scholarly journals SARS-CoV-2 surrogate (Phi6) environmental persistence within free-living amoebae

2021 ◽  
Author(s):  
Rafik Dey ◽  
Elena Dlusskaya ◽  
Nicholas J. Ashbolt
Keyword(s):  
Respiratory Virus ◽  
Viral Persistence ◽  
Model System ◽  
Aquatic Environments ◽  
Environmental Persistence ◽  
Free Living ◽  
Microscopy Imaging ◽  
Successful Model ◽  
Imaging Flow Cytometry ◽  
Induced Apoptosis

Abstract The reported persistence of SARS-CoV-2 virions in aquatic environments highlights the need to better understand potential mechanisms that may prolong its dissemination. We evaluated the possibility that amoebae might serve as transport hosts by studying the interaction of the enveloped bacteriophage Phi6, as a potential surrogated along with one of the most common amoebae in engineered aquatic environments, Vermamoeba vermiformis. Using microscopy, imaging flow cytometry and bacteriophage cell culture, our results imply that the SARS-CoV-2 surrogate triggers amoebic mitochondria and induced apoptosis to promote viral persistence in trophozoites. Furthermore, virus-infected amoebae were still infectious after 2 months within FLA cysts. These results suggest that amoebae could contribute to the environmental persistence of SARS-CoV-2, including disinfection processes. In addition, amoebae could be a successful model system for understanding respiratory virus-eukaryotic biology at the cellular and molecular levels.

scholarly journals Mitigation of Expression of Virulence Genes in Legionella pneumophila Internalized in the Free-Living Amoeba Willaertia magna C2c Maky

Pathogens ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 447 ◽  
Author(s):  
Rayane Mouh Mameri ◽  
Jacques Bodennec ◽  
Laurent Bezin ◽  
Sandrine Demanèche
Keyword(s):  
Gene Expression ◽  
Legionella Pneumophila ◽  
Virulence Genes ◽  
Natural Habitat ◽  
Acanthamoeba Castellanii ◽  
Severe Form ◽  
Aquatic Environments ◽  
Free Living ◽  
Intracellular Parasites ◽  
Free Living Amoeba

Legionella pneumophila is a human pathogen responsible for a severe form of pneumonia named Legionnaire disease. Its natural habitat is aquatic environments, being in a free state or intracellular parasites of free-living amoebae, such as Acanthamoeba castellanii. This pathogen is able to replicate within some amoebae. Willaertia magna C2c Maky, a non-pathogenic amoeba, was previously demonstrated to resist to L. pneumophila and even to be able to eliminate the L. pneumophila strains Philadelphia, Lens, and Paris. Here, we studied the induction of seven virulence genes of three L. pneumophila strains (Paris, Philadelphia, and Lens) within W. magna C2c Maky in comparison within A. castellanii and with the gene expression level of L. pneumophila strains alone used as controls. We defined a gene expression-based virulence index to compare easily and without bias the transcript levels in different conditions and demonstrated that W. magna C2c Maky did not increase the virulence of L. pneumophila strains in contrast to A. castellanii. These results confirmed the non-permissiveness of W. magna C2c Maky toward L. pneumophila strains.

scholarly journals The human pathogenic vibrios – A public health update with environmental perspectives

1989 ◽  
Vol 103 (1) ◽  
pp. 1-34 ◽  
Author(s):  
P. A. West
Keyword(s):  
Public Health ◽  
Acute Infection ◽  
Aquatic Environments ◽  
Free Living ◽  
Liver Disorders ◽  
Naturally Occurring ◽  
Pathogenic Vibrio ◽  
Ear Infections ◽  
Pathogenic Vibrios ◽  
Living Bacteria

PathogenicVibriospecies are naturally-occurring bacteria in freshwater and saline aquatic environments. Counts of free-living bacteria in water are generally less than required to induce disease. Increases in number of organisms towards an infective dose can occur as water temperatures rise seasonally followed by growth and concentration of bacteria on higher animals, such as chitinous plankton, or accumulation by shellfish and seafood. PathogenicVibriospecies must elaborate a series of virulence factors to elicit disease in humans.Activities which predispose diarrhoeal and extraintestinal infections include ingestion of seafood and shellfish and occupational or recreational exposure to natural aquatic environments, especially those above 20 °C. Travel to areas endemic for diseases due to pathogenicVibriospecies may be associated with infections. Host risk factors strongly associated with infections are lack of gastric acid and liver disorders.Involvement of pathogenicVibriospecies in cases of diarrhoea should be suspected especially if infection is associated with ingestion of seafood or shellfish, raw or undercooked, in the previous 72 h.Vibriospecies should be suspected in any acute infection associated with wounds sustained or exposed in the marine or estuarine environment. Laboratories serving coastal areas where infection due to pathogenic Vibrio species are most likely to occur should consider routine use of TCBS agar and other detection regimens for culture ofVibriospecies from faeces, blood and samples from wound and ear infections.

