Soil microbial communities control critical ecosystem processes such as decomposition, nutrient cycling, and soil organic matter formation. Continental scale patterns in the composition and ...functioning of microbial communities are related to climatic, biotic, and edaphic factors such as temperature and precipitation, plant community composition, and soil carbon, nitrogen, and pH. Although these relationships have been well explored individually, the examination of the factors that may act directly on microbial communities vs. those that may act indirectly through other ecosystem properties has not been well developed. To further such understanding, we utilized structural equation modeling (SEM) to evaluate a set of hypotheses about the direct and indirect effects of climatic, biotic, and edaphic variables on microbial communities across the continental United States. The primary goals of this work were to test our current understanding of the interactions among climate, soils, and plants in affecting microbial community composition, and to examine whether variation in the composition of the microbial community affects potential rates of soil enzymatic activities. A model of interacting factors created through SEM shows several expected patterns. Distal factors such as climate had indirect effects on microbial communities by influencing plant productivity, soil mineralogy, and soil pH, but factors related to soil organic matter chemistry had the most direct influence on community composition. We observed that both plant productivity and soil mineral composition were important indirect influences on community composition at the continental scale, both interacting to affect organic matter content and microbial biomass and ultimately community composition. Although soil hydrolytic enzymes were related to the moisture regime and soil carbon, oxidative enzymes were also affected by community composition, reflected in the abundance of soil fungi. These results highlight that soil microbial communities can be modeled within the context of multiple interacting ecosystem properties acting both directly and indirectly on their composition and function, and this provides a rich and informative context with which to examine communities. This work also highlights that variation in climate, microbial biomass, and microbial community composition can affect maximum rates of soil enzyme activities, potentially influencing rates of decomposition and nutrient mineralization in soils.
Pennsylvanian coals in the Appalachian Basin host pyrite that is locally enriched in potentially toxic trace elements such as As, Se, Hg, Pb, and Ni. A comparison of pyrite-rich coals from ...northwestern Alabama, eastern Kentucky, and West Virginia reveals differences in concentrations and mode of occurrence of trace elements in pyrite. Pyrite occurs as framboids, dendrites, or in massive crystalline form in cell lumens or crosscutting veins. Metal concentrations in pyrite vary over all scales, from microscopic to mine to regional, because trace elements are inhomogeneously distributed in the different morphological forms of pyrite, and in the multiple generations of sulfide mineral precipitates.
Early diagenetic framboidal pyrite is usually depleted in As, Se, and Hg, and enriched in Pb and Ni, compared to other pyrite forms. In dendritic pyrite, maps of As distribution show a chemical gradient from As-rich centers to As-poor distal branches, whereas Se concentrations are highest at the distal edges of the branches. Massive crystalline pyrite that fills veins is composed of several generations of sulfide minerals. Pyrite in late-stage veins commonly exhibits As-rich growth zones, indicating a probable epigenetic hydrothermal origin. Selenium is concentrated at the distal edges of veins. A positive correlation of As and Se in pyrite veins from Kentucky coals, and of As and Hg in pyrite-filled veins from Alabama coals, suggests coprecipitation of these elements from the same fluid.
In the Kentucky coal samples (n=18), As and Se contents in pyrite-filled veins average 4200ppm and 200ppm, respectively. In Alabama coal samples, As in pyrite-filled veins averages 2700ppm (n=34), whereas As in pyrite-filled cellular structures averages 6470ppm (n=35). In these same Alabama samples, Se averages 80ppm in pyrite-filled veins, but was below the detection limit in cell structures. In samples of West Virginia massive pyrite, As averages 1700ppm, and Se averages 270ppm (n=24). The highest concentration of Hg (≤102ppm) is in Alabama pyrite veins.
Improved detailed descriptions of sulfide morphology, sulfide mineral paragenesis, and trace-element concentration and distribution allow more informed predictions of: (1) the relative rate of release of trace elements during weathering of pyrite in coals, and (2) the relative effectiveness of various coal-cleaning procedures of removing pyrite. For example, trace element-rich pyrite has been shown to be more soluble than stoichiometric pyrite, and fragile fine-grained pyrite forms such as dendrites and framboids are more susceptible to dissolution and disaggregation but less amenable to removal during coal cleaning.
► Our work links chemical and microstructural data to decipher the nature and origin of coal-related sulfide minerals in Appalachian basin coals. ► Appalachian coals host trace metal-rich pyrite, which is more susceptible to weathering and dissolution processes than stoichiometric pyrite. ► Pyrite occurs in many morphologies, as dendrites, cell and vein fill, framboids, and coarsely crystalline. ► Trace metals are distributed inhomogeneously in different morphologies and generations of pyrite.
Genetic deficiency of dystrophin leads to disability and premature death in Duchenne muscular dystrophy (DMD), affecting the heart as well as skeletal muscle. Here, we report that clinical-stage ...cardiac progenitor cells, known as cardiosphere-derived cells (CDCs), improve cardiac and skeletal myopathy in the mdx mouse model of DMD. Injection of CDCs into the hearts of mdx mice augments cardiac function, ambulatory capacity, and survival. Exosomes secreted by human CDCs reproduce the benefits of CDCs in mdx mice and in human induced pluripotent stem cell-derived Duchenne cardiomyocytes. Surprisingly, CDCs and their exosomes also transiently restored partial expression of full-length dystrophin in mdx mice. The findings further motivate the testing of CDCs in Duchenne patients, while identifying exosomes as next-generation therapeutic candidates.
