Contrasting species-environment relationships in communities of testate amoebae, bryophytes and vascular plants along the fen-bog gradient.

Science.gov (United States)

Lamentowicz, Mariusz; Lamentowicz, Lukasz; van der Knaap, Willem O; Gabka, Maciej; Mitchell, Edward A D

2010-04-01

We studied the vegetation, testate amoebae and abiotic variables (depth of the water table, pH, electrical conductivity, Ca and Mg concentrations of water extracted from mosses) along the bog to extremely rich fen gradient in sub-alpine peatlands of the Upper Engadine (Swiss Alps). Testate amoeba diversity was correlated to that of mosses but not of vascular plants. Diversity peaked in rich fen for testate amoebae and in extremely rich fen for mosses, while for testate amoebae and mosses it was lowest in bog but for vascular plants in extremely rich fen. Multiple factor and redundancy analyses (RDA) revealed a stronger correlation of testate amoebae than of vegetation to water table and hydrochemical variables and relatively strong correlation between testate amoeba and moss community data. In RDA, hydrochemical variables explained a higher proportion of the testate amoeba and moss data than water table depth. Abiotic variables explained a higher percentage of the species data for testate amoebae (30.3% or 19.5% for binary data) than for mosses (13.4%) and vascular plants (10%). These results show that (1) vascular plant, moss and testate amoeba communities respond differently to ecological gradients in peatlands and (2) testate amoebae are more strongly related than vascular plants to the abiotic factors at the mire surface. These differences are related to vertical trophic gradients and associated niche differentiation.

Giant Viruses of Amoebae: A Journey Through Innovative Research and Paradigm Changes.

Science.gov (United States)

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

2017-09-29

Giant viruses of amoebae were discovered serendipitously in 2003; they are visible via optical microscopy, making them bona fide microbes. Their lifestyle, structure, and genomes break the mold of classical viruses. Giant viruses of amoebae are complex microorganisms. Their genomes harbor between 444 and 2,544 genes, including many that are unique to viruses, and encode translation components; their virions contain >100 proteins as well as mRNAs. Mimiviruses have a specific mobilome, including virophages, provirophages, and transpovirons, and can resist virophages through a system known as MIMIVIRE (mimivirus virophage resistance element). Giant viruses of amoebae bring upheaval to the definition of viruses and tend to separate the current virosphere into two categories: very simple viruses and viruses with complexity similar to that of other microbes. This new paradigm is propitious for enhanced detection and characterization of giant viruses of amoebae, and a particular focus on their role in humans is warranted.

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

Behavioural differentiation induced by environmental variation when crossing a toxic zone in an amoeba

International Nuclear Information System (INIS)

Kunita, Itsuki; Kuroda, Shigeru; Nakagaki, Toshiyuki; Ueda, Kei-Ichi; Akita, Dai

2017-01-01

Organisms choose from among various courses of action in response to a wide variety of environmental conditions and the mechanism by which various behaviours are induced is an open question. Interesting behaviour was recently reported: that a unicellular organism of slime mold Physarum polycephalum known as an amoeba had multiple responses (crossing, returning, etc) when the amoeba encounters a zone with toxic levels of quinine, even under carefully controlled conditions. We here examined this elegant example in more detail to obtain insight into behavioural differentiation. We found that the statistical distribution of passage times across a quinine zone switch from unimodal to bimodal (with peaks corresponding to fast crossing and no crossing) when a periodic light stimulation to modulate a biorhythm in amoeba is applied homogeneously across the space, even under the same level of chemical stimuli. Based on a mathematical model for cell movement in amoeba, we successfully reproduced the stimulation-induced differentiation, which was observed experimentally. These dynamics may be explained by a saddle structure around a canard solution. Our results imply that the differentiation of behavioural types in amoeba is modified step-by-step via the compounding of stimulation inputs. The complex behaviour like the differentiation in amoeba may provide a basis for understanding the mechanism of behaviour selection in higher animals from an ethological perspective. (paper)

Behavioural differentiation induced by environmental variation when crossing a toxic zone in an amoeba

Science.gov (United States)

Kunita, Itsuki; Ueda, Kei-Ichi; Akita, Dai; Kuroda, Shigeru; Nakagaki, Toshiyuki

2017-09-01

Organisms choose from among various courses of action in response to a wide variety of environmental conditions and the mechanism by which various behaviours are induced is an open question. Interesting behaviour was recently reported: that a unicellular organism of slime mold Physarum polycephalum known as an amoeba had multiple responses (crossing, returning, etc) when the amoeba encounters a zone with toxic levels of quinine, even under carefully controlled conditions. We here examined this elegant example in more detail to obtain insight into behavioural differentiation. We found that the statistical distribution of passage times across a quinine zone switch from unimodal to bimodal (with peaks corresponding to fast crossing and no crossing) when a periodic light stimulation to modulate a biorhythm in amoeba is applied homogeneously across the space, even under the same level of chemical stimuli. Based on a mathematical model for cell movement in amoeba, we successfully reproduced the stimulation-induced differentiation, which was observed experimentally. These dynamics may be explained by a saddle structure around a canard solution. Our results imply that the differentiation of behavioural types in amoeba is modified step-by-step via the compounding of stimulation inputs. The complex behaviour like the differentiation in amoeba may provide a basis for understanding the mechanism of behaviour selection in higher animals from an ethological perspective.

Mimivirus: leading the way in the discovery of giant viruses of amoebae.

Science.gov (United States)

Colson, Philippe; La Scola, Bernard; Levasseur, Anthony; Caetano-Anollés, Gustavo; Raoult, Didier

2017-04-01

The accidental discovery of the giant virus of amoeba - Acanthamoeba polyphaga mimivirus (APMV; more commonly known as mimivirus) - in 2003 changed the field of virology. Viruses were previously defined by their submicroscopic size, which probably prevented the search for giant viruses, which are visible by light microscopy. Extended studies of giant viruses of amoebae revealed that they have genetic, proteomic and structural complexities that were not thought to exist among viruses and that are comparable to those of bacteria, archaea and small eukaryotes. The giant virus particles contain mRNA and more than 100 proteins, they have gene repertoires that are broader than those of other viruses and, notably, some encode translation components. The infection cycles of giant viruses of amoebae involve virus entry by amoebal phagocytosis and replication in viral factories. In addition, mimiviruses are infected by virophages, defend against them through the mimivirus virophage resistance element (MIMIVIRE) system and have a unique mobilome. Overall, giant viruses of amoebae, including mimiviruses, marseilleviruses, pandoraviruses, pithoviruses, faustoviruses and molliviruses, challenge the definition and classification of viruses, and have increasingly been detected in humans.

Testate amoebae communities sensitive to surface moisture conditions in Patagonian peatlands

Science.gov (United States)

Loisel, J.; Booth, R.; Charman, D.; van Bellen, S.; Yu, Z.

2017-12-01

Here we examine moss surface samples that were collected during three field campaigns (2005, 2010, 2014) across southern Patagonian peatlands to assess the potential use of testate amoebae and 13C isotope data as proxy indicators of soil moisture. These proxies have been widely tested across North America, but their use as paleoecological tools remains sparse in the southern hemisphere. Samples were collected along a hydrological gradient spanning a range of water table depth from 0cm in wet hollows to over 85cm in dry hummocks. Moss moisture content was measured in the field. Over 25 taxa were identified, with many of them not found in North America. Ordinations indicate statistically significant and dominant effects of soil moisture and water table depth on testate assemblages, though interestingly 13C is even more strongly correlated with testates amoebae than direct soil conditions. It is possible that moss 13C signature constitutes a compound indicator that represents seasonal soil moisture better than opportunistic sampling during field campaigns. There is no significant effect of year or site across the dataset. In addition to providing a training set that translates testate amoebae moisture tolerance range into water tabel depth for Patagonian peatlands, we also compare our results with those from the North American training set to show that, despite 'novel' Patagonian taxa, the robustness of international training sets is probably sufficient to quantify most changes in soil moisture from any site around the world. We also identify key indicator species that are shown to be of universal value in peat-based hydrological reconstructions.

Amoeba Management System Transformation in the Light of Organisational Change Literature

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Urban Wieslaw

2017-03-01

Full Text Available The object of this study is the system of amoebas founded originally in Japanese Kyocera. The study aims to identify milestones of the transformation in a company organisational system to the Amoeba Management System (AMS. The study takes a conceptual research approach. It starts from the analysis of available sources on the AMS, identifies the most challenging points of this system, and afterwards, based on organisational change literature, formulates the main steps of transformation towards AMS. The following milestones of AMS implementation emerge from organisational change theories: (1 the preparation for AMS, (2 the change of organisational structure, (3 the design and introduction of a new accounting system, (4 the introduction of inner prices between amoebas, and (5 the transformation of the organisational culture. At the end of the study, the most important issues for future research are listed.

AMOEBA Polarizable Force Field Parameters of the Heme Cofactor in Its Ferrous and Ferric Forms.

Science.gov (United States)

Wu, Xiaojing; Clavaguera, Carine; Lagardère, Louis; Piquemal, Jean-Philip; de la Lande, Aurélien

2018-04-16

We report the first parameters of the heme redox cofactors for the polarizable AMOEBA force field in both the ferric and ferrous forms. We consider two types of complexes, one with two histidine side chains as axial ligands and one with a histidine and a methionine side chain as ligands. We have derived permanent multipoles from second-order Møller-Plesset perturbation theory (MP2). The sets of parameters have been validated in a first step by comparison of AMOEBA interaction energies of heme and a collection of biologically relevant molecules with MP2 and Density Functional Theory (DFT) calculations. In a second validation step, we consider interaction energies with large aggregates comprising around 80 H 2 O molecules. These calculations are repeated for 30 structures extracted from semiempirical PM7 DM simulations. Very encouraging agreement is found between DFT and the AMOEBA force field, which results from an accurate treatment of electrostatic interactions. We finally report long (10 ns) MD simulations of cytochromes in two redox states with AMOEBA testing both the 2003 and 2014 AMOEBA water models. These simulations have been carried out with the TINKER-HP (High Performance) program. In conclusion, owing to their ubiquity in biology, we think the present work opens a wide array of applications of the polarizable AMOEBA force field on hemeproteins.

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. Copyright © 2014 Elsevier GmbH. All rights reserved.

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...

Buse_Francisella and free-living amoebae data sets

Data.gov (United States)

U.S. Environmental Protection Agency — Co-infection data in the form of colony forming units and amoeba cell counts. This dataset is associated with the following publication: Buse , H., F. Schaefer, and...

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

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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

Long-Term Hydrological Reconstruction From a Beaver Meadow Using Testate Amoebae

Science.gov (United States)

Von Ness, K.; Loisel, J.; Karran, D. J.; Westbrook, C.; Kohlmeyer, C.

2016-12-01

Beaver ponds contribute up to 0.8 Tg/yr of atmospheric methane (CH4) globally (Whitfield et al., 2014) and were found to be the largest CH4 emitters among all the wetland types in boreal environments (Roulet et al., 1992). However, the sources and underlying mechanisms of carbon emission and sequestration in beaver ponds requires further elucidation. Here we present the historical development of a beaver meadow located in the Sibbald Research Wetland in the Rocky Mountains of Kananaskis Provincial Park, Alberta, Canada. We use a combination of testate amoebae, plant macrofossils, and other geochemical proxies to provide high-resolution reconstructions along three peat cores extracted in hydrologically distinct portions of the meadow. To our knowledge, this is the first attempt at reconstructing long-term hydrological conditions in these systems. Testate amoebae (Protozoa: Rhizopoda) are single-celled organisms that inhabit moist substrates and produce a decay-resistant test. As each taxon generally occupies a discrete ecological niche related to soil moisture and pH, testate amoebae are good indicators of past and ongoing hydrological change. Preliminary analysis of testate amoebae assemblages downcore suggests that this proxy is suitable to reconstruct hydrological changes in meadows, with wetter and drier communities being in good agreement with wetter and drier plant macrofossil assemblages. The nitrogen isotopic signature of peat samples (ongoing) will be used as a proxy for changes in nutrient input; it could become a proxy for past beaver activity.

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

OpenAIRE

Swindles, Graeme T.; Amesbury, Matthew J.; Turner, T. Edward; Carrivick, Jonathan L.; Woulds, Clare; Raby, Cassandra; Mullan, Donal; Roland, Thomas P.; Galloway, Jennifer M.; Parry, Lauren; Kokfelt, Ulla; Garneau, Michelle; Charman, Dan J.; Holden, Joseph

2015-01-01

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 (~ 200 km north of the Arctic Circle). Multivariate statistical 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 ne...

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...

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 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.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.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.

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,...

Origin and diversity of testate amoebae shell composition: Example of Bullinularia indica living in Sphagnum capillifolium.

Science.gov (United States)

Delaine, Maxence; Bernard, Nadine; Gilbert, Daniel; Recourt, Philippe; Armynot du Châtelet, Eric

2017-06-01

Testate amoebae are free-living shelled protists that build a wide range of shells with various sizes, shapes, and compositions. Recent studies showed that xenosomic testate amoebae shells could be indicators of atmospheric particulate matter (PM) deposition. However, no study has yet been conducted to assess the intra-specific mineral, organic, and biologic grain diversity of a single xenosomic species in a natural undisturbed environment. This study aims at providing new information about grain selection to develop the potential use of xenosomic testate amoebae shells as bioindicators of the multiple-origin mineral/organic diversity of their proximal environment. To fulfil these objectives, we analysed the shell content of 38 Bullinularia indica individuals, a single xenosomic testate amoeba species living in Sphagnum capillifolium, by scanning electron microscope (SEM) coupled with X-ray spectroscopy. The shells exhibited high diversities of mineral, organic, and biomineral grains, which confirms their capability to recycle xenosomes. Mineral grain diversity and size of B. indica matched those of the atmospheric natural mineral PM deposited in the peatbog. Calculation of grain size sorting revealed a discrete selection of grains agglutinated by B. indica. These results are a first step towards understanding the mechanisms of particle selection by xenosomic testate amoebae in natural conditions. Copyright © 2017 Elsevier GmbH. All rights reserved.

Platyamoeba pseudovannellida n. sp., a naked amoeba with wide salt tolerance isolated from the Salton Sea, California.

Science.gov (United States)

Hauer, G; Rogerson, A; Anderson, O R

2001-01-01

A new species of naked amoeba, Platyamoeba pseudovannellida n.sp., is described on the basis of light microscopic and fine structural features. The amoeba was isolated from the Salton Sea, California, from water at a salinity of ca. 44%. Locomotive amoebae occasionally had a spatulate outline and floating cells had radiating pseudopodia, sometimes with pointed tips. Both these features are reminiscent of the genus Vannella. However, the surface coat (glycocalyx) as revealed by TEM indicates that this is a species of Platyamoeba. Although salinity was not used as a diagnostic feature, this species was found to have remarkable tolerance to fluctuating salinity levels, even when changes were rapid. Amoebae survived over the range 0 per thousand to 150 per thousand salt and grew within the range 0 per thousand to 138 per thousand salt. The generation time of cells averaged 29 h and was not markedly affected by salt concentration. This is longer than expected for an amoeba of this size and suggests a high energetic cost of coping with salinity changes. The morphology of cells changed with increasing salinity: at 0 per thousand cells were flattened and active and at the other extreme (138 per thousand) amoebae were wrinkled and domed and cell movement was very slow. At the ultrastructural level, the cytoplasm of cells grown at high salinity (98 per thousand was considerably denser than that of cells reared at 0 per thousand.

[Nitrogen input altered testate amoebae community in peatland of Sanjiang Plain, Northeast China].

Science.gov (United States)

Song, Li-hong; Yan, Xiu-min; Wang, Ke-hong; Zhu, Xiao-yan; Wu, Dong-hu

2015-02-01

In the present study, an in situ control experiment was carried out to explore the response of testate amoebae to exogenous nitrogen addition in peatland of Sanjiang Plain. The results showed that nitrogen addition increased the biomass of testate amoebae at lower levels (6 g N · m(-2)), while decreased it at higher levels (> 12 g N · m(-2)). At genus level, nitrogen addition significantly increased the biomass of Arcella and Phryganella, decreased the biomass of Euglypha. Only lower nitrogen addition significantly increased the biomass of Centropyxis. At species level, nitrogen addition significantly decreased the biomass of Euglypha rotunda, while the biomass of either Centropyxis cassis or Phryganella acropodia was increased by a lower nitrogen addition treatment. This study suggested that the response of peatland testate amoebae to nitrogen addition was species specific, which could potentially be used as an indicator for the environment of peatlands.

The potential influence of short-term environmental variability on the composition of testate amoeba communities in Sphagnum peatlands.

Science.gov (United States)

Sullivan, Maura E; Booth, Robert K

2011-07-01

Testate amoebae are a group of moisture-sensitive, shell-producing protozoa that have been widely used as indicators of changes in mean water-table depth within oligotrophic peatlands. However, short-term environmental variability (i.e., sub-annual) also probably influences community composition. The objective of this study was to assess the potential influence of short-term environmental variability on the composition of testate amoeba communities in Sphagnum-dominated peatlands. Testate amoebae and environmental conditions, including hourly measurements of relative humidity within the upper centimeter of the peatland surface, were examined throughout the 2008 growing season at 72 microsites within 11 peatlands of Pennsylvania and Wisconsin, USA. Relationships among testate amoeba communities, vegetation, depth to water table, pH, and an index of short-term environmental variability (EVI), were examined using nonmetric multidimensional scaling and correlation analysis. Results suggest that EVI influences testate amoeba communities, with some taxa more abundant under highly variable conditions (e.g., Arcella discoides, Difflugia pulex, and Hyalosphenia subflava) and others more abundant when environmental conditions at the peatland surface were relatively stable (e.g., Archerella flavum and Bullinularia indica). The magnitude of environmental variability experienced at the peatland surface appears to be primarily controlled by vegetation composition and density. In particular, sites with dense Sphagnum cover had lower EVI values than sites with loose-growing Sphagnum or vegetation dominated by vascular plants and/or non-Sphagnum bryophytes. Our results suggest that more environmental information may be inferred from testate amoebae than previously recognized. Knowledge of relationships between testate amoebae and short-term environmental variability should lead to more detailed and refined environmental inferences.

The Evolution of a distributed operating system (Amoeba)

NARCIS (Netherlands)

van Renesse, Robbert; Tanenbaum, Andrew S.; Mullender, Sape J.

1989-01-01

AMOEBA is a research project to build a true distributed operating system using the object model. Under the COST11-ter MANDIS project this work was extended to cover wide-area networks. Besides describing the system, this paper discusses the successive versions in the implementation of its model,

Presence of rotavirus and free-living amoebae in the water supplies of Karachi, Pakistan

Science.gov (United States)

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

2017-01-01

ABSTRACT Rotavirus and pathogenic free-living amoebae are causative agents of important health problems, especially for developing countries like Pakistan where the population has limited access to clean water supplies. Here, we evaluated the prevalence of rotavirus and free-living amoebae (Acanthamoeba spp., Balamuthia mandrillaris, Naegleria fowleri) in drinking water supplies of Karachi, Pakistan. Six water filtration plants that supply drinking water to the population of Karachi were investigated. Additionally, drinking water samples from households were analyzed for the presence of rotavirus and free-living amoebae. Rotavirus was present in 35% of the water samples collected from water filtration plants; however, domestic tap water samples had a prevalence of only 5%. Out of 20 water samples from filtration plants, 13 (65%) were positive for Acanthamoeba spp., and one (5%) was positive for B. mandrillaris. Out of 20 drinking water samples collected from different areas of Karachi, 35% were positive for Acanthamoeba spp. Rotavirus was detected in 5% of the drinking water samples tested. Overall, these findings showed for the first time the presence of rotavirus, in addition to pathogenic free-living amoebae in drinking water supplies of Karachi that could be an important public health risk for the affected population. PMID:28591260

Presence of rotavirus and free-living amoebae in the water supplies of Karachi, Pakistan

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Farzana Abubakar Yousuf

Full Text Available ABSTRACT Rotavirus and pathogenic free-living amoebae are causative agents of important health problems, especially for developing countries like Pakistan where the population has limited access to clean water supplies. Here, we evaluated the prevalence of rotavirus and free-living amoebae (Acanthamoeba spp., Balamuthia mandrillaris, Naegleria fowleri in drinking water supplies of Karachi, Pakistan. Six water filtration plants that supply drinking water to the population of Karachi were investigated. Additionally, drinking water samples from households were analyzed for the presence of rotavirus and free-living amoebae. Rotavirus was present in 35% of the water samples collected from water filtration plants; however, domestic tap water samples had a prevalence of only 5%. Out of 20 water samples from filtration plants, 13 (65% were positive for Acanthamoeba spp., and one (5% was positive for B. mandrillaris. Out of 20 drinking water samples collected from different areas of Karachi, 35% were positive for Acanthamoeba spp. Rotavirus was detected in 5% of the drinking water samples tested. Overall, these findings showed for the first time the presence of rotavirus, in addition to pathogenic free-living amoebae in drinking water supplies of Karachi that could be an important public health risk for the affected population.

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

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.

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

2016-03-05

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. © 2015 Wiley Periodicals, Inc.

An analysis of hereditary increase in frequency of cell mortality induced by external factors (Experiments on nuclear transplantation in amoebae)

International Nuclear Information System (INIS)

Bychkovskaya, I.B.; Ochinskaya, G.K.; Yudin, A.L.; AN SSSR, Leningrad. Inst. Tsitologii)

1980-01-01

By using nuclear transplantations in Amoeba proteus a study was made of a peculiar heritable effect, a stable increase in the frequency of cell mortality incuced by comparatively low doses of x radiation (50 Gy) or slight heating (29 0 C during 6 to 7 h). This effect differs qualitatively from the known radiation effects (reproductive death, lethal sectoring) by its being non-specific for radiation. In addition, the effect is saltatory appearing in 100% of the treated cells and the extent of its expression is not dependent on the dose of an inducing factor (at supra-threshold doses) and the period of time after treatment. It was found that (1) the hereditary changes in amoebae, unlike those resulting in reproductive death, are transmitted during intercellular transplantations both by the nucleus and cytoplasm of an altered cell; (2) the transfer of the character under test is accomplished by means of a certiin factor capable of shuttling between the nucleus and cytoplasm, (3) the effect is not necessarily a consequence of primary injury of nuclear structures and it may be induced by treatment of the cytoplasm of an enucleated cell renucleated then by the nucleus of a normal amoeba. In this respect, the effect under test differs also from the known types of hereditary post-radiation lethal effects which are commonly suggested to involve primary injury of the nucleus. Possible mechanisms of genetic control over the character tested are discussed. (author)

Advances in the knowledge of amphizoic amoebae infecting fish

Czech Academy of Sciences Publication Activity Database

Dyková, Iva; Lom, Jiří

2004-01-01

Roč. 51, 2/3 (2004), s. 81-97 ISSN 0015-5683 R&D Projects: GA AV ČR IAA6022202 Institutional research plan: CEZ:AV0Z6022909 Keywords : amphizoic amoebae * fish hosts * review Subject RIV: EA - Cell Biology Impact factor: 0.837, year: 2004

Ecological niche models reveal the importance of climate variability for the biogeography of protosteloid amoebae.

Science.gov (United States)

Aguilar, María; Lado, Carlos

2012-08-01

Habitat availability and environmental preferences of species are among the most important factors in determining the success of dispersal processes and therefore in shaping the distribution of protists. We explored the differences in fundamental niches and potential distributions of an ecological guild of slime moulds-protosteloid amoebae-in the Iberian Peninsula. A large set of samples collected in a north-east to south-west transect of approximately 1000 km along the peninsula was used to test the hypothesis that, together with the existence of suitable microhabitats, climate conditions may determine the probability of survival of species. Although protosteloid amoebae share similar morphologies and life history strategies, canonical correspondence analyses showed that they have varied ecological optima, and that climate conditions have an important effect in niche differentiation. Maxent environmental niche models provided consistent predictions of the probability of presence of the species based on climate data, and they were used to generate maps of potential distribution in an 'everything is everywhere' scenario. The most important climatic factors were, in both analyses, variables that measure changes in conditions throughout the year, confirming that the alternation of fruiting bodies, cysts and amoeboid stages in the life cycles of protosteloid amoebae constitutes an advantage for surviving in a changing environment. Microhabitat affinity seems to be influenced by climatic conditions, which suggests that the micro-environment may vary at a local scale and change together with the external climate at a larger scale.

Real-time PCR systems targeting giant viruses of amoebae and their virophages.

Science.gov (United States)

Ngounga, Tatsiana; Pagnier, Isabelle; Reteno, Dorine-Gaelle Ikanga; Raoult, Didier; La Scola, Bernard; Colson, Philippe

2013-01-01

Giant viruses that infect amoebae, including mimiviruses and marseilleviruses, were first described in 2003. Virophages were subsequently described that infect mimiviruses. Culture isolation with Acanthamoeba spp. and metagenomic studies have shown that these giant viruses are common inhabitants of our biosphere and have enabled the recent detection of these viruses in human samples. However, the genomes of these viruses display substantial genetic diversity, making it a challenge to examine their presence in environmental and clinical samples using conventional and real-time PCR. We designed and evaluated the performance of PCR systems capable of detecting all currently isolated mimiviruses, marseilleviruses and virophages to assess their prevalence in various samples. Our real-time PCR assays accurately detected all or most of the members of the currently delineated lineages of giant viruses infecting acanthamoebae as well as the mimivirus virophages, and enabled accurate classification of the mimiviruses of amoebae in lineages A, B or C. We were able to detect four new mimiviruses directly from environmental samples and correctly classified these viruses within mimivirus lineage C. This was subsequently confirmed by culture on amoebae followed by partial Sanger sequencing. PCR systems such as those implemented here may contribute to an improved understanding of the prevalence of mimiviruses, their virophages and marseilleviruses in humans.

Sphagnum-dwelling testate amoebae in subarctic bogs are more sensitive to soil warming in the growing season than in winter: the results of eight-year field climate manipulations.

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Tsyganov, Andrey N; Aerts, Rien; Nijs, Ivan; Cornelissen, Johannes H C; Beyens, Louis

2012-05-01

Sphagnum-dwelling testate amoebae are widely used in paleoclimate reconstructions as a proxy for climate-induced changes in bogs. However, the sensitivity of proxies to seasonal climate components is an important issue when interpreting proxy records. Here, we studied the effects of summer warming, winter snow addition solely and winter snow addition together with spring warming on testate amoeba assemblages after eight years of experimental field climate manipulations. All manipulations were accomplished using open top chambers in a dry blanket bog located in the sub-Arctic (Abisko, Sweden). We estimated sensitivity of abundance, diversity and assemblage structure of living and empty shell assemblages of testate amoebae in the living and decaying layers of Sphagnum. Our results show that, in a sub-arctic climate, testate amoebae are more sensitive to climate changes in the growing season than in winter. Summer warming reduced species richness and shifted assemblage composition towards predominance of xerophilous species for the living and empty shell assemblages in both layers. The higher soil temperatures during the growing season also decreased abundance of empty shells in both layers hinting at a possible increase in their decomposition rates. Thus, although possible effects of climate changes on preservation of empty shells should always be taken into account, species diversity and structure of testate amoeba assemblages in dry subarctic bogs are sensitive proxies for climatic changes during the growing season. Copyright © 2011 Elsevier GmbH. All rights reserved.

Response of testate amoebae to a late Holocene ecosystem shift in an Amazonian peatland.

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Swindles, Graeme T; Kelly, Thomas J; Roucoux, Katherine H; Lawson, Ian T

2018-03-15

To date there have only been two studies using testate amoebae as palaeoecological indicators in tropical peatlands. Here we present a new ∼500-year testate amoeba record from San Jorge, a domed peatland in Peruvian Amazonia, which has a well-constrained vegetation history based on pollen analysis. We observe a major shift from Hyalosphenia subflava to Cryptodifflugia oviformis-dominated communities at ∼50 cm depth (c. AD 1760), which suggests a change to drier conditions in the peatland. The application of a statistical transfer function also suggests a deepening of the water table at this time. The transition in the microbial assemblage occurs at a time when pollen and geochemical data indicate drier conditions (reduced influence of river flooding), leading to an ecosystem switch to more ombrotrophic-like conditions in the peatland. Our work illustrates the potential of testate amoebae as important tools in tropical peatland palaeoecology, and the power of multiproxy approaches for understanding the long-term development of tropical peatlands. Copyright © 2018 Elsevier GmbH. All rights reserved.

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.

Kin discrimination increases with genetic distance in a social amoeba.

Science.gov (United States)

Ostrowski, Elizabeth A; Katoh, Mariko; Shaulsky, Gad; Queller, David C; Strassmann, Joan E

2008-11-25

In the social amoeba Dictyostelium discoideum, thousands of cells aggregate upon starvation to form a multicellular fruiting body, and approximately 20% of them die to form a stalk that benefits the others. The aggregative nature of multicellular development makes the cells vulnerable to exploitation by cheaters, and the potential for cheating is indeed high. Cells might avoid being victimized if they can discriminate among individuals and avoid those that are genetically different. We tested how widely social amoebae cooperate by mixing isolates from different localities that cover most of their natural range. We show here that different isolates partially exclude one another during aggregation, and there is a positive relationship between the extent of this exclusion and the genetic distance between strains. Our findings demonstrate that D. discoideum cells co-aggregate more with genetically similar than dissimilar individuals, suggesting the existence of a mechanism that discerns the degree of genetic similarity between individuals in this social microorganism.

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...

[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.

Environmental Free-Living Amoebae Isolated from Soil in Khon Kaen, Thailand, Antagonize Burkholderia pseudomallei.

Directory of Open Access Journals (Sweden)

Parumon Noinarin

Full Text Available Presence of Burkholderia pseudomallei in soil and water is correlated with endemicity of melioidosis in Southeast Asia and northern Australia. Several biological and physico-chemical factors have been shown to influence persistence of B. pseudomallei in the environment of endemic areas. This study was the first to evaluate the interaction of B. pseudomallei with soil amoebae isolated from B. pseudomallei-positive soil site in Khon Kaen, Thailand. Four species of amoebae, Paravahlkampfia ustiana, Acanthamoeba sp., Naegleria pagei, and isolate A-ST39-E1, were isolated, cultured and identified based on morphology, movement and 18S rRNA gene sequence. Co-cultivation combined with a kanamycin-protection assay of B. pseudomallei with these amoebae at MOI 20 at 30°C were evaluated during 0-6 h using the plate count technique on Ashdown's agar. The fate of intracellular B. pseudomallei in these amoebae was also monitored by confocal laser scanning microscopy (CLSM observation of the CellTracker™ Orange-B. pseudomallei stained cells. The results demonstrated the ability of P. ustiana, Acanthamoeba sp. and isolate A-ST39-E1 to graze B. pseudomallei. However, the number of internalized B. pseudomallei substantially decreased and the bacterial cells disappeared during the observation period, suggesting they had been digested. We found that B. pseudomallei promoted the growth of Acanthamoeba sp. and isolate A-ST39-E1 in co-cultures at MOI 100 at 30°C, 24 h. These findings indicated that P. ustiana, Acanthamoeba sp. and isolate A-ST39-E1 may prey upon B. pseudomallei rather than representing potential environmental reservoirs in which the bacteria can persist.

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.

Seasonal abundances of naked amoebae in biofilms on shells of zebra mussels (Dreissena polymorpha) with comparative data from rock scrapings.

Science.gov (United States)

Bischoff, Paul J; Wetmore, Scott

2009-01-01

In North America, zebra mussels (Dreissena polymorpha) are notoriously known as invasive species. The abundance of naked amoebae sampled from the shells of zebra mussels was compared with abundances from rock scrapings at approximately monthly intervals for 1 year. The sites were 2 km apart along the same shoreline. No significant difference in abundance of naked amoebae (F = 1.44; P amoebae in winter, followed by peaks in early spring. The percent encysted increased from a low of 1% in the summer to 80% in early winter.

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...

Pathogenic waterborne free-living amoebae: An update from selected Southeast Asian countries

Science.gov (United States)

Abdul Majid, Mohamad Azlan; Mahboob, Tooba; Mong, Brandon G. J.; Jaturas, Narong; Richard, Reena Leeba; Tian-Chye, Tan; Phimphila, Anusorn; Mahaphonh, Panomphanh; Aye, Kyaw Nyein; Aung, Wai Lynn; Chuah, Joon; Ziegler, Alan D.; Yasiri, Atipat; Sawangjaroen, Nongyao; Lim, Yvonne A. L.; Nissapatorn, Veeranoot

2017-01-01

Data on the distribution of free-living amoebae is still lacking especially in Southeast Asian region. The aquatic environment revealed a high occurrence of free-living amoebae (FLA) due to its suitable condition and availability of food source, which subsequently causes infection to humans. A total of 94 water samples consisted of both treated and untreated from Laos (31), Myanmar (42), and Singapore (21) were investigated for the presence of pathogenic FLA. Each water sample was filtered and cultured onto non-nutrient agar seeded with live suspension of Escherichia coli and incubated at room temperature. Morphological identification was conducted for both trophozoites and cysts via microscopic stains (Giemsa and immunofluorescence). The presence of Naegleria-like structures was the most frequently encountered in both treated and untreated water samples, followed by Acanthamoeba-like and Vermamoeba-like features. To identify the pathogenic isolates, species-specific primer sets were applied for molecular identification of Acanthamoeba, Naegleria, and Vermamoeba. The pathogenic species of Acanthamoeba lenticulata and A. triangularis were detected from untreated water samples, while Vermamoeba vermiformis was found in both treated and untreated water samples. Our results suggested that poor water quality as well as inadequate maintenance and treatment might be the cause of this alarming problem since chlorine disinfection is ineffective in eradicating these amoebas in treated water samples. Regular monitoring and examination of water qualities are necessary in order to control the growth, hence, further preventing the widespread of FLA infections among the public. PMID:28212409

Contrasting diversity of testate amoebae communities in Sphagnum and brown-moss dominated patches in relation to shell counts.

Science.gov (United States)

Lizoňová, Zuzana; Horsák, Michal

2017-04-01

Ecological studies of peatland testate amoebae are generally based on totals of 150 individuals per sample. However, the suitability of this standard has never been assessed for alkaline habitats such as spring fens. We explored the differences in testate amoeba diversity between Sphagnum and brown-moss microhabitats at a mire site with a highly diversified moss layer which reflects the small-scale heterogeneity in groundwater chemistry. Relationships between sampling efficiency and sample completeness were explored using individual-based species accumulation curves and the effort required to gain an extra species was assessed. Testate amoeba diversity differed substantially between microhabitats, with brown mosses hosting on average twice as many species and requiring greater shell totals to reach comparable sample analysis efficiency as for Sphagnum. Thus, for samples from alkaline conditions an increase in shell totals would be required and even an overall doubling up to 300 individuals might be considered for reliable community description. Our small-scale data are likely not robust enough to provide an ultimate solution for the optimization of shell totals. However, the results proved that testate amoebae communities from acidic and alkaline environments differ sharply in both species richness and composition and they might call for different methodological approaches. Copyright © 2017 Elsevier GmbH. All rights reserved.

What is the optimum sample size for the study of peatland testate amoeba assemblages?

Science.gov (United States)

Mazei, Yuri A; Tsyganov, Andrey N; Esaulov, Anton S; Tychkov, Alexander Yu; Payne, Richard J

2017-10-01

Testate amoebae are widely used in ecological and palaeoecological studies of peatlands, particularly as indicators of surface wetness. To ensure data are robust and comparable it is important to consider methodological factors which may affect results. One significant question which has not been directly addressed in previous studies is how sample size (expressed here as number of Sphagnum stems) affects data quality. In three contrasting locations in a Russian peatland we extracted samples of differing size, analysed testate amoebae and calculated a number of widely-used indices: species richness, Simpson diversity, compositional dissimilarity from the largest sample and transfer function predictions of water table depth. We found that there was a trend for larger samples to contain more species across the range of commonly-used sample sizes in ecological studies. Smaller samples sometimes failed to produce counts of testate amoebae often considered minimally adequate. It seems likely that analyses based on samples of different sizes may not produce consistent data. Decisions about sample size need to reflect trade-offs between logistics, data quality, spatial resolution and the disturbance involved in sample extraction. For most common ecological applications we suggest that samples of more than eight Sphagnum stems are likely to be desirable. Copyright © 2017 Elsevier GmbH. All rights reserved.

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

International Nuclear Information System (INIS)

Cabanes, P.; Pernin, P.

1998-01-01

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 -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 -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 -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 -1 . Naegleria fowleri concentrations decreased immediately and thereafter remained under 4 l -1 . Total residual chlorine and chlorinated organic compounds were also monitored in the evaluation of the environmental impact of this preventive action. (authors)

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

Directory of Open Access Journals (Sweden)

Valentyna Krashevska

Full Text Available 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.

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.

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.

[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.

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

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 ...

The rate and effects of spontaneous mutation on fitness traits in the social amoeba, Dictyostelium discoideum.

Science.gov (United States)

Hall, David W; Fox, Sara; Kuzdzal-Fick, Jennie J; Strassmann, Joan E; Queller, David C

2013-07-08

We performed a mutation accumulation (MA) experiment in the social amoeba Dictyostelium discoideum to estimate the rate and distribution of effects of spontaneous mutations affecting eight putative fitness traits. We found that the per-generation mutation rate for most fitness components is 0.0019 mutations per haploid genome per generation or larger. This rate is an order of magnitude higher than estimates for fitness components in the unicellular eukaryote Saccharomyces cerevisiae, even though the base-pair substitution rate is two orders of magnitude lower. The high rate of fitness-altering mutations observed in this species may be partially explained by a large mutational target relative to S. cerevisiae. Fitness-altering mutations also may occur primarily at simple sequence repeats, which are common throughout the genome, including in coding regions, and may represent a target that is particularly likely to give fitness effects upon mutation. The majority of mutations had deleterious effects on fitness, but there was evidence for a substantial fraction, up to 40%, being beneficial for some of the putative fitness traits. Competitive ability within the multicellular slug appears to be under weak directional selection, perhaps reflecting the fact that slugs are sometimes, but not often, comprised of multiple clones in nature. Evidence for pleiotropy among fitness components across MA lines was absent, suggesting that mutations tend to act on single fitness components.

Growth-supporting activity for Legionella pneumophila in tap water cultures and implication of hartmannellid amoebae as growth factors.

Science.gov (United States)

Wadowsky, R M; Butler, L J; Cook, M K; Verma, S M; Paul, M A; Fields, B S; Keleti, G; Sykora, J L; Yee, R B

1988-11-01

Photosynthetic cyanobacteria, heterotrophic bacteria, free-living amoebae, and ciliated protozoa may support growth of Legionella pneumophila. Studies were done with two tap water cultures (WS1 and WS2) containing L. pneumophila and associated microbiota to characterize growth-supporting activity and assess the relative importance of the microbiota in supporting multiplication of L. pneumophila. The water cultures were incubated in the dark at 35 degrees C. The growth-supporting factor(s) was separated from each culture by filtration through 1-micron-pore-size membrane filters. The retentate was then suspended in sterile tap water. Multiplication of L. pneumophila occurred when both the retentate suspension and the filtrate from either culture were inoculated into sterile tap water. L. pneumophila did not multiply in tap water inoculated with only the filtrate, even though filtration did not reduce the concentration of L. pneumophila or heterotrophic bacteria in either culture. Growth-supporting activity of the retentate suspension from WS1 was inactivated at 60 degrees C but unaffected at 0, 25, and 45 degrees C after 30-min incubations. Filtration experiments indicated that the growth-supporting factor(s) in WS1 was 2 to 5 micron in diameter. Ciliated protozoa were not detected in either culture. Hartmannellid amoebae were conclusively demonstrated in WS2 but not in WS1. L. pneumophila multiplied in tap water inoculated with the amoebae (10(3)/ml) and the 1-micron filtrate of WS2. No multiplication occurred in tap water inoculated with the filtrate only. Growth-supporting activity for L. pneumophila may be present in plumbing systems; hartmannellid amoebae appear to be important determinants of multiplication of L. pneumophila in some tap water cultures.

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

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...

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.

Brain-Eating Amoebae: Predilection Sites in the Brain and Disease Outcome

OpenAIRE

Ong, Timothy Yu Yee; Khan, Naveed Ahmed; Siddiqui, Ruqaiyyah

2017-01-01

Acanthamoeba spp. and Balamuthia mandrillaris are causative agents of granulomatous amoebic encephalitis (GAE), while Naegleria fowleri causes primary amoebic meningoencephalitis (PAM). PAM is an acute infection that lasts a few days, while GAE is a chronic to subacute infection that can last up to several months. Here, we present a literature review of 86 case reports from 1968 to 2016, in order to explore the affinity of these amoebae for particular sites of the brain, diagnostic modalities...

Interactions Between Testate Amoebae and Saprotrophic Microfungi in a Scots Pine Litter Microcosm

Czech Academy of Sciences Publication Activity Database

Vohník, Martin; Burdíková, Zuzana; Vyhnal, Aleš; Koukol, O.

2011-01-01

Roč. 61, č. 3 (2011), s. 660-668 ISSN 0095-3628 R&D Projects: GA ČR GP206/09/P340; GA ČR(CZ) GD204/09/H084 Institutional research plan: CEZ:AV0Z50110509; CEZ:AV0Z60050516 Keywords : testate amoebae * saprotrophic fungi * litter Subject RIV: EF - Botanics Impact factor: 2.912, year: 2011

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.

Impact of two hot and dry summers on the community structure and functional diversity of testate amoebae in an artificial bog, illustrating their use as bioindicators of peatland health

Directory of Open Access Journals (Sweden)

I. Koenig

2018-04-01

Full Text Available Ongoing climate warming threatens the survival of bogs at the warm/dry limit of their distribution (e.g. in central Europe, and jeopardises the restoration of damaged bogs even more. Because vegetation changes can be slow, early indicators of hydrological change such as testate amoebae are useful. We used testate amoeba community structure and community weighted mean of functional traits to monitor the impact of two very hot and dry summers on a small (around 100 m2 artificial peatland constructed in the botanic garden of Neuchâtel, Switzerland. We collected analogous samples in a naturally regenerating cutover peatland at 1000 m a.s.l. in the Jura Mountains as a reference. The comparison of living and dead assemblages in the botanic garden showed an increased representation of smaller testate amoeba taxa (Corythion dubium, small Euglypha sp. with a small pseudostome (indicative of dry conditions and a loss of mixotrophy in 2015, followed by a weaker further shift in 2016. Nevertheless, the testate amoeba community structure in 2016 still indicated a dry Sphagnum bog. Testate amoeba analysis allows rapid assessment of peatland health and/or restoration success. The comparison of living and dead assemblages makes it possible to observe changes within a season in a single sampling campaign.

Quadrulella texcalense sp nov from a Mexican desert: An unexpected new environment for hyalospheniid testate amoebae

Czech Academy of Sciences Publication Activity Database

Perez-Juarez, H.; Serrano-Vazquez, A.; Kosakyan, Anush; Mitchell, E.A.D.; Rivera Aguilar, V. M.; Lahr, D. J. G.; Hernandez Moreno, M. M.; Macías Cuellar, H.; Eguiarte, L. E.; Lara, E.

2017-01-01

Roč. 61, 17 July (2017), s. 253-264 ISSN 0932-4739 Institutional support: RVO:60077344 Keywords : Adaptation * Biological soil crust desert * Protist * Tehuacain-Cuicatlain Biosphere Reserve * Testate amoebae Subject RIV: EG - Zoology OBOR OECD: Zoology Impact factor: 2.581, year: 2016

Ecology of Testate Amoebae in the Komořany Ponds in the Vltava Basin

Czech Academy of Sciences Publication Activity Database

Burdíková, Zuzana; Čapek, Martin; Švindrych, Zdeněk; Gryndler, M.; Kubínová, Lucie; Holcová, K.

2012-01-01

Roč. 64, č. 1 (2012), s. 117-130 ISSN 0095-3628 R&D Projects: GA MŠk(CZ) LC06063; GA ČR(CZ) GAP108/11/0794 Institutional research plan: CEZ:AV0Z50110509 Keywords : ecology * freshwater ecosystem * testate amoebae * seasonal variability Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.277, year: 2012

Sphagnum-dwelling testate amoebae in subarctic bogs are more sensitive to soil warming in the growing season than in winter: the results of eight-year field climate manipulations.

NARCIS (Netherlands)

Tsyganov, A.N.; Aerts, R.; Nijs, I.; Cornelissen, J.H.C.; Beyens, L.

2012-01-01

Sphagnum-dwelling testate amoebae are widely used in paleoclimate reconstructions as a proxy for climate-induced changes in bogs. However, the sensitivity of proxies to seasonal climate components is an important issue when interpreting proxy records. Here, we studied the effects of summer warming,

Brain-Eating Amoebae: Predilection Sites in the Brain and Disease Outcome

Science.gov (United States)

Ong, Timothy Yu Yee; Siddiqui, Ruqaiyyah

2017-01-01

ABSTRACT Acanthamoeba spp. and Balamuthia mandrillaris are causative agents of granulomatous amoebic encephalitis (GAE), while Naegleria fowleri causes primary amoebic meningoencephalitis (PAM). PAM is an acute infection that lasts a few days, while GAE is a chronic to subacute infection that can last up to several months. Here, we present a literature review of 86 case reports from 1968 to 2016, in order to explore the affinity of these amoebae for particular sites of the brain, diagnostic modalities, treatment options, and disease outcomes in a comparative manner. PMID:28404683

Two distinct sensing pathways allow recognition of Klebsiella pneumoniae by Dictyostelium amoebae.

Science.gov (United States)

Lima, Wanessa C; Balestrino, Damien; Forestier, Christiane; Cosson, Pierre

2014-03-01

Recognition of bacteria by metazoans is mediated by receptors that recognize different types of microorganisms and elicit specific cellular responses. The soil amoebae Dictyostelium discoideum feeds upon a variable mixture of environmental bacteria, and it is expected to recognize and adapt to various food sources. To date, however, no bacteria-sensing mechanisms have been described. In this study, we isolated a Dictyostelium mutant (fspA KO) unable to grow in the presence of non-capsulated Klebsiella pneumoniae bacteria, but growing as efficiently as wild-type cells in the presence of other bacteria, such as Bacillus subtilis. fspA KO cells were also unable to respond to K. pneumoniae and more specifically to bacterially secreted folate in a chemokinetic assay, while they responded readily to B. subtilis. Remarkably, both WT and fspA KO cells were able to grow in the presence of capsulated LM21 K. pneumoniae, and responded to purified capsule, indicating that capsule recognition may represent an alternative, FspA-independent mechanism for K. pneumoniae sensing. When LM21 capsule synthesis genes were deleted, growth and chemokinetic response were lost for fspA KO cells, but not for WT cells. Altogether, these results indicate that Dictyostelium amoebae use specific recognition mechanisms to respond to different K. pneumoniae elements. © 2013 John Wiley & Sons Ltd.

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 stu...

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.

Tinker-OpenMM: Absolute and relative alchemical free energies using AMOEBA on GPUs.

Science.gov (United States)

Harger, Matthew; Li, Daniel; Wang, Zhi; Dalby, Kevin; Lagardère, Louis; Piquemal, Jean-Philip; Ponder, Jay; Ren, Pengyu

2017-09-05

The capabilities of the polarizable force fields for alchemical free energy calculations have been limited by the high computational cost and complexity of the underlying potential energy functions. In this work, we present a GPU-based general alchemical free energy simulation platform for polarizable potential AMOEBA. Tinker-OpenMM, the OpenMM implementation of the AMOEBA simulation engine has been modified to enable both absolute and relative alchemical simulations on GPUs, which leads to a ∼200-fold improvement in simulation speed over a single CPU core. We show that free energy values calculated using this platform agree with the results of Tinker simulations for the hydration of organic compounds and binding of host-guest systems within the statistical errors. In addition to absolute binding, we designed a relative alchemical approach for computing relative binding affinities of ligands to the same host, where a special path was applied to avoid numerical instability due to polarization between the different ligands that bind to the same site. This scheme is general and does not require ligands to have similar scaffolds. We show that relative hydration and binding free energy calculated using this approach match those computed from the absolute free energy approach. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

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

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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.

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

Science.gov (United States)

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

First Record of Potentially Pathogenic Amoeba Vermamoeba vermiformis (Lobosea: Gymnamoebia Isolated from a Freshwater of Dokdo Island in the East Sea, Korea

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Jong Soo Park

2016-01-01

Full Text Available Vermamoeba vermiformis is a very important free-living amoeba for human health in association with Legionnaires’ disease and keratitis. This interesting amoeba was firstly isolated from a freshwater of Dokdo (island, which was historically used for drinking water. Trophozoites and cyst forms of V. vermiformis strain MG1 are very similar to previous reported species. Trophozoites of V. vermiformis strain MG1 showed cylindrical shape with prominent anterior hyaline region. The average ratio of length and width was about 6.5. Typically, cysts of the strain MG1 showed a spherical or slightly ovoidal shape with smooth wall, and lacked cyst pores. Some cysts had crenulatewalled ectocyst, which was separated from endocyst wall. Further, 18S rRNA gene sequence of V. vermiformis strain MG1 showed very high similarity to other V. vermiformis species (99.4%-99.9% identity. Molecular phylogenetic analysis based on 18S rRNA gene sequences clearly confirmed that the isolate was one strain of V. vermiformis with maximum bootstrap value (maximum likelihood: 100% and Bayesian posterior probability of 1. Thus, the freshwater of Dokdo in Korea could harbor potentially pathogenic amoeba that may cause diseases in humans.

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

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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.

A free-living amoeba with unusual pattern of mitochondrial structure isolated from Atlantic salmon, Salmo salar L

Czech Academy of Sciences Publication Activity Database

Dyková, Iva; Veverková, Marie; Fiala, Ivan; Macháčková, Blanka

2002-01-01

Roč. 41, - (2002), s. 415-419 ISSN 0065-1583 R&D Projects: GA AV ČR IAA6022202 Institutional research plan: CEZ:AV0Z6022909 Keywords : free-living amoeba * mitochondrial cristae * Salmo salar Subject RIV: EA - Cell Biology Impact factor: 0.446, year: 2002

Ecology of testate amoebae in an Amazonian peatland and development of a transfer function for palaeohydrological reconstruction.

Science.gov (United States)

Swindles, Graeme T; Reczuga, Monika; Lamentowicz, Mariusz; Raby, Cassandra L; Turner, T Edward; Charman, Dan J; Gallego-Sala, Angela; Valderrama, Elvis; Williams, Christopher; Draper, Frederick; Honorio Coronado, Euridice N; Roucoux, Katherine H; Baker, Tim; Mullan, Donal J

2014-08-01

Tropical peatlands represent globally important carbon sinks with a unique biodiversity and are currently threatened by climate change and human activities. It is now imperative that proxy methods are developed to understand the ecohydrological dynamics of these systems and for testing peatland development models. Testate amoebae have been used as environmental indicators in ecological and palaeoecological studies of peatlands, primarily in ombrotrophic Sphagnum-dominated peatlands in the mid- and high-latitudes. We present the first ecological analysis of testate amoebae in a tropical peatland, a nutrient-poor domed bog in western (Peruvian) Amazonia. Litter samples were collected from different hydrological microforms (hummock to pool) along a transect from the edge to the interior of the peatland. We recorded 47 taxa from 21 genera. The most common taxa are Cryptodifflugia oviformis, Euglypha rotunda type, Phryganella acropodia, Pseudodifflugia fulva type and Trinema lineare. One species found only in the southern hemisphere, Argynnia spicata, is present. Arcella spp., Centropyxis aculeata and Lesqueresia spiralis are indicators of pools containing standing water. Canonical correspondence analysis and non-metric multidimensional scaling illustrate that water table depth is a significant control on the distribution of testate amoebae, similar to the results from mid- and high-latitude peatlands. A transfer function model for water table based on weighted averaging partial least-squares (WAPLS) regression is presented and performs well under cross-validation (r(2)(apparent)= 0.76, RMSE = 4.29; r(2)(jack)= 0.68, RMSEP =5.18). The transfer function was applied to a 1-m peat core, and sample-specific reconstruction errors were generated using bootstrapping. The reconstruction generally suggests near-surface water tables over the last 3,000 years, with a shift to drier conditions at c. cal. 1218-1273 AD.

Testate amoebae analysis in the peat deposits of the swamp Dolgon’koye in the south of Western Siberia and peatland paleohydrology for last 3100 years

Science.gov (United States)

Kurina, Irina V.; Blyakharchuk, Tatiana A.

2018-03-01

Our research is devoted to paleohydrological reconstruction in the swamp located in the river valley on the piedmont of the Altai Mountains in the south of Western Siberia. The reconstruction was carried out based on rhizopod analysis for the last 3100 cal yr. A large amount of different testate amoebae was found in the peat. Total 64 testate amoebae taxa were recorded in the peat core with the most abundant being: Trinema lineare, Centropyxis aculeata, C. aerophila, Euglypha rotunda, Cryptodifflugia sp. Decrease of surface wetness in the swamp are observed 2280, 2140, 1900–600 cal yr BP and increase – in 2700, 2500–1900, 230–215 cal yr BP. The results of our reconstruction of the swamp paleohydrology agrees well with the paleoclimatic data obtained earlier for the central area of the south of Western Siberia Plain. It indicates a high sensitivity of the swamp to climatic changes in the Holocene. The rhizopod analysis proved to be very effective when used for paleohydrology reconstruction in minerotrophic peat.

Evidence of parasexual activity in "asexual amoebae" Cochliopodium spp. (Amoebozoa): extensive cellular and nuclear fusion.

Science.gov (United States)

Tekle, Yonas I; Anderson, O Roger; Lecky, Ariel F

2014-09-01

The majority of microbial eukaryotes have long been considered asexual, though new evidence indicates sex, or sexual-like (parasexual) behaviors that deviate from the usual union of two gametes, among other variant aspects. Over a dozen amoebozoans are implicated to have sexual stages. However, the exact mechanism by which sex occurs in these lineages remains elusive. This is mainly due to the diverse quality and cryptic nature of their life cycle. In this study we present evidence of some previously unreported aspects of the life cycle of an amoeba, Cochliopodium, that undergoes unusual intraspecific interactions using light microscopy and immunocytochemistry. Similar to other amoebozoans, Cochliopodium, is considered asexual with no published reports of sex or parasexuality. We also investigated environmental conditions that govern the observed intraspecific interactions. Both light microscopic and immunocytochemistry evidence demonstrates Cochliopodium undergoes cellular fusion (plasmogamy) and nuclear fusion (karyogamy). Large plasmodia eventually undergo karyogamy and contain large fused, polyploid, nuclei. These are observed to fragment, subsequently, by karyotomy (nuclear fission) and cytoplasmic fission to yield uninucleated amoebae. This process could lead to a non-meiotic, parasexual exchange of chromosomes in Cochliopodium. These findings strongly suggest that Cochliopodium is involved in parasexual activity and should no longer be considered strictly asexual. Copyright © 2014 Elsevier GmbH. All rights reserved.

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

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. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ubiquiter circovirus sequences raise challenges in laboratory diagnosis: the case of honey bee and bee mite, reptiles, and free living amoebae.

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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.

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

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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

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

International Nuclear Information System (INIS)

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

2014-01-01

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. (paper)

[i]Legionella spp[/i]., amoebae and not-fermenting Gram negative bacteria in an Italian university hospital water system

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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

On different types of hereditable changes in the viability of Amoeba protens cells x-irradiated with varying doses

International Nuclear Information System (INIS)

Bychkovskaya, I.B.; Ochinskaya, G.K.; Erokhina, G.M.

1976-01-01

Qualitatively different types of cells lethality have been observed in the posterity of amoebae irradiated with doses ranging from 0.5 to 40 kR and from 60 to 120 kR. At doses of 0.5 to 40 kR, a certain part of cells in a population dies, and the effect is characterized by stability and independency of a radiation dose, hereditable radiation damage of all the cells in the population, and by the fact that it might be caused not only by a derect action of radiation but also by a preirradiated culture medium. Higher doses (60 to 120 kR) cause a more drastic but sell stable effect. Depending on a dose value, a varying percentage of cells has shown the effect not being caused by the action of the preirradiated medium. The data obtained indicate that there are different mechanisms of hereditable radiation damages to cells caused by varying radiation doses

Preferential feeding in Naegleria fowleri; intracellular bacteria isolated from amoebae in operational drinking water distribution systems.

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Miller, Haylea C; Morgan, Matthew J; Walsh, Tom; Wylie, Jason T; Kaksonen, Anna H; Puzon, Geoffrey J

2018-05-06

The amoeba Naegleria fowleri is the causative agent of the highly fatal disease, primary amoebic meningoencephalitis, and estimated to cause 16 deaths per year in the United States alone. Colonisation of drinking water distribution systems (DWDSs) by the N. fowleri is a significant public health issue. Understanding the factors which enable this pathogen to colonise and thrive in DWDSs is critical for proper management. The microbial ecology within DWDSs may influence the ability of N. fowleri to colonise DWDSs by facilitating the availability of an appropriate food source. Using biofilm samples obtained from operational DWDSs, 16S rRNA amplicon metabarcoding was combined with genus-specific PCR and Sanger sequencing of intracellular associated bacteria from isolated amoeba and their parental biofilms to identify Meiothermus chliarophilus as a potential food source for N. fowleri. Meiothermus was confirmed as a food source for N. fowleri following successful serial culturing of axenic N. fowleri with M. chliarophilus or M. ruber as the sole food source. The ability to identify environmental and ecological conditions favourable to N. fowleri colonisation, including the detection of appropriate food sources such as Meiothermus, could provide water utilities with a predictive tool for managing N. fowleri colonisation within the DWDS. Copyright © 2018 Elsevier Ltd. All rights reserved.

Reaching an entrepreneurial management system of amoebas. A qualitative insight into the European experiences

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Urban Wiesław

2016-03-01

Full Text Available The aim of the study is an assessment of the Amoeba Management System (AMS introduction advancements in some European companies. The study takes the practically focused research approach. The approaches, achievements and phases whilst introducing the AMS principles by companies are observed and critically assessed. First insight into the challenges of AMS introduction is taken basing on critical study of the literature output. The scientific studies and managerial publications are taken into consideration. The empirical part of the study is based on the qualitative approach. A multiple case study methodology is employed. The research objects are three companies, one of them operates in Sweden, the next two in Poland. Each of them have different experiences in AMS implementation, they also manifest different management styles and habits. The study demonstrates that AMS is a very prospective management methodology which can support companies in employees commitment during their journey towards operational excellence. The analysis results show different motivations for AMS introduction as well as different development paths, these are harmonized with different management styles in companies and culture occurring in countries. The study is particularly valuable because this is one of the first empirical investigations of AMS implementation in European companies. In the field of theory the study proposes the four level scale for amoebas system maturity. This scale allows to classify companies following AMS principles and, at the same time, this scale is also the kind of path of AMS implementation. The study points out basic tools for companies which support AMS implementation. These tools are already known in management literature, but experience of investigated companies shows that they are fundamental for successful AMS implementation.

Amoeba-like self-oscillating polymeric fluids with autonomous sol-gel transition.

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Onoda, Michika; Ueki, Takeshi; Tamate, Ryota; Shibayama, Mitsuhiro; Yoshida, Ryo

2017-07-13

In the field of polymer science, many kinds of polymeric material systems that show a sol-gel transition have been created. However, most systems are unidirectional stimuli-responsive systems that require physical signals such as a change in temperature. Here, we report on the design of a block copolymer solution that undergoes autonomous and periodic sol-gel transition under constant conditions without any on-off switching through external stimuli. The amplitude of this self-oscillation of the viscosity is about 2,000 mPa s. We also demonstrate an intermittent forward motion of a droplet of the polymer solution synchronized with the autonomous sol-gel transition. This polymer solution bears the potential to become the base for a type of slime-like soft robot that can transform its shape kaleidoscopically and move autonomously, which is associated with the living amoeba that moves forward by a repeated sol-gel transition.

The reconstruction of late Holocene depth-to-water-table based on testate amoebae in an eastern Australian mire

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Zheng, X.; Money, S.; Hope, G.

2017-12-01

There are relatively few quantitative palaeo-hydrological records available in eastern Australia, and those that are available, for example from dendroclimatology and the reconstruction of lake level, are often relatively short or have a relatively coarse temporal resolution (e.g. Wilkins et al. 2013; Palmer et al. 2015). Testate amoebae, a widely used hydrological proxy in the Northern Hemisphere, were used here to reconstruct depth to water table (DWT) at Snowy Flat, which is a Sphagnum-Richea-Empodismahigh altitude (1618 m asl) shrub bog in the Australian Capital Territory, Australia. Testate amoebae were quantified in a Snowy Flat core representing 4,200 cal Y BP and the community composition was used to reconstruct DWT based on our recently established transfer functions. Results from three different types of transfer functions (Fig. 1) consistently show there was a decreasing DWT (wetter) period centred on about 3350 cal Y BP, a trend towards increased dryness from about 3300 to 2200 cal Y BP and a distinctly drier period 850 to 700 cal Y BP which was immediately followed by a wetter period from 700 to 500 cal Y BP. We discuss these episodes and trends in relation to the drivers of climatic variability in this region and in particular, by comparing our results with other south-eastern Australia records, comment on the history of the southern annular mode.

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.

Amoebae of the genera Vannella Bovee, 1965 and Platyamoeba Page, 1969 isolated from fish and their phylogeny inferred from SSU rRNA gene and ITS sequences

Czech Academy of Sciences Publication Activity Database

Dyková, Iva; Boháčová, Lenka; Fiala, Ivan; Macháčková, Blanka; Pecková, Hana; Dvořáková, Helena

2005-01-01

Roč. 41, č. 3 (2005), s. 219-230 ISSN 0932-4739 R&D Projects: GA AV ČR IAA6022202 Institutional research plan: CEZ:AV0Z60220518 Keywords : fish-isolated amoebae * Vannella * Platyamoeba Subject RIV: EA - Cell Biology Impact factor: 1.253, year: 2005

MicroRNAs in Amoebozoa: deep sequencing of the small RNA population in the social amoeba Dictyostelium discoideum reveals developmentally regulated microRNAs.

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Avesson, Lotta; Reimegård, Johan; Wagner, E Gerhart H; Söderbom, Fredrik

2012-10-01

The RNA interference machinery has served as a guardian of eukaryotic genomes since the divergence from prokaryotes. Although the basic components have a shared origin, silencing pathways directed by small RNAs have evolved in diverse directions in different eukaryotic lineages. Micro (mi)RNAs regulate protein-coding genes and play vital roles in plants and animals, but less is known about their functions in other organisms. Here, we report, for the first time, deep sequencing of small RNAs from the social amoeba Dictyostelium discoideum. RNA from growing single-cell amoebae as well as from two multicellular developmental stages was sequenced. Computational analyses combined with experimental data reveal the expression of miRNAs, several of them exhibiting distinct expression patterns during development. To our knowledge, this is the first report of miRNAs in the Amoebozoa supergroup. We also show that overexpressed miRNA precursors generate miRNAs and, in most cases, miRNA* sequences, whose biogenesis is dependent on the Dicer-like protein DrnB, further supporting the presence of miRNAs in D. discoideum. In addition, we find miRNAs processed from hairpin structures originating from an intron as well as from a class of repetitive elements. We believe that these repetitive elements are sources for newly evolved miRNAs.

