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Revista Chilena de Infectologia :... 2018
Topics: Amoeba; Humans; Peru
PubMed: 31095187
DOI: 10.4067/S0716-10182018000600669 -
Genome Biology and Evolution Jul 2020The origin of plastids (chloroplasts) by endosymbiosis stands as one of the most important events in the history of eukaryotic life. The genetic, biochemical, and cell... (Review)
Review
The origin of plastids (chloroplasts) by endosymbiosis stands as one of the most important events in the history of eukaryotic life. The genetic, biochemical, and cell biological integration of a cyanobacterial endosymbiont into a heterotrophic host eukaryote approximately a billion years ago paved the way for the evolution of diverse algal groups in a wide range of aquatic and, eventually, terrestrial environments. Plastids have on multiple occasions also moved horizontally from eukaryote to eukaryote by secondary and tertiary endosymbiotic events. The overall picture of extant photosynthetic diversity can best be described as "patchy": Plastid-bearing lineages are spread far and wide across the eukaryotic tree of life, nested within heterotrophic groups. The algae do not constitute a monophyletic entity, and understanding how, and how often, plastids have moved from branch to branch on the eukaryotic tree remains one of the most fundamental unsolved problems in the field of cell evolution. In this review, we provide an overview of recent advances in our understanding of the origin and spread of plastids from the perspective of comparative genomics. Recent years have seen significant improvements in genomic sampling from photosynthetic and nonphotosynthetic lineages, both of which have added important pieces to the puzzle of plastid evolution. Comparative genomics has also allowed us to better understand how endosymbionts become organelles.
Topics: Amoeba; Biological Evolution; Chromatophores; Diatoms; Genomics; Photosynthesis; Plastids; Symbiosis
PubMed: 32402068
DOI: 10.1093/gbe/evaa096 -
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 -
Current Biology : CB Jun 2019Cooperation has been essential to the evolution of biological complexity, but many societies struggle to overcome internal conflicts and divisions. Dictyostelium... (Review)
Review
Cooperation has been essential to the evolution of biological complexity, but many societies struggle to overcome internal conflicts and divisions. Dictyostelium discoideum, or the social amoeba, has been a useful model system for exploring these conflicts and how they can be resolved. When starved, these cells communicate, gather into groups, and build themselves into a multicellular fruiting body. Some cells altruistically die to form the rigid stalk, while the remainder sit atop the stalk, become spores, and disperse. Evolutionary theory predicts that conflict will arise over which cells die to form the stalk and which cells become spores and survive. The power of the social amoeba lies in the ability to explore how cooperation and conflict work across multiple levels, ranging from proximate mechanisms (how does it work?) to ultimate evolutionary answers (why does it work?). Recent studies point to solutions to the problem of ensuring fairness, such as the ability to suppress selfishness and to recognize and avoid unrelated individuals. This work confirms a central role for kin selection, but also suggests new explanations for how social amoebae might enforce cooperation. New approaches based on genomics are also enabling researchers to decipher for the first time the evolutionary history of cooperation and conflict and to determine its role in shaping the biology of multicellular organisms.
Topics: Biological Evolution; Dictyostelium; Microbial Interactions
PubMed: 31163162
DOI: 10.1016/j.cub.2019.04.022 -
Pathogens and Global Health Sep 2022Free-living amoebae (FLA) are considered environmental pathogens and thus pose a public health threat. Their ubiquity in natural sources may magnify the potential... (Review)
Review
Free-living amoebae (FLA) are considered environmental pathogens and thus pose a public health threat. Their ubiquity in natural sources may magnify the potential severity of health outcomes in the future. However, less attention was given despite several probable public health risks that arise from the presence of pathogenic strains in the environment. Here, we provide epidemiological data based on investigations involving the distribution and occurrence of free-living amoebae in the Republic of the Philippines. This aims to connect data of fragmented studies of these organisms and provide potential roadmaps in FLA research in the country. The majority of the reviewed articles (n = 19) focused on characterization studies (36.8%; 7/19) while environmental isolation and isolation from biological samples had an equal frequency of 31.6% (6/19) each. There is a great disparity between the established ubiquity in environmental sources and the number of cases of FLA infections in the country. FLA-related research in the Philippines is still in its inceptive stage with several gaps to fill, which can be used to formulate policy briefs in the future regarding its isolation, identification, diagnosis, therapeutic management, and control of FLA infections in the country.
