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Biogeochemical processing of dissolved organic matter (DOM) in headwater rivers regulates aquatic food web dynamics, water quality, and carbon storage. Although headwater rivers are critical sources of energy to downstream ecosystems, underlying mechanisms structuring DOM composition and reactivity are not well quantified. By pairing mass spectrometry and fluorescence spectroscopy, here we show that hydrology and river geomorphology interactively shape molecular patterns in DOM composition. River segments with a single channel flowing across the valley bottom export DOM with a similar chemical profile through time. In contrast, segments with multiple channels of flow store large volumes of water during peak flows, which they release downstream throughout the summer. As flows subside, losses of lateral floodplain connectivity significantly increase the heterogeneity of DOM exported downstream. By linking geomorphologic landscape-scale processes with microbial metabolism, we show DOM heterogeneity increases as a function of fluvial complexity, with implications for ecosystem function and watershed management. The underlying mechanisms structuring dissolved organic matter (DOM) composition and reactivity in rivers remain poorly quantified. Here, the authors pair mass spectrometry and fluorescence spectroscopy to show that hydrology and river geomorphology both shape molecular patterns in DOM composition. [ABSTRACT FROM AUTHOR]

Increased plant productivity and decreased microbial respiratory C loss can potentially mitigate increasing atmospheric CO2, but we currently lack effective means to achieve these goals. Soil microbes may play critical roles in mediating plant productivity and soil C/N dynamics under future climate scenarios of elevated CO2 (eCO2) through optimizing functioning of the root-soil interface. By using a labeling technique with 13C and 15N, we examined the effects of plant growth-promoting Pseudomonas fluorescens on C and N cycling in the rhizosphere of a common grass species under eCO2. These microbial inoculants were shown to increase plant productivity. Although strong competition for N between the plant and soil microbes was observed, the plant can increase its capacity to store more biomass C per unit of N under P. fluorescens addition. Unlike eCO2 effects, P. fluorescens inoculants did not change mass-specific microbial respiration and accelerate soil decomposition related to N cycling, suggesting these microbial inoculants mitigated positive feedbacks of soil microbial decomposition to eCO2. The potential to mitigate climate change by optimizing soil microbial functioning by plant growth-promoting Pseudomonas fluorescens is a prospect for ecosystem management. [ABSTRACT FROM AUTHOR]

Objective:Our objective was to identify factors associated with recurrent preterm birth among underweight women. Methods:Maternally linked hospital and birth certificate records of deliveries in California between 2007 and 2010 were used. Consecutive singleton pregnancies of women with underweight body mass index (BMI <18.5 kg/m2) in the first pregnancy were analyzed. Pregnancies were categorized based on outcome of the first and second birth as: term-term; term-preterm; preterm-term and preterm-preterm. Results:We analyzed 4971 women with underweight BMI in the first pregnancy. Of these, 670 had at least one preterm birth. Among these 670, 86 (21.8%) women experienced a recurrent preterm birth. Odds for first term – second preterm birth were decreased for increases in maternal age (aOR: 0.90, 95%CI: 0.95–0.99) whereas inter-pregnancy interval <6 months was related to both first term – second preterm birth (aOR:1.66, 95%CI: 1.21–2.28) and first preterm birth – second term birth (aOR: 1.43, 95%CI: 1.04–1.96). Factors associated with recurrent preterm birth were: negative or no change in pre-pregnancy weight between pregnancies (aOR: 1.67, 95%CI: 1.07–2.60), inter-pregnancy interval <6 months (aOR: 2.14, 95%CI: 1.29–3.56), and maternal age in the first pregnancy (aOR: 0.93, 95%CI: 0.90–0.97). Conclusions:Recurrent preterm birth among underweight women was associated with younger age, short inter-pregnancy interval, and negative or no weight change between pregnancies. [ABSTRACT FROM PUBLISHER]

A letter to the editor is presented in response to the article "Learning the right lessons from the SUPPORT study controversy" by John D. Lantos in a 2014 issue.

Plant-associated microbiomes have tremendous potential to improve plant resilience and yields in farming systems. There is increasing evidence that biological technologies that use microbes or their metabolites can enhance nutrient uptake and yield, control pests and mitigate plant stress responses. However, to fully realize the potential of microbial technology, their efficacy and consistency under the broad range of real-world conditions need to be improved. While the optimization of microbial biofertilizers and biopesticides is advancing rapidly to enable use in various soils, crop varieties and environments, crop breeding programmes have yet to incorporate the selection of beneficial plant-microbe interactions to breed 'microbe-optimized plants'. Emerging efforts exploring microbiome engineering could lead to microbial consortia that are better suited to support plants. The combination of all three approaches could be integrated to achieve maximum benefits and significantly improved crop yields to address food security. [ABSTRACT FROM AUTHOR]

In the roundtable that follows, clinicians discuss a study published in this issue of the Journal in light of its methodology, relevance to practice, and implications for future research. Article discussed: Berrébi A, Assouline C, Bessières M-H, et al. Long-term outcome of children with congenital toxoplasmosis. Am J Obstet Gynecol 2010;203:552.e1-6. [Copyright &y& Elsevier]

Hartley et al. question whether reduction in Rmass, under experimental warming, arises because of the biomass method. We show the method they treat as independent yields the same result. We describe why the substrate-depletion hypothesis may not solely explain observed responses, and urge caution in interpretation of the seasonal data. [ABSTRACT FROM AUTHOR]

The adoption of conservation agriculture has gained considerable attention due to growing interest in managing soil biological diversity and overall soil health. However, there is limited understanding of how practices such as conservation tillage and residue retention affect soil biota across different spatial scales and are associated with alterations to other soil properties. In this study, we examined changes in soil physicochemical properties, soil macrofauna, and microbial communities at two soil depths (0–10 cm, and 10–20 cm) in a 6-year field experiment manipulating tillage and maize residue management. The following treatments were included in the experiment: no-till with residue retention; no-till with residue harvest; conventional tillage with residue retention; and conventional tillage with residue harvest. Macrofauna taxa were identified and estimated visually, while bacterial and fungal communities were identified and analyzed using high throughput sequencing and multivariate statistics including non-metric dimensional scaling and indicator species analysis. Soil physicochemical properties measured include soil carbon and nitrogen, soil moisture, permanganate oxidizable carbon, available soil phosphate, pH, electrical conductivity and aggregate stability. Residue retention increased macrofauna abundance and diversity across soil depths and tillage treatments. Fungal diversity was also highest under residue retention in the topsoil (0–10 cm), while bacterial diversity was generally higher under conventional tillage. Residue retention was the main driver of macrofauna and microbial community composition, while an interaction between tillage and residue management indicated that the effect of tillage on microbial communities was most pronounced when residues were retained. Soil carbon and nitrogen, aggregate stability, permanganate oxidizable carbon, soil moisture content, available soil phosphate and soil electrical conductivity were all enhanced under residue retention in the topsoil. Indicator species analysis suggested that macrofauna taxa belonging to Annelida, Aranaea and Chilopoda together with bacterial phyla Fibrobacteres and fungal phyla Rozellomycota were indicators for no-till combined with residue retention, while Coleoptera, Spirochaetae and Basidiomycota were indicators for conventional tillage with residue retention. Multivariate analyses suggested that total macrofauna abundance, soil carbon and pH were strongly associated with bacterial and fungal community composition in the topsoil layer. Co-inertia analysis indicated significant covariation between soil physicochemical, macrofauna, bacterial and fungal datasets, suggesting a strong association between different soil parameters and cascading effects of management on multiple soil properties. Our findings demonstrate that residue retention enhances soil biological, physical and chemical properties and that communities of soil macro- and microorganisms tend to respond in similar ways to these management interventions. • Tillage and residue management affected soil macrofauna and microbial communities in similar ways. • Residue retention generally improve soil physicochemical properties and biological diversity in the surface soil layer. • The effects of tillage on soil biological communities were generally small, but more pronounced under residue retention. • Changes in soil microbial communities were associated with alterations to both soil physicochemical properties (mainly soil C and pH) and soil macrofauna abundance. [ABSTRACT FROM AUTHOR]

