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MSphere Aug 2021Out of over 40 species of , which are free-living thermophilic amebae found in freshwater and soil worldwide, only Naegleria fowleri infects humans, causing primary... (Comparative Study)
Comparative Study
Out of over 40 species of , which are free-living thermophilic amebae found in freshwater and soil worldwide, only Naegleria fowleri infects humans, causing primary amebic meningoencephalitis (PAM), a typically fatal brain disease. To understand the population structure of species and the genetic relationships between N. fowleri isolates and to detect pathogenic factors, we characterized 52 novel clinical and environmental N. fowleri genomes and a single Naegleria lovaniensis strain, along with transcriptomic data for a subset of 37 N. fowleri isolates. Whole-genome analysis of 56 isolates from three species (N. fowleri, , and Naegleria gruberi) identified several genes unique to N. fowleri that have previously been linked to the pathogenicity of N. fowleri, while other unique genes could be associated with novel pathogenicity factors in this highly fatal pathogen. Population structure analysis estimated the presence of 10 populations within the three species, of which 7 populations were within N. fowleri. The whole-nuclear-genome (WNG) phylogenetic analysis showed an overall geographical clustering of N. fowleri isolates, with few exceptions, and provided higher resolution in identifying potential clusters of isolates beyond that of the traditional locus typing. There were only 34 genes that showed significant differences in gene expression between the clinical and environmental isolates. Genomic data generated in this study can be used for developing rapid molecular assays and to conduct future population-based global genomic analysis and will also be a valuable addition to genomic reference databases, where shotgun metagenomics data from routine water samples could be searched for the presence of N. fowleri strains. N. fowleri, the only known species to infect humans, causes fatal brain disease. PAM cases from 1965 to 2016 showed <20 cases per year globally. Out of approximately 150 cases in North America since 1962, only four PAM survivors are known, yielding a >97% case fatality rate, which is critically high. Although the pathogenesis of N. fowleri has been studied for the last 50 years, pathogenetic factors that lead to human infection and breaching the blood-brain barrier remain unknown. In addition, little is known regarding the genomic diversity both within N. fowleri isolates and among species. In this study, we generated novel genome sequences and performed comparative genomic and transcriptomic analysis of a set of 52 N. fowleri draft genome sequences from clinical and environmental isolates derived from all over the world in the last 53 years, which will help shape future genome-wide studies and develop sensitive assays for routine surveillance.
Topics: Central Nervous System Protozoal Infections; Environmental Microbiology; Gene Expression Profiling; Genome, Protozoan; Genomics; Humans; Naegleria fowleri; Phylogeny; Transcriptome; Water
PubMed: 34378985
DOI: 10.1128/mSphere.00637-21 -
Nature Communications Jul 2022Encystment is a common stress response of most protists, including free-living amoebae. Cyst formation protects the amoebae from eradication and can increase virulence...
Encystment is a common stress response of most protists, including free-living amoebae. Cyst formation protects the amoebae from eradication and can increase virulence of the bacteria they harbor. Here, we mapped the global molecular changes that occur in the facultatively pathogenic amoeba Acanthamoeba castellanii during the early steps of the poorly understood process of encystment. By performing transcriptomic, proteomic, and phosphoproteomic experiments during encystment, we identified more than 150,000 previously undescribed transcripts and thousands of protein sequences absent from the reference genome. These results provide molecular details to the regulation of expected biological processes, such as cell proliferation shutdown, and reveal new insights such as a rapid phospho-regulation of sites involved in cytoskeleton remodeling and translation regulation. This work constitutes the first time-resolved molecular atlas of an encysting organism and a useful resource for further investigation of amoebae encystment to allow for a better control of pathogenic amoebae.
Topics: Acanthamoeba castellanii; Amoeba; Bacteria; Proteomics; Virulence
PubMed: 35835784
DOI: 10.1038/s41467-022-31832-0 -
Animal Cognition Nov 2023Sensing, communication, navigation, decision-making, memory and learning are key components in a standard cognitive tool-kit that enhance an animal's ability to... (Review)
Review
Sensing, communication, navigation, decision-making, memory and learning are key components in a standard cognitive tool-kit that enhance an animal's ability to successfully survive and reproduce. However, these tools are not only useful for, or accessible to, animals-they evolved long ago in simpler organisms using mechanisms which may be either unique or widely conserved across diverse taxa. In this article, I review the recent research that demonstrates these key cognitive abilities in the plasmodial slime mould Physarum polycephalum, which has emerged as a model for non-animal cognition. I discuss the benefits and limitations of comparisons drawn between neural and non-neural systems, and the implications of common mechanisms across wide taxonomic divisions. I conclude by discussing future avenues of research that will draw the most benefit from a closer integration of Physarum and animal cognition research.