Radiation effects on the species-specific cell sorting-out of the cellular slime molds

International Nuclear Information System (INIS)

Satow, Takashi

1976-01-01

The effects of gamma-rays irradiation on the development and the species-specific cell sorting-out of the cellular slime mold, Dictyostelium discoideum, were investigated. The interphase amoebae of the organism showed extremely resistant to 60 Co gamma-rays. The percentage of non-stained cells estimated by dye staining method was more than 90% at the dose of 270 kR. The amoebae irradiated at 270 kR performed the development similar in the most respects to that of the un-irradiated amoebae except that a little portion of the fruiting bodies were abnormal and that the appearance of aggregates and slugs delayed 3 hrs. The ability of the species-specific cell sorting-out was not affected by gamma-rays irradiation at 270 kR. (auth.)

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

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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.

Review: Occurrence of the pathogenic amoeba Naegleria fowleri in groundwater

Science.gov (United States)

Bright, Kelly R.; Gerba, Charles P.

2017-06-01

Naegleria fowleri is a thermophilic free-living amoeba found worldwide in soils and warm freshwater. It is the causative agent of primary amebic meningoencephalitis, a nearly always fatal disease afflicting mainly children and young adults. Humans are exposed to the organism via swimming, bathing, or other recreational activity during which water is forcefully inhaled into the upper nasal passages. Although many studies have looked at the occurrence of N. fowleri in surface waters, limited information is available regarding its occurrence in groundwater and geothermally heated natural waters such as hot springs. This paper reviews the current literature related to the occurrence of N. fowleri in these waters and the methods employed for its detection. Case reports of potential groundwater exposures are also included. Despite increased interest in N. fowleri in recent years due to well-publicized cases linked to drinking water, many questions still remain unanswered. For instance, why the organism persists in some water sources and not in others is not well understood. The role of biofilms in groundwater wells and plumbing in individual buildings, and the potential for warming due to climate change to expand the occurrence of the organism into new regions, are still unclear. Additional research is needed to address these questions in order to better understand the ecology of N. fowleri and the conditions that result in greater risks to bathers.

Gold Nanoparticle Conjugation Enhances the Antiacanthamoebic Effects of Chlorhexidine

Science.gov (United States)

Aqeel, Yousuf; Siddiqui, Ruqaiyyah; Anwar, Ayaz; Shah, Muhammad Raza

2015-01-01

Acanthamoeba keratitis is a serious infection with blinding consequences and often associated with contact lens wear. Early diagnosis, followed by aggressive topical application of drugs, is a prerequisite in successful treatment, but even then prognosis remains poor. Several drugs have shown promise, including chlorhexidine gluconate; however, host cell toxicity at physiologically relevant concentrations remains a challenge. Nanoparticles, subcolloidal structures ranging in size from 10 to 100 nm, are effective drug carriers for enhancing drug potency. The overall aim of the present study was to determine whether conjugation with gold nanoparticles enhances the antiacanthamoebic potential of chlorhexidine. Gold-conjugated chlorhexidine nanoparticles were synthesized. Briefly, gold solution was mixed with chlorhexidine and reduced by adding sodium borohydride, resulting in an intense deep red color, indicative of colloidal gold-conjugated chlorhexidine nanoparticles. The synthesis was confirmed using UV-visible spectrophotometry that shows a plasmon resonance peak of 500 to 550 nm, indicative of gold nanoparticles. Further characterization using matrix-assisted laser desorption ionization-mass spectrometry showed a gold-conjugated chlorhexidine complex at m/z 699 ranging in size from 20 to 100 nm, as determined using atomic force microscopy. To determine the amoebicidal and amoebistatic effects, amoebae were incubated with gold-conjugated chlorhexidine nanoparticles. For controls, amoebae also were incubated with gold and silver nanoparticles alone, chlorhexidine alone, neomycin-conjugated nanoparticles, and neomycin alone. The findings showed that gold-conjugated chlorhexidine nanoparticles exhibited significant amoebicidal and amoebistatic effects at 5 μM. Amoebicidal effects were observed by parasite viability testing using a Trypan blue exclusion assay and flow-cytometric analysis using propidium iodide, while amoebistatic effects were observed using growth

Acetate and succinate production in amoebae, helminths, diplomonads, trichomonads and trypanosomatids: common and diverse metabolic strategies used by parasitic lower eukaryotes.

Science.gov (United States)

Bringaud, F; Ebikeme, C; Boshart, M

2010-08-01

Parasites that often grow anaerobically in their hosts have adopted a fermentative strategy relying on the production of partially oxidized end products, including lactate, glycerol, ethanol, succinate and acetate. This review focuses on recent progress in understanding acetate production in protist parasites, such as amoebae, diplomonads, trichomonads, trypanosomatids and in the metazoan parasites helminths, as well as the succinate production pathway(s) present in some of them. We also describe the unconventional organisation of the tricarboxylic acid cycle associated with the fermentative strategy adopted by the procyclic trypanosomes, which may resemble the probable structure of the primordial TCA cycle in prokaryotes.

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.

Myosin-II sets the optimal response time scale of chemotactic amoeba

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Hsu, Hsin-Fang; Westendorf, Christian; Tarantola, Marco; Bodenschatz, Eberhard; Beta, Carsten

2014-03-01

The response dynamics of the actin cytoskeleton to external chemical stimuli plays a fundamental role in numerous cellular functions. One of the key players that governs the dynamics of the actin network is the motor protein myosin-II. Here we investigate the role of myosin-II in the response of the actin system to external stimuli. We used a microfluidic device in combination with a photoactivatable chemoattractant to apply stimuli to individual cells with high temporal resolution. We directly compare the actin dynamics in Dictyostelium discodelium wild type (WT) cells to a knockout mutant that is deficient in myosin-II (MNL). Similar to the WT a small population of MNL cells showed self-sustained oscillations even in absence of external stimuli. The actin response of MNL cells to a short pulse of chemoattractant resembles WT during the first 15 sec but is significantly delayed afterward. The amplitude of the dominant peak in the power spectrum from the response time series of MNL cells to periodic stimuli with varying period showed a clear resonance peak at a forcing period of 36 sec, which is significantly delayed as compared to the resonance at 20 sec found for the WT. This shift indicates an important role of myosin-II in setting the response time scale of motile amoeba. Institute of Physics und Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24/25, 14476 Potsdam, Germany.

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.

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

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

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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.

Arcellacea (testate amoebae) as bio-indicators of road salt contamination in lakes.

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Roe, Helen M; Patterson, R Timothy

2014-08-01

Winter deicing operations occur extensively in mid- to high-latitude metropolitan regions around the world and result in a significant reduction in road accidents. Deicing salts can, however, pose a major threat to water quality and aquatic organisms. In this paper, we examine the utility of Arcellacea (testate amoebae) for monitoring lakes that have become contaminated by winter deicing salts, particularly sodium chloride. We analysed 50 sediment samples and salt-related water property variables (chloride concentrations; conductivity) from 15 lakes in the Greater Toronto Area and adjacent areas of southern Ontario, Canada. The sampled lakes included lakes in proximity to major highways and suburban roads and control lakes in forested settings away from road influences. Samples from the most contaminated lakes, with chloride concentrations in excess of 400 mg/l and conductivities of >800 μS/cm, were dominated by species typically found in brackish and/or inhospitable lake environments and by lower faunal diversities (lowest Shannon diversity index values) than samples with lower readings. Q-R-mode cluster analysis and detrended correspondence analysis (DCA) resulted in the recognition of four assemblage groupings. These reflect varying levels of salt contamination in the study lakes, along with other local influences, including nutrient loading. The response to nutrients can, however, be isolated if the planktic eutrophic indicator species Cucurbitella tricuspis is removed from the counts. The findings show that the group has considerable potential for biomonitoring in salt-contaminated lakes, and their presence in lake sediment cores may provide significant insights into long-term benthic community health, which is integral for remedial efforts.

Lamarckian evolution of the giant Mimivirus in allopatric laboratory culture on amoebae.

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Colson, Philippe; Raoult, Didier

2012-01-01

Acanthamoeba polyphaga Mimivirus has been subcultured 150 times on germ-free amoebae. This allopatric niche is very different from that found in the natural environment, where the virus is in competition with many other organisms. In this experiment, substantial gene variability and loss occurred concurrently with the emergence of phenotypically different viruses. We sought to quantify the respective roles of Lamarckian and Darwinian evolution during this experiment. We postulated that the Mimivirus genes that were down-regulated at the beginning of the allopatric laboratory culture and inactivated after 150 passages experienced Lamarckian evolution because phenotypic modifications preceded genotypic modifications, whereas we considered that genes that were highly transcribed in the new niche but were later inactivated obeyed Darwinian rules. We used the total transcript abundances and sequences described for the genes of Mimivirus at the beginning of its laboratory life and after 150 passages in allopatric culture on Acanthamoeba spp. We found a statistically significant positive correlation between the level of gene expression at the beginning of the culture and gene inactivation during the 150 passages. In particular, the mean transcript abundance at baseline was significantly lower for inactivated genes than for unchanged genes (165 ± 589 vs. 470 ± 1,625; p allopatric laboratory culture if they were encoded by variable genes than if they were encoded by conserved genes (9 vs. 15%; p = 0.062). Finally, Lamarckian evolution represented the evolutionary process encountered by 63% of the inactivated genes. Such observations may be explained by the lower level of DNA repair of useless genes.

Quadrulella texcalense sp. nov. from a Mexican desert: An unexpected new environment for hyalospheniid testate amoebae.

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Pérez-Juárez, Horacio; Serrano-Vázquez, Angélica; Kosakyan, Anush; Mitchell, Edward A D; Rivera Aguilar, Víctor M; Lahr, Daniel J G; Hernández Moreno, Mayra M; Cuellar, Humberto Macías; Eguiarte, Luis E; Lara, Enrique

2017-10-01

Quadrulella (Amoebozoa, Arcellinida, Hyalospheniidae) is a genus of testate amoebae with unmistakable morphology, which secretes characteristic square plates to reinforce the test. They are mainly known from fens and freshwater habitats and have never been documented in deserts. We describe a new species, Quadrulella texcalense, from biological soil crusts in the intertropical desert of Tehuacán (state of Puebla, Mexico). Quadrulella texcalense occurred only at altitudes between 2140 and 2221m.a.s.l., together with the bryophyte genera Pseudocrossidium, Weissia, Bryum, Didymodon, Neohyophyla and Aloina. The soil was extremely dry (moisture of 1.97-2.6%), which contrasts sharply with previous reports for the Quadrulella genus. Single cell mitochondrial cytochrome oxidase I (COI) barcoding of thirteen isolated cells showed an important morphological variability despite having all the same COI barcode sequence. Quadrulella texcalense was placed in a tree containing other Hyalsopheniidae, including a newly barcoded South African species, Q. elegans. Q. texcalense unambiguously branched within genus Quadrulella in a compact clade but with a long branch, suggesting accelerated evolution due to a transition towards a new environment and/or under-sampling. Copyright © 2017 Elsevier GmbH. All rights reserved.

Hydroecology of Amazonian lacustrine Arcellinida (testate amoebae): A case study from Lake Quistococha, Peru.

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Patterson, R Timothy; Huckerby, Gail; Kelly, Thomas J; Swindles, Graeme T; Nasser, Nawaf A

2015-10-01

Organic rich sediments were obtained from seven core tops taken in Lake Quistococha, near the city of Iquitos in the Peruvian Amazon. Subsamples from 0 to 4cm depth in each core were analyzed under dissecting light microscopy to carry out the first investigation of Arcellinida (testate lobose amoebae) from a lacustrine environment in this ecologically important region. The fauna was characterized by a low diversity, low abundance community dominated by centropyxids. This fauna is similar to 'stressed' assemblages reported from temperate latitudes, except that test concentrations were two orders of magnitude lower than typical in temperate lakes. Principle arcellinidan stressors in Lake Quistococha likely include the low pH 4 conditions in the lake, and a general lack of suitable minerogenic material to construct tests in the organic rich lake substrate. The low pH conditions are the result of runoff and seepage of water high in dissolved organic carbon from the adjacent similarly low pH 4 terrestrial peatland. The dearth of minerogenic material is the result of the lake being isolated from riverine input for the past ∼2000 years, even during flooding events. Other limiting factors contributing to depressed arcellinidan populations may include nutrient supply, predation pressure, competition, and post-mortem taphonomic factors. Copyright © 2015 Elsevier GmbH. All rights reserved.

Response of sphagnum peatland testate amoebae to a 1-year transplantation experiment along an artificial hydrological gradient.

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Marcisz, Katarzyna; Fournier, Bertrand; Gilbert, Daniel; Lamentowicz, Mariusz; Mitchell, Edward A D

2014-05-01

Peatland testate amoebae (TA) are well-established bioindicators for depth to water table (DWT), but effects of hydrological changes on TA communities have never been tested experimentally. We tested this in a field experiment by placing Sphagnum carpets (15 cm diameter) collected in hummock, lawn and pool microsites (origin) at three local conditions (dry, moist and wet) using trenches dug in a peatland. One series of samples was seeded with microorganism extract from all microsites. TA community were analysed at T0: 8-2008, T1: 5-2009 and T2: 8-2009. We analysed the data using conditional inference trees, principal response curves (PRC) and DWT inferred from TA communities using a transfer function used for paleoecological reconstruction. Density declined from T0 to T1 and then increased sharply by T2. Species richness, Simpson diversity and Simpson evenness were lower at T2 than at T0 and T1. Seeded communities had higher species richness in pool samples at T0. Pool samples tended to have higher density, lower species richness, Simpson diversity and Simpson Evenness than hummock and/or lawn samples until T1. In the PRC, the effect of origin was significant at T0 and T1, but the effect faded away by T2. Seeding effect was strongest at T1 and lowest vanished by T2. Local condition effect was strong but not in line with the wetness gradient at T1 but started to reflect it by T2. Likewise, TA-inferred DWT started to match the experimental conditions by T2, but more so in hummock and lawn samples than in pool samples. This study confirmed that TA responds to hydrological changes over a 1-year period. However, sensitivity of TA to hydrological fluctuations, and thus the accuracy of inferred DWT changes, was habitat specific, pool TA communities being least responsive to environmental changes. Lawns and hummocks may be thus better suited than pools for paleoecological reconstructions. This, however, contrasts with the higher prediction error and species' tolerance for

An evolutionarily significant unicellular strategy in response to starvation stress in Dictyostelium social amoebae [v1; ref status: indexed, http://f1000r.es/3hg

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Darja Dubravcic

2014-06-01

Full Text Available The social amoeba Dictyostelium discoideum is widely studied for its multicellular development program as a response to starvation and constitutes a model of choice in microbial cooperation studies. Aggregates of up to 106 cells form fruiting bodies containing two cell types: (i dormant spores (~80% that can persist for months in the absence of nutrients, and (ii dead stalk cells (~20% that promote the dispersion of the spores towards nutrient-rich areas. It is often overlooked that not all cells aggregate upon starvation. Using a new quantitative approach based on time-lapse fluorescence microscopy and a low ratio of reporting cells, we have quantified this fraction of non-aggregating cells. In realistic starvation conditions, up to 15% of cells do not aggregate, which makes this third cell fate a significant component of the population-level response of social amoebae to starvation. Non-aggregating cells have an advantage over cells in aggregates since they resume growth earlier upon arrival of new nutrients, but have a shorter lifespan under prolonged starvation. We find that phenotypic heterogeneities linked to cell nutritional state bias the representation of cells in the aggregating vs. non-aggregating fractions, and thus regulate population partitioning. Next, we report that the fraction of non-aggregating cells depends on genetic factors that regulate the timing of starvation, signal sensing efficiency and aggregation efficiency. In addition, interactions between clones in mixtures of non-isogenic cells affect the partitioning of each clone into both fractions. We further test the evolutionary significance of the non-aggregating cell fraction. The partitioning of cells into aggregating and non-aggregating fractions is optimal in fluctuating environments with an unpredictable duration of starvation periods. D. discoideum thus constitutes a model system lying at the intersection of microbial cooperation and bet hedging, defining a new

Systematic Analysis of γ-Aminobutyric Acid (GABA) Metabolism and Function in the Social Amoeba Dictyostelium discoideum*

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Wu, Yuantai; Janetopoulos, Chris

2013-01-01

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. PMID:23548898

Influence of climate and geography on the occurrence of Legionella and amoebae in composting facilities.

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

2014-11-24

The incidence of Legionnaires' disease (LD) in southern Switzerland is three times higher than in northern Switzerland. Climatic and geographic factors may be potential causes for this difference.We studied the prevalence of Legionella and free-living amoebae (FLA) in compost and bioaerosol in two Swiss regions to understand the role of climate and geography in the transmission of LD. We also tried to investigate whether or not compost storage duration would influence the composition of Legionella and FLA communities. A larger proportion of compost heaps in facilities from southern Switzerland harbor more diverse Legionella compared to the north (P=0.0146). FLA were isolated from composts in northern facilities at slightly higher rates (88.2% vs. 69.2%) and at lower rates from bioaerosols (6.3% vs. 13%) than in southern Switzerland. The diversity of FLA was higher in northern than in southern Switzerland (80% vs. 65%). A general decrease in the presence and variety of species was observed with decreasing compost storage time length. A discriminant model showed that values of vapour pressure, relative humidity and temperature distinguish the two regions, which were also characterised by different contamination rates by FLA and Legionella. The duration of outdoor storage may favour contamination of the compost by Legionella, and may increase the number and isolation of Legionella naturally occurring in compost. The climate in the south seems to favour higher Legionella contamination of compost heaps: this could explain the higher incidence of LD in southern Switzerland.

Unveiling exceptional Baltic bog ecohydrology, autogenic succession and climate change during the last 2000 years in CE Europe using replicate cores, multi-proxy data and functional traits of testate amoebae

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Gałka, Mariusz; Tobolski, Kazimierz; Lamentowicz, Łukasz; Ersek, Vasile; Jassey, Vincent E. J.; van der Knaap, Willem O.; Lamentowicz, Mariusz

2017-01-01

We present the results of high-resolution, multi-proxy palaeoecological investigations of two parallel peat cores from the Baltic raised bog Mechacz Wielki in NE Poland. We aim to evaluate the role of regional climate and autogenic processes of the raised bog itself in driving the vegetation and hydrology dynamics. Based on partly synchronous changes in Sphagnum communities in the two study cores we suggest that extrinsic factors (climate) played an important role as a driver in mire development during the bog stage (500-2012 CE). Using a testate amoebae transfer function, we found exceptionally stable hydrological conditions during the last 2000 years with a relatively high water table and lack of local fire events that allowed for rapid peat accumulation (2.75 mm/year) in the bog. Further, the strong correlation between pH and community-weighted mean of testate amoeba traits suggests that other variables than water-table depth play a role in driving microbial properties under stable hydrological conditions. There is a difference in hydrological dynamics in bogs between NW and NE Poland until ca 1500 CE, after which the water table reconstructions show more similarities. Our results illustrate how various functional traits relate to different environmental variables in a range of trophic and hydrological scenarios on long time scales. Moreover, our data suggest a common regional climatic forcing in Mechacz Wielki, Gązwa and Kontolanrahka. Though it may still be too early to attempt a regional summary of wetness change in the southern Baltic region, this study is a next step to better understand the long-term peatland palaeohydrology in NE Europe.

Presence of Legionella and Free-Living Amoebae in Composts and Bioaerosols from Composting Facilities

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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. PMID:23844174

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

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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.

Environmental factors shaping cultured free-living amoebae and their associated bacterial community within drinking water network.

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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. Copyright © 2016 Elsevier Ltd. All rights reserved.

Amoeba-inspired Tug-of-War algorithms for exploration-exploitation dilemma in extended Bandit Problem.

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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. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

The TOM Complex of Amoebozoans: the Cases of the Amoeba Acanthamoeba castellanii and the Slime Mold Dictyostelium discoideum.

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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. Copyright © 2015 The Authors. Published by Elsevier GmbH.. All rights reserved.

Detection of viable Helicobacter pylori inside free-living amoebae in wastewater and drinking water samples from Eastern Spain.

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Moreno-Mesonero, Laura; Moreno, Yolanda; Alonso, José Luis; Ferrús, M Antonia

2017-10-01

Helicobacter pylori is one of the most concerning emerging waterborne pathogens. It has been suggested that it could survive in water inside free-living amoebae (FLA), but nobody has studied this relationship in the environment yet. Thus, we aimed to detect viable H. pylori cells from inside FLA in water samples. Sixty-nine wastewater and 31 drinking water samples were collected. FLA were purified and identified by PCR and sequencing. For exclusively detecting H. pylori inside FLA, samples were exposed to sodium hypochlorite and assayed by specific PMA-qPCR, DVC-FISH and culture. FLA were detected in 38.7% of drinking water and 79.7% of wastewater samples, even after disinfection. In wastewater, Acanthamoeba spp. and members of the family Vahlkampfiidae were identified. In drinking water, Acanthamoeba spp. and Echinamoeba and/or Vermamoeba were present. In 39 (58.2%) FLA-positive samples, H. pylori was detected by PMA-qPCR. After DVC-FISH, 21 (31.3%) samples harboured viable H. pylori internalized cells. H. pylori was cultured from 10 wastewater samples. To our knowledge, this is the first report that demonstrates that H. pylori can survive inside FLA in drinking water and wastewater, strongly supporting the hypothesis that FLA could play an important role in the transmission of H. pylori to humans. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

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

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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

Polarization and charge transfer in the hydration of chloride ions

International Nuclear Information System (INIS)

Zhao Zhen; Rogers, David M.; Beck, Thomas L.

2010-01-01

A theoretical study of the structural and electronic properties of the chloride ion and water molecules in the first hydration shell is presented. The calculations are performed on an ensemble of configurations obtained from molecular dynamics simulations of a single chloride ion in bulk water. The simulations utilize the polarizable AMOEBA force field for trajectory generation and MP2-level calculations are performed to examine the electronic structure properties of the ions and surrounding waters in the external field of more distant waters. The ChelpG method is employed to explore the effective charges and dipoles on the chloride ions and first-shell waters. The quantum theory of atoms in molecules (QTAIM) is further utilized to examine charge transfer from the anion to surrounding water molecules. The clusters extracted from the AMOEBA simulations exhibit high probabilities of anisotropic solvation for chloride ions in bulk water. From the QTAIM analysis, 0.2 elementary charges are transferred from the ion to the first-shell water molecules. The default AMOEBA model overestimates the average dipole moment magnitude of the ion compared to the quantum mechanical value. The average magnitude of the dipole moment of the water molecules in the first shell treated at the MP2-level, with the more distant waters handled with an AMOEBA effective charge model, is 2.67 D. This value is close to the AMOEBA result for first-shell waters (2.72 D) and is slightly reduced from the bulk AMOEBA value (2.78 D). The magnitude of the dipole moment of the water molecules in the first solvation shell is most strongly affected by the local water-water interactions and hydrogen bonds with the second solvation shell, rather than by interactions with the ion.

Binding and Endocytosis of Bovine Hololactoferrin by the Parasite Entamoeba histolytica

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Guillermo Ortíz-Estrada

2015-01-01

Full Text Available Entamoeba histolytica is a human parasite that requires iron (Fe for its metabolic function and virulence. Bovine lactoferrin (B-Lf and its peptides can be found in the digestive tract after dairy products are ingested. The aim of this study was to compare virulent trophozoites recently isolated from hamster liver abscesses with nonvirulent trophozoites maintained for more than 30 years in cultures in vitro regarding their interaction with iron-charged B-Lf (B-holo-Lf. We performed growth kinetics analyses of trophozoites in B-holo-Lf and throughout several consecutive transfers. The virulent parasites showed higher growth and tolerance to iron than nonvirulent parasites. Both amoeba variants specifically bound B-holo-Lf with a similar Kd. However, averages of 9.45 × 105 and 6.65 × 106 binding sites/cell were found for B-holo-Lf in nonvirulent and virulent amoebae, respectively. Virulent amoebae bound more efficiently to human and bovine holo-Lf, human holo-transferrin, and human and bovine hemoglobin than nonvirulent amoebae. Virulent amoebae showed two types of B-holo-Lf binding proteins. Although both amoebae endocytosed this glycoprotein through clathrin-coated vesicles, the virulent amoebae also endocytosed B-holo-Lf through a cholesterol-dependent mechanism. Both amoeba variants secreted cysteine proteases cleaving B-holo-Lf. These data demonstrate that the B-Lf endocytosis is more efficient in virulent amoebae.

Binding and Endocytosis of Bovine Hololactoferrin by the Parasite Entamoeba histolytica.

Science.gov (United States)

Ortíz-Estrada, Guillermo; Calderón-Salinas, Víctor; Shibayama-Salas, Mineko; León-Sicairos, Nidia; de la Garza, Mireya

2015-01-01

Entamoeba histolytica is a human parasite that requires iron (Fe) for its metabolic function and virulence. Bovine lactoferrin (B-Lf) and its peptides can be found in the digestive tract after dairy products are ingested. The aim of this study was to compare virulent trophozoites recently isolated from hamster liver abscesses with nonvirulent trophozoites maintained for more than 30 years in cultures in vitro regarding their interaction with iron-charged B-Lf (B-holo-Lf). We performed growth kinetics analyses of trophozoites in B-holo-Lf and throughout several consecutive transfers. The virulent parasites showed higher growth and tolerance to iron than nonvirulent parasites. Both amoeba variants specifically bound B-holo-Lf with a similar K d . However, averages of 9.45 × 10(5) and 6.65 × 10(6) binding sites/cell were found for B-holo-Lf in nonvirulent and virulent amoebae, respectively. Virulent amoebae bound more efficiently to human and bovine holo-Lf, human holo-transferrin, and human and bovine hemoglobin than nonvirulent amoebae. Virulent amoebae showed two types of B-holo-Lf binding proteins. Although both amoebae endocytosed this glycoprotein through clathrin-coated vesicles, the virulent amoebae also endocytosed B-holo-Lf through a cholesterol-dependent mechanism. Both amoeba variants secreted cysteine proteases cleaving B-holo-Lf. These data demonstrate that the B-Lf endocytosis is more efficient in virulent amoebae.

Effect of a temperature gradient on Sphagnum fallax and its associated living microbial communities: a study under controlled conditions.

Science.gov (United States)

Jassey, Vincent E J; Gilbert, Daniel; Binet, Philippe; Toussaint, Marie-Laure; Chiapusio, Geneviève

2011-03-01

Microbial communities living in Sphagnum are known to constitute early indicators of ecosystem disturbances, but little is known about their response (including their trophic relationships) to climate change. A microcosm experiment was designed to test the effects of a temperature gradient (15, 20, and 25°C) on microbial communities including different trophic groups (primary producers, decomposers, and unicellular predators) in Sphagnum segments (0-3 cm and 3-6 cm of the capitulum). Relationships between microbial communities and abiotic factors (pH, conductivity, temperature, and polyphenols) were also studied. The density and the biomass of testate amoebae in Sphagnum upper segments increased and their community structure changed in heated treatments. The biomass of testate amoebae was linked to the biomass of bacteria and to the total biomass of other groups added and, thus, suggests that indirect effects on the food web structure occurred. Redundancy analysis revealed that microbial assemblages differed strongly in Sphagnum upper segments along a temperature gradient in relation to abiotic factors. The sensitivity of these assemblages made them interesting indicators of climate change. Phenolic compounds represented an important explicative factor in microbial assemblages and outlined the potential direct and (or) indirect effects of phenolics on microbial communities.

Long-term survival of Naegleria polaris from Antarctica after 10 years of storage at 4 °C.

Science.gov (United States)

Matsuo, Junji; Nakamura, Shinji; Okubo, Torahiko; Fukui, Manabu; Yamaguchi, Hiroyuki

2018-03-01

A free-living amoeba, Naegleria is ubiquitously distributed in various natural environments. Since some Naegleria spp. are exclusively distributed in the Arctic and sub-Antarctic regions, we hypothesized that the amoeba may be useful to determine long-term survival of Naegleria in laboratory conditions at 4 °C. The main objective of the study is to determine that a species of an environmental amoebal isolated can live at low temperatures after a long time. Here, we therefore show long-term survival of an amoeba, Naegleria polaris isolated from a sediment sample, which was collected from Antarctica 10 years ago, and since stored at 4 °C. The sample was put on non-nutrient agar plates with heat-killed Escherichia coli, and then the plate was incubated at 4, 15, or 30 °C. Motile amoebae were seen only when the plate was incubated at 15 °C. The sequencing of ribosomal DNA including internal transcribed spacers (ITS) 1, 5.8S rDNA, and ITS2 region revealed the amoebae to be N. polaris, which is exclusively distributed in the Arctic and sub-Antarctic regions. Scanning electron microscopic observation showed that no typical sucker-like structure was seen on the surface of N. polaris, but the cysts were similar to those of Naegleria fowleri. Thus, our result shows, for the first time, that N. polaris can survive after 10 years of storage at 4 °C. This finding may help us understand the still undescribed effects of environmental samples on viability of amoebae.

Protozoa Drive the Dynamics of Culturable Biocontrol Bacterial Communities.

Science.gov (United States)

Müller, Maren Stella; Scheu, Stefan; Jousset, Alexandre

2013-01-01

Some soil bacteria protect plants against soil-borne diseases by producing toxic secondary metabolites. Such beneficial biocontrol bacteria can be used in agricultural systems as alternative to agrochemicals. The broad spectrum toxins responsible for plant protection also inhibit predation by protozoa and nematodes, the main consumers of bacteria in soil. Therefore, predation pressure may favour biocontrol bacteria and contribute to plant health. We analyzed the effect of Acanthamoeba castellanii on semi-natural soil bacterial communities in a microcosm experiment. We determined the frequency of culturable bacteria carrying genes responsible for the production of the antifungal compounds 2,4-diacetylphloroglucinol (DAPG), pyrrolnitrin (PRN) and hydrogen cyanide (HCN) in presence and absence of A. castellanii. We then measured if amoebae affected soil suppressiveness in a bioassay with sugar beet seedlings confronted to the fungal pathogen Rhizoctonia solani. Amoebae increased the frequency of both DAPG and HCN positive bacteria in later plant growth phases (2 and 3 weeks), as well as the average number of biocontrol genes per bacterium. The abundance of DAPG positive bacteria correlated with disease suppression, suggesting that their promotion by amoebae may enhance soil health. However, the net effect of amoebae on soil suppressiveness was neutral to slightly negative, possibly because amoebae slow down the establishment of biocontrol bacteria on the recently emerged seedlings used in the assay. The results indicate that microfaunal predators foster biocontrol bacterial communities. Understanding interactions between biocontrol bacteria and their predators may thus help developing environmentally friendly management practices of agricultural systems.

Protozoa Drive the Dynamics of Culturable Biocontrol Bacterial Communities.

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Maren Stella Müller

Full Text Available Some soil bacteria protect plants against soil-borne diseases by producing toxic secondary metabolites. Such beneficial biocontrol bacteria can be used in agricultural systems as alternative to agrochemicals. The broad spectrum toxins responsible for plant protection also inhibit predation by protozoa and nematodes, the main consumers of bacteria in soil. Therefore, predation pressure may favour biocontrol bacteria and contribute to plant health. We analyzed the effect of Acanthamoeba castellanii on semi-natural soil bacterial communities in a microcosm experiment. We determined the frequency of culturable bacteria carrying genes responsible for the production of the antifungal compounds 2,4-diacetylphloroglucinol (DAPG, pyrrolnitrin (PRN and hydrogen cyanide (HCN in presence and absence of A. castellanii. We then measured if amoebae affected soil suppressiveness in a bioassay with sugar beet seedlings confronted to the fungal pathogen Rhizoctonia solani. Amoebae increased the frequency of both DAPG and HCN positive bacteria in later plant growth phases (2 and 3 weeks, as well as the average number of biocontrol genes per bacterium. The abundance of DAPG positive bacteria correlated with disease suppression, suggesting that their promotion by amoebae may enhance soil health. However, the net effect of amoebae on soil suppressiveness was neutral to slightly negative, possibly because amoebae slow down the establishment of biocontrol bacteria on the recently emerged seedlings used in the assay. The results indicate that microfaunal predators foster biocontrol bacterial communities. Understanding interactions between biocontrol bacteria and their predators may thus help developing environmentally friendly management practices of agricultural systems.

Bacterivory: a novel dual role for thraustochytrids in the sea

Digital Repository Service at National Institute of Oceanography (India)

Raghukumar, S.

in the presence of bacteria, both species produced amoebae, which moved using pseudopodia and phagocytosed bacterial cells. Several amoebae were produced in 'sporangia', or isolated vegetative cells transformed directly into amoebae. These findings were confirmed...

Effect of Clinoptilolite and Sepiolite Nanoclays on Human and Parasitic Highly Phagocytic Cells

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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.

Susceptibility of pathogenic and nonpathogenic Naegleria ssp

International Nuclear Information System (INIS)

Whiteman, L.Y.

1988-01-01

The susceptibility of four species of Naegleria amoebae to complement-mediated lysis was determined. The amoebicidal activity of normal human serum (NHS) and normal guinea pig serum (NGPS) for Naegleria amoebae was measured by an in vitro cytotoxicity assay. Release of radioactivity from amoebae labeled with 3 H-uridine and visual observation with a compound microscope were used as indices of lysis. Susceptibility or resistance to complement-mediated lysis in vitro correlated with the in vivo pathogenic potential. Nonpathogenic Naegleria amoebae were lysed at a faster rate and at higher cell concentrations than were pathogenic amoebae. Electrophoretic analysis of NHS incubated with pathogenic or nonpathogenic Naegleria spp. demonstrated that amoebae activate the complement cascade resulting in the production of C3 and C5 complement cleavage products. Treatment with papain or trypsin for 1 h, but not with sialidase, increase the susceptibility of highly pathogenic, mouse-passaged N. fowleri to lysis. Treatment with actinomycin D, cycloheximide or various protease inhibitors for 4 h did not increase susceptibility to lysis. Neither a repair process involving de novo protein synthesis nor a complement-inactivating protease appear to account for the increase resistance of N. fowleri amoebae to complement-mediated lysis. A binding study with 125 I radiolabeled C9 indicated that the terminal complement component does not remain stably bound to the membrane of pathogenic amoebae

Peristaltic transport and mixing of cytosol through the whole body of Physarum plasmodium.

Science.gov (United States)

Iima, Makoto; Nakagaki, Toshiyuki

2012-09-01

We study how the net transport and mixing of chemicals occur in a relatively large amoeba, the true slime mold Physarum polycephalum. The shuttle streaming of the amoeba is characterized by a rhythmic flow of the order of 1 μm/s in which the protoplasm streams back and forth. To explain the experimentally observed transport of chemicals, we formulate a simplified model to consider the mechanism by which net transport can be induced by shuttle (or periodic) motion inside the amoeba. This model is independent from the details of fluid property as it is based on the mass conservation law only. Even in such a simplified model, we demonstrate that sectional oscillations play an important role in net transport and discuss the effects of the sectional boundary motion on net transport in the microorganism.

Loss of Cln3 impacts protein secretion in the social amoeba Dictyostelium.

Science.gov (United States)

Huber, Robert J

2017-07-01

Neuronal ceroid lipofuscinosis (NCL), also referred to as Batten disease, is the most common form of childhood neurodegeneration. Mutations in CLN3 cause the most prevalent subtype of the disease, which manifests during early childhood and is currently untreatable. The precise function of the CLN3 protein is still not known, which has inhibited the development of targeted therapies. In the social amoeba Dictyostelium discoideum, loss of the CLN3 homolog, Cln3, reduces adhesion during early development, which delays streaming and aggregation. The results of the present study indicate that this phenotype may be at least partly due to aberrant protein secretion in cln3 - cells. It is well-established that Cln3 localizes primarily to the contractile vacuole (CV) system in Dictyostelium, and to a lesser extent, compartments of the endocytic pathway. Intriguingly, the CV system has been linked to the secretion of proteins that do not contain a signal peptide for secretion (i.e., unconventional protein secretion). Proteins that do contain a signal peptide are secreted via a conventional mechanism involving the endoplasmic reticulum, transport through the Golgi, and secretion via vesicle release. In this study, Cln3 was observed to co-localize with the Golgi marker wheat germ agglutinin suggesting that Cln3 participates in both secretion mechanisms. Chimeras of wild-type (WT) and cln3 - cells displayed delayed streaming and aggregation, and interestingly, cln3 - cells starved in conditioned media (CM) harvested from starving WT cells showed near normal timing of streaming and aggregation suggesting aberrant protein secretion in Cln3-deficient cells. Based on these observations, LC-MS/MS was used to reveal the protein content of CM from starved cells (mass spectrometry data are available via ProteomeXchange with identifier PXD004897). A total of 450 proteins were detected in WT and cln3 - CM, of which 3 were absent in cln3 - CM. Moreover, 12 proteins that were present in

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

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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

Novel Path Towards Colistin Resistance In Pseudomonas Aeruginosa During Chronic Infection Involves Polymorphisms In Uncharacterized Glycosyltransferase Gene

DEFF Research Database (Denmark)

Hermansen, Grith Miriam Maigaard; Jelsbak, Lars

2015-01-01

Introduction: Antibiotic resistance development in the gram-negative bacterium Pseudomonas aeruginosa is an increasing problem. The effect of colistin, one of the few last resort drugs commonly given to cystic fibrosis (CF) patients, is dependent on the lipopolysaccharide (LPS) structure. We have...... inhibitory concentration by microbroth dilution, virulence in an amoebae model and LPS structure by visualization in a silver-stained gel. Results: Reversion of the SNP to reference genotype resulted in increased colistin susceptibility, reduced virulence in an amoebae model and altered LPS structure...

Modulation of Zinc Homeostasis in Acanthamoeba castellanii as a Possible Antifungal Strategy against Cryptococcus gattii

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Nicole S. Ribeiro

2017-08-01

Full Text Available Cryptococcus gattii is a basidiomycetous yeast that can be found in the environment and is one of the agents of cryptococcosis, a life-threatening disease. During its life cycle, cryptococcal cells take hold inside environmental predators such as amoebae. Despite their evolutionary distance, macrophages and amoebae share conserved similar steps of phagocytosis and microbial killing. To evaluate whether amoebae also share other antifungal strategies developed by macrophages, we investigated nutritional immunity against cryptococcal cells. We focused on zinc homeostasis modulation in Acanthamoeba castellanii infected with C. gattii. The intracellular proliferation rate (IPR in amoebae was determined using C. gattii R265 and mutants for the ZIP1 gene, which displays defects of growth in zinc-limiting conditions. We detected a reduced IPR in cells lacking the ZIP1 gene compared to wild-type strains, suggesting that amoebae produce a low zinc environment to engulfed cells. Furthermore, flow cytometry analysis employing the zinc probe Zinpyr-1 confirmed the reduced concentration of zinc in cryptococcal-infected amoebae. qRT-PCR analysis of zinc transporter-coding genes suggests that zinc export by members of the ZnT family would be involved in the reduced intracellular zinc concentration. These results indicate that amoebae may use nutritional immunity to reduce fungal cell proliferation by reducing zinc availability for the pathogen.

Whole genome sequencing of mutation accumulation lines reveals a low mutation rate in the social amoeba Dictyostelium discoideum.

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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.

Basic features of slime mould motility

Science.gov (United States)

Shirakawa, Tomohiro

2015-03-01

The plasmodium of Physarum polycephalum is a unicellular and multi-nuclear giant amoeba that is formed by fusions of myriads of uninucleate microscopic amoebae at a point in the life cycle of the organism. The very large unicellular form of the plasmodium is very uncommon in nature; on the contrary, almost all of the other higher organisms have multi-cellular bodies. Therefore, the plasmodium has an exceptional property: although the plasmodium is a unicellular organism, the size of the amoeba is variable. The smallest plasmodium consists of the fusion of two amoebae, so the smallest size is twice that of a usual amoeba. There is no upper limit to the largest size of the plasmodium, in principle. There is a record of very large plasmodium of more than a few metres. A more interesting point is that despite the variety in the size, the plasmodium can move, feed and form complex structures and adapt itself to the environment in an intelligent manner...

Litter quality as driving factor for plant nutrition via grazing of protozoa on soil microorganisms.

Science.gov (United States)

Koller, Robert; Robin, Christophe; Bonkowski, Michael; Ruess, Liliane; Scheu, Stefan

2013-08-01

Plant residues provide a major source of nitrogen (N) for plant growth. Litter N mineralization varies with litter carbon-to-nitrogen (C-to-N) ratio and presence of bacterial-feeding fauna. We assessed the effect of amoebae, major bacterial feeders in soil, on mineralization of litter of low (high quality) and high C-to-N ratio (low quality) and evaluated consequences for plant growth. We used stable isotopes to determine plant N uptake from litter and plant C partitioning. Stable isotope probing of phospholipid fatty acids was used to follow incorporation of plant C into microorganisms. Amoebae increased plant N uptake independent of litter quality and thereby the biomass of shoots and roots by 33% and 66%, respectively. Plant allocation of total (13)C to roots in low (42%) exceeded that of high-quality litter treatments (26%). Amoebae increased plant allocation of (13)C to roots by 37%. Microbial community structure and incorporation of (13)C into PLFAs varied significantly with litter quality and in the low-quality litter treatment also with the presence of amoebae. Overall, the results suggest that in particular at low nutrient conditions, root-derived C fosters the mobilization of bacterial N by protozoa, thereby increasing plant growth when microorganisms and plants compete for nutrients. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Disentangling the effects of water chemistry and substratum structure on moss-dwelling unicellular and multicellular micro-organisms in spring-fens

Czech Academy of Sciences Publication Activity Database

Hájková, P.; Bojková, J.; Fránková, Markéta; Opravilová, V.; Hájek, M.; Kintrová, K.; Horsák, M.

2011-01-01

Roč. 70, suppl.1 (2011), s. 54-64 ISSN 1129-5767 Institutional research plan: CEZ:AV0Z60050516 Keywords : diatoms * rotifers * testate amoebae Subject RIV: EF - Botanics Impact factor: 1.207, year: 2011

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.

Cellulose degradation: a therapeutic strategy in the improved treatment of Acanthamoeba infections.

Science.gov (United States)

Lakhundi, Sahreena; Siddiqui, Ruqaiyyah; Khan, Naveed Ahmed

2015-01-14

Acanthamoeba is an opportunistic free-living amoeba that can cause blinding keratitis and fatal brain infection. Early diagnosis, followed by aggressive treatment is a pre-requisite in the successful treatment but even then the prognosis remains poor. A major drawback during the course of treatment is the ability of the amoeba to enclose itself within a shell (a process known as encystment), making it resistant to chemotherapeutic agents. As the cyst wall is partly made of cellulose, thus cellulose degradation offers a potential therapeutic strategy in the effective targeting of trophozoite encased within the cyst walls. Here, we present a comprehensive report on the structure of cellulose and cellulases, as well as known cellulose degradation mechanisms with an eye to target the Acanthamoeba cyst wall. The disruption of the cyst wall will make amoeba (concealed within) susceptible to chemotherapeutic agents, and at the very least inhibition of the excystment process will impede infection recurrence, as we bring these promising drug targets into focus so that they can be explored to their fullest.

Dictyostelium discoideum as a novel host system to study the interaction between phagocytes and yeasts

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Barbara Koller

2016-10-01

Full Text Available The social amoeba Dictyostelium discoideum is a well-established model organism to study the interaction between bacteria and phagocytes. In contrast, research using D. discoideum as a host model for fungi is rare. We describe a comprehensive study, which uses D. discoideum as a host model system to investigate the interaction with apathogenic (Saccharomyces cerevisiae and pathogenic (Candida sp. yeast. We show that Dictyostelium can be co-cultivated with yeasts on solid media, offering a convenient test to study the interaction between fungi and phagocytes. We demonstrate that a number of D. discoideum mutants increase (atg1-, kil1-, kil2- or decrease (atg6- the ability of the amoebae to predate yeast cells. On the yeast side, growth characteristics, reduced phagocytosis rate, as well as known virulence factors of C. albicans (EFG1, CPH1, HGC1, ICL1 contribute to the resistance of yeast cells against predation by the amoebae. Investigating haploid C. albicans strains, we suggest using the amoebae plate test for screening purposes after random mutagenesis. Finally, we discuss the potential of our adapted amoebae plate test to use D. discoideum for risk assessment of yeast strains.

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

Heterogeneity in the genus Allovahlkampfia and the description of the new genus Parafumarolamoeba (Vahlkampfiidae; Heterolobosea)

NARCIS (Netherlands)

Geisen, Stefan; Bonkowski, Michael; Zhang, Junling; De Jonckheere, Johan F.

Abstract Heterolobosean amoebae are common and diverse members of soil protist communities. In this study, we isolated seven strains of amoebae from soil samples taken in Tibet (at high altitude), Sardinia and the Netherlands, all resembling to belong to a similar heterolobosean morphospecies.

Polarizable protein packing

KAUST Repository

Ng, Albert H.; Snow, Christopher D.

2011-01-01

To incorporate protein polarization effects within a protein combinatorial optimization framework, we decompose the polarizable force field AMOEBA into low order terms. Including terms up to the third-order provides a fair approximation to the full

Journal of Biosciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

However, our studies have shown that amoebae and giardia contain splicoeosomal introns, ras-family signal-transduction proteins, ATP-binding casettes (ABC)-family drug transporters, Golgi, and a mitochondrion-derived organelle (amoebae only). These results suggest that most of the organelles of higher eukaryotes ...

RNA synthesis during germination of UV-irradiated Dictyostelium discoideum spores

International Nuclear Information System (INIS)

Okaichi, Kumio

1987-01-01

UV irradiation to the spores of Dictyostelium discoideum NC4 resulted in a more prolonged delay of amoeba-emergence from swollen spores with increasing UV fluence. During the germination, an inhibition of total RNA synthesis and a shift of stage of maximum RNA synthesis to the later period were observed. The maximum poly(A) + RNA synthetic activity was found on an early stage of amoeba-emergence prior about 1 h to the beginning of rRNA synthesis in unirradiated spore germination; but, in UV-irradiated spore germination, the stage of maximum poly(A) + RNA synthesis shifted to the later stage of germination with increasing UV fluence. A decreased synthesis of poly(A) + RNA and a severe inhibition of rRNA synthesis were observed on UV-irradiated and germinated spores, but no significant inhibition of 4 - 5 S RNA synthesis was detected. Actinomycin D suppressed almost completely the rRNA synthesis of emerged amoebae but the drug apparently did not affect the emergence of amoebae at any stage of germination. It was postulated that the delay of amoeba-emergence in UV-irradiated spore must be mainly due to the shift of the stage of maximum synthesis of poly(A) + RNA to the later stage of germination. (author)

[Detection and differentiation of Entamoeba histolytica and Entamoeba dispar by polymerase chain reaction in a community in Zulia State, Venezuela].

Science.gov (United States)

Rivero, Zulbey; Bracho, Angela; Calchi, Marinella; Díaz, Iris; Acurero, Ellen; Maldonado, Adriana; Chourio, Glenis; Arráiz, Nailet; Corzo, Gilbert

2009-01-01

Differential identification of Entamoeba histolytica and Entamoeba dispar is essential for both appropriate patient treatment and epidemiological purposes. To determine the prevalence of these amoeba infections in Santa Rosa de Agua (Maracaibo, Zulia State, Venezuela), a PCR assay using specific primers for each species was standardized and applied. 204 stool samples were analyzed through direct microscopic examination with SSF (0.85%) and lugol, formol-ether concentration, and PCR. Under direct microscopy, 42 individuals (20.58%) presented the E. histolytica/E. dispar complex. Meanwhile PCR showed 47 positive cases for these amoebas: 22 E. histolytica (10.78%), 16 E. dispar (7.84%), and 9 (4.41%) mixed infections. There was no significant difference in the presence of E. histolytica and/or E. dispar according to either gender or age. There were no cases of these amoebas in children under 2 years of age. Observed frequency of E. histolytica (31/204) shows the endemic nature of amoeba infection in this community.

An Assessment of Sub-Meter Scale Spatial Variability of Arcellinida (Testate Lobose Amoebae) Assemblages in a Temperate Lake: Implications for Limnological Studies.

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Steele, Riley E; Nasser, Nawaf A; Patterson, R Timothy; Gregory, Braden R B; Roe, Helen M; Reinhardt, Eduard G

2018-03-04

Arcellinida (testate lobose amoebae), a group of benthic protists, were examined from 46 sediment-water interface samples collected from oligotrophic Oromocto Lake, New Brunswick, Canada. To assess (1) assemblage homogeneity at a sub-meter spatial scale and (2) the necessity for collecting samples from multiple stations during intra-lake surveys; multiple samples were collected from three stations (quadrats 1, 2, and 3) across the north basin of Oromocto Lake, with quadrat 1 (n = 16) being the furthest to the west, quadrat 2 (n = 15) situated closer to the center of the basin, and quadrat 3 (n = 15) positioned 300 m south of the mouth of Dead Brook, an inlet stream. Results from cluster analysis and non-metric multidimensional scaling (NMDS) analysis identified two major Arcellinida assemblages, A1 and A2, the latter containing two sub-assemblages (A2a and A2b). Redundancy analysis and variance partitioning results indicated that seven statistically significant environmental variables (K, S, Sb, Ti, Zn, Fe, and Mn) explained 41.5% of the total variation in the Arcellinida distribution. Iron, Ti and K, indicators of detrital runoff, had the greatest influence on assemblage variance. The results of this study reveal that closely spaced samples (~ 10 cm) in an open-water setting are comprised of homogenous arcellinidan assemblages, indicating that replicate sampling is not required. The results, however, must be tempered with respect to the various water properties and physical characteristics that comprise individual lakes as collection of several samples may likely be necessary when sampling multiple sites of a lake basin characterized by varying water depths (e.g., littoral zone vs. open water), or lakes impacted by geogenic or anthropogenic stressors (e.g., eutrophication, or industrial contamination).

Molecular Detection of Legionella spp. and their associations with Mycobacterium spp., Pseudomonas aeruginosa and amoeba hosts in a drinking water distribution system.

Science.gov (United States)

Lu, J; Struewing, I; Vereen, E; Kirby, A E; Levy, K; Moe, C; Ashbolt, N

2016-02-01

This study investigated waterborne opportunistic pathogens (OPs) including potential hosts, and evaluated the use of Legionella spp. for indicating microbial water quality for OPs within a full-scale operating drinking water distribution system (DWDS). To investigate the occurrence of specific microbial pathogens within a major city DWDS we examined large volume (90 l drinking water) ultrafiltration (UF) concentrates collected from six sites between February, 2012 and June, 2013. The detection frequency and concentration estimates by qPCR were: Legionella spp. (57%/85 cell equivalent, CE l(-1) ), Mycobacterium spp. (88%/324 CE l(-1) ), Pseudomonas aeruginosa (24%/2 CE l(-1) ), Vermamoeba vermiformis (24%/2 CE l(-1) ) and Acanthamoeba spp. (42%/5 cyst equivalent, CE l(-1) ). There was no detection of the following microorganisms: human faecal indicator Bacteroides (HF183), Salmonella enterica, Campylobacter spp., Escherichia coli O157:H7, Giardia intestinalis, Cryptosporidium spp. or Naegleria fowleri. There were significant correlations between the qPCR signals of Legionella spp. and Mycobacterium spp., and their potential hosts V. vermiformis and Acanthamoeba spp. Sequencing of Legionella spp. demonstrated limited diversity, with most sequences coming from two dominant groups, of which the larger dominant group was an unidentified species. Other known species including Legionella pneumophila were detected, but at low frequency. The densities of Legionella spp. and Mycobacterium spp. were generally higher (17 and 324 folds, respectively) for distal sites relative to the entry point to the DWDS. Legionella spp. occurred, had significant growth and were strongly associated with free-living amoebae (FLA) and Mycobacterium spp., suggesting that Legionella spp. could provide a useful DWDS monitoring role to indicate potential conditions for non-faecal OPs. The results provide insight into microbial pathogen detection that may aid in the monitoring of microbial water

Prevalence of pathogenic free-living amoeba and other protozoa in natural and communal piped tap water from Queen Elizabeth protected area, Uganda.

Science.gov (United States)

Sente, Celsus; Erume, Joseph; Naigaga, Irene; Mulindwa, Julius; Ochwo, Sylvester; Magambo, Phillip Kimuda; Namara, Benigna Gabriela; Kato, Charles Drago; Sebyatika, George; Muwonge, Kevin; Ocaido, Michael

2016-08-03

Pathogenic water dwelling protozoa such as Acanthamoeba spp., Hartmannella spp., Naegleria spp., Cryptosporidium spp. and Giardia spp. are often responsible for devastating illnesses especially in children and immunocompromised individuals, yet their presence and prevalence in certain environment in sub-Saharan Africa is still unknown to most researchers, public health officials and medical practitioners. The objective of this study was to establish the presence and prevalence of pathogenic free-living amoeba (FLA), Cryptosporidium and Giardia in Queen Elizabeth Protected Area (QEPA). Samples were collected from communal taps and natural water sites in QEPA. Physical water parameters were measured in situ. The samples were processed to detect the presence of FLA trophozoites by xenic cultivation, Cryptosporidium oocysts by Ziehl-Neelsen stain and Giardia cysts by Zinc Sulphate floatation technique. Parasites were observed microscopically, identified, counted and recorded. For FLA, genomic DNA was extracted for amplification and sequencing. Both natural and tap water sources were contaminated with FLA, Cryptosporidium spp. and Giardia spp. All protozoan parasites were more abundant in the colder rainy season except for Harmannella spp. and Naegleria spp. which occurred more in the warmer months. The prevalence of all parasites was higher in tap water than in natural water samples. There was a strong negative correlation between the presence of Acanthamoeba spp., Hartmannella spp., Cryptosporidium spp. and Giardia spp. with Dissolved Oxygen (DO) (P protozoa that could possibly be the cause of a number of silent morbidities and mortalities among rural households in QEPA. This implies that water used by communities in QEPA is of poor quality and predisposes them to a variety of protozoan infections including the FLA whose public health importance was never reported, thus necessitating adoption of proper water safety measures.

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

Lack of Outer Membrane Protein A Enhances the Release of Outer Membrane Vesicles and Survival of Vibrio cholerae and Suppresses Viability of Acanthamoeba castellanii

Directory of Open Access Journals (Sweden)

Soni Priya Valeru

2014-01-01

Full Text Available Vibrio cholerae, the causative agent of the diarrhoeal disease cholera, survives in aquatic environments. The bacterium has developed a survival strategy to grow and survive inside Acanthamoeba castellanii. It has been shown that V. cholerae expresses outer membrane proteins as virulence factors playing a role in the adherence to interacted host cells. This study examined the role of outer membrane protein A (OmpA and outer membrane vesicles (OMVs in survival of V. cholerae alone and during its interaction with A. castellanii. The results showed that an OmpA mutant of V. cholerae survived longer than wild-type V. cholerae when cultivated alone. Cocultivation with A. castellanii enhanced the survival of both bacterial strains and OmpA protein exhibited no effect on attachment, engulfment, and survival inside the amoebae. However, cocultivation of the OmpA mutant of V. cholerae decreased the viability of A. castellanii and this bacterial strain released more OMVs than wild-type V. cholerae. Surprisingly, treatment of amoeba cells with OMVs isolated from the OmpA mutant significantly decreased viable counts of the amoeba cells. In conclusion, the results might highlight a regulating rule for OmpA in survival of V. cholerae and OMVs as a potent virulence factor for this bacterium towards eukaryotes in the environment.

Vernalophrys algivore gen. nov., sp. nov. (Rhizaria: Cercozoa: Vampyrellida), a New Algal Predator Isolated from Outdoor Mass Culture of Scenedesmus dimorphus.

Science.gov (United States)

Gong, Yingchun; Patterson, David J; Li, Yunguang; Hu, Zixuan; Sommerfeld, Milton; Chen, Yongsheng; Hu, Qiang

2015-06-15

Microbial contamination is the main cause of loss of biomass yield in microalgal cultures, especially under outdoor environmental conditions. Little is known about the identities of microbial contaminants in outdoor mass algal cultures. In this study, a new genus and species of vampyrellid amoeba, Vernalophrys algivore, is described from cultures of Scenedesmus dimorphus in open raceway ponds and outdoor flat-panel photobioreactors. This vampyrellid amoeba was a significant grazer of Scenedesmus and was frequently associated with a very rapid decline in algal numbers. We report on the morphology, subcellular structure, feeding behavior, molecular phylogeny, and life cycle. The new amoeba resembles Leptophrys in the shape of trophozoites and pseudopodia and in the mechanism of feeding (mainly by engulfment). It possesses two distinctive regions in helix E10_1 (nucleotides 117 to 119, CAA) and E23_1 (nucleotides 522 and 523, AG) of the 18S rRNA gene. It did not form a monophyletic group with Leptophrys in molecular phylogenetic trees. We establish a new genus, Vernalophrys, with the type species Vernalophrys algivore. The occurrence, impact of the amoeba on mass culture of S. dimorphus, and means to reduce vampyrellid amoeba contamination in Scenedesmus cultures are addressed. The information obtained from this study will be useful for developing an early warning system and control measures for preventing or treating this contaminant in microalgal mass cultures. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Inefficacy of marketed contact lens disinfection solutions against keratitis-causing Acanthamoeba castellanii belonging to the T4 genotype.

Science.gov (United States)

Lakhundi, Sahreena; Khan, Naveed Ahmed; Siddiqui, Ruqaiyyah

2014-06-01

The aim of this study was to assess the anti-amoebic effects of marketed contact lens disinfecting solutions. Using amoebistatic, amoebicidal, and cysticidal assays, nine different contact lens solutions were tested including: ReNu MultiPlus, DuraPlus, Ultimate Plus, OptiFree Replenish, OptiFree Express, Kontex Clean, Kontex Normal, Kontex Multisol extra+, Kontex Soak. In vitro growth inhibition (amoebistatic) assays were performed by incubating Acanthamoeba castellanii with aforementioned contact lens disinfection solutions as per manufacturer's instructions in the growth medium for up to 48h at 30°C. To determine amoebicidal and cysticidal effects, amoebae were incubated with contact lens solutions in phosphate buffered saline for 24h and viability was determined by haemocytometer counting as well as re-inoculating them in the growth medium. For controls, solutions were tested against bacterial corneal pathogen, Pseudomonas aeruginosa, as well as amoebae were incubated with the solvent alone. Of the nine contact lens solutions tested, none of them showed potent amoebicidal effects. Only DuraPlus and OptiFree Replenish exhibited trophozoite lysis of 85.3% and 73.7% respectively. In contrast, all contact lens disinfection solutions except Kontex Clean, Kontex Normal, Kontex Multisol extra+, tested showed amoebistatic effects. Importantly, none of the contact lens disinfection solutions exhibited cysticidal effects using qualitative assays, i.e., cysts treated with aforementioned solutions re-emerged as viable amoebae upon inoculation in the growth medium. However, more than 3-log reduction was observed when ReNu MultiPlus, DuraPlus and OptiFree Express were tested against P. aeruginosa which is in accordance with the ISO Stand-Alone Primary acceptance criteria. These findings are of great concern for contact lens users. Copyright © 2014 Elsevier Inc. All rights reserved.

Francisella tularensis type A Strains Cause the Rapid Encystment of Acanthamoeba castellanii and Survive in Amoebal Cysts for Three Weeks post Infection

Energy Technology Data Exchange (ETDEWEB)

El-Etr, S H; Margolis, J; Monack, D; Robison, R; Cohen, M; Moore, E; Rasley, A

2009-07-28

Francisella tularensis, the causative agent of the zoonotic disease tularemia, has recently gained increased attention due to the emergence of tularemia in geographical areas where the disease has been previously unknown, and the organism's potential as a bioterrorism agent. Although F. tularensis has an extremely broad host range, the bacterial reservoir in nature has not been conclusively identified. In this study, the ability of virulent F. tularensis strains to survive and replicate in the amoeba Acanthamoeba castellanii was explored. We observe that A. castellanii trophozoites rapidly encyst in response to F. tularensis infection and that this rapid encystment phenotype (REP) is caused by factor(s) secreted by amoebae and/or F. tularensis into the co-culture media. Further, our results indicate that in contrast to LVS, virulent strains of F. tularensis can survive in A. castellanii cysts for at least 3 weeks post infection and that induction of rapid amoeba encystment is essential for survival. In addition, our data indicate that pathogenic F. tularensis strains block lysosomal fusion in A. castellanii. Taken together, these data suggest that the interactions between F. tularensis strains and amoeba may play a role in the environmental persistence of F. tularensis.

Comparing the Dictyostelium and Entamoeba genomes reveals an ancient split in the Conosa lineage.

Directory of Open Access Journals (Sweden)

Jie Song

2005-12-01

Full Text Available The Amoebozoa are a sister clade to the fungi and the animals, but are poorly sampled for completely sequenced genomes. The social amoeba Dictyostelium discoideum and amitochondriate pathogen Entamoeba histolytica are the first Amoebozoa with genomes completely sequenced. Both organisms are classified under the Conosa subphylum. To identify Amoebozoa-specific genomic elements, we compared these two genomes to each other and to other eukaryotic genomes. An expanded phylogenetic tree built from the complete predicted proteomes of 23 eukaryotes places the two amoebae in the same lineage, although the divergence is estimated to be greater than that between animals and fungi, and probably happened shortly after the Amoebozoa split from the opisthokont lineage. Most of the 1,500 orthologous gene families shared between the two amoebae are also shared with plant, animal, and fungal genomes. We found that only 42 gene families are distinct to the amoeba lineage; among these are a large number of proteins that contain repeats of the FNIP domain, and a putative transcription factor essential for proper cell type differentiation in D. discoideum. These Amoebozoa-specific genes may be useful in the design of novel diagnostics and therapies for amoebal pathologies.

