozoan species, and originated both from Buruli ulcer endemic and non-endemic communities....... Conclusions/Significance This is the first report of experimental infection of amoebae with M. ulcerans and of the detection of the marker IS2404 in amoeba cultures isolated from the environment. We conclude that amoeba are potential natural hosts for M. ulcerans, yet remain sceptical about their implication...

  11. Amoeba-inspired nanoarchitectonic computing implemented using electrical Brownian ratchets.

    Science.gov (United States)

    Aono, M; Kasai, S; Kim, S-J; Wakabayashi, M; Miwa, H; Naruse, M

    2015-06-12

    In this study, we extracted the essential spatiotemporal dynamics that allow an amoeboid organism to solve a computationally demanding problem and adapt to its environment, thereby proposing a nature-inspired nanoarchitectonic computing system, which we implemented using a network of nanowire devices called 'electrical Brownian ratchets (EBRs)'. By utilizing the fluctuations generated from thermal energy in nanowire devices, we used our system to solve the satisfiability problem, which is a highly complex combinatorial problem related to a wide variety of practical applications. We evaluated the dependency of the solution search speed on its exploration parameter, which characterizes the fluctuation intensity of EBRs, using a simulation model of our system called 'AmoebaSAT-Brownian'. We found that AmoebaSAT-Brownian enhanced the solution searching speed dramatically when we imposed some constraints on the fluctuations in its time series and it outperformed a well-known stochastic local search method. These results suggest a new computing paradigm, which may allow high-speed problem solving to be implemented by interacting nanoscale devices with low power consumption.

  12. SPATIAL-VARIANT MORPHOLOGICAL FILTERS WITH NONLOCAL-PATCH-DISTANCE-BASED AMOEBA KERNEL FOR IMAGE DENOISING

    Directory of Open Access Journals (Sweden)

    Shuo Yang

    2015-01-01

    Full Text Available Filters of the Spatial-Variant amoeba morphology can preserve edges better, but with too much noise being left. For better denoising, this paper presents a new method to generate structuring elements for Spatially-Variant amoeba morphology.  The amoeba kernel in the proposed strategy is divided into two parts: one is the patch distance based amoeba center, and another is the geodesic distance based amoeba boundary, by which the nonlocal patch distance and local geodesic distance are both taken into consideration. Compared to traditional amoeba kernel, the new one has more stable center and its shape can be less influenced by noise in pilot image. What’s more important is that the nonlocal processing approach can induce a couple of adjoint dilation and erosion, and combinations of them can construct adaptive opening, closing, alternating sequential filters, etc. By designing the new amoeba kernel, a family of morphological filters therefore is derived. Finally, this paper presents a series of results on both synthetic and real images along with comparisons with current state-of-the-art techniques, including novel applications to medical image processing and noisy SAR image restoration.

  13. Detection and Identification of Free-living Amoeba from Environmental Water in Taiwan by PCR Method

    Science.gov (United States)

    Tsai, H. F.; Hsu, B. M.; Huang, K. H.; She, C. Y.; Kao, P. M.; Shen, S. M.; Tseng, S. F.; Chen, J. S.

    2012-04-01

    Acanthamoeba, Naegleria, Balamuthia and Hartmannella all belong to free-living amoebae that are present ubiquitously in the environment including water, soil, and air. Free-living amoebae are parasites which can infect humans and can lead to serious illness and even death. The aim of this study is to investigate the presence of free-living amoebae in aquatic environment in Taiwan, and to compare the differences between Acanthamoeba and Naegleria in diverse cultivation methods and conditions. In this study, we used molecular method by PCR amplification with specific primers to analyze the occurrence of free-living amoebae. We collected 176 samples from environmental water including drinking water treatment plants, stream water, and hot spring recreational areas in Taiwan. Based on the results of PCR, 43 water samples (24.4%) were detected positive for free-living amoebae. The most common Acanthamoeba genotype isolated from samples including T2, T4, T5, T12, and T15. N. australiensis and N. lovaniensis were also identified by molecular biology techniques. Furthermore, we found that both Acanthamoeba and Naegleria can be cultured by PYG in 30° C, but not all free-living amoebae can be isolated and enriched by using storage-cultivation method. Because of the widespread presence of Acanthamoeba and Naegleria in aquatic environments, the water quality and safety of aquatic environments should be more conscious in Taiwan and worldwide. Keywords: free-living amoebae; Acanthamoeba; Naegleria; Balamuthia; Hartmannella; PCR

  14. Bitter tastant responses in the amoeba Dictyostelium correlate with rat and human taste assays.

    Science.gov (United States)

    Cocorocchio, Marco; Ives, Robert; Clapham, David; Andrews, Paul L R; Williams, Robin S B

    2016-01-01

    Treatment compliance is reduced when pharmaceutical compounds have a bitter taste and this is particularly marked for paediatric medications. Identification of bitter taste liability during drug discovery utilises the rat in vivo brief access taste aversion (BATA) test which apart from animal use is time consuming with limited throughput. We investigated the suitability of using a simple, non-animal model, the amoeba Dictyostelium discoideum to investigate taste-related responses and particularly identification of compounds with a bitter taste liability. The effect of taste-related compounds on Dictyostelium behaviour following acute exposure (15 minutes) was monitored. Dictyostelium did not respond to salty, sour, umami or sweet tasting compounds, however, cells rapidly responded to bitter tastants. Using time-lapse photography and computer-generated quantification to monitor changes in cell membrane movement, we developed an assay to assess the response of Dictyostelium to a wide range of structurally diverse known bitter compounds and blinded compounds. Dictyostelium showed varying responses to the bitter tastants, with IC50 values providing a rank order of potency. Comparison of Dictyostelium IC50 values to those observed in response to a similar range of compounds in the rat in vivo brief access taste aversion test showed a significant (p = 0.0172) positive correlation between the two models, and additionally a similar response to that provided by a human sensory panel assessment test. These experiments demonstrate that Dictyostelium may provide a suitable model for early prediction of bitterness for novel tastants and drugs. Interestingly, a response to bitter tastants appears conserved from single-celled amoebae to humans. PMID:26708104

  15. Pseudomonas aeruginosa uses type III secretion system to kill biofilm-associated amoebae

    DEFF Research Database (Denmark)

    Matz, Carsten; Moreno, Ana Maria; Alhede, Morten;

    2008-01-01

    should allow opportunistic pathogenic bacteria to utilize their eukaryote-targeting arsenal to attack and exploit protozoan host cells. Studying cocultures of the environmental pathogen Pseudomonas aeruginosa and the amoeba Acanthamoeba castellanii, we found that P. aeruginosa rapidly colonized...... and killed biofilm-associated amoebae by a quorum-sensing independent mechanism. Analysis of the amoeba-induced transcriptome indicated the involvement of the P. aeruginosa type III secretion system (T3SS) in this interaction. A comparison of mutants with specific defects in the T3SS demonstrated the use...

  16. Using testate amoeba as potential biointegrators of atmospheric deposition of phenanthrene (polycyclic aromatic hydrocarbon) on "moss/soil interface-testate amoeba community" microecosystems.

    Science.gov (United States)

    Meyer, Caroline; Desalme, Dorine; Bernard, Nadine; Binet, Philippe; Toussaint, Marie-Laure; Gilbert, Daniel

    2013-03-01

    Microecosystem models could allow understanding of the impacts of pollutants such as polycyclic aromatic hydrocarbons on ecosystem functioning. We studied the effects of atmospheric phenanthrene (PHE) deposition on the microecosystem "moss/soil interface-testate amoebae (TA) community" over a 1-month period under controlled conditions. We found that PHE had an impact on the microecosystem. PHE was accumulated by the moss/soil interface and was significantly negatively correlated (0.4 < r(2) < 0.7) with total TA abundance and the abundance of five species of TA (Arcella sp., Centropyxis sp., Nebela lageniformis, Nebela tincta and Phryganella sp.). Among sensitive species, species with a superior trophic level (determined by the test aperture size) were more sensitive than other TA species. This result suggests that links between microbial groups in the microecosystems are disrupted by PHE and that this pollutant had effects both direct (ingestion of the pollutant or direct contact with cell) and/or indirect (decrease of prey) on the TA community. The TA community seems to offer a potential integrative tool to understand mechanisms and processes by which the atmospheric PHE deposition affects the links between microbial communities.

  17. Endosymbiotic bacteria associated with nematodes, ticks and amoebae.

    Science.gov (United States)

    Taylor, Mark; Mediannikov, Oleg; Raoult, Didier; Greub, Gilbert

    2012-02-01

    Endosymbiosis is a mutualistic, parasitic or commensal symbiosis in which one symbiont is living within the body of another organism. Such symbiotic relationship with free-living amoebae and arthropods has been reported with a large biodiversity of microorganisms, encompassing various bacterial clades and to a lesser extent some fungi and viruses. By contrast, current knowledge on symbionts of nematodes is still mainly restricted to Wolbachia and its interaction with filarial worms that lead to increased pathogenicity of the infected nematode. In this review article, we aim to highlight the main characteristics of symbionts in term of their ecology, host cell interactions, parasitism and co-evolution, in order to stimulate future research in a field that remains largely unexplored despite the availability of modern tools. PMID:22126456

  18. Evolutionary dynamics of altruism and cheating among social amoebas.

    Science.gov (United States)

    Brännström, A; Dieckmann, U

    2005-08-01

    Dictyostelium discoideum is a eukaryotic amoeba, which, when starvation is imminent, aggregates to form fruiting bodies consisting of a stalk of reproductively dead cells that supports spores. Because different clones may be involved in such aggregations, cheater strategies may emerge that allocate a smaller fraction of cells to stalk formation, thus gaining a reproductive advantage. In this paper, we model the evolutionary dynamics of allocation strategies in Dictyostelium under the realistic assumption that the number of clones involved in aggregations follows a random distribution. By determining the full course of evolutionary dynamics, we show that evolutionary branching in allocation strategies may occur, resulting in dimorphic populations that produce stalkless and stalked fruiting bodies. We also demonstrate that such dimorphisms are more likely to emerge when the variation in the number of clones involved in aggregations is large.

  19. The role of giant viruses of amoebas in humans.

    Science.gov (United States)

    Colson, Philippe; Aherfi, Sarah; La Scola, Bernard; Raoult, Didier

    2016-06-01

    Since 2003, dozens of giant viruses that infect amoebas (GVA), including mimiviruses and marseilleviruses, have been discovered. These giants appear to be common in our biosphere. From the onset, their presence and possible pathogenic role in humans have been serendipitously observed or investigated using a broad range of technological approaches, including culture, electron microscopy, serology and various techniques based on molecular biology. The link between amoebal mimiviruses and pneumonia has been the most documented, with findings that fulfill several of the criteria considered as proof of viral disease causation. Regarding marseilleviruses, they have been mostly described in asymptomatic persons, and in a lymph node adenitis. The presence and impact of GVA in humans undoubtedly deserve further investigation in medicine.

  20. Pathogen vacuole purification from legionella-infected amoeba and macrophages.

    Science.gov (United States)

    Hoffmann, Christine; Finsel, Ivo; Hilbi, Hubert

    2013-01-01

    Legionella pneumophila replicates intracellularly in environmental and immune phagocytes within a unique membrane-bound compartment, the Legionella-containing vacuole (LCV). Formation of LCVs is strictly dependent on the Icm/Dot type IV secretion system and the translocation of "effector" proteins into the cell. Some effector proteins decorate the LCV membrane and subvert host cell vesicle trafficking pathways. Here we describe a method to purify intact LCVs from Dictyostelium discoideum amoebae and RAW 264.7 murine macrophages. The method comprises a two-step protocol: first, LCVs are enriched by immuno-magnetic separation using an antibody against a bacterial effector protein specifically localizing to the LCV membrane, and second, the LCVs are further purified by density gradient centrifugation. The purified LCVs can be characterized by proteomics and other biochemical approaches.

  1. Genetic variation in the free-living amoeba Naegleria fowleri.

    Science.gov (United States)

    Pélandakis, M; De Jonckheere, J F; Pernin, P

    1998-08-01

    In this study, 30 strains of the pathogenic free-living amoeba Naegleria fowleri were investigated by using the randomly amplified polymorphic DNA (RAPD) method. The present study confirmed our previous finding that RAPD variation is not correlated with geographical origin. In particular, Mexican strains belong to the variant previously detected in Asia, Europe, and the United States. In France, surprisingly, strains from Cattenom gave RAPD patterns identical to those of the Japanese strains. In addition, all of these strains, together with an additional French strain from Chooz, exhibited similarities to South Pacific strains. The results also confirmed the presence of numerous variants in Europe, whereas only two variants were detected in the United States. The two variants found in the United States were different from the South Pacific variants. These findings do not support the previous hypothesis concerning the origin and modes of dispersal of N. fowleri.

  2. Streaming instability of slime mold amoebae: An analytical model

    Science.gov (United States)

    Höfer, Thomas; Maini, Philip K.

    1997-08-01

    During the aggregation of amoebae of the cellular slime mould Dictyostelium, the interaction of chemical waves of the signaling molecule cAMP with cAMP-directed cell movement causes the breakup of a uniform cell layer into branching patterns of cell streams. Recent numerical and experimental investigations emphasize the pivotal role of the cell-density dependence of the chemical wave speed for the occurrence of the streaming instability. A simple, analytically tractable, model of Dictyostelium aggregation is developed to test this idea. The interaction of cAMP waves with cAMP-directed cell movement is studied in the form of coupled dynamics of wave front geometries and cell density. Comparing the resulting explicit instability criterion and dispersion relation for cell streaming with the previous findings of model simulations and numerical stability analyses, a unifying interpretation of the streaming instability as a cAMP wave-driven chemotactic instability is proposed.

  3. Large scale spontaneous synchronization of cell cycles in amoebae

    Science.gov (United States)

    Segota, Igor; Boulet, Laurent; Franck, Carl

    2014-03-01

    Unicellular eukaryotic amoebae Dictyostelium discoideum are generally believed to grow in their vegetative state as single cells until starvation, when their collective aspect emerges and they differentiate to form a multicellular slime mold. While major efforts continue to be aimed at their starvation-induced social aspect, our understanding of population dynamics and cell cycle in the vegetative growth phase has remained incomplete. We show that substrate-growtn cell populations spontaneously synchronize their cell cycles within several hours. These collective population-wide cell cycle oscillations span millimeter length scales and can be completely suppressed by washing away putative cell-secreted signals, implying signaling by means of a diffusible growth factor or mitogen. These observations give strong evidence for collective proliferation behavior in the vegetative state and provide opportunities for synchronization theories beyond classic Kuramoto models.

  4. Intra-amoeba multiplication induces chemotaxis and biofilm colonization and formation for Legionella.

    Science.gov (United States)

    Bigot, Renaud; Bertaux, Joanne; Frere, Jacques; Berjeaud, Jean-Marc

    2013-01-01

    Legionella pneumophila, a facultative intracellular bacterium, is the causative agent of legionellosis. In the environment this pathogenic bacterium colonizes the biofilms as well as amoebae, which provide a rich environment for the replication of Legionella. When seeded on pre-formed biofilms, L. pneumophila was able to establish and survive and was only found at the surface of the biofilms. Different phenotypes were observed when the L. pneumophila, used to implement pre-formed biofilms or to form mono-species biofilms, were cultivated in a laboratory culture broth or had grown intracellulary within the amoeba. Indeed, the bacteria, which developed within the amoeba, formed clusters when deposited on a solid surface. Moreover, our results demonstrate that multiplication inside the amoeba increased the capacity of L. pneumophila to produce polysaccharides and therefore enhanced its capacity to establish biofilms. Finally, it was shown that the clusters formed by L. pneumophila were probably related to the secretion of a chemotaxis molecular agent.

  5. Toxoplasma gondii: uptake and survival of oocysts in free-living amoebae.

    Science.gov (United States)

    Winiecka-Krusnell, Jadwiga; Dellacasa-Lindberg, Isabel; Dubey, J P; Barragan, Antonio

    2009-02-01

    Waterborne transmission of the oocyst stage of Toxoplasma gondii can cause outbreaks of clinical toxoplasmosis in humans and infection of marine mammals. In water-related environments and soil, free-living amoebae are considered potential carriers of various pathogens, but knowledge on interactions with parasitic protozoa remains elusive. In the present study, we assessed whether the free-living Acanthamoeba castellanii, due to its phagocytic activity, can interact with T. gondii oocysts. We report that amoebae can internalize T. gondii oocysts by active uptake. Intracellular oocysts in amoebae rarely underwent phagocytic lysis, retained viability and established infection in mice. Interaction of T. gondii with amoebae did not reduce the infectivity and pathogenicity of oocysts even after prolonged co-cultivation. Our results show that uptake of oocysts by A. castellanii does not restrain the transmission of T. gondii in a murine infection model.

  6. Free-living amoebae in sediments from the Lascaux Cave in France.

    Directory of Open Access Journals (Sweden)

    Garcia-Sanchez A.M.

    2013-01-01

    Full Text Available The Lascaux Cave in France is an old karstic channel where the running waters are collected in a pool and pumped to the exterior. It is well-known that water bodies in the vicinity of humans are suspected to be reservoirs of amoebae and associated bacteria. In fact, the free-living amoebae Acanthamoeba astronyxis, Acanthamoeba castellanii, Acanthamoeba sp. and Hartmannella vermiformis were identif ied in the sediments of the cave using phylogenetic analyses and morphological traits. Lascaux Cave sediments and rock walls are wet due to a relative humidity near saturation and water condensation, and this environment and the presence of abundant bacterial communities constitute an ideal habitat for amoebae. The data suggest the need to carry out a detailed survey on all the cave compartments in order to determine the relationship between amoebae and pathogenic bacteria.

  7. Intra-amoeba multiplication induces chemotaxis and biofilm colonization and formation for Legionella.

    Directory of Open Access Journals (Sweden)

    Renaud Bigot

    Full Text Available Legionella pneumophila, a facultative intracellular bacterium, is the causative agent of legionellosis. In the environment this pathogenic bacterium colonizes the biofilms as well as amoebae, which provide a rich environment for the replication of Legionella. When seeded on pre-formed biofilms, L. pneumophila was able to establish and survive and was only found at the surface of the biofilms. Different phenotypes were observed when the L. pneumophila, used to implement pre-formed biofilms or to form mono-species biofilms, were cultivated in a laboratory culture broth or had grown intracellulary within the amoeba. Indeed, the bacteria, which developed within the amoeba, formed clusters when deposited on a solid surface. Moreover, our results demonstrate that multiplication inside the amoeba increased the capacity of L. pneumophila to produce polysaccharides and therefore enhanced its capacity to establish biofilms. Finally, it was shown that the clusters formed by L. pneumophila were probably related to the secretion of a chemotaxis molecular agent.

  8. Intra-amoeba multiplication induces chemotaxis and biofilm colonization and formation for Legionella.

    Science.gov (United States)

    Bigot, Renaud; Bertaux, Joanne; Frere, Jacques; Berjeaud, Jean-Marc

    2013-01-01

    Legionella pneumophila, a facultative intracellular bacterium, is the causative agent of legionellosis. In the environment this pathogenic bacterium colonizes the biofilms as well as amoebae, which provide a rich environment for the replication of Legionella. When seeded on pre-formed biofilms, L. pneumophila was able to establish and survive and was only found at the surface of the biofilms. Different phenotypes were observed when the L. pneumophila, used to implement pre-formed biofilms or to form mono-species biofilms, were cultivated in a laboratory culture broth or had grown intracellulary within the amoeba. Indeed, the bacteria, which developed within the amoeba, formed clusters when deposited on a solid surface. Moreover, our results demonstrate that multiplication inside the amoeba increased the capacity of L. pneumophila to produce polysaccharides and therefore enhanced its capacity to establish biofilms. Finally, it was shown that the clusters formed by L. pneumophila were probably related to the secretion of a chemotaxis molecular agent. PMID:24205008

  9. Dynamics of hybrid amoeba proteus containing zoochlorellae studied using fluorescence spectroscopy

    Science.gov (United States)

    Liu, C.-H.; Fong, B. A.; Alfano, S. A., Jr.; Rakhlin, I.; Wang, W. B.; Ni, X. H.; Yang, Y. L.; Zhou, F.; Zuzolo, R. C.; Alfano, R. R.

    2011-03-01

    The microinjection of organelles, plants, particles or chemical solutions into Amoeba proteus coupled with spectroscopic analysis and observed for a period of time provides a unique new model for cancer treatment and studies. The amoeba is a eukaryote having many similar features of mammalian cells. The amoeba biochemical functions monitored spectroscopically can provide time sequence in vivo information about many metabolic transitions and metabolic exchanges between cellar organelles and substances microinjected into the amoeba. It is possible to microinject algae, plant mitochondria, drugs or carcinogenic solutions followed by recording the native fluorescence spectra of these composites. This model can be used to spectroscopically monitor the pre-metabolic transitions in developing diseased cells such as a cancer. Knowing specific metabolic transitions could offer solutions to inhibit cancer or reverse it as well as many other diseases. In the present study a simple experiment was designed to test the feasibility of this unique new model by injecting algae and chloroplasts into amoeba. The nonradiative dynamics found from these composites are evidence in terms of the emission ratios between the intensities at 337nm and 419nm; and 684nm bands. There were reductions in the metabolic and photosynthetic processes in amoebae that were microinjected with chloroplasts and zoochlorellae as well of those amoebae that ingested the algae and chloroplasts. The changes in the intensity of the emissions of the peaks indicate that the zoochlorellae lived in the amoebae for ten days. Spectral changes in intensity under the UV and 633nm wavelength excitation are from the energy transfer of DNA and RNA, protein-bound chromophores and chlorophylls present in zoochlorellae undergoing photosynthesis. The fluorescence spectroscopic probes established the biochemical interplay between the cell organelles and the algae present in the cell cytoplasm. This hybrid state is indicative

  10. TESTATE AMOEBAE COMMUNITIES FROM CAVES OF SOME TERRITORIES IN EUROPEAN RUSSIA AND NORTH-EASTERN ITALY

    OpenAIRE

    Mazei, Yuri; Belyakova, Olga; Trulova, Alisa; Guidolin, Laura; Coppellotti, Olimpia

    2012-01-01

    The species composition of testate amoebae in caves from European Russia and North-East Italy was studied. Twenty-seven species were identified from various habitats inside caves (moist substratum on floor, guano, sediments of cave streams and pools, water droplets and bacterial mats on rocky surfaces). In caves of simple structure (without differing types of habitats), the species richness of testate amoebae was far lower than in that from habitats outside the caves. In heterogeneous caves, ...

  11. Conserved mechanisms of Mycobacterium marinum pathogenesis within the environmental amoeba Acanthamoeba castellanii.

    Science.gov (United States)

    Kennedy, George M; Morisaki, J Hiroshi; Champion, Patricia A DiGiuseppe

    2012-03-01

    Mycobacterium marinum is a waterborne mycobacterial pathogen. Due to their common niche, protozoa likely represent natural hosts for M. marinum. We demonstrate that the ESX-1 secretion system is required for M. marinum pathogenesis and that M. marinum utilizes actin-based motility in amoebae. Therefore, at least two virulence pathways used by M. marinum in macrophages are conserved during M. marinum infection of amoebae.

  12. Seasonal changes in Sphagnum peatland testate amoeba communities along a hydrological gradient

    OpenAIRE

    Katarzyna Marcisz; Łukasz Lamentowicz; Sandra Slowińska; Michal Slowinski; Witold Muszak; Mariusz Lamentowicz

    2014-01-01

    Testate amoebae are an abundant and functionally important group of protists in peatlands, but little is known about the seasonal patterns of their communities. We investigated the relationships between testate amoeba diversity and community structure and water table depth and light conditions (shading vs. insolation) in a Sphagnum peatland in Northern Poland (Linje mire) in spring and summer 2010. We monitored the water table at five sites across the peatland and collected Sphagnum samples i...

  13. Amoeba-related health risk in drinking water systems: could monitoring of amoebae be a complementary approach to current quality control strategies?

    Science.gov (United States)

    Codony, Francesc; Pérez, Leonardo Martín; Adrados, Bárbara; Agustí, Gemma; Fittipaldi, Mariana; Morató, Jordi

    2012-01-01

    Culture-based methods for fecal indicator microorganisms are the standard protocol to assess potential health risk from drinking water systems. However, these traditional fecal indicators are inappropriate surrogates for disinfection-resistant fecal pathogens and the indigenous pathogens that grow in drinking water systems. There is now a range of molecular-based methods, such as quantitative PCR, which allow detection of a variety of pathogens and alternative indicators. Hence, in addition to targeting total Escherichia coli (i.e., dead and alive) for the detection of fecal pollution, various amoebae may be suitable to indicate the potential presence of pathogenic amoeba-resisting microorganisms, such as Legionellae. Therefore, monitoring amoeba levels by quantitative PCR could be a useful tool for directly and indirectly evaluating health risk and could also be a complementary approach to current microbial quality control strategies for drinking water systems.

  14. Ecology of testate amoebae in Dajiuhu peatland of Shennongjia Mountains, China, in relation to hydrology

    Institute of Scientific and Technical Information of China (English)

    Yangmin QIN; Richard J PAYNE; Yansheng GU; Xianyu HUANG; Hongmei WANG

    2012-01-01

    This study investigates the testate amoeba communities of a large peatland in Central China.The ecology and seasonal variability of testate amoeba communitics were studied during 2009-2010.Investigation of environmental controls using ordination showed that the relationship between testate amoeba communities and depth to water table (DWT) and pH are extremely weak.The small proportion of variance explained by water table depth here (only 1.9% in the full data) shows that the hydrological control is weaker than we expected in this peatland,and weaker than any study we are aware of using a similar methodology.Attempts to develop speciesenvironment (transfer function) models or identify indicator species for future palaeoecological studies were unsuccessful.Previous large-scale studies of peatland testate amoeba ecology havc been largely restricted to Europe and North America and results have been relatively consistent among studies.Our results contrast with this consensus and suggest that at least in minerotrophic peatlands in China testate amoeba communities may be primarily controlled by different environmental variables.In China,testate amoebae have been relatively little studied but may prove to be valuable for a variety of applications in palaeoecology and biomonitoring and much further work is required.

  15. Amoeba-Inspired Heuristic Search Dynamics for Exploring Chemical Reaction Paths.

    Science.gov (United States)

    Aono, Masashi; Wakabayashi, Masamitsu

    2015-09-01

    We propose a nature-inspired model for simulating chemical reactions in a computationally resource-saving manner. The model was developed by extending our previously proposed heuristic search algorithm, called "AmoebaSAT [Aono et al. 2013]," which was inspired by the spatiotemporal dynamics of a single-celled amoeboid organism that exhibits sophisticated computing capabilities in adapting to its environment efficiently [Zhu et al. 2013]. AmoebaSAT is used for solving an NP-complete combinatorial optimization problem [Garey and Johnson 1979], "the satisfiability problem," and finds a constraint-satisfying solution at a speed that is dramatically faster than one of the conventionally known fastest stochastic local search methods [Iwama and Tamaki 2004] for a class of randomly generated problem instances [ http://www.cs.ubc.ca/~hoos/5/benchm.html ]. In cases where the problem has more than one solution, AmoebaSAT exhibits dynamic transition behavior among a variety of the solutions. Inheriting these features of AmoebaSAT, we formulate "AmoebaChem," which explores a variety of metastable molecules in which several constraints determined by input atoms are satisfied and generates dynamic transition processes among the metastable molecules. AmoebaChem and its developed forms will be applied to the study of the origins of life, to discover reaction paths for which expected or unexpected organic compounds may be formed via unknown unstable intermediates and to estimate the likelihood of each of the discovered paths.

  16. Accelerated Molecular Dynamics Simulations with the AMOEBA Polarizable Force Field on Graphics Processing Units.

    Science.gov (United States)

    Lindert, Steffen; Bucher, Denis; Eastman, Peter; Pande, Vijay; McCammon, J Andrew

    2013-11-12

    The accelerated molecular dynamics (aMD) method has recently been shown to enhance the sampling of biomolecules in molecular dynamics (MD) simulations, often by several orders of magnitude. Here, we describe an implementation of the aMD method for the OpenMM application layer that takes full advantage of graphics processing units (GPUs) computing. The aMD method is shown to work in combination with the AMOEBA polarizable force field (AMOEBA-aMD), allowing the simulation of long time-scale events with a polarizable force field. Benchmarks are provided to show that the AMOEBA-aMD method is efficiently implemented and produces accurate results in its standard parametrization. For the BPTI protein, we demonstrate that the protein structure described with AMOEBA remains stable even on the extended time scales accessed at high levels of accelerations. For the DNA repair metalloenzyme endonuclease IV, we show that the use of the AMOEBA force field is a significant improvement over fixed charged models for describing the enzyme active-site. The new AMOEBA-aMD method is publicly available (http://wiki.simtk.org/openmm/VirtualRepository) and promises to be interesting for studying complex systems that can benefit from both the use of a polarizable force field and enhanced sampling.

  17. Potentially pathogenic free-living amoebae in contact lenses of the asymptomatic contact lens wearers.

    Directory of Open Access Journals (Sweden)

    Maryam Niyyati

    2014-03-01

    Full Text Available Free-living amoebae (FLA including Acanthamoeba spp. and Hartmannella spp. are the causative agents of serious corneal infection especially within contact lens wearers. Thus contact lenses and their storage case could be a suitable niche for potentially pathogenic amoebae. The main objective of the present study was to evaluate the contamination of contact lenses to free living amoebae using morphological and sequencing based methods.Overall, 90 volunteers provided their contact lenses. All volunteers wore soft contact lenses. Both lenses were cultured in the same plate. Forty-eight of the volunteers were medical and dentistry student and 42 were ophthalmology attendees of hospitals in Tehran, Iran. All of the samples were inoculated to non-nutrient medium and monitored daily for the outgrowth of the amoebae. PCR and sequencing were performed using various primer pairs.Of the 90 volunteers, 9 (10% were positive for free-living amoebae outgrowth. Morphological analysis revealed that 3 isolates were belonged to Hartmannella genus according to small round cysts and 6 isolates were belonged to Acanthamoeba genus based on the star shape of endocysts. Sequencing revealed that Acanthamoeba belonged to T4, T3 and T5 genotype. Hartmannella were also belonged to vermiformis species.The presence of potentially pathogenic free living amoebae including Acanthamoeba and Hartmannella could be a high risk for people using soft contact lenses. These results revealed that improved clarification and professional recommendations for contact lens wearers is of utmost importance.

  18. Permissiveness of freshly isolated environmental strains of amoebae for growth of Legionella pneumophila.

    Science.gov (United States)

    Dupuy, Mathieu; Binet, Marie; Bouteleux, Celine; Herbelin, Pascaline; Soreau, Sylvie; Héchard, Yann

    2016-03-01

    Legionella pneumophila is a pathogenic bacterium commonly found in water and responsible for severe pneumonia. Free-living amoebae are protozoa also found in water, which feed on bacteria by phagocytosis. Under favorable conditions, some L. pneumophila are able to resist phagocytic digestion and even multiply within amoebae. However, it is not clear whether L. pneumophila could infect at a same rate a large range of amoebae or if there is some selectivity towards specific amoebal genera or strains. Also, most studies have been performed using collection strains and not with freshly isolated strains. In our study, we assess the permissiveness of freshly isolated environmental strains of amoebae, belonging to three common genera (i.e. Acanthamoeba, Naegleria and Vermamoeba), for growth of L. pneumophila at three different temperatures. Our results indicated that all the tested strains of amoebae were permissive to L. pneumophila Lens and that there was no significant difference between the strains. Intracellular proliferation was more efficient at a temperature of 40°C. In conclusion, our work suggests that, under favorable conditions, virulent strains of L. pneumophila could equally infect a large number of isolates of common freshwater amoeba genera.

  19. Presence of free-living amoebae in portable and stationary eye wash stations

    Energy Technology Data Exchange (ETDEWEB)

    Tyndall, R.L.; Lyle, M.M.; Ironside, K.S.

    1987-11-01

    Portable and stationary eye wash stations were tested for the presence of free-living amoebae. Such amoebae may be found in potable waters, and at least one genera, the Acanthamoebae, can cause severe infections when introduced into traumatized eyes. Concentrates or filtrates of water from eye wash stations were placed on nonnutrient agar plates seeded with Escherichia coli. Resultant outgrowths of free-living amoebae, which were morphologically identified as mixtures of Hartmannella and Acanthamoebae, were inoculated intranasally into weanling mice. Subsequently, brain and lung tissues from inject mice were tested for amoebae as an indication of persistent infection. Acanthamoebae and Hartmannella were detected in some eye wash stations at each of four test sites. Both portable and stationary stations harbored Acanthamoebae. Some of the isolates caused persistent pulmonary infection but were not isolated from brain tissue. Flushing stationary eye wash stations temporarily reduced the number of stations positive for amoebae. Treatment of portable stations with 25 ppm of free chlorine also reduced the number of stations harboring amoebae but caused corrosion in some of the stations.

  20. Amoeba-Inspired Heuristic Search Dynamics for Exploring Chemical Reaction Paths.

    Science.gov (United States)

    Aono, Masashi; Wakabayashi, Masamitsu

    2015-09-01

    We propose a nature-inspired model for simulating chemical reactions in a computationally resource-saving manner. The model was developed by extending our previously proposed heuristic search algorithm, called "AmoebaSAT [Aono et al. 2013]," which was inspired by the spatiotemporal dynamics of a single-celled amoeboid organism that exhibits sophisticated computing capabilities in adapting to its environment efficiently [Zhu et al. 2013]. AmoebaSAT is used for solving an NP-complete combinatorial optimization problem [Garey and Johnson 1979], "the satisfiability problem," and finds a constraint-satisfying solution at a speed that is dramatically faster than one of the conventionally known fastest stochastic local search methods [Iwama and Tamaki 2004] for a class of randomly generated problem instances [ http://www.cs.ubc.ca/~hoos/5/benchm.html ]. In cases where the problem has more than one solution, AmoebaSAT exhibits dynamic transition behavior among a variety of the solutions. Inheriting these features of AmoebaSAT, we formulate "AmoebaChem," which explores a variety of metastable molecules in which several constraints determined by input atoms are satisfied and generates dynamic transition processes among the metastable molecules. AmoebaChem and its developed forms will be applied to the study of the origins of life, to discover reaction paths for which expected or unexpected organic compounds may be formed via unknown unstable intermediates and to estimate the likelihood of each of the discovered paths. PMID:26129639

  1. Permissiveness of freshly isolated environmental strains of amoebae for growth of Legionella pneumophila.

    Science.gov (United States)

    Dupuy, Mathieu; Binet, Marie; Bouteleux, Celine; Herbelin, Pascaline; Soreau, Sylvie; Héchard, Yann

    2016-03-01

    Legionella pneumophila is a pathogenic bacterium commonly found in water and responsible for severe pneumonia. Free-living amoebae are protozoa also found in water, which feed on bacteria by phagocytosis. Under favorable conditions, some L. pneumophila are able to resist phagocytic digestion and even multiply within amoebae. However, it is not clear whether L. pneumophila could infect at a same rate a large range of amoebae or if there is some selectivity towards specific amoebal genera or strains. Also, most studies have been performed using collection strains and not with freshly isolated strains. In our study, we assess the permissiveness of freshly isolated environmental strains of amoebae, belonging to three common genera (i.e. Acanthamoeba, Naegleria and Vermamoeba), for growth of L. pneumophila at three different temperatures. Our results indicated that all the tested strains of amoebae were permissive to L. pneumophila Lens and that there was no significant difference between the strains. Intracellular proliferation was more efficient at a temperature of 40°C. In conclusion, our work suggests that, under favorable conditions, virulent strains of L. pneumophila could equally infect a large number of isolates of common freshwater amoeba genera. PMID:26832643

  2. Changes in Structure and Functioning of Protist (Testate Amoebae) Communities Due to Conversion of Lowland Rainforest into Rubber and Oil Palm Plantations

    Science.gov (United States)

    Krashevska, Valentyna; Klarner, Bernhard; Widyastuti, Rahayu; Maraun, Mark; Scheu, Stefan

    2016-01-01

    Large areas of tropical rainforest are being converted to agricultural and plantation land uses, but little is known of biodiversity and ecological functioning under these replacement land uses. We investigated the effects of conversion of rainforest into jungle rubber, intensive rubber and oil palm plantations on testate amoebae, diverse and functionally important protists in litter and soil. Living testate amoebae species richness, density and biomass were all lower in replacement land uses than in rainforest, with the impact being more pronounced in litter than in soil. Similar abundances of species of high and low trophic level in rainforest suggest that trophic interactions are more balanced, with a high number of functionally redundant species, than in rubber and oil palm. In contrast, plantations had a low density of high trophic level species indicating losses of functions. This was particularly so in oil palm plantations. In addition, the relative density of species with siliceous shells was >50% lower in the litter layer of oil palm and rubber compared to rainforest and jungle rubber. This difference suggests that rainforest conversion changes biogenic silicon pools and increases silicon losses. Overall, the lower species richness, density and biomass in plantations than in rainforest, and the changes in the functional composition of the testate amoebae community, indicate detrimental effects of rainforest conversion on the structure and functioning of microbial food webs. PMID:27463805

  3. Changes in Structure and Functioning of Protist (Testate Amoebae) Communities Due to Conversion of Lowland Rainforest into Rubber and Oil Palm Plantations.

    Science.gov (United States)

    Krashevska, Valentyna; Klarner, Bernhard; Widyastuti, Rahayu; Maraun, Mark; Scheu, Stefan

    2016-01-01

    Large areas of tropical rainforest are being converted to agricultural and plantation land uses, but little is known of biodiversity and ecological functioning under these replacement land uses. We investigated the effects of conversion of rainforest into jungle rubber, intensive rubber and oil palm plantations on testate amoebae, diverse and functionally important protists in litter and soil. Living testate amoebae species richness, density and biomass were all lower in replacement land uses than in rainforest, with the impact being more pronounced in litter than in soil. Similar abundances of species of high and low trophic level in rainforest suggest that trophic interactions are more balanced, with a high number of functionally redundant species, than in rubber and oil palm. In contrast, plantations had a low density of high trophic level species indicating losses of functions. This was particularly so in oil palm plantations. In addition, the relative density of species with siliceous shells was >50% lower in the litter layer of oil palm and rubber compared to rainforest and jungle rubber. This difference suggests that rainforest conversion changes biogenic silicon pools and increases silicon losses. Overall, the lower species richness, density and biomass in plantations than in rainforest, and the changes in the functional composition of the testate amoebae community, indicate detrimental effects of rainforest conversion on the structure and functioning of microbial food webs.

  4. Prevalence of Acanthamoeba spp. and other free-living amoebae in household water, Ohio, USA--1990-1992.

    Science.gov (United States)

    Stockman, Lauren J; Wright, Carolyn J; Visvesvara, Govinda S; Fields, Barry S; Beach, Michael J

    2011-03-01

    Knowledge of the prevalence of free-living amoebae (FLA) in US household water can provide a focus for prevention of amoeba-associated illnesses. Household water samples from two Ohio counties, collected and examined for amoebae during 1990-1992, were used to describe the prevalence of Acanthamoeba and other FLA in a household setting. Amoebae were isolated and identified by morphologic features. A total of 2,454 samples from 467 households were examined. Amoebae were found in water samples of 371 (79%) households. Sites most likely to contain amoeba were shower heads (52%) and kitchen sprayers (50%). Species of Hartmannella, Acanthamoeba, or Vahlkampfia were most common. Detection was higher in biofilm swab samples than in water samples. Detection of FLA and Acanthamoeba, at 79% and 51%, respectively, exceed estimates that have been published in previous surveys of household sources. We believe FLA are commonplace inhabitants of household water in this sample as they are in the environment.

  5. A study of nucleo-cytoplasmic large DNA viruses: detection and characterization of viruses in environmental amoeba

    OpenAIRE

    Fugas, Mariana Costa

    2012-01-01

    Tese de mestrado. Biologia (Biologia Molecular e Genética). Universidade de Lisboa, Faculdade de Ciências, 2012 Amoeba associated microorganisms (ARMs) are bacteria or viruses that share a symbiotic relationship with amoebas. Many ARMs are associated with human diseases and it has been reported the acquisition of resistance inside their host. These facts highlight the importance of finding and characterizing ARMs in a public health’s perspective. In the present work, amoebas from environme...

  6. Distribution of free-living amoebae in a treatment system of textile industrial wastewater.

    Science.gov (United States)

    Ramirez, Elizabeth; Robles, Esperanza; Martinez, Blanca; Ayala, Reynaldo; Sainz, Guadalupe; Martinez, Maria Elena; Gonzalez, Maria Elena

    2014-11-01

    Free-living amoebae have been found in soil, air and a variety of aquatic environments, but few studies have been conducted on industrial wastewater and none on wastewater from the textile industry. The aim of this study was to determine the presence and distribution of free-living amoebae in a biological treatment system that treats textile industrial wastewater. Samples were taken from input, aeration tank, sedimentation tank and output. Samples were centrifuged at 1200g for 15min, the sediment was seeded on non-nutritive agar with Enterobacter aerogenes (NNE) and the plates were incubated at 30 and 37°C. Free-living amoebae were present in all stages of the treatment system. The highest number of amoebic isolates was found in the aeration tank and no seasonal distribution was observed during the year. A total of 14 amoeba genera were isolated: Acanthamoeba, Echinamoeba, Korotnevella, Mayorella, Naegleria, Platyamoeba, Saccamoeba, Stachyamoeba, Thecamoeba, Vahlkampfia, Vannella, Vermamoeba, Vexillifera and Willaertia. The most frequently found amoebae were Acanthamoeba and Vermamoeba which were found in all treatment system stages. The constant presence and diversity of free-living amoebae in the treatment system were important findings due to the characteristics of the wastewater from the textile plant in terms of the residue content from colorants, fixers, carriers, surfactants, etc., used in fabric dyeing and finishing processes. The factors that determined the presence and distribution of amoebae in the activated sludge system were their capacity to form cysts, which allowed them to resist adverse conditions; food availability; an average temperature of 27-33°C; dissolved oxygen in average concentrations above 2mg/L, and pH in a range of 5.9-7.1.

  7. Importance of amoebae as a tool to isolate amoeba-resisting microorganisms and for their ecology and evolution: the Chlamydia paradigm.

    Science.gov (United States)

    Kebbi-Beghdadi, Carole; Greub, Gilbert

    2014-08-01

    Free-living amoebae are distributed worldwide and are frequently in contact with humans and animals. As cysts, they can survive in very harsh conditions and resist biocides and most disinfection procedures. Several microorganisms, called amoeba-resisting microorganisms (ARMs), have evolved to survive and multiply within these protozoa. Among them are many important pathogens, such as Legionella and Mycobacteria, and also several newly discovered Chlamydia-related bacteria, such as Parachlamydia acanthamoebae, Estrella lausannensis, Simkania negevensis or Waddlia chondrophila whose pathogenic role towards human or animal is strongly suspected. Amoebae represent an evolutionary crib for their resistant microorganisms since they can exchange genetic material with other ARMs and develop virulence traits that will be further used to infect other professional phagocytes. Moreover, amoebae constitute an ideal tool to isolate strict intracellular microorganisms from complex microbiota, since they will feed on other fast-growing bacteria, such as coliforms potentially present in the investigated samples. The paradigm that ARMs are likely resistant to macrophages, another phagocytic cell, and that they are likely virulent towards humans and animals is only partially true. Indeed, we provide examples of the Chlamydiales order that challenge this assumption and suggest that the ability to multiply in protozoa does not strictly correlate with pathogenicity and that we should rather use the ability to replicate in multiple and diverse eukaryotic cells as an indirect marker of virulence towards mammals. Thus, cell-culture-based microbial culturomics should be used in the future to try to discover new pathogenic bacterial species.

  8. Detection of the amoeba Entamoeba gingivalis in periodontal pockets

    Directory of Open Access Journals (Sweden)

    Bonner Mark

    2014-01-01

    Full Text Available Periodontitis is a public health issue, being one of the most prevalent diseases worldwide. However, the aetiology of the disease is still unclear: genetics of patients cannot explain the dispersed or isolated localisation of gingival pockets, while bacteria-based models are insufficient to distinguish gingivitis and periodontitis. The possible role of parasites in the establishment of periodontitis has been poorly studied until now. The aim of this project was to study a potential link between colonisation of gingival crevices by the amoeba Entamoeba gingivalis and periodontitis. In eight different dental clinics in France, samples were taken in periodontal pockets (72 or healthy sites (33, and submitted to microscopic observation and molecular identification by PCR with a new set of primers designed to specifically detect E. gingivalis. This blind sample analysis showed the strong sensitivity of PCR compared with clinical diagnosis (58/72 = 81%, and microscopy (51/65 = 78%. The results of this work show that the parasites detected by microscopy mainly – if not exclusively – belong to the species E. gingivalis and that the presence of the parasite is correlated with periodontitis.

  9. Periodic traction in migrating large amoeba of Physarum polycephalum.

    Science.gov (United States)

    Rieu, Jean-Paul; Delanoë-Ayari, Hélène; Takagi, Seiji; Tanaka, Yoshimi; Nakagaki, Toshiyuki

    2015-05-01

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

  10. 阿米巴经营%Amoeba Business

    Institute of Scientific and Technical Information of China (English)

    慈玉鹏

    2011-01-01

    阿米巴(amoeba)是一种单细胞生物,俗称变形虫.由于阿米巴这个名称来自于病原体,往往会引发人们的不愉快联想.一提到它,人们首先会想到的是这种病原虫引发的痢疾、肝脓肿、脑膜炎.然而,稻盛和夫为何要采纳这么一个比喻?难道找不出更好的词汇?确实是这样.如果先把阿米巴的致病性搁置一边,我们就可以看到,这种生物具有极强的生命力和多变性,躯体可任意伸缩,环境有利就长出伪足或者鞭毛快速行动,环境不利就变成可以长期存活而且抵抗力很强的包囊.

  11. Detection of the amoeba Entamoeba gingivalis in periodontal pockets.

    Science.gov (United States)

    Bonner, Mark; Amard, Véronique; Bar-Pinatel, Charlotte; Charpentier, Frédéric; Chatard, Jean-Michel; Desmuyck, Yvan; Ihler, Serge; Rochet, Jean-Pierre; Roux de La Tribouille, Véronique; Saladin, Luc; Verdy, Marion; Gironès, Núria; Fresno, Manuel; Santi-Rocca, Julien

    2014-01-01

    Periodontitis is a public health issue, being one of the most prevalent diseases worldwide. However, the aetiology of the disease is still unclear: genetics of patients cannot explain the dispersed or isolated localisation of gingival pockets, while bacteria-based models are insufficient to distinguish gingivitis and periodontitis. The possible role of parasites in the establishment of periodontitis has been poorly studied until now. The aim of this project was to study a potential link between colonisation of gingival crevices by the amoeba Entamoeba gingivalis and periodontitis. In eight different dental clinics in France, samples were taken in periodontal pockets (72) or healthy sites (33), and submitted to microscopic observation and molecular identification by PCR with a new set of primers designed to specifically detect E. gingivalis. This blind sample analysis showed the strong sensitivity of PCR compared with clinical diagnosis (58/72 = 81%), and microscopy (51/65 = 78%). The results of this work show that the parasites detected by microscopy mainly - if not exclusively - belong to the species E. gingivalis and that the presence of the parasite is correlated with periodontitis.

  12. Genotypic characterization of amoeba isolated from Acanthamoeba keratitis in Poland.

    Science.gov (United States)

    Derda, Monika; Solarczyk, Piotr; Cholewiński, Marcin; Hadaś, Edward

    2015-03-01

    Free-living amoebae belonging to the genus Acanthamoeba are the causative factor of many diseases. Among others, they cause Acanthamoeba keratitis (AK), a condition that usually occurs in contact lens wearers, though it is also observed in non-wearers. The number of diagnosed cases of AK increased more than eightfold during 8 years in the USA, and a proportional increase in frequency also occurred in Poland and Europe. Cases of AK are usually diagnosed late, and their therapy is difficult and rarely successful. AK is an uncommon diagnosis in Poland. The increased number of positive cases observed in our laboratory may reflect the growing at-risk population of contact lens wearers. Acanthamoeba as a genus of facultative human parasites is currently classified into 17 genotypes. Isolates belonging to seven genotypes were found to be associated with AK. One genotype in particular, T4, was found to be overrepresented in human disease. The main finding of our study is that in Poland, AK is almost always associated with the T4 genotype.

  13. Diverse sensitivity thresholds in dynamic signaling responses by social amoebae.

    Science.gov (United States)

    Wang, C Joanne; Bergmann, Adriel; Lin, Benjamin; Kim, Kyuri; Levchenko, Andre

    2012-02-28

    The complex transition from a single-cell to a multicellular life form during the formation of a fruiting body by the amoeba Dictyostelium discoideum is accompanied by a pulsatile collective signaling process that instigates chemotaxis of the constituent cells. Although the cells used for the analysis of this phenomenon are normally genetically identical (isogenic), it is not clear whether they are equally responsive to the waves of the signaling stimulus, nor is it clear how responses across the population influence collective cell behavior. Here, we found that isogenic Dictyostelium cells displayed differing sensitivities to the chemoattractant cyclic adenosine monophosphate (cAMP). Furthermore, the resulting signaling responses could be explained by a model in which cells are refractory to further stimulation for 5 to 6 min after the initial input and the signaling output is amplified, with the amplification threshold varying across the cells in the population. This pathway structure could explain intracellular amplification of the chemoattractant gradient during cell migration. The new model predicts that diverse cell responsiveness can facilitate collective cell behavior, specifically due to the presence of a small number of cells in the population with increased responsiveness that aid in propagating the initial cAMP signaling wave across the cell population. PMID:22375055

  14. Identification of amoebae implicated in the life cycle of Pfiesteria and Pfiesteria-like dinoflagellates

    Science.gov (United States)

    Peglar, M.T.; Nerad, T.A.; Anderson, O.R.; Gillevet, P.M.

    2004-01-01

    This study was undertaken to assess whether amoebae commonly found in mesohaline environments are in fact stages in the life cycles of Pfiesteria and Pfiesteria-like dinoflagellates. Primary isolations of amoebae and dinoflagellates were made from water and sediment samples from five tributaries of the Chesapeake Bay. Additional amoebae were also cloned from bioassay aquaria where fish mortality was attributed to Pfiesteria. Electron microscopy and small subunit (SSU) rRNA gene sequence analysis of these isolates clearly demonstrated that the commonly depicted amoeboid form of Pfiesteria is very likely a species of Korotnevella and is unrelated to Pfiesteria or Pfiesteria-like dinoflagellates. We have determined that the Pfiesteria and Pfiesteria-like dinoflagellates examined in this study undergo a typical homothallic life cycle without amoeboid stages. Furthermore, we have demonstrated that cloned amoebae sharing morphological characteristics described for stages in the life cycle of Pfiesteria do not transform into dinozoites. The strict clonal isolation and cultivation techniques used in this study substantially support the conclusion that the amoebae and some of the flagellates depicted in the life cycle of Pfiesteria are environmental contaminants of the Pfiesteria culture system and that the Ambush Predator Hypothesis needs to be rigorously reevaluated.

  15. Amoeba-inspired nanoarchitectonic computing: solving intractable computational problems using nanoscale photoexcitation transfer dynamics.

    Science.gov (United States)

    Aono, Masashi; Naruse, Makoto; Kim, Song-Ju; Wakabayashi, Masamitsu; Hori, Hirokazu; Ohtsu, Motoichi; Hara, Masahiko

    2013-06-18

    Biologically inspired computing devices and architectures are expected to overcome the limitations of conventional technologies in terms of solving computationally demanding problems, adapting to complex environments, reducing energy consumption, and so on. We previously demonstrated that a primitive single-celled amoeba (a plasmodial slime mold), which exhibits complex spatiotemporal oscillatory dynamics and sophisticated computing capabilities, can be used to search for a solution to a very hard combinatorial optimization problem. We successfully extracted the essential spatiotemporal dynamics by which the amoeba solves the problem. This amoeba-inspired computing paradigm can be implemented by various physical systems that exhibit suitable spatiotemporal dynamics resembling the amoeba's problem-solving process. In this Article, we demonstrate that photoexcitation transfer phenomena in certain quantum nanostructures mediated by optical near-field interactions generate the amoebalike spatiotemporal dynamics and can be used to solve the satisfiability problem (SAT), which is the problem of judging whether a given logical proposition (a Boolean formula) is self-consistent. SAT is related to diverse application problems in artificial intelligence, information security, and bioinformatics and is a crucially important nondeterministic polynomial time (NP)-complete problem, which is believed to become intractable for conventional digital computers when the problem size increases. We show that our amoeba-inspired computing paradigm dramatically outperforms a conventional stochastic search method. These results indicate the potential for developing highly versatile nanoarchitectonic computers that realize powerful solution searching with low energy consumption.

  16. Sensitivity of free-living amoeba trophozoites and cysts to water disinfectants.

    Science.gov (United States)

    Dupuy, Mathieu; Berne, Florence; Herbelin, Pascaline; Binet, Marie; Berthelot, Nelsie; Rodier, Marie-Hélène; Soreau, Sylvie; Héchard, Yann

    2014-03-01

    Free-living amoebae are naturally present in water. These protozoa could be pathogenic and could also shelter pathogenic bacteria. Thus, they are described as a potential hazard for health. Also, free-living amoebae have been described to be resistant to biocides, especially under their cyst resistant form. There are several studies on amoeba treatments but none of them compare sensitivity of trophozoites and cysts from different genus to various water disinfectants. In our study, we tested chlorine, monochloramine and chlorine dioxide on both cysts and trophozoites from three strains, belonging to the three main genera of free-living amoebae. The results show that, comparing cysts to trophozoites inactivation, only the Acanthamoeba cysts were highly more resistant to treatment than trophozoites. Comparison of the disinfectant efficiency led to conclude that chlorine dioxide was the most efficient treatment in our conditions and was particularly efficient against cysts. In conclusion, our results would help to adapt water treatments in order to target free-living amoebae in water networks.

  17. LPS-inducible factor(s) from activated macrophages mediates cytolysis of Naegleria fowleri amoebae

    Energy Technology Data Exchange (ETDEWEB)

    Cleary, S.F.; Marciano-Cabral, F.

    1986-03-01

    Soluble cytolytic factors of macrophage origin have previously been described with respect to their tumoricidal activity. The purpose of this study was to investigate the mechanism and possible factor(s) responsible for cytolysis of the amoeba Naegleria fowleri by activated peritoneal macrophages from B6C3F1 mice. Macrophages or conditioned medium (CM) from macrophage cultures were incubated with /sup 3/H-Uridine labeled amoebae. Percent specific release of label served as an index of cytolysis. Bacille Calmette-Guerin (BCG) and Corynebacterium parvum macrophages demonstrated significant cytolysis of amoebae at 24 h with an effector to target ratio of 10:1. Treatment of macrophages with inhibitors of RNA or protein synthesis blocked amoebicidal activity. Interposition of a 1 ..mu..m pore membrane between macrophages and amoebae inhibited killing. Inhibition in the presence of the membrane was overcome by stimulating the macrophages with LPS. CM from SPS-stimulated, but not unstimulated, cultures of activated macrophages was cytotoxic for amoebae. The activity was heat sensitive and was recovered from ammonium sulfate precipitation of the CM. Results indicate that amoebicidal activity is mediated by a protein(s) of macrophage origin induced by target cell contact or stimulation with LPS.

  18. Free-living freshwater amoebae differ in their susceptibility to the pathogenic bacterium Legionella pneumophila.

    Science.gov (United States)

    Dey, Rafik; Bodennec, Jacques; Mameri, Mouh Oulhadj; Pernin, Pierre

    2009-01-01

    Legionella pneumophila is known as a facultative intracellular parasite of free-living soil and freshwater amoebae, of which several species have been shown to support the growth of the pathogenic bacteria. We report for the first time the behaviour of two strains (c2c and Z503) of the amoeba Willaertia magna towards different strains of L. pneumophila serogroup 1 and compared it with Acanthamoeba castellanii and Hartmannella vermiformis, known to be L. pneumophila permissive. In contrast to the results seen with other amoebae, W. magna c2c inhibited the growth of one strain of Legionella (L. pneumophila, Paris), but not of others belonging to the same serogroup (L. pneumophila, Philadelphia and L. pneumophila, Lens). Also, the different L. pneumophila inhibited cell growth and induced cell death in A. castellanii, H. vermiformis and W. magna Z503 within 3-4 days while W. magna c2c strain remained unaffected even up to 7 days. Electron microscopy demonstrated that the formation of numerous replicative phagosomes observed within Acanthamoeba and Hartmannella is rarely seen in W. magna c2c cocultured with L. pneumophila. Moreover, the morphological differences were observed between L. pneumophila cultured either with Willaertia or other amoebae. These observations show that amoebae are not all equally permissive to L. pneumophila and highlight W. magna c2c as particularly resistant towards some strains of this bacterium.

  19. Free-living amoebae as opportunistic and non-opportunistic pathogens of humans and animals.

    Science.gov (United States)

    Schuster, Frederick L; Visvesvara, Govinda S

    2004-08-01

    Knowledge that free-living amoebae are capable of causing human disease dates back some 50 years, prior to which time they were regarded as harmless soil organisms or, at most, commensals of mammals. First Naegleria fowleri, then Acanthamoeba spp. and Balamuthia mandrillaris, and finally Sappinia diploidea have been recognised as etiologic agents of encephalitis; Acanthamoeba spp. are also responsible for amoebic keratitis. Some of the infections are opportunistic, occurring mainly in immunocompromised hosts (Acanthamoeba and Balamuthia encephalitides), while others are non-opportunistic (Acanthamoeba keratitis, Naegleria meningoencephalitis, and cases of Balamuthia encephalitis occurring in immunocompetent humans). The amoebae have a cosmopolitan distribution in soil and water, providing multiple opportunities for contacts with humans and animals, as evidenced by antibody titers in surveyed human populations. Although, the numbers of infections caused by these amoebae are low in comparison to other protozoal parasitoses (trypanosomiasis, toxoplasmosis, malaria, etc.), the difficulty in diagnosing them, the challenge of finding optimal antimicrobial treatments and the morbidity and relatively high mortality associated with, in particular, the encephalitides have been a cause for concern for clinical and laboratory personnel and parasitologists. This review presents information about the individual amoebae: their morphologies and life-cycles, laboratory cultivation, ecology, epidemiology, nature of the infections and appropriate antimicrobial therapies, the immune response, and molecular diagnostic procedures that have been developed for identification of the amoebae in the environment and in clinical specimens.

  20. Amoeba-inspired nanoarchitectonic computing: solving intractable computational problems using nanoscale photoexcitation transfer dynamics.

