11. Mitochondria can substitute for parvalbumin to lowercytosolic calcium levels in the murine fast skeletal muscleLorenzo Marcucci, Leonardo Nogara, Marta Canato, Elena Germinario, Anna Raffaello, Michela Carraro, Paolo Bernardi, Laura Pietrangelo, Simona Boncompagni, Feliciano Protasi, Nazareno Paolocci, Carlo Reggiani, 2024, original scientific article Abstract: Aim: Parvalbumin (PV) is a primary calcium buffer in mouse fast skeletal musclefibers. Previous work showed that PV ablation has a limited impact on cytosolicCa2+ ([Ca2+]cyto) transients and contractile response, while it enhances mitochon-drial density and mitochondrial matrix-free calcium concentration ([Ca2+]mito).Here, we aimed to quantitatively test the hypothesis that mitochondria act tocompensate for PV deficiency.Methods: We determined the free Ca 2+ redistribution during a 2 s 60 Hz tetanicstimulation in the sarcoplasmic reticulum, cytosol, and mitochondria. Via a re-action–diffusion Ca 2+ model, we quantitatively evaluated mitochondrial uptakeand storage capacity requirements to compensate for PV lack and analyzed pos-sible extracellular export.Results: [Ca 2+]mito during tetanic stimulation is greater in knock-out (KO)(1362 ± 392 nM) than in wild-type (WT) (855 ± 392 nM), p < 0.05. Under the as-sumption of a non-linear intramitochondrial buffering, the model predicts an ac-cumulation of 725 μmoles/Lfiber (buffering ratio 1:11 000) in KO, much higherthan in WT (137 μmoles/Lfiber, ratio 1:4500). The required transport rate via mi-tochondrial calcium uniporter (MCU) reaches 3 mM/s, compatible with availableliterature. TEM images of calcium entry units and Mn2+ quenching showed a greater capacity of store- operated calcium entry in KO compared to WT. However,levels of [Ca 2+]cyto during tetanic stimulation were not modulated to variations ofextracellular calcium.Conclusions: The model-based analysis of experimentally determined calciumdistribution during tetanic stimulation showed that mitochondria can act as abuffer to compensate for the lack of PV. This result contributes to a better under-standing of mitochondria's role in modulating [Ca2+]cyto in skeletal muscle fibers.
Keywords: calcium, mitochondria, mouse skeletal muscle fibers, parvalbumin, reaction-diffusion model
Published in DiRROS: 13.11.2024; Views: 86; Downloads: 54
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12. Spaceflight on the ISS changed the skeletal muscle proteome of two astronautsMarta Murgia, Joern Rittweger, Carlo Reggiani, Roberto Bottinelli, Matthias Mann, Stefano Schiaffino, Marco Vicenzo Narici, 2024, original scientific article Abstract: Skeletal muscle undergoes atrophy and loss of force during long space missions, when astronauts are persistently exposed to altered gravity and increased ionizing radiation. We previously carried out mass spectrometry-based proteomics from skeletal muscle biopsies of two astronauts, taken before and after a mission on the International Space Station. The experiments were part of an effort to find similarities between spaceflight and bed rest, a ground-based model of unloading, focused on proteins located at the costameres. We here extend the data analysis of the astronaut dataset and show compartment-resolved changes in the mitochondrial proteome, remodeling of the extracellular matrix and of the antioxidant response. The astronauts differed in their level of onboard physical exercise, which correlated with their respective preservation of muscle mass and force at landing in previous analyses. We show that the mitochondrial proteome downregulation during spaceflight, particularly the inner membrane and matrix, was dramatic for both astronauts. The expression of autophagy regulators and reactive oxygen species scavengers, however, showed partially opposite expression trends in the two subjects, possibly correlating with their level of onboard exercise. As mitochondria are primarily affected in many different tissues during spaceflight, we hypothesize that reactive oxygen species (ROS) rather than mechanical unloading per se could be the primary cause of skeletal muscle mitochondrial damage in space. Onboard physical exercise might have a strong direct effect on the prevention of muscle atrophy through mechanotransduction and a subsidiary effect on mitochondrial quality control, possibly through upregulation of autophagy and anti-oxidant responses.
