The Role of Fine-Scale Habitat Associations in Structuring Spider Assemblages: Determinants of Spatial Patterns in Community Composition

Elucidating the ecological determinants of community structure and how they vary spatially has a long history in ecology, but there still is no consensus on the mechanisms behind diversity patterns. The primary objective of this dissertation was to focus on spider assemblages to investigate how the fine-scale habitat associations of organisms may drive their community composition at larger scales. Research was conducted in the Bear River Mountains, Utah, in an attempt to elucidate the potential role of species-microhabitat associations in driving three well-known patterns of community composition that have typically been investigated at broad scales: 1) elevation gradients of species diversity, 2) the response of species assemblages to neighboring habitat structure and 3) community composition at the edges of habitat patches. Slope aspect was a significant predictor of spider density and species richness when communities were compared at the same elevation, suggesting that fine-scale topographic variables may play an important role in shaping elevational patterns of species composition. Cursorial spider composition was strongly linked to site temperature only, whereas differences across web spider assemblages significantly increased with dissimilarities in woody plant cover and temperature. The study on the effects of neighboring habitat structure revealed markedly reduced cursorial spider densities in shrubs without surrounding structure, and more cursorial species in control shrubs, whereas web spiders lacked any significant response to treatments. These contrasting responses indicate that data should be collected at larger spatial extents for mobile species, and that mobility may mediate the outcome of surrounding habitat modifications on the local composition of communities. In the last study, I focused on communities in which the edge-dwelling spiders Theridion and Dictyna strongly differed in terms of concealment and substrate generalization and found that microhabitat choice may affect the sensitivity of species to habitat geometry, a characteristic associated with habitat fragmentation. This work suggests that a better understanding of the links between the biological traits of species and their fine-scale environmental requirements may help uncover the mechanisms behind spatial patterns of community composition at larger scales

Comparison of antimicrobial resistance phenotypes and genotypes in enterotoxigenic Escherichia coli isolated from Australian and Vietnamese pigs

This study aimed to compare the antibiogram phenotype and carriage of antimicrobial resistance genes (ARGs) of 97 porcine multidrug-resistant (MDR) enterotoxigenic Escherichia coli (ETEC) isolates obtained from Vietnam and 117 porcine MDR-ETEC obtained from Australia, two countries with different antimicrobial regulation systems. An antimicrobial resistance index (ARI) was calculated to quantify their potential significance to public health. Both Vietnamese and Australian isolates had moderate to high levels of resistance to commonly used antibiotics (ampicillin, tetracycline and sulphonamides). None of the Australian isolates were resistant to fluoroquinolones or third-generation cephalosporins and none possessed associated plasmid-mediated ARGs. However, 23.1% of Australian isolates were resistant to gentamicin owing to ARGs associated with apramycin or neomycin resistance [e.g. aac(3)-IV] that impart cross-resistance to gentamicin. Whilst Vietnamese isolates carried aminoglycoside ARGs, 44.4% of commercial pig isolates were resistant to gentamicin in comparison with 0% of village pig isolates. The plasmid-mediated fluoroquinolone ARG qnrB was commonly detected in Vietnamese isolates (52.3% commercial, 44.1% village), but phenotypic resistance was low (3.2% and 11.8%, respectively). The mean ARI for Vietnamese isolates (26.0) was significantly different (P < 0.001) from the mean ARI for Australian isolates (19.8), primarily reflecting fluoroquinolone resistance in the former collection. This comparison suggests the effectiveness of regulations that slow the dissemination of 'critical' resistance by restricting the availability of important classes of antimicrobials

Moving forward in circles: challenges and opportunities in modelling population cycles

Population cycling is a widespread phenomenon, observed across a multitude of taxa in both laboratory and natural conditions. Historically, the theory associated with population cycles was tightly linked to pairwise consumer–resource interactions and studied via deterministic models, but current empirical and theoretical research reveals a much richer basis for ecological cycles. Stochasticity and seasonality can modulate or create cyclic behaviour in non-intuitive ways, the high-dimensionality in ecological systems can profoundly influence cycling, and so can demographic structure and eco-evolutionary dynamics. An inclusive theory for population cycles, ranging from ecosystem-level to demographic modelling, grounded in observational or experimental data, is therefore necessary to better understand observed cyclical patterns. In turn, by gaining better insight into the drivers of population cycles, we can begin to understand the causes of cycle gain and loss, how biodiversity interacts with population cycling, and how to effectively manage wildly fluctuating populations, all of which are growing domains of ecological research

Creatine supplementation in the elderly: is resistance training really needed?