Acanthamoeba and Dictyostelium as Cellular Models for Legionella Infection

Science.gov (United States)

Swart, A. Leoni; Harrison, Christopher F.; Eichinger, Ludwig; Steinert, Michael; Hilbi, Hubert

2018-01-01

Environmental bacteria of the genus Legionella naturally parasitize free-living amoebae. Upon inhalation of bacteria-laden aerosols, the opportunistic pathogens grow intracellularly in alveolar macrophages and can cause a life-threatening pneumonia termed Legionnaires' disease. Intracellular replication in amoebae and macrophages takes place in a unique membrane-bound compartment, the Legionella-containing vacuole (LCV). LCV formation requires the bacterial Icm/Dot type IV secretion system, which translocates literally hundreds of “effector” proteins into host cells, where they modulate crucial cellular processes for the pathogen's benefit. The mechanism of LCV formation appears to be evolutionarily conserved, and therefore, amoebae are not only ecologically significant niches for Legionella spp., but also useful cellular models for eukaryotic phagocytes. In particular, Acanthamoeba castellanii and Dictyostelium discoideum emerged over the last years as versatile and powerful models. Using genetic, biochemical and cell biological approaches, molecular interactions between amoebae and Legionella pneumophila have recently been investigated in detail with a focus on the role of phosphoinositide lipids, small and large GTPases, autophagy components and the retromer complex, as well as on bacterial effectors targeting these host factors. PMID:29552544

Acanthamoeba and Dictyostelium as Cellular Models for Legionella Infection

Directory of Open Access Journals (Sweden)

A. Leoni Swart

2018-03-01

Full Text Available Environmental bacteria of the genus Legionella naturally parasitize free-living amoebae. Upon inhalation of bacteria-laden aerosols, the opportunistic pathogens grow intracellularly in alveolar macrophages and can cause a life-threatening pneumonia termed Legionnaires' disease. Intracellular replication in amoebae and macrophages takes place in a unique membrane-bound compartment, the Legionella-containing vacuole (LCV. LCV formation requires the bacterial Icm/Dot type IV secretion system, which translocates literally hundreds of “effector” proteins into host cells, where they modulate crucial cellular processes for the pathogen's benefit. The mechanism of LCV formation appears to be evolutionarily conserved, and therefore, amoebae are not only ecologically significant niches for Legionella spp., but also useful cellular models for eukaryotic phagocytes. In particular, Acanthamoeba castellanii and Dictyostelium discoideum emerged over the last years as versatile and powerful models. Using genetic, biochemical and cell biological approaches, molecular interactions between amoebae and Legionella pneumophila have recently been investigated in detail with a focus on the role of phosphoinositide lipids, small and large GTPases, autophagy components and the retromer complex, as well as on bacterial effectors targeting these host factors.

Adaptation of Francisella tularensis to the Mammalian Environment Is Governed by Cues Which Can Be Mimicked In Vitro▿ †

OpenAIRE

Hazlett, Karsten R. O.; Caldon, Seth D.; McArthur, Debbie G.; Cirillo, Kerry A.; Kirimanjeswara, Girish S.; Magguilli, Micheal L.; Malik, Meenakshi; Shah, Aaloki; Broderick, Scott; Golovliov, Igor; Metzger, Dennis W.; Rajan, Krishna; Sellati, Timothy J.; Loegering, Daniel J.

2008-01-01

The intracellular bacterium Francisella tularensis survives in mammals, arthropods, and freshwater amoeba. It was previously established that the conventional media used for in vitro propagation of this microbe do not yield bacteria that mimic those harvested from infected mammals; whether these in vitro-cultivated bacteria resemble arthropod- or amoeba-adapted Francisella is unknown. As a foundation for our goal of identifying F. tularensis outer membrane proteins which are expressed during ...

Journal of Biosciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

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 ...

To what extent do food preferences explain the trophic position of heterotrophic and mixotrophic microbial consumers in a Sphagnum peatland?

Science.gov (United States)

Jassey, Vincent E J; Meyer, Caroline; Dupuy, Christine; Bernard, Nadine; Mitchell, Edward A D; Toussaint, Marie-Laure; Metian, Marc; Chatelain, Auriel P; Gilbert, Daniel

2013-10-01

Although microorganisms are the primary drivers of biogeochemical cycles, the structure and functioning of microbial food webs are poorly studied. This is the case in Sphagnum peatlands, where microbial communities play a key role in the global carbon cycle. Here, we explored the structure of the microbial food web from a Sphagnum peatland by analyzing (1) the density and biomass of different microbial functional groups, (2) the natural stable isotope (δ(13)C and δ(15)N) signatures of key microbial consumers (testate amoebae), and (3) the digestive vacuole contents of Hyalosphenia papilio, the dominant testate amoeba species in our system. Our results showed that the feeding type of testate amoeba species (bacterivory, algivory, or both) translates into their trophic position as assessed by isotopic signatures. Our study further demonstrates, for H. papilio, the energetic benefits of mixotrophy when the density of its preferential prey is low. Overall, our results show that testate amoebae occupy different trophic levels within the microbial food web, depending on their feeding behavior, the density of their food resources, and their metabolism (i.e., mixotrophy vs. heterotrophy). Combined analyses of predation, community structure, and stable isotopes now allow the structure of microbial food webs to be more completely described, which should lead to improved models of microbial community function.

Life under the Microscope: Children's Ideas about Microbes

Science.gov (United States)

Allen, Michael; Bridle, Georgina; Briten, Elizabeth

2015-01-01

Microbes (by definition) are tiny living things that are only visible through a microscope and include bacteria, viruses, fungi, and protoctists (mainly single-celled life forms such as amoebae and algae). Although people are familiar with the effects of microbes, such as infectious disease and food spoilage, because of their lack of visibility,…

Possible environmental sources of Acanthamoeba spp in contact lens wearers.

OpenAIRE

Seal, D; Stapleton, F; Dart, J

1992-01-01

The water supply and dust samples from the home environment (bathrooms and kitchens) of 50 wearers of contact lenses (CLs) were cultured for the presence of free-living amoebae. CL cases, solutions, and water taps were cultured for bacteria, which amoebae require for growth. Acanthamoeba spp were isolated from water drawn from six bathroom cold water taps (tank supplied), five in the presence of limescale, and from one kitchen cold water tap (mains supplied). There was an association between ...

EFEKTIFITAS PENGELOLAAN DAERAH PERLINDUNGAN LAUT (STUDI KASUS DESA MATTIRO LABANGENG KABUPATEN PANGKEP

Directory of Open Access Journals (Sweden)

Dafiuddin Salim

2014-10-01

Full Text Available Makalah ini menilai efektivitas manajemen di Marine Sanctuary (Daerah Perlindungan Laut atau DPL dari Mattiro Labangeng Kabupaten Village-Pangkep. Hal ini menunjukkan bahwa dampak dan efektivitas proses manajemen dinilai menggunakan indikator, termasuk indikator biofisik, sosial ekonomi dan institusi. Hasil penelitian menunjukkan bahwa ada dampak positif dalam beberapa indikator ekologi (karang, ikan dan benthos, sosio-ekonomi dan institusi. The increasion total persen tutupan karang diikuti oleh kelompok meningkatkan ikan karang (indikator, target dan jurusan dan benthos organisme di DPL. Dari sudut ekonomi ini pandangan, nilai-nilai ekonomi terumbu karang sumber daya dari kegiatan perikanan sebelum dan sesudah DPL adalah Rp 42,635,910.51/ha/tahun dan Rp 52,084,390.18/ha/tahun, masing-masing. Efektivitas DPL ini ditunjukkan oleh grafik teknik Amoeba dan hasil yang disajikan nilai-nilai positif. Ringkasan adalah nilai indikator saat ini lebih besar dari nilai ambang batas kritis / CTV.Kata Kunci: CTV, efektivitas, indikator, perlindungan laut, teknik amubaTHE EFFECTIVITY OF MARINE SANCTUARY MANAGEMENT (CASE STUDY OF MATTIRO VILLAGE OF LABANGENG PANGKEP DISTRICTABSTRAKThis paper is assessing management effectiveness in Marine Sanctuary (Daerah Perlindungan Laut or DPL of Mattiro Labangeng Village-Pangkep Regency. It is showed that impacts and effectiveness of the management process was assessed using indicators, includes biophysical, socio-economic and institution indicators. The results showed that there are positive impacts in some indicators of ecology (corals, fish and benthos, socio-economic and institution. The increasion in percent total of coral cover was followed by the increasing groups of reef fish (indicators, targets, and majors and benthos organisms in DPL. From economic’s point of views, the economic values of coral reefs resource from fisheries activities before and after DPL were Rp 42,635,910.51/ha/year and Rp 52,084,390.18/ha

Analysing the spatial patterns of livestock anthrax in Kazakhstan in relation to environmental factors: a comparison of local (Gi* and morphology cluster statistics

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Ian T. Kracalik

2012-11-01

Full Text Available We compared a local clustering and a cluster morphology statistic using anthrax outbreaks in large (cattle and small (sheep and goats domestic ruminants across Kazakhstan. The Getis-Ord (Gi* statistic and a multidirectional optimal ecotope algorithm (AMOEBA were compared using 1st, 2nd and 3rd order Rook contiguity matrices. Multivariate statistical tests were used to evaluate the environmental signatures between clusters and non-clusters from the AMOEBA and Gi* tests. A logistic regression was used to define a risk surface for anthrax outbreaks and to compare agreement between clustering methodologies. Tests revealed differences in the spatial distribution of clusters as well as the total number of clusters in large ruminants for AMOEBA (n = 149 and for small ruminants (n = 9. In contrast, Gi* revealed fewer large ruminant clusters (n = 122 and more small ruminant clusters (n = 61. Significant environmental differences were found between groups using the Kruskall-Wallis and Mann- Whitney U tests. Logistic regression was used to model the presence/absence of anthrax outbreaks and define a risk surface for large ruminants to compare with cluster analyses. The model predicted 32.2% of the landscape as high risk. Approximately 75% of AMOEBA clusters corresponded to predicted high risk, compared with ~64% of Gi* clusters. In general, AMOEBA predicted more irregularly shaped clusters of outbreaks in both livestock groups, while Gi* tended to predict larger, circular clusters. Here we provide an evaluation of both tests and a discussion of the use of each to detect environmental conditions associated with anthrax outbreak clusters in domestic livestock. These findings illustrate important differences in spatial statistical methods for defining local clusters and highlight the importance of selecting appropriate levels of data aggregation.

Health aspects of wood particles in fugitive emission during professional exposition

International Nuclear Information System (INIS)

Vlckova, H.; Schwarz, M.; Lalik, V.

2008-01-01

Fugitive emission of wood dust can constitute serious menace to health of worker in wood industry. Present paper describes not only influence of unaccompanied wood which develops allergic reactions, respire diseases, dermatosis, cancer etc., but also additional effects of natural wood components as endotoxins, microbial spores, amoebas, fungus, animal and proteins, volatile components wood resins, respectively. (authors)

Exploring Anti-Bacterial Compounds against Intracellular Legionella

Science.gov (United States)

Harrison, Christopher F.; Kicka, Sébastien; Trofimov, Valentin; Berschl, Kathrin; Ouertatani-Sakouhi, Hajer; Ackermann, Nikolaus; Hedberg, Christian; Cosson, Pierre; Soldati, Thierry; Hilbi, Hubert

2013-01-01

Legionella pneumophila is a ubiquitous fresh-water bacterium which reproduces within its erstwhile predators, environmental amoeba, by subverting the normal pathway of phagocytosis and degradation. The molecular mechanisms which confer resistance to amoeba are apparently conserved and also allow replication within macrophages. Thus, L. pneumophila can act as an ‘accidental’ human pathogen and cause a severe pneumonia known as Legionnaires’ disease. The intracellular localisation of L. pneumophila protects it from some antibiotics, and this fact must be taken into account to develop new anti-bacterial compounds. In addition, the intracellular lifestyle of L. pneumophila may render the bacteria susceptible to compounds diminishing bacterial virulence and decreasing intracellular survival and replication of this pathogen. The development of a single infection cycle intracellular replication assay using GFP-producing L. pneumophila and Acanthamoeba castellanii amoeba is reported here. This fluorescence-based assay allows for continuous monitoring of intracellular replication rates, revealing the effect of bacterial gene deletions or drug treatment. To examine how perturbations of the host cell affect L. pneumophila replication, several known host-targeting compounds were tested, including modulators of cytoskeletal dynamics, vesicle scission and Ras GTPase localisation. Our results reveal a hitherto unrealized potential antibiotic property of the β-lactone-based Ras depalmitoylation inhibitor palmostatin M, but not the closely related inhibitor palmostatin B. Further characterisation indicated that this compound caused specific growth inhibition of Legionella and Mycobacterium species, suggesting that it may act on a common bacterial target. PMID:24058631

Exploring anti-bacterial compounds against intracellular Legionella.

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Christopher F Harrison

Full Text Available Legionella pneumophila is a ubiquitous fresh-water bacterium which reproduces within its erstwhile predators, environmental amoeba, by subverting the normal pathway of phagocytosis and degradation. The molecular mechanisms which confer resistance to amoeba are apparently conserved and also allow replication within macrophages. Thus, L. pneumophila can act as an 'accidental' human pathogen and cause a severe pneumonia known as Legionnaires' disease. The intracellular localisation of L. pneumophila protects it from some antibiotics, and this fact must be taken into account to develop new anti-bacterial compounds. In addition, the intracellular lifestyle of L. pneumophila may render the bacteria susceptible to compounds diminishing bacterial virulence and decreasing intracellular survival and replication of this pathogen. The development of a single infection cycle intracellular replication assay using GFP-producing L. pneumophila and Acanthamoebacastellanii amoeba is reported here. This fluorescence-based assay allows for continuous monitoring of intracellular replication rates, revealing the effect of bacterial gene deletions or drug treatment. To examine how perturbations of the host cell affect L. pneumophila replication, several known host-targeting compounds were tested, including modulators of cytoskeletal dynamics, vesicle scission and Ras GTPase localisation. Our results reveal a hitherto unrealized potential antibiotic property of the β-lactone-based Ras depalmitoylation inhibitor palmostatin M, but not the closely related inhibitor palmostatin B. Further characterisation indicated that this compound caused specific growth inhibition of Legionella and Mycobacterium species, suggesting that it may act on a common bacterial target.

The amoebal MAP kinase response to Legionella pneumophila is regulated by DupA.

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Li, Zhiru; Dugan, Aisling S; Bloomfield, Gareth; Skelton, Jason; Ivens, Alasdair; Losick, Vicki; Isberg, Ralph R

2009-09-17

The amoeba Dictyostelium discoideum can support replication of Legionella pneumophila. Here we identify the dupA gene, encoding a putative tyrosine kinase/dual-specificity phosphatase, in a screen for D. discoideum mutants altered in allowing L. pneumophila intracellular replication. Inactivation of dupA resulted in depressed L. pneumophila growth and sustained hyperphosphorylation of the amoebal MAP kinase ERK1, consistent with loss of a phosphatase activity. Bacterial challenge of wild-type amoebae induced dupA expression and resulted in transiently increased ERK1 phosphorylation, suggesting that dupA and ERK1 are part of a response to bacteria. Indeed, over 500 of the genes misregulated in the dupA(-) mutant were regulated in response to L. pneumophila infection, including some thought to have immune-like functions. MAP kinase phosphatases are known to be highly upregulated in macrophages challenged with L. pneumophila. Thus, DupA may regulate a MAP kinase response to bacteria that is conserved from amoebae to mammals.

Genome Dynamics in Legionella: The Basis of Versatility and Adaptation to Intracellular Replication

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Gomez-Valero, Laura; Buchrieser, Carmen

2013-01-01

Legionella pneumophila is a bacterial pathogen present in aquatic environments that can cause a severe pneumonia called Legionnaires’ disease. Soon after its recognition, it was shown that Legionella replicates inside amoeba, suggesting that bacteria replicating in environmental protozoa are able to exploit conserved signaling pathways in human phagocytic cells. Comparative, evolutionary, and functional genomics suggests that the Legionella–amoeba interaction has shaped this pathogen more than previously thought. A complex evolutionary scenario involving mobile genetic elements, type IV secretion systems, and horizontal gene transfer among Legionella, amoeba, and other organisms seems to take place. This long-lasting coevolution led to the development of very sophisticated virulence strategies and a high level of temporal and spatial fine-tuning of bacteria host–cell interactions. We will discuss current knowledge of the evolution of virulence of Legionella from a genomics perspective and propose our vision of the emergence of this human pathogen from the environment. PMID:23732852

Expression of matrix metalloproteinases in Naegleria fowleri and their role in invasion of the central nervous system.

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Lam, Charlton; Jamerson, Melissa; Cabral, Guy; Carlesso, Ana Maris; Marciano-Cabral, Francine

2017-10-01

Naegleria fowleri is a free-living amoeba found in freshwater lakes and ponds and is the causative agent of primary amoebic meningoencephalitis (PAM), a rapidly fatal disease of the central nervous system (CNS). PAM occurs when amoebae attach to the nasal epithelium and invade the CNS, a process that involves binding to, and degradation of, extracellular matrix (ECM) components. This degradation is mediated by matrix metalloproteinases (MMPs), enzymes that have been described in other pathogenic protozoa, and that have been linked to their increased motility and invasive capability. These enzymes also are upregulated in tumorigenic cells and have been implicated in metastasis of certain tumours. In the present study, in vitro experiments linked MMPs functionally to the degradation of the ECM. Gelatin zymography demonstrated enzyme activity in N. fowleri whole cell lysates, conditioned media and media collected from invasion assays. Western immunoblotting indicated the presence of the metalloproteinases MMP-2 (gelatinase A), MMP-9 (gelatinase B) and MMP-14 [membrane type-1 matrix metalloproteinase (MT1-MMP)]. Highly virulent mouse-passaged amoebae expressed higher levels of MMPs than weakly virulent axenically grown amoebae. The functional relevance of MMPs in media was indicated through the use of the MMP inhibitor, 1,10-phenanthroline. The collective in vitro results suggest that MMPs play a critical role in vivo in invasion of the CNS and that these enzymes may be amenable targets for limiting PAM.

Survival of the fattest

DEFF Research Database (Denmark)

Morgani, Sophie M; Brickman, Joshua M

2013-01-01

Experiments on the social amoeba Dictyostelium discoideum show that the origins of lineage bias in this system lie in the nutritional history of individual cells. Clues to the molecular basis for this process suggest similar forces may be at work in early mammalian development.......Experiments on the social amoeba Dictyostelium discoideum show that the origins of lineage bias in this system lie in the nutritional history of individual cells. Clues to the molecular basis for this process suggest similar forces may be at work in early mammalian development....

An Amoebal Grazer of Cyanobacteria Requires Cobalamin Produced by Heterotrophic Bacteria.

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Ma, Amy T; Beld, Joris; Brahamsha, Bianca

2017-05-15

Amoebae are unicellular eukaryotes that consume microbial prey through phagocytosis, playing a role in shaping microbial food webs. Many amoebal species can be cultivated axenically in rich media or monoxenically with a single bacterial prey species. Here, we characterize heterolobosean amoeba LPG3, a recent natural isolate, which is unable to grow on unicellular cyanobacteria, its primary food source, in the absence of a heterotrophic bacterium, a Pseudomonas species coisolate. To investigate the molecular basis of this requirement for heterotrophic bacteria, we performed a screen using the defined nonredundant transposon library of Vibrio cholerae , which implicated genes in corrinoid uptake and biosynthesis. Furthermore, cobalamin synthase deletion mutations in V. cholerae and the Pseudomonas species coisolate do not support the growth of amoeba LPG3 on cyanobacteria. While cyanobacteria are robust producers of a corrinoid variant called pseudocobalamin, this variant does not support the growth of amoeba LPG3. Instead, we show that it requires cobalamin that is produced by the Pseudomonas species coisolate. The diversity of eukaryotes utilizing corrinoids is poorly understood, and this amoebal corrinoid auxotroph serves as a model for examining predator-prey interactions and micronutrient transfer in bacterivores underpinning microbial food webs. IMPORTANCE Cyanobacteria are important primary producers in aquatic environments, where they are grazed upon by a variety of phagotrophic protists and, hence, have an impact on nutrient flux at the base of microbial food webs. Here, we characterize amoebal isolate LPG3, which consumes cyanobacteria as its primary food source but also requires heterotrophic bacteria as a source of corrinoid vitamins. Amoeba LPG3 specifically requires the corrinoid variant produced by heterotrophic bacteria and cannot grow on cyanobacteria alone, as they produce a different corrinoid variant. This same corrinoid specificity is also

Cooling systems

International Nuclear Information System (INIS)

Coutant, C.C.

1978-01-01

Progress on the thermal effects project is reported with regard to physiology and distribution of Corbicula; power plant effects studies on burrowing mayfly populations; comparative thermal responses of largemouth bass from northern and southern populations; temperature selection by striped bass in Cherokee Reservoir; fish population studies; and predictive thermoregulation by fishes. Progress is also reported on the following; cause and ecological ramifications of threadfin shad impingement; entrainment project; aquaculture project; pathogenic amoeba project; and cooling tower drift project

Evidence that the intra-amoebal Legionella drancourtii acquired a sterol reductase gene from eukaryotes

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Fournier Pierre-Edouard

2009-03-01

Full Text Available Abstract Background Free-living amoebae serve as a natural reservoir for some bacteria that have evolved into «amoeba-resistant» bacteria. Among these, some are strictly intra-amoebal, such as Candidatus "Protochlamydia amoebophila" (Candidatus "P. amoebophila", whose genomic sequence is available. We sequenced the genome of Legionella drancourtii (L. drancourtii, another recently described intra-amoebal bacterium. By comparing these two genomes with those of their closely related species, we were able to study the genetic characteristics specific to their amoebal lifestyle. Findings We identified a sterol delta-7 reductase-encoding gene common to these two bacteria and absent in their relatives. This gene encodes an enzyme which catalyses the last step of cholesterol biosynthesis in eukaryotes, and is probably functional within L. drancourtii since it is transcribed. The phylogenetic analysis of this protein suggests that it was acquired horizontally by a few bacteria from viridiplantae. This gene was also found in the Acanthamoeba polyphaga Mimivirus genome, a virus that grows in amoebae and possesses the largest viral genome known to date. Conclusion L. drancourtii acquired a sterol delta-7 reductase-encoding gene of viridiplantae origin. The most parsimonious hypothesis is that this gene was initially acquired by a Chlamydiales ancestor parasite of plants. Subsequently, its descendents transmitted this gene in amoebae to other intra-amoebal microorganisms, including L. drancourtii and Coxiella burnetii. The role of the sterol delta-7 reductase in prokaryotes is as yet unknown but we speculate that it is involved in host cholesterol parasitism.

[Effects of adding straw carbon source to root knot nematode diseased soil on soil microbial biomass and protozoa abundance].

Science.gov (United States)

Zhang, Si-Hui; Lian, Jian-Hong; Cao, Zhi-Ping; Zhao, Li

2013-06-01

A field experiment with successive planting of tomato was conducted to study the effects of adding different amounts of winter wheat straw (2.08 g x kg(-1), 1N; 4.16 g x kg(-1), 2N; and 8.32 g x kg(-1), 4N) to the soil seriously suffered from root knot nematode disease on the soil microbial biomass and protozoa abundance. Adding straw carbon source had significant effects on the contents of soil microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) and the abundance of soil protozoa, which all decreased in the order of 4N > 2N > 1N > CK. The community structure of soil protozoa also changed significantly under straw addition. In the treatments with straw addition, the average proportion of fagellate, amoeba, and ciliates accounted for 36.0%, 59.5%, and 4.5% of the total protozoa, respectively. Under the same adding amounts of wheat straw, there was an increase in the soil MBC and MBN contents, MBC/MBN ratio, and protozoa abundance with increasing cultivation period.

Efficacy of hand held, inexpensive UV light sources on Acanthamoeba, causative organism in amoebic keratitis

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Ivan Cometa

2010-01-01

Full Text Available Ivan Cometa1, Andrew Rogerson1, Scott Schatz21Department of Biology, California State University Fresno, Fresno, CA, USA; 2Arizona College of Optometry, Midwestern University, Glendale, AZ, USAAbstract: Multipurpose lens cleaning solutions (MPS fail to consistently kill or inactivate Acanthamoeba cysts and UV irradiation, while effective at high doses, can damage contact lenses. The present study considered synergy of action between MPS and hand-held inexpensive (ie, relatively weak UV irradiation units. Regardless of disinfection method recently formed cysts (<10 days were far more susceptible to treatment than mature cysts (>14 days. This has important implications for future protocols on testing methods for killing amoebae. The study also showed that cysts of different strains (two tested, FLA2 and P120 are variable in their response to MPS, presumably reflecting differences in cyst wall structure and thus permeability to the disinfectant. On the other hand, the effect of UV irradiation was not wall structure dependent. A 6-hour treatment with MPS alone killed trophic amoebae but failed to kill any mature cysts. Cysts of strain FLA2 were killed after 24 hours with MPS but cysts of strain P120 survived. UV irradiation with the larger 4 W unit killed all cysts after 7 minutes and was more effective than the smaller battery-powered unit (after 10 minutes about 50% of cysts were killed. When the larger unit was used with the MPS disinfection, all trophozoites were killed using UV for 3 minutes and MPS for 1 hour. The resistant P120 cysts remained a challenge but a 2- to 4-minute UV treatment followed by MPS for 3 or 6 hours reduced mature cyst survival by about 50%. The small unit in combination with MPS was less effective but did reduce the time required to kill trophic amoebae in MPS (6 hours MPS alone versus 3 hours MPS with a 1-minute UV treatment. In short, inexpensive UV units do enhance MPS disinfection and future lens cleaning systems

Variation in the SSUrDNA of the Genus Protostelium Leads to a New Phylogenetic Understanding of the Genus and of the Species Concept for Protostelium mycophaga (Protosteliida, Amoebozoa).

Science.gov (United States)

Shadwick, John D L; Silberman, Jeffery D; Spiegel, Frederick W

2018-05-01

Members of the genus Protostelium (including P. mycophaga, P. nocturnum, and P. okumukumu) are protosteloid amoebae commonly found in terrestrial habitats on dead plant matter. They, along with the closely allied nominal genus Planoprotostelium, containing the single species Pl. aurantium, all have an amoeboid trophic stage with acutely pointed subpseudopodia and orange lipid droplets in the granuloplasm. These amoebae form stalked fruiting bodies topped with a single, usually deciduous spore. The species are identified based on their fruiting body morphologies except for Pl. aurantium which looks similar to P. mycophaga in fruiting morphology, but has amoebae that can make flagella in liquid medium. We built phylogenetic trees using nuclear small subunit ribosomal DNA sequences of 35 isolates from the genera Protostelium and Planoprotostelium and found that (1) the nonflagellated P. nocturnum and P. okumukumu branch basally in the genus Protostelium, (2) the flagellate, Pl. aurantium falls within the genus Protostelium in a monophyletic clade with the nominal variety, P. mycophaga var. crassipes, (3) the cultures initially identified as Protostelium mycophaga can be divided into at least three morphologically recognizable taxa, P. aurantium n. comb., P. apiculatum n. sp., and P. m. rodmani n. subsp., as well as a paraphyletic assemblage that includes the remainder of the P. mycophaga morphotype. These findings have implications for understanding the ecology, evolution, and diversity of these amoeboid organisms and for using these amoebae as models for other amoeboid groups. © 2017 The Author(s) Journal of Eukaryotic Microbiology © 2017 International Society of Protistologists.

Viable Species of Flamella (Amoebozoa: Variosea) Isolated from Ancient Arctic Permafrost Sediments.

Science.gov (United States)

Shmakova, Lyubov; Bondarenko, Natalya; Smirnov, Alexey

2016-02-01

Six viable strains of amoebae belonging to the genus Flamella (Amoebozoa, Variosea) were isolated from permafrost sediments sampled in the Russian Arctic region. Two of them are from late Pleistocene permafrost in North-East Siberia, and four--from Holocene and late Pleistocene in North-West Siberia. Light- and electron-microscopic study and molecular phylogeny show that these isolates represent two new species belonging to the genus Flamella. Both species are cyst-forming. This is a remarkable case of high resistance of protozoan cysts, allowing them to survive and recover an amoebae population after a very long, geologically significant period of rest; a "snapshot" of evolution in time. This study directly shows for the first time that amoeba cysts can be conserved not only for years and decades but for many thousand years and then recover, contributing to the formation of an active microbial community. We propose to name the new species as Flamella pleistocenica n.sp. and Flamella beringiania n.sp. Phylogenetic analysis shows that the genus Flamella is a robust and potentially species-rich group of Variosea. Copyright © 2015 Elsevier GmbH. All rights reserved.

Unusual Vermamoeba Vermiformis Strain Isolated from Snow in Mount Teide, Tenerife, Canary Islands, Spain

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Maria Reyes-Batlle

2015-10-01

Full Text Available Background: Free-living amoebae (FLA are protozoa that are widely distributed in the environment mainly in water and soil related habitats. Thermophilic amoebae are among the most common FLA in water bodies, being Vermamoeba vermiformis one of the most common species reported worldwide from these sources. Interestingly, V. vermiformis has often been reported to survive at high temperatures and osmotic pressure worldwide.Materials and Methods: In this study, snow samples were collected from Mount Teide, Tenerife, Canary Islands during the winter season of 2014. The samples were culture on non nutrient agar plates and checked daily for the presence of FLA. After a week, V. vermiformis amoebae were observed in the plates incubated at room temperature and 37ºC.Results: Molecular characterization was carried out by amplifying the 18S rDNA gene and DNA sequencing, confirmed that the isolated strain belonged to Vermamoeba vermiformis species.Conclusion: To the best of our knowledge, this is the first report of Vermamoeba vermiformis isolation from such an inusual habitat (low temperatures and high altitude and the first report of these species in the Canary islands.

Peroxynitrite and Peroxiredoxin in the Pathogenesis of Experimental Amebic Liver Abscess

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Judith Pacheco-Yepez

2014-01-01

Full Text Available The molecular mechanisms by which Entamoeba histolytica causes amebic liver abscess (ALA are still not fully understood. Amebic mechanisms of adherence and cytotoxic activity are pivotal for amebic survival but apparently do not directly cause liver abscess. Abundant evidence indicates that chronic inflammation (resulting from an inadequate immune response is probably the main cause of ALA. Reports referring to inflammatory mechanisms of liver damage mention a repertoire of toxic molecules by the immune response (especially nitric oxide and reactive oxygen intermediates and cytotoxic substances released by neutrophils and macrophages after being lysed by amoebas (e.g., defensins, complement, and proteases. Nevertheless, recent evidence downplays these mechanisms in abscess formation and emphasizes the importance of peroxynitrite (ONOO−. It seems that the defense mechanism of amoebas against ONOO−, namely, the amebic thioredoxin system (including peroxiredoxin, is superior to that of mammals. The aim of the present text is to define the importance of ONOO− as the main agent of liver abscess formation during amebic invasion, and to explain the superior capacity of amoebas to defend themselves against this toxic agent through the peroxiredoxin and thioredoxin system.

Radiation-induced inheritable changes in the death-rate of cells

International Nuclear Information System (INIS)

Bychkovskaya, I.B.; Ochinskaya, G.K.

1980-01-01

By the use of an original technique (regeneration of individual lines from sister cells) it was demonstrated on various individually cultivated protozoa (Amoeba proteus, Paramecium caudatum and Climacostomum virens) that even weak direct and indirect radiation effects can induce an appreciable increase in the death-rate of descendants. After a certain dose threshold, the effect did not depend on the power of the attack and remained at the same level for as long as 3 years. The observed changes were qualitatively different from known types of inheritable changes leading to cell death

Acanthamoeba polyphaga resuscitates viable non-culturable Legionella pneumophila after disinfection.

Science.gov (United States)

García, María Teresa; Jones, Snake; Pelaz, Carmen; Millar, Richard D; Abu Kwaik, Yousef

2007-05-01

Amoebae are the natural hosts for Legionella pneumophila and play essential roles in bacterial ecology and infectivity to humans. When L. pneumophila colonizes an aquatic installation, it can persist for years despite repeated treatments with disinfectants. We hypothesized that freshwater amoebae play an important role in bacterial resistance to disinfectants, and in subsequent resuscitation of viable non-culturable (VNC) L. pneumophila that results in re-emergence of the disease-causing strain in the disinfected water source. Our work showed that in the absence of Acanthamoeba polyphaga, seven L. pneumophila strains became non-culturable after treatment by 256 p.p.m. of sodium hypochlorite (NaOCl). In contrast, intracellular L. pneumophila within A. polyphaga was resistant to 1024 p.p.m. of NaOCl. In addition, L. pneumophila-infected A. polyphaga exhibited increased resistance to NaOCl. When chlorine-sterilized water samples were co-cultured with A. polyphaga, the non-culturable L. pneumophila were resuscitated and proliferated robustly within A. polyphaga. Upon treatment by NaOCl, uninfected amoebae differentiated into cysts within 48 h. In contrast, L. pneumophila-infected A. polyphaga failed to differentiate into cysts, and L. pneumophila was never detected in cysts of A. polyphaga. We conclude that amoebic trophozoites protect intracellular L. pneumophila from eradication by NaOCl, and play an essential role in resuscitation of VNC L. pneumophila in NaOCl-disinfected water sources. Intracellular L. pneumophila within trophozoites of A. polyphaga block encystation of the amoebae, and the resistance of both organisms to NaOCl is enhanced. To ensure long-term eradication and complete loss of the VNC state of L. pneumophila, we recommend that Legionella-protozoa co-culture should be an important tool to ensure complete loss of the VNC state of L. pneumophila.

The design of a real-time distributed system

International Nuclear Information System (INIS)

Hertzberger, L.O.; Tuynman, F.; Mullender, S.J.; Poletiek, G.; Vermeulen, J.C.; Renesse, R. van; Tanenbaum, A.S.

1986-01-01

In modern physics experiments an increasing number and variety of programmable processors is used. As a consequence, a software environment is needed that provides an integrated approach to development, testing and use of real-time distributed software. This contribution is based on work being done in the AMOEBA Distributed Operating System Project and the FADOS Real-Time Distributed Operating System Project. A short description of both systems is presented as an example of how basic real-time operating system services can be organized. AMOEBA is the result of fundamental research in the field of distributed operating systems, while FADOS has been designed for applications as encountered in experimental high-energy physics. (Auth.)

Isolation of amoebic-bacterial consortia capable of degrading trichloroethylene

International Nuclear Information System (INIS)

Tyndall, R.L.; Ironside, K.; Little, C.D.; Katz, S.; Kennedy, J.

1990-01-01

Groundwater from a waste disposal site contaminated with chlorinated alkenes was examined for the presence of amoebic-bacterial consortia capable of degrading the suspected carcinogen, trichloroethylene (TCE). Consortia were readily isolated from all of four test wells. They contained free-living amoebae, and heterotrophic and methylotrophic bacteria. Electron microscopic examination showed bacteria localized throughout the amoebic cytoplasm and an abundance of hyphomicrobium, but not Type I methanotrophs. The presence of Type II methanotrophs was indirectly indicated by lipid analysis of one consortium. The consortia have been passaged for over two years on mineral salts media in a methane atmosphere, which would not be expected to maintain the heterotrophs or amoebae separately. The methanotrophic bacteria apparently provided a stable nutrient source, allowing the persistence of the various genera. By use of 14 C-radiotracer techniques, the degradation of TCE by the consortia was observed with 14 C eventuating predominantly in CO 2 and water-soluble products. In a more detailed examination of one consortia, the amoebae and heterotrohic components did not degrade TCE, while a mixed culture of heterotrophs and methanotrophs did degrade TCE, suggesting the latter component was the primary cause for the consortium's ability to degrade TCE. Amoebic-bacterial consortia may play a role in stabilizing and preserving methylotrophic bacteria in hostile environments

Noisy Oscillations in the Actin Cytoskeleton of Chemotactic Amoeba

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Negrete, Jose; Pumir, Alain; Hsu, Hsin-Fang; Westendorf, Christian; Tarantola, Marco; Beta, Carsten; Bodenschatz, Eberhard

2016-09-01

Biological systems with their complex biochemical networks are known to be intrinsically noisy. Here we investigate the dynamics of actin polymerization of amoeboid cells, which are close to the onset of oscillations. We show that the large phenotypic variability in the polymerization dynamics can be accurately captured by a generic nonlinear oscillator model in the presence of noise. We determine the relative role of the noise with a single dimensionless, experimentally accessible parameter, thus providing a quantitative description of the variability in a population of cells. Our approach, which rests on a generic description of a system close to a Hopf bifurcation and includes the effect of noise, can characterize the dynamics of a large class of noisy systems close to an oscillatory instability.

Phospholipids of Entamoeba invadens

NARCIS (Netherlands)

Vliet, H.H.D.M. van; Kamp, J.A.F. op den; Deenen, L.L.M. van

1975-01-01

The major phosphoglycerides present in Entamoeba invadens are phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol. Furthermore, three different sphingolipids could be isolated from the amoeba. In addition to sphingomyelin and a phosphonolipid, ceramide

Zigzag turning preference of freely crawling cells.

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Taeseok Daniel Yang

Full Text Available The coordinated motion of a cell is fundamental to many important biological processes such as development, wound healing, and phagocytosis. For eukaryotic cells, such as amoebae or animal cells, the cell motility is based on crawling and involves a complex set of internal biochemical events. A recent study reported very interesting crawling behavior of single cell amoeba: in the absence of an external cue, free amoebae move randomly with a noisy, yet, discernible sequence of 'run-and-turns' analogous to the 'run-and-tumbles' of swimming bacteria. Interestingly, amoeboid trajectories favor zigzag turns. In other words, the cells bias their crawling by making a turn in the opposite direction to a previous turn. This property enhances the long range directional persistence of the moving trajectories. This study proposes that such a zigzag crawling behavior can be a general property of any crawling cells by demonstrating that 1 microglia, which are the immune cells of the brain, and 2 a simple rule-based model cell, which incorporates the actual biochemistry and mechanics behind cell crawling, both exhibit similar type of crawling behavior. Almost all legged animals walk by alternating their feet. Similarly, all crawling cells appear to move forward by alternating the direction of their movement, even though the regularity and degree of zigzag preference vary from one type to the other.

Quantifying the degree of persistence in random amoeboid motion based on the Hurst exponent of fractional Brownian motion.

Science.gov (United States)

Makarava, Natallia; Menz, Stephan; Theves, Matthias; Huisinga, Wilhelm; Beta, Carsten; Holschneider, Matthias

2014-10-01

Amoebae explore their environment in a random way, unless external cues like, e.g., nutrients, bias their motion. Even in the absence of cues, however, experimental cell tracks show some degree of persistence. In this paper, we analyzed individual cell tracks in the framework of a linear mixed effects model, where each track is modeled by a fractional Brownian motion, i.e., a Gaussian process exhibiting a long-term correlation structure superposed on a linear trend. The degree of persistence was quantified by the Hurst exponent of fractional Brownian motion. Our analysis of experimental cell tracks of the amoeba Dictyostelium discoideum showed a persistent movement for the majority of tracks. Employing a sliding window approach, we estimated the variations of the Hurst exponent over time, which allowed us to identify points in time, where the correlation structure was distorted ("outliers"). Coarse graining of track data via down-sampling allowed us to identify the dependence of persistence on the spatial scale. While one would expect the (mode of the) Hurst exponent to be constant on different temporal scales due to the self-similarity property of fractional Brownian motion, we observed a trend towards stronger persistence for the down-sampled cell tracks indicating stronger persistence on larger time scales.

Developmental Cycle and Genome Analysis of Protochlamydia massiliensis sp. nov. a New Species in the Parachlamydiacae Family

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Samia Benamar

2017-08-01

Full Text Available Amoeba-associated microorganisms (AAMs are frequently isolated from water networks. In this paper, we report the isolation and characterization of Protochlamydia massiliensis, an obligate intracellular Gram-negative bacterium belonging to the Parachlamydiaceae family in the Chlamydiales order, from a cooling water tower. This bacterium was isolated on Vermamoeba vermiformis. It has a multiple range of hosts among amoeba and is characterized by a typical replication cycle of Chlamydiae with a particularity, recently shown in some chlamydia, which is the absence of inclusion vacuoles in the V. vermiformis host, adding by this a new member of Chlamydiae undergoing developmental cycle changes in the newly adapted host V. vermiformis. Draft genome sequencing revealed a chromosome of 2.86 Mb consisting of four contigs and a plasmid of 92 Kb.

Effects of Nickel, Chlorpyrifos and Their Mixture on the Dictyostelium discoideum Proteome

Science.gov (United States)

Boatti, Lara; Robotti, Elisa; Marengo, Emilio; Viarengo, Aldo; Marsano, Francesco

2012-01-01

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. PMID:23443088

Ecology and life history of an amoebomastigote, Paratetramitus jugosus, from a microbial mat: new evidence for multiple fission

Science.gov (United States)

Enzien, M.; McKhann, H. I.; Margulis, L.

1989-01-01

Five microbial habitats (gypsum crust, gypsum photosynthetic community, Microcoleus mat, Thiocapsa scum, and black mud) were sampled for the presence of the euryhaline, rapidly growing amoebomastigote, Paratetramitus jugosus. Field investigations of microbial mats from Baja California Norte, Mexico, and Salina Bido near Matanzas, Cuba, reveal that P. jugosus is most frequently found in the Thiocapsa layer of microbial mats. Various stages of the life history were studied using phase-contrast, differential-interference, and transmission electron microscopy. Mastigote stages were induced and studied by electron microscopy; mastigotes that actively feed on bacteria bear two or more undulipodia. A three-dimensional drawing of the kinetid ("basal apparatus") based on electron micrographs is presented. Although promitoses were occasionally observed, it is unlikely that they can account for the rapid growth of P. jugosus populations on culture media. Dense, refractile, spherical, and irregular-shaped bodies were seen at all times in all cultures along with small mononucleate (approximately 2-7 micrometers diameter) amoebae. Cytochemical studies employing two different fluorescent stains for DNA (DAPI, mithramycin) verified the presence of DNA in these small bodies. Chromatin-like material seen in electron micrographs within the cytoplasm and blebbing off nuclei were interpreted to the chromatin bodies. Our interpretation, consistent with the data but not proven, is that propagation by multiple fission of released chromatin bodies that become small amoebae may occur in Paratetramitus jugosus. These observations are consistent with descriptions of amoeba propagules in the early literature (Hogue, 1914).

Atomic force microscopic imaging of Acanthamoeba castellanii and Balamuthia mandrillaris trophozoites and cysts.

Science.gov (United States)

Aqeel, Yousuf; Siddiqui, Ruqaiyyah; Ateeq, Muhammad; Raza Shah, Muhammad; Kulsoom, Huma; Khan, Naveed Ahmed

2015-01-01

Light microscopy and electron microscopy have been successfully used in the study of microbes, as well as free-living protists. Unlike light microscopy, which enables us to observe living organisms or the electron microscope which provides a two-dimensional image, atomic force microscopy provides a three-dimensional surface profile. Here, we observed two free-living amoebae, Acanthamoeba castellanii and Balamuthia mandrillaris under the phase contrast inverted microscope, transmission electron microscope and atomic force microscope. Although light microscopy was of lower magnification, it revealed functional biology of live amoebae such as motility and osmoregulation using contractile vacuoles of the trophozoite stage, but it is of limited value in defining the cyst stage. In contrast, transmission electron microscopy showed significantly greater magnification and resolution to reveal the ultra-structural features of trophozoites and cysts including intracellular organelles and cyst wall characteristics but it only produced a snapshot in time of a dead amoeba cell. Atomic force microscopy produced three-dimensional images providing detailed topographic description of shape and surface, phase imaging measuring boundary stiffness, and amplitude measurements including width, height and length of A. castellanii and B. mandrillaris trophozoites and cysts. These results demonstrate the importance of the application of various microscopic methods in the biological and structural characterization of the whole cell, ultra-structural features, as well as surface components and cytoskeleton of protist pathogens. © 2014 The Author(s) Journal of Eukaryotic Microbiology © 2014 International Society of Protistologists.

Characterization of the gene encoding serine acetyltransferase, a regulated enzyme of cysteine biosynthesis from the protist parasites Entamoeba histolytica and Entamoeba dispar. Regulation and possible function of the cysteine biosynthetic pathway in Entamoeba.

Science.gov (United States)

Nozaki, T; Asai, T; Sanchez, L B; Kobayashi, S; Nakazawa, M; Takeuchi, T

1999-11-05

The enteric protist parasites Entamoeba histolytica and Entamoeba dispar possess a cysteine biosynthetic pathway, unlike their mammalian host, and are capable of de novo production of L-cysteine. We cloned and characterized cDNAs that encode the regulated enzyme serine acetyltransferase (SAT) in this pathway from these amoebae by genetic complementation of a cysteine-auxotrophic Escherichia coli strain with the amoebic cDNA libraries. The deduced amino acid sequences of the amoebic SATs exhibited, within the most conserved region, 36-52% identities with the bacterial and plant SATs. The amoebic SATs contain a unique insertion of eight amino acids, also found in the corresponding region of a plasmid-encoded SAT from Synechococcus sp., which showed the highest overall identities to the amoebic SATs. Phylogenetic reconstruction also revealed a close kinship of the amoebic SATs with cyanobacterial SATs. Biochemical characterization of the recombinant E. histolytica SAT revealed several enzymatic features that distinguished the amoebic enzyme from the bacterial and plant enzymes: 1) inhibition by L-cysteine in a competitive manner with L-serine; 2) inhibition by L-cystine; and 3) no association with cysteine synthase. Genetically engineered amoeba strains that overproduced cysteine synthase and SAT were created. The cysteine synthase-overproducing amoebae had a higher level of cysteine synthase activity and total thiol content and revealed increased resistance to hydrogen peroxide. These results indicate that the cysteine biosynthetic pathway plays an important role in antioxidative defense of these enteric parasites.

Questions on unusual Mimivirus-like structures observed in human cells [version 1; referees: 2 approved

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Elena Angela Lusi

2017-03-01

Full Text Available Background: Mimiviruses or giant viruses that infect amoebas have the ability to retain the Gram stain, which is usually used to colour bacteria. There is some evidence suggesting that Mimiviruses can also infect human cells. Guided by these premises, we performed a routine Gram stain on a variety of human specimens to see if we could detect the same Gram positive blue granules that identify Mimiviruses in the amoebas. Methods: We analysed 24 different human specimens (liver, brain, kidney, lymph node and ovary using Gram stain histochemistry, electron microscopy immunogold, high resolution mass spectrometry and protein identification. Results: We detected in the human cells Gram positive granules that were distinct from bacteria. The fine blue granules displayed the same pattern of the Gram positive granules that diagnose Mimiviruses in the cytoplasm of the amoebas. Electron microscopy confirmed the presence of human Mimiviruses-like structures and mass spectrometry identified histone H4 peptides, which had the same footprints as giant viruses. However, some differences were noted: the Mimivirus-like structures identified in the human cells were ubiquitous and manifested a distinct mammalian retroviral antigenicity. Conclusions: Our main hypotheses are that the structures could be either giant viruses having a retroviral antigenicity or ancestral cellular components having a viral origin. However, other possible alternatives have been proposed to explain the nature and function of the newly identified structures.

The use of Sphagnum cellulose oxygen isotope ratios in ombrotrophic peatlands as a proxy for paleoclimate.

Science.gov (United States)

Taylor, M.; Pendall, E.; Jackson, S.; Booth, R. K.; Nichols, J. E.; Huang, Y.

2006-12-01

Developing proxies for discerning paleoclimate that are independent of the pollen record can provide insight into various aspects of climate variability and improve confidence in the interpretation of climate-vegetation interactions. To date, proxies including plant macrofossils, humification indices, testate amoebae, and ratios of n-alkane abundances have been used to infer past climate variability from temperate ombrotrophic peatlands in upper Midwestern North America. These proxies are used to infer past changes in surface-moisture conditions, which in ombrotrophic peatlands is primarily a function of precipitation and temperature. This study investigates the potential uses of stable oxygen isotopes to complement hydrologic proxies. δ18O of surface water and Sphagnum moss cellulose from bogs throughout North America indicates a correlation between average growing season temperatures and δ18O-values. The existence of a modern temperature signal in moss cellulose suggests that δ18O-derived records will not only complement paleohydrological records, but also help assess relative changes in precipitation and temperature. Humification and testate amoebae data from two cores taken from Minden and Irwin Smith Bogs in central and northeastern Michigan have recorded several extreme drought events during the Holocene, including one at 1000 YBP. Comparison of δ18O-values of picked Sphagnum remains to down-core humification and testate amoebae data suggest good temporal correspondence, with the δ18O-values around 1000 YBP indicating a warmer growing season.

Ecohydrology of a Sphagnum peatland in transitional climate - an interdysciplinary study

Science.gov (United States)

Słowińska, S.; Słowiński, M.; Lamentowicz, M.; Skrzypek, G.

2012-04-01

Sphagnum peatlands of the Central Europe are regarded as the valuable and endangered habitats. Their existence depends on the complex climatic, hydrological, topographical and botanical conditions. Good understanding of peatlands' ecohydrology is crucial for the appropriate environmental management. Our long-term ecological study is focused on a poor fen located in Northern Poland - a unique floristic nature reserve and Nature 2000 area. Main aims of the research were to: a) understand an influence of the temperature and precipitation on the ground water, b) explain an impact of the local climate and the groundwater table level on testate amoebae communities, Sphagnum mosses growth and stable carbon, nitrogen and oxygen isotope compositions, c) use the neo- ecological data for the quantitative palaeoecological reconstructions. We have been conducting the monitoring of the growth of Sphagnum mosses in five plots. Vegetation was sampled three times during the growing season for the stable isotope and testate amoebae analyses (July, September and December 2009). Temperature of the air and acrotelm, air humidity, precipitation and groundwater table were recorded using automatic data loggers. Our research confirmed that even small fluctuation of temperature, precipitation and annual distribution of precipitation have a very strong impact on the hydrology of the peatland. Testate amoeba communities and stable isotopes from Sphagnum clearly indicated the hydrological response of the mire in the different parts of the peatland. The next step is a detailed seasonal study supported by the manipulative warming experiment.

Detection of Balamuthia mandrillaris DNA by real-time PCR targeting the RNase P gene

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Lewin Astrid

2008-12-01

Full Text Available Abstract Background The free-living amoeba Balamuthia mandrillaris may cause fatal encephalitis both in immunocompromised and in – apparently – immunocompetent humans and other mammalian species. Rapid, specific, sensitive, and reliable detection requiring little pathogen-specific expertise is an absolute prerequisite for a successful therapy and a welcome tool for both experimental and epidemiological research. Results A real-time polymerase chain reaction assay using TaqMan® probes (real-time PCR was established specifically targeting the RNase P gene of B. mandrillaris amoebae. The assay detected at least 2 (down to 0.5 genomes of B. mandrillaris grown in axenic culture. It did not react with DNA from closely related Acanthamoeba (3 species, nor with DNA from Toxoplasma gondii, Leishmania major, Pneumocystis murina, Mycobacterium bovis (BCG, human brain, various mouse organs, or from human and murine cell lines. The assay efficiently detected B. mandrillaris DNA in spiked cell cultures, spiked murine organ homogenates, B. mandrillaris-infected mice, and CNS tissue-DNA preparations from 2 patients with proven cerebral balamuthiasis. This novel primer set was successfully combined with a published set that targets the B. mandrillaris 18S rRNA gene in a duplex real-time PCR assay to ensure maximum specificity and as a precaution against false negative results. Conclusion A real-time PCR assay for B. mandrillaris amoebae is presented, that is highly specific, sensitive, and reliable and thus suited both for diagnosis and for research.

Giant viruses of amoebas: an update

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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.

New Entamoeba group in howler monkeys (Alouatta spp.) associated with parasites of reptiles.

Science.gov (United States)

Villanueva-García, Claudia; Gordillo-Chávez, Elías José; Baños-Ojeda, Carlos; Rendón-Franco, Emilio; Muñoz-García, Claudia Irais; Carrero, Julio César; Córdoba-Aguilar, Alex; Maravilla, Pablo; Galian, José; Martínez-Hernández, Fernando; Villalobos, Guiehdani

2017-08-01

Our knowledge of the parasite species present in wildlife hosts is incomplete. Protozoans such as amoebae of the genus Entamoeba infect a large variety of vertebrate species, including NHPs. However, traditionally, their identification has been accomplished through microscopic evaluation; therefore, amoeba species have not always been identified correctly. We searched for Entamoeba spp. using a fragment of the small subunit rDNA in free-ranging howler monkeys (Alouatta palliata and A. pigra) from southeast Mexico. One hundred fifty five samples were collected, with 46 from A. palliata and 109 from A. pigra and 8 of the total samples were positive. We detected a new clade of Entamoeba, which was separated from other described species but closer to E. insolita, as well as an unnamed sequence typically found in iguana species with low shared identity values (reptiles.

Bacteria and parasites in contact lenses of asymptomatic wearers in Nigeria

Directory of Open Access Journals (Sweden)

Michael Osita Emina

2011-04-01

Conclusions: EWCL present more microorganisms and pose threat to the users. DWCL had more amoebae, which calls for suitable lens care methods. Further studies may be needed to determine the level of care required for contact lens users in developing countries.

All basic condensed matter physics phenomena and notions mirror ...

Indian Academy of Sciences (India)

biology an opportunity to explore a variety of condensed matter phenomena and situations, some of which have ... The biological matter such as the tiniest of life, an amoeba, is alive ..... and black-holes, nature fascinates physicists. It is the ...

A comparison of assays measuring the viability of Legionella pneumophila after treatment with copper and silver ions

Science.gov (United States)

Background: The relatively high prevalence of Legionella pneumophila in premise plumbing systems has been widely reported. Published reports indicate Legionella has a comparatively high resistance to chlorine and moreover has the ability to grow in phagocytic amoeba which could p...

Impact of drinking water conditions and copper materials on downstream biofilm microbial communities and legionella pneumophila colonization

Science.gov (United States)

Legionella pneumophila, the medically important species within the genus Legionella, is a concern in engineered water systems. Its ability to amplify within free-living amoebae is well documented, but its interactions/ecology within the microbial community of drinking water biofi...

Biology Today symposium | Mid Year Meetings | Events | Indian ...

Indian Academy of Sciences (India)

11.15, D. P. KASBEKAR, Centre for Cellular and Molecular Biology, Hyderabad Neurospora abhors a transposon. 11.45, IMRAN SIDDIQI, Centre for Cellular and Molecular Biology, Hyderabad Meiotic chromosome organization. 12.15, VIDYANAND NANJUNDIAH, Indian Institute of Science, Bengaluru Social amoebae.

The disappearance of Sphagnum imbricatum from Butterburn Flow, UK

NARCIS (Netherlands)

McClymont, E.L.; Mauquoy, D.; Yeloff, D.; Broekens, P.; van Geel, B.; Charman, D.J.; Pancost, R.D.; Chambers, F.M.; Evershed, R.P.

2008-01-01

The disappearance of the previously abundant moss species Sphagnum imbricatum has been investigated at Butterburn Flow, northern England, using organic geochemical, elemental, macrofossil, pollen and testate amoebae analyses. Variations in the assemblage of peat-forming plants were tracked using the

Entamoeba histolytica-secreted cysteine proteases induce IL-8 production in human mast cells via a PAR2-independent mechanism.

Science.gov (United States)

Lee, Young Ah; Nam, Young Hee; Min, Arim; Kim, Kyeong Ah; Nozaki, Tomoyoshi; Saito-Nakano, Yumiko; Mirelman, David; Shin, Myeong Heon

2014-01-01

Entamoeba histolytica is an extracellular tissue parasite causing colitis and occasional liver abscess in humans. E. histolytica-derived secretory products (SPs) contain large amounts of cysteine proteases (CPs), one of the important amoebic virulence factors. Although tissue-residing mast cells play an important role in the mucosal inflammatory response to this pathogen, it is not known whether the SPs induce mast cell activation. In this study, when human mast cells (HMC-1 cells) were stimulated with SPs collected from pathogenic wild-type amoebae, interleukin IL-8 mRNA expression and production were significantly increased compared with cells incubated with medium alone. Inhibition of CP activity in the SPs with heat or the CP inhibitor E64 resulted in significant reduction of IL-8 production. Moreover, SPs obtained from inhibitors of cysteine protease (ICP)-overexpressing amoebae with low CP activity showed weaker stimulatory effects on IL-8 production than the wild-type control. Preincubation of HMC-1 cells with antibodies to human protease-activated receptor 2 (PAR2) did not affect the SP-induced IL-8 production. These results suggest that cysteine proteases in E. histolytica-derived secretory products stimulate mast cells to produce IL-8 via a PAR2-independent mechanism, which contributes to IL-8-mediated tissue inflammatory responses during the early phase of human amoebiasis. © Y.A. Lee et al., published by EDP Sciences, 2014.

Entamoeba histolytica-secreted cysteine proteases induce IL-8 production in human mast cells via a PAR2-independent mechanism

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Lee Young Ah

2014-01-01

Full Text Available Entamoeba histolytica is an extracellular tissue parasite causing colitis and occasional liver abscess in humans. E. histolytica-derived secretory products (SPs contain large amounts of cysteine proteases (CPs, one of the important amoebic virulence factors. Although tissue-residing mast cells play an important role in the mucosal inflammatory response to this pathogen, it is not known whether the SPs induce mast cell activation. In this study, when human mast cells (HMC-1 cells were stimulated with SPs collected from pathogenic wild-type amoebae, interleukin IL-8 mRNA expression and production were significantly increased compared with cells incubated with medium alone. Inhibition of CP activity in the SPs with heat or the CP inhibitor E64 resulted in significant reduction of IL-8 production. Moreover, SPs obtained from inhibitors of cysteine protease (ICP-overexpressing amoebae with low CP activity showed weaker stimulatory effects on IL-8 production than the wild-type control. Preincubation of HMC-1 cells with antibodies to human protease-activated receptor 2 (PAR2 did not affect the SP-induced IL-8 production. These results suggest that cysteine proteases in E. histolytica-derived secretory products stimulate mast cells to produce IL-8 via a PAR2-independent mechanism, which contributes to IL-8-mediated tissue inflammatory responses during the early phase of human amoebiasis.

Comparison of biofilm ecology supporting growth of individual Naegleria species in a drinking water distribution system.

Science.gov (United States)

Puzon, Geoffrey J; Wylie, Jason T; Walsh, Tom; Braun, Kalan; Morgan, Matthew J

2017-04-01

Free-living amoebae (FLA) are common components of microbial communities in drinking water distribution systems (DWDS). FLA are of clinical importance both as pathogens and as reservoirs for bacterial pathogens, so identifying the conditions promoting amoebae colonisation of DWDSs is an important public health concern for water utilities. We used high-throughput amplicon sequencing to compare eukaryotic and bacterial communities associated with DWDS biofilms supporting distinct FLA species (Naegleria fowleri, N. lovaniensis or Vermamoeba sp.) at sites with similar physical/chemical conditions. Eukaryote and bacterial communities were characteristics of different FLA species presence, and biofilms supporting Naegleria growth had higher bacterial richness and higher abundance of Proteobacteria, Bacteroidetes (bacteria), Nematoda and Rotifera (eukaryota). The eukaryotic community in the biofilms had the greatest difference in relation to the presence of N. fowleri, while the bacterial community identified individual bacterial families associated with the presence of different Naegleria species. Our results demonstrate that ecogenomics data provide a powerful tool for studying the microbial and meiobiotal content of biofilms, and, in these samples can effectively discriminate biofilm communities supporting pathogenic N. fowleri. The identification of microbial species associated with N. fowleri could further be used in the management and control of N. fowleri in DWDS. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Impact of Chlorine and Heat on the Survival of Hartmannella vermiformis and Subsequent Growth of Legionella pneumophila.

Science.gov (United States)

Kuchta, J M; Navratil, J S; Shepherd, M E; Wadowsky, R M; Dowling, J N; States, S J; Yee, R B

1993-12-01

Hartmannella vermiformis, a common amoebal inhabitant of potable-water systems, supports intracellular multiplication of Legionella pneumophila and is probably important in the transportation and amplification of legionellae within these systems. To provide a practical guide for decontamination of potable-water systems, we assessed the chlorine and heat resistance of H. vermiformis. H. vermiformis cysts and trophozoites were treated independently with chlorine at concentrations of 2.0 to 10.0 ppm for 30 min and then cocultured with L. pneumophila. Both cysts and trophozoites were sensitive to concentrations between 2.0 and 4.0 ppm and above (trophozoites somewhat more so than cysts), and 10.0 ppm was lethal to both forms. Hartmannellae treated with chlorine up to a concentration of 4.0 ppm supported the growth of legionellae. To determine whether heat would be an effective addendum to chlorine treatment of amoebae, hartmannellae were subjected to temperatures of 55 and 60 degrees C for 30 min and alternatively to 50 degrees C followed by treatment with chlorine at a concentration of 2 ppm. Fewer than 0.05% of the amoebae survived treatment at 55 degrees C, and there were no survivors at 60 degrees C. Pretreatment at 50 degrees C appeared to make hartmannella cysts more susceptible to chlorine but did not further reduce the concentration of trophozoites.

Water Table Depth Reconstruction in Ombrotrophic Peatlands Using Biomarker Abundance Ratios and Compound-Specific Hydrogen Isotope Composition

Science.gov (United States)

Nichols, J. E.; Jackson, S. T.; Booth, R. K.; Pendall, E. G.; Huang, Y.

2005-12-01

Sediment cores from ombrotrophic peat bogs provide sensitive records of changes in precipitation/evaporation (P/E) balance. Various proxies have been developed to reconstruct surface moisture conditions in peat bogs, including testate amoebae, plant macrofossils, and peat humification. Studying species composition of testate amoeba assemblages is time consuming and requires specialized training. Humification index can be influenced by environmental factors other than moisture balance. The plant macrofossil proxy is less quantitative and cannot be performed on highly decomposed samples. We demonstrate that the ratio of C23 alkane to C29 alkane abundance may provide a simple alternative or complementary means of tracking peatland water-table depth. Data for this proxy can be collected quickly using a small sample (100 mg dry). Water-table depth decreases during drought, and abundance of Sphagnum, the dominant peat-forming genus, decreases as vascular plants increase. Sphagnum moss produces mainly medium chain-length alkanes (C21-C25) while vascular plants (grasses and shrubs) produce primarily longer chain-length alkanes (C27-C31). Therefore, C23:C29 n-alkane ratios quantitatively track the water table depth fluctuations in peat bogs. We compared C23:C29 n-alkane ratios in a core from Minden Bog (southeastern Michigan) with water table depth reconstructions based on testate-amoeba assemblages and humification. The 184-cm core spans the past ~3kyr of continuous peat deposition in the bog. Our results indicate that the alkane ratios closely track the water table depth variations, with C29 most abundant during droughts. We also explored the use of D/H ratios in Sphagnum biomarkers as a water-table depth proxy. Compound-specific hydrogen isotope ratio analyses were performed on Sphagnum biomarkers: C23 and C25 alkane and C24 acid. Dry periods are represented in these records by an enrichment of deuterium in these Sphagnum-specific compounds. These events also correlate

Using Sparse Capabilities in a Distributed Operating System

NARCIS (Netherlands)

Tanenbaum, Andrew S.; Mullender, Sape J.; van Renesse, Robbert

Most distributed operating systems constructed to date have lacked a unifying mechanism for naming and protection. In this paper we discuss a system, Amoeba, that uses capabilities for naming and protecting objects. In contrast to traditional, centralized operating systems, in which capabilities are

Formation, succession and landscape history of Central-European summit raised bogs: A multiproxy study from the Hrubý Jeseník Mountains

Czech Academy of Sciences Publication Activity Database

Dudová, Lydie; Hájková, Petra; Buchtová, H.; Opravilová, V.