    Science.gov (United States)

    Aono, Masashi; Naruse, Makoto; Kim, Song-Ju; Wakabayashi, Masamitsu; Hori, Hirokazu; Ohtsu, Motoichi; Hara, Masahiko

    2013-06-18

    Biologically inspired computing devices and architectures are expected to overcome the limitations of conventional technologies in terms of solving computationally demanding problems, adapting to complex environments, reducing energy consumption, and so on. We previously demonstrated that a primitive single-celled amoeba (a plasmodial slime mold), which exhibits complex spatiotemporal oscillatory dynamics and sophisticated computing capabilities, can be used to search for a solution to a very hard combinatorial optimization problem. We successfully extracted the essential spatiotemporal dynamics by which the amoeba solves the problem. This amoeba-inspired computing paradigm can be implemented by various physical systems that exhibit suitable spatiotemporal dynamics resembling the amoeba's problem-solving process. In this Article, we demonstrate that photoexcitation transfer phenomena in certain quantum nanostructures mediated by optical near-field interactions generate the amoebalike spatiotemporal dynamics and can be used to solve the satisfiability problem (SAT), which is the problem of judging whether a given logical proposition (a Boolean formula) is self-consistent. SAT is related to diverse application problems in artificial intelligence, information security, and bioinformatics and is a crucially important nondeterministic polynomial time (NP)-complete problem, which is believed to become intractable for conventional digital computers when the problem size increases. We show that our amoeba-inspired computing paradigm dramatically outperforms a conventional stochastic search method. These results indicate the potential for developing highly versatile nanoarchitectonic computers that realize powerful solution searching with low energy consumption. PMID:23565603

  1. Detection and identification of free-living amoeba from aquatic environment in Taiwan

    Science.gov (United States)

    Jiun Tzeng, Kai; Che Tung, Min; Hsu, Bing Mu; Tsai, Hsiu Feng; Huang, Po Hsiang; Hao Huang, Kuan; Kao, Po Min; Shen, Shu Min; Chen, Jung Sheng

    2013-04-01

    Free-living amoebae including Acanthamoeba, Naegleria, Balamuthia and Hartmannella are widely distributed in water, soil, and air. They can infect humans and can lead to serious illness even death. The aim of this study is to investigate the presence of free-living amoebae from aquatic environment in Taiwan, and to compare the differences between Acanthamoeba and Naegleria in different cultivation methods and conditions. In this study, we used molecular method with specific primers by Polymerase Chain Reaction (PCR) to amplify and to analyze the occurrence of free-living amoebae in aquatic environment. We collected 92 samples from environmental water in Taiwan. The results show that 33 water samples (35.9%) and 11 water samples (12.0%) were detected positive for Acanthamoeba and Naegleria, respectively. Furthermore, both Acanthamoeba and Naegleria can be cultured by PYG in 30° C, but not all free-living amoebae can be enriched and isolated by using storage-cultivation method. Due to the presence of Acanthamoeba and Naegleria in aquatic environment, the water quality monitoring should be more conscious. Keywords: free-living amoebae; Acanthamoeba; Naegleria; Balamuthia; Hartmannella; PCR

  2. Ecological features and bioindicative significance of the testate amoebas (Testacea, Rhizopoda in natural and anthropogenically disturbed biogeocenoses

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    V. V. Red’ko

    2006-12-01

    Full Text Available The literature data on physiology and ecology characteristics of testate amoebas Testacea, Rhizopoda were reviewed. The testate amoebas can be used as the bioindicators of the different soil conditions in natural biogeocenoses. The data of using the superclass Rhizopoda members as indicators of anthropogenic influences on soil are given.

  3. Occurrence of free-living amoebae in communities of low and high endemicity for Buruli ulcer in southern Benin.

    Science.gov (United States)

    Eddyani, Miriam; De Jonckheere, Johan F; Durnez, Lies; Suykerbuyk, Patrick; Leirs, Herwig; Portaels, Françoise

    2008-11-01

    Buruli ulcer or Mycobacterium ulcerans disease occurs mainly in areas in proximity to standing or slowly running freshwater, habitats in which free-living amoebae occur. For this reason, a possible link between the habitat of M. ulcerans and free-living amoebae was investigated. Free-living amoebae and mycobacteria were isolated from water and biofilm specimens taken from protected and unprotected sources of water in villages known to have either high or low endemicity for Buruli ulcer in Benin. Amoebae were isolated from 78.8% of samples. A greater proportion of water bodies in areas of high endemicity had amoebae than in areas of low endemicity (83.3% versus 66.7%). Protected sources of water were significantly more likely to contain amoebae in areas of high endemicity than in areas of low endemicity (88.0% versus 11.1%). Several pathogenic free-living amoebae and mycobacteria were isolated. However, no M. ulcerans was isolated and no specimen was positive for IS2404 PCR. Our results show that the study area has a water hygiene problem, which is greater in areas of high Buruli ulcer endemicity than in areas of low endemicity. Our observations indicate that additional studies are required to explore the possible link between free-living amoebae and mycobacteria.

  4. Impact of free-living amoebae on presence of Parachlamydia acanthamoebae in the hospital environment and its survival in vitro without requirement for amoebae.

    Science.gov (United States)

    Fukumoto, Tatsuya; Matsuo, Junji; Hayashi, Yasuhiro; Hayashi, Masahiro; Oguri, Satoshi; Nakamura, Shinji; Mizutani, Yoshihiko; Yao, Takashi; Akizawa, Kouzi; Suzuki, Haruki; Shimizu, Chikara; Matsuno, Kazuhiko; Yamaguchi, Hiroyuki

    2010-09-01

    Parachlamydia acanthamoebae is an obligately intracellular bacterium that infects free-living amoebae and is a potential human pathogen in hospital-acquired pneumonia. We examined whether the presence of P. acanthamoebae is related to the presence of Acanthamoeba in an actual hospital environment and assessed the in vitro survival of P. acanthamoebae. Ninety smear samples were collected between November 2007 and March 2008 (trial 1, n = 52) and between October 2008 and February 2009 (trial 2, n = 38) from the floor (dry conditions, n = 56) and sink outlets (moist conditions, n = 34) of a hospital. The prevalences of P. acanthamoebae DNA in the first and second trials were 64.3% and 76%, respectively. The prevalences of Acanthamoeba DNA in the first and second trials were 48% and 63.1%, respectively. A statistical correlation between the prevalence of P. acanthamoebae and that of Acanthamoeba was found (trial 1, P = 0.011; trial 2, P = 0.022), and that correlation increased when samples from just the dry area (floor smear samples, P = 0.002) were analyzed but decreased when samples from a moist area were analyzed (P = 0.273). The in vitro experiment showed that, without Acanthamoeba, P. acanthamoebae could not survive in dry conditions for 3 days at 30 degrees C or 15 days at 15 degrees C. Thus, both organisms were coincidentally found in an actual hospital environment, with the presence of Acanthamoeba having a significant effect on the long-term survival of P. acanthamoebae, suggesting that this potential human pathogen could spread through a hospital environment via Acanthamoeba.

  5. Free energy simulations with the AMOEBA polarizable force field and metadynamics on GPU platform.

    Science.gov (United States)

    Peng, Xiangda; Zhang, Yuebin; Chu, Huiying; Li, Guohui

    2016-03-01

    The free energy calculation library PLUMED has been incorporated into the OpenMM simulation toolkit, with the purpose to perform enhanced sampling MD simulations using the AMOEBA polarizable force field on GPU platform. Two examples, (I) the free energy profile of water pair separation (II) alanine dipeptide dihedral angle free energy surface in explicit solvent, are provided here to demonstrate the accuracy and efficiency of our implementation. The converged free energy profiles could be obtained within an affordable MD simulation time when the AMOEBA polarizable force field is employed. Moreover, the free energy surfaces estimated using the AMOEBA polarizable force field are in agreement with those calculated from experimental data and ab initio methods. Hence, the implementation in this work is reliable and would be utilized to study more complicated biological phenomena in both an accurate and efficient way. © 2015 Wiley Periodicals, Inc.

  6. A new pentaplex-nested PCR to detect five pathogenic bacteria in free living amoebae.

    Science.gov (United States)

    Calvo, L; Gregorio, I; García, A; Fernández, M T; Goñi, P; Clavel, A; Peleato, M L; Fillat, M F

    2013-02-01

    Changes in water use and anthropogenic activity have major impacts on the quality of natural aquatic ecosystems, water distribution and wastewater plants. One of the main problems is the presence of some pathogenic microorganisms that are resistant to disinfection procedures when they are hosted by free living amoeba and that in many cases are hardly detectable by culture-based procedures. In this work we report a sensitive, low-cost procedure consisting of a pentaplex-nested PCR that allows simultaneous detection of Legionella pneumophila, Mycobacterium spp., Pseudomonas spp., Vibrio cholerae and the microcystin-producing cyanobacteria Microcystis aeruginosa. The method has been used to detect the presence of these pathogenic bacteria in water and inside free living amoeba. Its validation in 72 samples obtained from different water sources from Aragon (Spain) evidences that Mycobacterium and Pseudomonas spp are prevailing as amoeba-resistant bacteria.

  7. Free-living amoebae, a training field for macrophage resistance of mycobacteria.

    Science.gov (United States)

    Salah, I B; Ghigo, E; Drancourt, M

    2009-10-01

    Mycobacterium species evolved from an environmental recent common ancestor by reductive evolution and lateral gene transfer. Strategies selected through evolution and developed by mycobacteria resulted in resistance to predation by environmental unicellular protists, including free-living amoebae. Indeed, mycobacteria are isolated from the same soil and water environments as are amoebae, and experimental models using Acanthamoeba spp. and Dictyostelium discoideum were exploited to analyse the mechanisms for intracellular survival. Most of these mechanisms have been further reproduced in macrophages for mycobacteria regarded as opportunistic and obligate pathogens. Amoebal cysts may protect intracellular mycobacteria against adverse conditions and may act as a vector for mycobacteria. The latter hypothesis warrants further environmental and clinical studies to better assess the role of free-living amoebae in the epidemiology of infections caused by mycobacteria.

  8. Late Holocene palaeohydrological changes in a Sphagnum peat bog from NW Romania based on testate amoebae

    Directory of Open Access Journals (Sweden)

    Andrei-Cosmin Diaconu

    2016-04-01

    Full Text Available This paper investigates the possibility of reconstructing the palaeohydrological changes in an active Sphagnum peat bog from north-western Romania using testate amoebae fauna and organic matter content determined by loss on ignition (LOI. In total 28 taxa of testate amoebae were identified of which 11 were frequent enough to present a remarkable ecological significance. Based on the relative abundance of these taxa nine zones were identified, crossing from very wet to dry climate conditions. The wet periods identified are characterized by taxa like Centropyxis cassis, Amphitrema flavum and Hyalosphenia papilio, while in the dry periods Difflugia pulex and Nebela militaris thrive. We showed that combining qualitative information regarding hydrological preferences with the quantitative percentage data from the fossil record it is possible to obtain information regarding major surface moisture changes from the peat bog surface. Furthermore we identified a link between distribution of testate amoebae assemblages, organic matter variation and minerogenic material.

  9. Foraging Behaviors and Potential Computational Ability of Problem-Solving in an Amoeba

    Science.gov (United States)

    Nakagaki, Toshiyuki

    We study cell behaviors in the complex situations: multiple locations of food were simultaneously given. An amoeba-like organism of true slime mold gathered at the multiple food locations while body shape made of tubular network was totally changed. Then only a few tubes connected all of food locations through a network shape. By taking the network shape of body, the plasmodium could meet its own physiological requirements: as fast absorption of nutrient as possible and sufficient circulation of chemical signals and nutrients through a whole body. Optimality of network shape was evaluated in relation to a combinatorial optimization problem. Here we reviewed the potential computational ability of problem-solving in the amoeba, which was much higher than we'd though. The main message of this article is that we had better to change our stupid opinion that an amoeba is stupid.

  10. Neighborhoods and Fertility in Accra, Ghana: An AMOEBA-based Approach.

    Science.gov (United States)

    Weeks, John R; Getis, Arthur; Hill, Allan G; Agyei-Mensah, Samuel; Rain, David

    2010-01-01

    Fertility levels remain high in most of sub-Saharan Africa, despite recent declines, and even in a large capital city such as Accra, Ghana, women are having children at a pace that is well above replacement level and this will contribute to significant levels of future population growth in the city. Our purpose in this paper is to evaluate the way in which neighborhood context may shape reproductive behavior in Accra. In the process, we introduce several important innovations to the understanding of intra-urban fertility levels in a sub-Saharan African city: (1) despite the near explosion of work on neighborhoods as a spatial unit of analysis, very little of this research has been conducted outside of the richer countries; (2) we characterize neighborhoods on the basis of local knowledge of what we call "vernacular neighborhoods"; (3) we then define what we call "organic neighborhoods" using a new clustering tool-the AMOEBA algorithm-to create these neighborhoods; and then (4) we evaluate and explain which of the neighborhood concepts has the largest measurable contextual effect on an individual woman's reproductive behavior. Multi-level regression analysis suggests that vernacular neighborhoods are more influential on a woman's decision to delay marriage, whereas the organic neighborhoods based on socioeconomic status better capture the factors that shape fertility decisions after marriage. PMID:21572914

  11. A novel testate amoebae trait-based approach to infer environmental disturbance in Sphagnum peatlands

    Science.gov (United States)

    Marcisz, Katarzyna; Colombaroli, Daniele; Jassey, Vincent E. J.; Tinner, Willy; Kołaczek, Piotr; Gałka, Mariusz; Karpińska-Kołaczek, Monika; Słowiński, Michał; Lamentowicz, Mariusz

    2016-01-01

    Species’ functional traits are closely related to ecosystem processes through evolutionary adaptation, and are thus directly connected to environmental changes. Species’ traits are not commonly used in palaeoecology, even though they offer powerful advantages in understanding the impact of environmental disturbances in a mechanistic way over time. Here we show that functional traits of testate amoebae (TA), a common group of palaeoecological indicators, can serve as an early warning signal of ecosystem disturbance and help determine thresholds of ecosystem resilience to disturbances in peatlands. We analysed TA traits from two Sphagnum-dominated mires, which had experienced different kinds of disturbances in the past 2000 years – fire and peat extraction, respectively. We tested the effect of disturbances on the linkages between TA community structure, functional trait composition and functional diversity using structural equation modelling. We found that traits such as mixotrophy and small hidden apertures (plagiostomic apertures) are strongly connected with disturbance, suggesting that these two traits can be used as palaeoecological proxies of peatland disturbance. We show that TA functional traits may serve as a good proxy of past environmental changes, and further analysis of trait-ecosystem relationships could make them valuable indicators of the contemporary ecosystem state. PMID:27658521

  12. Proteinases in Naegleria Fowleri (strain NF3), a pathogenic amoeba: a preliminary study.

    Science.gov (United States)

    Mat Amin, Nakisah

    2004-12-01

    Naegleria fowleri is a free-living amoeba, known as a causative agent for a fatal disease of the central nervous system (CNS) in man such as Primary amoebic meningoencephalitis (PAM). Factors contributing to its pathogenicity and its distribution in the environment have been investigated by previous researchers. In case of its pathogenicity, several enzymes such as phospolipase A and sphingomyelinase, have been proposed to probably act as aggressors in promoting PAM but no study so far have been conducted to investigate the presence of proteinase enzyme in this amoeba although a 56kDa cystein proteinase enzyme has been identified in Entamoeba histolytica as an important contributing factor in the amoeba's virulence. In this preliminary study, a pathogenic amoeba, Naegleria fowleri (strain NF3) was examined for the presence of proteinases. Samples of enzymes in this amoeba were analysed by electrophoresis using SDS-PAGE-gelatin gels. The results showed that this amoeba possesses at least two high molecular weight proteinases on gelatin gels; their apparent molecular weights are approximately 128 kDa and approximately 170 kDa. Band of approximately 128 kDa enzyme is membrane-associated and its activity is higher at alkaline pH compared with lower pH; at lower pH, its activity is greatly stimulated by DTT. The approximately 170 kDa band enzyme appears to be inactivated at pH 8.0, at lower ph its activity is higher and DTT-dependance. The activity of this enzyme is partially inhibited by inhibitor E-64 but markedly inhibited to antipain suggesting it belongs to the cysteine proteinase group.

  13. Vampires in the oceans: predatory cercozoan amoebae in marine habitats.

    Science.gov (United States)

    Berney, Cédric; Romac, Sarah; Mahé, Frédéric; Santini, Sébastien; Siano, Raffaele; Bass, David

    2013-12-01

    Vampire amoebae (vampyrellids) are predators of algae, fungi, protozoa and small metazoans known primarily from soils and in freshwater habitats. They are among the very few heterotrophic naked, filose and reticulose protists that have received some attention from a morphological and ecological point of view over the last few decades, because of the peculiar mode of feeding of known species. Yet, the true extent of their biodiversity remains largely unknown. Here we use a complementary approach of culturing and sequence database mining to address this issue, focusing our efforts on marine environments, where vampyrellids are very poorly known. We present 10 new vampyrellid isolates, 8 from marine or brackish sediments, and 2 from soil or freshwater sediment. Two of the former correspond to the genera Thalassomyxa Grell and Penardia Cash for which sequence data were previously unavailable. Small-subunit ribosomal DNA analysis confirms they are all related to previously sequenced vampyrellids. An exhaustive screening of the NCBI GenBank database and of 454 sequence data generated by the European BioMarKs consortium revealed hundreds of distinct environmental vampyrellid sequences. We show that vampyrellids are much more diverse than previously thought, especially in marine habitats. Our new isolates, which cover almost the full phylogenetic range of vampyrellid sequences revealed in this study, offer a rare opportunity to integrate data from environmental DNA surveys with phenotypic information. However, the very large genetic diversity we highlight within vampyrellids (especially in marine sediments and soils) contrasts with the paradoxically low morphological distinctiveness we observed across our isolates. PMID:23864128

  14. Lacustrine Arcellinina (Testate Amoebae) as Bioindicators of Arsenic Contamination.

    Science.gov (United States)

    Nasser, Nawaf A; Patterson, R Timothy; Roe, Helen M; Galloway, Jennifer M; Falck, Hendrik; Palmer, Michael J; Spence, Christopher; Sanei, Hamed; Macumber, Andrew L; Neville, Lisa A

    2016-07-01

    Arcellininids (testate amoebae) were examined from 61 surface sediment samples collected from 59 lakes in the vicinity of former gold mines, notably Giant Mine, near Yellowknife, Northwest Territories, Canada to determine their utility as bioindicators of arsenic (As), which occurs both as a byproduct of gold extraction at mines in the area and ore-bearing outcrops. Cluster analysis (Q-R-mode) and detrended correspondence analysis (DCA) reveal five arcellininid assemblages, three of which are related to varying As concentrations in the sediment samples. Redundancy analysis (RDA) showed that 14 statistically significant environmental parameters explained 57 % of the variation in faunal distribution, while partial RDA indicated that As had the greatest influence on assemblage variance (10.7 %; p  10000 ppm, min = 16.1 ppm, n = 32), while difflugiid dominated assemblages were prevalent in substrates with relatively low As concentrations (median = 30.2 ppm, max = 905.2 ppm, min = 6.3 ppm, n = 20). Most of the lakes with very high As levels are located downwind (N and W) of the former Giant Mine roaster stack where refractory ore was roasted and substantial quantities of As were released (as As2O3) to the atmosphere in the first decade of mining. This spatial pattern suggests that a significant proportion of the observed As, in at least these lakes, are industrially derived. The results of this study highlight the sensitivity of Arcellinina to As and confirm that the group has considerable potential for assessing the impact of As contamination on lakes. PMID:27026100

  15. [The role of the floodplain gradient in structuring of testate amoebae communities in the Ilych River].

    Science.gov (United States)

    Mazeĭ, Iu A; Malysheva, E A; Lapteva, E M; Komarov, A A; Taskaeva, A A

    2012-01-01

    Forty-two testate amoebae taxa were identified in alluvial soils of floodplain islands in the Ilych River. Among the pedo- and eurybionts, there were aquatic rhizopods. Along the floodplain transect (willow --> meadow --> deciduous forest --> coniferous forest), the testate amoebae community changed directly. There are spatially homogeneous (low beta-diversity) testacean communities but species rich on the local level (high alpha-diversity) within forests. Within willows and meadows, communities are characterized by low alpha-diversity and high heterogeneity that leads to high gamma-diversity. PMID:22988761

  16. Free-living amoebae in Egypt. 1. Naegleria gruberi and Naegleria fowleri.

    Science.gov (United States)

    Nashed, N N; Youssef, F G; Mansour, N S

    1991-04-01

    Two Naegleria species were isolated and identified from various water sources in Lower and Upper Egypt. Identification was based on the morphology, nuclear division and the excystation and flagellation tests. The trophic, cystic and flagellate forms of N. gruberi are larger than those of N. fowleri and the cyst of the former species has one or more pores while that of the latter species has no pores and has an outer gelatinous layer. The size and the morphological characteristics of these two free-living amoebae from Egypt were in complete agreement with those previously described for amoebae of this same genus and species endemic to other geographical areas.

  17. Relationships between free living amoebae and Exophiala dermatitidis: a preliminary study.

    Science.gov (United States)

    Cateau, Estelle; Mergey, Tiphaine; Kauffmann-Lacroix, Catherine; Rodier, Marie-Helene

    2009-02-01

    Free living amoebae can play a role as reservoirs for pathogens isolated from hospital water. We have investigated the potential interactions between two protozoa (Acanthamoeba castellanii and Hartmanella vermiformis) that may be recovered from hospital water tips and Exophiala dermatitidis, a black yeast often recovered from water sources. We showed that the presence of trophozoites or supernatants of culture of H. vermiformis increased fungal growth, whereas the same phenomenon was observed only with the supernatant of A. castellanii cultures. These preliminary results highlight the fact that the recovering of free-living amoebae in hospital water taps could lead to the development of fungal nosocomial pathogens.

  18. [The role of the floodplain gradient in structuring of testate amoebae communities in the Ilych River].

    Science.gov (United States)

    Mazeĭ, Iu A; Malysheva, E A; Lapteva, E M; Komarov, A A; Taskaeva, A A

    2012-01-01

    Forty-two testate amoebae taxa were identified in alluvial soils of floodplain islands in the Ilych River. Among the pedo- and eurybionts, there were aquatic rhizopods. Along the floodplain transect (willow --> meadow --> deciduous forest --> coniferous forest), the testate amoebae community changed directly. There are spatially homogeneous (low beta-diversity) testacean communities but species rich on the local level (high alpha-diversity) within forests. Within willows and meadows, communities are characterized by low alpha-diversity and high heterogeneity that leads to high gamma-diversity.

  19. Control of Branchionus sp. and Amoeba sp. in cultures of Arthrospira sp. Control de Branchionus sp. y Amoeba sp. en cultivos de Arthrospira sp.

    OpenAIRE

    Carlos Méndez; Eduardo Uribe

    2012-01-01

    Cultivation of cyanobacterium Arthrospira sp. has been developed in many countries for the production of proteins, pigments and other compounds. Outdoor mass cultures are often affected by biological contamination, drastically reducing productivity as far as bringing death. This study evaluates the control of Branchionus sp. and Amoeba sp. with two chemical compounds: urea (U) and ammonium bicarbonate (AB), in laboratory conditions and outdoor mass culture of Arthrospira sp. The lethal concen...

  20. The abundant free-living amoeba, Acanthamoeba polyphaga, increases the survival of Campylobacter jejuni in milk and orange juice

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    Jenny Olofsson

    2015-09-01

    Full Text Available Background: Campylobacter jejuni is a common cause of human bacterial diarrhea in most parts of the world. Most C. jejuni infections are acquired from contaminated poultry, milk, and water. Due to health care costs and human suffering, it is important to identify all possible sources of infection. Unpasteurized milk has been associated with several outbreaks of C. jejuni infection. Campylobacter has been identified on fresh fruit, and other gastrointestinal pathogens such as Salmonella, E. coli O157:H7 and Cryptosporidium have been involved in fruit juice outbreaks. C. jejuni is sensitive to the acidic environment of fruit juice, but co-cultures with the amoeba, Acanthamoeba polyphaga, have previously been shown to protect C. jejuni at low pH. Methods: To study the influence of A. polyphaga on the survival of C. jejuni in milk and juice, the bacteria were incubated in the two products at room temperature and at 4°C with the following treatments: A C. jejuni preincubated with A. polyphaga before the addition of product, B C. jejuni mixed with A. polyphaga after the addition of product, and C C. jejuni in product without A. polyphaga. Bacterial survival was assessed by colony counts on blood agar plates. Results: Co-culture with A. polyphaga prolonged the C. jejuni survival both in milk and juice. The effect of co-culture was most pronounced in juice stored at room temperature. On the other hand, A. polyphaga did not have any effect on C. jejuni survival during pasteurization of milk or orange juice, indicating that this is a good method for eliminating C. jejuni in these products. Conclusion: Amoebae-associated C. jejuni in milk and juice might cause C. jejuni infections.

  1. Amoebae as potential environmental hosts for Mycobacterium ulcerans and other mycobacteria, but doubtful actors in Buruli ulcer epidemiology.

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    Sophie Gryseels

    Full Text Available BACKGROUND: The reservoir and mode of transmission of Mycobacterium ulcerans, the causative agent of Buruli ulcer, remain unknown. Ecological, genetic and epidemiological information nonetheless suggests that M. ulcerans may reside in aquatic protozoa. METHODOLOGY/PRINCIPAL FINDINGS: We experimentally infected Acanthamoeba polyphaga with M. ulcerans and found that the bacilli were phagocytised, not digested and remained viable for the duration of the experiment. Furthermore, we collected 13 water, 90 biofilm and 45 detritus samples in both Buruli ulcer endemic and non-endemic communities in Ghana, from which we cultivated amoeboid protozoa and mycobacteria. M. ulcerans was not isolated, but other mycobacteria were as frequently isolated from intracellular as from extracellular sources, suggesting that they commonly infect amoebae in nature. We screened the samples as well as the amoeba cultures for the M. ulcerans markers IS2404, IS2606 and KR-B. IS2404 was detected in 2% of the environmental samples and in 4% of the amoeba cultures. The IS2404 positive amoeba cultures included up to 5 different protozoan species, and originated both from Buruli ulcer endemic and non-endemic communities. CONCLUSIONS/SIGNIFICANCE: This is the first report of experimental infection of amoebae with M. ulcerans and of the detection of the marker IS2404 in amoeba cultures isolated from the environment. We conclude that amoeba are potential natural hosts for M. ulcerans, yet remain sceptical about their implication in the transmission of M. ulcerans to humans and their importance in the epidemiology of Buruli ulcer.

  2. Mycobacterium tuberculosis complex mycobacteria as amoeba-resistant organisms.

    Directory of Open Access Journals (Sweden)

    Felix Mba Medie

    Full Text Available BACKGROUND: Most environmental non-tuberculous mycobacteria have been demonstrated to invade amoebal trophozoites and cysts, but such relationships are largely unknown for members of the Mycobacterium tuberculosis complex. An environmental source has been proposed for the animal Mycobacterium bovis and the human Mycobacterium canettii. METHODOLOGY/PRINCIPAL FINDINGS: Using optic and electron microscopy and co-culture methods, we observed that 89±0.6% of M. canettii, 12.4±0.3% of M. tuberculosis, 11.7±2% of M. bovis and 11.2±0.5% of Mycobacterium avium control organisms were phagocytized by Acanthamoeba polyphaga, a ratio significantly higher for M. canettii (P = 0.03, correlating with the significantly larger size of M. canetti organisms (P = 0.035. The percentage of intraamoebal mycobacteria surviving into cytoplasmic vacuoles was 32±2% for M. canettii, 26±1% for M. tuberculosis, 28±2% for M. bovis and 36±2% for M. avium (P = 0.57. M. tuberculosis, M. bovis and M. avium mycobacteria were further entrapped within the double wall of <1% amoebal cysts, but no M. canettii organisms were observed in amoebal cysts. The number of intracystic mycobacteria was significantly (P = 10(-6 higher for M. avium than for the M. tuberculosis complex, and sub-culturing intracystic mycobacteria yielded significantly more (P = 0.02 M. avium organisms (34×10(4 CFU/mL than M. tuberculosis (42×10(1 CFU/mL and M. bovis (35×10(1 CFU/mL in the presence of a washing fluid free of mycobacteria. Mycobacteria survived in the cysts for up to 18 days and cysts protected M. tuberculosis organisms against mycobactericidal 5 mg/mL streptomycin and 2.5% glutaraldehyde. CONCLUSIONS/SIGNIFICANCE: These data indicate that M. tuberculosis complex organisms are amoeba-resistant organisms, as previously demonstrated for non-tuberculous, environmental mycobacteria. Intercystic survival of tuberculous mycobacteria, except for M. canettii, protect them

  3. Seasonal changes in Sphagnum peatland testate amoeba communities along a hydrological gradient.

    Science.gov (United States)

    Marcisz, Katarzyna; Lamentowicz, Lukasz; Słowińska, Sandra; Słowiński, Michał; Muszak, Witold; Lamentowicz, Mariusz

    2014-10-01

    Testate amoebae are an abundant and functionally important group of protists in peatlands, but little is known about the seasonal patterns of their communities. We investigated the relationships between testate amoeba diversity and community structure and water table depth and light conditions (shading vs. insolation) in a Sphagnum peatland in Northern Poland (Linje mire) in spring and summer 2010. We monitored the water table at five sites across the peatland and collected Sphagnum samples in lawn and hummock micro-sites around each piezometer, in spring (3 May) and mid-summer (6 August) 2010. Water table differed significantly between micro-sites and seasons (Kruskal-Wallis test, p=0.001). The community structure of testate amoebae differed significantly between spring and summer in both hummock and lawn micro-sites. We recorded a small, but significant drop in Shannon diversity, between spring and summer (1.76 vs. 1.72). Strongest correlations were found between testate amoeba communities and water table lowering and light conditions. The relative abundance of mixotrophic species Hyalosphenia papilio, Archerella flavum and of Euglypha ciliata was higher in the summer.

  4. Virulence determinants of the human pathogenic fungus Aspergillus fumigatus protect against soil amoeba predation.

    Science.gov (United States)

    Hillmann, Falk; Novohradská, Silvia; Mattern, Derek J; Forberger, Tilmann; Heinekamp, Thorsten; Westermann, Martin; Winckler, Thomas; Brakhage, Axel A

    2015-08-01

    Filamentous fungi represent classical examples for environmentally acquired human pathogens whose major virulence mechanisms are likely to have emerged long before the appearance of innate immune systems. In natural habitats, amoeba predation could impose a major selection pressure towards the acquisition of virulence attributes. To test this hypothesis, we exploited the amoeba Dictyostelium discoideum to study its interaction with Aspergillus fumigatus, two abundant soil inhabitants for which we found co-occurrence in various sites. Fungal conidia were efficiently taken up by D. discoideum, but ingestion was higher when conidia were devoid of the green fungal spore pigment dihydroxynaphtalene melanin, in line with earlier results obtained for immune cells. Conidia were able to survive phagocytic processing, and intracellular germination was initiated only after several hours of co-incubation which eventually led to a lethal disruption of the host cell. Besides phagocytic interactions, both amoeba and fungus secreted cross inhibitory factors which suppressed fungal growth or induced amoeba aggregation with subsequent cell lysis, respectively. On the fungal side, we identified gliotoxin as the major fungal factor killing Dictyostelium, supporting the idea that major virulence attributes, such as escape from phagocytosis and the secretion of mycotoxins are beneficial to escape from environmental predators.

  5. Naegleria fowleri amoebae express a membrane-associated calcium-independent phospholipase A(2).

    Science.gov (United States)

    Barbour, S E; Marciano-Cabral, F

    2001-02-26

    Naegleria fowleri, a free-living amoeba, is the causative agent of primary amoebic meningoencephalitis. Previous reports have demonstrated that N. fowleri expresses one or more forms of phospholipase A(2) (PLA(2)) and that a secreted form of this enzyme is involved in pathogenesis. However, the molecular nature of these phospholipases remains largely unknown. This study was initiated to determine whether N. fowleri expresses analogs of the well-characterized PLA(2)s that are expressed by mammalian macrophages. Amoeba cell homogenates contain a PLA(2) activity that hydrolyzes the substrate that is preferred by the 85 kDa calcium-dependent cytosolic PLA(2), cPLA(2). However, unlike the cPLA(2) enzyme in macrophages, this activity is largely calcium-independent, is constitutively associated with membranes and shows only a modest preference for phospholipids that contain arachidonate. The amoeba PLA(2) activity is sensitive to inhibitors that block the activities of cPLA(2)-alpha and the 80 kDa calcium-independent PLA(2), iPLA(2), that are expressed by mammalian cells. One of these compounds, methylarachidonyl fluorophosphonate, partially inhibits the constitutive release of [(3)H]arachidonic acid from pre-labeled amoebae. Together, these data suggest that N. fowleri expresses a constitutively active calcium-independent PLA(2) that may play a role in the basal phospholipid metabolism of these cells.

  6. First Report of Vannellidae Amoebae (Vannella Spp. Isolated From Biofilm Source

    Directory of Open Access Journals (Sweden)

    F Zaeri

    2011-09-01

    Full Text Available Background: Members of the Vannellidae family are free-living amoebae (FLA distributed mainly in water and soil sources. The present study reports the first isolation of this genus in the biofilm source from hospital environment in Tehran, Iran.Methods: Biofilm samples were collected from hospital environment. Cultivation was performed in non-nutrient agar covered with a heat-killed Escherichia coli. Cloning of the suspected amoe­bae was done. PCR amplification and Homology analysis using the Basic Local Alignment Search Tool (BLASTn was performed to search for the most similar reference sequences.Results: Microscopic examination showed numerous fan-shaped amoebae and peculiar cysts differ­ent to the usual shape of typical FLA. Sequence analysis of the PCR- product revealed that the suspected amoebae are highly homologous with Vannella spp. gene (99% identity and 100% query coverage available in the gene bank database.Conclusion: Although Vannella spp. is not proved to be pathogenic itself, but they are capable of har­boring pathogenic intracellular organisms such as Microsporidian parasites. Thus, identifica­tion of such amoebae can be of clinical importance, as they could lead to transmission of other pathogens to human.

  7. Exposure to synthetic greywater inhibits amoebae encystation and alters expression of Legionella pneumophila virulence genes

    Science.gov (United States)

    Water conservation efforts have focused on greywater (GW) usage, especially for applications that do not require potable water quality. However, there is a need to better understand environmental pathogens and their free-living amoebae (FLA) hosts within GW. Using synthetic gre...

  8. Free-living amoebae used to isolate consortia capable of degrading trichloroethylene

    Energy Technology Data Exchange (ETDEWEB)

    Tyndall, R.L.; Katz, D.S.; Little, C.D. [Oak Ridge National Lab., TN (United States); Kennedy, J.R. [Univ. of Tennessee, Knoxville, TN (United States)

    1991-12-31

    The interaction of protozoa with prokaryotes is well documented. These interactions can be either ecto- or endosymbiotic. An example of photosynthetic symbiosis is the well-defined interaction between paramecium and entrapped Chlorella. Paramecium can also form symbiotic relationships with gram-negative heterotrophic bacteria. Jeon has described an interaction between amoebae and engulfed bacteria, that eventuated into a dependency of the amoebae on the presence of the engulfed bacterium. Free-living amoebae and tetrahymena can engulf and subsequently provide the necessary niche for the replication of Legionella. Acanthamoebae trophozoites and cysts can harbor and support the replication of unidentified gram-negative bacteria. King has recently shown that bacteria associated with free-living amoebae are more resistant to toxic environments. Assuming that methylotrophic bacteria in situ are a part of a mixed community, and based on our observations that bacteria associated with protozoa may not be easily isolated by standard techniques, we attempted to use protozoa as a tool to isolate TCE-degrading bacteria.

  9. Seasonal changes in Sphagnum peatland testate amoeba communities along a hydrological gradient.

    Science.gov (United States)

    Marcisz, Katarzyna; Lamentowicz, Lukasz; Słowińska, Sandra; Słowiński, Michał; Muszak, Witold; Lamentowicz, Mariusz

    2014-10-01

    Testate amoebae are an abundant and functionally important group of protists in peatlands, but little is known about the seasonal patterns of their communities. We investigated the relationships between testate amoeba diversity and community structure and water table depth and light conditions (shading vs. insolation) in a Sphagnum peatland in Northern Poland (Linje mire) in spring and summer 2010. We monitored the water table at five sites across the peatland and collected Sphagnum samples in lawn and hummock micro-sites around each piezometer, in spring (3 May) and mid-summer (6 August) 2010. Water table differed significantly between micro-sites and seasons (Kruskal-Wallis test, p=0.001). The community structure of testate amoebae differed significantly between spring and summer in both hummock and lawn micro-sites. We recorded a small, but significant drop in Shannon diversity, between spring and summer (1.76 vs. 1.72). Strongest correlations were found between testate amoeba communities and water table lowering and light conditions. The relative abundance of mixotrophic species Hyalosphenia papilio, Archerella flavum and of Euglypha ciliata was higher in the summer. PMID:25176338

  10. Survey for the presence of specific free-living amoebae in cooling waters from Belgian power plants.

    Science.gov (United States)

    Behets, Jonas; Declerck, Priscilla; Delaedt, Yasmine; Verelst, Lieve; Ollevier, Frans

    2007-05-01

    Free-living amoebae (FLA) are distributed ubiquitously in aquatic environments with increasing importance in hygienic, medical and ecological relationships to man. In this study, water samples from Belgian industrial cooling circuits were quantitatively surveyed for the presence of FLA. Isolated, thermotolerant amoebae were identified morphologically as well as using the following molecular methods: enzyme-linked immunosorbent assay and isoenzyme electrophoresis and PCR. Thermophilic amoebae were present at nearly all collection sites, and the different detection methods gave similar results. Naegleria fowleri was the most frequently encountered thermotolerant species, and concentrations of thermotolerant FLA were correlated with higher temperatures.

  11. Management System of Distributed Database Based on Amoeba Middleware%基于Amoeba中间件的分布式数据库管理系统

    Institute of Scientific and Technical Information of China (English)

    孙巍; 谭成翔

    2013-01-01

    This paper proposes a management system of distributed databases in the background of the large-scale application of databases. The system uses the middleware of Amoeba to realize the management of server cluster. It utilizes Amoeba to gather and modify the information of servers, to configure the parameters of Amoeba servers and MySQL database servers , load balancing, the separation rule of read and write, and data segmentation. Administrators can use this system to master the state of servers and avoid tedious operation. At last, the experiment shows that it can effectively configure the parameters to manage a large number of servers.%在数据库运用普遍建立于计算机网络之上的环境下,通过Amoeba中间件,实现对服务器集群的统一管理.该系统利用Amoeba中间件,通过对服务器信息的收集和修改,实现Amoeba服务器参数、MySQL数据库服务器参数、负载均衡、读写分离规则以及数据切分功能的配置.该系统避免了繁琐而杂乱的各个服务器独立配置,让管理人员从整体上掌控整个服务器系统运行状态.最后,实验验证,该套系统能够有效管理和配置服务器运行参数.

  12. Disruption of MDCK cell tight junctions by the free-living amoeba Naegleria fowleri.

    Science.gov (United States)

    Shibayama, Mineko; Martínez-Castillo, Moisés; Silva-Olivares, Angélica; Galindo-Gómez, Silvia; Navarro-García, Fernando; Escobar-Herrera, Jaime; Sabanero, Myrna; Tsutsumi, Víctor; Serrano-Luna, Jesús

    2013-02-01

    Naegleria fowleri is the aetiological agent of primary amoebic meningoencephalitis. This parasite invades its host by penetrating the olfactory mucosa. However, the mechanism of epithelium penetration is not well understood. In the present study, we evaluated the effect of N. fowleri trophozoites and the non-pathogenic Naegleria gruberi on Madin-Darby canine kidney (MDCK) tight junction proteins, including claudin-1, occludin and ZO-1, as well as on the actin cytoskeleton. Trophozoites from each of the free-living amoeba species were co-cultured with MDCK cells in a 1 : 1 ratio for 1, 3, 6 or 10 h. Light microscopy revealed that N. fowleri caused morphological changes as early as 3 h post-infection in an epithelial MDCK monolayer. Confocal microscopy analysis revealed that after 10 h of co-culture, N. fowleri trophozoites induced epithelial cell damage, which was characterized by changes in the actin apical ring and disruption of the ZO-1 and claudin-1 proteins but not occludin. Western blot assays revealed gradual degradation of ZO-1 and claudin-1 as early as 3 h post-infection. Likewise, there was a drop in transepithelial electrical resistance that resulted in increased epithelial permeability and facilitated the invasion of N. fowleri trophozoites by a paracellular route. In contrast, N. gruberi did not induce alterations in MDCK cells even at 10 h post-infection. Based on these results, we suggest that N. fowleri trophozoites disrupt epithelial monolayers, which could enable their penetration of the olfactory epithelium and subsequent invasion of the central nervous system.

  13. [A study on the taxonomy of soil amoebas from Caspian plague foci based on an analysis of ribosomal operon sequences].

    Science.gov (United States)

    Koshel', E I; Anisimova, L V; Novichkova, L A; Vidiaeva, N A; Guseva, N P; Eroshenko, G A; Kutyrev, V V

    2015-01-01

    The results of a study on the taxonomy and quantitative abundance of free-living amoebas in soil samples from the Russian plague foci of the northwestern Caspian steppe, the Caspian sand, and the Volga-Ural steppe are presented. Amoebas of the Willaertia and Hartmanella genera, as well as representatives of myxomycetes, were isolated from samples. From these, amoebas of the Acanthamoeba genus predominated and could be as abundantas 300000 cells per 1 g of soil. Sequencing of the 18S rRNA gene region showed that Acanthamoeba from the Volga-Ural steppe focus belonged to the A. castellanii species. Phylogenetic analysis confirmed that amoebas from two other Caspian foci belonged to the species of Acanthamoeba spp.

  14. Presence of pathogenic amoebae in power plant cooling waters. Final report, October 15, 1977-September 30, 1979. [Naegleria fowleri

    Energy Technology Data Exchange (ETDEWEB)

    Tyndall, R.L.; Willaert, E.; Stevens, A.R.

    1981-03-01

    Cooling-water-associated algae and sediments from five northern and five southern or western electric power plants were tested for the presence of pathogenic amoebae. In addition, water algae and sediments from five northern and five southern/western sites not associated with power plants were tested. There was a significant correlation at northern power plants between the presence of thermophilic, pathogenic amoebae in cooling waters and thermal additions. Presence of the pathogenic did not correlate with salinity, pH, conductivity, or a variety of various chemical components of the cooling waters. Selected pathogenic isolates were tested serologically and were classified as Naegleria fowleri. Although thermal additions were shown to be contributing factor in predisposing cooling waters to the growth of pathogenic amoebae, the data suggest the involvement of other currently undefined parameters associated with the presence of the pathogenic amoebae. 35 refs., 21 tabs.

  15. Status of free-living amoebae (Acanthamoeba spp., Naegleria fowleri, Balamuthia mandrillaris) in drinking water supplies in Karachi, Pakistan.

    Science.gov (United States)

    Yousuf, Farzana Abubakar; Siddiqui, Ruqaiyyah; Subhani, Faysal; Khan, Naveed Ahmed

    2013-06-01

    The ability of pathogenic free-living amoebae to produce infections is a growing concern. In this study, we investigated the presence of free-living amoebae (Acanthamoeba spp., Naegleria fowleri, Balamuthia mandrillaris) in drinking water supplies in Karachi, Pakistan. Fifty-two domestic tap water samples were examined. Amoebae were identified by morphological characteristics and polymerase chain reaction. Thirty percent of the examined samples were positive for Acanthamoeba spp., 8% for N. fowleri while B. mandrillaris were not recovered. Additionally we examined secretory IgA antibody to Acanthamoeba and B. mandrillaris. Acanthamoeba antibody prevalence rate was 100% in both males and females, while B. mandrillaris antibody prevalence rate was 5.5% in males only (females were negative). Our findings suggest that free-living amoebae are a potential health hazard in domestic water supplies in Karachi, Pakistan.

  16. Evidence of test detachment in Astrorhiza limicola and two consequential synonyms: Amoeba gigantea and Megamoebomyxa argillobia (Foraminiferida)

    DEFF Research Database (Denmark)

    Cedhagen, Tomas; Tendal, Ole S.

    1989-01-01

    Laboratory observations and experiments demonstrate that the naked rhizopods Amoeba gigantea SANDAHL, 1857 and Megamoebomyxa argillo~ia NYHOLM, 1950, and the foraminifers Astrorhiza arenifera STSCHEDRlNA, 1946, A. sabulifera STSCHEDRINA, 1946 and A. arctlca STSCHEDRINA, 1958 are synonyms of Astro......Laboratory observations and experiments demonstrate that the naked rhizopods Amoeba gigantea SANDAHL, 1857 and Megamoebomyxa argillo~ia NYHOLM, 1950, and the foraminifers Astrorhiza arenifera STSCHEDRlNA, 1946, A. sabulifera STSCHEDRINA, 1946 and A. arctlca STSCHEDRINA, 1958 are synonyms...

  17. Detection and identification of free-living amoeba from aquatic environment in different seasons in Taiwan

    Science.gov (United States)

    Tzeng, K.; Hsu, B.; Tsai, H.; Huang, P.; Tsai, J.; Kao, P.; Huang, K.; Chen, J.

    2013-12-01

    Free-living amoeba includes Acanthamoeba and Naegleria, which are widely distributed in water and soil. Human infection with free-living amoeba leads to serious illness, even lethal. For example, central nervous system infection will cause amoebic meningoencephalitis, and infections will cause amoebic keratitis. The presence of free-living amoeba in environment water can be used as a water quality indicator in ecosystem assessment. In Taiwan, reservoirs are indispensable because of the water source are limited by the steep terrain and the short river flow. Therefore, we need to pay more attention in the quality control of reservoirs water. The aims of this study are to investigate the presence of free-living amoeba in Taiwan reservoirs, and to compare the differences among seasons. At last, the identification and genotyping of Acanthamoeba and Naegleria are investigated. In this study, we use polymerase chain reaction with specific primers to analyze the presence of free-living amoeba in aquatic environment. We collected total 60 samples from reservoirs in Taiwan. The water samples are divided into two parts for both direct concentration method and culture method. The results show the different detection rates among seasons. For Acanthamoeba, the detection rates were 28.3% (17 of 60 water samples), 21.7% (13 of 60 water samples) and 8.3% (5 of 60 water samples) in autumn, winter and spring, respectively. For Naegleria, the detection rates were 6.7% (4 of 60 water samples), 0% (0 of 60 water samples) and 0% (0 of 60 water samples) were detected positive in autumn, winter and spring, respectively. Sequence analysis showed that the major genotypes in Acanthamoeba were T3, T4, T10 and T11 in autumn, T2, T4 and T10 in winter, T4 in spring. Due to the presences of Acanthamoeba and Naegleria in reservoirs, we should pay more attention in water quality monitoring to prevent the potential risks of diseases. Keywords: free-living amoeba, Acanthamoeba, Naegleria, polymerase

  18. Diversity and community structure of testate amoebae (protista) in tropical montane rain forests of southern Ecuador: altitudinal gradient, aboveground habitats and nutrient limitation.

    OpenAIRE

    Krashevs'ka, Valentyna

    2009-01-01

    The tropical Andes in southern Ecuador constitute a hotspot of plant (especially trees and bryophytes) and animal (especially birds, bats, arctiid and geometrid mothes) diversity. However, data on small animals such as testate amoebae as an important component of the soil and aboveground community are lacking. Variations in density, diversity and community structure of testate amoebae along altitudinal transects in tropical regions are largely unknown. Testate amoebae colonize almost any habi...

  19. Comparison of Free-Living Amoebae in Hot Water Systems of Hospitals with Isolates from Moist Sanitary Areas by Identifying Genera and Determining Temperature Tolerance

    OpenAIRE

    Rohr, Ute; Weber, Susanne; Michel, Rolf; Selenka, Fidelis; Wilhelm, Michael

    1998-01-01

    Legionella-contaminated hot water systems and moist sanitary areas in six hospitals were sampled for amoebae by following a standardized collection protocol. Genus identifications and temperature tolerance determinations were made. Amoebae identified as Hartmannella vermiformis (65%), Echinamoebae spp. (15%), Saccamoebae spp. (12%), and Vahlkampfia spp. (9%) were detected in 29 of 56 (52%) hot water samples. Twenty-three of 49 (47%) swabs obtained from moist areas were amoeba positive. The fo...

  20. Efecto de la estructuración por macrófitas y por recursos alimentarios en la distribución horizontal de tecamebas y rotíferos en un lago andino patagónico Effect of macrophytes and food resources on the horizontal distribution of testate amoebae and rotifers in an Andean-Patagonian lake

    Directory of Open Access Journals (Sweden)

    MARCELA BASTIDAS-NAVARRO

    2007-09-01

    con el aumento de la abundancia de la cianofita Coelosphaerium kuetzingianum. Las diferencias señaladas indican que los recursos alimentarios serían un factor determinante en la distribución de especies de tecamebas y rotíferos en el lago Escondido. Para estos zoopláncteres de pequeño tamaño las macrófitas litorales brindarían alimento al favorecer el incremento del fitoplancton de redThe presence of macrophytes in the littoral zone of lakes produces particular conditions including higher resource availability for consumers. For this reason, the littoral zone is generally the area with the highest diversity of lakes and rivers. In this work we studied the horizontal distribution of testate amoebae and rotifers in Lago Escondido (Argentina in relation to food resources availability. The study was carried out along a north-south transect that includes the littoral and the pelagic zone of the lake. Phytoplankton and zooplankton were sampled during summer and spring (2001-2003 in five sampling stations: one pelagic and four littoral. Rotifers and testate amoebae, as well as phytoplanktonic algae abundance and biomass were estimated. Food resources were classified as nanoplankton ( 20 μm and the biovolume of these fractions varied significantly within the pelagic and littoral zones of the lake. Nanoplankon dominated the pelagic zone and was mainly composed by nanoflagellates while net phytoplankton prevailed in the littoral zone and was composed by diatoms, cyanophytes and chlorophytes. The highest number of species and diversity of testate amoebae and rotifers were observed in the littoral stations; nevertheless, no significant differences between the zones colonized by different macrophytes were observed. The CCA analysis showed four different groups. Keratella cochlearis, Synchaeta spp., Polyarthra vulgaris and Collotheca mutabilis characterized the pelagic samples and were related with a high abundance of nanoplankton. On the other hand, rotifers like

  1. Engineering an artificial amoeba propelled by nanoparticle-triggered actin polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Yi Jinsoo; Schmidt, Jacob; Chien Aichi; Montemagno, Carlo D [Department of Bioengineering, University of California Los Angeles, 420 Westwood Plaza, 7523 Boelter Hall, Los Angeles, CA 90095-1600 (United States)], E-mail: montemcd@ucmail.uc.edu

    2009-02-25

    We have engineered an amoeba system combining nanofabricated inorganic materials with biological components, capable of propelling itself via actin polymerization. The nanofabricated materials have a mechanism similar to the locomotion of the Listeria monocytogenes, food poisoning bacteria. The propulsive force generation utilizes nanoparticles made from nickel and gold functionalized with the Listeria monocytogenes transmembrane protein, ActA. These Listeria-mimic nanoparticles were in concert with actin, actin binding proteins, ATP (adenosine triphosphate) and encapsulated within a lipid vesicle. This system is an artificial cell, such as a vesicle, where artificial nanobacteria and actin polymerization machinery are used in driving force generators inside the cell. The assembled structure was observed to crawl on a glass surface analogously to an amoeba, with the speed of the movement dependent on the amount of actin monomers and ATP present.

  2. Engineering an artificial amoeba propelled by nanoparticle-triggered actin polymerization

    International Nuclear Information System (INIS)

    We have engineered an amoeba system combining nanofabricated inorganic materials with biological components, capable of propelling itself via actin polymerization. The nanofabricated materials have a mechanism similar to the locomotion of the Listeria monocytogenes, food poisoning bacteria. The propulsive force generation utilizes nanoparticles made from nickel and gold functionalized with the Listeria monocytogenes transmembrane protein, ActA. These Listeria-mimic nanoparticles were in concert with actin, actin binding proteins, ATP (adenosine triphosphate) and encapsulated within a lipid vesicle. This system is an artificial cell, such as a vesicle, where artificial nanobacteria and actin polymerization machinery are used in driving force generators inside the cell. The assembled structure was observed to crawl on a glass surface analogously to an amoeba, with the speed of the movement dependent on the amount of actin monomers and ATP present.

  3. Reconstruction of active regular motion in amoeba extract: dynamic cooperation between sol and gel states.

    Science.gov (United States)

    Nishigami, Yukinori; Ichikawa, Masatoshi; Kazama, Toshiya; Kobayashi, Ryo; Shimmen, Teruo; Yoshikawa, Kenichi; Sonobe, Seiji

    2013-01-01

    Amoeboid locomotion is one of the typical modes of biological cell migration. Cytoplasmic sol-gel conversion of an actomyosin system is thought to play an important role in locomotion. However, the mechanisms underlying sol-gel conversion, including trigger, signal, and regulating factors, remain unclear. We developed a novel model system in which an actomyosin fraction moves like an amoeba in a cytoplasmic extract. Rheological study of this model system revealed that the actomyosin fraction exhibits shear banding: the sol-gel state of actomyosin can be regulated by shear rate or mechanical force. Furthermore, study of the living cell indicated that the shear-banding property also causes sol-gel conversion with the same order of magnitude as that of shear rate. Our results suggest that the inherent sol-gel transition property plays an essential role in the self-regulation of autonomous translational motion in amoeba.

  4. Bacterial killing in macrophages and amoeba: do they all use a brass dagger?

    Science.gov (United States)

    German, Nadezhda; Doyscher, Dominik; Rensing, Christopher

    2013-10-01

    Macrophages are immune cells that are known to engulf pathogens and destroy them by employing several mechanisms, including oxidative burst, induction of Fe(II) and Mn(II) efflux, and through elevation of Cu(I) and Zn(II) concentrations in the phagosome ('brass dagger'). The importance of the latter mechanism is supported by the presence of multiple counteracting efflux systems in bacteria, responsible for the efflux of toxic metals. We hypothesize that similar bacteria-killing mechanisms are found in predatory protozoa/amoeba species. Here, we present a brief summary of soft metal-related mechanisms used by macrophages, and perhaps amoeba, to inactivate and destroy bacteria. Based on this, we think it is likely that copper resistance is also selected for by protozoan grazing in the environment.

  5. An intracellular replication niche for Vibrio cholerae in the amoeba Acanthamoeba castellanii.

    Science.gov (United States)

    Van der Henst, Charles; Scrignari, Tiziana; Maclachlan, Catherine; Blokesch, Melanie

    2016-04-01

    Vibrio cholerae is a human pathogen and the causative agent of cholera. The persistence of this bacterium in aquatic environments is a key epidemiological concern, as cholera is transmitted through contaminated water. Predatory protists, such as amoebae, are major regulators of bacterial populations in such environments. Therefore, we investigated the interaction between V. cholerae and the amoeba Acanthamoeba castellanii at the single-cell level. We observed that V. cholerae can resist intracellular killing. The non-digested bacteria were either released or, alternatively, established a replication niche within the contractile vacuole of A. castellanii. V. cholerae was maintained within this compartment even upon encystment. The pathogen ultimately returned to its aquatic habitat through lysis of A. castellanii, a process that was dependent on the production of extracellular polysaccharide by the pathogen. This study reinforces the concept that V. cholerae is a facultative intracellular bacterium and describes a new host-pathogen interaction.

  6. Free-living amoebae isolated from water-hyacinth root (Eichhornia crassipes).

    Science.gov (United States)

    Ramirez, Elizabeth; Robles, Esperanza; Martinez, Blanca

    2010-09-01

    Free-living amoebae are widely distributed in aquatic environments and their hygienic, medical and ecological relationships to man are increasingly important. The purpose of this study was to isolate free-living amoebae from water-hyacinth root (Eichhornia crassipes) and the water of an urban lake in Mexico City. Five grams of wet root were seeded on non-nutritive agar with Enterobacter aerogenes (NNE). Water samples were concentrated by centrifugation at 1200g for 15min and the pellet was seeded on NNE. Of the 16 isolated genera, 10 were detected in both habitats. The most frequent were Vannella in root and Acanthamoeba and Naegleria in water. The total number of isolates and genera isolated from root was higher than that isolated from water. The differences between root and water are probably due to the morphological characteristics of water-hyacinth root, which provides a large habitat and refuge area for many organisms.

  7. [Regulation of cortical cytoskeleton dynamics during migration of free-living amoebae].

    Science.gov (United States)

    Kłopocka, Wanda; Redowicz, Maria Jolanta; Wasik, Anna

    2009-01-01

    Amoeba proteus and smaller by an order of magnitude (and evolutionary younger) Acanthamoeba castellanii have been for many years model cells for studies of amoeboidal (crawling) type of movement, characteristic also for some of metazoan cells such as fibroblasts, granulocytes and macrophages. Amoeboidal migration is indispensable of organization and dynamics of actin-based cytoskeleton. While there is a number of data on molecular mechanisms of motility of A. castellanii, there is very little known about bases of migration of A. proteus. Noteworthy, a large A. proteus (length approximately 600 microm) have been from over a century an object for studies on biology and physiology of cellular migration. This review describes the current knowledge on molecular aspects of force generation required for migration of these two amoebae and attempts to compare the functioning and regulation of actin cytoskeleton in these free-living unicellular species.

  8. Free-living amoebae: what part do they play in healthcare-associated infections?

    Science.gov (United States)

    Cateau, E; Delafont, V; Hechard, Y; Rodier, M H

    2014-07-01

    Free-living amoebae (FLA) are ubiquitous protozoa that do not require a host organism for survival. They are found in natural environments such as water or soil, and man-made environments including tap water or swimming pools, where they may interact with other micro-organisms, including bacteria, fungi and viruses. FLA can harbour micro-organisms including those found in hospital water systems, offering them protection against hostile conditions, providing a vehicle of dissemination, and enabling them to prepare for subsequent survival in macrophages. The interaction between Legionella pneumophila and FLA has been studied extensively; subsequent investigations have shown that FLA may serve as a reservoir for other bacteria including mycobacteria, Pseudomonas aeruginosa, Acinetobacter baumannii, or even fungi and viruses. Amoebae found in hospital water systems can serve as a reservoir of potential pathogens and thus be indirectly related to healthcare-associated infections.

  9. Polymerase chain reaction detection of potentially pathogenic free-living amoebae in dental units.

    Science.gov (United States)

    Leduc, Annie; Gravel, Sabrina; Abikhzer, Jérémie; Roy, Stéphane; Barbeau, Jean

    2012-07-01

    Several genera of amoebae can be found in water from dental units and on the inner surface of waterlines. The presence of bacterial biofilms on these surfaces is thought to favor the proliferation of amoebae. Potentially pathogenic Acanthamoeba and Naegleria spp. may be an infection risk for patients through contact with open surgical sites or aerosolization. A polymerase chain reaction of DNA extracted from pelleted samples showed that Acanthamoeba spp. and Naegleria spp. were present in water from dental units, suction lines, and suction filters at the dental clinic of the Université de Montréal. Acanthamoeba spp. were detected in 24.2% of 66 samples and Naegleria spp. in 3.0%. We discuss the infection risk associated with these results.

  10. Knowledge of morphology is still required when identifying new amoeba isolates by molecular techniques.

    Science.gov (United States)

    De Jonckheere, Johan F; Gryseels, Sophie; Eddyani, Miriam

    2012-08-01

    We have isolated several free-living amoeba strains from the environment in Ghana, which have internal transcribed spacers, including the 5.8S rDNA, sequences similar to sequences attributed to Vahlkampfiidae (Heterolobosea) in databases. However, morphological examination shows that the isolates belong to the Hartmannellidae (Amoebozoa). We provide evidence that the sequences in the databases are wrongly classified as belonging to a genus or species of the Vahlkampfiidae, but rather belong to strains of the genus Hartmannella.

