Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 467
Filtrar
1.
Appl Environ Microbiol ; 87(18): e0074721, 2021 08 26.
Artigo em Inglês | MEDLINE | ID: mdl-34232736

RESUMO

Here, we sought to test the resistance of human pathogens to unaltered environmental free-living amoebae. Amoebae are ubiquitous eukaryotic microorganisms and important predators of bacteria. Environmental amoebae have also been proposed to serve as both potential reservoirs and training grounds for human pathogens. However, studies addressing their relationships with human pathogens often rely on a few domesticated amoebae that have been selected to feed on rich medium, thereby possibly overestimating the resistance of pathogens to these predatory phagocytes. From an open-air composting site, we recovered over 100 diverse amoebae that were able to feed on Acinetobacter baumannii and Klebsiella pneumoniae. In a standardized and quantitative assay for predation, the isolated amoebae showed a broad predation spectrum, killing clinical isolates of A. baumannii, K. pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus. Interestingly, A. baumannii, which was previously reported to resist predation by laboratory strains of Acanthamoeba, was efficiently consumed by closely related environmental amoebae. The isolated amoebae were capable of feeding on highly virulent carbapenem-resistant or methicillin-resistant clinical isolates. In conclusion, the natural environment is a rich source of amoebae with broad-spectrum bactericidal activities, including against antibiotic-resistant isolates. IMPORTANCE Free-living amoebae have been proposed to play an important role in hosting and disseminating various human pathogens. The resistance of human pathogens to predation by amoebae is often derived from in vitro experiments using model amoebae. Here, we sought to isolate environmental amoebae and to test their predation on diverse human pathogens, with results that challenge conclusions based on model amoebae. We found that the natural environment is a rich source of diverse amoebae with broad-spectrum predatory activities against human pathogens, including highly virulent and antibiotic-resistant clinical isolates.


Assuntos
Amoeba/fisiologia , Bactérias/crescimento & desenvolvimento , Interações Microbianas , Antibacterianos , Carbapenêmicos , Compostagem , Farmacorresistência Bacteriana , Farmacorresistência Bacteriana Múltipla , Humanos , Microbiologia do Solo
2.
Genes (Basel) ; 12(4)2021 03 27.
Artigo em Inglês | MEDLINE | ID: mdl-33801615

RESUMO

Multicellularity evolved repeatedly in the history of life, but how it unfolded varies greatly between different lineages. Dictyostelid social amoebas offer a good system to study the evolution of multicellular complexity, with a well-resolved phylogeny and molecular genetic tools being available. We compare the life cycles of the Dictyostelids with closely related amoebozoans to show that complex life cycles were already present in the unicellular common ancestor of Dictyostelids. We propose frost resistance as an early driver of multicellular evolution in Dictyostelids and show that the cell signalling pathways for differentiating spore and stalk cells evolved from that for encystation. The stalk cell differentiation program was further modified, possibly through gene duplication, to evolve a new cell type, cup cells, in Group 4 Dictyostelids. Studies in various multicellular organisms, including Dictyostelids, volvocine algae, and metazoans, suggest as a common principle in the evolution of multicellular complexity that unicellular regulatory programs for adapting to environmental change serve as "proto-cell types" for subsequent evolution of multicellular organisms. Later, new cell types could further evolve by duplicating and diversifying the "proto-cell type" gene regulatory networks.


Assuntos
Amoeba/fisiologia , Dictyostelium/fisiologia , Estresse Fisiológico , Evolução Biológica , Temperatura Baixa , Evolução Molecular , Estágios do Ciclo de Vida , Filogenia , Transdução de Sinais
3.
Proc Natl Acad Sci U S A ; 118(6)2021 02 09.
Artigo em Inglês | MEDLINE | ID: mdl-33526668

RESUMO

Bacteria are inherently social organisms whose actions should ideally be studied within an interactive ecological context. We show that the exchange and modification of natural products enables two unrelated bacteria to defend themselves against a common predator. Amoebal predation is a major cause of death in soil bacteria and thus it exerts a strong selective pressure to evolve defensive strategies. A systematic analysis of binary combinations of coisolated bacteria revealed strains that were individually susceptible to predation but together killed their predator. This cooperative defense relies on a Pseudomonas species producing syringafactin, a lipopeptide, which induces the production of peptidases in a Paenibacillus strain. These peptidases then degrade the innocuous syringafactin into compounds, which kill the predator. A combination of bioprospecting, coculture experiments, genome modification, and transcriptomics unravel this novel natural product-based defense strategy.


