Plant Trait Assembly Affects Superiority of Grazer's Foraging Strategies in Species-Rich Grasslands

Background

Current plant – herbivore interaction models and experiments with mammalian herbivores grazing plant monocultures show the superiority of a maximizing forage quality strategy (MFQ) over a maximizing intake strategy (MI). However, there is a lack of evidence whether grazers comply with the model predictions under field conditions.

Methodology/Findings

We assessed diet selection of sheep (Ovis aries) using plant functional traits in productive mesic vs. low-productivity dry species-rich grasslands dominated by resource-exploitative vs. resource-conservative species respectively. Each grassland type was studied in two replicates for two years. We investigated the first grazing cycle in a set of 288 plots with a diameter of 30 cm, i.e. the size of sheep feeding station. In mesic grasslands, high plot defoliation was associated with community weighted means of leaf traits referring to high forage quality, i.e. low leaf dry matter content (LDMC) and high specific leaf area (SLA), with a high proportion of legumes and the most with high community weighted mean of forage indicator value. In contrast in dry grasslands, high community weighted mean of canopy height, an estimate of forage quantity, was the best predictor of plot defoliation. Similar differences in selection on forage quality vs. quantity were detected within plots. Sheep selected plants with higher forage indicator values than the plot specific community weighted mean of forage indicator value in mesic grasslands whereas taller plants were selected in dry grasslands. However, at this scale sheep avoided legumes and plants with higher SLA, preferred plants with higher LDMC while grazing plants with higher forage indicator values in mesic grasslands.

Conclusions

Our findings indicate that MFQ appears superior over MI only in habitats with a predominance of resource-exploitative species. Furthermore, plant functional traits (LDMC, SLA, nitrogen fixer) seem to be helpful correlates of forage quality only at the community level.     

A Phylogenomic Perspective on the Radiation of Ray-Finned Fishes Based upon Targeted Sequencing of Ultraconserved Elements (UCEs)

Ray-finned fishes constitute the dominant radiation of vertebrates with over 32,000 species. Although molecular phylogenetics has begun to disentangle major evolutionary relationships within this vast section of the Tree of Life, there is no widely available approach for efficiently collecting phylogenomic data within fishes, leaving much of the enormous potential of massively parallel sequencing technologies for resolving major radiations in ray-finned fishes unrealized. Here, we provide a genomic perspective on longstanding questions regarding the diversification of major groups of ray-finned fishes through targeted enrichment of ultraconserved nuclear DNA elements (UCEs) and their flanking sequence. Our workflow efficiently and economically generates data sets that are orders of magnitude larger than those produced by traditional approaches and is well-suited to working with museum specimens. Analysis of the UCE data set recovers a well-supported phylogeny at both shallow and deep time-scales that supports a monophyletic relationship between Amia and Lepisosteus (Holostei) and reveals elopomorphs and then osteoglossomorphs to be the earliest diverging teleost lineages. Our approach additionally reveals that sequence capture of UCE regions and their flanking sequence offers enormous potential for resolving phylogenetic relationships within ray-finned fishes.     

The Value of In Vitro Diagnostic Testing in Medical Practice: A Status Report

BackgroundIn vitro diagnostic (IVD) investigations are indispensable for routine patient management. Appropriate testing allows early-stage interventions, reducing late-stage healthcare expenditure (HCE).AimTo investigate HCE on IVDs in two developed markets and to assess the perceived value of IVDs on clinical decision-making. Physician-perceived HCE on IVD was evaluated, as well as desired features of new diagnostic markers.MethodsPast and current HCE on IVD was calculated for the US and Germany. A total of 79 US/German oncologists and cardiologists were interviewed to assess the number of cases where: physicians ask for IVDs; IVDs are used for initial diagnosis, treatment monitoring, or post-treatment; and decision-making is based on an IVD test result. A sample of 201 US and German oncologists and cardiologists was questioned regarding the proportion of HCE they believed to be attributable to IVD testing. After disclosing the actual IVD HCE, the physician’s perception of the appropriateness of the amount was captured. Finally, the association between physician-rated impact of IVD on decision-making and perceived contribution of IVD expenditure on overall HCE was assessed.ResultsIVD costs account for 2.3% and 1.4% of total HCE in the US and Germany. Most physicians (81%) believed that the actual HCE on IVDs was >5%; 19% rated the spending correctly (0–4%, p<0.001). When informed of the actual amount, 64% of physicians rated this as appropriate (p<0.0001); 66% of decision-making was based on IVD. Significantly, more physicians asked for either additional clinical or combined clinical/health economic data than for the product (test/platform) alone (p<0.0001).ConclusionsOur results indicate a poor awareness of actual HCE on IVD, but a high attributable value of diagnostic procedures for patient management. New markers should deliver actionable and medically relevant information, to guide decision-making and foster improved patient outcomes.     