2013-01-01

Roč. 23, č. 2 (2013), s. 230-242 ISSN 0959-6836 R&D Projects: GA ČR GA206/08/0389 Institutional support: RVO:67985939 Keywords : bog succession * Larix * testate amoebae Subject RIV: EF - Botanics Impact factor: 3.794, year: 2013

Phototaxis during the slug stage of Dictyostelium discoideum: a model study

NARCIS (Netherlands)

Marée, A.F.M.; Panfilov, A.V.; Hogeweg, P.

1999-01-01

During the slug stage, the cellular slime mould Dictyostelium discoideum moves towards light sources. We have modelled this phototactic behaviour using a hybrid cellular automata/partial differential equation model. In our model, individual amoebae are not able to measure the direction from which

Molecular comparison of cultivable protozoa from a pristine and a polycyclic aromatic hydrocarbon polluted site

DEFF Research Database (Denmark)

Lara, E; Berney, C; Ekelund, Flemming

2007-01-01

We compared the abundance and diversity of cultivable protozoa (flagellates and amoebae) in a polycyclic aromatic hydrocarbon (PAH) polluted soil and an unpolluted control, by isolating and cultivating clonal strains. The number of cultivable protozoa was higher in the polluted soil; however...

Non-tuberculous mycobacteria and microbial populations in drinking water distribution systems

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Rossella Briancesco

2010-01-01

Full Text Available Data on the occurrence of non-tuberculous mycobacteria (NTM, in parallel with those obtained for bacterial indicators and amoebae, are presented with the aim to collect information on the spread of NTM in drinking water distribution systems in Italy. Samples were collected from taps of hospitals and households in Central and Southern Italy. The concentration values obtained for the more traditional microbial parameters complied with the mandatory requirements for drinking water. Conversely, moderate-to-high microbial loads (till 300 CFU/L were observed for the NTM. Positive samples were obtained from 62% of the investigated water samples. Analogous results were observed for amoebae showing a higher percentage of positive samples (76%. In terms of public health, the presence of mycobacteria in water distribution systems may represent a potential risk especially for vulnerable people such as children, the elderly or immunocompromised individuals.

Retrotransposon Domestication and Control in Dictyostelium discoideum

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Marek Malicki

2017-10-01

Full Text Available Transposable elements, identified in all eukaryotes, are mobile genetic units that can change their genomic position. Transposons usually employ an excision and reintegration mechanism, by which they change position, but not copy number. In contrast, retrotransposons amplify via RNA intermediates, increasing their genomic copy number. Hence, they represent a particular threat to the structural and informational integrity of the invaded genome. The social amoeba Dictyostelium discoideum, model organism of the evolutionary Amoebozoa supergroup, features a haploid, gene-dense genome that offers limited space for damage-free transposition. Several of its contemporary retrotransposons display intrinsic integration preferences, for example by inserting next to transfer RNA genes or other retroelements. Likely, any retrotransposons that invaded the genome of the amoeba in a non-directed manner were lost during evolution, as this would result in decreased fitness of the organism. Thus, the positional preference of the Dictyostelium retroelements might represent a domestication of the selfish elements. Likewise, the reduced danger of such domesticated transposable elements led to their accumulation, and they represent about 10% of the current genome of D. discoideum. To prevent the uncontrolled spreading of retrotransposons, the amoeba employs control mechanisms including RNA interference and heterochromatization. Here, we review TRE5-A, DIRS-1 and Skipper-1, as representatives of the three retrotransposon classes in D. discoideum, which make up 5.7% of the Dictyostelium genome. We compile open questions with respect to their mobility and cellular regulation, and suggest strategies, how these questions might be addressed experimentally.

Model cortical association fields account for the time course and dependence on target complexity of human contour perception.

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Vadas Gintautas

2011-10-01

Full Text Available Can lateral connectivity in the primary visual cortex account for the time dependence and intrinsic task difficulty of human contour detection? To answer this question, we created a synthetic image set that prevents sole reliance on either low-level visual features or high-level context for the detection of target objects. Rendered images consist of smoothly varying, globally aligned contour fragments (amoebas distributed among groups of randomly rotated fragments (clutter. The time course and accuracy of amoeba detection by humans was measured using a two-alternative forced choice protocol with self-reported confidence and variable image presentation time (20-200 ms, followed by an image mask optimized so as to interrupt visual processing. Measured psychometric functions were well fit by sigmoidal functions with exponential time constants of 30-91 ms, depending on amoeba complexity. Key aspects of the psychophysical experiments were accounted for by a computational network model, in which simulated responses across retinotopic arrays of orientation-selective elements were modulated by cortical association fields, represented as multiplicative kernels computed from the differences in pairwise edge statistics between target and distractor images. Comparing the experimental and the computational results suggests that each iteration of the lateral interactions takes at least [Formula: see text] ms of cortical processing time. Our results provide evidence that cortical association fields between orientation selective elements in early visual areas can account for important temporal and task-dependent aspects of the psychometric curves characterizing human contour perception, with the remaining discrepancies postulated to arise from the influence of higher cortical areas.

Experimental study on pathogenic potential of six Acanthamoeba strains isolated from fish

Czech Academy of Sciences Publication Activity Database

Veverková, Marie; Dyková, Iva; Pecková, Hana

2002-01-01

Roč. 49, č. 3 (2002), s. 243-245 ISSN 0015-5683 R&D Projects: GA AV ČR KSK6005114 Institutional research plan: CEZ:AV0Z6022909 Keywords : amoeba * fish * pathology Subject RIV: EA - Cell Biology Impact factor: 0.515, year: 2002

Meeting on the Microbiology of Soils, Autumn 2001: Estimation of protozoan diversity in soil

DEFF Research Database (Denmark)

Ekelund, Flemming

2002-01-01

Different methods of estimating protozoan diversity in soil are discussed in this paper, with the major emphasis on heterotrophic flagellates. Although many species of ciliates and testate amoebae seem to be unique to the soil environment, the communities of heterotrophic flagellates and naked am...

Microbial- and isothiocyanate-mediated control of Phytophthora and Pythium species

Science.gov (United States)

M.F. Cohen; E. Yamamoto; E. Condeso; B.L. Anacker; N. Rank; M. Mazzola

2008-01-01

Plant pathogens of the oomycete lineage share common susceptibilities to many biotic and abiotic stresses. We are investigating the potential of antagonistic bacteria, isothiocyanates, and mycophagous amoebae to control diseases caused by Phytophthora spp., including the etiologic agent of sudden oak death, Phytophthora ramorum (...

Filling Knowledge Gaps for Mimivirus Entry, Uncoating, and Morphogenesis.

Science.gov (United States)

Andrade, Ana Cláudia Dos Santos Pereira; Rodrigues, Rodrigo Araújo Lima; Oliveira, Graziele Pereira; Andrade, Kétyllen Reis; Bonjardim, Cláudio Antônio; La Scola, Bernard; Kroon, Erna Geessien; Abrahão, Jônatas Santos

2017-11-15

Since the discovery of mimivirus, its unusual structural and genomic features have raised great interest in the study of its biology; however, many aspects concerning its replication cycle remain uncertain. In this study, extensive analyses of electron microscope images, as well as biological assay results, shed light on unclear points concerning the mimivirus replication cycle. We found that treatment with cytochalasin, a phagocytosis inhibitor, negatively impacted the incorporation of mimivirus particles by Acanthamoeba castellanii , causing a negative effect on viral growth in amoeba monolayers. Treatment of amoebas with bafilomicin significantly impacted mimivirus uncoating and replication. In conjunction with microscopic analyses, these data suggest that mimiviruses indeed depend on phagocytosis for entry into amoebas, and particle uncoating (and stargate opening) appears to be dependent on phagosome acidification. In-depth analyses of particle morphogenesis suggest that the mimivirus capsids are assembled from growing lamellar structures. Despite proposals from previous studies that genome acquisition occurs before the acquisition of fibrils, our results clearly demonstrate that the genome and fibrils can be acquired simultaneously. Our data suggest the existence of a specific area surrounding the core of the viral factory where particles acquire the surface fibrils. Furthermore, we reinforce the concept that defective particles can be formed even in the absence of virophages. Our work provides new information about unexplored steps in the life cycle of mimivirus. IMPORTANCE Investigating the viral life cycle is essential to a better understanding of virus biology. The combination of biological assays and microscopic images allows a clear view of the biological features of viruses. Since the discovery of mimivirus, many studies have been conducted to characterize its replication cycle, but many knowledge gaps remain to be filled. In this study, we conducted a

Regulation of TORC2 complex in Dictyostelium discoideum

NARCIS (Netherlands)

Khanna, Ankita

2016-01-01

Dictyostelium is an amoeba that lives in the soil where it feeds on bacteria. During scarcity of food, Dictyostelium cells undergo a highly regulated developmental process in which the cells aggregate by chemotaxing towards pulsatile emission of extracellular cAMP from a signaling center; the cells

The Life History of Flabellula baltica Smirnov (Gymnamoebae, Rhizopoda): Adaptations to a Spatially and Temporally Heterogeneous Environment

DEFF Research Database (Denmark)

Fenchel, Tom

2010-01-01

The polymorphic life history of the marine naked amoeba Flabellula baltica was studied. It can be interpreted in terms of adaptations to an environment that is patchy in time and space and it represents trade-off between longevity during starvation and the ability to initiate multiplication soon ...

Systemic acanthamoebiasis associated with canine distemper in dogs in the semiarid region of Paraíba, Brazil

Directory of Open Access Journals (Sweden)

Maria T.S. Frade

2015-02-01

Full Text Available Infections by free-living amoebae can cause systemic disease in animals and humans. We describe the epidemiological, clinical and pathological aspects of disseminated acanthamoebiasis associated with canine distemper in three dogs of the semiarid region of Paraíba, Northeastern Brazil. Affected dogs developed progressive neurological and respiratory signs that progressed to death within in two to 20 days. Gross lesions were irregular and with yellow-reddish nodules randomly distributed in the lungs, heart, kidneys, spleen, lymph nodes, adrenals, and intestine. One dog had foci of malacia in the parietal cortex and another one in nucleus of brain basis. Histologically, pyogranulomas with areas of necrosis and hemorrhage in all organs affected were observed, associated with myriads of intralesional amoebic trophozoites. All three cases were concomitant canine distemper, that possibly triggered immunosuppression in the dogs. The diagnosis was performed through microscopic findings of infection by free-living amoebae and confirmed Acanthamoeba sp. by immunohistochemistry

DupA: a key regulator of the amoebal MAP kinase response to Legionella pneumophila

Science.gov (United States)

Li, Zhiru; Dugan, Aisling S.; Bloomfield, Gareth; Skelton, Jason; Ivens, Alasdair; Losick, Vicki; Isberg, Ralph R.

2009-01-01

SUMMARY The dupA gene, encoding a putative tyrosine kinase/dual specificity phosphatase (Dusp), was identified in a screen for Dictyostelium discoideum mutants altered in supporting Legionella pneumophila intracellular replication. The absence of dupA resulted in hyperphosphorylation of ERK1, consistent with the loss of a phosphatase activity, as well as degradation of ERK2. ERK1 hyperphosphorylation mimicked the response of this protein after bacterial challenge of wild type amoebae. Similar to Dusps in higher eukaryotic cells, the amoebal dupA gene was induced after bacterial contact, indicating a response of Dusps that is conserved from amoebae to mammals. A large set of genes was misregulated in the dupA− mutant that largely overlaps with genes responding to L. pneumophila infection. Some of the amoebal genes appear to be involved in a response similar to innate immunity in higher eukaryotes, indicating there was misregulation of a conserved response to bacteria. PMID:19748467

Concentration of Naegleria fowleri in natural waters used for recreational purposes in Sonora, Mexico (November 2007-October 2008).

Science.gov (United States)

Lares-Villa, Fernando; Hernández-Peña, Claudia

2010-09-01

A survey was designed to know the concentration of Naegleria fowleri in recreational areas in Hornos, Sonora, during a year. Samples were taken monthly at La Isleta and Las Palmas and the total amoeba counts were obtained by the most probable number method (MPN). The identification of N. fowleri was made by PCR. The maximum concentration of total thermophilic amoebae was 9175 MPN/L for La Isleta and 3477 MPN/L for Las Palmas. Thermophilic Naegleria were present mainly during summer and fall. October's concentrations were up to 201 MPN/L, at both places. The maximum concentrations of N. fowleri were 201 MPN/L and 18 MPN/L for La Isleta and Las Palmas respectively, and were isolated from August to October. The presence of N. fowleri in these particular natural bodies of water reinforces the need for adaptation of preventive measures to avoid cases of primary amoebic meningoencephalitis. Copyright 2010 Elsevier Inc. All rights reserved.

Microbiological quality in the Zacatepec's aquifer, Morelos, Mexico; Calidad microbiologica del acuifero de Zacatepec, Morelos, Mexico

Energy Technology Data Exchange (ETDEWEB)

Ramirez, Elizabeth; Robles, Esperanza; Sainz, Ma. Guadalupe; Ayala, Reynaldo; Campoy, Emelia [Facultad de Estudios Superiores, Iztacala, Universidad Nacional Autonoma de Mexico, Tlalnepantla, Estado de Mexico (Mexico)]. E-mail: erf@servidor.unam.mx

2009-11-15

Groundwater is one of the main supply sources of drinking water in Mexico, as they support a poor biological community, because of their low contain of nutrients. However in the recent years, human activities and urban growth are the main factors of aquifer contamination. Therefore, water may contain chemical contaminants and microorganisms that can cause several diseases; such is the case of free-living amoebae (FLA). The objective of this research is to determine the microbiological quality (total coliforms, fecal coliforms and free-living amoebae) of Zacatepec aquifer, in the state of Morelos. Monthly samplings of thirteen wells of the aquifer were carried out during one year. The following physicochemical parameters were measure in situ: pH, dissolved oxygen (DO) and temperature. Total and fecal coliforms were determined by the membrane filter technique. Free-living amoebae were cultured on non-nutritive agar medium (NNE); the identification was carried out taking in account their morphological features. All the wells were polluted with total coliforms, one with a geometric mean of 107 CFU/100 mL. Fecal coliforms were absent in four wells; nevertheless, one presented a geometric mean of 107 CFU/100 mL. The most polluted well was number 3, and the months with more bacteria were April and July. Free-living amoebae were isolated in all the wells, the highest isolation number was found in well number 2, while the lowest were found in wells 4, 5, and 10. December and January were the months with the highest number of amoebae, and April with the lowest. Twenty two species belonging to 16 genera were isolated; the most frequent was Hartmannella with 38 %; this amoeba has not been reported as pathogenic, but it has been associated to ocular and brain infections in humans. Of the pathogenic amoebae, Acanthamoeba was isolated, but with a low frequency (6.7 %). Physicochemical parameters had low seasonal variation, pH was close to neutrality in a range of 6.4 to 7

Effects of Disinfection on Legionella spp., Eukarya, and Biofilms in a Hot Water System

Science.gov (United States)

Moletta-Denat, Marina; Frère, Jacques; Onillon, Séverine; Trouilhé, Marie-Cécile; Robine, Enric

2012-01-01

Legionella species are frequently detected in hot water systems, attached to the surface as a biofilm. In this work, the dynamics of Legionella spp. and diverse bacteria and eukarya associated together in the biofilm, coming from a pilot scale 1 system simulating a real hot water system, were investigated throughout 6 months after two successive heat shock treatments followed by three successive chemical treatments. Community structure was assessed by a fingerprint technique, single-strand conformation polymorphism (SSCP). In addition, the diversity and dynamics of Legionella and eukarya were investigated by small-subunit (SSU) ribosomal cloning and sequencing. Our results showed that pathogenic Legionella species remained after the heat shock and chemical treatments (Legionella pneumophila and Legionella anisa, respectively). The biofilm was not removed, and the bacterial community structure was transitorily affected by the treatments. Moreover, several amoebae had been detected in the biofilm before treatments (Thecamoebae sp., Vannella sp., and Hartmanella vermiformis) and after the first heat shock treatment, but only H. vermiformis remained. However, another protozoan affiliated with Alveolata, which is known as a host cell for Legionella, dominated the eukaryal species after the second heat shock and chemical treatment tests. Therefore, effective Legionella disinfection may be dependent on the elimination of these important microbial components. We suggest that eradicating Legionella in hot water networks requires better study of bacterial and eukaryal species associated with Legionella in biofilms. PMID:22820326

Genetic Determinism vs. Phenotypic Plasticity in Protist Morphology

Czech Academy of Sciences Publication Activity Database

Mulot, M.; Marcisz, K.; Grandgirard, L.; Lara, E.; Kosakyan, Anush; Robroek, B. J. M.; Lamentowicz, M.; Payne, R. J.; Mitchell, E.A.D.

2017-01-01

Roč. 64, č. 6 (2017), s. 729-739 ISSN 1066-5234 Institutional support: RVO:60077344 Keywords : Body size * protozoa * soil moisture * testate amoebae * water table depth Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Genetics and heredity (medical genetics to be 3) Impact factor: 2.692, year: 2016

The evolution of a distributed operating system

NARCIS (Netherlands)

van Renesse, Robbert; Tanenbaum, Andrew S.; Mullender, Sape J.; Schröder-Preikschat, Wolfgang; Zimmer, Wolfgang

AMOEBA is a research project to build a true distributed operating system using the object model. Under the COST11-ter MANDIS project this work was extended to cover wide-area networks. Besides describing the system, this paper discusses the successive versions in the implementation of its model,

Diffusion-Assisted Aggregation and Synchronization in Dictyostelium discoideum

Science.gov (United States)

Nagano, Seido

1998-05-01

In biological pattern formation, chemotaxis and cell adhesion are essential. However, we lack quantitative data and a theory to understand their coordination. The cellular dynamics theory presented can clarify how Dictyostelium discoideum amoebae use diffusible cyclic adenosine 3',5'-monophosphate, and coordinate chemotaxis and cell adhesion during aggregation.

Ribosomal RNA genes challenge the monophyly of the Hyalospheniidae (Amoebozoa: Arcellinida)

DEFF Research Database (Denmark)

Lara, Enrique; Heger, Thierry J; Ekelund, Flemming

2008-01-01

causes confusion in the phylogeny, taxonomy and the debate on cosmopolitanism of free-living protists. Here we present a SSU rRNA-based phylogeny of the Hyalospheniidae including the most common species. Similar to the filose testate amoebae of the order Euglyphida the most basal clades have a terminal...

Strategies of the protozoan parasite Entamoeba histolytica to evade ...

Indian Academy of Sciences (India)

Unknown

and the subsequent migration of the amoeba to the liver where abscesses are formed (Espinosa-Cantellano and. Martinez-Paloma 2000; Stanley 2001). ..... activity of bacterial peroxiredoxins; Nature (London) 407. 211–215. Cario E and Podolsky D K 2000 Differential alteration in intes- tinal epithelial cell expression of ...

Increased aeolian activity during humidity shifts as recorded in a raised bog in south-west Sweden during the past 1700 years

Directory of Open Access Journals (Sweden)

R. de Jong

2007-07-01

Full Text Available Analyses of testate amoebae and aeolian sediment influx (ASI were used to reconstruct effective humidity changes and aeolian activity in the coastal zone of south-west Sweden. Cores were taken from an ombrotrophic peat sequence from the Undarsmosse bog. Since both types of analysis were carried out on the same core, a direct comparison between humidity fluctuations in the bog and aeolian activity was possible, potentially providing detailed information on atmospheric circulation changes in this region. Relatively wet bog surface conditions occurred from around 1500 to 1230 and 770 to 380 cal. yrs BP, whereas dry conditions dominated from ca. 1630 to 1530, 1160 to 830 and 300 to 50 cal. yrs BP. The transitions between these phases occurred within 60–100 years and are characterised by a major change in the testate amoebae assemblages. A watertable reconstruction was used to study the hydrological changes at the bog surface in more detail. ASI peak events were reconstructed around 1450, 1150, 850 and after 370 cal. yrs BP. Most interestingly, these aeolian activity peaks started during the recorded hydrological transitions, regardless of the direction of these shifts. Our results therefore suggest that humidity shifts in this region were associated with temporary intensifications of atmospheric circulation during the past 1700 years. Several ASI peaks apparently coincide with reduced solar activity, possibly suggesting a solar related cause for some of the observed events.

Free-living protozoa in the gastrointestinal tract and feces of pigs: Exploration of an unknown world and towards a protocol for the recovery of free-living protozoa.

Science.gov (United States)

Chavatte, N; Lambrecht, E; Van Damme, I; Sabbe, K; Houf, K

2016-07-30

Associations with free-living protozoa (FLP) have been implicated in the persistence of foodborne pathogenic bacteria in food-related environments. To date however no information is available on the presence of FLP in the gastrointestinal tract (GIT) of pigs, which represents an important reservoir for zoonotic foodborne bacteria and hence a potential location for associations with FLP. This is at least partly due to the lack of adequate protocols to recover FLP from intestinal content and feces. In the present study different protocols to recover FLP from the porcine GIT and feces were tested. The most effective protocols were then applied to explore the presence of live FLP in the pig GIT and feces. A filtration based protocol was identified as the most suitable method to recover viable FLP from the porcine GIT and feces. Cultivable FLP were recovered from different parts of the GIT, suggesting at least a transient presence of FLP in this habitat. Free-living amoebae species (Acanthamoeba spp., Hyperamoeba sp., Vannella sp., Vermamoeba vermiformis, hartmannellids and vahlkampfiids) but also ciliates (Colpoda sp. and Tetrahymena/Glaucoma lookalike) and flagellates (cercomonads, bodonids and glissomonads) were recovered and cultured from pig intestinal content. Acanthamoeba hatchetti and Filamoeba sinensis were isolated for the first time from pig intestinal content. Despite high gastric acidity, non-cyst forming amoeba species were also detected which suggests survival of their trophozoites in the animal GIT. Copyright © 2016 Elsevier B.V. All rights reserved.

One Year Genome Evolution of Lausannevirus in Allopatric versus Sympatric Conditions.

Science.gov (United States)

Mueller, Linda; Bertelli, Claire; Pillonel, Trestan; Salamin, Nicolas; Greub, Gilbert

2017-06-01

Amoeba-resisting microorganisms raised a great interest during the last decade. Among them, some large DNA viruses present huge genomes up to 2.5 Mb long, exceeding the size of small bacterial genomes. The rate of genome evolution in terms of mutation, deletion, and gene acquisition in these genomes is yet unknown. Given the suspected high plasticity of viral genomes, the microevolution of the 346 kb genome of Lausannevirus, a member of Megavirales, was studied. Hence, Lausannevirus was co-cultured within the amoeba Acanthamoeba castellanii over one year. Despite a low number of mutations, the virus showed a genome reduction of 3.7% after 12 months. Lausannevirus genome evolution in sympatric conditions was investigated by its co-culture with Estrella lausannensis, an obligate intracellular bacterium, in the amoeba A. castellanii during one year. Cultures were split every 3 months. Genome sequencing revealed that in these conditions both, Lausannevirus and E. lausannensis, show stable genome, presenting no major rearrangement. In fact, after one year they acquired from 2 to 7 and from 4 to 10 mutations per culture for Lausannevirus and E. lausannensis, respectively. Interestingly, different mutations in the endonuclease encoding genes of Lausannevirus were observed in different subcultures, highlighting the importance of this gene product in the replication of Lausannevirus. Conversely, mutations in E. lausannensis were mainly located in a gene encoding for a phosphoenolpyruvate-protein phosphotransferase (PtsI), implicated in sugar metabolism. Moreover, in our conditions and with our analyses we detected no horizontal gene transfer during one year of co-culture. © The Author(s) 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Infection in a rat model reactivates attenuated virulence after long-term axenic culture of Acanthamoeba spp

Directory of Open Access Journals (Sweden)

Carolina De Marco Verissimo

2013-11-01

Full Text Available Prolonged culturing of many microorganisms leads to the loss of virulence and a reduction of their infective capacity. However, little is known about the changes in the pathogenic strains of Acanthamoeba after long culture periods. Our study evaluated the effect of prolonged culturing on the invasiveness of different isolates of Acanthamoeba in an in vivo rat model. ATCC strains of Acanthamoeba, isolates from the environment and clinical cases were evaluated. The in vivo model was effective in establishing the infection and differentiating the pathogenicity of the isolates and re-isolates. The amoebae cultured in the laboratory for long periods were less virulent than those that were recently isolated, confirming the importance of passing Acanthamoeba strains in animal models.

Response of microbial communities to experimental warming and precipitation decrease in Rzecin peatland (Poland)

Science.gov (United States)

Basińska, Anna M.; Gąbka, Maciej; Reczuga, Monika; Łuców, Dominika; Stróżecki, Marcin; Samson, Mateusz; Józefczyk, Damian; Chojnicki, Bogdan; Urbaniak, Marek; Leśny, Jacek; Olejnik, Janusz; Gilbert, Daniel; Silvennoinen, Hanna; Juszczak, Radosław; Lamentowicz, Mariusz

2017-04-01

In the last decade researchers are intensively testing the consequences of different climate change scenarios. Due to high biodiversity, huge amount of stored carbon and their sensitivity to environmental changes, peatlands became important for the temperature increase and drought experiments. Analyses showed that mosses, vascular plants and microbial communities were affected by warming or drought, but still not all effects are clear. Studying the response of microbial groups and indicators (e.g. mixotrophic species of testate amoeba) to warming in combination with decrease of precipitation will allow to better understand the future environmental changes. To recognize the inflow of organic matter and the carbon fixing processes in disturbed environment, we need to analyse the structure and biomass of main groups living in peatlands and the response of those groups to disturbances. The Polish - Norway "WETMAN" project was designed to recognize biotic and abiotic components of ecosystem response to active warming and decrease of precipitation. In this study we present the response of microbial communities and chosen testate amoeba species (TA) to different treatments: warming, warming and decreased precipitation and only decreased precipitation, in relation to control plots. The microbial biomass of upper and lower Sphagnum segments were analysed separately. Particular microbial groups were positively correlated with manipulations e. g. microalgae and rotifers, and other were negatively affected by combination of drought and warming e.g. cyanobacteria and testate amoeba. The structure of community was modified by manipulations, and differed in the case of upper and lower segment of Sphagnum. RDA analyses showed that different factors were crucial for the biomass of microbial groups in upper (conductivity, temperature and phosphorus) and lower (nitrates and sodium) segment. Considering higher taxonomic resolution we found that at the beginning of the experiment TA

VHTR-fuel irradiation capsules for VT-1 hole of JRR-2

International Nuclear Information System (INIS)

Kikuchi, Teruo; Kikuchi, Akira; Tobita, Tsutomu; Kashimura, Satoru; Miyasaka, Yasuhiko

1977-02-01

Irradiations of VHTR fuels were made in the VT-1 irradiation hole of JRR-2. Three capsules, VP-1, VP-2 and VP-4, which contained fuel compacts, were irradiated for 300 hr at temperatures of 950 0 , 1370 0 and 1500 0 C up to the estimated burn-ups of 0.74, 0.87 and 0.80%FIMA, respectively. And, to study the amoeba effect of fuel particles, two capsules, VP-3 and VP-5, were irradiated for 300 hr at temperatures of 1650 0 and 1670 0 C up to the estimated burn-ups of 0.38 and 0.33%FIMA, respectively. (auth.)

Collective Behavior of Amoebae in Thin Films

Science.gov (United States)

Bae, Albert

2005-03-01

We have discovered new aspects of social behavior in Dictyostelium discoideum by culturing high density colonies in liquid media depleted of nutrients in confined geometries by using three different preparations: I. thin (15-40um thick) and II. ultrathin (behavior of cells despite flattening that increased their areas by over an order of magnitude. We also observed that the earliest synchronized response of cells following the onset of starvation, a precursor to aggregation, was hastened by reducing the thickness of the aqueous culture layer. We were surprised to find that the threshold concentration for aggregation was raised by thin film confinement when compared to bulk behavior. Finally, both the ultra thin and microfluidic preparations reveal, with new clarity, vortex states of aggregation.

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

2016-01-01

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. PMID:27357338

Detección y diferenciación de Entamoeba histolytica y Entamoeba dispar mediante reacción en cadena de la polimerasa en individuos de una comunidad del Estado Zulia, Venezuela Detection and differentiation of Entamoeba histolytica and Entamoeba dispar by polymerase chain reaction in a community in Zulia State, Venezuela

Directory of Open Access Journals (Sweden)

Zulbey Rivero

2009-01-01

Full Text Available La identificación diferencial de Entamoeba histolytica y Entamoeba dispar es esencial para un tratamiento adecuado del paciente y con fines epidemiológicos. Para determinar la prevalencia de E. histolytica y E. dispar se estandarizó y aplicó un ensayo de PCR, utilizando oligonucleótidos específicos para cada especie. 204 muestras de heces de individuos de la comunidad de Santa Rosa de Agua (Municipio Maracaibo, Estado Zulia, Venezuela, fueron analizadas a través del examen directo con SSF (0,85% y lugol, concentrado de formol-éter y PCR. Al examen microscópico, 42 individuos (20,58% presentaron formas evolutivas del complejo E. histolytica/E. dispar; mientras que la técnica de PCR evidenció un total de 47 casos positivos a estas amibas; de los cuales 22 eran portadores de E. histolytica (10,78%, 16 (7,84% de E. dispar y 9 (4,41% presentaron infección mixta. No hubo diferencia significativa al relacionar las variables sexo y presencia de E. histolytica y/o E. dispar, ni con los grupos etarios. No existieron casos de estas amibas, en los menores de 2 años. La frecuencia observada de E. histolytica (31/204, demuestra el carácter endémico de la amibiasis en esta comunidad.Differential identification of Entamoeba histolytica and Entamoeba dispar is essential for both appropriate patient treatment and epidemiological purposes. To determine the prevalence of these amoeba infections in Santa Rosa de Agua (Maracaibo, Zulia State, Venezuela, a PCR assay using specific primers for each species was standardized and applied. 204 stool samples were analyzed through direct microscopic examination with SSF (0.85% and lugol, formol-ether concentration, and PCR. Under direct microscopy, 42 individuals (20.58% presented the E. histolytica/E. dispar complex. Meanwhile PCR showed 47 positive cases for these amoebas: 22 E. histolytica (10.78%, 16 E. dispar (7.84%, and 9 (4.41% mixed infections. There was no significant difference in the presence of E

Vermistella arctica n. sp. Nominates the Genus Vermistella as a Candidate for Taxon with Bipolar Distribution

Czech Academy of Sciences Publication Activity Database

Tyml, Tomáš; Kostka, Martin; Ditrich, O.; Dyková, I.

2016-01-01

Roč. 63, č. 2 (2016), s. 210-219 ISSN 1066-5234 R&D Projects: GA ČR(CZ) GBP505/12/G112 Institutional support: RVO:60077344 Keywords : actin * biogeography * bipolar distribution * free-living amoebae * phylogeny * polar regions * SSU Subject RIV: EG - Zoology Impact factor: 2.692, year: 2016

Effect of ionizing and non ionizing radiation on Protozoan and Parasites Ova causing gastroenteritis presents in sewage sludge wastes

International Nuclear Information System (INIS)

Shamma, M.; Al-Adawi, M.A.; Sharabi, N.

2006-01-01

Helminths eggs viability was determined by aid of methods and techniques which depend on the morphological parameters, studying the motility incubation and applying the vital staining. The protozoa viability was studied by using many vital staining, but applying culture techniques on specific composed media did not give any results. The disinfection results showed that for ascaris eggs, protozoa and amoeba oocysts irradiated by 6 KGy of gamma (Co 6 0) which was sufficient to kill all types of such parasites. On the contrary, conflict the UV radiation was able to motivate the ascaris eggs embryonations. Also, the viability of the Giardia and Entamoeba oocysts were not affected. In the light of the current experiments, it is possible to conclude that using the UV technique instead of the ionizing radiation for killing the helminths eggs and protozoa is not usable. (Authors)

Autonomous and non-autonomous traits mediate social cooperation ...

Indian Academy of Sciences (India)

2011-07-08

Jul 8, 2011 ... In the trishanku (triA−) mutant of the social amoeba Dictyostelium discoideum, aggregates are smaller than usual and the spore mass is located mid-way up the stalk, not at the apex. We have monitored aggregate territory size, spore allocation and fruiting body morphology in chimaeric groups of ...

The revised classification of eukaryotes

Czech Academy of Sciences Publication Activity Database

Adl, S.; Simpson, A. G. B.; Lane, C. E.; Lukeš, Julius; Bass, D.; Bowser, S. S.; Brown, M W.; Burki, F.; Dunthorn, M.; Hampl, V.; Heiss, A.; Hoppenrath, M.; Lara, E.; Gall, L. L.; Lynn, D. H.; McManus, H.; Mitchell, E. A. D.; Mozley-Stanridge, S. E.; Parfrey, L. W.; Pawlowski, J.; Rueckert, S.; Shadwick, L.; Schoch, C.L.; Smirnov, A.; Spiegel, F. W.

2012-01-01

Roč. 59, č. 5 (2012), s. 429-514 ISSN 1066-5234 Institutional support: RVO:60077344 Keywords : Algae * amoebae * biodiversity * ciliates * flagellates * fungi * parasites * protozoa * systematics * taxonomy Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.162, year: 2012 http://onlinelibrary.wiley.com/doi/10.1111/j.1550-7408.2012.00644.x/pdf

Nebela jiuhuensis nov. sp. (Amoebozoa; Arcellinida; Hyalospheniidae): A New Member of the Nebela saccifera - equicalceus - ansata Group Described from Sphagnum Peatlands in South-Central China.

Science.gov (United States)

Qin, Yangmin; Man, Baiying; Kosakyan, Anush; Lara, Enrique; Gu, Yansheng; Wang, Hongmei; Mitchell, Edward A D

2016-09-01

Hyalospheniids are among the most common and conspicuous testate amoebae in high-latitude peatlands and forest humus. These testate amoebae were widely studied as bioindicators and are increasingly used as models in microbial biogeography. However, data on their diversity and ecology are still very unevenly distributed geographically: notably, data are lacking for low-latitude peatlands. We describe here a new species, Nebela jiuhuensis, from peatlands near the Middle Yangtze River reach of south-central China with characteristic morphology. The test (shell) has hollow horn-like lateral extensions also found in N. saccifera, N. equicalceus (=N. hippocrepis), and N. ansata, three large species restricted mostly to Sphagnum peatlands of Eastern North America. Mitochondrial cytochrome oxidase (COI) data confirm that N. jiuhuensis is closely related to the morphologically very similar North American species N. saccifera and more distantly to N. ansata within the N. penardiana group. These species are all found in wet mosses growing in poor fens. Earlier reports of morphologically similar specimens found in South Korea peatlands suggest that N. jiuhuensis may be distributed in comparable peatlands in Eastern Asia (China and Korea). The discovery of such a conspicuous new species in Chinese peatlands suggests that many new testate amoebae species are yet to be discovered, including potential regional endemics. Furthermore, human activities (e.g., drainage, agriculture, and pollution) have reduced the known habitat of N. jiuhuensis, which can thus be considered as locally endangered. We, therefore, suggest that this very conspicuous micro-organism with a probably limited geographical distribution and specific habitat requirement should be considered as a flagship species for microbial biogeography as well as local environmental conservation and management. © 2016 The Author(s) Journal of Eukaryotic Microbiology © 2016 International Society of Protistologists.

Lack of Ecological and Life History Context Can Create the Illusion of Social Interactions in Dictyostelium discoideum.

Science.gov (United States)

Martínez-García, Ricardo; Tarnita, Corina E

2016-12-01

Studies of social microbes often focus on one fitness component (reproductive success within the social complex), with little information about or attention to other stages of the life cycle or the ecological context. This can lead to paradoxical results. The life cycle of the social amoeba Dictyostelium discoideum includes a multicellular stage in which not necessarily clonal amoebae aggregate upon starvation to form a possibly chimeric (genetically heterogeneous) fruiting body made of dead stalk cells and spores. The lab-measured reproductive skew in the spores of chimeras indicates strong social antagonism that should result in low genotypic diversity, which is inconsistent with observations from nature. Two studies have suggested that this inconsistency stems from the one-dimensional assessment of fitness (spore production) and that the solution lies in tradeoffs between multiple life-history traits, e.g.: spore size versus viability; and spore-formation (via aggregation) versus staying vegetative (as non-aggregated cells). We develop an ecologically-grounded, socially-neutral model (i.e. no social interactions between genotypes) for the life cycle of social amoebae in which we theoretically explore multiple non-social life-history traits, tradeoffs and tradeoff-implementing mechanisms. We find that spore production comes at the expense of time to complete aggregation, and, depending on the experimental setup, spore size and viability. Furthermore, experimental results regarding apparent social interactions within chimeric mixes can be qualitatively recapitulated under this neutral hypothesis, without needing to invoke social interactions. This allows for simple potential resolutions to the previously paradoxical results. We conclude that the complexities of life histories, including social behavior and multicellularity, can only be understood in the appropriate multidimensional ecological context, when considering all stages of the life cycle.

Půdní mikrofauna, krytenky (Protozoa: Testacea) a půdní hlístice (Nematoda), vybraných lokalit CHKO a BR Křivoklátsko

Czech Academy of Sciences Publication Activity Database

Háněl, Ladislav

2011-01-01

Roč. 31, - (2011), s. 209-214 ISSN 0231-5807 R&D Projects: GA ČR(CZ) GA206/93/0276; GA ČR(IO) GA526/06/1348 Institutional research plan: CEZ:AV0Z60660521 Keywords : Křivoklátsko Protected Landscape Area * deciduous forest * testate amoebae Subject RIV: EH - Ecology, Behaviour

Excitable signal relay in Dictyostelium discoideum

Science.gov (United States)

Mestler, Troy; Schwab, David; Mehta, Pankaj; Gregor, Thomas

2011-03-01

The social amoeba D. discoideum transitions when starved from a collection of individual cells into a multicellular spore-complex. During this process, amoebae display several interesting phenomena including intercellular signaling, pattern formation, and cell differentiation. At the heart of these phenomena is the exchange of the signaling molecule cyclic-AMP, which has previously been extensively studied using a variety of indirect methods. Here we employ a sensor that uses a compound fluorescent protein whose emission spectrum changes in the presence of bound cyclic AMP to directly monitor, in real time and in vivo, intracellular cAMP concentrations. We use cells expressing this sensor in microchemostats to study intracellular cAMP concentrations at the single-cell level in response to precise, dynamically-controlled external cAMP stimulation. Specifically, we show that these cells display excitability much like that found in neurons and agree experimentally quite well with a modified FitzHugh-Nagumo dynamical systems model. This single-cell model sets groundwork for a comprehensive multicellular model that promises to explain emergent behavior in D. discoideum.

Heterogeneity in the genus Allovahlkampfia and the description of the new genus Parafumarolamoeba (Vahlkampfiidae; Heterolobosea).

Science.gov (United States)

Geisen, Stefan; Bonkowski, Michael; Zhang, Junling; De Jonckheere, Johan F

2015-08-01

Heterolobosean amoebae are common and diverse members of soil protist communities. In this study, we isolated seven strains of amoebae from soil samples taken in Tibet (at high altitude), Sardinia and the Netherlands, all resembling to belong to a similar heterolobosean morphospecies. However, sequences of the small subunit (SSU) rDNA and internal transcribed spacers, including the 5.8S rDNA, revealed a high heterogeneity in the genus Allovahlkampfia to which six of the isolates belong. Some unnamed strains, of which the sequences had been published before, are also included within the genus Allovahlkampfia. One Allovahlkampfia isolated in the Netherlands harbors a twin-ribozyme, containing a His-Cys box, similar to the one found in strain BA of Allovahlkampfia. The other SSU rDNA sequence grouped in phylogenetic analyses with sequences obtained in environmental sequencing studies as sister to the genus Fumarolamoeba. This phylogenetic placement was supported by analyses of the 5.8S rDNA leading us to describe it as a new genus Parafumarolamoeba. Copyright © 2015 Elsevier GmbH. All rights reserved.

The TolC protein of Legionella pneumophila plays a major role in multi-drug resistance and the early steps of host invasion.

Directory of Open Access Journals (Sweden)

Mourad Ferhat

Full Text Available Pneumonia associated with Iegionnaires's disease is initiated in humans after inhalation of contaminated aerosols. In the environment, Legionella pneumophila is thought to survive and multiply as an intracellular parasite within free-living amoeba. In the genome of L. pneumophila Lens, we identified a unique gene, tolC, encoding a protein that is highly homologous to the outer membrane protein TolC of Escherichia coli. Deletion of tolC by allelic exchange in L. pneumophila caused increased sensitivity to various drugs. The complementation of the tolC mutation in trans restored drug resistance, indicating that TolC is involved in multi-drug efflux machinery. In addition, deletion of tolC caused a significant attenuation of virulence towards both amoebae and macrophages. Thus, the TolC protein appears to play a crucial role in virulence which could be mediated by its involvement in efflux pump mechanisms. These findings will be helpful in unraveling the pathogenic mechanisms of L. pneumophila as well as in developing new therapeutic agents affecting the efflux of toxic compounds.

Isolation and Genotyping of Acanthamoeba Strains from Environmental Sources in Ahvaz City, Khuzestan Province, Southern Iran

Science.gov (United States)

Rahdar, M; Niyyati, M; Salehi, M; Feghhi, M; Makvandi, M; Pourmehdi, M; Farnia, S

2012-01-01

Background Acanthamoeba spp. are free-living amoebae commonly found in the environmental sources such as water, soil, and air. This ubiquitous amoeba is the causative agent of amoebic keratitis (AK). The objective of the present study was to investigate the presence of Acanthamoeba spp. in water and soil sources in Ahvaz City, Khuzestan Province, southern Iran. Methods In general, 110 samples of water and soil were taken from different localities of Ahvaz including agricultural canals, rivers, and swimming pools. Filtration and cultivation were carried out on non-nutrient agar medium (NNA). Axenic cultivation was performed for all of positive isolates. PCR analysis was conducted on positive samples. Sequencing was done for 15 PCR products. Genotypes were identified by Blast search and homology analysis. Results Acanthamoeba spp. was found in 43 (71.6%) of samples of water and 13 (26%) soil samples. Genotyping of 15 samples proved that Acanthamoeba belonged to T4 (86.6%), T2 (6.6%), and T5 (6.6%) genotypes. Conclusion TYI-S-33 medium could be better than PYG medium for Acanthamoeba axenic culture. PMID:23323088

Integrated analysis of bacterial and microeukaryotic communities from differentially active mud volcanoes in the Gulf of Cadiz.

Science.gov (United States)

Coelho, Francisco J R C; Louvado, António; Domingues, Patrícia M; Cleary, Daniel F R; Ferreira, Marina; Almeida, Adelaide; Cunha, Marina R; Cunha, Ângela; Gomes, Newton C M

2016-10-20

The present study assesses the diversity and composition of sediment bacterial and microeukaryotic communities from deep-sea mud volcanoes (MVs) associated with strike-slip faults in the South-West Iberian Margin (SWIM). We used a 16S/18S rRNA gene based pyrosequencing approach to characterize and correlate the sediment bacterial and microeukaryotic communities from MVs with differing gas seep regimes and from an additional site with no apparent seeping activity. In general, our results showed significant compositional changes of bacterial and microeukaryotic communities in sampling sites with different seepage regimes. Sediment bacterial communities were enriched with Methylococcales (putative methanotrophs) but had lower abundances of Rhodospirillales, Nitrospirales and SAR202 in the more active MVs. Within microeukaryotic communities, members of the Lobosa (lobose amoebae) were enriched in more active MVs. We also showed a strong correlation between Methylococcales populations and lobose amoeba in active MVs. This study provides baseline information on the diversity and composition of bacterial and microeukaryotic communities in deep-sea MVs associated with strike-slip faults.

Graphical representation of transmutation and decay chain data, transmutation cross section and delayed gamma ray emission data

International Nuclear Information System (INIS)

Seki, Yasushi; Iida, Hiromasa; Kawasaki, Hiromitsu.

1982-09-01

In a D-T burning fusion reactor, the neutron induced activity severely limits personnel access to the reactor. Accurate evaluation of the induced activity and dose rate is necessary to conduct effective biological shield design. In order to evaluate the dose rate accurately, considerable amount of activation data is required. This report gives graphical representation of transmutation and decay chain data, transmutation cross section data and delayed gamma ray emission data for 116 nuclides of interest in terms of fusion reactor design. This graphical representation was made with hope of producing a reference for examining activation problems. It has already been shown to be effective in correcting inappropriate data. A computer code AMOEBA developed for the checking and plotting of the activation data is also described in this report. (author)

Occurrence and parameters of frequency of Legionella in warm water systems of hospitals and hotels in Lower Saxony.

Science.gov (United States)

Habicht, W; Müller, H E

1988-03-01

A total of 1241 water samples was investigated from 103 hospitals and 62 hotels in Lower Saxony 1985-87. 331 of 949 samples from hospitals and 26 of 292 samples from hotels were Legionella positive. All together 70% of the hospitals and 18% of the hotels investigated were Legionella positive, and 836 strains of Legionella were isolated (Table 1). As they could be diagnosed they belong to L. pneumophila SG1 306 strains, SG2 36 strains, SG3 127 strains, SG4 45 strain, SG5 29 strain, SG6 106 strains, SG9 13 strains and SG10 13 strains. Further 134 strains belonging to L. pneumophila but not to SG1-SG12 show cross reactions with serogroups 5, 8, and 10. Finally, 16 strains belong to L. dumoffii and 1 strain to L. anisa (Table 2). The following parameters of water samples were studied, too: temperature, pH value, conductivity, concentration of iron, of organic matter, of other bacteria, occurrence of amoebas, and the materials of water plumbing systems. Most samples contained concentrations of Legionella in the range of 10(1)-10(3) CFU/ml, highest concentrations were 10(5) CFU/ml (Fig. 1). Most frequently, Legionella were isolated within the range of temperature of 35-45 degrees C. However, a few of the water samples were positive for Legionella even up to 66 degrees C (Fig. 3). The conductivity has no and the pH value (Fig. 2) has only little influence on the occurrence of Legionella. There is a positive correlation between concentration of iron and frequency of Legionella (Fig. 4). Also organic matter (Fig. 6) and amoebas (Table 3) seem to enhance the occurrence of Legionella. Plumbing systems consisting of copper showed an inhibitory effect on Legionella during the first five years, whereas no effect could be detected in older systems (Fig. 5).

Inorganic Polyphosphate Is Essential for Salmonella Typhimurium Virulence and Survival in Dictyostelium discoideum

Directory of Open Access Journals (Sweden)

Macarena A. Varas

2018-01-01

Full Text Available Inorganic polyphosphate (polyP deficiency in enteric bacterial pathogens reduces their ability to invade and establish systemic infections in different hosts. For instance, inactivation of the polyP kinase gene (ppk encoding the enzyme responsible for polyP biosynthesis reduces invasiveness and intracellular survival of Salmonella enterica serovar Typhimurium (S. Typhimurium in epithelial cells and macrophages in vitro. In addition, the virulence in vivo of a S. Typhimurium Δppk mutant is significantly reduced in a murine infection model. In spite of these observations, the role played by polyP during the Salmonella-host interaction is not well understood. The social amoeba Dictyostelium discoideum has proven to be a useful model for studying relevant aspects of the host-pathogen interaction. In fact, many intracellular pathogens can survive within D. discoideum cells using molecular mechanisms also required to survive within macrophages. Recently, we established that S. Typhimurium is able to survive intracellularly in D. discoideum and identified relevant genes linked to virulence that are crucial for this process. The aim of this study was to determine the effect of a polyP deficiency in S. Typhimurium during its interaction with D. discoideum. To do this, we evaluated the intracellular survival of wild-type and Δppk strains of S. Typhimurium in D. discoideum and the ability of these strains to delay the social development of the amoeba. In contrast to the wild-type strain, the Δppk mutant was unable to survive intracellularly in D. discoideum and enabled the social development of the amoeba. Both phenotypes were complemented using a plasmid carrying a copy of the ppk gene. Next, we simultaneously evaluated the proteomic response of both S. Typhimurium and D. discoideum during host-pathogen interaction via global proteomic profiling. The analysis of our results allowed the identification of novel molecular signatures that give insight into

Eukaryotic cell flattening

Science.gov (United States)

Bae, Albert; Westendorf, Christian; Erlenkamper, Christoph; Galland, Edouard; Franck, Carl; Bodenschatz, Eberhard; Beta, Carsten

2010-03-01

Eukaryotic cell flattening is valuable for improving microscopic observations, ranging from bright field to total internal reflection fluorescence microscopy. In this talk, we will discuss traditional overlay techniques, and more modern, microfluidic based flattening, which provides a greater level of control. We demonstrate these techniques on the social amoebae Dictyostelium discoideum, comparing the advantages and disadvantages of each method.

Human pigmentation: A side effect adapted from a primitive organism′s survival, acting through cell attachment with an affinity for the keratinocyte and for elastin: Part I

Directory of Open Access Journals (Sweden)

Sanju Arianayagam

2014-01-01

Full Text Available Pigmentation featured millions of years ago and perhaps began with an amoeba frightening off a predator with some agent such as dopamine to prevent its attachment for phagocytosis by an enemy. This paper suggests that the environmental forces of grip and stick deserve greater emphasis and that mechanical forces involved in grip and stick or release from attachment, all point to control of proteases underlying pigmentation. There is an affinity for elastin as a pathway for melanin to exit its peripheral location in the epidermis into lymphatics and play a humeral role in defense mechanisms. The hair follicle follows the epidermal-dermal pattern of behavior with an affinity for elastin, a controlling function of melanin and through the bulge, an influence of mechanical forces and control by protease inhibitors.

Didymium-like myxogastrids (class Mycetozoa) as endocommensals of sea urchins (Sphaerechinus granularis)

Czech Academy of Sciences Publication Activity Database

Dyková, Iva; Lom, Jiří; Dvořáková, Helena; Pecková, Hana; Fiala, Ivan

2007-01-01

Roč. 54, č. 1 (2007), s. 1-12 ISSN 0015-5683 R&D Projects: GA ČR GA206/05/2384; GA MŠk LC522 Institutional research plan: CEZ:AV0Z60220518 Keywords : Didymium-like myxogastrids * Myxogastrea * sea - urchin amoeba strains * SSU rDNA * flagellar apparatus * phylogeny Subject RIV: EA - Cell Biology Impact factor: 1.000, year: 2007

New data on aetiology of nodular gill disease in rainbow trout, Oncorhynchus mykiss

Czech Academy of Sciences Publication Activity Database

Dyková, Iva; Kostka, Martin; Wortberg, F.; Nardy, E.; Pecková, Hana

2010-01-01

Roč. 57, č. 3 (2010), s. 157-163 ISSN 0015-5683 R&D Projects: GA ČR GA524/09/0137; GA MŠk LC522 Institutional research plan: CEZ:AV0Z60220518 Keywords : nodular gill disease * aetiological study * amoebae * Naegleria sp. * fish diseases * aquaculture * Oncorhynchus mykiss Subject RIV: GJ - Animal Vermins ; Diseases, Veterinary Medicine Impact factor: 1.533, year: 2010

Interactions of Bacteria and Amoebae with Ocular Biomaterials

OpenAIRE

John, Thomas

1991-01-01

The use of biomaterials in periocular and intraocular sites has resulted in some ocular inflammations and infections which can result in vision-threatening ocular disease. This review addresses bacterial interactions with, and adherence to ocular biomaterials such as soft contact lenses, surgical suture materials, and intraocular lenses. In addition, adherence of Acanthamoeba to soft contact lenses is described, and the role of these lenses in the development of Acanthamoeba keratitis is disc...

Role of interferon in resistance and immunity to protozoa

Science.gov (United States)

Sonnenfeld, G.; Degee, A. L. W.; Mansfield, J. M.; Newsome, A. L.; Arnold, R. R.

1985-01-01

Production of interferon (I) in response to protozoan infection, and the interferon-mediated inhibition of parasite replication were studied in order to determine if these effects may be related to immunologic-mediated resistance of the hosts. Two extracellular parasites-Trypanosoma brucei rhodesiense and Naegleria fowlei were used. Upon infection with the trypanosome, only resistant strains of mice produced I. An early peak of alpha/beta I is followed by appearance of gamma I, which coincided with antibody production and a drop in parasitemia. In case of the amoeba, pretreatment of its suspension with alpha/beta I inhibits its replication in vitro, and appears to protect mice from the infection and the disease. It is proposed that production of interferon, with its regulatory effect on the immune responses, may play a major role in regulating the processes of protozoan-caused diseases.

Effect of ionizing and non ionizing radiation on Protozoan and Parasites Ova causing gastroenteritis presents in sewage sludge wastes

International Nuclear Information System (INIS)

Shamma, M.; Al-Adawi, M.A.; Sharabi, N.

2005-06-01

The efficacy of Adra wastewater treatment plant for removing of parasitic eggs and other pathogens was various as the results of this work showed many eggs detected on and numeration referenced methods were applied for liquid and dried sledges. Helminths eggs viability was determined by aid of methods and techniques which depend on the morphological parameters, studying the motility incubation and applying the vital staining. The protozoa viability was studied by using vital staining, but applying culture techniques on specific composed media did not give any results. The disinfection results for ascaris eggs, protozoa and amoeba oocysts irradiated by 6 KGy of gamma (Co 6 0) which was sufficient to kill all types of such parasites. In conflict the UV radiation was able to motivate the division of the ascaris eggs embryo nations. Also, the viability of the Giardia and Entamoeba oocysts not affected. Therefor the UV technique couldn't be the alternative technology of ionizing radiation. (author)

Form follows function: ultrastructure of different morphotypes of Physarum polycephalum

Science.gov (United States)

Oettmeier, Christina; Lee, Jonghyun; Döbereiner, Hans-Günther

2018-04-01

The multinucleate, unicellular slime mold Physarum polycephalum is a highly motile and morphologically diverse giant amoeba. Despite being brainless and lacking neurons, it exhibits ‘smart’ behavior. There is considerable interest in describing such traits and to investigate the underlying mechanochemical patterns which may hint at universal principles of behavior and decision-making. Furthermore, the slime mold’s mechanism of locomotion is unique. It resembles amoeboid movement, but differs from the locomotion of other amoebae in many ways, e.g. in their much larger size and lack of lobopodia. These two aspects, behavior and locomotion, are linked by the cytoskeleton and the overall morphology of P. polycephalum. In this paper, we present a structural analysis of different growth forms (micro-, meso- and macroplasmodia) by transmission electron microscopy (TEM), scanning electron microscopy (SEM), light microscopy, and fluorescence microscopy of F-actin. With these detailed investigations of cellular ultrastructure and morphology, we provide the basis for the analysis of, e.g. viscoelastic and rheological measurements. Our data also provide structural details for the many models that have been constructed for the understanding of locomotion. We conclude that morphological information is vital for the assessment and measurement of material properties.

Detection limits of Legionella pneumophila in environmental samples after co-culture with Acanthamoeba polyphaga

Science.gov (United States)

2013-01-01

Background The efficiency of recovery and the detection limit of Legionella after co-culture with Acanthamoeba polyphaga are not known and so far no investigations have been carried out to determine the efficiency of the recovery of Legionella spp. by co-culture and compare it with that of conventional culturing methods. This study aimed to assess the detection limits of co-culture compared to culture for Legionella pneumophila in compost and air samples. Compost and air samples were spiked with known concentrations of L. pneumophila. Direct culturing and co-culture with amoebae were used in parallel to isolate L. pneumophila and recovery standard curves for both methods were produced for each sample. Results The co-culture proved to be more sensitive than the reference method, detecting 102-103 L. pneumophila cells in 1 g of spiked compost or 1 m3 of spiked air, as compared to 105-106 cells in 1 g of spiked compost and 1 m3 of spiked air. Conclusions Co-culture with amoebae is a useful, sensitive and reliable technique to enrich L. pneumophila in environmental samples that contain only low amounts of bacterial cells. PMID:23442526

Fatal primary amoebic meningoencephalitis in a Norwegian tourist returning from Thailand.

Science.gov (United States)

Stubhaug, Tore Taksdal; Reiakvam, Olaug Marie; Stensvold, Christen Rune; Hermansen, Nils Olav; Holberg-Petersen, Mona; Antal, Ellen-Ann; Gaustad, Knut; Førde, Ingrid Schage; Heger, Bernt

2016-06-01

Primary amoebic meningoencephalitis (PAM) is a rare disease caused by the free-living amoeba Naegleria fowleri . Infection occurs by insufflation of water containing amoebae into the nasal cavity, and is usually associated with bathing in freshwater. Nasal irrigation is a more rarely reported route of infection. A fatal case of PAM in a previously healthy Norwegian woman, acquired during a holiday trip to Thailand, is described. Clinical findings were consistent with rapidly progressing meningoencephalitis. The cause of infection was discovered by chance, owing to the unexpected detection of N. fowleri DNA by a PCR assay targeting fungi. A conclusive diagnosis was established based on sequencing of N. fowleri DNA from brain biopsies, supported by histopathological findings. Nasal irrigation using contaminated tap water is suspected as the source of infection. The clinical presentation of PAM is very similar to severe bacterial meningitis. This case is a reminder that when standard investigations fail to identify a cause of infection in severe meningoencephalitis, it is of crucial importance to continue a broad search for a conclusive diagnosis. PAM should be considered as a diagnosis in patients with symptoms of severe meningoencephalitis returning from endemic areas.

Elimination of Naegleria fowleri from bulk water and biofilm in an operational drinking water distribution system.

Science.gov (United States)

Miller, Haylea C; Morgan, Matthew J; Wylie, Jason T; Kaksonen, Anna H; Sutton, David; Braun, Kalan; Puzon, Geoffrey J

2017-03-01

Global incidence of primary amoebic meningoencephalitis cases associated with domestic drinking water is increasing. The need for understanding disinfectant regimes capable of eliminating the causative microorganism, Naegleria fowleri, from bulk water and pipe wall biofilms is critical. This field study demonstrated the successful elimination of N. fowleri from the bulk water and pipe wall biofilm of a persistently colonised operational drinking water distribution system (DWDS), and the prevention of further re-colonisation. A new chlorination unit was installed along the pipe line to boost the free chlorine residual to combat the persistence of N. fowleri. Biofilm and bulk water were monitored prior to and after re-chlorination (RCl), pre-rechlorination (pre-RCl) and post-rechlorination (post-RCl), respectively, for one year. A constant free chlorine concentration of > 1 mg/L resulted in the elimination of N. fowleri from both the bulk water and biofilm at the post-RCl site. Other amoeba species were detected during the first two months of chlorination, but all amoebae were eliminated from both the bulk water and biofilm at post-RCl after 60 days of chlorination with free chlorine concentrations > 1 mg/L. In addition, a dynamic change in the biofilm community composition and a four log reduction in biofilm cell density occurred post-RCl. The pre-RCl site continued to be seasonally colonised by N. fowleri, but the constant free chlorine residual of > 1 mg/L prevented N. fowleri from recolonising the bulk and pipe wall biofilm at the post-RCl site. To our knowledge, this is the first study to demonstrate successful removal of N. fowleri from both the bulk and pipe wall biofilm and prevention of re-colonisation of N. fowleri in an operational DWDS. The findings of this study are of importance to water utilities in addressing the presence of N. fowleri and other amoeba in susceptible DWDSs. Copyright © 2016 Elsevier Ltd. All rights reserved.

Photochemotherapeutic Strategy against Acanthamoeba Infections

Science.gov (United States)

Aqeel, Yousuf; Siddiqui, Ruqaiyyah; Anwar, Ayaz; Shah, Muhammad Raza; Khoja, Shahrukh

2015-01-01

Acanthamoeba is a protist pathogen that can cause serious human infections, including blinding keratitis and a granulomatous amoebic encephalitis that almost always results in death. The current treatment for these infections includes a mixture of drugs, and even then, a recurrence can occur. Photochemotherapy has shown promise in the treatment of Acanthamoeba infections; however, the selective targeting of pathogenic Acanthamoeba has remained a major concern. The mannose-binding protein is an important adhesin expressed on the surface membranes of pathogenic Acanthamoeba organisms. To specifically target Acanthamoeba, the overall aim of this study was to synthesize a photosensitizing compound (porphyrin) conjugated with mannose and test its efficacy in vitro. The synthesis of mannose-conjugated porphyrin was achieved by mixing benzaldehyde and pyrrole, yielding tetraphenylporphyrin. Tetraphenylporphyrin was then converted into mono-nitrophenylporphyrin by selectively nitrating the para position of the phenyl rings, as confirmed by nuclear magnetic resonance (NMR) spectroscopy. The mono-nitrophenylporphyrin was reduced to mono-aminophenylporphyrin in the presence of tin dichloride and confirmed by a peak at m/z 629. Finally, mono-aminoporphyrin was conjugated with mannose, resulting in the formation of an imine bond. Mannose-conjugated porphyrin was confirmed through spectroscopic analysis and showed that it absorbed light of wavelengths ranging from 425 to 475 nm. To determine the antiacanthamoebic effects of the derived product, amoebae were incubated with mannose-conjugated porphyrin for 1 h and washed 3 times to remove extracellular compound. Next, the amoebae were exposed to light of the appropriate wavelength for 1 h. The results revealed that mannose-conjugated porphyrin produced potent trophicidal effects and blocked excystation. In contrast, Acanthamoeba castellanii incubated with mannose alone and porphyrin alone did not exhibit an antiamoebic effect

The Amoebal MAP Kinase Response to Legionella pneumophila Is Regulated by DupA

OpenAIRE

Li, Zhiru; Dugan, Aisling S.; Bloomfield, Gareth; Skelton, Jason; Ivens, Alasdair; Losick, Vicki; Isberg, Ralph R.

2009-01-01

The amoeba Dictyostelium discoideum can support replication of Legionella pneumophila. Here we identify the dupA gene, encoding a putative tyrosine kinase/dual-specificity phosphatase, in a screen for D. discoideum mutants altered in allowing L. pneumophila intracellular replication. Inactivation of dupA resulted in depressed L. pneumophila growth and sustained hyperphosphorylation of the amoebal MAP kinase ERK1, consistent with loss of a phosphatase activity. Bacterial challenge of wild-type...