Assuntos
Bactérias/metabolismo , Lipopeptídeos/metabolismo , Comportamento Predatório/fisiologia , Amoeba/fisiologia , Animais , Bactérias/classificação , Bactérias/crescimento & desenvolvimento , Perfilação da Expressão Gênica , Lipopeptídeos/química , Paenibacillus/citologia , Filogenia , Pseudomonas/citologia , Microbiologia do Solo
4.
PLoS One ; 16(2): e0246311, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33524055

RESUMO

Amoeboid cell migration is characterized by frequent changes of the direction of motion and resembles a persistent random walk on long time scales. Although it is well known that cell migration is typically driven by the actin cytoskeleton, the cause of this migratory behavior remains poorly understood. We analyze the spontaneous dynamics of actin assembly due to nucleation promoting factors, where actin filaments lead to an inactivation of these factors. We show that this system exhibits excitable dynamics and can spontaneously generate waves, which we analyze in detail. By using a phase-field approach, we show that these waves can generate cellular random walks. We explore how the characteristics of these persistent random walks depend on the parameters governing the actin-nucleator dynamics. In particular, we find that the effective diffusion constant and the persistence time depend strongly on the speed of filament assembly and the rate of nucleator inactivation. Our findings point to a deterministic origin of the random walk behavior and suggest that cells could adapt their migration pattern by modifying the pool of available actin.


Assuntos
Actinas/fisiologia , Amoeba/fisiologia , Movimento Celular/fisiologia , Citoesqueleto/fisiologia , Modelos Teóricos
5.
Biomolecules ; 11(1)2021 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-33467718

RESUMO

The ubiquitin pathway is highly conserved across the eukaryotic domain of life and plays an essential role in a plethora of cellular processes. It is not surprising that many intracellular bacterial pathogens often target the essential host ubiquitin pathway. The intracellular bacterial pathogen Legionella pneumophila injects into the host cell cytosol multiple classes of classical and novel ubiquitin-modifying enzymes that modulate diverse ubiquitin-related processes in the host cell. Most of these pathogen-injected proteins, designated as effectors, mimic known E3-ubiquitin ligases through harboring F-box or U-box domains. The classical F-box effector, AnkB targets host proteins for K48-linked polyubiquitination, which leads to excessive proteasomal degradation that is required to generate adequate supplies of amino acids for metabolism of the pathogen. In contrast, the SidC and SdcA effectors share no structural similarity to known eukaryotic ligases despite having E3-ubiquitin ligase activity, suggesting that the number of E3-ligases in eukaryotes is under-represented. L. pneumophila also injects into the host many novel ubiquitin-modifying enzymes, which are the SidE family of effectors that catalyze phosphoribosyl-ubiquitination of serine residue of target proteins, independently of the canonical E1-2-3 enzymatic cascade. Interestingly, the environmental bacterium, L. pneumophila, has evolved within a diverse range of amoebal species, which serve as the natural hosts, while accidental transmission through contaminated aerosols can cause pneumonia in humans. Therefore, it is likely that the novel ubiquitin-modifying enzymes of L. pneumophila were acquired by the pathogen through interkingdom gene transfer from the diverse natural amoebal hosts. Furthermore, conservation of the ubiquitin pathway across eukaryotes has enabled these novel ubiquitin-modifying enzymes to function similarly in mammalian cells. Studies on the biological functions of these effectors are likely to reveal further novel ubiquitin biology and shed further lights on the evolution of ubiquitin.