Topics: Amebiasis; Amoeba; Environmental Monitoring; Epidemiological Monitoring; Humans; Philippines; Public Health
PubMed: 35112656
DOI: 10.1080/20477724.2022.2035626 -
Seminars in Cell & Developmental Biology Oct 2015
Topics: Amoeba; Animals; Bacteria; Bacterial Physiological Phenomena; Humans; Models, Biological; Movement; Plasmodium; Viruses
PubMed: 26431787
DOI: 10.1016/j.semcdb.2015.09.019 -
Science Advances Oct 2023Pancreatic ductal adenocarcinoma (PDAC) has a very poor prognosis because of its high propensity to metastasize and its immunosuppressive microenvironment. Using a panel...
Pancreatic ductal adenocarcinoma (PDAC) has a very poor prognosis because of its high propensity to metastasize and its immunosuppressive microenvironment. Using a panel of pancreatic cancer cell lines, three-dimensional (3D) invasion systems, microarray gene signatures, microfluidic devices, mouse models, and intravital imaging, we demonstrate that ROCK-Myosin II activity in PDAC cells supports a transcriptional program conferring amoeboid invasive and immunosuppressive traits and in vivo metastatic abilities. Moreover, we find that immune checkpoint CD73 is highly expressed in amoeboid PDAC cells and drives their invasive, metastatic, and immunomodulatory traits. Mechanistically, CD73 activates RhoA-ROCK-Myosin II downstream of PI3K. Tissue microarrays of human PDAC biopsies combined with bioinformatic analysis reveal that rounded-amoeboid invasive cells with high CD73-ROCK-Myosin II activity and their immunosuppressive microenvironment confer poor prognosis to patients. We propose targeting amoeboid PDAC cells as a therapeutic strategy.
Topics: Animals; Humans; Mice; Adenocarcinoma; Amoeba; Carcinoma, Pancreatic Ductal; Cell Line, Tumor; Cell Movement; Cytoskeletal Proteins; Immunosuppression Therapy; Myosin Type II; Pancreatic Neoplasms; Tumor Microenvironment
PubMed: 37851808
DOI: 10.1126/sciadv.adi0244 -
JMM Case Reports Jun 2016This case report describes a human survivor of infection. This is a free-living amoeba that can cause infection with the devastating consequence of near universally...
INTRODUCTION
This case report describes a human survivor of infection. This is a free-living amoeba that can cause infection with the devastating consequence of near universally fatal encephalitis. We report this case to demonstrate the possibility of recovery.
CASE PRESENTATION
A 26-year-old Hispanic male, a landscape gardener, presented to the hospital in March 2010 with a two month history of headache, visual disturbances and new-onset seizures. Brain imaging identified two enhancing central lesions and was later identified by brain biopsy. He received several months of various antimicrobials including miltefosine, a novel use of the drug in this disease at the time. Seven weeks into therapy, considerations were made to switch him to 'comfort care' because of worsening clinical status and seemingly lack of response to treatment. The patient finally demonstrated clinical and radiological improvement after eight weeks with modified therapy, despite experiencing some debilitating toxic effects likely to be related to antibiotics. Two years after his initial presentation he made a complete recovery.
CONCLUSION
amoebic encephalitis is considered an almost universally fatal disease; this case demonstrates the possibility of recovery. This report outlines his treatment, drug toxicities and includes additional information regarding the therapeutic use of the drug miltefosine. Whether his survival is related to the specific antimicrobials used in this case is unknown and further investigation is warranted.