Topics: Animals; Physarum polycephalum; Cognition; Learning
PubMed: 37166523
DOI: 10.1007/s10071-023-01782-1 -
Infectious Disorders Drug Targets 2020Encephalitis caused by Free-living amoebae (FLA) has a mortality rate of around 95- 98%, a fraction that has not changed in the past decades. Pathogenic FLA include... (Review)
Review
Encephalitis caused by Free-living amoebae (FLA) has a mortality rate of around 95- 98%, a fraction that has not changed in the past decades. Pathogenic FLA include Acanthamoeba, Balamuthia mandrillaris, and Naegleria fowleri that are known to target the brain after an extra cerebral infection in the case of Acanthamoeba and Balamuthia mandrillaris, or directly the brain, as in the case of the Naegleria fowleri. The Acanthamoeba spp. and Balamuthia mandrillaris cause granulomatous amoebic encephalitis (GAE) while Naegleria fowleri, the so termed "brain eating amoeba" causes primary amoebic meningoencephalitis (PAM). The attempts to obtain a speedy diagnosis and an aggressive treatment protocol are the areas where advances can make a difference and reduce the mortality rates. At first, we highlight the reasons behind the diagnostic delays and treatment failures and provide proposals to establish a quick diagnosis in both PAM and GAE. Secondly, we emphasize the use of a transcribrial device, and a prompt, but vigilant surgical reduction of the intracranial pressure in these patients which could be life-saving. We also debate that an exudate obtained from the olfactory region by irrigation via a modified transcribrial device or by conventional methods, instead of a cerebrospinal fluid sample, could serve as a source of obtaining amoeba in PAM for a real-time polymerase chain reaction-based definitive diagnosis of PAM. Also, introduced is the rationale that has the potential to deliver the drugs to the brain in patients with PAM and the GAE localized to the frontal lobe of the brain, by bypassing the blood brain barrier. We put forward these proposals for debate and deliberation to our fellow colleagues in order to spot the potential of their application to reduce the mortality rates caused by the rare but fatal encephalitis caused by these FLA.
Topics: Acanthamoeba; Amebiasis; Antiprotozoal Agents; Balamuthia mandrillaris; Brain; Central Nervous System Protozoal Infections; Encephalitis; Humans; Naegleria fowleri
PubMed: 30961516
DOI: 10.2174/1871526519666190405170601 -
International Journal of Hygiene and... Sep 2022One Health approaches are becoming increasingly necessary in the world we live in. Human beings, animals, plants and the environment are intrinsically interconnected and... (Review)
Review
One Health approaches are becoming increasingly necessary in the world we live in. Human beings, animals, plants and the environment are intrinsically interconnected and when some intervention occurs, mainly through the action of man himself, everyone suffers the consequences. The objective of this review was to collect data about the occurrence and dispersion of Naegleria fowleri, an amphizoic free-living amoeba, and its implications for health approaches through the One Health concept. N. fowleri is an opportunistic amoeba, better known as brain-eating amoeba, which causes Primary Amoebic Meningoencephalitis. This amoeba is widely distributed around the world, being isolated from different matrices of natural or anthropogenic environments with temperatures above 30 °C with an upper limit of 45-46 °C. Highly lethal, it has claimed numerous humans patients and only five people have survived the disease so far. Our results indicate that climate change plays a major role in the growth and dispersion of the pathogen in the environment, causing damage to humans and animals. Changes in temperature, antimicrobial resistance, possible transport of other microorganisms by the amoeba, conventional treatments with chlorination, among others, were addressed in our study and should be considered in order to raise questions and possible solutions to this problem that involves health as a whole. The diagnostic methods, prospection of new anti-Naegleria drugs and the control of this parasite in the environment are specific and urgent issues. We know that the human-animal-plants-environment spheres are inseparable, so it is necessary to turn a directed look at the One Health approaches related to N. fowleri.
Topics: Animals; Humans; Naegleria fowleri; One Health; Amebiasis; Amoeba; Temperature
PubMed: 36308781
DOI: 10.1016/j.ijheh.2022.114053 -
Methods in Molecular Biology (Clifton,... 2022Physarum polycephalum is a protist slime mould that exhibits a high degree of responsiveness to its environment through a complex network of tubes and cytoskeletal...