Abstract: Although potential enzyme activity measurements have a long history of use as an indicator of microbial activity, current methods do not provide accurate estimates of in situ activity. In the field, diffusion rates typically limit the rate at which enzymes can pair with substrates. However, the common laboratory practice of creating soil slurries removes all diffusion constraints. In addition, temperature strongly affects in situ enzyme activities, but is rarely considered in enzyme assays. To address these limitations, we developed a new protocol to measure the moisture and temperature sensitivity of enzyme activities. We incorporated sensitivity data obtained using this protocol into a model to estimate the effects of temperature and moisture on in situ β-glucosidase enzyme activity, recognizing that other factors such as substrate concentrations and diffusion constraints also affect in situ enzyme activities. Soil samples were collected from the Boston-Area Climate Experiment every two weeks over a 10-week period to track enzyme dynamics as field temperature and moisture changed. Precipitation inputs to an old-field were manipulated to produce drought (50% ambient precipitation), ambient, and wet (150% ambient precipitation) treatments. Temperature sensitivity of β-glucosidase was determined by assaying for the enzyme in soil slurries at three different temperatures (15, 25 and 35 °C). Moisture sensitivity was determined by exposing soils to different moisture levels in the lab and adding substrate to homogenized dry or moist soils instead of slurries. Temperature sensitivity was calculated as Q 10 and moisture sensitivity was calculated using a linear regression for each field treatment at each sample collection date. Moisture sensitivity varied significantly among the five sample dates and treatments, whereas temperature sensitivity remained stable. At almost every time point, β-glucosidase activity responded more strongly to increased moisture in soils of drought plots than in soils of ambient and wet plots. We estimated in situ β-glucosidase activity in the fall using the temperature and moisture sensitivities. Estimates that used only temperature or only moisture sensitivity suggested that ambient plots had the highest activity, followed by wet and then drought plots. Estimates based on both temperature and moisture suggested that β-glucosidase activity responded primarily to changes in temperature, except when soils were dry, with water potentials below −1 MPa. These results demonstrate that low soil moisture can strongly limit in situ enzyme activity in soils, negating any positive effect of warming. This study provides a template for parsing out the role of specific abiotic drivers on in situ enzyme activities, which could lead to the explicit incorporation of enzymes in biogeochemical models, improving upon the ability of current models to predict rates of biogeochemical processes in dynamic environments. [Copyright &y& Elsevier]

Soil organic matter (SOM) plays a central role in mediating soil productivity through its impacts on nutrient cycling and retention, aggregate stability and water retention. Thus, management techniques or technologies including novel soil amendments could benefit farmers through the accumulation of carbon (C) and other nutrients in SOM. However, these same inputs can also lead to accelerated mineralization of native SOM through the process known as priming. This unresolved paradox may be due to the limited understanding of how different SOM fractions respond to priming and in which direction. In this study, we examine the response of functionally distinct SOM fractions to priming when soils are amended with lactobionate, a low molecular weight sugar acid byproduct of cheese manufacturing. Liquid-based 13C lactobionate was added to an agricultural silty loam soil to study its persistence, priming effects, and response of different SOM fractions to lactobionate over 84 days. Cumulative soil carbon dioxide (CO 2) was greater in lactobionate-amended soils versus control and by the end of the experiment, 53% of added lactobionate was mineralized. In total, positive priming of 40% of extant SOM was observed from 14 to 84 days. Lactobionate-induced changes to SOM fractions were determined at days 14, 28, 56 and 84 of the incubation to examine if and how priming altered the distribution of C between fast and slow-cycling SOC fractions. In response to lactobionate, the total C content of the water extractable organic matter (WEOM) fraction initially increased by 100% from the dissolved lactobionate we added, but then declined and at a faster rate than other SOM fractions. In addition, the total C of the light-fraction particulate organic matter (LF-POM) fraction also declined. At the same time, we observed total C increases in the slower-cycling sand-sized POM (H-POM) and mineral-associated organic (MAOM) C fractions, in response to lactobionate additions. We also saw a marginal increase in total soil C in the lactobionate-amended soils. Our findings therefore suggest that the application of lactobionate to soils may induce positive priming of the faster cycling LF-POM and WEOM fractions, but also concurrent gains in the H-POM and MAOM C fractions associated with long-term persistence and relative resiliency to disturbance with no net loss of total soil carbon. Thus, the application of low-molecular weight C-based materials such as lactobionate presents an avenue to building more persistent SOM through its impacts on the internal cycling and transformation of SOM fractions. • We examined the response of distinct soil organic matter fractions to priming. • Light-fraction particulate organic matter declined in carbon and nitrogen under positive priming. • Heavy/sand-sized particulate organic matter increased under positive priming. • Mineral-associated organic matter also increased under positive priming. • Less protected soil organic matter fractions are a source of primed carbon. [ABSTRACT FROM AUTHOR]

Thus, soil organic C storage is linked to N availability and can result in N immobilization in SOM with feedbacks to plant productivity. In-N-Out: A hierarchical framework to understand and predict soil carbon storage and nitrogen recycling Conversely, when N is available in excess of plant and microbial demand, the C and N cycles decouple, and N is lost from the system. We further hypothesize that C input-limited systems have N in excess of demand, resulting in decoupling of the N and C cycles, and the opening of N cycle to losses from the soil. [Extracted from the article]