  11. Phospholipids trigger Cryptococcus neoformans capsular enlargement during interactions with amoebae and macrophages.

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    Cara J Chrisman

    2011-05-01

    Full Text Available A remarkable aspect of the interaction of Cryptococcus neoformans with mammalian hosts is a consistent increase in capsule volume. Given that many aspects of the interaction of C. neoformans with macrophages are also observed with amoebae, we hypothesized that the capsule enlargement phenomenon also had a protozoan parallel. Incubation of C. neoformans with Acanthamoeba castellanii resulted in C. neoformans capsular enlargement. The phenomenon required contact between fungal and protozoan cells but did not require amoeba viability. Analysis of amoebae extracts showed that the likely stimuli for capsule enlargement were protozoan polar lipids. Extracts from macrophages and mammalian serum also triggered cryptococcal capsular enlargement. C. neoformans capsule enlargement required expression of fungal phospholipase B, but not phospholipase C. Purified phospholipids, in particular, phosphatidylcholine, and derived molecules triggered capsular enlargement with the subsequent formation of giant cells. These results implicate phospholipids as a trigger for both C. neoformans capsule enlargement in vivo and exopolysaccharide production. The observation that the incubation of C. neoformans with phospholipids led to the formation of giant cells provides the means to generate these enigmatic cells in vitro. Protozoan- or mammalian-derived polar lipids could represent a danger signal for C. neoformans that triggers capsular enlargement as a non-specific defense mechanism against potential predatory cells. Hence, phospholipids are the first host-derived molecules identified to trigger capsular enlargement. The parallels apparent in the capsular response of C. neoformans to both amoebae and macrophages provide additional support for the notion that certain aspects of cryptococcal virulence emerged as a consequence of environmental interactions with other microorganisms such as protists.

  12. [CHROMATIN ORGANIZATION IN CELL CYCLE OF AMOEBA PROTEUS ACCORDING TO OPTICAL TOMOGRAPHY DATA].

    Science.gov (United States)

    Demin, S Yu; Berdieva, M A; Podlipaeva, Yu I; Yudin, A L; Goodkov, A V

    2015-01-01

    For the first time the nuclear cycle of large freshwater amoeba Amoeba proteus was studied by the method of optical tomography. The nuclei were fixed in situ in the cells of synchronized culture, stained by DAPI and examined by confocal laser scanning microscope. 3D-images of intranuclear chromatin were studied in details at different stages of nuclear cycle. The obtained data, together with literary ones allow represent the dynamics of structural organization of the nucleus in Amoeba proteus cell cycle in a new fashion. It was concluded that in this species the two-stage interphase takes place, as well as mitosis of peculiar type which does not correspond to any known type of mitosis according to classification existing now. It is presumed that in the course of nuclear cycle the chromosomes and/or their fragments are amplified, this presumption being in a good correspondence with the data about nuclear DNA hyperreplication in the cell cycle of A. proteus. As a result of chromosomes amplification their number may vary at different stages of cell cycle, and it allows to explain the contradictory data concerning the exact number of chromosomes in this species. The elimination of extra-DNA occurs mainly at the stage between prophase and prometaphase. We presume the majority of chromosomes, or may be even all of them to be referred to cholocentric type according to their behaviour during the mitosis.

  13. Pathogenic and opportunistic free-living amoebae: Acanthamoeba spp., Balamuthia mandrillaris, Naegleria fowleri, and Sappinia diploidea.

    Science.gov (United States)

    Visvesvara, Govinda S; Moura, Hercules; Schuster, Frederick L

    2007-06-01

    Among the many genera of free-living amoebae that exist in nature, members of only four genera have an association with human disease: Acanthamoeba spp., Balamuthia mandrillaris, Naegleria fowleri and Sappinia diploidea. Acanthamoeba spp. and B. mandrillaris are opportunistic pathogens causing infections of the central nervous system, lungs, sinuses and skin, mostly in immunocompromised humans. Balamuthia is also associated with disease in immunocompetent children, and Acanthamoeba spp. cause a sight-threatening infection, Acanthamoeba keratitis, mostly in contact-lens wearers. Of more than 30 species of Naegleria, only one species, N. fowleri, causes an acute and fulminating meningoencephalitis in immunocompetent children and young adults. In addition to human infections, Acanthamoeba, Balamuthia and Naegleria can cause central nervous system infections in animals. Because only one human case of encephalitis caused by Sappinia diploidea is known, generalizations about the organism as an agent of disease are premature. In this review we summarize what is known of these free-living amoebae, focusing on their biology, ecology, types of disease and diagnostic methods. We also discuss the clinical profiles, mechanisms of pathogenesis, pathophysiology, immunology, antimicrobial sensitivity and molecular characteristics of these amoebae.

  14. Survey of pathogenic free-living amoebae and Legionella spp. in mud spring recreation area.

    Science.gov (United States)

    Hsu, Bing-Mu; Lin, Che-Li; Shih, Feng-Cheng

    2009-06-01

    Acanthamoeba, Hartmannella, and Naegleria are free-living amoebae, ubiquitous in aquatic environments. Several species within these genera are recognized as potential human pathogens. These free-living amoebae may facilitate the proliferation of their parasitical bacteria, such as Legionella. In this study, we identified Acanthamoeba, Hartmannella, Naegleria, and Legionella using various analytical procedures and investigated their occurrence at a mud spring recreation area in Taiwan. We investigated factors potentially associated with the prevalence of the pathogens, including various water types, and physical and microbiological water quality parameters. Spring water was collected from 34 sites and Acanthamoeba, Hartmannella, Naegleria, and Legionella were detected in 8.8%, 35.3%, 14.7%, and 47.1%, respectively. The identified species of Acanthamoeba included Acanthamoeba castellanii and Acanthamoeba polyphaga. Nearly all the Hartmannella isolates are identified as Hartmannella vermiformis. The Naegleria species included Naegleria australiensis and its sister groups, and two other isolates referred to a new clade of Naegleria genotypes. The Legionella species identified included unnamed Legionella genotypes, Legionella pneumophila serotype 6, uncultured Legionella spp., Legionella lytica, Legionella drancourtii, and Legionella waltersii. Significant differences (Mann-Whitney U test, Pfree-living amoebae and Legionella are prevalent in this Taiwanese mud spring recreation area. The presence of pathogens should be considered a potential health threat when associated with human activities in spring water.

  15. Potentially pathogenic free-living amoebae isolated from hospital wards with immunodeficient patients in Tehran, Iran.

    Science.gov (United States)

    Lasjerdi, Zohreh; Niyyati, Maryam; Haghighi, Ali; Shahabi, Saed; Biderouni, Farid Tahvildar; Taghipour, Niloofar; Eftekhar, Mohamad; Nazemalhosseini Mojarad, Ehsan

    2011-09-01

    This study investigated the occurrence of free-living amoebae (FLA) in immunodeficiency wards of hospitals in Tehran, Iran. A total of 70 dust and biofilm samples from wards serving transplant, pediatric (malignancies), HIV, leukemia and oncology patients of five university hospitals were collected and examined for the presence of FLA using culturing and molecular approaches. Based on the morphology of the amoebae in plate cultures, primer sets were applied for molecular identification of Acanthamoeba, vahlkampfiid amoebae and Hartmannella. Out of 70 samples, 37 (52.9%) were positive for FLA. Acanthamoeba belonged to the T4 genotype was the most prevalent isolate. Presence of the T4 genotype on medical instruments, including an oxygen mask in an isolation room of an immunodeficiency pediatric ward, should be of concern for health authorities. Acanthamoeba T5 genotypes, Hartmannella vermiformis, and Vahlkampfia avara were also present. These results highlight a clear need for greater attention to improved disinfection, especially where susceptible patients, such as those who are immune-suppressed, are served. To our knowledge, this is the first report of these FLA in immunodeficiency wards in Iran, and also the first to identify Acanthamoeba T5, Hartmannella, and Vahlkampfia in moist habitats, such as biofilms, in this country.

  16. Isolation of Free-Living Amoebae from Sarein Hot Springs in Ardebil Province, Iran

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    A Badirzadeh

    2011-06-01

    Full Text Available Background: Free-living amoebae (FLA are a group of ubiquitous protozoan, which are distrib­uted in the natural and artificial environment sources. The main aim of the current study was to identify the presence of FLA in the recreational hot springs of Sarein in Ardebil Province of Iran.Methods: Seven recreational hot springs were selected in Sarein City and 28 water samples (four from each hot spring were collected using 500 ml sterile plastic bottles during three month. Filtra­tion of water samples was performed, and culture was done in non-nutrient agar medium enriched with Escherichia coli. Identification of the FLA was based on morphological criteria of cysts and trophozoites. Genotype identification of Acanthamoeba positive samples were also per­formed using sequencing based method.Results: Overall, 12 out of 28 (42.9% samples were positive for FLA which Acanthamoeba and Vahlkampfiid amoebae were found in one (3.6% and 11 (39.3% samples, respectively. Se­quence analysis of the single isolate of Acanthamoeba revealed potentially pathogenic T4 geno­type corresponding to A. castellanii.Conclusion: Contamination of hot springs to FLA, such as Acanthamoeba T4 genotype (A. castel­lanii and Vahlkampfiid amoebae, could present a sanitary risk for high risk people, and health authorities must be aware of FLA presence.

  17. Free-living amoebae and their intracellular pathogenic microorganisms: risks for water quality.

    Science.gov (United States)

    Thomas, Vincent; McDonnell, Gerald; Denyer, Stephen P; Maillard, Jean-Yves

    2010-05-01

    An increasing number of microorganisms, including bacteria but also viruses and eukaryotes, have been described as benefiting from interaction with free-living amoebae (FLA). Beneficial interaction can be due to resistance to predation conferring ecological advantage, intracellular survival and/or intracellular proliferation. This review highlights the potential risk associated with amoebae by listing all known pathogenic microbial species for which growth and/or survival promotion by FLA (mainly Acanthamoeba spp.) has been demonstrated. It focuses on the susceptibility of amoebal and intra-amoebal bacteria to various categories of biocides, the known mechanisms of action of these biocides against trophozoites and cysts and the various methods used to demonstrate efficacy of treatments against FLA. Brief descriptions of FLA ecology and prevalence in domestic/institutional water systems and their intrinsic pathogenicity are also presented. The intention is to provide an informed opinion on the environmental risks associated with the presence of FLA and on the survival of cysts following biocidal treatments, while also highlighting the need to conduct research on the roles of amoebae in aquatic ecosystems.

  18. Free-living Amoebae (FLA: morphological and molecular identification of Acanthamoeba in dental unit water

    Directory of Open Access Journals (Sweden)

    Trabelsi H.

    2010-03-01

    Full Text Available The aim of our study was to detect free-living Amoebae (FLA by morphological methods and to identify Acanthamoeba spp. by PCR in the dental unit water lines (DUWL. Materials and methods: it was a prospective study dealing with 196 water samples collected from DUWL (94 samples taken in the early morning before materials flush and patient consultations and 102 samples taken after consultations. At the same time, 39 samples from tap water were realized. Results: 135 (69 % samples were positives by the morphological study with morphotypical diversity. The predominant morphotype was the monopodial (39.2 %. 18 strains of Acanthamoeba spp. were detected in DUW (13.3 % and three strains in tap water (10 %. The amplification of 18S rDNA gene of these strains of Acanthamoeba spp. was positive for all samples. Conclusion: the FLA and Acanthamoeba were isolated both in tap water and in dental unit. The amoeba pathogenicity has not been demonstrated after oral or dental contamination; but the presence of intracellular and pathogenic bacteria in the amoeba could be a source of microbiological risks for patients in case of deep dental care or immunodepression. The improvement of this dental unit was necessary by putting a filter of 0.2 microns porosity before the arrival of the water in hand-pieces allowing the limitation of FLA passage.

  19. "Candidatus Mesochlamydia elodeae" (Chlamydiae: Parachlamydiaceae), a novel chlamydia parasite of free-living amoebae.

    Science.gov (United States)

    Corsaro, Daniele; Müller, Karl-Dieter; Wingender, Jost; Michel, Rolf

    2013-02-01

    Vannella sp. isolated from waterweed Elodea sp. was found infected by a chlamydia-like organism. This organism behaves like a parasite, causing the death through burst of its host. Once the vannellae degenerated, the parasite was successfully kept in laboratory within a Saccamoeba sp. isolated from the same waterweed sample, which revealed in fine through electron microscopy to harbor two bacterial endosymbionts: the chlamydial parasite we introduce and another endosymbiont initially and naturally present in the host. Herein, we provide molecular-based identification of both the amoeba host and its two endosymbionts, with special focus on the chlamydia parasite. High sequence similarity values of the 18S rDNA permitted to assign the amoeba to the species Saccamoeba lacustris (Amoebozoa, Tubulinea). The bacterial endosymbiont naturally harbored by the host belonged to Sphingomonas koreensis (Alpha-Proteobacteria). The chlamydial parasite showed a strict specificity for Saccamoeba spp., being unable to infect a variety of other amoebae, including Acanthamoeba, and it was itself infected by a bacteriophage. Sequence similarity values of the 16S rDNA and phylogenetic analysis indicated that this strain is a new member of the family Parachlamydiaceae, for which we propose the name "Candidatus Mesochlamydia elodeae."

  20. Development of AMOEBA force field for 1,3-dimethylimidazolium based ionic liquids.

    Science.gov (United States)

    Starovoytov, Oleg N; Torabifard, Hedieh; Cisneros, G Andrés

    2014-06-26

    The development of AMOEBA (a multipolar polarizable force field) for imidazolium based ionic liquids is presented. Our parametrization method follows the AMOEBA procedure and introduces the use of QM intermolecular total interactions as well as QM energy decomposition analysis (EDA) to fit individual interaction energy components. The distributed multipoles for the cation and anions have been derived using both the Gaussian distributed multipole analysis (GDMA) and Gaussian electrostatic model-distributed multipole (GEM-DM) methods.1 The intermolecular interactions of a 1,3-dimethylimidazolium [dmim(+)] cation with various anions, including fluoride [F(-)], chloride [Cl(-)], nitrate [NO(3)(-)], and tetraflorouborate [BF(4)(-)], were studied using quantum chemistry calculations at the MP2/6-311G(d,p) level of theory. Energy decomposition analysis was performed for each pair using the restricted variational space decomposition approach (RVS) at the HF/6-311G(d,p) level. The new force field was validated by running a series of molecular dynamic (MD) simulations and by analyzing thermodynamic and structural properties of these systems. A number of thermodynamic properties obtained from MD simulations were compared with available experimental data. The ionic liquid structure reproduced using the AMOEBA force field is also compared with the data from neutron diffraction experiment and other MD simulations. Employing GEM-DM force fields resulted in a good agreement on liquid densities ρ, enthalpies of vaporization ΔH(vap), and diffusion coefficients D(±) in comparison with conventional force fields. PMID:24901255

  1. A weak pulsed magnetic field affects adenine nucleotide oscillations, and related parameters in aggregating Dictyostelium discoideum amoebae.

    Science.gov (United States)

    Davies, E; Olliff, C; Wright, I; Woodward, A; Kell, D

    1999-02-01

    A model eukaryotic cell system was used to explore the effect of a weak pulsed magnetic field (PMF) on time-varying physiological parameters. Dictyostelium discoideum cells (V12 strain) were exposed to a pulsed magnetic field (PMF) of flux density 0.4 mT, generated via air-cored coils in trains of 2 ms pulses gated at 20 ms. This signal is similar to those used to treat non-uniting fractures. Samples were taken over periods of 20 min from harvested suspensions of amoebae during early aggregation phase, extracted and derivatised for HPLC fluorescent assay of adenine nucleotides. Analysis of variance showed a significant athermal damping effect (P < 0.002, n = 22) of the PMF on natural adenine nucleotide oscillations and some consistent changes in phase relationships. The technique of nonlinear dielectric spectroscopy (NLDS) revealed a distinctive effect of PMF, caffeine and EGTA in modulating the cellular harmonic response to an applied weak signal. Light scattering studies also showed altered frequency response of cells to PMF, EGTA and caffeine. PMF caused a significant reduction of caffeine induced cell contraction (P < 0.0006, n = 19 by paired t-test) as shown by Malvern particle size analyser, suggesting that intracellular calcium may be involved in mediating the effect of the PMF. PMID:10228582

  2. The social amoeba Polysphondylium pallidum loses encystation and sporulation, but can still erect fruiting bodies in the absence of cellulose.

    Science.gov (United States)

    Du, Qingyou; Schaap, Pauline

    2014-09-01

    Amoebas and other freely moving protists differentiate into walled cysts when exposed to stress. As cysts, amoeba pathogens are resistant to biocides, preventing treatment and eradication. Lack of gene modification procedures has left the mechanisms of encystation largely unexplored. Genetically tractable Dictyostelium discoideum amoebas require cellulose synthase for formation of multicellular fructifications with cellulose-rich stalk and spore cells. Amoebas of its distant relative Polysphondylium pallidum (Ppal), can additionally encyst individually in response to stress. Ppal has two cellulose synthase genes, DcsA and DcsB, which we deleted individually and in combination. Dcsa- mutants formed fruiting bodies with normal stalks, but their spore and cyst walls lacked cellulose, which obliterated stress-resistance of spores and rendered cysts entirely non-viable. A dcsa-/dcsb- mutant made no walled spores, stalk cells or cysts, although simple fruiting structures were formed with a droplet of amoeboid cells resting on an sheathed column of decaying cells. DcsB is expressed in prestalk and stalk cells, while DcsA is additionally expressed in spores and cysts. We conclude that cellulose is essential for encystation and that cellulose synthase may be a suitable target for drugs to prevent encystation and render amoeba pathogens susceptible to conventional antibiotics.

  3. Ménage-à-trois: the amoeba Nuclearia sp. from Lake Zurich with its ecto- and endosymbiotic bacteria.

    Science.gov (United States)

    Dirren, Sebastian; Salcher, Michaela M; Blom, Judith F; Schweikert, Michael; Posch, Thomas

    2014-09-01

    We present a fascinating triad relationship between a eukaryotic amoeba and its two bacterial symbionts. The morphological characteristics of the amoeba allowed for a confident assignment to the genus Nuclearia (Opisthokonta, Nucleariidae), but species identification resulted in an ambiguous result. Sequence analysis indicated an affiliation to the species N. thermophila, however, several morphological features contradict the original description. Amoebal isolates were cultured for several years with their preferred food source, the microcystin-producing harmful cyanobacterium Planktothrix rubescens. Symbioses of the amoeba with ecto- and endosymbiotic bacteria were maintained over this period. Several thousand cells of the ectosymbiont are regularly arranged inside a layer of extracellular polymeric substances produced by the amoeba. The ectosymbiont was identified as Paucibacter toxinivorans (Betaproteobacteria), which was originally isolated by enrichment with microcystins. We found indications that our isolated ectosymbiont indeed contributed to toxin-degradation. The endosymbiont (Gammaproteobacteria, 15-20 bacteria per amoeba) is enclosed in symbiosomes inside the host cytoplasm and represents probably an obligate symbiont. We propose the name "Candidatus Endonucleariobacter rarus" for this bacterium that was neither found free-living nor in a symbiotic association. Nucleariidae are uniquely suited model organisms to study the basic principles of symbioses between opisthokonts and prokaryotes.

  4. Impairment of O-antigen production confers resistance to grazing in a model amoeba-cyanobacterium predator-prey system.

    Science.gov (United States)

    Simkovsky, Ryan; Daniels, Emy F; Tang, Karen; Huynh, Stacey C; Golden, Susan S; Brahamsha, Bianca

    2012-10-01

    The grazing activity of predators on photosynthetic organisms is a major mechanism of mortality and population restructuring in natural environments. Grazing is also one of the primary difficulties in growing cyanobacteria and other microalgae in large, open ponds for the production of biofuels, as contaminants destroy valuable biomass and prevent stable, continuous production of biofuel crops. To address this problem, we have isolated a heterolobosean amoeba, HGG1, that grazes upon unicellular and filamentous freshwater cyanobacterial species. We have established a model predator-prey system using this amoeba and Synechococcus elongatus PCC 7942. Application of amoebae to a library of mutants of S. elongatus led to the identification of a grazer-resistant knockout mutant of the wzm ABC O-antigen transporter gene, SynPCC7942_1126. Mutations in three other genes involved in O-antigen synthesis and transport also prevented the expression of O-antigen and conferred resistance to HGG1. Complementation of these rough mutants returned O-antigen expression and susceptibility to amoebae. Rough mutants are easily identifiable by appearance, are capable of autoflocculation, and do not display growth defects under standard laboratory growth conditions, all of which are desired traits for a biofuel production strain. Thus, preventing the production of O-antigen is a pathway for producing resistance to grazing by certain amoebae.

  5. Mycobacterium abscessus phospholipase C expression is induced during coculture within amoebae and enhances M. abscessus virulence in mice.

    Science.gov (United States)

    Bakala N'Goma, Jean Claude; Le Moigne, Vincent; Soismier, Nathalie; Laencina, Laura; Le Chevalier, Fabien; Roux, Anne-Laure; Poncin, Isabelle; Serveau-Avesque, Carole; Rottman, Martin; Gaillard, Jean-Louis; Etienne, Gilles; Brosch, Roland; Herrmann, Jean-Louis; Canaan, Stéphane; Girard-Misguich, Fabienne

    2015-02-01

    Mycobacterium abscessus is a pathogenic, rapidly growing mycobacterium involved in pulmonary and cutaneo-mucous infections worldwide, to which cystic fibrosis patients are exquisitely susceptible. The analysis of the genome sequence of M. abscessus showed that this bacterium is endowed with the metabolic pathways typically found in environmental microorganisms that come into contact with soil, plants, and aquatic environments, where free-living amoebae are frequently present. M. abscessus also contains several genes that are characteristically found only in pathogenic bacteria. One of them is MAB_0555, encoding a putative phospholipase C (PLC) that is absent from most other rapidly growing mycobacteria, including Mycobacterium chelonae and Mycobacterium smegmatis. Here, we report that purified recombinant M. abscessus PLC is highly cytotoxic to mouse macrophages, presumably due to hydrolysis of membrane phospholipids. We further showed by constructing and using an M. abscessus PLC knockout mutant that loss of PLC activity is deleterious to M. abscessus intracellular survival in amoebae. The importance of PLC is further supported by the fact that M. abscessus PLC was found to be expressed only in amoebae. Aerosol challenge of mice with M. abscessus strains that were precultured in amoebae enhanced M. abscessus lung infectivity relative to M. abscessus grown in broth culture. Our study underlines the importance of PLC for the virulence of M. abscessus. Despite the difficulties of isolating M. abscessus from environmental sources, our findings suggest that M. abscessus has evolved in close contact with environmental protozoa, which supports the argument that amoebae may contribute to the virulence of opportunistic mycobacteria.

  6. The Salmonella pathogenicity island 2-encoded type III secretion system is essential for the survival of Salmonella enterica serovar Typhimurium in free-living amoebae.

    Science.gov (United States)

    Bleasdale, Benjamin; Lott, Penelope J; Jagannathan, Aparna; Stevens, Mark P; Birtles, Richard J; Wigley, Paul

    2009-03-01

    Free-living amoebae represent a potential reservoir and predator of Salmonella enterica. Through the use of type III secretion system (T3SS) mutants and analysis of transcription of selected T3SS genes, we demonstrated that the Salmonella pathogenicity island 2 is highly induced during S. enterica serovar Typhimurium infection of Acanthamoeba polyphaga and is essential for survival within amoebae.

  7. Comparison of free-living amoebae in hot water systems of hospitals with isolates from moist sanitary areas by identifying genera and determining temperature tolerance.

    Science.gov (United States)

    Rohr, U; Weber, S; Michel, R; Selenka, F; Wilhelm, M

    1998-05-01

    Legionella-contaminated hot water systems and moist sanitary areas in six hospitals were sampled for amoebae by following a standardized collection protocol. Genus identifications and temperature tolerance determinations were made. Amoebae identified as Hartmannella vermiformis (65%), Echinamoebae spp. (15%), Saccamoebae spp. (12%), and Vahlkampfia spp. (9%) were detected in 29 of 56 (52%) hot water samples. Twenty-three of 49 (47%) swabs obtained from moist areas were amoeba positive. The following genera were identified: Acanthamoeba (22%), Naegleria (22%), Vahlkampfia (20%), Hartmannella (15%), and Vanella (7%). The temperature tolerance of amoebae from hot water systems was strikingly different from that of amoebae from moist areas. At 44 degrees C on agar, 59% of amoebic isolates sampled from hot water systems showed growth. The corresponding value for isolates from moist areas was only 17%. Six Acanthamoeba isolates from the moist areas were considered potential pathogens. Four Hartmannella and two Saccamoeba isolates from hot water could be cultured at 53 degrees C. PMID:9572957

  8. Testate amoeba Rhogostoma minus Belar, 1921, associated with nodular gill disease of rainbow trout, Oncorhynchus mykiss (Walbaum).

    Science.gov (United States)

    Dyková, I; Tyml, T

    2016-05-01

    The case study targeted to determine the aetiology of nodular gill disease (NGD) of farmed rainbow trout. The methods included microscopical examination of gill material in fresh, culturing of isolated organisms, histology, transmission electron microscopy and molecular biology identification. The results revealed an intravital colonization of fish gills by the testate amoeba Rhogostoma minus Belar, 1921. Rhogostoma infection was found in all fish examined microscopically (15/15); in contrast, naked amoebae related to fully developed NGD lesions were found in minority of these fish (5/15). They belonged to four genera, Acanthamoeba, Vermamoeba, Naegleria and Vannella. Results presented in this study contribute to the mosaic of findings that contrary to amoebic gill disease of marine fish turn attention to the possibility of the heterogeneous, multi-amoeba-species and multifactorial aetiology of NGD.

  9. Response of forest soil euglyphid testate amoebae (Rhizaria: Cercozoa) to pig cadavers assessed by high-throughput sequencing.

    Science.gov (United States)

    Seppey, Christophe V W; Fournier, Bertrand; Szelecz, Ildikò; Singer, David; Mitchell, Edward A D; Lara, Enrique

    2016-03-01

    Decomposing cadavers modify the soil environment, but the effect on soil organisms and especially on soil protists is still poorly documented. We conducted a 35-month experiment in a deciduous forest where soil samples were taken under pig cadavers, control plots and fake pigs (bags of similar volume as the pigs). We extracted total soil DNA, amplified the SSU ribosomal RNA (rRNA) gene V9 region and sequenced it by Illumina technology and analysed the data for euglyphid testate amoebae (Rhizaria: Euglyphida), a common group of protozoa known to respond to micro-environmental changes. We found 51 euglyphid operational taxonomic units (OTUs), 45 of which did not match any known sequence. Most OTUs decreased in abundance underneath cadavers between days 0 and 309, but some responded positively after a time lag. We sequenced the full-length SSU rRNA gene of two common OTUs that responded positively to cadavers; a phylogenetic analysis showed that they did not belong to any known euglyphid family. This study confirmed the existence of an unknown diversity of euglyphids and that they react to cadavers. Results suggest that metabarcoding of soil euglyphids could be used as a forensic tool to estimate the post-mortem interval (PMI) particularly for long-term (>2 months) PMI, for which no reliable tool exists. PMID:25874666

  10. Iron metabolism and resistance to infection by invasive bacteria in the social amoeba Dictyostelium discoideum

    Directory of Open Access Journals (Sweden)

    Salvatore eBozzaro

    2013-09-01

    Full Text Available Dictyostelium cells are forest soil amoebae, which feed on bacteria and proliferate as solitary cells until bacteria are consumed. Starvation triggers a change in life style, forcing cells to gather into aggregates to form multicellular organisms capable of cell differentiation and morphogenesis. As a soil amoeba and a phagocyte that grazes on bacteria as the obligate source of food, Dictyostelium could be a natural host of pathogenic bacteria. Indeed, many pathogens that occasionally infect humans are hosted for most of their time in protozoa or free-living amoebae, where evolution of their virulence traits occurs. Due to these features and its amenability to genetic manipulation, Dictyostelium has become a valuable model organism for studying strategies of both the host to resist infection and the pathogen to escape the defence mechanisms. Similarly to higher eukaryotes, iron homeostasis is crucial for Dictyostelium resistance to invasive bacteria. Iron is essential for Dictyostelium, as both iron deficiency or overload inhibit cell growth. The Dictyostelium genome shares with mammals many genes regulating iron homeostasis. Iron transporters of the Nramp (Slc11A family are represented with two genes, encoding Nramp1 and Nramp2. Like the mammalian ortholog, Nramp1 is recruited to phagosomes and macropinosomes, whereas Nramp2 is a membrane protein of the contractile vacuole network, which regulates osmolarity. Nramp1 and Nramp2 localization in distinct compartments suggests that both proteins synergistically regulate iron homeostasis. Rather than by absorption via membrane transporters, iron is likely gained by degradation of ingested bacteria and efflux via Nramp1 from phagosomes to the cytosol. Nramp gene disruption increases Dictyostelium sensitivity to infection, enhancing intracellular growth of Legionella or Mycobacteria. Generation of mutants in other "iron genes" will help identify genes essential for iron homeostasis and resistance to

  11. Investigating the role of free-living amoebae as a reservoir for Mycobacterium ulcerans.

    Directory of Open Access Journals (Sweden)

    Nana Ama Amissah

    2014-09-01

    Full Text Available The reservoir and mode of transmission of Mycobacterium ulcerans, the causative agent of Buruli ulcer, still remain a mystery. It has been suggested that M. ulcerans persists with difficulty as a free-living organism due to its natural fragility and inability to withstand exposure to direct sunlight, and thus probably persists within a protective host environment.We investigated the role of free-living amoebae as a reservoir of M. ulcerans by screening the bacterium in free-living amoebae (FLA cultures isolated from environmental specimens using real-time PCR. We also followed the survival of M. ulcerans expressing green fluorescence protein (GFP in Acanthameoba castellanii by flow cytometry and observed the infected cells using confocal and transmission electron microscopy for four weeks in vitro. IS2404 was detected by quantitative PCR in 4.64% of FLA cultures isolated from water, biofilms, detritus and aerosols. While we could not isolate M. ulcerans, 23 other species of mycobacteria were cultivated from inside FLA and/or other phagocytic microorganisms. Laboratory experiments with GFP-expressing M. ulcerans in A. castellani trophozoites for 28 days indicated the bacteria did not replicate inside amoebae, but they could remain viable at low levels in cysts. Transmission electron microscopy of infected A. castellani confirmed the presence of bacteria within both trophozoite vacuoles and cysts. There was no correlation of BU notification rate with detection of the IS2404 in FLA (r = 0.07, n = 539, p = 0.127.This study shows that FLA in the environment are positive for the M. ulcerans insertion sequence IS2404. However, the detection frequency and signal strength of IS2404 positive amoabae was low and no link with the occurrence of BU was observed. We conclude that FLA may host M. ulcerans at low levels in the environment without being directly involved in the transmission to humans.

  12. Iron metabolism and resistance to infection by invasive bacteria in the social amoeba Dictyostelium discoideum.

    Science.gov (United States)

    Bozzaro, Salvatore; Buracco, Simona; Peracino, Barbara

    2013-01-01

    Dictyostelium cells are forest soil amoebae, which feed on bacteria and proliferate as solitary cells until bacteria are consumed. Starvation triggers a change in life style, forcing cells to gather into aggregates to form multicellular organisms capable of cell differentiation and morphogenesis. As a soil amoeba and a phagocyte that grazes on bacteria as the obligate source of food, Dictyostelium could be a natural host of pathogenic bacteria. Indeed, many pathogens that occasionally infect humans are hosted for most of their time in protozoa or free-living amoebae, where evolution of their virulence traits occurs. Due to these features and its amenability to genetic manipulation, Dictyostelium has become a valuable model organism for studying strategies of both the host to resist infection and the pathogen to escape the defense mechanisms. Similarly to higher eukaryotes, iron homeostasis is crucial for Dictyostelium resistance to invasive bacteria. Iron is essential for Dictyostelium, as both iron deficiency or overload inhibit cell growth. The Dictyostelium genome shares with mammals many genes regulating iron homeostasis. Iron transporters of the Nramp (Slc11A) family are represented with two genes, encoding Nramp1 and Nramp2. Like the mammalian ortholog, Nramp1 is recruited to phagosomes and macropinosomes, whereas Nramp2 is a membrane protein of the contractile vacuole network, which regulates osmolarity. Nramp1 and Nramp2 localization in distinct compartments suggests that both proteins synergistically regulate iron homeostasis. Rather than by absorption via membrane transporters, iron is likely gained by degradation of ingested bacteria and efflux via Nramp1 from phagosomes to the cytosol. Nramp gene disruption increases Dictyostelium sensitivity to infection, enhancing intracellular growth of Legionella or Mycobacteria. Generation of mutants in other "iron genes" will help identify genes essential for iron homeostasis and resistance to pathogens.

  13. Detection of a parasitic amoeba (Order Dactylopodida) in the female gonads of oysters in Brazil.

    Science.gov (United States)

    Sühnel, Simone; Ivachuk, Celene da S; Schaefer, Ana L C; Pontinha, Vitor A; Martins, Maurício L; Figueras, Antonio; Meyer, Gary R; Jones, Simon R M; Stewart, Johnson C; Gurney-Smith, Helen J; Magalhães, Aimê R M; Bower, Susan M

    2014-07-01

    The impacts of oocyte parasites on the reproductive success of molluscs are largely unknown. In this study, we evaluated the presence of gonad parasites in 6 species of marine bivalve molluscs native to southern Brazil. Cultured bivalves included the mangrove oyster Crassostrea gasar (sometimes called C. brasiliana), the brown mussel Perna perna, the lion's paw scallop Nodipecten nodosus and the wing pearl oyster Pteria hirundo. Another species of mangrove oyster, C. rhizophorae, and the carib pointed venus clam Anomalocardia brasiliana (syn. A. flexuosa) were collected from the wild. Molluscs were collected in winter 2009 and summer 2010 for histopathological and molecular evaluation. An unknown ovarian parasite (UOP) was observed in histopathological sections of female gonads of C. gasar and C. rhizophorae. The UOP possessed features suggestive of amoebae, including an irregular outer membrane, frothy cytoplasm, a nucleus with a prominent central nucleolus and a closely associated basophilic parasome. PCR analysis was negative for Marteilioides chungmuensis, Perkinsus spp. and Paramoeba perurans. However, real-time PCR successfully amplified DNA from oyster gonads when using universal Paramoeba spp. primers. Also, conventional PCR amplified DNA using primers specific for Perkinsela amoebae-like organisms (syn. Perkinsiella), which are considered as endosymbionts of Parameoba spp., previously thought to be the parasome. Our results suggest that this UOP is a species of amoeba belonging to 1 of the 2 families of the order Dactylopodida, possibly related to Paramoeba spp. This study represents the first report of this type of organism in oysters. We found that C. gasar and C. rhizophorae were the most susceptible molluscs to these UOPs.

  14. Computational identification of putative miRNAs and their target genes in pathogenic amoeba Naegleria fowleri.

    Science.gov (United States)

    Padmashree, Dyavegowda; Swamy, Narayanaswamy Ramachandra

    2015-01-01

    Naegleria fowleri is a parasitic unicellular free living eukaryotic amoeba. The parasite spreads through contaminated water and causes primary amoebic meningoencephalitis (PAM). Therefore, it is of interest to understand its molecular pathogenesis. Hence, we analyzed the parasite genome for miRNAs (microRNAs) that are non-coding, single stranded RNA molecules. We identified 245 miRNAs using computational methods in N. fowleri, of which five miRNAs are conserved. The predicted miRNA targets were analyzed by using miRanda (software) and further studied the functions by subsequently annotating using AmiGo (a gene ontology web tool).

  15. Cellular, biochemical, and molecular changes during encystment of free-living amoebae.

    Science.gov (United States)

    Fouque, Emilie; Trouilhé, Marie-Cécile; Thomas, Vincent; Hartemann, Philippe; Rodier, Marie-Hélène; Héchard, Yann

    2012-04-01

    Free-living amoebae are protozoa found in soil and water. Among them, some are pathogenic and many have been described as potential reservoirs of pathogenic bacteria. Their cell cycle is divided into at least two forms, the trophozoite and the cyst, and the differentiation process is named encystment. As cysts are more resistant to disinfection treatments than trophozoites, many studies focused on encystment, but until recently, little was known about cellular, biochemical, and molecular modifications operating during this process. Important signals and signaling pathways at play during encystment, as well as cell responses at the molecular level, have been described. This review summarizes our knowledge and focuses on new findings.

  16. Isolation of Free-Living Amoebae from Sarein Hot Springs in Ardebil Province, Iran

    OpenAIRE

    Badirzadeh, A; Niyyati, M; Babaei, Z; Amini, H.; H Badirzadeh; Rezaeian, M.

    2011-01-01

    Background: Free-living amoebae (FLA) are a group of ubiquitous protozoan, which are distrib­uted in the natural and artificial environment sources. The main aim of the current study was to identify the presence of FLA in the recreational hot springs of Sarein in Ardebil Province of Iran.Methods: Seven recreational hot springs were selected in Sarein City and 28 water samples (four from each hot spring) were collected using 500 ml sterile plastic bottles during three month. Filtra­tion of wat...

  17. SSU rRNA reveals a sequential increase in shell complexity among the euglyphid testate amoebae (Rhizaria: Euglyphida)

    DEFF Research Database (Denmark)

    Lara, Enrique; Heger, Thierry J; Mitchell, Edward A D;

    2007-01-01

    The existing data on the molecular phylogeny of filose testate amoebae from order Euglyphida has revealed contradictions between traditional morphological classification and SSU rRNA phylogeny and, moreover, the position of several important genera remained unknown. We therefore carried out a study...... aiming to fill several important gaps and better understand the relationships among the main euglyphid testate amoebae and the evolutionary steps that led to the present diversity at a higher level. We obtained new SSU rRNA sequences from five genera and seven species. This new phylogeny obtained shows...

  18. Testate amoebae (Protozoa Rhizopoda in two biotopes of Ubatiba stream, Maricá, Rio de Janeiro State

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    Viviane Bernardes dos Santos Miranda

    2015-07-01

    Full Text Available Four samplings were carried out during the dry and rainy seasons in 2014, in two biotopes (plankton and aquatic macrophytes to assess the composition and species richness of testate amoebae community in a coastal stream in the state of Rio de Janeiro, Brazil. Results showed great representation of Difflugiidae, Centropyxidae, Lesquereusiidae and Arcellidae families. Higher richness was observed in the plankton samples and higher densities of testate amoebae were reported among the aquatic vegetation during the dry season. Current investigation is a pioneer study conducted in the Ubatiba stream. Further researches on these protists, especially in Rio de Janeiro, should be undertaken.

  19. Use of highly sensitive sublethal stress responses in the social amoeba Dictyostelium discoideum for an assessment of freshwater quality.

    Science.gov (United States)

    Sforzini, Susanna; Dagnino, Alessandro; Torrielli, Sara; Dondero, Francesco; Fenoglio, Stefano; Negri, Alessandro; Boatti, Lara; Viarengo, Aldo

    2008-06-01

    In this work, the sensitivity of a battery of tests on the social amoeba Dictyostelium discoideum has been assessed within a freshwater toxicity study. The results obtained from the evaluation of survival and replication rate of D. discoideum were compared to those derived with a series of widely used tests for freshwater toxicity assessment, i. e. bioassays using Vibrio fischeri, Daphnia magna and Pseudokirchneriella subcapitata. The effects on sublethal endpoints, i.e. lysosomal membrane stability (LMS) and endocytotic rate, were analysed in conjunction with high-level endpoints to verify the potential to make a typical bioassay more sensitive. The field ecotoxicological investigation employing D. discoideum is part of a monitoring study assessing environmental quality of the Bormida River (Italy), subjected until recently to a chronic industrial pollution. The survey was carried out at several stations (upstream and downstream of a chemical factory outlet) in two different periods. In 2002, the results of chemical analyses performed on river water indicated no contamination. The ecotoxicological data obtained in this period showed that no evidence of biological effects was observed using V. fischeri and D. magna bioassays. In spite of the previous classical acute toxicity tests, significant differences in cell viability of D. discoideum were found. By analysing the effects measured on LMS and endocytotic rate, more relevant changes were observed for these sublethal stress biomarkers compared to survival. The chronic toxicity data showed significant changes in cell growth both of P. subcapitata and D. discoideum. Nevertheless, more sensitive and rapid responses were obtained when assessing the effects of exposure on D. discoideum. The chemical and ecotoxicological data obtained in 2006 indicated a full recovery of the quality of the river water (neither contamination nor toxicity found). Altogether, the results reported in this study underline that the use of a

  20. Testate amoebae communities from some freshwater and soil habitats in China (Hubei and Shandong Provinces)

    Institute of Scientific and Technical Information of China (English)

    Anatoly BOBROV; Yuri MAZEI; Viktor CHERNYSHOV; Yingchun GONG; Weisong FENG

    2012-01-01

    Seventy-eight species and forms of testate amoebae were identified from 29 freshwater and soil habitats in three territories of China (Shandong and Hubei Provinces).Most abundant species from the genera Plagiopyxis,Centropyxis and Trinema represent the globally-distributed and eurybiont group of testate amoebae.The species richness was observed to be the lowest (7-12 species per biotope) in sandy sediments of the Yangtze River,but considerably higher (20-30 taxa) in soil environment.In the range of terrestrial habitats,the most remote communities from Laoshan Mountain in Shandong Province,China manifested the highest difference from others.On the other hand,communities originated in the most distant from industrial center places (Guifeng Mountain in Hubei Province,China) possess the most peculiar species composition including specific Gondwanian taxa (e.g.Nebela bigibbosa).In sum,the results obtained provide the evidence that the community complexity and specificity reduce in the places located within areas that are highly populated and intensively visited by humans.

  1. Archaeological occurrences and historical review of the human amoeba, Entamoeba histolytica, over the past 6000years.

    Science.gov (United States)

    Le Bailly, Matthieu; Maicher, Céline; Dufour, Benjamin

    2016-08-01

    Understanding parasite history and the evolution of host/parasite relationships is one of the most important aspects of paleoparasitology. Within the framework of this research topic, this paper focuses on the human pathogenic amoeba, Entamoeba histolytica. The compilation of all the available archaeological data concerning this parasite leads to a first glimpse of the history of this parasite of current medical importance. Paleoparasitological investigation into this parasite uses immunological techniques and shows that the modern strain of E. histolytica has been present in Western Europe since at least the Neolithic period (3700yearsBCE), and could have originated in the Old World. The appearance of the modern amoeba strain in the pre-Columbian Americas and the Middle East around the 12th century CE gives rise to hypotheses as to how human migrations (Atlantic or Pacific routes) contributed to the diffusion of this pathogen, resulting in its current distribution. This compilation proves that parasites are valuable proxies for studying past human and animal migrations, and should be given more consideration in the future.

  2. Development of a nested PCR assay to detect the pathogenic free-living amoeba Naegleria fowleri.

    Science.gov (United States)

    Réveiller, Fabienne L; Cabanes, Pierre-André; Marciano-Cabral, Francine

    2002-05-01

    Naegleria fowleri is the causative agent of primary amoebic meningoencephalitis, a fatal disease of the central nervous system that is acquired while swimming or diving in freshwater. A cDNA clone designated Mp2C15 obtained from N. fowleri was used as a probe to distinguish N. fowleri from other free-living amoebae. The Mp2C15 probe hybridized to genomic DNA from pathogenic N. fowleri and antigenically related non-pathogenic N. lovaniensis. Mp2C15 was digested with the restriction enzyme XbaI, resulting in two fragments, Mp2C15.G and Mp2C15.P. Four species of Naegleria and four species of Acanthamoeba were examined for reactivity with Mp2C15.P. Mp2C15.P was specific for N. fowleri and was used in the development of a nested PCR assay which is capable of detecting as little as 5 pg of N. fowleri DNA or five intact N. fowleri amoebae. In summary, a rapid, sensitive, and specific assay for the detection of N. fowleri was developed.

  3. Acanthamoeba and other free-living amoebae in bat guano, an extreme habitat.

    Science.gov (United States)

    Mulec, Janez; Dietersdorfer, Elisabeth; Üstüntürk-Onan, Miray; Walochnik, Julia

    2016-04-01

    Several representatives of the so-called free-living amoebae (FLA) are of medical relevance, not only as facultative pathogens but also as vehicles for pathogenic bacteria. Some FLA can survive and even grow under extreme environmental conditions. Bat guano is an exceptional habitat, the conditions becoming gradually more extreme with aging. In the current study, samples of bat guano of different ages from five caves in Slovenia were screened for the presence of FLA. FLA were isolated from almost all guano samples, including guano with a pH of 3.5. Only the two samples that had been drawn from >20-year-old guano were negative for FLA. Generally, FLA diversity correlated to high concentrations of cultivable bacteria (∼10(8) CFU/g) and fungi (∼10(5) CFU/g). Interestingly, the absence of FLA in seasoned guanos was mirrored by the presence of dictyostelid slime moulds. The isolated amoebae were identified as belonging to the genera Acanthamoeba, Copromyxa, Naegleria, Sappinia, Tetramitus, Thecamoeba, Vahlkampfia, Vannella and Vermamoeba. To the best of our knowledge, this is the first study on the diversity of FLA in guano.

  4. Old lineages in a new ecosystem: diversification of arcellinid amoebae (Amoebozoa and peatland mosses.

    Directory of Open Access Journals (Sweden)

    Omar Fiz-Palacios

    Full Text Available Arcellinid testate amoebae (Amoebozoa form a group of free-living microbial eukaryotes with one of the oldest fossil records known, yet several aspects of their evolutionary history remain poorly understood. Arcellinids occur in a range of terrestrial, freshwater and even brackish habitats; however, many arcellinid morphospecies such as Hyalosphenia papilio are particularly abundant in Sphagnum-dominated peatlands, a relatively new ecosystem that appeared during the diversification of Sphagnum species in the Miocene (5-20 Myr ago. Here, we reconstruct divergence times in arcellinid testate amoebae after selecting several fossils for clock calibrations and then infer whether or not arcellinids followed a pattern of diversification that parallels the pattern described for Sphagnum. We found that the diversification of core arcellinids occurred during the Phanerozoic, which is congruent with most arcellinid fossils but not with the oldest known amoebozoan fossil (i.e. at ca. 662 or ca. 750 Myr. Overall, Sphagnum and the Hyalospheniidae exhibit different patterns of diversification. However, an extensive molecular phylogenetic analysis of distinct clades within H. papilio species complex demonstrated a correlation between the recent diversification of H. papilio, the recent diversification of Sphagnum mosses, and the establishment of peatlands.

  5. Do free-living amoebae in treated drinking water systems present an emerging health risk?

    Science.gov (United States)

    Thomas, Jacqueline M; Ashbolt, Nicholas J

    2011-02-01

    There is an expanding body of evidence that free-living amoebae (FLA) increase both the numbers and virulence of water-based, human-pathogenic, amoeba-resisting microorganisms (ARM). Legionella spp., Mycobacterium spp., and other opportunistic human pathogens are known to be both ARM and also the etiologic agents of potentially fatal human lung infections. However, comparatively little is known about the FLA that may facilitate ARM growth in drinking water. This review examines the available literature on FLA in treated drinking water systems; in total 26 studies from 18 different countries. FLA were reported to breakthrough the water treatment barrier and enter distribution systems, in addition to the expected post-treatment system ingress. Once in the distribution system there is evidence of FLA colonization and regrowth especially in reservoirs and in-premise plumbing storage tanks. At the point of use the average FLA detection rate was 45% but highly variable (n = 16, σ = 31) due to both differences in both assay methods and the type of water systems examined. This review reveals that FLA are consistently detected in treated drinking water systems around the world and present a yet unquantified emerging health risk. However, more research is urgently required before accurate risks assessments can be undertaken to assess the impacts on human health, in households and institutions, due to exposure to FLA facilitated pathogenic ARM.

  6. Detection of free-living amoebae by using multiplex quantitative PCR.

    Science.gov (United States)

    Le Calvez, Thomas; Trouilhé, Marie-Cécile; Humeau, Philippe; Moletta-Denat, Marina; Frère, Jacques; Héchard, Yann

    2012-06-01

    Free-living amoebae (FLA) are protozoa found worldwide in soil and aquatic environments, which are able to colonize man-made water networks. Some FLA have the potential to be pathogenic and others might harbour pathogenic bacteria. Indeed, FLA feed on bacteria, but some bacteria could resist phagocytosis and either survive in FLA or even multiply within FLA. These bacteria are collectively named amoeba resistant bacteria (ARB). The best characterized example is Legionella pneumophila, for which FLA is the main reservoir in the environment. Not only could FLA be a reservoir that protects ARB, some bacteria might become more resistant to treatment and be more virulent. Thus, it is of medical significance to quantify FLA populations in soil, water or the environment. The main limitation for the quantification of FLA is that classical culture is not efficient and reliable for many genera and 'strains'. Thus, several PCR-based quantification methods have been published for various FLA. However, thus far, no method has been published to simultaneously quantify the main FLA genera in the same PCR reaction. In this study, we developed a multiplex qPCR method to detect both Amoebozoan (i.e. Acanthamoeba, Hartmannella and Echinamoeba) and Vahlkampfiidae (i.e. Vahlkampfia and Naegleria) using 18S ribosomal RNA as the target gene. This method was shown to be specific, reliable and sensitive, could be used for the quantification of FLA and is likely to be useful to anticipate risks due to FLA or pathogenic bacteria, such as L. pneumophila.

  7. Isolation and molecular characterization of free-living amoebae from different water sources in Italy.

    Science.gov (United States)

    Montalbano Di Filippo, Margherita; Santoro, Maristella; Lovreglio, Piero; Monno, Rosa; Capolongo, Carmen; Calia, Carla; Fumarola, Luciana; D'Alfonso, Rossella; Berrilli, Federica; Di Cave, David

    2015-03-24

    Free-living amoebae (FLA) are protozoa ubiquitous in Nature, isolated from a variety of environments worldwide. In addition to their natural distribution, some species have been found to be pathogenic to humans. In the present study a survey was conducted in order to evaluate the presence and to characterize at molecular level the isolates of amoebic organisms collected from different water sources in Italy. A total of 160 water samples were analyzed by culture and microscopic examination. FLA were found in 46 (28.7%) of the investigated water samples. Groundwater, well waters, and ornamental fountain waters were the sources with higher prevalence rates (85.7%, 50.0%, and 45.9%, respectively). Identification of FLA species/genotypes, based on the 18S rDNA regions, allowed to identify 18 (39.1%) Acanthamoeba isolates (genotypes T4 and T15) and 21 (45.6%) Vermamoeba vermiformis isolates. Other FLA species, including Vahlkampfia sp. and Naegleria spp., previously reported in Italy, were not recovered. The occurrence of potentially pathogenic free-living amoebae in habitats related to human population, as reported in the present study, supports the relevance of FLA as a potential health threat to humans.

  8. Relevance of free-living amoebae as hosts for phylogenetically diverse microorganisms.

    Science.gov (United States)

    Scheid, Patrick

    2014-07-01

    In addition to their role as parasites, free-living amoebae (FLA) can act as hosts of and vehicles for phylogentically diverse microorganisms while some of them replicate intracellularly. These microorganisms are adapted to the intracellular conditions in the amoeba, find suitable conditions and protection from negative environmental influences and take advantage of the dispersal in the environment by their amoebic host. It is expedient to call these organisms "endocytobionts", at least during the initial steps of any studies. By doing so, it is not necessary to go into potential characteristics of these relationships such as parasitism, phoresy, zoochory, or mutualism at an early stage of study. Among those organisms resisting the lysis within their amoebic host, there are obligate and facultative pathogenic microorganisms affecting the health of humans or animals. FLA-endocytobiont relationships are not only important for the tenacity of the involved microorganisms. Especially if FLA are present in biofilms and there are close ties with many other microorganisms, the odds are for some of these microorganisms to develop human pathogenic properties. Here, the amoebic passage seems to be a prerequisite for the development of virulence factors and it may have an impact on evolutionary processes.

  9. Isolation and Molecular Characterization of Free-Living Amoebae from Different Water Sources in Italy

    Directory of Open Access Journals (Sweden)

    Margherita Montalbano Di Filippo

    2015-03-01

    Full Text Available Free-living amoebae (FLA are protozoa ubiquitous in Nature, isolated from a variety of environments worldwide. In addition to their natural distribution, some species have been found to be pathogenic to humans. In the present study a survey was conducted in order to evaluate the presence and to characterize at molecular level the isolates of amoebic organisms collected from different water sources in Italy. A total of 160 water samples were analyzed by culture and microscopic examination. FLA were found in 46 (28.7% of the investigated water samples. Groundwater, well waters, and ornamental fountain waters were the sources with higher prevalence rates (85.7%, 50.0%, and 45.9%, respectively. Identification of FLA species/genotypes, based on the 18S rDNA regions, allowed to identify 18 (39.1% Acanthamoeba isolates (genotypes T4 and T15 and 21 (45.6% Vermamoeba vermiformis isolates. Other FLA species, including Vahlkampfia sp. and Naegleria spp., previously reported in Italy, were not recovered. The occurrence of potentially pathogenic free-living amoebae in habitats related to human population, as reported in the present study, supports the relevance of FLA as a potential health threat to humans.

  10. Growth ability of Gram negative bacteria in free-living amoebae.

    Science.gov (United States)

    Zeybek, Zuhal; Binay, Ali Rıza

    2014-11-01

    When bacteria and free-living amoebae (FLAs) live both in natural waters and man-made aquatic systems, they constantly interact with each other. Some bacteria can survive and grow within FLAs. Therefore, it has recently been thought that FLAs play an important role in spreading pathogenic bacteria in aquatic systems. In this study we investigated the intracellular growing ability of 7 different Gram-negative bacteria (Pseudomonas fluorescens, Pseudomonas putida, Pasteurella pneumotropica, Aeromonas salmonicida, Legionella pneumophila serogroup 1, L. pneumophila serogroup 3, L. pneumophila serogroup 6) in four different FLA isolates (A1-A4). Among these, four bacterial isolates (P. fluorescens, P.putida, P.pneumotropica, A.salmonicida) and two free-living amoebae isolates (A3, A4) were isolated from the tap water in our city (Istanbul). It was found that 4 different Gram-negative bacteria could grow in A1, 2 different Gram-negative bacteria could grow in A2, 4 different Gram-negative bacteria could grow in A3, 1 Gram-negative bacterium could grow in A4. In conclusion, we think that this ability of growth could vary according to the characteristics of both bacteria and FLA isolates. Also, other factors such as environmental temperature, bacterial concentration, and extended incubation period may play a role in these interactions. This situation can be clarified with future studies.

  11. Occurrence of free-living amoebae in streams of the Mexico Basin.

    Science.gov (United States)

    Bonilla-Lemus, Patricia; Caballero Villegas, Adán S; Carmona Jiménez, Javier; Lugo Vázquez, Alfonso

    2014-11-01

    Free-living amoebae (FLA) are protozoa that are widely distributed in nature. They are important in the cycling of nutrients in aquatic food chains, but their distribution in natural aquatic environments is not well known. We conducted a survey to determine the presence and distribution of FLA and their relation to some physicochemical parameters in streams of the Mexico Basin in Central Mexico. Thirty-two sites from 18 streams were sampled. Samples were centrifuged and cultured onto NNA-media to isolate amoebae. Identifications were based on morphology. The pathogenicity of Acanthamoeba isolates was tested. Oxygen saturation, temperature, pH, specific conductance, water flow, dissolved reactive phosphorus, nitrites, nitrates, ammonia, dissolved inorganic nitrogen and coliforms were determined. One hundred-and-twenty FLA representing 18 genera were identified. The most frequent genera were Vannella, Rosculus and Acanthamoeba. The frequency of potentially pathogenic FLA was low and only 3 Acanthamoeba isolates were invasive in mice. The highest species richness of FLA was found in streams located into agriculture activity areas and those close to small villages that discharge wastewater into them. Water temperatures were always below 17°C. Oxygen saturation and pH were within the limits for the growth of most FLA. The presence of Acanthamoeba and Naegleria was low; nevertheless, they include potentially pathogenic species and can act as vectors and reservoirs for microbial pathogens and can produce human infections.

  12. Potentially pathogenic free-living amoebae (FLA) isolated in Spanish wastewater treatment plants.

    Science.gov (United States)

    García, A; Goñi, P; Clavel, A; Lobez, S; Fernandez, M T; Ormad, M P

    2011-10-01

    This work studies the characterization of pathogenic free-living amoebae (FLA) from sewage effluents. Some of them, such as Acanthamoeba, Naegleria, Hartmannella, Sappinia, Balamuthia and Paravahlkampfia have been reported as a cause of diseases in humans. Therefore, the study of their habitats and their pathogenicity has become necessary. The population of potentially pathogenic FLA was analysed in five Spanish wastewater treatment plants. Five of the seven FLA isolated were identified as genus Acanthamoeba genotypes T3, T4, T7 and T9. Hartmannella and Naegleria were also isolated. Acanthamoeba demonstrated great thermotolerance and osmotolerance. It was also observed that treatment with sodium hypochlorite showed no significative reduction in the number of amoeba at concentrations of 0-100 ppm. The high resistance of FLA cysts to disinfection methods is a trojan horse for public health insofar as they colonize water systems and allow the survival of intracellular microorganisms resistant to FLA. The results of this work advance current knowledge of the FLA population.

  13. Archaeological occurrences and historical review of the human amoeba, Entamoeba histolytica, over the past 6000years.

    Science.gov (United States)

    Le Bailly, Matthieu; Maicher, Céline; Dufour, Benjamin

    2016-08-01

    Understanding parasite history and the evolution of host/parasite relationships is one of the most important aspects of paleoparasitology. Within the framework of this research topic, this paper focuses on the human pathogenic amoeba, Entamoeba histolytica. The compilation of all the available archaeological data concerning this parasite leads to a first glimpse of the history of this parasite of current medical importance. Paleoparasitological investigation into this parasite uses immunological techniques and shows that the modern strain of E. histolytica has been present in Western Europe since at least the Neolithic period (3700yearsBCE), and could have originated in the Old World. The appearance of the modern amoeba strain in the pre-Columbian Americas and the Middle East around the 12th century CE gives rise to hypotheses as to how human migrations (Atlantic or Pacific routes) contributed to the diffusion of this pathogen, resulting in its current distribution. This compilation proves that parasites are valuable proxies for studying past human and animal migrations, and should be given more consideration in the future. PMID:27130884

  14. Detection of Free-Living Amoebae Using Amoebal Enrichment in a Wastewater Treatment Plant of Gauteng Province, South Africa

    Directory of Open Access Journals (Sweden)

    P. Muchesa

    2014-01-01

    Full Text Available Free-living amoebae pose a potential health risk in water systems as they may be pathogenic and harbor potential pathogenic bacteria known as amoebae resistant bacteria. Free-living amoebae were observed in 150 (87.2% of the environmental water samples. In particular, Acanthamoeba sp. was identified in 22 (12.8% using amoebal enrichment and confirmed by molecular analysis. FLA were isolated in all 8 stages of the wastewater treatment plant using the amoebal enrichment technique. A total of 16 (9.3% samples were positive for FLA from influent, 20 (11.6% from bioreactor feed, 16 (9.3% from anaerobic zone, 16 (9.3% from anoxic zone, 32 (18.6% from aerators, 16 (9.3% from bioreactor effluent, 11 (6.4% from bioreactor final effluent, and 45 (26.2% from maturation pond. This study provides baseline information on the occurrence of amoebae in wastewater treatment plant. This has health implications on receiving water bodies as some FLA are pathogenic and are also involved in the transmission and dissemination of pathogenic bacteria.