Assuntos
Adaptação Fisiológica , Amoeba/fisiologia , Evolução Biológica , Interações Hospedeiro-Patógeno/fisiologia , Legionella pneumophila/fisiologia , Ubiquitinação
6.
Environ Microbiol ; 23(1): 126-142, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33063404

RESUMO

As predators of bacteria, amoebae select for traits that allow bacteria to become symbionts by surviving phagocytosis and exploiting the eukaryotic intracellular environment. Soil-dwelling social amoebae can help us answer questions about the natural ecology of these amoeba-bacteria symbioses along the pathogen-mutualist spectrum. Our objective was to characterize the natural bacterial microbiome of phylogenetically and morphologically diverse social amoeba species using next-generation sequencing of 16S rRNA amplicons directly from amoeba fruiting bodies. We found six phyla of amoeba-associated bacteria: Proteobacteria, Bacteroidetes, Actinobacteria, Chlamydiae, Firmicutes, and Acidobacteria. The most common associates of amoebae were classified to order Chlamydiales and genus Burkholderia-Caballeronia-Paraburkholderia. These bacteria were present in multiple amoeba species across multiple locations. While there was substantial intraspecific variation, there was some evidence for host specificity and differentially abundant taxa between different amoeba hosts. Amoebae microbiomes were distinct from the microbiomes of their soil habitat, and soil pH affected amoeba microbiome diversity. Alpha-diversity was unsurprisingly lower in amoebae samples compared with soil, but beta-diversity between amoebae samples was higher than between soil samples. Further exploration of social amoebae microbiomes may help us understand the roles of bacteria, host, and environment on symbiotic interactions and microbiome formation in basal eukaryotic organisms.


Assuntos
Amoeba/microbiologia , Bactérias/isolamento & purificação , Especificidade de Hospedeiro , Microbiota , Microbiologia do Solo , Amoeba/fisiologia , Bactérias/classificação , Bactérias/genética , Fenômenos Fisiológicos Bacterianos , Filogenia , RNA Ribossômico 16S/genética , Solo/química , Simbiose
7.
Lett Appl Microbiol ; 72(1): 82-89, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32978979

RESUMO

Candida auris is an emerging species responsible for life-threatening infections. Its ability to be resistant to most systemic antifungal classes and its capacity to persist in a hospital environment have led to health concerns. Currently, data about environmental reservoirs are limited but remain essential in control of C. auris spread. The aim of our study was to explore the interactions between C. auris and two free-living amoeba (FLA) species, Vermamoeba vermiformis and Acanthamoeba castellanii, potentially found in the same water environment. Candida auris was incubated with FLA trophozoites or their culture supernatants. The number of FLA and yeasts was determined at different times and transmission electron microscopy (TEM) was performed. Supernatants of FLAs promoted yeast survival and proliferation. Internalization of viable C. auris within both FLA species was also evidenced by TEM. A water environmental reservoir of C. auris can therefore be considered through FLAs and contamination of the hospital water networks would consequently be possible.


Assuntos
Amoeba/fisiologia , Candida/fisiologia , Microbiologia da Água , Candida/crescimento & desenvolvimento , Candida albicans/fisiologia , Proliferação de Células
8.
Appl Environ Microbiol ; 87(2)2021 01 04.
Artigo em Inglês | MEDLINE | ID: mdl-33158887

RESUMO

Amoebae are protists that have complicated relationships with bacteria, covering the whole spectrum of symbiosis. Amoeba-bacterium interactions contribute to the study of predation, symbiosis, pathogenesis, and human health. Given the complexity of their relationships, it is necessary to understand the ecology and evolution of their interactions. In this paper, we provide an updated review of the current understanding of amoeba-bacterium interactions. We start by discussing the diversity of amoebae and their bacterial partners. We also define three types of ecological interactions between amoebae and bacteria and discuss their different outcomes. Finally, we focus on the implications of amoeba-bacterium interactions on human health, horizontal gene transfer, drinking water safety, and the evolution of symbiosis. In conclusion, amoeba-bacterium interactions are excellent model systems to investigate a wide range of scientific questions. Future studies should utilize advanced techniques to address research gaps, such as detecting hidden diversity, lack of amoeba genomes, and the impacts of amoeba predation on the microbiome.


