scholarly journals Pectobacterium brasiliense 1692 Chemotactic Responses and the Role of Methyl-Accepting Chemotactic Proteins in Ecological Fitness

2021 ◽  
Vol 12 ◽  
Author(s):  
Collins Kipngetich Tanui ◽  
Divine Yutefar Shyntum ◽  
Precious K. Sedibane ◽  
Daniel Bellieny-Rabelo ◽  
Lucy N. Moleleki
Keyword(s):  
Potato Tuber ◽  
Functional Characterization ◽  
Soft Rot ◽  
The Other ◽  
Differentially Expressed ◽  
Ecological Fitness ◽  
Swimming Motility ◽  
Tuber Infection ◽  
Mutant Strains

To adapt to changing environmental niches, bacteria require taxis, a movement toward or away from a stimulus (ligand). Chemotaxis has been studied in some members of the Soft Rot Pectobacteriaceae (SRP), particularly members of the genus Dickeya. On the contrary, there are fewer studies on this topic for the other genus in the SRP group, namely Pectobacterium. This study evaluated chemotactic responses in Pectobacterium brasiliense (Pb 1692) to various ligands. A total of 34 methyl-accepting chemotactic proteins (MCPs) were identified in the Pb 1692 genome and the domain architectures of these MCPs were determined. Four Pb 1692 MCPs previously shown to be differentially expressed during potato tuber infection were selected for further functional characterization. Toward this end, Pb 1692 mutant strains each lacking either AED-0001492, AED-0003671, AED-0000304, or AED-0000744 were generated. Two of these mutants (AED-0001492 and AED-0003671), were attenuated in their ability to grow and respond to citrate and are thus referred to as MCPcit2 and MCPcit1, respectively, while the other two, AED-0000304 (MCPxyl) and AED-0000744 (MCPasp), were affected in their ability to respond to xylose and aspartate, respectively. Trans-complementation of the mutant strains restored swimming motility in the presence of respective ligands. The four MCP mutants were not affected in virulence but were significantly attenuated in their ability to attach to potato leaves suggesting that ecological fitness is an important contribution of these MCPs toward Pb 1692 biology.

scholarly journals Functional characterization of SARS-CoV-2 infection suggests a complex inflammatory response and metabolic alterations

2020 ◽  
Author(s):  
Lucía Trilla-Fuertes ◽  
Ricardo Ramos ◽  
Natalia Blanca-López ◽  
Elena López-Camacho ◽  
Laura Martín-Pedraza ◽  
...  
Keyword(s):  
Inflammatory Response ◽  
Functional Characterization ◽  
Self Regulation ◽  
Transcriptional Response ◽  
The Other ◽  
Differentially Expressed ◽  
Node Activity ◽  
Cytokines And Chemokines ◽  
Variable Genes

AbstractCovid-19, caused by the SARS-CoV-2 virus, has reached the category of a worldwide pandemic. Even though intensive efforts, no effective treatments or a vaccine are available. Molecular characterization of the transcriptional response in Covid-19 patients could be helpful to identify therapeutic targets. In this study, RNAseq data from peripheral blood mononuclear cell samples from Covid-19 patients and healthy controls was analyzed from a functional point of view using probabilistic graphical models. Two networks were built: one based on genes differentially expressed between healthy and infected individuals and another one based on the 2,000 most variable genes in terms of expression in order to make a functional characterization. In the network based on differentially expressed genes, two inflammatory response nodes with different tendencies were identified, one related to cytokines and chemokines, and another one related to bacterial infections. In addition, differences in metabolism, which were studied in depth using Flux Balance Analysis, were identified. SARS-CoV2-infection caused alterations in glutamate, methionine and cysteine, and tetrahydrobiopterin metabolism. In the network based on 2,000 most variable genes, also two inflammatory nodes with different tendencies between healthy individuals and patients were identified. Similar to the other network, one was related to cytokines and chemokines. However, the other one, lower in Covid-19 patients, was related to allergic processes and self-regulation of the immune response. Also, we identified a decrease in T cell node activity and an increase in cell division node activity. In the current absence of treatments for these patients, functional characterization of the transcriptional response to SARS-CoV-2 infection could be helpful to define targetable processes. Therefore, these results may be relevant to propose new treatments.

