Nature Communications最新文献

Dynamo action refers to energy exchange processes through which magnetic fields are generated at the expense of kinetic energy of the plasma flows. Dynamos can generate magnetic fields across scales larger or smaller than the flows themselves. Multi-scale dynamo processes underpin magnetic phenomena from planetary cores to stellar and galactic environments, while also shaping turbulent magnetic fields at smaller scales. Yet, experimental validation of dynamo action has remained largely confined to laboratories. Here we report evidence for a turbulent dynamo in the terrestrial magnetosheath. Observations reveal the predicted spatial topology of stretched and folded magnetic fields, compressive effects, and pressure anisotropy instabilities essential for magnetic field amplification. Our findings also highlight the central role of turbulent dynamos in energy conversion and structure formation within collisionless plasma turbulence. The observed energy exchange signatures indicate that the magnetosheath may serve as a natural testbed for validating dynamo theories and simulations.

Oestrogen receptor (ER) activation leads to the formation of DNA double strand breaks (DSB), promoting genomic instability and tumour heterogeneity. The single-stranded DNA cytosine deaminase APOBEC3B (A3B) serves as a co-activator of ER and is implicated in inducing DSBs at transcriptional enhancers regulated by ER. Using whole-genome sequencing in an engineered cell model lacking base excision repair (BER) function, we demonstrate that A3B preferentially targets transcriptionally active regulatory regions in an R-loop-dependent manner. Strand-specific DNA:RNA immunoprecipitation sequencing (ssDRIP-seq) and ssDNA-associated protein immunoprecipitation sequencing (SPI-seq) confirm that A3B binds to and deaminates ssDNA within R-loops, a process facilitated by ER transactivation. Furthermore, BER-mediated processing of A3B-induced uracil bases contributes to the formation of R-loop-associated DSBs, which are essential for ER-regulated gene activation. These findings establish a role for A3B in R-loop homeostasis and transcriptional regulation, with implications for understanding ER-driven genomic instability and potential therapeutic targeting of A3B.

The sustainable synthesis on ammonia at mild thermal conditions is a pivotal goal in catalysis, yet finding efficient alternatives to the energy-intensive Haber-Bosch process remains a great challenge. Here we show that a composite material comprising uranium and few-layer graphdiyne (U/GDY) catalyzes ammonia production with high efficiency at low temperature and pressure. We synthesize few-layer GDY in supercritical CO₂ to create a stable scaffold that hosts uranium in specific valency and cluster states. Both experimental results and theoretical calculations reveal that the unique electronic interplay between the 5 f electrons of uranium and the conjugated structure of GDY optimizes the adsorption and activation of nitrogen. This synergism facilitates a favorable reaction pathway involving specific nitrogen recognition and efficient product release. Our findings demonstrate the potential of uranium-based composites in catalysis and offer a strategy for designing actinide-carbon hybrid materials in challenging chemical transformations.

Global declines in coastal habitats and wildlife have devastating consequences for Indigenous Peoples. In some places, hydropower development has environmental impacts that contribute significantly to coastal habitat loss. As development is rejuvenated for the carbon-neutral transition, mitigation of further coastal habitat impacts depends on assessing the relative and interactive effects of climate change and hydropower development. Here, we follow a detection and attribution framework to understand the collapse and limited recovery of a social-ecological system including eelgrass (Zostera marina, shikaapaashkw), geese (Branta spp., nisk and iyiwaapuwaau), and Cree (Eeyou) in subarctic eastern James Bay, Canada (Eeyou Istchee). Informed by historical observations, Indigenous knowledge, and scientific research, we attribute the collapse of eelgrass and shifts in the associated social-ecological system to ecological effects of hydroelectric development (1978-1996), which degraded local environments causing eelgrass declines. Climate-driven extreme events (1998 onward) compounded losses and ecological feedbacks extended eelgrass declines all along the coast. Eelgrass recovery today appears limited by poor water clarity, altered sediments, hydrologic changes from development, and a new climate regime. Eeyou have adapted by shifting their relationships with the coastal habitat. Comprehensive assessments for hydropower developments should explicitly consider coastal social-ecological dynamics and the possible compounding impacts of climate change.