• The relationship between gross N turnover and temperature and moisture varies on annual and seasonal scales. • The gross N turnover under the influence of temperature and water is different between field and laboratory conditions. • Soil temperature has more influence on soil gross nitrogen turnover than moisture. Understanding how soil nitrogen (N) turnover responds to temperature and soil moisture alterations is important for accurately predicting responses of soil N availability and plant productivity to global climate change. However, few studies had explored such questions under natural conditions. We investigated effects of temperature and moisture on soil gross N turnover with an annual scale field experiment in an Inner Mongolian grassland and a laboratory incubation experiment. In the field experiment, on the annual scale both gross ammonification and nitrification rates showed a hump-shaped response to temperature, with maximum rates occurring around 10 °C and 5 °C, respectively. Gross ammonification rates did not respond to soil moisture, and gross nitrification rates decreased first and then increasing with soil moisture, which the threshold was 35% water holding capacity (WHC). Totally, soil temperature explained more variation than moisture in gross ammonification (0.30 VS 0.04) and nitrification (0.24 VS 0.14) rates. On the seasonal scale, both soil temperature and moisture showed generally significant effects on gross N turnover. Grazing had no effects on soil temperature and moisture sensitivity of gross N turnover on the annual scale, but increased the sensitivity of gross ammonification to soil moisture during the spring freeze–thaw period. In the laboratory incubation experiment, gross ammonification and nitrification rates increased with the increase of temperature, although there was no difference between 20 °C and 30 °C. Gross ammonification rates reached a maximum at 50% WHC, while gross nitrification rates did not respond to soil moisture until 100% WHC. Soil temperature explained more variation than moisture in gross ammonification (0.71 VS 0.01) and nitrification (0.37 VS 0.25) rates. Our results imply that climate warming may have greater impact on gross nitrogen turnover compared to changes in rainfall, however it remains great uncertainty due to the low explanation of soil temperature and moisture. [ABSTRACT FROM AUTHOR]

Abstract Crop yield reductions are common in drought-stressed agroecosystems and are likely to become more frequent with climate change. To combat this, soil amendments are often used to enhance soil moisture retention but typically only lead to marginal improvements. Moreover, even as concern over agricultural water use mounts, a large fraction of food is wasted. Diverting more food waste and byproducts back to agricultural fields could reduce waste issues while ameliorating critical water limitations. We evaluated lactobionate, a lactose derivative and major dairy industry byproduct, as a potential soil amendment for enhancing both soil moisture and soil organic carbon (SOC). Lactobionate (LB) is a hydrophilic compound consisting primarily of cations and simple sugar acids. These combined properties could synergistically modify numerous controls on soil-water balances. In a laboratory setting, we compared LB stabilized with various cations (K+, NH 4 +, and Ca+) across a range of soil types to determine LB effects on soil moisture and SOC retention. All LB amendments increased soil water content relative to unamended soil across a range of soil matric potentials and raised available water content by 37%. Additionally, LB amended soils had on average 70 times more microbial biomass and decreased soil inorganic nitrogen content compared to unamended soils. We found that K+-LB, the most effective amendment, increased soil water content by 100–600% compared to unamended soils and as much as 87% of the increased SOC following LB additions was retained after 2 months. Our results suggest that tapping into novel sources of organic inputs such as LB may be an effective approach for simultaneously enhancing soil moisture and carbon stocks while increasing the economic and energetic value of food production byproducts. Highlights • Lactobionate was evaluated for increases in soil carbon and water retention. • Lactobionate increased available water content by 37%. • Elevated soil carbon concentrations with lactobionate persisted for two months. • Soils amended with lactobionate had 70 times more microbial biomass. • Lactobionate is an effective soil amendment for carbon and moisture-limited soils. [ABSTRACT FROM AUTHOR]

Rapid climate warming in the Arctic threatens to destabilize vast stocks of soil carbon (C) that have accumulated over millennia, which could amplify the C-climate feedback. However, climate-induced shrub expansion may counteract these losses if their higher-quality litter (lower C:N) is efficiently incorporated into microbial products and stabilized within the soil. Alternatively, increased C inputs could stimulate microbial decomposition of old soil organic matter (SOM) through priming mechanisms. We investigated whether inputs of low molecular weight carbon (LMW-C) induced SOM priming or retention in soils underlying Eriophorum vaginatum , an ubiquitous tussock-forming sedge, and Betula nana, a dominant shrub that is expanding its range and coverage across the Arctic. We did not find evidence of priming, defined as an increase in the decomposition of native SOM stocks, from soils underlying either vegetation type. However, microbial respiration of new LMW-C inputs was twice as high in soils underlying E. vaginatum than B. nana, while belowground retention of new LMW-C inputs was 150% higher in soils underlying B. nana. Our results highlight the extraordinary capacity of shrub-colonized soils to retain new C inputs belowground, which may mitigate soil C loss as the Arctic climate warms. [ABSTRACT FROM AUTHOR]

Hereditary fructose intolerance (HFI) is an autosomal recessive disorder caused by aldolase B (ALDOB) deficiency resulting in an inability to metabolize fructose. The toxic accumulation of intermediate fructose-1-phosphate causes multiple metabolic disturbances, including postprandial hypoglycemia, lactic acidosis, electrolyte disturbance, and liver/kidney dysfunction. The clinical presentation varies depending on the age of exposure and the load of fructose. Some common infant formulas contain fructose in various forms, such as sucrose, a disaccharide of fructose and glucose. Exposure to formula containing fructogenic compounds is an important, but often overlooked trigger for severe metabolic disturbances in HFI. Here we report four neonates with undiagnosed HFI, all caused by the common, homozygous mutation c.448G>C (p.A150P) in ALDOB , who developed life-threatening acute liver failure due to fructose-containing formulas. These cases underscore the importance of dietary history and consideration of HFI in cases of neonatal or infantile acute liver failure for prompt diagnosis and treatment of HFI. [ABSTRACT FROM AUTHOR]

It is becoming increasingly clear that plant roots can impact the decomposition of existing soil C in the rhizosphere. Studies under controlled conditions suggest this impact may be plant species dependent, but whether this is the case in natural conditions or what factors underlie this variation is mostly unknown., With a novel field-based isotopic approach combining 13C-enriched glucose and 5-bromo-2-deoxyuridine additions, we compared in situ C decomposition of added labile C and native soil C (priming) among eight semi-arid grassland species' rhizospheres to investigate the factors driving inter-species variation. We examined the influence of several rhizosphere factors related to soil chemistry, microbial activity, microbial community, microbial stoichiometry, plant chemistry and root morphology., Plant species generated distinct microbial and chemical rhizosphere environments, which translated into differences in the direction, magnitude and temporal dynamics of the soil C priming. Soil C decomposition was positively related to soil C/P and soil N/P (via its influence on the bacterial community), which in turn were positively related to plant N/P. Plant C/N was also a significant factor via its negative influence on soil N/P. In contrast, the main direct predictors of labile C decomposition were microbial biomass, microbial C/N and the C-degrading enzymes, which in turn were linked to root morphology and C chemistry., Synthesis. Within this community, plant species' rhizospheres can vary in their susceptibility to C loss in response to changes in C availability. Soil stoichiometry, driven by plant chemical traits, appeared to be the strongest driver of priming. Our study suggests that shifts in plant communities involving increases in N relative to P have the greatest potential to lead to C loss. We provide evidence of root morphology and C chemistry as drivers of labile C processing in soil, a novel empirical contribution to our understanding of the role of plant traits below-ground. The contrasting regulation of different pools of soil C suggests observations of the regulation of simple C compounds should not be extrapolated to the whole C pool. Our findings provide support for rhizosphere-driven mechanisms by which shifts in plant community composition could have implications on the ecosystem-level C balance. [ABSTRACT FROM AUTHOR]