  15. Detection of free-living amoebae using amoebal enrichment in a wastewater treatment plant of Gauteng Province, South Africa.

    Science.gov (United States)

    Muchesa, P; Mwamba, O; Barnard, T G; Bartie, C

    2014-01-01

    Free-living amoebae pose a potential health risk in water systems as they may be pathogenic and harbor potential pathogenic bacteria known as amoebae resistant bacteria. Free-living amoebae were observed in 150 (87.2%) of the environmental water samples. In particular, Acanthamoeba sp. was identified in 22 (12.8%) using amoebal enrichment and confirmed by molecular analysis. FLA were isolated in all 8 stages of the wastewater treatment plant using the amoebal enrichment technique. A total of 16 (9.3%) samples were positive for FLA from influent, 20 (11.6%) from bioreactor feed, 16 (9.3%) from anaerobic zone, 16 (9.3%) from anoxic zone, 32 (18.6%) from aerators, 16 (9.3%) from bioreactor effluent, 11 (6.4%) from bioreactor final effluent, and 45 (26.2%) from maturation pond. This study provides baseline information on the occurrence of amoebae in wastewater treatment plant. This has health implications on receiving water bodies as some FLA are pathogenic and are also involved in the transmission and dissemination of pathogenic bacteria.

  16. Shedding light on microbial dark matter: a TM6 bacterium as natural endosymbiont of a free-living amoeba.

    Science.gov (United States)

    Delafont, Vincent; Samba-Louaka, Ascel; Bouchon, Didier; Moulin, Laurent; Héchard, Yann

    2015-12-01

    The TM6 phylum belongs to the so-called microbial dark matter that gathers uncultivated bacteria detected only via DNA sequencing. Recently, the genome sequence of a TM6 bacterium (TM6SC1) has led to suggest that this bacterium would adopt an endosymbiotic life. In the present paper, free-living amoebae bearing a TM6 strain were isolated from a water network. The amoebae were identified as Vermamoeba vermiformis and the presence of a TM6 strain was detected by polymerase chain reaction and microscopy. The partial sequence of its 16S rRNA gene showed this strain to be closely related to the sequenced TM6SC1 strain. These bacteria displayed a pyriform shape and were found within V. vermiformis. Therefore, these bacteria were named Vermiphilus pyriformis. Interactions studies showed that V. pyriformis was highly infectious and that its relation with V. vermiformis was specific and highly stable. Finally, it was found that V. pyriformis inhibited the encystment of V. vermiformis. Overall, this study describes for the first time an endosymbiotic relationship between a TM6 bacterium and a free-living amoeba in the environment. It suggests that other bacteria of the TM6 phylum might also be endosymbiotic bacteria and may be found in other free-living amoebae or other organisms.

  17. Quantitative detection of the free-living amoeba Hartmannella vermiformis in surface water by using real-time PCR

    NARCIS (Netherlands)

    Kuiper, M.W.; Valster, R.M.; Wullings, B.A.; Boonstra, H.; Smidt, H.; Kooij, van der D.

    2006-01-01

    A real-time PCR-based method targeting the 18S rRNA gene was developed for the quantitative detection of Hartmannella vermiformis, a free-living amoeba which is a potential host for Legionella pneumophila in warm water systems and cooling towers. The detection specificity was validated using genomic

  18. First evidence of testate amoebae in Lago Fagnano (54° S), Tierra del Fuego (Argentina): Proxies to reconstruct environmental changes

    Science.gov (United States)

    Caffau, Mauro; Lenaz, Davide; Lodolo, Emanuele; Zecchin, Massimo; Comici, Cinzia; Tassone, Alejandro

    2015-12-01

    We report here the first findings of testate amoebae at high southern latitudes (54° S) from four gravity cores recovered in the Lago Fagnano (Tierra del Fuego, Argentina), where twelve taxa have been recognized. Among them, Centropyxis constricta "constricta", Centropyxis elongata, Difflugia globulus, Difflugia oblonga "oblonga", and Difflugia protaeiformis "amphoralis" are always present, while other taxa are randomly distributed. According to the sand/silt ratio in the different cores, the Total Organic Carbon content and the Carbon/Nitrogen ratio, as well as the presence/disappearance and abundance of testate amoebae from cluster analysis, we infer a correlation between major textural/granulometrical changes found in the cores and environmental changes. A seismic event occurred on 1949, which substantially modified the morphology of the eastern Lago Fagnano shoreline and the supply pattern from two main eastern tributaries of the lake, is recorded in the studied cores. This event has in part modified the distribution of testate amoebae taxa within the studied cores. Present results show that testate amoebae represent important indicators to detect changes occurring in the environment in which they live.

  19. Migration of amoeba cells in an electric field

    Science.gov (United States)

    Guido, Isabella; Bodenschatz, Eberhard

    2015-03-01

    Exogenous and endogenous electric fields play a role in cell physiology as a guiding mechanism for the orientation and migration of cells. Electrotaxis of living cells has been observed for several cell types, e.g. neurons, fibroblasts, leukocytes, neural crest cells, cancer cells. Dictyostelium discoideum (Dd), an intensively investigated chemotactic model organism, also exhibits a strong electrotactic behavior moving toward the cathode under the influence of electric fields. Here we report experiments on the effects of DC electric fields on the directional migration of Dd cells. We apply the electric field to cells seeded into microfluidic devices equipped with agar bridges to avoid any harmful effects of the electric field on the cells (ions formation, pH changes, etc.) and a constant flow to prevent the build-up of chemical gradient that elicits chemotaxis. Our results show that the cells linearly increase their speed over time when a constant electric field is applied for a prolonged duration (2 hours). This novel phenomenon cannot be attributed to mechanotaxis as the drag force of the electroosmotic flow is too small to produce shear forces that can reorient cells. It is independent of the cellular developmental stage and to our knowledge, it was not observed in chemotaxis. This work is supported by MaxSynBio project of the Max Planck Society.

  20. 长白山区泥炭地现代有壳变形虫环境意义探讨%ENVIRONMENTAL IMPLICATIONS OF THE MODERN TESTATE AMOEBAE IN THE PE

    Institute of Scientific and Technical Information of China (English)

    李鸿凯; 卜兆君; 王升忠; 安芷生; 赵红艳; 马云艳; 陈旭

    2009-01-01

    tests were recorded.Detrended correspondence analysis(DCA)shows that 4 peatlands have similar testate amoebae assemblages.Since th e length of gradient is short than 3,a linear ordination model,redundancy analysis(RDA),was used tzo explore the relationship between testate amoebae assemblages and 7 environmental variables including latitude,longitude,altitude,pH,conductivity,DWT,and moisture of peat.The results show that the 7 environmental variables explain 31.8% of variation in species data.DWT,pH and moisture of peat have greater marginal effects,which are 10%,9% and 8%,respectively.All of these three variables are extremely significantly correlated with axis 1 of ordination.So they are principal factors which determine the assemblage of testate amoebae in peatlands in the Changbai Mountains.Monte Carol significance tests(999 permutation)of DWT,pH and soil moisture are all p < 0.001,which proves that they can be target variables in developing transfer functions for quantitative paleo-environmental reconstruction.The conclusion of this paper is consistent with ecological studies of testate amoeba conducted in other regions in the world.This convinces us that testate amoebae can be an extra method in paleoecological study on peat sediments in the Changbai Mountains.Coupling with other proxies such as pollen,plant macrofossil,humification degree,and isotope composition,we can recover a more integrated picture for the past.

  1. Pathogenesis of amoebic encephalitis: Are the amoebae being credited to an 'inside job' done by the host immune response?

    Science.gov (United States)

    Baig, Abdul Mannan

    2015-08-01

    Pathogenic free living amoeba like Naegleria fowleri, Acanthamoeba spp., and Balamuthia mandrillaris are known to cause fatal "amoebic meningoencephalitis" by acquiring different route of entries to the brain. The host immune response to these protist pathogens differs from each another, as evidenced by the postmortem gross and microscopic findings from the brains of the affected patients. Cited with the expression of 'brain eating amoeba' when the infection is caused by N. fowleri, this expression is making its way into parasitology journals and books. The impression that it imparts is, as if the brain damage is substantially due to the enzymes and toxins produced by this amoeba. A detailed review of the literature, analysis of archived specimens and with our experimental assays, here we establish that with N. fowleri, Acanthamoeba and Balamuthia spp., the infections result in an extensive brain damage that in fact is substantially caused by the host immune response rather than the amoeba. Due to the comparatively larger sizes of these pathogens and the prior exposure of the amoebal antigen to the human body, the host immune system launches an amplified response that not only breaches the blood brain barrier (BBB), but also becomes the major cause of brain damage in Amoebic meningoencephalitis. It is our understanding that for N. fowleri the host immune response is dominated by acute inflammatory cytokines and that, in cases of Acanthamoeba and Balamuthia spp., it is the type IV hypersensitivity reaction that fundamentally not only contributes to disruption and leakiness of the blood brain barrier (BBB) but also causes the neuronal damage. The further intensification of brain damage is done by toxins and enzymes secreted by the amoeba, which causes the irreversible brain damage.

  2. Giants among larges: how gigantism impacts giant virus entry into amoebae.

    Science.gov (United States)

    Rodrigues, Rodrigo Araújo Lima; Abrahão, Jônatas Santos; Drumond, Betânia Paiva; Kroon, Erna Geessien

    2016-06-01

    The proposed order Megavirales comprises the nucleocytoplasmic large DNA viruses (NCLDV), infecting a wide range of hosts. Over time, they co-evolved with different host cells, developing various strategies to penetrate them. Mimiviruses and other giant viruses enter cells through phagocytosis, while Marseillevirus and other large viruses explore endocytosis and macropinocytosis. These differing strategies might reflect the evolution of those viruses. Various scenarios have been proposed for the origin and evolution of these viruses, presenting one of the most enigmatic issues to surround these microorganisms. In this context, we believe that giant viruses evolved independently by massive gene/size gain, exploring the phagocytic pathway of entry into amoebas. In response to gigantism, hosts developed mechanisms to evade these parasites.

  3. Words: blocks, amoebas, or patches of fog? Artificial intelligence and the conceptual foundations of fuzzy logic

    Science.gov (United States)

    Jaki, Stanley L.

    1996-06-01

    Words are the fundamental carriers of information. Words that refer to numbers stand apart from all other words in one respect: Numbers are concepts that lend themselves to spatial representations with exact contours. Yet the verbal definition of numbers, through which their meaning is defined, shares in a property common to all words: their verbal definition cannot be given a spatial representation with exact contours. In that definitional respect, words are not even comparable to amoebas which, although they constantly change their shapes, have clear boundaries. Words are best to be likened to patches of fog that not only change but have no strict boundaries. While this does not land all discourse in the realm of half-truths, it sets basic limits to what can be achieved by fuzzy logic and programs of artificial intelligence.

  4. 变形虫模型构造%Introduction of Amoeba Computational Model

    Institute of Scientific and Technical Information of China (English)

    阮军; 李德华

    2009-01-01

    为了将信息技术为代表的高技术群服务于现代战争的分析和模拟,提出变形虫模型(Amoeba ComputationalModel,ACM)作为"虚拟战争实验室"设计的核心思路.该模型通过运行阴阳五行的观点,把世界政治、军事、经济格局的演化与五行元素之间的相互作用的联系起来,采用复杂适应系统理论与系统动力学方法相结合的思路,试图建立初步的、开放的战争试验系统的系统理论架构.

  5. Spontaneous emergence of large-scale cell cycle synchronization in amoeba colonies

    Science.gov (United States)

    Segota, Igor; Boulet, Laurent; Franck, David; Franck, Carl

    2014-06-01

    Unicellular eukaryotic amoebae Dictyostelium discoideum are generally believed to grow in their vegetative state as single cells until starvation, when their collective aspect emerges and they differentiate to form a multicellular slime mold. While major efforts continue to be aimed at their starvation-induced social aspect, our understanding of population dynamics and cell cycle in the vegetative growth phase has remained incomplete. Here we show that cell populations grown on a substrate spontaneously synchronize their cell cycles within several hours. These collective population-wide cell cycle oscillations span millimeter length scales and can be completely suppressed by washing away putative cell-secreted signals, implying signaling by means of a diffusible growth factor or mitogen. These observations give strong evidence for collective proliferation behavior in the vegetative state.

  6. Bioaccumulation of pathogenic bacteria and amoeba by zebra mussels and their presence in watercourses.

    Science.gov (United States)

    Mosteo, R; Goñi, P; Miguel, N; Abadías, J; Valero, P; Ormad, M P

    2016-01-01

    Dreissena polymorpha (the zebra mussel) has been invading freshwater bodies in Europe since the beginning of the nineteenth century. Filter-feeding organisms can accumulate and concentrate both chemical and biological contaminants in their tissues. Therefore, zebra mussels are recognized as indicators of freshwater quality. In this work, the capacity of the zebra mussel to accumulate human pathogenic bacteria and protozoa has been evaluated and the sanitary risk associated with their presence in surface water has also been assessed. The results show a good correlation between the pathogenic bacteria concentration in zebra mussels and in watercourses. Zebra mussels could therefore be used as an indicator of biological contamination. The bacteria (Escherichia coli, Enterococcus spp., Pseudomonas spp., and Salmonella spp.) and parasites (Cryptosporidium oocysts and free-living amoebae) detected in these mussels reflect a potential sanitary risk in water.

  7. Giants among larges: how gigantism impacts giant virus entry into amoebae.

    Science.gov (United States)

    Rodrigues, Rodrigo Araújo Lima; Abrahão, Jônatas Santos; Drumond, Betânia Paiva; Kroon, Erna Geessien

    2016-06-01

    The proposed order Megavirales comprises the nucleocytoplasmic large DNA viruses (NCLDV), infecting a wide range of hosts. Over time, they co-evolved with different host cells, developing various strategies to penetrate them. Mimiviruses and other giant viruses enter cells through phagocytosis, while Marseillevirus and other large viruses explore endocytosis and macropinocytosis. These differing strategies might reflect the evolution of those viruses. Various scenarios have been proposed for the origin and evolution of these viruses, presenting one of the most enigmatic issues to surround these microorganisms. In this context, we believe that giant viruses evolved independently by massive gene/size gain, exploring the phagocytic pathway of entry into amoebas. In response to gigantism, hosts developed mechanisms to evade these parasites. PMID:27039270

  8. Prevalence of potentially pathogenic free-living amoebae from Acanthamoeba and Naegleria genera in non-hospital, public, internal environments from the city of Santos, Brazil

    Directory of Open Access Journals (Sweden)

    Lais Helena Teixeira

    2009-12-01

    Full Text Available Acanthamoeba and Naegleria species are free-living amoebae (FLA found in a large variety of natural habitats. The prevalence of such amoebae was determined from dust samples taken from public non-hospital internal environments with good standards of cleanliness from two campuses of the same University in the city of Santos (SP, Brazil, and where young and apparently healthy people circulate. The frequency of free-living amoebae in both campuseswas 39% and 17% respectively, with predominance of the genus Acanthamoeba. On the campus with a much larger number of circulating individuals, the observed frequency of free-living amoebae was 2.29 times larger (P< 0.00005. Two trophozoite forms of Naegleria fowleri, are the only species of this genus known to cause primary amoebian meningoencephalitis, a rare and non-opportunistic infection. We assume that the high frequency of these organisms in different internal locations represents some kind of public health risk.

  9. Prevalence of potentially pathogenic free-living amoebae from Acanthamoeba and Naegleria genera in non-hospital, public, internal environments from the city of Santos, Brazil.

    Science.gov (United States)

    Teixeira, Lais Helena; Rocha, Silvana; Pinto, Rosa Maria Ferreiro; Caseiro, Marcos Montani; Costa, Sergio Olavo Pinto da

    2009-12-01

    Acanthamoeba and Naegleria species are free-living amoebae (FLA) found in a large variety of natural habitats. The prevalence of such amoebae was determined from dust samples taken from public non-hospital internal environments with good standards of cleanliness from two campuses of the same University in the city of Santos (SP), Brazil, and where young and apparently healthy people circulate. The frequency of free-living amoebae in both campuses was 39% and 17% respectively, with predominance of the genus Acanthamoeba. On the campus with a much larger number of circulating individuals, the observed frequency of free-living amoebae was 2.29 times larger (P< 0.00005). Two trophozoite forms of Naegleria fowleri, are the only species of this genus known to cause primary amoebian meningoencephalitis, a rare and non-opportunistic infection. We assume that the high frequency of these organisms in different internal locations represents some kind of public health risk.

  10. A year long study of the presence of free living amoeba in Spain.

    Science.gov (United States)

    Magnet, A; Fenoy, S; Galván, A L; Izquierdo, F; Rueda, C; Fernandez Vadillo, C; Del Aguila, C

    2013-12-01

    Free-living amoeba such as Acanthamoeba and Balamuthia mandrillaris can act as opportunistic parasites on a wide range of vertebrates and they are becoming a serious threat to human health due to the resistance of their cysts to harsh environmental conditions, disinfectants, some water treatment practices and their ubiquitous distribution. This work was carried out in order to study the presence of these free-living amoebae (FLA) and their possible seasonality in a continental-Mediterranean climate in different types of water. For this purpose, a total of 223 water samples were collected during one year from four drinking water treatment plants (DWTP), seven wastewater treatment plants (WWTP) and six locations of influence (LI) on four river basins from Spain. Water samples were concentrated using the IDEXX Filta-Max(®) system and analyzed by a triplex real time PCR that detects Acanthamoeba, B. mandrillaris and Naegleria fowleri. Agar plates were also seeded for Acanthamoeba culture. From the three FLA studied, N. fowleri was not detected in any sample while B. mandrillaris was found at the entrance of a DWTP; this being, to our knowledge, the first report of these protozoa in water worldwide. On the other hand, the presence of Acanthamoeba observed was higher, 94.6% of the studied points were positive by real time PCR and 85.2% by culture, resulting in 99.1% positive for Acanthamoeba with both methods. All genetically analyzed Acanthamoeba were genotype T4 but nine different T4/DF3 sequences were observed, three of them being described for the first time, assigning new codes. No seasonal distribution of Acanthamoeba was found. These facts should serve as a warning to contact lens wearers of the risk of a poor hygiene when handling their contact lenses. It should also serve as a signal to physicians to consider FLA as a possible causative agent of nervous system infections as well as Acanthamoeba keratitis due to their high environmental presence shown in this

  11. Check-list of microscopic protosteloid amoebae from the Southwest of Europe

    Directory of Open Access Journals (Sweden)

    Aguilar, María

    2012-12-01

    Full Text Available A biodiversity survey for protosteloid amoebae was carried out in Spain, Portugal and France between 2005 and 2010. Samples were collected from three different microhabitats – aerial litter, ground litter, and bark of living plants – in a total of 97 localities. As result 26 to 28 species out of the 33 species of microscopic protosteloid amoebae described to date were recorded. An annotated list that comprises all available data about these organisms from this part of the world, a key to the species, comments on the morphology of the sporocarps and the trophic stages is presented. Photomicrographs of the fruiting bodies of most species, and distribution maps are also included.

    Se ha realizado un estudio de la biodiversidad de las amebas protos - teloides en España, Portugal y Francia entre 2005 y 2010. Las muestras se recolectaron en tres microhábitats diferentes –hojarasca aérea, hojarasca del suelo y corteza de plantas vivas– en un total de 97 localidades. Como resultado se encontraron entre 26 y 28 especies de las 33 especies de amebas protosteloides microscópicas descritas. Se presenta una lista comentada que contiene todos los datos disponibles sobre estos organismos en esta parte del mundo, una clave de las especies y comentarios sobre la morfología de los esporocarpos y de los estados tróficos. También se incluyen fotomicrografías de los cuerpos fructíferos de la mayoría de las especies y mapas de distribución.

  12. Evolutionary diversity of social amoebae N-glycomes may support interspecific autonomy.

    Science.gov (United States)

    Feasley, Christa L; van der Wel, Hanke; West, Christopher M

    2015-08-01

    Multiple species of cellular slime mold (CSM) amoebae share overlapping subterranean environments near the soil surface. Despite similar life-styles, individual species form independent starvation-induced fruiting bodies whose spores can renew the life cycle. N-glycans associated with the cell surface glycocalyx have been predicted to contribute to interspecific avoidance, resistance to pathogens, and prey preference. N-glycans from five CSM species that diverged 300-600 million years ago and whose genomes have been sequenced were fractionated into neutral and acidic pools and profiled by MALDI-TOF-MS. Glycan structure models were refined using linkage specific antibodies, exoglycosidase digestions, MALDI-MS/MS, and chromatographic studies. Amoebae of the type species Dictyostelium discoideum express modestly trimmed high mannose N-glycans variably modified with core α3-linked Fuc and peripherally decorated with 0-2 residues each of β-GlcNAc, Fuc, methylphosphate and/or sulfate, as reported previously. Comparative analyses of D. purpureum, D. fasciculatum, Polysphondylium pallidum, and Actyostelium subglobosum revealed that each displays a distinctive spectrum of high-mannose species with quantitative variations in the extent of these modifications, and qualitative differences including retention of Glc, mannose methylation, and absence of a peripheral GlcNAc, fucosylation, or sulfation. Starvation-induced development modifies the pattern in all species but, except for universally observed increased mannose-trimming, the N-glycans do not converge to a common profile. Correlations with glycogene repertoires will enable future reverse genetic studies to eliminate N-glycomic differences to test their functions in interspecific relations and pathogen evasion. PMID:25987342

  13. Relevant Genes Linked to Virulence Are Required for Salmonella Typhimurium to Survive Intracellularly in the Social Amoeba Dictyostelium discoideum.

    Science.gov (United States)

    Riquelme, Sebastián; Varas, Macarena; Valenzuela, Camila; Velozo, Paula; Chahin, Nicolás; Aguilera, Paulina; Sabag, Andrea; Labra, Bayron; Álvarez, Sergio A; Chávez, Francisco P; Santiviago, Carlos A

    2016-01-01

    The social amoeba Dictyostelium discoideum has proven to be a useful model for studying relevant aspects of the host-pathogen interaction. In this work, D. discoideum was used as a model to study the ability of Salmonella Typhimurium to survive in amoebae and to evaluate the contribution of selected genes in this process. To do this, we performed infection assays using axenic cultures of D. discoideum co-cultured with wild-type S. Typhimurium and/or defined mutant strains. Our results confirmed that wild-type S. Typhimurium is able to survive intracellularly in D. discoideum. In contrast, mutants ΔaroA and ΔwaaL are defective in intracellular survival in this amoeba. Next, we included in our study a group of mutants in genes directly linked to Salmonella virulence. Of note, mutants ΔinvA, ΔssaD, ΔclpV, and ΔphoPQ also showed an impaired ability to survive intracellularly in D. discoideum. This indicates that S. Typhimurium requires a functional biosynthetic pathway of aromatic compounds, a lipopolysaccharide containing a complete O-antigen, the type III secretion systems (T3SS) encoded in SPI-1 and SPI-2, the type VI secretion system (T6SS) encoded in SPI-6 and PhoP/PhoQ two-component system to survive in D. discoideum. To our knowledge, this is the first report on the requirement of O-antigen and T6SS in the survival of Salmonella within amoebae. In addition, mutants ΔinvA and ΔssaD were internalized in higher numbers than the wild-type strain during competitive infections, suggesting that S. Typhimurium requires the T3SS encoded in SPI-1 and SPI-2 to evade phagocytosis by D. discoideum. Altogether, these results indicate that S. Typhimurium exploits a common set of genes and molecular mechanisms to survive within amoeba and animal host cells. The use of D. discoideum as a model for host-pathogen interactions will allow us to discover the gene repertoire used by Salmonella to survive inside the amoeba and to study the cellular processes that are affected

  14. Holocene environmental changes in southern Kamchatka, Far Eastern Russia, inferred from a pollen and testate amoebae peat succession record

    Science.gov (United States)

    Klimaschewski, A.; Barnekow, L.; Bennett, K. D.; Andreev, A. A.; Andrén, E.; Bobrov, A. A.; Hammarlund, D.

    2015-11-01

    High resolution palaeoenvironmental records in Far-Eastern Russia are rare, and the Kamchatka Peninsula is among the least studied areas of the region. This paper describes a record spanning the last ca. 11,000 yr, obtained from a bog in the southern part of Kamchatka. The radiocarbon dated core was analysed for pollen, testate amoebae, charcoal and loss-on-ignition (LOI). The vegetation during the early Holocene was dominated by grasses (Poaceae), birch (Betula) and heath (Ericaceae p. p.). Around 10,300 cal yr BP there was a substantial change in the vegetation cover to shrub alder (Alnus viridis s.l.) stands with sedges and ferns (Polypodiophyta) as well as herbs such as meadow rue (Thalictrum) in the understory. In the surroundings of Utka peatlands started to form. The variations in the vegetation cover were most probably caused by climatic changes. At the beginning of sediment accumulation, before 10,300 cal yr BP, the composition of the vegetation points to cooler summers and/or decreased annual precipitation. Around 10,300 cal yr BP, changes in vegetation occurred due to rising temperatures and/or changed water regimes. Increased abundancies of dry indicating testate amoebae after 9100 cal yr BP point to intermediate to dry soil conditions. Between 8600 and 7700 cal yr BP tree alder (Alnus incana) was widely spread at the site which probably indicates optimal environmental conditions. The tephra layer at 381-384.5 cm (ca. 8500 cal yr BP) produces a strong impact on the testate amoebae assemblages. At 7700 cal yr BP there was a sudden drop of A. incana in the local vegetation. From this time on, A. incana and also A. viridis decrease continuously whereas Betula gradually increases. The upper part of the sequence (after 6300 cal yr BP) shows higher abundancies of meadowsweet (Filipendula) and sweet gale (Myrica) pollen. After 6300 cal yr BP, changes in testate amoebae demonstrate variable soil moisture conditions at the site. Between 3700 and 1800 cal yr BP

  15. Distribution of Legionella pneumophila bacteria and Naegleria and Hartmannella amoebae in thermal saline baths used in balneotherapy.

    Science.gov (United States)

    Zbikowska, Elżbieta; Walczak, Maciej; Krawiec, Arkadiusz

    2013-01-01

    The present study was aimed at investigating the coexistence and interactions between free living amoebae of Naegleria and Hartmannella genera and pathogenic Legionella pneumophila bacteria in thermal saline baths used in balneotherapy in central Poland. Water samples were collected from November 2010 to May 2011 at intervals longer than 1 month. The microorganisms were detected with the use of a very sensitive fluorescence in situ hybridisation method. In addition, the morphology of the amoebae was studied. Despite relatively high salinity level, ranging from 1.5 to 5.0 %, L. pneumophila were found in all investigated baths, although their number never exceeded 10(6) cells dm(-3). Hartmannella were not detected, while Naegleria fowleri were found in one bath. The observation that N. fowleri and L. pneumophila may coexist in thermal saline baths is the first observation emphasising potential threat from these microorganisms in balneotherapy.

  16. Growth regulation of Legionella Pneumophila in biofilms and amoebae; Wachstumsregulation von Legionella Pneumophila in Biofilmen und Amoeben

    Energy Technology Data Exchange (ETDEWEB)

    Hilbi, H.

    2006-07-01

    This final report for the Swiss Federal Office of Energy (SFOE) presents the results of studies made on the regulation of the growth of Legionella Pneumophila bacteria in biofilms and amoebae. In a first project, the formation of biofilms by Legionella Pneumophila bacteria was analysed in static and dynamic systems using a complex growth medium. Under static and dynamic clinical and environmental conditions, the adherence of the biofilms on polystyrene tissue was studied. This was also examined under dynamic flow conditions. In a second part of the project, the regulation of growth of Legionella Pneumophila in amoebae was examined in that changes were made to the genome of the bacteria. The importance of the work for the de-activation of Legionella Pneumophila bacteria in biofilms is noted in the conclusions of the report.

  17. Development of a high- versus low-pathogenicity model of the free-living amoeba Naegleria fowleri.

    Science.gov (United States)

    Burri, Denise C; Gottstein, Bruno; Zumkehr, Béatrice; Hemphill, Andrew; Schürch, Nadia; Wittwer, Matthias; Müller, Norbert

    2012-10-01

    Species in the genus Naegleria are free-living amoebae of the soil and warm fresh water. Although around 30 species have been recognized, Naegleria fowleri is the only one that causes primary amoebic meningoencephalitis (PAM) in humans. PAM is an acute and fast progressing disease affecting the central nervous system. Most of the patients die within 1-2 weeks of exposure to the infectious water source. The fact that N. fowleri causes such fast progressing and highly lethal infections has opened many questions regarding the relevant pathogenicity factors of the amoeba. In order to investigate the pathogenesis of N. fowleri under defined experimental conditions, we developed a novel high- versus low-pathogenicity model for this pathogen. We showed that the composition of the axenic growth media influenced growth behaviour and morphology, as well as in vitro cytotoxicity and in vivo pathogenicity of N. fowleri. Trophozoites maintained in Nelson's medium were highly pathogenic for mice, demonstrated rapid in vitro proliferation, characteristic expression of surface membrane vesicles and a small cell diameter, and killed target mouse fibroblasts by both contact-dependent and -independent destruction. In contrast, N. fowleri cultured in PYNFH medium exhibited a low pathogenicity, slower growth, increased cell size and contact-dependent target cell destruction. However, cultivation of the amoeba in PYNFH medium supplemented with liver hydrolysate (LH) resulted in trophozoites that were highly pathogenic in mice, and demonstrated an intermediate proliferation rate in vitro, diminished cell diameter and contact-dependent target cell destruction. Thus, in this model, the presence of LH resulted in increased proliferation of trophozoites in vitro and enhanced pathogenicity of N. fowleri in mice. However, neither in vitro cytotoxicity mechanisms nor the presence of membrane vesicles on the surface correlated with the pathologic potential of the amoeba. This indicated that the

  18. Amphizoic amoebae: pathogenic free-living protozoa; review of the literature and review of cases in Thailand.

    Science.gov (United States)

    Siripanth, Chutatip

    2005-05-01

    A large variety of species of free-living amoebae (FLA) caused an indefinite form of these protozoa. Non-fixed form, as indicated by amoeboid movement and possed the bacteria to survive in nature. Two species of pathogenic FLA: Naegleria fowleri and Acanthamoeba spp. were identified as the causative agents of Primary Amoebic Meningoencephalitis (PAM) and Granulomatous Amoebic Encephalitis (GAE) respectively. They were suggested to amphizoic protozoa, capable of living as parasites or as free-living and they were also considered to be distributed worldwide. These amoebae were detected in lakes, rivers and ponds. The first case of meningoencephalitis was observed in 1961 by Fowler Many cases were reported later on and the pathogenicity was tested by nasal inoculation of mice. In fact, quite a number of FLA were isolated but only a few species were pathogenic to humans. The three typical features which allow recognition of Naegleria spp. flagellate stage, round cyst and promitotic trophozoite. This promitosis distinguishes the Naegleria genus from Acanthamoeba spp. The disease caused by PAM usually occurs with acute onset, whereas chronic for GAE. The GAE cases mentioned are mostly in debilitated patients, chronic alcoholics or patients under treatment with immunosuppressive methods. About 6 cases of PAM were reported in Thailand during 1982-1997. Four cases of GAE were reported in 1994 and two isolated cases ofAcanthamoebafrom keratitis patients were reported in 2000. Finally one case of PAM and one case of GAE were reported in 2001. The surveys of FLA were set up to study the distribution of these pathogenic amoebae and determine the prevalence of amoebae in aquatic habitats of human environments. About 40% were identified as Acanthamoeba spp., 30% were Naegleria spp., 20% were Hartmanella and 10% were Vahlkampfia. Only 10% of Naegleria spp. belonged to Naegleria fowleri.

  19. A Novel Glycolipid Biosurfactant Confers Grazing Resistance upon Pantoea ananatis BRT175 against the Social Amoeba Dictyostelium discoideum.

    Science.gov (United States)

    Smith, Derek D N; Nickzad, Arvin; Déziel, Eric; Stavrinides, John

    2016-01-01

    Pantoea is a versatile genus of bacteria with both plant- and animal-pathogenic strains, some of which have been suggested to cause human infections. There is, however, limited knowledge on the potential determinants used for host association and pathogenesis in animal systems. In this study, we used the model host Dictyostelium discoideum to show that isolates of Pantoea ananatis exhibit differential grazing susceptibility, with some being resistant to grazing by the amoebae. We carried out a high-throughput genetic screen of one grazing-resistant isolate, P. ananatis BRT175, using the D. discoideum pathosystem to identify genes responsible for the resistance phenotype. Among the 26 candidate genes involved in grazing resistance, we identified rhlA and rhlB, which we show are involved in the biosynthesis of a biosurfactant that enables swarming motility in P. ananatis BRT175. Using liquid chromatography-mass spectrometry (LC-MS), the biosurfactant was shown to be a glycolipid with monohexose-C10-C10 as the primary congener. We show that this novel glycolipid biosurfactant is cytotoxic to the amoebae and is capable of compromising cellular integrity, leading to cell lysis. The production of this biosurfactant may be important for bacterial survival in the environment and could contribute to the establishment of opportunistic infections. IMPORTANCE The genetic factors used for host interaction by the opportunistic human pathogen Pantoea ananatis are largely unknown. We identified two genes that are important for the production of a biosurfactant that confers grazing resistance against the social amoeba Dictyostelium discoideum. We show that the biosurfactant, which exhibits cytotoxicity toward the amoebae, is a glycolipid that incorporates a hexose rather than rhamnose. The production of this biosurfactant may confer a competitive advantage in the environment and could potentially contribute to the establishment of opportunistic infections. PMID:27303689

  20. Pathogenic free-living amoebae in a closed-loop power plant; risk assessment and risk management

    Energy Technology Data Exchange (ETDEWEB)

    Cabanes, P. [Electricite de France (EDF), 75 - Paris (France). Service Etudes Medicales; Pringuez, E.; Siclet, F.; Khalanski, M. [Electricite de France (EDF), 75 - Paris (France). Direction des Etudes et Recherches; Bard, D. [CEA/Fontenay-aux-Roses, Inst. de Protection et de Surete Nucleaire (IPSN), 92 (France); Pernin, P. [Faculte de Pharmacie de Lyon, 69 (France)

    1998-07-01

    Since 1980, the water used for cooling in French power plants has been tested for pathogenic amoebae, especially Naegleria fowleri, the causative agent of Primary Amoebic Meningoencephalitis (PAM), a rapid fatal disease of the central nervous system. The replacement of brass condensers by stainless steel condensers resulted in increased Naegleria fowleri development, to a density of as much as 3000 l{sup -1} in the Dampierre power plant cooling water. Downstream from Dampierre, the maximum detected density of this amoeba during the summer of 1995 was 80 l{sup -1}, at low river flow. The replacement of a second condenser in 1996 at the same power plant was expected to double the amoebae concentration in the river. The hypothetical PAM risk for swimmers was then predicted to be 10{sup -4} per swim. To reduce the risk continuous chlorination of the closed-loop cooling system was implemented at a free residual chlorine level in the range of 0.3-0.5 mg.l{sup -1}. Naegleria fowleri concentrations decreased immediately and thereafter remained under 4 l{sup -1}. Total residual chlorine and chlorinated organic compounds were also monitored in the evaluation of the environmental impact of this preventive action. (authors)

  1. Detection and Molecular Characterization of Potentially Pathogenic Free-living Amoebae from Water Sources in Kish Island, Southern Iran.

    Science.gov (United States)

    Niyyati, Maryam; Lasgerdi, Zohreh; Lorenzo-Morales, Jacob

    2015-01-01

    Amoebic keratitis, a sight-threatening corneal infection, mainly occurs in contact lens wearers who wash their eyes with tap water. The present research was conducted to identify the occurrence of potentially pathogenic free-living amoebae (FLA) in tap water sources on Kish Island, a tourist region in Iran. Amoebae were detected using a culture-enriched method and by polymerase chain reaction (PCR)/sequencing of the diagnostic fragment 3 region of the 18S rRNA gene of Acanthamoeba. In the case of other free-living amoebae species, PCR/sequencing analysis of the 18S rDNA was conducted. Results of this study showed the presence of Acanthamoeba belonging to T3, T4, T5, and T11 genotypes in tap water sources. Additionally, Vermamoebae vermiformis was detected in three water samples. This is the first report of the Acanthamoeba genotypes T3, T4, T5, and T11 and V. vermiformis species in tap water sources in a tourist region in Iran.

  2. POTENTIALLY PATHOGENIC FREE-LIVING AMOEBAE IN SOME FLOOD-AFFECTED AREAS DURING 2011 CHIANG MAI FLOOD

    Directory of Open Access Journals (Sweden)

    Anchalee Wannasan

    2013-12-01

    Full Text Available SUMMARY The survey was carried out to investigate the presence of potentially pathogenic free-living amoebae (FLA during flood in Chiang Mai, Thailand in 2011. From different crisis flood areas, seven water samples were collected and tested for the presence of amoebae using culture and molecular methods. By monoxenic culture, FLA were detected from all samples at 37 °C incubation. The FLA growing at 37 °C were morphologically identified as Acanthamoeba spp., Naegleria spp. and some unidentified amoebae. Only three samples (42.8%, defined as thermotolerant FLA, continued to grow at 42 °C. By molecular methods, two non-thermotolerant FlA were shown to have 99% identity to Acanthamoeba sp. and 98% identity to Hartmannella vermiformis while the two thermotolerant FLA were identified as Echinamoeba exundans (100% identity and Hartmannella sp. (99% identity. This first report of the occurrence of FLA in water during the flood disaster will provide information to the public to be aware of potentially pathogenic FLA.

  3. Potentially pathogenic free-living amoebae in some flood-affected areas during 2011 Chiang Mai flood.

    Science.gov (United States)

    Wannasan, Anchalee; Uparanukraw, Pichart; Songsangchun, Apichart; Morakote, Nimit

    2013-01-01

    The survey was carried out to investigate the presence of potentially pathogenic free-living amoebae (FLA) during flood in Chiang Mai, Thailand in 2011. From different crisis flood areas, seven water samples were collected and tested for the presence of amoebae using culture and molecular methods. By monoxenic culture, FLA were detected from all samples at 37 °C incubation. The FLA growing at 37 °C were morphologically identified as Acanthamoeba spp., Naegleria spp. and some unidentified amoebae. Only three samples (42.8%), defined as thermotolerant FLA, continued to grow at 42 °C. By molecular methods, two non-thermotolerant FlA were shown to have 99% identity to Acanthamoeba sp. and 98% identity to Hartmannella vermiformis while the two thermotolerant FLA were identified as Echinamoeba exundans (100% identity) and Hartmannella sp. (99% identity). This first report of the occurrence of FLA in water during the flood disaster will provide information to the public to be aware of potentially pathogenic FLA.

  4. Surveillance and evaluation of the infection risk of free-living amoebae and Legionella in different aquatic environments.

    Science.gov (United States)

    Ji, Wen-Tsai; Hsu, Bing-Mu; Chang, Tien-Yu; Hsu, Tsui-Kang; Kao, Po-Min; Huang, Kuan-Hao; Tsai, Shiou-Feng; Huang, Yu-Li; Fan, Cheng-Wei

    2014-11-15

    Free-living amoebae (FLA) are ubiquitous in various aquatic environments. Several amoebae species are pathogenic and host other pathogens such as Legionella, but the presence of FLA and its parasites as well as the related infection risk are not well known. In this study, the presence of pathogenic FLA and Legionella in various water bodies was investigated. Water samples were collected from a river, intake areas of drinking water treatment plants, and recreational hot spring complexes in central and southern Taiwan. A total of 140 water samples were tested for the presence of Acanthamoeba spp., Naegleria spp., Vermamoeba vermiformis, and Legionella. In addition, phylogenetic characteristics and water quality parameters were also assessed. The pathogenic genotypes of FLA included Acanthamoeba T4 and Naegleria australiensis, and both were abundant in the hot spring water. In contrast, Legionella pneumophila was detected in different aquatic environments. Among the FLA assessed, V. vermiformis was most likely to coexist with Legionella spp. The total bacteria level was associated with the presence of FLA and Legionella especially in hot spring water. Taken together, FLA contamination in recreational hot springs and drinking water source warrants more attention on potential legionellosis and amoebae infections.

  5. The Phanerozoic diversification of silica-cycling testate amoebae and its possible links to changes in terrestrial ecosystems.

    Science.gov (United States)

    Lahr, Daniel J G; Bosak, Tanja; Lara, Enrique; Mitchell, Edward A D

    2015-01-01

    The terrestrial cycling of Si is thought to have a large influence on the terrestrial and marine primary production, as well as the coupled biogeochemical cycles of Si and C. Biomineralization of silica is widespread among terrestrial eukaryotes such as plants, soil diatoms, freshwater sponges, silicifying flagellates and testate amoebae. Two major groups of testate (shelled) amoebae, arcellinids and euglyphids, produce their own silica particles to construct shells. The two are unrelated phylogenetically and acquired biomineralizing capabilities independently. Hyalosphenids, a group within arcellinids, are predators of euglyphids. We demonstrate that hyalosphenids can construct shells using silica scales mineralized by the euglyphids. Parsimony analyses of the current hyalosphenid phylogeny indicate that the ability to "steal" euglyphid scales is most likely ancestral in hyalosphenids, implying that euglyphids should be older than hyalosphenids. However, exactly when euglyphids arose is uncertain. Current fossil record contains unambiguous euglyphid fossils that are as old as 50 million years, but older fossils are scarce and difficult to interpret. Poor taxon sampling of euglyphids has also prevented the development of molecular clocks. Here, we present a novel molecular clock reconstruction for arcellinids and consider the uncertainties due to various previously used calibration points. The new molecular clock puts the origin of hyalosphenids in the early Carboniferous (∼370 mya). Notably, this estimate coincides with the widespread colonization of land by Si-accumulating plants, suggesting possible links between the evolution of Arcellinid testate amoebae and the expansion of terrestrial habitats rich in organic matter and bioavailable Si.

  6. The Phanerozoic diversification of silica-cycling testate amoebae and its possible links to changes in terrestrial ecosystems.

    Science.gov (United States)

    Lahr, Daniel J G; Bosak, Tanja; Lara, Enrique; Mitchell, Edward A D

    2015-01-01

    The terrestrial cycling of Si is thought to have a large influence on the terrestrial and marine primary production, as well as the coupled biogeochemical cycles of Si and C. Biomineralization of silica is widespread among terrestrial eukaryotes such as plants, soil diatoms, freshwater sponges, silicifying flagellates and testate amoebae. Two major groups of testate (shelled) amoebae, arcellinids and euglyphids, produce their own silica particles to construct shells. The two are unrelated phylogenetically and acquired biomineralizing capabilities independently. Hyalosphenids, a group within arcellinids, are predators of euglyphids. We demonstrate that hyalosphenids can construct shells using silica scales mineralized by the euglyphids. Parsimony analyses of the current hyalosphenid phylogeny indicate that the ability to "steal" euglyphid scales is most likely ancestral in hyalosphenids, implying that euglyphids should be older than hyalosphenids. However, exactly when euglyphids arose is uncertain. Current fossil record contains unambiguous euglyphid fossils that are as old as 50 million years, but older fossils are scarce and difficult to interpret. Poor taxon sampling of euglyphids has also prevented the development of molecular clocks. Here, we present a novel molecular clock reconstruction for arcellinids and consider the uncertainties due to various previously used calibration points. The new molecular clock puts the origin of hyalosphenids in the early Carboniferous (∼370 mya). Notably, this estimate coincides with the widespread colonization of land by Si-accumulating plants, suggesting possible links between the evolution of Arcellinid testate amoebae and the expansion of terrestrial habitats rich in organic matter and bioavailable Si. PMID:26734499

  7. Detection of free living amoebae, Acanthamoeba and Naegleria, in swimming pools, Malaysia.

    Science.gov (United States)

    Init, I; Lau, Y L; Arin Fadzlun, A; Foead, A I; Neilson, R S; Nissapatorn, V

    2010-12-01

    This study reports the detection of Acanthamoeba and Naegleria species in 14 swimming pools around Petaling Jaya and Kuala Lumpur, Malaysia. Sampling was carried out at 4 sites (the platforms (P), wall (W), 1 meter from the wall (1) and middle (2)) of each swimming pool. These free living amoebae (FLA) were detected under light and inverted microscopes after being cultured on the surface of non-nutrient agar lawned with Escherichia coli. Acanthamoeba species were detected in higher number of culture plates from all sampling sites of all the swimming pools. While Naegleria, were detected in fewer culture plates at 3 sampling sites (absent at site P) of 8 swimming pools. This suggested that the thick double-walled cysts of Acanthamoeba were more resistant, thus remaining viable in the dry-hot areas of the platforms and in chlorinated water of the swimming pools whereas Naegleria cysts, that are fragile and susceptible to desiccation, preferred watery or moist areas for growth and proliferation. The prevalence of both FLA was highest at site W (76.2%), followed by site 1 (64.7%), lowest at site 2 (19.4%), and could be detected at all 3 sampling levels (top, middle and bottom) of these 3 sites. The surface of site W might act as a bio-film that accumulated all kinds of microbes providing sufficient requirement for the FLA to develop and undergo many rounds of life cycles as well as moving from top to bottom in order to graze food. Other factors such as human activities, the circulating system which was fixed at all swimming pools, blowing wind which might carry the cysts from surroundings and the swimming flagellate stage of Naegleria could also contribute to the distribution of the FLA at these sampling sites. Both FLA showed highest growth (80.4%) at room temperature (25-28 ºC) and lesser (70.0%) at 37 ºC which might be due to the overgrowth of other microbes (E. coli, fungi, algae, etc). While at 44 ºC, only Acanthamoeba species could survive thus showing that

  8. Sentinel cells, symbiotic bacteria and toxin resistance in the social amoeba Dictyostelium discoideum.

    Science.gov (United States)

    Brock, Debra A; Callison, W Éamon; Strassmann, Joan E; Queller, David C

    2016-04-27

    The social amoeba Dictyostelium discoideum is unusual among eukaryotes in having both unicellular and multicellular stages. In the multicellular stage, some cells, called sentinels, ingest toxins, waste and bacteria. The sentinel cells ultimately fall away from the back of the migrating slug, thus removing these substances from the slug. However, some D. discoideum clones (called farmers) carry commensal bacteria through the multicellular stage, while others (called non-farmers) do not. Farmers profit from their beneficial bacteria. To prevent the loss of these bacteria, we hypothesize that sentinel cell numbers may be reduced in farmers, and thus farmers may have a diminished capacity to respond to pathogenic bacteria or toxins. In support, we found that farmers have fewer sentinel cells compared with non-farmers. However, farmers produced no fewer viable spores when challenged with a toxin. These results are consistent with the beneficial bacteria Burkholderia providing protection against toxins. The farmers did not vary in spore production with and without a toxin challenge the way the non-farmers did, which suggests the costs of Burkholderia may be fixed while sentinel cells may be inducible. Therefore, the costs for non-farmers are only paid in the presence of the toxin. When the farmers were cured of their symbiotic bacteria with antibiotics, they behaved just like non-farmers in response to a toxin challenge. Thus, the advantages farmers gain from carrying bacteria include not just food and protection against competitors, but also protection against toxins.

  9. A decade of improvements in Mimiviridae and Marseilleviridae isolation from amoeba.

    Science.gov (United States)

    Pagnier, Isabelle; Reteno, Dorine-Gaelle Ikanga; Saadi, Hanene; Boughalmi, Mondher; Gaia, Morgan; Slimani, Meriem; Ngounga, Tatsiana; Bekliz, Meriem; Colson, Philippe; Raoult, Didier; La Scola, Bernard

    2013-01-01

    Since the isolation of the first giant virus, the Mimivirus, by T.J. Rowbotham in a cooling tower in Bradford, UK, and after its characterisation by our group in 2003, we have continued to develop novel strategies to isolate additional strains. By first focusing on cooling towers using our original time-consuming procedure, we were able to isolate a new lineage of giant virus called Marseillevirus and a new Mimivirus strain called Mamavirus. In the following years, we have accumulated the world's largest unique collection of giant viruses by improving the use of antibiotic combinations to avoid bacterial contamination of amoeba, developing strategies of preliminary screening of samples by molecular methods, and using a high-throughput isolation method developed by our group. Based on the inoculation of nearly 7,000 samples, our collection currently contains 43 strains of Mimiviridae (14 in lineage A, 6 in lineage B, and 23 in lineage C) and 17 strains of Marseilleviridae isolated from various environments, including 3 of human origin. This study details the procedures used to build this collection and paves the way for the high-throughput isolation of new isolates to improve the record of giant virus distribution in the environment and the determination of their pangenome.

  10. Isolation and Identification of Free-Living Amoebae from Tap Water in Sivas, Turkey

    Directory of Open Access Journals (Sweden)

    Kübra Açıkalın Coşkun

    2013-01-01

    Full Text Available The present work focuses on a local survey of free-living amoebae (FLA that cause opportunistic and nonopportunistic infections in humans. Determining the prevalence of FLA in water sources can shine a light on the need to prevent FLA related illnesses. A total of 150 samples of tap water were collected from six districts of Sivas province. The samples were filtered and seeded on nonnutrient agar containing Escherichia coli spread. Thirty-three (22% out of 150 samples were found to be positive for FLA. The FLA were identified by morphology and by PCR using 18S rDNA gene. The morphological analysis and partial sequencing of the 18S rDNA gene revealed the presence of three different species, Acanthamoeba castellanii, Acanthamoeba polyphaga, and Hartmannella vermiformis. Naegleria fowleri, Balamuthia mandrillaris, or Sappinia sp. was not isolated during the study. All A. castellanii and A. polyphaga sequence types were found to be genotype T4 that contains most of the pathogenic Acanthamoeba strains. The results indicated the occurrence and distribution of FLA species in tap water in these localities of Sivas, Turkey. Furthermore, the presence of temperature tolerant Acanthamoeba genotype T4 in tap water in the region must be taken into account for health risks.

  11. Isolation and Identification of Free-Living Amoebae from Tap Water in Sivas, Turkey

    Science.gov (United States)

    Coşkun, Kübra Açıkalın; Özçelik, Semra; Elaldı, Nazif; Tutar, Yusuf

    2013-01-01

    The present work focuses on a local survey of free-living amoebae (FLA) that cause opportunistic and nonopportunistic infections in humans. Determining the prevalence of FLA in water sources can shine a light on the need to prevent FLA related illnesses. A total of 150 samples of tap water were collected from six districts of Sivas province. The samples were filtered and seeded on nonnutrient agar containing Escherichia coli spread. Thirty-three (22%) out of 150 samples were found to be positive for FLA. The FLA were identified by morphology and by PCR using 18S rDNA gene. The morphological analysis and partial sequencing of the 18S rDNA gene revealed the presence of three different species, Acanthamoeba castellanii, Acanthamoeba polyphaga, and Hartmannella vermiformis. Naegleria fowleri, Balamuthia mandrillaris, or Sappinia sp. was not isolated during the study. All A. castellanii and A. polyphaga sequence types were found to be genotype T4 that contains most of the pathogenic Acanthamoeba strains. The results indicated the occurrence and distribution of FLA species in tap water in these localities of Sivas, Turkey. Furthermore, the presence of temperature tolerant Acanthamoeba genotype T4 in tap water in the region must be taken into account for health risks. PMID:23971043

  12. Low-molecular-mass thiol compounds from a free-living highly pathogenic amoeba, Naegleria fowleri.

    Science.gov (United States)

    Ondarza, Raúl N; Iturbe, Angélica; Hernández, Eva; Hurtado, Gerardo

    2003-04-01

    Acid extracts labelled with the fluorescent reagent monobromobimane and separated by HPLC have enabled the detection of low-molecular-mass thiol compounds in Naegleria fowleri for the first time. The amounts detected are expressed in nmol/1 x 10(6) trophozoites cultivated at various stages of growth in the appropriate culture medium. N. fowleri is a highly pathogenic free-living amoeba, in which we found important thiol compounds, some of them in their reduced and oxidized forms. Unlike cysteine and glutathione, a number of these are not represented in normal human lymphocytes. Some of these thiol compounds from Naegleria must have their respective disulphide reductases, although the presence of thiol-disulphide exchange reactions must be considered. Ovothiol A, with antioxidant properties, is an example of a compound that is kept reduced by trypanothione in trypanosomatids, although no disulphide reductase for ovothiol A has yet been discovered. In our case we were unable to detect this biothiol in Naegleria. The presence of thiol compounds that seem to be particular to this pathogen and which are not present in human lymphocytes opens the possibility of searching for disulphide-reducing enzymes that can serve as drug targets.

  13. Ophthalmology hospital wards contamination to pathogenic free living Amoebae in Iran.

    Science.gov (United States)

    Lasjerdi, Zohreh; Niyyati, Maryam; Lorenzo-Morales, Jacob; Haghighi, Ali; Taghipour, Niloofar

    2015-09-01

    The present study was conducted to determine the occurrence of potentially pathogenic free-living amoeba in ophthalmology wards in reference hospitals in Iran. Since an increasing number of Acanthamoeba Keratitis cases after eye surgery and eye trauma have been recently observed in this country, it could be possible that the disinfection procedures undertaken in the clinical setting may not have a good hygiene and disinfection procedures, hence the aim of this study. Therefore, 42 dust and biofilm samples were collected from different areas of ophthalmology wards and checked for the presence of FLA using morphological criteria, PCR based analysis and DNA sequencing. Of the 42 samples from dust and biofilm sources, 18(42.86%) isolates were found to contain FLA and 12(92.3%) isolates belonged to Acanthamoeba T4 genotype. Isolation of the pathogenic genotype T4 from medical instruments, including slit lamp in corneal wards, may be a threat for patients undergoing eye surgery in these wards. Other FLA isolated in this study included Acanthamoeba genotype T5, Vahlkampfia sp, Naegleria australiensis, Vermamoeba vermiformis and Echinamoeba exudans. To our knowledge, this is the first report of the presence of potentially pathogenic FLA in ophthalmology wards in Iran. Improved disinfection methods and monitoring of hospitals ward are thus necessary in this area in order to minimize the risk of infection in patients.

  14. Lateral gene exchanges shape the genomes of amoeba-resisting microorganisms

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    Claire eBertelli

    2012-08-01

    Full Text Available Based on Darwin’s concept of the tree of life, vertical inheritance was thought to be dominant, and mutations, deletions and duplication were streaming the genomes of living organisms. In the current genomic era, increasing data indicated that both vertical and lateral gene inheritance interact in space and time to trigger genome evolution, particularly among microorganisms sharing a given ecological niche. As a paradigm to their diversity and their survival in a variety of cell types, intracellular microorganisms, and notably intracellular bacteria, were considered as less prone to lateral genetic exchanges. Such specialized microorganisms generally have a smaller gene repertoire because they do rely on their host’s factors for some basic regulatory and metabolic functions. Here we review events of lateral gene transfer (LGT that illustrate the genetic exchanges among intra-amoebal microorganisms or between the microorganism and its amoebal host. We tentatively investigate the functions of laterally transferred genes in the light of the interaction with their host as they should confer a selective advantage and success to the amoeba-resisting microorganisms.

  15. Free-living amoebae (FLA) co-occurring with legionellae in industrial waters.

    Science.gov (United States)

    Scheikl, Ute; Sommer, Regina; Kirschner, Alexander; Rameder, Alexandra; Schrammel, Barbara; Zweimüller, Irene; Wesner, Wolfgang; Hinker, Manfred; Walochnik, Julia

    2014-08-01

    Legionella pneumophila is known as the causative agent of Legionnaires' disease and free-living amoebae (FLA) can serve as vehicles for legionellae. The aim of this study was to screen industrial waters for the occurrence of FLA and their co-occurrence with legionellae. A total of 201 water samples, including 129 cooling waters and 72 process waters, and 30 cooling lubricants were included in the study. Treated waters were screened periodically, pre and post treatment. Altogether, 72.6% of the water samples were positive for FLA, acanthamoebae being most prevalent (in 23.9% of the samples) followed by Vermamoeba vermiformis (19.4%). Only one cooling lubricant was positive (Acanthamoeba genotype T4). Legionella spp. were detected in 34.8% of the water samples and in 15% in high concentrations (>1000 CFU/100 ml). Altogether, 81.4% of the Legionella-positive samples were positive for FLA by standard methods. By applying a highly sensitive nested PCR to a representative set of random samples it was revealed that Legionella spp. always co-occurred with Acanthamoeba spp. Although the addition of disinfectants did influence amoebal density and diversity, treated waters showed no difference concerning FLA in the interphases of disinfection. It appears that FLA can re-colonize treated waters within a short period of time.

  16. Isolation and identification of free-living amoebae from tap water in Sivas, Turkey.

    Science.gov (United States)

    Coşkun, Kübra Açıkalın; Ozçelik, Semra; Tutar, Lütfi; Elaldı, Nazif; Tutar, Yusuf

    2013-01-01

    The present work focuses on a local survey of free-living amoebae (FLA) that cause opportunistic and nonopportunistic infections in humans. Determining the prevalence of FLA in water sources can shine a light on the need to prevent FLA related illnesses. A total of 150 samples of tap water were collected from six districts of Sivas province. The samples were filtered and seeded on nonnutrient agar containing Escherichia coli spread. Thirty-three (22%) out of 150 samples were found to be positive for FLA. The FLA were identified by morphology and by PCR using 18S rDNA gene. The morphological analysis and partial sequencing of the 18S rDNA gene revealed the presence of three different species, Acanthamoeba castellanii, Acanthamoeba polyphaga, and Hartmannella vermiformis. Naegleria fowleri, Balamuthia mandrillaris, or Sappinia sp. was not isolated during the study. All A. castellanii and A. polyphaga sequence types were found to be genotype T4 that contains most of the pathogenic Acanthamoeba strains. The results indicated the occurrence and distribution of FLA species in tap water in these localities of Sivas, Turkey. Furthermore, the presence of temperature tolerant Acanthamoeba genotype T4 in tap water in the region must be taken into account for health risks.

  17. Characteristics of motive force derived from trajectory analysis of Amoeba proteus.

    Science.gov (United States)

    Masaki, Noritaka; Miyoshi, Hiromi; Tsuchiya, Yoshimi

    2007-01-01

    We used a monochromatic charge-coupled-device camera to observe the migration behavior of Amoeba proteus every 5 s over a time course of 10000 s in order to investigate the characteristics of its centroid movement (cell velocity) over the long term. Fourier transformation of the time series of the cell velocity revealed that its power spectrum exhibits a Lorentz type profile with a relaxation time of a few hundred seconds. Moreover, some sharp peaks were found in the power spectrum, where the ratios of any two frequencies corresponding to the peaks were expressed as simple rational numbers. Analysis of the trajectory using a Langevin equation showed that the power spectrum reflects characteristics of the cell's motive force. These results suggest that some phenomena relating to the cell's motility, such as protoplasmic streaming and the sol-gel transformation of actin filaments, which seem to be independent phenomena and have different relaxation times, interact with each other and cooperatively participate in the generation process of the motive force. PMID:17351734

  18. Evolution of the actin gene family in testate lobose amoebae (Arcellinida) is characterized by two distinct clades of paralogs and recent independent expansions.