Physarum polycephalum is a protist slime mould that exhibits a high degree of responsiveness to its environment through a complex network of tubes and cytoskeletal components that coordinate behavior across its unicellular, multinucleated body. Physarum has been used to study decision making, problem solving, and mechanosensation in aneural biological systems. The robust generative and repair capacities of Physarum also enable the study of whole-body regeneration within a relatively simple model system. Here we describe methods for growing, imaging, quantifying, and sampling Physarum that are adapted for investigating regeneration and repair.
Topics: Adaptation, Physiological; Models, Biological; Physarum polycephalum
PubMed: 35359302
DOI: 10.1007/978-1-0716-2172-1_3 -
ACS Biomaterials Science & Engineering Feb 2020In many situations, cells migrate through tiny orifices. Examples include the extravasation of immune cells from the bloodstream for fighting infections, the...
In many situations, cells migrate through tiny orifices. Examples include the extravasation of immune cells from the bloodstream for fighting infections, the infiltration of cancer cells during metastasis, and the migration of human pathogens. An extremely motile and medically relevant type of human pathogen is . In the study presented here, we investigated how a combination of microparticles and microstructured interfaces controls the migration of trophozoites. The microinterfaces comprised well-defined micropillar arrays, and the trophozoites easily migrated through the given constrictions by adapting the shape and size of their intracellular vacuoles and by adapting intracellular motion. After feeding the trophozoite cells in microinterfaces with synthetic, stiff microparticles of various sizes and shapes, their behavior changed drastically: if the particles were smaller than the micropillar gap, migration was still possible. If the cells incorporated particles larger than the pillar gap, they could become immobilized but could also display remarkable problem-solving capabilities. For example, they turned rod-shaped microparticles such that their short axis fit through the pillar gap or they transported the particles above the structure. As migration is a crucial contribution to pathogenicity and is also relevant to other biological processes in microenvironments, such as cancer metastasis, our results provide an interesting strategy for controlling the migration of cells containing intracellular particles by microstructured interfaces that serve as migration-limiting environments.
Topics: Acanthamoeba castellanii; Amoeba; Animals; Humans; Trophozoites
PubMed: 32215319
DOI: 10.1021/acsbiomaterials.9b00496 -
Current Protocols May 2022This article describes a practical method for prospecting and isolating giant viruses based on direct inoculation of environmental samples into amoeba cultures of...
This article describes a practical method for prospecting and isolating giant viruses based on direct inoculation of environmental samples into amoeba cultures of Acanthamoeba castellanii. The giant viruses that infect amoebas have already been isolated from various environmental samples in several countries worldwide, including in extreme environments. Here we describe the methodologic procedures regarding the prospecting of giant viruses in A. castellanii, including the preparation of environmental samples, the culture of amoebas, and the observation of cytopathic effects that can indicate the presence and potential isolation of giant viruses. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Sample collection Support Protocol: Propagation of Acanthamoeba castellanii Basic Protocol 2: Prospecting of giant viruses in environmental samples by cytopathic effect analysis.
Topics: Acanthamoeba castellanii; Amoeba; Giant Viruses
PubMed: 35612516
DOI: 10.1002/cpz1.455 -
Molecular Microbiology Jan 2023Mammalian professional phagocytic cells ingest and kill invading microorganisms and prevent the development of bacterial infections. Our understanding of the sequence of...
Mammalian professional phagocytic cells ingest and kill invading microorganisms and prevent the development of bacterial infections. Our understanding of the sequence of events that results in bacterial killing and permeabilization in phagosomes is still largely incomplete. In this study, we used the Dictyostelium discoideum amoeba as a model phagocyte to study the fate of the bacteria Klebsiella pneumoniae inside phagosomes. Our analysis distinguishes three consecutive phases: bacteria first lose their ability to divide (killing), then their cytosolic content is altered (permeabilization), and finally their DNA is degraded (digestion). Phagosomal acidification and production of free radicals are necessary for rapid killing, membrane-permeabilizing proteins BpiC and AlyL are required for efficient permeabilization. These results illustrate how a combination of genetic and microscopical tools can be used to finely dissect the molecular events leading to bacterial killing and permeabilization in a maturing phagosome.
Topics: Animals; Dictyostelium; Phagosomes; Klebsiella pneumoniae; Membrane Proteins; Bacteria; Mammals
PubMed: 36416195
DOI: 10.1111/mmi.15004 -
Therapeutic Delivery Mar 2023Tweetable abstract Nebulized emanator for intranasal delivery of antiamebic drugs to the brain.
Tweetable abstract Nebulized emanator for intranasal delivery of antiamebic drugs to the brain.
Topics: Amoeba; Brain; Naegleria fowleri; Administration, Intranasal
PubMed: 37191013
DOI: 10.4155/tde-2023-0015