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Cyanobacterial thylakoid membranes are known to host photosynthetic and respiratory complexes. This hampers a straight forward interpretation of the highly dynamic fluorescence originating from photosynthetic units. The present study focuses on dark-to-light transitions in whole cells of a PSI-deficient mutant of the cyanobacterium Synechocystis sp. PCC 6803. The time-dependent cellular fluorescence spectrum has been measured, while having previously exposed the cells to different conditions that affect respiratory activity. The analysis method used allows the detected signal to be decomposed in a few components that are then assigned to functional emitting species. Additionally, we have worked out a minimal mathematical model consisting of sensible postulated species to interpret the recorded data. We conclude that the following two functional complexes play a major role: a phycobilisome antenna complex coupled to a PSII dimer with either two or no closed reaction centers. Crucially, we present evidence for an additional species capable of strongly quenching fluorescence, whose formation requires the presence of oxygen.
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http://dx.doi.org/10.1016/j.bbabio.2017.11.002 | DOI Listing |
ACS Nano
September 2025
Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80303, United States.
Tuning the exciton fine structure of lead halide perovskites to brighten the dark excitonic ground state is crucial for enhancing their optoelectronic performance. While Rashba splitting is linked to dark-to-light exciton flipping, the specific nature of this phenomenon remains unclear. Here, we systematically studied 18 CsPbBr structures, representing 2D systems of CsPbBr with varying degrees of distortion, using density functional theory (DFT) and the Model-Bethe-Salpeter Equation (m-BSE).
View Article and Find Full Text PDFPlant J
June 2025
Department of Biotechnology, National Institute of Technology Durgapur, Durgapur, 713209, India.
HY5, a basic leucine zipper (bZIP) transcription factor, acts as a positive regulator of photomorphogenesis across various wavelengths of light. HY5 also mediates crosstalk between light and abscisic acid (ABA) signaling pathways. During transition from dark to light, HY5 regulates the transcription of about one third of genes in Arabidopsis, necessitating precise regulation of HY5 activity for proper seedling growth.
View Article and Find Full Text PDFJ Integr Plant Biol
August 2025
National Engineering Laboratory of Crop Stress Resistance Breeding, School of Life Sciences, Anhui Agricultural University, Hefei, 230036, China.
Germinating seeds undergo elaborate de-etiolation developmental transitions upon initial soil emergence. As central transcription factors promoting cotyledon greening, the abundance of ETHYLENE-INSENSITIVE 3 (EIN3) and PHYTOCHROME-INTERACTING FACTOR 3 (PIF3) are strictly controlled by physically associating themselves with the EIN3-BINDING F BOX PROTEINS 1 and 2 (EBF1/2) for ubiquitination. Here, we report that the B-box zinc-finger protein BBX32, as a positive regulator during seedling de-etiolation.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
June 2025
New Cornerstone Science Laboratory, Department of Biology, School of Life Sciences, Institute of Plant and Food Science, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China.
Greening immediately after etiolated-seedling's emergence from the soil is critical for plants to initiate their autotrophic life cycle through photosynthesis. The greening process relies on a complex transcriptional network that fine-tunes the biosynthesis of chlorophyll and prevents premature development of chloroplasts. In this study, we identified the HOOKLESS1 (HLS1) as a key regulator of light-induced cotyledon greening.
View Article and Find Full Text PDFPlant Cell
April 2025
College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang Province 310058, China.
Stomatal opening facilitates CO2 uptake and causes water loss via transpiration. Compared with the considerable progress made toward understanding phototropin-mediated blue light (BL) signaling in guard cells, the significance of cryptochromes (CRYs) in stomatal opening and their downstream elements remain largely unknown. Here, we show that 3 homologous MYB transcription factor genes, namely MYB11, MYB12, and MYB111, are rapidly transactivated in guard cells during the dark-to-light transition in Arabidopsis (Arabidopsis thaliana).
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