scholarly journals Assessing the microbial community dynamics and the role of bacteriophages in bacterial mortality in Lake Geneva

2006 ◽  
Vol 19 (2) ◽  
pp. 115-126 ◽  
Author(s):  
Solange Duhamel ◽  
Isabelle Domaizon-Pialat ◽  
Sébastien Personnic ◽  
Stéphan Jacquet
Keyword(s):  
Community Dynamics ◽  
Heterotrophic Bacteria ◽  
Critical Role ◽  
Lake Geneva ◽  
Bacterial Mortality ◽  
Microbial Community Dynamics ◽  
First Time ◽  
New Evidence

SummaryThe aims of this work were to study, for the first time, the succession of microbial communities (from viruses to ciliates) in the largest occidental European lake (Lake Geneva) and to perform two one-weekin situexperiments in March-April (Exp1) and May (Exp2) 2004 in order to assess both small flagellate protozoan and virus-induced mortality of heterotrophic bacteria. Both nanoflagellates and viruses could be responsible for 31 to 42% of the total daily mortality of heterotrophic bacteria. In May (Exp2), viruses could explain up to 10% of the bacterial mortality whereas flagellates were responsible for 32% of the bacterioplankton removal. These results provide new evidence for the critical role played by viruses in the functioning of the microbial food webs and highlight the importance of further considering this biological compartment for a better understanding of the plankton ecology of Lake Geneva.

Molecular modulation of calcium oxalate crystallization

2006 ◽  
Vol 291 (6) ◽  
pp. F1123-F1132 ◽  
Author(s):  
James J. De Yoreo ◽  
S. Roger Qiu ◽  
John R. Hoyer
Keyword(s):  
Molecular Modeling ◽  
Calcium Oxalate ◽  
Stone Formation ◽  
Energy Levels ◽  
Critical Role ◽  
Specific Interactions ◽  
Crystal Surfaces ◽  
Site Specific

Calcium oxalate monohydrate (COM) is the primary constituent of the majority of renal stones. Osteopontin (OPN), an aspartic acid-rich urinary protein, and citrate, a much smaller molecule, are potent inhibitors of COM crystallization at levels present in normal urine. Current concepts of the role of site-specific interactions in crystallization derived from studies of biomineralization are reviewed to provide a context for understanding modulation of COM growth at a molecular level. Results from in situ atomic force microscopy (AFM) analyses of the effects of citrate and OPN on growth verified the critical role of site-specific interactions between these growth modulators and individual steps on COM crystal surfaces. Molecular modeling investigations of interactions of citrate with steps and faces on COM crystal surfaces provided links between the stereochemistry of interaction and the binding energy levels that underlie mechanisms of growth modification and changes in overall crystal morphology. The combination of in situ AFM and molecular modeling provides new knowledge that will aid rationale design of therapeutic agents for inhibition of stone formation.

Active and total microbial community dynamics and the role of functional genes bamA and mcrA during anaerobic digestion of phenol and p-cresol

2018 ◽  
Vol 264 ◽  
pp. 290-297 ◽  
Author(s):  
Oscar Franchi ◽  
Patricia Bovio ◽  
Eduardo Ortega-Martínez ◽  
Francisca Rosenkranz ◽  
Rolando Chamy
Keyword(s):  
Microbial Community ◽  
Anaerobic Digestion ◽  
Community Dynamics ◽  
Functional Genes ◽  
Microbial Community Dynamics

scholarly journals Dynamics of Hydrology and Anaerobic Hydrocarbon Degrader Communities in A Tar-Oil Contaminated Aquifer

2019 ◽  
Vol 7 (2) ◽  
pp. 46 ◽  
Author(s):  
Giovanni Pilloni ◽  
Anne Bayer ◽  
Bettina Ruth-Anneser ◽  
Lucas Fillinger ◽  
Marion Engel ◽  
...  
Keyword(s):  
Community Dynamics ◽  
Ecological Status ◽  
Contaminated Aquifer ◽  
Contaminant Plumes ◽  
Microbial Community Dynamics ◽  
Remediation Strategies ◽  
Tar Oil ◽  
Microbial Habitat ◽  
Hydrocarbon Degraders

