scholarly journals Positive, Neutral and Negative Interactions in Cocultures between Pyrococcus furiosus and Different Methanogenic Archaea

2012 ◽  
Vol 5 ◽  
pp. MBI.S8516 ◽  
Author(s):  
Agnes Weiner ◽  
Simone Schopf ◽  
Gerhard Wanner ◽  
Alexander Probst ◽  
Reinhard Wirth
Keyword(s):  
Pyrococcus Furiosus ◽  
Model Organism ◽  
Methanogenic Archaea ◽  
Hyperthermophilic Archaea ◽  
Positive Interactions ◽  
Metabolic Intermediates ◽  
Positive Effects ◽  
Methanopyrus Kandleri ◽  
Inhibitory Interactions ◽  
Microscopic Techniques

The model organism Pyrococcus furiosus has recently been reported to interact with Methanopyrus kandleri in coculture, suggesting a H2 symbiosis. In the current study we further investigated this hypothesis by growing P. furiosus with four other hyperthermophilic methanogens providing evidence that the organisms did not only exert positive effects ( P. furiosus/ Methanocaldococcus villosus and P. furiosus/ Methanocaldococcus infernus) on each other, but also neutral ( P. furiosus/ Methanocaldococcus jannaschii) and even inhibitory interactions ( P. furiosus/ Methanotorris igneus) were detected suggesting interspecies relationships not only based on H2 symbiosis. Using various microscopic techniques we further analyzed the coculture with the highest positive interactions ( P. furiosus/ M. villosus) concerning its growth behavior on various surfaces, which turned out to be in stark contrast to the previous reported coculture of P. furiosus/ M. kandleri. This communication provides new insights into possible interactions of extremophilic Archaea in cocultures and again raises the question if and how hyperthermophilic Archaea communicate besides metabolic intermediates like H2.

Policing and the Legacies of Wartime State Predation: Evidence from a Survey and Field Experiment in Liberia

2021 ◽  
pp. 002200272110130
Author(s):  
Robert A. Blair ◽  
Benjamin S. Morse
Keyword(s):  
Field Experiment ◽  
Police Officers ◽  
Positive Interactions ◽  
Security Sector Reform ◽  
Security Sector ◽  
Sector Reform ◽  
Positive Effects ◽  
State Security ◽  
Post Conflict ◽  
Conflict Period

How does violence during civil war shape citizens’ willingness to trust and rely on state security providers in the post-conflict period? Can post-conflict security sector reform restore perceptions of state security forces among victims of wartime state predation? Using a survey and field experiment in Liberia, we show that rebel-perpetrated violence is strongly positively correlated with trust and reliance on the police after conflict is over, while state-perpetrated violence is not. Victims of wartime state predation are, however, more likely to update their priors about the police in response to positive interactions with newly reformed police officers. We also show that abuses committed by police officers in the post-conflict period are negatively correlated with citizens’ perceptions of the police, potentially counteracting the positive effects of security sector reform. We corroborate our quantitative findings with detailed qualitative observations of interactions between civilians and police officers in the field.

scholarly journals Genome Evolution at the Genus Level: Comparison of Three Complete Genomes of Hyperthermophilic Archaea

2001 ◽  
Vol 11 (6) ◽  
pp. 981-993
Author(s):  
Odile Lecompte ◽  
Raymond Ripp ◽  
Valérie Puzos-Barbe ◽  
Simone Duprat ◽  
Roland Heilig ◽  
...  
Keyword(s):  
Pyrococcus Furiosus ◽  
Hyperthermophilic Archaea ◽  
Trna Genes ◽  
Distance Ratio ◽  
Genomic Plasticity ◽  
Relative Contribution ◽  
Complete Genomes ◽  
Replication Terminus ◽  
Living Organisms ◽  
High Level

We have compared three complete genomes of closely related hyperthermophilic species of Archaea belonging to thePyrococcus genus: Pyrococcus abyssi, Pyrococcus horikoshii, and Pyrococcus furiosus. At the genomic level, the comparison reveals a differential conservation among four regions of the Pyrococcus chromosomes correlated with the location of genetic elements mediating DNA reorganization. This discloses the relative contribution of the major mechanisms that promote genomic plasticity in these Archaea, namely rearrangements linked to the replication terminus, insertion sequence-mediated recombinations, and DNA integration within tRNA genes. The combination of these mechanisms leads to a high level of genomic plasticity in these hyperthermophilic Archaea, at least comparable to the plasticity observed between closely related bacteria. At the proteomic level, the comparison of the threePyrococcus species sheds light on specific selection pressures acting both on their coding capacities and evolutionary rates. Indeed, thanks to two independent methods, the “reciprocal best hits“ approach and a new distance ratio analysis, we detect the false orthology relationships within the Pyrococcus lineage. This reveals a high amount of differential gains and losses of genes since the divergence of the three closely related species. The resulting polymorphism is probably linked to an adaptation of these free-living organisms to differential environmental constraints. As a corollary, we delineate the set of orthologous genes shared by the three species, that is, the genes that may characterize the Pyrococcus genus. In this conserved core, the amino acid substitution rate is equal between P. abyssi and P. horikoshii for most of their shared proteins, even for fast-evolving ones. In contrast, strong discrepancies exist among the substitution rates observed in P. furiosus relative to the two other species, which is in disagreement with the molecular clock hypothesis.

