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Recycling of Energy Dissipated as Heat Accounts for High Activity of Photosystem II.

ABSTRACT: Photosystem II (PSII) converts light into chemical energy powering almost all life on Earth. The primary photovoltaic reaction in the PSII reaction center requires energy corresponding to 680 nm, which is significantly higher than in the case of the low-energy states in the antenna complexes involved in the harvesting of excitations driving PSII. Here we show that despite seemingly insufficient energy, the low-energy excited states can power PSII because of the activity of the thermally driven up-conversion. We demonstrate the operation of this mechanism both in intact leaves and in isolated pigment-protein complex LHCII. A mechanism is proposed, according to which the effective utilization of thermal energy in the photosynthetic apparatus is possible owing to the formation of LHCII supramolecular structures, leading to the coupled energy levels corresponding to approximately 680 and 700 nm, capable of exchanging excitation energy through the spontaneous relaxation and the thermal up-conversion.

SUBMITTER: Zubik M

PROVIDER: S-EPMC7588127 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature

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Recycling of Energy Dissipated as Heat Accounts for High Activity of Photosystem II.

Zubik Monika M Luchowski Rafal R Kluczyk Dariusz D Grudzinski Wojciech W Maksim Magdalena M Nosalewicz Artur A Gruszecki Wieslaw I WI

The journal of physical chemistry letters 20200413 9

Photosystem II (PSII) converts light into chemical energy powering almost all life on Earth. The primary photovoltaic reaction in the PSII reaction center requires energy corresponding to 680 nm, which is significantly higher than in the case of the low-energy states in the antenna complexes involved in the harvesting of excitations driving PSII. Here we show that despite seemingly insufficient energy, the low-energy excited states can power PSII because of the activity of the thermally driven u ...[more]

PMID: 32271019

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Project description:PurposeTo determine factors impacting cumulative dissipated energy (CDE) and postoperative best-corrected visual acuity (BCVA) in phacoemulsification.DesignReview of 1102 cases at University of California, San Francisco (UCSF) and at Zhongshan Ophthalmic Center (ZOC), China.SubjectsPatients who underwent cataract surgery at UCSF 03/2014-03/2019 and at ZOC 10/2018-05/2019.MethodsPatient demographics, medical history, routine ocular examination, and surgical information, including disassembly method, complications, and surgeon training level were recorded. Univariable and multivariable regression models were used to determine factors associated with CDE and good postoperative BCVA (20/40 or better) at 1 month.Outcome measuresCDE, postoperative BCVA.ResultsIn multivariable analysis, patient age at time of surgery, diabetes, degree of nuclear sclerosis (NS), white-to-white corneal diameter, disassembly method, preoperative BCVA, surgeon training level, and surgical center were significantly associated with CDE. Log10CDE increased by 0.20-0.31 for patient age ≥ 70 years, by 0.07 if the patient had diabetes, by 0.12-0.41 for NS grade ≥ 2, by 0.48 per 10 mm increase in white-to-white corneal diameter, by 0.34-0.47 for disassembly method other than non-stop chop, by 0.16 per unit increase in preoperative logMAR BCVA, and by > 0.09 when phacoemulsification was performed by residents early in their training. Log10CDE was 0.33 higher at UCSF than ZOC. In multivariable analysis, worse baseline visual acuity and age above 90 years at time of surgery decreased the odds of good BCVA (OR = 0.26 per unit increase in preoperative logMAR BCVA; OR = 0.12 for age > 90); comorbid retinal issues decreased the odds of good postoperative BCVA (OR = 0.13-0.39); greater anterior chamber depth (ACD) or shorter axial length (AL), increased the odds of good postoperative outcome (OR = 2.64 per 1 mm increase ACD, OR = 0.84 per 1 mm increase AL).ConclusionsCataract grade determined by slit lamp exam and, for the first time, older patient age, were noted to be important predictors of high CDE. CDE was not a risk factor for postoperative BCVA measured at postoperative 1 month. When surgery was performed by trainees under supervision, lower training level was associated with higher CDE, but not with worse postoperative BCVA.

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Recycling of Energy Dissipated as Heat Accounts for High Activity of Photosystem II.

Publications

Recycling of Energy Dissipated as Heat Accounts for High Activity of Photosystem II.

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