Plant choice between arbuscular mycorrhizal fungal species results in increased plant P acquisition.

Arbuscular mycorrhizal fungi (AMF) are plant root symbionts that provide phosphorus (P) to plants in exchange for photosynthetically fixed carbon (C). Previous research has shown that plants-given a choice among AMF species-may preferentially allocate C to AMF species that provide more P. However, these investigations rested on a limited set of plant and AMF species, and it therefore remains unclear how general this phenomenon is. Here, we combined 4 plant and 6 AMF species in 24 distinct plant-AMF species compositions in split-root microcosms, manipulating the species identity of AMF in either side of the root system. Using 14C and 32P/33P radioisotope tracers, we tracked the transfer of C and P between plants and AMF, respectively. We found that when plants had a choice of AMF species, AMF species which transferred more P acquired more C. Evidence for preferential C allocation to more beneficial AMF species within individual plant roots was equivocal. However, AMF species which transferred more P to plants did so at lower C-to-P ratios, highlighting the importance both of absolute and relative costs of P acquisition from AMF. When plants had a choice of AMF species, their shoots contained a larger total amount of P at higher concentrations. Our results thus highlight the benefits of plant C choice among AMF for plant P acquisition.

The influence of warming and biotic interactions on the potential for range expansion of native and nonnative species.

Plant species ranges are expected to shift in response to climate change, however, it is unclear how species interactions will affect range shifts. Because of the potential for enemy release of invasive nonnative plant species from species-specific soil pathogens, invasive plants may be able to shift ranges more readily than native plant species. Additionally, changing climatic conditions may alter soil microbial functioning, affecting plant-microbe interactions. We evaluated the effects of site, plant-soil microbe interactions, altered climate, and their interactions on the growth and germination of three congeneric shrub species, two native to southern and central Florida (Eugenia foetida and E. axillaris), and one nonnative invasive from south America (E. uniflora). We measured germination and biomass for these plant species in growth chambers grown under live and sterile soils from two sites within their current range, and one site in their expected range, simulating current (2010) and predicted future (2050) spring growing season temperatures in the new range. Soil microbes (microscopic bacteria, fungi, viruses and other organisms) had a net negative effect on the invasive plant, E. uniflora, across all sites and temperature treatments. This negative response to soil microbes suggests that E. uniflora's invasive success and potential for range expansion are due to other contributing factors, e.g. higher germination and growth relative to native Eugenia. The effect of soil microbes on the native species depended on the geographic provenance of the microbes, and this may influence range expansion of these native species.

Belowground impacts of alpine woody encroachment are determined by plant traits, local climate, and soil conditions.

Global climate and land use change are causing woody plant encroachment in arctic, alpine, and arid/semi-arid ecosystems around the world, yet our understanding of the belowground impacts of this phenomenon is limited. We conducted a globally distributed field study of 13 alpine sites across four continents undergoing woody plant encroachment and sampled soils from both woody encroached and nearby herbaceous plant community types. We found that woody plant encroachment influenced soil microbial richness and community composition across sites based on multiple factors including woody plant traits, site level climate, and abiotic soil conditions. In particular, root symbiont type was a key determinant of belowground effects, as Nitrogen-fixing woody plants had higher soil fungal richness, while Ecto/Ericoid mycorrhizal species had higher soil bacterial richness and symbiont types had distinct soil microbial community composition. Woody plant leaf traits indirectly influenced soil microbes through their impact on soil abiotic conditions, primarily soil pH and C:N ratios. Finally, site-level climate affected the overall magnitude and direction of woody plant influence, as soil fungal and bacterial richness were either higher or lower in woody encroached versus herbaceous soils depending on mean annual temperature and precipitation. All together, these results document global impacts of woody plant encroachment on soil microbial communities, but highlight that multiple biotic and abiotic pathways must be considered to scale up globally from site- and species-level patterns. Considering both the aboveground and belowground effects of woody encroachment will be critical to predict future changes in alpine ecosystem structure and function and subsequent feedbacks to the global climate system.

Shrub range expansion alters diversity and distribution of soil fungal communities across an alpine elevation gradient.

Global climate and land use change are altering plant and soil microbial communities worldwide, particularly in arctic and alpine biomes where warming is accelerated. The widespread expansion of woody shrubs into historically herbaceous alpine plant zones is likely to interact with climate to affect soil microbial community structure and function; however, our understanding of alpine soil ecology remains limited. This study aimed to (i) determine whether the diversity and community composition of soil fungi vary across elevation gradients and to (ii) assess the impact of woody shrub expansion on these patterns. In the White Mountains of California, sagebrush (Artemisia rothrockii) shrubs have been expanding upwards into alpine areas since 1960. In this study, we combined observational field data with a manipulative shrub removal experiment along an elevation transect of alpine shrub expansion. We utilized next-generation sequencing of the ITS1 region for fungi and joint distribution modelling to tease apart effects of the environment and intracommunity interactions on soil fungi. We found that soil fungal diversity declines and community composition changes with increasing elevation. Both abiotic factors (primarily soil moisture and soil organic C) and woody sagebrush range expansion had significant effects on these patterns. However, fungal diversity and relative abundance had high spatial variation, overwhelming the predictive power of vegetation type, elevation and abiotic soil conditions at the landscape scale. Finally, we observed positive and negative associations among fungal taxa which may be important in structuring community responses to global change.