Assuntos
Amoeba/fisiologia , Fenômenos Fisiológicos Bacterianos , Interações Microbianas , Bactérias
9.
PLoS One ; 15(11): e0235725, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33147262

RESUMO

Sex is a hallmark of eukaryotes but its evolution in microbial eukaryotes is poorly elucidated. Recent genomic studies revealed microbial eukaryotes possess a genetic toolkit necessary for sexual reproduction. However, the mechanism of sexual development in a majority of microbial eukaryotes including amoebozoans is poorly characterized. The major hurdle in studying sex in microbial eukaryotes is a lack of observational evidence, primarily due to its cryptic nature. In this study, we used a tractable fusing amoeba, Cochliopodium, to investigate sexual development using stage-specific Differential Gene Expression (DGE) and cytological analyses. Both DGE and cytological results showed that most of the meiosis and sex-related genes are upregulated in Cochliopodium undergoing fusion in laboratory culture. Relative gene ontology (GO) category representations in unfused and fused cells revealed a functional skew of the fused transcriptome toward DNA metabolism, nucleus and ligases that are suggestive of a commitment to sexual development. However, the GO categories of unfused cells were dominated by metabolic pathways and other processes indicative of a vegetative phase. Our study provides strong evidence that the fused cells represent a sexual stage in Cochliopodium. Our findings have further implications in understanding the evolution and mechanism of inheritance involving multiparents in other eukaryotes with a similar reproductive strategy.


Assuntos
Amoeba/fisiologia , Perfilação da Expressão Gênica/métodos , Reprodução Assexuada/fisiologia , Amoeba/genética , Regulação da Expressão Gênica , Fusão Nuclear , Análise de Sequência de RNA , Análise de Célula Única
10.
Protist ; 171(6): 125773, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33243724

RESUMO

The marine protozoan parasite Neoparamoeba perurans has been established as the causative agent for amoebic gill disease (AGD) in Atlantic salmon (Salmo salar). Freshwater bathing is the only routinely used treatment for AGD in Australia while hydrogen peroxide (H2O2) is used in countries with cooler water temperatures. The identification of new treatments that do not rely on either freshwater or H2O2 bathing is highly sought. However, in vitro based methods for high throughput screening of antiparasitic compounds have not been established for this parasite. To this end the present study evaluated two in vitro bioassays based on metabolic energy production and cellular membrane integrity to distinguish between amoebistatic (crenated or pseudocyst forms with recovery possible) and amoebicidal (death) activity. Amoebae were subject to either freshwater, H2O2 or chloramine-T for 4h treatment and assessed 24h after recovery. Visualization by microscopy and bioassay assessment 24h post-treatment confirmed that H2O2 and freshwater are 95% amoebicidal albeit due to different mechanisms of action. These data are consistent with other studies where amoebae have been observed to recover following exposure to these compounds and provide evidence for the inclusion of a recovery component to differentiate between the mechanism of action of amoebicidal and amoebistatic treatments. Together these bioassays are a critical tool for high throughput screening of novel and more effective treatments against AGD.


Assuntos
Amebíase/parasitologia , Amoeba/fisiologia , Bioensaio/normas , Doenças dos Peixes/parasitologia , Ensaios de Triagem em Larga Escala/métodos , Amoeba/citologia , Animais , Organismos Aquáticos , Pesqueiros , Ensaios de Triagem em Larga Escala/normas , Viabilidade Microbiana
11.
Explore (NY) ; 16(4): 250-256, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32475792

RESUMO

Background From intelligent behaviors of individual molecules and primitive organisms to those with a nervous system and brain, nature displays a fascinating collective memory across time and space. Using certain electronic circuits called memristors, it has been possible to emulate several processes of memory and learning, including a predictive form of intelligence of simple amoebas. Purpose What is the core of such intelligent performances? Although memristors are able to effectively describe puzzling biologic behaviors, recent results challenge their very existence altogether. This paper asks what can be gleaned from the underlying controversy itself, which will be argued is analogous to the observer principle in quantum physics. It is hypothesized that the material phenomena of resonance and sync have a counterpart involving behavior and memory. This questions the prominent role of a causative agent, and which type of behavior or memory is being occasioned. Results Building on the theory of memristors, the challenge of their actualization, and puzzling behaviors of amoebas, this paper proposes that 'resonating actions' - that is, similar or interlinked behaviors beyond space and time - are enabled by an underlying field of potentiation or domain of influence, and not by a cause-effect relationship. Such linked behaviors resemble a form of 'action coherence.' Habituated actions, memory, and behavior may arise out of a similar field of consciousness (here, modeled as memristors). These principles may be at the core of many hitherto unexplained mysteries of collective learning and behavior beyond space and time. Although this study is based on amoebas, the key postulates are also of great relevance to human thinking, behavior, and performance (including the representation of illness), and have independently been confirmed in the fields of consciousness research and spirituality.