Chemical Profile and Antioxidant Properties of Extracts and Essential Oils from Citrus × limon (L.) Burm. cv. Femminello Comune

Citrus × limon cv. Femminello Comune (Rutaceae) from Rocca Imperiale (Italy), one of the six Protected Geographical Indication (PGI) Italian lemon crops, has been recently received renewed interest. In this work, fresh and dried peels and leaves were extracted by hydrodistillation, supercritical fluid extraction (SFE), and Soxhlet apparatus. Chemical profile was assessed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). Except for leaves extracts obtained by Soxhlet apparatus, the monoterpene hydrocarbons fraction dominated. Limonene, γ‐terpinene, and β‐pinene were the main identified compounds. The antioxidant activity was investigated using different in vitro assays namely 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH), ABTS, ferric reducing ability power (FRAP), and β‐carotene bleaching test. In DPPH test, the essential oil obtained by hydrodistillation of fresh peel exhibited the highest activity (IC₅₀ of 1.17 mg/ml). Leaves extracted by SFE showed a good activity in both DPPH and β‐carotene bleaching test with IC₅₀ values of 2.20 and 6.66 mg/ml, respectively. Monoterpene hydrocarbons fraction exhibited a positive Pearson's correlation coefficient with all antioxidant assays. Leaves, often considered waste material, should be considered from a different point because they represent a matrix of indisputable interest.     

On the Permeation by Dioxygen of Urate Oxidase from Aspergillus flavus in Complex with Xanthine Anion: Dioxygen Pathways and a Portrait of the Enzyme Cavities from Molecular Dynamics Simulations in Water Solution

This work describes molecular dynamics (MD) simulations in aqueous media for the complex of the homotetrameric urate oxidase (UOX) from Aspergillus flavus with xanthine anion ( 5 ) in the presence of dioxygen (O₂). After 196.6 ns of trajectory from unrestrained MD, a O₂ molecule was observed leaving the bulk solvent to penetrate the enzyme between two subunits, A/C. From here, the same O₂ molecule was observed migrating, across subunit C, to the hydrophobic cavity that shares residue V227 with the active site. The latter was finally attained, after 378.3 ns of trajectory, with O₂ at a bonding distance from 5 . The reverse same O₂ pathway, from 5 to the bulk solvent, was observed as preferred pathway under random acceleration MD (RAMD), where an external, randomly oriented force was acting on O₂. Both MD and RAMD simulations revealed several cavities populated by O₂ during its migration from the bulk solvent to the active site or backwards. Paying attention to the last hydrophobic cavity that apparently serves as O₂ reservoir for the active site, it was noticed that its volume undergoes ample fluctuations during the MD simulation, as expected from the thermal motion of a flexible protein, independently from the particular subunit and no matter whether the cavity is filled or not by O₂.     

Unveiling the Pathways of Dioxygen Through the C2 Component of the Environmentally Relevant Monooxygenase p‐Hydroxyphenylacetate Hydroxylase from Acinetobacter baumannii: A Molecular Dynamics Investigation

In this work, models of the homotetrameric C2 component of the monooxygenase p‐hydroxyphenylacetate hydroxylase from Acinetobacter baumannii, in complex with dioxygen (O₂) and, or not, the substrate p‐hydroxyphenylacetate (HPA) were built. Both models proved to be amenable to random‐acceleration molecular dynamics (RAMD) simulations, whereby a tiny randomly oriented external force, acting on O₂ at the active site in front of flavin mononucleotide (FMNH^?), accelerated displacement of O₂ toward the bulk solvent. This allowed us to carry out a sufficiently large number of RAMD simulations to be of statistical significance. The two systems behaved very similarly under RAMD, except for O₂ leaving the active site more easily in the absence of HPA, but then finding similar obstacles in getting to the gate as when the active site was sheltered by HPA. This challenges previous conclusions that HPA can only reach the active center after that the C4aOOH derivative of FMNH^? is formed, requiring uptake of O₂ at the active site before HPA. According to these RAMD simulations, O₂ could well get to FMNH^? also in the presence of the substrate at the active site.     

