Detecting the Environment

Mann, Nicholas H.

doi:10.1007/0-306-46855-7_14

Cited by 8 publications

(3 citation statements)

References 221 publications

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“…Besides photoreduction in PS1, a certain amount of oxygen can be also photoreduced in PS2 (Shimakawa et al 2015) or reduced extracellularly by reduced redox compounds excreted by the microbial cells (see Darus et al 2014 anda review in McCormick et al 2015). Accordingly, the DO consumption by reduced redox compounds, together with a decrease of DO evolving-PS2 It is well established that light inactivates the glucose-6-phosphate dehydrogenase (Mann 2002;Stanier and CohenBazire 1977;Tanaka et al 1985), meaning that respiration of stored organic carbon by cyanobacteria is not responsible for the emergence of anodic current during illumination. This means that the anodic current observed was the result of electrons extracellularly diverted from the photosynthetic bacteria, either directly towards the electrode (Gorby et al 2006;Sekar et al 2014) and/or indirectly via intermediate electron carriers e.g.…”

Section: Electrodes Are Used As Electron Sinks Under Reductive Stressmentioning

confidence: 99%

Marine phototrophic consortia transfer electrons to electrodes in response to reductive stress

et al. 2015

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This work studies how extracellular electron transfer (EET) from cyanobacteria-dominated marine microbial biofilms to solid electrodes is affected by the availability of inorganic carbon (Ci). The EET was recorded chronoamperometrically in the form of electrical current by a potentiostat in two identical photo-electrochemical cells using carbon electrodes poised at a potential of +0.6 V versus standard hydrogen electrode under 12/12 h illumination/dark cycles. The Ci was supplied by the addition of NaHCO3 to the medium and/or by sparging CO2 gas. At high Ci conditions, EET from the microbial biofilm to the electrodes was observed only during the dark phase, indicating the occurrence of a form of night-time respiration that can use insoluble electrodes as the terminal electron acceptor. At low or no Ci conditions, however, EET also occurred during illumination suggesting that, in the absence of their natural electron acceptor, some cyanobacteria are able to utilise solid electrodes as an electron sink. This may be a natural survival mechanism for cyanobacteria to maintain redox balance in environments with limiting CO2 and/or high light intensity.

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Section: Electrodes Are Used As Electron Sinks Under Reductive Stressmentioning

confidence: 99%

Marine phototrophic consortia transfer electrons to electrodes in response to reductive stress

et al. 2015

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“…We will only give a short consideration of the knowledge of some other selected aspects of adaptation to iron limitation in cyanobacteria. For comprehensive and broad views on the consequences of iron limitation in cyanobacteria see previously published reviews (Boyer et al 1987, Tandeau de Marsac and Houmard 1993, Ferreira and Straus 1994, Straus 1994, Mann 2000).…”

Section: Introductionmentioning

confidence: 99%

Adaptation of the photosynthetic electron transport chain in cyanobacteria to iron deficiency: The function of IdiA and IsiA

Michel

Pistorius

2004

Physiologia Plantarum

165

140

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In this review we give an overview on the adaptational responses of photosystem (PS) II and PSI in cyanobacteria to iron starvation, mainly summarizing our results with the mesophilic Synechococcus elongatus PCC 7942. We also discuss this process with respect to the strong interrelationship between iron limitation and oxidative stress that exists in cyanobacteria as oxygenic photosynthetic organisms. The adaptation of the multiprotein complexes PSII and PSI to iron starvation is a sequential process, which is characterized by the enhanced expression of two major iron-regulated proteins, IdiA (iron deficiency induced protein A) and IsiA (iron stress induced protein A). Our results suggest that IdiA protects the acceptor side of PSII against oxidative stress under conditions of mild iron limitation in a currently unclear way, whereas prolonged iron deficiency leads to the synthesis of a chlorophyll a antenna around PSI-trimers consisting of IsiA molecules. The physiological consequences of these alterations under prolonged iron starvation, as shown by acridine yellow fluorescence measurements, are a reduction of linear electron transport activity through PSII and an increase of cyclic electron flow around PSI as well as an increase in respiratory activity. IdiA and IsiA expression are mediated by two distinct helix-turn-helix transcriptional regulators of the Crp/Fnr family. IdiB positively regulates expression of idiA under iron starvation, and Fur represses transcription of isiA under iron-sufficient conditions. Although both transcriptional regulators seem to operate independently of each other, our results indicate that a cross-talk between the signal transduction pathways exists. Moreover, IdiA as well as IsiA expression are affected by hydrogen peroxide. We suggest that due to the interdependence of iron limitation and the formation of reactive oxygen species, peroxide stress might be the superior trigger that leads to expression of these proteins under iron starvation. The modifications of PSII and PSI under iron starvation influence the redox state of redox-sensitive components of the electron transport chain, and thus the activity of metabolic pathways being regulated in dependence of the redox state of these components.

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“…190 Dieses Licht, das ein anderes ist als dasjenige einer "konventionellen Glorie" und ihres "himmelblau-idealistischen Nimbus", 191 hätte der Dichter in den folgenden Sätzen implizit vorausgesehen -er, der bereits damals vom Herzog Carl August und von Goethe anerkannt wurde, aber nun erst, nach seinem Tode, als Held bezeichnet werden kann, als nun ewiger, zugleich gebändigter und freier Stern über der Nation. 192 Fast sein ganzes Leben lang hat er sein Leiden und seine Verzweiflung am Dasein ertragen, um dann mit seiner werdenden "Glorie" in das deutsche Land und darüber hinaus ausstrahlen zu können.…”

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Zur Darstellung künstlerischer Existenz in Thomas Manns frühen Erzählungen Der kleine Herr Friedemann, Schwere Stunde und Das Wunderkind.

Srichai¹

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Detecting the Environment

Cited by 8 publications

References 221 publications

Marine phototrophic consortia transfer electrons to electrodes in response to reductive stress

Marine phototrophic consortia transfer electrons to electrodes in response to reductive stress

Adaptation of the photosynthetic electron transport chain in cyanobacteria to iron deficiency: The function of IdiA and IsiA

Zur Darstellung künstlerischer Existenz in Thomas Manns frühen Erzählungen Der kleine Herr Friedemann, Schwere Stunde und Das Wunderkind.

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