scholarly journals Diversity in yeast–mycelium dimorphism response of the Dutch elm disease pathogens: the inoculum size effect

2016 ◽  
Vol 62 (6) ◽  
pp. 525-529 ◽  
Author(s):  
Marie-Ève Wedge ◽  
Erika Sayuri Naruzawa ◽  
Martha Nigg ◽  
Louis Bernier
Keyword(s):  
Quorum Sensing ◽  
Size Effect ◽  
Inoculum Size ◽  
Dutch Elm Disease ◽  
Dimorphic Fungi ◽  
Ophiostoma Ulmi ◽  
Signalling Molecules ◽  
A Cell ◽  
Different Strains ◽  
External Stimuli

Dutch elm disease (DED) is caused by the dimorphic fungi Ophiostoma ulmi, Ophiostoma novo-ulmi, and Ophiostoma himal-ulmi. A cell population density-dependent phenomenon related to quorum sensing was previously shown to affect the reversible transition from yeast-like to mycelial growth in liquid shake cultures of O. novo-ulmi NRRL 6404. Since the response to external stimuli often varies among DED fungal strains, we evaluated the effect of inoculum size on 8 strains of the 3 species of DED agents by determining the proportion of yeast and mycelium produced at different spore inoculum concentrations in defined liquid shake medium. The results show that not all DED fungi strains respond similarly to inoculum size effect, since variations were observed among strains. It is thus possible that the different strains belonging to phylogenetically close species use different signalling molecules or molecular signalling pathways to regulate their growth mode via quorum-sensing mechanisms.

scholarly journals Inoculum Size Effect in Dimorphic Fungi: Extracellular Control of Yeast-Mycelium Dimorphism in Ceratocystis ulmi

2004 ◽  
Vol 70 (3) ◽  
pp. 1356-1359 ◽  
Author(s):  
Jacob M. Hornby ◽  
Sarah M. Jacobitz-Kizzier ◽  
Donna J. McNeel ◽  
Ellen C. Jensen ◽  
David S. Treves ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Size Effect ◽  
Organic Solvent ◽  
Inoculum Size ◽  
Dutch Elm Disease ◽  
Sulfur Source ◽  
Dimorphic Fungus ◽  
Promoting Effect ◽  
Dimorphic Fungi ◽  
Methyl Donors

ABSTRACT We studied the inoculum size effect in Ceratocystis ulmi, the dimorphic fungus that causes Dutch elm disease. In a defined glucose-proline-salts medium, cells develop as budding yeasts when inoculated at ≥106 spores per ml and as mycelia when inoculated at <106 spores per ml. The inoculum size effect was not influenced by inoculum spore type, age of the spores, temperature, pH, oxygen availability, trace metals, sulfur source, phosphorous source, or the concentration of glucose or proline. Similarly, it was not influenced by added adenosine, reducing agents, methyl donors, amino sugars, fatty acids, or carbon dioxide. Instead, growing cells excreted an unknown quorum-sensing factor that caused a morphological shift from mycelia to budding yeasts. This yeast-promoting effect is abolished if it is extracted with an organic solvent such as ethyl acetate. The quorum-sensing activity acquired by the organic solvent could be added back to fresh medium in a dose-dependent fashion. The quorum-sensing activity in C. ulmi spent medium was specific for C. ulmi and had no effect on the dimorphic fungus Candida albicans or the photomorphogenic fungus Penicillium isariaeforme. In addition, farnesol, the quorum-sensing molecule produced by C. albicans, did not inhibit mycelial development of C. ulmi when present at concentrations of up to 100 μM. We conclude that the inoculum size effect is a manifestation of a quorum-sensing system that is mediated by an excreted extracellular molecule, and we suggest that quorum sensing is a general phenomenon in dimorphic fungi.

scholarly journals Quorum sensing in Aliivibrio wodanis 06/09/139 and its role in controlling various phenotypic traits

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11980
Author(s):  
Amudha Deepalakshmi Maharajan ◽  
Hilde Hansen ◽  
Miriam Khider ◽  
Nils Peder Willassen
Keyword(s):  
Quorum Sensing ◽  
Protease Activity ◽  
Cell Communication ◽  
Homoserine Lactone ◽  
Phenotypic Traits ◽  
Signalling Molecules ◽  
A Cell ◽  
Cell Densities ◽  
Cell Culture Assay ◽  
Cytopathogenic Effect

