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Journal of Clinical Microbiology Jan 2022Infections caused by Naegleria fowleri, Acanthamoeba spp., and Balamuthia mandrillaris result in a variety of clinical manifestations in humans. These amoebae are found...
Infections caused by Naegleria fowleri, Acanthamoeba spp., and Balamuthia mandrillaris result in a variety of clinical manifestations in humans. These amoebae are found in water and soil worldwide. spp. and B. mandrillaris cause granulomatous amoebic encephalitis (GAE), which usually presents as a mass, while N. fowleri causes primary amoebic meningoencephalitis (PAM). spp. can also cause keratitis, and both spp. and can cause lesions in skin and respiratory mucosa. These amoebae can be difficult to diagnose clinically as these infections are rare and, if not suspected, can be misdiagnosed with other more common diseases. Microscopy continues to be the key first step in diagnosis, but the amoeba can be confused with macrophages or other infectious agents if an expert in infectious disease pathology or clinical microbiology is not consulted. Although molecular methods can be helpful in establishing the diagnosis, these are only available in referral centers. Treatment requires combination of antibiotics and antifungals and, even with prompt diagnosis and treatment, the mortality for neurological disease is extremely high.
Topics: Acanthamoeba; Amebiasis; Amoeba; Balamuthia mandrillaris; Humans; Naegleria fowleri
PubMed: 34133896
DOI: 10.1128/JCM.00228-21 -
Nucleic Acids Research Apr 2024MicroRNAs (miRNAs) are important and ubiquitous regulators of gene expression in both plants and animals. They are thought to have evolved convergently in these lineages...
MicroRNAs (miRNAs) are important and ubiquitous regulators of gene expression in both plants and animals. They are thought to have evolved convergently in these lineages and hypothesized to have played a role in the evolution of multicellularity. In line with this hypothesis, miRNAs have so far only been described in few unicellular eukaryotes. Here, we investigate the presence and evolution of miRNAs in Amoebozoa, focusing on species belonging to Acanthamoeba, Physarum and dictyostelid taxonomic groups, representing a range of unicellular and multicellular lifestyles. miRNAs that adhere to both the stringent plant and animal miRNA criteria were identified in all examined amoebae, expanding the total number of protists harbouring miRNAs from 7 to 15. We found conserved miRNAs between closely related species, but the majority of species feature only unique miRNAs. This shows rapid gain and/or loss of miRNAs in Amoebozoa, further illustrated by a detailed comparison between two evolutionary closely related dictyostelids. Additionally, loss of miRNAs in the Dictyostelium discoideum drnB mutant did not seem to affect multicellular development and, hence, demonstrates that the presence of miRNAs does not appear to be a strict requirement for the transition from uni- to multicellular life.
Topics: Amoebozoa; Dictyostelium; MicroRNAs; Phylogeny; Evolution, Molecular; RNA, Protozoan; Conserved Sequence; RNA Interference
PubMed: 38375870
DOI: 10.1093/nar/gkae109 -
Annals of Agricultural and... Sep 2018is a unicellular, anaerobic protist which lives in the intestinal tract of diverse animals, including humans. It was found that the host specificity and the pathogenic... (Review)
Review
is a unicellular, anaerobic protist which lives in the intestinal tract of diverse animals, including humans. It was found that the host specificity and the pathogenic potential of different isolates are correlated with sequence variations in the SSU-rRNA gene. Identification of the organism to the species level is still an unresolved challenge. Genetic diversity revisions have led to the identification of 17 subtypes (STs) within the genus, and 9 (ST1 to ST9) have been reported in humans with varying prevalence. Since the members of the genus revealed a large genetic diversity, several molecular modalities of subtyping methods have been developed. Numerous studies on conveying the pathogenic potential to the molecular subtypes are available, but they could not be compared or analysed with the different molecular techniques employed. The use of different approaches may give false positives during diagnosis and the possibility of missed infections. A review of recent scientific literature indicates that the development of PCR assays is needed for molecular epidemiology and for mixed infections in health and disease cohorts, and also to help identify sources of transmission to humans, as well as to identify potential animal and environmental reservoirs. This review summarizes some of the recent progress and improvements in research on genetic diversity, taxonomy, molecular epidemiology, pathogenicity and subtyping methods.