The role of phenols in potato tuber resistance against soft rot byErwinia carotovora ssp.carotovora

1991 ◽  
Vol 34 (1) ◽  
pp. 9-16 ◽  
Author(s):  
Arun Kumar ◽  
V. S. Pundhir ◽  
K. C. Gupta
Keyword(s):  
Potato Tuber ◽  
Soft Rot ◽  
Tuber Resistance

scholarly journals Identification and Functional Characterization of a Xenorhabdus nematophila Oligopeptide Permease

2004 ◽  
Vol 70 (9) ◽  
pp. 5621-5627 ◽  
Author(s):  
Samantha S. Orchard ◽  
Heidi Goodrich-Blair
Keyword(s):  
Functional Characterization ◽  
Xenorhabdus Nematophila ◽  
Nutrient Source ◽  
Host Interactions ◽  
Laboratory Medium ◽  
Mutant Strains ◽  
Oligopeptide Permease ◽  
Encoding Genes

ABSTRACT The bacterium Xenorhabdus nematophila is a mutualist of Steinernema carpocapsae nematodes and a pathogen of insects. Presently, it is not known what nutrients the bacterium uses to thrive in these host environments. In other symbiotic bacteria, oligopeptide permeases have been shown to be important in host interactions, and we therefore sought to determine if oligopeptide uptake is essential for growth or symbiotic functions of X. nematophila in laboratory or host environments. We identified an X. nematophila oligopeptide permease (opp) operon of two sequential oppA genes, predicted to encode oligopeptide-binding proteins, and putative permease-encoding genes oppB, oppC, oppD, and oppF. Peptide-feeding studies indicated that this opp operon encodes a functional oligopeptide permease. We constructed strains with mutations in oppA 1, oppA 2, or oppB and examined the ability of each mutant strain to grow in a peptide-rich laboratory medium and to interact with the two hosts. We found that the opp mutant strains had altered growth phenotypes in the laboratory medium and in hemolymph isolated from larval insects. However, the opp mutant strains were capable of initiating and maintaining both mutualistic and pathogenic host interactions. These data demonstrate that the opp genes allow X. nematophila to utilize peptides as a nutrient source but that this function is not essential for the existence of X. nematophila in either of its host niches. To our knowledge, this study represents the first experimental analysis of the role of oligopeptide transport in mediating a mutualistic invertebrate-bacterium interaction.

Role of motility and chemotaxis in the pathogenesis of Dickeya dadantii 3937 (ex Erwinia chrysanthemi 3937)

Microbiology ◽  
2009 ◽  
Vol 155 (2) ◽  
pp. 434-442 ◽  
Author(s):  
María Antúnez-Lamas ◽  
Ezequiel Cabrera-Ordóñez ◽  
Emilia López-Solanilla ◽  
Rosa Raposo ◽  
Oswaldo Trelles-Salazar ◽  
...  
Keyword(s):  
Culture Media ◽  
Soft Rot ◽  
Erwinia Chrysanthemi ◽  
Flagellar Motor ◽  
Wild Type ◽  
Dickeya Dadantii ◽  
Pectolytic Enzymes ◽  
Virulence Assay ◽  
Mutant Strains

Dickeya dadantii 3937 (ex Erwinia chrysanthemi), a member of the Enterobacteriaceae, causes soft rot in many economically important crops. A successful pathogen has to reach the interior of the plant in order to cause disease. To study the role of motility and chemotaxis in the pathogenicity of D. dadantii 3937, genes involved in the chemotactic signal transduction system (cheW, cheB, cheY and cheZ) and in the structure of the flagellar motor (motA) were mutagenized. All the mutant strains grew like the wild-type in culture media, and the production and secretion of pectolytic enzymes was not affected. As expected, the swimming ability of the mutant strains was reduced with respect to the wild-type: motA (94 %), cheY (80 %), cheW (74 %), cheB (54 %) and cheZ (48 %). The virulence of the mutant strains was analysed in chicory, Saintpaulia and potato. The mutant strains were also tested for their capability to enter into Arabidopsis leaves. All the mutants showed a significant decrease of virulence in certain hosts; however, the degree of virulence reduction varied depending on the virulence assay. The ability to penetrate Arabidopsis leaves was impaired in all the mutants, whereas the capacity to colonize potato tubers after artificial inoculation was affected in only two mutant strains. In general, the virulence of the mutants could be ranked as motA<cheY<cheB=cheW<cheZ, which correlated with the degree to which swimming was affected. These results clearly indicate that motility plays an important role in the pathogenicity of this bacterium.

scholarly journals gerR, a Novel ger Operon Involved in l-Alanine- and Inosine-Initiated Germination of Bacillus cereus ATCC 14579

2005 ◽  
Vol 71 (2) ◽  
pp. 774-781 ◽  
Author(s):  
Luc M. Hornstra ◽  
Ynte P. de Vries ◽  
Willem M. de Vos ◽  
Tjakko Abee ◽  
Marjon H. J. Wells-Bennik
Keyword(s):  
High Pressure ◽  
Bacillus Cereus ◽  
Parental Strain ◽  
Essential Role ◽  
Insertional Mutagenesis ◽  
The Other ◽  
Receptor Complex ◽  
Germination Response ◽  
Mutant Strains

