scholarly journals Exopolysaccharide Production in Response to Medium Acidification Is Correlated With an Increase in Competition for Nodule Occupancy

2014 ◽  
Vol 27 (12) ◽  
pp. 1307-1317 ◽  
Author(s):  
Barney A. Geddes ◽  
Juan E. González ◽  
Ivan J. Oresnik
Keyword(s):  
Growth Medium ◽  
Root Hair ◽  
Sinorhizobium Meliloti ◽  
Fluorescent Microscopy ◽  
Low Molecular Weight ◽  
Nodule Occupancy ◽  
Expression Of Genes ◽  
Infected Root ◽  
Acidic Compartment ◽  
Root Hair Cells

Sinorhizobium meliloti strains unable to utilize galactose as a sole carbon source, due to mutations in the De-Ley Doudoroff pathway (dgoK), were previously shown to be more competitive for nodule occupancy. In this work, we show that strains carrying this mutation have galactose-dependent exopolysaccharide (EPS) phenotypes that were manifested as aberrant Calcofluor staining as well as decreased mucoidy when in an expR+ genetic background. The aberrant Calcofluor staining was correlated with changes in the pH of the growth medium. Strains carrying dgoK mutations were subsequently demonstrated to show earlier acidification of their growth medium that was correlated with an increase expression of genes associated with succinoglycan biosynthesis as well as increased accumulation of high and low molecular weight EPS in the medium. In addition, it was shown that the acidification of the medium was dependent on the inability of S. meliloti strains to initiate the catabolism of galactose. To more fully understand why strains carrying the dgoK allele were more competitive for nodule occupancy, early nodulation phenotypes were investigated. It was found that strains carrying the dgoK allele had a faster rate of nodulation. In addition, nodule competition experiments using genetic backgrounds unable to synthesize either succinoglycan or EPSII were consistent with the hypothesis that the increased competition phenotype was dependent upon the synthesis of succinoglycan. Fluorescent microscopy experiments on infected root-hair cells, using the acidotropic dye Lysotracker Red DND-99, provide evidence that the colonized curled root hair is an acidic compartment.

scholarly journals Succinoglycan Production Contributes to Acidic pH Tolerance in Sinorhizobium meliloti Rm1021

2017 ◽  
Vol 30 (12) ◽  
pp. 1009-1019 ◽  
Author(s):  
Justin P. Hawkins ◽  
Barney A. Geddes ◽  
Ivan J. Oresnik
Keyword(s):  
Molecular Weight ◽  
Sinorhizobium Meliloti ◽  
Degree Of Polymerization ◽  
Low Ph ◽  
Nodule Development ◽  
Low Molecular Weight ◽  
Nodule Occupancy ◽  
Acidic Ph ◽  
Ph Tolerance ◽  
Genes Encoding

In this work, the hypothesis that exopolysaccharide plays a role in the survival of Sinorhizobium meliloti at low pH levels is addressed. When S. meliloti was grown at pH 5.75, synthesis of succinoglycan increased, whereas synthesis of galactoglucan decreased. Succinoglycan that was isolated from cultures grown at low pH had a lower degree of polymerization relative to that which was isolated from cultures grown at neutral pH, suggesting that low–molecular weight (LMW) succinoglycan might play a role in adaptation to low pH. Mutants unable to produce succinoglycan or only able to produce high–molecular weight polysaccharide were found to be sensitive to low pH. However, strains unable to produce LMW polysaccharide were 10-fold more sensitive. In response to low pH, transcription of genes encoding proteins for succinoglycan, glycogen, and cyclic β(1-2) glucans biosynthesis increased, while those encoding proteins necessary for the biosynthesis of galactoglucan decreased. While changes in pH did not affect the production of glycogen or cyclic β(1-2) glucan, it was found that the inability to produce cyclic β(1-2) glucan did contribute to pH tolerance in the absence of succinoglycan. Finally, in addition to being sensitive to low pH, a strain carrying mutations in exoK and exsH, which encode the glycanases responsible for the cleavage of succinoglycan to LMW succinoglycan, exhibited a delay in nodulation and was uncompetitive for nodule occupancy. Taken together, the data suggest that the role for LMW succinoglycan in nodule development may be to enhance survival in the colonized curled root hair.