Introduction: Decreases in muscle mass, strength and power are associated with ageing, all of which increase the risk of falls, and cause a loss of independence. Creatine supplementation is often used in younger athletes to improve anaerobic performance, power and strength, however the potential benefits of creatine supplementation in older individuals are less clear. With an ageing population comes age-related losses in skeletal muscle mass, sarcopenia and associated risks of falls, morbidity and mortality. Importantly many older individuals still regularly perform aerobic and resistance training which serves to maintain this muscle mass and reduce these risks however a large proportion do not partake in regular exrecise [1]. There is evidence that creatine supplementation may maintain muscle mass and function in older adults [2], but an important question is whether resistance training and creatine supplementation have an additive effect on muscle structure and function or can older adults receive the same degree of benefit by just partaking in one of these protocols? Creatine Creatine is important for energy metabolism, and is thought to be an effective ergogenic aid in physical performance [3]. Creatine is synthesised within the body and ingested naturally from meat [3] or artificially through supplements. 94% of total body creatine is located in skeletal muscles and is stored as either free (40%) or phosphorylated creatine (PCr; 60%) [4]. Within skeletal muscles, creatine is hypothesised to shuttle high energy phosphogens between the mitochondria and cytosol [5], increasing the efficiency of cross-bridge cycling and thereby enhancing skeletal muscle contraction (Figure 1). Firstly, ATP synthesised in the mitochondrial matrix is transported via creatine kinase (CK) to the mitochondrial intermembrane space where CK catalyses the formation of ADP and PCr; Figure 2 reveals the equation from which ATP is then generated from stores of PCr via creatine kinase during periods of intense exercise. The ADP produced is transported back to the matrix where it is rephosphorylated when required. Liberated PCr migrates to the cytosol to sites of ATP consumption, where local CK enzymes regenerate ATP to allow for increased contraction. The liberated creatine then diffuses back to the mitochondria to allow for subsequent phosphorylation if required. This “transport” process is thought to occur in endurance-type activities [6-8]. Creatine supplementation has been shown to increase PCr regeneration [9], increasing ATP availability, thus facilitating prolonged physical activity [4]. Aim: This review assesses the current literature on whether creatine supplementation in the presence of resistance training enhances physical performance in older adults above and beyond those undertaking resistance training alone or only taking creatine supplements. Results: Whilst reports are conflicting, there is good evidence to suggest that creatine supplementation with resistance training increases muscular endurance, lower body strength and lean body mass; this is above results obtained with creatine supplementation or resistance training alone. The increased muscle mass observed with training has previously been shown to lead to increased bone mineral content and an associated reduced fracture risk; however, the additional benefits of creatine supplementation on this are less clear, and more work is needed to confirm whether exogenously taken creatine will benefit bone mineral density. Conclusion: Creatine supplementation in the elderly may lead to increased muscle mass, endurance and performance, and those who undertake resistance training may show further improvements with creatine supplementation. However, for elderly subjects who do not partake in resistance training, creatine supplementation offers significant improvements in increasing muscular mass and strength, and increasing their quality of life, whilst these benefits are lower on the whole than those who undertake regular resistance training