Genetics of plant-microbe nitrogen-fixing symbiosis

1985 ◽  
Vol 85 (3-4) ◽  
pp. 239-252
Author(s):  
G. C. Machray ◽  
W. D. P. Stewart
Keyword(s):  
Nitrogen Fixation ◽  
Genetic Analysis ◽  
Symbiotic Nitrogen Fixation ◽  
Model System ◽  
Present Knowledge ◽  
Nitrogen Fixing ◽  
Free Living ◽  
Genetic Level ◽  
And Control ◽  
Control Of Expression

SynopsisA wide variety of plant-microbe nitrogen-fixing symbioses which include cyanobacteria as the nitrogenfixing partner exist. While some information has been gathered on the biochemical changes in the cyanobacterium upon entering into symbiosis, very little is known about the accompanying changes at the genetic level. Much of our present knowledge of the organisation and control of expression of nitrogenfixation (nif) genes is derived from studies of the free-living diazotroph Klebsiella pneumoniae. This organism thus provides a model system and source of experimental material for the genetic analysis of symbiotic nitrogen fixation. We describe the use of cloned K. pneumoniae genes for nitrogen fixation and its regulation in the genetic analysis' of nitrogen fixation in cyanobacteria which can enter into symbiosis with plants. These studies reveal some dissimilarities in the organisation of nif genes and raise questions as to the genetic control of nitrogen fixation in symbiosis.

QUANTITATIVE FRET MEASUREMENT BASED ON CONFOCAL MICROSCOPY IMAGING AND PARTIAL ACCEPTOR PHOTOBLEACHING

2012 ◽  
Vol 05 (03) ◽  
pp. 1250015 ◽  
Author(s):  
XIAO-PING WANG ◽  
HUAI-NA YU ◽  
TONG-SHENG CHEN
Keyword(s):  
Protein Interactions ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Region Of Interest ◽  
Living Cells ◽  
Live Cells ◽  
Protein Protein Interactions ◽  
Microscopy Imaging ◽  
Acceptor Photobleaching ◽  
Induced Apoptosis

Fluorescence resonance energy transfer (FRET) technology had been widely used to study protein–protein interactions in living cells. In this study, we developed a ROI-PbFRET method to real-time quantitate the FRET efficiency of FRET construct in living cells by combining the region of interest (ROI) function of confocal microscope and partial acceptor photobleaching. We validated the ROI-PbFRET method using GFPs-based FRET constructs including 18AA and SCAT3, and used it to quantitatively monitor the dynamics of caspase-3 activation in single live cells stably expressing SCAT3 during staurosporine (STS)-induced apoptosis. Our results for the first demonstrate that ROI-PbFRET method is a powerful potential tool for detecting the dynamics of molecular interactions in live cells.

scholarly journals Virtual-freezing fluorescence imaging flow cytometry

2020 ◽  
Author(s):  
Hideharu Mikami ◽  
Makoto Kawaguchi ◽  
Chun-Jung Huang ◽  
Hiroki Matsumura ◽  
Takeaki Sugimura ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Spatial Resolution ◽  
High Throughput ◽  
Cancer Biology ◽  
Single Cells ◽  
Image Sensor ◽  
Imaging Method ◽  
Microscopy Imaging ◽  
Trade Off ◽  
Imaging Flow Cytometry

ABSTRACTBy virtue of the combined merits of flow cytometry and fluorescence microscopy, imaging flow cytometry (IFC) has become an established tool for cell analysis in diverse biomedical fields such as cancer biology, microbiology, immunology, hematology, and stem cell biology. However, the performance and utility of IFC are severely limited by the fundamental trade-off between throughput, sensitivity, and spatial resolution. For example, at high flow speed (i.e., high throughput), the integration time of the image sensor becomes short, resulting in reduced sensitivity or pixel resolution. Here we present an optomechanical imaging method that overcomes the trade-off by virtually “freezing” the motion of flowing cells on the image sensor to effectively achieve 1,000 times longer exposure time for microscopy-grade fluorescence image acquisition. Consequently, it enables high-throughput IFC of single cells at >10,000 cells/s without sacrificing sensitivity and spatial resolution. The availability of numerous information-rich fluorescence cell images allows high-dimensional statistical analysis and accurate classification with deep learning, as evidenced by our demonstration of unique applications in hematology and microbiology.