PubMed: 28348755
DOI: 10.1099/jmmcr.0.005031 -
Annals of Agricultural and... May 2017[b]Abstract Introduction[/b]. Among free-living amoebae that are widely distributed in nature only four genera/species are known as agents of human infections:[i]... (Review)
Review
[b]Abstract Introduction[/b]. Among free-living amoebae that are widely distributed in nature only four genera/species are known as agents of human infections:[i] Acanthamoeba spp., Naegleriafowleri, Balamuthia mandrillaris[/i] and[i] Sappiniapedata[/i]. These amoebae are not well adapted to parasitism, and could exist in the human environment without the need for a host. Infections due to these amoebae, despite low morbidity, are characterized by relatively high mortality rate and pose serious clinical problems. [b]Objectve[/b]. This review study presents and summarizes current knowledge about infections due to pathogenic and opportunistic free-living amoebae focused on epidemiology, clinical manifestations, diagnosis and treatment based on global literature. [b]State of knowledge[/b]. All four genera have been recognized as etiologic factors of fatal central nervous system infections and other serious diseases in humans. [i]N. fowleri[/i] causes an acute fulminating meningoencephalitis in children and young adults. [i]Acanthamoeba spp[/i]. and [i]B.mandrillaris[/i] are opportunistic pathogens causing granulomatous amoebic encephalitis and disseminated or localized infections which could affect the skin, sinuses, lungs, adrenals and/or bones. [i]Acanthamoeba spp[/i]. is also the main agent of acute eye infection -[i] Acanthamoeba keratitis, [/i]mostly in contact lens wearers. However, there is only one recognized case of encephalitis caused by [i]S. pedata. [/i] [b]Conclusions[/b]. Amoebic diseases are difficult to diagnose which leads to delayed treatment, and result in a high mortality rate. Considering those issues, there is an urgent need to draw more attention to this type of diseases.
Topics: Amebiasis; Amoeba; Animals; Humans
PubMed: 28664704
DOI: 10.5604/12321966.1233568 -
Frontiers in Cellular and Infection... 2022A variety of bacteria have evolved the ability to interact with environmental phagocytic predators such as amoebae, which may have facilitated their subsequent...
A variety of bacteria have evolved the ability to interact with environmental phagocytic predators such as amoebae, which may have facilitated their subsequent interactions with phagocytes in animal hosts. Our recent study found that the animal pathogen can evade predation by the common soil amoeba , survive within, and hijack its complex life cycle as a propagation and dissemination vector. However, it is uncertain whether the mechanisms allowing interactions with predatory amoebae are conserved among species, because divergence, evolution, and adaptation to different hosts and ecological niches was accompanied by acquisition and loss of many genes. Here we tested 9 diverse species in three assays representing distinct aspects of their interactions with . Several human and animal pathogens retained the abilities to survive within single-celled amoeba, to inhibit amoebic plaque expansion, and to translocate with amoebae to the fruiting body and disseminate along with the fruiting body. In contrast, these abilities were partly degraded for the bird pathogen , and for the human-restricted species and . Interestingly, a different lineage of only known to infect sheep retained the ability to interact with , demonstrating that these abilities were lost in multiple lineages independently, correlating with niche specialization and recent rapid genome decay apparently mediated by insertion sequences. has been isolated sporadically from diverse human and environmental sources, has acquired insertion sequences, undergone genome decay and has also lost the ability to interact with amoebae, suggesting some specialization to some unknown niche. A genome-wide association study (GWAS) identified a set of genes that are potentially associated with the ability to interact with . These results suggest that massive gene loss associated with specialization of some species to a closed life cycle in a particular host was repeatedly and independently accompanied by loss of the ability to interact with amoebae in an environmental niche.
Topics: Amoeba; Animals; Bordetella; Bordetella bronchiseptica; Dictyostelium; Genome-Wide Association Study; Sheep
PubMed: 35223538
DOI: 10.3389/fcimb.2022.798317