Greenhouse gas (GHG) emissions from thawed permafrost are difficult to predict because they result from complex interactions between abiotic drivers and multiple, often competing, microbial metabolic processes. Our objective was to characterize mechanisms controlling methane (CH) and carbon dioxide (CO) production from permafrost. We simulated permafrost thaw for the length of one growing season (90 days) in oxic and anoxic treatments at 1 and 15 °C to stimulate aerobic and anaerobic respiration. We measured headspace CH and CO concentrations, as well as soil chemical and biological parameters (e.g. dissolved organic carbon (DOC) chemistry, microbial enzyme activity, NO production, bacterial community structure), and applied an information theoretic approach and the Akaike information criterion to find the best explanation for mechanisms controlling GHG flux. In addition to temperature and redox status, CH production was explained by the relative abundance of methanogens, activity of non-methanogenic anaerobes, and substrate chemistry. Carbon dioxide production was explained by microbial community structure and chemistry of the DOC pool. We suggest that models of permafrost CO production are refined by a holistic view of the system, where the prokaryote community structure and detailed chemistry are considered. In contrast, although CH production is the result of many syntrophic interactions, these actions can be aggregated into a linear approach, where there is a single path of organic matter degradation and multiple conditions must be satisfied in order for methanogenesis to occur. This concept advances our mechanistic understanding of the processes governing anaerobic GHG flux, which is critical to understanding the impact the release of permafrost C will have on the global C cycle. [ABSTRACT FROM AUTHOR]

Soil organic matter (SOM) is extremely complex. It is composed of hundreds of different organic substances and it has been difficult to quantify these diverse substances in a dynamic- ecosystem functioning standpoint.Analytical pyrolysis has been used to compare chemical differences between soils, but its ability to measure the absolute amount of a specific compound in the soil is still in question.Our objective was to assess whether utilizing pyrolysis-molecular beam mass spectroscopy (py-MBMS) to define the signature of known reference compounds (adenine, indole, palmitic acid, etc.) and biological samples (chitin, fungi, cellulose, etc.) separately and when added to whole soils it was possible to make py-MBMS more quantitative.Reference compounds, spanning a wide variety of compound categories, and biological samples, expected to be present in SOM, were added to three soils from Colorado, Ohio, and Massachusetts that have varying total C, % clay, and clay type.Py-MBMS, a rapid analysis technique originally developed to analyze complex biomolecules, flash pyrolyzes soil organic matter to form products that are often considered characteristic of the original molecular structure. Samples were pyrolyzed at 550 °C by py-MBMS.All samples were weighed and %C and %N determined both before and after pyrolysis to evaluate mass loss, C loss, and N loss for the samples.An average relationship of r 2 = 0.76 ( P = 0.005) was found for the amount of cellulose added to soil at 25, 50, and 100% of soil C relative to the ion intensity of select mass/charge of the compound.There was a relationship of r 2 = 0.93 ( P < 0.001) for the amount of indole added to soil at 25, 50, and 100% of soil C and the ion intensity of the associated mass variables (mass/charge).Comparing spectra of pure compounds with the spectra of the compounds added to soil and isolated clay showed that interference could occur based on soil type and compound with the Massachusetts soil with high C (55.8 g C kg − 1 ) and low % clay (5.4%) having the least interference and the Colorado soil with low C (14.6 g C kg − 1 ) and a moderate smectite clay content of 14% having the greatest soil interference.Due to soil interference from clay type and content and varying optimum temperatures of pyrolysis for different compounds it is unlikely that analytical pyrolysis can be quantitative for all types of compounds.Select compound categories such as carbohydrates have the potential to be quantified in soil with analytical pyrolysis due to the fact that they: 1) almost fully pyrolyzed, 2) were represented by a limited number of m / z , and 3) had a strong relationship with the amount added and the total ion intensity produced.The three different soils utilized in this study had similar proportions of C pyrolyzed in the whole soil (54–57%) despite differences in %C and %clay between the soils. Mid-infrared spectroscopic analyses of the soil before and after pyrolysis showed that pyrolysis resulted in reductions in the 3400, 2930–2870, 1660 and 1430 cm − 1 bands.These bands are primarily representative of O H and N H bonds, C H stretch, and δ (CH 2 ) in polysaccharides/lipid and are associated with mineralizable SOM.The incorporation of standards into routine analytical pyrolysis allowed us to assess the quantitative potential of py-MBMS along with the effect of the mineral matrix, which we believe is applicable to all forms of analytical pyrolysis. [ABSTRACT FROM AUTHOR]

Increased plant productivity and decreased microbial respiratory C loss can potentially mitigate increasing atmospheric CO2, but we currently lack effective means to achieve these goals. Soil microbes may play critical roles in mediating plant productivity and soil C/N dynamics under future climate scenarios of elevated CO2 (eCO2) through optimizing functioning of the root-soil interface. By using a labeling technique with 13C and 15N, we examined the effects of plant growth-promoting Pseudomonas fluorescens on C and N cycling in the rhizosphere of a common grass species under eCO2. These microbial inoculants were shown to increase plant productivity. Although strong competition for N between the plant and soil microbes was observed, the plant can increase its capacity to store more biomass C per unit of N under P. fluorescens addition. Unlike eCO2 effects, P. fluorescens inoculants did not change mass-specific microbial respiration and accelerate soil decomposition related to N cycling, suggesting these microbial inoculants mitigated positive feedbacks of soil microbial decomposition to eCO2. The potential to mitigate climate change by optimizing soil microbial functioning by plant growth-promoting Pseudomonas fluorescens is a prospect for ecosystem management. [ABSTRACT FROM AUTHOR]