Assuntos
Amoeba/fisiologia , Cognição , Memória , Eletrônica/instrumentação , Mixomicetos/fisiologia
12.
mBio ; 11(3)2020 05 26.
Artigo em Inglês | MEDLINE | ID: mdl-32457245

RESUMO

The human-pathogenic fungus Aspergillus fumigatus is a ubiquitous saprophyte that causes fatal lung infections in immunocompromised individuals. Following inhalation, conidia are ingested by innate immune cells and can arrest phagolysosome maturation. How this virulence trait could have been selected for in natural environments is unknown. Here, we found that surface exposure of the green pigment 1,8-dihydroxynaphthalene-(DHN)-melanin can protect conidia from phagocytic uptake and intracellular killing by the fungivorous amoeba Protostelium aurantium and delays its exocytosis from the nonfungivorous species Dictyostelium discoideum To elucidate the antiphagocytic properties of the surface pigment, we followed the antagonistic interactions of A. fumigatus conidia with the amoebae in real time. For both amoebae, conidia covered with DHN-melanin were internalized at far lower rates than were seen with conidia lacking the pigment, despite high rates of initial attachment to nonkilling D. discoideum When ingested by D. discoideum, the formation of nascent phagosomes was followed by transient acidification of phagolysosomes, their subsequent neutralization, and, finally, exocytosis of the conidia. While the cycle was completed in less than 1 h for unpigmented conidia, the process was significantly prolonged for conidia covered with DHN-melanin, leading to an extended intracellular residence time. At later stages of this cellular infection, pigmented conidia induced enhanced damage to phagolysosomes and infected amoebae failed to recruit the ESCRT (endosomal sorting complex required for transport) membrane repair machinery or the canonical autophagy pathway to defend against the pathogen, thus promoting prolonged intracellular persistence in the host cell and the establishment of a germination niche in this environmental phagocyte.IMPORTANCE Infections with Aspergillus fumigatus are usually acquired by an inhalation of spores from environmental sources. How spores of a saprophytic fungus have acquired abilities to withstand and escape the phagocytic attacks of innate immune cells is not understood. The fungal surface pigment dihydroxynaphtalene-melanin has been shown to be a crucial factor for the delay in phagosome maturation. Here, we show that this pigment also has a protective function against environmental phagocytes. Pigmented conidia escaped uptake and killing by the fungus-eating amoeba Protostelium aurantium When ingested by the nonfungivorous phagocyte Dictyostelium discoideum, the pigment attenuated the launch of cell autonomous defenses against the fungal invader, such as membrane repair and autophagy, leading to prolonged intracellular retention. Membrane damage and cytoplasmic leakage may result in an influx of nutrients and thus may further promote intracellular germination of the fungus, indicating that A. fumigatus has acquired some of the basic properties of intracellular pathogens.


Assuntos
Amoeba/microbiologia , Amoeba/fisiologia , Aspergillus fumigatus/química , Melaninas/química , Esporos Fúngicos/química , Antibiose , Aspergillus fumigatus/patogenicidade , Simulação por Computador , Dictyostelium/microbiologia , Dictyostelium/fisiologia , Complexos Endossomais de Distribuição Requeridos para Transporte , Naftóis/química , Fagocitose , Fagossomos , Virulência
13.
Eur J Protistol ; 73: 125674, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32200296