Involvement of Sib Proteins in the Regulation of Cellular Adhesion in Dictyostelium discoideum▿ †

OpenAIRE

Cornillon, Sophie; Froquet, Romain; Cosson, Pierre

2008-01-01

Molecular mechanisms ensuring cellular adhesion have been studied in detail in Dictyostelium amoebae, but little is known about the regulation of cellular adhesion in these cells. Here, we show that cellular adhesion is regulated in Dictyostelium, notably by the concentration of a cellular secreted factor accumulating in the medium. This constitutes a quorum-sensing mechanism allowing coordinated regulation of cellular adhesion in a Dictyostelium population. In order to understand the mechani...

Potential role of bacteria packaging by protozoa in the persistence and transmission of pathogenic bacteria

OpenAIRE

Denoncourt, Alix M.; Paquet, Valérie E.; Charette, Steve J.

2014-01-01

Many pathogenic bacteria live in close association with protozoa. These unicellular eukaryotic microorganisms are ubiquitous in various environments. A number of protozoa such as amoebae and ciliates ingest pathogenic bacteria, package them usually in membrane structures, and then release them into the environment. Packaged bacteria are more resistant to various stresses and are more apt to survive than free bacteria. New evidence indicates that protozoa and not bacteria control the packaging...

Polarizable protein packing

KAUST Repository

Ng, Albert H.

2011-01-24

To incorporate protein polarization effects within a protein combinatorial optimization framework, we decompose the polarizable force field AMOEBA into low order terms. Including terms up to the third-order provides a fair approximation to the full energy while maintaining tractability. We represent the polarizable packing problem for protein G as a hypergraph and solve for optimal rotamers with the FASTER combinatorial optimization algorithm. These approximate energy models can be improved to high accuracy [root mean square deviation (rmsd) < 1 kJ mol -1] via ridge regression. The resulting trained approximations are used to efficiently identify new, low-energy solutions. The approach is general and should allow combinatorial optimization of other many-body problems. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011 Copyright © 2011 Wiley Periodicals, Inc.

Morphology, antigenicity, and nucleic acid content of the Bacteroides sp. used in the culture of Entamoeba histolytica.

Science.gov (United States)

Albach, R A; Shaffer, J G; Watson, R H

1965-10-01

Albach, Richard A. (Lutheran General Hospital, Park Ridge, Ill.), James G. Shaffer, and Robert H. Watson. Morphology, antigenicity, and nucleic acid content of the Bacteroides sp. used in the culture of Entamoeba histolytica. J. Bacteriol. 90:1045-1053. 1965.-Certain changes in morphology, antigenicity, and nucleic acid content that occur in a culture of Bacteroides sp. in the presence of penicillin G in CLG medium are described. This "variant" is one of seven recovered in several laboratories, all of which are descendants of the original Bacteroides isolated by Shaffer and Frye. Penicillin-inhibited cells of this culture are currently being used in the routine propagation of Entamoeba histolytica in CLG medium. Evidence is presented for the loss of ability to react with antibody in these penicillin-inhibited bacteria in CLG medium, when studied by fluorescent-antibody techniques. The implications of the antigenic changes observed as they pertain to similar antigenic studies of the amoebas are discussed. A pronounced reduction in the ribonucleic acid (RNA) content of such penicillin-inhibited cells was also observed. The potential importance of the changes that occur in the RNA of these cells with respect to considerations of the growth requirements of the amoebas is also discussed.

Molecular characterization of Acanthamoeba strains isolated from domestic dogs in Tenerife, Canary Islands, Spain.

Science.gov (United States)

Valladares, María; Reyes-Batlle, María; Martín-Navarro, Carmen M; López-Arencibia, Atteneri; Dorta-Gorrín, Alexis; Wagner, Carolina; Martínez-Carretero, Enrique; Piñero, José E; Valladares, Basilio; Lorenzo-Morales, Jacob

2015-06-01

The present study describes two cases of Acanthamoeba infections (keratitis and ascites/peritonitis) in small breed domestic dogs in Tenerife, Canary Islands, Spain. In both cases, amoebic trophozoites were observed under the inverted microscope and isolated from the infected tissues and/or fluids, without detecting the presence of other viral, fungal or bacterial pathogens. Amoebae were isolated using 2 % non-nutrient agar plates and axenified for further biochemical and molecular analyses. Osmotolerance and thermotolerance assays revealed that both isolates were able to grow up to 37 °C and 1 M of mannitol and were thus considered as potentially pathogenic. Moreover, the strains were classified as highly cytotoxic as they cause more than 75 % of toxicity when incubated with two eukaryotic cell lines. In order to classify the strains at the molecular level, the diagnostic fragment 3 (DF3) region of the 18S rDNA of Acanthamoeba was amplified and sequenced, revealing that both isolates belonged to genotype T4. In both cases, owners of the animals did not allow any further studies or follow-up and therefore the current status of these animals is unknown. Furthermore, the isolation of these pathogenic amoebae should raise awareness with the veterinary community locally and worldwide.

Fate of Entamoeba histolytica during establishment of amoebic liver abscess analyzed by quantitative radioimaging and histology.

Science.gov (United States)

Rigothier, Marie-Christine; Khun, Hout; Tavares, Paulo; Cardona, Ana; Huerre, Michel; Guillén, Nancy

2002-06-01

The protozoan parasite Entamoeba histolytica is the causative agent of amoebiasis, a human disease characterized by dysentery and liver abscess. The physiopathology of hepatic lesions can be satisfactorily reproduced in the hamster animal model by the administration of trophozoites through the portal vein route. Hamsters were infected with radioactively labeled amoebas for analysis of liver abscess establishment and progression. The radioimaging of material from parasite origin and quantification of the number inflammation foci, with or without amoebas, described here provides the first detailed assessment of trophozoite survival and death during liver infection by E. histolytica. The massive death of trophozoites observed in the first hours postinfection correlates with the presence of a majority of inflammatory foci without parasites. A critical point for success of infection is reached after 12 h when the lowest number of trophozoites is observed. The process then enters a commitment phase during which parasites multiply and the size of the infection foci increases fast. The liver shows extensive areas of dead hepatocytes that are surrounded by a peripheral layer of parasites facing inflammatory cells leading to acute inflammation. Our results show that the host response promotes massive parasite death but also suggest also that this is a major contributor to the establishment of inflammation during development of liver abscess.

Morphometric and genetic analysis of Arcella intermedia and Arcella intermedia laevis (Amoebozoa, Arcellinida) illuminate phenotypic plasticity in microbial eukaryotes.

Science.gov (United States)

Porfírio-Sousa, Alfredo L; Ribeiro, Giulia M; Lahr, Daniel J G

2017-04-01

Testate amoebae are eukaryotic microorganisms characterized by the presence of an external shell (test). The shell morphology is used as a diagnostic character, but discordance between morphological and molecular data has been demonstrated in groups of arcellinids (Amoebozoa), one of the principal groups of testate amoebae. Morphology of the test is supposed to differentiate genera and species and it is applied in ecological, monitoring and paleontological studies. However, if phenotype does not reflect genotype, conclusions in these types of studies become severely impaired. The objective of this work is to evaluate the morphometrical and morphological variation of the closely related and morphologically similar taxa Arcella intermedia laevis Tsyganov and Mazei, 2006 and Arcella intermedia (Deflandre 1928) Tsyganov and Mazei, 2006 in nature and in cultured individuals and see how these are correlated with molecular data. Our results demonstrate that phenotypic plasticity in Arcella intermedia make morphological distinctions impossible in both taxa. Arcella intermedia and Arcella intermedia laevis are molecularly identical for SSU rDNA and a mitochondrial molecular marker (NAD9/7). We conclude that morphological techniques alone cannot identify phenotypic plasticity from natural populations. More work is clearly needed to better understand the morphological, morphometric and molecular variability in these organisms. Copyright © 2016 Elsevier GmbH. All rights reserved.

Three-dimensional simulation of pseudopod-driven swimming of amoeboid cells

Science.gov (United States)

Campbell, Eric; Bagchi, Prosenjit

2016-11-01

Pseudopod-driven locomotion is common in eukaryotic cells, such as amoeba, neutrophils, and cancer cells. Pseudopods are protrusions of the cell body that grow, bifurcate, and retract. Due to the dynamic nature of pseudopods, the shape of a motile cell constantly changes. The actin-myosin protein dynamics is a likely mechanism for pseudopod growth. Existing theoretical models often focus on the acto-myosin dynamics, and not the whole cell shape dynamics. Here we present a full 3D simulation of pseudopod-driven motility by coupling a surface-bound reaction-diffusion (RD) model for the acto-myosin dynamics, a continuum model for the cell membrane deformation, and flow of the cytoplasmic and extracellular fluids. The whole cell is represented as a viscous fluid surrounded by a membrane. A finite-element method is used to solve the membrane deformation, and the RD model on the deforming membrane, while a finite-difference/spectral method is used to solve the flow fields inside and outside the cell. The fluid flow and cell deformation are coupled by the immersed-boundary method. The model predicts pseudopod growth, bifurcation, and retraction as observed for a swimming amoeba. The work provides insights on the role of membrane stiffness and cytoplasmic viscosity on amoeboid swimming. Funded by NSF CBET 1438255.

The prevalence of protozoa in the gut of German cockroaches (Blattella germanica) with special reference to Lophomonas blattarum.

Science.gov (United States)

Martínez-Girón, Rafael; Martínez-Torre, Cristina; van Woerden, Hugo Cornelis

2017-11-01

The German cockroach (Blattella germanica) is a common domestic pest, which produces allergens that have been associated with broncho-pulmonary disease. Various protozoan species have been identified in the intestine of this cockroach and it has been hypothesised that these protozoa, or their proteases, may contribute to the burden of cockroach-associated allergens and adjuvants present in domestic dust. The aim of this study was therefore to determine the prevalence of protozoan species in the intestine of Blattella germanica. German cockroaches were anesthetised and dissected and gut contents are used to produce wet slides for microscopy. Both, Giemsa and Papanicolaou stains were used to confirm correct identification of Lophomonas blattarum. Representatives of four genera of protozoa were identified in 110 cockroaches: Nyctoterus sp. was observed in 91.8% of cases, Gregarina sp. in 64.5%, Amoeba sp. in 25.4% and Lophomonas blattarum in 13.6%. Nyctoterus and Gregarina were statistically significantly more likely to be found in diseased cockroaches compared to Amoeba or Lophomonas. The prevalence of Lophomonas blattarum was similar to that in published studies of a different species of cockroach, Periplaneta americana. Further work is needed to assess the interplay between protozoa, cockroaches and broncho-pulmonary diseases.

Disseminated Acanthamoeba Infection Presenting With Cutaneous Lesions in an Immunocompromised Patient: A Case Report, Review of Histomorphologic Findings, and Potential Diagnostic Pitfalls.

Science.gov (United States)

Morrison, Annie O; Morris, Robert; Shannon, Amie; Lauer, Scott R; Guarner, Jeannette; Kraft, Colleen S

2016-02-01

Free-living amoebas are exceedingly rare causes of cutaneous infections and present unique diagnostic and therapeutic challenges. We describe a case of disseminated acanthamoebiasis with cutaneous manifestations and summarize additional diagnostic, prognostic, and therapeutic highlights. A 58-year-old man with relapsed chronic lymphocytic leukemia had several weeks of progressive, painful ulcerations on the forehead, arms, abdomen, and thighs. A biopsy was performed for histopathologic evaluation. The biopsy specimen showed inflammatory infiltrate with abscess formation involving the epidermis, dermis, and subcutis. Scattered cells showed nuclei with a prominent central karyosome, dispersed chromatin, and either abundant foamy basophilic cytoplasm or two well-demarcated cytoplasmic walls. Acanthamoeba species was confirmed by polymerase chain reaction from the formalin-fixed, paraffin-embedded tissue. Cutaneous lesions from acanthamoebiasis are exceptionally rare but should be included in the differential diagnosis of necrotic cutaneous lesions in immunocompromised patients. Although infrequently encountered, pathologists need to be aware of the morphologic features of free-living amoebas. Immunohistochemical and molecular studies can confirm the diagnosis. Multiagent treatment regimens, when initiated empirically, have been more successful than single-agent regimens, but infections involving the central nervous system are almost universally fatal. © American Society for Clinical Pathology, 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Evaluating Different Virulence Traits of Klebsiella pneumoniae Using Dictyostelium discoideum and Zebrafish Larvae as Host Models

Directory of Open Access Journals (Sweden)

Andrés E. Marcoleta

2018-02-01

Full Text Available Multiresistant and invasive hypervirulent Klebsiella pneumoniae strains have become one of the most urgent bacterial pathogen threats. Recent analyses revealed a high genomic plasticity of this species, harboring a variety of mobile genetic elements associated with virulent strains, encoding proteins of unknown function whose possible role in pathogenesis have not been addressed. K. pneumoniae virulence has been studied mainly in animal models such as mice and pigs, however, practical, financial, ethical and methodological issues limit the use of mammal hosts. Consequently, the development of simple and cost-effective experimental approaches with alternative host models is needed. In this work we described the use of both, the social amoeba and professional phagocyte Dictyostelium discoideum and the fish Danio rerio (zebrafish as surrogate host models to study K. pneumoniae virulence. We compared three K. pneumoniae clinical isolates evaluating their resistance to phagocytosis, intracellular survival, lethality, intestinal colonization, and innate immune cells recruitment. Optical transparency of both host models permitted studying the infective process in vivo, following the Klebsiella-host interactions through live-cell imaging. We demonstrated that K. pneumoniae RYC492, but not the multiresistant strains 700603 and BAA-1705, is virulent to both host models and elicits a strong immune response. Moreover, this strain showed a high resistance to phagocytosis by D. discoideum, an increased ability to form biofilms and a more prominent and irregular capsule. Besides, the strain 700603 showed the unique ability to replicate inside amoeba cells. Genomic comparison of the K. pneumoniae strains showed that the RYC492 strain has a higher overall content of virulence factors although no specific genes could be linked to its phagocytosis resistance, nor to the intracellular survival observed for the 700603 strain. Our results indicate that both zebrafish

Si cycling in a forest biogeosystem - the importance of transient state biogenic Si pools

Science.gov (United States)

Sommer, M.; Jochheim, H.; Höhn, A.; Breuer, J.; Zagorski, Z.; Busse, J.; Barkusky, D.; Meier, K.; Puppe, D.; Wanner, M.; Kaczorek, D.

2013-07-01

The relevance of biological Si cycling for dissolved silica (DSi) export from terrestrial biogeosystems is still in debate. Even in systems showing a high content of weatherable minerals, like Cambisols on volcanic tuff, biogenic Si (BSi) might contribute > 50% to DSi (Gerard et al., 2008). However, the number of biogeosystem studies is rather limited for generalized conclusions. To cover one end of controlling factors on DSi, i.e., weatherable minerals content, we studied a forested site with absolute quartz dominance (> 95%). Here we hypothesise minimal effects of chemical weathering of silicates on DSi. During a four year observation period (05/2007-04/2011), we quantified (i) internal and external Si fluxes of a temperate-humid biogeosystem (beech, 120 yr) by BIOME-BGC (version ZALF), (ii) related Si budgets, and (iii) Si pools in soil and beech, chemically as well as by SEM-EDX. For the first time two compartments of biogenic Si in soils were analysed, i.e., phytogenic and zoogenic Si pool (testate amoebae). We quantified an average Si plant uptake of 35 kg Si ha-1 yr-1 - most of which is recycled to the soil by litterfall - and calculated an annual biosilicification from idiosomic testate amoebae of 17 kg Si ha-1. The comparatively high DSi concentrations (6 mg L-1) and DSi exports (12 kg Si ha-1 yr-1) could not be explained by chemical weathering of feldspars or quartz dissolution. Instead, dissolution of a relictic, phytogenic Si pool seems to be the main process for the DSi observed. We identified canopy closure accompanied by a disappearance of grasses as well as the selective extraction of pine trees 30 yr ago as the most probable control for the phenomena observed. From our results we concluded the biogeosystem to be in a transient state in terms of Si cycling.

Si cycling in a forest biogeosystem – the importance of transient state biogenic Si pools

Directory of Open Access Journals (Sweden)

M. Sommer

2013-07-01

Full Text Available The relevance of biological Si cycling for dissolved silica (DSi export from terrestrial biogeosystems is still in debate. Even in systems showing a high content of weatherable minerals, like Cambisols on volcanic tuff, biogenic Si (BSi might contribute > 50% to DSi (Gerard et al., 2008. However, the number of biogeosystem studies is rather limited for generalized conclusions. To cover one end of controlling factors on DSi, i.e., weatherable minerals content, we studied a forested site with absolute quartz dominance (> 95%. Here we hypothesise minimal effects of chemical weathering of silicates on DSi. During a four year observation period (05/2007–04/2011, we quantified (i internal and external Si fluxes of a temperate-humid biogeosystem (beech, 120 yr by BIOME-BGC (version ZALF, (ii related Si budgets, and (iii Si pools in soil and beech, chemically as well as by SEM-EDX. For the first time two compartments of biogenic Si in soils were analysed, i.e., phytogenic and zoogenic Si pool (testate amoebae. We quantified an average Si plant uptake of 35 kg Si ha−1 yr−1 – most of which is recycled to the soil by litterfall – and calculated an annual biosilicification from idiosomic testate amoebae of 17 kg Si ha−1. The comparatively high DSi concentrations (6 mg L−1 and DSi exports (12 kg Si ha−1 yr−1 could not be explained by chemical weathering of feldspars or quartz dissolution. Instead, dissolution of a relictic, phytogenic Si pool seems to be the main process for the DSi observed. We identified canopy closure accompanied by a disappearance of grasses as well as the selective extraction of pine trees 30 yr ago as the most probable control for the phenomena observed. From our results we concluded the biogeosystem to be in a transient state in terms of Si cycling.

Si cycling in a forest biogeosystem - the importance of anthropogenic perturbation and induced transient state of biogenic Si pools

Science.gov (United States)

Sommer, M.; Jochheim, H.; Höhn, A.; Breuer, J.; Zagorski, Z.; Busse, J.; Barkusky, D.; Puppe, D.; Wanner, M.; Kaczorek, D.

2012-12-01

The relevance of biological Si cycling for dissolved silica (DSi) export from terrestrial biogeosystems is still in debate. Even in systems showing a high content of weatherable minerals, like Cambisols on volcanic tuff, biogenic Si (BSi) might contribute > 50% to total DSi (Gerard et~al., 2008). However, the actual number of biogeosystem studies is rather limited for generalised conclusions. To cover one end of controlling factors on DSi - weatherable minerals content - we studied a~forested site with absolute quartz dominance (> 95%). Hence, we hypothesise minimal effects of chemical weathering of silicates on DSi. During a~four year observation period (May 2007-April 2011) we quantified (i) internal and external Si fluxes of a temperate-humid biogeosystem (beech, 120 yr) by BIOME-BGC (vers. ZALF), (ii) related Si budgets, and, (iii) Si pools in soil and beech, chemically as well as by SEM-EDX. For the first time both compartments of biogenic Si in soils were analysed, i.e. phytogenic and zoogenic Si pool (testate amoebae). We quantified an average Si plant uptake of 35 kg Si ha-1 yr-1 - most of which is recycled to the soil by litterfall - and calculated an annual biosilicification from idiosomic testate amoebae of 17 kg Si ha-1. High DSi concentrations (6 mg l-1) and DSi exports (12 kg Si ha-1 yr-1) could not be explained by chemical weathering of feldspars or quartz dissolution. Instead, dissolution of a relictic phytolith Si pool seems to be the main process for the DSi observed. We identified forest management, i.e. selective extraction of pine trees 20 yr ago followed by a disappearance of grasses, as the most probable control for the phenomena observed and hypothesised the biogeosystem to be in a transient state in terms of Si cycling.

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...

Ecological paradigm of legionella: a revision. New strategy and its implication in public health Revisión del paradigma ecológico de la 'legionella'. Estrategia ecológica y su implicación en salud pública

Directory of Open Access Journals (Sweden)

José Bernardo Ferrer Simó

2008-12-01

Full Text Available Some aspects difficultly explained by the ecological model described by Rowbothan in 1980, as the abnormally low infectious dose, the long distances in which bacteria remains viable in the aerosol, the difficulty of growth in the standard culture media, the low efficiency of the antilegionela disinfectants, in the control of the outbreaks, the reinfection or the absence of 'person to person' transmission, are analyzed from an ecological microbiology standpoint. Focused on the bacterium-protozoo relationship , several studies suggest that bacterial growth might take place in two functionally different phases or stages, according to the proportion or ratio bacterium-amoeba (MOI-multiplicity of infection. In the first phase of rapid growth, in which this relationship is substantially low, the entry of Legionella bacterium in the amoeba would originate a unique vacuole, which after amebian lyses, it would liberate free infectants forms for other amoebae. During the second stage, of dissemination or settling of other ecological niches, with high MOI ratios, several growth vesicles are produced inside the amoeba and are expelled without lyses. The deadlock of the amoeba in this phase, is produced after the massive liberation of the vesicles. Some authors suggest that these vesicles are the infectant nuclei of the legionelosis transmission because of his resistance and alive-legionela packing characteristics. The presence of a specific biofilm might be determinant in this process. Keeping in mind this amoeba-legionela relationship-interaction system, the preventive measures should go directed to supporting the MOI relation low, always in conjunction with low levels of biofilm. In this respect, the addition of in continue antilegionela disinfectants substances seems to be indispensable. Reached the phase of dissemination (only fits the cleanliness is the unique measure of action. The research on specific mechanisms of legionela-amoeba invasion would be

Pack hunting by a common soil amoeba on nematodes

NARCIS (Netherlands)

Geisen, Stefan; Rosengarten, J.; Koller, R.; Mulder, Christian; Urich, T.; Bonkowski, M.

2015-01-01

Soils host the most complex communities on Earth,
including the most diverse and abundant eukaryotes,
i.e. heterotrophic protists. Protists are generally con-
sidered as bacterivores, but evidence for negative
interactions with nematodes both from laboratory and
field studies

Free-living amoebae isolated in the Central African Republic ...

African Journals Online (AJOL)

Bathing sites and cerebrospinal fluid from patients died of bacterial meningitis untagged were explored by culture and PCR and the amplicons were sequenced which allowed to characterize the species found. Only species of the genus Tetramitus, namely T. Entericus, T. waccamawensis and T.sp similar to those already ...

Phylogeny and Systematics of Leptomyxid Amoebae (Amoebozoa, Tubulinea, Leptomyxida).

Science.gov (United States)

Smirnov, Alexey; Nassonova, Elena; Geisen, Stefan; Bonkowski, Michael; Kudryavtsev, Alexander; Berney, Cedric; Glotova, Anna; Bondarenko, Natalya; Dyková, Iva; Mrva, Martin; Fahrni, Jose; Pawlowski, Jan

2017-04-01

We describe four new species of Flabellula, Leptomyxa and Rhizamoeba and publish new SSU rRNA gene and actin gene sequences of leptomyxids. Using these data we provide the most comprehensive SSU phylogeny of leptomyxids to date. Based on the analyses of morphological data and results of the SSU rRNA gene phylogeny we suggest changes in the systematics of the order Leptomyxida (Amoebozoa: Lobosa: Tubulinea). We propose to merge the genera Flabellula and Paraflabellula (the genus Flabellula remains valid by priority rule). The genus Rhizamoeba is evidently polyphyletic in all phylogenetic trees; we suggest retaining the generic name Rhizamoeba for the group unifying R. saxonica, R.matisi n. sp. and R. polyura, the latter remains the type species of the genus Rhizamoeba. Based on molecular and morphological evidence we move all remaining Rhizamoeba species to the genus Leptomyxa. New family Rhizamoebidae is established here in order to avoid paraphyly of the family Leptomyxidae. With the suggested changes both molecular and morphological systems of the order Leptomyxida are now fully congruent to each other. Copyright © 2016 Elsevier GmbH. All rights reserved.

Solving inverse problems for biological models using the collage method for differential equations.

Science.gov (United States)

Capasso, V; Kunze, H E; La Torre, D; Vrscay, E R

2013-07-01

In the first part of this paper we show how inverse problems for differential equations can be solved using the so-called collage method. Inverse problems can be solved by minimizing the collage distance in an appropriate metric space. We then provide several numerical examples in mathematical biology. We consider applications of this approach to the following areas: population dynamics, mRNA and protein concentration, bacteria and amoeba cells interaction, tumor growth.

Intestinal Parasitic Infections in Bahir Dar and Risk Factors for Transmission

OpenAIRE

Erko, Berhanu; Medhin, Girmay; Birrie, Hailu

1995-01-01

A study of intestinal parasites and assessment of transmission factors were made in Bahir Dar town, northwestern Ethiopia. Out of 528 children examined by formolether concentration method over 95 % were found to harbour one or more intestinal parasites. Human behaviour and poor sanitary conditions appeared to be responsible for the transmission of geohelminths, faeco-orally transmitted amoebae and water-related schistosome parasites. Health education is suggested to play a vital role in the c...

Naringenin is a novel inhibitor of Dictyostelium cell proliferation and cell migration

International Nuclear Information System (INIS)

Russ, Misty; Martinez, Raquel; Ali, Hind; Steimle, Paul A.

2006-01-01

Naringenin is a flavanone compound that alters critical cellular processes such as cell multiplication, glucose uptake, and mitochondrial activity. In this study, we used the social amoeba, Dictyostelium discoideum, as a model system for examining the cellular processes and signaling pathways affected by naringenin. We found that naringenin inhibited Dictyostelium cell division in a dose-dependent manner (IC 5 ∼ 20 μM). Assays of Dictyostelium chemotaxis and multicellular development revealed that naringenin possesses a previously unrecognized ability to suppress amoeboid cell motility. We also found that naringenin, which is known to inhibit phosphatidylinositol 3-kinase activity, had no apparent effect on phosphatidylinositol 3,4,5-trisphosphate synthesis in live Dictyostelium cells; suggesting that this compound suppresses cell growth and migration via alternative signaling pathways. In another context, the discoveries described here highlight the value of using the Dictyostelium model system for identifying and characterizing the mechanisms by which naringenin, and related compounds, exert their effects on eukaryotic cells

Amoebic liver abscess in northern Sri Lanka: first report of immunological and molecular confirmation of aetiology.

Science.gov (United States)

Kannathasan, Selvam; Murugananthan, Arumugam; Kumanan, Thirunavukarasu; Iddawala, Devika; de Silva, Nilanthi Renuka; Rajeshkannan, Nadarajah; Haque, Rashidul

2017-01-07

Since 1985, amoebic liver abscess (ALA) has been a public health problem in northern Sri Lanka. Clinicians arrive at a diagnosis based on clinical and ultrasonographic findings, which cannot differentiate pyogenic liver abscess (PLA) from ALA. As the treatment and outcome of the ALA and PLA differs, determining the etiological agent is crucial. All clinically diagnosed ALA patients admitted to the Teaching Hospital (TH) in Jaffna during the study period were included and the clinical features, haematological parameters, and ultrasound scanning findings were obtained. Aspirated pus, blood, and faecal samples from patients were also collected. Pus and faeces were examined microscopically for amoebae. Pus was cultured in Robinson's medium for amoebae, and MacConkey and blood agar for bacterial growth. ELISA kits were used for immunodiagnosis of Entamoeba histolytica infection. DNA was extracted from selected pus samples and amplified using nested PCR and the purified product was sequenced. From July 2012 to July 2015, 346 of 367 clinically diagnosed ALA patients admitted to Jaffna Teaching Hospital were enrolled in this study. Almost all patients (98.6%) were males with a history of heavy alcohol consumption (100%). The main clinical features were fever (100%), right hypochodric pain (100%), tender hepatomegaly (90%) and intercostal tenderness (60%). Most patients had leukocytosis (86.7%), elevated ESR (85.8%) and elevated alkaline phosphatase (72.3%). Most of the abscesses were in the right lobe (85.3%) and solitary (76.3%) in nature. Among the 221 (63.87%) drained abscesses, 93.2% were chocolate brown in colour with the mean volume of 41.22 ± 1.16 ml. Only four pus samples (2%) were positive for amoeba by culture and the rest of the pus and faecal samples were negative microscopically and by culture. Furthermore, all pus samples were negative for bacterial growth. Antibody against E. histolytica (99.7%) and the E. histolytica antigen were detected in the pus

Acanthamoeba keratitis challenges a case report

OpenAIRE

Cristina, Stan; Cristina, Vlăduţiu; Mihaela, Popovici

2016-01-01

Acanthamoeba keratitis is a rare, chronic, mainly contact lens-related infection caused by a free-living amoeba found ubiquitously in water and soil. A case of a 9-year-old child, who presented to our clinic with painful, red left eye, associated with photophobia, and decreased visual acuity, wais reported. The clinical examination revealed a discoid opacity inferiorly bounded by a dense, gray infiltrate. The progressive nature of the corneal infiltrate, the epithelial defect, and the lack of...

From Social Network (Centralized vs. Decentralized) to Collective Decision-Making (Unshared vs. Shared Consensus)

OpenAIRE

Sueur, Cédric; Deneubourg, Jean-Louis; Petit, Odile

2012-01-01

Relationships we have with our friends, family, or colleagues influence our personal decisions, as well as decisions we make together with others. As in human beings, despotism and egalitarian societies seem to also exist in animals. While studies have shown that social networks constrain many phenomena from amoebae to primates, we still do not know how consensus emerges from the properties of social networks in many biological systems. We created artificial social networks that represent the...

Effects of altered temperature and precipitation on desert protozoa associated with biological soil crusts.

Science.gov (United States)

Darby, Brian J; Housman, David C; Zaki, Amr M; Shamout, Yassein; Adl, Sina M; Belnap, Jayne; Neher, Deborah A

2006-01-01

Biological soil crusts are diverse assemblages of bacteria, cyanobacteria, algae, fungi, lichens, and mosses that cover much of arid land soils. The objective of this study was to quantify protozoa associated with biological soil crusts and test the response of protozoa to increased temperature and precipitation as is predicted by some global climate models. Protozoa were more abundant when associated with cyanobacteria/lichen crusts than with cyanobacteria crusts alone. Amoebae, flagellates, and ciliates originating from the Colorado Plateau desert (cool desert, primarily winter precipitation) declined 50-, 10-, and 100-fold, respectively, when moved in field mesocosms to the Chihuahuan Desert (hot desert, primarily summer rain). However, this was not observed in protozoa collected from the Chihuahuan Desert and moved to the Sonoran desert (hot desert, also summer rain, but warmer than Chihuahuan Desert). Protozoa in culture began to encyst at 37 degrees C. Cysts survived the upper end of daily temperatures (37-55 degrees C), and could be stimulated to excyst if temperatures were reduced to 15 degrees C or lower. Results from this study suggest that cool desert protozoa are influenced negatively by increased summer precipitation during excessive summer temperatures, and that desert protozoa may be adapted to a specific desert's temperature and precipitation regime.

Pentastomiasis and other parasitic zoonoses from reptiles and amphibians.

Science.gov (United States)

Pantchev, Nikola; Tappe, Dennis

2011-01-01

Reptiles are growing in popularity as pets.The colonization of reptiles and amphibians by parasites and the resulting disease conditions are the most common problems seen in captive animals.This review focuses on pentastomiasis and sparganosis, important parasitic zoonoses of reptiles and amphibians, respectively, and free living-amoebae. Humans are suitable accidental hosts for some pentastomid species (particularly Armillifer and Porocephalus). In geographical areas with special ethnics, such as in West and Central Africa, and East Asia, 8-45% of the human population can be affected. Usually the larvae are coincidentally found during abdominal surgeries. However, fatalities have been described. Extreme caution is necessary when handling infected reptiles. Ocular or cerebral sparganosis is not uncommonly found in humans in East Asia. This disease is caused by spargana, tapeworm larvae (plerocercoids) of Spirometra sp. The infection occurs when uncooked meat from reptiles or amphibians is applied to wounds or eyes and the parasites migrate directly to human tissue, or by consumption of contaminated food or water. As a consequence of the reptile's predatory behaviour, the full spectrum of endo- and ectoparasites from potential prey animals can be found as transiting parasites in the intestinal tract, e. g. Hymenolepis nana, Cryptosporidium (C.) muris, C parvum or Capillaria hepatica. Occasionally, free-living amoebae are also found in reptile faeces (Acanthamoeba, Naegleria, Hartmanella, Vahlkampfia or Echinamoeba sp.).

Integrating Horizontal Gene Transfer and Common Descent to Depict Evolution and Contrast It with “Common Design”1

Science.gov (United States)

GUILLERMO PAZ-Y-MIÑO-C; ESPINOSA, AVELINA

2016-01-01

Horizontal gene transfer (HGT) and common descent interact in space and time. Because events of HGT co-occur with phylogenetic evolution, it is difficult to depict evolutionary patterns graphically. Tree-like representations of life’s diversification are useful, but they ignore the significance of HGT in evolutionary history, particularly of unicellular organisms, ancestors of multicellular life. Here we integrate the reticulated-tree model, ring of life, symbiogenesis whole-organism model, and eliminative pattern pluralism to represent evolution. Using Entamoeba histolytica alcohol dehydrogenase 2 (EhADH2), a bifunctional enzyme in the glycolytic pathway of amoeba, we illustrate how EhADH2 could be the product of both horizontally acquired features from ancestral prokaryotes (i.e. aldehyde dehydrogenase [ALDH] and alcohol dehydrogenase [ADH]), and subsequent functional integration of these enzymes into EhADH2, which is now inherited by amoeba via common descent. Natural selection has driven the evolution of EhADH2 active sites, which require specific amino acids (cysteine 252 in the ALDH domain; histidine 754 in the ADH domain), iron- and NAD+ as cofactors, and the substrates acetyl-CoA for ALDH and acetaldehyde for ADH. Alternative views invoking “common design” (i.e. the non-naturalistic emergence of major taxa independent from ancestry) to explain the interaction between horizontal and vertical evolution are unfounded. PMID:20021546

Distributed computer systems theory and practice

CERN Document Server

Zedan, H S M

2014-01-01

Distributed Computer Systems: Theory and Practice is a collection of papers dealing with the design and implementation of operating systems, including distributed systems, such as the amoeba system, argus, Andrew, and grapevine. One paper discusses the concepts and notations for concurrent programming, particularly language notation used in computer programming, synchronization methods, and also compares three classes of languages. Another paper explains load balancing or load redistribution to improve system performance, namely, static balancing and adaptive load balancing. For program effici

Environmental Mycobacterium avium subsp. paratuberculosis hosted by free-living amoebae

Science.gov (United States)

Mycobacterium avium subsp. paratuberculosis is responsible for paratuberculosis in animals. This disease, leading to an inflammation of the gastrointestinal tract, has a high impact on animal health and an important economic burden. The environmental life cycle of Mycobacterium avium subsp. paratube...

NAKED AMOEBAE (PROTOZOA) OF THE SALTON SEA, CALIFORNIA. (R826552)

Science.gov (United States)

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Soil fauna communities and microbial respiration in high Arctic tundra soils at Zackenberg, Northeast Greenland

DEFF Research Database (Denmark)

Sørensen, Louise I.; Holmstrup, Martin; Maraldo, Kristine

2006-01-01

The soil fauna communities were described for three dominant vegetation types in a high arctic site at Zackenberg, Northeast Greenland. Soil samples were extracted to quantify the densities of mites, collembolans, enchytraeids, diptera larvae, nematodes and protozoa. Rates of microbial respiration...... densities (naked amoeba and heterotrophic flagellates) were equal. Respiration rate of unamended soil was similar in soil from the three plots. However, a higher respiration rate increase in carbon + nutrient amended soil and the higher densities of soil fauna (with the exception of mites and protozoa...

Development and application of a most probable number-PCR assay to quantify flagellate populations in soil samples

DEFF Research Database (Denmark)

Fredslund, Line; Ekelund, Flemming; Jacobsen, Carsten Suhr

2001-01-01

This paper reports on the first successful molecular detection and quantification of soil protozoa. Quantification of heterotrophic flagellates and naked amoebae in soil has traditionally relied on dilution culturing techniques, followed by most-probable-number (MPN) calculations. Such methods...... are biased by differences in the culturability of soil protozoa and are unable to quantify specific taxonomic groups, and the results are highly dependent on the choice of media and the skills of the microscopists. Successful detection of protozoa in soil by DNA techniques requires (i) the development...

Current Status of Acanthamoeba in Iran: A Narrative Review Article.

Directory of Open Access Journals (Sweden)

Maryam Niyyati

2015-06-01

Full Text Available Free-living amoebae belonging to the genus Acanthamoeba have an environmental distribution. Amoebic keratitis due to these protozoan parasites continue to rise in Iran and worldwide. In Iran, there are various researches regarding both morphological and molecular identification of Acanthamoeba spp. in environmental and clinical samples. However, there is no thorough review about Acanthamoeba genotypes and their distribution in environmental sources such as water, dust and biofilm in Iran. Besides, according to increasing cases of Amoebic keratitis in the region awareness regarding the pathogenic potential of these sight-threatening amoebae is of utmost importance.We conducted a thorough review based on the database sources such as MEDLINE, PubMed and Google scholar. No restrictions were placed on study date, study design or language of publication. We searched all valuable and relevant information considering the occurrence of the Acanthamoeba in both environmental and clinical samples.According to our thorough review Acanthamoeba belonging to T4 genotype is the most prevalent type strain in environmental and clinical samples in several regions in Iran and worldwide, however, there are reports regarding Acanthamoeba belonging to other genotypes such as T2, T3, T5, T6 and T11 and the mentioned point could leads us to more researches with the goal of presenting the real genotype dominance of Acanthamoeba and related disease in the country.Overall, the present review will focus on present status of genotypes of Acanthamoeba in Iran during recent years.

Comparing and improving reconstruction methods for proxies based on compositional data

Science.gov (United States)

Nolan, C.; Tipton, J.; Booth, R.; Jackson, S. T.; Hooten, M.

2017-12-01

Many types of studies in paleoclimatology and paleoecology involve compositional data. Often, these studies aim to use compositional data to reconstruct an environmental variable of interest; the reconstruction is usually done via the development of a transfer function. Transfer functions have been developed using many different methods. Existing methods tend to relate the compositional data and the reconstruction target in very simple ways. Additionally, the results from different methods are rarely compared. Here we seek to address these two issues. First, we introduce a new hierarchical Bayesian multivariate gaussian process model; this model allows for the relationship between each species in the compositional dataset and the environmental variable to be modeled in a way that captures the underlying complexities. Then, we compare this new method to machine learning techniques and commonly used existing methods. The comparisons are based on reconstructing the water table depth history of Caribou Bog (an ombrotrophic Sphagnum peat bog in Old Town, Maine, USA) from a new 7500 year long record of testate amoebae assemblages. The resulting reconstructions from different methods diverge in both their resulting means and uncertainties. In particular, uncertainty tends to be drastically underestimated by some common methods. These results will help to improve inference of water table depth from testate amoebae. Furthermore, this approach can be applied to test and improve inferences of past environmental conditions from a broad array of paleo-proxies based on compositional data

[Contamination of protozoa by enteroviruses in fresh water and sewages].

Science.gov (United States)

Skachkov, M V; Al'misheva, A Sh; Plotnikov, A O; Nemtseva, N V; Skvortsov, V O

2009-01-01

To determine rate of infection of protozoa by enteroviruses to assess the potential role of protozoa as a natural reservoir of enteroviruses. The samples were collected from flowing and stagnant water reservoirs in Orenburg region in summer and autumn. The samples of sewages were taken in all stages of their treatment. Cultures of protozoa were isolated with micromanipulator equipped with micropipette, incubated on Pratt's medium at 25 degrees C and fed with Pseudomonas fluorescens culture. RNA of enteroviruses was detected by reverse transcription polymerase chain reaction (RT-PCR). Seventy-two protozoan species were found in Ural river, whereas 15 and 38 species were found in lakes and sewages respectively. Enteroviruses were detected by RT-PCR in 61.8% cultures of protozoa belonging to 23 species of flagellates, amoebae and ciliates isolated from natural water bodies undergoing anthropogenic impact as well as from sewages in all stages of their treatment. Predominant localization of enteroviruses in dominant taxons of protozoa (Paraphysomonas sp., Spumella sp., Petalomonas poosilla, Amoeba sp.) was noted. Obtained data confirm presence of enteroviruses in protozoa living both in flowing and stagnant recreation natural water bodies as well as in sewages and confirm the hypothesis of persistence of enteroviruses in protozoa and the reservoir role of the latter. Contingency of life cycles of viruses and protozoa allows to explain the seasonality of aseptic meningitis incidence caused by enteroviruses, which peaks in summer and autumn when protozoa massively multiply in water bodies.

Chemical composition and anti-Acanthamoeba activity of Melaleuca styphelioides essential oil.

Science.gov (United States)

Albouchi, Ferdaous; Sifaoui, Ines; Reyes-Batlle, Maria; López-Arencibia, Atteneri; Piñero, José E; Lorenzo-Morales, Jacob; Abderrabba, Manef

2017-12-01

Acanthamoeba infections cause serious humans diseases, such as amoebic keratitis and granulomatous amoebic encephalitis. Melaleuca essential oil has been reported to be effective in treating bacterial and fungal infections. However, the anti-parasitic effects of this essential oil are not well studied. In the present study, we first characterized the composition of the essential oil, extracted from the Tunisian Melaleuca styphelioides leaves, and then tested its effect on the Acanthamoeba castellanii Neff. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that the major common compounds were Caryophyllene oxide (23.42%), Spathulenol (20.5%), Isoaromadendrene epoxide (7.45%), Ledol (5.98%), α-Pinene (3.82%), Isopinocarveol (2.18%). Our data also showed that M. styphelioides essential oil inhibited the growth of Acanthamoeba with an IC 50 value of 69.03 ± 9.17 μg/ml. This work suggests M. styphelioides essential oil as a potential anti amoeba drug. Nevertheless, further studies are still needed to further verify the cytotoxicity of the studied oil on human macrophages and check its applicability to treat Acanthamoeba infections in vivo. Copyright © 2017 Elsevier Inc. All rights reserved.

Presencia de Malameba locustae (Protozoa: Rhizopoda en acridios (Orthoptera: Acrididae de la provincia de Misiones, Argentina Presence of Malameba locustae (Protozoa: Rhizopoda in grasshoppers (Orthoptera: Acrididae of Misiones province, Argentina

Directory of Open Access Journals (Sweden)

Carlos E. Lange

2004-07-01

Full Text Available La ameba patógena Malameba locustae King y Taylor fue detectada parasitando ejemplares del acridio Ronderosia bergi (Stal recolectados en las cercanías del Parque Nacional Iguazú, Misiones. El hallazgo constituye el segundo registro de M. locustae para acridios sudamericanos.Individuals of the grasshopper Ronderosia bergi (Stal collected in the surroundings of Iguazú National Park, Misiones, were found to be parasitized by the pathogenic amoeba Malameba locustae King & Taylor. The finding constitutes the second record of M. locustae for southamerican grasshoppers.

Population dynamics of active and total ciliate populations in arable soil amended with wheat

DEFF Research Database (Denmark)

Ekelund, F.; Frederiksen, Helle B.; Ronn, R.

2002-01-01

of the population may be encysted. The factors governing the dynamics of active and encysted cells in the soil are not well understood. Our objective was to determine the dynamics of active and encysted populations of ciliates during the decomposition of freshly added organic material. We monitored, in soil...... microcosms, the active and total populations of ciliates, their potential prey (bacteria and small protozoa), their potential competitors (amoebae, flagellates, and nematodes), and their potential predators (nematodes). We sampled with short time intervals (2 to 6 days) and generated a data set, suitable...

Host tissue destruction by Entamoeba histolytica: molecules mediating adhesion, cytolysis, and proteolysis

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Rolf D. Horstmann

1992-01-01

Full Text Available Entamoeba histolytica, the protozoan parasite causing human amoebisis, has recently been found to comprise two genetically distinct forms, potentially pathogenic and constitutively nonpathogenic ones. Host tissue destruction by pathogenic forms is belived to result from cell functions mediaed by a lectin-type adherence receptor, a pore-forming peptide involved in host cell lysis, and abundant expression of cysteine proteinase(s. Isolation and molecular cloning of these amoeba products have provided the tools for structural analyses and manipulations of cell functions including comparisons between pathogenic and nonpathogenic forms.

The Selective Use of Hypochlorite to Prevent Pond Crashes for Algae-Biofuel Production.

Science.gov (United States)

2015-09-21

Although algae-biofuels have many advantages including high areal productivity, algae can be preyed upon by amoebas, protozoans, ciliates, and rotifers, particularly in open pond systems. Thus, these higher organisms need to be controlled. In this study, Chlorella kessleri was used as the algal culture and Brachionus calyciflorus as the source of predation. The effect of sodium hypochlorite (bleach) was tested with the goal of totally inhibiting the rotifer while causing minor inhibition to the alga. The 24-hr LC50 for B. calyciflorus in spring water was 0.198 mg Cl/L while the 24-hr LC50 for C. kessleri was 0.321 mg Cl/L. However, chlorine dissipates rapidly as the algae serves as reductant. Results showed a chlorine dosage between 0.45 to 0.6 mg Cl/L and a dosing interval of two hours created the necessary chlorine concentrations to inhibit predation while letting the algae grow; thus giving algae farmers a tool to prevent pond crashes. Water Environ. Res., 87 (2015).

Analyzing the spatial positioning of nuclei in polynuclear giant cells

International Nuclear Information System (INIS)

Stange, Maike; Hintsche, Marius; Sachse, Kirsten; Gerhardt, Matthias; Beta, Carsten; Valleriani, Angelo

2017-01-01

How cells establish and maintain a well-defined size is a fundamental question of cell biology. Here we investigated to what extent the microtubule cytoskeleton can set a predefined cell size, independent of an enclosing cell membrane. We used electropulse-induced cell fusion to form giant multinuclear cells of the social amoeba Dictyostelium discoideum . Based on dual-color confocal imaging of cells that expressed fluorescent markers for the cell nucleus and the microtubules, we determined the subcellular distributions of nuclei and centrosomes in the giant cells. Our two- and three-dimensional imaging results showed that the positions of nuclei in giant cells do not fall onto a regular lattice. However, a comparison with model predictions for random positioning showed that the subcellular arrangement of nuclei maintains a low but still detectable degree of ordering. This can be explained by the steric requirements of the microtubule cytoskeleton, as confirmed by the effect of a microtubule degrading drug. (paper)

Analyzing the spatial positioning of nuclei in polynuclear giant cells

Science.gov (United States)

Stange, Maike; Hintsche, Marius; Sachse, Kirsten; Gerhardt, Matthias; Valleriani, Angelo; Beta, Carsten

2017-11-01

How cells establish and maintain a well-defined size is a fundamental question of cell biology. Here we investigated to what extent the microtubule cytoskeleton can set a predefined cell size, independent of an enclosing cell membrane. We used electropulse-induced cell fusion to form giant multinuclear cells of the social amoeba Dictyostelium discoideum. Based on dual-color confocal imaging of cells that expressed fluorescent markers for the cell nucleus and the microtubules, we determined the subcellular distributions of nuclei and centrosomes in the giant cells. Our two- and three-dimensional imaging results showed that the positions of nuclei in giant cells do not fall onto a regular lattice. However, a comparison with model predictions for random positioning showed that the subcellular arrangement of nuclei maintains a low but still detectable degree of ordering. This can be explained by the steric requirements of the microtubule cytoskeleton, as confirmed by the effect of a microtubule degrading drug.

Plan of development of ZrC-TRISO coated fuel particle and construction of ZrC coater

Energy Technology Data Exchange (ETDEWEB)

Ueta, Shohei; Ino, Hiroichi; Sawa, Kazuhiro [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment; Tobita, Tsutomu [Nuclear Engineering Company, Ltd., Tokai, Ibaraki (Japan); Takahashi, Masashi [Nuclear Fuel Industries, Ltd., Tokyo (Japan)

2002-11-01

In order to use coated fuel particle under higher temperature condition, more refractory coating material, which is more refractory than conventional silicon carbide (SiC), should be applied. Zirconium carbide (ZrC) is considered to be one of the promising materials, which is proposed as candidate for VHTR fuel material in GENERATION-IV, because of its intactness under high temperature of around 2000degC and its higher stability against kernel migration (amoeba effect) and fission product corrosion under normal operating condition. In order to develop ZrC coated particle for commercial use, research and development items were extracted based on review of the previous works. Research and development plan was determined. Based on the plan, a new ZrC coater of 100g batch size, which applies bromine process, was constructed. This report describes the review of precious works, extracted research and develop items and plan, and specifications of the ZrC coater. (author)

Potentially pathogenic amoeba-associated microorganisms in cooling towers and their control.

Science.gov (United States)

Pagnier, Isabelle; Merchat, Michèle; La Scola, Bernard

2009-06-01

Cooling towers provide a favorable environment for the proliferation of microorganisms. Cooling towers generate a biofilm and often aerosolize contaminated water, thereby increasing the risk of microorganism dissemination by human inhalation. This pathogen dissemination was first revealed by the epidemics of Legionnaires' disease that were directly related to the presence of cooling towers, and since then, the ecology of Legionella pneumophila has been well studied. Each country has specific standards regarding the acceptable amount of microorganisms in cooling tower systems. However, those standards typically only concern L. pneumophila, even though many other microorganisms can also be isolated from cooling towers, including protozoa, bacteria and viruses. Microbiological control of the cooling tower system can be principally achieved by chemical treatments and also by improving the system's construction. Several new treatments are being studied to improve the efficiency of disinfection. However, as most of these treatments continue to focus solely on L. pneumophila, reports of other types of pathogens continue to increase. Therefore, how their dissemination affects the human populous health should be addressed now.

High fidelity information processing in folic acid chemotaxis of Dictyostelium amoebae.

Science.gov (United States)

Segota, Igor; Mong, Surin; Neidich, Eitan; Rachakonda, Archana; Lussenhop, Catherine J; Franck, Carl

2013-11-06

Living cells depend upon the detection of chemical signals for their existence. Eukaryotic cells can sense a concentration difference as low as a few per cent across their bodies. This process was previously suggested to be limited by the receptor-ligand binding fluctuations. Here, we first determine the chemotaxis response of Dictyostelium cells to static folic acid gradients and show that they can significantly exceed this sensitivity, responding to gradients as shallow as 0.2% across the cell body. Second, using a previously developed information theory framework, we compare the total information gained about the gradient (based on the cell response) to its upper limit: the information gained at the receptor-ligand binding step. We find that the model originally applied to cAMP sensing fails as demonstrated by the violation of the data processing inequality, i.e. the total information exceeds the information at the receptor-ligand binding step. We propose an extended model with multiple known receptor types and with cells allowed to perform several independent measurements of receptor occupancy. This does not violate the data processing inequality and implies the receptor-ligand binding noise dominates both for low- and high-chemoattractant concentrations. We also speculate that the interplay between exploration and exploitation is used as a strategy for accurate sensing of otherwise unmeasurable levels of a chemoattractant.

Control of cyclin C levels during development of Dictyostelium.

Directory of Open Access Journals (Sweden)

David M Greene

2010-05-01

Full Text Available Cdk8 and its partner cyclin C form part of the mediator complex which links the basal transcription machinery to regulatory proteins. The pair are required for correct regulation of a subset of genes and have been implicated in control of development in a number of organisms including the social amoeba Dictyostelium discoideum. When feeding, Dictyostelium amoebae are unicellular but upon starvation they aggregate to form a multicellular structure which develops into a fruiting body containing spores. Cells in which the gene encoding Cdk8 has been deleted fail to enter aggregates due to a failure of early gene expression.We have monitored the expression levels of cyclin C protein during development and find levels decrease after the multicellular mound is formed. This decrease is triggered by extracellular cAMP that, in turn, is working in part through an increase in intracellular cAMP. The loss of cyclin C is coincident with a reduction in the association of Cdk8 with a high molecular weight complex in the nucleus. Overexpression of cyclin C and Cdk8 lead to an increased rate of early development, consistent with the levels being rate limiting.Overall these results show that both cyclin C and Cdk8 are regulated during development in response to extracellular signals and the levels of these proteins are important in controlling the timing of developmental processes. These findings have important implications for the role of these proteins in controlling development, suggesting that they are targets for developmental signals to regulate gene expression.

DNA mutations mediate microevolution between host-adapted forms of the pathogenic fungus Cryptococcus neoformans.

Directory of Open Access Journals (Sweden)

Denise A Magditch

Full Text Available The disease cryptococcosis, caused by the fungus Cryptococcus neoformans, is acquired directly from environmental exposure rather than transmitted person-to-person. One explanation for the pathogenicity of this species is that interactions with environmental predators select for virulence. However, co-incubation of C. neoformans with amoeba can cause a "switch" from the normal yeast morphology to a pseudohyphal form, enabling fungi to survive exposure to amoeba, yet conversely reducing virulence in mammalian models of cryptococcosis. Like other human pathogenic fungi, C. neoformans is capable of microevolutionary changes that influence the biology of the organism and outcome of the host-pathogen interaction. A yeast-pseudohyphal phenotypic switch also happens under in vitro conditions. Here, we demonstrate that this morphological switch, rather than being under epigenetic control, is controlled by DNA mutation since all pseudohyphal strains bear mutations within genes encoding components of the RAM pathway. High rates of isolation of pseudohyphal strains can be explained by the physical size of RAM pathway genes and a hypermutator phenotype of the strain used in phenotypic switching studies. Reversion to wild type yeast morphology in vitro or within a mammalian host can occur through different mechanisms, with one being counter-acting mutations. Infection of mice with RAM mutants reveals several outcomes: clearance of the infection, asymptomatic maintenance of the strains, or reversion to wild type forms and progression of disease. These findings demonstrate a key role of mutation events in microevolution to modulate the ability of a fungal pathogen to cause disease.

Not all are free-living: high-throughput DNA metabarcoding reveals a diverse community of protists parasitizing soil metazoa.

Science.gov (United States)

Geisen, S; Laros, I; Vizcaíno, A; Bonkowski, M; de Groot, G A

2015-09-01

Protists, the most diverse eukaryotes, are largely considered to be free-living bacterivores, but vast numbers of taxa are known to parasitize plants or animals. High-throughput sequencing (HTS) approaches now commonly replace cultivation-based approaches in studying soil protists, but insights into common biases associated with this method are limited to aquatic taxa and samples. We created a mock community of common free-living soil protists (amoebae, flagellates, ciliates), extracted DNA and amplified it in the presence of metazoan DNA using 454 HTS. We aimed at evaluating whether HTS quantitatively reveals true relative abundances of soil protists and at investigating whether the expected protist community structure is altered by the co-amplification of metazoan-associated protist taxa. Indeed, HTS revealed fundamentally different protist communities from those expected. Ciliate sequences were highly over-represented, while those of most amoebae and flagellates were under-represented or totally absent. These results underpin the biases introduced by HTS that prevent reliable quantitative estimations of free-living protist communities. Furthermore, we detected a wide range of nonadded protist taxa probably introduced along with metazoan DNA, which altered the protist community structure. Among those, 20 taxa most closely resembled parasitic, often pathogenic taxa. Therewith, we provide the first HTS data in support of classical observational studies that showed that potential protist parasites are hosted by soil metazoa. Taken together, profound differences in amplification success between protist taxa and an inevitable co-extraction of protist taxa parasitizing soil metazoa obscure the true diversity of free-living soil protist communities. © 2015 John Wiley & Sons Ltd.

[Intestinal parasitosis among non-permanent resident students in Tunisia: a review of 23 years of monitoring in the department of Parasitology-Mycology at the Rabta Hospital of Tunisia].

Science.gov (United States)

Dridi, Kalthoum; Fakhfakh, Najla; Belhadj, Sleh; Kaouech, Emira; Kallel, Kalthoum; Chaker, Emna

2015-07-01

In order to fight digestive parasitism in Tunisia, a national program of surveillance of non-permanent resident students in Tunisia has been found to detect these parasitosis in this target population. To determine the prevalence of intestinal parasitosis among non-permanent resident students in Tunisia, to identify the different parasitic species founded and to show the interest of this screening. During a period of 23 years (1990-2012), 7386 parasitological examinations of stools has been made among students essentially from or had visited tropical Africa, Maghreb and Middle-East, at the laboratory of Parasitology-Mycology at the Rabta Hospital of Tunis. The prevalence of intestinal parasitism found was 34.45% (i.e. 2545 infested students). Among the protozoa that have been isolated in the majority of cases (78.75%), amoebae were most frequently found (86.4%) represented mainly by Entamoeba coli and Endolimax nanus in respectively, 25.62 and 23.33% of parasites isolated; while Entamoeba histolytica/dispar, only pathogenic Amoeba was found in 8.05% of the total of parasites isolated. Regarding helminths, found in 21.25% of parasites isolated, Ankylostome was predominant (34.5%) represented by the species of Necator americanus. A single case of Ancylostom duodenale has been isolated. Among the identified parasite species, 38.7% were known parasitic pathogens for humans. These results note the interest of the control of the non-permanent resident students in Tunisia. The precocious tracking and treatment of affected subjects permits to avoid the introduction and the dissemination of parasites already rare and virulent strains in our country.

Microfaunal primary succession on the volcanic island Surtsey

DEFF Research Database (Denmark)

Frederiksen, Helle B.; Kraglund, H. O.; Ekelund, F.

2001-01-01

and nematodes were absent and only amoebae and heterotrophic flagellates were found. Most of the protozoan populations we examined were unable to survive salinity levels corresponding to seawater. We therefore conclude that many of soil protozoa populations on Surtsey arrived to the island as airborne cysts...... with different vegetation types (unvegetated soil, soil with one or two plant species, and bird colony soil with a diverse vegetation). We recorded at least 16 nematode taxa and 13 flagellate taxa. Most of these were not reported in previous surveys from Surtsey. On the location with unvegetated soil, ciliates...

Dicty_cDB: [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available VF (Link to library) VFC231 (Link to dictyBase) - - - Contig-U16593-1 VFC231P (Link... to Original site) VFC231F 428 VFC231Z 202 VFC231P 630 - - Show VFC231 Library VF (Link to library) Clone ID VFC231 (Link to dict...yBase) Atlas ID - NBRP ID - dictyBase ID - Link to Contig Contig-U16593-1 Original site URL http://dict...amoeba histolytica genomic, DNA sequence. 48 0.13 1 AC116984 |AC116984.2 Dictyostelium discoideum chromosome...mbrane 4.0 %: vesicles of secretory system 4.0 %: extracellular, including cell wall >> predict

Basic principles of Hasse diagram technique in chemistry.

Science.gov (United States)

Brüggemann, Rainer; Voigt, Kristina

2008-11-01

Principles of partial order applied to ranking are explained. The Hasse diagram technique (HDT) is the application of partial order theory based on a data matrix. In this paper, HDT is introduced in a stepwise procedure, and some elementary theorems are exemplified. The focus is to show how the multivariate character of a data matrix is realized by HDT and in which cases one should apply other mathematical or statistical methods. Many simple examples illustrate the basic theoretical ideas. Finally, it is shown that HDT is a useful alternative for the evaluation of antifouling agents, which was originally performed by amoeba diagrams.

Molecular robots with sensors and intelligence.

Science.gov (United States)

Hagiya, Masami; Konagaya, Akihiko; Kobayashi, Satoshi; Saito, Hirohide; Murata, Satoshi

2014-06-17

CONSPECTUS: What we can call a molecular robot is a set of molecular devices such as sensors, logic gates, and actuators integrated into a consistent system. The molecular robot is supposed to react autonomously to its environment by receiving molecular signals and making decisions by molecular computation. Building such a system has long been a dream of scientists; however, despite extensive efforts, systems having all three functions (sensing, computation, and actuation) have not been realized yet. This Account introduces an ongoing research project that focuses on the development of molecular robotics funded by MEXT (Ministry of Education, Culture, Sports, Science and Technology, Japan). This 5 year project started in July 2012 and is titled "Development of Molecular Robots Equipped with Sensors and Intelligence". The major issues in the field of molecular robotics all correspond to a feedback (i.e., plan-do-see) cycle of a robotic system. More specifically, these issues are (1) developing molecular sensors capable of handling a wide array of signals, (2) developing amplification methods of signals to drive molecular computing devices, (3) accelerating molecular computing, (4) developing actuators that are controllable by molecular computers, and (5) providing bodies of molecular robots encapsulating the above molecular devices, which implement the conformational changes and locomotion of the robots. In this Account, the latest contributions to the project are reported. There are four research teams in the project that specialize on sensing, intelligence, amoeba-like actuation, and slime-like actuation, respectively. The molecular sensor team is focusing on the development of molecular sensors that can handle a variety of signals. This team is also investigating methods to amplify signals from the molecular sensors. The molecular intelligence team is developing molecular computers and is currently focusing on a new photochemical technology for accelerating DNA

Identification and Molecular Typing of Naegleria fowleri from a Patient of Primary Amebic Meningoencephalitis (PAM) in China.

Science.gov (United States)

Zhang, Ling-Ling; Wu, Mao; Hu, Bang-Chuan; Chen, Hua-Liang; Pan, Jin-Ren; Ruan, Wei; Yao, Li-Nong

2018-05-08

Naegleria fowleri (N. fowleri) is the only Naegleria spp. known to cause an acute, fulminant, and rapidly fatal central nervous system infection called primary amebic meningoencephalitis (PAM) in human. In 2016, a suspected PAM patient was found in Zhejiang Province of China. The pathogen was identified by microscopic examination and PCR. The positive PCR products were sequenced and the sequences were aligned using NCBI BLAST programme. The homologous and phylogenetic analysis was conducted using the MEGA 6 programme. Under the microscopy, the motile cells with pseudopodia were observed in the direct smear, the motion characteristics of pseudopodia as well as the cell morphology suggested that the pathogen were amoeba trophozoites. The smears stained with Wright-Giemsa showed amoeba trophozoites with various sharps, which were measured of 10-25μm and characterized by the prominent, centrally placed nucleolus and the vacuolated cytoplasm. The PCR showed negative for E. histolytica and E. dispar, while positive for Naegleria spp.and N. fowleri. The nucleotide sequences acquired from this study were submitted to the Genbank with accession numbers of KX909928 and KX909927, respectively. The Blast analysis revealed that the sequences of KX909928 and KX909927 have 100% similarity with the sequence of N. fowleri gene (KT375442.1). Sequence alignment and phylogenetic tree reavealed that N. fowleri collected from this study was classified as genotype 2 and had a closest relative with N. lovaniensis. This study confirms N. fowleri as the agent responsible for this patient, however, PAM normally progresses fast and universally fatal within a week, so the patient still died at two weeks after the onset of symptoms. Copyright © 2018. Published by Elsevier Ltd.

Diversity of the soil biota in burned areas of southern taiga forests (Tver oblast)

Science.gov (United States)

Gongalsky, K. B.; Zaitsev, A. S.; Korobushkin, D. I.; Saifutdinov, R. A.; Yazrikova, T. E.; Benediktova, A. I.; Gorbunova, A. Yu.; Gorshkova, I. A.; Butenko, K. O.; Kosina, N. V.; Lapygina, E. V.; Kuznetsova, D. M.; Rakhleeva, A. A.; Shakhab, S. V.

