Photosensitizers Neutral Red (Type I) and Rose Bengal (Type II) Cause Light-Dependent Toxicity in <i>Chlamydomonas reinhardtii</i> and Induce the <i>Gpxh</i> Gene via Increased Singlet Oxygen Formation

Fischer, Beat B.; Krieger‐Liszkay, Anja; Eggen, Rik I.L.

doi:10.1021/es049673y

Cited by 99 publications

(74 citation statements)

References 54 publications

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“…Blocking the gene expression of LHCX1 and LHCX2 with DCMU in HL was not possible. As mentioned above, besides keeping the PQ pool oxidized, DCMU creates high amounts of singlet oxygen (Flors et al, 2006), which in plants is the most harmful ROS (Triantaphylidès et al, 2008;Triantaphylidès and Havaux, 2009) and which is able to induce nuclear gene expression (op den Camp et al, 2003;Fischer et al, 2004). We assume that LHCX1 and LHCX2 are also induced by singlet oxygen, which superimposes on the effect of the PQ pool redox state.…”

Section: The Regulation Of Lhcx Gene Expressionmentioning

confidence: 99%

High Light Acclimation in the Secondary Plastids Containing Diatom Phaeodactylum tricornutum is Triggered by the Redox State of the Plastoquinone Pool

et al. 2012

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In diatoms, the process of energy-dependent chlorophyll fluorescence quenching (qE) has an important role in photoprotection. Three components are essential for qE: (1) the light-dependent generation of a transthylakoidal proton gradient; (2) the deepoxidation of the xanthophyll diadinoxanthin (Dd) into diatoxanthin (Dt); and (3) specific nucleus-encoded antenna proteins, called Light Harvesting Complex Protein X (LHCX). We used the model diatom Phaeodactylum tricornutum to investigate the concerted light acclimation response of the qE key components LHCX, proton gradient, and xanthophyll cycle pigments (Dd+Dt) and to identify the intracellular light-responsive trigger. At high-light exposure, the up-regulation of three of the LHCX genes and the de novo synthesis of Dd+Dt led to a pronounced rise of qE. By inhibiting either the conversion of Dd to Dt or the translation of LHCX genes, qE amplification was abolished and the diatom cells suffered from stronger photoinhibition. Artificial modification of the redox state of the plastoquinone (PQ) pool via 3-(3,4-dichlorophenyl)-1,1-dimethylurea and 5-dibromo-6-isopropyl-3-methyl-1,4-benzoquinone resulted in a disturbance of Dd+Dt synthesis in an opposite way. Moreover, we could increase the transcription of two of the four LHCX genes under low-light conditions by reducing the PQ pool using 5-dibromo-6-isopropyl-3-methyl-1,4-benzoquinone. Altogether, our results underline the central role of the redox state of the PQ pool in the light acclimation of diatoms. Additionally, they emphasize strong evidence for the existence of a plastid-to-nucleus retrograde signaling mechanism in an organism with plastids that derived from secondary endosymbiosis.

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Section: The Regulation Of Lhcx Gene Expressionmentioning

confidence: 99%

High Light Acclimation in the Secondary Plastids Containing Diatom Phaeodactylum tricornutum is Triggered by the Redox State of the Plastoquinone Pool

et al. 2012

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“…This photosensitizer was previously shown to specifically generate singlet oxygen ( 1 O 2 ) upon light irradiation [5].…”

Section: Introductionmentioning

confidence: 99%

Rose bengal uptake by E. faecalis and F. nucleatum and light-mediated antibacterial activity measured by flow cytometry

Manoil

Filieri

Schrenzel

et al. 2016

Journal of Photochemistry and Photobiology B: Biology

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Rose bengal uptake by E. faecalis and F. nucleatum and light-mediated antibacterial activity measured by flow cytometry Antibacterial photodynamic therapy (aPDT) using rose bengal (RB) and blue-light kills bacteria through the production of reactive oxygen derivates. However, the interaction mechanism of RB with bacterial cells remains unclear. This study investigated the uptake efficiency and the antibacterial activity of blue light-activated RB against Enterococcus faecalis and Fusobacterium nucleatum. Spectrophotometry and epifluorescence microscopy were used to evaluate binding of RB to bacteria. The antibacterial activity of RB after various irradiation times was assessed by flow cytometry in combination with cell sorting. Uptake of RB increased in a concentration dependent manner in both strains although E. faecalis displayed higher uptake values. RB appeared to bind specific sites located at the cellular poles of E. faecalis and at regular intervals along F. nucleatum. Blue-light irradiation of samples incubated with RB significantly reduced bacterial viability. After incubation with 10 μM RB and 240 s irradiation, only 0.01% (± 0.01%) of E. faecalis cells and 0.03% (±0.03%) of F. nucleatum survived after treatment. This study indicated that RB can bind to E. faecalis and F. nucleatum in a sufficient amount to elicit effective aPDT. Epifluorescence microscopy showed a yet-unreported property of RB binding to bacterial membranes. Flow cytometry allowed the detection of bacteria with damaged membranes that were unable to form colonies on agars after cell sorting.