ABSTRACT Bacillus cereus endospores germinate in response to particular nutrients. Spores are able to sense these nutrients in the environment by receptors encoded by the gerA family of operons. Analysis of the Bacillus cereus ATCC 14579 genome revealed seven gerA family homologues. Using a transposon Tn917-based insertional mutagenesis approach followed by an enrichment procedure to select for l-alanine-induced germination mutants, we isolated a mutant with a defect in the l-alanine germination pathway. The transposon disrupted the last gene of a tricistronic gerA family operon, designated gerR, with the order gerRA, gerRC, gerRB. A second mutant was created by insertion of pMUTIN4 in gerRC. Both mutants showed the same phenotype for nutrient-induced germination. Spores of the gerR mutant strains were blocked in their l-alanine-initiated germination pathway and showed a delayed inosine-induced germination response. Apparently, germination mediated by l-alanine and inosine cannot be compensated for completely by the other germinant receptors, and this points towards an essential role of the gerR-encoded receptor in the receptor complex. In food products, spores of the mutant strains showed a reduced germination response compared to spores of the parental strain. High-pressure-initiated germination was not affected by the gerR mutations, as experiments with 100 and 550 MPa showed no difference with spores of the parental strain.

scholarly journals Role of Ttca of Citrobacter Werkmanii in Bacterial Growth, Biocides Resistance, Biofilm Formation and Swimming Motility

2018 ◽  
Vol 19 (9) ◽  
pp. 2644
Author(s):  
Gang Zhou ◽  
Ying-Si Wang ◽  
Hong Peng ◽  
Xiao-Mo Huang ◽  
Xiao-Bao Xie ◽  
...  
Keyword(s):  
Growth Rate ◽  
Homologous Recombination ◽  
Biofilm Formation ◽  
The Other ◽  
Swimming Motility ◽  
Tn5 Transposon ◽  
Phenotypic Changes ◽  
Resistant Strains ◽  
First Time

To screen, identify and study the genes involved in isothiazolone resistance and biofilm formation in Citrobacter werkmanii strain BF-6. A Tn5 transposon library of approximately 900 mutants of C. werkmanii strain BF-6 was generated and screened to isolate 1,2-benzisothiazolin-3-one (BIT) resistant strains. In addition, the tRNA 2-thiocytidine (32) synthetase gene (ttcA) was deleted through homologous recombination and the resulting phenotypic changes of the ΔttcA mutant were studied. A total of 3 genes were successfully identified, among which ΔttcA mutant exhibited a reduction in growth rate and swimming motility. On the other hand, an increase in biofilms formation in ΔttcA were observed but not with a significant resistance enhancement to BIT. This work, for the first time, highlights the role of ttcA gene of C. werkmanii strain BF-6 in BIT resistance and biofilm formation.

Plasma Levels of Protein S, Protein C, and Factor X: Effects of Sex, Hormonal State and Age

1995 ◽  
Vol 74 (05) ◽  
pp. 1271-1275 ◽  
Author(s):  
C M A Henkens ◽  
V J J Bom ◽  
W van der Schaaf ◽  
P M Pelsma ◽  
C Th Smit Sibinga ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Postmenopausal Women ◽  
Protein C ◽  
Blood Donors ◽  
Premenopausal Women ◽  
Protein S ◽  
The Other ◽  
Factor X ◽  
Normal Ranges

SummaryWe measured total and free protein S (PS), protein C (PC) and factor X (FX) in 393 healthy blood donors to assess differences in relation to sex, hormonal state and age. All measured proteins were lower in women as compared to men, as were levels in premenopausal women as compared to postmenopausal women. Multiple regression analysis showed that both age and subgroup (men, pre- and postmenopausal women) were of significance for the levels of total and free PS and PC, the subgroup effect being caused by the differences between the premenopausal women and the other groups. This indicates a role of sex-hormones, most likely estrogens, in the regulation of levels of pro- and anticoagulant factors under physiologic conditions. These differences should be taken into account in daily clinical practice and may necessitate different normal ranges for men, pre- and postmenopausal women.

On the role of the dispute between "non-possessors" and "Josephites" in the culture of Moscow's prediction

1998 ◽  
pp. 61-62
Author(s):  
N. S. Jurtueva
Keyword(s):  
The Other ◽  
Moral Transformation ◽  
15Th Century ◽  
The Future ◽  
Secular Power

In the XIV century. centripetal tendencies began to appear in the Moscow principality. Inside the Russian church, several areas were distinguished. Part of the clergy supported the specificobar form. The other understood the need for transformations in society. As a result, this led to a split in the Russian church in the 15th century for "non-possessors" and "Josephites". The former linked the fate of the future with the ideology of hesychasm and its moral transformation, while the latter sought support in alliance with a strong secular power.

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