Replicability and Recurrence in the Experimental Evolution of a Group I Ribozyme

In order to explore the variety of possible responses available to a ribozyme population evolving a novel phenotype, five Tetrahymena thermophila group I intron ribozyme pools were evolved in parallel for cleavage of a DNA oligonucleotide. These ribozyme populations were propagated under identical conditions and characterized when they reached apparent phenotypic plateaus; the populations that reached the highest plateau showed a near 100-fold improvement in DNA cleavage activity. A detailed characterization of the evolved response in these populations reveals at least two distinct phenotypic trajectories emerging as a result of the imposed selection. Not only do these distinct solutions exhibit differential DNA cleavage activity, but they also exhibit a very different correlation with a related, but unselected, phenotype: RNA cleavage activity. In turn, each of these trajectories is underwritten by differing genotypic profiles. This study underscores the complex network of possible trajectories through sequence space available to an evolving population and uncovers the diversity of solutions that result when the process of experimental evolution is repeated multiple times in a simple, engineered system

Conceptualizing Emotions Along the Dimensions of Valence, Arousal, and Communicative Frequency – Implications for Social-Cognitive Tests and Training Tools

Background and Objectives: Emotion words are mostly characterized along the classic dimensions of arousal and valence. In the current study we sought to complement this characterization by investigating the frequency of emotions in human everyday communication, which may be crucial information for designing new diagnostic or intervention tools to test and improve emotion recognition. Methods: One hundred healthy German individuals were asked to indicate the valence and arousal of 62 emotion words in a questionnaire. Importantly, participants were additionally asked to indicate the frequency with which they experience each emotion themselves and observe it in others. Results: Positive emotions were judged to occur more often than negative emotions in everyday life. The more negatively valenced emotions were rated to be observed more often in others than experienced in one-self. On the other hand more positively valenced emotions were experienced more often in one-self than they were observed in others. Finally, increasing age was associated with a decrease in the frequency of observing an emotion in other people. Limitations: Future studies with larger sample sizes are needed to ascertain if the findings also apply to other cultural and language contexts. Conclusion: These results imply a greater frequency of positive emotions than negative emotions in everyday communication. The finding of such a bias toward positive emotions can guide the selection of emotion words for implementation in socio-emotional intervention tools. Such a selection may represent an effective means for improving social-cognitive functioning in people with respective impairments

By Any Other Name: Heterologous Replacement of the \u3ci\u3eEscherichia coli\u3c/i\u3e RNase P Protein Subunit Has \u3ci\u3eIn Vivo\u3c/i\u3e Fitness Consequences

Bacterial RNase P is an essential ribonucleoprotein composed of a catalytic RNA component (encoded by the rnpB gene) and an associated protein moiety (encoded by rnpA). We construct a system that allows for the deletion of the essential endogenous rnpA copy and for its simultaneous replacement by a heterologous version of the gene. Using growth rate as a proxy, we explore the effects on fitness of heterologous replacement by increasingly divergent versions of the RNase P protein. All of the heterologs tested complement the loss of the endogenous rnpA gene, suggesting that all existing bacterial versions of the rnpA sequence retain the elements required for functional interaction with the RNase P RNA. All replacements, however, exact a cost on organismal fitness, and particularly on the rate of growth acceleration, defined as the time required to reach maximal growth rate. Our data suggest that the similarity of the heterolog to the endogenous version — whether defined at the sequence, structure or codon usage level — does not predict the fitness costs of the replacement. The common assumption that sequence similarity predicts functional similarity requires experimental confirmation and may prove to be an oversimplification

Importance of multispin couplings in renormalized Hamiltonians Phys

We introduce a Monte Carlo approach to the calculation of more distant renormalized interactions with higher accuracy than is possible with previous methods. We have applied our method to study the effects of multispin interactions, which turn out to be far more important than commonly assumed. Even though the individual multispin interactions usually have smaller coupling constants than two-spin interactions, they can dominate the effects of two-spin interactions because they are so numerous

Rethinking the Composition of a Rational Antibiotic Arsenal for the 21st Century

The importance of the human microbiome in health may be the single most valuable development in our conception of the microbial world since Pasteur\u27s germ theory of the 1860s. Its implications for our understanding of health and pathogenesis are profound. Coupled with the revolution in diagnostics that we are now witnessing - a revolution that changes medicine from a science of symptoms to a science of causes - we cannot continue to develop antibiotics as we have for the past 80 years. Instead, we need to usher in a new conception of the role of antibiotics in treatment: away from single molecules that target broad phylogenetic spectra and towards targeted molecules that cripple the pathogen while leaving the rest of the microbiome largely intact

A Survey of Proper-Motion Stars. XV. Orbital Solutions for 34 Double-lined Spectroscopic Binaries

We present orbital solutions for 34 double-lined spectroscopic binaries found in the Carney-Latham sample of 1464 stars selected for high proper motion. We use TODCOR, a two-dimensional correlation technique, to extract the velocities for the primary and secondary stars and their light ratio. For our single-order echelle spectra, obtained with the Center for Astrophysics Digital Speedometers, we find that we can reach secondaries that are as much as 2 mag fainter than their primaries. The ratio of the primary to secondary velocity residuals from the orbital fit equals approximately the secondary-to-primary light ratio, as would be expected for the photon-limited case. We use our mass and light ratios to evaluate the mass-luminosity relation for metal-poor main-sequence dwarfs in the mass range 0.55–0.8 M. We assume an L ∝ β relation and find that the exponent at around 5200 Å is 7.4 ± 0.6. We find this is in good agreement with the slope of the corresponding theoretical MV- 14 Gyr isochrones from the VandenBerg & Bell models for metal-poor stars

ESD Reviews: Model Dependence in Multi-Model Climate Ensembles: Weighting, Sub-Selection and Out-Of-Sample Testing

The rationale for using multi-model ensembles in climate change projections and impacts research is often based on the expectation that different models constitute independent estimates; therefore, a range of models allows a better characterisation of the uncertainties in the representation of the climate system than a single model. However, it is known that research groups share literature, ideas for representations of processes, parameterisations, evaluation data sets and even sections of model code. Thus, nominally different models might have similar biases because of similarities in the way they represent a subset of processes, or even be near-duplicates of others, weakening the assumption that they constitute independent estimates. If there are near-replicates of some models, then treating all models equally is likely to bias the inferences made using these ensembles. The challenge is to establish the degree to which this might be true for any given application. While this issue is recognised by many in the community, quantifying and accounting for model dependence in anything other than an ad-hoc way is challenging. Here we present a synthesis of the range of disparate attempts to define, quantify and address model dependence in multi-model climate ensembles in a common conceptual framework, and provide guidance on how users can test the efficacy of approaches that move beyond the equally weighted ensemble. In the upcoming Coupled Model Intercomparison Project phase 6 (CMIP6), several new models that are closely related to existing models are anticipated, as well as large ensembles from some models. We argue that quantitatively accounting for dependence in addition to model performance, and thoroughly testing the effectiveness of the approach used will be key to a sound interpretation of the CMIP ensembles in future scientific studies

The role of Europe’s schools of public health in times of war: ASPHER statement on the war against Ukraine

info:eu-repo/semantics/publishedVersio