Aquifers are typically perceived as rather stable habitats, characterized by low biogeochemical and microbial community dynamics. Upon contamination, aquifers shift to a perturbed ecological status, in which specialized populations of contaminant degraders establish and mediate aquifer restoration. However, the ecological controls of such degrader populations, and possible feedbacks between hydraulic and microbial habitat components, remain poorly understood. Here, we provide evidence of such couplings, via 4 years of annual sampling of groundwater and sediments across a high-resolution depth-transect of a hydrocarbon plume. Specialized anaerobic degrader populations are known to be established at the reactive fringes of the plume. Here, we show that fluctuations of the groundwater table were paralleled by pronounced dynamics of biogeochemical processes, pollutant degradation, and plume microbiota. Importantly, a switching in maximal relative abundance between dominant degrader populations within the Desulfobulbaceae and Desulfosporosinus spp. was observed after hydraulic dynamics. Thus, functional redundancy amongst anaerobic hydrocarbon degraders could have been relevant in sustaining biodegradation processes after hydraulic fluctuations. These findings contribute to an improved ecological perspective of contaminant plumes as a dynamic microbial habitat, with implications for both monitoring and remediation strategies in situ.

scholarly journals Treatment of Metastatic Disease through Natural Killer Cell Modulation by Infected Cell Vaccines

Viruses ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 434
Author(s):  
Seyedeh Raheleh Niavarani ◽  
Christine Lawson ◽  
Lee-Hwa Tai
Keyword(s):  
Infected Cell ◽  
Natural Killer ◽  
Tumor Antigens ◽  
Critical Role ◽  
Killer Cell ◽  
Oncolytic Viruses ◽  
Cell Vaccine ◽  
Tumor Killing

Oncolytic viruses (OVs) are a form of immunotherapy that release tumor antigens in the context of highly immunogenic viral signals following tumor-targeted infection and destruction. Emerging preclinical and clinical evidence suggests that this in situ vaccine effect is critical for successful viro-immunotherapy. In this review, we discuss the application of OV as an infected cell vaccine (ICV) as one method of enhancing the potency and breadth of anti-tumoral immunity. We focus on understanding and manipulating the critical role of natural killer (NK) cells and their interactions with other immune cells to promote a clinical outcome. With a synergistic tumor killing and immune activating mechanism, ICVs represent a valuable new addition to the cancer fighting toolbox with the potential to treat malignant disease.

scholarly journals The Critical Role of Biliary Candidiasis in Development of Surgical Site Infections after Pancreatoduodenectomy: Results of Prospective Study Using a Selective Culture Medium for Candida Species

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Hiroyuki Kato ◽  
Yusuke Iizawa ◽  
Kei Nakamura ◽  
Kazuyuki Gyoten ◽  
Aoi Hayasaki ◽  
...  
Keyword(s):  
Risk Factor ◽  
Candida Species ◽  
Critical Role ◽  
Significant Risk ◽  
Surgical Site Infections ◽  
Preoperative Assessment ◽  
Significant Risk Factor ◽  
High Level ◽  
New Evidence