RESUMO

Sphagnum peatlands host a high abundance of protists, especially testate amoebae. Here, we designed a study to investigate the functional diversity of testate amoebae in relation to wetness and forest cover in Baltic bogs. We provided new data on the influence of openness/wetness gradient on testate amoebae communities, showing significant differences in selected testate amoebae (TA) traits. Three key messages emerged from our investigations: 1) we recorded an effect of peatland surface openness on testate amoebae functional traits that led us to accept the hypothesis that TA traits differ according to light intensity and hydrology. Mixotrophic species were recorded in high relative abundance in open plots, whereas they were nearly absent in forested sites; 2) we revealed a hydrological threshold for the occurrence of mixotrophic testate amoebae that might be very important in terms of peatland functioning and carbon sink vs. source context; and 3) mixotrophic species with organic tests were nearly absent in forested sites that were dominated by heterotrophic species with agglutinated or idiosomic tests. An important message from this study is that taxonomy of TA rather indicates the hydrological gradient whereas traits of mixotrophs the openness gradient.


Assuntos
Amoeba/classificação , Amoeba/fisiologia , Ecossistema , Países Bálticos , Biodiversidade , Demografia , Florestas , Hidrologia , Luz Solar
14.
Mikrobiyol Bul ; 54(1): 50-65, 2020 Jan.
Artigo em Turco | MEDLINE | ID: mdl-32050878

RESUMO

Legionella bacteria living in free form or in biofilm and free-living amoebae (FLA) can infect humans through swimming pools and can cause various diseases. FLA may also threaten the health of swimmers because they are capable of being hosts for Legionella and some other bacteria. The aim of this study was to investigate the presence of total aerobic heterotrophic bacteria (TAHB), FLA and Legionella bacteria in swimming pool waters and biofilm samples in Istanbul by using culture and FISH methods. Water plate count agar (wPCA), buffered charcoal yeast extract (BCYE) agar supplemented with glycinevancomycin-polymyxin-cycloheximide (GVPC) and Escherichia coli cultivated non-nutrient agar (NNA) were used for the culture of TAHB, Legionella and FLA. For the FISH method analysis , Leg 705 and Leg PNE1 probes labeled with fluorescent dye for Legionella and ACANTHA probe for Acanthamoeba genus FLA were used. Legionella pneumophila serogroup 1 ATCC 33152, L.pneumophila serogroup 3 ATCC 33155 and Acanthamoeba castellani ATCC 50373 were used as positive controls. TAHB were grown in 92% and 84% of water and biofilm samples. Although Legionella bacteria could not be grown in any of the water samples, it was detected in 6 (24%) water samples by FISH method. Although these bacteria could be grown in 1 (4%) of biofilm samples, 7 (28%) were detected by FISH method. FLA were found to be 16% by culture in water samples and 28% by FISH analysis. These amoebae were detected 8% and 20% in biofilm samples by culture and FISH method, respectively. It was determined that one of the isolates of FLA had thermotolerant activity (potentially pathogenic). L.pneumophila serogroup 1 was detected in one water sample and in four biofilm samples. According to the culture method, TAHB and FLA were found to be more common in water samples than in biofilm samples and Legionella bacteria were more common in biofilm samples than in water samples (p≤ 0.05). In the detection of Legionella bacteria, the superiority of FISH method compared to culture method was found to be statistically significant (p≤ 0.05). In this study, it was found that the number of TAHB in the controlled swimming pools was within the limits determined by the Ministry of Health (≤ 200 cfu/ml). It will be appropriate to examine both water and biofilm samples for the investigation of TAHB, FLA and Legionella. It may be appropriate to use both culture and FISH methods to detect the presence of FLA in water and biofilm samples. This study is the first study to investigate the presence of Legionella and FLA in swimming pools in Istanbul, and further studies are needed to examine more pool water and biofilm samples. With the data obtained, the health principles and controls of swimming pools will be re-considered and will be contributed to public health.