2016-03-01

Relations between soil biota diversity and its contribution to the performance of some ecosystem functions were assessed based on the results obtained in undisturbed and burned spruce forests near the Central Forest Nature Biosphere Reserve (Tver oblast). In August 2014, in two 4-year-old burned areas, abiotic parameters of the soils, indicators of the state of the microbial communities, the number, taxonomic diversity, and the abundance of the main groups of soil invertebrates (testate amoebae, nematodes, enchytraeids, mites, collembolans, and the mesofauna as a whole) were determined. In the soils of the burned areas, higher CO2, CH4, and N2O emissions were observed. The number of bacterial cells remained similar, and the total length of active mycelium was not significantly different. All this implies a certain intensification of biogenic processes promoting the mobilization of carbon and nitrogen after fire. The number of most of the groups of soil animals was lower (not always significantly) in the burned area than that in the soils of the undisturbed forests. The changes in the taxonomic diversity were specific for each taxon studied. Overall, the diversity of invertebrates was related to the litter thickness. However, the high taxonomic diversity of soil fauna did not always correspond to the active functioning of the ecosystem. Thus, for some taxa, a quite close correlation was found, for instance, between the total number of species (of testate amoebae in particular) and the berry crop, as well as between the soil mesofauna population and the dead wood stock. The total diversity of the investigated taxa included in the detrital trophic web was the most reliable indicator of the carbon stock in the burned areas.

Investigation of Legionella Contamination in Bath Water Samples by Culture, Amoebic Co-Culture, and Real-Time Quantitative PCR Methods.

Science.gov (United States)

Edagawa, Akiko; Kimura, Akio; Kawabuchi-Kurata, Takako; Adachi, Shinichi; Furuhata, Katsunori; Miyamoto, Hiroshi

2015-10-19

We investigated Legionella contamination in bath water samples, collected from 68 bathing facilities in Japan, by culture, culture with amoebic co-culture, real-time quantitative PCR (qPCR), and real-time qPCR with amoebic co-culture. Using the conventional culture method, Legionella pneumophila was detected in 11 samples (11/68, 16.2%). Contrary to our expectation, the culture method with the amoebic co-culture technique did not increase the detection rate of Legionella (4/68, 5.9%). In contrast, a combination of the amoebic co-culture technique followed by qPCR successfully increased the detection rate (57/68, 83.8%) compared with real-time qPCR alone (46/68, 67.6%). Using real-time qPCR after culture with amoebic co-culture, more than 10-fold higher bacterial numbers were observed in 30 samples (30/68, 44.1%) compared with the same samples without co-culture. On the other hand, higher bacterial numbers were not observed after propagation by amoebae in 32 samples (32/68, 47.1%). Legionella was not detected in the remaining six samples (6/68, 8.8%), irrespective of the method. These results suggest that application of the amoebic co-culture technique prior to real-time qPCR may be useful for the sensitive detection of Legionella from bath water samples. Furthermore, a combination of amoebic co-culture and real-time qPCR might be useful to detect viable and virulent Legionella because their ability to invade and multiply within free-living amoebae is considered to correlate with their pathogenicity for humans. This is the first report evaluating the efficacy of the amoebic co-culture technique for detecting Legionella in bath water samples.

Epilepsy research methods update: Understanding the causes of epileptic seizures and identifying new treatments using non-mammalian model organisms.

Science.gov (United States)

Cunliffe, Vincent T; Baines, Richard A; Giachello, Carlo N G; Lin, Wei-Hsiang; Morgan, Alan; Reuber, Markus; Russell, Claire; Walker, Matthew C; Williams, Robin S B

2015-01-01

This narrative review is intended to introduce clinicians treating epilepsy and researchers familiar with mammalian models of epilepsy to experimentally tractable, non-mammalian research models used in epilepsy research, ranging from unicellular eukaryotes to more complex multicellular organisms. The review focuses on four model organisms: the social amoeba Dictyostelium discoideum, the roundworm Caenorhabditis elegans, the fruit fly Drosophila melanogaster and the zebrafish Danio rerio. We consider recent discoveries made with each model organism and discuss the importance of these advances for the understanding and treatment of epilepsy in humans. The relative ease with which mutations in genes of interest can be produced and studied quickly and cheaply in these organisms, together with their anatomical and physiological simplicity in comparison to mammalian species, are major advantages when researchers are trying to unravel complex disease mechanisms. The short generation times of most of these model organisms also mean that they lend themselves particularly conveniently to the investigation of drug effects or epileptogenic processes across the lifecourse. Copyright © 2014 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.

Electron probe micro-analysis of irradiated Triso-coated UO2 particles, (1)

International Nuclear Information System (INIS)

Ogawa, Toru; Minato, Kazuo; Fukuda, Kosaku; Ikawa, Katsuichi

1983-11-01

The Triso-coated low-enriched UO 2 particles were subjected to the post-irradiation electron probe micro-analysis. Observations and analyses on the amoeba effect, inclusions and solutes in the UO 2 matrix were made. In the cooler side of the particle which suffered extensive kernel migration, two significant features were observed: (1) the wake of minute particles, presumably UO 2 , left by the moving kernel in the carbon phase and (2) carbon precipitation in the pores and along the grain boundaries of the UO 2 kernel. Both features could be hardly explained by the gas-phase mechanism of carbon transport and rather suggest the solid state mechanism. Two-types of 4d-transition metal inclusions were observed: the one which was predominantly Mo with a fraction of Tc and another which was enriched with Ru and containing significant amount of Si. The Mo and Si were also found in the UO 2 matrix; the observation led to the discussion of the oxygen potential in the irradiated Triso-coated UO 2 particle. (author)

Amebiasis in four ball pythons, Python reginus.

Science.gov (United States)

Kojimoto, A; Uchida, K; Horii, Y; Okumura, S; Yamaguch, R; Tateyama, S

2001-12-01

Between September 13th and November 18th in 1999, four ball pythons, Python reginus kept in the same display, showed anorexia and died one after another. At necropsy, all four snakes had severe hemorrhagic colitis. Microscopically, all snakes had severe necrotizing hemorrhagic colitis, in association with ameba-like protozoa. Some of the protozoa had macrophage-like morphology and others formed protozoal cysts with thickened walls. These protozoa were distributed throughout the wall in the large intestine. Based on the pathological findings, these snakes were infested with a member of Entamoeba sp., presumably with infection by Entamoeba invadens, the most prevalent type of reptilian amoebae.

Area 51: How do Acanthamoeba invade the central nervous system?

Science.gov (United States)

Siddiqui, Ruqaiyyah; Emes, Richard; Elsheikha, Hany; Khan, Naveed Ahmed

2011-05-01

Acanthamoeba granulomatous encephalitis generally develops as a result of haematogenous spread, but it is unclear how circulating amoebae enter the central nervous system (CNS) and cause inflammation. At present, the mechanisms which Acanthamoeba use to invade this incredibly well-protected area of the CNS and produce infection are not well understood. In this paper, we propose two key virulence factors: mannose-binding protein and extracellular serine proteases as key players in Acanthamoeba traversal of the blood-brain barrier leading to neuronal injury. Both molecules should provide excellent opportunities as potential targets in the rational development of therapeutic interventions against Acanthamoeba encephalitis. Copyright © 2011 Elsevier Ltd. All rights reserved.

Dicty_cDB: Contig-U12612-1 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available ... 50 2e-14 5 ( DW406140 ) EST000561 Trichophyton rubrum cDNA library Tricho... 50 2e-14 5 ( C... CAPH Naegleria gruberi amoeba stage ... 48 2e-15 6 ( DW703626 ) EST027107 Trichophyton rubrum cDNA library 7 Tric...... 50 7e-15 5 ( DW405704 ) EST000125 Trichophyton rubrum cDNA library Tric...ho... 50 1e-14 5 ( DW683765 ) EST007246 Trichophyton rubrum cDNA library 1 Tric... 50 1e-14 5 ( DW678803 ) EST002284 Tric...hophyton rubrum cDNA library 0 Tric... 50 1e-14 5 ( DW697736 ) EST021217 Trichophyton rubrum cDNA library 6 Tric

An Amoeba/Zoozanthellae Consortium as a Model System for Animal/Algal Symbiosis

Science.gov (United States)

1991-06-18

Areschoug, Gelidium robustum enzymes with a wider range of subs5%ec... (Gardner) Hollenberg et Abbott, Gigaruna ex- This paper describes the us of...or sevn days occured between 4 3 Log S to P iracilaria and Gelidium although these are both Log L t S agarophytes. A lag of one to two weeks occurred...regeneration in Porphyra perforata. J. Phycol. 20:609-616. )f Gelidium , Prionitis and Gigaruina, mostly from Poine-Fuller. M., 1987a. A multinucleated marine

Lemons, Mealworms, and the Giant Amoeba: A Eureka Trip through School Science.

Science.gov (United States)

McCormack, Alan J.

1980-01-01

Outlines teaching methods that emphasize the use of the right hemisphere of the brain. Argues that most productive thinking requires both modes of thinking and that any good elementary science program should include activities designed to develop both modes. (Author/IRT)

Actin cytoskeleton of chemotactic amoebae operates close to the onset of oscillations

Science.gov (United States)

Westendorf, Christian; Negrete, Jose; Bae, Albert J.; Sandmann, Rabea; Bodenschatz, Eberhard; Beta, Carsten

2013-01-01

The rapid reorganization of the actin cytoskeleton in response to external stimuli is an essential property of many motile eukaryotic cells. Here, we report evidence that the actin machinery of chemotactic Dictyostelium cells operates close to an oscillatory instability. When averaging the actin response of many cells to a short pulse of the chemoattractant cAMP, we observed a transient accumulation of cortical actin reminiscent of a damped oscillation. At the single-cell level, however, the response dynamics ranged from short, strongly damped responses to slowly decaying, weakly damped oscillations. Furthermore, in a small subpopulation, we observed self-sustained oscillations in the cortical F-actin concentration. To substantiate that an oscillatory mechanism governs the actin dynamics in these cells, we systematically exposed a large number of cells to periodic pulse trains of different frequencies. Our results indicate a resonance peak at a stimulation period of around 20 s. We propose a delayed feedback model that explains our experimental findings based on a time-delay in the regulatory network of the actin system. To test the model, we performed stimulation experiments with cells that express GFP-tagged fusion proteins of Coronin and actin-interacting protein 1, as well as knockout mutants that lack Coronin and actin-interacting protein 1. These actin-binding proteins enhance the disassembly of actin filaments and thus allow us to estimate the delay time in the regulatory feedback loop. Based on this independent estimate, our model predicts an intrinsic period of 20 s, which agrees with the resonance observed in our periodic stimulation experiments. PMID:23431176

Between a Pod and a Hard Test: The Deep Evolution of Amoebae

Czech Academy of Sciences Publication Activity Database

Kang, S.; Tice, A. K.; Spiegel, F. W.; Silberman, J. D.; Pánek, T.; Čepička, I.; Kostka, Martin; Kosakyan, A.; Alcantara, D. M. C.; Roger, A. J.; Shadwick, L.; Smirnov, A.; Kudryavtsev, A.; Lahr, D. J. G.; Brown, M. W.

2017-01-01

Roč. 34, č. 9 (2017), s. 2258-2270 ISSN 0737-4038 Institutional support: RVO:60077344 Keywords : phylogenomics * transcriptomes * Amoebozoa * reductive evolution * phylotranscriptomics Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Biology (theoretical, mathematical, thermal, cryobiology, biological rhythm), Evolutionary biology Impact factor: 6.202, year: 2016

Between a Pod and a Hard Test: The Deep Evolution of Amoebae.

Science.gov (United States)

Kang, Seungho; Tice, Alexander K; Spiegel, Frederick W; Silberman, Jeffrey D; Pánek, Tomáš; Cepicka, Ivan; Kostka, Martin; Kosakyan, Anush; Alcântara, Daniel M C; Roger, Andrew J; Shadwick, Lora L; Smirnov, Alexey; Kudryavtsev, Alexander; Lahr, Daniel J G; Brown, Matthew W

2017-09-01

Amoebozoa is the eukaryotic supergroup sister to Obazoa, the lineage that contains the animals and Fungi, as well as their protistan relatives, and the breviate and apusomonad flagellates. Amoebozoa is extraordinarily diverse, encompassing important model organisms and significant pathogens. Although amoebozoans are integral to global nutrient cycles and present in nearly all environments, they remain vastly understudied. We present a robust phylogeny of Amoebozoa based on broad representative set of taxa in a phylogenomic framework (325 genes). By sampling 61 taxa using culture-based and single-cell transcriptomics, our analyses show two major clades of Amoebozoa, Discosea, and Tevosa. This phylogeny refutes previous studies in major respects. Our results support the hypothesis that the last common ancestor of Amoebozoa was sexual and flagellated, it also may have had the ability to disperse propagules from a sporocarp-type fruiting body. Overall, the main macroevolutionary patterns in Amoebozoa appear to result from the parallel losses of homologous characters of a multiphase life cycle that included flagella, sex, and sporocarps rather than independent acquisition of convergent features. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Genome sequencing reveals metabolic and cellular interdependence in an amoeba-kinetoplastid symbiosis

Czech Academy of Sciences Publication Activity Database

Tanifuji, G.; Cenci, U.; Moog, D.; Dean, S.; Nakayama, T.; David, Vojtěch; Fiala, Ivan; Curtis, B.A.; Sibbald, S. J.; Onodera, N. T.; Colp, M.; Flegontov, Pavel; Johnson-MacKinnon, J.; McPhee, M.; Inagaki, Y.; Hashimoto, T.; Kelly, S.; Gull, K.; Lukeš, Julius; Archibald, J.M.

2017-01-01

Roč. 7, SEP 15 (2017), č. článku 11688. ISSN 2045-2322 R&D Projects: GA ČR(CZ) GA14-23986S; GA MŠk LL1601 Institutional support: RVO:60077344 Keywords : trypanosoma-brucei reveals * hidden markov model * neoparamoeba-pemaquidensis * gill disease * phylogenetic analyses * ichthyobodo-necator * gene prediction * host control * evolution * proteomics Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Biochemistry and molecular biology Impact factor: 4.259, year: 2016

Marine amoebae with cytoplasmic and perinuclear symbionts deeply branching in the Gammaproteobacteria

Czech Academy of Sciences Publication Activity Database

Schulz, F.; Tyml, Tomáš; Pizzetti, I.; Dyková, I.; Fazi, S.; Kostka, Martin; Horn, M.

2015-01-01

Roč. 5, 25 August (2015), č. článku 13381. ISSN 2045-2322 R&D Projects: GA ČR(CZ) GBP505/12/G112 Institutional support: RVO:60077344 Keywords : free- living amebas * bacterial endosymbionts * phylogenetic inference * Paramecium caudatum * Naegleria * gene expression * environment * chlamydiae * diversity * pathogens Subject RIV: EG - Zoology Impact factor: 5.228, year: 2015

Legionella - (re-)awakening to the Amoeba-based Pathogens of Distribution System Biofilm

Science.gov (United States)

Fecal pathogens have long been the focus of concern in the distribution of drinking waters. Yet today, with distribution system ‘failures’ accounting for the majority of waterborne outbreaks in the USA, there is growing realization that pathogens endemic to aquatic biofilms may a...

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

Bacteria and protozoa coexist in a wide range of biofilm communities of natural, technical and medical importance. Generally, this interaction is characterized by the extensive grazing activity of protozoa on bacterial prey populations. We hypothesized that the close spatial coexistence in biofilms...... suggest that conserved virulence pathways and specifically the T3SS play a central role in bacteria- protozoa interactions in biofilms and may be instrumental for the environmental persistence and evolution of opportunistic bacterial pathogens....

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.

Science.gov (United States)

Bhat, Deepak; Gopalakrishnan, Manoj

2012-08-01

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.

Acanthamoebicidal activity of periglaucine A and betulinic acid from Pericampylus glaucus (Lam.) Merr. in vitro.

Science.gov (United States)

Mahboob, Tooba; Azlan, Abdul-Majid; Shipton, Fiona Natalia; Boonroumkaew, Patcharaporn; Nor Azman, Nadiah Syafiqah; Sekaran, Shamala Devi; Ithoi, Init; Tan, Tian-Chye; Samudi, Chandramathi; Wiart, Christophe; Nissapatorn, Veeranoot

2017-12-01

Acanthamoeba species are pathogenic protozoa which account for amoebic keratitis, conjunctivitis and granulomatous amoebic encephalitis. These amoebae form cysts which resist drugs and more effective acanthamoebicidal agents are needed. Medicinal plants could be useful in improving the current treatment strategies for Acanthamoeba infections. In the present study, we examined the amoebicidal effects of Pericampylus glaucus (Lam.) Merr., a medicinal plant used for the treatment of conjunctivitis in Malaysia. Pathogenic Acanthamoeba triangularis were isolated from environmental water samples and treated with different concentrations of fractions obtained from Pericampylus glaucus (Lam.) Merr. as well as main constituents for 24-72 h. Chlorhexidine was used as a reference drug. Ethanol fraction of stem showed significant (p < 0.05) inhibition of trophozoites survival. Betulinic acid and periglaucine A from this plant at 100 μg/mL inhibited more than 70% survival of both cysts and trophozoites. The calculated therapeutic index for betulinic acid and periglaucine A was 170 and 1.5 for trophozoites stage and 3.75 and 8.5 for cysts stage. The observed amoebicidal efficacies indicate the beneficial aspects of this plant in the treatment of Acanthamoeba infection. Periglaucine A could also be of value for the treatment of Acanthamoeba infection. Copyright © 2017 Elsevier Inc. All rights reserved.

Survey on medicinal plants traditionally used in Senegal for the treatment of tuberculosis (TB) and assessment of their antimycobacterial activity.

Science.gov (United States)

Diop, ElHadji Assane; Queiroz, Emerson Ferreira; Kicka, Sébastien; Rudaz, Serge; Diop, Tahir; Soldati, Thierry; Wolfender, Jean-Luc

2018-04-24

In West Africa, populations are used to taking traditional medicine as a first aid against common health problems. In this aspect, many plants are claimed to be effective in the treatment of Tuberculosis (TB), which according to the World Health Organization (WHO) remains one of the world's deadliest communicable diseases. The main aim of this study was to identify plants used to treat TB-symptoms by the population of Senegal and to evaluate their possible concomitant use with clinically approved TB-drugs. This approach allowed the selection of plants effectively used in traditional medicine. In order to verify if the usage of some of these plants can be rationalized, the activity of their traditional preparations was assessed with both an intracellular and extracellular antimycobacterial host-pathogen assays. An ethnopharmacological survey conducted on 117 TB-patients and 30 healers in Senegal from March to May 2014. The questionnaires were focused on the use of medicinal plants to treat common TB -symptoms (cough longer than 2 weeks, fever, night sweats, weight loss and bloody sputum). Local plant names, utilized organs (herbal drugs) and traditional formulations of the plants were recorded. Extracts were prepared by mimicking the traditional decoction in boiling water and screened for their antimycobacterial activity using Mycobacterium marinum, as a validated TB surrogate, and an Acanthamoeba castellanii - M. marinum whole-cell based host-pathogen assay, to detect anti-infective activities. By the end of the survey, nearly 30 plants were cited and the 12 most cited herbal drugs were collected and their usage documented by extensive literature search. Extracts of the chosen herbs were screened with the described assays; with a main focus on traditional formulas (mainly herbal decoctions). Two of the water extracts from Combretum aculeatum and Guiera senegalensis showed significant antimycobacterial activities when compared to the positive control drug (rifampin

Effect of temperature and colonization of Legionella pneumophila and Vermamoeba vermiformis on bacterial community composition of copper drinking water biofilms.

Science.gov (United States)

Buse, Helen Y; Ji, Pan; Gomez-Alvarez, Vicente; Pruden, Amy; Edwards, Marc A; Ashbolt, Nicholas J

2017-07-01

It is unclear how the water-based pathogen, Legionella pneumophila (Lp), and associated free-living amoeba (FLA) hosts change or are changed by the microbial composition of drinking water (DW) biofilm communities. Thus, this study characterized the bacterial community structure over a 7-month period within mature (> 600-day-old) copper DW biofilms in reactors simulating premise plumbing and assessed the impact of temperature and introduction of Lp and its FLA host, Vermamoeba vermiformis (Vv), co-cultures (LpVv). Sequence and quantitative PCR (qPCR) analyses indicated a correlation between LpVv introduction and increases in Legionella spp. levels at room temperature (RT), while at 37°C, Lp became the dominant Legionella spp. qPCR analysis suggested Vv presence may not be directly associated with Lp biofilm growth at RT and 37°C, but may contribute to or be associated with non-Lp legionellae persistence at RT. Two-way PERMANOVA and PCoA revealed that temperature was a major driver of microbiome diversity. Biofilm community composition also changed over the seven-month period and could be associated with significant shifts in dissolved oxygen, alkalinity and various metals in the influent DW. Hence, temperature, biofilm age, DW quality and transient intrusions/amplification of pathogens and FLA hosts may significantly impact biofilm microbiomes and modulate pathogen levels over extended periods. © 2016 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

A gene encoding the major beta tubulin of the mitotic spindle in Physarum polycephalum plasmodia

Energy Technology Data Exchange (ETDEWEB)

Burland, T.G.; Paul, E.C.A.; Oetliker, M.; Dove, W.F.

1988-03-01

The multinucleate plasmodium of Physarum polycephalum is unusual among eucaryotic cells in that it uses tubulins only in mitotic-spindle microtubules; cytoskeletal, flagellar, and centriolar microtubules are absent in this cell type. The authors identified a ..beta..-tubulin cDNA clone, ..beta..105, which is shown to correspond to the transcript of the betC ..beta..-tubulin locus and to encode ..beta..2 tubulin, the ..beta.. tubulin expressed specifically in the plasmodium and used exclusively in the mitotic spindle. Physarum amoebae utilize tubulins in the cytoskeleton, centrioles, and flagella, in addition to the mitotic spindle. Sequence analysis shows that ..beta..2 tubulin is only 83% identical to the two ..beta.. tubulins expressed in amoebae. This compares with 70 to 83% identity between Physarum ..beta..2 tubulin and the ..beta.. tubulins of yeasts, fungi, alga, trypanosome, fruit fly, chicken, and mouse. On the other hand, Physarum ..beta..2 tubulin is no more similar to, for example, Aspergillus ..beta.. tubulins than it is to those of Drosophila melanogaster or mammals. Several eucaryotes express at least one widely diverged ..beta.. tubulin as well as one or more ..beta.. tubulins that conform more closely to a consensus ..beta..-tubulin sequence. The authors suggest that ..beta..-tubulins diverge more when their expression pattern is restricted, especially when this restriction results in their use in fewer functions. This divergence among ..beta.. tubulins could have resulted through neutral drift. For example, exclusive use of Physarum ..beta..2 tubulin in the spindle may have allowed more amino acid substitutions than would be functionally tolerable in the ..beta.. tubulins that are utilized in multiple microtubular organelles. Alternatively, restricted use of ..beta.. tubulins may allow positive selection to operate more freely to refine ..beta..-tubulin function.

Investigation of Legionella Contamination in Bath Water Samples by Culture, Amoebic Co-Culture, and Real-Time Quantitative PCR Methods

Directory of Open Access Journals (Sweden)

Akiko Edagawa

2015-10-01

Full Text Available We investigated Legionella contamination in bath water samples, collected from 68 bathing facilities in Japan, by culture, culture with amoebic co-culture, real-time quantitative PCR (qPCR, and real-time qPCR with amoebic co-culture. Using the conventional culture method, Legionella pneumophila was detected in 11 samples (11/68, 16.2%. Contrary to our expectation, the culture method with the amoebic co-culture technique did not increase the detection rate of Legionella (4/68, 5.9%. In contrast, a combination of the amoebic co-culture technique followed by qPCR successfully increased the detection rate (57/68, 83.8% compared with real-time qPCR alone (46/68, 67.6%. Using real-time qPCR after culture with amoebic co-culture, more than 10-fold higher bacterial numbers were observed in 30 samples (30/68, 44.1% compared with the same samples without co-culture. On the other hand, higher bacterial numbers were not observed after propagation by amoebae in 32 samples (32/68, 47.1%. Legionella was not detected in the remaining six samples (6/68, 8.8%, irrespective of the method. These results suggest that application of the amoebic co-culture technique prior to real-time qPCR may be useful for the sensitive detection of Legionella from bath water samples. Furthermore, a combination of amoebic co-culture and real-time qPCR might be useful to detect viable and virulent Legionella because their ability to invade and multiply within free-living amoebae is considered to correlate with their pathogenicity for humans. This is the first report evaluating the efficacy of the amoebic co-culture technique for detecting Legionella in bath water samples.

Survey of Legionella spp. in Mud Spring Recreation Area

Science.gov (United States)

Hsu, B.-M.; Ma, P.-H.; Su, I.-Z.; Chen, N.-S.

2009-04-01

Legionella genera are parasites of FLA, and intracellular bacterial replication within the FLA plays a major role in the transmission of disease. At least 13 FLA species—including Acanthamoeba spp., Naegleria spp., and Hartmannella spp.—support intracellular bacterial replication. In the study, Legionellae were detected with microbial culture or by direct DNA extraction and analysis from concentrated water samples or cultured free-living amoebae, combined with molecular methods that allow the taxonomic identification of these pathogens. The water samples were taken from a mud spring recreation area located in a mud-rock-formation area in southern Taiwan. Legionella were detected in 15 of the 34 samples (44.1%). Four of the 34 samples analyzed by Legionella culture were positive for Legionella, five of 34 were positive for Legionella when analyzed by direct DNA extraction and analysis, and 11 of 34 were positive for amoebae-resistant Legionella when analyzed by FLA culture. Ten samples were shown to be positive for Legionella by one analysis method and five samples were shown to be positive by two analysis methods. However, Legionella was detected in no sample by all three analysis methods. This suggests that the three analysis methods should be used together to detect Legionella in aquatic environments. In this study, L. pneumophila serotype 6 coexisted with A. polyphaga, and two uncultured Legionella spp. coexisted with either H. vermiformis or N. australiensis. Of the unnamed Legionella genotypes detected in six FLA culture samples, three were closely related to L. waltersii and the other three were closely related to L. pneumophila serotype 6. Legionella pneumophila serotype 6, L. drancourtii, and L. waltersii are noted endosymbionts of FLA and are categorized as pathogenic bacteria. This is significant for human health because these Legionella exist within FLA and thus come into contact with typically immunocompromised people.

Static and dynamic modelling of lanthanide and actinide cations in solution

International Nuclear Information System (INIS)

Marjolin, A.

2012-01-01

We propose a theoretical approach, based on both quantum analyses (energy decomposition analysis and topological analysis of the chemical bond) and classical molecular dynamics, for the study of f-element complexes. First, we introduce the different QM methods adapted to the study of f-elements and use them for geometry optimization and interaction energy calculations of the model system [M-(OH 2 )] m+ where M is a lanthanide or actinide cation. We then perform energy decomposition analysis to quantify the physical nature of the metal-ligand interaction in terms of the different contributions. Furthermore, the different energy contributions will be used as reference curves for the parameterization of the polarizable force fields AMOEBA and SIBFA. Next, starting from the optimized geometries, we establish the reference diabatic dissociation curves at high level of theory so as to take into account the multi-reference nature of the systems. These dissociation curves will also be used for parameterization of the AMOEBA potential. We then propose a three step validation protocol as well as a first application, it being the computation of Gibbs hydration free energies for the f-element cations. We also propose an extension of the SIBFA force field to trivalent lanthanide ions and tetravalent actinide ions. Last, we use the topological analysis approaches of ELF and NCI to investigate the nature of the different interactions in Gadolinium(III) model and real systems. The aim of the whole study was to develop and apply different theoretical approaches so as to be able to discriminate between lanthanide and actinide cations. Indeed, despite their similar chemical behavior, they still feature a selective character that we wish to be able to both explain and predict. (author) [fr

Interaction between Mycobacterium avium subsp. paratuberculosis and environmental protozoa

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Rowe Michael T

2006-07-01

Full Text Available Abstract Background Interactions between Mycobacterium avium subsp. paratuberculosis (Map and free-living protozoa in water are likely to occur in nature. The potential impact of ingestion of Map by two naturally occurring Acanthamoeba spp. on this pathogen's survival and chlorine resistance was investigated. Results Between 4.6 and 9.1% of spiked populations of three Map strains (NCTC 8578, B2 and ATCC 19698, which had been added at a multiplicity of infection of 10:1, were ingested by Acanthamoeba castellanii CCAP 1501/1B and A. polyphaga CCAP 1501/3B during co-culture for 3 h at 25°C. Map cells were observed to be present within the vacuoles of the amoebae by acid-fast staining. During extended co-culture of Map NCTC 8578 at 25°C for 24 d with both A. castellanii and A. polyphaga Map numbers did not change significantly during the first 7 days of incubation, however a 1–1.5 log10 increase in Map numbers was observed between days 7 and 24 within both Acanthamoeba spp. Ingested Map cells were shown to be more resistant to chlorine inactivation than free Map. Exposure to 2 μg/ml chlorine for 30 min resulted in a log10 reduction of 0.94 in ingested Map but a log10 reduction of 1.73 in free Map (p Conclusion This study demonstrated that ingestion of Map by and survival and multiplication of Map within Acanthamoeba spp. is possible, and that Map cells ingested by amoebae are more resistant to inactivation by chlorine than free Map cells. These findings have implications with respect to the efficacy of chlorination applied to Map infected surface waters.

Paramecium species ingest and kill the cells of the human pathogenic fungus Cryptococcus neoformans.

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Frager, Shalom Z; Chrisman, Cara J; Shakked, Rachel; Casadevall, Arturo

2010-08-01

A fundamental question in the field of medical mycology is the origin of virulence in those fungal pathogens acquired directly from the environment. In recent years, it was proposed that the virulence of certain environmental animal-pathogenic microbes, such as Cryptococcus neoformans, originated from selection pressures caused by species-specific predation. In this study, we analyzed the interaction of C. neoformans with three Paramecium spp., all of which are ciliated mobile protists. In contrast to the interaction with amoebae, some Paramecium spp. rapidly ingested C. neoformans and killed the fungus. This study establishes yet another type of protist-fungal interaction supporting the notion that animal-pathogenic fungi in the environment are under constant selection by predation.

Entamoeba sp. (Sarcomastigophora: Endamoebidae) from ostriches (Struthio camelus) (Aves: Struthionidae).

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Martínez-Díaz, R A; Herrera, S; Castro, A; Ponce, F

2000-10-01

The first case of Entamoeba of the 1-nucleate mature cyst group in birds is described. Trophozoites and cysts of Entamoeba have been found in ostriches (Struthio camelus) from farms located all over Spain. The cysts are large (13.47microm mean diameter); they possess one nucleus when mature, with a large endosome and peripheral chromatine arranged in small granules; chromatoid bodies, when present, are large and elongated. Trophozoites are large (19. 88microm mean diameter), with a clear differentiation between ecto- and endoplasm, this containing numerous vacuoles; the nucleus is large and diffuse. The characteristics of this amoeba resembles but do not completely fulfill those of E. suis and E. chattoni; also, these species are from mammals.

Is Balamuthia mandrillaris a public health concern worldwide?

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Lorenzo-Morales, Jacob; Cabello-Vílchez, Alfonso Martín; Martín-Navarro, Carmen M; Martínez-Carretero, Enrique; Piñero, José E; Valladares, Basilio

2013-10-01

Balamuthia mandrillaris is an opportunistic, free-living amoeba that can cause skin lesions and the typically fatal Balamuthia amoebic encephalitis (BAE) both in immunocompromised and immunocompetent individuals. Available data for BAE cases indicate that this disease is difficult to detect because knowledge of predisposing factors is lacking, causing a challenge for diagnosing BAE. The number of reported BAE cases is increasing worldwide, and this is a major concern because little is known about the pathogen, no standardized detection tools are available, and most of the treatments are almost empirical. The recently reported cases, novel diagnostics tools, and successful therapeutic approaches against BAE infections are reviewed here. Copyright © 2013 Elsevier Ltd. All rights reserved.

[The National Serum Bank].

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Magos-López, C; Sánchez-Villarreal, F; Gutiérrez, G; Tapia-Conyer, R

1992-01-01

A National Serum Bank was established to store sera obtained during the National Seroepidemiological Survey performed in Mexico in 1987. More than 70,000 serum samples were obtained from subjects of either sex 1-99 years of age in each of the 32 states of the country. The current collection of sera includes 28,704 male samples and 40,629 female samples. This paper describes the procedures for handling serum samples, including reception registry, storage and distribution to several laboratories for detection of measles, rubella, poliomyelitis, AIDS, diphtheria, pertussis, tetanus, brucella, salmonella, amoeba, toxoplasma, American trypanosomiasis and cysticercus. Determinations of total cholesterol were also made in order to describe its distribution and to identify the prevalence of hypercholesterolemia.

Occurrence and Control of Legionella in Recycled Water Systems

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Jjemba, Patrick K.; Johnson, William; Bukhari, Zia; LeChevallier, Mark W.

2015-01-01

Legionella pneumophila is on the United States Environmental Protection Agency (USEPA) Candidate Contaminant list (CCL) as an important pathogen. It is commonly encountered in recycled water and is typically associated with amoeba, notably Naegleria fowleri (also on the CCL) and Acanthamoeba sp. No legionellosis outbreak has been linked to recycled water and it is important for the industry to proactively keep things that way. A review was conducted examine the occurrence of Legionella and its protozoa symbionts in recycled water with the aim of developing a risk management strategy. The review considered the intricate ecological relationships between Legionella and protozoa, methods for detecting both symbionts, and the efficacy of various disinfectants. PMID:26140674

Optimal control for Malaria disease through vaccination

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Munzir, Said; Nasir, Muhammad; Ramli, Marwan

2018-01-01

Malaria is a disease caused by an amoeba (single-celled animal) type of plasmodium where anopheles mosquito serves as the carrier. This study examines the optimal control problem of malaria disease spread based on Aron and May (1982) SIR type models and seeks the optimal solution by minimizing the prevention of the spreading of malaria by vaccine. The aim is to investigate optimal control strategies on preventing the spread of malaria by vaccination. The problem in this research is solved using analytical approach. The analytical method uses the Pontryagin Minimum Principle with the symbolic help of MATLAB software to obtain optimal control result and to analyse the spread of malaria with vaccination control.

The actin cytoskeleton of chemotactic amoebae operates close to the onset of oscillations

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Westendorf, Christian; Negrete, Jose, Jr.; Bae, Albert; Sandmann, Rabea; Bodenschatz, Eberhard; Beta, Carsten

2013-03-01

We report evidence that the actin machinery of chemotactic Dictyostelium cells operates close to an oscillatory instability. The averaged F-actin response of many cells to a short-time pulse of cAMP is reminiscent of a damped oscillation. At the single-cell level, however, the response dynamics ranged from short, strongly damped responses to slowly decaying, weakly damped oscillations. Furthermore, in a small subpopulation, we observed self-sustained oscillations in the cortical F-actin concentration. We systematically exposed a large number of cells to periodic pulse trains. The results indicate a resonance peak at periodic inputs of around 20 s. We propose a delayed feedback model that explains our experimental findings based on a time-delay in the actin regulatory network. To quantitatively test the model, we performed stimulation experiments with cells that express GFP-tagged fusion proteins of Coronin and Aip1. These served as markers of the F-actin disassembly process and thus allow us to estimate the delay time. Based on this independent estimate, our model predicts an intrinsic period of 20 s, which agrees with the resonance observed experimentally. Financial support by the Max-Planck Society and the DFG (SFB 937).

Strains of Uronema marinum (Scuticociliatia) co-isolated with amoebae of the genus Neoparamoeba

Czech Academy of Sciences Publication Activity Database

Dyková, Iva; Tyml, Tomáš; Kostka, Martin; Pecková, Hana

2010-01-01

Roč. 89, č. 1 (2010), s. 71-77 ISSN 0177-5103 R&D Projects: GA ČR GA524/09/0137; GA MŠk LC522 Institutional research plan: CEZ:AV0Z60220518 Keywords : Uronema marinum * SSU rDNA * histophagous strains Subject RIV: GJ - Animal Vermins ; Diseases, Veterinary Medicine Impact factor: 1.572, year: 2010

A polycystin-type transient receptor potential (Trp channel that is activated by ATP

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David Traynor

2017-02-01

Full Text Available ATP and ADP are ancient extra-cellular signalling molecules that in Dictyostelium amoebae cause rapid, transient increases in cytosolic calcium due to an influx through the plasma membrane. This response is independent of hetero-trimeric G-proteins, the putative IP3 receptor IplA and all P2X channels. We show, unexpectedly, that it is abolished in mutants of the polycystin-type transient receptor potential channel, TrpP. Responses to the chemoattractants cyclic-AMP and folic acid are unaffected in TrpP mutants. We report that the DIF morphogens, cyclic-di-GMP, GABA, glutamate and adenosine all induce strong cytoplasmic calcium responses, likewise independently of TrpP. Thus, TrpP is dedicated to purinergic signalling. ATP treatment causes cell blebbing within seconds but this does not require TrpP, implicating a separate purinergic receptor. We could detect no effect of ATP on chemotaxis and TrpP mutants grow, chemotax and develop almost normally in standard conditions. No gating ligand is known for the human homologue of TrpP, polycystin-2, which causes polycystic kidney disease. Our results now show that TrpP mediates purinergic signalling in Dictyostelium and is directly or indirectly gated by ATP.

Multiple identification of most important waterborne protozoa in surface water used for irrigation purposes by 18S rRNA amplicon-based metagenomics.

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Moreno, Y; Moreno-Mesonero, L; Amorós, I; Pérez, R; Morillo, J A; Alonso, J L

2018-01-01

Understanding waterborne protozoan parasites (WPPs) diversity has important implications in public health. In this study, we evaluated a NGS-based method as a detection approach to identify simultaneously most important WPPs using 18S rRNA high-throughput sequencing. A set of primers to target the V4 18S rRNA region of WPPs such as Cryptosporidium spp., Giardia sp., Blastocystis sp., Entamoeba spp, Toxoplasma sp. and free-living amoebae (FLA) was designed. In order to optimize PCR conditions before sequencing, both a mock community with a defined composition of representative WPPs and a real water sample inoculated with specific WPPs DNA were prepared. Using the method proposed in this study, we have detected the presence of Giardia intestinalis, Acanthamoeba castellanii, Toxoplasma gondii, Entamoeba histolytica and Blastocystis sp. at species level in real irrigation water samples. Our results showed that untreated surface irrigation water in open fields can provide an important source of WPPs. Therefore, the methodology proposed in this study can establish a basis for an accurate and effective diagnostic of WPPs to provide a better understanding of the risk associated to irrigation water. Copyright © 2017 The Authors. Published by Elsevier GmbH.. All rights reserved.

Slime moulds use heuristics based on within-patch experience to decide when to leave.

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Latty, Tanya; Beekman, Madeleine

2015-04-15

Animals foraging in patchy, non-renewing or slowly renewing environments must make decisions about how long to remain within a patch. Organisms can use heuristics ('rules of thumb') based on available information to decide when to leave the patch. Here, we investigated proximate patch-departure heuristics in two species of giant, brainless amoeba: the slime moulds Didymium bahiense and Physarum polycephalum. We explicitly tested the importance of information obtained through experience by eliminating chemosensory cues of patch quality. In P. polycephalum, patch departure was influenced by the consumption of high, and to a much lesser extent low, quality food items such that engulfing a food item increased patch-residency time. Physarum polycephalum also tended to forage for longer in darkened, 'safe' patches. In D. bahiense, engulfment of any food item increased patch residency irrespective of that food item's quality. Exposure to light had no effect on the patch-residency time of D. bahiense. Given that these organisms lack a brain, our results illustrate how the use of simple heuristics can give the impression that individuals make sophisticated foraging decisions. © 2015. Published by The Company of Biologists Ltd.

Acanthamoeba keratitis challenges a case report.

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Cristina, Stan; Cristina, Vlăduţiu; Mihaela, Popovici

2016-01-01

Acanthamoeba keratitis is a rare, chronic, mainly contact lens-related infection caused by a free-living amoeba found ubiquitously in water and soil. A case of a 9-year-old child, who presented to our clinic with painful, red left eye, associated with photophobia, and decreased visual acuity, wais reported. The clinical examination revealed a discoid opacity inferiorly bounded by a dense, gray infiltrate. The progressive nature of the corneal infiltrate, the epithelial defect, and the lack of response to treatment was highly suggestive for Acanthamoeba keratitis. The distinctiveness of this case was the presence of Acanthamoeba keratitis in a child without a history of trauma or contact lens usage, the lack of an appropriate diagnosis and management of this vision-threatening infection.

Early detection of protozoan grazers in algal biofuel cultures.

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Day, John G; Thomas, Naomi J; Achilles-Day, Undine E M; Leakey, Raymond J G

2012-06-01

Future micro-algal biofuels will most likely be derived from open-pond production systems. These are by definition open to "invasion" by grazers, which could devastate micro-algal mass-cultures. There is an urgent requirement for methodologies capable of early detection and control of grazers in dense algal cultures. In this study a model system employing the marine alga Nannochloropsis oculata was challenged by grazers including ciliates, amoebae and a heterotrophic dinoflagellate. A FlowCAM flow-cytometer was used to detect all grazers investigated (size range 80 μm in length) in the presence of algae. Detection limits were 1.4 × 10(8) cells ml(-1) (>0.5 g l(-1) dry wt.). Copyright © 2012 Elsevier Ltd. All rights reserved.

Prevalence of amebiasis in inflammatory bowel disease in Turkey.

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Ustun, Sebnem; Dagci, Hande; Aksoy, Umit; Guruz, Yuksel; Ersoz, Galip

2003-08-01

To explore the prevalence of amebiasis in inflammatory bowel disease (IBD) in Turkey. In this study, amoeba prevalence in 160 cases of IBD, 130 of ulcerative colitis and 30 of Crohn's disease were investigated in fresh faeces by means of wet mount+Lugol's iodine staining, modified formol ethyl acetate and trichrome staining methods and to compare the diagnostic accuracy of wet mount+Lugol's iodine staining, modified formol ethyl acetate and trichrome staining methods in the diagnosis of Entamoeba histolytica (E. histolytica)/ Entamoeba dispar (E. dispar). E. histolytica/E. dispar cysts and trophozoites were found in 14 (8.75 %) of a total of 160 cases, 13 (10.0 %) of the 130 patients with ulcerative colitis and 1 (3.3 %) of the 30 patients with Crohn's disease. As for the 105 patients in the control group who had not any gastrointestinal complaints, 2 (1.90 %) patients were found to have E. histolytica /E. dispar cysts in their faeces. Parasite prevalence in the patient group was determined to be significantly higher than that in the control group (Fischer's Exact Test, Pparasites were compared with one another, the most effective one was found to be trichrome staining method (Kruskal-Wallis Test, Pprevalence compared to the normal population. The trichrome staining method is more effective for the detection of E. histolytica /E. dispar than the wet mount+Lugol's iodine staining, modified formol ethyl acetate methods.

Feeding behavior of Frontonia leucas (Ehrenberg (Protozoa, Ciliophora, Hymenostomatida under different environmental conditions in a lotic system Comportamento alimentar de Frontonia leucas (Ehrenberg (Protozoa, Ciliophora, Hymenostomatida sob diferentes condições ambientais em um sistema lótico

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Roberto Júnio P. Dias

2006-09-01

Full Text Available The objective of this study was to record and describe the morphological changes and the ingestion mechanisms of Frontonia leucas (Ehrenberg, 1833 according to the food type and to relate the food ingested with the different environmental conditions in a lotic system, namely São Pedro stream, located in the municipality of Juiz de Fora, Minas Gerais, Brazil. We sampled three points on a monthly basis from August 2002 to June 2003, each of which receiving different levels of untreated sewage. We prepared culture media for the ciliate specimens containing filtered water from each point and the types of food observed inside F. leucas (cyanobacteria, diatoms, desmids and testate amoebas. We observed the ingestion mechanisms of F. leucas in vivo, under a phase contrast optical microscope, using instantaneous sampling and sequence sampling as behavior observation methods, noting the following parameters: dissolved oxygen concentration, pH, conductivity and water temperature. We noted the F. leucas ciliates ingesting diatoms and desmids at collection point 1 and filamentous cyanobacteria, testate amoebas (Arcella and Centropyxis and rotifers at points 2 and 3. The present work records for the first time the ingestion of testate amoebas of the genus Centropyxis by F. leucas. We noted five ingestion mechanisms by F. leucas while feeding on cyanobacteria and testate amoebas of the genus Centropyxis, three of these related to the ciliary action and two involving physical changes in the cytoplasm. For ingestion of diatoms, desmid (Closterium and Arcella, the mechanisms involving ciliary action alone were sufficient for ingestion, since these preys are smaller than the ciliate under study. The autecological data registered for F. leucas were 1.98-8.01 mg l-1 O2, pH 6.9-8.73, 58-390 µS/cm and 19.5-26.2ºC, confirming its ample ecological valence.O objetivo do presente trabalho foi registrar e descrever as alterações morfológicas e os mecanismos de ingest

Genome Segregation and Packaging Machinery in Acanthamoeba polyphaga Mimivirus Is Reminiscent of Bacterial Apparatus

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Chelikani, Venkata; Ranjan, Tushar; Zade, Amrutraj; Shukla, Avi

2014-01-01

ABSTRACT Genome packaging is a critical step in the virion assembly process. The putative ATP-driven genome packaging motor of Acanthamoeba polyphaga mimivirus (APMV) and other nucleocytoplasmic large DNA viruses (NCLDVs) is a distant ortholog of prokaryotic chromosome segregation motors, such as FtsK and HerA, rather than other viral packaging motors, such as large terminase. Intriguingly, APMV also encodes other components, i.e., three putative serine recombinases and a putative type II topoisomerase, all of which are essential for chromosome segregation in prokaryotes. Based on our analyses of these components and taking the limited available literature into account, here we propose for the first time a model for genome segregation and packaging in APMV that can possibly be extended to NCLDV subfamilies, except perhaps Poxviridae and Ascoviridae. This model might represent a unique variation of the prokaryotic system acquired and contrived by the large DNA viruses of eukaryotes. It is also consistent with previous observations that unicellular eukaryotes, such as amoebae, are melting pots for the advent of chimeric organisms with novel mechanisms. IMPORTANCE Extremely large viruses with DNA genomes infect a wide range of eukaryotes, from human beings to amoebae and from crocodiles to algae. These large DNA viruses, unlike their much smaller cousins, have the capability of making most of the protein components required for their multiplication. Once they infect the cell, these viruses set up viral replication centers, known as viral factories, to carry out their multiplication with very little help from the host. Our sequence analyses show that there is remarkable similarity between prokaryotes (bacteria and archaea) and large DNA viruses, such as mimivirus, vaccinia virus, and pandoravirus, in the way that they process their newly synthesized genetic material to make sure that only one copy of the complete genome is generated and is meticulously placed inside

Frequency of Intestinal Parasites in Patients With Gastrointestinal Disorders, in Different Parts of Iran During 2012-2013

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Nozhat Zebardast

2015-02-01

Full Text Available Background: Intestinal parasites of humans are one of the most important health problems worldwide, especially those located in tropical and subtropical areas. Objectives: The aim of this study was to determine the frequency of intestinal parasites in patients with gastrointestinal disorders, in different parts of Iran. Patients and Methods: A total of 1520 stool samples were collected from patients with gastrointestinal disorders. The stool specimens were examined by direct wet mount, formalin-ether concentration and a modified version of the Ziehl-Neelsen staining technique. Amoeba-positive samples were cultured for further differentiation of Entamoeba histolytica, E. dispar, E. moshkovskii. DNA-based methods were used to differentiate these amoebas and to detect Cryptosporidium- positive samples. Statistical analysis was carried out by SPSS ver. 16. Results: Out of the 1520 individuals studied, 153 (10.06% were infected at least with one intestinal parasite. 781 (51.4% of patients were male and 738 (48.6% were female. The prevalence of protozoan parasites 148 (9.7% was significantly higher than helminth parasites 5 (0.3% (P < 0.001. The frequency of intestinal parasites was as follows: Blastocystis sp., 72 (4.73%; Giardia intestinalis, 35 (2.30%; Entamoeba coli 21 (1.38%; Endolimax nana 10 (0.92%; Cryptosporidium spp., 1 (0.06%; Entamoeba dispar, 1 (0.06%; Dientamoeba fragilis, 1 (0.06%; Hymenolepis nana, 3 (0.19%; Dicrocoelium dendriticum, 2 (0.13%. In five (0.32% of the positive samples, co-infections with two parasites were found. G. intestinalis was more prevalent in male 22/35 (62.86% than female 13/35 (37.14% as well as in 0-9 years old group. In one sample Heterodera ova contained larva were seen. Conclusions: Blastocystis and G. intestinalis were the predominant intestinal parasites detected in patient with gastrointestinal disorders. The results indicated that the intestinal parasites, particularly helminth infections have been

Identification of unusual phospholipid fatty acyl compositions of Acanthamoeba castellanii.

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Marta Palusinska-Szysz

Full Text Available Acanthamoeba are opportunistic protozoan pathogens that may lead to sight-threatening keratitis and fatal granulomatous encephalitis. The successful prognosis requires early diagnosis and differentiation of pathogenic Acanthamoeba followed by aggressive treatment regimen. The plasma membrane of Acanthamoeba consists of 25% phospholipids (PL. The presence of C20 and, recently reported, 28- and 30-carbon fatty acyl residues is characteristic of amoeba PL. A detailed knowledge about this unusual PL composition could help to differentiate Acanthamoeba from other parasites, e.g. bacteria and develop more efficient treatment strategies. Therefore, the detailed PL composition of Acanthamoeba castellanii was investigated by 31P nuclear magnetic resonance spectroscopy, thin-layer chromatography, gas chromatography, high performance liquid chromatography and liquid chromatography-mass spectrometry. Normal and reversed phase liquid chromatography coupled with mass spectrometric detection was used for detailed characterization of the fatty acyl composition of each detected PL. The most abundant fatty acyl residues in each PL class were octadecanoyl (18∶0, octadecenoyl (18∶1 Δ9 and hexadecanoyl (16∶0. However, some selected PLs contained also very long fatty acyl chains: the presence of 28- and 30-carbon fatty acyl residues was confirmed in phosphatidylethanolamine (PE, phosphatidylserine, phosphatidic acid and cardiolipin. The majority of these fatty acyl residues were also identified in PE that resulted in the following composition: 28∶1/20∶2, 30∶2/18∶1, 28∶0/20∶2, 30∶2/20∶4 and 30∶3/20∶3. The PL of amoebae are significantly different in comparison to other cells: we describe here for the first time unusual, very long chain fatty acids with Δ5-unsaturation (30∶35,21,24 and 30∶221,24 localized exclusively in specific phospholipid classes of A. castellanii protozoa that could serve as specific biomarkers for the presence of

Variation, sex, and social cooperation: molecular population genetics of the social amoeba Dictyostelium discoideum.

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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.

Antimycobacterial drug discovery using Mycobacteria-infected amoebae identifies anti-infectives and new molecular targets.

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Trofimov, Valentin; Kicka, Sébastien; Mucaria, Sabrina; Hanna, Nabil; Ramon-Olayo, Fernando; Del Peral, Laura Vela-Gonzalez; Lelièvre, Joël; Ballell, Lluís; Scapozza, Leonardo; Besra, Gurdyal S; Cox, Jonathan A G; Soldati, Thierry

2018-03-02

Tuberculosis remains a serious threat to human health world-wide, and improved efficiency of medical treatment requires a better understanding of the pathogenesis and the discovery of new drugs. In the present study, we performed a whole-cell based screen in order to complete the characterization of 168 compounds from the GlaxoSmithKline TB-set. We have established and utilized novel previously unexplored host-model systems to characterize the GSK compounds, i.e. the amoeboid organisms D. discoideum and A. castellanii, as well as a microglial phagocytic cell line, BV2. We infected these host cells with Mycobacterium marinum to monitor and characterize the anti-infective activity of the compounds with quantitative fluorescence measurements and high-content microscopy. In summary, 88.1% of the compounds were confirmed as antibiotics against M. marinum, 11.3% and 4.8% displayed strong anti-infective activity in, respectively, the mammalian and protozoan infection models. Additionally, in the two systems, 13-14% of the compounds displayed pro-infective activity. Our studies underline the relevance of using evolutionarily distant pathogen and host models in order to reveal conserved mechanisms of virulence and defence, respectively, which are potential "universal" targets for intervention. Subsequent mechanism of action studies based on generation of over-expresser M. bovis BCG strains, generation of spontaneous resistant mutants and whole genome sequencing revealed four new molecular targets, including FbpA, MurC, MmpL3 and GlpK.

Numerical trials of HISSE

Science.gov (United States)

Peters, C.; Kampe, F. (Principal Investigator)

1980-01-01

The mathematical description and implementation of the statistical estimation procedure known as the Houston integrated spatial/spectral estimator (HISSE) is discussed. HISSE is based on a normal mixture model and is designed to take advantage of spectral and spatial information of LANDSAT data pixels, utilizing the initial classification and clustering information provided by the AMOEBA algorithm. The HISSE calculates parametric estimates of class proportions which reduce the error inherent in estimates derived from typical classify and count procedures common to nonparametric clustering algorithms. It also singles out spatial groupings of pixels which are most suitable for labeling classes. These calculations are designed to aid the analyst/interpreter in labeling patches with a crop class label. Finally, HISSE's initial performance on an actual LANDSAT agricultural ground truth data set is reported.

How discordant morphological and molecular evolution among microorganisms can revise our notions of biodiversity on earth

Science.gov (United States)

Lahr, Daniel J. G.; Laughinghouse, H. Dail; Oliverio, Angela; Gao, Feng; Katz, Laura A.

2014-01-01

Microscopy has revealed a tremendous diversity of bacterial and eukaryotic forms. More recent molecular analyses show discordance in estimates of biodiversity based on morphological analyses. Moreover, phylogenetic analyses of the diversity of microbial forms have revealed evidence of convergence at scales as large as interdomain – i.e. convergent forms shared between bacteria and eukaryotes. Here, we highlight examples of such discordance, focusing on exemplary lineages such as testate amoebae, ciliates and cyanobacteria, which have long histories of morphological study. We discuss examples in two categories: 1) morphologically identical (or highly similar) individuals that are genetically distinct and 2) morphologically distinct individuals that are genetically distinct. We argue that hypotheses about discordance can be tested using the concept of neutral morphologies, or more broadly neutral phenotypes, as a null hypothesis. PMID:25156897

Naegleria fowleri in thermally polluted waters

Energy Technology Data Exchange (ETDEWEB)

Kasprzak, W; Mazur, T; Cerva, L

1982-01-01

Two complexes of lakes and canals supplying water for two electric power plants, their steam condensors and an adjoining river were investigated by means of culture methods for the presence of Naegleria fowleri in Poland in the period from 1974 to 1980. Sixty-four strains of N. fowleri were isolated, 13 isolates being virulent for mice when instilled intranasally. These strains were found in the steam condensor of the power station A and in waters polluted with warm water of this plant. Pathogenic N. fowleri strains occurred also in an adjoining river connected with the water system of the power plant. The results show the possible role of the steam condensor A as an incubator and regular source of pollution with pathogenic amoebae for its own system of cooling waters and even the adjoining river.

The impact of the fungicide fenpropimorph (Corbel) on bacterivorous and fungivorous protozoa in soil

DEFF Research Database (Denmark)

Ekelund, Flemming

1999-01-01

1. The ability of indigenous soil protozoa to survive and multiply when exposed to various concentrations of the fungicide fenpropimorph was investigated. The number of protozoan taxa in relation to biocide concentration was examined in enrichment cultures. The population dynamics of bacterivorous...... and fungivorous protozoa, hyphal forming units, and respiration activity were followed in soil microcosms amended with glucose and various concentrations of fenpropimorph. 2. The average number of flagellate taxa detected in 50-mg portions of air-dried soil declined from 12 to zero with fenpropimorph...... as in systems with glucose only; however, soil respiration was significantly impeded in microcosm systems with a low pesticide content and stimulated in systems with a high pesticide content. 4. Bacterivorous protozoa (naked amoebae and heterotrophic flagellates) were affected at all tested concentrations (074...

Risk Assessment for the Spread of Serratia marcescens Within Dental-Unit Waterline Systems Using Vermamoeba vermiformis.

Science.gov (United States)

Lal, Sham; Singhrao, Sim K; Achilles-Day, Undine E M; Morton, L H Glyn; Pearce, Mark; Crean, StJohn

2015-10-01

Vermamoeba vermiformis is associated with the biofilm ecology of dental-unit waterlines (DUWLs). This study investigated whether V. vermiformis is able to act as a vector for potentially pathogenic bacteria and so aid their dispersal within DUWL systems. Clinical dental water was initially examined for Legionella species by inoculating it onto Legionella selective-medium plates. The molecular identity/profile of the glassy colonies obtained indicated none of these isolates were Legionella species. During this work bacterial colonies were identified as a non-pigmented Serratia marcescens. As the water was from a clinical DUWL which had been treated with Alpron™, this prompted the question as to whether S. marcescens had developed resistance to the biocide. Exposure to Alpron™ indicated that this dental biocide was effective, under laboratory conditions, against S. marcescens at up to 1 × 10(8) colony forming units/millilitre (cfu/ml). V. vermiformis was cultured for 8 weeks on cells of S. marcescens and Escherichia coli. Subsequent electron microscopy showed that V. vermiformis grew equally well on S. marcescens and E. coli (P = 0.0001). Failure to detect the presence of S. marcescens within the encysted amoebae suggests that V. vermiformis is unlikely to act as a vector supporting the growth of this newly isolated, nosocomial bacterium.

An unexpected role for mixotrophs in the response of peatland carbon cycling to climate warming.

Science.gov (United States)

Jassey, Vincent E J; Signarbieux, Constant; Hättenschwiler, Stephan; Bragazza, Luca; Buttler, Alexandre; Delarue, Frédéric; Fournier, Bertrand; Gilbert, Daniel; Laggoun-Défarge, Fatima; Lara, Enrique; Mills, Robert T E; Mitchell, Edward A D; Payne, Richard J; Robroek, Bjorn J M

2015-11-25

Mixotrophic protists are increasingly recognized for their significant contribution to carbon (C) cycling. As phototrophs they contribute to photosynthetic C fixation, whilst as predators of decomposers, they indirectly influence organic matter decomposition. Despite these direct and indirect effects on the C cycle, little is known about the responses of peatland mixotrophs to climate change and the potential consequences for the peatland C cycle. With a combination of field and microcosm experiments, we show that mixotrophs in the Sphagnum bryosphere play an important role in modulating peatland C cycle responses to experimental warming. We found that five years of consecutive summer warming with peaks of +2 to +8°C led to a 50% reduction in the biomass of the dominant mixotrophs, the mixotrophic testate amoebae (MTA). The biomass of other microbial groups (including decomposers) did not change, suggesting MTA to be particularly sensitive to temperature. In a microcosm experiment under controlled conditions, we then manipulated the abundance of MTA, and showed that the reported 50% reduction of MTA biomass in the field was linked to a significant reduction of net C uptake (-13%) of the entire Sphagnum bryosphere. Our findings suggest that reduced abundance of MTA with climate warming could lead to reduced peatland C fixation.

Revisiting the Acanthamoeba species that form star-shaped cysts (genotypes T7, T8, T9, and T17): characterization of seven new Brazilian environmental isolates and phylogenetic inferences.

Science.gov (United States)

Magliano, Ana C M; Teixeira, Marta M G; Alfieri, Silvia C

2012-01-01

Free-living amoebae of the genus Acanthamoeba are the agents of both opportunistic and non-opportunistic infections and are frequently isolated from the environment. Of the 17 genotypes (T1-T17) identified thus far, 4 (T7, T8, T9, and T17) accommodate the rarely investigated species of morphological group I, those that form large, star-shaped cysts. We report the isolation and characterization of 7 new Brazilian environmental Acanthamoeba isolates, all assigned to group I. Phylogenetic analyses based on partial (~1200 bp) SSU rRNA gene sequences placed the new isolates in the robustly supported clade composed of the species of morphological group I. One of the Brazilian isolates is closely related to A. comandoni (genotype T9), while the other 6, together with 2 isolates recently assigned to genotype T17, form a homogeneous, well-supported group (2·0% sequence divergence) that likely represents a new Acanthamoeba species. Thermotolerance, osmotolerance, and cytophatic effects, features often associated with pathogenic potential, were also examined. The results indicated that all 7 Brazilian isolates grow at temperatures up to 40°C, and resist under hyperosmotic conditions. Additionally, media conditioned by each of the new Acanthamoeba isolates induced the disruption of SIRC and HeLa cell monolayers.

Neutrophil and Alveolar Macrophage-Mediated Innate Immune Control of Legionella pneumophila Lung Infection via TNF and ROS.

Directory of Open Access Journals (Sweden)

Pascal Ziltener

2016-04-01

Full Text Available Legionella pneumophila is a facultative intracellular bacterium that lives in aquatic environments where it parasitizes amoeba. However, upon inhalation of contaminated aerosols it can infect and replicate in human alveolar macrophages, which can result in Legionnaires' disease, a severe form of pneumonia. Upon experimental airway infection of mice, L. pneumophila is rapidly controlled by innate immune mechanisms. Here we identified, on a cell-type specific level, the key innate effector functions responsible for rapid control of infection. In addition to the well-characterized NLRC4-NAIP5 flagellin recognition pathway, tumor necrosis factor (TNF and reactive oxygen species (ROS are also essential for effective innate immune control of L. pneumophila. While ROS are essential for the bactericidal activity of neutrophils, alveolar macrophages (AM rely on neutrophil and monocyte-derived TNF signaling via TNFR1 to restrict bacterial replication. This TNF-mediated antibacterial mechanism depends on the acidification of lysosomes and their fusion with L. pneumophila containing vacuoles (LCVs, as well as caspases with a minor contribution from cysteine-type cathepsins or calpains, and is independent of NLRC4, caspase-1, caspase-11 and NOX2. This study highlights the differential utilization of innate effector pathways to curtail intracellular bacterial replication in specific host cells upon L. pneumophila airway infection.

Iron economy in Naegleria gruberi reflects its metabolic flexibility.