In accordance with previous reports, the incidence of biliary candidiasis (BC) after pancreaticoduodenectomy (PD) was reported to be 0 to 5%, and the clinical significance of BC still has been elusive. In this study, we prospectively evaluated the precise incidence of BC after PD using the CHROMagar Candida plate in an attempt to elucidate whether BC has a significant impact on the clinical outcomes after PD.Patients and Method. From November 2014 to March 2016, the consecutive 51 patients who underwent PD were enrolled for this study. The bile juice was prospectively collected through the biliary stent tube on postoperative days (POD) 3, 7, and 14 and directly incubated onto the CHROMagar Candida plate for the cultivation of various Candida species. In the presence or absence of BC, we compared the incidence of SSIs.Results. The incidence of postoperative BC was 15% on POD 3, 24% on POD 7, and 39% on POD 14, respectively. Taken together, 22 patients out of 51 (43.1%) developed BC after PD. Moreover, the incidence of SSIs was significantly higher in patients with BC than in those without it (71% versus 7%, p=0.005). BC was selected as the only significant risk factor of SSIs after PD among the various risk factors. Even though a cause of BC is unknown, high level of alkaline phosphatase (cut-off line >300 IU/L) was selected as the only preoperative risk factor of the development of BC.Conclusion. We elucidated new evidence in which BC could be the independent cause of SSIs after PD and should not be recognized as just contamination artifacts. Preoperative assessment for identifying carriers of Candida species might be essential for reducing the incidence of SSIs after PD.

scholarly journals Isolation and Characterization of Cryptococcus neoformans Spores Reveal a Critical Role for Capsule Biosynthesis Genes in Spore Biogenesis

2009 ◽  
Vol 8 (4) ◽  
pp. 595-605 ◽  
Author(s):  
Michael R. Botts ◽  
Steven S. Giles ◽  
Marcellene A. Gates ◽  
Thomas R. Kozel ◽  
Christina M. Hull
Keyword(s):  
Cryptococcus Neoformans ◽  
Fungal Pathogens ◽  
Critical Role ◽  
Spore Formation ◽  
Yeast Cells ◽  
Isolation And Characterization ◽  
Specific Configuration ◽  
First Time

ABSTRACT Spores are essential particles for the survival of many organisms, both prokaryotic and eukaryotic. Among the eukaryotes, fungi have developed spores with superior resistance and dispersal properties. For the human fungal pathogens, however, relatively little is known about the role that spores play in dispersal and infection. Here we present the purification and characterization of spores from the environmental fungus Cryptococcus neoformans. For the first time, we purified spores to homogeneity and assessed their morphological, stress resistance, and surface properties. We found that spores are morphologically distinct from yeast cells and are covered with a thick spore coat. Spores are also more resistant to environmental stresses than yeast cells and display a spore-specific configuration of polysaccharides on their surfaces. Surprisingly, we found that the surface of the spore reacts with antibodies to the polysaccharide glucuronoxylomannan, the most abundant component of the polysaccharide capsule required for C. neoformans virulence. We explored the role of capsule polysaccharide in spore development by assessing spore formation in a series of acapsular strains and determined that capsule biosynthesis genes are required for proper sexual development and normal spore formation. Our findings suggest that C. neoformans spores may have an adapted cell surface that facilitates persistence in harsh environments and ultimately allows them to infect mammalian hosts.

scholarly journals Seasonal and Sexual Differences in the Microbiota of the Hoopoe Uropygial Secretion

Genes ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 407 ◽  
Author(s):  
Sonia Rodríguez-Ruano ◽  
Manuel Martín-Vivaldi ◽  
Juan Peralta-Sánchez ◽  
Ana García-Martín ◽  
Ángela Martínez-García ◽  
...  
Keyword(s):  
Breeding Season ◽  
Community Dynamics ◽  
Quantitative Polymerase Chain Reaction ◽  
Infection Risk ◽  
Uropygial Gland ◽  
Molecular Fingerprinting ◽  
Microbial Community Dynamics ◽  
High Infection ◽  
Uropygial Secretion