When plants establish in novel environments, they can modify soil microbial community structure and functional properties in ways that enhance their own success. Although soil microbial communities are influenced by abiotic environmental variability, rhizosphere microbial communities may also be affected by plant activities such as nutrient uptake during the growing season. We predicted that during the growing season, plant N uptake would explain much of the variation in rhizosphere microbial community assembly and functional traits. We grew the invasive C3 grass Bromus tectorum and three commonly co-occurring native C3 grasses in a controlled greenhouse environment, and examined rhizosphere bacterial community structural and functional characteristics at three different plant growth stages. We found that soil N availability and plant tissue N levels strongly correlated with shifts in rhizosphere bacterial community structure. It also appeared that the rapid drawdown of soil nutrients in the rhizosphere during the plant growing season triggered a selection event whereby only those microbes able to tolerate the changing nutrient conditions were able to persist. Plant N uptake rates inversely corresponded to microbial biomass N levels during periods of peak plant growth. Mechanisms which enable plants to influence rhizosphere bacterial community structure and function are likely to affect their competitive ability and fitness. Our study suggests that plants can alter their rhizosphere microbiomes through influencing nutrient availability. The ways in which plants establish their rhizosphere bacterial communities may now be viewed as a selection trait related to intrinsic plant species nutrient demands. [ABSTRACT FROM AUTHOR]

The implementation of soil health-promoting practices, such as cover cropping and compost application, has important implications for nutrient cycling and management in agroecosystems. At the same time, plant belowground carbon (C) allocation patterns can influence nutrient cycling and availability in soil through changes to the microbial community, but the effects may depend on the crop genotype and management practices in place. We evaluated belowground C allocation patterns using 13C labeling and root architecture in two genotypes of winter wheat (Triticum aestivum) with different levels of exudation and belowground allocation strategies in soils with contrasting compost amendment legacy (108.7 Mg ha−1 every 2 years over 10 years vs. no compost). We also measured microbial community structure and function in the rhizosphere and quantified uptake of residue-derived N from 15N-labelled cover crop residues. We found an interactive effect between soil management and genotype, where in the no-compost soil, the high-exudation genotype (Snowmass) increased exudation by over 4-fold, while the low-exudate genotype (Byrd) increased only 2-fold. While we did not observe genotype differences in rhizosphere enzyme activity or dissolved N pools, residue N uptake was 1.8 times greater for Snowmass in the compost-amended soil. There were more rhizosphere microbial taxa associated with the high-exudate genotype (Snowmass); nine bacterial and seven fungal families were indicative of Snowmass, versus one bacterial and four fungal families for Byrd. Our results suggest that the high-exudation strategy can influence the rhizosphere microbial community, and lead to greater short-term residue N uptake in high SOM soil. By directly linking root architecture, exudation, microbial communities, and N mineralization and uptake dynamics, this work demonstrates that plasticity in root C allocation is genotype-specific and influences microbial communities and nutrient cycling depending on the soil health context. • We evaluated belowground C in high- and low-exudate winter wheat genotypes with high/no compost amendment history • Net root exudation (assessed using 13C) and root growth were lower in the compost-amended soil. • Genotype differences in belowground allocation were greatest in the no-compost soil. • The high exudation genotype had greater numbers of specific indicator microbial taxa. • Genotype effects on organic N mobilization and uptake depended on soil management. [ABSTRACT FROM AUTHOR]

Declining rates of soil respiration are reliably observed during long-term laboratory incubations. However, the cause of this decline is uncertain. We explored different controls on soil respiration to elucidate the drivers of respiration rate declines during long-term soil incubations. Following a long-term (707 day) incubation (30 °C) of soils from two sites (a cultivated and a forested plot at Kellogg Biological Station, Hickory Corners, MI, USA), soils were significantly depleted of both soil carbon and microbial biomass. To test the ability of these carbon- and biomass-depleted ("incubation-depleted") soils to respire labile organic matter, we exposed soils to a second, 42 day incubation (30 °C) with and without an addition of plant residues. We controlled for soil carbon and microbial biomass depletion by incubating field fresh ("fresh") soils with and without an amendment of wheat and corn residues. Although respiration was consistently higher in the fresh versus incubation-depleted soil (2 and 1.2 times higher in the fresh cultivated and fresh forested soil, respectively), the ability to respire substrate did not differ between the fresh and incubation-depleted soils. Further, at the completion of the 42 day incubation, levels of microbial biomass in the incubation-depleted soils remained unchanged, while levels of microbial biomass in the field-fresh soil declined to levels similar to that of the incubation-depleted soils. Extra-cellular enzyme pools in the incubation-depleted soils were sometimes slightly reduced and did not respond to addition of labile substrate and did not limit soil respiration. Our results support the idea that available soil organic matter, rather than a lack microbial biomass and extracellular enzymes, limits soil respiration over the course of long-term incubations. That decomposition of both wheat and corn straw residues did not change after major changes in the soil biomass during extended incubation supports the omission of biomass values from biogeochemical models. [ABSTRACT FROM AUTHOR]

Soil health is a promising lens through which to approach land management, having the potential to serve as a descriptor of biophysical processes and as an effective communication tool across stakeholders. However, this potential has been largely unrealized due to difficulty in quantitatively assessing soil health and linking those assessments to outcomes. Here we discuss many multiple persistent obstacles to quantitative soil health assessment and outline a suite of analyses to help address those obstacles. Specifically, we propose a quantitative approach to developing and selecting soil health indicators that help connect management-induced changes in soil health to specific outcomes (e.g., yield or water quality). To demonstrate the utility of this approach, we perform a small case study using published data from North Carolina and New York cropping systems. Additionally, we outline how this approach is scalable and flexible enough to integrate future soil health metric development. The proposed approach stands to provide a quantitative, empirical basis for future measurement, assessment, and interpretation of soil health. • Robust and reliable quantitative soil health assessment has proved elusive. • Our pipeline addresses persistent pitfalls of current soil health assessment. • Indicator selection and connecting to agroecological outcomes are essential. • We outline an approach to soil health assessment that is rigorous and interpretable. [ABSTRACT FROM AUTHOR]

Semi-arid regions support the majority of global wheat production, but they are threatened by continued soil erosion and increased risk of drought and extreme temperatures from climate change. Enhancing soil organic matter (SOM) is a key adaptation strategy for sustaining agriculture in these regions because it can improve water retention and nutrient cycling. When seeking to increase SOM, growers face a dilemma, known as the 'soil carbon (C) dilemma' (Janzen, 2006): How can SOM be increased, while also increasing the release of nutrients that accompanies decomposition? Our observational study examined whether growers could address this dilemma through intensification with diverse grain crops. We specifically tested whether incorporating legumes into a continuous rotation influences the form and amount of SOM as well as productivity in farms of the central Great Plains region of the U.S. by contrasting three, no-till rotation systems: 1) conventional wheat-fallow; 2) continuous grain-only rotations, and 3) continuous grain rotations that incorporate a legume crop. We sampled on-farm fields and experimental agricultural research station plots that had received one of these rotations for at least eight years. We compared yield, soil organic C (SOC), and nitrogen (N) stocks in bulk soil to 1 m, as well as SOC and N in particulate organic matter (POM) and mineral-associated organic matter (MAOM) in surface soils (0–10 cm) among the different rotations. We also estimated the long-term effects of the rotations on SOC fractions through a simulation of each rotation with the MEMS 1.0 model, verified with measured data. We found that intensifying the rotation with continuous grains led to 1.5-fold increase in aggregate size but did not change SOC stocks. Incorporating a legume to the continuous grain rotation resulted in 1 Mg C ha-1 more SOC on average in surface soil compared to wheat-fallow rotations. No significant soil changes among rotations were observed at depth. Longer-term simulations of these cropping systems suggest that including legumes could allow for 10% greater SOC gains over time compared to wheat-fallow. Since legume incorporation also increased crop yields across the full rotation cycle, our results support our hypothesis that growers can solve the 'soil C dilemma' by simultaneously increasing the quantity and N-content of soil input through continuous cropping with both grains and legumes. [Display omitted] • Crops included in rotation impact the form and amount of soil carbon gained. • Continuous cropping enhanced aggregate size compared to wheat-fallow. • Including legumes in continuous cropping increases capacity to gain soil carbon. • Integrating quantification with modeling improves inference on soil carbon. [ABSTRACT FROM AUTHOR]

