Summary• The hypothesis was tested that flavonoids may scavenge singlet oxygen ( 1 O 2 ) in mesophyll cells of Phillyrea latifolia exposed to excess-light stress.• In cross-sections taken from leaves developed at 10% (shade) or 100% (sun) solar irradiance, we evaluated the excess photosynthetically active radiation (PAR)-induced accumulation of 1 O 2 in mesophyll cells by imaging the fluorescence quenching of theThe intracellular location of flavonoids was also analyzed using three-dimensional deconvolution microscopy.• Photo-induced quenching of DanePy fluorescence was markedly greater in the mesophyll of shade leaves than in that of sun leaves, the former showing a negligible accumulation of mesophyll flavonoids. The photo-induced generation of 1 O 2 was inversely related to the content of flavonoids in the mesophyll cells of sun leaves. Flavonoids were located in the chloroplasts, and were likely associated with the chloroplast envelope.• Here we provide relevant evidence for the potential scavenger activity of chloroplast-located flavonoids against 1 O 2 and new insights into the photo-protective role of flavonoids in higher plants.

The loss of organization of the corneal collagen lattice induced by photothermal effects was analyzed by using second-harmonic generation (SHG) imaging. Porcine cornea samples were treated with low-power laser irradiation in order to get localized areas of tissue disorganization. The disorder induced within the irradiated area of corneal stroma was quantified by means of Discrete Fourier Transform, auto-correlation and entropy analyses of the SHG images. Polarization modulated SHG measurements allowed to probe the changes in the structural anisotropy of sub-micron hierarchical levels of the stromal collagen. Our results emphasize the great potential of the SHG imaging to detect subtle modifications in the collagen assembly. The proposed analytical methods may be used to track several genetic, pathologic, accidental or surgical-induced disorder states of biological tissues.

Starburst dendrimers (SBDs) of different generations (size) and level of protonations of their surface amino groups and solutions of dimyristoylphosphatidylcholine (DMPC) vesicles were analyzed, both separately and in mixtures of the two components, by negative-staining transmission electron microscopy (TEM), dynamic light scattering (DLS), and, mainly, by computer-aided continuous wave (CW)-and pulsed-electron paramagnetic resonance (EPR). For the EPR study, the SBDs were labeled with a nitroxide radical (SBD-T). TE micrographs showed the vesicles as multilamellar structures of spherical shape with diameters ranging from 0.2 to 1.2 m. DLS measurements provided the mean vesicle diameter (d) at ca. 400 nm, whereas the diameter of generation 6 was 7 nm. No large-sized permanent supramolecular structures (d > 400 nm) were formed. EPR measurements at room temperature were poorly informative, since (1) a fraction of the dendrimers was not interacting with the vesicles, and (b) the labels that were interacting with the vesicles were rotating quickly around the main axis. Interactions between the dendrimers and the vesicles (tested by a decrease in rotational mobility of the label) became EPR-observable and quantifiable below the freezing transition of a portion of the solution, which could not be detected by EPR analysis. The fraction of the dendrimers interacting with the vesicles underwent a glass transition. Dendrimer-vesicle interactions modified the direction of the fast-rotation axis of the radical, and the interaction was more effective for protonated dendrimers of a larger size, i.e., later generation. A "complex" was formed between one solvent molecule and the nitroxide radical. Interactions between the SBD-T and the vesicle partially compressed the hydration layer of the N-O group, and/or the hydration layer of the vesicle headgroups was compressed onto the unpaired-electron site. This study provides information on the possible utilization of starburst dendrimers as gene carriers.

Objectives: Currently, the exact reasons why different α-synucleinopathies exhibit variable pathologies and phenotypes are still unknown. A potential explanation may be the existence of distinctive α-synuclein conformers or strains. Here, we intend to analyze the seeding activity of dementia with Lewy bodies (DLB) and Parkinson's disease (PD) brain-derived α-synuclein seeds by real-time quaking-induced conversion (RT-QuIC) and to investigate the structure and morphology of the α-synuclein aggregates generated by RT-QuIC. Methods: A misfolded α-synuclein-enriched brain fraction from frontal cortex and substantia nigra pars compacta tissue, isolated by several filtration and centrifugation steps, was subjected to α-synuclein/RT-QuIC analysis. Our study included neuropathologically well-characterized cases with DLB, PD, and controls (Ctrl). Biochemical and morphological analyses of RT-QuIC products were conducted by western blot, dot blot analysis, Raman spectroscopy, atomic force microscopy, and transmission electron microscopy. Results: Independently from the brain region, we observed different seeding kinetics of α-synuclein in the RT-QuIC in patients with DLB compared to PD and Ctrl. Biochemical characterization of the RT-QuIC product indicated the generation of a proteinase K-resistant and fibrillary α-synuclein species in DLB-seeded reactions, whereas PD and control seeds failed in the conversion of wild-type α-synuclein substrate. Interpretation: Structural variances of α-synuclein seeding kinetics and products in DLB and PD indicated, for the first time, the existence of different α-synuclein strains in these groups. Therefore, our study contributes to a better understanding of the clinical heterogeneity among α-synucleinopathies, offers an opportunity for a specific diagnosis, and opens new avenues for the future development of strain-specific therapies. ANN NEUROL 2019;85:691-703 S ynucleinopathies, such as Parkinson's disease (PD) and dementia with Lewy bodies (DLB), are a class of neurodegenerative diseases characterized by the presence of insoluble intraneural deposits consisting of fibrillary α-synuclein, 1,2 referred to as Lewy bodies. A PD with dementia (PDD) diagnosis is appropriate when the cognitive symptoms View this article online at wileyonlinelibrary.com.