Changes in axonal myelination are an important hallmark of aging and a number of neurological diseases. Demyelinated axons are impaired in their function and degenerate over time. Oligodendrocytes, the cells responsible for myelination of axons, are sensitive to mechanical properties of their environment. Growing evidence indicates that mechanical properties of demyelinating lesions are different from the healthy state and thus have the potential to affect myelinating potential of oligodendrocytes. We performed a high-resolution spatial mapping of the mechanical heterogeneity of demyelinating lesions using atomic force microscope-enabled indentation. Our results indicate that the stiffness of specific regions of mouse brain tissue is influenced by age and degree of myelination. Here we specifically demonstrate that acquired acute but not genetic demyelination leads to decreased tissue stiffness, which could influence the remyelination potential of oligodendrocytes. We also demonstrate that specific brain regions have unique ranges of stiffness in white and grey matter. Our ex vivo findings may help the design of future in vitro models to mimic the mechanical environment of the brain in healthy and diseased states. The mechanical properties of demyelinating lesions reported here may facilitate novel approaches in treating demyelinating diseases such as multiple sclerosis. Mechanical characteristics of a cell's environment can have a profound influence on its biological properties. Neuronal and glial cells are sensitive to mechanical input during development, in disease and regeneration. Sustained tensile strain can promote differentiation of oligodendrocyte progenitor cells into mature oligodendrocytes, which are responsible for the myelination of axons. Changing myelination is an important hallmark in human aging and disease, such as multiple sclerosis. Our hypothesis is that these diseases might be characterized by altered tissue stiffness and that this has an influence on remyelination potential. Here we investigate tissue stiffness profiles of healthy, aged and disease model mice. Manipulating the tissue stiffness might be another promising approach for new treatments.
Abstract Marketed as a healthier alternative to soft wheat, spelt ( Triticum aestivum ssp. spelta) is in increasing demand from consumers and bakers in Switzerland. The Swiss spelt landscape is currently dominated by two varieties – Ostro and Oberkulmer Rotkorn – considered as references for Swiss “typical” spelt. However, these two varieties are rather old and deliver low yields; the market therefore needs improved spelt varieties with higher agronomic potential while keeping the essential attributes of typical spelt. As spelt and winter wheat can be interbred, modern spelt varieties often result from crosses between the two. It has therefore become increasingly difficult to distinguish between typical spelt and modern wheat-spelt intercrosses. This project aims to clarify the phenotypic distinction between typical spelt and modern wheat-spelt intercrosses in the Swiss context. To do this, we performed field trials with 50 spelt varieties, including typical and modern cultivars from Switzerland and Central Europe. We measured agronomic, rheological and nutritional parameters of each variety. In addition, these cultivars were genotyped using a 25K Illumina Wheat SNP array. This allowed us to identify which phenotypic parameters were associated with genetic proximity to typical spelt. Swiss typical spelt varieties were characterized by highly extensible doughs, later phenology, low harvest index, high thousand kernel weights, and lower Zeleny/protein ratio. By linking phenotypic characteristics, easily measurable in fields, to the underlying genetic information of each variety, these results will help to better classify spelt varieties in Switzerland and pave the way for more clarity and transparency on the Swiss spelt market.
Abstract Although the development and application of nanomaterials is a growing industry, little data is available on the ecotoxicological effects on aquatic organisms. Therefore, we set up a workflow to address the potential uptake of weathered multi-walled carbon nanotubes (wMWCNTs) by a model organism, the pulmonary mud snail Lymnaea stagnalis ( L. stagnalis ), which plays an important role in the food web. It represents a suitable organism for this approach because as a grazer it potentially ingests large amounts of sedimented wMWCNTs. As food source for L. stagnalis , benthic biofilm was investigated by the use of a transmission electron microscope (TEM) and a scanning electron microscope (SEM) after exposure with wMWCNTs. In addition, isotopic labeling was applied with 14 C-wMWCNTs (0.1 mg/L) to quantify fate, behavior, and enrichment of 14 C-wMWCNTs in benthic biofilm and in L. stagnalis . Enrichment in benthic biofilm amounted to 529.0 µg wMWCNTs/g dry weight and in L. stagnalis to 79.6 µg wMWCNTs/g dry weight. A bioconcentration factor ( BCF ) for L. stagnalis was calculated (3500 L/kg). We demonstrate the accumulation of wMWCNTs (10 mg/L) in the digestive tract of L. stagnalis in an effect study. Moreover, the physiological markers glycogen and triglycerides as indicators for the physiological state, as well as the RNA/DNA ratio as growth indicator, were examined. No significant differences between exposed and control animals were analyzed for glycogen and triglycerides after 24 days of exposure, but a decreasing trend is recognizable for triglycerides. In contrast, the significant reduction in the RNA/DNA ratio of L. stagnalis indicated an inhibition of growth with a following recovery after depuration. The described workflow enables a comprehensive determination of the fate and the behavior of wMWCNTs specifically and in general all kinds of CNTs in the aquatic environment and therefore contributes to a holistic risk assessment of wMWCNTs.