Assuntos
Amoeba , Biofilmes , Monitoramento Ambiental , Legionella , Piscinas , Microbiologia da Água , Água , Amoeba/fisiologia , Monitoramento Ambiental/métodos , Incidência , Legionella/fisiologia , Turquia , Água/parasitologia
15.
Environ Microbiol ; 22(10): 4183-4197, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-31386262

RESUMO

Vibrios are ubiquitous in marine environments and opportunistically colonize a broad range of hosts. Strains of Vibrio tasmaniensis present in oyster farms can thrive in oysters during juvenile mortality events and behave as facultative intracellular pathogen of oyster haemocytes. Herein, we wondered whether V. tasmaniensis LGP32 resistance to phagocytosis is specific to oyster immune cells or contributes to resistance to other phagocytes, like marine amoebae. To address this question, we developed an integrative study, from the first description of amoeba diversity in oyster farms to the characterization of LGP32 interactions with amoebae. An isolate of the Vannella genus, Vannella sp. AP1411, which was collected from oyster farms, is ubiquitous, and belongs to one clade of Vannella that could be found associated with Vibrionaceae. LGP32 was shown to be resistant to grazing by Vannella sp. AP1411 and this phenotype depends on some previously identified virulence factors: secreted metalloprotease Vsm and copper efflux p-ATPase CopA, which act at different steps during amoeba-vibrio interactions, whereas some other virulence factors were not involved. Altogether, our work indicates that some virulence factors can be involved in multi-host interactions of V. tasmaniensis ranging from protozoans to metazoans, potentially favouring their opportunistic behaviour.


Assuntos
Amebozoários/fisiologia , Ostreidae/microbiologia , Vibrio/fisiologia , Amoeba/fisiologia , Animais , Proteínas de Bactérias/genética , Comportamento Predatório , Vibrio/genética , Vibrio/patogenicidade , Fatores de Virulência/genética
16.
J Eukaryot Microbiol ; 67(2): 203-208, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31691412

RESUMO

Amoeba proteus is possibly the best known of all unicellular eukaryotes. At the same time, several quintessential issues of its biology, including some aspects of the cell cycle, remain unsolved. Here, we show that this obligate agamic amoebae and related species have a special type of cyclic polyploidy. Their nucleus has an euploid status only for a small fraction of the cell cycle, during metaphase and telophase. The rest of the time it has an aneuploid status, which is a consequence of polyploidization. Extrusion of "excess" chromatin from the nucleus in late interphase and during prophase results in depolyploidization. Such a strategy of life cycle in unicellular eukaryotes is thought to be the main mechanism of "resetting" the Muller's ratchet and is a satisfactory alternative to the meiotic recombination for agamic protists.


Assuntos
Amoeba/fisiologia , Aneuploidia , Ciclo Celular , Cromatina/fisiologia , Poliploidia , Amoeba/genética
17.
Virol J ; 16(1): 126, 2019 11 04.
Artigo em Inglês | MEDLINE | ID: mdl-31684962

RESUMO

Since the discovery of mimivirus, numerous giant viruses associated with free-living amoebae have been described. The genome of giant viruses can be more than 2.5 megabases, and virus particles can exceed the size of many bacteria. The unexpected characteristics of these viruses have made them intriguing research targets and, as a result, studies focusing on their interactions with their amoeba host have gained increased attention. Studies have shown that giant viruses can establish host-pathogen interactions, which have not been previously demonstrated, including the unprecedented interaction with a new group of small viruses, called virophages, that parasitize their viral factories. In this brief review, we present recent advances in virophage-giant virus-host interactions and highlight selected studies involving interactions between giant viruses and amoebae. These unprecedented interactions involve the giant viruses mimivirus, marseillevirus, tupanviruses and faustovirus, all of which modulate the amoeba environment, affecting both their replication and their spread to new hosts.


Assuntos
Amoeba/virologia , Vírus Gigantes/fisiologia , Interações Hospedeiro-Patógeno , Amoeba/fisiologia , Vesículas Extracelulares/metabolismo , Vesículas Extracelulares/virologia , Genoma Viral , Especificidade de Hospedeiro , Mimiviridae/fisiologia , Modelos Biológicos , Virófagos/fisiologia , Replicação Viral
18.
Sci Rep ; 9(1): 16369, 2019 11 08.
Artigo em Inglês | MEDLINE | ID: mdl-31704992

