Genome-resolved metagenomics reveals diverse taxa and metabolic complexity in Antarctic lake microbial structures.

Lake Untersee, a lake in Antarctica that is perennially covered with ice, is home to unique microbial structures that are not lithified. We have evaluated the structure of the community and its metabolic potential across the pigmented upper layers and the sediment-enriched deeper layers in these pinnacle and cone-shaped microbial structures using metagenomics. These microbial structures are inhabited by distinct communities. The upper layers of the cone-shaped structures have a higher abundance of the cyanobacterial MAG Microcoleus, while the pinnacle-shaped structures have a higher abundance of Elainellacea MAG. This suggests that cyanobacteria influence the morphologies of the mats. We identified stark contrasts in the composition of the community and its metabolic potential between the upper and lower layers of the mat. The upper layers of the mat, which receive light, have an increased abundance of photosynthetic pathways. In contrast, the lower layer has an increased abundance of heterotrophic pathways. Our results also showed that Lake Untersee is the first Antarctic lake with a substantial presence of ammonia-oxidizing Nitrospiracea and amoA genes. The genomic capacity for recycling biological molecules was prevalent across metagenome-assembled genomes (MAGs) that cover 19 phyla. This highlights the importance of nutrient scavenging in ultra-oligotrophic environments. Overall, our study provides new insights into the formation of microbial structures and the potential metabolic complexity of Antarctic laminated microbial mats. These mats are important environments for biodiversity that drives biogeochemical cycling in polar deserts.

Fluorine Rich Borate Salt Anion Based Electrolyte for High Voltage Sodium Metal Battery Development.

This study demonstrates the enhanced performance in high-voltage sodium full cells using a novel electrolyte composition featuring a highly fluorinated borate ester anion (1 M Na[B(hfip)4].3DME) in a binary carbonate mixture (EC:EMC), compared to a conventional electrolyte (1 M Na[PF6] EC:EMC). The prolonged cycling performance of sodium metal battery employing high voltage cathodes (NVPF@C@CNT and NFMO) is attributed to uniform and dense sodium deposition along with the formation of fluorine and boron-rich solid electrolyte interphase (SEI) on the sodium metal anode. Simultaneously, a robust cathode electrolyte interphase (CEI) is formed on the cathode side due to the improved electrochemical stability window and superior aluminum passivation of the novel electrolyte. The CEIs on high-voltage cathodes are discovered to be abundant in C-F, B-O, and B-F components, which contributes to long-term cycling stability by effectively suppressing undesirable side reactions and mitigating electrolyte decomposition. The participation of DME in the primary solvation shell coupled with the comparatively weaker interaction between Na+ and [B(hfip)4]- in the secondary solvation shell, provides additional confirmation of labile desolvation. This, in turn, supports the active participation of the anion in the formation of fluorine and boron-rich interphases on both the anode and cathode.

Impact of randomly assigned "pay-as-you-go" liquefied petroleum gas prices on energy use for cooking: Experimental pilot evidence from rural Rwanda.

The disease burden related to air pollution from traditional solid-fuel cooking practices in low- and middle-income countries impacts millions of people globally. Although the use of liquefied petroleum gas (LPG) fuel for cooking can meaningfully reduce household air pollution concentrations, major barriers, including affordability and accessibility, have limited widespread adoption. Using a randomized controlled trial, our objective was to evaluate the association between the cost and use of LPG among 23 rural Rwandan households. We provided a 2-burner LPG stove with accessories and incorporated a "pay-as-you-go" (PAYG) LPG service model that included fuel delivery. PAYG services remove the large up-front cost of cylinder refills by integrating "smart meter" technology that allows participants to pay in incremental amounts, as needed. We assigned three randomized discounted prices for LPG to each household at ~4-week intervals over a 12-week period. We modeled the relationship between randomized PAYG LPG price and use (standardized to monthly periods), analyzing effect modification by relative household wealth. A 1000 Rwandan Franc (about 1 USD at the time of the study) increase in LPG price/kg was associated with a 4.1 kg/month decrease in use (95% confidence interval [CI]: -6.7, -1.6; n=69 observations). Wealth modified this association; we observed a 9.7 kg/month reduction (95% CI: -14.8, -4.5) among wealthier households and a 2.5 kg/month reduction (95% CI: -5.3, 0.3) among lower-wealth households (p-interaction=0.01). The difference in price sensitivity was driven by higher LPG use among wealthier households at more heavily discounted prices; from an 80% to 10% discount, wealthy households used 17.5 to 5.3 kg/month and less wealthy households used 6.2 to 3.1 kg/month. Our pilot-level experimental evidence of PAYG LPG in a rural low-resource setting suggests that further exploration of subsidized pricing varied by household wealth is needed to ensure future policy initiatives can achieve targets without exacerbating inequities.

