Litter quality and the law of the most limiting: Opportunities for restoring nutrient cycles in acidified forest soils.

The adverse effects of soil acidification are extensive and may result in hampered ecosystem functioning. Admixture of tree species with nutrient rich litter has been proposed to restore acidified forest soils and improve forest vitality, productivity and resilience. However, it is common belief that litter effects are insufficiently functional for restoration of poorly buffered sandy soils.

Lessons learned from rapid environmental risk assessments for prioritization of alien species using expert panels.

Limiting the spread and impacts of invasive alien species (IAS) on biodiversity and ecosystems has become a goal of global, regional and national biodiversity policies. Evidence based management of IAS requires support by risk assessments, which are often based on expert judgment. We developed a tool to prioritize potentially new IAS based on their ecological risks, socio-economic impact and feasibility of management using multidisciplinary expert panels.

FEI's direct electron detector developments: Embarking on a revolution in cryo-TEM.

In early 2011 FEI Company launched the "Falcon", its first commercial direct electron detector product intended for application in 3-D electron microscopy in the life sciences. In this paper we discuss the principle of direct electron detection and its implementation in Falcon cameras. We describe the signal formation in the sensor and its impact on the detection quantum efficiency (DQE) of the sensor.

A posteriori correction of camera characteristics from large image data sets.

Large datasets are emerging in many fields of image processing including: electron microscopy, light microscopy, medical X-ray imaging, astronomy, etc. Novel computer-controlled instrumentation facilitates the collection of very large datasets containing thousands of individual digital images. In single-particle cryogenic electron microscopy ("cryo-EM"), for example, large datasets are required for achieving quasi-atomic resolution structures of biological complexes.

Plant quality and local adaptation undermine relocation in a bog specialist butterfly.

The butterfly Boloria aquilonaris is a specialist of oligotrophic ecosystems. Population viability analysis predicted the species to be stable in Belgium and to collapse in the Netherlands with reduced host plant quality expected to drive species decline in the latter. We tested this hypothesis by rearing B.

Molecular architecture of the "stressosome," a signal integration and transduction hub.

A commonly used strategy by microorganisms to survive multiple stresses involves a signal transduction cascade that increases the expression of stress-responsive genes. Stress signals can be integrated by a multiprotein signaling hub that responds to various signals to effect a single outcome. We obtained a medium-resolution cryo-electron microscopy reconstruction of the 1.

Cryo-electron microscopy reveals a novel DNA-binding site on the MCM helicase.

The eukaryotic MCM2-7 complex is recruited at origins of replication during the G1 phase and acts as the main helicase at the replication fork during the S phase of the cell cycle. To characterize the interplay between the MCM helicase and DNA prior to the melting of the double helix, we determined the structure of an archaeal MCM orthologue bound to a 5.6-kb double-stranded DNA segment, using cryo-electron microscopy.

Magnification variations due to illumination curvature and object defocus in transmission electron microscopy.

It has previously been shown that - in theory - magnification variations can occur in an imaging system as a function of defocus, depending on the field curvature of the illuminating system. We here present the results of practical experiments to verify this effect in the transmission electron microscope. We find that with illumination settings typically used in the electron microscopy of biological macromolecules, systematic variations in magnification of ~ 0.