Accuracy and Precision of Tidal Wetland Soil Carbon Mapping in the Conterminous United States

Tidal wetlands produce long-term soil organic carbon (C) stocks. Thus for carbon accounting purposes, we need accurate and precise information on the magnitude and spatial distribution of those stocks. We assembled and analyzed an unprecedented soil core dataset, and tested three strategies for mapping carbon stocks: applying the average value from the synthesis to mapped tidal wetlands, applying models fit using empirical data and applied using soil, vegetation and salinity maps, and relying on independently generated soil carbon maps. Soil carbon stocks were far lower on average and varied less spatially and with depth than stocks calculated from available soils maps. Further, variation in carbon density was not well-predicted based on climate, salinity, vegetation, or soil classes. Instead, the assembled dataset showed that carbon density across the conterminous united states (CONUS) was normally distributed, with a predictable range of observations. We identified the simplest strategy, applying mean carbon density (27.0 kg C m−3), as the best performing strategy, and conservatively estimated that the top meter of CONUS tidal wetland soil contains 0.72 petagrams C. This strategy could provide standardization in CONUS tidal carbon accounting until such a time as modeling and mapping advancements can quantitatively improve accuracy and precision

The Effect of Fertilization on Biomass and Metabolism in North Carolina Salt Marshes: Modulated by Location-Specific Factors

The resilience of salt marshes to sea level rise depends on vertical accretion through belowground biomass production and sediment deposition to maintain elevation above sea level. Increased nitrogen (N) availability from anthropogenic sources may stimulate aboveground biomass production and sediment deposition and, thus, accretion; however, increased N may also negatively impact marsh accretion by decreasing belowground biomass and increasing net CO2 emissions. A study was conducted in Spartina alterniflora‐dominated salt marshes in North Carolina, USA, to determine how responses to fertilization vary across locations with different physical and chemical characteristics. Pore water residence time, inundation time, and proximity to tidal creeks drove spatial differences in pore water sulfide, ammonium, and dissolved carbon concentrations. Although annual respiration and gross primary production were greater at the creek edge than interior marsh sites, net ecosystem CO2 exchange (NEE) was nearly balanced at all the sites. Fertilization decreased belowground biomass in the interior sites but not on the creek edge. Aboveground biomass, respiration, gross primary production, and net CO2 emissions increased in response to fertilization, but responses were diminished in interior marsh locations with high pore water sulfide. Hourly NEE measured by chambers were similar to hourly NEE observed by a nearby eddy covariance tower, but correcting for inundation depth relative to plant height was critical for accurate extrapolation to annual fluxes. The impact of fertilization on biomass and NEE, and thus marsh resilience, varied across marsh locations depending upon location‐specific pore water sulfide concentrations

Apospory and Diplospory in Diploid Boechera (Brassicaceae) May Facilitate Speciation by Recombination-Driven Apomixis-to-Sex Reversals

Apomixis (asexual seed formation) in angiosperms occurs either sporophytically, through adventitious embryony, or gametophytically, where an unreduced female gametophyte (embryo sac) forms and produces an unreduced egg that develops into an embryo parthenogenetically. Multiple types of gametophytic apomixis occur, and these are differentiated based on where and when the unreduced gametophyte forms, a process referred to as apomeiosis. Apomeiotic gametophytes form directly from ameiotic megasporocytes, as in Antennaria-type diplospory, from unreduced spores derived from 1st division meiotic restitutions, as in Taraxacum-type diplospory, or from cells of the ovule wall, as in Hieracium-type apospory. Multiple types of apomeiosis occasionally occur in the same plant, which suggests that the different types occur in response to temporal and/or spatial shifts in termination of sexual processes and onset timing of apomeiosis processes. To better understand the origins and evolutionary implications of apomixis in Boechera (Brassicaceae), we determined apomeiosis type for 64 accessions representing 44 taxonomic units. Plants expressing apospory and diplospory were equally common, and these generally produced reduced and unreduced pollen, respectively. Apospory and diplospory occurred simultaneously in individual plants of seven taxa. In Boechera, apomixis perpetuates otherwise sterile or semisterile interspecific hybrids (allodiploids) through multiple generations. Accordingly, ample time, in these multigenerational clones, is available for rare meioses to produce haploid, intergenomically recombined male and female gametes. The fusion of such gametes could then produce segmentally autoploidized progeny. If sex re-emerges among such progeny, then new and genomically unique sexual species could evolve. Herein, we present evidence that such apomixis-facilitated speciation is occurring in Boechera, and we hypothesize that it might also be occurring in facultatively apomictic allodiploids of other angiospermous taxa

High body burdens of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) in California women.