Shot noise in a strange metal.

Strange-metal behavior has been observed in materials ranging from high-temperature superconductors to heavy fermion metals. In conventional metals, current is carried by quasiparticles; although it has been suggested that quasiparticles are absent in strange metals, direct experimental evidence is lacking. We measured shot noise to probe the granularity of the current-carrying excitations in nanowires of the heavy fermion strange metal YbRh2Si2. When compared with conventional metals, shot noise in these nanowires is strongly suppressed. This suppression cannot be attributed to either electron-phonon or electron-electron interactions in a Fermi liquid, which suggests that the current is not carried by well-defined quasiparticles in the strange-metal regime that we probed. Our work sets the stage for similar studies of other strange metals.

Fluoroborate ionic liquids as sodium battery electrolytes.

High-voltage sodium batteries are an appealing solution for economical energy storage applications. Currently available electrolyte materials have seen limited success in such applications therefore the identification of high-performing and safer alternatives is urgently required. Herein we synthesise six novel ionic liquids derived from two fluoroborate anions which have shown great promise in recent battery literature. This study reports for the first time the electrochemically applicable room-temperature ionic liquid (RTIL) N-ethyl-N,N,N-tris(2-(2-methoxyethoxy)ethyl)ammonium (tetrakis)hexafluoroisopropoxy borate ([N2(2O2O1)3][B(hfip)4]). The RTIL shows promising physical properties with a very low glass-transition at -73 °C and low viscosity. The RTIL exhibits an electrochemical window of 5.3 V on a glassy carbon substrate which enables high stability electrochemical cycling of sodium in a 3-electrode system. Of particular note is the strong passivation behaviour of [N2(2O2O1)3][B(hfip)4] on aluminium current-collector foil at potentials as high as 7 V (vs. Na+/Na) which is further improved with the addition of 50 mol% Na[FSI]. This study shows [B(hfip)4]- ionic liquids have the desired physical and electrochemical properties for high-voltage sodium electrolytes.

Evolutionary History Mediates Population Response to Rapid Environmental Change through Within-Generational and Transgenerational Plasticity.

AbstractRapid environmental change is affecting many organisms; some are coping well, but many species are in decline. A key mechanism for facilitating success following environmental change is phenotypic plasticity. Organisms use cues to respond phenotypically to environmental conditions; many incorporate recent information (within-generation plasticity) and information from previous generations (transgenerational plasticity). We extend an existing evolutionary model where organisms utilize within-generational plasticity, transgenerational plasticity, and bet hedging to include changes in environmental regime. We show how when rapid evolution of plasticity is not possible, the effect of environmental change (altering the environment mean, variance, or autocorrelation or cue reliability) on population growth rate depends on the population's evolutionary history and past evolutionary responses to historical environmental conditions. We then evaluate the predictions that populations adapted to highly variable environments or with greater within-generational plasticity are more likely to successfully respond to environmental change. We identify when these predictions fail and show that environmental change is most detrimental when previously reliable cues become unreliable. When multiple cues become unreliable, environmental change can cause deleterious effects regardless of the population's evolutionary history. Overall, this work provides a general framework for understanding the role of plasticity in population responses to rapid environmental change.

Water sources and composition of dissolved gases and bubbles in a saline high Arctic spring.

We investigate the water sources for a perennial spring, "Little Black Pond," located at Expedition Fiord, Axel Heiberg Island in the Canadian High Arctic based on dissolved gases. We measured the dissolved O2 in the likely sources Phantom Lake and Astro Lake and the composition of noble gases (3He/4He, 4He, Ne,36Ar, 40Ar, Kr, Xe), N2, O2, CO2, H2S, CH4, and tritium dissolved in the outflow water and bubbles emanating from the spring. The spring is associated with gypsum-anhydrite piercement structures and occurs in a region of thick, continuous permafrost (400-600 m). The water columns in Phantom and Astro lakes are uniform and saturated with O2. The high salinity of the water emanating from the spring, about twice sea water, affects the gas solubility. Oxygen in the water and bubbles is below the detection limit. The N2/Ar ratio in the bubbles and the salty water is 89.9 and 40, respectively, and the relative ratios of the noble gases, with the exception of Neon, are consistent with air dissolved in lake water mixed with air trapped in glacier bubbles as the source of the gases. The Ne/Ar ratio is ~62% of the air value. Our results indicate that about half (0.47±0.1) of the spring water derives from the lakes and the other half from subglacial melt. The tritium and helium results indicate that the groundwater residence time is over 70 years and could be thousands of years.

