scholarly journals The typA Gene is Required for Stress Adaptation as Well as for Symbiosis of Sinorhizobium meliloti 1021 with Certain Medicago truncatula Lines

2004 ◽  
Vol 17 (3) ◽  
pp. 235-244 ◽  
Author(s):  
Ernö Kiss ◽  
Thierry Huguet ◽  
Véréna Poinsot ◽  
Jacques Batut
Keyword(s):  
Escherichia Coli ◽  
Low Temperature ◽  
Medicago Truncatula ◽  
Sinorhizobium Meliloti ◽  
Sodium Dodecyl ◽  
Low Ph ◽  
Stress Adaptation ◽  
Symbiotic Interaction ◽  
Wide Range ◽  
Cold Sensitive

In this article, we describe the typA gene of Sinorhizobium meliloti, the orthologue of typA/bipA genes found in a wide range of bacteria. We found that typA was required for survival of S. meliloti under certain stress conditions, such as growth at low temperature or low pH and in the presence of sodium dodecyl sulfate (SDS). The cold-sensitive phenotype of both Escherichia coli bipA and S. meliloti typA mutants were cross-complemented, indicating that the two genes are functionally equivalent. typA was indispensable for symbiosis on Medicago truncatula Jemalong and F83005.5 and contributes to the full efficiency of symbiosis on other host plant lines such as DZA315.16 or several cultivars of M. sativa. Hence, the symbiotic requirement for typA is host dependent. Interestingly, the symbiotic defect was different on Jemalong and F83005.5 plants, thus indicating that typA is required at a different stage of the symbiotic interaction.

scholarly journals Expression of Medicago truncatula Genes Responsive to Nitric Oxide in Pathogenic and Symbiotic Conditions

2008 ◽  
Vol 21 (6) ◽  
pp. 781-790 ◽  
Author(s):  
Alberto Ferrarini ◽  
Matteo De Stefano ◽  
Emmanuel Baudouin ◽  
Chiara Pucciariello ◽  
Annalisa Polverari ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Medicago Truncatula ◽  
Regulatory Networks ◽  
Sinorhizobium Meliloti ◽  
Biotic Interactions ◽  
Hypersensitive Reaction ◽  
Nodule Formation ◽  
Polymorphism Analysis ◽  
Symbiotic Interaction ◽  
Physiological Relevance

Nitric oxide (NO) is involved in diverse physiological processes in plants, including growth, development, response to pathogens, and interactions with beneficial microorganisms. In this work, a dedicated microarray representing the widest database available of NO-related transcripts in plants has been produced with 999 genes identified by a cDNA amplified fragment length polymorphism analysis as modulated in Medicago truncatula roots treated with two NO donors. The microarray then was used to monitor the expression of NO-responsive genes in M. truncatula during the incompatible interaction with the foliar pathogen Colletotrichum trifolii race 1 and during the symbiotic interaction with Sinorhizobium meliloti 1021. A wide modulation of NO-related genes has been detected during the hypersensitive reaction or during nodule formation and is discussed with special emphasis on the physiological relevance of these genes in the context of the two biotic interactions. This work clearly shows that NO-responsive genes behave differently depending on the plant organ and on the type of interaction, strengthening the need to consider regulatory networks, including different signaling molecules.

scholarly journals The Medicago truncatula N5 Gene Encoding a Root-Specific Lipid Transfer Protein Is Required for the Symbiotic Interaction with Sinorhizobium meliloti

2009 ◽  
Vol 22 (12) ◽  
pp. 1577-1587 ◽  
Author(s):  
Youry Pii ◽  
Alessandra Astegno ◽  
Elisa Peroni ◽  
Massimo Zaccardelli ◽  
Tiziana Pandolfini ◽  
...  
Keyword(s):  
Medicago Truncatula ◽  
Sinorhizobium Meliloti ◽  
Lipid Transfer Protein ◽  
Symbiotic Association ◽  
Lipid Transfer ◽  
Symbiotic Interaction ◽  
Transgenic Roots ◽  
Transfer Protein ◽  
Small Proteins

