Drebrin (DBN) regulates cytoskeletal functions during neuronal development, and is thought to contribute to structural and functional synaptic changes associated with aging and Alzheimer’s disease. Here we show that DBN coordinates stress signalling with cytoskeletal dynamics, via a mechanism involving kinase ataxia-telangiectasia mutated (ATM). An excess of reactive oxygen species (ROS) stimulates ATM-dependent phosphorylation of DBN at serine-647, which enhances protein stability and accounts for improved stress resilience in dendritic spines. We generated a humanized DBN Caenorhabditis elegans model and show that a phospho-DBN mutant disrupts the protective ATM effect on lifespan under sustained oxidative stress. Our data indicate a master regulatory function of ATM-DBN in integrating cytosolic stress-induced signalling with the dynamics of actin remodelling to provide protection from synapse dysfunction and ROS-triggered reduced lifespan. They further suggest that DBN protein abundance governs actin filament stability to contribute to the consequences of oxidative stress in physiological and pathological conditions.

Sea ice is a key factor for the functioning and services provided by polar marine ecosystems. However, ecosystem responses to sea-ice loss are largely unknown because time-series data are lacking. Here, we use shotgun metagenomics of marine sedimentary ancient DNA off Kamchatka (Western Bering Sea) covering the last ~20,000 years. We traced shifts from a sea ice-adapted late-glacial ecosystem, characterized by diatoms, copepods, and codfish to an ice-free Holocene characterized by cyanobacteria, salmon, and herring. By providing information about marine ecosystem dynamics across a broad taxonomic spectrum, our data show that ancient DNA will be an important new tool in identifying long-term ecosystem responses to climate transitions for improvements of ocean and cryosphere risk assessments. We conclude that continuing sea-ice decline on the northern Bering Sea shelf might impact on carbon export and disrupt benthic food supply and could allow for a northward expansion of salmon and Pacific herring.

<p>Understanding marine ecological systems is a challenging task that requires probing of different comparable states and comprehensive time series analysis. In this approach, we analyze sedimentary ancient DNA recovered from marine sediments which function as an extensive archive of past biota, as they conserve snapshots of the ecological community from the time of its DNA deposition. We examine metagenomic shotgun data from 22 samples as a time series ranging 124 kyrs from a probed sediment core recovered from the Shirshov Ridge in the Bering Sea basin to explore the possibilities of paleometagenomic network analyses. Looking at the presence and abundance of different taxa inhabiting the ocean at certain periods and climatic conditions including (1) the last interglacial (Eemian), (2) the last glacial period, and (3) the modern interglacial (Holocene), we reconstruct and analyze ecological networks and inspect how they have changed and adapted over time. Moreover, by developing extensive network analysis methods including species interaction enrichment and comparable simulation models we evaluate the viability of identifying complex connections and relationships between organisms, as well as the influence of reconstructed environmental factors. Our analysis establishes an initial pipeline for paleometagenomic network analyses and enables further research, e.g. network comparison of multiple marine sites to better understand past ecological mechanisms.</p>