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Photosynthesis is initiated when the sun's light induces electron transfer from chlorophyll to plastoquinone, a para-quinone. While photosynthesis occurs in the intact chloroplasts of living plants, similar photochemical reactions between dietary chlorophyll metabolites and quinones are likely and may affect health outcomes. Herein, we continue our studies of the direct photoreduction of para-quinones and ortho-quinones that were generated by the photo-oxidation of catechols. Chlorophyll metabolites, including pheophorbide A, chlorin e6, and pyropheophorbide A, as well as methylene blue were employed as photosensitizers. We detected hydrogen peroxide using horseradish peroxidase following the photo-oxidation of the catechol dopamine, even in the presence of EDTA, a tertiary amine electron donor. Under ambient oxygen, hydrogen peroxide was also detected after the photoreduction of several para-quinones, including 2,3-dimethoxy-5-methyl-p-benzoquinone (CoQ0), methoxy-benzoquinone, and methyl-benzoquinone. The combinations of methylene blue and EDTA or pheophorbide A and triethanolamine as the electron donor in 20% dimethylformamide were optimized for photoreduction of the para-quinones. Chlorin e6 and pyropheophorbide A were less effective for the photoreduction of CoQ0 but were equivalent to pheophorbide A for generating hydrogen peroxide in photo-oxidation reactions with photosensitizers, oxygen, and triethanolamine. We employed dinitrophenylhydrazine to generate intensely colored adducts of methoxy-benzoquinone, methyl-benzoquinone, and 1,4-benzoquinone. [ABSTRACT FROM AUTHOR]

Abstract Background Sigma factors and the alarmone ppGpp control the allocation of RNA polymerase to promoters under stressful conditions. Both ppGpp and the sigma factor σS (RpoS) are potentially subject to variability across the species Escherichia coli. To find out the extent of strain variation we measured the level of RpoS and ppGpp using 31 E. coli strains from the ECOR collection and one reference K-12 strain. Results Nine ECORs had highly deleterious mutations in rpoS, 12 had RpoS protein up to 7-fold above that of the reference strain MG1655 and the remainder had comparable or lower levels. Strain variation was also evident in ppGpp accumulation under carbon starvation and spoT mutations were present in several low-ppGpp strains. Three relationships between RpoS and ppGpp levels were found: isolates with zero RpoS but various ppGpp levels, strains where RpoS levels were proportional to ppGpp and a third unexpected class in which RpoS was present but not proportional to ppGpp concentration. High-RpoS and high-ppGpp strains accumulated rpoS mutations under nutrient limitation, providing a source of polymorphisms. Conclusions The ppGpp and σS variance means that the expression of genes involved in translation, stress and other traits affected by ppGpp and/or RpoS are likely to be strain-specific and suggest that influential components of regulatory networks are frequently reset by microevolution. Different strains of E. coli have different relationships between ppGpp and RpoS levels and only some exhibit a proportionality between increasing ppGpp and RpoS levels as demonstrated for E. coli K-12.

Background: Parkinson's disease (PD) is the most common neurodegenerative movement disease. Human endogenous retroviruses (HERVs) are proviral remnants of ancient retroviral infection of germ cells that now constitute about 8% of the human genome. Under certain disease conditions, HERV genes are activated and partake in the disease process. However, virtually nothing is known about the pathological relationship, if any, between HERV and PD., Objective: The objectives of this study were to unravel the pathological relationship between human endogenous retrovirus K (HERV-K) and PD, determine the localization of HERV-K in the brain, determine whether HERV-K levels are altered in PD brain and blood, and examine whether HERV-K could serve as a biomarker for PD., Methods: In situ HERV-K and glial fibrillary acidic protein (GFAP) expression in the superior frontal and fusiform cortices of PD and control brain were analyzed using immunofluorescence and confocal microscopy. HERV-K load and copy number in PD and control blood were measured by digital droplet polymerase chain reaction and GFAP by single-molecule array. HERV-K load was analyzed in relation to the Hoehn and Yahr Scale and Movement Disorder Society Unified Parkinson's Disease Rating Scale Part III., Results: HERV-K is predominantly expressed in astrocytes and colocalized with astrocytic GFAP, with decreased expression of both HERV-K and GFAP in PD brain compared with controls. Consistent with this, HERV-K levels were decreased in PD blood compared with controls and were correlated to blood GFAP levels. HERV-K levels were inversely correlated to PD severity and duration., Conclusions: These findings suggest that HERV-K is related to astrocyte function and to PD progression, and that HERV-K could be neuroprotective. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society., (© 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.)