Specific protein changes contribute to the differential muscle mass loss during ageing

In the skeletal muscle, the ageing process is characterized by a loss of muscle mass and strength, coupled with a decline of mitochondrial function and a decrease of satellite cells. This profile is more pronounced in hindlimb than in forelimb muscles, both in humans and in rodents. Utilizing light and electron microscopy, myosin heavy chain isoform distribution, proteomic analysis by 2D‐DIGE, MALDI‐TOF MS and quantitative immunoblotting, this study analyzes the protein levels and the nuclear localization of specific molecules, which can contribute to a preferential muscle loss. Our results identify the molecular changes in the hindlimb (gastrocnemius) and forelimb (triceps) muscles during ageing in rats (3‐ and 22‐month‐old). Specifically, the oxidative metabolism contributes to tissue homeostasis in triceps, whereas respiratory chain disruption and oxidative‐stress‐induced damage imbalance the homeostasis in gastrocnemius muscle. High levels of dihydrolipoyllysine‐residue acetyltransferase (Dlat) and ATP synthase subunit alpha (Atp5a1) are detected in triceps and gastrocnemius, respectively. Interestingly, in triceps, both molecules are increased in the nucleus in aged rats and are associated to an increased protein acetylation and myoglobin availability. Furthermore, autophagy is retained in triceps whereas an enhanced fusion, decrement of mitophagy and of regenerative potential is observed in aged gastrocnemius muscle.     

The effects of demographic stochasticity and parameter uncertainty on predicting the establishment of introduced species

Invasive species are a serious threat to biodiversity worldwide and predicting whether an introduced species will first establish and then become invasive can be useful to preserve ecosystem services. Establishment is influenced by multiple factors, such as the interactions between the introduced individuals and the resident community, and demographic and environmental stochasticity. Field observations are often incomplete or biased. This, together with an imperfect knowledge of the ecological traits of the introduced species, makes the prediction of establishment challenging. Methods that consider the combined effects of these factors on our ability to predict the establishment of an introduced species are currently lacking. We develop an inference framework to assess the combined effects of demographic stochasticity and parameter uncertainty on our ability to predict the probability of establishment following the introduction of a small number of individuals. We find that even moderate levels of demographic stochasticity influence both the probability of establishment, and, crucially, our ability to correctly predict that probability. We also find that estimation of the demographic parameters of an introduced species is fundamental to obtain precise estimates of the interaction parameters. For typical values of demographic stochasticity, the drop in our ability to predict an establishment can be 30% when having priors on the demographic parameters compared to having their accurate values. The results from our study illustrate how demographic stochasticity may bias the prediction of the probability of establishment. Our method can be applied to estimate probability of establishment of introduced species in field scenarios, where time series data and prior information on the demographic traits of the introduced species are available.     

Design of a Virtual Player for Joint Improvisation with Humans in the Mirror Game

Joint improvisation is often observed among humans performing joint action tasks. Exploring the underlying cognitive and neural mechanisms behind the emergence of joint improvisation is an open research challenge. This paper investigates jointly improvised movements between two participants in the mirror game, a paradigmatic joint task example. First, experiments involving movement coordination of different dyads of human players are performed in order to build a human benchmark. No designation of leader and follower is given beforehand. We find that joint improvisation is characterized by the lack of a leader and high levels of movement synchronization. Then, a theoretical model is proposed to capture some features of their interaction, and a set of experiments is carried out to test and validate the model ability to reproduce the experimental observations. Furthermore, the model is used to drive a computer avatar able to successfully improvise joint motion with a human participant in real time. Finally, a convergence analysis of the proposed model is carried out to confirm its ability to reproduce joint movements between the participants.