Transient signal generation in a self-assembled nanosystem fueled by ATP

A fundamental difference exists in the way signal generation is dealt with in natural and synthetic systems. While nature uses the transient activation of signalling pathways to regulate all cellular functions, chemists rely on sensory devices that convert the presence of an analyte into a steady output signal. The development of chemical systems that bear a closer analogy to living ones (that is, require energy for functioning, are transient in nature and operate out-of-equilibrium) requires a paradigm shift in the design of such systems. Here we report a straightforward strategy that enables transient signal generation in a self-assembled system and show that it can be used to mimic key features of natural signalling pathways, which are control over the output signal intensity and decay rate, the concentration-dependent activation of different signalling pathways and the transient downregulation of catalytic activity. Overall, the reported methodology provides temporal control over supramolecular processe

Why regionality is an important value in organic agriculture: the case of the Netherlands

Organic agriculture is a system of production and consumption in which values play a prominent role. The new IFOAM principles reflect the current worldwide consensus on the most important values of organic agriculture. Regionality or proximity is not explicitly mentioned in these principles. Also in the present EU-regulation on organic agriculture hardly any standards are formulated concerning this issue. On the other hand, some private organic labels do have extra standards - concerning for instance the origin of organic feed - while both producers and consumers of organic products often mention regional production as an important value. The question is whether, and if so why regionality is an important issue to be dealt with in the upcoming reformed EU-regulation on organic agriculture. To answer this question, the consequences are evaluated of the de-velopment of intensive, large-scale organic animal production in the Netherlands in the light of the value of regionality

Photoswitchable catalysis by a nanozyme mediated by a lightsensitive cofactor

The activity of a gold nanoparticle-based catalyst can be reversibly up- and down-regulated by light. Light is used to switch a small molecule between cis- and trans-isomers, which inhibits the catalytic activity of the nanoparticles to different extent. The system is functional in aqueous buffer, which paves the way for integrating the system in biological networks

Kinematic Analysis of Swimmers with Permanent Physical Disabilities

When the movement patterns of persons with permanent physical disabilities are observed from underwater, it is apparent that they have adapted unique variations in their swimming strokes to compensate for existing anatomic and neuromuscular deficits. Using underwater videotaping and subsequent analysis it is now possible to both identify and evaluate the movement mechanics of these swimmers. The purpose of this paper is to describe how motion analysis technology can be used in biomechanical research to examine the stroke mechanics of swimmers with permanent physical disabilities. In addition, we will identify the unique movement patterns of these swimmers, and, when applicable, discuss the limitations to their swimming efficiency

THE APPLICATION OF HIGH-SPEED VIDEOGRAPHY TO THE KINEMATIC ANALYSIS OF FREESTYLE SWIMMING

The purpose of this paper is to present the preliminary results of the use of high-speed videography and subsequent “multi-2D” motion analysis in the study of selected factors associated with Freestyle swimming. Variations in hip velocity in the longitudinal plane of motion were assessed in a series of trials which required swimmers to (1) Perform the underwater pull phase using the traditional “90-degree” elbow bend; and (2) Repeat the effort while holding the elbow in a fully extended position; (3) Allow the elbows to precede the hands while attempting to engage the water during the propulsive phase, i.e. pull with a “dropped elbow.” and (4) Consciously guide the hands through an exaggerated lateral path, referred to as the “S pull”; The resulting data produced quantifiable results that address a number of technical assumptions long-held by coaches and swimmers

Robust detection of alternative splicing in a population of single cells

Single cell RNA-seq experiments provide valuable insight into cellular heterogeneity but suffer from low coverage, 3′ bias and technical noise. These unique properties of single cell RNA-seq data make study of alternative splicing difficult, and thus most single cell studies have restricted analysis of transcriptome variation to the gene level. To address these limitations, we developed SingleSplice, which uses a statistical model to detect genes whose isoform usage shows biological variation significantly exceeding technical noise in a population of single cells. Importantly, SingleSplice is tailored to the unique demands of single cell analysis, detecting isoform usage differences without attempting to infer expression levels for full-length transcripts. Using data from spike-in transcripts, we found that our approach detects variation in isoform usage among single cells with high sensitivity and specificity. We also applied SingleSplice to data from mouse embryonic stem cells and discovered a set of genes that show significant biological variation in isoform usage across the set of cells. A subset of these isoform differences are linked to cell cycle stage, suggesting a novel connection between alternative splicing and the cell cycle

SLICER: inferring branched, nonlinear cellular trajectories from single cell RNA-seq data

Accuracy of trajectory reconstruction using a subset of cells. (a) Graph showing how similar the SLICER trajectory is when computed using a random subset of lung cells. The blue bars show the similarity in cell ordering (units are percent sorted with respect to the trajectory constructed from all cells). The orange bars show the similarity in branch assignments (percentage of cells assigned to the same branch as the trajectory constructed from all cells). The values shown were obtained by averaging the results from five subsampled datasets for each percentage (80 %, 60 %, 40 %, and 20 %). (b) Order preservation and branch identity values computed as in panel (a), but for datasets sampled from the neural stem cell dataset. (PDF 106 kb