Aging of biological systems is influenced by various factors, conditions and processes. Among others, processes allowing organisms to deal with various types of stress are of key importance. In particular, oxidative stress as the result of the generation of reactive oxygen species (ROS) at the mitochondrial respiratory chain and the accumulation of ROS-induced molecular damage has been strongly linked to aging. Here we view the impact of ROS from a different angle: their role in the control of gene expression. We report a genome-wide transcriptome analysis of the fungal aging model Podospora anserina grown on medium containing paraquat (PQ). This treatment leads to an increased cellular generation and release of H2O2, a reduced growth rate, and a decrease in lifespan. The combined challenge by PQ and copper has a synergistic negative effect on growth and lifespan. The data from the transcriptome analysis of the wild type cultivated under PQ-stress and their comparison to those of a longitudinal aging study as well as of a copper-uptake longevity mutant of P. anserina revealed that PQ-stress leads to the up-regulation of transcripts coding for components involved in mitochondrial remodeling. PQ also affects the expression of copper-regulated genes suggesting an increase of cytoplasmic copper levels as it has been demonstrated earlier to occur during aging of P. anserina and during senescence of human fibroblasts. This effect may result from the induction of the mitochondrial permeability transition pore via PQ-induced ROS, leading to programmed cell death as part of an evolutionary conserved mechanism involved in biological aging and lifespan control.

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Cornelia Kenneweg und Matthias Wiemer stellen in ihrem Beitrag das Threshold Concept Framework (TCF) vor und erläutern, wie es wissenschaftsdidaktische Fragestellungen bereichern kann. Das TCF bietet einen Erklärungsansatz, wie sich der Zugang zu Wissenschaft und wissenschaftlichen Disziplinen als Aneignungsprozess von Begriffen und als Konstruktion individueller und intersubjektiver Begriffsräume verstehen lässt. Der Ansatz kann Hochschullehrenden zudem eine wissenschaftlich reflektierende Auseinandersetzung mit dem eigenen Fach ermöglichen und den Austausch von Lehrenden, Hochschuldidaktiker:innen und Studierenden befördern. Als mögliche Anknüpfungspunkte für die Wissenschaftsdidaktik werden das transformative Potential von Threshold Concepts, ihre Rolle in professionellen Lehr-/Lerngemeinschaften sowie der ihnen inhärente Umgang mit unsicherem Wissen und Ungewissheit(en) betrachtet.

The degradation of damaged proteins is an important vital function especially during aging and stress. The ubiquitin proteasome system is one of the major cellular machineries for protein degradation. Health and longevity are associated with high proteasome activity. To demonstrate such a role in aging of Podospora anserina, we first analyzed the transcript and protein abundance of selected proteasome components in wild-type cultures of different age. No significant differences were observed. Next, in order to increase the overall proteasome abundance we generated strains overexpressing the catalytic proteasome subunits PaPRE2 and PaPRE3. Although transcript levels were strongly increased, no substantial effect on the abundance of the corresponding proteins was observed. Finally, the analysis of the P. anserina strains expressing the sequence coding for the CL1 degron fused to the Gfp gene revealed no evidence for degradation of the GFP-CL1 fusion protein by the proteasome. Instead, our results demonstrate the degradation of the CL1-degron sequence via autophagy, indicating that basal autophagy appears to be a very effective protein quality control pathway in P. anserina.

Zusammenfassung Studierende in soziale Prozesse einzubinden ist ein zentrales Argument für Forschendes Lernen im Studium. Dabei können unterschiedliche Bildungsziele in den Fokus rücken, die eine je eigene Perspektive auf Gemeinschaftsbildungsprozesse erfordern. Der Beitrag geht diesen verschiedenen Perspektiven nach und zeigt, welche Herausforderungen und Chancen sich aus einer differenzierten Betrachtung der unterschiedlichen Verwirklichungen von Gemeinschaft für die Lehrpraxis ergeben.

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