The Medicago truncatula N5 gene is induced in roots after Sinorhizobium meliloti infection and it codes for a putative lipid transfer protein (LTP), a family of plant small proteins capable of binding and transferring lipids between membranes in vitro. Various biological roles for plant LTP in vivo have been proposed, including defense against pathogens and modulation of plant development. The aim of this study was to shed light on the role of MtN5 in the symbiotic interaction between M. truncatula and S. meliloti. MtN5 cDNA was cloned and the mature MtN5 protein expressed in Escherichia coli. The lipid binding capacity and antimicrobial activity of the recombinant MtN5 protein were tested in vitro. MtN5 showed the capacity to bind lysophospholipids and to inhibit M. truncatula pathogens and symbiont growth in vitro. Furthermore, MtN5 was upregulated in roots after infection with either the fungal pathogen Fusarium semitectum or the symbiont S. meliloti. Upon S. meliloti infection, MtN5 was induced starting from 1 day after inoculation (dpi). It reached the highest concentration at 3 dpi and it was localized in the mature nodules. MtN5-silenced roots were impaired in nodulation, showing a 50% of reduction in the number of nodules compared with control roots. On the other hand, transgenic roots overexpressing MtN5 developed threefold more nodules with respect to control roots. Here, we demonstrate that MtN5 possesses biochemical features typical of LTP and that it is required for the successful symbiotic association between M. truncatula and S. meliloti.

An Assessment of Escherichia coli O157:H7 Contamination Risks in Commercial Mayonnaise from Pasteurized Eggs and Environmental Sources, and Behavior in Low-pH Dressings

1995 ◽  
Vol 58 (10) ◽  
pp. 1059-1064 ◽  
Author(s):  
JOHN P. ERICKSON ◽  
JOSEPH W. STAMER ◽  
MARANDA HAYES ◽  
DENISE N. MCKENNA ◽  
LESLIE A. VAN ALSTINE
Keyword(s):  
Escherichia Coli ◽  
Health Hazard ◽  
Food Service ◽  
Low Ph ◽  
Escherichia Coli O157 ◽  
Contamination Sources ◽  
Wide Range ◽  
Processing Plants ◽  
Contamination Levels ◽  
Food Service Workers

An enterohemorrhaghic Escherichia coli O157:H7 (EHEC) outbreak in 1993 was epidemioiogically linked to commercial real mayonnaise. This study evaluated EHEC contamination risk during commercial mayonnaise and mayonnaise dressing production, and EHEC behavior in low-pH dressings. Two potential contamination sources, pasteurized liquid eggs and wet environmental areas, were surveyed for 4 months in three processing plants. One hundred eighty-eight egg lots and 114 environmental swabs were collected and analyzed for EHEC by enrichment and direct plating methods. All plant samples were EHEC negative. Commercial mayonnaise plants which use pasteurized eggs and employ effective good manufacturing practices (GMP) sanitation programs are unlikely EHEC harborage and contamination sources. Five commercial real-mayonnaise-based and reduced-calorie and/or fat mayonnaise dressings were inoculated with ≥6 log10 colony-forming units (CFU)/g EHEC contamination levels and stored at 25°C. The products contained a wide range of acetic acid, NaCl, and preservative levels, while pH varied from 3.21 to 3.94. Products below pH 3.6 rapidly inactivated EHEC, producing ≥7 log10 CFU/g decreases in ≤1 to ≤3 days. High EHEC lethality was also observed in the pH 3.94, egg white-mayonnaise dressing. Intact packages of commercial mayonnaise and mayonnaise dressings pose negligible EHEC contamination and health hazard risks. As with any food, consumers and food-service workers must use stringent hygienic practices to prevent microbial pathogen contamination during preparation, handling, and storage of mayonnaise-ingredient recipes such as chilled perishable salads and salad bar dressings.

scholarly journals Expression Dynamics of the Medicago truncatula Transcriptome during the Symbiotic Interaction with Sinorhizobium meliloti: Which Role for Nitric Oxide?

2012 ◽  
Vol 161 (1) ◽  
pp. 425-439 ◽  
Author(s):  
Alexandre Boscari ◽  
Jennifer del Giudice ◽  
Alberto Ferrarini ◽  
Luca Venturini ◽  
Anne-Lise Zaffini ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Medicago Truncatula ◽  
Sinorhizobium Meliloti ◽  
Symbiotic Interaction

scholarly journals Identification of New Potential Regulators of the Medicago truncatula—Sinorhizobium meliloti Symbiosis Using a Large-Scale Suppression Subtractive Hybridization Approach

2007 ◽  
Vol 20 (3) ◽  
pp. 321-332 ◽  
Author(s):  
Laurence Godiard ◽  
Andreas Niebel ◽  
Fabienne Micheli ◽  
Jérôme Gouzy ◽  
Thomas Ott ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Suppression Subtractive Hybridization ◽  
Medicago Truncatula ◽  
Large Scale ◽  
Sinorhizobium Meliloti ◽  
Zinc Finger Protein ◽  
Gene Clusters ◽  
Subtractive Hybridization ◽  
Symbiotic Interaction ◽  
Genes Encoding