Background Quorum Sensing (QS) is a cell-to-cell communication system that bacteria utilize to adapt to the external environment by synthesizing and responding to signalling molecules called autoinducers. The psychrotrophic bacterium Aliivibrio wodanis 06/09/139, originally isolated from a winter ulcer of a reared Atlantic salmon, produces the autoinducer N-3-hydroxy-decanoyl-homoserine-lactone (3OHC10-HSL) and encodes the QS systems AinS/R and LuxS/PQ, and the master regulator LitR. However, the role of QS in this bacterium has not been investigated yet. Results In the present work we show that 3OHC10-HSL production is cell density and temperature-dependent in A. wodanis 06/09/139 with the highest production occurring at a low temperature (6 °C). Gene inactivation demonstrates that AinS is responsible for 3OHC10-HSL production and positively regulated by LitR. Inactivation of ainS and litR further show that QS is involved in the regulation of growth, motility, hemolysis, protease activity and siderophore production. Of these QS regulated activities, only the protease activity was found to be independent of LitR. Lastly, supernatants harvested from the wild type and the ΔainS and ΔlitR mutants at high cell densities show that inactivation of QS leads to a decreased cytopathogenic effect (CPE) in a cell culture assay, and strongest attenuation of the CPE was observed with supernatants harvested from the ΔlitR mutant. Conclusion A. wodanis 06/09/139 use QS to regulate a number of activities that may prove important for host colonization or interactions. The temperature of 6 °C that is in the temperature range at which winter ulcer occurs, plays a role in AHL production and development of CPE on a Chinook Salmon Embryo (CHSE) cell line.

scholarly journals PapRIV, a BV-2 microglial cell activating quorum sensing peptide

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yorick Janssens ◽  
Nathan Debunne ◽  
Anton De Spiegeleer ◽  
Evelien Wynendaele ◽  
Marta Planas ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Cell Model ◽  
Dependent Manner ◽  
Communication Signals ◽  
Gram Positive Bacteria ◽  
A Cell ◽  
Gastro Intestinal Tract

AbstractQuorum sensing peptides (QSPs) are bacterial peptides produced by Gram-positive bacteria to communicate with their peers in a cell-density dependent manner. These peptides do not only act as interbacterial communication signals, but can also have effects on the host. Compelling evidence demonstrates the presence of a gut-brain axis and more specifically, the role of the gut microbiota in microglial functioning. The aim of this study is to investigate microglial activating properties of a selected QSP (PapRIV) which is produced by Bacillus cereus species. PapRIV showed in vitro activating properties of BV-2 microglia cells and was able to cross the in vitro Caco-2 cell model and reach the brain. In vivo peptide presence was also demonstrated in mouse plasma. The peptide caused induction of IL-6, TNFα and ROS expression and increased the fraction of ameboid BV-2 microglia cells in an NF-κB dependent manner. Different metabolites were identified in serum, of which the main metabolite still remained active. PapRIV is thus able to cross the gastro-intestinal tract and the blood–brain barrier and shows in vitro activating properties in BV-2 microglia cells, hereby indicating a potential role of this quorum sensing peptide in gut-brain interaction.

scholarly journals Quorum Sensing: a Transcriptional Regulatory System Involved in the Pathogenicity of Burkholderia mallei

2004 ◽  
Vol 72 (11) ◽  
pp. 6589-6596 ◽  
Author(s):  
Ricky L. Ulrich ◽  
David DeShazer ◽  
Harry B. Hines ◽  
Jeffrey A. Jeddeloh
Keyword(s):  
Quorum Sensing ◽  
Virulence Factor ◽  
Regulatory System ◽  
In Silico Analysis ◽  
Homoserine Lactone ◽  
Burkholderia Mallei ◽  
Wild Type ◽  
Transcriptional Regulatory ◽  
A Cell