Soil carbon stabilization is known to depend in part on its distribution in structural aggregates, and upon soil microbial activity within the aggregates. However, the influence of climate change on continued soil C storage within aggregates of different size classes is unknown. In this study, we applied a modified dry-sieving technique to separate bulk soil into three fractions (>1 mm large macroaggregate; 0.25-1 mm small macroaggregate; <0.25 mm microaggregate), and measured the activities of seven microbial enzymes involved in the cycling of C, N, and P, in the context of a long-term elevated CO2 and warming experiment. Significant effects of aggregate size were found for most enzyme activities, enzyme stoichiometry, and specific enzyme activities (per unit of microbial biomass), suggesting that aggregate size distribution mediates microbial feedbacks to climate change. C decomposition enzyme activities, the ratios of total C:N and C:P enzyme activity, and the specific enzyme activity for C decomposition were significantly higher in the microaggregates across climate treatments. However, specific enzyme activity for N decomposition was significantly higher in macroaggregates. Increased specific enzyme activity for C decomposition under both elevated CO2 and warming suggests that these climate changes can enhance microbial ability to decompose soil organic matter (SOM). Moreover, changes in the enzyme C:N:P stoichiometry suggest that soil microorganisms may be able to adjust nutrient acquisition ratios in response to climate change. Our study suggests that identifying and modeling aggregate size as a function of SOM decomposition could improve our mechanistic understanding of soil biogeochemical cycling responses to climate change. [ABSTRACT FROM AUTHOR]

Abstract: This review focuses on some important and challenging aspects of soil extracellular enzyme research. We report on recent discoveries, identify key research needs and highlight the many opportunities offered by interactions with other microbial enzymologists. The biggest challenges are to understand how the chemical, physical and biological properties of soil affect enzyme production, diffusion, substrate turnover and the proportion of the product that is made available to the producer cells. Thus, the factors that regulate the synthesis and secretion of extracellular enzymes and their distribution after they are externalized are important topics, not only for soil enzymologists, but also in the broader context of microbial ecology. In addition, there are many uncertainties about the ways in which microbes and their extracellular enzymes overcome the generally destructive, inhibitory and competitive properties of the soil matrix, and the various strategies they adopt for effective substrate detection and utilization. The complexity of extracellular enzyme activities in depolymerising macromolecular organics is exemplified by lignocellulose degradation and how the many enzymes involved respond to structural diversity and changing nutrient availabilities. The impacts of climate change on microbes and their extracellular enzymes, although of profound importance, are not well understood but we suggest how they may be predicted, assessed and managed. We describe recent advances that allow for the manipulation of extracellular enzyme activities to facilitate bioremediation, carbon sequestration and plant growth promotion. We also contribute to the ongoing debate as to how to assay enzyme activities in soil and what the measurements tell us, in the context of both traditional methods and the newer techniques that are being developed and adopted. Finally, we offer our collective vision of the future of extracellular enzyme research: one that will depend on imaginative thinking as well as technological advances, and be built upon synergies between diverse disciplines. [Copyright &y& Elsevier]

Abstract: Several leaf litter decay studies have indicated that decomposition occurs more rapidly when litter is placed beneath the plant species from which it had been derived than beneath a different plant species (i.e. home-field advantage, HFA), although support for this notion has not been universal. We provide the first quantification of HFA in relation to leaf litter decomposition using published litter mass loss data from forest ecosystems in North America, South America, and Europe. Our findings indicate that HFA is widespread in forest ecosystems; on average litter mass loss was 8% faster at home than away. We hypothesize that HFA results from specialization of the soil biotic community in decomposing litter derived from the plant above it. Climate and initial litter quality data can be used to explain about 70% of the variability in litter decomposition at a global scale, leaving about 30% unexplained. We suggest that HFA be recognized as a factor that explains some of this remaining variability. [Copyright &y& Elsevier]

Plant roots add carbon (C) -rich rhizodeposits to the soil, which can alter microbial activity and nitrogen (N) cycling with implications for N availability and uptake by plants. We evaluated root architecture, rhizodeposit C, and microbial community structure and function across a breeding gradient of twelve winter wheat genotypes and examined how these rhizosphere traits were related to the availability and uptake of N from fresh cover crop residues in the soil. We traced wheat-derived C into soil and microbial pools using continuous isotopic labelling (13C–CO 2) and applied 15N labelled plant residues to quantify plant and microbial uptake of residue-derived N. Wheat genotypes differed in root C allocation patterns, influencing N cycling. Thicker roots released more C into soil, which enhanced N mineralization through stimulation of the microbial biomass. Microbial biomass increased N-cycling enzyme activity and residue N-uptake by wheat. Microbial communities did not differ between wheat genotypes but were strongly related to patterns in root C allocation, and several genera showed strong relationships with root C deposition and N uptake. The microbial community associated with extractable root-derived C was structurally different from the community associated with residue N uptake, indicating that N-cycling and mineralization was not necessarily carried out by the same microbial community members as those stimulated by rhizosphere C inputs. Our results indicate that differential patterns of rhizodeposition and associated belowground C allocation strategies in winter wheat can alter microbial communities and influence cycling and plant availability of residue N. Ecologically-based nutrient management in agricultural systems should consider the role of crop root traits and associated microbiomes to optimize soil nutrient dynamics. • Wheat with short, coarse roots had the highest C rhizodeposition and enzyme activity. • Soil N-cycling enzyme activity was stimulated by the release of wheat-derived C. • Microbial biomass C was related to increased cover crop N uptake and N cycling activity. • Rhizosphere microbial communities and taxa were associated with specific C and N pools, but not wheat genotype. [ABSTRACT FROM AUTHOR]