Zebrafish faithfully regenerate their fins after amputation which includes restoration of bone tissue and a component of cell plasticity. It is currently unclear how different cell populations of the regenerate divide labor to allow for efficient regenerate growth and proper patterning. Here, we studied lineage relationships of FACS-enriched epidermal, blastemal and bone forming fin regenerate cells by single cell (sc) RNA sequencing, lineage tracing, targeted osteoblast ablation and electron microscopy to show that the majority of osteoblasts in the outgrowing regenerate derive from osterix+ osteoblasts, while mmp9+ cells give rise to a limited cell number at the fin segment joints. A third population of distal blastema cells contributes to distal osteoblast progenitors, suggesting compartmentalization during appendage regeneration. Fin elongation and bone formation are carried out by distinct regenerate cell populations, and these variably depend on Fgf signaling. Ablation of osterix+ osteoblasts irreversibly impairs patterning of segment joints, and prevents bone matrix formation in the proximal regenerate. The resulting reduced regenerate length is partially compensated for by the distal regenerate which shows increased Wnt signaling activity. Surprisingly, ablation of joint cells does not abolish the formation of segment joints. Our study characterizes rare fin regenerate cell populations, indicates intricate osteoblast-blastema lineage relationships, inherent detection and compensation of impaired regeneration, and demonstrates zonation of the elongating regenerate. Furthermore, it sheds light on the variable dependence of bone formation on growth factor signaling.
In T cells, processes such as migration and immunological synapse formation are accompanied by the dynamic reorganization of the actin cytoskeleton, which has been suggested to be mediated by regulators of RhoGTPases and by F-actin bundlers. SWAP-70 controls F-actin dynamics in various immune cells, but its role in T cell development and function has remained incompletely understood. CD4 + regulatory T (Treg) cells expressing the transcription factor Foxp3 employ diverse mechanisms to suppress innate and adaptive immunity, which is critical for maintaining immune homeostasis and self-tolerance. Here, we propose Swap-70 as a novel member of the Foxp3-dependent canonical Treg cell signature. We show that Swap-70 -/- mice have increased numbers of Foxp3 + Treg cells with an effector/memory-like phenotype that exhibit impaired suppressor function in vitro , but maintain overall immune homeostasis in vivo . Upon formation of an immunological synapse with antigen presenting cells in vitro , cytosolic SWAP-70 protein is selectively recruited to the interface in Treg cells. In this context, Swap-70 -/- Treg cells fail to downregulate CD80/CD86 on osteoclast precursor cells by trans-endocytosis and to efficiently suppress osteoclastogenesis and osteoclast function. These data provide first evidence for a crucial role of SWAP-70 in Treg cell biology and further highlight the important non-immune function of Foxp3 + Treg cells in bone homeostasis mediated through direct SWAP-70-dependent mechanisms.
Einleitung und Ziele Das intestinale Epithel spielt eine zentrale Rolle in der Resorption von Nahrungsbestandteilen sowie der Erhaltung der intestinalen Barrierefunktion und der Prävention intestinaler Entzündung. In der vorliegenden Arbeit untersuchten wir die Bedeutung von SETDB1, einer Histon-Methyltransferase die zur Heterochromatin-Bildung und Repression der Genexpression beiträgt, in der intestinalen Homöostase und bei chronisch-entzündlichen Darmerkrankungen (CED).
Zebrafish regenerate their fins which involves a component of cell plasticity. It is currently unclear how regenerate cells divide labor to allow for appropriate growth and patterning. Here, we studied lineage relationships of fluorescence-activated cell sorting-enriched epidermal, bone-forming (osteoblast), and (non-osteoblast) blastemal fin regenerate cells by single-cell RNA sequencing, lineage tracing, targeted osteoblast ablation, and electron microscopy. Most osteoblasts in the outgrowing regenerate derive from osterix+ osteoblasts, while mmp9+ cells reside at segment joints. Distal blastema cells contribute to distal osteoblast progenitors, suggesting compartmentalization of the regenerating appendage. Ablation of osterix+ osteoblasts impairs segment joint and bone matrix formation and decreases regenerate length which is partially compensated for by distal regenerate cells. Our study characterizes expression patterns and lineage relationships of rare fin regenerate cell populations, indicates inherent detection and compensation of impaired regeneration, suggests variable dependence on growth factor signaling, and demonstrates zonation of the elongating fin regenerate.
Microtubules play a major role in intracellular trafficking of vesicles in endocrine cells. Detailed knowledge of microtubule organization and their relation to other cell constituents is crucial for understanding cell function. However, their role in insulin transport and secretion is currently under debate. Here, we use F ib -S em to image islet beta cells in their entirety with unprecedented resolution. We reconstruct mitochondria, Golgi apparati, centrioles, insulin secretory granules and micro-tubules of seven beta cells, and generate a comprehensive spatial map of microtubule-organelle interactions. We find that micro-tubules form non-radial networks that are predominantly not connected to either centrioles or endomembranes. Microtubule number and length, but not microtubule polymer density, vary with glucose stimulation. Furthermore, insulin secretory granules are enriched near the plasma membrane where they associate with microtubules. In summary, we provide the first 3D reconstructions of complete microtubule networks in primary mammalian cells together with evidence regarding their importance for insulin secretory granule positioning and thus supportive role in insulin secretion.