Synthesis of Poly(allyl glycidyl ether)-Derived Polyampholytes and Their Application to the Cryopreservation of Living Cells.

Through the postpolymerization modification of poly(allyl glycidyl ether) (PAGE), a functionalizable polyether with a poly(ethylene oxide) backbone, we engineered a new class of highly tunable polyampholyte materials. These polyampholytes can be synthesized to have several useful properties, including low cytotoxicity and pH-responsive coacervate formation. In this study, we used PAGE-based polyampholytes (PAGE-PAs) for the cryopreservation of mammalian cell suspensions. Typically, dimethyl sulfoxide (DMSO) is the cryoprotectant used for preserving mammalian cells, but DMSO suffers from key drawbacks including toxicity and difficult post-thaw removal that motivates the development of new materials and methods. Toxicity and post-thaw survival were dependent on PAGE-PA composition with the highest immediate post-thaw survival for normal human dermal fibroblasts occurring for the least toxic PAGE-PA at a cation/anion ratio of 35:65. With low toxicity, the PAGE-PA concentration could be increased in order to increase immediate post-thaw survival of the immortalized mouse embryonic fibroblasts (NIH/3T3). While immediate post-thaw viability was achieved using only the PAGE-PAs, long-term cell survival was low, highlighting the challenges involved with the design of cryoprotective polyampholytes. An environment utilizing both PAGE-PAs and DMSO in a cryoprotective solution offered promising post-thaw viabilities exceeding 70%, with long-term metabolic activities comparable to unfrozen cells.

Assessment of vulnerability to water shortage in semi-arid river basins: The value of demand reduction and storage capacity.

Interest in securing reliable water supplies has increased due to climate change and rapid population growth. This challenge is significant in growing areas with limited water supplies. To meet water demands, water managers are considering new storage infrastructure to increase the reliability of water supplies while also identifying opportunities to reduce water use per person. Although these strategies change water consumption patterns, their success at reducing shortages across space and time for different climate change scenarios remains unclear. In this paper, population- and climate-dependent future water supply and demand models are developed and integrated into a water allocation model calibrated for the South Platte River Basin of Colorado. Eight future climate scenarios are simulated using four statistically downscaled models from the Coupled Model Inter-Comparison Project Phase 5 (CMIP5) with two Representative Concentration Pathways (RCP). Lastly, findings from the water allocation model simulations are generalized beyond the study area using a novel approach by introducing dimensionless indices to characterize water shortage and basin conditions. Results reveal a threshold ratio of total storage capacity to mean water supply with a value of 0.64 above which additional storage has no effect on total water shortages. This threshold communicates the limitation of building storage infrastructure as a strategy to adapt to decreasing average water supplies for basins considering increasing storage capacity. However, basins with low current capacity are likely to fall below the threshold and could invest in reservoirs to mitigate future shortages.

Survival strategies of an anoxic microbial ecosystem in Lake Untersee, a potential analog for Enceladus.

Lake Untersee located in Eastern Antarctica, is a perennially ice-covered lake. At the bottom of its southern basin lies 20 m of anoxic, methane rich, stratified water, making it a good analog for Enceladus, a moon of Saturn. Here we present the first metagenomic study of this basin and detail the community composition and functional potential of the microbial communities at 92 m, 99 m depths and within the anoxic sediment. A diverse and well-populated microbial community was found, presenting the potential for Enceladus to have a diverse and abundant community. We also explored methanogenesis, sulfur metabolism, and nitrogen metabolism, given the potential presence of these compounds on Enceladus. We found an abundance of these pathways offering a variety of metabolic strategies. Additionally, the extreme conditions of the anoxic basin make it optimal for testing spaceflight technology and life detection methods for future Enceladus exploration.