Holograms to Focus Arbitrary Ultrasonic Fields through the Skull

[EN] We report 3D-printed acoustic holographic lenses for the formation of ultrasonic fields of complex spatial distribution inside the skull. Using holographic lenses, we experimentally, numerically and theoretically produce acoustic beams whose spatial distribution matches target structures of the central nervous system. In particular, we produce three types of targets of increasing complexity. First, a set of points are selected at the center of both right and left human hippocampi. Experiments using a skull phantom and 3D printed acoustic holographic lenses show that the corresponding bi-focal lens simultaneously focuses acoustic energy at the target foci, with good agreement between theory and simulations. Second, an arbitrary curve is set as the target inside the skull phantom. Using time-reversal methods the holographic beam bends following the target path, in a similar way as self-bending beams do in free space. Finally, the right human hippocampus is selected as a target volume. The focus of the corresponding holographic lens overlaps with the target volume in excellent agreement between theory in free-media, and experiments and simulations including the skull phantom. The precise control of focused ultrasound into the central nervous system is mainly limited due to the strong phase aberrations produced by refraction and attenuation of the skull. Using the present method, the ultrasonic beam can be focused not only at a single point but overlapping one or various target structures simultaneously using low-cost 3D-printed acoustic holographic lens. The results open new paths to spread incoming biomedical ultrasound applications including blood-brain barrier opening and neuromodulation.This work is supported by the Spanish Ministry of Economy and Innovation (MINECO) through Project No. TEC2016-80976-R. 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Health-related Quality of Life in Patients With Nonalcoholic Fatty Liver Disease: A Prospective Multi-center UK Study

BACKGROUND & AIMS: It is unclear whether health-related quality of life (HRQoL) is impaired in patients with nonalcoholic fatty liver disease (NAFLD) without advanced fibrosis and how this compares with the general population. We aimed to assess HRQoL in patients with NAFLD in comparison to the general population and any associations of fibrosis severity and metabolic comorbidities with impairments in HRQoL. METHODS: We prospectively enrolled 513 consecutive patients with NAFLD who completed the EuroQol 5-dimensional questionnaire (EQ-5D) and Chronic Liver Disease Questionnaires (CLDQ). Demographic and clinical information, liver biopsy results, and/or liver stiffness (LS) by transient elastography were recorded. A general population sub-cohort of the Health Survey for England 2018 was used as a comparator (n = 5483), and a 1:1 propensity-score (PS) matching was performed, according to age, sex, body mass index, and type 2 diabetes mellitus (T2DM). RESULTS: EQ-5D-5L utility was significantly lower in 466 PS-matched patients with NAFLD compared with PS-matched controls (0.77 ± 0.27 vs 0.84 ± 0.19; P < .001), even in those without advanced fibrosis (F ≤2 or LS <8kPa) (0.80 ± 0.24 vs 0.84 ± 0.19; P = .024). HRQoL measures (EQ-5D-5L, EQ-VAS, CLDQ) did not differ between patients with NAFLD with and without advanced fibrosis. LS was independently associated with lower EQ-5D-5L in all patients with NAFLD but not in those without advanced fibrosis. In the latter, lower EQ-5D-5L was associated with female sex, T2DM, and depression. CONCLUSIONS: Patients with NAFLD, even those without advanced fibrosis, have worse HRQoL compared with the general population. In patients with NAFLD without advanced fibrosis, HRQoL is independently associated with non-liver comorbidities but not LS. Multi-disciplinary management is therefore required in NAFLD, irrespective of fibrosis severity

Phylogenetic grouping, antibiotic resistance profile, fluoroquinolone susceptibility and ST131 status of canine extra intestinal Escherichia Coli isolated from submissions to a veterinary diagnostic laboratory 2005-08