RESUMO

For a wide range of cells, from bacteria to mammals, locomotion movements are a crucial systemic behavior for cellular life. Despite its importance in a plethora of fundamental physiological processes and human pathologies, how unicellular organisms efficiently regulate their locomotion system is an unresolved question. Here, to understand the dynamic characteristics of the locomotion movements and to quantitatively study the role of the nucleus in the migration of Amoeba proteus we have analyzed the movement trajectories of enucleated and non-enucleated amoebas on flat two-dimensional (2D) surfaces using advanced non-linear physical-mathematical tools and computational methods. Our analysis shows that both non-enucleated and enucleated amoebas display the same kind of dynamic migration structure characterized by highly organized data sequences, super-diffusion, non-trivial long-range positive correlations, persistent dynamics with trend-reinforcing behavior, and move-step fluctuations with scale invariant properties. Our results suggest that the presence of the nucleus does not significantly affect the locomotion of amoeba in 2D environments.


Assuntos
Amoeba/fisiologia , Núcleo Celular/fisiologia , Modelos Biológicos , Análise dos Mínimos Quadrados , Microscopia de Vídeo , Movimento/fisiologia , Dinâmica não Linear
19.
PLoS Negl Trop Dis ; 13(10): e0007742, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31589617

RESUMO

Paracoccidioides spp. are thermodimorphic fungi that cause a neglected tropical disease (paracoccidioidomycosis) that is endemic to Latin America. These fungi inhabit the soil, where they live as saprophytes with no need for a mammalian host to complete their life cycle. Despite this, they developed sophisticated virulence attributes allowing them not only to survive in host tissues but also to cause disease. A hypothesis for selective pressures driving the emergence or maintenance of virulence of soil fungi is their interaction with soil predators such as amoebae and helminths. We evaluated the presence of environmental amoeboid predators in soil from armadillo burrows where Paracoccidioides had been previously detected and tested if the interaction of Paracoccidioides with amoebae selects for fungi with increased virulence. Nematodes, ciliates, and amoebae-all potential predators of fungi-grew in cultures from soil samples. Microscopical observation and ITS sequencing identified the amoebae as Acanthamoeba spp, Allovahlkampfia spelaea, and Vermamoeba vermiformis. These three amoebae efficiently ingested, killed and digested Paracoccidioides spp. yeast cells, as did laboratory adapted axenic Acanthamoeba castellanii. Sequential co-cultivation of Paracoccidioides with A. castellanii selected for phenotypical traits related to the survival of the fungus within a natural predator as well as in murine macrophages and in vivo (Galleria mellonella and mice). These changes in virulence were linked to the accumulation of cell wall alpha-glucans, polysaccharides that mask recognition of fungal molecular patterns by host pattern recognition receptors. Altogether, our results indicate that Paracoccidioides inhabits a complex environment with multiple amoeboid predators that can exert selective pressure to guide the evolution of virulence traits.


Assuntos
Amoeba/fisiologia , Interações Hospedeiro-Patógeno/fisiologia , Paracoccidioides/fisiologia , Microbiologia do Solo , Acanthamoeba castellanii/fisiologia , Amoeba/citologia , Amoeba/microbiologia , Animais , Tatus , Cilióforos , Técnicas de Cocultura , Modelos Animais de Doenças , Fungos , Macrófagos/microbiologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Nematoides , Paracoccidioides/patogenicidade , Paracoccidioidomicose/microbiologia , Fagocitose , Solo , Virulência , Fatores de Virulência/fisiologia
20.
Nat Commun ; 10(1): 3690, 2019 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-31417086

RESUMO

Associative memory is the main type of learning by which complex organisms endowed with evolved nervous systems respond efficiently to certain environmental stimuli. It has been found in different multicellular species, from cephalopods to humans, but never in individual cells. Here we describe a motility pattern consistent with associative conditioned behavior in the microorganism Amoeba proteus. We use a controlled direct-current electric field as the conditioned stimulus, and a specific chemotactic peptide as the unconditioned stimulus. The amoebae are capable of linking two independent past events, generating persistent locomotion movements that can prevail for 44 min on average. We confirm a similar behavior in a related species, Metamoeba leningradensis. Thus, our results indicate that unicellular organisms can modify their behavior during migration by associative conditioning.


Assuntos
Amoeba/fisiologia , Aprendizagem por Associação/fisiologia , Condicionamento Clássico/fisiologia , Locomoção/fisiologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...