Induction of reactive oxygen generation and functional changes in mitochondria and their involvement in the development of bacterial rot in lettuce caused by Pseudomonas cichorii

Effects of low-frequency electromagnetic fields (LF EMF) on the activation of different tissue recovery processes have already been fully understood. Preliminary recent data demonstrated that a special case of sinusoidal electromagnetic fields, known as amplitude-modulated currents (AMC) could have a potential to accelerate the cell metabolism or cell migration. An AMC generator was designed to generate sinusoidal induced electric currents with the amplitude modulation and the harmonic carrier frequency of 5,000 Hz was modulated by frequencies of 1 to 100 Hz. The magnetic field peak was 6 mT, electric field intensity 2 V/m and the current density of induced electrical currents was approximately 1 A/m2. The coil of the generator was adapted to easy handling and safe integration into the shelf of the CO2 incubator. The shelf with the coil was prepared for the introduction of cells in standard plastic in vitro chambers. The tests focused on cells with migratory capacity after injury or during immunological processes and thus, mesenchymal stromal cells (MSC), dendritic cells (DC), and fibroblasts were chosen. The tests involved exposures of the cells to LF EMF (180 min/day) every day, for a period of three days, before examining them for cell death, morphology changes, and CD markers. The samples were tested by using MTT assay and the effects on the intracellular concentration of reactive oxygen species were quantified. The cell migration was finally measured with the help of the transwell migration assay. None of the cell types showed any decrease in the cell viability after the LF EMF application and the cells displayed minimum changes in reactive oxygen species. Functional changes (acceleration of cell migration) after AMC exposure were statistically significant for the MSC samples only. The acceleration of MSCs is associated with the production of MMP by these cells. The EMF has a potential to be a safe, clinically applicable selective activator of MSC homing, MSC paracrine production, and subsequent regeneration processes.

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Divergent and convergent effects on gene expression and function in acute versus chronic endothelial activation

Physiological Genomics ◽

10.1152/physiolgenomics.00157.2006 ◽

2007 ◽

Vol 31 (1) ◽

pp. 104-113 ◽

Cited By ~ 20

Author(s):

Gangaraju Rajashekhar ◽

Matthew Grow ◽

Antje Willuweit ◽

Carolyn E. Patterson ◽

Matthias Clauss

Keyword(s):

Gene Expression ◽

Reactive Oxygen Species ◽

Endothelial Cells ◽

Map Kinases ◽

Reactive Oxygen ◽

Endothelial Activation ◽

P38 Map Kinase ◽

Endothelial Cell Migration ◽

Oxygen Species ◽

Functional Changes

Activation of the vascular endothelium with cytokines such as TNF is widely used to study the role of the vasculature in proinflammatory disease. To gain insight into mechanisms of prolonged vascular endothelial activation we compared changes in gene expression induced by continuous activation in stable tmTNF-expressing cells with changes due to acute TNF challenge in vitro. Affymetrix Genechip analysis was performed on RNA from control, acute and continuous TNF-activated endothelial cells. Only 36% of the significant changes in gene expression were convergent between the acute and continuously activated endothelial cells compared with the control. From the divergently regulated genes, for example the cytokine ENA-78 was specifically induced in chronically activated cells, while E-selectin, a cell adhesion molecule, was upregulated only in acutely activated endothelial cells. Antioxidant SOD gene induction was noted in acute activation, while a regulatory NADPH oxidase subunit was selectively upregulated in continuously activated endothelium in accordance with significant reactive oxygen species induction occurred only in these cells. Accordingly, p38 and ERK1/2, two MAP kinases downstream of reactive oxygen species, were activated in stable transmembrane-spanning precursor (tm) TNF-expressing cells and were refractory to activation with soluble TNF or VEGF. In consequence, the increased p38 MAP kinase activity contributed to increased endothelial cell migration in tmTNF-expressing cells. These data suggest that continuous activation of endothelial cells leads to specific expression and functional changes, consistent with alterations observed in dysfunctional endothelium exposed to or involved in chronic inflammation.

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The mechanism of cell-damaging reactive oxygen generation by colloidal fullerenes

Biomaterials ◽

10.1016/j.biomaterials.2007.09.002 ◽

2007 ◽

Vol 28 (36) ◽

pp. 5437-5448 ◽

Cited By ~ 88

Author(s):

Zoran Markovic ◽

Biljana Todorovic-Markovic ◽

Duska Kleut ◽

Nadezda Nikolic ◽

Sanja Vranjes-Djuric ◽

...

Keyword(s):

Reactive Oxygen ◽

Oxygen Generation

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Activation of phospholipases by N -acetylchitooligosaccharide elicitor in suspension-cultured rice cells mediates reactive oxygen generation

Physiologia Plantarum ◽

10.1034/j.1399-3054.2003.00131.x ◽

2003 ◽

Vol 118 (3) ◽

pp. 361-370 ◽

Cited By ~ 47

Author(s):

Takeshi Yamaguchi ◽

Eiichi Minami ◽

Naoto Shibuya

Keyword(s):

Reactive Oxygen ◽

Oxygen Generation

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Induction of Apoptotic Cell Death Leads to the Development of Bacterial Rot Caused by Pseudomonas cichorii

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-19-0112 ◽

2006 ◽

Vol 19 (2) ◽

pp. 112-122 ◽

Cited By ~ 25

Author(s):

Akinori Kiba ◽

Yasutaka Sangawa ◽

Kouhei Ohnishi ◽

Nan Yao ◽

Pyoyun Park ◽

...

Keyword(s):

Cell Death ◽

De Novo ◽

Apoptotic Cell ◽

Leaf Tissue ◽

Apoptotic Cell Death ◽

Pseudomonas Cichorii ◽

Disease Symptoms ◽

Dna Laddering ◽

Bacterial Rot ◽

De Novo Protein Synthesis

Pseudomonas cichorii is the major causal agent of bacterial rot of lettuce. Collapse and browning symptoms were observed in lettuce leaf tissue from 15 to 24 h after inoculation (HAI) with P.cichorii; superoxide anion generation was detected at 1 to 6 HAI; and cell death was induced at 6 HAI, reaching a maximum at approximately 9 and 12 HAI. Heterochromatin condensation and DNA laddering also were observed within 3 HAI. Pharmacological studies showed that induction of cell death and DNA laddering was closely associated with de novo protein synthesis, protein kinase, intracellular reactive oxygen species, DNase, serine protease, and caspase III-like protease. Moreover, chemicals, which inhibited the induction of cell death and DNA laddering, also suppressed the development of disease symptoms. These results suggest that apoptotic cell death might be closely associated with the development of bacterial rot caused by P. cichorii.

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