Thermostability and Thermoactivity of Citrate Synthases from the Thermophilic and Hyperthermophilic Archaea, Thermoplasma acidophilum and Pyrococcus furiosus

2000 ◽  
Vol 304 (4) ◽  
pp. 657-668 ◽  
Author(s):  
Michael A. Arnott ◽  
Rebecca A. Michael ◽  
Carl R. Thompson ◽  
David W. Hough ◽  
Michael J. Danson
Keyword(s):  
Pyrococcus Furiosus ◽  
Hyperthermophilic Archaea ◽  
Thermoplasma Acidophilum

An archaeal bi-species biofilm formed by Pyrococcus furiosus and Methanopyrus kandleri

2008 ◽  
Vol 190 (3) ◽  
pp. 371-377 ◽  
Author(s):  
Simone Schopf ◽  
Gerhard Wanner ◽  
Reinhard Rachel ◽  
Reinhard Wirth
Keyword(s):  
Pyrococcus Furiosus ◽  
Methanopyrus Kandleri

scholarly journals Novel Type of ADP-Forming Acetyl Coenzyme A Synthetase in Hyperthermophilic Archaea: Heterologous Expression and Characterization of Isoenzymes from the Sulfate Reducer Archaeoglobus fulgidus and the Methanogen Methanococcus jannaschii

2002 ◽  
Vol 184 (3) ◽  
pp. 636-644 ◽  
Author(s):  
Meike Musfeldt ◽  
Peter Schönheit
Keyword(s):  
Coenzyme A ◽  
Pyrococcus Furiosus ◽  
Sequence Similarity ◽  
Hyperthermophilic Archaea ◽  
Archaeoglobus Fulgidus ◽  
Methanococcus Jannaschii ◽  
Acetyl Coa ◽  
Acetyl Coenzyme A ◽  
Acetyl Coenzyme ◽  
Α And Β Subunits

ABSTRACT Acetyl coenzyme A (CoA) synthetase (ADP forming) (ACD) represents a novel enzyme of acetate formation and energy conservation (acetyl-CoA + ADP + Pi ⇌ acetate + ATP + CoA) in Archaea and eukaryotic protists. The only characterized ACD in archaea, two isoenzymes from the hyperthermophile Pyrococcus furiosus, constitute 145-kDa heterotetramers (α2, β2). The coding genes for the α and β subunits are located at different sites in the P. furiosus chromosome. Based on significant sequence similarity of the P. furiosus genes, five open reading frames (ORFs) encoding putative ACD were identified in the genome of the hyperthermophilic sulfate-reducing archaeon Archaeoglobus fulgidus and one ORF was identified in the hyperthermophilic methanogen Methanococcus jannaschii. The ORFs constitute fusions of the homologous P. furiosus genes encoding the α and β subunits. Two ORFs, AF1211 and AF1938, of A. fulgidus and ORF MJ0590 of M. jannaschii were cloned and functionally overexpressed in Escherichia coli. The purified recombinant proteins were characterized as distinctive isoenzymes of ACD with different substrate specificities. In contrast to the Pyrococcus ACD, the ACDs of Archaeoglobus and Methanococcus constitute homodimers of about 140 kDa composed of two identical 70-kDa subunits, which represent fusions of the homologous P. furiosus α and β subunits in an αβ (AF1211 and MJ0590) or βα (AF1938) orientation. The data indicate that A. fulgidus and M. jannaschii contains a novel type of ADP-forming acetyl-CoA synthetase in Archaea, in which the subunit polypeptides and their coding genes are fused.

scholarly journals The Mode of Cell Wall Growth in Selected Archaea Is Similar to the General Mode of Cell Wall Growth in Bacteria as Revealed by Fluorescent Dye Analysis

2010 ◽  
Vol 77 (5) ◽  
pp. 1556-1562 ◽  
Author(s):  
Reinhard Wirth ◽  
Annett Bellack ◽  
Markus Bertl ◽  
Yvonne Bilek ◽  
Thomas Heimerl ◽  
...  
Keyword(s):  
Cell Wall ◽  
Fluorescent Dyes ◽  
Pyrococcus Furiosus ◽  
Wall Material ◽  
Cell Wall Material ◽  
Cell Wall Growth ◽  
Archaeal Species ◽  
Dye Analysis ◽  
Wall Growth ◽  
Methanopyrus Kandleri

ABSTRACTThe surfaces of 8 bacterial and 23 archaeal species, including many hyperthermophilicArchaea, could be stained using succinimidyl esters of fluorescent dyes. This allowed us for the first time to analyze the mode of cell wall growth inArchaeaby subculturing stained cells. The data obtained show that incorporation of new cell wall material inArchaeafollows the pattern observed forBacteria: in the coccoid speciesPyrococcus furiosusincorporation was in the region of septum formation while for the rod-shaped speciesMethanopyrus kandleriandMethanothermus sociabilis, a diffuse incorporation of cell wall material over the cell length was observed. Cell surface appendages like fimbriae/pili, fibers, or flagella were detectable by fluorescence staining only in a very few cases although their presence was proven by electron microscopy. Our data in addition prove that Alexa Fluor dyes can be used forin situanalyses at temperatures up to 100°C.