Keywords: skeletal muscles, microgravity, muscle atrophy, autophagy
Published in DiRROS: 12.11.2024; Views: 104; Downloads: 56
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13. Predlog metodologije za spremljanje stanja gozdov za l. 2025 : predlog metodologije v skladu s Pravilnikom o varstvu gozdov (2009) in mednarodnimi zavezami (Konvencija UNECE CLRTAP)Daniel Žlindra, Lado Kutnar, Tom Levanič, Anže Martin Pintar, Urša Vilhar, Primož Simončič, 2024, treatise, preliminary study, study Keywords: monitoring, stanje gozdov, osutost dreves, poškodovanost dreves, rast dreves, meteorološke meritve, ozon, pritalna vegetacija, fenološka opazovanja, foliarni popis, zračne usedline
Published in DiRROS: 12.11.2024; Views: 87; Downloads: 0
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15. Label-free and sensitive detection of Citrus Bark Cracking Viroid in hop using ▫$Ti_3C_2T_x$▫ MXene-modified genosensorAlnilan Cristina Barros Lobato, Ivan Konjević, Sebastjan Radišek, Jernej Jakše, Helena Volk, Monika Hermanová, Miroslav Fojta, Jan Paštika, Zdeněk Sofer, Rui Gusmão, Samo B. Hočevar, Nikola Tasić, 2025, original scientific article Published in DiRROS: 12.11.2024; Views: 103; Downloads: 50
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17. Three decades of understorey vegetation change in Quercus-dominated forests as a result of increasing canopy mortality and global change symptomsJanez Kermavnar, Lado Kutnar, 2024, original scientific article Abstract: Questions The long-term response of understorey vegetation to increasing tree mortality has rarely been addressed in resurvey studies. For two Quercus-dominated forest types, we asked: (a) How did overstorey alterations, induced by canopy mortality, affect understorey diversity and composition? (b) Is there a signal of global change effects on understorey communities? (c) Are these assemblages experiencing a homogenization process? Location Five sites in Quercus robur (QR) and four sites in Q. petraea (QP) forests, Slovenia. Methods We studied changes in vascular plants in the understorey layer from 1992/1993 to 2023 across 45 permanent 20 m × 20 m plots in QR and QP forests, respectively. Vegetation surveys were carried out following the standard Braun-Blanquet method. We compared original surveys with recent resurveys using multivariate analysis, ecological indicator values (EIV), plant traits and methods that quantify changes in individual species. Results Since the early 1990s, tree layer cover decreased from 95% to an average of 55% in QR, whereas it remained relatively high (77%) in QP plots. This resulted in denser understorey vegetation and a significant increase in plot-level species richness in QR forests, but a slight decrease in QP forests. The extensive loss of canopy cover and disturbance effects in QR forests caused significant changes in species composition. Species turnover in QR was driven by colonization of new disturbance-tolerant taxa characterized by ruderal traits, whereas the compositional shift in QP was to a greater extent due to species losses. We detected a process of vegetation thermophilization (increase in EIV-temperature), suggesting an effect of rapid climatic warming. Understorey communities are now more similar to each other than 30 years ago, indicating a decrease in beta-diversity (floristic homogenization). Conclusions Despite some common trends, vegetation responses were forest type-specific. Our study presents evidence of understorey vegetation changes triggered by increased canopy mortality (a strong local driver particularly in QR plots) and also points to the signal of global change symptoms (thermophilization, homogenization), which acted rather independently from the observed decline in tree layer cover.
Keywords: floristic homogenization, forest disturbances, permanent vegetation plots, Quercus robur, Quercus petraea, resurvey study, Slovenia, thermophilization, tree layer cover
Published in DiRROS: 11.11.2024; Views: 104; Downloads: 48
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