Andreas Walter

Aging is one of the most fundamental, yet least understood biological processes that affect all forms of eukaryotic life. Mitochondria are intimately involved in aging, but the underlying molecular mechanisms are largely unknown. Electron cryotomography of whole mitochondria from the aging model organism Podospora anserina revealed profound age-dependent changes in membrane architecture. With increasing age, the typical cristae disappear and the inner membrane vesiculates. The ATP synthase dimers that form rows at the cristae tips dissociate into monomers in inner-membrane vesicles, and the membrane curvature at the ATP synthase inverts. Dissociation of the ATP synthase dimer may involve the peptidyl prolyl isomerase cyclophilin D. Finally, the outer membrane ruptures near large contact-site complexes, releasing apoptogens into the cytoplasm. Inner-membrane vesiculation and dissociation of ATP synthase dimers would impair the ability of mitochondria to supply the cell with sufficient ATP to maintain essential cellular functions.

Significance The growing human population generates increasing demand for food and energy. Microalgae are a promising source of sustainable bioproducts whose production may not exacerbate worsening environmental problems. The green alga Chromochloris zofingiensis has potential as a biofuel feedstock and source of high-value nutraceutical molecules, including the carotenoid astaxanthin. We present a high-quality, chromosome-level assembly of the genome by using a hybrid sequencing approach with independent validation by optical mapping. Our analyses of the genome and transcriptome, in addition to experiments characterizing astaxanthin production, advance understanding of the green lineage and carotenoid production, and enhance prospects for improving commercial production of C. zofingiensis.

Abstract This paper analyses the trading activity of German mutual funds in the 1998–2002 period to investigate whether German mutual fund managers are engaged in herding behaviour. Another objective of the study is to determine the impact of this herd‐like trading on stock prices. Our results provide evidence of herding and positive feedback trading by German mutual fund managers. We show that a significant portion of herding detected in the German market is associated with spurious herding as a consequence of changes in benchmark index composition. Investigating the impact of mutual fund herding on stock prices, we find that herding seems to neither destabilise nor stabilise stock prices.

The frontiers of bioimaging are currently being pushed towards the integration and correlation of several modalities to tackle biomedical research questions holistically and across multiple scales. Correlated Multimodal Imaging (CMI) gathers information about exactly the same specimen with two or more complementary modalities that – combined – create a composite and complementary view of the sample (including insights into structure, function, dynamics and molecular composition). CMI allows to describe biomedical processes within their overall spatio-temporal context and gain a mechanistic understanding of cells, tissues, diseases or organisms by untangling their molecular mechanisms within their native environment. The two best-established CMI implementations are hardware-fused platforms in (Pre)clinical Imaging (Hybrid Imaging) and Correlated Light and Electron Microscopy (CLEM) in biological imaging. Although the merits of Hybrid Imaging and CLEM are well established, both approaches would benefit from standardization of protocols, ontologies and data handling, and the development of optimized and advanced implementations. Specifically, CMI pipelines that aim at bridging preclinical and biological imaging beyond CLEM and Hybrid Imaging are rare but bear great potential to substantially advance both bioimaging and biomedical research. CMI faces three main challenges for its routine use in biomedical research: (1) Sample handling and preparation procedures that are compatible across modalities without compromising data quality, (2) soft- and hardware solutions to relocate the same region of interest (ROI) after transfer between imaging platforms including fiducial markers, and (3) automated software solutions to correlate complex, multiscale, multimodal and volumetric image data including reconstruction, segmentation and visualization. This review goes beyond preclinical imaging and puts its accessible information into a broader imaging context. We present a comprehensive overview of the field of CMI from PHI to correlative microscopy, highlight requirements for optimization and standardization, present a synopsis of current solutions to challenges of the field and focus on current efforts to bridge the gap between preclinical and biological imaging. The review is line with major European initiatives, such as COMULIS (CA17121), a COST Action to promote and foster Correlated Multimodal Imaging in Life Sciences.