Science.gov (United States)

Mach, Jan; Bíla, Jarmila; Ženíšková, Kateřina; Arbon, Dominik; Malych, Ronald; Glavanakovová, Marie; Nývltová, Eva; Sutak, Robert

2018-05-05

Naegleria gruberi is a free-living amoeba, closely related to the human pathogen Naegleria fowleri, the causative agent of the deadly human disease primary amoebic meningoencephalitis. Herein, we investigated the effect of iron limitation on different aspects of N. gruberi metabolism. Iron metabolism is among the most conserved pathways found in all eukaryotes. It includes the delivery, storage and utilisation of iron in many cell processes. Nevertheless, most of the iron metabolism pathways of N. gruberi are still not characterised, even though iron balance within the cell is crucial. We found a single homolog of ferritin in the N. gruberi genome and showed its localisation in the mitochondrion. Using comparative mass spectrometry, we identified 229 upregulated and 184 down-regulated proteins under iron-limited conditions. The most down-regulated protein under iron-limited conditions was hemerythrin, and a similar effect on the expression of hemerythrin was found in N. fowleri. Among the other down-regulated proteins were [FeFe]-hydrogenase and its maturase HydG and several heme-containing proteins. The activities of [FeFe]-hydrogenase, as well as alcohol dehydrogenase, were also decreased by iron deficiency. Our results indicate that N. gruberi is able to rearrange its metabolism according to iron availability, prioritising mitochondrial pathways. We hypothesise that the mitochondrion is the center for iron homeostasis in N. gruberi, with mitochondrially localised ferritin as a potential key component of this process. Copyright © 2018 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.

Yersinia outer protein YopE affects the actin cytoskeleton in Dictyostelium discoideum through targeting of multiple Rho family GTPases

LENUS (Irish Health Repository)

Vlahou, Georgia

2009-07-14

Abstract Background All human pathogenic Yersinia species share a virulence-associated type III secretion system that translocates Yersinia effector proteins into host cells to counteract infection-induced signaling responses and prevent phagocytosis. Dictyostelium discoideum has been recently used to study the effects of bacterial virulence factors produced by internalized pathogens. In this study we explored the potential of Dictyostelium as model organism for analyzing the effects of ectopically expressed Yersinia outer proteins (Yops). Results The Yersinia pseudotuberculosis virulence factors YopE, YopH, YopM and YopJ were expressed de novo within Dictyostelium and their effects on growth in axenic medium and on bacterial lawns were analyzed. No severe effect was observed for YopH, YopJ and YopM, but expression of YopE, which is a GTPase activating protein for Rho GTPases, was found to be highly detrimental. GFP-tagged YopE expressing cells had less conspicuous cortical actin accumulation and decreased amounts of F-actin. The actin polymerization response upon cAMP stimulation was impaired, although chemotaxis was unaffected. YopE also caused reduced uptake of yeast particles. These alterations are probably due to impaired Rac1 activation. We also found that YopE predominantly associates with intracellular membranes including the Golgi apparatus and inhibits the function of moderately overexpressed RacH. Conclusion The phenotype elicited by YopE in Dictyostelium can be explained, at least in part, by inactivation of one or more Rho family GTPases. It further demonstrates that the social amoeba Dictyostelium discoideum can be used as an efficient and easy-to-handle model organism in order to analyze the function of a translocated GAP protein of a human pathogen.

Label-free imaging of acanthamoeba using multimodal nonlinear optical microscopy

Science.gov (United States)

Kobayashi, Tsubasa; Cha, Yu-Rok; Kaji, Yuichi; Oshika, Tetsuro; Leproux, Philippe; Couderc, Vincent; Kano, Hideaki

2018-02-01

Acanthamoeba keratitis is a disease in which amoebae named Acanthamoeba invade the cornea of an eye. To diagnose this disease before it becomes serious, it is important to detect the cyst state of Acanthamoeba in the early stage of infection. In the present study, we explored spectroscopic signitures of the cyst state of Acanthamoeba using multimodal nonlinear optical microscopy with the channels of multiplex coherent anti-Stokes Raman scattering (CARS), second harmonic generation (SHG), and third harmonic generation (THG). A sharp band at around 1603 cm-1 in the CARS (Im[χ(3)]) spectrum was found at the cyst state of Acanthamoeba, which possibly originates from ergosterol and/or 7-dehydrostigmasterol. It can be used as a maker band of Acanthamoeba for medical treatment. Keyword: Acanthamoeba keratitis, coherent anti-Stokes Raman scattering, CARS, second harmonic generation, SHG, microspectroscopy, multiphoton microscopy

A flavin-dependent halogenase catalyzes the chlorination step in the biosynthesis of Dictyostelium differentiation-inducing factor 1.

Science.gov (United States)

Neumann, Christopher S; Walsh, Christopher T; Kay, Robert R

2010-03-30

Differentiation-inducing factor 1 (DIF-1) is a polyketide-derived morphogen which drives stalk cell formation in the developmental cycle of Dictyostelium discoideum. Previous experiments demonstrated that the biosynthetic pathway proceeds via dichlorination of the precursor molecule THPH, but the enzyme responsible for this transformation has eluded characterization. Our recent studies on prokaryotic flavin-dependent halogenases and insights from the sequenced Dd genome led us to a candidate gene for this transformation. In this work, we present in vivo and in vitro evidence that chlA from Dd encodes a flavin-dependent halogenase capable of catalyzing both chlorinations in the biosynthesis of DIF-1. The results provide in vitro characterization of a eukaryotic oxygen-dependent halogenase and demonstrate a broad reach in biology for this molecular tailoring strategy, notably its involvement in the differentiation program of a social amoeba.

Soil fauna communities and microbial respiration in high Arctic tundra soils at Zackenberg, Northeast Greenland

DEFF Research Database (Denmark)

Sørensen, Louise I.; Holmstrup, Martin; Maraldo, Kristine

2006-01-01

The soil fauna communities were described for three dominant vegetation types in a high arctic site at Zackenberg, Northeast Greenland. Soil samples were extracted to quantify the densities of mites, collembolans, enchytraeids, diptera larvae, nematodes and protozoa. Rates of microbial respiration...... densities (naked amoeba and heterotrophic flagellates) were equal. Respiration rate of unamended soil was similar in soil from the three plots. However, a higher respiration rate increase in carbon + nutrient amended soil and the higher densities of soil fauna (with the exception of mites and protozoa...... were also assessed. Collembolans were found in highest densities in dry heath soil, about 130,000 individuals m-2, more than twice as high as in mesic heath soils. Enchytraeids, diptera larvae and nematodes were also more abundant in the dry heath soil than in mesic heath soils, whereas protozoan...

Exploiting amoeboid and non-vertebrate animal model systems to study the virulence of human pathogenic fungi.

Science.gov (United States)

Mylonakis, Eleftherios; Casadevall, Arturo; Ausubel, Frederick M

2007-07-27

Experiments with insects, protozoa, nematodes, and slime molds have recently come to the forefront in the study of host-fungal interactions. Many of the virulence factors required for pathogenicity in mammals are also important for fungal survival during interactions with non-vertebrate hosts, suggesting that fungal virulence may have evolved, and been maintained, as a countermeasure to environmental predation by amoebae and nematodes and other small non-vertebrates that feed on microorganisms. Host innate immune responses are also broadly conserved across many phyla. The study of the interaction between invertebrate model hosts and pathogenic fungi therefore provides insights into the mechanisms underlying pathogen virulence and host immunity, and complements the use of mammalian models by enabling whole-animal high throughput infection assays. This review aims to assist researchers in identifying appropriate invertebrate systems for the study of particular aspects of fungal pathogenesis.

Protists from a sewage‐contaminated aquifer on cape cod, Massachusetts

Science.gov (United States)

Novarino, Gianfranco; Warren, Alan; Kinner, Nancy E.; Harvey, Ronald W.

1994-01-01

Several species of flagellates (genera Bodo, Cercomonas, Cryptaulax, Cyathomonas, Goniomonas, Spumella) have been identified in cultures from a plume of organic contamination (treated sewage effluent) within an aquifer on Cape Cod, Massachusetts. Amoebae and numerous unidentifiable 2‐ to 3‐μm flagellates have also been observed. As a rule, flagellates were associated with solid surfaces, or were capable of temporary surface attachment, corroborating earlier observations from in situ and column transport experiments suggesting that protists in the Massachusetts aquifer have a high propensity for association with sediment grain surfaces. Based on the fact that cultures from the uncontaminated part of the aquifer yielded only a few species of protists, it is hypothesized that the greater abundance and variety of food sources in the contaminant plume is capable of supporting a greater number of protistan species.

Aerobic mitochondria of parasitic protists: Diverse genomes and complex functions.

Science.gov (United States)

Zíková, Alena; Hampl, Vladimír; Paris, Zdeněk; Týč, Jiří; Lukeš, Julius

In this review the main features of the mitochondria of aerobic parasitic protists are discussed. While the best characterized organelles are by far those of kinetoplastid flagellates and Plasmodium, we also consider amoebae Naegleria and Acanthamoeba, a ciliate Ichthyophthirius and related lineages. The simplistic view of the mitochondrion as just a power house of the cell has already been abandoned in multicellular organisms and available data indicate that this also does not apply for protists. We discuss in more details the following mitochondrial features: genomes, post-transcriptional processing, translation, biogenesis of iron-sulfur complexes, heme metabolism and the electron transport chain. Substantial differences in all these core mitochondrial features between lineages are compatible with the view that aerobic protists harbor organelles that are more complex and flexible than previously appreciated. Copyright © 2016 Elsevier B.V. All rights reserved.

TM9 and cannibalism: how to learn more about cancer by studying amoebae and invertebrates.

Science.gov (United States)

Fais, Stefano; Fauvarque, Marie-Odile

2012-01-01

Phagocytosis is used not only for immune defense but may also be used to obtain nutrients, as observed when tumor cells feed upon neighboring cells during "tumor cell cannibalism". The TM9 protein TM9SF4, important in canonical phagocytosis, is involved in this cannibalism by metastatic cells and may represent a novel therapeutic target. Copyright © 2011 Elsevier Ltd. All rights reserved.

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.

Heterolobosean amoebae from Arctic and Antarctic extremes: 18 novel strains of Allovahlkampfia, Vahlkampfia and Naegleria

Czech Academy of Sciences Publication Activity Database

Tyml, Tomáš; Skulinová, K.; Kavan, J.; Ditrich, O.; Kostka, M.; Dyková, I.

2016-01-01

Roč. 56, October (2016), s. 119-133 ISSN 0932-4739 R&D Projects: GA ČR(CZ) GBP505/12/G112 Institutional support: RVO:60077344 Keywords : Arctic * Antarctic * Heterolobosea * Molecular taxonomy * Tetramitia Subject RIV: GJ - Animal Vermins ; Diseases, Veterinary Medicine Impact factor: 2.581, year: 2016

Co-isolation of Vahlkampfia and acanthamoeba in acanthamoeba-like keratitis in a Spanish population.

Science.gov (United States)

Arnalich-Montiel, Francisco; Lorenzo-Morales, Jacob; Irigoyen, Cristina; Morcillo-Laiz, Rafael; López-Vélez, Rogelio; Muñoz-Negrete, Francisco; Piñero, Jose E; Valladares, Basilio

2013-05-01

To report the co-isolation incidence of Acanthamoeba and Vahlkampfia in amoebic keratitis from a tertiary care institution in Madrid, Spain. In this retrospective case series, 7 eyes of 7 consecutive patients with culture-proven or polymerase chain reaction-positive Acanthamoeba keratitis were seen at a tertiary care institution from January 2010 to April 2011, and their charts were reviewed. Two of 7 patients showed mixed Acanthamoeba and Vahlkampfia keratitis. Good clinical response to the treatment was strongly correlated with early diagnosis, whereas delayed diagnosis resulted in poor response to the treatment in single or mixed infection. Co-isolation of Vahlkampfia and Acanthamoeba in Acanthamoeba-like keratitis has recently been detected in our population. This finding should raise awareness of the existence of other amoeba different from Acanthamoeba causing keratitis. There are not enough cases yet to determine the impact of mixed amoebic keratitis in the prognosis of this disease.

RNase P RNA from the Recently Evolved Plastid of Paulinella and from Algae

Directory of Open Access Journals (Sweden)

Pilar Bernal-Bayard

2014-11-01

Full Text Available The RNase P RNA catalytic subunit (RPR encoded in some plastids has been found to be functionally defective. The amoeba Paulinella chromatophora contains an organelle (chromatophore that is derived from the recent endosymbiotic acquisition of a cyanobacterium, and therefore represents a model of the early steps in the acquisition of plastids. In contrast with plastid RPRs the chromatophore RPR retains functionality similar to the cyanobacterial enzyme. The chromatophore RPR sequence deviates from consensus at some positions but those changes allow optimal activity compared with mutated chromatophore RPR with the consensus sequence. We have analyzed additional RPR sequences identifiable in plastids and have found that it is present in all red algae and in several prasinophyte green algae. We have assayed in vitro a subset of the plastid RPRs not previously analyzed and confirm that these organelle RPRs lack RNase P activity in vitro.

Potential role of bacteria packaging by protozoa in the persistence and transmission of pathogenic bacteria

Directory of Open Access Journals (Sweden)

Alix M Denoncourt

2014-05-01

Full Text Available Many pathogenic bacteria live in close association with protozoa. These unicellular eukaryotic microorganisms are ubiquitous in various environments. A number of protozoa such as amoebae and ciliates ingest pathogenic bacteria, package them usually in membrane structures, and then release them into the environment. Packaged bacteria are more resistant to various stresses and are more apt to survive than free bacteria. New evidence indicates that protozoa and not bacteria control the packaging process. It is possible that packaging is more common than suspected and may play a major role in the persistence and transmission of pathogenic bacteria. To confirm the role of packaging in the propagation of infections, it is vital that the molecular mechanisms governing the packaging of bacteria by protozoa be identified as well as elements related to the ecology of this process in order to determine whether packaging acts as a Trojan Horse.

Biomimetics in Modern Organizations – Laws or Metaphors?

Directory of Open Access Journals (Sweden)

Markus Schatten

2011-06-01

Full Text Available Biomimetics, the art and science of imitating nature and life for technological solutions is discussed from a modern organization theory perspective. The main hypothesis of this article is that there are common laws in nature that are applicable to living, social and likewise organizational systems. To take advantage of these laws, the study of nature’s principles for their application to organizations is proposed – a process which is in product and technology design known as bionic creativity engineering. In a search for most interesting concepts borrowed from nature we found amoeba organizations, the theory of autopoiesis or self-creation, neural networks, heterarchies, as well as fractals and bioteaming which are described and reviewed. Additionally other concepts like swarm intelligence, stigmergy, as well as genesis and reproduction, are introduced. In the end all these ideas are summarized and guidelines for further research are given.

Exploiting amoeboid and non-vertebrate animal model systems to study the virulence of human pathogenic fungi.

Directory of Open Access Journals (Sweden)

Eleftherios Mylonakis

2007-07-01

Full Text Available Experiments with insects, protozoa, nematodes, and slime molds have recently come to the forefront in the study of host-fungal interactions. Many of the virulence factors required for pathogenicity in mammals are also important for fungal survival during interactions with non-vertebrate hosts, suggesting that fungal virulence may have evolved, and been maintained, as a countermeasure to environmental predation by amoebae and nematodes and other small non-vertebrates that feed on microorganisms. Host innate immune responses are also broadly conserved across many phyla. The study of the interaction between invertebrate model hosts and pathogenic fungi therefore provides insights into the mechanisms underlying pathogen virulence and host immunity, and complements the use of mammalian models by enabling whole-animal high throughput infection assays. This review aims to assist researchers in identifying appropriate invertebrate systems for the study of particular aspects of fungal pathogenesis.

Evidence for Chlamydiaceae and Parachlamydiaceae in a wild boar (Sus scrofa population in Italy

Directory of Open Access Journals (Sweden)

Antonietta Di Francesco

2013-03-01

Full Text Available Conjunctival swabs from 44 free-living wild boars culled during a demographic control programme applied in a Regional Park located in the Northern Italy were examined by 16S rRNA encoding gene nested PCR. In total, 22 (50% wild boars were PCR positive. Sequencing of the amplicons identified Chlamydia suis and Chlamydia pecorum in 12 and 5 samples, respectively. For one sample found PCR positive, the nucleotide sequence could not be determined. Four conjunctival samples showed ≥ 92% sequence similarities to 16S rRNA sequences from Chlamydia-like organisms, as did large intestine, uterus, and vaginal swabs from the same four animals. Amoeba DNA was found in one Chlamydia-like organism positive conjunctival swab. To our knowledge, this is the first detection of members of the Parachlamydiaceae family in wild boars, confirming a large animal host range for Chlamydia-like organisms.

Hospital hydrotherapy pools treated with ultra violet light: bad bacteriological quality and presence of thermophilic Naegleria.

Science.gov (United States)

De Jonckheere, J. F.

1982-01-01

The microbiological quality of eight halogenated and two u.v.-treated hydrotherapy pools in hospitals was investigated. The microbiological quality of halogenated hydrotherapy pools was comparable to halogenated public swimming pools, although in some Pseudomonas aeruginosa and faecal pollution indicators were more frequent due to bad management. On the other hand u.v.-treated hydrotherapy pools had very bad microbiological quality. Apart from faecal pollution indicators, P. aeruginosa was present in very high numbers. Halogenated hydrotherapy pools were not highly contaminated with amoebae, and Naegleria spp. were never detected. On the other hand u.v.-treated pools contained very high numbers of thermophilic Naegleria. The Naegleria isolated were identified as N. lovaniensis, a species commonly found in association with N. fowleri. Isoenzyme analysis showed a different type of N. lovaniensis was present in each of two u.v.-treated pools. Images Plate 1 PMID:7061835

Ab initio calculation of the electronic absorption spectrum of liquid water

International Nuclear Information System (INIS)

Martiniano, Hugo F. M. C.; Galamba, Nuno; Cabral, Benedito J. Costa

2014-01-01

The electronic absorption spectrum of liquid water was investigated by coupling a one-body energy decomposition scheme to configurations generated by classical and Born-Oppenheimer Molecular Dynamics (BOMD). A Frenkel exciton Hamiltonian formalism was adopted and the excitation energies in the liquid phase were calculated with the equation of motion coupled cluster with single and double excitations method. Molecular dynamics configurations were generated by different approaches. Classical MD were carried out with the TIP4P-Ew and AMOEBA force fields. The BLYP and BLYP-D3 exchange-correlation functionals were used in BOMD. Theoretical and experimental results for the electronic absorption spectrum of liquid water are in good agreement. Emphasis is placed on the relationship between the structure of liquid water predicted by the different models and the electronic absorption spectrum. The theoretical gas to liquid phase blue-shift of the peak positions of the electronic absorption spectrum is in good agreement with experiment. The overall shift is determined by a competition between the O–H stretching of the water monomer in liquid water that leads to a red-shift and polarization effects that induce a blue-shift. The results illustrate the importance of coupling many-body energy decomposition schemes to molecular dynamics configurations to carry out ab initio calculations of the electronic properties in liquid phase

A comparison of assays measuring the viability of Legionella ...

Science.gov (United States)

Background: The relatively high prevalence of Legionella pneumophila in premise plumbing systems has been widely reported. Published reports indicate Legionella has a comparatively high resistance to chlorine and moreover has the ability to grow in phagocytic amoeba which could provide additional protection in chlorinated drinking water distribution systems. Copper-Silver (Cu-Ag) ionization treatment systems are commercially available for use in large building water systems to help control the risks from Legionella bacteria. The objectives of this study were to develop and optimize Legionella viability assays and use them to investigate the viability of Legionella bacteria after exposure to water treated with coppper and silver ions. Methods: Log phase L. pneumophila cells were used in all experiments and were generated by incubation at 35C for 48 hours in buffered yeast extract broth. Viability assays used included plating on buffered charcoal yeast extract agar to determine the number of culturable cells and treating cells with propidium monoazide (PMA) or ethidium monoazide (EMA) followed by quantitative PCR targeting mip gene of L. pneumophila. The qPCR viability assays were optimized using L. pneumophila inactivated by heat treatment at 65C for 60 min. The effectiveness of Cu-Ag ionization treatment was studied by inoculating L. pneumonia at 105 CFU/mL in water collected directly from a building water system that employed this technology and incubat

Microbial Communities as Environmental Indicators of Ecological Disturbance in Restored Carbonate Fen-Results of 10 Years of Studies.

Science.gov (United States)

Mieczan, Tomasz; Tarkowska-Kukuryk, Monika

2017-08-01

Interactions between bacteria and protists are essential to the ecosystem ecology of fens. Until now, however, there has been almost no information on how restoration procedures in carbonate fens affect the functioning of microbial food webs. Changes in vegetation patterns resulting from restoration may take years to be observed, whereas microbial processes display effects even after short-term exposure to changes in environmental conditions caused by restoration. Therefore, microbial processes and patterns can be used as sensitive indicators of changes in environmental conditions. The present study attempts to verify the hypothesis that the species richness and abundance of microbial loop components would differ substantially before and after restoration. The effect of restoration processes on the functioning of the food web was investigated for a 10 years in a carbonate-rich fen, before and after restoration. The restoration procedure (particularly the improvement in hydrological conditions) distinctly modified the taxonomic composition and functioning of microbial food webs. This is reflected in the increased abundance and diversity of testate amoeba, i.e. top predators, within the microbial food web and in the pronounced increase in the abundance of bacteria. This study suggests potential use of microbial loop components as bio-indicators and bio-monitoring tools for hydrological status of fens and concentrations of nutrients. Better understanding of what regulates microbial populations and activity in fens and unravelling of these fundamental mechanisms are particularly critical in order to more accurately predict how fens will respond to global change or anthropogenic disturbances.

Bioremediation of experimental petroleum spills on mineral soils in the Vestfold Hills, Antarctica

International Nuclear Information System (INIS)

Kerry, E.

1993-01-01

The effect of nutrient and water enhancement on the biodegradation of petroleum was tested in Antarctic mineral soils. Nitrogen, phosphorus and potassium were applied in solution, with or without gum xanthan or plastic covers, to sites artificially contaminated with distillate. The effectiveness of these procedures was assessed by measuring changes in total petroleum hydrocarbons; heptadecane/pristane and octadecane/phytane ratios; in concentrations of major hydrocarbon components and in microbial numbers and activity. Significantly lower hydrocarbon concentration were recorded after one year in soils treated with fertilizer solutions, but only in the surface 3 cm. These soils also showed lowered heptadecane/pristane and octadecane/phytane ratios and had the highest levels of microbial activity relative to other plots. Soils treated with gum xanthan or covered with plastic had the highest residual hydrocarbon levels. Both treatments inhibited evaporative loss of hydrocarbon, and there were indications that gum xanthan was utilized by the microbiota as an alternative carbon source to distillate. Higher temperatures were recorded under the plastic but no stimulation of biodegradation was detected. Estimated numbers of metabolically active bacteria were in the range 10 7 to 10 8 g -1 dry weight of soil, with an estimated biomass of 0.03 to 0.26 mg g -1 soil. Estimated numbers of amoebae were in the range 10 6 10 7 g -1 soil (biomass of 2 to 4 mg g -1 ). The highest populations were recorded in fertilized, contaminated soils, the only soils where petroleum degradation was demonstrated. 23 refs., 1 fig., 4 tabs

Physical parameters and accumulation rates in peat in relation to the climate during the last 150 years

Energy Technology Data Exchange (ETDEWEB)

Borgmark, Anders [Dept. of Physical Geography and Quaternary Geology, Stockholm Univ. (Sweden)

2006-12-15

more theoretical deduced numbers. In this study the temporal resolution is relatively high, with ca years/sample, and therefore it has been possible to detect leads/lags between the proxies, as opposed to longer sequences with lower time resolution. Biological proxies, e.g. plant macrofossils and testate amoebae, reflect the actual wetness conditions at the time when the plants and amoebae lived. Peat humification and C/N ratio on the other hand reflect the conditions during the decay-process of the organic material, i.e. processes that influence already deposited material. In this data it is evident that there is a discrepancy between peat decomposition and dry bulk density/C-N accumulation rates, this might be a result of secondary decomposition, or it could reflect different responses in decomposition and growth rates to changes in temperature and precipitation. Increasing temperature is likely to increase CO{sub 2} and CH{sub 4} emissions to the atmosphere, this is said to be the only direct climatic effect on existing Boreal peatlands but indirect effects as increased peat oxidation induced by falling water tables are exceedingly important, however extremely difficult to forecast. Despite these apprehensions the positive carbon balance in the Boreal peatlands could be expected to be maintained for several thousands of years.

Physical parameters and accumulation rates in peat in relation to the climate during the last 150 years

International Nuclear Information System (INIS)

Borgmark, Anders

2006-12-01

theoretical deduced numbers. In this study the temporal resolution is relatively high, with ca years/sample, and therefore it has been possible to detect leads/lags between the proxies, as opposed to longer sequences with lower time resolution. Biological proxies, e.g. plant macrofossils and testate amoebae, reflect the actual wetness conditions at the time when the plants and amoebae lived. Peat humification and C/N ratio on the other hand reflect the conditions during the decay-process of the organic material, i.e. processes that influence already deposited material. In this data it is evident that there is a discrepancy between peat decomposition and dry bulk density/C-N accumulation rates, this might be a result of secondary decomposition, or it could reflect different responses in decomposition and growth rates to changes in temperature and precipitation. Increasing temperature is likely to increase CO 2 and CH 4 emissions to the atmosphere, this is said to be the only direct climatic effect on existing Boreal peatlands but indirect effects as increased peat oxidation induced by falling water tables are exceedingly important, however extremely difficult to forecast. Despite these apprehensions the positive carbon balance in the Boreal peatlands could be expected to be maintained for several thousands of years

Ciliate Paramecium is a natural reservoir of Legionella pneumophila

Science.gov (United States)

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

2016-04-01

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

Rapid centriole assembly in Naegleria reveals conserved roles for both de novo and mentored assembly.

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Fritz-Laylin, Lillian K; Levy, Yaron Y; Levitan, Edward; Chen, Sean; Cande, W Zacheus; Lai, Elaine Y; Fulton, Chandler

2016-03-01

Centrioles are eukaryotic organelles whose number and position are critical for cilia formation and mitosis. Many cell types assemble new centrioles next to existing ones ("templated" or mentored assembly). Under certain conditions, centrioles also form without pre-existing centrioles (de novo). The synchronous differentiation of Naegleria amoebae to flagellates represents a unique opportunity to study centriole assembly, as nearly 100% of the population transitions from having no centrioles to having two within minutes. Here, we find that Naegleria forms its first centriole de novo, immediately followed by mentored assembly of the second. We also find both de novo and mentored assembly distributed among all major eukaryote lineages. We therefore propose that both modes are ancestral and have been conserved because they serve complementary roles, with de novo assembly as the default when no pre-existing centriole is available, and mentored assembly allowing precise regulation of number, timing, and location of centriole assembly. © 2016 Wiley Periodicals, Inc.

Entamoeba struthionis n.sp. (Sarcomastigophora: Endamoebidae) from ostriches (Struthio camelus).

Science.gov (United States)

Ponce Gordo, F; Martínez Díaz, R A; Herrera, S

2004-02-06

In the present work we identify the species of Entamoeba from ostriches (Struthio camelus). The complete sequence of the small subunit ribosomal RNA gene from this organism has been compared with those published for other species of the genus and clear differences have been found. These results confirm previous data which showed differences on parasite morphology and class of host with the other Entamoeba species. Taking all these data together, it can be concluded that the organism from ostriches is a new species whose proposed name is Entamoeba struthionis n.sp. This species probably infects rheas (Rhea americana), but genetic analysis of isolates from this host should be performed to confirm morphological data. Also, comparison of gene sequences with data from other authors on cysts recovered from human stool samples showed the possibility that this amoeba may affect humans. Further studies are needed to determine the risk of transmission of this new species to humans.

Atypical ploidy cycles, Spo11, and the evolution of meiosis.

Science.gov (United States)

Bloomfield, Gareth

2016-06-01

The Spo11 protein induces DNA double strand breaks before the first division of meiosis, enabling the formation of the chiasmata that physically link homologous chromosomes as they align. Spo11 is an ancient and well conserved protein, related in sequence and structure to a DNA topoisomerase subunit found in Archaea as well as a subset of eukaryotes. However the origins of its meiotic function are unclear. This review examines some apparent exceptions to the rule that Spo11 activity is specific to, and required for meiosis. Spo11 appears to function in the context of unusual forms of ploidy reduction in some protists and fungi. One lineage of amoebae, the dictyostelids, is thought to undergo meiosis during its sexual cycle despite having lost Spo11 entirely. Further experimental characterisation of these and other non-canonical ploidy cycling mechanisms may cast light of the evolution of meiosis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Legionella pneumophila: the paradox of a highly sensitive opportunistic waterborne pathogen able to persist in the environment

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Jean-Marc eBerjeaud

2016-04-01

Full Text Available Legionella pneumophila, the major causative agent of Legionnaires’ disease, is found in freshwater environments in close association with free-living amoebae and multispecies biofilms, leading to persistence, spread, biocide resistance, and elevated virulence of the bacterium. Indeed, legionellosis outbreaks are mainly due to the ability of this bacterium to colonize and persist in water facilities, despite harsh physical and chemical treatments. However, these treatments are not totally efficient and, after a lag period, L. pneumophila may be able to quickly re-colonize these systems. Several natural compounds (biosurfactants, antimicrobial peptides… with anti-Legionella properties have recently been described in the literature, highlighting their specific activities against this pathogen. In this review, we first consider this hallmark of Legionella to resist killing, in regard to its biofilm or host-associated life style. Then, we focus more accurately on natural anti-Legionella molecules described so far, which could provide new eco-friendly and alternative ways to struggle against this important pathogen in plumbing.

Mechanistic insights of the Min oscillator via cell-free reconstitution and imaging

Science.gov (United States)

Mizuuchi, Kiyoshi; Vecchiarelli, Anthony G.

2018-05-01

The MinD and MinE proteins of Escherichia coli self-organize into a standing-wave oscillator on the membrane to help align division at mid-cell. When unleashed from cellular confines, MinD and MinE form a spectrum of patterns on artificial bilayers—static amoebas, traveling waves, traveling mushrooms, and bursts with standing-wave dynamics. We recently focused our cell-free studies on bursts because their dynamics recapitulate many features of Min oscillation observed in vivo. The data unveiled a patterning mechanism largely governed by MinE regulation of MinD interaction with membrane. We proposed that the MinD to MinE ratio on the membrane acts as a toggle switch between MinE-stimulated recruitment and release of MinD from the membrane. In this review, we summarize cell-free data on the Min system and expand upon a molecular mechanism that provides a biochemical explanation as to how these two ‘simple’ proteins can form the remarkable spectrum of patterns.

A non-Lévy random walk in chacma baboons: what does it mean?

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Cédric Sueur

Full Text Available The Lévy walk is found from amoebas to humans and has been described as the optimal strategy for food research. Recent results, however, have generated controversy about this conclusion since animals also display alternatives to the Lévy walk such as the Brownian walk or mental maps and because movement patterns found in some species only seem to depend on food patches distribution. Here I show that movement patterns of chacma baboons do not follow a Lévy walk but a Brownian process. Moreover this Brownian walk is not the main process responsible for movement patterns of baboons. Findings about their speed and trajectories show that baboons use metal maps and memory to find resources. Thus the Brownian process found in this species appears to be more dependent on the environment or might be an alternative when known food patches are depleted and when animals have to find new resources.

Characterization of PEBBLEs as a Tool for Real-Time Measurement of Dictyostelium discoideum Endosomal pH

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Everett Moding

2009-01-01

Full Text Available The measurement of intracellular ion concentration change is important for understanding the cellular mechanisms for communication. Recently developed nanosensors, (Photonic Explorers for Biomedical use with Biologically Localized Embedding PEBBLEs, have a number of advantages for measuring ions in cells over established methods using microelectrodes, unbound fluorescent dyes, or NMR. PEBBLE sensors have been shown to work in principle for measuring dynamic ion changes, but few in vivo applications have been demonstrated. We modified the protocol for the fabrication of pH sensing PEBBLEs and developed a protocol for the utilization of these sensors for the monitoring of dynamic pH changes in the endosomes of slime mold Dictyostelium discoideum (D. discoideum. Oregon Green 514-CdSe Quantum Dot PEBBLEs were used to measure real-time pH inside D. discoideum endosomes during cAMP stimulation. Endosomal pH was shown to decrease during cAMP signaling, demonstrating a movement of protons into the endosomes of D. discoideum amoebae.

Acanthamoeba feature a unique backpacking strategy to trap and feed on Listeria monocytogenes and other motile bacteria

DEFF Research Database (Denmark)

Doyscher, Dominik; Fieseler, Lars; Dons, Lone Elisabet

2013-01-01

Despite its prominent role as an intracellular human pathogen, Listeria monocytogenes normally features a saprophytic lifestyle, and shares many environmental habitats with predatory protozoa. Earlier studies claimed that Acanthamoeba may act as environmental reservoirs for L.?monocytogenes, wher......Despite its prominent role as an intracellular human pathogen, Listeria monocytogenes normally features a saprophytic lifestyle, and shares many environmental habitats with predatory protozoa. Earlier studies claimed that Acanthamoeba may act as environmental reservoirs for L.......?monocytogenes, whereas others failed to confirm this hypothesis. Our findings support the latter and provide clear evidence that L.?monocytogenes is unable to persist in Acanthamoeba castellanii and A.?polyphaga. Instead, external Listeria cells are rapidly immobilized on the surface of Acanthamoeba trophozoites......-lapse microscopy revealed that shortly after the bacteria are collected, the amoeba can change direction of movement, phagocytose the backpack and continue to repeat the process. The phenomenon was also observed with avirulent L.?monocytogenes mutants, non-pathogenic Listeria, and other motile bacteria, indicating...

Investigation of the role of genes encoding zinc exporters zntA, zitB, and fieF during Salmonella typhimurium infection

DEFF Research Database (Denmark)

Huang, Kaisong; Wang, Dan; Frederiksen, Rikki F.

2018-01-01

The transition metal zinc is involved in crucial biological processes in all living organisms and is essential for survival of Salmonella in the host. However, little is known about the role of genes encoding zinc efflux transporters during Salmonella infection. In this study, we constructed...... deletion mutants for genes encoding zinc exporters (zntA, zitB, and fieF) in the wild-type (WT) strain Salmonella enterica serovar Typhimurium (S. Typhimurium) 4/74. The mutants 4/74ΔzntA and 4/74ΔzntA/zitB exhibited a dramatic growth delay and abrogated growth ability, respectively, in Luria Bertani...... medium supplemented with 0.25 mM ZnCl2 or 1.5 mM CuSO4 compared to the WT strain. In order to investigate the role of genes encoding zinc exporters on survival of S. Typhimurium inside cells, amoeba and macrophage infection models were used. No significant differences in uptake or survival were detected...

Repertoire of free-living protozoa in contact lens solutions.

Science.gov (United States)

Bouchoucha, Ibtissem; Aziz, Aurore; Hoffart, Louis; Drancourt, Michel

2016-10-29

The repertoire of free-living protozoa in contact lens solutions is poorly known despite the fact that such protozoa may act as direct pathogens and may harbor intra-cellular pathogens. Between 2009 and 2014, the contact lens solutions collected from patients presenting at our Ophthalmology Department for clinically suspected keratitis, were cultured on non-nutrient agar examined by microscope for the presence of free-living protozoa. All protozoa were identified by 18S rRNA gene sequencing. A total of 20 of 233 (8.6 %) contact lens solution specimens collected from 16 patients were cultured. Acanthamoeba amoeba in 16 solutions (80 %) collected from 12 patients and Colpoda steini, Cercozoa sp., Protostelium sp. and a eukaryotic more closely related to Vermamoeba sp., were each isolated in one solution. Cercozoa sp., Colpoda sp., Protostelium sp. and Vermamoeba sp. are reported for the first time as contaminating contact lens solutions. The repertoire of protozoa in contact lens solutions is larger than previously known.

[AMEBIOSIS

Science.gov (United States)

Náquira C, César

1997-01-01

This is a short review of the infection and disease caused by Entamoeba histolytica. The morphology of the evolutive stages and the life cycle of the parasite is described, including biochemical and immunological data.The intestinal and extraintestinal forms of this disease are briefly characterized as well as the diagnosis by images and laboratory. Differentiation between E. histolytica and E. dispar (known as nonpathogenic E. histolytica) with similar morphology is crucial for individual or mass treatment.This treatment is dealing with the better known drugs and their recommended dosis. The infection by E. histolytica/E. dispar is widely distributed in Peru with variable rates of prevalence (1 to 28%), according with the applied methodology, and the studied population. Recently, the presence of both amoebas has been confirmed by biochemical characterization, and their real prevalence must be determined. The profilaxis and control of this parasitism is based in avoiding fecalism. Sanitary education, environmental sanitation, and mass treatment of risk groups would be the most important measures against ameblasis.

The phylogenetic analysis of tetraspanins projects the evolution of cell-cell interactions from unicellular to multicellular organisms.

Science.gov (United States)

Huang, Shengfeng; Yuan, Shaochun; Dong, Meiling; Su, Jing; Yu, Cuiling; Shen, Yang; Xie, Xiaojin; Yu, Yanhong; Yu, Xuesong; Chen, Shangwu; Zhang, Shicui; Pontarotti, Pierre; Xu, Anlong

2005-12-01

In animals, the tetraspanins are a large superfamily of membrane proteins that play important roles in organizing various cell-cell and matrix-cell interactions and signal pathways based on such interactions. However, their origin and evolution largely remain elusive and most of the family's members are functionally unknown or less known due to difficulties of study, such as functional redundancy. In this study, we rebuilt the family's phylogeny with sequences retrieved from online databases and our cDNA library of amphioxus. We reveal that, in addition to in metazoans, various tetraspanins are extensively expressed in protozoan amoebae, fungi, and plants. We also discuss the structural evolution of tetraspanin's major extracellular domain and the relation between tetraspanin's duplication and functional redundancy. Finally, we elucidate the coevolution of tetraspanins and eukaryotes and suggest that tetraspanins play important roles in the unicell-to-multicell transition. In short, the study of tetraspanin in a phylogenetic context helps us understand the evolution of intercellular interactions.

An autoregulatory circuit for long-range self-organization in Dictyostelium cell populations.

Science.gov (United States)

Sawai, Satoshi; Thomason, Peter A; Cox, Edward C

2005-01-20

Nutrient-deprived Dictyostelium amoebae aggregate to form a multicellular structure by chemotaxis, moving towards propagating waves of cyclic AMP that are relayed from cell to cell. Organizing centres are not formed by founder cells, but are dynamic entities consisting of cores of outwardly rotating spiral waves that self-organize in a homogeneous cell population. Spiral waves are ubiquitously observed in chemical reactions as well as in biological systems. Although feedback control of spiral waves in spatially extended chemical reactions has been demonstrated in recent years, the mechanism by which control is achieved in living systems is unknown. Here we show that mutants of the cyclic AMP/protein kinase A pathway show periodic signalling, but fail to organize coherent long-range wave territories, owing to the appearance of numerous spiral cores. A theoretical model suggests that autoregulation of cell excitability mediated by protein kinase A acts to optimize the number of signalling centres.

Amoeboid swimming: a generic self-propulsion of cells in fluids by means of membrane deformations.

Science.gov (United States)

Farutin, Alexander; Rafaï, Salima; Dysthe, Dag Kristian; Duperray, Alain; Peyla, Philippe; Misbah, Chaouqi

2013-11-27

Microorganisms, such as bacteria, algae, or spermatozoa, are able to propel themselves forward thanks to flagella or cilia activity. By contrast, other organisms employ pronounced changes of the membrane shape to achieve propulsion, a prototypical example being the Eutreptiella gymnastica. Cells of the immune system as well as dictyostelium amoebas, traditionally believed to crawl on a substratum, can also swim in a similar way. We develop a model for these organisms: the swimmer is mimicked by a closed incompressible membrane with force density distribution (with zero total force and torque). It is shown that fast propulsion can be achieved with adequate shape adaptations. This swimming is found to consist of an entangled pusher-puller state. The autopropulsion distance over one cycle is a universal linear function of a simple geometrical dimensionless quantity A/V(2/3) (V and A are the cell volume and its membrane area). This study captures the peculiar motion of Eutreptiella gymnastica with simple force distribution.

Non-Pollen Palynomorphs Characteristic for the Dystrophic Stage of Humic Lakes in the Wigry National Park, Ne Poland

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Fiłoc Magdalena

2015-06-01

Full Text Available The numerous dystrophic (humic lakes are a very important feature of Wigry National Park, NE Poland. As the most recent palaeoecological data indicate, at the beginning of its development (in the Late Glacial and Early and Middle Holocene these water bodies functioned as harmonious lakes, and their transformation into dystrophic lakes and the stabilization of the trophic state took place at the beginning of the Subboreal. Palynological analysis of sediments from two such lakes (Lake Ślepe and Lake Suchar II, with special emphasis on non-pollen palynomorphs (NPPs, was aimed at a detailed biological characterization of dystrophic lakes during their long-lasting existence. The obtained results allowed for the designation of organisms characteristic for dystrophic lakes, of which representatives appeared with the decreasing pH of the water and the formation of Sphagnum peat around lakes. These organisms were divided into four groups: algae, fungi, testate amoebas, and animals. Their representatives appear invarious developmental stages of dystrophic lakes.

Some aspects of interrelations between fungi and other biota in forest soil.

Science.gov (United States)

Krivtsov, Vladimir; Griffiths, Bryan S; Salmond, Ross; Liddell, Keith; Garside, Adam; Bezginova, Tanya; Thompson, Jacqueline A; Staines, Harry J; Watling, Roy; Palfreyman, John W

2004-08-01

Interrelations of fungal mycelium with other soil biota are of paramount importance in forestry and soil ecology. Here we present the results of statistical analysis of a comprehensive data set collected in the first (and the only) British fungus sanctuary over a period of four months. The variables studied included a number of soil properties, bacteria, protozoan flagellates, ciliates and amoebae, microbial and plant feeding nematodes, various microarthropods, and two fungal biomarkers--glomalin and ergosterol. One way ANOVA showed that the dynamics of the microbiota studied was influenced by seasonal changes. Superimposed on these changes, however, was variability due to biological interactions and habitat characteristics. Two fungal biomarkers, ergosterol and glomalin, were differently influenced by other biota and abiotic variables. The results indicate that the dynamics of soil fungi is influenced not only by soil microarthropods, but also by those found in forest litter. The overall outcome, therefore, is likely to be very complex and will depend upon specific conditions of any particular ecosystem.

Fission-product behaviour in irradiated TRISO-coated particles: Results of the HFR-EU1bis experiment and their interpretation

International Nuclear Information System (INIS)

Barrachin, M.; Dubourg, R.; Groot, S. de; Kissane, M.P.; Bakker, K.

2011-01-01

Highlights: → The microstructure and FPs in UO 2 TRISO particles (10% FIMA, 1573 K) were studied. → Very large porosities (>10 μm) were observed in the high temperature particles. → Significant Xe and Cs releases from the kernel were observed. → Mo and Ru are mainly present in the metallic precipitates in the kernel. - Abstract: It is important to understand fission-product (FP) and kernel micro-structure evolution in TRISO-coated fuel particles. FP behaviour, while central to severe-accident evaluation, impacts: evolution of the kernel oxygen potential governing in turn carbon oxidation (amoeba effect and pressurization); particle pressurization through fission-gas release from the kernel; and coating mechanical resistance via reaction with some FPs (Pd, Cs, Sr). The HFR-Eu1bis experiment irradiated five HTR fuel pebbles containing TRISO-coated UO 2 particles and went beyond current HTR specifications (e.g., central temperature of 1523 K). This study presents ceramographic and EPMA examinations of irradiated urania kernels and coatings. Significant evolutions of the kernel (grain structure, porosity, metallic-inclusion size, intergranular bubbles) as a function of temperature are shown. Results concerning FP migration are presented, e.g., significant xenon, caesium and palladium release from the kernel, molybdenum and ruthenium mainly present in metallic precipitates. The observed FP and micro-structural evolutions are interpreted and explanations proposed. The effect of high flux rate and high temperature on fission-gas behaviour, grain-size evolution and kernel swelling is discussed. Furthermore, Cs, Mo and Zr behaviour is interpreted in connection with oxygen-potential. This paper shows that combining state-of-the-art post-irradiation examination and state-of-the-art modelling fundamentally improves understanding of HTR fuel behaviour.

Mathematical model and computer code for coated particles performance at normal operating conditions

International Nuclear Information System (INIS)

Golubev, I.; Kadarmetov, I.; Makarov, V.

2002-01-01

Computer modeling of thermo-mechanical behavior of coated particles during operating both at normal and off-normal conditions has a very significant role particularly on a stage of new reactors development. In Russia a big experience has been accumulated on fabrication and reactor tests of CP and fuel elements with UO 2 kernels. However, this experience cannot be using in full volume for development of a new reactor installation GT-MHR. This is due to very deep burn-up of the fuel based on plutonium oxide (up to 70% fima). Therefore the mathematical modeling of CP thermal-mechanical behavior and failure prediction becomes particularly important. The authors have a clean understanding that serviceability of fuel with high burn-ups are defined not only by thermo-mechanics, but also by structured changes in coating materials, thermodynamics of chemical processes, 'amoeba-effect', formation CO etc. In the report the first steps of development of integrate code for numerical modeling of coated particles behavior and some calculating results concerning the influence of various design parameters on fuel coated particles endurance for GT-MHR normal operating conditions are submitted. A failure model is developed to predict the fraction of TRISO-coated particles. In this model it is assumed that the failure of CP depends not only on probability of SiC-layer fracture but also on the PyC-layers damage. The coated particle is considered as a uniform design. (author)

Seasonal variation of the protozooplanktonic community in a tropical oligotrophic environment (Ilha Solteira reservoir, Brazil).

Science.gov (United States)

Mansano, A S; Hisatugo, K F; Leite, M A; Luzia, A P; Regali-Seleghim, M H

2013-05-01

The seasonal variation of the protozooplanktonic community (ciliates and testate amoebae) was studied in a tropical oligotrophic reservoir in Brazil, which was under the influence of two contrasting climatic seasons (rainy/warm and dry/cold). The aim of this study was to evaluate the effect of these climatic changes on physical, chemical and biological variables in the dynamic of this community. The highest mean density of total protozoans occurred in the rainy/warm season (5683.2 ind L-1), while the lowest was in the dry/cold (2016.0 ind L-1). Considering the seasonal variations, the protozoan groups that are truly planktonic, such as the oligotrichs (Spirotrichea), predominated in the dry season, whereas during the rainy season, due to the material input and resuspension of sediment, sessile protozoans of the Peritrichia group were the most important ones. The dominant protozoans were Urotricha globosa, Cothurnia annulata, Pseudodifflugia sp. and Halteria grandinella. The highest densities of H. grandinella were associated with more oxygenated and transparent water conditions, while the highest densities of C. annulata occurred in sites with high turbidity, pH and trophic state index (TSI). The study demonstrated that density and composition of protozooplanktonic species and groups of the reservoir suffered seasonal variation due to the environmental variables (mainly temperature, turbidity, water transparency, dissolved oxygen and TSI) and the biological variables (e.g. morphological characteristics, eating habits and escape strategies from predation of the species).

Biofilm Composition and Threshold Concentration for Growth of Legionella pneumophila on Surfaces Exposed to Flowing Warm Tap Water without Disinfectant.

Science.gov (United States)

van der Kooij, Dick; Bakker, Geo L; Italiaander, Ronald; Veenendaal, Harm R; Wullings, Bart A

2017-03-01

Legionella pneumophila in potable water installations poses a potential health risk, but quantitative information about its replication in biofilms in relation to water quality is scarce. Therefore, biofilm formation on the surfaces of glass and chlorinated polyvinyl chloride (CPVC) in contact with tap water at 34 to 39°C was investigated under controlled hydraulic conditions in a model system inoculated with biofilm-grown L. pneumophila The biofilm on glass (average steady-state concentration, 23 ± 9 pg ATP cm -2 ) exposed to treated aerobic groundwater (0.3 mg C liter -1 ; 1 μg assimilable organic carbon [AOC] liter -1 ) did not support growth of the organism, which also disappeared from the biofilm on CPVC (49 ± 9 pg ATP cm -2 ) after initial growth. L. pneumophila attained a level of 4.3 log CFU cm -2 in the biofilms on glass (1,055 ± 225 pg ATP cm -2 ) and CPVC (2,755 ± 460 pg ATP cm -2 ) exposed to treated anaerobic groundwater (7.9 mg C liter -1 ; 10 μg AOC liter -1 ). An elevated biofilm concentration and growth of L. pneumophila were also observed with tap water from the laboratory. The Betaproteobacteria Piscinibacter and Methyloversatilis and amoeba-resisting Alphaproteobacteria predominated in the clones and isolates retrieved from the biofilms. In the biofilms, the Legionella colony count correlated significantly with the total cell count (TCC), heterotrophic plate count, ATP concentration, and presence of Vermamoeba vermiformis This amoeba was rarely detected at biofilm concentrations of water-associated disease outbreaks reported in the United States. The organism proliferates in biofilms on surfaces exposed to warm water in engineered freshwater installations. An investigation with a test system supplied with different types of warm drinking water without disinfectant under controlled hydraulic conditions showed that treated aerobic groundwater (0.3 mg liter -1 of organic carbon) induced a low biofilm concentration that supported no or very

DISTRIBUSI PARASIT USUS PROTOZOA DI KABUPATEN HULU SUNGAI UTARA KALIMANTAN SELATAN

Directory of Open Access Journals (Sweden)

Anorital Anorital

2012-07-01

Full Text Available The intestinal infection disease caused by protozoa: amoeba is one of the public health problem with high incidence in the community. From the research activity conducted in Hulu Sungai Utara Regency in the year 2002, to obtain of prevalence of protozoa infection from stool examination from resident in 6 villages at 3 subdistrict in Hulu Sungai Utara Regency. The research has conducted to be carry out survey parasite to the community. Sample size will be examination are 230 persons per village, so that to 6 villages will be examed as 1.600 persons. The examination directly by using lugol 2% and checked on the microscope with magnification 10x10 and 10x40. For resident which its sample stool is positive the protozoa to be given a treatment by metronidazol. From stool examination result obtained prevalence resident which are positive the amoeba intestine protozoa is Entamoeba coli 19,8%, Endolimax nana 15,8%, and Entamoeba histolityca 15,4%. While prevalence resident which are positive the intestine flagellata/B. hominis is Blastocystis hominis 25,5% and Giardia lamblia 11,6%. From 5 micro-organism on the intestine. Entamoeba histolityca, Blastocystis hominis and Giardia lamblia are cause diarrhoea because having the pathogenic. From survey ot socio-cultural, known also the resident percentage which drinking no safe water 43,3%, source of drinking water obtained from river or swamp is 67,7%, human waste disposal in river and swamp is 79,5%, and take a bath and brush the teeth with water of river and swamp is 78,6%; showing bad condition of environmental sanitation, personal hygiene, and life behavior. Good personal hygiene and environmental sanitation practices are the major factors of this disease prevention. The main principle to prevent the spreading of protozoa infection is to cut off the link of infection sources to human beings. Personal hygiene is focused on the management of individual behaviour, meanwhile environmental sanitation

Your Garden Hose: A potential health risk due to Legionella spp. growth facilitated by free-living amoebae

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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 ...

Ménage-a-trois: The amoeba Nuclearia sp. from Lake Zurich with its ecto- and endosymbiotic bacteria

Czech Academy of Sciences Publication Activity Database

Dirren, S.; Salcher, Michaela M.; Blom, J. F.; Schweikert, M.; Posch, T.

2014-01-01

Roč. 165, č. 5 (2014), s. 745-758 ISSN 1434-4610 Institutional support: RVO:60077344 Keywords : bacteria-protist symbioses * ectosymbionts * endosymbionts * feeding * Nucleariidae * Paucibacter toxinivorans Subject RIV: DA - Hydrology ; Limnology Impact factor: 3.045, year: 2014

The role of Src kinase in the biology and pathogenesis of Acanthamoeba castellanii

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Siddiqui Ruqaiyyah

2012-06-01

Full Text Available Abstract Background Acanthamoeba species are the causative agents of fatal granulomatous encephalitis in humans. Haematogenous spread is thought to be a primary step, followed by blood–brain barrier penetration, in the transmission of Acanthmaoeba into the central nervous system, but the associated molecular mechanisms remain unclear. Here, we evaluated the role of Src, a non-receptor protein tyrosine kinase in the biology and pathogenesis of Acanthamoeba. Methods Amoebistatic and amoebicidal assays were performed by incubating amoeba in the presence of Src kinase-selective inhibitor, PP2 (4-amino-5-(4-chlorophenyl-7-(t-butylpyrazolo[3,4-d]pyrimidine and its inactive analog, PP3 (4-amino-7-phenylpyrazolo[3,4-d]pyrimidine. Using this inhibitor, the role of Src kinase in A. castellanii interactions with Escherichia coli was determined. Zymographic assays were performed to study effects of Src kinase on extracellular proteolytic activities of A. castellanii. The human brain microvascular endothelial cells were used to determine the effects of Src kinase on A. castellanii adhesion to and cytotoxicity of host cells. Results Inhibition of Src kinase using a specific inhibitor, PP2 (4-amino-5-(4 chlorophenyl-7-(t-butylpyrazolo [3,4-d] pyrimidine but not its inactive analog, PP3 (4-amino-7-phenylpyrazolo[3,4-d] pyrimidine, had detrimental effects on the growth of A. castellanii (keratitis isolate, belonging to the T4 genotype. Interestingly, inhibition of Src kinase hampered the phagocytic ability of A. castellanii, as measured by the uptake of non-invasive bacteria, but, on the contrary, invasion by pathogenic bacteria was enhanced. Zymographic assays revealed that inhibition of Src kinases reduced extracellular protease activities of A. castellanii. Src kinase inhibition had no significant effect on A. castellanii binding to and cytotoxicity of primary human brain microvascular endothelial cells, which constitute the blood–brain barrier

Entamoeba marina n. sp.; a New Species of Entamoeba Isolated from Tidal Flat Sediment of Iriomote Island, Okinawa, Japan.

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Shiratori, Takashi; Ishida, Ken-Ichiro

2016-05-01

The genus Entamoeba includes anaerobic lobose amoebae, most of which are parasites of various vertebrates and invertebrates. We report a new Entamoeba species, E. marina n. sp. that was isolated from a sample of tidal flat sediment collected at Iriomote Island, Okinawa, Japan. Trophozoites of E. marina were 12.8-32.1 μm in length and 6.8-15.9 μm in width, whereas the cysts were 8.9-15.8 μm in diam. and contained four nuclei. The E. marina cells contained a rounded nucleus with a small centric karyosome and uniformly arranged peripheral chromatin. Although E. marina is morphologically indistinguishable from other tetranucleated cyst-forming Entamoeba species, E. marina can be distinguished from them based on the combination of molecular phylogenetic analyses using SSU rDNA gene and the difference of collection sites. Therefore, we propose E. marina as a new species of the genus Entamoeba. © 2015 The Author(s) Journal of Eukaryotic Microbiology © 2015 International Society of Protistologists.

Chlorogenic Acid: Recent Advances on Its Dual Role as a Food Additive and a Nutraceutical against Metabolic Syndrome

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Jesús Santana-Gálvez

2017-02-01

Full Text Available Chlorogenic acid (5-O-caffeoylquinic acid is a phenolic compound from thehydroxycinnamic acid family. This polyphenol possesses many health-promoting properties, mostof them related to the treatment of metabolic syndrome, including anti-oxidant, anti-inflammatory,antilipidemic, antidiabetic, and antihypertensive activities. The first part of this review will discussthe role of chlorogenic acid as a nutraceutical for the prevention and treatment of metabolicsyndrome and associated disorders, including in vivo studies, clinical trials, and mechanisms ofaction. The second part of the review will be dealing with the role of chlorogenic acid as a foodadditive. Chlorogenic acid has shown antimicrobial activity against a wide range of organisms,including bacteria, yeasts, molds, viruses, and amoebas. These antimicrobial properties can beuseful for the food industry in its constant search for new and natural molecules for thepreservation of food products. In addition, chlorogenic acid has antioxidant activity, particularlyagainst lipid oxidation; protective properties against degradation of other bioactive compoundspresent in food, and prebiotic activity. The combination of these properties makes chlorogenic acidan excellent candidate for the formulation of dietary supplements and functional foods.

Targeting channels and transporters in protozoan parasite infections

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Meier, Anna; Erler, Holger; Beitz, Eric

2018-03-01

Infectious diseases caused by pathogenic protozoa are among the most significant causes of death in humans. Therapeutic options are scarce and massively challenged by the emergence of resistant parasite strains. Many of the current anti-parasite drugs target soluble enzymes, generate unspecific oxidative stress, or act by an unresolved mechanism within the parasite. In recent years, collections of drug-like compounds derived from large-scale phenotypic screenings, such as the malaria or pathogen box, have been made available to researchers free of charge boosting the identification of novel promising targets. Remarkably, several of the compound hits have been found to inhibit membrane proteins at the periphery of the parasites, i.e. channels and transporters for ions and metabolites. In this review, we will focus on the progress made on targeting channels and transporters at different levels and the potential for use against infections with apicomplexan parasites mainly Plasmodium spp. (malaria) and Toxoplasma gondii (toxoplasmosis), with kinetoplastids Trypanosoma brucei (sleeping sickness), Trypanosoma cruzi (Chagas disease) and Leishmania ssp. (leishmaniasis), and the amoeba Entamoeba histolytica (amoebiasis).

Metacommunity analysis of amoeboid protists in grassland soils.

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Fiore-Donno, Anna Maria; Weinert, Jan; Wubet, Tesfaye; Bonkowski, Michael

2016-01-11

This study reveals the diversity and distribution of two major ubiquitous groups of soil amoebae, the genus Acanthamoeba and the Myxomycetes (plasmodial slime-moulds) that are rarely, if ever, recovered in environmental sampling studies. We analyzed 150 grassland soil samples from three Biodiversity Exploratories study regions in Germany. We developed specific primers targeting the V2 variable region in the first part of the small subunit of the ribosomal RNA gene for high-throughput pyrotag sequencing. From ca. 1 million reads, applying very stringent filtering and clustering parameters to avoid overestimation of the diversity, we obtained 273 acanthamoebal and 338 myxomycete operational taxonomic units (OTUs, 96% similarity threshold). This number is consistent with the genetic diversity known in the two investigated lineages, but unequalled to date by any environmental sampling study. Only very few OTUs were identical to already known sequences. Strikingly different OTUs assemblages were found between the three German regions (PerMANOVA p.value = 0.001) and even between sites of the same region (multiple-site Simpson-based similarity indices <0.4), showing steep biogeographical gradients.

Establishment of a continuous culture system for Entamoeba muris and analysis of the small subunit rRNA gene

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Kobayashi S.

2009-06-01

Full Text Available We established a culture system for Entamoeba muris (MG-EM-01 strain isolated from a Mongolian gerbil using a modified Balamuth’s egg yolk infusion medium supplemented with 4% adult bovine serum and Bacteroides fragilis cocultured with Escherichia coli. Further, encystation was observed in the culture medium. The morphological characteristics of E. muris are similar to those of Entamoeba coli (E. coli; moreover, the malic isoenzyme electrophoretic band, which shows species-specific electrophoretic mobility, of E. muris had almost the same mobility as that observed with the malic isoenzyme electrophorectic band of E. coli (UZG-EC-01 strain isolated from a gorilla. We determined the small subunit rRNA (SSU-rRNA gene sequence of the MG-EM-01 strain, and this sequence was observed to show 82.7% homology with that of the UZG-EC-01 strain. Further, the resultant phylogenetic tree for molecular taxonomy based on the SSU-rRNA genes of the 21 strains of the intestinal parasitic amoeba species indicated that the MG-EM-01 strain was most closely related to E. coli.

Acanthamoeba belonging to T3, T4, and T11: genotypes isolated from air-conditioning units in Santiago, Chile.

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Astorga, Berbeli; Lorenzo-Morales, Jacob; Martín-Navarro, Carmen M; Alarcón, Verónica; Moreno, Johanna; González, Ana C; Navarrete, Elizabeth; Piñero, José E; Valladares, Basilio

2011-01-01

Free-living amoebae (FLA) of the genus Acanthamoeba are widely distributed in the environment, in the air, soil, and water, and have also been isolated from air-conditioning units. The objective of this work was to investigate the presence of this genus of FLA in the air-conditioning equipment at the Institute of Public Health of Chile in Santiago, Chile. Water and air samples were collected from air-conditioning systems and were checked for the presence of Acanthamoeba spp. Positive samples were further classified at the genotype level after sequencing the highly variable diagnostic fragment 3 (DF3) region of the 18S rRNA gene. This is the first report of the T3, T4, and T11 genotypes of Acanthamoeba in air-conditioning units from Chile. Overall, the widespread distribution of potentially pathogenic Acanthamoeba strains in the studied source demands more awareness within the public and health professionals in Chile as this pathogen is emerging as a risk for human health worldwide. © 2011 The Author(s) Journal of Eukaryotic Microbiology © 2011 International Society of Protistologists.

ACANTHAMOEBA SP.S-11 PHAGOCYTOTIC ACTIVITY ON MYCOBACTERIUM LEPRAE IN DIFFERENT NUTRIENT CONDITIONS.

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Paling, Sepling; Wahyuni, Ratna; Ni'matuzahroh; Winarni, Dwi; Iswahyudi; Astari, Linda; Adriaty, Dinar; Agusni, Indropo; Izumi, Shinzo

2018-01-01

Mycobacterium leprae ( M. leprae ) is a pathogenic bacterium that causes leprosy. The presence of M. leprae in the environment is supported by microorganisms that act as the new host for M. leprae . Acanthamoeba 's potential to be a host of M. leprae in the environment. Acanthamoeba sp. is Free Living Amoeba (FLA) that classified as holozoic, saprophytic, and saprozoic. The existence of nutrients in the environment influence Acanthamoeba ability to phagocytosis or pinocytosis. This study is aimed to determine Acanthamoeba sp.S-11 phagocytic activity to Mycobacterium leprae ( M. leprae ) which cultured in non-nutrient media and riched-nutrient media. This research conducted by culturing Acanthamoeba sp.S-11 and M. leprae on different nutrient media conditions. M. leprae intracellular DNA were isolated and amplified by M. leprae specific primers through Real Time PCR (Q-PCR). The results showed that Acanthamoeba co-cultured on non-nutrient media were more active to phagocyte M. leprae than on rich-nutrient media. The use of non-nutrient media is recommended to optimize Acanthamoeba sp. phagocytic activity to M. leprae .

Impact and control of protozoan parasites in maricultured fishes.

