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Given its importance for human health, vegetation and climate, trends in ground-level ozone (O3) concentrations in eastern Germany were systematically analysed using the long-term O3 data from 16 measurement stations. The findings indicate that despite reductions in oxides of nitrogen (NOx= NO + NO2) concentrations across all sites, O3 pollution in Saxony has in fact worsened over the past decade, especially in densely populated urban areas. The strongest O3 trend is observed at a traffic-dominated station, with an annual ozone increase of 1.2 µg m−3 yr−1 (or 3.5 % yr−1), while urban and rural background stations show more moderate rises of, on average, 0.5 µg m−3 yr−1 (or 1.1 % yr−1) over the last decade. To diagnose O3 formation and the controlling effects of NOx and volatile organic compounds (VOCs) over the past decades in this region, for the first time, detailed photochemical box modelling was performed by means of the complex MCM (Master Chemical Mechanism). Analysis of isopleth diagrams for two seasons indicates that O3 formation was predominantly VOC-limited at traffic and urban sites from 2000 to 2019. The observed rise in O3 levels suggests that current efforts to reduce total non-methane volatile organic compound (TNMVOC, including NMVOCs and oxygenated VOCs) emissions and NOx from various sources unfortunately remain insufficient. Based on anthropogenic and biogenic emission data, we recommend that continued NOx abatement and further additional VOC controls, with a focus on solvent use, be implemented in densely populated areas to mitigate O3 pollution in the coming years.

Given its importance for human health, vegetation and climate, trends in ground-level ozone (O.sub.3) concentrations in eastern Germany were systematically analysed using the long-term O.sub.3 data from 16 measurement stations. The findings indicate that despite reductions in oxides of nitrogen (NO.sub.x = NO + NO.sub.2) concentrations across all sites, O.sub.3 pollution in Saxony has in fact worsened over the past decade, especially in densely populated urban areas. The strongest O.sub.3 trend is observed at a traffic-dominated station, with an annual ozone increase of 1.2 µg m.sup.-3 yr.sup.-1 (or 3.5 % yr.sup.-1 ), while urban and rural background stations show more moderate rises of, on average, 0.5 µg m.sup.-3 yr.sup.-1 (or 1.1 % yr.sup.-1) over the last decade.

Given its importance for human health, vegetation and climate, trends in ground-level ozone (O3) concentrations in eastern Germany were systematically analysed using the long-term O3 data from 16 measurement stations. The findings indicate that despite reductions in oxides of nitrogen (NOx= NO + NO2) concentrations across all sites, O3 pollution in Saxony has in fact worsened over the past decade, especially in densely populated urban areas. The strongest O3 trend is observed at a traffic-dominated station, with an annual ozone increase of 1.2 µg m−3 yr−1 (or 3.5 % yr−1), while urban and rural background stations show more moderate rises of, on average, 0.5 µg m−3 yr−1 (or 1.1 % yr−1) over the last decade.To diagnose O3 formation and the controlling effects of NOx and volatile organic compounds (VOCs) over the past decades in this region, for the first time, detailed photochemical box modelling was performed by means of the complex MCM (Master Chemical Mechanism). Analysis of isopleth diagrams for two seasons indicates that O3 formation was predominantly VOC-limited at traffic and urban sites from 2000 to 2019. The observed rise in O3 levels suggests that current efforts to reduce total non-methane volatile organic compound (TNMVOC, including NMVOCs and oxygenated VOCs) emissions and NOx from various sources unfortunately remain insufficient. Based on anthropogenic and biogenic emission data, we recommend that continued NOx abatement and further additional VOC controls, with a focus on solvent use, be implemented in densely populated areas to mitigate O3 pollution in the coming years.

Lipids are increasingly recognized as bioactive mediators of extracellular vesicle (EV) functions. However, while EV proteins and nucleic acids are well described, EV lipids are insufficiently understood due to lack of adequate quantitative methods. We adapted an established targeted and quantitative mass spectrometry (LC-MS/MS) method originally developed for analysis of 94 eicosanoids and seven polyunsaturated fatty acids (PUFA) in human plasma. Additionally, the influence of freeze–thaw (FT) cycles, injection volume, and extraction solvent were investigated. The modified protocol was applied to lipidomic analysis of differently polarized macrophage-derived EVs. We successfully quantified three PUFAs and eight eicosanoids within EVs. Lipid extraction showed reproducible PUFA and eicosanoid patterns. We found a particularly high impact of FT cycles on EV lipid profiles, with significant reductions of up to 70%. Thus, repeated FT will markedly influence analytical results and may alter EV functions, emphasizing the importance of a standardized sample pretreatment protocol for the analysis of bioactive lipids in EVs. EV lipid profiles differed largely depending on the polarization of the originating macrophages. Particularly, we observed major changes in the arachidonic acid pathway. We emphasize the importance of a standardized sample pretreatment protocol for the analysis of bioactive lipids in EVs.