Census of “ Microturbellarians” (free-living Platyhelminthes) of the zoogeographical regions originating from Gondwana

Zootaxa ◽  
2003 ◽  
Vol 146 (1) ◽  
pp. 1 ◽  
Author(s):  
CAROLINA NOREÑA ◽  
FRANCISCO BRUSA ◽  
ANNO FAUBEL
Keyword(s):  
Complete Data ◽  
Aquatic Environments ◽  
New Combinations ◽  
Free Living

In this study we review microturbellarian species known to occur in zoogeographical regions that originated from Gondwana. The 510 reported species are from all types of aquatic environments (marine, brackish and freshwater). Complete data of the distribution and bibliographical references are provided. In addition, taxonomic discrepancies, as well as new combinations, are clarified. This checklist is the first revised compendium of the microturbellarians of the Gondwanian zoogeographical regions.

scholarly journals NhaA, an Na+/H+ Antiporter Involved in Environmental Survival of Vibrio cholerae

2000 ◽  
Vol 182 (10) ◽  
pp. 2937-2944 ◽  
Author(s):  
Sophie Vimont ◽  
Patrick Berche
Keyword(s):  
Vibrio Cholerae ◽  
Vibrio Parahaemolyticus ◽  
Natural Habitat ◽  
Aquatic Environments ◽  
Wild Type ◽  
Transcriptional Fusion ◽  
Free Living ◽  
E Coli ◽  
Functional Homology ◽  
Wide Range

ABSTRACT Vibrio cholerae, the agent of cholera, is a normal inhabitant of aquatic environments, in which it survives under a wide range of conditions of pH and salinity. In this work, we identified thenhaA gene in a wild-type epidemic strain of V. cholerae O1. nhaA encodes a protein of 382 amino acids that is very similar to the proteins NhaA of Vibrio parahaemolyticus, Vibrio alginolyticus (∼87% identity), and Escherichia coli (56% identity). V. cholerae NhaA complements an E. coli nhaA mutant, enabling it to grow in 700 mM NaCl, pH 7.5, indicating functional homology to E. coli NhaA. However, unlike E. coli, the growth of a nhaA-inactivated mutant ofV. cholerae was not restricted at various pH and NaCl concentrations, although it was inhibited in the presence of 120 mM LiCl at pH 8.5. Nevertheless, using a nhaA′-lacZtranscriptional fusion, we observed induction of nhaAtranscription by Na+, Li+, and K+. These results strongly suggest that NhaA is an Na+/H+ antiporter contributing to the Na+/H+ homeostasis of V. cholerae. nhaA-related sequences were detected in all strains ofV. cholerae from the various serogroups. This gene is presumably involved in the survival and persistence of free-living bacteria in their natural habitat.

scholarly journals Cleavage of Mcd1 by Caspase-like Protease Esp1 Promotes Apoptosis in Budding Yeast

2008 ◽  
Vol 19 (5) ◽  
pp. 2127-2134 ◽  
Author(s):  
Hui Yang ◽  
Qun Ren ◽  
Zhaojie Zhang
Keyword(s):  
Hydrogen Peroxide ◽  
Cell Death ◽  
Membrane Potential ◽  
Cytochrome C ◽  
Mitochondrial Membrane ◽  
Apoptotic Cell ◽  
Model System ◽  
Dependent Manner ◽  
Induced Apoptosis ◽  
Dual Functions

Over the last decade, yeast has been used successfully as a model system for studying the molecular mechanism of apoptotic cell death. Here, we report that Mcd1, the yeast homology of human cohesin Rad21, plays an important role in hydrogen peroxide-induced apoptosis in yeast. On induction of cell death, Mcd1 is cleaved and the C-terminal fragment is translocated from nucleus into mitochondria, causing the decrease of mitochondrial membrane potential and the amplification of cell death in a cytochrome c-dependent manner. We further demonstrate that the caspase-like protease Esp1 has dual functions and that it is responsible for the cleavage of Mcd1 during the hydrogen peroxide-induced apoptosis. When apoptosis is induced, Esp1 is released from the anaphase inhibitor Pds1. The activated Esp1 acts as caspase-like protease for the cleavage of Mcd1, which enhances the cell death via its translocation from nucleus to mitochondria.

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