Following our first report on elevated polybrominated diphenyl ether (PBDE) concentrations in California women, we expanded our investigation to include diverse groups of local women. We analyzed additional adipose and serum samples collected in the late 1990s from San Francisco Bay Area women participating in a breast cancer study and in a reproductive study, respectively. Adipose samples (n = 32) were analyzed by low-resolution mass spectrometry in negative-ion chemical ionization mode, whereas serum samples (n = 50) were analyzed by dual-column gas chromatography with electron capture detection. The results confirmed our earlier findings. Concentrations of 2,2,4,4 -tetrabromodiphenyl ether (BDE-47) in contemporary California women ranged between 5 and 510 ng/g lipid, with a median (16.5 ng/g lipid) 3-10 times higher than those reported from Europe. In contrast, PBDEs were not measurable in any of 420 archived serum samples collected in the 1960s from San Francisco Bay Area women participating in a study of child development. BDE-47 concentrations did not increase with age or with concentrations of a polychlorinated biphenyl (PCB-153), suggesting other routes of exposure in addition to diet. Rising body burdens of endocrine-disrupting chemicals such as PBDEs may pose a potential public health threat

Covert Neurological Symptoms Associated With Silent Infarcts From Midlife to Older Age: The Atherosclerosis Risk in Communities Study

Unrecognized or unreported stroke-like symptoms, called covert symptoms, occur in persons free of clinical stroke. Whether covert symptoms are associated with subclinical brain infarcts (SBI) is unknown. This study examined the association between covert stroke-like symptoms and SBI/stroke in persons with no history of stroke or TIA

Identification of Maize Genes Associated with Host Plant Resistance or Susceptibility to Aspergillus flavus Infection and Aflatoxin Accumulation

infection and aflatoxin accumulation. inoculation were compared in two resistant maize inbred lines (Mp313E and Mp04∶86) in contrast to two susceptible maize inbred lines (Va35 and B73) by microarray analysis. Principal component analysis (PCA) was used to find genes contributing to the larger variances associated with the resistant or susceptible maize inbred lines. The significance levels of gene expression were determined by using SAS and LIMMA programs. Fifty candidate genes were selected and further investigated by quantitative RT-PCR (qRT-PCR) in a time-course study on Mp313E and Va35. Sixteen of the candidate genes were found to be highly expressed in Mp313E and fifteen in Va35. Out of the 31 highly expressed genes, eight were mapped to seven previously identified quantitative trait locus (QTL) regions. A gene encoding glycine-rich RNA binding protein 2 was found to be associated with the host hypersensitivity and susceptibility in Va35. A nuclear pore complex protein YUP85-like gene was found to be involved in the host resistance in Mp313E. infection and aflatoxin accumulation. These findings will be important in identification of DNA markers for breeding maize lines resistant to aflatoxin accumulation

Uncertainty in United States coastal wetland greenhouse gas inventorying

© The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Environmental Research Letters 13 (2018): 115005, doi:10.1088/1748-9326/aae157.Coastal wetlands store carbon dioxide (CO2) and emit CO2 and methane (CH4) making them an important part of greenhouse gas (GHG) inventorying. In the contiguous United States (CONUS), a coastal wetland inventory was recently calculated by combining maps of wetland type and change with soil, biomass, and CH4 flux data from a literature review. We assess uncertainty in this developing carbon monitoring system to quantify confidence in the inventory process itself and to prioritize future research. We provide a value-added analysis by defining types and scales of uncertainty for assumptions, burial and emissions datasets, and wetland maps, simulating 10 000 iterations of a simplified version of the inventory, and performing a sensitivity analysis. Coastal wetlands were likely a source of net-CO2-equivalent (CO2e) emissions from 2006–2011. Although stable estuarine wetlands were likely a CO2e sink, this effect was counteracted by catastrophic soil losses in the Gulf Coast, and CH4 emissions from tidal freshwater wetlands. The direction and magnitude of total CONUS CO2e flux were most sensitive to uncertainty in emissions and burial data, and assumptions about how to calculate the inventory. Critical data uncertainties included CH4 emissions for stable freshwater wetlands and carbon burial rates for all coastal wetlands. Critical assumptions included the average depth of soil affected by erosion events, the method used to convert CH4 fluxes to CO2e, and the fraction of carbon lost to the atmosphere following an erosion event. The inventory was relatively insensitive to mapping uncertainties. Future versions could be improved by collecting additional data, especially the depth affected by loss events, and by better mapping salinity and inundation gradients relevant to key GHG fluxes. Social Media Abstract: US coastal wetlands were a recent and uncertain source of greenhouse gasses because of CH4 and erosion.Financial support was provided primarily by NASA Carbon Monitoring Systems (NNH14AY67I) and the USGS Land Carbon Program, with additional support from The Smithsonian Institution, The Coastal Carbon Research Coordination Network (DEB-1655622), and NOAA Grant: NA16NMF4630103

Hospital trajectories and early predictors of clinical outcomes differ between SARS-CoV-2 and influenza pneumonia