ABSTRACT Numerous gram-negative bacterial pathogens regulate virulence factor expression by using a cell density mechanism termed quorum sensing (QS). An in silico analysis of the Burkholderia mallei ATCC 23344 genome revealed that it encodes at least two luxI and four luxR homologues. Using mass spectrometry, we showed that wild-type B. mallei produces the signaling molecules N-octanoyl-homoserine lactone and N-decanoyl-homoserine lactone. To determine if QS is involved in the virulence of B. mallei, we generated mutations in each putative luxIR homologue and tested the pathogenicities of the derivative strains in aerosol BALB/c mouse and intraperitoneal hamster models. Disruption of the B. mallei QS alleles, especially in RJ16 (bmaII) and RJ17 (bmaI3), which are luxI mutants, significantly reduced virulence, as indicated by the survival of mice who were aerosolized with 104 CFU (10 50% lethal doses [LD50s]). For the B. mallei transcriptional regulator mutants (luxR homologues), mutation of the bmaR5 allele resulted in the most pronounced decrease in virulence, with 100% of the challenged animals surviving a dose of 10 LD50s. Using a Syrian hamster intraperitoneal model of infection, we determined the LD50s for wild-type B. mallei and each QS mutant. An increase in the relative LD50 was found for RJ16 (bmaI1) (>967 CFU), RJ17 (bmaI3) (115 CFU), and RJ20 (bmaR5) (151 CFU) compared to wild-type B. mallei (<13 CFU). These findings demonstrate that B. mallei carries multiple luxIR homologues that either directly or indirectly regulate the biosynthesis of an essential virulence factor(s) that contributes to the pathogenicity of B. mallei in vivo.

scholarly journals Environmental modification via a quorum sensing molecule influences the social landscape of siderophore production

2017 ◽  
Vol 284 (1852) ◽  
pp. 20170200 ◽  
Author(s):  
Roman Popat ◽  
Freya Harrison ◽  
Ana C. da Silva ◽  
Scott A. S. Easton ◽  
Luke McNally ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Public Goods ◽  
Bacterial Species ◽  
Relative Fitness ◽  
Iron Starvation ◽  
Signal Molecule ◽  
Signalling Molecules ◽  
Signalling Molecule ◽  
The Impact ◽  
Social Trait

Bacteria produce a wide variety of exoproducts that favourably modify their environment and increase their fitness. These are often termed ‘public goods’ because they are costly for individuals to produce and can be exploited by non-producers (cheats). The outcome of conflict over public goods is dependent upon the prevailing environment and the phenotype of the individuals in competition. Many bacterial species use quorum sensing (QS) signalling molecules to regulate the production of public goods. QS, therefore, determines the cooperative phenotype of individuals, and influences conflict over public goods. In addition to their regulatory functions, many QS molecules have additional properties that directly modify the prevailing environment. This leads to the possibility that QS molecules could influence conflict over public goods indirectly through non-signalling effects, and the impact of this on social competition has not previously been explored. The Pseudomonas aeruginosa QS signal molecule PQS is a powerful chelator of iron which can cause an iron starvation response. Here, we show that PQS stimulates a concentration-dependent increase in the cooperative production of iron scavenging siderophores, resulting in an increase in the relative fitness of non-producing siderophore cheats. This is likely due to an increased cost of siderophore output by producing cells and a concurrent increase in the shared benefits, which accrue to both producers and cheats. Although PQS can be a beneficial signalling molecule for P. aeruginosa , our data suggest that it can also render a siderophore-producing population vulnerable to competition from cheating strains. More generally, our results indicate that the production of one social trait can indirectly affect the costs and benefits of another social trait.

Analytical electrofocusing and two-dimensional electrophoresis of proteins extracted from the mycelia of aggressive and nonaggressive strains of Ophiostoma ulmi

1986 ◽  
Vol 64 (9) ◽  
pp. 2073-2081 ◽  
Author(s):  
Robert S. Jeng
Keyword(s):  
Dutch Elm Disease ◽  
Two Dimensional ◽  
Polyacrylamide Gels ◽  
Ophiostoma Ulmi ◽  
Two Dimensional Electrophoresis ◽  
Coomassie Blue ◽  
Isoelectric Points ◽  
Additional Protein ◽  
Dimensional Electrophoresis ◽  
Electrophoresis Of Proteins