Draft Genome Sequence from a Putative New Genus and Species in the Family M1A02 within the Phylum Planctomycetes, Isolated from Benthic Pinnacle Mats in Lake Untersee, Antarctica.

Here, we report the draft genome sequence for a new putative genus and species in the family M1A02 within the order Phycisphaerales. Isolated from the metagenome of a benthic pinnacle-shaped mat in the Antarctic Lake Untersee, the members of this family have been found in biofilms and freshwater environments.

Protocol design and synopsis: Omalizumab as Monotherapy and as Adjunct Therapy to Multiallergen OIT in Children and Adults with Food Allergy (OUtMATCH).

Background: Food allergy is common and causes substantial morbidity and even mortality. Safe and effective treatments for food allergy would therefore be highly desirable, especially for individuals with multiple food allergies. Objectives: Our aim was to describe a phase 3 study on treatment of patients with multiple food allergies with omalizumab. Methods: The study was developed as a collaboration between the Consortium for Food Allergy Research, the National Institute of Allergy and Infectious Diseases, and 2 industry sponsors (Genentech and Novartis). Results: The study is currently under way, enrolling participants from age 1 year to age 55 years who are allergic to peanut and at least 2 other foods (including milk, egg, wheat, cashew, hazelnut, and walnut). The study is designed to address 3 major questions. First, stage 1 will study the potential value of omalizumab for the treatment of patients with peanut allergy and at least 2 other common food allergens. Second, stage 2 will directly compare treatment of patients with multifood allergies using omalizumab as monotherapy versus treatment with omalizumab-facilitated multiallergen oral immunotherapy in which omalizumab is used as an adjunctive treatment. Third, stage 3 will address the longer-term outcomes following these treatment approaches, including the introduction of dietary forms of the study foods to induce or maintain desensitization. Conclusions: This phase 3 study will provide important information on the potential of omalizumab to treat patients with multiple food allergies.

Generalizing effects of frontostriatal structural connectivity on self-esteem using predictive modeling.

Determining the generalizability of biological mechanisms supporting psychological constructs is a central goal of cognitive neuroscience. Self-esteem is a popular psychological construct that is associated with a variety of measures of mental health and life satisfaction. Recently, there has been interest in identifying biological mechanisms that support individual differences in self-esteem. Understanding the biological basis of self-esteem requires identifying predictive biomarkers of self-esteem that generalize across groups of individuals. Previous research using diffusion magnetic resonance imaging has shown that self-esteem is related to the integrity of structural connections linking frontostriatal brain systems involved in self-referential processing and reward. However, these findings were based on a small, relatively homogeneous group of participants. In the current study, we used an out-of-sample predictive modeling approach to generalize the results of the previous study to an independent sample of participants more than twice the size of the original study. We found that both linear univariate and multivariate machine learning models trained on frontostriatal integrity from the original data significantly predicted self-esteem in the independent dataset. These findings underscore the relationship between self-esteem and frontostriatal connectivity and suggest these results are robust to differences in scanning acquisition, analytic methods, and participant demographics.

Changing climate, changing minds? The effects of natural disasters on public perceptions of climate change.

The frequency and intensity of natural disasters such as hurricanes, wildfires, and floods are predicted to change as greenhouse gas concentrations increase. These disasters may represent sources of information for individuals as they update their beliefs related to climate change. Using a dataset that includes climate beliefs of respondents, we examine the effect of natural disasters on climate change beliefs and find that hurricanes significantly increase the probability that survey respondents from a given county believe that climate change is occurring and that it is human caused. We find that past experience with certain types of natural disasters (e.g., hurricanes) impacts beliefs regarding whether climate change is occurring and if it is human caused. The research contributes to the literature evaluating climate change attitudes by using spatially disaggregate information on climate change beliefs and exposure to a set of natural disasters over time. Characterizing beliefs and attitudes toward climate change and related policies is important since these beliefs are a determinant of individual adaptation and support for policies related to reducing carbon emissions.

High-resolution epitope mapping by AllerScan reveals relationships between IgE and IgG repertoires during peanut oral immunotherapy.