• Identifying common responses of microbial functional genes to elevated CO 2 (eCO 2) • Nitrogen (N) fixation, carbon fixation and decomposition genes increased under eCO 2. • Plant biomass, soil carbon (C) decomposition and soil moisture increased under eCO 2. • Potential molecular biomarkers of global change for predicting ecosystem functions. • Increasing soil C, soil N and net primary productivity in future eCO 2 environments. Atmospheric CO 2 concentration is increasing, largely due to anthropogenic activities. Previous studies of individual free-air CO 2 enrichment (FACE) experimental sites have shown significant impacts of elevated CO 2 (eCO 2) on soil microbial communities; however, no common microbial response patterns have yet emerged, challenging our ability to predict ecosystem functioning and sustainability in the future eCO 2 environment. Here we analyzed 66 soil microbial communities from five FACE sites, and showed common microbial response patterns to eCO 2 , especially for key functional genes involved in carbon and nitrogen fixation (e.g., pcc/acc for carbon fixation, nifH for nitrogen fixation), carbon decomposition (e.g., amyA and pulA for labile carbon decomposition, mnp and lcc for recalcitrant carbon decomposition), and greenhouse gas emissions (e.g., mcrA for methane production, norB for nitrous oxide production) across five FACE sites. Also, the relative abundance of those key genes was generally increased and directionally associated with increased biomass, soil carbon decomposition, and soil moisture. In addition, a further literature survey of more disparate FACE experimental sites indicated increased biomass, soil carbon decay, nitrogen fixation, methane and nitrous oxide emissions, plant and soil carbon and nitrogen under eCO 2. A conceptual framework was developed to link commonly responsive functional genes with ecosystem processes, such as pcc/acc vs. soil carbon storage , amyA/pulA/mnp/lcc vs. soil carbon decomposition, and nifH vs. nitrogen availability, suggesting that such common responses of microbial functional genes may have the potential to predict ecosystem functioning and sustainability in the future eCO 2 environment. [ABSTRACT FROM AUTHOR]

Rapid climate change in the Arctic is altering microbial structure and function, with important consequences for the global ecosystem. Emerging evidence suggests organisms in higher trophic levels may also influence microbial communities, but whether warming alters these effects is unclear. Wolf spiders are dominant Arctic predators whose densities are expected to increase with warming. These predators have temperature-dependent effects on decomposition via their consumption of fungal-feeding detritivores, suggesting they may indirectly affect the microbial structure as well. To address this, we used a fully factorial mesocosm experiment to test the effects of wolf spider density and warming on litter microbial structure in Arctic tundra. We deployed replicate litter bags at the surface and belowground in the organic soil profile and analyzed the litter for bacterial and fungal community structure, mass loss, and nutrient characteristics after 2 and 14 months. We found there were significant interactive effects of wolf spider density and warming on fungal but not bacterial communities. Specifically, higher wolf spider densities caused greater fungal diversity under ambient temperature but lower fungal diversity under warming at the soil surface. We also observed interactive treatment effects on fungal composition belowground. Wolf spider density influenced surface bacterial composition, but the effects did not change with warming. These findings suggest a widespread predator can have indirect, cascading effects on litter microbes and that effects on fungi specifically shift under future expected levels of warming. Overall, our study highlights that trophic interactions may play important, albeit overlooked, roles in driving microbial responses to warming in Arctic terrestrial ecosystems., Importance: The Arctic contains nearly half of the global pool of soil organic carbon and is one of the fastest warming regions on the planet. Accelerated decomposition of soil organic carbon due to warming could cause positive feedbacks to climate change through increased greenhouse gas emissions; thus, changes in ecological dynamics in this region are of global relevance. Microbial structure is an important driver of decomposition and is affected by both abiotic and biotic conditions. Yet how activities of soil-dwelling organisms in higher trophic levels influence microbial structure and function is unclear. In this study, we demonstrate that predicted changes in abundances of a dominant predator and warming interactively affect the structure of litter-dwelling fungal communities in the Arctic. These findings suggest predators may have widespread, indirect cascading effects on microbial communities, which could influence ecosystem responses to future climate change., Competing Interests: The authors declare no conflict of interest.

Background: Neonatal transpyloric feeding (TPF) has not been rigorously studied since the 1980s. Our objective was to evaluate early TPF, defined as TPF initiated within the first week after birth, among preterm infants in the setting of modern neonatal practice., Study Design: A retrospective cohort study was conducted between 2013 and 2017 for all extremely low birth weight (ELBW) infants born in a tertiary neonatal intensive care unit where early TPF is a common practice. Infants were excluded if they did not receive enteral feeding within the first week after birth or if they died prior to initiation of enteral feeding. The primary outcome was death or bronchopulmonary dysplasia (BPD). The association between early TPF and the primary outcome was assessed using multivariable logistic regression, with adjustment for gestational age, birth weight, and intubation status., Result: The study sample included 368 ELBW infants. Twenty-seven percent received early TPF. Death or BPD occurred in 58% of infants who received early TPF compared with 67% of infants who received gastric feeding, adjusted odds ratio 0.6, 95% confidence interval 0.3-0.9. Growth and adverse gastrointestinal outcomes did not differ between the two groups., Conclusion: Early TPF is associated with reduced risk of death or BPD among ELBW infants. Further investigation in the form of a randomized controlled trial is required to confirm a causal association between early TPF and improved clinical outcomes.

Translating the ever-increasing wealth of information on microbiomes (environment, host or built environment) to advance our understanding of system-level processes is proving to be an exceptional research challenge. One reason for this challenge is that relationships between characteristics of microbiomes and the system-level processes that they influence are often evaluated in the absence of a robust conceptual framework and reported without elucidating the underlying causal mechanisms. The reliance on correlative approaches limits the potential to expand the inference of a single relationship to additional systems and advance the field. We propose that research focused on how microbiomes influence the systems they inhabit should work within a common framework and target known microbial processes that contribute to the system-level processes of interest. Here, we identify three distinct categories of microbiome characteristics (microbial processes, microbial community properties and microbial membership) and propose a framework to empirically link each of these categories to each other and the broader system-level processes that they affect. We posit that it is particularly important to distinguish microbial community properties that can be predicted using constituent taxa (community-aggregated traits) from those properties that cannot currently be predicted using constituent taxa (emergent properties). Existing methods in microbial ecology can be applied to more explicitly elucidate properties within each of these three categories of microbial characteristics and connect them with each other. We view this proposed framework, gleaned from a breadth of research on environmental microbiomes and ecosystem processes, as a promising pathway with the potential to advance discovery and understanding across a broad range of microbiome science.