Local Positive Feedback Regulation Determines Cell Shape in Root Hair Cells

Science ◽  
2008 ◽  
Vol 319 (5867) ◽  
pp. 1241-1244 ◽  
Author(s):  
S. Takeda ◽  
C. Gapper ◽  
H. Kaya ◽  
E. Bell ◽  
K. Kuchitsu ◽  
...  
Keyword(s):  
Hair Cells ◽  
Positive Feedback ◽  
Root Hair ◽  
Cell Shape ◽  
Feedback Regulation ◽  
Root Hair Cells

scholarly journals Mutation in the ntrR Gene, a Member of the vap Gene Family, Increases the Symbiotic Efficiency of Sinorhizobium meliloti

2001 ◽  
Vol 14 (7) ◽  
pp. 887-894 ◽  
Author(s):  
Boglárka Oláh ◽  
Erno Kiss ◽  
Zoltán Györgypál ◽  
Judit Borzi ◽  
Gyöngyi Cinege ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Pathogenic Bacteria ◽  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Nifh Gene ◽  
Dry Weight ◽  
Nodule Occupancy ◽  
Gene Encoding ◽  
Symbiotic Efficiency ◽  
Host Interactions

In specific plant organs, namely the root nodules of alfalfa, fixed nitrogen (ammonia) produced by the symbiotic partner Sinorhizobium meliloti supports the growth of the host plant in nitrogen-depleted environment. Here, we report that a derivative of S. meliloti carrying a mutation in the chromosomal ntrR gene induced nodules with enhanced nitrogen fixation capacity, resulting in an increased dry weight and nitrogen content of alfalfa. The efficient nitrogen fixation is a result of the higher expression level of the nifH gene, encoding one of the subunits of the nitrogenase enzyme, and nifA, the transcriptional regulator of the nif operon. The ntrR gene, controlled negatively by its own product and positively by the symbiotic regulator syrM, is expressed in the same zone of nodules as the nif genes. As a result of the nitrogen-tolerant phenotype of the strain, the beneficial effect of the mutation on efficiency is not abolished in the presence of the exogenous nitrogen source. The ntrR mutant is highly competitive in nodule occupancy compared with the wild-type strain. Sequence analysis of the mutant region revealed a new cluster of genes, termed the “ntrPR operon,” which is highly homologous to a group of vap-related genes of various pathogenic bacteria that are presumably implicated in bacterium-host interactions. On the basis of its favorable properties, the strain is a good candidate for future agricultural utilization.

scholarly journals Low-Molecular-Weight Polyethyleneimine Grafted Polythiophene for Efficient siRNA Delivery

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Pan He ◽  
Kyoji Hagiwara ◽  
Hui Chong ◽  
Hsiao-hua Yu ◽  
Yoshihiro Ito
Keyword(s):  
Molecular Weight ◽  
Sirna Delivery ◽  
Fluorescent Microscopy ◽  
Molar Ratio ◽  
Low Molecular Weight ◽  
Label Free ◽  
Endosomal Membrane ◽  
Cationic Copolymers ◽  
Interfering Rna

Owing to its hydrophilicity, negative charge, small size, and labile degradation by endogenous nucleases, small interfering RNA (siRNA) delivery must be achieved by a carrier system. In this study, cationic copolymers composed of low-molecular-weight polyethylenimine and polythiophenes were synthesized and evaluated as novel self-tracking siRNA delivery vectors. The concept underlying the design of these copolymers is that hydrophobicity and rigidity of polythiophenes should enhance the transport of siRNA across the cell membrane and endosomal membrane. A gel retardation assay showed that the nanosized complexes formed between the copolymers and siRNA were stable even at a molar ratio of 1 : 2. The high cellular uptake (>80%) and localization of the copolymer vectors inside the cells were easily analyzed by tracking the fluorescence of polythiophene using fluorescent microscopy and cytometry. Anin vitroluciferase knockdown (KD) assay in A549-luc cells demonstrated that the siRNA complexes with more hydrophobic copolymers achieved a higher KD efficiency of 52.8% without notable cytotoxicity, indicating protein-specific KD activity rather than solely the cytotoxicity of the materials. Our polythiophene copolymers should serve as novel, efficient, low cell toxicity, and label-free siRNA delivery systems.