The uropygial gland of hoopoe nestlings and nesting females hosts bacterial symbionts that cause changes in the characteristics of its secretion, including an increase of its antimicrobial activity. These changes occur only in nesting individuals during the breeding season, possibly associated with the high infection risk experienced during the stay in the hole-nests. However, the knowledge on hoopoes uropygial gland microbial community dynamics is quite limited and based so far on culture-dependent and molecular fingerprinting studies. In this work, we sampled wild and captive hoopoes of different sex, age, and reproductive status, and studied their microbiota using quantitative polymerase chain reaction (qPCR), fluorescence in situ hybridization (FISH) and pyrosequencing. Surprisingly, we found a complex bacterial community in all individuals (including non-nesting ones) during the breeding season. Nevertheless, dark secretions from nesting hoopoes harbored significantly higher bacterial density than white secretions from breeding males and both sexes in winter. We hypothesize that bacterial proliferation may be host-regulated in phases of high infection risk (i.e., nesting). We also highlight the importance of specific antimicrobial-producing bacteria present only in dark secretions that may be key in this defensive symbiosis. Finally, we discuss the possible role of environmental conditions in shaping the uropygial microbiota, based on differences found between wild and captive hoopoes.

Functional role of a polymorphism in the Pannexin1 gene in collageninduced platelet aggregation

2015 ◽  
Vol 114 (08) ◽  
pp. 325-336 ◽  
Author(s):  
Filippo Molica ◽  
Jean-François Denis ◽  
Paul Bradfield ◽  
Silvia Penuela ◽  
Anne Zufferey ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Reactivity ◽  
Critical Role ◽  
Atp Release ◽  
Human Platelets ◽  
Immune Synapse ◽  
Cardiovascular Patients ◽  
Exogenous Expression ◽  
First Time

SummaryPannexin1 (Panx1) forms ATP channels that play a critical role in the immune response by reinforcing purinergic signal amplification in the immune synapse. Platelets express Panx1 and given the importance of ATP release in platelets, we investigated Panx1 function in platelet aggregation and the potential impact of genetic polymorphisms on Panx1 channels. We show here that Panx1 forms ATP release channels in human platelets and that inhibiting Panx1 channel function with probenecid, mefloquine or specific 10Panx1 peptides reduces collagen-induced platelet aggregation but not the response induced by arachidonic acid or ADP. These results were confirmed using Panx1-/- platelets. Natural variations have been described in the human Panx1 gene, which are predicted to induce non-conservative amino acid substitutions in its coding sequence. Healthy subjects homozygous for Panx1–400C, display enhanced platelet reactivity in response to collagen compared with those bearing the Panx1–400A allele. Conversely, the frequency of Panx1–400C homozygotes was increased among cardiovascular patients with hyper-reactive platelets compared with patients with hypo-reactive platelets. Exogenous expression of polymorphic Panx1 channels in a Panx-deficient cell line revealed increased basal and stimulated ATP release from cells transfected with Panx1–400C channels compared with Panx1–400A expressing transfectants. In conclusion, we demonstrate a specific role for Panx1 channels in the signalling pathway leading to collagen-induced platelet aggregation. Our study further identifies for the first time an association between a Panx1–400A>C genetic polymorphism and collagen-induced platelet reactivity. The Panx1–400C variant encodes for a gain-of-function channel that may adversely affect atherothrombosis by specifically enhancing collagen-induced ATP release and platelet aggregation.

scholarly journals Robust procedure for creating and characterizing the atomic structure of scanning tunneling microscope tips

2017 ◽  
Vol 8 ◽  
pp. 2389-2395 ◽  
Author(s):  
Sumit Tewari ◽  
Koen M Bastiaans ◽  
Milan P Allan ◽  
Jan M van Ruitenbeek
Keyword(s):  
Atomic Structure ◽  
Scanning Tunneling Microscope ◽  
Critical Role ◽  
Atomic Layer ◽  
Atomic Scale ◽  
Scanning Tunneling ◽  
Tunneling Microscope ◽  
Stm Tips

Scanning tunneling microscopes (STM) are used extensively for studying and manipulating matter at the atomic scale. In spite of the critical role of the STM tip, procedures for controlling the atomic-scale shape of STM tips have not been rigorously justified. Here, we present a method for preparing tips in situ while ensuring the crystalline structure and a reproducibly prepared tip structure up to the second atomic layer. We demonstrate a controlled evolution of such tips starting from undefined tip shapes.

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