Soluble mycelial proteins from Ophiostoma ulmi (Buism.) Nannf., the causal agent of Dutch elm disease, were separated by analytical electrofocusing and two-dimensional electrophoresis in polyacrylamide gels. Results showed the aggressive and nonaggressive strains of this pathogen each had about 60 Coomassie blue stained bands having isoelectric points from 3 to 7. Both strains of this fungus had their own characteristic electrofocusing patterns. Nonaggressive isolate S116, for example, lacked two protein bands, one near the anode and one near the cathode, but it had five additional protein bands distributed from pH 4 to 6. Two-dimensional electrophoresis of total soluble proteins depicted that there were 36 proteins found to be specific for the nonaggressive isolate S116 and 12 proteins for the aggressive isolate RR2.

scholarly journals Controlled Construction of Stable Network Structure Composed of Honeycomb-Shaped Microhydrogels

Life ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 38 ◽  
Author(s):  
Masayuki Hayakawa ◽  
Satoshi Umeyama ◽  
Ken Nagai ◽  
Hiroaki Onoe ◽  
Masahiro Takinoue
Keyword(s):  
Cell Communication ◽  
Model Systems ◽  
Stable Component ◽  
Photosensitive Polymer ◽  
A Cell ◽  
External Stimuli ◽  
Structural Instabilities ◽  
Insight Into ◽  
Stable Network ◽  
Microfluidic Technique

Recently, the construction of models for multicellular systems such as tissues has been attracting great interest. These model systems are expected to reproduce a cell communication network and provide insight into complicated functions in living systems./Such network structures have mainly been modelled using a droplet and a vesicle. However, in the droplet and vesicle network, there are difficulties attributed to structural instabilities due to external stimuli and perturbations. Thus, the fabrication of a network composed of a stable component such as hydrogel is desired. In this article, the construction of a stable network composed of honeycomb-shaped microhydrogels is described. We produced the microhydrogel network using a centrifugal microfluidic technique and a photosensitive polymer. In the network, densely packed honeycomb-shaped microhydrogels were observed. Additionally, we successfully controlled the degree of packing of microhydrogels in the network by changing the centrifugal force. We believe that our stable network will contribute to the study of cell communication in multicellular systems.

F-actin as a functional target for retro-retinoids: a potential role in anhydroretinol-triggered cell death

1999 ◽  
Vol 112 (15) ◽  
pp. 2521-2528 ◽  
Author(s):  
I. Korichneva ◽  
U. Hammerling
Keyword(s):  
Cell Death ◽  
Early Event ◽  
Pattern Reversal ◽  
Cell Periphery ◽  
Growth And Survival ◽  
Signalling Molecules ◽  
Herbimycin A ◽  
Morphological Studies ◽  
A Cell ◽  
Survival Potential

The retro-retinoids, metabolites of vitamin A (retinol), belong to a family of lipophilic signalling molecules implicated in regulation of cell growth and survival. Growth-promoting properties have been ascribed to 14-hydroxy-retro-retinol (14HRR), while anhydroretinol (AR) was discovered to act as a natural antagonist triggering growth arrest and death by apoptosis. Based on morphological studies and inhibition of apoptosis by the kinase blocker, herbimycin A, it has been suggested that retro-retinoids exhibit their function in the cytosolic compartment. F-actin emerged as a functional target for retro-retinoid action. By FACS analysis and fluorescence microscopy of phalloidin-FITC labeled cells we demonstrated that F-actin reorganization was an early event in AR-triggered apoptosis. Fluorescence images of AR-treated fibroblasts displayed short, thick, stick-like and punctate structures, and membrane ruffles at the cell periphery along with an increased diffuse staining pattern. Reversal of the AR effect by 14HRR or retinol indicates that F-actin is a common site for regulation by retro-retinoids. Inhibition of both cell death and actin depolymerisation by bcl-2 implies that cytoskeleton reorganization is downstream of bcl-2-related processes. Furthermore, stabilization of microfilaments by jasplakinolide increased the survival potential of AR treated cells, while weakening the cytoskeleton by cytochalasin B abetted apoptosis. Thus the cytoskeleton is an important way station in a communication network that decides whether a cell should live or die.

Sign in / Sign up

Export Citation Format

Share Document