Peanut allergy can result in life-threatening reactions and is a major public health concern. Oral immunotherapy (OIT) induces desensitization to food allergens through administration of increasing amounts of allergen. To dissect peanut-specific immunoglobulin E (IgE) and IgG responses in subjects undergoing OIT, we have developed AllerScan, a method that leverages phage-display and next-generation sequencing to identify the epitope targets of peanut-specific antibodies. We observe a striking diversification and boosting of the peanut-specific IgG repertoire after OIT and a reduction in pre-existing IgE levels against individual epitopes. High-resolution epitope mapping reveals shared recognition of public epitopes in Ara h 1, 2, 3, and 7. In individual subjects, OIT-induced IgG specificities overlap extensively with IgE and exhibit strikingly similar antibody footprints, suggesting related clonal lineages or convergent evolution of peanut-specific IgE and IgG B cells. Individual differences in epitope recognition identified via AllerScan could inform safer and more effective personalized immunotherapy.

Large-scale functional coactivation patterns reflect the structural connectivity of the medial prefrontal cortex.

The medial prefrontal cortex (MPFC) is among the most consistently implicated brain regions in social and affective neuroscience. Yet, this region is also highly functionally heterogeneous across many domains and has diverse patterns of connectivity. The extent to which the communication of functional networks in this area is facilitated by its underlying structural connectivity fingerprint is critical for understanding how psychological phenomena are represented within this region. In the current study, we combined diffusion magnetic resonance imaging and probabilistic tractography with large-scale meta-analysis to investigate the degree to which the functional coactivation patterns of the MPFC are reflected in its underlying structural connectivity. Using unsupervised machine learning techniques, we compared parcellations between the two modalities and found congruence between parcellations at multiple spatial scales. Additionally, using connectivity and coactivation similarity analyses, we found high correspondence in voxel-to-voxel similarity between each modality across most, but not all, subregions of the MPFC. These results provide evidence that meta-analytic functional coactivation patterns are meaningfully constrained by underlying neuroanatomical connectivity and provide convergent evidence of distinct subregions within the MPFC involved in affective processing and social cognition.

Microbial Diversity of Pinnacle and Conical Microbial Mats in the Perennially Ice-Covered Lake Untersee, East Antarctica.

Antarctic perennially ice-covered lakes provide a stable low-disturbance environment where complex microbially mediated structures can grow. Lake Untersee, an ultra-oligotrophic lake in East Antarctica, has the lake floor covered in benthic microbial mat communities, where laminated organo-sedimentary structures form with three distinct, sympatric morphologies: small, elongated cuspate pinnacles, large complex cones and flat mats. We examined the diversity of prokaryotes and eukaryotes in pinnacles, cones and flat microbial mats using high-throughput sequencing of 16S and 18S rRNA genes and assessed how microbial composition may underpin the formation of these distinct macroscopic mat morphologies under the same environmental conditions. Our analysis identified distinct clustering of microbial communities according to mat morphology. The prokaryotic communities were dominated by Cyanobacteria, Proteobacteria, Verrucomicrobia, Planctomycetes, and Actinobacteria. While filamentous Tychonema cyanobacteria were common in all mat types, Leptolyngbya showed an increased relative abundance in the pinnacle structures only. Our study provides the first report of the eukaryotic community structure of Lake Untersee benthic mats, which was dominated by Ciliophora, Chlorophyta, Fungi, Cercozoa, and Discicristata. The eukaryote richness was lower than for prokaryote assemblages and no distinct clustering was observed between mat morphologies. These findings suggest that cyanobacterial assemblages and potentially other bacteria and eukaryotes may influence structure morphogenesis, allowing distinct structures to form across a small spatial scale.

Mechanism of Polymer-Mediated Cryopreservation Using Poly(methyl glycidyl sulfoxide).

Under the right conditions, some biological systems can maintain high viability after being frozen and thawed, but many others (e.g., organs and many mammalian cells) cannot. To increase the rates of post-thaw viability and widen the library of living cells and tissues that can be stored frozen, an improved understanding of the mode of action of polymeric cryoprotectants is required. Here, we present a polymeric cryoprotectant, poly(methyl glycidyl sulfoxide) (PMGS), that achieved higher post-thaw viability for fibroblast cells than its small-molecule analogue dimethyl sulfoxide. By limiting the amount of water that freezes and facilitating cellular dehydration after ice nucleation, PMGS mitigates the mechanical and osmotic stresses that the freezing of water imparts on cells and facilitates higher-temperature vitrification of the remaining unfrozen volume. The development of PMGS advances a fundamental physical understanding of polymer-mediated cryopreservation, which enables new material design for long-term preservation of complex cellular networks and tissue.