The role of plant villin in the organization of the actin cytoskeleton, cytoplasmic streaming and the architecture of the transvacuolar strand in root hair cells of Hydrocharis

Planta ◽  
2000 ◽  
Vol 210 (5) ◽  
pp. 836-843 ◽  
Author(s):  
Motoki Tominaga ◽  
Etsuo Yokota ◽  
Luis Vidali ◽  
Seiji Sonobe ◽  
Peter K. Hepler ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Hair Cells ◽  
Root Hair ◽  
Cytoplasmic Streaming ◽  
Root Hair Cells

scholarly journals Comparison of Effects on Gene Expression Activity of Low-Molecular-Weight Lychee Fruit Polyphenol (Oligonol®), Adenosine, and Minoxidil in Human Dermal Papilla Cells

2017 ◽  
Vol 3 (1) ◽  
pp. 5 ◽  
Author(s):  
Koji Wakame ◽  
Akifumi Nakata ◽  
Keisuke Sato ◽  
Yoshihiro Mihara ◽  
Jun Takanari ◽  
...  
Keyword(s):  
Cell Lines ◽  
Dna Microarrays ◽  
Food Product ◽  
Dermal Papilla ◽  
Pcr Analysis ◽  
Low Molecular Weight ◽  
Dermal Papilla Cells ◽  
Dermal Papilla Cell ◽  
Expression Of Genes ◽  
Expression Activity

Background: Oligonol® (OLG) is a functional food product and ingredient for cosmetics derived from a lychee fruit polyphenol. It has been reported to act on the skin as an anti-inflammatory and prevent UVB-induced skin damage.Aim: In this study, with the aim of exploring new functionalities of OLG on the scalp, we investigated the effect of OLG on human dermal papilla cells by comparing with adenosine and minoxidil at the genetic level.Method: OLG, adenosine, and minoxidil were applied to human dermal papilla cell lines for 24 h, after which VEGF, FGF-7, WNT5a, and WNT10a mRNA expressions were measured by real-time PCR analysis. Additionally, using DNA microarrays, we investigated the effect on 205 inflammation-related genes.Result: Consequently, in human dermal papilla cell lines, FGF-7 and WNT10a mRNA expression were observed in 100 µg/mL OLG-supplemented cells. The results of the DNA microarray analysis showed that 10 genes were suppressed by OLG.Conclusions: OLG may be expected to affect function of human dermal papilla cell by regulating the expression of genes related to cell proliferation and inflammation.

scholarly journals Alfalfa Root Nodule Invasion Efficiency Is Dependent on Sinorhizobium melilotiPolysaccharides

2000 ◽  
Vol 182 (15) ◽  
pp. 4310-4318 ◽  
Author(s):  
Brett J. Pellock ◽  
Hai-Ping Cheng ◽  
Graham C. Walker
Keyword(s):  
Molecular Weight ◽  
Sinorhizobium Meliloti ◽  
Root Nodule ◽  
Fluorescent Protein ◽  
Infection Thread ◽  
Low Molecular Weight ◽  
Infection Threads ◽  
Green Fluorescent ◽  
K Antigen ◽  
Alfalfa Root

ABSTRACT The soil bacterium Sinorhizobium meliloti is capable of entering into a nitrogen-fixing symbiosis with Medicago sativa (alfalfa). Particular low-molecular-weight forms of certain polysaccharides produced by S. meliloti are crucial for establishing this symbiosis. Alfalfa nodule invasion by S. meliloti can be mediated by any one of three symbiotically important polysaccharides: succinoglycan, EPS II, or K antigen (also referred to as KPS). Using green fluorescent protein-labeled S. meliloti cells, we have shown that there are significant differences in the details and efficiencies of nodule invasion mediated by these polysaccharides. Succinoglycan is highly efficient in mediating both infection thread initiation and extension. However, EPS II is significantly less efficient than succinoglycan at mediating both invasion steps, and K antigen is significantly less efficient than succinoglycan at mediating infection thread extension. In the case of EPS II-mediated symbioses, the reduction in invasion efficiency results in stunted host plant growth relative to plants inoculated with succinoglycan or K-antigen-producing strains. Additionally, EPS II- and K-antigen-mediated infection threads are 8 to 10 times more likely to have aberrant morphologies than those mediated by succinoglycan. These data have important implications for understanding how S. meliloti polysaccharides are functioning in the plant-bacterium interaction, and models are discussed.

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