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•CDCs improve cardiac and skeletal myopathy in the mdx mouse model of DMD•CDC exosomes reproduce the benefits of CDCs•CDCs and their exosomes transiently restored partial expression of dystrophin
In this article, Marbán and colleagues show that exosomes mediate benefits of cell therapy in mouse and human models of Duchenne muscular dystrophy.
The mineralogic residence and abundance of trace metals is an important environmental issue. Data from the USGS coal quality database show that potentially toxic elements, including Hg, As, Mo, Se, ...Cu, and Tl are enriched in a subset of coal samples in the Black Warrior Basin of Alabama, USA. Although the coal as-mined typically is low in these elements, localized enrichments occur in high-pyrite coals and near faults. Microscopic analyses demonstrate that the residence of these elements is dominantly in a late-stage pyrite associated with structurally disrupted coal. Further, our data suggest addition of Hg to the coal matrix as well. The source of these trace elements was hydrothermal fluids driven into the Black Warrior Basin by Alleghanian age tectonism.
The relationships between soil parent lithology, nutrient concentrations, microbial biomass and community structure were evaluated in soils from a small watershed impacted by historic Hg mining. ...Upland and wetland soils, stream sediments and tailings were collected and analyzed for nutrients (DOC, SO
4
=, NO
3
−), Hg, MeHg, and phospholipid fatty acids (PLFA). Stream sediment was derived from serpentinite, siltstone, volcanic rocks and mineralized serpentine with cinnabar, metacinnabar and other Hg phases. Soils from different parent materials had distinct PLFA biomass and community structures that are related to nutrient concentrations and toxicity effects of trace metals including Hg. The formation of MeHg appears to be most strongly linked to soil moisture, which in turn has a correlative relationship with PLFA biomass in wetland soils. The greatest concentrations of MeHg (>
0.5 ng g
−
1
MeHg) were measured in wetland soils and soil with a volcanic parent (9.5–37 µg g
−
1
Hg). Mercury methylation was associated with sulfate-reducing bacteria, including
Desulfobacter sp. and
Desulfovibrio sp., although these organisms are not exclusively responsible for Hg methylation. Statistical models of the data demonstrated that soil microbial communities varied more with soil type than with season.
According to diffusion theory, consumer beliefs or perceptions of innovation attributes, along with external socioeconomic and media exposures, influence the decision to adopt an innovation. To ...examine the relative influence of beliefs, attitudes, and external variables, the current study synthesizes perspectives from the Technology Adoption Model (TAM) and diffusion theory, and presents an integrated model of consumer adoption. The article reports the results of a survey investigating the measurement model in predicting potential adoption by late adopters of cellular phones. The model confirms the importance of attitudes towards potential adoption. Also significant are the influence of media ownership on perceptions of advantage, observability, and compatibility of the innovation. Media use and change agent contacts significantly influence perceptions of complexity of the innovation. Age, income and occupation were the sociodemographic variables that indirectly influenced adoption intention.
We have searched for proton decay via p→e+π0 and p→μ+π0 using Super-Kamiokande data from April 1996 to March 2015, 0.306 megaton·years exposure in total. The atmospheric neutrino background rate in ...Super-Kamiokande IV is reduced to almost half that of phase I-III by tagging neutrons associated with neutrino interactions. The reach of the proton lifetime is further enhanced by introducing new signal criteria that select the decay of a proton in a hydrogen atom. No candidates were seen in the p→e+π0 search. Two candidates that passed all of the selection criteria for p→μ+π0 have been observed, but these are consistent with the expected number of background events of 0.87. Lower limits on the proton lifetime are set at τ/B(p→e+π0)>1.6×1034 years and τ/B(p→μ+π0)>7.7×1033 years at 90% confidence level.
We have searched for proton decays into a charged antilepton (e+, μ+) plus a meson (η, ρ0, ω) and for neutron decays into a charged antilepton (e+, μ+) plus a meson (π−, ρ−) using Super-Kamiokande ...I-IV data, corresponding to 0.316 megaton·years of exposure. This measurement updates the previous published result by using 2.26 times more data and improved analysis methods. No significant evidence for nucleon decay is observed and lower limits on the partial lifetime of the nucleon are obtained. The limits range from 3×1031 to 1×1034 years at 90% confidence level, depending on the decay mode.
A search for Supernova Relic Neutrinos ν¯e’s is first conducted via inverse-beta-decay by tagging neutron capture on hydrogen at Super-Kamiokande-IV. The neutron tagging efficiency is determined to ...be (17.74±0.04stat.±1.05sys.)%, while the corresponding accidental background probability is (1.06±0.01stat.±0.18sys.)%. Using 960days of data, we obtain 13 inverse-beta-decay candidates in the range of Eν¯e between 13.3MeV and 31.3MeV. All of the observed candidates are attributed to background. Upper limits at 90% C.L. are calculated in the absence of a signal.
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