BACKGROUND: A comparison of pneumonias due to SARS-CoV-2 and influenza, in terms of clinical course and predictors of outcomes, might inform prognosis and resource management. We aimed to compare clinical course and outcome predictors in SARS-CoV-2 and influenza pneumonia using multi-state modelling and supervised machine learning on clinical data among hospitalised patients. METHODS: This multicenter retrospective cohort study of patients hospitalised with SARS-CoV-2 (March-December 2020) or influenza (Jan 2015-March 2020) pneumonia had the composite of hospital mortality and hospice discharge as the primary outcome. Multi-state models compared differences in oxygenation/ventilatory utilisation between pneumonias longitudinally throughout hospitalisation. Differences in predictors of outcome were modelled using supervised machine learning classifiers. FINDINGS: Among 2,529 hospitalisations with SARS-CoV-2 and 2,256 with influenza pneumonia, the primary outcome occurred in 21% and 9%, respectively. Multi-state models differentiated oxygen requirement progression between viruses, with SARS-CoV-2 manifesting rapidly-escalating early hypoxemia. Highly contributory classifier variables for the primary outcome differed substantially between viruses. INTERPRETATION: SARS-CoV-2 and influenza pneumonia differ in presentation, hospital course, and outcome predictors. These pathogen-specific differential responses in viral pneumonias suggest distinct management approaches should be investigated. FUNDING: This project was supported by NIH/NCATS UL1 TR002345, NIH/NCATS KL2 TR002346 (PGL), the Doris Duke Charitable Foundation grant 2015215 (PGL), NIH/NHLBI R35 HL140026 (CSC), and a Big Ideas Award from the BJC HealthCare and Washington University School of Medicine Healthcare Innovation Lab and NIH/NIGMS R35 GM142992 (PS)

Metformin Blunts Muscle Hypertrophy in Response to Progressive Resistance Exercise Training in Older Adults: A Randomized, Double‐Blind, Placebo‐Controlled, Multicenter Trial: The MASTERS Trial

Progressive resistance exercise training (PRT) is the most effective known intervention for combating aging skeletal muscle atrophy. However, the hypertrophic response to PRT is variable, and this may be due to muscle inflammation susceptibility. Metformin reduces inflammation, so we hypothesized that metformin would augment the muscle response to PRT in healthy women and men aged 65 and older. In a randomized, double-blind trial, participants received 1,700 mg/day metformin (N = 46) or placebo (N = 48) throughout the study, and all subjects performed 14 weeks of supervised PRT. Although responses to PRT varied, placebo gained more lean body mass (p = .003) and thigh muscle mass (p \u3c .001) than metformin. CT scan showed that increases in thigh muscle area (p = .005) and density (p = .020) were greater in placebo versus metformin. There was a trend for blunted strength gains in metformin that did not reach statistical significance. Analyses of vastus lateralis muscle biopsies showed that metformin did not affect fiber hypertrophy, or increases in satellite cell or macrophage abundance with PRT. However, placebo had decreased type I fiber percentage while metformin did not (p = .007). Metformin led to an increase in AMPK signaling, and a trend for blunted increases in mTORC1 signaling in response to PRT. These results underscore the benefits of PRT in older adults, but metformin negatively impacts the hypertrophic response to resistance training in healthy older individuals. ClinicalTrials.gov Identifier: NCT02308228

Reducing the Population Burden of Coronary Heart Disease by Modifying Adiposity: Estimates From the ARIC Study

Background: Excess adiposity, which affects 69% of US adults, increases coronary heart disease (CHD) risk in an association that manifests below conventional obesity cut points. The population-level impact on CHD risk that is attainable through modest adiposity reductions in populations is not well characterized. We estimated the effect of hypothetical reductions in both body mass index (BMI) and waist circumference (WC) on CHD incidence. Methods and Results: The study population included 13 610 ARIC (Atherosclerosis Risk in Communities) participants. Our hypothetical reduction in BMI or WC was applied relative to the temporal trend, with no hypothetical reduction among those with BMI >24 or WC >88 cm, respectively. This threshold for hypothetical reduction is near the clinical guidelines for excess adiposity. CHD risk differences compared the hypothetical reduction with no reduction. Sensitivity analysis was conducted to estimate the effect of applying the hypothetical BMI reduction at the established overweight cut point of 25. Cumulative 12-year CHD incidence with no intervention was 6.3% (95% CI, 5.9–6.8%). Risk differences following the hypothetical BMI and WC reductions were −0.6% (95% CI, −1.0% to −0.1%) and −1.0% (95% CI, −1.4% to −0.5%), respectively. These results were robust for the sensitivity analyses. Consequently, we estimated that this hypothetical reduction of 5% in BMI and WC, respectively, could have prevented 9% and 16%, respectively, of the CHD events occurring in this study population over 12 years, after adjustment for established CHD risk factors. Conclusions: Meaningful CHD risk reductions could derive from modest reductions in adiposity attainable through lifestyle modification