    Science.gov (United States)

    Lahr, Daniel J G; Nguyen, Truc B; Barbero, Erika; Katz, Laura A

    2011-01-01

    The evolution of actin gene families is characterized by independent expansions and contractions across the eukaryotic tree of life. Here, we assess diversity of actin gene sequences within three lineages of the genus Arcella, a free-living testate (shelled) amoeba in the Arcellinida. We established four clonal lines of two morphospecies, Arcella hemisphaerica and A. vulgaris, and assessed their phylogenetic relationship within the "Amoebozoa" using small subunit ribosomal DNA (SSU-rDNA) genealogy. We determined that the two lines of A. hemisphaerica are identical in SSU-rDNA, while the two A. vulgaris are independent genetic lineages. Furthermore, we characterized multiple actin gene copies from all lineages. Analyses of the resulting sequences reveal numerous diverse actin genes, which differ mostly by synonymous substitutions. We estimate that the actin gene family contains 40-50 paralogous members in each lineage. None of the three independent lineages share the same paralog with another, and divergence between actins reaches 29% in contrast to just 2% in SSU-rDNA. Analyses of effective number of codons (ENC), compositional bias, recombination signatures, and genetic diversity in the context of a gene tree indicate that there are two groups of actins evolving with distinct patterns of molecular evolution. Within these groups, there have been multiple independent expansions of actin genes within each lineage. Together, these data suggest that the two groups are located in different regions of the Arcella genome. Furthermore, we compare the Arcella actin gene family with the relatively well-described gene family in the slime mold Dictyostelium discoideum and other members of the Amoebozoa clade. Overall patterns of molecular evolution are similar in Arcella and Dictyostelium. However, the separation of genes in two distinct groups coupled with recent expansion is characteristic of Arcella and might reflect an unusual pattern of gene family evolution in the lobose

  19. Holarctic phylogeography of the testate amoeba Hyalosphenia papilio (Amoebozoa: Arcellinida) reveals extensive genetic diversity explained more by environment than dispersal limitation.

    Science.gov (United States)

    Heger, Thierry J; Mitchell, Edward A D; Leander, Brian S

    2013-10-01

    Although free-living protists play essential roles in aquatic and soil ecology, little is known about their diversity and phylogeography, especially in terrestrial ecosystems. We used mitochondrial cytochrome c oxidase subunit 1 (COI) gene sequences to investigate the genetic diversity and phylogeography of the testate amoeba morphospecies Hyalosphenia papilio in 42 Sphagnum (moss)-dominated peatlands in North America, Europe and Asia. Based on ≥1% sequence divergence threshold, our results from single-cell PCRs of 301 individuals revealed 12 different genetic lineages and both the general mixed Yule-coalescent (GMYC) model and the automatic barcode gap discovery (ABGD) methods largely support the hypothesis that these 12 H. papilio lineages correspond to evolutionary independent units (i.e. cryptic species). Our data also showed a high degree of genetic heterogeneity within different geographical regions. Furthermore, we used variation partitioning based on partial redundancy analyses (pRDA) to evaluate the contributions of climate and dispersal limitations on the distribution patterns of the different genetic lineages. The largest fraction of the variation in genetic lineage distribution was attributed to purely climatic factors (21%), followed by the joint effect of spatial and bioclimatic factors (13%), and a purely spatial effect (3%). Therefore, these data suggest that the distribution patterns of H. papilio genetic lineages in the Northern Hemisphere are more influenced by climatic conditions than by dispersal limitations.

  20. Article for the "Free-living amoebae special issue": Isolation and characterisation of various amoebophagous fungi and evaluation of their prey spectrum.

    Science.gov (United States)

    Michel, Rolf; Walochnik, Julia; Scheid, Patrick

    2014-11-01

    This article gives an overview on the isolation and characterisation of endoparasitic fungi invading free-living amoebae (FLA), including the ones forming thalli inside their hosts such as Cochlonema euryblastum and also the predatory fungi which capture amoebae by adhesive hyphae. Acaulopage spp. and Stylopage spp. trap, intrude, and exploit amoebal trophozoites. Previous phylogenetic studies proved Cochlonema to be a member of the Zoopagales. The genetic investigation of Acaulopage tetraceros demonstrated its close relationship to Cochlonema. Co-cultivation of A. tetraceros with a number of FLA revealed a great prey spectrum of this amoebophageous fungus. In addition it was shown that solitary amoebal stages of slime moulds such as Dictyostelium sp. and Physarum sp. are also suited as welcome prey amoebae.

  1. A Novel Lineage of 'Naked Filose Amoebae'; Kraken carinae gen. nov. sp. nov. (Cercozoa) with a Remarkable Locomotion by Disassembly of its Cell Body.

    Science.gov (United States)

    Dumack, Kenneth; Schuster, Julia; Bass, David; Bonkowski, Michael

    2016-06-01

    The term 'filose amoebae' describes a highly polyphyletic assemblage of protists whose phylogenetic placement can be unpredictable based on gross morphology alone. We isolated six filose amoebae from soils of two European countries and describe a new genus and species of naked filose amoebae, Kraken carinae gen. nov. sp. nov. We provide a morphological description based on light microscopy and small subunit rRNA gene sequences (SSU rDNA). In culture, Kraken carinae strains were very slow-moving and preyed on bacteria using a network of filopodia. Phylogenetic analyses of SSU sequences reveal that Kraken are core (filosan) Cercozoa, branching weakly at the base of the cercomonad radiation, most closely related to Paracercomonas, Metabolomonas, and Brevimastigomonas. Some Kraken sequences are >99% similar to an environmental sequence obtained from a freshwater lake in Antarctica, indicating that Kraken is not exclusively soil dwelling, but also inhabits freshwater habitats. PMID:27236418

  2. Free-living amoebae (FLA: detection, morphological and molecular identification of Acanthamoeba genus in the hydraulic system of an haemodialysis unit in Tunisia

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    Dendana F.

    2008-06-01

    Full Text Available The free-living amoebae (FLA are ubiquitous and opportunistic protozoa. They can induce human and animal diseases. The aim of our study was to detect the FLA and Acanthamoeba genus in the hydraulic system of an hemodialysis unit. It was a prospective study of 46 water samples. The first collect (23 was before cleaning and after the haemodialysis sessions and the second (23 after cleaning and before the hemodialysis sessions. Results: the morphological study enabled us to detect morphotypic diversity. The predominant morphotypes were the acanthopodial forms (29%. At the entrance of hemodialysis unit there were acanthopodial (44% and monotactic (25% forms; at the outlet, acanthopodial and fan-shaped forms (25% each. In addition, Acanthamoeba genus was present in 39% (1st collect and 18% (2nd collect. The amplification of the FLA 18S rDNA gene was negative in only one sample localized in the last stage of water treatment unit (WTU. The amplification of the 18S rDNA (ASA.A1 Acanthamoeba gene was positive in15 samples. Conclusions: we noted that, in the hemodialysis unit, the purification techniques used in the WTU were effective, but there is a problem of water stagnation in the drain, which constitutes an appropriate condition for the biofilms formation. It is then necessary to use a filter with a low porosity (0.2 μm at the entrance of the hemodialysis unit and if possible to change the drain

  3. Morphological and molecular identification of free living amoeba isolated from hospital water in Tunisia.

    Science.gov (United States)

    Trabelsi, Houaida; Dendana, F; Neji, S; Sellami, H; Cheikhrouhou, F; Makni, F; Ayadi, A

    2016-01-01

    Free-living amoebae (FLA) are opportunistic and ubiquitous protozoa that are widely found in various environmental sources. They are known to cause serious human infections. The aim of our study was to detect FLA and Acanthamoeba spp. in hospital water circuits. Eighty-four water samples were collected over a period of 4 months (September-December 2011) from different wards of the Sfax University Hospital (surgical services, intensive care unit, operating theater, and water storage tanks). FLA were detected in 53.5 % of samples as follows: surgical services (80 %), operating theater and surgical intensive care unit (13.3 %), medical intensive care unit (0 %), water storage tanks (6.6 %). The predominant morphotype was the acanthopodial (89 %). The others morphotypes were as follows: monopodial (40 %), dactylopodial (22 %), rugosa (62 %), eruptive (24 %), fan shaped (18 %), and polypodial (18 %). Acanthamoeba was found in 40 samples (47.6 %). 64.2 % of isolates were identified as Acanthamoeba spp. by PCR, using primers to amplify a region of 18S rDNA which showed variation in the product length. Sequence analysis of five PCR products identified Acanthamoeba sp. These isolates belong to T4, T10, and T11 genotypes, and to our knowledge this is the first report of the T10 and T11 genotype in Tunisia.The occurrence of potentially pathogenic FLA in the hospital environment may represent a health risk for patients, since these organisms can cause severe opportunistic illness and also can harbor pathogenic agents. Thus, increased awareness regarding these parasites and recognition of their importance, particularly in immunocompromised patients is crucial.

  4. Of Amoebae and Men: Extracellular DNA Traps as an Ancient Cell-Intrinsic Defense Mechanism

    Science.gov (United States)

    Zhang, Xuezhi; Soldati, Thierry

    2016-01-01

    Since the discovery of the formation of DNA-based extracellular traps (ETs) by neutrophils as an innate immune defense mechanism (1), hundreds of articles describe the involvement of ETs in physiological and pathological human and animal conditions [reviewed in Ref. (2), and the previous Frontiers Research Topic on NETosis: http://www.frontiersin.org/books/NETosis_At_the_Intersection_of_Cell_Biology_Microbiology_and_Immunology/195]. Interestingly, a few reports reveal that ETs can be formed by immune cells of more ancient organisms, as far back as the common ancestor of vertebrates and invertebrates (3). Recently, we reported that the Sentinel cells of the multicellular slug of the social amoeba Dictyostelium discoideum also produce ETs to trap and kill slug-invading bacteria [see Box 1; and Figure 1 Ref. (4)]. This is a strong evidence that DNA-based cell-intrinsic defense mechanisms emerged much earlier than thought, about 1.3 billion years ago. Amazingly, using extrusion of DNA as a weapon to capture and kill uningestable microbes has its rationale. During the emergence of multicellularity, a primitive innate immune system developed in the form of a dedicated set of specialized phagocytic cells. This professionalization of immunity allowed the evolution of sophisticated defense mechanisms including the sacrifice of a small set of cells by a mechanism related to NETosis. This altruistic behavior likely emerged in steps, starting from the release of “dispensable” mitochondrial DNA by D. discoideum Sentinel cells. Grounded in this realization, one can anticipate that in the near future, many more examples of the invention and fine-tuning of ETs by early metazoan ancestors will be identified. Consequently, it can be expected that this more complete picture of the evolution of ETs will impact our views of the involvement and pathologies linked to ETs in human and animals. PMID:27458458

  5. Presence of Legionella and free-living Amoebae in composts and bioaerosols from composting facilities.

    Science.gov (United States)

    Conza, Lisa; Pagani, Simona Casati; Gaia, Valeria

    2013-01-01

    Several species of Legionella cause Legionnaires' disease (LD). Infection may occur through inhalation of Legionella or amoebal vesicles. The reservoirs of Legionella are water, soil, potting soil and compost. Some species of free-living amoebae (FLA) that are naturally present in water and soil were described as hosts for Legionella. This study aimed to understand whether or not the composting facilities could be sources of community-acquired Legionella infections after development of bioaerosols containing Legionella or FLA. We looked for the presence of Legionella (by co-culture) and FLA (by culture) in composts and bioaerosols collected at four composting facilities located in southern Switzerland. We investigated the association between the presence of Legionella and compost and air parameters and presence of FLA. Legionella spp. (including L. pneumophila) were detected in 69.3% (61/88) of the composts and FLA (mainly Acanthamoeba, Vermamoeba, Naegleria and Stenamoeba) in 92.0% (81/88). L. pneumophila and L. bozemanii were most frequently isolated. FLA as potential host for Legionella spp. were isolated from 40.9% (36/88) of the composts in all facilities. In Legionella-positive samples the temperature of compost was significantly lower (P = 0.012) than in Legionella-negative samples. Of 47 bioaerosol samples, 19.1% (9/47) were positive for FLA and 10.6% (5/47) for L. pneumophila. Composts (62.8%) were positive for Legionella and FLA contemporaneously, but both microorganisms were never detected simultaneously in bioaerosols. Compost can release bioaerosol containing FLA or Legionella and could represent a source of infection of community-acquired Legionella infections for workers and nearby residents.

  6. Presence of Legionella and free-living Amoebae in composts and bioaerosols from composting facilities.

    Directory of Open Access Journals (Sweden)

    Lisa Conza

    Full Text Available Several species of Legionella cause Legionnaires' disease (LD. Infection may occur through inhalation of Legionella or amoebal vesicles. The reservoirs of Legionella are water, soil, potting soil and compost. Some species of free-living amoebae (FLA that are naturally present in water and soil were described as hosts for Legionella. This study aimed to understand whether or not the composting facilities could be sources of community-acquired Legionella infections after development of bioaerosols containing Legionella or FLA. We looked for the presence of Legionella (by co-culture and FLA (by culture in composts and bioaerosols collected at four composting facilities located in southern Switzerland. We investigated the association between the presence of Legionella and compost and air parameters and presence of FLA. Legionella spp. (including L. pneumophila were detected in 69.3% (61/88 of the composts and FLA (mainly Acanthamoeba, Vermamoeba, Naegleria and Stenamoeba in 92.0% (81/88. L. pneumophila and L. bozemanii were most frequently isolated. FLA as potential host for Legionella spp. were isolated from 40.9% (36/88 of the composts in all facilities. In Legionella-positive samples the temperature of compost was significantly lower (P = 0.012 than in Legionella-negative samples. Of 47 bioaerosol samples, 19.1% (9/47 were positive for FLA and 10.6% (5/47 for L. pneumophila. Composts (62.8% were positive for Legionella and FLA contemporaneously, but both microorganisms were never detected simultaneously in bioaerosols. Compost can release bioaerosol containing FLA or Legionella and could represent a source of infection of community-acquired Legionella infections for workers and nearby residents.

  7. An expanded phylogeny of social amoebas (Dictyostelia shows increasing diversity and new morphological patterns

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    Stephenson Steven L

    2011-03-01

    Full Text Available Abstract Background Social Amoebae or Dictyostelia are eukaryotic microbes with a unique life cycle consisting of both uni- and multicellular stages. They have long fascinated molecular, developmental and evolutionary biologists, and Dictyostelium discoideum is now one of the most widely studied eukaryotic microbial models. The first molecular phylogeny of Dictyostelia included most of the species known at the time and suggested an extremely deep taxon with a molecular depth roughly equivalent to Metazoa. The group was also shown to consist of four major clades, none of which correspond to traditional genera. Potential morphological justification was identified for three of the four major groups, on the basis of which tentative names were assigned. Results Over the past four years, the Mycetozoan Global Biodiversity Survey has identified many new isolates that appear to be new species of Dictyostelia, along with numerous isolates of previously described species. We have determined 18S ribosomal RNA gene sequences for all of these new isolates. Phylogenetic analyses of these data show at least 50 new species, and these arise from throughout the dictyostelid tree breaking up many previously isolated long branches. The resulting tree now shows eight well-supported major groups instead of the original four. The new species also expand the known morphological diversity of the previously established four major groups, violating nearly all previously suggested deep morphological patterns. Conclusions A greatly expanded phylogeny of Dictyostelia now shows even greater morphological plasticity at deep taxonomic levels. In fact, there now seem to be no obvious deep evolutionary trends across the group. However at a finer level, patterns in morphological character evolution are beginning to emerge. These results also suggest that there is a far greater diversity of Dictyostelia yet to be discovered, including novel morphologies.

  8. Quantitative detection and differentiation of free-living amoeba species using SYBR green-based real-time PCR melting curve analysis.

    Science.gov (United States)

    Behets, Jonas; Declerck, Priscilla; Delaedt, Yasmine; Verelst, Lieve; Ollevier, Frans

    2006-12-01

    Real-time polymerase chain reaction melting curve analysis (MCA) allows differentiation of several free-living amoebae species. Distinctive characteristics were found for Naegleria fowleri, N. lovaniensis, N. australiensis, N. gruberi, Hartmanella vermiformis, and Willaertia magna. Species specificity of the amplicons was confirmed using agarose gel electrophoresis and sequence-based approaches. Amplification efficiency ranged from 91% to 98%, indicating the quantitative potential of the assay. This MCA approach can be used for quantitative detection of free-living amoebae after cultivation but also as a culture-independent detection method.

  9. Is there a size limit for cosmopolitan distribution in free-living microorganisms? A biogeographical analysis of testate amoebae from polar areas.

    Science.gov (United States)

    Yang, Jun; Smith, Humphrey G; Sherratt, Thomas N; Wilkinson, David M

    2010-05-01

    A long-standing debate in microbial ecology is the extent to which free-living microorganisms exhibit cosmopolitan distributions. We use a comparison of testate amoebae communities in cold "polar" locations (Arctic, Antarctic, and Tibet) to investigate how a microorganism's size affects its probability of having a cosmopolitan distribution. We show that the probability a given taxa being reported in all three locations increases as testate size decreases. Likewise, excluding those testates found only in Tibet, very small testates (amoebae, a cosmopolitan distribution becomes increasingly common as median taxon size decreases.

  10. Relationships between testate amoeba communities and water quality in Lake Donghu,a large alkaline lake in Wuhan, China

    Institute of Scientific and Technical Information of China (English)

    Yangmin QIN; Bertrand FOURNIER; Enrique LARA; Yansheng GU; Hongmei WANG; Yongde CUI; Xiaoke ZHANG

    2013-01-01

    The middle Yangtze Reach is one of the most developed regions of China.As a result,most lakes in this area have suffered from eutrophication and serious environmental pollution during recent decades.The aquatic biodiversity in the lakes of the area is thus currently under significant threat from continuous human activities.Testate amoebae (TA) are benthic (rarely planktonic) microorganisms characterized by an agglutinated or autogenous shell.Owing to their high abundance,preservation potential in lacustrine sediments,and distinct response to environmental stress,they are increasingly used as indicators for monitoring water quality and reconstructing palaeoenvironmental changes.However this approach has not yet been developed in China.This study presents an initial assessment of benthic TA assemblages in eight lakes of Lake Donghu in the region of Wuhan,China.Testate amoeba community structure was most strongly correlated to water pH.In more alkaline conditions,communities were dominated by Centropyxis aculeata,Difflugia oblonga,Pontigulasia compressa,Pon.elisa and Lesquereusia modesta.These results are consistent with previous studies and show that TA could be useful for reconstructing past water pH fluctuations in China.To achieve this,the next step will be to expand the database and build transfer function models.

  11. Amoeba host-Legionella synchronization of amino acid auxotrophy and its role in bacterial adaptation and pathogenic evolution.

    Science.gov (United States)

    Price, Christopher T D; Richards, Ashley M; Von Dwingelo, Juanita E; Samara, Hala A; Abu Kwaik, Yousef

    2014-02-01

    Legionella pneumophila, the causative agent of Legionnaires' disease, invades and proliferates within a diverse range of free-living amoeba in the environment, but upon transmission to humans, the bacteria hijack alveolar macrophages. Intracellular proliferation of L. pneumophila in two evolutionarily distant hosts is facilitated by bacterial exploitation of conserved host processes that are targeted by bacterial protein effectors injected into the host cell. A key aspect of microbe-host interaction is microbial extraction of nutrients from the host, but understanding of this is still limited. AnkB functions as a nutritional virulence factor and promotes host proteasomal degradation of polyubiquitinated proteins generating gratuitous levels of limiting host cellular amino acids. Legionella pneumophila is auxotrophic for several amino acids including cysteine, which is a metabolically preferred source of carbon and energy during intracellular proliferation, but is limiting in both amoebae and humans. We propose that synchronization of bacterial amino acids auxotrophy with the host is a driving force in pathogenic evolution and nutritional adaptation of L. pneumophila and other intracellular bacteria to life within the host cell. Understanding microbial strategies of nutrient generation and acquisition in the host will provide novel antimicrobial strategies to disrupt pathogen access to essential sources of carbon and energy.

  12. Sex ratio and gamete size across eastern North America in Dictyostelium discoideum, a social amoeba with three sexes.

    Science.gov (United States)

    Douglas, T E; Strassmann, J E; Queller, D C

    2016-07-01

    Theory indicates that numbers of mating types should tend towards infinity or remain at two. The social amoeba, Dictyostelium discoideum, however, has three mating types. It is therefore a mystery how this species has broken the threshold of two mating types, but has not increased towards a much higher number. Frequency-dependent selection on rare types in combination with isogamy, a form of reproduction involving gametes similar in size, could explain the evolution of multiple mating types in this system. Other factors, such as drift, may be preventing the evolution of more than three. We first looked for evidence of isogamy by measuring gamete size associated with each type. We found no evidence of size dissimilarities between gametes. We then looked for evidence of balancing selection, by examining mating type distributions in natural populations and comparing genetic differentiation at the mating type locus to that at more neutral loci. We found that mating type frequency varied among the three populations we examined, with only one of the three showing an even sex ratio, which does not support balancing selection. However, we found more population structure at neutral loci than the mating type locus, suggesting that the three mating types are indeed maintained at intermediate frequencies by balancing selection. Overall, the data are consistent with balancing selection acting on D. discoideum mating types, but with a sufficiently weak rare sex advantage to allow for drift, a potential explanation for why these amoebae have only three mating types.

  13. Free-living amoebae and their associated bacteria in Austrian cooling towers: a 1-year routine screening.

    Science.gov (United States)

    Scheikl, Ute; Tsao, Han-Fei; Horn, Matthias; Indra, Alexander; Walochnik, Julia

    2016-09-01

    Free-living amoebae (FLA) are widely spread in the environment and known to cause rare but often serious infections. Besides this, FLA may serve as vehicles for bacterial pathogens. In particular, Legionella pneumophila is known to replicate within FLA thereby also gaining enhanced infectivity. Cooling towers have been the source of outbreaks of Legionnaires' disease in the past and are thus usually screened for legionellae on a routine basis, not considering, however, FLA and their vehicle function. The aim of this study was to incorporate a screening system for host amoebae into a Legionella routine screening. A new real-time PCR-based screening system for various groups of FLA was established. Three cooling towers were screened every 2 weeks over the period of 1 year for FLA and Legionella spp., by culture and molecular methods in parallel. Altogether, 83.3 % of the cooling tower samples were positive for FLA, Acanthamoeba being the dominating genus. Interestingly, 69.7 % of the cooling tower samples were not suitable for the standard Legionella screening due to their high organic burden. In the remaining samples, positivity for Legionella spp. was 25 % by culture, but overall positivity was 50 % by molecular methods. Several amoebal isolates revealed intracellular bacteria.

  14. Sex ratio and gamete size across eastern North America in Dictyostelium discoideum, a social amoeba with three sexes.

    Science.gov (United States)

    Douglas, T E; Strassmann, J E; Queller, D C

    2016-07-01

    Theory indicates that numbers of mating types should tend towards infinity or remain at two. The social amoeba, Dictyostelium discoideum, however, has three mating types. It is therefore a mystery how this species has broken the threshold of two mating types, but has not increased towards a much higher number. Frequency-dependent selection on rare types in combination with isogamy, a form of reproduction involving gametes similar in size, could explain the evolution of multiple mating types in this system. Other factors, such as drift, may be preventing the evolution of more than three. We first looked for evidence of isogamy by measuring gamete size associated with each type. We found no evidence of size dissimilarities between gametes. We then looked for evidence of balancing selection, by examining mating type distributions in natural populations and comparing genetic differentiation at the mating type locus to that at more neutral loci. We found that mating type frequency varied among the three populations we examined, with only one of the three showing an even sex ratio, which does not support balancing selection. However, we found more population structure at neutral loci than the mating type locus, suggesting that the three mating types are indeed maintained at intermediate frequencies by balancing selection. Overall, the data are consistent with balancing selection acting on D. discoideum mating types, but with a sufficiently weak rare sex advantage to allow for drift, a potential explanation for why these amoebae have only three mating types. PMID:27018644

  15. Effect of disinfectants on pathogenic free-living amoebae: in axenic conditions.

    OpenAIRE

    Cursons, R T; Brown, T J; Keys, E A

    1980-01-01

    The amoebicidal properties of chlorine, chlorine dioxide, ozone, and deciquam 222 were examined in axenic conditions. Naegleria spp. were found to be more sensitive to chlorine and chlorine dioxide than Acanthamoeba spp. No marked difference in sensitivity to ozone or deciquam 222 could be detected between the pathogenic (A-1) and nonpathogenic (1501) strains of Acanthamoeba and the pathogenic (MsT) and nonpathogenic (P1200f) strains of Naegleria. Methods of disinfection are discussed with re...

  16. Coprophilic amoebae and flagellates, including Guttulinopsis, Rosculus and Helkesimastix, characterise a divergent and diverse rhizarian radiation and contribute to a large diversity of faecal-associated protists

    NARCIS (Netherlands)

    Bass, David; Silberman, Jeffrey; Brown, M.W.; Pearce, R.A.; Tice, A.K.; Jousset, A.; Geisen, Stefan; Hartikainen, Hanna

    2016-01-01

    A wide diversity of organisms utilize faecal habitats
    as a rich nutrient source or a mechanism to traverse
    through animal hosts. We sequenced the 18S rRNA
    genes of the coprophilic, fruiting body-forming
    amoeba Guttulinopsis vulgaris and its non-fruiting
    relatives Rosculus ‘ithacu

  17. Folic acid is a potent chemoattractant of free-living amoebae in a new and amazing species of protist, Vahlkampfia sp.

    Science.gov (United States)

    Maeda, Yasuo; Mayanagi, Taira; Amagai, Aiko

    2009-03-01

    Folic acid (folate; vitamin Bc) is well recognized as essential for the proper metabolism of the essential amino acid methionine as well as for the synthesis of adenine and thymine. A folate deficiency has been Implicated in a wide variety of disorders from Alzheimer's disease to depression and neural tube defects. In the cellular slime molds, including Dictyostelium, vegetative growth-phase cells are known to chemotactically move toward folate that is secreted by bacterial food sources such as Escherichia coli. Intracellular folate signal transductlon, including G proteins, Ca(2+)channels, and the PIP3 pathway, has been reported in D. discoideum. To our surprise, the genuine chemoattractant(s) of free-living protozoan amoebae have remained to be determined, possibly because of lack of a pertinent method for assaying chemotaxis. We recently isolated a primitive free-living amoeba from the soil of Costa Rica and identified it as a new species of the genus Vahlkampfia belonging to Subclass Gymnamoebia, which includes Entamoeba and Acanthamoeba. The amoebae can grow and multiply quite rapidly, engulfing nearby bacteria such as E. coli. Importantly, we have demonstrated here using a quite simple but finely designed chemotaxis assay that the Vahlkampfia amoebae exhibit chemotaxis toward higher folate concentrations. Riboflavin and cyanocobalamin were also found to serve as positive chemoattractants. Among these chemoattractants, folate is of particular importance because its function seems to be evolutionarily conserved as a potent chemoattractant of amoeboid cells in a wide range of organisms as well as in the Protista and cellular slime molds.

  18. Isolamento de amebas de vida livre a partir de água mineral engarrafada Isolation of free-living amoebae from bottled mineral water

    Directory of Open Access Journals (Sweden)

    Homero Coutinho Salazar

    1982-10-01

    Full Text Available Foram isoladas amebas dos gêneros Vahlkampfia, Glaeseria, Acanthamoeba, Filamoeba, Amoeba, Platyamoeba e Hartmanella de dez diferentes marcas de água mineral engarrafadas, servidas no Rio de Janeiro, RJ (Brasil. Somente uma das marcas foi negativa para protozoários, enquanto que de todas as outras foram isoladas amebas de vida livre. O significado desses resultados é discutido como um indicador de qualidade da água mineral usada comercialmente, destacando-se o fato de que alguns desses microorganismos são potencialmente patogênicos.Amoebae of the genera Vahlkampfia, Glaeseria, Acanthamoeba, Filamoeba, Amoeba, Platyamoeba and Hartmanella were isolated from ten different brands of bottled mineral water used in Rio de Janeiro. Of these brands, only one was negative after an incubation period of twenty days, while the others were all positive for free living amoebae. The results are discussed as an indicator of the quality of commercially used mineral water and it is stressed that some of these microorganisms are potentially pathogenic.

  19. Micriamoeba tesseris nov. gen. nov. sp.: a new taxon of free-living small-sized Amoebae non-permissive to virulent Legionellae.

    Science.gov (United States)

    Atlan, Danièle; Coupat-Goutaland, Bénédicte; Risler, Arnaud; Reyrolle, Monique; Souchon, Maud; Briolay, Jérôme; Jarraud, Sophie; Doublet, Patricia; Pélandakis, Michel

    2012-11-01

    Investigation of soil amoebae in 11 cooling towers allowed us to isolate a major unknown small-sized amoeba population (SZA). However, SZA did not appear to be specific to cooling tower ecosystems since they are also a major amoeba population found in muds isolated from different points of a water treatment plant. The SSU-rDNA sequences from SZA strains did not match any known database sequences, suggesting that SZA constitutes a new amoeba taxon. We isolated and further described one of the SZA that we named Micriamoeba tesseris. The phylogenetic analyses showed that Micriamoeba tesseris belongs to the Amebozoa and branched together with genus Echinamoeba+Vermamoeba vermiformis. Phylogenetic analyses within the Micriamoeba group distinguished different subgroups of Micriamoeba strains according to their origin, i.e. cooling tower or mud. Although Micriamoeba are able to feed on viable E. coli cells, they do not uptake virulent Legionella pneumophila strains, thus enabling them to avoid infection by Legionella. Consequently, Micriamoeba is not directly involved in L. pneumophila multiplication. However, an indirect role of Micriamoeba in Legionella risk is discussed.

  20. Does climate warming stimulate or inhibit soil protist communities? A test on testate amoebae in high-arctic tundra with free-air temperature increase.

    Science.gov (United States)

    Tsyganov, Andrey N; Nijs, Ivan; Beyens, Louis

    2011-04-01

    Soil testate amoebae assemblages in a grassland area at Zackenberg (Northeast Greenland) were subjected to simulated climate-warming during the growing season using the Free-Air Temperature Increase technique. Samples were collected in upper (0 - 3cm) and deeper (3 - 6cm) soil horizons. Mean temperature elevations at 2.5 and 7.5 cm depth were 2.58 ± SD 1.11 and 2.13±SD 0.77°C, respectively, and did not differ significantly. Soil moisture in the top 11cm was not affected by the warming. During the manipulation, the densities of living amoebae and empty shells were higher in the experimental plots but only in the upper layer. Possibly, testate amoebae in the deeper layer were limited by other factors, suggesting that warming enhances the carrying capacity only in favourable conditions. Species richness, on the other hand, was only increased in the deeper horizon. Warming did not change the percentage of individuals belonging to small-sized species in any of the living assemblages, contrary to our expectation that those species would quickly increase their density. However, in the empty shell assemblages, the proportion of small-sized individuals in the experimental plots was higher in both layers, indicating a rapid, transient increase in small amoebae before the first sampling date. Changes in successional state of testate amoebae assemblages in response to future climate change might thus be ephemeral, whereas alterations in density and species richness might be more sustained.

  1. 阿米巴经营与市场型企业%Amoeba Management and Market-type Enterprise

    Institute of Scientific and Technical Information of China (English)

    胡关子

    2011-01-01

    京瓷公司阿米巴经营取得了极大的成功,其原因在于构建了独特的组织形式与运行机制,即在阿米巴的组织基础上,通过核算机制引入了市场价格,再利用其独特的权威机制来克服企业部价格机制的不足。这样,使得企业的外部激励部化,低能激励高能化,从而提高了企业对市场的反应速度与企业的竞争力。我们称这种引入市场机制的企业为市场型企业,但我们也发现,随着企业的增大,企业部的价格机制就越难以发挥作用,故阿米巴经营也有它的局限性。%Amoeba management has brought Kyocera a huge success, for the company has constructed a unique form of organization and operation mechanism. That is, the market price was introduced through the accounting mechanism on the basis of organization of Amoeba, and then Kyocera used its unique authoritative mechanism to overcome the deficiency of the internal price mechanism. Thus, it led the enterprise to internalize the external incentives, and low-energy incentives to high-energy, so that it helps to fasten the reaction speed to the market and the competitiveness of enterprise. The enterprise, which introduces market mechanism, is called the market-type firm. But we also find out that, with the expansion of the enterprise, the internal price mechanism will be difficult to play its role, so there are still certain limitations in Amoeba management.

  2. [Investigation of potentially pathogenic free-living amoebae and their in vivo pathogenicity in water supplies of Turkey].

    Science.gov (United States)

    Yazar, Süleyman; Gürbüz, Esra; Sönmez, Mehmet Fatih; Çetinkaya, Ülfet; Kuk, Salih

    2016-07-01

    Free-living amoebae (FLA) are found widely in soil and water in the nature. Among them in which potentially pathogenic for humans and animals are known as "potential pathogenic free-living amoebae (PPFLA)". PPFLA are characterized as the causes of clinical manifestations leading to death especially in immunosuppressed people. Four genus of PPFLA (Acanthamoeba, Naegleria, Balamuthia and Sappinia) are known to be pathogenic to humans. The aims of this study were to investigate the presence of PPFLA in the water supplies in Turkey and to determine their in vivo pathogenicity. A total of 664 water samples were collected from the ponds, rivers, streams and wells found in provinces located at different regions (central, western, eastern and southeastern regions) of Turkey. These samples were initially inoculated in the monoxenic culture media and evaluated by both microscopy and polymerase chain reaction (PCR) in terms of the presence of FLA. The samples identified as positive were then cultured in axenic media, the growth of amoebae that were confirmed microscopically, were than studied with PCR for molecular characterization. The isolates that were found positive by PCR from axenic cultures were inoculated intranasally to immunocompetent and immunodeficient (athymic) [BALB/c Rag2(-/-) gamma(c)(-/-)] BALB/c mice followed by the evaluation on the 21st day by histopathological and molecular methods to investigate their in vivo pathogenicity. In our study, 143 water samples were detected as positive in monoxenic cultures and 41 of them were detected as positive in axenic cultures. Twenty of 41 samples detected as positive in axenic culture could be continued in culture for three months. As a result of PCR using primers common to SYA, only nine have been identified from 20 samples as positive. According to the result of the PCR with specific primers, all (n= 9) were positive for Acanthamoeba sp., eight for Sappini sp. and five for Balamuthia mandrillaris, while none was

  3. [Investigation of potentially pathogenic free-living amoebae and their in vivo pathogenicity in water supplies of Turkey].

    Science.gov (United States)

    Yazar, Süleyman; Gürbüz, Esra; Sönmez, Mehmet Fatih; Çetinkaya, Ülfet; Kuk, Salih

    2016-07-01

    Free-living amoebae (FLA) are found widely in soil and water in the nature. Among them in which potentially pathogenic for humans and animals are known as "potential pathogenic free-living amoebae (PPFLA)". PPFLA are characterized as the causes of clinical manifestations leading to death especially in immunosuppressed people. Four genus of PPFLA (Acanthamoeba, Naegleria, Balamuthia and Sappinia) are known to be pathogenic to humans. The aims of this study were to investigate the presence of PPFLA in the water supplies in Turkey and to determine their in vivo pathogenicity. A total of 664 water samples were collected from the ponds, rivers, streams and wells found in provinces located at different regions (central, western, eastern and southeastern regions) of Turkey. These samples were initially inoculated in the monoxenic culture media and evaluated by both microscopy and polymerase chain reaction (PCR) in terms of the presence of FLA. The samples identified as positive were then cultured in axenic media, the growth of amoebae that were confirmed microscopically, were than studied with PCR for molecular characterization. The isolates that were found positive by PCR from axenic cultures were inoculated intranasally to immunocompetent and immunodeficient (athymic) [BALB/c Rag2(-/-) gamma(c)(-/-)] BALB/c mice followed by the evaluation on the 21st day by histopathological and molecular methods to investigate their in vivo pathogenicity. In our study, 143 water samples were detected as positive in monoxenic cultures and 41 of them were detected as positive in axenic cultures. Twenty of 41 samples detected as positive in axenic culture could be continued in culture for three months. As a result of PCR using primers common to SYA, only nine have been identified from 20 samples as positive. According to the result of the PCR with specific primers, all (n= 9) were positive for Acanthamoeba sp., eight for Sappini sp. and five for Balamuthia mandrillaris, while none was

  4. Coexistence of Legionella pneumophila Bacteria and Free-Living Amoebae in Lakes Serving as a Cooling System of a Power Plant.

    Science.gov (United States)

    Zbikowska, Elżbieta; Kletkiewicz, Hanna; Walczak, Maciej; Burkowska, Aleksandra

    2014-01-01

    The study was aimed at determining whether potentially pathogenic free-living amoebae (FLA) and Legionella pneumophila can be found in lakes serving as a natural cooling system of a power plant. Water samples were collected from five lakes forming the cooling system of the power plants Pątnów and Konin (Poland). The numbers of investigated organisms were determined with the use of a very sensitive molecular method-fluorescence in situ hybridization (FISH). The result of the present study shows that thermally altered aquatic environments provide perfect conditions for the growth of L. pneumophila and amoebae. The bacteria were identified in the biofilm throughout the entire research period and in the subsurface water layer in July and August. Hartmanella sp. and/or Naegleria fowleri were identified in the biofilm throughout the entire research period.

  5. [i]Legionella spp[/i]., amoebae and not-fermenting Gram negative bacteria in an Italian university hospital water system

    OpenAIRE

    Pasqualina Laganà; Gabriella Caruso; Davide Piccione; Maria Eufemia Gioffrè; Raffaella Pino; Santi Delia

    2014-01-01

    [b]Introduction. [/b]In hospital and other health care facilities, contamination of water systems by potentially infectious microorganisms, such as bacteria, viruses and protozoa, is a source of nosocomial infections, which may originate fromcolonization of water pipes, cooling towers, spa pools, taps, showers and water supplies. [b]Objective. [/b]The study focuses on the occurrence of [i]Legionella spp.[/i], free-living amoebae and non-fermenting Gram-negative microorganisms in a Unive...

  6. Occurrence and molecular characterization of free-living amoeba species (Acanthamoeba, Hartmannella, and Saccamoeba limax) in various surface water resources of Iran.

    Science.gov (United States)

    Mahmoudi, Mohammad Reza; Rahmati, Behnaz; Seyedpour, Seyed Hosssen; Karanis, Panagiotis

    2015-12-01

    This study was conducted to determine the presence and molecular identity of Acanthamoeba species in the surface water resources of four provinces in Iran, namely Guilan, Mazandaran (North of Iran), Alborz, and Tehran (capital city), using culture- and molecular-based methods. During March to November 2014, 49 surface water samples were collected from environmental water sources-the distinct surface waters of Guilan, Mazandaran, Alborz, and Tehran provinces, in Iran. For the isolation of Acanthamoeba species, approximately 500 ml of the water samples were filtered through a cellulose nitrate membrane with a pore size of 0.45 μ. The filter was transferred onto non-nutrient agar plates seeded with Gram-negative bacteria (Escherichia coli) as a food source. The presence of Acanthamoeba was confirmed by the genus-specific primer pair JDP1 and 2, and/or NA primers were used to identify Acanthamoeba and certain other free-living amoebae. In total, 38 out of 49 samples were positive by culture and/or PCR for Acanthamoeba and other free-living amoebae from all three provinces. By sequencing the positive isolates, the strains were shown to belong to Acanthamoeba (16 isolates belonged to T4 and 2 isolates belonged to T5), Hartmannella vermiformis (3/24), and Saccamoeba limax (2/24). The T4 and T5 genotypes were detected in Guilan and Mazandaran provinces. Two isolates from Guilan and Tehran provinces belonged to S. limax, and H. vermiformis was detected in Guilan province. The results of this study highlight the need to pay more attention to free-living amoebae, as human activity was observed in all of the localities from which these samples were taken. These surface waters can be potential sources for the distribution and transmission of pathogenic Acanthamoeba in the study areas, and free-living amoebas (FLA) (particularly the Acanthamoeba species) can serve as hosts for and vehicles of various microorganisms.

  7. PCR detection and analysis of the free-living amoeba Naegleria in hot springs in Yellowstone and Grand Teton National Parks.

    Science.gov (United States)

    Sheehan, Kathy B; Fagg, Jennifer A; Ferris, Michael J; Henson, Joan M

    2003-10-01

    Free-living thermotolerant amoebae pose a significant health risk to people who soak and swim in habitats suitable for their growth, such as hot springs. In this survey of 23 different hot springs in Yellowstone and Grand Teton National Parks, we used PCR with primer sets specific for Naegleria to detect three sequence types that represent species not previously described, as well as a fourth sequence type identified as the pathogen Naegleria fowleri.

  8. PCR Detection and Analysis of the Free-Living Amoeba Naegleria in Hot Springs in Yellowstone and Grand Teton National Parks

    OpenAIRE

    Sheehan, Kathy B.; Fagg, Jennifer A.; Ferris, Michael J.; Henson, Joan M.

    2003-01-01

    Free-living thermotolerant amoebae pose a significant health risk to people who soak and swim in habitats suitable for their growth, such as hot springs. In this survey of 23 different hot springs in Yellowstone and Grand Teton National Parks, we used PCR with primer sets specific for Naegleria to detect three sequence types that represent species not previously described, as well as a fourth sequence type identified as the pathogen Naegleria fowleri.

  9. Moss stable isotopes (carbon-13, oxygen-18) and testate amoebae reflect environmental inputs and microclimate along a latitudinal gradient on the Antarctic Peninsula.

    Science.gov (United States)

    Royles, Jessica; Amesbury, Matthew J; Roland, Thomas P; Jones, Glyn D; Convey, Peter; Griffiths, Howard; Hodgson, Dominic A; Charman, Dan J

    2016-07-01

    The stable isotope compositions of moss tissue water (δ(2)H and δ(18)O) and cellulose (δ(13)C and δ(18)O), and testate amoebae populations were sampled from 61 contemporary surface samples along a 600-km latitudinal gradient of the Antarctic Peninsula (AP) to provide a spatial record of environmental change. The isotopic composition of moss tissue water represented an annually integrated precipitation signal with the expected isotopic depletion with increasing latitude. There was a weak, but significant, relationship between cellulose δ(18)O and latitude, with predicted source water inputs isotopically enriched compared to measured precipitation. Cellulose δ(13)C values were dependent on moss species and water content, and may reflect site exposure to strong winds. Testate amoebae assemblages were characterised by low concentrations and taxonomic diversity, with Corythion dubium and Microcorycia radiata types the most cosmopolitan taxa. The similarity between the intra- and inter-site ranges measured in all proxies suggests that microclimate and micro-topographical conditions around the moss surface were important determinants of proxy values. Isotope and testate amoebae analyses have proven value as palaeoclimatic, temporal proxies of climate change, whereas this study demonstrates that variations in isotopic and amoeboid proxies between microsites can be beyond the bounds of the current spatial variability in AP climate. PMID:27003701

  10. Moss stable isotopes (carbon-13, oxygen-18) and testate amoebae reflect environmental inputs and microclimate along a latitudinal gradient on the Antarctic Peninsula.

    Science.gov (United States)

    Royles, Jessica; Amesbury, Matthew J; Roland, Thomas P; Jones, Glyn D; Convey, Peter; Griffiths, Howard; Hodgson, Dominic A; Charman, Dan J

    2016-07-01

    The stable isotope compositions of moss tissue water (δ(2)H and δ(18)O) and cellulose (δ(13)C and δ(18)O), and testate amoebae populations were sampled from 61 contemporary surface samples along a 600-km latitudinal gradient of the Antarctic Peninsula (AP) to provide a spatial record of environmental change. The isotopic composition of moss tissue water represented an annually integrated precipitation signal with the expected isotopic depletion with increasing latitude. There was a weak, but significant, relationship between cellulose δ(18)O and latitude, with predicted source water inputs isotopically enriched compared to measured precipitation. Cellulose δ(13)C values were dependent on moss species and water content, and may reflect site exposure to strong winds. Testate amoebae assemblages were characterised by low concentrations and taxonomic diversity, with Corythion dubium and Microcorycia radiata types the most cosmopolitan taxa. The similarity between the intra- and inter-site ranges measured in all proxies suggests that microclimate and micro-topographical conditions around the moss surface were important determinants of proxy values. Isotope and testate amoebae analyses have proven value as palaeoclimatic, temporal proxies of climate change, whereas this study demonstrates that variations in isotopic and amoeboid proxies between microsites can be beyond the bounds of the current spatial variability in AP climate.

  11. From Environmental Sequences to Morphology: Observation and Characterisation of a Paulinellid Testate Amoeba (Micropyxidiella edaphonis gen. nov. sp. nov. Euglyphida, Paulinellidae) from Soil using Fluorescent in situ Hybridization.

    Science.gov (United States)

    Tarnawski, Sonia-Estelle; Lara, Enrique

    2015-05-01

    High microbial diversity is revealed by environmental DNA surveys. However, nothing is known about the morphology and function of these potentially new organisms. In the course of an environmental soil diversity study, we found for the first time environmental sequences that reveal the presence of Paulinellidae (a mostly marine and marginally freshwater family of euglyphid testate amoebae) in samples of forest litter from different geographic origins. The new sequences form a basal, robust clade in the family. We used fluorescent in situ hybridization (FISH) to detect the organisms from which these sequences derived. We isolated the cells and documented them with light and scanning electron microscopy. Based on these observations, we described these organisms as Micropyxidiella edaphonis gen. nov. sp. nov. The organisms were very small testate amoebae (generally less than 10μm) with an irregular proteinaceous test. This suggests an unknown diversity in testate amoebae, and calls for extending this type of investigations to other protist groups which are known only as environmental DNA sequences.

  12. Morphological Features and In Vitro Cytopathic Effect of Acanthamoeba griffini Trophozoites Isolated from a Clinical Case

    Directory of Open Access Journals (Sweden)

    Arturo González-Robles

    2014-01-01

    Full Text Available Light and transmission electron microscopy observations are reported on the structure and in vitro cytopathic effect of Acanthamoeba griffini trophozoites isolated from a clinical case. Live trophozoites were moderately active with a remarkable pleomorphism which changed from ovoid to quite elongated shapes. When moving, amoebae formed cytoplasmic projections such as wide lamellae and acanthopodia of diverse size and thickness which contain a significant amount of actin. Ultrastructurally, the cytoplasm showed the main organelles found in other free-living amoebae. Coincubation of trophozoites with MDCK cell monolayers resulted in a local damage to target cells after 24 h of interaction, suggesting that the cytopathic effect is contact-dependent. By transmission electron microscopy, amoebae appeared to engulf small portions of the MDCK cells; however, the cells that were not in contact with trophozoites had an unaltered morphology. When epithelial monolayers were incubated with conditioned medium for 24 h, small areas of cell injury were also observed. The phylogenetical analysis as well as the sequencing of the acquired amplified product for the DF3 region of the amoebae isolate confirmed that it belongs to genotype T3, which includes other pathogenic amoebae; besides the activity of two drugs currently used against Acanthamoeba was tested on A. griffini.

  13. Isolamento de amebas de vida livre potencialmente patogênicas em poeira de hospitais Isolation of potencially pathogenic free-living amoebas in hospital dust

    Directory of Open Access Journals (Sweden)

    Maria Aparecida da Silva

    2003-04-01

    Full Text Available OBJETIVO: Observar a ocorrência de amebas de vida livre dos gêneros Acanthamoeba e Naegleria em amostras de poeira coletadas em hospitais. MÉTODOS: Foram coletadas 132 amostras de poeira em dois hospitais do município de Presidente Prudente, São Paulo. Os locais da coleta foram: Unidade de Terapia Intensiva, Centro Cirúrgico, Isolamento de Moléstias Infecciosas, Berçário, Emergência e Cozinha. As amostras foram semeadas em três meios de cultura: meio de ágar não nutriente com Escherichia coli, meio de ágar infusão de soja e microcultivo em meio de Pavlova modificado por Giazzi. As amebas isoladas foram identificadas segundo critérios morfológicos. RESULTADOS: O índice geral de positividade para amebas de vida livre, potencialmente patogênicas, dos gêneros Acanthamoeba e Naegleria, foi de 45,5%, sendo positivas 41,6% das amostras de poeira coletadas no hospital universitário e 50% no hospital estadual. Obtiveram-se 45,5% de positividade do gênero Acanthamoeba e 3,8% para amebas do gênero Naegleria. CONCLUSÕES: As amebas de vida livre, potencialmente patogênicas, estavam presentes em todos os ambientes estudados dos dois hospitais, sendo que as espécies do gênero Acanthamoeba foram as isoladas com maior freqüência.OBJECTIVE: To evaluate the occurrence of free-living amoebas of the genera Acanthamoeba and Naegleria is dust samples colleted in two hospitals. METHODS: One-hundred and thirty-two dust samples were collected in two hospitals in Brazil. Hospital collection sites were the following: intensive care unit, operation rooms, nursery, kitchen, emergency and infectious diseases isolation room . The isolation of the amoebas was performed in three culture media: non-nutrient agar inoculated with Escherichia coli, soy agar, and microculture in Giazzi-modified Pavlova's medium. The amoebas were identified according to morphological criteria. RESULTS: Amoebas of the genera Acanthamoeba and Naegleria were found in 45.5% of

  14. Changes of autophagy during encystation of free-living amoeba%自由生活阿米巴成囊过程中的自噬变化

    Institute of Scientific and Technical Information of China (English)

    王南宁; 谭玉珍; 王海杰

    2011-01-01

    Objective To investigate autophagic changes of free-living amoeha during transformation from trophozoites to cysts. Methods Trophozoites were induced to form cysts with withdrawing of E. coli from the medium.Autophagic changes of the amoeha were investigated on 24hours, 36hours and 48hours after induction. the morphological changes of amoeba during encystation were viewed with a scanning electron microscope, The autophagic structures in amoeba were examined with a transmission electron microscope, cross-section areas of the autophagic structures were measured with an image analyzer. The autophagosomes of amoeba were labeled with monodansylcadaverine ( MDC ) staining and counted under confocal laser scanning microscope. Results In the control group, amoeba was full of fragment of E.coli, the level of autophagy was low. There were few autophagic structures in amoeba. Comparing with the control group,the autophagic level of amoeha after induction for 24 hours was enhanced significantly. Number of autophagic structures increased, the ratios of the cross-sectional areas of the autophagic precursors, autophagosomes and autophagolysosomes to that of the cytoplasm of amoeba were higher. The level of autophagy was attenuated significantly and number of autophagic structures decreased after induction for 36 hours. After induction for 48 hours, 92% trophozoites were transform to cysts,no autophagic structures were observed. Conclusion During encystation, autophagic activities of amoeba increased significantly in the early phase and decreaed in the later phase gradually.%目的 探讨自由生活阿米巴由滋养体向包囊转变过程中的自噬变化.方法 通过撤除大肠埃希菌培养基,诱导滋养体转变为包囊,分别在24 h、36 h和48 h时进行观察.在扫描电子显微镜下观察阿米巴成囊过程中的形态学变化,透射电镜下观察阿米巴自噬的变化及各种自噬结构的结构特点,图像分析仪测量自噬结构的断面面

  15. 大变形虫(Amoeba proteus)室内培养方法的比较

    Institute of Scientific and Technical Information of China (English)

    陈建琴; 吴蓓蓓

    2003-01-01

    大变形虫(Amoeba proteus)是原生动物门肉足亚门(Sarcodina)、根足总纲(Rhizopoda)、叶足纲(Lobosea)、变形目(Amoebida)、变形虫科(Amoebidae)、变形虫属(Amoeba)的代表动物,最主要的特征是虫体的细胞质可以延伸形成伪足,做变形动物(amoeboid movement).一般生活在池塘、水坑中,通常附着在浸没的植物上或粘性沉渣中,密度小,野外采集困难,镜检难度大.为满足高校无脊椎动物学实验教学的需要,本文比较了室内培养大变形虫的几种方法,以获得充足的实验材料.

  16. Presence of potentially pathogenic free-living amoebae strains from well water samples in Guinea-Bissau

    Science.gov (United States)

    Baquero, Rocío A; Reyes-Batlle, María; Nicola, Graciela G; Martín-Navarro, Carmen M; López-Arencibia, Atteneri; Guillermo Esteban, J; Valladares, Basilio; Martínez-Carretero, Enrique; Piñero, José E; Lorenzo-Morales, Jacob

    2014-01-01

    Free-living amoebae (FLA) include opportunistic pathogens such as Naegleria fowleri, Balamuthia mandrillaris, and the genera Sappinia and Acanthamoeba. In this study, a survey was conducted in order to evaluate the presence of potentially pathogenic amoebic strains in water samples collected from wells located in the western part of Guinea-Bissau. The samples were left to precipitate for 48 hours and then the sediments were seeded on non-nutrient agar plates containing Escherichia coli spread and cultures were checked daily for the presence of FLA. Identification of FLA strains was based on the morphological and polymerase chain reaction (PCR) using the 18S rDNA or 16S mitochondrial rDNA genes in the case of Naegleria and Balamuthia genera, respectively. In the case of positive samples of Acanthamoeba, strains were further classified at the genotype level by sequencing the diagnostic fragment 3 (DF3) region located in the 18S rDNA gene as previously described. Sappinia sp. was not isolated during the study and thus, no molecular analysis was performed for this genus. The obtained results revealed the presence of Acanthamoeba (genotypes T3 and T4), Naegleria fowleri, and Balamuthia mandrillaris. To the best of our knowledge, this is the first report demonstrating the presence of FLA in water bodies from Guinea-Bissau and the first report on the isolation of Balamuthia mandrillaris from environmental sources in Africa. PMID:24934796

  17. Screening of recreational areas of rivers for potentially pathogenic free-living amoebae in the suburbs of Tehran, Iran.

    Science.gov (United States)

    Niyyati, Maryam; Lasjerdi, Zohreh; Nazar, Mahdieh; Haghighi, Ali; Nazemalhosseini Mojarad, Ehsan

    2012-03-01

    A survey was conducted to determine the presence of free-living amoebae (FLA), especially Acanthamoeba and Naegleria, in river recreation areas in Tehran Province, Iran. All rivers surveyed were associated with human activity, and two were also a source of municipal tap water. Fifty-five water samples from 10 major rivers were screened for FLA and identified by morphological characters, PCR amplification targeting specific genes for Acanthamoeba (DF3 region of Rns gene) and other FLA (ITS PCR), and homology analysis. The percentage of positive FLA isolates was 27.3%, of which 80% were Acanthamoeba, assigned to the T4 and T15 genotype, and 20% were Naegleria. Isolation of Acanthamoeba T4 genotype (91.7%) from recreation areas could be a health threat and a sanitary risk associated with human activity where young people and tourists congregate in summer. Posting of warning signs and education of high-risk individuals are important for disease prevention. To the best of our knowledge this is the first report of genotype T15 (clustered with A. jacobsi) identified in Iran and the first report of the distribution of FLA such as Naegleria (N. pagei, N. clarki and N. fultoni) in recreation areas in rivers of Tehran Province using molecular methods.

  18. Environmental factors shaping cultured free-living amoebae and their associated bacterial community within drinking water network.

    Science.gov (United States)

    Delafont, Vincent; Bouchon, Didier; Héchard, Yann; Moulin, Laurent

    2016-09-01

    Free-living amoebae (FLA) constitute an important part of eukaryotic populations colonising drinking water networks. However, little is known about the factors influencing their ecology in such environments. Because of their status as reservoir of potentially pathogenic bacteria, understanding environmental factors impacting FLA populations and their associated bacterial community is crucial. Through sampling of a large drinking water network, the diversity of cultivable FLA and their bacterial community were investigated by an amplicon sequencing approach, and their correlation with physicochemical parameters was studied. While FLA ubiquitously colonised the water network all year long, significant changes in population composition were observed. These changes were partially explained by several environmental parameters, namely water origin, temperature, pH and chlorine concentration. The characterisation of FLA associated bacterial community reflected a diverse but rather stable consortium composed of nearly 1400 OTUs. The definition of a core community highlighted the predominance of only few genera, majorly dominated by Pseudomonas and Stenotrophomonas. Co-occurrence analysis also showed significant patterns of FLA-bacteria association, and allowed uncovering potentially new FLA - bacteria interactions. From our knowledge, this study is the first that combines a large sampling scheme with high-throughput identification of FLA together with associated bacteria, along with their influencing environmental parameters. Our results demonstrate the importance of physicochemical parameters in the ecology of FLA and their bacterial community in water networks.

  19. Presence of potentially pathogenic free-living amoebae strains from well water samples in Guinea-Bissau.

    Science.gov (United States)

    Baquero, Rocío A; Reyes-Batlle, María; Nicola, Graciela G; Martín-Navarro, Carmen M; López-Arencibia, Atteneri; Guillermo Esteban, J; Valladares, Basilio; Martínez-Carretero, Enrique; Piñero, José E; Lorenzo-Morales, Jacob

    2014-06-01

    Free-living amoebae (FLA) include opportunistic pathogens such as Naegleria fowleri, Balamuthia mandrillaris, and the genera Sappinia and Acanthamoeba. In this study, a survey was conducted in order to evaluate the presence of potentially pathogenic amoebic strains in water samples collected from wells located in the western part of Guinea-Bissau. The samples were left to precipitate for 48 hours and then the sediments were seeded on non-nutrient agar plates containing Escherichia coli spread and cultures were checked daily for the presence of FLA. Identification of FLA strains was based on the morphological and polymerase chain reaction (PCR) using the 18S rDNA or 16S mitochondrial rDNA genes in the case of Naegleria and Balamuthia genera, respectively. In the case of positive samples of Acanthamoeba, strains were further classified at the genotype level by sequencing the diagnostic fragment 3 (DF3) region located in the 18S rDNA gene as previously described. Sappinia sp. was not isolated during the study and thus, no molecular analysis was performed for this genus. The obtained results revealed the presence of Acanthamoeba (genotypes T3 and T4), Naegleria fowleri, and Balamuthia mandrillaris. To the best of our knowledge, this is the first report demonstrating the presence of FLA in water bodies from Guinea-Bissau and the first report on the isolation of Balamuthia mandrillaris from environmental sources in Africa.

  20. Systematic analysis of γ-aminobutyric acid (GABA) metabolism and function in the social amoeba Dictyostelium discoideum.

    Science.gov (United States)

    Wu, Yuantai; Janetopoulos, Chris

    2013-05-24

    While GABA has been suggested to regulate spore encapsulation in the social amoeba Dictyostelium discoideum, the metabolic profile and other potential functions of GABA during development remain unclear. In this study, we investigated the homeostasis of GABA metabolism by disrupting genes related to GABA metabolism and signaling. Extracellular levels of GABA are tightly regulated during early development, and GABA is generated by the glutamate decarboxylase, GadB, during growth and in early development. However, overexpression of the prespore-specific homologue, GadA, in the presence of GadB reduces production of extracellular GABA. Perturbation of extracellular GABA levels delays the process of aggregation. Cytosolic GABA is degraded by the GABA transaminase, GabT, in the mitochondria. Disruption of a putative vesicular GABA transporter (vGAT) homologue DdvGAT reduces secreted GABA. We identified the GABAB receptor-like family member GrlB as the major GABA receptor during early development, and either disruption or overexpression of GrlB delays aggregation. This delay is likely the result of an abolished pre-starvation response and late expression of several "early" developmental genes. Distinct genes are employed for GABA generation during sporulation. During sporulation, GadA alone is required for generating GABA and DdvGAT is likely responsible for GABA secretion. GrlE but not GrlB is the GABA receptor during late development.