Excellence in performance and stress reduction during two different full scale simulator training courses: a pilot study.

BACKGROUND: Simulator training is well established to improve technical and non-technical skills in critical situations. Few data exist about stress experienced during simulator training. This study aims to evaluate performance and stress in intensivists before and after two different simulator-based training approaches. METHODS: Thirty-two intensivists took part in one of six 1-day simulator courses. The courses were randomised to either crew resource management (CRM) training, which contains psychological teaching and simulator scenarios, or classic simulator training (MED). Before and after the course each participant took part in a 10-min test scenario. Before (T1) and after (T2) the scenario, and then again 15 min later (T3), saliva samples were taken, and amylase and cortisol were measured. Non-technical skills were evaluated using the Anaesthetist's Non-Technical Skills (ANTS) assessment tool. Clinical performance of the participants in the test scenarios was rated using a checklist. RESULTS: Twenty-nine participants completed the course (17-CRM, 12-MED). ANTS scores as well as clinical performances were significantly better in the post-intervention scenario, with no differences between the groups. Both cortisol concentration and amylase activity showed a significant increase during the test scenarios. In the post-intervention scenario, the increase in amylase but not cortisol was significantly smaller. There were no differences between the CRM and MED group. CONCLUSIONS: High fidelity patient simulation produces significant stress. After a 1-day simulator training, stress response measured by salivary alpha-amylase was reduced. Clinical performance and non-technical skills improved after 1 day of simulator training. Neither stress nor performance differed between the groups.

Six steps from head to hand: a simulator based transfer oriented psychological training to improve patient safety.

UNLABELLED: The incidence of human errors in the field of medicine is high. Two strategies to increase patient safety are simulator training and crew resource management (CRM) seminars, psychological courses on human performance and error management. AIM: To establish a CRM course combining psychological training on human error with simulator training. METHODS: Evaluation of a new 1-day training approach targeting physicians, nurses, and paramedics. The course was divided into four modules focusing on situation awareness, task management, teamwork, and decision-making. Each of the modules was set up according to a new six-step approach. The course started with an introduction into good CRM behaviour and an instructor demonstration of a simulator scenario. The participants had to debrief the instructors regarding their human performance. Step 2 was a lecture about the psychological background, and the third step consisted of psychological exercises related to the topic of the module. A psychological exercise in a medical context (MiniSim) made up step 4, which involved a patient simulator. The last two steps were a simulator scenario and a debriefing, as in other simulator courses. A psychologist and a physician were the facilitators in all steps. Two pilot courses were evaluated. RESULTS: Seventeen evaluation questionnaires were received. All participants rated the course as good (10) and very good (7). The psychological exercises were highly valued (good, 5; very good, 11 participants). Thirteen participants agreed that the course content was related to their work. CONCLUSION: We established the first course curriculum combining psychological teaching with simulator training for healthcare professionals in emergency medicine. Similar concepts using the six-step approach can be applied to other medical specialties.

N(omega)-nitro-L-arginine methyl ester effects on neutrophil function and bacterial clearance.

Nitric oxide synthase (NOS) inhibitors are considered promising as a therapeutic option in severe septic shock. The aim of this study was to investigate the effects of N-nitro-L-arginine methyl ester (L-NAME) application on neutrophil (PMN) respiratory burst, phagocytosis, and elimination of Escherichia coli from blood and tissue in rabbits. Twenty-eight female chinchilla rabbits were randomized to a treatment and control group. To quantify the bacterial clearance process, 10 colony forming units (CFU) of E. coli were injected intravenously into anesthetized rabbits. Animals in the L-NAME group had a significantly higher mortality compared with controls. NOS inhibition resulted in a significant delay of bacterial clearance (P < 0.001). These findings correlated with a significant augmentation of all organ E. coli findings (P = 0.002-0.035). PMN phagocytosis activity was notably reduced by L-NAME treatment during the experimental observation. Neutrophil burst, on the other hand, was amplified by NOS inhibition (P = 0.008). Our findings point to an interference with the PMN-dependent immune mechanisms after L-NAME treatment. The augmented PMN burst reaction could be a compensatory mechanism, potentially leading to tissue damage. Therefore, in this model, we find sufficient evidence pointing to a possible cause for the deleterious effect of early nonselective NOS inhibition in critically ill patients.