Fluoroquinolones (FQs) are a recommended treatment for Escherichia coli infections in companion animals, particularly in cases of resistance to other drug classes. In a retrospective study, 162 canine clinical E. coli isolates, obtained from veterinary diagnostic submissions (January 2005 - June 2008), were analyzed for phylogenetic group and antibiogram phenotype, using nine antimicrobials and enrofloxacin, ciprofloxacin, moxifloxacin and pradofloxacin minimum inhibitory concentrations (MICs), either in the absence or presence of an efflux pump inhibitor. The isolate susceptibility distribution was bimodal; a high proportion (141/162;87%) showed a sensitivity equivalent to wildtype E. coli (enrofloxacin MIC 0.004 - 0.06 μg/mL), while a minority (4/162;2%) showed reduced susceptibility (enrofloxacin MICs of 0.125 - 0.5 μg/mL), and the remainder (17/162;10%) yielding enrofloxacin MICs in the highlevel resistance range of ≥16 μg/mL. All FQ-resistant isolates were also multidrug-resistant. The majority of FQsensitive isolates belonged to phylogenetic group B2 (101/162;62%), and the majority of resistant isolates to group D (8/17;47%). A single resistant B2 isolate and three FQ-sensitive isolates were identified as ST131. Efflux pump activity contributed significantly to MICs for all FQs, except for ciprofloxacin, which may be attributable to its higher polarity compared to the other FQs. These findings confirm a low prevalence of FQ resistance in Australian canine E. coli isolates. Detection of a high moxifloxacin: low ciprofloxacin MIC efflux-associated phenotype (102/162;63%) amongst canine strains may indicate previous exposure to moxifloxacin selective pressure, providing more evidence of exchange of E. coli strains between humans and dogs. The presence of sensitive ST131 strains in the isolate collection does suggest, however, that resistant ST131 strains could potentially emerge under both human and veterinary antimicrobial selection pressure, a risk that could be mitigated by using the most active fluoroquinolone (i.e. pradofloxacin in dogs) against wild-type E. coli at mutant prevention concentrations.Joanne L, Platell, Darren J. Trott, Heinz-Georg Wetzstein, Micheal Leitner and Rowland N. Cobbol

Remodelling of a polypyrimidine tract-binding protein complex during apoptosis activates cellular IRESs.

Post-transcriptional control of gene expression is mediated by the interaction of RNA-binding proteins with their cognate mRNAs that specifically regulate their stability, localization and translation. mRNA-binding proteins are multifunctional and it has been proposed therefore that a combinatorial RNA-binding protein code exists that allows specific protein sub-complexes to control cytoplasmic gene expression under a range of pathophysiological conditions. We show that polypyrimidine tract-binding protein (PTB) is central to one such complex that forms in apoptotic cells. Thus, during apoptosis initiated by TNF-related apoptosis inducing ligand there is a change in the repertoire of RNA-binding proteins with which PTB interacts. We show that altering the cellular levels of PTB and its binding partners, either singly or in combination, is sufficient to directly change the rates of apoptosis with increased expression of PTB, YBX1, PSF and NONO/p54(nrb) accelerating this process. Mechanistically, we show that these proteins post-transcriptionally regulate gene expression, and therefore apoptotic rates, by interacting with and stimulating the activity of RNA elements (internal ribosome entry segments) found in mRNAs that are translated during apoptosis. Taken together, our data show that PTB function is controlled by a set of co-recruited proteins and importantly provide further evidence that it is possible to dictate cell fate by modulating cytoplasmic gene expression pathways alone

PNAS plus: plasmodium falciparum responds to amino acid starvation by entering into a hibernatory state

The human malaria parasite Plasmodium falciparum is auxotrophic for most amino acids. Its amino acid needs are met largely through the degradation of host erythrocyte hemoglobin; however the parasite must acquire isoleucine exogenously, because this amino acid is not present in adult human hemoglobin. We report that when isoleucine is withdrawn from the culture medium of intraerythrocytic P. falciparum, the parasite slows its metabolism and progresses through its developmental cycle at a reduced rate. Isoleucine-starved parasites remain viable for 72 h and resume rapid growth upon resupplementation. Protein degradation during starvation is important for maintenance of this hibernatory state. Microarray analysis of starved parasites revealed a 60% decrease in the rate of progression through the normal transcriptional program but no other apparent stress response. Plasmodium parasites do not possess a TOR nutrient-sensing pathway and have only a rudimentary amino acid starvation-sensing eukaryotic initiation factor 2α (eIF2α) stress response. Isoleucine deprivation results in GCN2-mediated phosphorylation of eIF2α, but kinase-knockout clones still are able to hibernate and recover, indicating that this pathway does not directly promote survival during isoleucine starvation. We conclude that P. falciparum, in the absence of canonical eukaryotic nutrient stress-response pathways, can cope with an inconsistent bloodstream amino acid supply by hibernating and waiting for more nutrient to be provided