Seeds preserve a far developed plant embryo in a quiescent state. Seed metabolism relies on stored resources and is reactivated to drive germination when the external conditions are favorable. Since the switchover from quiescence to reactivation provides a remarkable case of a cell physiological transition we investigated the earliest events in energy and redox metabolism of Arabidopsis seeds at imbibition. By developing fluorescent protein biosensing in intact seeds, we observed ATP accumulation and oxygen uptake within minutes, indicating rapid activation of mitochondrial respiration, which coincided with a sharp transition from an oxidizing to a more reducing thiol redox environment in the mitochondrial matrix. To identify individual operational protein thiol switches, we captured the fast release of metabolic quiescence in organello and devised quantitative iodoacetyl tandem mass tag (iodoTMT)-based thiol redox proteomics. The redox state across all Cys peptides was shifted toward reduction from 27.1% down to 13.0% oxidized thiol. A large number of Cys peptides (412) were redox switched, representing central pathways of mitochondrial energy metabolism, including the respiratory chain and each enzymatic step of the tricarboxylic acid (TCA) cycle. Active site Cys peptides of glutathione reductase 2, NADPH-thioredoxin reductase a/b, and thioredoxin-o1 showed the strongest responses. Germination of seeds lacking those redox proteins was associated with markedly enhanced respiration and deregulated TCA cycle dynamics suggesting decreased resource efficiency of energy metabolism. Germination in aged seeds was strongly impaired. We identify a global operation of thiol redox switches that is required for optimal usage of energy stores by the mitochondria to drive efficient germination.

Mitochondrial architecture and the contacts between the outer and the inner mitochondrial membrane depend on the mitochondrial contact site and cristae organizing system (MICOS) that is highly conserved from yeast to human. Mutations in the mammalian MICOS subunit Mic14/CHCHD10 have been linked to amyotrophic lateral sclerosis and frontotemporal dementia, indicating the importance of this protein. Mic14/CHCHD10 has a yeast ortholog, Mix17, a protein of unknown function, which has not been shown to interact with MICOS so far. As a first step to elucidate the function of Mix17 and its orthologs, we analyzed its interactions, biogenesis and mitochondrial sublocation. We report that Mix17 is no stable MICOS subunit in yeast. Our data suggest that Mix17 is the first Mia40 substrate in the mitochondrial outer membrane. Unlike all other Mia40 substrates, Mix17 spans the outer membrane and exposes its N-terminus to the cytosol. The insertion of Mix17 is likely to be mediated by its interaction with Tom40, the pore of the TOM complex. Moreover, we show that the exposure of Mix17 to the cytosolic side of the membrane depends on its N-terminus.Competing Interest StatementThe authors have declared no competing interest.Footnotes* The results section was updated to test for the interaction of Mix17 and the MICOS complex (revised Fig.1). Moreover, we provide the quantification of the experiment shown in revised Fig. 3A (former Fig. 2A) to substantiate the result. In addition, we further investigated the association of Mix17 and Tom40 (revised Fig. 7C).

Seeds preserve a far developed plant embryo in a quiescent state. Seed metabolism relies on stored resources and is re-activated to drive germination when the external conditions are favorable. Since the switchover from quiescence to re-activation provides a remarkable case of a cell physiological transition we investigated the earliest events in energy and redox metabolism of Arabidopsis seeds at imbibition. By developing fluorescent protein biosensing in intact seeds, we observed ATP accumulation and oxygen uptake within minutes, indicating rapid activation of mitochondrial respiration, which coincided with a sharp transition from an oxidizing to a more reducing thiol redox environment in the mitochondrial matrix. To identify individual operational protein thiol switches, we captured the fast release of metabolic quiescence in organello and devised quantitative iodoacetyl tandem mass tag-based (iodoTMT) thiol redox proteomics. The redox state across all Cys-peptides was shifted towards reduction from 27.1 % to 13.0 %. A large number of Cys-peptides (412) were redox-switched, representing central pathways of mitochondrial energy metabolism, including the respiratory chain and each enzymatic step of the tricarboxylic acid cycle (TCA). Active site Cys-peptides of glutathione reductase 2, NADPH-thioredoxin reductase a/b and thioredoxin-o1 showed the strongest responses. Germination of seeds lacking those redox proteins was associated with markedly enhanced respiration and deregulated TCA cycle dynamics suggesting decreased resource efficiency of energy metabolism. Germination in aged seeds was strongly impaired. We identify a global operation of thiol redox switches that is required for optimal usage of energy stores by the mitochondria to drive efficient germination.