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“…Despite (21,23,55). The photosynthetic proteobacterium Rhodobacter sphaeroides also induces a glutathione peroxidase in response to singlet oxygen (37), and multiple R. sphaeroides operons have been identified that appear to be under 1 O 2 ‫ء‬ control (3).…”

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confidence: 99%

Acclimation to Singlet Oxygen Stress in Chlamydomonas reinhardtii

2007

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In an aerobic environment, responding to oxidative cues is critical for physiological adaptation (acclimation) to changing environmental conditions. The unicellular alga Chlamydomonas reinhardtii was tested for the ability to acclimate to specific forms of oxidative stress. Acclimation was defined as the ability of a sublethal pretreatment with a reactive oxygen species to activate defense responses that subsequently enhance survival of that stress. C. reinhardtii exhibited a strong acclimation response to rose bengal, a photosensitizing dye that produces singlet oxygen. This acclimation was dependent upon photosensitization and occurred only when pretreatment was administered in the light. Shifting cells from low light to high light also enhanced resistance to singlet oxygen, suggesting an overlap in high-light and singlet oxygen response pathways. Microarray analysis of RNA levels indicated that a relatively small number of genes respond to sublethal levels of singlet oxygen. Constitutive overexpression of either of two such genes, a glutathione peroxidase gene and a glutathione S-transferase gene, was sufficient to enhance singlet oxygen resistance. Escherichia coli and Saccharomyces cerevisiae exhibit well-defined responses to reactive oxygen but did not acclimate to singlet oxygen, possibly reflecting the relative importance of singlet oxygen stress for photosynthetic organisms.Reactive oxygen species (ROS) production is an unavoidable consequence of life in an aerobic environment, and reliance upon oxygenic photosynthesis presents plants and algae with sources of ROS not generally shared by their nonphotosynthetic counterparts. Nearly any form of biotic or abiotic stress affects the chloroplast, where the photosynthetic electron transport chain brings together photosensitizing pigments, redox-active electron carriers, and oxygen generation in a polyunsaturated lipid environment. Disruptions in the balance between incoming excitation energy and terminal electron acceptors can result in ROS production and eventual cell death. High-light (HL) stress, for example, leads to increased production of singlet oxygen ( 1 O 2 ‫,)ء‬ hydrogen peroxide, and superoxide in the chloroplast (31, 44), while hypersensitive responses to tobacco mosaic virus in tobacco result in down-regulation of the proteins necessary to repair ROS-mediated damage to photosystem II (71). Understanding how plants and algae respond to ROS and limit ROS-induced damage is therefore necessary to piece together responses to biotic and abiotic stress.As a result of the capacity of ROS for damaging cellular constituents, including proteins, nucleic acids, and membranes (41), ROS are often cast in a purely destructive role. Evidence is emerging, however, that sublethal levels of ROS can be important signaling intermediates (4, 30), activating pathways that bolster defense responses and enhance survival of subsequent stress (11,13,47,78). For example, in the yeast Saccharomyces cerevisiae, sublethal levels of hydrogen peroxide activate the YAP1 (yeast ...

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Photosensitizers Neutral Red (Type I) and Rose Bengal (Type II) Cause Light-Dependent Toxicity in Chlamydomonas reinhardtii and Induce the Gpxh Gene via Increased Singlet Oxygen Formation

Cited by 99 publications

References 54 publications

High Light Acclimation in the Secondary Plastids Containing Diatom Phaeodactylum tricornutum is Triggered by the Redox State of the Plastoquinone Pool

High Light Acclimation in the Secondary Plastids Containing Diatom Phaeodactylum tricornutum is Triggered by the Redox State of the Plastoquinone Pool

Rose bengal uptake by E. faecalis and F. nucleatum and light-mediated antibacterial activity measured by flow cytometry

Acclimation to Singlet Oxygen Stress in Chlamydomonas reinhardtii

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