  1. The TOM Complex of Amoebozoans: the Cases of the Amoeba Acanthamoeba castellanii and the Slime Mold Dictyostelium discoideum.

    Science.gov (United States)

    Wojtkowska, Małgorzata; Buczek, Dorota; Stobienia, Olgierd; Karachitos, Andonis; Antoniewicz, Monika; Slocinska, Małgorzata; Makałowski, Wojciech; Kmita, Hanna

    2015-07-01

    Protein import into mitochondria requires a wide variety of proteins, forming complexes in both mitochondrial membranes. The TOM complex (translocase of the outer membrane) is responsible for decoding of targeting signals, translocation of imported proteins across or into the outer membrane, and their subsequent sorting. Thus the TOM complex is regarded as the main gate into mitochondria for imported proteins. Available data indicate that mitochondria of representative organisms from across the major phylogenetic lineages of eukaryotes differ in subunit organization of the TOM complex. The subunit organization of the TOM complex in the Amoebozoa is still elusive, so we decided to investigate its organization in the soil amoeba Acanthamoeba castellanii and the slime mold Dictyostelium discoideum. They represent two major subclades of the Amoebozoa: the Lobosa and Conosa, respectively. Our results confirm the presence of Tom70, Tom40 and Tom7 in the A. castellanii and D. discoideum TOM complex, while the presence of Tom22 and Tom20 is less supported. Interestingly, the Tom proteins display the highest similarity to Opisthokonta cognate proteins, with the exception of Tom40. Thus representatives of two major subclades of the Amoebozoa appear to be similar in organization of the TOM complex, despite differences in their lifestyle. PMID:26074248

  2. Ubiquiter circovirus sequences raise challenges in laboratory diagnosis: the case of honey bee and bee mite, reptiles, and free living amoebae.

    Science.gov (United States)

    Marton, Szilvia; Ihász, Katalin; Lengyel, György; Farkas, Szilvia L; Dán, Ádám; Paulus, Petra; Bányai, Krisztián; Fehér, Enikő

    2015-03-01

    Circoviruses of pigs and birds are established pathogens, however, the exact role of other, recently described circoviruses and circovirus-like viruses remains to be elucidated. The aim of this study was the detection of circoviruses in neglected host species, including honey bees, exotic reptiles and free-living amoebae by widely used broad-spectrum polymerase chain reaction (PCR) assays specific for the replication initiation protein coding gene of these viruses. The majority of sequences obtained from honey bees were highly similar to canine and porcine circoviruses, or, were distantly related to dragonfly cycloviruses. Other rep sequences detected in some honey bees, reptiles and amoebae showed similarities to various rep sequences deposited in the GenBank. Back-to-back PCR primers designed for the amplification of whole viral genomes failed to work that suggested the existence of integrated rep-like elements in many samples. Rolling circle amplification and exonuclease treatment confirmed the absence of small circular DNA genomes in the specimens analysed. In case of honey bees Varroa mite DNA contamination might be a source of the identified endogenous rep-like elements. The reptile and amoebae rep-like sequences were nearly identical with each other and with sequences detected in chimpanzee feces raising the possibility that detection of novel or unusual rep-like elements in some host species might originate from the microbial community of the host. Our results indicate that attention is needed when broad-spectrum rep gene specific polymerase chain reaction is chosen for laboratory diagnosis of circovirus infections.

  3. Isolation and identification of pathogenic free-living amoeba from surface and tap water of Shiraz City using morphological and molecular methods.

    Science.gov (United States)

    Armand, B; Motazedian, M H; Asgari, Q

    2016-01-01

    Free-living amoebae (FLA) are the most abundant and widely distributed protozoa in the environment. An investigation was conducted to determine the presence of free-living amoebae (FLA), Acanthamoeba and Vermamoeba in waterfronts of parks and squares and tap water of Shiraz City, Iran. FLA are considered pathogenic for human. These ubiquitous organisms have been isolated from different environments such as water, soil, and air. Eighty-two water samples were collected from different places of Shiraz City during the summer of 2013. All samples were processed in Dept. of Parasitology and Mycology, Shiraz University of Medical Sciences, Fars, Iran. Samples were screened for FLA and identified by morphological characters in the cultures, PCR amplification targeting specific genes for each genus and sequencing determined frequent species and genotypes base on NCBI database. Overall, 48 samples were positive for Acanthamoeba and Vermamoeba in non-nutrient agar culture based on morphological characteristics. The PCR examination was done successfully. Sequencing results were revealed T4 (62.96 %) genotypes as the most common genotype of Acanthamoeba in the Shiraz water sources. In addition, T5 (33.33 %) and T15 (3.71 %) were isolated from water supplies. Vermamoeba vermiformis was known the dominant species from this genus. The high frequency of Acanthamoeba spp. and Vermamoeba in different environmental water sources of Shiraz is an alert for the public health related to water sources. The result highlights a need for taking more attention to water supplies in order to prevent illnesses related to free-living amoebae.

  4. Ubiquiter circovirus sequences raise challenges in laboratory diagnosis: the case of honey bee and bee mite, reptiles, and free living amoebae.

    Science.gov (United States)

    Marton, Szilvia; Ihász, Katalin; Lengyel, György; Farkas, Szilvia L; Dán, Ádám; Paulus, Petra; Bányai, Krisztián; Fehér, Enikő

    2015-03-01

    Circoviruses of pigs and birds are established pathogens, however, the exact role of other, recently described circoviruses and circovirus-like viruses remains to be elucidated. The aim of this study was the detection of circoviruses in neglected host species, including honey bees, exotic reptiles and free-living amoebae by widely used broad-spectrum polymerase chain reaction (PCR) assays specific for the replication initiation protein coding gene of these viruses. The majority of sequences obtained from honey bees were highly similar to canine and porcine circoviruses, or, were distantly related to dragonfly cycloviruses. Other rep sequences detected in some honey bees, reptiles and amoebae showed similarities to various rep sequences deposited in the GenBank. Back-to-back PCR primers designed for the amplification of whole viral genomes failed to work that suggested the existence of integrated rep-like elements in many samples. Rolling circle amplification and exonuclease treatment confirmed the absence of small circular DNA genomes in the specimens analysed. In case of honey bees Varroa mite DNA contamination might be a source of the identified endogenous rep-like elements. The reptile and amoebae rep-like sequences were nearly identical with each other and with sequences detected in chimpanzee feces raising the possibility that detection of novel or unusual rep-like elements in some host species might originate from the microbial community of the host. Our results indicate that attention is needed when broad-spectrum rep gene specific polymerase chain reaction is chosen for laboratory diagnosis of circovirus infections. PMID:25823454

  5. Defects in the synthetic pathway prevent DIF-1 mediated stalk lineage specification cascade in the non-differentiating social amoeba, Acytostelium subglobosum

    Directory of Open Access Journals (Sweden)

    Kurato Mohri

    2014-05-01

    Full Text Available Separation of somatic cells from germ-line cells is a crucial event for multicellular organisms, but how this step was achieved during evolution remains elusive. In Dictyostelium discoideum and many other dictyostelid species, solitary amoebae gather and form a multicellular fruiting body in which germ-line spores and somatic stalk cells differentiate, whereas in Acytostelium subglobosum, acellular stalks form and all aggregated amoebae become spores. In this study, because most D. discoideum genes known to be required for stalk cell differentiation have homologs in A. subglobosum, we inferred functional variations in these genes and examined conservation of the stalk cell specification cascade of D. discoideum mediated by the polyketide differentiation-inducing factor-1 (DIF-1 in A. subglobosum. Through heterologous expression of A. subglobosum orthologs of DIF-1 biosynthesis genes in D. discoideum, we confirmed that two of the three genes were functional equivalents, while DIF-methyltransferase (As-dmtA involved at the final step of DIF-1 synthesis was not. In fact, DIF-1 activity was undetectable in A. subglobosum lysates and amoebae of this species were not responsive to DIF-1, suggesting a lack of DIF-1 production in this species. On the other hand, the molecular function of an A. subglobosum ortholog of DIF-1 responsive transcription factor was equivalent with that of D. discoideum and inhibition of polyketide synthesis caused developmental arrest in A. subglobosum, which could not be rescued by DIF-1 addition. These results suggest that non-DIF-1 polyketide cascades involving downstream transcription factors are required for fruiting body development of A. subglobosum.

  6. Temporal and non-permanent division of labor during sorocarp formation in the social amoeba Acytostelium subglobosum.

    Science.gov (United States)

    Mohri, Kurato; Kiyota, Yu; Kuwayama, Hidekazu; Urushihara, Hideko

    2013-03-15

    Somatic cell differentiation is crucial for the development of multicellular organisms. While the development of a fruiting body in Dictyostelium discoideum represents a simple model of this process with separation of stalk cells from the spore lineage, that of Acytostelium subglobosum is not accompanied by cell type separation. This species produces acellular stalks and, seemingly, all aggregated amoebae become spores; however, it possesses homologs for the stalk-cell marker genes of D. discoideum. In this study, we analyzed the spatio-temporal expression of A. subglobosum orthologs for D. discoideum stalk- or spore-lineage markers to clarify the developmental process of A. subglobosum. We first found that the prespore vesicles, which contained spore coat proteins, started to accumulate in the tip region and were observed in the entire sorogen throughout later development, confirming that all A. subglobosum cells became spores. The expression of a stalk-lineage gene ortholog, As-ecmA, started at the mound stage and was prominent in the protruding sorogen. Although two spore-lineage gene orthologs, As-cotD1 and -cotD2, were likewise detected shortly after cell aggregation and increased in intensity until tip formation, their expression diminished in the protruding sorogen. Double-fluorescence staining of these prestalk and prespore marker genes revealed that the expression of these marker genes was mutually exclusive and that expression switching occurred in the early tip. Our results indicate that A. subglobosum cells become committed to the spore lineage first, and then, while keeping this commitment intact, participate in stalk formation. Instead of the permanent division of labor observed in D. discoideum, A. subglobosum produces fruiting bodies by all cells contributing to the formation of the stalk as well as forming spores.

  7. Whole genome sequencing of mutation accumulation lines reveals a low mutation rate in the social amoeba Dictyostelium discoideum.

    Directory of Open Access Journals (Sweden)

    Gerda Saxer

    Full Text Available Spontaneous mutations play a central role in evolution. Despite their importance, mutation rates are some of the most elusive parameters to measure in evolutionary biology. The combination of mutation accumulation (MA experiments and whole-genome sequencing now makes it possible to estimate mutation rates by directly observing new mutations at the molecular level across the whole genome. We performed an MA experiment with the social amoeba Dictyostelium discoideum and sequenced the genomes of three randomly chosen lines using high-throughput sequencing to estimate the spontaneous mutation rate in this model organism. The mitochondrial mutation rate of 6.76×10(-9, with a Poisson confidence interval of 4.1×10(-9 - 9.5×10(-9, per nucleotide per generation is slightly lower than estimates for other taxa. The mutation rate estimate for the nuclear DNA of 2.9×10(-11, with a Poisson confidence interval ranging from 7.4×10(-13 to 1.6×10(-10, is the lowest reported for any eukaryote. These results are consistent with low microsatellite mutation rates previously observed in D. discoideum and low levels of genetic variation observed in wild D. discoideum populations. In addition, D. discoideum has been shown to be quite resistant to DNA damage, which suggests an efficient DNA-repair mechanism that could be an adaptation to life in soil and frequent exposure to intracellular and extracellular mutagenic compounds. The social aspect of the life cycle of D. discoideum and a large portion of the genome under relaxed selection during vegetative growth could also select for a low mutation rate. This hypothesis is supported by a significantly lower mutation rate per cell division in multicellular eukaryotes compared with unicellular eukaryotes.

  8. Amoeba-based computing for traveling salesman problem: long-term correlations between spatially separated individual cells of Physarum polycephalum.

    Science.gov (United States)

    Zhu, Liping; Aono, Masashi; Kim, Song-Ju; Hara, Masahiko

    2013-04-01

    A single-celled, multi-nucleated amoeboid organism, a plasmodium of the true slime mold Physarum polycephalum, can perform sophisticated computing by exhibiting complex spatiotemporal oscillatory dynamics while deforming its amorphous body. We previously devised an "amoeba-based computer (ABC)" to quantitatively evaluate the optimization capability of the amoeboid organism in searching for a solution to the traveling salesman problem (TSP) under optical feedback control. In ABC, the organism changes its shape to find a high quality solution (a relatively shorter TSP route) by alternately expanding and contracting its pseudopod-like branches that exhibit local photoavoidance behavior. The quality of the solution serves as a measure of the optimality of which the organism maximizes its global body area (nutrient absorption) while minimizing the risk of being illuminated (exposure to aversive stimuli). ABC found a high quality solution for the 8-city TSP with a high probability. However, it remains unclear whether intracellular communication among the branches of the organism is essential for computing. In this study, we conducted a series of control experiments using two individual cells (two single-celled organisms) to perform parallel searches in the absence of intercellular communication. We found that ABC drastically lost its ability to find a solution when it used two independent individuals. However, interestingly, when two individuals were prepared by dividing one individual, they found a solution for a few tens of minutes. That is, the two divided individuals remained correlated even though they were spatially separated. These results suggest the presence of a long-term memory in the intrinsic dynamics of this organism and its significance in performing sophisticated computing. PMID:23438635

  9. Amoeba-inspired Tug-of-War algorithms for exploration-exploitation dilemma in extended Bandit Problem.

    Science.gov (United States)

    Aono, Masashi; Kim, Song-Ju; Hara, Masahiko; Munakata, Toshinori

    2014-03-01

    The true slime mold Physarum polycephalum, a single-celled amoeboid organism, is capable of efficiently allocating a constant amount of intracellular resource to its pseudopod-like branches that best fit the environment where dynamic light stimuli are applied. Inspired by the resource allocation process, the authors formulated a concurrent search algorithm, called the Tug-of-War (TOW) model, for maximizing the profit in the multi-armed Bandit Problem (BP). A player (gambler) of the BP should decide as quickly and accurately as possible which slot machine to invest in out of the N machines and faces an "exploration-exploitation dilemma." The dilemma is a trade-off between the speed and accuracy of the decision making that are conflicted objectives. The TOW model maintains a constant intracellular resource volume while collecting environmental information by concurrently expanding and shrinking its branches. The conservation law entails a nonlocal correlation among the branches, i.e., volume increment in one branch is immediately compensated by volume decrement(s) in the other branch(es). Owing to this nonlocal correlation, the TOW model can efficiently manage the dilemma. In this study, we extend the TOW model to apply it to a stretched variant of BP, the Extended Bandit Problem (EBP), which is a problem of selecting the best M-tuple of the N machines. We demonstrate that the extended TOW model exhibits better performances for 2-tuple-3-machine and 2-tuple-4-machine instances of EBP compared with the extended versions of well-known algorithms for BP, the ϵ-Greedy and SoftMax algorithms, particularly in terms of its short-term decision-making capability that is essential for the survival of the amoeba in a hostile environment. PMID:24384066

  10. Characterization of Selenaion koniopes n. gen., n. sp., an amoeba that represents a new major lineage within heterolobosea, isolated from the Wieliczka salt mine.

    Science.gov (United States)

    Park, Jong Soo; De Jonckheere, Johan F; Simpson, Alastair G B

    2012-01-01

    A new heterolobosean amoeba, Selenaion koniopes n. gen., n. sp., was isolated from 73‰ saline water in the Wieliczka salt mine, Poland. The amoeba had eruptive pseudopodia, a prominent uroid, and a nucleus without central nucleolus. Cysts had multiple crater-like pore plugs. No flagellates were observed. Transmission electron microscopy revealed several typical heterolobosean features: flattened mitochondrial cristae, mitochondria associated with endoplasmic reticulum, and an absence of obvious Golgi dictyosomes. Two types of larger and smaller granules were sometimes abundant in the cytoplasm--these may be involved in cyst formation. Mature cysts had a fibrous endocyst that could be thick, plus an ectocyst that was covered with small granules. Pore plugs had a flattened dome shape, were bipartite, and penetrated only the endocyst. Phylogenies based on the 18S rRNA gene and the presence of 18S rRNA helix 17_1 strongly confirmed assignment to Heterolobosea. The organism was not closely related to any described genus, and instead formed the deepest branch within the Heterolobosea clade after Pharyngomonas, with support for this deep-branching position being moderate (i.e. maximum likelihood bootstrap support--67%; posterior probability--0.98). Cells grew at 15-150‰ salinity. Thus, S. koniopes is a halotolerant, probably moderately halophilic heterolobosean, with a potentially pivotal evolutionary position within this large eukaryote group.

  11. A Record of Moisture History in Hawaii since the Arrival of Humans Inferred from Testate Amoebae and Cladocera Fossils Preserved in Bog Sediments

    Science.gov (United States)

    Barrett, K.; Kim, S. H.; Hotchkiss, S.

    2015-12-01

    Around AD 800, Polynesians arrived on the Hawaiian Islands where they expanded and intensified distinct agricultural practices in the islands' wet and dry regions. Dryland farming productivity in particular would have been sensitive to atmospheric rearrangements of the ENSO and PDO systems that affect rainfall in Hawaii. The few detailed terrestrial paleoclimate records in Hawaii are mainly derived from vegetation proxies (e.g. pollen, seeds, fruits, and plant biomarkers) which are heavily influenced by widespread landscape modification following human arrival. Here we present initial results of an independent paleomoisture proxy: fossil remains of moisture-sensitive testate amoebae (Protozoa: Rhizopoda) and cladocera (water fleas) preserved in continuous bog sediments on Kohala Volcano uplsope of the ancient Kohala agricultural field system, one of the largest dryland field systems in Hawaii. Hydrologic conditions inferred from testate amoebae and cladoceran fossil assemblages correlate with observed decadal moisture regimes in Hawaii and state changes of the PDO system during the last century. Testate ameoabe and cladoceran fossils in older sediments reveal an alternating history of very wet, lake-forming conditions on the bog surface to periods when bog soils were much drier than today's, demonstrating that this method can be paired with vegetation proxies to provide a better understanding of hydroclimate variability in prehistoric Hawaii.

  12. 187-gene phylogeny of protozoan phylum Amoebozoa reveals a new class (Cutosea) of deep-branching, ultrastructurally unique, enveloped marine Lobosa and clarifies amoeba evolution.

    Science.gov (United States)

    Cavalier-Smith, Thomas; Chao, Ema E; Lewis, Rhodri

    2016-06-01

    Monophyly of protozoan phylum Amoebozoa, and subdivision into subphyla Conosa and Lobosa each with different cytoskeletons, are well established. However early diversification of non-ciliate lobose amoebae (Lobosa) is poorly understood. To clarify it we used recently available transcriptomes to construct a 187-gene amoebozoan tree for 30 species, the most comprehensive yet. This robustly places new genus Atrichosa (formerly lumped with Trichosphaerium) within lobosan class Tubulinea, not Discosea as previously supposed. We identified an earliest diverging lobosan clade comprising marine amoebae armoured by porose scaliform cell-envelopes, here made a novel class Cutosea with two pseudopodially distinct new families. Cutosea comprise Sapocribrum, ATCC PRA-29 misidentified as 'Pessonella', plus from other evidence Squamamoeba. We confirm that Acanthamoeba and ATCC 50982 misidentified as Stereomyxa ramosa are closely related. Discosea have a strongly supported major subclade comprising Thecamoebida plus Glycostylida (suborders Dactylopodina, Stygamoebina; Vannellina) phylogenetically distinct from Centramoebida. Stygamoeba is sister to Dactylopodina. Himatismenida are either sister to Centramoebida or deeper branching. Discosea usually appear holophyletic (rarely paraphyletic). Paramoeba transcriptomes include prokinetoplastid Perkinsela-like endosymbiont sequences. Cunea, misidentified as Mayorella, is closer to Paramoeba than Vexillifera within holophyletic Dactylopodina. Taxon-rich site-heterogeneous rDNA trees confirm cutosan distinctiveness, allow improved conosan taxonomy, and reveal previous dictyostelid tree misrooting. PMID:27001604

  13. Effects of temporally persistent ant nests of soil protozoan communities and the abundance of morphological types of amoeba

    Science.gov (United States)

    We compared soil protozoan communities near ant nests with soil protozoans in reference soils 5m from the edge of any mounds. We sampled three species of Chihuahuan Desert ants that construct nests that persist for more than a decade: a seed harvester, Pogonomymex rugosus, a liquid feeding honey-po...

  14. [i]Legionella spp[/i]., amoebae and not-fermenting Gram negative bacteria in an Italian university hospital water system

    Directory of Open Access Journals (Sweden)

    Pasqualina Laganà

    2014-09-01

    Full Text Available [b]Introduction. [/b]In hospital and other health care facilities, contamination of water systems by potentially infectious microorganisms, such as bacteria, viruses and protozoa, is a source of nosocomial infections, which may originate fromcolonization of water pipes, cooling towers, spa pools, taps, showers and water supplies. [b]Objective. [/b]The study focuses on the occurrence of [i]Legionella spp.[/i], free-living amoebae and non-fermenting Gram-negative microorganisms in a University hospital water system located in the town of Messina (Sicily, Italy, which had never been examined previously. Materials and Methods. From January 2008 – March 2009, hot tap water samples were collected from 10 wards.[i] Legionella spp[/i]. recovered on selective culture medium were identified by microagglutination latex test; free-living amoebae were cultured using [i]Escherichia coli [/i]as a food source. Non-fermenting Gram negative microorganisms were identified by API 20 NE strips. [b]Results.[/b] [i]Legionella spp.[/i] were found in 33.33% of the samples. [i]L. pneumophila[/i] serogroup 1 was recovered from the Laboratory Diagnostic and Anaesthesia-Neurology Wards, with a peak of 3.5 × 10[sup]4[/sup] cfu/L in May 2008. [i]L. pneumophila[/i] serogroups 2–14 were found in the Othorhinolaryngology, Pathologic Anatomy, Paediatrics and Surgery Wards, and peaked (4 × 10[sup]4[/sup] cfu/L in April 2008. Pseudomonadaceae and Hyphomycetes were also detected. Legionella spp. were recovered from samples positive for non-pathogenic amoebae [i]Hartmannella spp[/i]. [b]Conclusion.[/b] This first study of a Messina hospital water system suggested potential health risks related to the detection of [i]Hartmannella spp[/i]., as reservoirs for[i] Legionella spp.[/i], and Pseudomonas aeruginosa, a Gram negative non-fermenting bacterium frequently causing nosocomial pneumonia. The urgent need for monitoring programmes and prevention measures to ensure hospital water

  15. Species richness of testate amoebae in different environments from the upper Paraná river floodplain (PR/MS - doi: 10.4025/actascibiolsci.v33i3.7261 Species richness of testate amoebae in different environments from the upper Paraná river floodplain (PR/MS - doi: 10.4025/actascibiolsci.v33i3.7261

    Directory of Open Access Journals (Sweden)

    Fábio Amodêo Lansac-Tôha

    2011-07-01

    Full Text Available This study evaluated the species richness of testate amoebae in the plankton from different environments of the upper Paraná river floodplain. Samplings were performed at subsurface of pelagic region from twelve environments using motorized pump and plankton net (68 µm, during four hydrological periods. We identified 67 taxa, distributed in seven families and Arcellidae, Difflugiidae and Centropyxidae were the most representative families. Higher values of species richness were observed in the lakes (connected and isolated during the flood pulses. Centropyxis aculeata, Difflugia gramem and D. pseudogramem were frequent throughout the study period. Seasonal variability of species in the channels and isolated lakes was evidenced by beta diversity. Besides that, in the rivers, extreme changes in species composition were verified during the high-water period. Our results highlight the importance of the present study to improve the knowledge about the diversity and geographic distribution of these organisms in Brazil and emphasize the importance of current flow in the displacement of testate amoebae from their preferred habitats, marginal vegetation and sediment.This study evaluated the species richness of testate amoebae in the plankton from different environments of the upper Paraná river floodplain. Samplings were performed at subsurface of pelagic region from twelve environments using motorized pump and plankton net (68 µm, during four hydrological periods. We identified 67 taxa, distributed in seven families and Arcellidae, Difflugiidae and Centropyxidae were the most representative families. Higher values of species richness were observed in the lakes (connected and isolated during the flood pulses. Centropyxis aculeata, Difflugia gramem and D. pseudogramem were frequent throughout the study period. Seasonal variability of species in the channels and isolated lakes was evidenced by beta diversity. Besides that, in the rivers, extreme

  16. Immunity to amoeba.

    Science.gov (United States)

    Nowak, Barbara; Valdenegro-Vega, Victoria; Crosbie, Philip; Bridle, Andrew

    2014-04-01

    Amoebic infections in fish are most likely underestimated and sometimes overlooked due to the challenges associated with their diagnosis. Amoebic diseases reported in fish affect either gills or internal organs or may be systemic. Host response ranges from hyperplastic response in gill infections to inflammation (including granuloma formation) in internal organs. This review focuses on the immune response of Atlantic salmon to Neoparamoeba perurans, the causative agent of Amoebic Gill Disease (AGD).

  17. Amoebae Anticipate Periodic Events

    Science.gov (United States)

    Saigusa, Tetsu; Tero, Atsushi; Nakagaki, Toshiyuki; Kuramoto, Yoshiki

    2008-01-01

    When plasmodia of the true slime mold Physarum were exposed to unfavorable conditions presented as three consecutive pulses at constant intervals, they reduced their locomotive speed in response to each episode. When the plasmodia were subsequently subjected to favorable conditions, they spontaneously reduced their locomotive speed at the time when the next unfavorable episode would have occurred. This implied the anticipation of impending environmental change. We explored the mechanisms underlying these types of behavior from a dynamical systems perspective.

  18. The Bionic Amoeba.

    Science.gov (United States)

    Wright, Emmett L.

    1979-01-01

    A demonstration is described that encourages students to engage in inquiry in biology. Using chemicals and an overhead projector, the instructor can simulate a living organism projected onto a screen. The reaction can aid students in defining the characteristics of life. (SA)

  19. Structure of microbial communities in Sphagnum peatlands and effect of atmospheric carbon dioxide enrichment.

    Science.gov (United States)

    Mitchell, E A D; Gilbert, D; Buttler, A; Amblard, C; Grosvernier, P; Gobat, J M

    2003-08-01

    Little is known about the structure of microbial communities in Sphagnum peatlands, and the potential effects of the increasing atmospheric CO2 concentration on these communities are not known. We analyzed the structure of microbial communities in five Sphagnum-dominated peatlands across Europe and their response to CO2 enrichment using miniFACE systems. After three growing seasons, Sphagnum samples were analyzed for heterotrophic bacteria, cyanobacteria, microalgae, heterotrophic flagellates, ciliates, testate amoebae, fungi, nematodes, and rotifers. Heterotrophic organisms dominated the microbial communities and together represented 78% to 97% of the total microbial biomass. Testate amoebae dominated the protozoan biomass. A canonical correspondence analysis revealed a significant correlation between the microbial community data and four environmental variables (Na+, DOC, water table depth, and DIN), reflecting continentality, hydrology, and nitrogen deposition gradients. Carbon dioxide enrichment modified the structure of microbial communities, but total microbial biomass was unaffected. The biomass of heterotrophic bacteria increased by 48%, and the biomass of testate amoebae decreased by 13%. These results contrast with the absence of overall effect on methane production or on the vegetation, but are in line with an increased below-ground vascular plant biomass at the same sites. We interpret the increase in bacterial biomass as a response to a CO2-induced enhancement of Sphagnum exudation. The causes for the decrease of testate amoebae are unclear but could indicate a top-down rather than a bottom-up control on their density.

  20. Detection of the free living amoeba Naegleria fowleri by using conventional and real-time PCR based on a single copy DNA sequence.

    Science.gov (United States)

    Régoudis, Estelle; Pélandakis, Michel

    2016-02-01

    The amoeba-flagellate Naegleria fowleri is a causative agent of primary amoebic meningoencephalitis (PAM). This thermophilic species occurs worldwide and tends to proliferate in warm aquatic environment. The PAM cases remain rare but this infection is mostly fatal. Here, we describe a single copy region which has been cloned and sequenced, and was used for both conventional and real-time PCR. Targeting a single-copy DNA sequence allows to directly quantify the N. fowleri cells. The real-time PCR results give a detection limit of 1 copy per reaction with high reproducibility without the need of a Taqman probe. This procedure is of interest as compared to other procedures which are mostly based on the detection of multi-copy DNA associated with a Taqman probe.

  1. Separate Culture and Morphological Observation of Free Living Amoebae and Ciliates%自生阿米巴和纤毛虫的分离培养与观察

    Institute of Scientific and Technical Information of China (English)

    岳爱梅; 刘营; 谭叶; 丛慧; 林佳慧; 张英杰; 张忠广

    2013-01-01

    Objective To study the methods of cultivation and morphological observation of free living amoebae and ciliates and observe the growth and species change of parasites in different time and vegetables. Methods Various green vegetable juice were prepared for cultivating the amoebae and ciliates at 37℃ The growth of free living amoebae and ciliates were observed using microscope. Results Rotary motion of ciliates was observed after cultivation for 48 hours.Decreased quantity and activity of ciliates and increased quantity and activity of free living amoebae were observed after cultivation for 72 hours. Decreased quantity of free living amoebae and ciliates were observed even disappeared but the cysts appeared after cultivation for 144 hours. And various green vegetable juice showed differences in culturing the amoebae and ciliates; between 72 h to 120 h ciliates could be found in celery juice, while free living amoebae were found between 96 h to 120 h. Ciliates could be easier to observe in rape flower juice between 72 h to 96h and free living amoebae easier to see in caraway juice between 72 h to 120 h. Conclusion This method is simple and convenient to observe the living amoebae and ciliates. It is useful in the parasitology teaching.%目的 研究建立自生阿米巴和纤毛虫的培养方法,观察不同菜种在不同时间寄生虫的生长情况及种类的变化.方法 制作不同蔬菜叶的悬液,37℃恒温培养,镜下观察不同时间自生阿米巴和纤毛虫的生长情况.结果 培养48 h后,可观察到纤毛虫活跃的旋转运动;72 h后纤毛虫数量减少,活动度降低,自生阿米巴出现,蠕动活跃;144 h后自生阿米巴、纤毛虫数量减少甚至观察不到,包囊出现,不同菜种在不同时间自生阿米巴、纤毛虫数量、种类也相应变化,如芹菜中纤毛虫在72~120 h、阿米巴在96~120 h数量最多,最易观察到,油菜中纤毛虫在72~96 h最易观察到,香菜中阿米巴在72~120 h

  2. Soil microbial toxicity of eight polycyclic aromatic compounds: effects on nitrification, the genetic diversity of bacteria, and the total number of protozoans

    DEFF Research Database (Denmark)

    Sverdrup, Line Emilie; Ekelund, Flemming; Krogh, Paul Henning;

    2002-01-01

    Eight polycyclic aromatic compounds (PACs) were tested for their toxic effect on the soil nitrification process, bacterial genetic diversity, and the total number of protozoans (naked amoebae and heterotrophic flagellates). After four weeks of exposure in a well-characterized agricultural soil...

  3. Evolution of stalk/spore ratio in a social amoeba: cell-to-cell interaction via a signaling chemical shaped by cheating risk.

    Science.gov (United States)

    Uchinomiya, Kouki; Iwasa, Yoh

    2013-11-01

    The social amoeba (or cellular slime mold) is a model system for cell cooperation. When food is depleted in the environment, cells aggregate together. Some of these cells become stalks, raising spores to aid in their dispersal. Differentiation-inducing factor-1 (DIF-1) is a signaling chemical produced by prespore cells and decomposed by prestalk cells. It affects the rate of switching between prestalk and prespore cells, thereby achieving a stable stalk/spore ratio. In this study we analyzed the evolution of the stalk/spore ratio. Strains may differ in the production and decomposition rates of the signaling chemical, and in the sensitivity of cells to switch in response to the signaling chemical exposure. When two strains with the same stalk/spore ratio within their own fruiting body are combined into a single fruiting body, one strain may develop into prespores to a greater degree than the other. Direct evolutionary simulations and quantitative genetic dynamics demonstrate that if a fruiting body is always formed by a single strain, the cells evolve to produce less signaling chemical and become more sensitive to the signaling chemical due to the cost of producing the chemical. In contrast, if a fruiting body is formed by multiple strains, the cells evolve to become less sensitive to the signaling chemical and produce more signaling chemical in order to reduce the risk of being exploited. In contrast, the stalk-spore ratio is less likely to be affected by small cheating risk.

  4. DESCRIPTIONS OF FIVE NEW RECORDS OF TESTATE AMOEBAE (PROTOZOA) FROM CHINA%中国有壳肉足虫(原生动物)五新纪录描述

    Institute of Scientific and Technical Information of China (English)

    张文静; 杨军; 沈韫芬

    2009-01-01

    Five testate amoebae taxa, which were first recorded in China, were investigated by light microscopy. These taxa are Arcella artocrea aplanata Grospietsch, 1954, A. costata angulosa (Perty) Playfair, 1918, A. discoides pseudovulgaris Deflandre, 1928, A. gibbosa laevis Deflandre, 1928 and Difflugia gramen globulosa Stěpánek et Jiriek et Jirí, 1958.%描述了采自云南、湖北和广东的5种有壳肉足虫,隶属原生动物亚界,肉鞭门,叶足纲,表壳目,均为国内新纪录种:非游巧装表壳虫Arcella artocrtea aplanata Grospietsch,1954;具角肋表壳虫A.costata angulosa (Perty) Playfair,1918;拟普通盘状表壳虫A.discoides pseudovulgaris Deflandre ,1928;光滑弯凸表壳虫A.gibbosa laevis Deflandre ,1928;球形叉口砂壳虫Difflugia gramen globulosa Stěpánek et Jirí,1958.

  5. Cooccurrence of free-living amoebae and nontuberculous Mycobacteria in hospital water networks, and preferential growth of Mycobacterium avium in Acanthamoeba lenticulata.

    Science.gov (United States)

    Ovrutsky, Alida R; Chan, Edward D; Kartalija, Marinka; Bai, Xiyuan; Jackson, Mary; Gibbs, Sara; Falkinham, Joseph O; Iseman, Michael D; Reynolds, Paul R; McDonnell, Gerald; Thomas, Vincent

    2013-05-01

    The incidence of lung and other diseases due to nontuberculous mycobacteria (NTM) is increasing. NTM sources include potable water, especially in households where NTM populate pipes, taps, and showerheads. NTM share habitats with free-living amoebae (FLA) and can grow in FLA as parasites or as endosymbionts. FLA containing NTM may form cysts that protect mycobacteria from disinfectants and antibiotics. We first assessed the presence of FLA and NTM in water and biofilm samples collected from a hospital, confirming the high prevalence of NTM and FLA in potable water systems, particularly in biofilms. Acanthamoeba spp. (genotype T4) were mainly recovered (8/17), followed by Hartmannella vermiformis (7/17) as well as one isolate closely related to the genus Flamella and one isolate only distantly related to previously described species. Concerning mycobacteria, Mycobacterium gordonae was the most frequently found isolate (9/17), followed by Mycobacterium peregrinum (4/17), Mycobacterium chelonae (2/17), Mycobacterium mucogenicum (1/17), and Mycobacterium avium (1/17). The propensity of Mycobacterium avium hospital isolate H87 and M. avium collection strain 104 to survive and replicate within various FLA was also evaluated, demonstrating survival of both strains in all amoebal species tested but high replication rates only in Acanthamoeba lenticulata. As A. lenticulata was frequently recovered from environmental samples, including drinking water samples, these results could have important consequences for the ecology of M. avium in drinking water networks and the epidemiology of disease due to this species.

  6. Coprophilic amoebae and flagellates, including Guttulinopsis, Rosculus and Helkesimastix, characterise a divergent and diverse rhizarian radiation and contribute to a large diversity of faecal-associated protists.

    Science.gov (United States)

    Bass, David; Silberman, Jeffrey D; Brown, Matthew W; Pearce, Rebecca A; Tice, Alexander K; Jousset, Alexandre; Geisen, Stefan; Hartikainen, Hanna

    2016-05-01

    A wide diversity of organisms utilize faecal habitats as a rich nutrient source or a mechanism to traverse through animal hosts. We sequenced the 18S rRNA genes of the coprophilic, fruiting body-forming amoeba Guttulinopsis vulgaris and its non-fruiting relatives Rosculus 'ithacus' CCAP 1571/3, R. terrestris n. sp. and R. elongata n. sp. and demonstrate that they are related to the coprophilic flagellate Helkesimastix in a strongly supported, but highly divergent 18S sister clade. PCR primers specific to both clades were used to generate 18S amplicons from a range of environmental and faecal DNA samples. Phylogenetic analysis of the cloned sequences demonstrated a high diversity of uncharacterised sequence types within this clade, likely representing previously described members of the genera Guttulinopsis, Rosculus and Helkesimastix, as well as so-far unobserved organisms. Further, an Illumina MiSeq sequenced set of 18S V4-region amplicons generated from faecal DNAs using universal eukaryote primers showed that core-cercozoan assemblages in faecal samples are as diverse as those found in more conventionally examined habitats. These results reveal many novel lineages, some of which appear to occur preferentially in faecal material, in particular cercomonads and glissomonads. More broadly, we show that faecal habitats are likely untapped reservoirs of microbial eukaryotic diversity.

  7. Evolution of stalk/spore ratio in a social amoeba: cell-to-cell interaction via a signaling chemical shaped by cheating risk.

    Science.gov (United States)

    Uchinomiya, Kouki; Iwasa, Yoh

    2013-11-01

    The social amoeba (or cellular slime mold) is a model system for cell cooperation. When food is depleted in the environment, cells aggregate together. Some of these cells become stalks, raising spores to aid in their dispersal. Differentiation-inducing factor-1 (DIF-1) is a signaling chemical produced by prespore cells and decomposed by prestalk cells. It affects the rate of switching between prestalk and prespore cells, thereby achieving a stable stalk/spore ratio. In this study we analyzed the evolution of the stalk/spore ratio. Strains may differ in the production and decomposition rates of the signaling chemical, and in the sensitivity of cells to switch in response to the signaling chemical exposure. When two strains with the same stalk/spore ratio within their own fruiting body are combined into a single fruiting body, one strain may develop into prespores to a greater degree than the other. Direct evolutionary simulations and quantitative genetic dynamics demonstrate that if a fruiting body is always formed by a single strain, the cells evolve to produce less signaling chemical and become more sensitive to the signaling chemical due to the cost of producing the chemical. In contrast, if a fruiting body is formed by multiple strains, the cells evolve to become less sensitive to the signaling chemical and produce more signaling chemical in order to reduce the risk of being exploited. In contrast, the stalk-spore ratio is less likely to be affected by small cheating risk. PMID:23911583

  8. Effect of phosphatidylcholine-cholesterol liposomes on Entamoeba histolytica virulence.

    Science.gov (United States)

    Serrano-Luna, Jesús; Gutiérrez-Meza, Manuel; Mejía-Zepeda, Ricardo; Galindo-Gómez, Silvia; Tsutsumi, Víctor; Shibayama, Mineko

    2010-12-01

    Trophozoites of Entamoeba histolytica HM-1:IMSS become less virulent after long-term maintenance in axenic cultures. The factors responsible for the loss of virulence during in vitro cultivation remain unclear. However, it is known that in vitro cultivation of amoeba in culture medium supplemented with cholesterol restores their virulence. In this study, we analyzed the effect of adding phosphatidylcholine-cholesterol (PC-Chol) liposomes to the culture medium and evaluated the effect of this lipid on various biochemical and biological functions of E. histolytica HM-1:IMSS in terms of its virulence. The addition of PC-Chol liposomes to the culture medium maintained the virulence of these parasites against hamster liver at the same level as the original virulent E. histolytica strain, even though these amoebae were maintained without passage through hamster liver for 18 months. The trophozoites also showed increased endocytosis, erythrophagocytosis, and carbohydrate residue expression on the amoebic surface. Protease activities were also modified by the presence of cholesterol in the culture medium. These findings indicate the capacity of cholesterol to preserve amoeba virulence and provide an alternative method for the maintenance of virulent E. histolytica trophozoites without the need for in vivo procedures.

  9. 瘤棘砂壳虫(肉足亚门:根足总纲)壳体元素组成%Elemental Composition of the Shell of the Testate Amoeba Difflugia tuberspinifera (Sarcodina:Rhizopoda)

    Institute of Scientific and Technical Information of China (English)

    杨军; Louis BEYENS; 沈韫芬; 冯伟松

    2004-01-01

    X-ray microanalysis was used to study the elemental composition of the shell of the freshwater testate amoeba Difflugia tuberspinifera Hu et al.,1997 collected from Mulan Lake,Hubei province,China in July 2003.The results show that the shell is composed of ten elements:Si in greater quantity;then Ca and Al;and traces of K,Na,Cl,Fe,Mg,S and P.The analysis of results suggests that D.tuberspinifera in elemental composition appears to occupy a middle position between marine and soil testate amoebae.%利用X射线能谱仪对采自中国湖北省木兰湖的瘤棘砂壳虫(Difflugia tuberspinifera)壳体元素组成进行分析,结果发现:构成壳体的化学元素主要为Si,其次是Ca和Al,还有微量K、Na、Cl、Fe、Mg、S和P.分析表明瘤棘砂壳虫壳体化学元素的构成介于海洋和土壤有壳肉足虫之间.

  10. Holocene palaeohydrological history of the Tǎul Muced peat bog (Northern Carpathians, Romania) based on testate amoebae (Protozoa) and plant macrofossils

    Science.gov (United States)

    Cosmin Diaconu, Andrei; Feurdean, Angelica; Lamentowicz, Mariusz; Gałka, Mariusz; Tanţǎu, Ioan

    2016-04-01

    Knowledge of past local vs. regional hydro-climate variability is a priority in climate research. This is because ecosystems and human depend on local climatic conditions and the magnitude of these climate changes is more variable at local and regional rather than at global scales. Ombrotrophic bogs are highly suitable for hydro-climate reconstructions as they are entirely dependent on the water from precipitation. We used stratigraphy, radiocarbon dating, testate amoebae (TA) and plant macrofossils on a peat profile from an ombrotrophic bog (Tǎul Muced) located in the Biosphere Reserve of the Rodna National Park Romania. We performed quantitative reconstruction of the depth to water table (DWT) and pH over the last 8000 years in a continental area of CE Europe. We identified six main stages in the development of the bog based on changes in TA assemblages in time. Wet conditions and pH between 2 and 4.5 were recorded between 4600-2750 and 1300-400 cal. yr BP, by the occurrence of Archerella flavum, Amphitrema wrightianum and Hyalosphenia papilio. This was associated to a local vegetation primarily composed of Sphagnum magellanicum and S. angustifolium. Dry stages and pH of 2.5 to 5 were inferred between 7550-4600, 2750-1300 and -50 cal. yr BP, by the dominance of Nebela militaris, Difflugia pulex and Phryganella acropodia. These overall dry conditions were also connected with increased abundance of Eriophorum vaginatum. The period between 400 and -50 cal. yr BP was characterized by a rapid shift from dry to wet conditions on the surface of the bog. Vegetation shifted from Sphagnum magellanicum to Sphagnum russowii dominated community. Our reconstruction remains in relatively good agreement with other palaeohydrological records from Central Eastern Europe. However, it shows contrasting conditions to others particularly with records from NW Europe. The valuable information regarding bog hydrology offered by our record puts an accent on the need of more regional TA

  11. Amebas testáceas ocorrentes na região de Porto Alegre, Rio Grande do Sul: II. Novos registros para a região Testate amoebae found in the region of Porto Alegre, Rio Grande do Sul: II. New record to the region

    Directory of Open Access Journals (Sweden)

    Vladimir Stolzenberg Torres

    1998-01-01

    Full Text Available A second study of the testate amoebae of the region of Porto Alegre, Rio Grande do Sul revealed the presence of Arcella Ehrenberg, 1830.Difflugia Leclerc, 1815, Lesquereusia Schulumberger, 1845, Centropyxis Stein, 1857, Bulinularia Penard, 1911 and Euglypha Dujardin, 1841 genera. Our finds demand emendations of the diagnostic characteristics of several species.

  12. Disentangling the effects of water chemistry and substratum structure on moss-dwelling unicellular and multicellular micro-organisms in spring-fens

    Directory of Open Access Journals (Sweden)

    Michal HORSÁK

    2011-09-01

    Full Text Available Water chemistry is known to be one of the most important factors controlling species composition of many macro-organisms in wetlands. It is unclear to what extent micro-organisms respond to water chemistry as compared to chemistry-mediated substratum structure. We explored how the assemblages of different groups of micro-organisms in bryophyte tufts of spring-fens were determined by water chemistry and substratum structure. The aim was to compare unicellular autotrophic diatoms, unicellular heterotrophic testate amoebae and multicellular heterotrophic monogonont rotifers. Assemblages of all three groups showed a strong compositional gradient correlated with water pH and conductivity, calcium concentration and dominance of Sphagnum. While a second strong gradient in species composition of diatoms and testate amoebae was explained by factors such as substratum structure and water content, that of rotifers remained unexplained. Unlike the other two groups, testate amoeba assemblages were significantly determined by phosphates. Nitrates and iron were important species composition determinants for diatoms. Rotifers differed from the other groups in that they did not respond significantly to silica, iron or nutrients. When variation caused by substratum characteristics and water chemistry were partitioned out, testate amoebae were controlled more by substratum, while rotifers and diatoms were controlled more by water chemistry. Variation explained by individual effects of substratum or water chemistry, as compared to shared effects, was much lower for rotifers than for testate amoebae and diatoms. Our results show that, in semi-terrestrial ecosystems, pH and calcium concentrations are generally the main drivers of variation in species composition of unicellular and multicellular microorganisms, mirroring well described patterns for macro-organisms, providing support for general ecological hypotheses. Other water chemistry variables differed between

  13. 长江中游泥炭湿地有壳变形虫空间分布及其对水化学因子的响应%RESPONSE OF TESTATE AMOEBAE COMMUNITY TO WATER CHEMISTRY IN PEATLANDS NEAR THE MIDDLE REACH OF YANGTZE RIVER

    Institute of Scientific and Technical Information of China (English)

    秦养民; 王翰林; 张千帆; 张随成; 谭开甲; 张志麒; 顾延生; 黄咸雨; 王红梅

    2013-01-01

    The rare distributions of peatlands near the middle reach of Yangtze River are important for their biodiversity, local ecological safety, climate change, hydrology and as historical archives. To investigate the biodiversity and ecology in the peatlands can help us to better understand their ecological roles for the society. A total 69 number of Sphagnum samples were collected from five different peatlands in Dajiuhu (23 samples) , Erxianyan ( 20 samples) and Qizimeishan(26 samples) in July 2010. The upper 5cm Sphagnum were collected for testate amoebae analysis. A small hole was drilled at each sampling site to test the depth to water table (DTW) ,pH and conductivity. At each site,about 20ml water was taken to the lab for chemistry analysis. Testate amoebae are a kind of protozoa that build a test (shell) ,in which a single amoeboid cell is enclosed. They occur worldwide in a range of terrestrial, wetland, lakes and especially are abundant in Sphagnum-dominated peats. They are sensitive to environmental changes and thus as excellent indicators for biomonitoring. A lot of studies have repeatedly proven that surface moisture or the depth to water table (DTW) in peatlands is the most important factor to control the distribution of testate amoeba communities. However,the relationship between testate amoebae and water chemistry is still unclear. This study investigated the response of testate amoebae community to water chemistry in peatlands near the middle Yangtze reaches of Central China. The results showed that Cr and Mn can significantly affect testate amoebae community. The differences of testate amoebae community between different sites may reflect the type, characters, and human activities among peatlands. Our results suggested that testate amoebae can be as indicators for peatlands management, biomonitoring and sustainable development.%长江中游高山泥炭湿地在区域生态安全和生物多样性保护方面具有举足重要的地位,有壳变形虫是

  14. NOTE ON THE TAXONOMY OF TESTATE AMOEBAE AND THEIR APPLICATIONS IN ECOLOGY AND PALAEOECOLOGY OF CHINA,WITH PARTICULAR REFERENCE TO GENUS Argynnia Vucetich,1974%中国有壳变形虫Argynnia(Vucetich,1974)属的修订及若干环境重建问题探讨

    Institute of Scientific and Technical Information of China (English)

    秦养民; 张文静; 李鸿凯; Edward A. D. Mitchell; Enrique Lara; 张千帆; 朱荣; 顾延生

    2011-01-01

    Testate amoebae are unicellular protists that build a test( shell) ,in which a single amoeboid cell is enclosed. They occur worldwide in a range of terrestrial, wetland, freshwater and even marine habitats, and have proven to be excellent paleoenvironmental proxies in peats and lakes. In protist diversity, testate amoebae occupy a special position due to their particularly conspicuous shell morphology and their important role in nutrient cycling and energy fluxes within microbial food webs. Although most testate amoebae species are generally supposed to have a cosmopolitan distribution, some species are classical examples of local endemism in free-living protozoa and this question is thus debated. Previous morphological and molecular studies justified that genus Argynnia Vucetich,1974 is different from genus Nebela Leidy,1874. However,genus Argynnia is still included in genus Nebela in Chinese testate amoeba taxonomy. Our first goal is to draw attention of Chinese testate amoeba researchers in the current taxonomy of this group, in which the genus Argynnia is separated from genus Nebela combining previous morphological and molecular studies.In China and even in Asia, research on testate amoebae in peatland ecosystems have only began in recent years. Two species belonging to this genus have been observed in China; Argynnia caudata ( Leidy 1876) and A. Dentistoma ( Penard 1890). Possible problems in environmental reconstructions using testate amoeba based transfer functions as well as estimates of global testate amoeba biodiversity caused by taxonomic inconsistency are also discussed, illustrating the necessity for a major taxonomic effort for this group toward a high bioindicator value.%有壳变形虫是一类具外壳的陆相淡水根足纲(Rhizopoda)原生动物,广泛栖息于湖泊、泥炭、沼泽、土壤等各种淡水潮湿环境,由于其壳体具有很好的抗腐蚀性而在沉积物中保存下来,近年来广泛应用于泥炭和湖泊湿地的古

  15. Intracellular multiplication of Legionella species and the influence of amoebae on their intracellular growth in human monocytes: mono mac 6 cells and Acanthamoeba castellanii as suitable in vitro models.

    Science.gov (United States)

    Neumeister, Birgid

    2004-01-01

    Legionellae are important etiological agents of pneumonia. Legionella pneumophila (predominantly serogroup 1) is detected in most cases of legionellosis; other species only occasionally cause infections, predominantly in immunocompromized patients. Aquiferous technical systems are the primary source of infection (air-conditioning systems, refrigerators, showers, whirlpools, springs, taps, moisturizing equipment, medical nebulizers, and swimming pools). Legionellae are present in the water in these systems, within the amoebae, flagellates, and ciliates in which they replicate. After inhalation of contaminated aerosols, the bacteria multiply intracellularly within alveolar macrophages. The ability to multiply within monocytic host cells is usually considered to correspond to pathogenicity. The mechanisms of intracellular replication have been only partially characterized. Analysis of the molecular pathogenesis of Legionella infection, both in the pathogen itself and in the host cell, is the subject of current research and may lead to new options in prophylaxis and treatment. We have established the human Mono Mac 6 cell line (MM6) instead of the previously used histiocytic lymphoma cell line U 937 or the promyelocytic leukemia cell line HL-60 to investigate the intracellular replication of legionellae and the molecular pathogenesis of Legionella infection within human monocytic host cells. MM6 cells represent a more mature macrophage-like cell line that expresses phenotypic and functional properties of mature monocytes and that does not need to be stimulated by phorbol esters or 1,25-dihydroxyvitamin D3. A good correlation between the prevalence of a given Legionella species and its intracellular multiplication in MM6 cells could be demonstrated.In addition to Legionella, MM6 cells were found to support the intracellular growth of Mycobacterium tuberculosis and Chlamydia pneumoniae, two other important bacterial agents involved in induction of pneumonia. Therefore

  16. 应用rioja软件包建立有壳变形虫-环境因子转换函数%Building Transfer Functions Between Testate amoeba and Environmental Variables with 'rioja' Package

    Institute of Scientific and Technical Information of China (English)

    李鸿凯; 李微微; 蒲有宝; 王从洋; 王松梅; 杨晓林

    2013-01-01

    R language,as an open source programming language and software environment,is widely used in statistics for its free availability.The ‘rioja’ package of R specially deals with the analysis of Quaternary science data,containing functions for constrained clustering,transfer functions and plotting stratigraphic data.Testate amoebae are a group of unicellular protists living in terrestrial habitats.Their decayed resistant and morphologically diagnostic shells (tests) allow them to be extensive used as proxy in peat based paleoenvironmental reconstruction.This study aimed to:① Present an example of application of ‘rioja’ package; ② build Testate amoeba-based transfer functions for quantitatively reconstructing paleoenvironment changes in Changbai Mountains with peat archive.The training set was constituted by 75 samples collected from four peatlands,Hani(42°12′50″N,126°31 ′05 ″E),Jinchuan(42°20 ′47 ″N,126°21 ′35 ″E),Chichi(42°03 ′16 ″N,128°03 ′22 ″E) and Yuanchi(42°01 ′55 ″N,128°25 ′58 ″E),in Changbai Mountains,northeast China.Three factors,depth to water table (DWT),pH and peat moisture,were selected as the target environmental variables.The models of Weighted Averaging (WA) and Weighted Averaging Partial Least Squares (WA-PLS) were used to build transfer functions.Leave-one-out was chosen as cross validation method.The results showed that the second component of WA-PLS is the best models for DWT producing a RMSEP of 7.39 and R2 of 0.74.For pH and peat moisture,both first component of WA-PLS and WA with inverse deshrinking could be regarded as the best models for they have the lowest RMSEP and relatively higher R2.The RMSEP of pH is 0.18 and R2 is 0.72,while for peat moisture RMSEP isl.95% and R2 is 0.62.The performances of the transfer function were comparable with other studies in the world.DWT,pH and peat moisture could be quantitive reconstructed with the mean errors of ±7.39 cm,±0.18 and ± 1.95

  17. Effect of therapeutic chemical agents in vitro and on experimental meningoencephalitis due to Naegleria fowleri.

    Science.gov (United States)

    Kim, Jong-Hyun; Jung, Suk-Yul; Lee, Yang-Jin; Song, Kyoung-Ju; Kwon, Daeho; Kim, Kyongmin; Park, Sun; Im, Kyung-Il; Shin, Ho-Joon

    2008-11-01

    Naegleria fowleri is a ubiquitous, pathogenic free-living amoeba; it is the most virulent Naegleria species and causes primary amoebic meningoencephalitis (PAME) in laboratory animals and humans. Although amphotericin B is currently the only agent available for the treatment of PAME, it is a very toxic antibiotic and may cause many adverse effects on other organs. In order to find other potentially therapeutic agents for N. fowleri infection, the present study was undertaken to evaluate the in vitro and in vivo efficacies of miltefosine and chlorpromazine against pathogenic N. fowleri. The result showed that the growth of the amoeba was effectively inhibited by treatment with amphotericin B, miltefosine, and chlorpromazine. When N. fowleri trophozoites were treated with amphotericin B, miltefosine, and chlorpromazine, the MICs of the drug were 0.78, 25, and 12.5 microg/ml, respectively, on day 2. In experimental meningoencephalitis of mice that is caused by N. fowleri, the survival rates of mice treated with amphotericin B, miltefosine, and chlorpromazine were 40, 55, and 75%, respectively, during 1 month. The average mean time to death for the amphotericin B, miltefosine, and chlorpromazine treatments was 17.9 days. In this study, the effect of drugs was found to be optimal when 20 mg/kg was administered three times on days 3, 7, and 11. Finally, chlorpromazine had the best therapeutic activity against N. fowleri in vitro and in vivo. Therefore, it may be a more useful therapeutic agent for the treatment of PAME than amphotericin B.

  18. 甘肃尕海湿地冬季肉鞭虫物种多样性研究%Studies on Species Diversity of Amoebae and Flagellates in Gahai Wetland of Gansu Province in Winter

    Institute of Scientific and Technical Information of China (English)

    刘汉成; 王珊珊; 马雄; 马海财; 巩红冬; 宁应之

    2012-01-01

    Species diversity of amoebae and flagellates in Cahai wetland was studied with "non-flooded pelri dish method" and in vivo observation from October 2011 to January 2012. In addition to 6 unnamed species, total 81 species, belonging to 2 subphylums,6 classes, 13orders,26 families and 39 genera,were identified. Euglenida and Kineto-plastida are the dominant groups, occupied 38. 18% and 25.45% respectively in Mastigophora. And amoebida is the dominant group (62.5% ) in Sarcodina. The results showed that Dinoflagellida was rare community in this area with only one species, one genus found. Results of the studies indicated that there is abundant species in Gahai wetland, and the species distribution has an obvious negative relationship to the temperature of various sampling sites,but no significant relationship with the altitude or humidity of the sampling site.%自2011年10月至2012年1月,用“非淹没培养皿法”和活体现察法对冬季尕海湿地内肉鞭虫物种多样性和群落特征进行了研究.共鉴定到肉鞭类原生动物87种,隶属于2亚门6纲13目26科39属,其中包括6个未定名种.在鞭毛亚门中眼虫目和动基体目为优势类群,物种数分别占该亚门物种总数的38.18%和25.45%.肉足亚门中变形目为优势类群,物种数占该亚门物种总数的62.5%.腰鞭目物种为该地区罕见类群,只有1属1种.研究结果表明,尕海湿地内肉鞭虫物种丰富,物种分布与海拔和样点湿度无明显关系,而与样点内生境的温度呈显著负相关性.

  19. Therapeutic effect of rokitamycin in vitro and on experimental meningoencephalitis due to Naegleria fowleri.

    Science.gov (United States)

    Kim, Jong-Hyun; Lee, Yang-Jin; Sohn, Hae-Jin; Song, Kyoung-Ju; Kwon, Daeho; Kwon, Myung-Hee; Im, Kyung-Il; Shin, Ho-Joon

    2008-11-01

    Inhalation of freshwater containing the free-living amoeba Naegleria fowleri leads to a potentially fatal infection known as primary amoebic meningoencephalitis (PAME). Amphotericin B is the only agent with clinical efficacy in the treatment of PAME in humans, however this drug is often associated with adverse effects on the kidney and other organs. In an attempt to select other useful therapeutic agents for treating PAME, the amoebicidal activities of antibacterial agents including clarithromycin, erythromycin, hygromycin B, neomycin, rokitamycin, roxithromycin and zeocin were examined. Results showed that the growth of amoeba was effectively inhibited by treatment with hygromycin B, rokitamycin and roxithromycin. Notably, when N. fowleri trophozoites were treated with rokitamycin, the minimal inhibitory concentration was 6.25 microg/mL on Day 2. In the treatment of experimental meningoencephalitis due to N. fowleri, survival rates of mice treated with roxithromycin and rokitamycin were 25% and 80%, respectively, over 1 month. The mean time to death for roxithromycin and rokitamycin treatment was 16.2 days and 16.8 days, respectively, compared with 11.2 days for control mice. Finally, rokitamycin showed both in vitro and in vivo therapeutic efficacy against N. fowleri and may be a candidate drug for the treatment of PAME.

