Dataset Information

Intrinsic Fluctuations in Transpiration Induce Photorespiration to Oxidize P700 in Photosystem I.

ABSTRACT: Upon exposure to environmental stress, the primary electron donor in photosystem I (PSI), P700, is oxidized to suppress the production of reactive oxygen species that could oxidatively inactivate the function of PSI. The illumination of rice leaves with actinic light induces intrinsic fluctuations in the opening and closing of stomata, causing the net CO₂ assimilation rate to fluctuate. We examined the effects of these intrinsic fluctuations on electron transport reactions. Under atmospheric O₂ conditions (21 kPa), the effective quantum yield of photosystem II (PSII) (Y(II)) remained relatively high while the net CO₂ assimilation rate fluctuated, which indicates the function of alternative electron flow. By contrast, under low O₂ conditions (2 kPa), Y(II) fluctuated. These results suggest that photorespiration primarily drove the alternative electron flow. Photorespiration maintained the oxidation level of ferredoxin (Fd) throughout the fluctuation of the net CO₂ assimilation rate. Moreover, the relative activity of photorespiration was correlated with both the oxidation level of P700 and the magnitude of the proton gradient across the thylakoid membrane in 21 kPa O₂ conditions. These results show that photorespiration oxidized P700 by stimulating the proton gradient formation when CO₂ assimilation was suppressed by stomatal closure.

SUBMITTER: Furutani R

PROVIDER: S-EPMC7763966 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature

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Intrinsic Fluctuations in Transpiration Induce Photorespiration to Oxidize P700 in Photosystem I.

Furutani Riu R Makino Amane A Suzuki Yuij Y Wada Shinya S Shimakawa Ginga G Miyake Chikahiro C

Plants (Basel, Switzerland) 20201212 12

Upon exposure to environmental stress, the primary electron donor in photosystem I (PSI), P700, is oxidized to suppress the production of reactive oxygen species that could oxidatively inactivate the function of PSI. The illumination of rice leaves with actinic light induces intrinsic fluctuations in the opening and closing of stomata, causing the net CO<sub>2</sub> assimilation rate to fluctuate. We examined the effects of these intrinsic fluctuations on electron transport reactions. Under atmo ...[more]

PMID: 33322777

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Project description:Electrophysiological studies have long demonstrated a high degree of correlated activity between the left and right hemispheres, however little is known about regional variation in this interhemispheric coordination. Whereas cognitive models and neuroanatomical evidence suggest differences in coordination across primary sensory-motor cortices versus higher-order association areas, these have not been characterized. Here, we used resting-state functional magnetic resonance imaging data acquired from 62 healthy volunteers to examine interregional correlation in spontaneous low-frequency hemodynamic fluctuations. Using a probabilistic atlas, we correlated probability-weighted time series from 112 regions comprising the entire cerebrum. We then examined regional variation in correlated activity between homotopic regions, contrasting primary sensory-motor cortices, unimodal association areas, and heteromodal association areas. Consistent with previous studies, robustly correlated spontaneous activity was noted between all homotopic regions, which was significantly higher than that between nonhomotopic (heterotopic and intrahemispheric) regions. We further demonstrated substantial regional variation in homotopic interhemispheric correlations that was highly consistent across subjects. Specifically, there was a gradient of interhemispheric correlation, with highest correlations across primary sensory-motor cortices (0.758, SD=0.152), significantly lower correlations across unimodal association areas (0.597, SD=0.230) and still lower correlations across heteromodal association areas (0.517, SD=0.226). These results demonstrate functional differences in interhemispheric coordination related to the brain's hierarchical subdivisions. Synchrony across primary cortices may reflect networks engaged in bilateral sensory integration and motor coordination, whereas lower coordination across heteromodal association areas is consistent with functional lateralization of these regions. This novel method of examining interhemispheric coordination may yield insights regarding diverse disease processes as well as healthy development.

Dataset Information

Intrinsic Fluctuations in Transpiration Induce Photorespiration to Oxidize P700 in Photosystem I.

Publications

Intrinsic Fluctuations in Transpiration Induce Photorespiration to Oxidize P700 in Photosystem I.

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