Soil organic matter is critical to sustainable agriculture because it provides nutrients to crops as it decomposes and increases nutrient- and water-holding capacity when built up. Fast- and slow-cycling fractions of soil organic matter can have different impacts on crop production because fast-cycling fractions rapidly release nutrients for short-term plant growth and slow-cycling fractions bind nutrients that mineralize slowly and build up water-holding capacity. We explored the controls on these fractions in a tropical agroecosystem and their relationship to crop yields. We performed physical fractionation of soil organic matter from 48 farms and plots in western Kenya. We found that fast-cycling, particulate organic matter was positively related to crop yields, but did not have a strong effect, while slower-cycling, mineral-associated organic matter was negatively related to yields. Our finding that slower-cycling organic matter was negatively related to yield points to a need to revise the view that stabilization of organic matter positively impacts food security. Our results support a new paradigm that different soil organic matter fractions are controlled by different mechanisms, potentially leading to different relationships with management outcomes, like crop yield. Effectively managing soils for sustainable agriculture requires quantifying the effects of specific organic matter fractions on these outcomes., (© 2016 by the Ecological Society of America.)

Phosphorus (P) is a critical nutrient used to maximize plant growth and yield. Current agriculture management practices commonly experience low plant P use efficiency due to natural chemical sorption and transformations when P fertilizer is applied to soils. A perplexing challenge facing agriculture production is finding sustainable solutions to deliver P more efficiently to plants. Using prescribed applications of specific soil microbial assemblages to mobilize soil bound-P to improve crop nutrient uptake and productivity has rarely been employed. We investigated whether inoculation of soils with a bacterial consortium developed to mobilize soil P, named Mammoth P(TM), could increase plant productivity. In turf, herbs, and fruits, the combination of conventional inorganic fertilizer combined with Mammoth P(TM) increased productivity up to twofold compared to the fertilizer treatments without the Mammoth P(TM) inoculant. Jalapeño plants were found to bloom more rapidly when treated with either Mammoth P. In wheat trials, we found that Mammoth P(TM) by itself was able to deliver yields equivalent to those achieved with conventional inorganic fertilizer applications and improved productivity more than another biostimulant product. Results from this study indicate the substantial potential of Mammoth P(TM) to enhance plant growth and crop productivity.

Germline mutations in RASA1 are associated with capillary malformation-arteriovenous malformation (CM-AVM) syndrome. CM-AVM syndrome is characterized by multi-focal capillary malformations and arteriovenous malformations. Lymphatic anomalies have been proposed as part of the phenotype. Intrafamilial variability has been reported, suggesting modifiers and somatic events. The objective of the study was to identify somatic RASA1 "second hits" from vascular malformations associated with CM-AVM syndrome, and describe phenotypic variability. Participants were examined and phenotyped. Genomic DNA was extracted from peripheral blood on all participants. Whole-exome sequencing was performed on the proband. Using Sanger sequencing, RASA1 exon 8 was PCR-amplified to track the c.1248T>G, p.Tyr416X germline variant through the family. A skin biopsy of a capillary malformation from the proband's mother was also obtained, and next-generation sequencing was performed on DNA from the affected tissue. A familial germline heterozygous novel pathogenic RASA1 variant, c.1248T>G (p.Tyr416X), was identified in the proband and her mother. The proband had capillary malformations, chylothorax, lymphedema, and overgrowth, while her affected mother had only isolated capillary malformations. Sequence analysis of DNA extracted from a skin biopsy of a capillary malformation of the affected mother showed a second RASA1 somatic mutation (c.2245C>T, p.Arg749X). These results and the extreme variable expressivity support the hypothesis that somatic "second hits" are required for the development of vascular anomalies associated with CM-AVM syndrome. In addition, the phenotypes of the affected individuals further clarify that lymphatic manifestations are also part of the phenotypic spectrum of RASA1-related disorders. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

Climate change over the past ∼50 years has resulted in earlier occurrence of plant life-cycle events for many species. Across temperate, boreal and polar latitudes, earlier seasonal warming is considered the key mechanism leading to earlier leaf expansion and growth. Yet, in seasonally snow-covered ecosystems, the timing of spring plant growth may also be cued by snowmelt, which may occur earlier in a warmer climate. Multiple environmental cues protect plants from growing too early, but to understand how climate change will alter the timing and magnitude of plant growth, experiments need to independently manipulate temperature and snowmelt. Here, we demonstrate that altered seasonality through experimental warming and earlier snowmelt led to earlier plant growth, but the aboveground production response varied among plant functional groups. Earlier snowmelt without warming led to early leaf emergence, but often slowed the rate of leaf expansion and had limited effects on aboveground production. Experimental warming alone had small and inconsistent effects on aboveground phenology, while the effect of the combined treatment resembled that of early snowmelt alone. Experimental warming led to greater aboveground production among the graminoids, limited changes among deciduous shrubs and decreased production in one of the dominant evergreen shrubs. As a result, we predict that early onset of the growing season may favour early growing plant species, even those that do not shift the timing of leaf expansion., (Published by Oxford University Press on behalf of the Annals of Botany Company.)

Moderate preterm infants remain at increased risk for adverse outcomes, including acute bilirubin encephalopathy (ABE). Evidence-based guidelines for management of hyperbilirubinemia in preterm infants less than 35 weeks' gestational age are not yet optimized. High concentrations of unconjugated bilirubin can cause permanent posticteric neurologic sequelae (kernicterus). Clinical manifestations of ABE in preterm infants are similar to, but often more subtle than, those of term infants. This review outlines clinical strategies to operationalize management of hyperbilirubinemia in moderately preterm infants to meet recently published consensus-based recommendations., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Soils are immensely diverse microbial habitats with thousands of co-existing bacterial, archaeal, and fungal species. Across broad spatial scales, factors such as pH and soil moisture appear to determine the diversity and structure of soil bacterial communities. Within any one site however, bacterial taxon diversity is high and factors maintaining this diversity are poorly resolved. Candidate factors include organic substrate availability and chemical recalcitrance, and given that they appear to structure bacterial communities at the phylum level, we examine whether these factors might structure bacterial communities at finer levels of taxonomic resolution. Analyzing 16S rRNA gene composition of nucleotide analog-labeled DNA by PhyloChip microarrays, we compare relative growth rates on organic substrates of increasing chemical recalcitrance of >2,200 bacterial taxa across 43 divisions/phyla. Taxa that increase in relative abundance with labile organic substrates (i.e., glycine, sucrose) are numerous (>500), phylogenetically clustered, and occur predominantly in two phyla (Proteobacteria and Actinobacteria) including orders Actinomycetales, Enterobacteriales, Burkholderiales, Rhodocyclales, Alteromonadales, and Pseudomonadales. Taxa increasing in relative abundance with more chemically recalcitrant substrates (i.e., cellulose, lignin, or tannin-protein) are fewer (168) but more phylogenetically dispersed, occurring across eight phyla and including Clostridiales, Sphingomonadalaes, Desulfovibrionales. Just over 6% of detected taxa, including many Burkholderiales increase in relative abundance with both labile and chemically recalcitrant substrates. Estimates of median rRNA copy number per genome of responding taxa demonstrate that these patterns are broadly consistent with bacterial growth strategies. Taken together, these data suggest that changes in availability of intrinsically labile substrates may result in predictable shifts in soil bacterial composition.