  20. Effect of environmental stress factors on the uptake and survival of Campylobacter jejuni in Acanthamoeba castellanii

    DEFF Research Database (Denmark)

    Bui, Thanh Xuan; Qvortrup, Klaus; Wolff, Anders;

    2012-01-01

    Background: Campylobacter jejuni is a major cause of bacterial food-borne illness in Europe and North America. The mechanisms allowing survival in the environment and transmission to new hosts are not well understood. Environmental free-living protozoa may facilitate both processes. Pre-exposure ......Background: Campylobacter jejuni is a major cause of bacterial food-borne illness in Europe and North America. The mechanisms allowing survival in the environment and transmission to new hosts are not well understood. Environmental free-living protozoa may facilitate both processes. Pre...... was slightly up-regulated under heat and oxidative stresses but down-regulated under starvation and osmotic stresses, the htrA gene showing the largest down-regulation in response to osmotic stress. Pre-exposure of bacteria to low nutrient or osmotic stress reduced bacterial uptake by amoeba, but no effect...... of heat or oxidative stress was observed. Finally, C. jejuni rapidly lost viability within amoeba cells and pre-exposure to oxidative stress had no significant effect on intracellular survival. However, the numbers of intracellular bacteria recovered 5 h post-gentamicin treatment were lower with starved...

  1. Effect of Clinoptilolite and Sepiolite Nanoclays on Human and Parasitic Highly Phagocytic Cells

    Directory of Open Access Journals (Sweden)

    Yanis Toledano-Magaña

    2015-01-01

    Full Text Available Nanoclays have potential applications in biomedicine raising the need to evaluate their toxicity in in vitro models as a first approach to its biocompatibility. In this study, in vitro toxicity of clinoptilolite and sepiolite nanoclays (NC was analyzed in highly phagocytic cultures of amoebas and human and mice macrophages. While amebic viability was significantly affected only by sepiolite NC at concentrations higher than 0.1 mg/mL, the effect on macrophage cultures was dependent on the origin of the cells. Macrophages derived from human peripheral blood monocytes were less affected in viability (25% decrease at 48 h, followed by the RAW 264.7 cell line (40%, and finally, macrophages derived from mice bone marrow monocytes (98%. Moreover, the cell line and mice macrophages die mainly by necrosis, whereas human macrophages exhibit increased apoptosis. Cytokine expression analysis in media of sepiolite NC treated cultures showed a proinflammatory profile (INFγ, IL-1α, IL-8, and IL-6, in contrast with clinoptilolite NC that induced lees cytokines with concomitant production of IL-10. The results show that sepiolite NC is more toxic to amoebas and macrophages than clinoptilolite NC, mostly in a time and dose-dependent manner. However, the effect of sepiolite NC was comparable with talc powder suggesting that both NC have low cytotoxicity in vitro.

  2. Effect of chlorine and temperature on free-living protozoa in operational man-made water systems (cooling towers and hot sanitary water systems) in Catalonia.

    Science.gov (United States)

    Canals, Oriol; Serrano-Suárez, Alejandra; Salvadó, Humbert; Méndez, Javier; Cervero-Aragó, Sílvia; Ruiz de Porras, Vicenç; Dellundé, Jordi; Araujo, Rosa

    2015-05-01

    In recent decades, free-living protozoa (FLP) have gained prominence as the focus of research studies due to their pathogenicity to humans and their close relationship with the survival and growth of pathogenic amoeba-resisting bacteria. In the present work, we studied the presence of FLP in operational man-made water systems, i.e. cooling towers (CT) and hot sanitary water systems (HSWS), related to a high risk of Legionella spp. outbreaks, as well as the effect of the biocides used, i.e. chlorine in CT and high temperature in HSWS, on FLP. In CT samples, high-chlorine concentrations (7.5 ± 1.5 mg chlorine L(-1)) reduced the presence of FLP by 63.8 % compared to samples with low-chlorine concentrations (0.04 ± 0.08 mg chlorine L(-1)). Flagellates and amoebae were observed in samples collected with a level of 8 mg chlorine L(-1), which would indicate that some FLP, including the free-living amoeba (FLA) Acanthamoeba spp., are resistant to the discontinuous chlorine disinfection method used in the CT studied. Regarding HSWS samples, the amount of FLP detected in high-temperatures samples (53.1 ± 5.7 °C) was 38 % lower than in low-temperature samples (27.8 ± 5.8 °C). The effect of high temperature on FLP was chiefly observed in the results obtained by the culture method, in which there was a clear reduction in the presence of FLP at temperatures higher than 50 °C, but not in those obtained by PCR. The findings presented here show that the presence of FLP in operational man-made water systems should be taken into account in future regulations. PMID:25410311

  3. Moduli of monopole walls and amoebas

    Science.gov (United States)

    Cherkis, Sergey A.; Ward, Richard S.

    2012-05-01

    We study doubly-periodic monopoles, also called monopole walls, determining their spectral data and computing the dimensions of their moduli spaces. Using spectral data we identify the moduli, and compare our results with a perturbative analysis. We also identify an SL(2, {Z}) action on monopole walls, in which the S transformation corresponds to the Nahm transform.

  4. The multicellularity genes of dictyostelid social amoebas.

    Science.gov (United States)

    Glöckner, Gernot; Lawal, Hajara M; Felder, Marius; Singh, Reema; Singer, Gail; Weijer, Cornelis J; Schaap, Pauline

    2016-06-30

    The evolution of multicellularity enabled specialization of cells, but required novel signalling mechanisms for regulating cell differentiation. Early multicellular organisms are mostly extinct and the origins of these mechanisms are unknown. Here using comparative genome and transcriptome analysis across eight uni- and multicellular amoebozoan genomes, we find that 80% of proteins essential for the development of multicellular Dictyostelia are already present in their unicellular relatives. This set is enriched in cytosolic and nuclear proteins, and protein kinases. The remaining 20%, unique to Dictyostelia, mostly consists of extracellularly exposed and secreted proteins, with roles in sensing and recognition, while several genes for synthesis of signals that induce cell-type specialization were acquired by lateral gene transfer. Across Dictyostelia, changes in gene expression correspond more strongly with phenotypic innovation than changes in protein functional domains. We conclude that the transition to multicellularity required novel signals and sensors rather than novel signal processing mechanisms.

  5. Moduli of Monopole Walls and Amoebas

    CERN Document Server

    Cherkis, Sergey A

    2012-01-01

    We study doubly-periodic monopoles, also called monopole walls, determining their spectral data and computing the dimensions of their moduli spaces. Using spectral data we identify the moduli, and compare our results with a perturbative analysis. We also identify an SL(2,Z) action on monopole walls, in which the S transformation corresponds to the Nahm transform.

  6. Giant Viruses of Amoebas: An Update.

    Science.gov (United States)

    Aherfi, Sarah; Colson, Philippe; La Scola, Bernard; Raoult, Didier

    2016-01-01

    During the 12 past years, five new or putative virus families encompassing several members, namely Mimiviridae, Marseilleviridae, pandoraviruses, faustoviruses, and virophages were described. In addition, Pithovirus sibericum and Mollivirus sibericum represent type strains of putative new giant virus families. All these viruses were isolated using amoebal coculture methods. These giant viruses were linked by phylogenomic analyses to other large DNA viruses. They were then proposed to be classified in a new viral order, the Megavirales, on the basis of their common origin, as shown by a set of ancestral genes encoding key viral functions, a common virion architecture, and shared major biological features including replication inside cytoplasmic factories. Megavirales is increasingly demonstrated to stand in the tree of life aside Bacteria, Archaea, and Eukarya, and the megavirus ancestor is suspected to be as ancient as cellular ancestors. In addition, giant amoebal viruses are visible under a light microscope and display many phenotypic and genomic features not found in other viruses, while they share other characteristics with parasitic microbes. Moreover, these organisms appear to be common inhabitants of our biosphere, and mimiviruses and marseilleviruses were isolated from human samples and associated to diseases. In the present review, we describe the main features and recent findings on these giant amoebal viruses and virophages.

  7. Giant viruses of amoebas: an update

    Directory of Open Access Journals (Sweden)

    Sarah eAherfi

    2016-03-01

    Full Text Available During the 12 past years, five new or putative virus families encompassing several members, namely Mimiviridae, Marseilleviridae, pandoraviruses, faustoviruses, and virophages were described. In addition, Pithovirus sibericum and Mollivirus sibericum represent type strains of putative new giant virus families. All these viruses were isolated using amoebal coculture methods. These giant viruses were linked by phylogenomic analyses to other large DNA viruses. They were then proposed to be classified in a new viral order, the Megavirales, on the basis of their common origin, as shown by a set of ancestral genes encoding key viral functions, a common virion architecture, and shared major biological features including replication inside cytoplasmic factories. Megavirales is increasingly demonstrated to stand in the tree of life aside Bacteria, Archaea and Eukarya, and the megavirus ancestor is suspected to be as ancient as cellular ancestors. In addition, giant amoebal viruses are visible under a light microscope and display many phenotypic and genomic features not found in other viruses, while they share other characteristics with parasitic microbes. Moreoever, these organisms appear to be common inhabitants of our biosphere, and mimiviruses and marseilleviruses were isolated from human samples and associated to diseases. In the present review, we describe the main features and recent findings on these giant amoebal viruses and virophages.

  8. Bacteria isolated from amoebae/bacteria consortium

    Science.gov (United States)

    Tyndall, Richard L.

    1995-01-01

    New protozoan derived microbial consortia and method for their isolation are provided. Consortia and bacteria isolated therefrom are useful for treating wastes such as trichloroethylene and trinitrotoluene. Consortia, bacteria isolated therefrom, and dispersants isolated therefrom are useful for dispersing hydrocarbons such as oil, creosote, wax, and grease.

  9. A cytohesin homolog in Dictyostelium amoebae.

    Directory of Open Access Journals (Sweden)

    Maria Christina Shina

    Full Text Available BACKGROUND: Dictyostelium, an amoeboid motile cell, harbors several paralogous Sec7 genes that encode members of three distinct subfamilies of the Sec7 superfamily of Guanine nucleotide exchange factors. Among them are proteins of the GBF/BIG family present in all eukaryotes. The third subfamily represented with three members in D. discoideum is the cytohesin family that has been thought to be metazoan specific. Cytohesins are characterized by a Sec7 PH tandem domain and have roles in cell adhesion and migration. PRINCIPAL FINDINGS: Dictyostelium SecG exhibits highest homologies to the cytohesins. It harbors at its amino terminus several ankyrin repeats that are followed by the Sec7 PH tandem domain. Mutants lacking SecG show reduced cell-substratum adhesion whereas cell-cell adhesion that is important for development is not affected. Accordingly, multicellular development proceeds normally in the mutant. During chemotaxis secG(- cells elongate and migrate in a directed fashion towards cAMP, however speed is moderately reduced. SIGNIFICANCE: The data indicate that SecG is a relevant factor for cell-substrate adhesion and reveal the basic function of a cytohesin in a lower eukaryote.

  10. Giant Viruses of Amoebas: An Update

    Science.gov (United States)

    Aherfi, Sarah; Colson, Philippe; La Scola, Bernard; Raoult, Didier

    2016-01-01

    During the 12 past years, five new or putative virus families encompassing several members, namely Mimiviridae, Marseilleviridae, pandoraviruses, faustoviruses, and virophages were described. In addition, Pithovirus sibericum and Mollivirus sibericum represent type strains of putative new giant virus families. All these viruses were isolated using amoebal coculture methods. These giant viruses were linked by phylogenomic analyses to other large DNA viruses. They were then proposed to be classified in a new viral order, the Megavirales, on the basis of their common origin, as shown by a set of ancestral genes encoding key viral functions, a common virion architecture, and shared major biological features including replication inside cytoplasmic factories. Megavirales is increasingly demonstrated to stand in the tree of life aside Bacteria, Archaea, and Eukarya, and the megavirus ancestor is suspected to be as ancient as cellular ancestors. In addition, giant amoebal viruses are visible under a light microscope and display many phenotypic and genomic features not found in other viruses, while they share other characteristics with parasitic microbes. Moreover, these organisms appear to be common inhabitants of our biosphere, and mimiviruses and marseilleviruses were isolated from human samples and associated to diseases. In the present review, we describe the main features and recent findings on these giant amoebal viruses and virophages. PMID:27047465

  11. Effect of Nutritional Stress on Autophagy in Free-Living Amoeba%营养缺乏对自由生活阿米巴自噬的影响

    Institute of Scientific and Technical Information of China (English)

    王南宁; 谭玉珍; 王海杰

    2010-01-01

    目的 研究在营养缺乏的环境中自由生活阿米巴自噬的变化和自噬结构的形态学特征.方法 对照组自由生活阿米巴用涂有大肠埃希菌的琼脂培养基培养.实验组将在大肠埃希菌中培养的阿米巴转移至不含大肠埃希菌的琼脂培养基上培养12 h.扫描电镜下观察不提供细菌的培养环境中阿米巴的形态学变化,透射电镜下观察阿米巴自噬的变化及自噬前体、自噬体和自噬溶酶体的结构特点.图像分析仪测量虫体内自噬结构与细胞质的断面面积.单丹磺酰尸胺(MDC)染色法标记自由生活阿米巴虫体内的自噬体.在共聚焦激光扫描显微镜下观察和定量分析.结果 对照组中自由生活阿米巴均为滋养体形式;实验组中,滋养体逐渐向包囊转变.对照组阿米巴虫体内充满细菌碎片,只发生轻微的自噬,自噬结构数目较少.与对照组比较,实验组阿米巴自噬水平显著提高,自噬结构数目增多,自噬前体、自噬体和自噬溶酶体与细胞质的断面面积比增大(P<0.05或0.01);部分阿米巴虫体内残存未消化的细菌碎片.结论 在缺乏营养的环境中,自由生活阿米巴由滋养体向包囊转变,虫体内自噬功能显著增强.

  12. Species richness and geographic distribution of testate amoebae (Rhizopoda in Brazilian freshwater environments = Riqueza de espécies e distribuição geográfica de amebas testáceas (Rhizopoda em ambientes aquáticos continentais brasileiros

    Directory of Open Access Journals (Sweden)

    Fábio Amodêo Lansac-Tôha

    2007-04-01

    Full Text Available The present study aimed to analyze the species richness of testate amoebae, as well as to describe their geographic distribution and different habitat types in Brazilian freshwater environments. Until now, 346 infrageneric taxa have been recorded, belonging to 13 families and 40 genera. In the Center-West region, 267 taxa were recorded; 188 taxa in the Southeast; 129 taxa in the South, 53 taxa in the North; and 18 taxa in Northeast region. A total of 282 taxa were recorded in plankton; 80 taxa in aquatic macrophytes; 81 taxa insediment; and 73 taxa in moss/sphagnum. The results regarding testate amoebae species richness are not yet conclusive, given that most research on these organisms was carried out in central, southeastern and southern Brazil. The higher number of taxa observed in plankton may be due to the fact that most studies on testate amoebae in Brazil had been carried out in the planktonic compartment, including reservoirs, floodplain lagoons, channels, tributaries and rivers. In addition, the majority of studies with sediment samples were conducted in estuaries or coastal lagoons, where salinity is a restricting factor for the occurrence of these organisms.Este trabalho visa realizar um levantamento da riqueza de espécies de amebas testáceas, bem como descrever a distribuição geográfica e a distribuição em diferentes tipos de habitats desses organismos em ambientes aquáticos continentais brasileiros. Até o momento, são registrados 346 táxons infragenéricos, pertencentes a 13 famílias e 40 gêneros. São registrados 267 táxons na região centro-oeste, 188táxons na região sudeste, 129 táxons na região sul, 53 táxons na região norte e 18 táxons na região nordeste. São registrados 282 táxons no plâncton; 131 táxons em macrófitas aquáticas, 81 táxonsno sedimento e 73 táxons em musgos/esfágnos. Os resultados sobre a riqueza de tecamebas não é ainda conclusiva, visto que a maioria das pesquisas foi conduzida

  13. Riqueza de espécies e distribuição geográfica de amebas testáceas (Rhizopoda em ambientes aquáticos continentais brasileiros - DOI: 10.4025/actascibiolsci.v29i2.525 Species richness and geographic distribution of testate amoebae (Rhizopoda in Brazilian freshwater environments

    Directory of Open Access Journals (Sweden)

    Leandro Junio Fulone

    2007-12-01

    Full Text Available Este trabalho visa realizar um levantamento da riqueza de espécies de amebas testáceas, bem como descrever a distribuição geográfica e a distribuição em diferentes tipos de habitats desses organismos em ambientes aquáticos continentais brasileiros. Até o momento, são registrados 346 táxons infragenéricos, pertencentes a 13 famílias e 40 gêneros. São registrados 267 táxons na região centro-oeste, 188 táxons na região sudeste, 129 táxons na região sul, 53 táxons na região norte e 18 táxons na região nordeste. São registrados 282 táxons no plâncton; 131 táxons em macrófitas aquáticas, 81 táxons no sedimento e 73 táxons em musgos/esfágnos. Os resultados sobre a riqueza de tecamebas não é ainda conclusiva, visto que a maioria das pesquisas foi conduzida nas regiões centro-oeste, sudeste e sul. O maior número de táxons registrados no plâncton pode ser em virtude de que a maioria dos estudos sobre tecamebas, no Brasil, ter sido realizada no compartimento planctônico, incluindo reservatórios, lagoas de várzeas, canais, tributários e rios. Além disso, a maior parte dos estudos, em amostras de sedimento, foi conduzida em estuários ou lagoas costeiras, onde a salinidade é um fator limitante para a ocorrência desses organismos.The present study aimed to analyze the species richness of testate amoebae, as well as to describe their geographic distribution and different habitat types in Brazilian freshwater environments. Until now, 346 infrageneric taxa have been recorded, belonging to 13 families and 40 genera. In the Center-West region, 267 taxa were recorded; 188 taxa in the Southeast; 129 taxa in the South, 53 taxa in the North; and 18 taxa in Northeast region. A total of 282 taxa were recorded in plankton; 80 taxa in aquatic macrophytes; 81 taxa in sediment; and 73 taxa in moss/sphagnum. The results regarding testate amoebae species richness are not yet conclusive, given that most research on these organisms

  14. Species richness of testate amoebae in different environments from the upper Paraná river floodplain (PR/MS = Riqueza de amebas testáceas em diferentes ambientes da planície de inundação do alto rio Paraná (PR/MS

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    Deise de Morais Costa

    2011-07-01

    Full Text Available This study evaluated the species richness of testate amoebae in the plankton from different environments of the upper Parana river floodplain. Samplings were performed at subsurface of pelagic region from twelve environments using motorized pump and plankton net (68 ƒÝm, during four hydrological periods. We identified 67 taxa, distributed in seven families and Arcellidae, Difflugiidae and Centropyxidae were the most representative families. Higher values of species richness were observed in the lakes (connected and isolated during the flood pulses. Centropyxis aculeata, Difflugia gramem and D.pseudogramem were frequent throughout the study period. Seasonal variability of species in the channels and isolated lakes was evidenced by beta diversity. Besides that, in the rivers, extreme changes in species composition were verified during the high-water period. Our results highlight the importance of the present study to improve the knowledge about the diversity and geographic distribution of these organisms in Brazil and emphasize the importance of current flow in the displacement of testate amoebae from their preferredhabitats, marginal vegetation and sediment.Este estudo objetivou avaliar a riqueza de taxons de amebas testaceas no plancton de diferentes ambientes da planicie de inundacao do alto rio Parana. Foram amostrados 12 pontos da regiao pelagica em diferentes ambientes (rios, canais e lagoas e em quatro periodos hidrologicos. Foram identificados 67 taxons, distribuidos em sete familias. Arcellidae, Difflugiidae e Centropyxidae foram as familiasmais especiosas. Nas lagoas (abertas e fechadas, durante os pulsos de inundacao, foram observados os maiores valores para a riqueza de especies. Centropyxis aculeata, Difflugia gramem e D. pseudogramem foram frequentes durante todo o periodo estudado. Os dados obtidos pela diversidade beta evidenciaram a variabilidade sazonal das especies nos canais e lagoas fechadas. Nos rios, as alteracoes

  15. Effects of pesticides, polychlorinated biphenyls and metals on the growth and reproduction of Acanthamoeba castellanii

    Energy Technology Data Exchange (ETDEWEB)

    Prescott, L.M.; Kubovec, M.K.; Tryggestad, D.

    1977-07-01

    The effects of pollutants (pesticides, PCB and metals) were studied in the free-living amoeba, Acanthamoeba castellanii. Eight pesticides were used--the insecticides dieldrin, aldrin and sevin, and the herbicides linuron, stam F-34, IPC, atrazine and simazine. It was shown that the sensitivity of A. castellanii to pesticides varied greatly. The population growth was inhibited by linuron, stam F-34, IPC, sevin and atrazine at a level of 10 mg/l. The polychlorinated biphenyl, Arochor 1254, had no significant effect at a concentration of 0.01 mg/l (10 ppb). The studies with metal ions showed that A. castellanii was unaffected by moderately high levels of Cu and Zn, but was sensitive to the presence of Pb and mercuric ions.

  16. Few apparent short-term effects of elevated soil temperature and increased frequency of summer precipitation on the abundance and taxonomic diversity of desert soil micro- and meso-fauna

    Science.gov (United States)

    Darby, B.J.; Neher, D.A.; Housman, D.C.; Belnap, J.

    2011-01-01

    Frequent hydration and drying of soils in arid systems can accelerate desert carbon and nitrogen mobilization due to respiration, microbial death, and release of intracellular solutes. Because desert microinvertebrates can mediate nutrient cycling, and the autotrophic components of crusts are known to be sensitive to rapid desiccation due to elevated temperatures after wetting events, we studied whether altered soil temperature and frequency of summer precipitation can also affect the composition of food web consumer functional groups. We conducted a two-year field study with experimentally-elevated temperature and frequency of summer precipitation in the Colorado Plateau desert, measuring the change in abundance of nematodes, protozoans, and microarthropods. We hypothesized that microfauna would be more adversely affected by the combination of elevated temperature and frequency of summer precipitation than either effect alone, as found previously for phototrophic crust biota. Microfauna experienced normal seasonal fluctuations in abundance, but the effect of elevated temperature and frequency of summer precipitation was statistically non-significant for most microfaunal groups, except amoebae. The seasonal increase in abundance of amoebae was reduced with combined elevated temperature and increased frequency of summer precipitation compared to either treatment alone, but comparable with control (untreated) plots. Based on our findings, we suggest that desert soil microfauna are relatively more tolerant to increases in ambient temperature and frequency of summer precipitation than the autotrophic components of biological soil crust at the surface.

  17. Synopsis of 6S Management and Amoeba Management & Instance Analysis of Application of Dairy Products Processing Enterprises%6S管理和阿米巴经营管理简介及乳制品加工企业应用实例分析

    Institute of Scientific and Technical Information of China (English)

    朱俊光; 李春梅

    2014-01-01

    中国乳业正呈现出正态上升的发展趋势,各乳制品加工企业也在不断地扩充规模。集团收购或扩充新厂时容易产生一些问题,比如人员劳动效率低下,员工素质不高,经济意识薄弱,质量意识不强等,此类问题多半是因为企业的管理制度不到位造成的。本文分别介绍了6S管理模式和阿米巴经营管理模式,并就其在乳制品加工企业的实际应用和收效分别做了阐述,以期对乳制品加工企业管理模式的选择提供借鉴。%China dairy industry is showing a rising development trend, dairy processing companies also constantly expand their scale. There are some problems during acquiring company or expansion of new factory, such as:staff work efifciency is low, employee’s quality are not good enough, economical consciousness lighter, lack of quality consciousness. These above problems are mostly because of improper management system. This paper exposited 6S management and Amoeba management in several dairy factories, in order to provide reference for dairy processing companies management mode.

  18. Abundância de tecamebas no plâncton de reservatórios do Estado do Paraná- DOI: 10.4025/actascibiolsci.v26i4.1522 Testate amoebae abundance in plankton samples from Paraná State reservoirs - DOI: 10.4025/actascibiolsci.v26i4.1522

    Directory of Open Access Journals (Sweden)

    Claudia Costa Bonecker

    2004-04-01

    Full Text Available Este trabalho teve o objetivo de investigar os padrões de distribuição espacial e temporal da abundância de tecamebas (Rhizopoda no plâncton de diferentes reservatórios do Estado do Paraná bem como a importância de fatores hidrodinâmicos e morfométricos na determinação desses padrões. Os 30 reservatórios estudados estão localizados em seis diferentes bacias, incluindo ambientes com áreas, morfometrias e idades variáveis. As amostragens foram realizadas em julho e novembro de 2001, períodos de estiagem e chuvoso, respectivamente. As amostras foram obtidas à superfície dos reservatórios, na região lacustre, utilizando-se uma bomba (600 litros por amostra e uma rede de plâncton com malhagem de 68 um. As tecamebas foram registradas em 23 reservatórios. Maiores densidades foram encontradas nos reservatórios JMF, Salto do Meio, Melissa, Mourão e Salto do Vau, durante o período de estiagem, e JMF, Salto Osório, Salto do Meio e Melissa, durante o período chuvoso. Esses reservatórios apresentam características similares, como reduzidas profundidades e dimensões morfométricas. Além disso, a maioria deles têm características hidrodinâmicas similares a de ambientes lóticos, por apresentarem alta velocidade de corrente. Por outro lado, as tecamebas foram ausentes ou presentes em baixas densidades, em geral, nos reservatórios com maiores dimensões e profundidade. Ao contrário do esperado, sazonalmente, maiores densidades foram observadas durante o período de estiagem, para a maioria dos reservatórios. Esses resultados podem estar relacionados com o fato de os reservatórios, nesse período hidrológico, apresentarem uma nítida redução de suas dimensões (área e profundidade, determinando uma maior influência de organismos bentônicos para a composição e abundância da comunidade protozooplanctônica δThis study aimed to investigate patterns of spatial and temporal distribution of testate amoebae (Rhizopoda

  19. Targeting cyst wall is an effective strategy in improving the efficacy of marketed contact lens disinfecting solutions against Acanthamoeba castellanii cysts.

    Science.gov (United States)

    Abjani, Farhat; Khan, Naveed Ahmed; Yousuf, Farzana Abubakar; Siddiqui, Ruqaiyyah

    2016-06-01

    Acanthamoeba cysts are highly resistant to contact lens disinfecting solutions. Acanthamoeba cyst wall is partially made of 1,4 β-glucan (i.e., cellulose) and other complex polysaccharides making it a hardy shell that protects the resident amoeba. Here, we hypothesize that targeting the cyst wall structure in addition to antiamoebic compound would improve the efficacy of marketed contact lens disinfecting solutions. Using chlorhexidine as an antiamoebic compound and cellulase enzyme to disrupt cyst wall structure, the findings revealed that combination of both agents abolished viability of Acanthamoeba castellanii cysts and trophozoites. When tested alone, none of the agents nor contact lens disinfecting solutions completely destroyed A. castellanii cysts and trophozoites. The absence of cyst wall-degrading enzymes in marketed contact lens disinfecting solutions render them ineffective against Acanthamoeba cysts. It is concluded that the addition of cyst wall degrading molecules in contact lens disinfecting solutions will enhance their efficacy in decreasing the incidence of Acanthamoeba effectively.

  20. Isolamento e identificação de amebas de vida livre potencialmente patogênicas em amostras de ambientes de hospital público da cidade de Porto Alegre, RS Isolation and identification of potentially pathogenic free-living amoebae in samples from environments in a public hospital in the city of Porto Alegre, Rio Grande do Sul

    Directory of Open Access Journals (Sweden)

    Ana Maris Carlesso

    2007-06-01

    Full Text Available Um estudo sobre a presença de amebas de vida livre em um hospital público foi desenvolvido na Cidade de Porto Alegre, RS. Poeira e biofilmes de 15 ambientes hospitalares, incluindo CTI, UTI pediátrica, cozinha, emergência, centro cirúrgico ambulatorial e centro cirúrgico, reservatórios de água, torneira e 6 bebedouros coletivos foram coletados mensalmente, de julho de 2004 a março de 2005, usando-se suabes estéreis, preparados para a pesquisa. As AVL foram isoladas em cultivo, utilizando-se meio de ágar não nutriente adicionado de Escherichia coli, mortas pelo calor. A identificação dos protozoários foi feita pela observação morfológica de cistos e trofozoítos, segundo critérios morfológicos de Page (1988. Das 135 amostras coletadas dos 15 ambientes estudados, 47 (35% foram positivas para AVL. Destas, 34% apresentaram características morfológicas próprias do gênero Acanthamoeba.A study on the presence of free-living amoebae in a public hospital was developed in the city of Porto Alegre, State of Rio Grande do Sul. Dust and biofilms were collected using sterile swabs that had been prepared for this study, from 15 hospital environments, including the intensive care center, pediatric intensive care unit, kitchen, emergency room, outpatient surgical center, clinical surgical center, water storage tanks, taps and six drinking fountains for general use, every month from July 2004 to March 2005. The FLAs were isolated by culturing, using non-nutrient agar medium with the addition of heat-killed Escherichia coli. The protozoa were identified by morphological observation of cysts and trophozoites, in accordance with Page's morphological criteria (1988. Among the 135 samples collected from the 15 environments, 47 (35% were positive for FLAs. Of these, thirty-four percent presented morphological characteristics particular to the genus Acanthamoeba.

  1. Effective Results on p-adic Tropical Discriminants

    CERN Document Server

    Rusek, Korben

    2012-01-01

    We study A-discriminants from a p-adic point of view, refining earlier work on the tropical discriminant. In particular, we study the case where A is a collection of $n+3$ points in Z^n in general position, and give an algorithm to compute the image of the A-discriminant variety under the p-adic valuation map. Consequences of our approach include tight lower and upper bounds, of order quadratic in n, for the number of connected components of the complement of the amoeba closure. We also detail a Sage package for plotting certain p-adic discriminant amoebae, and present explicit examples of point sets yielding discriminant amoebae with extremal behavior. We also discuss the setting where A has arbitrary cardinality.

  2. Amoebas and Euglenas and Paramecia...Oh, My!

    Science.gov (United States)

    Farenga, Stephen; Joyce, Beverly

    2000-01-01

    Describes a partnership involving fifth grade students, preservice teachers, a classroom teacher, and a university faculty member in introducing students to the basic anatomy of a cell using three-dimensional models, analogies, and hands-on/minds-on activities. (ASK)

  3. A new freshwater amoeba: Cochliopodium pentatrifurcatum n. sp. (Amoebozoa, Amorphea).

    Science.gov (United States)

    Tekle, Yonas I; Roger, Anderson O; Lecky, Ariel F; Kelly, Samantha D

    2013-01-01

    Cochliopodium pentatrifurcatum n. sp. (ATCC(©) 30935(TM) ) is described based on light microscopic morphology, fine structure, and molecular genetic evidence. Cochliopodium pentatrifurcatum n. sp. (length ~ 25 μm) is characterized by surface microscales (0.3 μm tall) containing a circular porous base (~ 0.6 μm diam.) with a thin peripheral rim. Five radially arranged feet, emanating from the base, support a short central column terminating apically as a funnel-shaped collar (~ 0.5 μm diam.) composed of five radial, trifurcate rays extending from the center toward a thin peripheral rim. The central spine is 0.5-0.6 μm long. The comparative morphologies and combined molecular genetic evidence, SSU-rDNA and COI, indicate that the new species falls in a clade sufficiently different from other species to suggest that it is a valid new species.

  4. Dimer Models from Mirror Symmetry and Quivering Amoebae

    CERN Document Server

    Feng, B; Kennaway, K D; Vafa, C; Feng, Bo; He, Yang-Hui; Kennaway, Kristian D.; Vafa, Cumrun

    2005-01-01

    Dimer models are 2-dimensional combinatorial systems that have been shown to encode the gauge groups, matter content and tree-level superpotential of the world-volume quiver gauge theories obtained by placing D3-branes at the tip of a singular toric Calabi-Yau cone. In particular the dimer graph is dual to the quiver graph. However, the string theoretic explanation of this was unclear. In this paper we use mirror symmetry to shed light on this: the dimer models live on a T^2 subspace of the T^3 fiber that is involved in mirror symmetry and is wrapped by D6-branes. These D6-branes are mirror to the D3-branes at the singular point, and geometrically encode the same quiver theory on their world-volume.

  5. Regulation of dynamic cyclic nucleotide signalling in social amoebas

    NARCIS (Netherlands)

    Weening, Karin Esther

    2010-01-01

    Over the past years, much information has been gathered about the importance of the individual key components that control cAMP signalling in eukaryotes and prokaryotes. In mammalians, several different classes of ACs produce cAMP and much is known about their mechanism of stimulation and function.

  6. Tackling infection owing to brain-eating amoeba.

    Science.gov (United States)

    Baig, Abdul Mannan; Khan, Naveed Ahmed

    2015-02-01

    In view of the devastating nature of primary amoebic meningoencephalitis caused by Naegleria fowleri and the problems associated with diagnostic delays and chemotherapeutic failures, here we propose a noninvasive diagnostic method using the 'reverse transcribrial route device', a novel strategy in the management of this life-threatening infection with a case fatality rate of more than 90%. The proposed rationale should stimulate interest in this emerging infection that almost always proves fatal.

  7. Method of separating bacteria from free living amoebae

    Energy Technology Data Exchange (ETDEWEB)

    Tyndall, Richard L. (Clinton, TN)

    1994-01-01

    New protozoan derived microbial consortia and method for their isolation are provided. Consortia and bacteria isolated therefrom are useful for treating wastes such as trichloroethylene and trinitrotoluene. Consortia, bacteria isolated therefrom, and dispersants isolated therefrom are useful for dispersing hydrocarbons such as oil, creosote, wax, and grease.

  8. Evolutionary position of breviate amoebae and the primary eukaryote divergence.

    Science.gov (United States)

    Minge, Marianne A; Silberman, Jeffrey D; Orr, Russell J S; Cavalier-Smith, Thomas; Shalchian-Tabrizi, Kamran; Burki, Fabien; Skjaeveland, Asmund; Jakobsen, Kjetill S

    2009-02-22

    Integration of ultrastructural and molecular sequence data has revealed six supergroups of eukaryote organisms (excavates, Rhizaria, chromalveolates, Plantae, Amoebozoa and opisthokonts), and the root of the eukaryote evolutionary tree is suggested to lie between unikonts (Amoebozoa, opisthokonts) and bikonts (the other supergroups). However, some smaller lineages remain of uncertain affinity. One of these unassigned taxa is the anaerobic, free-living, amoeboid flagellate Breviata anathema, which is of key significance as it is unclear whether it is a unikont (i.e. possibly the deepest branching amoebozoan) or a bikont. To establish its evolutionary position, we sequenced thousands of Breviata genes and calculated trees using 78 protein sequences. Our trees and specific substitutions in the 18S RNA sequence indicate that Breviata is related to other Amoebozoa, thereby significantly increasing the cellular diversity of this phylum and establishing Breviata as a deep-branching unikont. We discuss the implications of these results for the ancestral state of Amoebozoa and eukaryotes generally, demonstrating that phylogenomics of phylogenetically 'nomadic' species can elucidate key questions in eukaryote evolution. Furthermore, mitochondrial genes among the Breviata ESTs demonstrate that Breviata probably contains a modified anaerobic mitochondrion. With these findings, remnants of mitochondria have been detected in all putatively deep-branching amitochondriate organisms.

  9. Indecisive Behavior of Amoeba Crossing AN Environmental Barrier

    Science.gov (United States)

    Takagi, S.; Nishiura, Y.; Nakagaki, T.; Ueda, T.; Ueda, K.-I.

    2007-07-01

    We report here a new kind of behavior that seems to be 'indecisive' in an amoeboid organism, the Physarum plasmodium of true slime mold. The plasmodium migrating in a narrow lane stops moving for a period of time (several hours but the duration differs for each plasmodium) when it encounters the presence of a chemical repellent, quinine. After stopping period, the organism suddenly begins to move again in one of three different ways as the concentration of repellent increases: going through the repulsive place (penetration), splitting into two fronts of going throught it and turning (splitting) and turning back (rebound). In relation to the physiological mechanism for tip migration in the plasmodium, we found that the frontal tip is capable of moving further although the tip is divided from a main body of organism. This means that a motive force of front locomotion is produced by a local process at the tip. Based on this finding, a mathematical model for front locomotion is considered in order to understand the dynamics for both the long period of stopping and three kinds of behavior. A model based on reaction-diffusion equations succeeds to reproduce the experimental observation. The origin of long-time stopping and three different outputs may be reduced to the hidden instabilities of internal dynamics of the pulse, which may be a skeleton structure extracted from much more complex dynamics imbedded in the Physarum plasmodium.

  10. Lysophosphatidic acid is a chemoattractant for Dictyostelium discoideum amoebae.

    OpenAIRE

    Jalink, K.; Moolenaar, W H; Duijn, B., Van

    1993-01-01

    The naturally occurring phospholipid lysophosphatidic acid (LPA) can induce a number of physiological responses in vertebrate cells, including platelet aggregation, smooth muscle contraction, and fibroblast proliferation. LPA is thought to activate a specific G-protein-coupled receptor, thereby triggering classic second messenger pathways such as stimulation of phospholipase C and inhibition of adenylate cyclase. Here we report that 1-oleoyl-LPA, at submicromolar concentrations, evokes a chem...

  11. Composição de amebas testáceas (Protozoa-Rhizopoda de dois córregos do Estado de São Paulo, incluindo novos registros para o Brasil - DOI: 10.4025/actascibiolsci.v27i2.1319 Testate amoebae composition (Protozoa-Rhizopoda from two São Paulo State creeks, including new records for Brazil - DOI: 10.4025/actascibiolsci.v27i2.1319

    Directory of Open Access Journals (Sweden)

    Luiz Felipe Machado Velho

    2005-03-01

    Full Text Available Com o intuito de avaliar a composição e a riqueza da assembléia de amebas testáceas em dois córregos localizados no Noroeste paulista, foram realizadas amostragens mensais durante doze meses no distrito de Talhado, município de São José do Rio Preto, Estado de São Paulo. Os resultados mostraram que apesar do baixo valor de riqueza observado (21 táxons, oito táxons não haviam sido registrados anteriormente no Estado de São Paulo, o que evidencia a necessidade de se aumentar os esforços de coleta no estado além da qualificação de pesquisadores aptos na identificação de tais organismos. Dois táxons, Difflugia corona ecornis e Difflugia lobostoma cornuta, constituem novos registros para o BrasilTwelve monthly samplings were collected in São José do Rio Preto, São Paulo State, Brazil, with the purpose of evaluating the composition and the richness of the testate amoebae assemblage in two creeks. Despite the low richness observed (21 taxa, the results showed that eight taxa had not been recorded before in São Paulo State, which points out to the need of increasing the sampling effort in the state as well as the researchers qualification who should be able to identify such organisms. Difflugia corona ecornis and Difflugia lobostoma cornuta, constitute two new records for Brazil

  12. On the effects of cycloheximide on cell motility and polarisation in Dictyostelium discoideum

    Directory of Open Access Journals (Sweden)

    Traynor David

    2006-01-01

    Full Text Available Abstract Background Cycloheximide is a protein synthesis inhibitor that acts specifically on the 60S subunit of eukaryotic ribosomes. It has previously been shown that a short incubation of Dictyostelium discoideum amoebae in cycloheximide eliminates fluid phase endocytosis. Results We found that treatment with cycloheximide also causes the amoebae to retract their pseudopodia, round up and cease movement. Furthermore, fluid phase endocytosis, phagocytosis and capping cease in the presence of 2 mM cycloheximide, although membrane uptake, as measured using FM1-43, is unaffected. In the presence of cycloheximide, aggregation-competent amoebae sensitive to cAMP, although round, can still localise CRAC, ABP120, PI3K and actin polymerisation in response to a micropipette filled with cAMP. The behaviour of wild-type amoebae in the presence of cycloheximide is surprisingly similar to that of amoebae having a temperature-sensitive version of NSF at the restrictive temperature. Conclusion Our results may suggest that, upon cycloheximide treatment, either a labile protein required for polarised membrane recycling is lost, or a control mechanism linking protein synthesis to membrane recycling is activated.

  13. Effects of Nickel, Chlorpyrifos and Their Mixture on the Dictyostelium discoideum Proteome

    Directory of Open Access Journals (Sweden)

    Francesco Marsano

    2012-11-01

    Full Text Available Mixtures of chemicals can have additive, synergistic or antagonistic interactions. We investigated the effects of the exposure to nickel, the organophosphate insecticide chlorpyrifos at effect concentrations (EC of 25% and 50% and their binary mixture (Ec25 + EC25 on Dictyostelium discoideum amoebae based on lysosomal membrane stability (LMS. We treated D. discoideum with these compounds under controlled laboratory conditions and evaluated the changes in protein levels using a two-dimensional gel electrophoresis (2DE proteomic approach. Nickel treatment at EC25 induced changes in 14 protein spots, 12 of which were down-regulated. Treatment with nickel at EC50 resulted in changes in 15 spots, 10 of which were down-regulated. Treatment with chlorpyrifos at EC25 induced changes in six spots, all of which were down-regulated; treatment with chlorpyrifos at EC50 induced changes in 13 spots, five of which were down-regulated. The mixture corresponding to EC25 of each compound induced changes in 19 spots, 13 of which were down-regulated. The data together reveal that a different protein expression signature exists for each treatment, and that only a few proteins are modulated in multiple different treatments. For a simple binary mixture, the proteomic response does not allow for the identification of each toxicant. The protein spots that showed significant differences were identified by mass spectrometry, which revealed modulations of proteins involved in metal detoxification, stress adaptation, the oxidative stress response and other cellular processes.

  14. A Gene, ALCA, Affecting the Life Cycle Form Expressed in PHYSARUM POLYCEPHALUM.

    Science.gov (United States)

    Truitt, C L; Hoffman, C S; Holt, C E

    1982-05-01

    The usual sequence of forms in the Physarum polycephalum life cycle is plasmodium-spore-amoeba-plasmodium. So-called "amoebaless life cycle" or alc mutants of this Myxomycete undergo a simplified plasmodium-spore-plasmodium life cycle. We have analyzed three independently isolated alc mutants and found in each case that the failure of the spores to give rise to amoebae is due to a recessive Mendelian allele. The three mutations are tightly linked to one another and belong to a single complementation group, alcA. The mutations are pleiotropic, not only interfering with the establishment of the amoebal form at spore germination, but also affecting the phenotype of alc amoebae, which occasionally arise from alc spores. The alc amoebae (1) grow more slowly than wild type, particularly at elevated temperatures; (2) tend to transform directly into plasmodia, circumventing the sexual fusion of amoebae that usually accompanies plasmodium formation; and (3) form plasmodia by the sexual mechanism less efficiently than wild-type amoebae. The various effects of an alc mutation seem to derive from mutation of a single gene, since reversion for one effect is always accompanied by reversion for the other effects. Moreover, a mutation, aptA1, that blocks direct plasmodium formation by alcA amoebae, also increases their growth rate to near normal. The manner of plasmodium formation in alcA strains differs significantly from that in another class of mutants, the gad mutants. Unlike gad amoebae, alcA amoebae need not reach a critical density in order to differentiate directly into plasmodia and do not respond to the extracellular inducer of differentiation. In addition, alcA differentiation is not prevented by a mutation, npfA1, that blocks direct differentiation by most gad amoebae.

  15. The antiamoebic effect of a crude drug formulation of herbal extracts against Entamoeba histolytica in vitro and in vivo.

    Science.gov (United States)

    Sohni, Y R; Kaimal, P; Bhatt, R M

    1995-01-01

    The antiamoebic effect of a crude drug formulation against Entamoeba histolytica was studied. In the traditional system of medicine in India, the formulation has been prescribed for intestinal disorders. It comprises of five medicinal herbs, namely, Boerhavia diffusa, Berberis aristata, Tinospora cordifolia, Terminalia chebula and Zingiber officinale. The dried and pulverized plants were extracted in ethanol together and individually. In vitro amoebicidal activity was studied to determine the minimal inhibitory concentration (MIC) values of all the constituent extracts as well as the whole formulation. The formulation had a MIC of 1000 micrograms/ml as compared with 10 micrograms/ml for metronidazole. In experimental caecal amoebiasis in rats the formulation had a curative rate of 89% with the average degree of infection (ADI) reduced to 0.4 in a group dosed with 500 mg/kg per day as compared with ADI of 3.8 for the sham-treated control group of rats. Metronidazole had a cure rate of 89% (ADI = 0.4) at a dose of 100 mg/kg per day and cured the infection completely (ADI = 0) when the dosage was doubled to 200 mg/kg per day. There were varying degrees of inhibition of the following enzyme activities of crude extracts of axenically cultured amoebae: DNase, RNase, aldolase, alkaline phosphatase, acid phosphatase, alpha-amylase and protease.

  16. Effects of External Distur-bance on Soil Protozoa Abundance%外来扰动对土壤原生动物丰富度的影响

    Institute of Scientific and Technical Information of China (English)

    周乘波; 张四海

    2015-01-01

    In order to study the effect of external disturbance on abundance of flagellate, ciliate and amoeba in the soil, the study took the soil of QingYuan BaiShanZu Nature Reserve as samples, and set up three different external dis-turbance degree including respectively without disturbed area (W), without-ex-ternal disturbed area (W-Y), external disturbed area (Y). Every area got four specimens. The results were as follows:the protozoan total abundance in W-Y area reached the maximum (21368.8 a/g soil), that in Y area was the middle (18733.0 a/g soil), and that in W area was the minimum (15418.0a/g soil). Ap-propriate external disturbance was bene-ficial to increase protozoa total abun-dance and the abundance of flagellate, ciliates and amoeba, respectively. The increased amount of ciliate was the biggest, and the smallest was flagellate. With the improvement of protozoa total abundance, protozoan community struc-ture was also changed.%为研究不同程度的外来干扰对土壤中鞭毛虫、纤毛虫和肉足虫丰富度的影响,以丽水庆元百山祖自然保护区的土样作为测试土样,设置3个梯度的不同外来干扰程度:无人扰动区(W)、无人-外来扰动交汇区(W-Y)和外来扰动区(Y),每个梯度取4个样,研究土壤中鞭毛虫、纤毛虫、肉足虫的总丰富度、相对丰度以及群落结构.结果表明:W-Y区原生动物的总丰富度最大,为21368.8个/g土,其次是Y区,为18733.0个/g,W区最低,为15418.0个/g土;适当外来扰动,有利于原生动物总丰富度及鞭毛虫、纤毛虫和肉足虫的丰富度增加,其中以纤毛虫增幅最大,鞭毛虫增幅最小.随着原生动物总丰富度的提高,原生动物的群落结构也有所改变.

  17. Prey-predator dynamics in communities of culturable soil bacteria and protozoa: differential effects of mercury

    DEFF Research Database (Denmark)

    Holtze, M. S.; Ekelund, F.; Rasmussen, Lasse Dam;

    2003-01-01

    with 1/100 TSB as growth medium were also negatively affected by Hg. The different fractions of protozoa were affected to different degrees suggesting that amoebae were less sensitive than slow-growing flagellates, which again were less sensitive than the fast-growing flagellates. In contrast, Hg did...

  18. Pathogenic and nonpathogenic Acanthamoeba spp. in thermally polluted discharges and surface waters

    Energy Technology Data Exchange (ETDEWEB)

    de Jonckheere, J.F.

    1981-02-01

    During spring and autumn, the total number of amoebae and the number of acanthamoeba species able to grow at 37 degrees C were determined in six thermally polluted factory discharges and the surrounding surface waters. The isolated Acanthamoeba strains were studied for growth in axenic medium, cytopathic effect in Vito cell cultures, and virulence in mice. Although more amoebae were isolated in autumn, the number of Acanthamoeba species was lower than in spring, when the percent of pathogenic strains among the isolates was highest. Higher concentrations of amoebae were found in warm discharges, and more virulent strains occurred in thermal discharges than in surface waters.

  19. Intranasal coadministration of Cholera toxin with amoeba lysates modulates the secretion of IgA and IgG antibodies, production of cytokines and expression of pIgR in the nasal cavity of mice in the model of Naegleria fowleri meningoencephalitis.

    Science.gov (United States)

    Carrasco-Yepez, Maricela; Campos-Rodriguez, Rafael; Lopez-Reyes, Israel; Bonilla-Lemus, Patricia; Rodriguez-Cortes, Antonio Yahve; Contis-Montes de Oca, Arturo; Jarillo-Luna, Adriana; Miliar-Garcia, Angel; Rojas-Hernandez, Saul

    2014-11-01

    The nasal mucosa is the first contact with antigens to induce IgA response. The role of this site has rarely been studied. We have shown than intranasal administration with Naegleria fowleri lysates plus Cholera toxin (CT) increased the protection (survival up to 100%) against N. fowleri infection in mice and apparently antibodies IgA and IgG together with polymorphonuclear (PMN) cells avoid the attachment of N. fowleri to apical side of the nasal epithelium. We also observed that nasal immunization resulted in the induction of antigen-specific IgG subclasses (IgG1 and IgG2a) in nasal washes at days 3 and 9 after the challenge and IgA and IgG in the nasal cavity, compared to healthy and infected mice. We found that immunization with both treatments, N. fowleri lysates plus CT or CT alone, increased the expression of the genes for alpha chain, its receptor (pIgR), and it also increased the expression of the corresponding proteins evidenced by the ∼65 and ∼74kDa bands, respectively. Since the production of pIgR, IgA and IgG antibodies, is up-regulated by some factors, we analyzed the expression of genes for IL-10, IL-6, IFN-γ, TNF-α and IL-1β by using RT-PCR of nasal passages. Immunization resulted in an increased expression of IL-10, IL-6, and IFN-γ cytokines. We also aimed to examine the possible influences of immunization and challenge on the production of inflammatory cytokines (TNF-α and IL-1β). We observed that the stimulus of immunization inhibits the production of TNF-α compared to the infected group where the infection without immunization causes an increase in it. Thus, it is possible that the coexistence of selected cytokines produced by our immunization model may provide a highly effective immunological environment for the production of IgA, IgG and pIgR as well as a strong activation of the PMN in mucosal effector tissue such as nasal passages.

  20. Is Swimming Safe in Areas with the Freshwater 'Brain-Eating' Amoeba?

    Science.gov (United States)

    ... a 2015 study in the Journal of the Pediatric Infectious Diseases Society said. "Considering the millions of times that ... low risk," agreed Dr. Sunil Sood, chair of Pediatrics-Infectious Disease at Southside Hospital, in Bay Shore, N.Y. ...

  1. Charles Darwin meets Amoeba economicus: why natural selection cannot explain rationality

    OpenAIRE

    Elias L. Khalil

    2006-01-01

    Advocates of natural selection usually regard rationality as redundant, i.e., as a mere linguistic device to describe natural selection. But this “Redundancy Thesis” faces the anomaly that rationality differs from natural selection. One solution is to conceive rationality as a trait selected by the neo-Darwinian mechanism of natural selection as . But this “Rationality-qua-Trait Thesis” faces a problem as well: Following neo-Darwinism, one cannot classify one allele of, e.g., eyesight as bett...

  2. Amitochondriate amoebae and the evolution of DNA-dependent RNA polymerase II

    OpenAIRE

    Stiller, John W.; Duffield, Ellen C. S.; Hall, Benjamin D.

    1998-01-01

    Unlike parasitic protist groups that are defined by the absence of mitochondria, the Pelobiontida is composed mostly of free-living species. Because of the presence of ultrastructural and cellular features that set them apart from all other eukaryotic organisms, it has been suggested that pelobionts are primitively amitochondriate and may represent the earliest-evolved lineage of extant protists. Analyses of rRNA genes, however, have suggested that the group arose well after the diversificati...

  3. "道"与"术"的融通%About Amoeba Business Model

    Institute of Scientific and Technical Information of China (English)

    李平

    2011-01-01

    @@ 稻盛和夫在创业初期,既负责管理、又负责研发,还负责营销.可当公司发展到100人以上时,他感到心力文瘁、苦不堪言,曾经梦想有多个分身可以到公司重要部门承担责任.于是,他把公司细分成若干个所谓的"阿米巴",从内部选拔领导,赋予重任,后来惊奇的发现,原本被认为只能做杂工的人,逐渐成长为阿米巴的负责人,直至公司的核心领导.基于这种充分赋权模式的推广,京瓷公司也从个名不见经传的小作坊式工厂,实现跨越式发展进而成为世界500强企业之一.

  4. Generalized logarithmic Gauss map and its relation to (co)amoebas

    CERN Document Server

    Madani, Farid

    2012-01-01

    We define the generalized logarithmic Gauss map for algebraic varieties of the complex algebraic torus of any codimension. Moreover, we describe the set of critical points of the logarithmic mapping restricted to our variety, and we show an analogous of Mikhalkin's result on the critical points of the logarithmic map restricted to a hypersurfaces.

  5. Pandoraviruses: amoeba viruses with genomes up to 2.5 Mb reaching that of parasitic eukaryotes.

    Science.gov (United States)

    Philippe, Nadège; Legendre, Matthieu; Doutre, Gabriel; Couté, Yohann; Poirot, Olivier; Lescot, Magali; Arslan, Defne; Seltzer, Virginie; Bertaux, Lionel; Bruley, Christophe; Garin, Jérome; Claverie, Jean-Michel; Abergel, Chantal

    2013-07-19

    Ten years ago, the discovery of Mimivirus, a virus infecting Acanthamoeba, initiated a reappraisal of the upper limits of the viral world, both in terms of particle size (>0.7 micrometers) and genome complexity (>1000 genes), dimensions typical of parasitic bacteria. The diversity of these giant viruses (the Megaviridae) was assessed by sampling a variety of aquatic environments and their associated sediments worldwide. We report the isolation of two giant viruses, one off the coast of central Chile, the other from a freshwater pond near Melbourne (Australia), without morphological or genomic resemblance to any previously defined virus families. Their micrometer-sized ovoid particles contain DNA genomes of at least 2.5 and 1.9 megabases, respectively. These viruses are the first members of the proposed "Pandoravirus" genus, a term reflecting their lack of similarity with previously described microorganisms and the surprises expected from their future study.

  6. 变形虫的设计概念%Design Concept of Amoeba Graphic

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    小孩玩游戏,似乎是天经地义的事.而成人就须必恭必敬地工作,游戏之乐,似乎也只能仅存于对幼时的回忆中。大多数人对童年都满是美好回忆,向往着重新回到那个无拘无束的世界里:没有压力、没有围城,没有负担、没有竞争;满是欢乐、满是笑声、满是挂满泪花却依然灿烂的笑颜;我们曾轻而易举地

  7. Did terrestrial diversification of amoebas (amoebozoa occur in synchrony with land plants?

    Directory of Open Access Journals (Sweden)

    Omar Fiz-Palacios

    Full Text Available Evolution of lineage diversification through time is an active area of research where much progress has been made in the last decade. Contrary to the situation in animals and plants little is known about how diversification rates have evolved in most major groups of protist. This is mainly due to uncertainty about phylogenetic relationships, scarcity of the protist fossil record and the unknown diversity within these lineages. We have analyzed the evolutionary history of the supergroup Amoebozoa over the last 1000 million years using molecular dating and species number estimates. After an origin in the marine environment we have dated the colonization of terrestrial habitats by three distinct lineages of Amoebozoa: Dictyostelia, Myxogastria and Arcellinida. The common ancestor of the two sister taxa, Dictyostelia and Myxogastria, appears to have existed before the colonization of land by plants. In contrast Arcellinida seems to have diversify in synchrony with land plant radiation, and more specifically with that of mosses. Detection of acceleration of diversification rates in Myxogastria and Arcellinida points to a co-evolution within the terrestrial habitats, where land plants and the amoebozoans may have interacted during the evolution of these new ecosystems.

  8. FYVE-dependent endosomal targeting of an arrestin-related protein in amoeba.

    Directory of Open Access Journals (Sweden)

    Dorian Guetta

    Full Text Available BACKGROUND: Visual and β-arrestins are scaffolding proteins involved in the regulation of receptor-dependent intracellular signaling and their trafficking. The arrestin superfamilly includes several arrestin domain-containing proteins and the structurally related protein Vps26. In Dictyostelium discoideum, the arrestin-domain containing proteins form a family of six members, namely AdcA to -F. In contrast to canonical arrestins, Dictyostelium Adc proteins show a more complex architecture, as they possess, in addition to the arrestin core, other domains, such as C2, FYVE, LIM, MIT and SAM, which potentially mediate selective interactions with either lipids or proteins. METHODOLOGY AND PRINCIPAL FINDINGS: A detailed analysis of AdcA has been performed. AdcA extends on both sides of the arrestin core, in particular by a FYVE domain which mediates selective interactions with PI(3P, as disclosed by intrinsic fluorescence measurements and lipid overlay assays. Localization studies showed an enrichment of tagged- and endogenous AdcA on the rim of early macropinosomes and phagosomes. This vesicular distribution relies on a functional FYVE domain. Our data also show that the arrestin core binds the ADP-ribosylation factor ArfA, the unique amoebal Arf member, in its GDP-bound conformation. SIGNIFICANCE: This work describes one of the 6 arrestin domain-containing proteins of Dictyostelium, a novel and atypical member of the arrestin clan. It provides the basis for a better understanding of arrestin-related protein involvement in trafficking processes and for further studies on the expanding roles of arrestins in eukaryotes.

  9. Monitoring for the Presence of Parasitic Protozoa and Free-living Amoebae in Drinking Water Plants

    Directory of Open Access Journals (Sweden)

    Amany Saad Amer.

    2012-07-01

    Full Text Available Contamination of drinking water by microorganisms represents a major human health hazard in many parts of the world. The main objective of drinking water treatment is to provide microbiologically safe drinking water. The conventional drinking water treatment and disinfection has proved to be one of the major public health advances in modern times. A number of processes; namely water treatment, disinfection and changes influence the quality of drinking water delivered to the customer’s tap during transport of treated water via the distribution system. At least 325 water-associated outbreaks of parasitic protozoan disease have reported. In this study, drinking water from treatment plants evaluated for the presence of parasitic protozoa. Water samples collected from two main points: (a outlet of the water treatment plants (b distribution system at different distances from the water treatment plants. Protozoa were concentrated from each water sample by adsorption and accumulation on the nitrocellulose membrane filters (0.45 μm pore size and detected by conventional staining methods.

  10. How social evolution theory impacts our understanding of development in the social amoeba Dictyostelium.

    Science.gov (United States)

    Strassmann, Joan E; Queller, David C

    2011-05-01

    Dictyostelium discoideum has been very useful for elucidating principles of development over the last 50 years, but a key attribute means there is a lot to be learned from a very different intellectual tradition: social evolution. Because Dictyostelium arrives at multicellularity by aggregation instead of through a single-cell bottleneck, the multicellular body could be made up of genetically distinct cells. If they are genetically distinct, natural selection will result in conflict over which cells become fertile spores and which become dead stalk cells. Evidence for this conflict includes unequal representation of two genetically different clones in spores of a chimera, the poison-like differentiation inducing factor (DIF) system that appears to involve some cells forcing others to become stalk, and reduced functionality in migrating chimeras. Understanding how selection operates on chimeras of genetically distinct clones is crucial for a comprehensive view of Dictyostelium multicellularity. In nature, Dictyostelium fruiting bodies are often clonal, or nearly so, meaning development will often be very cooperative. Relatedness levels tell us what benefits must be present for sociality to evolve. Therefore it is important to measure relatedness in nature, show that it has an impact on cooperation in the laboratory, and investigate genes that Dictyostelium uses to discriminate between relatives and non-relatives. Clearly, there is a promising future for research at the interface of development and social evolution in this fascinating group.