Topics: Animals; Blastocystis; Blastocystis Infections; Genetic Variation; Humans; Virulence
PubMed: 30260199
DOI: 10.26444/aaem/81315 -
Annual Review of Genetics Nov 2016Comparisons among a variety of eukaryotes have revealed considerable variability in the structures and processes involved in their meiosis. Nevertheless, conventional... (Review)
Review
Comparisons among a variety of eukaryotes have revealed considerable variability in the structures and processes involved in their meiosis. Nevertheless, conventional forms of meiosis occur in all major groups of eukaryotes, including early-branching protists. This finding confirms that meiosis originated in the common ancestor of all eukaryotes and suggests that primordial meiosis may have had many characteristics in common with conventional extant meiosis. However, it is possible that the synaptonemal complex and the delicate crossover control related to its presence were later acquisitions. Later still, modifications to meiotic processes occurred within different groups of eukaryotes. Better knowledge on the spectrum of derived and uncommon forms of meiosis will improve our understanding of many still mysterious aspects of the meiotic process and help to explain the evolutionary basis of functional adaptations to the meiotic program.
Topics: Alveolata; Amoebozoa; Animals; Chromosome Pairing; Eukaryota; Fungi; Meiosis; Prophase; Recombination, Genetic; Stramenopiles; Synaptonemal Complex
PubMed: 27686280
DOI: 10.1146/annurev-genet-120215-035100 -
Indian Journal of Medical Microbiology 2022Free-living amoebae (FLA) exist in various environmental sources and are the causative agents of many serious human diseases. We surveyed various natural and artificial...
PURPOSE
Free-living amoebae (FLA) exist in various environmental sources and are the causative agents of many serious human diseases. We surveyed various natural and artificial water bodies in areas of north India to detect the presence of FLA species.
MATERIALS AND METHODS
Surface water samples were collected from 29 water bodies and subjected to microscopy, non-nutrient agar (NNA) culture, and various polymerase chain reaction (PCR) assays for the detection of FLA.
RESULTS
FLA were found in 62.1% (18/29) of the natural and artificial water bodies by NNA culture. Based on PCR based detection, Acanthamoeba spp. was identified in 41.4% (12/29), Vannella spp./Vahlkampfia ovis in 17.2% (5/29) and Naegleria spp. in 20.7% (6/29) of the samples from different locations. PCR-sequencing of Naegleria positive samples identified them as Naegleria australiensis and Naegleria species.
CONCLUSIONS
The present study reports widespread occurrence of medically important FLA species in various natural and artificial water bodies, and highlights the need for regular molecular surveillance of FLA in the environment for better control and prevention of the diseases caused by FLA.
Topics: Acanthamoeba; Amoeba; Animals; Humans; Naegleria; Polymerase Chain Reaction; Sheep; Water
PubMed: 35660264
DOI: 10.1016/j.ijmmb.2022.05.002 -
Trends in Parasitology Mar 2022Naegleria fowleri, Balamuthia mandrillaris, and Acanthamoeba spp. can cause devastating brain infections in humans which almost always result in death. The symptoms of... (Review)
Review
Naegleria fowleri, Balamuthia mandrillaris, and Acanthamoeba spp. can cause devastating brain infections in humans which almost always result in death. The symptoms of the three infections overlap, but brain inflammation and the course of the disease differ, depending on the amoeba that is responsible. Understanding the differences between these amoebae can result in the development of strategies to prevent and treat these infections. Recently, numerous scientific advancements have been made in the understanding of pathogenicity mechanisms in general, and the basic biology, epidemiology, and the human immune response towards these amoebae in particular. In this review, we combine this knowledge and aim to identify which factors can explain the differences between the lethal brain infections caused by N. fowleri, B. mandrillaris, and Acanthamoeba spp.
Topics: Acanthamoeba; Amebiasis; Amoeba; Balamuthia mandrillaris; Encephalitis; Humans; Naegleria fowleri
PubMed: 34758928
DOI: 10.1016/j.pt.2021.10.004 -
Trends in Parasitology Apr 2018In addition to well-known human-infecting species, Entamoeba species not found in humans have been identified recently in nonhuman primates (NHPs). Importantly, it has... (Review)
Review
In addition to well-known human-infecting species, Entamoeba species not found in humans have been identified recently in nonhuman primates (NHPs). Importantly, it has become clear that the organism identified as Entamoeba histolytica in NHPs is usually a distinct species, Entamoeba nuttalli. Many DNA-based stool surveys use species-specific detection methods and so may miss the full range of Entamoeba species present. In addition, authors may be using the same species name to describe distinct organisms. These various shortcomings may not be obvious to readers. In this review, we clarify the relationships between Entamoeba species' names based on morphological and molecular data, and highlight gaps in recently published data on Entamoeba species in wild NHPs resulting from the use of variable methodology.