We set up a large-scale suppression subtractive hybridization (SSH) approach to identify Medicago truncatula genes differentially expressed at different stages of the symbiotic interaction with Sinorhizobium meliloti, with a particular interest for regulatory genes. We constructed 7 SSH libraries covering successive stages from Nod factor signal transduction to S. meliloti infection, nodule organogenesis, and functioning. Over 26,000 clones were differentially screened by two rounds of macroarray hybridizations. In all, 3,340 clones, corresponding to genes whose expression was potentially affected, were selected, sequenced, and ordered into 2,107 tentative gene clusters, including 767 MtS clusters corresponding to new M. truncatula genes. In total, 52 genes encoding potential regulatory proteins, including transcription factors (TFs) and other elements of signal transduction cascades, were identified. The expression pattern of some of them was analyzed by quantitative reverse-transcription polymerase chain reaction in wild-type and in Nod¯ M. truncatula mutants blocked before or after S. meliloti infection. Three genes, coding for TFs of the bHLH and WRKY families and a C2H2 zinc-finger protein, respectively, were found to be upregulated, following S. meliloti inoculation, in the infection-defective mutant lin, whereas the bHLH gene also was expressed in the root-hair-curling mutant hcl. The potential role of these genes in early symbiotic steps is discussed.

scholarly journals (Homo)glutathione Depletion Modulates Host Gene Expression during the Symbiotic Interaction between Medicago truncatula and Sinorhizobium meliloti

2009 ◽  
Vol 151 (3) ◽  
pp. 1186-1196 ◽  
Author(s):  
Chiara Pucciariello ◽  
Gilles Innocenti ◽  
Willem Van de Velde ◽  
Annie Lambert ◽  
Julie Hopkins ◽  
...  
Keyword(s):  
Gene Expression ◽  
Medicago Truncatula ◽  
Sinorhizobium Meliloti ◽  
Host Gene ◽  
Glutathione Depletion ◽  
Host Gene Expression ◽  
Symbiotic Interaction

scholarly journals Impact of Membrane Phospholipid Alterations in Escherichia coli on Cellular Function and Bacterial Stress Adaptation

2017 ◽  
Vol 199 (13) ◽  
Author(s):  
Veronica W. Rowlett ◽  
Venkata K. P. S. Mallampalli ◽  
Anja Karlstaedt ◽  
William Dowhan ◽  
Heinrich Taegtmeyer ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Environmental Conditions ◽  
Environmental Stresses ◽  
Membrane Phospholipid ◽  
Stress Adaptation ◽  
Cell Physiology ◽  
Membrane Phospholipids ◽  
Content Type ◽  
Bacterial Physiology ◽  
Wide Range

ABSTRACT Bacteria have evolved multiple strategies to sense and rapidly adapt to challenging and ever-changing environmental conditions. The ability to alter membrane lipid composition, a key component of the cellular envelope, is crucial for bacterial survival and adaptation in response to environmental stress. However, the precise roles played by membrane phospholipids in bacterial physiology and stress adaptation are not fully elucidated. The goal of this study was to define the role of membrane phospholipids in adaptation to stress and maintenance of bacterial cell fitness. By using genetically modified strains in which the membrane phospholipid composition can be systematically manipulated, we show that alterations in major Escherichia coli phospholipids transform these cells globally. We found that alterations in phospholipids impair the cellular envelope structure and function, the ability to form biofilms, and bacterial fitness and cause phospholipid-dependent susceptibility to environmental stresses. This study provides an unprecedented view of the structural, signaling, and metabolic pathways in which bacterial phospholipids participate, allowing the design of new approaches in the investigation of lipid-dependent processes involved in bacterial physiology and adaptation. IMPORTANCE In order to cope with and adapt to a wide range of environmental conditions, bacteria have to sense and quickly respond to fluctuating conditions. In this study, we investigated the effects of systematic and controlled alterations in bacterial phospholipids on cell shape, physiology, and stress adaptation. We provide new evidence that alterations of specific phospholipids in Escherichia coli have detrimental effects on cellular shape, envelope integrity, and cell physiology that impair biofilm formation, cellular envelope remodeling, and adaptability to environmental stresses. These findings hold promise for future antibacterial therapies that target bacterial lipid biosynthesis.

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