  11. Identification of Pif1 helicases with novel accessory domains in various amoebae.

    Science.gov (United States)

    Harman, Ashley; Manna, Sam

    2016-10-01

    Pif1 helicases are a conserved family of eukaryotic proteins involved in the maintenance of both nuclear and mitochondrial DNA. These enzymes possess a number of known and putative functions, which facilitate overall genome integrity. Here we have identified multiple subtypes of Pif1 proteins in various pathogenic and non-pathogenic amoeboid species which possess additional domains not present in other Pif1 helicases. These helicases each possess one of five different accessory domains, which have roles in ubiquitination, origin of DNA replication recognition or single-stranded nucleic acid binding activity. Using a robust phylogenetic approach we examined each Pif1 class, which revealed that gene duplication, fusion and horizontal gene transfer events have all contributed to the evolution of these enzymes. This study has identified the first collection of Pif1 helicases to contain additional domains, which likely confer novel enzymatic activity, or improve existing functionality. Furthermore, the potential functions of these helicases may shed further light on the overall role the Pif1 family plays in genome maintenance. PMID:27421564

  12. Variation, sex, and social cooperation: molecular population genetics of the social amoeba Dictyostelium discoideum.

    Directory of Open Access Journals (Sweden)

    Jonathan M Flowers

    2010-07-01

    Full Text Available Dictyostelium discoideum is a eukaryotic microbial model system for multicellular development, cell-cell signaling, and social behavior. Key models of social evolution require an understanding of genetic relationships between individuals across the genome or possibly at specific genes, but the nature of variation within D. discoideum is largely unknown. We re-sequenced 137 gene fragments in wild North American strains of D. discoideum and examined the levels and patterns of nucleotide variation in this social microbial species. We observe surprisingly low levels of nucleotide variation in D. discoideum across these strains, with a mean nucleotide diversity (pi of 0.08%, and no strong population stratification among North American strains. We also do not find any clear relationship between nucleotide divergence between strains and levels of social dominance and kin discrimination. Kin discrimination experiments, however, show that strains collected from the same location show greater ability to distinguish self from non-self than do strains from different geographic areas. This suggests that a greater ability to recognize self versus non-self may arise among strains that are more likely to encounter each other in nature, which would lead to preferential formation of fruiting bodies with clonemates and may prevent the evolution of cheating behaviors within D. discoideum populations. Finally, despite the fact that sex has rarely been observed in this species, we document a rapid decay of linkage disequilibrium between SNPs, the presence of recombinant genotypes among natural strains, and high estimates of the population recombination parameter rho. The SNP data indicate that recombination is widespread within D. discoideum and that sex as a form of social interaction is likely to be an important aspect of the life cycle.

  13. Electrophoretic isoenzyme patterns of the pathogenic and non-pathogenic intestinal amoebae of man.

    Science.gov (United States)

    Sargeaunt, P G; Williams, J E

    1979-01-01

    Cultured stocks of Entamoeba hartmanni, Endolimax nana, Iodamoeba buetschlli and Dientamoeba fragilis were compared with the four Entamoeba histolytical groups already described (SARGEAUNT et al., 1978), by the electrophoretic patterns of three enzymes: glucose phosphate isomerase (GPI), phosphoglucomutase (PGM) and L-malate: NADP+ oxidoreductase (oxalacetate-decarboxylating) (ME). All the species were easily distinguished by their characteristic patterns. PMID:473310

  14. Testate amoebae (Protozoa: Rhizopoda of Deepor Beel (a Ramsar site, Assam, northeastern India

    Directory of Open Access Journals (Sweden)

    B.K. Sharma

    2011-07-01

    Full Text Available Twenty-one species of Rhizopoda belonging to eight genera and six families were documented from Deepor Beel, an important floodplain lake of the Brahmaputra River basin, showing the richest diversity of testaceans known to date from any freshwater ecosystem in India. Two species are new records from Assam, while all species are new to this Ramsar site. Our results show a Lobosea/Filosea ratio of 2.0, qualitative importance of Euglyphidae and Centropyxidae = Difflugidae and species richness of Difflugia a; Centropyxis.

  15. Cytopathic changes and pro-inflammatory cytokines induced by Naegleria fowleri trophozoites in rat microglial cells and protective effects of an anti-Nfa1 antibody.

    Science.gov (United States)

    Oh, Y-H; Jeong, S-R; Kim, J-H; Song, K-J; Kim, K; Park, S; Sohn, S; Shin, H-J

    2005-12-01

    Naegleria fowleri, a free-living amoeba, causes fatal primary amoebic meningoencephalitis in experimental animals and humans. The nfa1 gene (360 bp) was previously cloned from a cDNA library of pathogenic N. fowleri by immunoscreening, and produced a 13.1-kDa recombinant protein that showed pseudopodia-specific localization by immunocytochemistry. On the basis of an idea that the pseudopodia-specific Nfa1 protein seems to be involved in the pathogenicity of N. fowleri, the cytopathic activity of N. fowleri trophozoites co-cultured with rat microglial cells was observed, and the effects of an anti-Nfa1 antibody in a co-culture system were elucidated. Using light, scanning and transmission electron microscopy, it was seen that N. fowleri trophozoites in contact with microglial cells produced vigorous pseudopodia and a food-cup structure. Microglial cells were destroyed by N. fowleri trophozoites as seen from necrotic cell death in a time-dependent manner. In a(51)Cr release assay, N. fowleri showed 17.8%, 24.9%, 54.6% and 98% cytotoxicity against microglial cells at 3, 6, 12 and 24 h post-incubation, respectively. However, when anti-Nfa1 antibody was added in a coculture system, N. fowleri cytotoxicity was reduced to 15.5%, 20.3%, 46.7% and 66.9%, respectively. Moreover, microglial cells co-cultured with N. fowleri trophozoites secreted the pro-inflammatory cytokines, TNF-alpha, IL-1beta and IL-6. In the presence of anti-Nfa1 antibody, the secretion of TNF-alpha was slightly, but not significantly, decreased.

  16. Effectiveness of a dynein team in a tug of war helped by reduced load sensitivity of detachment: evidence from the study of bidirectional endosome transport in D. discoideum

    International Nuclear Information System (INIS)

    Bidirectional cargo transport by molecular motors in cells is a complex phenomenon in which the cargo (usually a vesicle) alternately moves in retrograde and anterograde directions. In this case, teams of oppositely pulling motors (e.g., kinesin and dynein) bind to the cargo, simultaneously, and ‘coordinate’ their activity such that the motion consists of spells of positively and negatively directed segments, separated by pauses of varying duration. A set of recent experiments have analyzed the bidirectional motion of endosomes in the amoeba D. discoideum in detail. It was found that in between directional switches, a team of five to six dyneins stall a cargo against a stronger kinesin in a tug of war, which lasts for almost a second. As the mean detachment time of a kinesin under its stall load was also observed to be ∼1 s, we infer that the collective detachment time of the dynein assembly must also be similar. Here, we analyze this inference from a modeling perspective, using experimentally measured single-molecule parameters as inputs. We find that the commonly assumed exponential load-dependent detachment rate is inconsistent with observations, as it predicts that a five-dynein assembly will detach under its combined stall load in less than a hundredth of a second. A modified model where the load-dependent unbinding rate is assumed to saturate at stall-force level for super-stall loads gives results which are in agreement with experimental data. Our analysis suggests that the load-dependent detachment of a dynein in a team is qualitatively different at sub-stall and super-stall loads, a conclusion which is likely to have implications in other situations involving collective effects of many motors. (paper)

  17. Effect of high levels of the rotifer Lecane inermis on the ciliate community in laboratory-scale sequencing batch bioreactors (SBRs).

    Science.gov (United States)

    Fyda, Janusz; Babko, Roman; Fiałkowska, Edyta; Pajdak-Stós, Agnieszka; Kocerba-Soroka, Wioleta; Sobczyk, Mateusz; Sobczyk, Łukasz

    2015-10-01

    Due to its ability to feed on filamentous bacteria, the rotifer Lecane inermis has already been recognized as a potential control agent of activated sludge bulking, which is usually caused by the excessive growth of filamentous microorganisms. However, their effectiveness depends, in part, on their abundance. We studied the influence of high densities of L. inermis on the protozoan community in activated sludge from a wastewater treatment plant (WWTP) in 4 laboratory-scale sequencing batch bioreactors (SBRs). Two treatments and two controls were subjected to nutrient removal system in process similar to that used in a WWTP. The experiment lasted 9 days and was repeated in 24-h cycles, including phases of agitation with feeding, aeration and agitation and sedimentation with decantation at the end of the cycle. In total, 32 taxa were identified, among which 25 were ciliated protozoa, 4 were amoebae, 2 were flagellates, and one was a nematode. Rotifers were then introduced to 2 bioreactors at a final concentration of 500ind.mL(-1), and the taxonomic composition and abundance of the activated sludge microfauna were assessed 2, 5 and 8 days thereafter. The mean density of ciliates on the first day of experiment was 12,610ind.mL(-1) and diminished to 4868±432ind.mL-±432ind.mL(-1) in the control and 5496±638ind.mL(-1) in the rotifer-treated group on the last day. Thus, even extremely high densities of artificially introduced rotifers did not negatively affect the protozoan community. On the contrary, the protozoan community was more diverse in the treatment group than in the control.

  18. The interplay between Entamoeba and enteropathogenic bacteria modulates epithelial cell damage.

    Directory of Open Access Journals (Sweden)

    José Manuel Galván-Moroyoqui

    Full Text Available BACKGROUND: Mixed intestinal infections with Entamoeba histolytica, Entamoeba dispar and bacteria with exacerbated manifestations of disease are common in regions where amoebiasis is endemic. However, amoeba-bacteria interactions remain largely unexamined. METHODOLOGY: Trophozoites of E. histolytica and E. dispar were co-cultured with enteropathogenic bacteria strains Escherichia coli (EPEC, Shigella dysenteriae and a commensal Escherichia coli. Amoebae that phagocytosed bacteria were tested for a cytopathic effect on epithelial cell monolayers. Cysteine proteinase activity, adhesion and cell surface concentration of Gal/GalNAc lectin were analyzed in amoebae showing increased virulence. Structural and functional changes and induction of IL-8 expression were determined in epithelial cells before and after exposure to bacteria. Chemotaxis of amoebae and neutrophils to human IL-8 and conditioned culture media from epithelial cells exposed to bacteria was quantified. PRINCIPAL FINDINGS: E. histolytica digested phagocytosed bacteria, although S. dysenteriae retained 70% viability after ingestion. Phagocytosis of pathogenic bacteria augmented the cytopathic effect of E. histolytica and increased expression of Gal/GalNAc lectin on the amoebic surface and increased cysteine proteinase activity. E. dispar remained avirulent. Adhesion of amoebae and damage to cells exposed to bacteria were increased. Additional increases were observed if amoebae had phagocytosed bacteria. Co-culture of epithelial cells with enteropathogenic bacteria disrupted monolayer permeability and induced expression of IL-8. Media from these co-cultures and human recombinant IL-8 were similarly chemotactic for neutrophils and E. histolytica. CONCLUSIONS: Epithelial monolayers exposed to enteropathogenic bacteria become more susceptible to E. histolytica damage. At the same time, phagocytosis of pathogenic bacteria by amoebae further increased epithelial cell damage. SIGNIFICANCE

  19. Cryptococcal 3-Hydroxy Fatty Acids Protect Cells Against Amoebal Phagocytosis.

    Science.gov (United States)

    Madu, Uju L; Ogundeji, Adepemi O; Mochochoko, Bonang M; Pohl, Carolina H; Albertyn, Jacobus; Swart, Chantel W; Allwood, J William; Southam, Andrew D; Dunn, Warwick B; May, Robin C; Sebolai, Olihile M

    2015-01-01

    We previously reported on a 3-hydroxy fatty acid that is secreted via cryptococcal capsular protuberances - possibly to promote pathogenesis and survival. Thus, we investigated the role of this molecule in mediating the fate of Cryptococcus (C.) neoformans and the related species C. gattii when predated upon by amoebae. We show that this molecule protects cells against the phagocytic effects of amoebae. C. neoformans UOFS Y-1378 (which produces 3-hydroxy fatty acids) was less sensitive toward amoebae compared to C. neoformans LMPE 046 and C. gattii R265 (both do not produce 3-hydroxy fatty acids) and addition of 3-hydroxy fatty acids to C. neoformans LMPE 046 and C. gattii R265 culture media, causes these strains to become more resistant to amoebal predation. Conversely, addition of aspirin (a 3-hydroxy fatty acid inhibitor) to C. neoformans UOFS Y-1378 culture media made cells more susceptible to amoebae. Our data suggest that this molecule is secreted at a high enough concentration to effect intracellular signaling within amoeba, which in turn, promotes fungal survival.

  20. Cryptococcal 3-hydroxy fatty acids protect cells against amoebal phagocytosis

    Directory of Open Access Journals (Sweden)

    Uju Lynda Madu

    2015-12-01

    Full Text Available We previously reported on a 3-hydroxy fatty acid that is secreted via cryptococcal capsular protuberances - possibly to promote pathogenesis and survival. Thus, we investigated the role of this molecule in mediating the fate of Cryptococcus (C. neoformans and the related species C. gattii when predated upon by amoebae. We show that this molecule protects cells against the phagocytic effects of amoebae. C. neoformans UOFS Y-1378 (which produces 3-hydroxy fatty acids was less sensitive towards amoebae compared to C. neoformans LMPE 046 and C. gattii R265 (both do not produce 3-hydroxy fatty acids and addition of 3-hydroxy fatty acids to C. neoformans LMPE 046 and C. gattii R265 culture media, causes these strains to become more resistant to amoebal predation. Conversely, addition of aspirin (a 3-hydroxy fatty acid inhibitor to C. neoformans UOFS Y-1378 culture media made cells more susceptible to amoebae. Our data suggest that this molecule is secreted at a high enough concentration to effect intracellular signalling within amoeba, which in turn, promotes fungal survival.

  1. Species-specific immunity induced by infection with Entamoeba histolytica and Entamoeba moshkovskii in mice.

    Science.gov (United States)

    Shimokawa, Chikako; Culleton, Richard; Imai, Takashi; Suzue, Kazutomo; Hirai, Makoto; Taniguchi, Tomoyo; Kobayashi, Seiki; Hisaeda, Hajime; Hamano, Shinjiro

    2013-01-01

    Entamoeba histolytica, the parasitic amoeba responsible for amoebiasis, causes approximately 100,000 deaths every year. There is currently no vaccine against this parasite. We have previously shown that intracecal inoculation of E. histolytica trophozoites leads to chronic and non-healing cecitis in mice. Entamoeba moshkovskii, a closely related amoeba, also causes diarrhea and other intestinal disorders in this model. Here, we investigated the effect of infection followed by drug-cure of these species on the induction of immunity against homologous or heterologous species challenge. Mice were infected with E. histolytica or E. moshkovskii and treated with metronidazole 14 days later. Re-challenge with E. histolytica or E. moshkovskii was conducted seven or 28 days following confirmation of the clearance of amoebae, and the degree of protection compared to non-exposed control mice was evaluated. We show that primary infection with these amoebae induces a species-specific immune response which protects against challenge with the homologous, but not a heterologous species. These findings pave the way, therefore, for the identification of novel amoebae antigens that may become the targets of vaccines and provide a useful platform to investigate host protective immunity to Entamoeba infections.

  2. Characterization of Entamoeba histolytica-induced dephosphorylation in Jurkat cells

    Indian Academy of Sciences (India)

    J E Teixeira; B J Mann

    2002-11-01

    Entamoeba histolytica killing of host cells is contact dependent and mediated by a Gal/GalNAc lectin. Upon contact with amoeba a rapid and extensive dephosphorylation of tyrosine phosphorylated host cell proteins is observed. This effect is mediated by the Gal/GalNAc lectin. However, it requires intact cells, as purified lectin failed to induce dephosphorylation in Jurkat cells. The nonpathogenic, but morphologically identical amoeba, Entamoeba moshkovskii also did not induce dephosphorylation in target cells. Treatment of Jurkat cells with phosphotyrosine phosphatase inhibitors has shown that a host phosphatase is responsible for dephosphorylation. However, it was found that the CD45 phosphotase was not necessary for dephosphorylation of host cell proteins.

  3. Chemotherapy Effects

    Science.gov (United States)

    ... saved articles window. My Saved Articles » My ACS » Chemotherapy Side Effects Chemotherapy drugs are powerful medicines that can cause side ... on the side effects most commonly caused by chemotherapy, this is a good place to start. Managing ...

  4. Placebo Effect

    Science.gov (United States)

    ... David C. Spencer, MD Steven Karceski, MD The placebo effect Joseph H. Friedman, MD Richard Dubinsky, MD ... truly effective, it is often compared to a placebo. WHAT IS A PLACEBO? Placebos are usually thought ...

  5. The abundant free-living amoeba, Acanthamoeba polyphaga, increases the survival of Campylobacter jejuni in milk and orange juice

    OpenAIRE

    Olofsson, Jenny; Griekspoor Berglund, Petra; Olsen, Björn; Ellström, Patrik; Axelsson-Olsson, Diana

    2015-01-01

    Background: Campylobacter jejuni is a common cause of human bacterial diarrhea in most parts of the world. Most C. jejuni infections are acquired from contaminated poultry, milk, and water. Due to health care costs and human suffering, it is important to identify all possible sources of infection. Unpasteurized milk has been associated with several outbreaks of C. jejuni infection. Campylobacter has been identified on fresh fruit, and other gastrointestinal pathogens such as Salmonella, E. co...

  6. Morphotypes in Naked Amoebas (Protista: Distribution in Water Bodies of Zhytomyr and Volyn Polissia (Ukraine and Possible Ecological Significance

    Directory of Open Access Journals (Sweden)

    Patsyuk M. K.

    2014-12-01

    Full Text Available Проанализированы биотопическое и сезонное распределения видов голых амёб, принадлежащих к определённым мор- фотипам, на территории Житомирского и Волынского Полесья. Показано, что политактический и в некоторой степени ругозный и разветвлённый морфотипы имеют адаптивное значение и могли сформироваться в результате адаптации к условиям, которые характерны для олиготрофных озёр. В свою очередь, формирование ланцетообразного морфотипа может быть связано с адаптацией к низким температурам воды, а фламельного - к высоким.

  7. FOUR CORE STRENGTH OF AMOEBA OPERATING%阿米巴管理的四项核心力量

    Institute of Scientific and Technical Information of China (English)

    覃文钊

    2011-01-01

    放弃“术”而探究“道”,才是学习管理的主要目标。众多企业都曾导入过阿米巴经营模式,凡是把它单纯地作为“术”引入的大都失败了,凡是把“道”和“术”相结合的都成功了。

  8. Naegleria fowleri: a free-living highly pathogenic amoeba contains trypanothione/trypanothione reductase and glutathione/glutathione reductase systems.

    Science.gov (United States)

    Ondarza, Raúl N; Hurtado, Gerardo; Tamayo, Elsa; Iturbe, Angélica; Hernández, Eva

    2006-11-01

    This paper presents definitive data showing that the thiol-bimane compound isolated and purified by HPLC from Naegleria fowleri trophozoites unequivocally corresponds by matrix assisted laser-desorption ionization-time-of-flight MS, to the characteristic monoprotonated ion of trypanothione-(bimane)(2) [M(+)H(+)] of m/z 1104.57 and to the trypanothione-(bimane) of m/z 914.46. The trypanothione disulfide T(S)(2) was also found to have a molecular ion of m/z 723.37. Additionally HPLC demonstrated that thiol-bimane compounds corresponding to cysteine and glutathione were present in Naegleria. The ion patterns of the thiol-bimane compounds prepared from commercial trypanothione standard, Entamoeba histolytica and Crithidia luciliae are identical to the Naegleria thiol-bimane compound. Partially purified extracts from N. fowleri showed the coexistence of glutathione and trypanothione reductases activities. There is not doubt that the thiol compound trypanothione, which was previously thought to occur only in Kinetoplastida, is also present in the human pathogens E. histolytica and N. fowleri, as well as in the non-pathogenic euglenozoan E. gracilis. The presence of the trypanothione/trypanothione reductase system in N. fowleri creates the possibility of using this enzyme as a new "drug target" for rationally designed drugs to eliminate the parasite, without affecting the human host.

  9. Your Garden Hose: A potential health risk due to Legionella spp. growth facilitated by free-living amoebae

    Science.gov (United States)

    Common garden hoses may generate aerosols of inhalable size (<10 um) during use. If aerosols are inhaled containing Legionella bacteria, Legionnaires' disease or Pontiac fever may result. Noting clinical cases have been linked to garden hose use. The hose environment is ideal ...

  10. The CRISPR-Associated Gene cas2 of Legionella pneumophila Is Required for Intracellular Infection of Amoebae

    OpenAIRE

    Felizza F Gunderson; Cianciotto, Nicholas P.

    2013-01-01

    ABSTRACT Recent studies have shown that the clustered regularly interspaced palindromic repeats (CRISPR) array and its associated (cas) genes can play a key role in bacterial immunity against phage and plasmids. Upon analysis of the Legionella pneumophila strain 130b chromosome, we detected a subtype II-B CRISPR-Cas locus that contains cas9, cas1, cas2, cas4, and an array with 60 repeats and 58 unique spacers. Reverse transcription (RT)-PCR analysis demonstrated that the entire CRISPR-Cas loc...

  11. Molecular differentiation of Entamoeba histolytica and Entamoeba dispar from Tunisian food handlers with amoeba infection initially diagnosed by microscopy.

    OpenAIRE

    Ben Ayed S.; Ben Abdallah R.; Mousli M.; Aoun K.; Thellier M.; Bouratbine A.

    2008-01-01

    The purpose of the study was to obtain more reliable epidemiological data concerning Entamoeba (E.) histolytica infection in Tunisian food handlers using established molecular tools able to differentiate E. histolytica from E. dispar. From 2002 to 2005, 4,266 fresh stools specimens received in the setting of the National program of food handlers' control were analysed by optical microscopy. Twelve (2.8 per thousand) were positive for the presence of four nuclei cysts identified as E. histolyt...

  12. Your Garden Hose: A potential health risk due to Legionella spp. growth facilitated by free-living amoebae

    Science.gov (United States)

    Common garden hoses may generate aerosols of inhalable size (Legionella bacteria, Legionnaires' disease or Pontiac fever may result. Noting clinical cases have been linked to garden hose use. The hose environment is ideal ...

  13. Molecular differentiation of Entamoeba histolytica and Entamoeba dispar from Tunisian food handlers with amoeba infection initially diagnosed by microscopy

    Directory of Open Access Journals (Sweden)

    Ben Ayed S.

    2008-03-01

    Full Text Available The purpose of the study was to obtain more reliable epidemiological data concerning Entamoeba (E. histolytica infection in Tunisian food handlers using established molecular tools able to differentiate E. histolytica from E. dispar. From 2002 to 2005, 4,266 fresh stools specimens received in the setting of the National program of food handlers’ control were analysed by optical microscopy. Twelve (2.8 ‰ were positive for the presence of four nuclei cysts identified as E. histolytica/E. dispar. Extraction of DNA from the 12 samples, followed by specific amplifications of E. histolytica and E. dispar SSU rDNA, showed that 11 samples (92% were positive for E. dispar and negative for E. histolytica. Sequencing analysis of 8 PCR products permitted to verify the results obtained with conventional PCR. The remaining sample was negative by PCR amplifying E. histolytica DNA or E. dispar DNA specifically, although it did not show any inhibition. It probably contains protozoan cysts genetically distinct from these two species but morphological similar. Estimation of relative proportions between E. histolytica and E. dispar in cyst carriers showed that all explored individuals harboured the non pathogenic E. dispar strains. This result highlights the need of use in this population of complementary tests that allow specific diagnosis and obviate unnecessary chemotherapy.

  14. Systems effectiveness

    CERN Document Server

    Habayeb, A R

    1987-01-01

    Highlights three principal applications of system effectiveness: hardware system evaluation, organizational development and evaluation, and conflict analysis. The text emphasizes the commonality of the system effectiveness discipline. The first part of the work presents a framework for system effectiveness, partitioning and hierarchy of hardware systems. The second part covers the structure, hierarchy, states, functions and activities of organizations. Contains an extended Appendix on mathematical concepts and also several project suggestions.

  15. "Further Effects"

    Science.gov (United States)

    Kinigstein, Steven Michael

    In writing Further Effects, I intended to illustrate the benefits that are to be had from the use of effects - processing, when applied at the compositional level, rather than as a post-compositional afterthought. When effects are used creatively in the compositional stage, they will influence the very nature of a piece. They are capable of expressing rhythmic and metric ideas. They can alter the natural timbre of an instrument. This can be done on levels of abstraction ranging from discreet subtlety to disguise beyond recognition. There is one effect (known as "pitch shift.") that allows an instrument to play pitches that are well outside of its range. In Further Effects, I direct the performers to use a volume pedal (which I view as a tool, rather than an effect) for the broadened creative use of dynamics that it so efficiently grants. The use of an effects processor and volume pedal creates a need for ancillary equipment. An amplifier, cables, and an electric hook-up (a microphone or a pickup) will be required for each instrument. While an amplifier serves to project the processed sound, there must also be a device or method to suppress unprocessed sound. A great deal of thought and work goes into the use of effects; yet I feel it is wasteful to use this musical resource merely as post-compositional decoration.

  16. Effective Parenting

    Science.gov (United States)

    ... come, like your child's school play and his soccer games. Your Current Parenting Experiences Spend some time ... and be unable to handle the tasks of running a family as effectively. Take a moment to ...

  17. Facebook Effect

    OpenAIRE

    STOICA, Anamaria

    2011-01-01

    This research paper is intended to understand the effects that Facebook, the social networking site has upon us, whether it influences our lives in a good or in a bad way. In order to understand the Facebook Effect we are trying to see how it impacts our lives at economic level,social level, political level, terminology level , psychological level and cultural level . Starting from the question : What does Facebook want? we found several answers consisting in pros and cons of this phenomenon ...

  18. Effective Programming

    DEFF Research Database (Denmark)

    Frost, Jacob

    To investigate the use of VTLoE as a basis for formal derivation of functional programs with effects. As a part of the process, a number of issues central to effective formal programming are considered. In particular it is considered how to develop a proof system suitable for pratical reasoning......, how to implement this system in the generic proof assistant Isabelle and finally how to apply the logic and the implementation to programming....

  19. Photodynamic inactivation of Acanthamoeba polyphaga with curcuminoids: an in vitro study

    Science.gov (United States)

    Corrêa, Thaila Q.; Geralde, Mariana C.; Carvalho, Mariana T.; Bagnato, Vanderlei S.; Kurachi, Cristina; de Souza, Clovis W. O.

    2016-03-01

    Acanthamoeba polyphaga are free-living amoebae that can be considered potentially pathogenic organisms by cause serious human infections, including keratitis and granulomatous amoebic encephalitis that usually results in death. Photodynamic inactivation (PDI) has been used for the biological control of microorganisms and can be promise in the control of Acanthamoeba infections. This study evaluated the in vitro effectiveness of PDI in A. polyphaga using curcuminoids salt as photosensitizer (PS) besides observing morphological changes caused by this PS in this organism, in confocal microscopy. A. polyphaga trophozoites were grown at 37°C in PYG medium for 48 to 72 hours. After, the trophozoites were incubated with PS solution during one hour and the samples were irradiated using light-emitting diodes at 460 nm at light doses 30 and 50 J/cm2. The results revealed reduction of 27.7%, 61.4% and 82.5% at 30 J/cm2 and 75.2%, 85.0% and 95.9% at 50 J/cm2, respectively, at curcuminoid salt concentrations of 500, 1000 and 1500 μg/mL. Through fluorescence images, it was possible to visualize the curcuminoid salt's uptake by the trophozoites. The PS showed toxicity to amoebae, in the dark, but the irradiation in PDI contributed to amoebae death effect. These data suggest that PDI may be an application of therapeutic intervention against Acanthamoeba infections, since it was effective in the inactivation of these amoebae.

  20. Effective nonvanishing, effective global generation

    CERN Document Server

    De Cataldo, M A A

    1997-01-01

    We prove a multiple-points higher-jets nonvanishing theorem by the use of local Seshadri constants. Applications are given to effectivity problems such as constructing rational and birational maps into Grassmannians, and the global generation of vector bundles.

  1. Treatment Effects

    DEFF Research Database (Denmark)

    Heckman, James J.; Lopes, Hedibert F.; Piatek, Rémi

    2014-01-01

    This paper contributes to the emerging Bayesian literature on treatment effects. It derives treatment parameters in the framework of a potential outcomes model with a treatment choice equation, where the correlation between the unobservable components of the model is driven by a low-dimensional v......This paper contributes to the emerging Bayesian literature on treatment effects. It derives treatment parameters in the framework of a potential outcomes model with a treatment choice equation, where the correlation between the unobservable components of the model is driven by a low...... observe the same person in both the treated and untreated states, but it also turns out to be straightforward to implement. Formulae are provided to compute mean treatment effects as well as their distributional versions. A Monte Carlo simulation study is carried out to illustrate how the methodology can...

  2. Relevance of the bioavailable fraction of DDT and its metabolites in freshwater sediment toxicity: New insight into the mode of action of these chemicals on Dictyostelium discoideum.

    Science.gov (United States)

    Sforzini, Susanna; Governa, Daniela; Boeri, Marta; Oliveri, Laura; Oldani, Alessandro; Vago, Fabio; Viarengo, Aldo; Borrelli, Raffaella

    2016-10-01

    In this work, the toxicity of lake sediments contaminated with DDT and its metabolites DDD and DDE (collectively, DDX) was evaluated with widely used toxicity tests (i.e., Vibrio fischeri, Daphnia magna, Pseudokirchneriella subcapitata, and Lumbriculus variegatus) and with the social amoeba Dictyostelium discoideum, a model organism that is also suitable for studying pollutant-induced alterations at the molecular and cellular levels. Although the DDX concentration in the sediments was high (732.5 ppb), the results suggested a minimal environmental risk; in fact, no evidence of harmful effects was found using the different bioassays or when we considered the results of more sensitive sublethal biomarkers in D. discoideum amoebae. In line with the biological results, the chemical data showed that the concentration of DDX in the pore water (in general a highly bioavailable phase) showed a minimal value (0.0071ppb). To confirm the importance of the bioavailability of the toxic chemicals in determining their biological effects and to investigate the mechanisms of DDX toxicity, we exposed D. discoideum amoebae to 732.5ppb DDX in water solution. DDX had no effect on cell viability; however, a strong reduction in amoebae replication rate was observed, which depended mainly on a reduction in endocytosis rate and on lysosomal and mitochondrial alterations. In the presence of a moderate and transient increase in reactive oxygen species, the glutathione level in DDX-exposed amoebae drastically decreased. These results highlight that studies of the bioavailability of pollutants in environmental matrices and their biological effects are essential for site-specific ecological risk assessment. Moreover, glutathione depletion in DDX-exposed organisms is a new finding that could open the possibility of developing new pesticide mixtures that are more effective against DDT-resistant malaria vectors. PMID:27340883

  3. Relationship between Legionella pneumophila and Acanthamoeba polyphaga: Physiological status and susceptibility to chemical inactivation

    Energy Technology Data Exchange (ETDEWEB)

    Barker, J.; Farrell, I. (Aston Univ., Aston Triangle, Birmingham (United Kingdom)); Brown, M.R.W.; Collier, P.J.; Gilbert, P. (Univ. of Manchester (United Kingdom))

    1992-08-01

    Survival studies were conducted on Legionella pneumophila cells that had been grown intracellulary in Acanthamoeba polyphaga and then exposed to polyhexamethylene biguanide (PHMB), benzisothiazolone (BIT), and 5-chloro-N-methylisothiazolone (CMIT). Susceptibilities were also determined for L. pneumophila grown under iron-sufficient and iron-depleted conditions. BIT was relatively ineffective against cells to PHMB and CMIT. The activities of all three biocides were greatly reduced against L. pneumophila grown in amoebae. PHMB (1 [times] MIC) gave 99.99% reductions in viability for cultures grown in broth within 6 h and no detectable survivors at 24 h but only 90 and 99.9% killing at 6 h and 24 h, respectively, for cells grown in amoebae. The antimicrobial properties of the three biocides against A. polyphaga were also determined. The majority of amoebae recovered from BIT treatment, but few, if any, survived CMIT treatment or exposure of PHMB. This study not only shows the profound effect that intra-amoebal growth has on the physiological status and antimicrobial susceptibility of L. pneumophila but also reveals PHMB to be a potential biocide for effective water treatment. In this respect, PHMB has significant activity, below its recommended use concentrations, against both the host amoeba and L. pneumophila.

  4. Ventilation Effectiveness

    DEFF Research Database (Denmark)

    Mundt, M.; Mathisen, H. M.; Moser, M.;

    Improving the ventilation effectiveness allows the indoor air quality to be significantly enhanced without the need for higher air changes in the building, thereby avoiding the higher costs and energy consumption associated with increasing the ventilation rates. This Guidebook provides easy...

  5. Communicating Effectively

    Science.gov (United States)

    The seventh module of the EPEC-O (Education in Palliative and End-of-Life Care for Oncology) Self-Study: Cultural Considerations When Caring for African Americans explores communication issues pertinent to African Americans with cancer and their health care providers, discusses strategies for culturally sensitive communication, and presents the SPIKES protocol, a practical framework for effective communication.

  6. Genetic effects

    International Nuclear Information System (INIS)

    In 1948-1953 a large scale field survey was conducted to investigate the possible genetic effects of A-bomb radiation on over 70,000 pregnancy terminations in the cities of Hiroshima and Nagasaki. The indices of possible genetic effect including sex ratio, birth weight, frequency of malformation, stillbirth, neonatal death, deaths within 9 months and anthropometric measurements at 9 months of age for these children were investigated in relation to their parent's exposure status to the A-bomb. There were no detectable genetic effects in this sample, except for a slight change in sex ratio which was in the direction to be expected if exposure had induced sex-linked lethal mutations. However, continued study of the sex ratio, based upon birth certificates in Hiroshima and Nagasaki for 1954-1962, did not confirm the earlier trend. Mortality in these children of A-bomb survivors is being followed using a cohort of 54,000 subjects. No clearly significant effect of parental exposure on survival of the children has been demonstrated up to 1972 (age 17 on the average). On the basis of the regression data, the minimal genetic doubling dose of this type of radiation for mutations resulting in death is estimated at 46 rem for the father and 125 rem for the mother. (auth.)

  7. Monitoring the Effects of Oil Sands Process-Affected Water (OSPW) on Thecamoebian Assemblages: An Experimental Approach

    Science.gov (United States)

    Christie, D. G.; McCarthy, F. F.; Penner, T.; MacKinnon, M. M.

    2009-05-01

    Thecamoebian (testate amoeba) assemblages have been shown to respond over short time periods to environmental conditions in aquatic reclamation options under development at oil sands operations in northeastern Alberta. This makes them a useful bio-monitoring tool for assessing reclamation success. Thecamoebian responses to Oil Sands Process Water (OSPW) have been monitored in the field at lacustrine and wetland test sites established by Syncrude Canada Ltd. and Suncor Energy Ltd. These field studies have confirmed that the generation times of testate amoebas is sufficiently rapid to permit the construction of a controlled laboratory experiment to be completed within one year, where controlled exposures of a natural assemblage of thecamoebians to OSPW can be undertaken to better understand the community responses to stressors We intend to culture these protists in the lab and monitor their response to different concentrations of OSPW in a controlled environment. Survival and changes in relative community composition (difflugiids vs. centropyxids) will be used to establish the dilution of OSPW in which thecameobians can survive and examine how a natural assemblage changes over time in response to increased concentrations of OSPW. This will assist in reclamation management in the Oil Sands region of Alberta.

  8. Health effects

    Energy Technology Data Exchange (ETDEWEB)

    Mahieu, L

    1998-07-01

    The main objectives of research in the field of health effects at the Belgian Nuclear Research Centre SCK-CEN are: (1) to study cancer mortality and morbidity in nuclear workers in Belgium; (2) to document the feasibility of retrospective cohort studies in Belgium; (3) to participate in the IARC study; (4) to elucidate the mechanisms of the effects of ionizing radiation on the mammalian embryo during the early phases of its development; (5) to assess the genetic risks of material exposure to ionizing radiation; (6) to elucidate the cellular mechanisms leading to brain damage after prenatal irradiation; (7) to advise authorities and to provide the general population with adequate information concerning the health risk arising from radiation exposure. Progress and major achievements in these topical areas for 1997 are reported.

  9. Tectonomagnetic effects

    Science.gov (United States)

    Johnston, M.

    1978-01-01

    Measurements of the actual stress within the Earth and its changes with time are very difficult. It is much easier to monitor the direct effects of this stress, such as ground strain, or the indirect effects, such as changes in resistivity, strain, changes in seismic velocity or changes in magnetic field, and so forth. The latter technique is one of the more promising methods for monitoring substantial volumes of the Earth's crust near active faults with only a few instruments. It derives from the piezomagnetic properties of rocks (that is, the change in rock magnetization and, therefore, local magnetic field due to a change in applied stress). AS stress and strain fields along active faults vary, these variations should be reflected in changing local magnetic fields. In particular, rapidly changing fields might be expected to occur just before a large earthquake.

  10. Thermal Effects.

    Science.gov (United States)

    Yan, Ming; Zhang, Panyue; Zeng, Guangming

    2016-10-01

    This review focuses on the research literatures published in 2015 relating to topics of thermal effects in water pollution control. This review is divided into the following sections: biological nitrogen and phosphorus removal, wastewater treatment for organic conversion, industrial wastewater treatment, anaerobic digestion of sewage sludge and solid waste, sludge biochar preparation and application, pyrolysis of sewage sludge, reduction heavy metal in sewage sludge and soil, and other issues of wastewater and sludge treatment. PMID:27620109

  11. Effective Teachers

    Directory of Open Access Journals (Sweden)

    Beverly A. King Miller

    2015-09-01

    Full Text Available This article focuses on the educational strategies that can be used to support female students of African descent in their persistence in science, technology, engineering, and mathematics (STEM education and careers. STEM careers have historically been White male and White female dominated, which has yielded an underrepresentation of those of African descent. Drawing from a grounded qualitative case study, the data used for this article share the responses of Afro-Caribbean females in STEM who have immigrated to the United States from the country of Panama. As Latinas, they are representative of the changing face in the American educational system—bilingual, multicultural, and of African descent. The strategies offered reflect their own teaching practices, their former teachers, or experiences with their children’s teachers. What emerged were descriptions of four strategies and behaviors of effective teachers that align with Ladson-Billings’s culturally relevant pedagogy and Gay’s culturally responsive teaching. Included in the findings are the high standards and expectations embodied by effective teachers that serve to positively inspire their students. Culturally responsive teachers create an atmosphere of learning that supports academic success, conveying their belief in their students’ ability based upon their own reflectivity. As the U.S. educational system continues to become multilingual and multicultural, there is need for strategies for the successful inclusion and progression of students in STEM educational pathways and careers. This will occur as teachers challenge themselves to be the agents of change in the lives of their students.

  12. Effective Area

    Directory of Open Access Journals (Sweden)

    Ehud Keinan

    2015-07-01

    Full Text Available This article defines a new term, Effective Area, K, of a given territory as a function of four independent parameters: its nominal acreage, A, the intellectual competence of its inhabitants, B, their social competence, C, and their global influence, D, using a simple formalism: K = A x B x C x D. This analysis demonstrates that in our current world any consideration of the physical area of a given territory is meaningless if the quality of its population is ignored. K is a much more useful parameter than A, certainly for political and economical considerations, explaining why claims for territorial expansion are placed low on the national ladder of priorities in the developed countries. In many respects, large geographical areas may become a burden rather than an advantage. Thus, the importance of armed conflicts over geographical territories, which have taken a dominant part of the entire human history, is fading away. Furthermore, although the global acreage is constant, the total effective area of planet Earth keeps growing, providing sufficient room for the growing human population.

  13. Shockingly effective

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Maurice

    2011-12-15

    This paper presents the Electropure technology developed by Ground Effects Environmental Services Inc. This electric-based, chemical-free technology can treat hydraulic fracturing flowback and is capable of removing almost 99% of the contaminants while simultaneously minimizing water transportation costs for the treated volume. The technology uses a two-stage, vacuum-enhanced electro-catalytic oxidation process to disrupt and remove contaminants like, guar gums, iron, scaling agents, suspended solids, and polymers found in frac water. It has successfully treated some of the most difficult to treat wastewater, including gel and hybrid frac water. The treated water can be reused in fracturing operations, which eliminates the need and cost to replace the treated volume with fresh water and simultaneously reduces greenhouse gas emissions. Although treated water using this technology cannot be compared to drinking water, it is more applicable for fracture operations and other industrial uses.

  14. Side Effects of Chemotherapy

    Science.gov (United States)

    ... Men Living with Prostate Cancer Side Effects of Chemotherapy Side Effects Urinary Dysfunction Bowel Dysfunction Erectile Dysfunction ... Side Effects of Hormone Therapy Side Effects of Chemotherapy Side Effects: When to Seek Help PSA Rising ...

  15. Artemisia annua L. as a plant with potential use in the treatment of acanthamoebiasis.

    Science.gov (United States)

    Derda, Monika; Hadaś, Edward; Cholewiński, Marcin; Skrzypczak, Łukasz; Grzondziel, Anna; Wojtkowiak-Giera, Agnieszka

    2016-04-01

    The treatment of acanthamoebiasis is a great problem. Most cerebral invasions end with death, and the treatment of ocular invasions is usually long-lasting and not very effective. Numerous plant extracts and substances isolated from plants, which are effective against trophozoites or cysts, have been studied in the treatment of acanthamoebiasis. However, no agents that are simultaneously effective against both developing forms of amoebae have been discovered yet. It seems that such a plant which fulfils both tasks is Artemisia annua L. Our studies showed that water, alcohol and chloroform extracts from the herb A. annua L. can be applied in general and local treatment or in combined therapy with antibiotics in the treatment of acanthamoebiasis. Extracts from this plant show not only in vitro but also in vivo effects. Studies carried out on experimental animals infected with amoebae show that the application of these extracts significantly prolongs the survival of the animals. PMID:26782959

  16. Physiological effects in aromatherapy

    OpenAIRE

    Tapanee Hongratanaworakit

    2004-01-01

    The effects of aromas on humans are divided into physiological and psychological effects. The physiological effect acts directly on the physical organism, the psychological effect acts via the sense of smell or olfactory system, which in turn may cause a physiological effect. This paper reviews on the physiological effects which are used for the evaluation of the effects of aromas. Physiological parameters, i.e. heart rate blood pressure, electrodermal activity, electroencephalogram, slow pot...

  17. The most common herbal medicines affecting Sarcomastigophora branches: a review study.

    Science.gov (United States)

    Bahmani, Mahmoud; Saki, Kourosh; Rafieian-Kopaei, Mahmoud; Karamati, Seyed Ahmad; Eftekhari, Zohre; Jelodari, Mahyar

    2014-09-01

    Parasitic diseases cause annual mortality of more than 200 thousand people. Currently many drugs are used to treat parasitic diseases; however, they are mostly expensive, toxic, with side effects and drug resistance. Medicinal plants have been shown to represent natural source of cheap drugs with low toxicity. In this review article, the most common and most effective herbal medicines on pathogenic protozoan Sarcomastigophora branches such as Trypanosoma, Leishmania, Amoeba, Trichomonas and Giardia were reviewed. The recently published papers about different drugs as well as herbal medicines as alternative for synthetic drugs were searched using scientific sites such as Medline, PubMed and Google Scholar. The used terms included: Medicinal plants, herbal medicine, protozoa, Trypanosoma, Sarcomastigophora branches, Leishmania, Amoeba, Trichomonas or Giardia.

  18. Intensional Effect Polymorphism

    OpenAIRE

    Long, Yuheng; Liu, Yu David; Rajan, Hridesh

    2015-01-01

    Type-and-effect systems are a powerful tool for program construction and verification. We describe intensional effect polymorphism, a new foundation for effect systems that integrates static and dynamic effect checking. Our system allows the effect of polymorphic code to be intensionally inspected through a lightweight notion of dynamic typing. When coupled with parametric polymorphism, the powerful system utilizes runtime information to enable precise effect reasoning, while at the same time...

  19. Physiological effects in aromatherapy

    Directory of Open Access Journals (Sweden)

    Tapanee Hongratanaworakit

    2004-01-01

    Full Text Available The effects of aromas on humans are divided into physiological and psychological effects. The physiological effect acts directly on the physical organism, the psychological effect acts via the sense of smell or olfactory system, which in turn may cause a physiological effect. This paper reviews on the physiological effects which are used for the evaluation of the effects of aromas. Physiological parameters, i.e. heart rate blood pressure, electrodermal activity, electroencephalogram, slow potential brain waves (contingent negativevariation, and eye blink rate or pupil functions, are used as indices for the measurement of the aroma effects

  20. The Singular Limit of a Chemotaxis-Growth System with General Initial Data

    CERN Document Server

    Alfaro, Matthieu

    2009-01-01

    We study the singular limit of a system of partial differential equations which is a model for an aggregation of amoebae subjected to three effects: diffusion, growth and chemotaxis. The limit problem involves motion by mean curvature together with a nonlocal drift term. We consider rather general initial data. We prove a generation of interface property and study the motion of interfaces. We also obtain an optimal estimate of the thickness and the location of the transition layer that develops.

  1. Acanthamoeba castellanii induces host cell death via a phosphatidylinositol 3-kinase-dependent mechanism

    OpenAIRE

    Sissons, James; Kim, Kwang Sik; Stins, Monique; Jayasekera, Samantha; Alsam, Selwa; Khan, Naveed Ahmed

    2005-01-01

    Granulomatous amoebic encephalitis due to Acanthamoeba castellanii is a serious human infection with fatal consequences, but it is not clear how the circulating amoebae interact with the blood-brain barrier and transmigrate into the central nervous system. We studied the effects of an Acanthamoeba encephalitis isolate belonging to the T1 genotype on human brain microvascular endothelial cells, which constitute the blood-brain barrier. Using an apoptosis-specific enzyme-linked immunosorbent as...

  2. Dictyostelium discoideum: a model for testing novel inhibitors of urokinase-type plasminogen activator

    OpenAIRE

    Thompson, Elinor

    2013-01-01

    The social amoeba Dictyostelium discoideum is a useful non-animal eukaryote for testing novel compounds and dissecting cell regulatory molecular networks. We used this model organism to investigate the effect of a series of arylboronic acids and pinacol esters on development, chemotaxis and viability. These compounds were studied in parallel by collaborators for serine protease and urokinase-type plasminogen activator (uPA) inhibition, both in vitro and in vivo. In those biochemical assays, t...

  3. The mirror effect and the spacing effect.

    Science.gov (United States)

    Murdock, Bennet

    2003-09-01

    In the mirror effect, there are fewer false negatives (misses) and false positives (false alarms) for rare (low-frequency) words than for common (high-frequency) words. In the spacing effect, recognition accuracy is positively related to the interval (spacing or lag) between two presentations of an item. These effects are related in that they are both manifestations of a leapfrog effect (a weaker item jumps over a stronger item). They seem to be puzzles for traditional strength theory and at least some current global-matching models. A computational strength-based model (EICL) is proposed that incorporates excitation, inhibition, and a closed-loop learning algorithm. The model consists of three nonlinear coupled stochastic difference equations, one each for excitation (x), inhibition (y), and context (z). Strength is the algebraic sum (i.e., s = x - y + z). These equations are used to form a toy lexicon that serves as a basis for the experimental manipulations. The model can simulate the mirror effect forced-choice inequalities and the spacing effect for single-item recognition, all parameters are random variables, and the same parameter values are used for both the mirror and the spacing effects. No parameter values varied with the independent variables (word frequency for the mirror effect, lag for the spacing effect), so the model, not the parameters, is doing the work. PMID:14620350

  4. Schwinger Effect, Hawking Radiation, and Unruh Effect

    CERN Document Server

    Kim, Sang Pyo

    2016-01-01

    We revisit the Schwinger effect in de Sitter, anti-de Sitter spaces and charged black holes, and explore the interplay between quantum electrodynamics and the quantum gravity effect at one-loop level. We then advance a thermal interpretation of the Schwinger effect in curved spacetimes. Finally, we show that the Schwinger effect in a near-extremal black hole differs from Hawking radiation of charged particles in a non-extremal black hole and is factorized into those in an anti-de Sitter space and a Rindler space with the surface gravity for acceleration.

  5. Schwinger Effect, Hawking Radiation, and Unruh Effect

    OpenAIRE

    Kim, Sang Pyo

    2016-01-01

    We revisit the Schwinger effect in de Sitter, anti-de Sitter spaces and charged black holes, and explore the interplay between quantum electrodynamics and the quantum gravity effect at one-loop level. We then advance a thermal interpretation of the Schwinger effect in curved spacetimes. Finally, we show that the Schwinger effect in a near-extremal black hole differs from Hawking radiation of charged particles in a non-extremal black hole and is factorized into those in an anti-de Sitter space...

  6. The Pinball Effect

    DEFF Research Database (Denmark)

    Hendricks, Vincent Fella; Wiewiura, Joachim Schmidt

    2016-01-01

    You might have heard of the bystander-effect, but what about the Pinball-effect, which disrupts your attention on important tasks?......You might have heard of the bystander-effect, but what about the Pinball-effect, which disrupts your attention on important tasks?...

  7. Biological effects of radiation

    International Nuclear Information System (INIS)

    This fourth chapter presents: cell structure and metabolism; radiation interaction with biological tissues; steps of the production of biological effect of radiation; radiosensitivity of tissues; classification of biological effects; reversibility, transmissivity and influence factors; pre-natal biological effects; biological effects in therapy and syndrome of acute irradiation

  8. Galvanomagnetic effects in graphene

    OpenAIRE

    Boiko, I. I.

    2010-01-01

    Galvanomagnetic effects in graphene Magnetoresistivity and Hole-effect were theoretically investigated for neutral and gated graphene. It is shown that in neutral graphene Hall-effect is totally absent. In gated, exactly monopolar graphene effect of magnetoresistivity vanishes; here Hall-constant does not involve any relaxation characteristic in contrast to result obtained for popular method of relaxation time approximation.

  9. Survival in amoeba--a major selection pressure on the presence of bacterial copper and zinc resistance determinants? Identification of a "copper pathogenicity island".

    Science.gov (United States)

    Hao, Xiuli; Lüthje, Freja L; Qin, Yanan; McDevitt, Sylvia Franke; Lutay, Nataliya; Hobman, Jon L; Asiani, Karishma; Soncini, Fernando C; German, Nadezhda; Zhang, Siyu; Zhu, Yong-Guan; Rensing, Christopher

    2015-07-01

    The presence of metal resistance determinants in bacteria usually is attributed to geological or anthropogenic metal contamination in different environments or associated with the use of antimicrobial metals in human healthcare or in agriculture. While this is certainly true, we hypothesize that protozoan predation and macrophage killing are also responsible for selection of copper/zinc resistance genes in bacteria. In this review, we outline evidence supporting this hypothesis, as well as highlight the correlation between metal resistance and pathogenicity in bacteria. In addition, we introduce and characterize the "copper pathogenicity island" identified in Escherichia coli and Salmonella strains isolated from copper- and zinc-fed Danish pigs.

  10. Evidence for an amoeba-like infectious stage of ichthyophonus sp. and description of a circulating blood stage: a probable mechanism for dispersal within the fish host

    Science.gov (United States)

    Kocan, Richard; LaPatra, Scott; Hershberger, Paul

    2013-01-01

    Small amoeboid cells, believed to be the infectious stage of Ichthyophonus sp., were observed in the bolus (stomach contents) and tunica propria (stomach wall) of Pacific staghorn sculpins and rainbow trout shortly after they ingested Ichthyophonus sp.–infected tissues. By 24–48 hr post-exposure (PE) the parasite morphed from the classically reported multinucleate thick walled schizonts to 2 distinct cell types, i.e., a larger multinucleate amoeboid cell surrounded by a narrow translucent zone and a smaller spherical cell surrounded by a “halo” and resembling a small schizont. Both cell types also appeared in the tunica propria, indicating that they had recently penetrated the columnar epithelium of the stomach. No Ichthyophonus sp. pseudo-hyphae (“germination tubes”) were observed in the bolus or penetrating the stomach wall. Simultaneously, Ichthyophonus sp. was isolated in vitro from aortic blood, which was consistently positive from 6 to 144 hr PE, then only intermittently for the next 4 wk. Small PAS-positive cells observed in blood cultures grew into colonies consisting of non-septate tubules (pseudo-hyphae) terminating in multinucleated knob-like apices similar to those seen in organ explant cultures. Organ explants were culture positive every day; however, typical Ichthyophonus sp. schizonts were not observed histologically until 20–25 days PE. From 20 to 60 days PE, schizont diameter increased from ≤25 μm to ≥82 μm. Based on the data presented herein, we are confident that we have resolved the life cycle of Ichthyophonus sp. within the piscivorous host.

  11. 一种适合于实验教学的阿米巴培养法%An Amoeba Culture Method Suitable for Experiments Teaching

    Institute of Scientific and Technical Information of China (English)

    林文萍

    2010-01-01

    @@ 在寄生虫检验实验教学中,溶组织内阿米巴形态多以染色标本片观察,而在临床中,却以活体标本诊断为主.为了让学生了解活体阿米巴伪足运动的特点,经多年探索,我们成功培养了自由阿米巴,而且培养方法简单,特别适合于实验教学.

  12. 论制造业阿米巴经营模式实践分析%Analysis of Practices of Amoeba Management Model in Manufacturing Industry

    Institute of Scientific and Technical Information of China (English)

    孙智慧; 赵俊丰

    2016-01-01

    阿米巴经营模式由日本企业家稻盛和夫提出,其创办的京瓷和第二电电公司采用阿米巴经营模式,皆以惊人的速度成长并进入世界500强.阿米巴经营模式也被越来越多的企业学习、导入和运用.以制造型企业A公司为例,阐述了阿米巴经营模式的建立、核算、改进等内容,供其他制造型企业参考、借鉴.

  13. Use of multiplex PCR and PCR restriction enzyme analysis for detection and exploration of the variability in the free-living amoeba Naegleria in the environment.

    Science.gov (United States)

    Pélandakis, Michel; Pernin, Pierre

    2002-04-01

    A multiplex PCR was developed to simultaneously detect Naegleria fowleri and other Naegleria species in the environment. Multiplex PCR was also capable of identifying N. fowleri isolates with internal transcribed spacers of different sizes. In addition, restriction fragment length polymorphism analysis of the PCR product distinguished the main thermophilic Naegleria species from the sampling sites.

  14. The amoeba-to-flagellate transformation test is not reliable for the diagnosis of the genus Naegleria. Description of three new Naegleria spp.

    Science.gov (United States)

    De Jonckheere, J F; Brown, S; Dobson, P J; Robinson, B S; Pernin, P

    2001-07-01

    Trophozoites of several isolates from one location in Australia have failed consistently to transform into flagellates, although they display all other characteristics of the genus Naegleria. When changing the standard transformation test, flagellates were produced. In phylogenetic trees derived from partial small subunit ribosomal DNA (SSUrDNA) sequences, one of these strains branches close to a cluster comprising N. clarki, N. australiensis, N. italica and N. jadini. It is proposed that these Australian isolates represent a new species, named N. fultoni (strain NG885). Failing to form flagellates since their isolation, even when different transformation procedures are used, are two Naegleria strains from Chile and Indonesia. In SSUrDNA-based phylogenetic trees the Chilean strain clusters with N. pussardi and the Indonesian strain clusters with N. galeacystis, but the degree of sequence difference from these described species (3.5% and 2.2%, respectively) is sufficient to propose that both of the strains represent new species, named N. chilensis (strain NG946) and N. indonesiensis (strain NG945), respectively. The close relationships between each of the new species and the Naegleria species with which they cluster in SSUrDNA-based trees were confirmed by ribosomal internal transcribed spacer region (ITS) sequence comparisons. In France, several non-flagellating N. fowleri strains were isolated from one location. ITS rDNA sequence comparisons indicated that they correspond to a 'type' of N. fowleri found in both Europe and the USA. A redefinition of the genus Naegleria is proposed as a consequence of these and previous findings.

  15. Cultivation of Pathogenic Free-living Amoebae%致病性自由生活阿米巴的培养

    Institute of Scientific and Technical Information of China (English)

    彭恒; 朱淮民

    2009-01-01

    致病性自由生活阿米巴病原体的分离培养,对疾病诊断和病原体研究都具有重要意义.本文综述该病原体国内外报道的分离培养方法 ,主要包括样品处理、培养条件、虫株传代、虫株致病性检测和虫株保存方法 .

  16. A Micro-Culture Method for Continuous Observation of Free-living Amoebae%阿米巴活体微培养法

    Institute of Scientific and Technical Information of China (English)

    陈洪友; 姜庆五; 李勤学; 李子华

    2005-01-01

    目的建立一种既可做阿米巴与病原体共培养实验,又可连续观察阿米巴活体形态细微变化的培养技术.方法以24孔细胞培养板覆盖玻片为容器,37℃下微量悬滴将阿米巴与白色念珠菌共同培养,普通光学显微镜(×1000)下连续观察阿米巴的形态、活动能力、吞噬的细菌等情况.结果经微量悬滴培养在普通光学显微镜油镜下可连续观察阿米巴各种形态,滋养体呈T、K、Y字形态,并可连续观察吞噬白色念珠菌的过程.结论本法可观察到常规固定染色标本无法见到的阿米巴滋养体T、K、Y字形态及其吞噬白色念珠菌过程.

  17. Microscopic isolation and characterization of free living amoebae (FLA from surface water sources.in Birjand, the capital city of the South Khorasan

    Directory of Open Access Journals (Sweden)

    Mahmoodreza Behravan

    2015-07-01

    Conclusion: The results indicated that a significant percentage of surface water sources in Birjand city was contaminated with Acanthamoeba spp. It is necessary for physicians, therefore, to take into account the diseases caused by these infectious agents. Besides, local regional health professionals should take into consideration the potential role of surface stagnant water sources in transferring these infectious agents. Placing warning signs in areas contaminated with these infectious agents seems a useful measure.

  18. Molecular Detection of Legionella spp. and their associations with Mycobacterium spp., Pseudomonas aeruginosa and amoeba hosts in a drinking water distribution system

    Data.gov (United States)

    U.S. Environmental Protection Agency — Quantity of Legionella spp., Mycobacterium spp., Acanthamoeba,Vermamoeba vermiformis and Pseudomonas aeruginosa were estimated using qPCR methods. This dataset is...

  19. Intrinsic Spin Hall Effect

    OpenAIRE

    Murakami, Shuichi

    2005-01-01

    A brief review is given on the spin Hall effect, where an external electric field induces a transverse spin current. It has been recognized over 30 years that such effect occurs due to impurities in the presence of spin-orbit coupling. Meanwhile, it was proposed recently that there is also an intrinsic contribution for this effect. We explain the mechanism for this intrinsic spin Hall effect. We also discuss recent experimental observations of the spin Hall effect.

  20. Quantum Hall effect

    OpenAIRE

    Taylor, Simon

    2015-01-01

    The main goal of this project was to write a review about different quantum Hall effects. This review focuses on the integer and relativistic quantum Hall effect in graphene. The quantum Hall effect is a newly discovered phenomena that was experimentally observed in 1980 and relativistic quantum Hall effect in graphene was observed in 2005. This project takes a theoretical approach to describe the quantum Hall effects and graphene itself. Experiments has shown that for very strong magnetic fi...