Topics: Animals; Biodiversity; Entamoeba; Entamoebiasis; Primate Diseases; Primates; Species Specificity
PubMed: 29396202
DOI: 10.1016/j.pt.2017.12.008 -
Scientific Reports Jul 2022The supergroup Amoebozoa unites a wide diversity of amoeboid organisms and encompasses enigmatic lineages that have been recalcitrant to modern phylogenetics. Deep...
The supergroup Amoebozoa unites a wide diversity of amoeboid organisms and encompasses enigmatic lineages that have been recalcitrant to modern phylogenetics. Deep divergences, taxonomic placement of some key taxa and character evolution in the group largely remain poorly elucidated or controversial. We surveyed available Amoebozoa genomes and transcriptomes to mine conserved putative single copy genes, which were used to enrich gene sampling and generate the largest supermatrix in the group to date; encompassing 824 genes, including gene sequences not previously analyzed. We recovered a well-resolved and supported tree of Amoebozoa, revealing novel deep level relationships and resolving placement of enigmatic lineages congruent with morphological data. In our analysis the deepest branching group is Tubulinea. A recent proposed major clade Tevosa, uniting Evosea and Tubulinea, is not supported. Based on the new phylogenetic tree, paleoecological and paleontological data as well as data on the biology of presently living amoebozoans, we hypothesize that the evolution of Amoebozoa probably was driven by adaptive responses to a changing environment, where successful survival and predation resulted from a capacity to disrupt and graze on microbial mats-a dominant ecosystem of the mid-Proterozoic period of the Earth history.
Topics: Amoeba; Amoebozoa; Ecosystem; Lobosea; Phylogeny
PubMed: 35778543
DOI: 10.1038/s41598-022-15372-7 -
Microbial Ecology Nov 2018Free-living amoebae are protists that are widely distributed in the environment including water, soil, and air. Although the amoebae of the genus Acanthamoeba are still... (Review)
Review
Free-living amoebae are protists that are widely distributed in the environment including water, soil, and air. Although the amoebae of the genus Acanthamoeba are still the most studied, other species, such as Vermamoeba vermiformis (formerly Hartmannella vermiformis), are the subject of increased interest. Found in natural or man-made aquatic environments, V. vermiformis can support the multiplication of other microorganisms and is able to harbor and potentially protect pathogenic bacteria or viruses. This feature is to be noted because of the presence of this thermotolerant amoeba in hospital water networks. As a consequence, this protist could be implicated in health concerns and be indirectly responsible for healthcare-related infections. This review highlights, among others, the consequences of V. vermiformis relationships with other microorganisms and shows that this free-living amoeba species is therefore of interest for public health.
Topics: Hartmannella; Hospitals; Public Health; RNA, Protozoan; RNA, Ribosomal, 18S; Sequence Analysis, RNA; Water Supply
PubMed: 29737382
DOI: 10.1007/s00248-018-1199-8 -
European Journal of Cell Biology Jun 2015The current eukaryotic tree of life groups most eukaryotes into one of five supergroups, the Opisthokonta, Amoebozoa, Archaeplastida, Excavata and SAR (Stramenopile,... (Review)
Review
The current eukaryotic tree of life groups most eukaryotes into one of five supergroups, the Opisthokonta, Amoebozoa, Archaeplastida, Excavata and SAR (Stramenopile, Alveolata, Rhizaria). Molecular and comparative morphological analyses revealed that the last eukaryotic common ancestor (LECA) already contained a rather sophisticated equipment of organelles including a mitochondrion, an endomembrane system, a nucleus with a lamina, a microtubule-organizing center (MTOC), and a flagellar apparatus. Recent studies of MTOCs, basal bodies/centrioles, and nuclear envelope organization of organisms in different supergroups have clarified our picture of how the nucleus and MTOCs co-evolved from LECA to extant eukaryotes. In this review we summarize these findings with special emphasis on valuable contributions of research on a lamin-like protein, nuclear envelope proteins, and the MTOC in the amoebozoan model organism Dictyostelium discoideum.
Topics: Amoeba; Animals; Biological Evolution; Centrosome; Chromatin; Dictyostelium; Humans; Nuclear Lamina; Phylogeny
PubMed: 25952183
DOI: 10.1016/j.ejcb.2015.04.004