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Buchmann, Kurt

2015-01-01

Aquaculture, including both freshwater and marine production, has on a world scale exhibited one of the highest growth rates within animal protein production during recent decades and is expected to expand further at the same rate within the next 10 years. Control of diseases is one of the most prominent challenges if this production goal is to be reached. Apart from viral, bacterial, fungal and metazoan infections it has been documented that protozoan parasites affect health and welfare and thereby production of fish in marine aquaculture. Representatives within the main protozoan groups such as amoebae, dinoflagellates, kinetoplastid flagellates, diplomonadid flagellates, apicomplexans, microsporidians and ciliates have been shown to cause severe morbidity and mortality among farmed fish. Well studied examples are Neoparamoeba perurans, Amyloodinium ocellatum, Spironucleus salmonicida, Ichthyobodo necator, Cryptobia salmositica, Loma salmonae, Cryptocaryon irritans, Miamiensis avidus and Trichodina jadranica. The present report provides details on the parasites' biology and impact on productivity and evaluates tools for diagnosis, control and management. Special emphasis is placed on antiprotozoan immune responses in fish and a strategy for development of vaccines is presented.

Amphitremida (poche, 1913 is a new major, ubiquitous labyrinthulomycete clade.

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Fatma Gomaa

Full Text Available Micro-eukaryotic diversity is poorly documented at all taxonomic levels and the phylogenetic affiliation of many taxa - including many well-known and common organisms - remains unknown. Among these incertae sedis taxa are Archerella flavum (Loeblich and Tappan, 1961 and Amphitrema wrightianum (Archer, 1869 (Amphitremidae, two filose testate amoebae commonly found in Sphagnum peatlands. To clarify their phylogenetic position, we amplified and sequenced the SSU rRNA gene obtained from four independent DNA extractions of A. flavum and three independent DNA extractions of A. wrightianum. Our molecular data demonstrate that genera Archerella and Amphitrema form a fully supported deep-branching clade within the Labyrinthulomycetes (Stramenopiles, together with Diplophrys sp. (ATCC50360 and several environmental clones obtained from a wide range of environments. This newly described clade we named Amphitremida is diverse genetically, ecologically and physiologically. Our phylogenetic analysis suggests that osmotrophic species evolved most likely from phagotrophic ancestors and that the bothrosome, an organelle that produces cytoplasmic networks used for attachment to the substratum and to absorb nutrients from the environments, appeared lately in labyrithulomycete evolution.

A Non-canonical Melanin Biosynthesis Pathway Protects Aspergillus terreus Conidia from Environmental Stress.

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Geib, Elena; Gressler, Markus; Viediernikova, Iuliia; Hillmann, Falk; Jacobsen, Ilse D; Nietzsche, Sandor; Hertweck, Christian; Brock, Matthias

2016-05-19

Melanins are ubiquitous pigments found in all kingdoms of life. Most organisms use them for protection from environmental stress, although some fungi employ melanins as virulence determinants. The human pathogenic fungus Aspergillus fumigatus and related Ascomycetes produce dihydroxynaphthalene- (DHN) melanin in their spores, the conidia, and use it to inhibit phagolysosome acidification. However, biosynthetic origin of melanin in a related fungus, Aspergillus terreus, has remained a mystery because A. terreus lacks genes for synthesis of DHN-melanin. Here we identify genes coding for an unusual NRPS-like enzyme (MelA) and a tyrosinase (TyrP) that A. terreus expressed under conidiation conditions. We demonstrate that MelA produces aspulvinone E, which is activated for polymerization by TyrP. Functional studies reveal that this new pigment, Asp-melanin, confers resistance against UV light and hampers phagocytosis by soil amoeba. Unexpectedly, Asp-melanin does not inhibit acidification of phagolysosomes, thus likely contributing specifically to survival of A. terreus conidia in acidic environments. Copyright © 2016 Elsevier Ltd. All rights reserved.

A physical perspective on cytoplasmic streaming.

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Goldstein, Raymond E; van de Meent, Jan-Willem

2015-08-06

Organisms show a remarkable range of sizes, yet the dimensions of a single cell rarely exceed 100 µm. While the physical and biological origins of this constraint remain poorly understood, exceptions to this rule give valuable insights. A well-known counterexample is the aquatic plant Chara, whose cells can exceed 10 cm in length and 1 mm in diameter. Two spiralling bands of molecular motors at the cell periphery drive the cellular fluid up and down at speeds up to 100 µm s(-1), motion that has been hypothesized to mitigate the slowness of metabolite transport on these scales and to aid in homeostasis. This is the most organized instance of a broad class of continuous motions known as 'cytoplasmic streaming', found in a wide range of eukaryotic organisms-algae, plants, amoebae, nematodes and flies-often in unusually large cells. In this overview of the physics of this phenomenon, we examine the interplay between streaming, transport and cell size and discuss the possible role of self-organization phenomena in establishing the observed patterns of streaming.

Paulinella chromatophora – rethinking the transition from endosymbiont to organelle

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Eva C.M. Nowack

2014-12-01

Full Text Available Eukaryotes co-opted photosynthetic carbon fixation from prokaryotes by engulfing a cyanobacterium and stably integrating it as a photosynthetic organelle (plastid in a process known as primary endosymbiosis. The sheer complexity of interactions between a plastid and the surrounding cell that started to evolve over 1 billion years ago, make it challenging to reconstruct intermediate steps in organelle evolution by studying extant plastids. Recently, the photosynthetic amoeba Paulinella chromatophora was identified as a much sought-after intermediate stage in the evolution of a photosynthetic organelle. This article reviews the current knowledge on this unique organism. In particular it describes how the interplay of reductive genome evolution, gene transfers, and trafficking of host-encoded proteins into the cyanobacterial endosymbiont contributed to transform the symbiont into a nascent photosynthetic organelle. Together with recent results from various other endosymbiotic associations a picture emerges that lets the targeting of host-encoded proteins into bacterial endosymbionts appear as an early step in the establishment of an endosymbiotic relationship that enables the host to gain control over the endosymbiont.

Decidable and undecidable arithmetic functions in actin filament networks

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Schumann, Andrew

2018-01-01

The plasmodium of Physarum polycephalum is very sensitive to its environment, and reacts to stimuli with appropriate motions. Both the sensory and motor stages of these reactions are explained by hydrodynamic processes, based on fluid dynamics, with the participation of actin filament networks. This paper is devoted to actin filament networks as a computational medium. The point is that actin filaments, with contributions from many other proteins like myosin, are sensitive to extracellular stimuli (attractants as well as repellents), and appear and disappear at different places in the cell to change aspects of the cell structure—e.g. its shape. By assembling and disassembling actin filaments, some unicellular organisms, like Amoeba proteus, can move in response to various stimuli. As a result, these organisms can be considered a simple reversible logic gate—extracellular signals being its inputs and motions its outputs. In this way, we can implement various logic gates on amoeboid behaviours. These networks can embody arithmetic functions within p-adic valued logic. Furthermore, within these networks we can define the so-called diagonalization for deducing undecidable arithmetic functions.

Circulating Hemocytes from Larvae of the Japanese Rhinoceros Beetle Allomyrina dichotoma (Linnaeus) (Coleoptera: Scarabaeidae) and the Cellular Immune Response to Microorganisms.

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Hwang, Sejung; Bang, Kyeongrin; Lee, Jiae; Cho, Saeyoull

2015-01-01

Hemocytes of the last larva of the Japanese rhinoceros beetle A. dichotoma (Linnaeus) (Coleoptera: Scarabaeidae) were classified as granulocytes, plasmatocytes, oenocytoids, spherulocytes, prohemocytes, and adipohemocytes. Among these cell types, only the granulocytes became immunologically activated with obvious morphological changes, displaying large amoeba-like, lobopodia-like, and fan-like structures. In addition, their cytoplasmic granules became larger and greatly increased in number. To explore whether these granules could be immunologically generated as phagosomes, total hemocytes were stained with LysoTracker. Greater than 90% of the granulocytes retained the LysoTracker dye at 4 h post-bacterial infection. In flow cytometry analysis, the red fluorescent signal was highly increased at 4 h post-bacterial infection (60.36%) compared to controls (5.08%), as was confirmed by fluorescent microscopy. After 12 h post-infection, these signals returned to basal levels. The uptake of pathogens by granulocytes rapidly triggered the translocation of the microtubule-associated protein 1 light chain 3 alpha (LC3) to the phagosome, which may result in enhanced pathogen killing.

Circulating Hemocytes from Larvae of the Japanese Rhinoceros Beetle Allomyrina dichotoma (Linnaeus (Coleoptera: Scarabaeidae and the Cellular Immune Response to Microorganisms.

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Sejung Hwang

Full Text Available Hemocytes of the last larva of the Japanese rhinoceros beetle A. dichotoma (Linnaeus (Coleoptera: Scarabaeidae were classified as granulocytes, plasmatocytes, oenocytoids, spherulocytes, prohemocytes, and adipohemocytes. Among these cell types, only the granulocytes became immunologically activated with obvious morphological changes, displaying large amoeba-like, lobopodia-like, and fan-like structures. In addition, their cytoplasmic granules became larger and greatly increased in number. To explore whether these granules could be immunologically generated as phagosomes, total hemocytes were stained with LysoTracker. Greater than 90% of the granulocytes retained the LysoTracker dye at 4 h post-bacterial infection. In flow cytometry analysis, the red fluorescent signal was highly increased at 4 h post-bacterial infection (60.36% compared to controls (5.08%, as was confirmed by fluorescent microscopy. After 12 h post-infection, these signals returned to basal levels. The uptake of pathogens by granulocytes rapidly triggered the translocation of the microtubule-associated protein 1 light chain 3 alpha (LC3 to the phagosome, which may result in enhanced pathogen killing.

Isolation of thermotolerant Vermamoeba vermiformis strains from water sources in Lanzarote Island, Canary Islands, Spain.

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Reyes-Batlle, María; Wagner, Carolina; Zamora-Herrera, Jonadab; Vargas-Mesa, Alejandro; Sifaoui, Ines; González, Ana C; López-Arencibia, Atteneri; Valladares, Basilio; Martínez-Carretero, Enrique; Piñero, José E; Lorenzo-Morales, Jacob

2016-09-01

In this study, twenty water samples were collected in the island of Lanzarote, Canary Islands, Spain in order to check for the presence of V. vermiformis strains in these samples. Water samples were cultured on 2% Non-Nutrient Agar (NNA) plates covered with a thin layer of heat killed E. coli and checked daily for the presence of Vermamoeba. After a week, V. vermiformis amoebae were observed in 2 of the 20 processed samples (10%) incubated at room temperature and 37°C. Molecular characterization was carried out by amplifying the 18S rDNA gene and DNA sequencing in order to confirm the identity of the isolated amoebic strains. To the best of our knowledge, this is the first report on the presence of FLA in environmental sources in Lanzarote Island and the first report of Vermamoeba vermiformis in water sources in this island. Furthermore, the two strains isolated in this study were collected in recreational areas with close contact with humans and thus awareness should be raised.

Inactivation of microbiota from urban wastewater by single and sequential electrocoagulation and electro-Fenton treatments.

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Anfruns-Estrada, Eduard; Bruguera-Casamada, Carmina; Salvadó, Humbert; Brillas, Enric; Sirés, Ignasi; Araujo, Rosa M

2017-12-01

This work aims at comparing the ability of two kinds of electrochemical technologies, namely electrocoagulation (EC) and electro-Fenton (EF), to disinfect primary and secondary effluents from municipal wastewater treatment plants. Heterotrophic bacteria, Escherichia coli, enterococci, Clostridium perfringens spores, somatic coliphages and eukaryotes (amoebae, flagellates, ciliates and metazoa) were tested as indicator microorganisms. EC with an Fe/Fe cell at 200 A m -2 and natural pH allowed >5 log unit removal of E. coli and final concentration below 1 bacteria mL -1 of coliphages and eukaryotes from both effluents in ca. 60 min, whereas heterotrophic bacteria, enterococci and spores were more resistant. A larger removal was obtained for the primary effluent, probably because the flocs remove higher amount of total organic carbon (TOC), entrapping more easily the microbiota. EF with a boron-doped diamond (BDD) anode and an air-diffusion cathode that produces H 2 O 2 on site was first performed at pH 3.0, with large or even total inactivation of microorganisms within 30 min. A more effective microorganism removal was attained as compared to EC thanks to • OH formed from Fenton's reaction. A quicker disinfection was observed for the secondary effluent owing to its lower TOC content, allowing the attack of greater quantities of electrogenerated oxidants on microorganisms. Wastewater disinfection by EF was also feasible at natural pH (∼7), showing similar abatement of active microorganisms as a result of the synergistic action of generated oxidants like active chlorine and coagulation with iron hydroxides. A sequential EC/EF treatment (30 min each) was more effective for a combined decontamination and disinfection of urban wastewater. Copyright © 2017 Elsevier Ltd. All rights reserved.

Stealth proteins: in silico identification of a novel protein family rendering bacterial pathogens invisible to host immune defense.

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Peter Sperisen

2005-11-01

Full Text Available There are a variety of bacterial defense strategies to survive in a hostile environment. Generation of extracellular polysaccharides has proved to be a simple but effective strategy against the host's innate immune system. A comparative genomics approach led us to identify a new protein family termed Stealth, most likely involved in the synthesis of extracellular polysaccharides. This protein family is characterized by a series of domains conserved across phylogeny from bacteria to eukaryotes. In bacteria, Stealth (previously characterized as SacB, XcbA, or WefC is encoded by subsets of strains mainly colonizing multicellular organisms, with evidence for a protective effect against the host innate immune defense. More specifically, integrating all the available information about Stealth proteins in bacteria, we propose that Stealth is a D-hexose-1-phosphoryl transferase involved in the synthesis of polysaccharides. In the animal kingdom, Stealth is strongly conserved across evolution from social amoebas to simple and complex multicellular organisms, such as Dictyostelium discoideum, hydra, and human. Based on the occurrence of Stealth in most Eukaryotes and a subset of Prokaryotes together with its potential role in extracellular polysaccharide synthesis, we propose that metazoan Stealth functions to regulate the innate immune system. Moreover, there is good reason to speculate that the acquisition and spread of Stealth could be responsible for future epidemic outbreaks of infectious diseases caused by a large variety of eubacterial pathogens. Our in silico identification of a homologous protein in the human host will help to elucidate the causes of Stealth-dependent virulence. At a more basic level, the characterization of the molecular and cellular function of Stealth proteins may shed light on fundamental mechanisms of innate immune defense against microbial invasion.

Stealth Proteins: In Silico Identification of a Novel Protein Family Rendering Bacterial Pathogens Invisible to Host Immune Defense.

Directory of Open Access Journals (Sweden)

2005-11-01

Full Text Available There are a variety of bacterial defense strategies to survive in a hostile environment. Generation of extracellular polysaccharides has proved to be a simple but effective strategy against the host's innate immune system. A comparative genomics approach led us to identify a new protein family termed Stealth, most likely involved in the synthesis of extracellular polysaccharides. This protein family is characterized by a series of domains conserved across phylogeny from bacteria to eukaryotes. In bacteria, Stealth (previously characterized as SacB, XcbA, or WefC is encoded by subsets of strains mainly colonizing multicellular organisms, with evidence for a protective effect against the host innate immune defense. More specifically, integrating all the available information about Stealth proteins in bacteria, we propose that Stealth is a D-hexose-1-phosphoryl transferase involved in the synthesis of polysaccharides. In the animal kingdom, Stealth is strongly conserved across evolution from social amoebas to simple and complex multicellular organisms, such as Dictyostelium discoideum, hydra, and human. Based on the occurrence of Stealth in most Eukaryotes and a subset of Prokaryotes together with its potential role in extracellular polysaccharide synthesis, we propose that metazoan Stealth functions to regulate the innate immune system. Moreover, there is good reason to speculate that the acquisition and spread of Stealth could be responsible for future epidemic outbreaks of infectious diseases caused by a large variety of eubacterial pathogens. Our in silico identification of a homologous protein in the human host will help to elucidate the causes of Stealth-dependent virulence. At a more basic level, the characterization of the molecular and cellular function of Stealth proteins may shed light on fundamental mechanisms of innate immune defense against microbial invasion.

Intranasal Coadministration of the Cry1Ac Protoxin with Amoebal Lysates Increases Protection against Naegleria fowleri Meningoencephalitis

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Rojas-Hernández, Saúl; Rodríguez-Monroy, Marco A.; López-Revilla, Rubén; Reséndiz-Albor, Aldo A.; Moreno-Fierros, Leticia

2004-01-01

Cry1Ac protoxin has potent mucosal and systemic adjuvant effects on antibody responses to proteins or polysaccharides. In this work, we examined whether Cry1Ac increased protective immunity against fatal Naegleria fowleri infection in mice, which resembles human primary amoebic meningoencephalitis. Higher immunoglobulin G (IgG) than IgA anti-N. fowleri responses were elicited in the serum and tracheopulmonary fluids of mice immunized by the intranasal or intraperitoneal route with N. fowleri lysates either alone or with Cry1Ac or cholera toxin. Superior protection against a lethal challenge with 5 × 104 live N. fowleri trophozoites was achieved for immunization by the intranasal route. Intranasal immunization of N. fowleri lysates coadministered with Cry1Ac increased survival to 100%; interestingly, immunization with Cry1Ac alone conferred similar protection to that achieved with amoebal lysates alone (60%). When mice intranasally immunized with Cry1Ac plus lysates were challenged with amoebae, both IgG and IgA mucosal responses were rapidly increased, but only the increased IgG response persisted until day 60 in surviving mice. The brief rise in the level of specific mucosal IgA does not exclude the role that this isotype may play in the early defense against this parasite, since higher IgA responses were detected in nasal fluids of mice intranasally immunized with lysates plus either Cry1Ac or cholera toxin, which, indeed, were the treatments that provided the major protection levels. In contrast, serum antibody responses do not seem to be related to the protection level achieved. Both acquired and innate immune systems seem to play a role in host defense against N. fowleri infection, but further studies are required to elucidate the mechanisms involved in protective effects conferred by Cry1Ac, which may be a valuable tool to improve mucosal vaccines. PMID:15271892

PARFUME Theory and Model basis Report

Energy Technology Data Exchange (ETDEWEB)

Darrell L. Knudson; Gregory K Miller; G.K. Miller; D.A. Petti; J.T. Maki; D.L. Knudson

2009-09-01

The success of gas reactors depends upon the safety and quality of the coated particle fuel. The fuel performance modeling code PARFUME simulates the mechanical, thermal and physico-chemical behavior of fuel particles during irradiation. This report documents the theory and material properties behind vari¬ous capabilities of the code, which include: 1) various options for calculating CO production and fission product gas release, 2) an analytical solution for stresses in the coating layers that accounts for irradiation-induced creep and swelling of the pyrocarbon layers, 3) a thermal model that calculates a time-dependent temperature profile through a pebble bed sphere or a prismatic block core, as well as through the layers of each analyzed particle, 4) simulation of multi-dimensional particle behavior associated with cracking in the IPyC layer, partial debonding of the IPyC from the SiC, particle asphericity, and kernel migration (or amoeba effect), 5) two independent methods for determining particle failure probabilities, 6) a model for calculating release-to-birth (R/B) ratios of gaseous fission products that accounts for particle failures and uranium contamination in the fuel matrix, and 7) the evaluation of an accident condition, where a particle experiences a sudden change in temperature following a period of normal irradiation. The accident condi¬tion entails diffusion of fission products through the particle coating layers and through the fuel matrix to the coolant boundary. This document represents the initial version of the PARFUME Theory and Model Basis Report. More detailed descriptions will be provided in future revisions.

CYP51 is an essential drug target for the treatment of primary amoebic meningoencephalitis (PAM).

Science.gov (United States)

Debnath, Anjan; Calvet, Claudia M; Jennings, Gareth; Zhou, Wenxu; Aksenov, Alexander; Luth, Madeline R; Abagyan, Ruben; Nes, W David; McKerrow, James H; Podust, Larissa M

2017-12-01

Primary Amoebic Meningoencephalitis (PAM) is caused by Naegleria fowleri, a free-living amoeba that occasionally infects humans. While considered "rare" (but likely underreported) the high mortality rate and lack of established success in treatment makes PAM a particularly devastating infection. In the absence of economic inducements to invest in development of anti-PAM drugs by the pharmaceutical industry, anti-PAM drug discovery largely relies on drug 'repurposing'-a cost effective strategy to apply known drugs for treatment of rare or neglected diseases. Similar to fungi, N. fowleri has an essential requirement for ergosterol, a building block of plasma and cell membranes. Disruption of sterol biosynthesis by small-molecule inhibitors is a validated interventional strategy against fungal pathogens of medical and agricultural importance. The N. fowleri genome encodes the sterol 14-demethylase (CYP51) target sharing ~35% sequence identity to fungal orthologues. The similarity of targets raises the possibility of repurposing anti-mycotic drugs and optimization of their usage for the treatment of PAM. In this work, we (i) systematically assessed the impact of anti-fungal azole drugs, known as conazoles, on sterol biosynthesis and viability of cultured N. fowleri trophozotes, (ii) identified the endogenous CYP51 substrate by mass spectrometry analysis of N. fowleri lipids, and (iii) analyzed the interactions between the recombinant CYP51 target and conazoles by UV-vis spectroscopy and x-ray crystallography. Collectively, the target-based and parasite-based data obtained in these studies validated CYP51 as a potentially 'druggable' target in N. fowleri, and conazole drugs as the candidates for assessment in the animal model of PAM.

A decade of intestinal protozoan epidemiology among settled immigrants in Qatar.

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Abu-Madi, Marawan A; Behnke, Jerzy M; Boughattas, Sonia; Al-Thani, Asma; Doiphode, Sanjay H

2016-08-05

The World Health Organization estimates that about 3.5 billion people worldwide are affected by intestinal parasitic infections. Reports have already emphasized the role of immigrants in outbreaks of parasitic diseases in industrialized countries. With the mass influx of immigrants to Qatar, patent intestinal parasitic infections have been observed. Herein, the prevalence of intestinal protozoan infections was analysed in 29,286 records of subjects referred for stool examination at the Hamad Medical Corporation over the course of a decade (2005 to 2014, inclusive). Overall prevalence of combined protozoan infections was 5.93 % but there were significant temporal trends, age and sex effects and those arising from the region of origin of the subjects. The most common protozoan was Blastocystis hominis (overall prevalence 3.45 %). Giardia duodenalis, Chilomastix mesnili, Entamoeba coli, Entamoeba hartmanni, Endolimax nana, Iodamoeba butschlii, Entamoeba histolytica/dispar, Cryptosporidium sp. and a single case of Isospora were also detected. The prevalence of combined protozoan infections, G. duodenalis and the non-pathogenic amoebae all declined significantly across the decade. That of B. hominis varied between years but showed no directional trend across years and there was no evidence that prevalence of E. histolyitica/dispar changed significantly. Protozoan infections were observed among all regional groups, but prevalence was higher among subjects from the Arabian Peninsula, Africa and Asia compared to those from the Eastern Mediterranean and Qatar. Prevalence was higher among male subjects in all cases, but age-prevalence profiles differed between the taxa. These results offer optimism that prevalence will continue to decline in the years ahead.

Resistance of Acanthamoeba Cysts to Disinfection Treatments Used in Health Care Settings▿

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Coulon, Céline; Collignon, Anne; McDonnell, Gerald; Thomas, Vincent

2010-01-01

Free-living amoebae that belong to the genus Acanthamoeba are widespread in the environment, including water. They are responsible for human infections and can host pathogenic microorganisms. Under unfavorable conditions, they form cysts with high levels of resistance to disinfection methods, thus potentially representing a threat to public health. In the present study we evaluated the efficacies of various biocides against trophozoites and cysts of several Acanthamoeba strains. We demonstrated that disinfectant efficacy varied depending on the strains tested, with environmental strains demonstrating greater resistance than collection strains. Trophozoites were inactivated by all treatments except those using glutaraldehyde as an active compound: for these treatments, we observed resistance even after 30 min exposure. Cysts resisted many treatments, including certain conditions with glutaraldehyde and other biocides. Moist heat at 55°C was not efficient against cysts, whereas exposure at 65°C was. Several chemical formulations containing peracetic acid, hydrogen peroxide, or ortho-phthalaldehyde presented greater efficacy than glutaraldehyde, as did ethanol and sodium hypochlorite; however, some of these treatments required relatively long incubation times to achieve cyst inactivation. Amoebal cysts can be highly resistant to some high-level disinfectants, which has implications for clinical practice. These results highlight the need to consider the effective disinfection of protozoa in their vegetative and resistant forms due to their intrinsic resistance. This is important not only to prevent the transmission of protozoa themselves but also due to the risks associated with a range of microbial pathogens that are found to be associated intracellularly with these microorganisms. PMID:20519477

Diverse protist grazers select for virulence-related traits in Legionella

Science.gov (United States)

Amaro, Francisco; Wang, Wen; Gilbert, Jack A; Roger Anderson, O; Shuman, Howard A

2015-01-01

It is generally accepted that selection for resistance to grazing by protists has contributed to the evolution of Legionella pneumophila as a pathogen. Grazing resistance is becoming more generally recognized as having an important role in the ecology and evolution of bacterial pathogenesis. However, selection for grazing resistance presupposes the existence of protist grazers that provide the selective pressure. To determine whether there are protists that graze on pathogenic Legionella species, we investigated the existence of such organisms in a variety of environmental samples. We isolated and characterized diverse protists that graze on L. pneumophila and determined the effects of adding L. pneumophila on the protist community structures in microcosms made from these environmental samples. Several unrelated organisms were able to graze efficiently on L. pneumophila. The community structures of all samples were markedly altered by the addition of L. pneumophila. Surprisingly, some of the Legionella grazers were closely related to species that are known hosts for L. pneumophila, indicating the presence of unknown specificity determinants for this interaction. These results provide the first direct support for the hypothesis that protist grazers exert selective pressure on Legionella to acquire and retain adaptations that contribute to survival, and that these properties are relevant to the ability of the bacteria to cause disease in people. We also report a novel mechanism of killing of amoebae by one Legionella species that requires an intact Type IV secretion system but does not involve intracellular replication. We refer to this phenomenon as ‘food poisoning'. PMID:25575308

Design and fabrication of an advanced TRISO fuel with ZrC coating

Energy Technology Data Exchange (ETDEWEB)

Porter, Ian E., E-mail: porteri@email.sc.edu [University of South Carolina, Mechanical Engineering Department, 300 Main Street, Columbia, SC 29208, United Sates (United States); Knight, Travis W., E-mail: knighttw@cec.sc.edu [University of South Carolina, Mechanical Engineering Department, 300 Main Street, Columbia, SC 29208, United Sates (United States); Dulude, Michael C., E-mail: dulude@email.sc.edu [University of South Carolina, Mechanical Engineering Department, 300 Main Street, Columbia, SC 29208, United Sates (United States); Roberts, Elwyn, E-mail: robertse@cec.sc.edu [University of South Carolina, Mechanical Engineering Department, 300 Main Street, Columbia, SC 29208, United Sates (United States); Hobbs, Jim, E-mail: JSHobbs@nuclearfuelservices.com [Nuclear Fuel Services, Inc., 1205 Banner Hill Road, Erwin, TN 37650 (United States)

2013-06-15

Highlights: • Zirconium carbide was deposited on surrogate zirconia and UO{sub 2} kernels. • Deposition rates were found to be dependent on temperature and gas concentration. • Calcining and sintering parameters were optimized to reduce cracking in UO{sub 2} kernel production. -- Abstract: Very high temperature reactors (VHTRs) are expected to achieve coolant outlet temperatures up to 1000 °C, allowing for increased plant efficiency as well as the ability to use the process heat for hydrogen production and various uses in the process chemical industry. The feasibility of using VHTRs as part of the next generation of nuclear reactors greatly depends on the reliability of tri-structural isotropic (TRISO) fuel particles to retain both gaseous and metallic fission products created in irradiated uranium dioxide (UO{sub 2}). This work sought the deposition parameters necessary to produce an additional zirconium carbide (ZrC) layer used in advanced coated particle fuels. The additional ZrC layer will act as an oxygen getter to prevent typical TRISO failure mechanisms including over pressurization of the particle and kernel migration of the kernel within the particle, also known as the amoeba effect. In this study, ZrC coatings were applied to surrogate zirconia kernels as well as UO{sub 2} kernels using a chemical vapor deposition (CVD) fluidized bed reactor, and the deposition characteristics were analyzed via scanning electron microscopy (SEM) techniques. The ZrC layer was confirmed through X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The calcining and sintering of urania kernels for use in these coating experiments is also discussed.

Design and fabrication of an advanced TRISO fuel with ZrC coating

International Nuclear Information System (INIS)

Porter, Ian E.; Knight, Travis W.; Dulude, Michael C.; Roberts, Elwyn; Hobbs, Jim

2013-01-01

Highlights: • Zirconium carbide was deposited on surrogate zirconia and UO 2 kernels. • Deposition rates were found to be dependent on temperature and gas concentration. • Calcining and sintering parameters were optimized to reduce cracking in UO 2 kernel production. -- Abstract: Very high temperature reactors (VHTRs) are expected to achieve coolant outlet temperatures up to 1000 °C, allowing for increased plant efficiency as well as the ability to use the process heat for hydrogen production and various uses in the process chemical industry. The feasibility of using VHTRs as part of the next generation of nuclear reactors greatly depends on the reliability of tri-structural isotropic (TRISO) fuel particles to retain both gaseous and metallic fission products created in irradiated uranium dioxide (UO 2 ). This work sought the deposition parameters necessary to produce an additional zirconium carbide (ZrC) layer used in advanced coated particle fuels. The additional ZrC layer will act as an oxygen getter to prevent typical TRISO failure mechanisms including over pressurization of the particle and kernel migration of the kernel within the particle, also known as the amoeba effect. In this study, ZrC coatings were applied to surrogate zirconia kernels as well as UO 2 kernels using a chemical vapor deposition (CVD) fluidized bed reactor, and the deposition characteristics were analyzed via scanning electron microscopy (SEM) techniques. The ZrC layer was confirmed through X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The calcining and sintering of urania kernels for use in these coating experiments is also discussed

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...

Molecular evolution of the reactive oxygen-generating NADPH oxidase (Nox/Duox family of enzymes

Directory of Open Access Journals (Sweden)

Lambeth J David

2007-07-01

Full Text Available Abstract Background NADPH-oxidases (Nox and the related Dual oxidases (Duox play varied biological and pathological roles via regulated generation of reactive oxygen species (ROS. Members of the Nox/Duox family have been identified in a wide variety of organisms, including mammals, nematodes, fruit fly, green plants, fungi, and slime molds; however, little is known about the molecular evolutionary history of these enzymes. Results We assembled and analyzed the deduced amino acid sequences of 101 Nox/Duox orthologs from 25 species, including vertebrates, urochordates, echinoderms, insects, nematodes, fungi, slime mold amoeba, alga and plants. In contrast to ROS defense enzymes, such as superoxide dismutase and catalase that are present in prokaryotes, ROS-generating Nox/Duox orthologs only appeared later in evolution. Molecular taxonomy revealed seven distinct subfamilies of Noxes and Duoxes. The calcium-regulated orthologs representing 4 subfamilies diverged early and are the most widely distributed in biology. Subunit-regulated Noxes represent a second major subdivision, and appeared first in fungi and amoeba. Nox5 was lost in rodents, and Nox3, which functions in the inner ear in gravity perception, emerged the most recently, corresponding to full-time adaptation of vertebrates to land. The sea urchin Strongylocentrotus purpuratus possesses the earliest Nox2 co-ortholog of vertebrate Nox1, 2, and 3, while Nox4 first appeared somewhat later in urochordates. Comparison of evolutionary substitution rates demonstrates that Nox2, the regulatory subunits p47phox and p67phox, and Duox are more stringently conserved in vertebrates than other Noxes and Nox regulatory subunits. Amino acid sequence comparisons identified key catalytic or regulatory regions, as 68 residues were highly conserved among all Nox/Duox orthologs, and 14 of these were identical with those mutated in Nox2 in variants of X-linked chronic granulomatous disease. In addition to

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.

PLATYAMOEBA PSEUDOVANNELLIDA N. SP., A NAKED AMOEBA WITH WIDE SALT TOLERANCE ISOLATED FROM THE SALTON SEA, CALIFORNIA. (R826552)

Science.gov (United States)

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Characterization of the SPI-1 and Rsp type three secretion systems in Pseudomonas fluorescens F113.

Science.gov (United States)

Barret, Matthieu; Egan, Frank; Moynihan, Jennifer; Morrissey, John P; Lesouhaitier, Olivier; O'Gara, Fergal

2013-06-01

Pseudomonas fluorescens F113 is a plant growth-promoting rhizobacterium (PGPR) isolated from the sugar beet rhizosphere. The recent annotation of the F113 genome sequence has revealed that this strain encodes a wide array of secretion systems, including two complete type three secretion systems (T3SSs) belonging to the Hrp1 and SPI-1 families. While Hrp1 T3SSs are frequently encoded in other P. fluorescens strains, the presence of a SPI-1 T3SS in a plant-beneficial bacterial strain was unexpected. In this work, the genetic organization and expression of these two T3SS loci have been analysed by a combination of transcriptional reporter fusions and transcriptome analyses. Overexpression of two transcriptional activators has shown a number of genes encoding putative T3 effectors. In addition, the influence of these two T3SSs during the interaction of P. fluorescens F113 with some bacterial predators was also assessed. Our data revealed that the transcriptional activator hilA is induced by amoeba and that the SPI-1 T3SS could potentially be involved in resistance to amoeboid grazing. © 2013 John Wiley & Sons Ltd and Society for Applied Microbiology.

Gene discovery by chemical mutagenesis and whole-genome sequencing in Dictyostelium.

Science.gov (United States)

Li, Cheng-Lin Frank; Santhanam, Balaji; Webb, Amanda Nicole; Zupan, Blaž; Shaulsky, Gad

2016-09-01

Whole-genome sequencing is a useful approach for identification of chemical-induced lesions, but previous applications involved tedious genetic mapping to pinpoint the causative mutations. We propose that saturation mutagenesis under low mutagenic loads, followed by whole-genome sequencing, should allow direct implication of genes by identifying multiple independent alleles of each relevant gene. We tested the hypothesis by performing three genetic screens with chemical mutagenesis in the social soil amoeba Dictyostelium discoideum Through genome sequencing, we successfully identified mutant genes with multiple alleles in near-saturation screens, including resistance to intense illumination and strong suppressors of defects in an allorecognition pathway. We tested the causality of the mutations by comparison to published data and by direct complementation tests, finding both dominant and recessive causative mutations. Therefore, our strategy provides a cost- and time-efficient approach to gene discovery by integrating chemical mutagenesis and whole-genome sequencing. The method should be applicable to many microbial systems, and it is expected to revolutionize the field of functional genomics in Dictyostelium by greatly expanding the mutation spectrum relative to other common mutagenesis methods. © 2016 Li et al.; Published by Cold Spring Harbor Laboratory Press.

The Three Laws of Thought, Plus One: The Law of Comparisons

Directory of Open Access Journals (Sweden)

Thomas L. Saaty

2014-02-01

Full Text Available The rules of logic are nearly 2500 years old and date back to Plato and Aristotle who set down the three laws of thought: identity, non-contradiction, and excluded middle. The use of language and logic has been adequate for us to develop mathematics, prove theorems, and create scientific knowledge. However, the laws of thought are incomplete. We need to extend our logical system by adding to the very old laws of thought an essential yet poorly understood law. It is a necessary law of thought that resides in our biology even deeper than the other three laws. It is related to the rudiments of how we as living beings, and even nonliving things, respond to influences as stimuli. It helps us discriminate between being ourselves and sensing that there is something else that is not ourselves that even amoebas seem to know. It is the intrinsic ability to sense and distinguish. This fourth law is the law of comparisons. Although it has been missing from our logical deductions it underlies the other three laws of thought because without it we cannot know what is and what is not.

Sampling gene diversity across the supergroup Amoebozoa: large EST data sets from Acanthamoeba castellanii, Hartmannella vermiformis, Physarum polycephalum, Hyperamoeba dachnaya and Hyperamoeba sp.

Science.gov (United States)

Watkins, Russell F; Gray, Michael W

2008-04-01

From comparative analysis of EST data for five taxa within the eukaryotic supergroup Amoebozoa, including two free-living amoebae (Acanthamoeba castellanii, Hartmannella vermiformis) and three slime molds (Physarum polycephalum, Hyperamoeba dachnaya and Hyperamoeba sp.), we obtained new broad-range perspectives on the evolution and biosynthetic capacity of this assemblage. Together with genome sequences for the amoebozoans Dictyostelium discoideum and Entamoeba histolytica, and including partial genome sequence available for A. castellanii, we used the EST data to identify genes that appear to be exclusive to the supergroup, and to specific clades therein. Many of these genes are likely involved in cell-cell communication or differentiation. In examining on a broad scale a number of characters that previously have been considered in simpler cross-species comparisons, typically between Dictyostelium and Entamoeba, we find that Amoebozoa as a whole exhibits striking variation in the number and distribution of biosynthetic pathways, for example, ones for certain critical stress-response molecules, including trehalose and mannitol. Finally, we report additional compelling cases of lateral gene transfer within Amoebozoa, further emphasizing that although this process has influenced genome evolution in all examined amoebozoan taxa, it has done so to a variable extent.

[Detection of Entamoeba histolytica and Entamoeba dispar by PCR in children, less than five years of age with diarrhea, in Maracaibo, Venezuela. A preliminary study].

Science.gov (United States)

Bracho Mora, Angela; Rivero de Rodríguez, Zulbey; Arraiz, Nailet; Villalobos, Rafael; Urdaneta, Haydee

2013-12-01

To determine the prevalence of Entamoeba histolytica as a producer of diarrhea, a study was conducted in children, less than five years of age, with diarrhea who attended several out patient clinics of the Servicio Aut6nomo Hospital Universitario, Maracaibo, Venezuela. A macroscopic and microscopic examination with physiological saline, lugol and Kinyoun staining were performed to the stool samples obtained. The remainder of the sample was frozen until DNA extraction, and PCR amplification was performed separately for E. histolytica and E. dispar. Microscopic examination showed no trophozoites and/or cysts of Entamoeba histolytica/dispar/moshkovskii, or intestinal coccidians in any of the 50 samples analyzed. Parasites detected were Giardia lamblia (6%), Blastocystis sp. (4%), Pentatrichomonas hominis (2%), Ascaris lumbricoides (2%) and Trichuris trichiura (2%). By PCR, six samples (12%) had DNA of E. dispar and two (4%) had DNA from E. histolytica; no child showed association of both amoebae. The two children who had E. histolytica were one-year-old. E. dispar was detected in younger children. We suggest that the prevalence of E. histolytica in children under five years is really low.

Isolation of Balamuthia mandrillaris from urban dust, free of known infectious involvement.

Science.gov (United States)

Niyyati, Maryam; Lorenzo-Morales, Jacob; Rezaeian, Mostafa; Martin-Navarro, Carmen M; Haghi, Afsaneh Motevalli; Maciver, Sutherland K; Valladares, Basilio

2009-12-01

The free-living amoeba Balamuthia mandrillaris can cause fatal encephalitis in humans and other mammals. The organism is associated with soils, and soil exposure has been identified as a risk factor for this pathogen. However, B. mandrillaris has been isolated only once from soils believed to be the source of the infection in child from California, USA who died of Balamuthia amoebic encephalitis and once from another unrelated soil source. We report for a third time the isolation of B. mandrillaris from the environment and for the second time its isolation from a sample not known to be involved with pathogenicity. We have established the new clonal B. mandrillaris strain (ID-19) in axenic media. The identity of our isolate was originally by morphology using a light microscope and this has been confirmed by 16S rRNA gene PCR. The new strain ID-19 groups with others of the species. The fact that our isolate came from dust particles deposited on surfaces from the air in an urban environment may suggest that it is not just soil exposure that constitutes a risk factor for Balamuthia infection. This is the first report of this organism from Iran.

Discrepancy between species borders at morphological and molecular levels in the genus Cochliopodium (Amoebozoa, Himatismenida), with the description of Cochliopodium plurinucleolum n. sp.

Science.gov (United States)

Geisen, Stefan; Kudryavtsev, Alexander; Bonkowski, Michael; Smirnov, Alexey

2014-05-01

Amoebae of the genus Cochliopodium are characterized by a tectum that is a layer of scales covering the dorsal surface of the cell. A combination of scale structure, morphological features and, nowadays, molecular information allows species discrimination. Here we describe a soil species Cochliopodium plurinucleolum n. sp. that besides strong genetic divergence from all currently described species of Cochliopodium differs morphologically by the presence of several peripheral nucleoli in the nucleus. Further, we unambiguously show that the Golgi attachment associated with a dictyosome in Cochliopodium is a cytoplasmic microtubule organizing center (MTOC). Last, we provide detailed morphological and molecular information on the sister clade of C. plurinucleolum, containing C. minus, C. minutoidum, C. pentatrifurcatum and C. megatetrastylus. These species share nearly identical sequences of both, small subunit ribosomal RNA and partial Cox1 genes, and nearly identical structure of the scales. Scales of C. pentatrifurcatum differ, however, strongly from scales of the others while sequences of C. pentatrifurcatum and C. minus are nearly identical. These discrepancies urge for future sampling efforts to disentangle species characteristics within Cochliopdium and to investigate morphological and molecular patterns that allow reliable species differentiation. Copyright © 2014 Elsevier GmbH. All rights reserved.

Project CLIMPEAT - Influence of global warming and drought on the carbon sequestration and biodiversity of Sphagnum peatlands

Science.gov (United States)

Lamentowicz, M.; Buttler, A.; Mitchell, E. A. D.; Chojnicki, B.; Słowińska, S.; Słowiński, M.

2012-04-01

Northern peatlands represent a globally significant pool of carbon and are subject to the highest rates of climate warming, and most of these peatlands are in continental settings. However, it is unclear if how fast peatlands respond to past and present changes in temperature and surface moisture in continental vs. oceanic climate settings. The CLIMPEAT project brings together scientists from Poland and Switzerland. Our goal is to assess the past and present vulnerability to climate change of Sphagnum peatland plant and microbial communities, peat organic matter transformations and carbon sequestration using a combination of field and mesocosm experiments simulating warming and water table changes and palaeoecological studies. Warming will be achieved using ITEX-type "Open-Top Chambers". The field studies are conducted in Poland, at the limit between oceanic and continental climates, and are part of a network of projects also including field experiments in the French Jura (sub-oceanic) and in Siberia (continental). We will calibrate the response of key biological (plants, testate amoebae) and geochemical (isotopic composition of organic compounds, organic matter changes) proxies to warming and water table changes and use these proxies to reconstruct climate changes during the last 1000 years.

Cunea n. g. (Amoebozoa, Dactylopodida) with two cryptic species isolated from different areas of the ocean

KAUST Repository

Kudryavtsev, Alexander

2015-06-01

© 2015 Elsevier GmbH. This paper describes a new genus, Cunea n. g., of marine naked amoebae with two cryptic species, Cunea profundata and Cunea thuwala, isolated from distant localities in the ocean and different depths (Brazilian abyssal plain, Western Atlantic Ocean, depth >5. km and the Red Sea off the Saudi Arabian coast, depth ca. 58.7. m). Both species are very similar to each other in the set of light microscopic and ultrastructural characters and might be described as a single species, yet their genetic divergence based on 3 molecular markers (small-subunit ribosomal RNA, actin and cytochrome c oxidase subunit 1) corresponds to the level of variation typically observed between different morphospecies of Amoebozoa. In addition, the studied strains differ strongly in their temperature tolerance ranges, C. profundata isolated from the cold Atlantic deep-sea habitat being able to reproduce under lower temperatures than C. thuwala isolated from the warm Red Sea benthos. Molecular phylogenetic analysis based on SSU rRNA gene shows that the new genus robustly branches within the Dactylopodida, but forms an independent clade within this order that does not group with any of its known genera.

An apparent Acanthamoeba genotype is the product of a chimeric 18S rDNA artifact.

Science.gov (United States)

Corsaro, Daniele; Venditti, Danielle

2018-02-01

Free-living amoebae of the genus Acanthamoeba are potentially pathogenic protozoa widespread in the environment. The detection/diagnosis as well as environmental survey strategies is mainly based on the identification of the 18S rDNA sequences of the strains that allow the recovery of various distinct genotypes/subgenotypes. The accurate recording of such data is important to better know the environmental distribution of distinct genotypes and how they may be preferentially associated with disease. Recently, a putative new acanthamoebal genotype T99 was introduced, which comprises only environmental clones apparently with some anomalous features. Here, we analyze these sequences through partial treeing and BLAST analyses and find that they are actually chimeras. Our results show that the putative T99 genotype is very likely formed by chimeric sequences including a middle fragment from acanthamoebae of genotype T13, while the 5'- and 3'-end fragments came from a nematode and a cercozoan, respectively. Molecular phylogenies of Acanthamoeba including T99 are consequently erroneous as genotype T99 does not exist in nature. Careful identification of Acanthamoeba genotypes is therefore critical for both phylogenetic and diagnostic applications.

Deciphering the genomes of 16 Acanthamoeba species does not provide evidence of integration of known giant virus-associated mobile genetic elements.

Science.gov (United States)

Chelkha, Nisrine; Colson, Philippe; Levasseur, Anthony; La Scola, Bernard

2018-06-02

Giant viruses infect protozoa, especially amoebae of the genus Acanthamoeba. These viruses possess genetic elements named Mobilome. So far, this mobilome comprises provirophages which are integrated into the genome of their hosts, transpovirons, and Maverick/Polintons. Virophages replicate inside virus factories within Acanthamoeba and can decrease the infectivity of giant viruses. The virophage infecting CroV was found to be integrated in the host of CroV, Cafeteria roenbergensis, thus protecting C. roenbergensis by reduction of CroV multiplication. Because of this unique property, assessment of the mechanisms of replication of virophages and their relationship with giant viruses is a key element of this investigation. This work aimed at evaluating the presence and the dynamic of these mobile elements in sixteen Acanthamoeba genomes. No significant traces of the integration of genomes or sequences from known virophages were identified in all the available Acanthamoeba genomes. These results brought us to hypothesize that the interactions between mimiviruses and their virophages might occur through different mechanisms, or at low frequency. An additional explanation could be that our knowledge of the diversity of virophages is still very limited. Copyright © 2018 Elsevier B.V. All rights reserved.

Cunea n. g. (Amoebozoa, Dactylopodida) with two cryptic species isolated from different areas of the ocean

KAUST Repository

Kudryavtsev, Alexander; Pawlowski, Jan

2015-01-01

© 2015 Elsevier GmbH. This paper describes a new genus, Cunea n. g., of marine naked amoebae with two cryptic species, Cunea profundata and Cunea thuwala, isolated from distant localities in the ocean and different depths (Brazilian abyssal plain, Western Atlantic Ocean, depth >5. km and the Red Sea off the Saudi Arabian coast, depth ca. 58.7. m). Both species are very similar to each other in the set of light microscopic and ultrastructural characters and might be described as a single species, yet their genetic divergence based on 3 molecular markers (small-subunit ribosomal RNA, actin and cytochrome c oxidase subunit 1) corresponds to the level of variation typically observed between different morphospecies of Amoebozoa. In addition, the studied strains differ strongly in their temperature tolerance ranges, C. profundata isolated from the cold Atlantic deep-sea habitat being able to reproduce under lower temperatures than C. thuwala isolated from the warm Red Sea benthos. Molecular phylogenetic analysis based on SSU rRNA gene shows that the new genus robustly branches within the Dactylopodida, but forms an independent clade within this order that does not group with any of its known genera.

Development of perianal ulcer as a result of acute fulminant amoebic colitis.

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Torigoe, Takayuki; Nakayama, Yoshifumi; Yamaguchi, Koji

2012-09-14

We report a case of acute fulminant amoebic colitis that resulted in the development of a perianal ulcer in a 29-year-old Japanese homosexual man with acquired immunodeficiency syndrome (AIDS). The patient was admitted to our hospital with a persistent perianal abscess that was refractory to antibiotic therapy administered at another hospital. On admission, we observed a giant ulcer in the perianal region. At first, cytomegalovirus colitis was suspected by blood investigations. Ganciclovir therapy was initiated; however, the patient developed necrosis of the skin around the anus during therapy. We only performed end-sigmoidostomy and necrotomy to avoid excessive surgical invasion. Histopathological examination of the surgical specimen revealed the presence of trophozoite amoebae, indicating a final diagnosis of acute fulminant amoebic colitis. The patient's postoperative course was favorable, and proctectomy of the residual rectum was performed 11 mo later. Amoebic colitis is one of the most severe complications affecting patients with AIDS. Particularly, acute fulminant amoebic colitis may result in a poor prognosis; therefore, staged surgical therapy as a less invasive procedure should be considered as one of the treatment options for these patients.

Energetics of formation and migration of self-interstitials and self-interstitial clusters in α-iron

International Nuclear Information System (INIS)

Wirth, B.D.; Odette, G.R.; California Univ., Santa Barbara, CA; Maroudas, D.; Lucas, G.E.; California Univ., Santa Barbara, CA

1997-01-01

Energetic primary recoil atoms from fast neutron irradiation generate both isolated point defects and clusters of vacancies and interstitials. Self-interstitial mobility as well as defect cluster stability and mobility play key roles in the subsequent fate of defects and, hence, in the overall microstructural evolution under irradiation. Self-interstitials and two, three and four-member self-interstitial clusters are highly mobile at low temperatures as observed in molecular-dynamics simulations and high mobility probably also extends to larger clusters. In this study, the morphology, energetics and mobility of self-interstitials and small self-interstitial clusters in α-iron are studied by molecular-statics and molecular-dynamics simulations using a Finnis-Sinclair many-body interatomic potential. Self-interstitial migration is found to be a two-step process consisting of a rotation out of the split-dumbbell configuration into the split-dumbbell configuration and translational jumps through the crowdion configuration before returning to the dumbbell configuration. Self-interstitial clusters of type split-interstitials assembled on adjacent {110} planes migrate along directions in an amoeba-like fashion by sequential local dissociation and re-association processes. (orig.)

TM9/Phg1 and SadA proteins control surface expression and stability of SibA adhesion molecules in Dictyostelium.

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Froquet, Romain; le Coadic, Marion; Perrin, Jackie; Cherix, Nathalie; Cornillon, Sophie; Cosson, Pierre

2012-02-01

TM9 proteins form a family of conserved proteins with nine transmembrane domains essential for cellular adhesion in many biological systems, but their exact role in this process remains unknown. In this study, we found that genetic inactivation of the TM9 protein Phg1A dramatically decreases the surface levels of the SibA adhesion molecule in Dictyostelium amoebae. This is due to a decrease in sibA mRNA levels, in SibA protein stability, and in SibA targeting to the cell surface. A similar phenotype was observed in cells devoid of SadA, a protein that does not belong to the TM9 family but also exhibits nine transmembrane domains and is essential for cellular adhesion. A contact site A (csA)-SibA chimeric protein comprising only the transmembrane and cytosolic domains of SibA and the extracellular domain of the Dictyostelium surface protein csA also showed reduced stability and relocalization to endocytic compartments in phg1A knockout cells. These results indicate that TM9 proteins participate in cell adhesion by controlling the levels of adhesion proteins present at the cell surface.

Combustible shales of the U. S. S. R

Energy Technology Data Exchange (ETDEWEB)

Dobryanskii, A F

1947-01-01

Without exception, the geological character of all known oil shales (including sapropelic shales) indicates an aqueous origin for these minerals. The initial organic material of shales has accumulated in every geological period from Cambrian to the present time. Algae, amoeba, rhizopoda, multicellular organisms, and highly organized animals and plants were the forerunners of an intermediate decomposition product referred to as ''pelogen.'' After deposition, pelogen is transformed into sapropels under the influence of anerobic conditions. The composition of sapropel depends upon the percentage of humic acids, lignins, bitumens, albumin, and similar materials that were present in the pelogen. Wax and solid hydrocarbons do not contribute significantly to the process of conversion. Factors that affect the composition of the sapropel are prevalence of plant or animal matter, age of the sapropel, and depth of burial. The basic reaction involved in the change from pelogen to sapropel consisted of an increase in carbon and hydrogen content and a decrease in oxygen content. During this change, hydroxyl groups were removed in the form of water, carboxyl in the form of carbon dioxide gas, and ethereal oxygen in the form of carbon dioxide and carbon monoxide.

Scalable improvement of SPME multipolar electrostatics in anisotropic polarizable molecular mechanics using a general short-range penetration correction up to quadrupoles.

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Narth, Christophe; Lagardère, Louis; Polack, Étienne; Gresh, Nohad; Wang, Qiantao; Bell, David R; Rackers, Joshua A; Ponder, Jay W; Ren, Pengyu Y; Piquemal, Jean-Philip

2016-02-15

We propose a general coupling of the Smooth Particle Mesh Ewald SPME approach for distributed multipoles to a short-range charge penetration correction modifying the charge-charge, charge-dipole and charge-quadrupole energies. Such an approach significantly improves electrostatics when compared to ab initio values and has been calibrated on Symmetry-Adapted Perturbation Theory reference data. Various neutral molecular dimers have been tested and results on the complexes of mono- and divalent cations with a water ligand are also provided. Transferability of the correction is adressed in the context of the implementation of the AMOEBA and SIBFA polarizable force fields in the TINKER-HP software. As the choices of the multipolar distribution are discussed, conclusions are drawn for the future penetration-corrected polarizable force fields highlighting the mandatory need of non-spurious procedures for the obtention of well balanced and physically meaningful distributed moments. Finally, scalability and parallelism of the short-range corrected SPME approach are addressed, demonstrating that the damping function is computationally affordable and accurate for molecular dynamics simulations of complex bio- or bioinorganic systems in periodic boundary conditions. Copyright © 2016 Wiley Periodicals, Inc.

[New viral risks in blood transfusion by 2016].

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Pozzetto, B; Garraud, O

2016-02-01

Viral safety remains a major concern in transfusion of blood products. Over years, the control measures applied to blood products were made more and more sophisticated; however, the number of infectious agents, and notably of viruses, that can be transmitted by transfusion is increasing continuously. The aim of this review paper is to actualize that published in the same journal by the same authors in 2011 with more details on some of actual vs virtual viral threats that were identified recently in the field of blood transfusion. The main subjects that are covered successively concern the transmission via transfusion of hepatitis E virus, the frequency of transfusion transmitted arboviruses, transfusion at the time of the Ebola epidemics in West Africa, the debated role of Marseillevirus (giant viruses infecting amoebae and suspected to infect human blood latently), and, finally, the recent report of the identification in blood donors of a new member of the Flaviviridae family. The addition of these new viral risks to those already identified-partially controlled or not-pleads for the urgent need to move forward to considering inactivation of infectious agents in blood products. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Prevalence of protozoa species in drinking and environmental water sources in Sudan.

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Shanan, Salah; Abd, Hadi; Bayoumi, Magdi; Saeed, Amir; Sandström, Gunnar

2015-01-01

Protozoa are eukaryotic cells distributed worldwide in nature and are receiving increasing attention as reservoirs and potential vectors for the transmission of pathogenic bacteria. In the environment, on the other hand, many genera of the protozoa are human and animal pathogens. Only limited information is available on these organisms in developing countries and so far no information on their presence is available from Sudan. It is necessary to establish a molecular identification of species of the protozoa from drinking and environmental water. 600 water samples were collected from five states (Gadarif, Khartoum, Kordofan, Juba, and Wad Madani) in Sudan and analysed by polymerase chain reaction (PCR) and sequencing. 57 out of 600 water samples were PCR positive for protozoa. 38 out of the 57 positive samples were identified by sequencing to contain 66 protozoa species including 19 (28.8%) amoebae, 17 (25.7%) Apicomplexa, 25 (37.9%) ciliates, and 5 (7.6%) flagellates. This study utilized molecular methods identified species belonging to all phyla of protozoa and presented a fast and accurate molecular detection and identification of pathogenic as well as free-living protozoa in water uncovering hazards facing public health.

Prevalence of Protozoa Species in Drinking and Environmental Water Sources in Sudan

Directory of Open Access Journals (Sweden)

Salah Shanan

2015-01-01

Full Text Available Protozoa are eukaryotic cells distributed worldwide in nature and are receiving increasing attention as reservoirs and potential vectors for the transmission of pathogenic bacteria. In the environment, on the other hand, many genera of the protozoa are human and animal pathogens. Only limited information is available on these organisms in developing countries and so far no information on their presence is available from Sudan. It is necessary to establish a molecular identification of species of the protozoa from drinking and environmental water. 600 water samples were collected from five states (Gadarif, Khartoum, Kordofan, Juba, and Wad Madani in Sudan and analysed by polymerase chain reaction (PCR and sequencing. 57 out of 600 water samples were PCR positive for protozoa. 38 out of the 57 positive samples were identified by sequencing to contain 66 protozoa species including 19 (28.8% amoebae, 17 (25.7% Apicomplexa, 25 (37.9% ciliates, and 5 (7.6% flagellates. This study utilized molecular methods identified species belonging to all phyla of protozoa and presented a fast and accurate molecular detection and identification of pathogenic as well as free-living protozoa in water uncovering hazards facing public health.

Primary immigration and succession of soil organisms on reclaimed opencast coal mining areas in eastern Germany

Energy Technology Data Exchange (ETDEWEB)

Wanner, M.; Dunger, W. [Staatliches Museum Naturkunde, Gorlitz (Germany)

2002-07-01

Immigration to and colonisation of recultivated opencast coal mining areas by soil organisms were investigated in eastern Germany during the period 1996-1998 in freshly exposed substrates (immigration test) and two up to 46-year-old afforested mine soils (stage-dependent succession). The results indicate that immigration by air is characteristic for protists, soil microarthropods and spiders, while active locomotion is more important for the soil macrofauna. Testate amoebae assemblages showed no evident differences between 30-37-year-old Tertiary afforestations (ash-ameliorated, pyrite-rich, low soil pH) and 46-year-old Pleistocene sites (liming, low pyrite content, moderate soil pH), while comparisons in soil animals revealed pronounced differences in abundance, biomass and species composition. Generally, all investigated soil animal groups indicated taxon-specific immigration and colonisation strategies with pronounced site preferences, dependent on substrate quality, age and afforestation. Within 40 years, a consistent trend is visible from an open pioneer to a woodland community. Furthermore, it was demonstrated that long-term investigations as well as numerous taxa of different trophic levels are essential for a comprehensive evaluation of recultivated mine dumps.

Balamuthia mandrillaris: Morphology, biology, and virulence

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Siddiqui, Ruqaiyyah; Khan, Naveed Ahmed

2015-01-01

Balamuthia mandrillaris is a protist pathogen that can cause encephalitis with a fatality rate of >95%. This is due to our incomplete understanding of the pathogenesis and pathophysiology of B. mandrillaris encephalitis. B. mandrillaris has two stages in its life cycle, an active trophozoite stage during which it divides mitotically. However, under unfavorable conditions, the trophozoite transforms into a dormant cyst stage. A major concern during the course of therapy is that B. mandrillaris can transform into cysts. Cysts are highly resistant to physical and chemical conditions and present a problem in successful antimicrobial chemotherapy. Several lines of evidence suggest that B. mandrillaris encephalitis develops as a result of hematogenous spread, but it is unclear how circulating amoebae enter the central nervous system and cause inflammation, blood-brain barrier disruption, and neuronal injury. Recent studies have identified several parasite-host determinants for B. mandrillaris translocation of the blood-brain barrier, and host inflammatory markers that may be associated with neuronal injury. These determinants may provide important targets for the prevention and treatment of this devastating infection. Here, we present a brief overview of the current understanding of the morphology, biology, pathogenesis, and pathophysiology of B. mandrillaris encephalitis. PMID:25709948

Performance of extended Lagrangian schemes for molecular dynamics simulations with classical polarizable force fields and density functional theory.

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Vitale, Valerio; Dziedzic, Jacek; Albaugh, Alex; Niklasson, Anders M N; Head-Gordon, Teresa; Skylaris, Chris-Kriton

2017-03-28

Iterative energy minimization with the aim of achieving self-consistency is a common feature of Born-Oppenheimer molecular dynamics (BOMD) and classical molecular dynamics with polarizable force fields. In the former, the electronic degrees of freedom are optimized, while the latter often involves an iterative determination of induced point dipoles. The computational effort of the self-consistency procedure can be reduced by re-using converged solutions from previous time steps. However, this must be done carefully, as not to break time-reversal symmetry, which negatively impacts energy conservation. Self-consistent schemes based on the extended Lagrangian formalism, where the initial guesses for the optimized quantities are treated as auxiliary degrees of freedom, constitute one elegant solution. We report on the performance of two integration schemes with the same underlying extended Lagrangian structure, which we both employ in two radically distinct regimes-in classical molecular dynamics simulations with the AMOEBA polarizable force field and in BOMD simulations with the Onetep linear-scaling density functional theory (LS-DFT) approach. Both integration schemes are found to offer significant improvements over the standard (unpropagated) molecular dynamics formulation in both the classical and LS-DFT regimes.

From social network (centralized vs. decentralized) to collective decision-making (unshared vs. shared consensus).

Science.gov (United States)

Sueur, Cédric; Deneubourg, Jean-Louis; Petit, Odile

2012-01-01

Relationships we have with our friends, family, or colleagues influence our personal decisions, as well as decisions we make together with others. As in human beings, despotism and egalitarian societies seem to also exist in animals. While studies have shown that social networks constrain many phenomena from amoebae to primates, we still do not know how consensus emerges from the properties of social networks in many biological systems. We created artificial social networks that represent the continuum from centralized to decentralized organization and used an agent-based model to make predictions about the patterns of consensus and collective movements we observed according to the social network. These theoretical results showed that different social networks and especially contrasted ones--star network vs. equal network--led to totally different patterns. Our model showed that, by moving from a centralized network to a decentralized one, the central individual seemed to lose its leadership in the collective movement's decisions. We, therefore, showed a link between the type of social network and the resulting consensus. By comparing our theoretical data with data on five groups of primates, we confirmed that this relationship between social network and consensus also appears to exist in animal societies.

Efficient Cross-Modal Transfer of Shape Information in Visual and Haptic Object Categorization

Directory of Open Access Journals (Sweden)

Nina Gaissert

2011-10-01

Full Text Available Categorization has traditionally been studied in the visual domain with only a few studies focusing on the abilities of the haptic system in object categorization. During the first years of development, however, touch and vision are closely coupled in the exploratory procedures used by the infant to gather information about objects. Here, we investigate how well shape information can be transferred between those two modalities in a categorization task. Our stimuli consisted of amoeba-like objects that were parametrically morphed in well-defined steps. Participants explored the objects in a categorization task either visually or haptically. Interestingly, both modalities led to similar categorization behavior suggesting that similar shape processing might occur in vision and haptics. Next, participants received training on specific categories in one of the two modalities. As would be expected, training increased performance in the trained modality; however, we also found significant transfer of training to the other, untrained modality after only relatively few training trials. Taken together, our results demonstrate that complex shape information can be transferred efficiently across the two modalities, which speaks in favor of multisensory, higher-level representations of shape.