Microbial Hotspots in Lithic Macrohabitats Inferred from DNA Fractionation and Metagenomics in the Atacama Desert

The existence of microbial activity hotspots in temperate regions of Earth is driven by soil heterogeneities, especially the temporal and spatial availability of nutrients. Here we investigate whether microbial activity hotspots also exist in lithic microhabitats in one of the most arid regions of the world, the Atacama Desert in Chile. While previous studies evaluated the total DNA fraction to elucidate the microbial communities, we here for the first time use a DNA separation approach on lithic microhabitats, together with metagenomics and other analysis methods (i.e., ATP, PLFA, and metabolite analysis) to specifically gain insights on the living and potentially active microbial community. Our results show that hypolith colonized rocks are microbial hotspots in the desert environment. In contrast, our data do not support such a conclusion for gypsum crust and salt rockenvironments, because only limited microbial activity could be observed. The hypolith community is dominated by phototrophs, mostly Cyanobacteria and Chloroflexi, at both study sites. The gypsum crusts are dominated by methylotrophs and heterotrophic phototrophs, mostly Chloroflexi, and the salt rocks (halite nodules) by phototrophic and halotolerant endoliths, mostly Cyanobacteria and Archaea. The major environmental constraints in the organic-poor arid and hyperarid Atacama Desert are water availability and UV irradiation, allowing phototrophs and other extremophiles to play a key role in desert ecology

Who was at risk of trauma-related injuries during the COVID-19 pandemic? A retrospective study from a level 1 trauma centre in Switzerland.

INTRODUCTION During the first wave of the COVID-19 pandemic, increasingly strict restrictions were imposed on the activities of the Swiss population, with a peak from 21 March to 27 April 2020. Changes in trauma patterns during the pandemic and the lockdown have been described in various studies around the world, and highlight some particularly exposed groups of people. The objective of this study was to assess changes in trauma-related presentations to the emergency department (ED) during the first wave of the COVID-19 pandemic, as compared to the same period in the previous year, with a particular focus on vulnerable populations. MATERIALS AND METHODS All trauma-related admissions to our ED in the first half of 2019 and 2020 were included. Patient demographics, trauma mechanism, affected body region, injury severity and discharge type were extracted from our hospital information system. Trauma subpopulations, such as interpersonal violence, self-inflicted trauma, geriatric trauma and sports-related trauma were analysed. RESULTS A total of 5839 ED presentations were included in our study, of which 39.9% were female. Median age was 40 years (interquartile range: 27-60). In comparison to 2019, there was a 15.5% decrease in trauma-related ED presentations in the first half of 2020. This decrease was particularly marked in the 2-month March/April period, with a drop of 36.8%. In 2020, there was a reduction in injuries caused by falls of less than 3 metres or by mechanical force. There was a marked decrease in sports-related trauma and an increase in injuries related to pedal cycles. Geriatric trauma, self-harm and assault-related injuries remained stable. CONCLUSION This study described changes in trauma patterns and highlighted populations at risk of trauma during the pandemic in Switzerland in the context of previous international studies.These results may contribute to resource management in a future pandemic

Transit time distributions and StorAge Selection functions in a sloping soil lysimeter with time-varying flow paths: Direct observation of internal and external transport variability

Transit times through hydrologic systems vary in time, but the nature of that variability is not well understood. Transit times variability was investigated in a 1 m(3) sloping lysimeter, representing a simplified model of a hillslope receiving periodic rainfall events for 28 days. Tracer tests were conducted using an experimental protocol that allows time-variable transit time distributions (TTDs) to be calculated from data. Observed TTDs varied with the storage state of the system, and the history of inflows and outflows. We propose that the observed time variability of the TTDs can be decomposed into two parts: internal variability associated with changes in the arrangement of, and partitioning between, flow pathways; and external variability driven by fluctuations in the flow rate along all flow pathways. These concepts can be defined quantitatively in terms of rank StorAge Selection (rSAS) functions, which is a theory describing lumped transport dynamics. Internal variability is associated with temporal variability in the rSAS function, while external is not. The rSAS function variability was characterized by an inverse storage effect, whereby younger water is released in greater proportion under wetter conditions than drier. We hypothesize that this effect is caused by the rapid mobilization of water in the unsaturated zone by the rising water table. Common approximations used to model transport dynamics that neglect internal variability were unable to reproduce the observed breakthrough curves accurately. This suggests that internal variability can play an important role in hydrologic transport dynamics, with implications for field data interpretation and modeling.National Science Foundation [EAR-1344552, EAR-1417175]; CUAHSI Pathfinder fellowshipFirst published: 22 September 2016; 6 Month Embargo.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]