Proteolysis inhibition by hibernating bear serum leads to increased protein content in human muscle cells

Muscle atrophy is one of the main characteristics of human ageing and physical inactivity, with resulting adverse health outcomes. To date, there are still no efficient therapeutic strategies for its prevention and/or treatment. However, during hibernation, bears exhibit a unique ability for preserving muscle in conditions where muscle atrophy would be expected in humans. Therefore, our objective was to determine whether there are components of bear serum which can control protein balance in human muscles. In this study, we exposed cultured human differentiated muscle cells to bear serum collected during winter and summer periods, and measured the impact on cell protein content and turnover. In addition, we explored the signalling pathways that control rates of protein synthesis and degradation. We show that the protein turnover of human myotubes is reduced when incubated with winter bear serum, with a dramatic inhibition of proteolysis involving both proteasomal and lysosomal systems, and resulting in an increase in muscle cell protein content. By modulating intracellular signalling pathways and inducing a protein sparing phenotype in human muscle cells, winter bear serum therefore holds potential for developing new tools to fight human muscle atrophy and related metabolic disorders

Human shields mediate sexual conflict in a top predator - Data

Text file containing GPS reloaction data linked to spatial covariates and bear metadata. Note that the continuous variables are already scaled

Resource selection by sympatric free-ranging dairy cattle and brown bears

Livestock depredation is an important factor that contributes to low public acceptance of large carnivores, and is often used as an incentive to reduce large carnivore populations. In central Sweden, brown bears (Ursus arctos) coexist with a traditional cattle husbandry system that allows daytime free-ranging of dairy cattle. Despite a growing brown bear population, depredation on cattle remained stable during the last decade, and among the lowest rates reported worldwide. Nevertheless, major stakeholders argue for a substantial reduction in brown bear numbers, among other reasons, to safeguard this traditional husbandry system. Based on satellite tracking data, we assessed and correlated the resource selection of nine brown bears that were sympatric with six daytime free-ranging cattle herds during the free-ranging season (June-August) in 2008. We found a significant and negative relationship between resource selection of brown bears and free ranging cattle during the study period, mainly because of inverse relationships between the species towards vegetation density and human-related infrastructure, such as forest roads, buildings, and settlements. We predict that the probability of an encounter between these species, given that there is no directed predation, is highest in dense vegetation patches close to these human habitation-related variables. Because of the low reported depredation rates and the apparent habitat segregation between the species, our results provide no support for the argument to reduce brown bear numbers to safeguard this traditional cattle herding system