We report the first direct decomposition of the fluorescence lifetime heterogeneity during multiphasic fluorescence induction in dark-adapted leaves by multi-frequency phase and modulation fluorometry (PMF). A very fast component, assigned to photosystem I (PSI), was found to be constant in lifetime and yield, whereas the two slow components, which are strongly affected by the closure of the reaction centers by light, were assigned to PSII. Based on a modified "reversible radical pair" kinetic model with three compartments, we showed that a loosely connected pigment complex, which is assumed to be the CP47 complex, plays a specific role with respect to the structure and function of the PSII: (i) it explains the heterogeneity of PSII fluorescence lifetime as a compartmentation of excitation energy in the antenna, (ii) it is the site of a conformational change in the first second of illumination, and (iii) it is involved in the mechanisms of nonphotochemical quenching (NPQ). On the basis of the multi-frequency PMF analysis, we reconciled two apparently antagonistic aspects of chlorophyll a fluorescence in vivo: it is heterogeneous with respect to the kinetic structure (several lifetime components) and homogeneous with respect to average quantities (quasi-linear mean tau-Phi relationship).
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http://dx.doi.org/10.1016/j.bbabio.2004.04.003 | DOI Listing |
Schizophr Bull
January 2025
Orygen, Parkville, Victoria 3052, Australia.
Background: Although attention deficit hyperactivity disorder (ADHD) is known to be common in psychotic disorders, reported prevalence rates vary widely, with limited understanding of how different factors (eg, assessment methods, geographical region) may be associated with this variation. The aim was to conduct a systematic review and meta-analysis to determine the prevalence of ADHD in psychotic disorders and factors associated with the variability in reported rates.
Study Design: Searches were conducted in MEDLINE, Embase, PsycINFO, CINAHL, and Scopus in May 2023.
Biophys Rep (N Y)
January 2025
UCLA-DOE Institute for Genomics and Proteomics, Department of Biological Chemistry, University of California at Los Angeles, Los Angeles, CA 90095, USA,; Department of Chemistry and Biochemistry, University of California at Los Angeles, Los Angeles, CA 90095, USA,; Department of Physiology, University of California at Los Angeles, Los Angeles, CA 90095, USA,; California Nano Systems Institute, University of California at Los Angeles, Los Angeles, CA 90095, USA,; Department of Physics, Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 52900, Israel.
Membrane potential (MP) changes can provide a simple readout of bacterial functional and metabolic state or stress levels. While several optical methods exist for measuring fast changes in MP in excitable cells, there is a dearth of such methods for absolute and precise measurements of steady-state membrane potentials (MPs) in bacterial cells. Conventional electrode-based methods for the measurement of MP are not suitable for calibrating optical methods in small bacterial cells.
View Article and Find Full Text PDFAddict Behav
January 2025
University of Connecticut, Storrs, CT, USA.
Objectives: To expand the literature documenting that tobacco use inequities persist and continue to increase for minoritized youth populations by exploring patterns of tobacco use across multiple intersections of sexual, gender, racial, and ethnic identities. Studies with this focus are needed to understand the degree to which tobacco use varies across groups who hold multiple minoritized identities.
Methods: The current study used a novel analytical approach- Exhaustive Chi-square Automatic Interaction Detection - to examine lifetime cigarette use among a U.
Anal Chem
January 2025
Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States.
Two-dimensional infrared (2D IR) spectroscopy is a powerful technique for measuring molecular heterogeneity and dynamics with a high spatiotemporal resolution. The methods can be applied to characterize specific residues of proteins by incorporating frequency-resolved vibrational labels. However, the time scale of dynamics that 2D IR spectroscopy can measure is limited by the vibrational label's excited-state lifetime due to the decay of 2D IR absorption bands.
View Article and Find Full Text PDFJ Membr Biol
January 2025
Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Kolkata, India.
Inward rectifying potassium (Kir) channels play a critical role in maintaining the resting membrane potential and cellular homeostasis. The high-resolution crystal structure of homotetrameric KirBac1.1 in detergent micelles provides a snapshot of the closed state.
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