scholarly journals Enzymatic reconstitution of ribosomal peptide backbone thioamidation

2018 ◽  
Vol 115 (12) ◽  
pp. 3030-3035 ◽  
Author(s):  
Nilkamal Mahanta ◽  
Andi Liu ◽  
Shihui Dong ◽  
Satish K. Nair ◽  
Douglas A. Mitchell
Keyword(s):  
Posttranslational Modifications ◽  
Active Site ◽  
Methanogenic Archaea ◽  
Methanosarcina Acetivorans ◽  
Binding Studies ◽  
Peptide Backbone ◽  
Α Subunit ◽  
Essential Enzyme ◽  
Methanopyrus Kandleri

Methyl-coenzyme M reductase (MCR) is an essential enzyme found strictly in methanogenic and methanotrophic archaea. MCR catalyzes a reversible reaction involved in the production and consumption of the potent greenhouse gas methane. The α-subunit of this enzyme (McrA) contains several unusual posttranslational modifications, including the only known naturally occurring example of protein thioamidation. We have recently demonstrated by genetic deletion and mass spectrometry that the tfuA and ycaO genes of Methanosarcina acetivorans are involved in thioamidation of Gly465 in the MCR active site. Modification to thioGly has been postulated to stabilize the active site structure of MCR. Herein, we report the in vitro reconstitution of ribosomal peptide thioamidation using heterologously expressed and purified YcaO and TfuA proteins from M. acetivorans. Like other reported YcaO proteins, this reaction is ATP-dependent but requires an external sulfide source. We also reconstitute the thioamidation activity of two TfuA-independent YcaOs from the hyperthermophilic methanogenic archaea Methanopyrus kandleri and Methanocaldococcus jannaschii. Using these proteins, we demonstrate the basis for substrate recognition and regioselectivity of thioamide formation based on extensive mutagenesis, biochemical, and binding studies. Finally, we report nucleotide-free and nucleotide-bound crystal structures for the YcaO proteins from M. kandleri. Sequence and structure-guided mutagenesis with subsequent biochemical evaluation have allowed us to assign roles for residues involved in thioamidation and confirm that the reaction proceeds via backbone O-phosphorylation. These data assign a new biochemical reaction to the YcaO superfamily and paves the way for further characterization of additional peptide backbone posttranslational modifications.

scholarly journals Earthworms and Fusarium oxysporum: effect on strawberry plant growth and production

2018 ◽  
Vol 39 (4) ◽  
pp. 1437
Author(s):  
Mario Gámiz Infante ◽  
Manuel Avilés Guerrero ◽  
Celia Borrero Vega ◽  
Wilian Carlo Demetrio ◽  
Jair Alves Dionísio
Keyword(s):  
Plant Growth ◽  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
Lumbricus Terrestris ◽  
Nutrient Content ◽  
Life Forms ◽  
Fruit Production ◽  
Positive Interactions ◽  
Soil Pathogens ◽  
Positive Effects

Earthworms are soil invertebrates that play an important environmental role and are often referred to as “ecosystem engineers”. These invertebrates can influence several organisms, from microscopic life forms to plants. Although many works had reported positive effects of earthworms on plant growth, studies combining these invertebrates and soil pathogens showed numerous positive interactions. Fusarium wilt is a global disease that can cause severe damage to strawberry fields. The aim of this study was to evaluate the effects of inoculation of earthworms (Lumbricus terrestris) and Fusarium wilt (Fusarium oxysporum f. sp. fragariae) in strawberry plants. This greenhouse experiment was carried out in the University of Seville School of Agricultural Engineering, Utrera City, Spain. Strawberries (Rooted cuttings) were planted in plastic pots and administered the following treatments: Control (absence of F. oxysporum f. sp. fragariae and earthworms), T1 (absence of F. oxysporum f. sp. fragariae, two L. terrestris per pot), T2 (inoculum of F. oxysporum f. sp. fragariae, absence of L. terrestris), and T3 (inoculum of F. oxysporum f. sp. fragariae and two L. terrestris). Weekly fruit production was measured for seven months. After this period the shoot fresh weight and the leaf nutrient content was measured. The results obtained showed no interaction between L. terrestris and F. oxysporum f. sp. fragariae on strawberry production. T1 treatment resulted in fruit production superior to other treatments, including the control. An absence of differences in dry shoot matter was observed with earthworm treatment, and small differences were found in the leaf nutrient content. The earthworm inoculation was unable to suppress the negative effects of Fusarium wilt in strawberry production. However, positive effects such as a reduction in the disease severity were found in the earthworm treated plants. In treatments without F. oxysporum f. sp. fragariae inoculation, the presence of earthworms increased plant productivity by 44.21 g per pot, compared with the control.

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