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  • 1
    Language: English
    In: Pediatrics, May 2014, Vol.133(5), pp.e1277-84
    Description: Inadequate maternal vitamin D (assessed by using 25-hydroxyvitamin D [25OHD]) levels during pregnancy may affect tooth calcification, predisposing enamel hypoplasia and early childhood caries (ECC). The purpose of this study was to determine the relationship between prenatal 25OHD concentrations and dental caries among offspring during the first year of life. This prospective cohort study recruited expectant mothers from an economically disadvantaged urban area. A prenatal questionnaire was completed and serum sample drawn for 25OHD. Dental examinations were completed at 1 year of age while the parent/caregiver completed a questionnaire. The examiner was blinded to mothers' 25OHD levels. A P value ≤ .05 was considered significant. Overall, 207 women were enrolled (mean age: 19 ± 5 years). The mean 25OHD level was 48 ± 24 nmol/L, and 33% had deficient levels. Enamel hypoplasia was identified in 22% of infants; 23% had cavitated ECC, and 36% had ECC when white spot lesions were included in the assessment. Mothers of children with ECC had significantly lower 25OHD levels than those whose children were caries-free (41 ± 20 vs 52 ± 27 nmol/L; P = .05). Univariate Poisson regression analysis for the amount of untreated decay revealed an inverse relationship with maternal 25OHD. Logistic regression revealed that enamel hypoplasia (P 〈 .001), infant age (P = .002), and lower prenatal 25OHD levels (P = .02) were significantly associated with ECC. This study found that maternal prenatal 25OHD levels may have an influence on the primary dentition and the development of ECC.
    Keywords: Early Childhood Caries ; Enamel Hypoplasia ; Infant ; Vitamin D ; Prenatal Care ; Dental Caries -- Prevention & Control ; Vitamin D -- Administration & Dosage
    ISSN: 00314005
    E-ISSN: 1098-4275
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  • 2
    Language: English
    In: Nature, Dec 18, 2008, Vol.456(7224), p.888(2)
    Keywords: Nitrous Oxide -- Environmental Aspects ; Nitrous Oxide -- Chemical Properties ; Climate Change -- Causes Of ; Climate Change -- Prevention
    ISSN: 0028-0836
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  • 3
    In: Global Change Biology, August 2015, Vol.21(8), pp.2831-2831
    Description: To purchase or authenticate to the full-text of this article, please visit this link: http://onlinelibrary.wiley.com/doi/10.1111/gcb.12836/abstract Byline: Sharon A. Billings, William H. Schlesinger Keywords: atmospheric CO.sub.2; biomass burning; CO.sub.2 capture; global carbon cycle; missing carbon sink; pyrogenic organic matter ***** No abstract is available for this article. *****
    Keywords: Atmospheric Co 2 ; Biomass Burning ; Co 2 Capture ; Global Carbon Cycle ; Missing Carbon Sink ; Pyrogenic Organic Matter
    ISSN: 1354-1013
    E-ISSN: 1365-2486
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  • 4
    Language: English
    In: Soil Biology and Biochemistry, June, 2012, Vol.49, p.11(12)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.soilbio.2012.01.030 Byline: Lisa K. Tiemann, Sharon A. Billings Abstract: Changes in soil moisture with cycles of soil wetting and drying are associated with shifts in osmotic potentials that can induce physiological stress for microbial communities. These instances of soil moisture stress can be of sufficient magnitude to alter flows of C and N at an ecosystem scale. In this study we manipulated the duration and severity of soil moisture stress and disturbance in grassland soils from four sites along a precipitation gradient. After subjecting soils to a two-month long incubation under two different wetting-drying regimes, one of high and one of low stress and disturbance, we moistened soils with.sup.13C- and.sup.15N-labeled glycine solution to trace C and N though the soil and its microbial communities as they dried. Contrary to our predictions, we found evidence for preferential use of N-free osmolytes with increased soil moisture stress in soils from the mesic end of the precipitation gradient. Soils from the western, semi-arid end of the gradient were less sensitive to soil moisture stress and did not differ in N demand under high and low stress. Specific respiration rates were higher in all soils under greater soil moisture stress immediately after re-wetting, then returned to levels equal to or below rates in soils under low soil moisture stress regimes. Nitrification outpaced denitrification processes in soils under the highest levels of soil moisture stress. These results suggest increases in both soil CO.sub.2 release and N losses as stress induced by greater soil moisture variability increases in relatively mesic grassland systems, a predicted consequence of climate change in this region. Author Affiliation: University of Kansas, Department of Ecology and Evolutionary Biology and Kansas Biological Survey, 2101 Constant Ave., Lawrence, KS 66047, USA Article History: Received 25 August 2011; Revised 27 January 2012; Accepted 31 January 2012
    Keywords: Soil Moisture ; Soil Microbiology ; Nitrification ; Glycine ; Rain ; Evolutionary Biology ; Denitrification ; Ecosystems
    ISSN: 0038-0717
    Source: Cengage Learning, Inc.
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  • 5
    Language: English
    In: Soil Biology and Biochemistry, June, 2012, Vol.49, p.11(12)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.soilbio.2012.01.030 Byline: Lisa K. Tiemann, Sharon A. Billings Abstract: Changes in soil moisture with cycles of soil wetting and drying are associated with shifts in osmotic potentials that can induce physiological stress for microbial communities. These instances of soil moisture stress can be of sufficient magnitude to alter flows of C and N at an ecosystem scale. In this study we manipulated the duration and severity of soil moisture stress and disturbance in grassland soils from four sites along a precipitation gradient. After subjecting soils to a two-month long incubation under two different wetting-drying regimes, one of high and one of low stress and disturbance, we moistened soils with.sup.13C- and.sup.15N-labeled glycine solution to trace C and N though the soil and its microbial communities as they dried. Contrary to our predictions, we found evidence for preferential use of N-free osmolytes with increased soil moisture stress in soils from the mesic end of the precipitation gradient. Soils from the western, semi-arid end of the gradient were less sensitive to soil moisture stress and did not differ in N demand under high and low stress. Specific respiration rates were higher in all soils under greater soil moisture stress immediately after re-wetting, then returned to levels equal to or below rates in soils under low soil moisture stress regimes. Nitrification outpaced denitrification processes in soils under the highest levels of soil moisture stress. These results suggest increases in both soil CO.sub.2 release and N losses as stress induced by greater soil moisture variability increases in relatively mesic grassland systems, a predicted consequence of climate change in this region. Author Affiliation: University of Kansas, Department of Ecology and Evolutionary Biology and Kansas Biological Survey, 2101 Constant Ave., Lawrence, KS 66047, USA Article History: Received 25 August 2011; Revised 27 January 2012; Accepted 31 January 2012
    Keywords: Soil Microbiology ; Nitrification ; Precipitation (Meteorology) ; Ecosystems ; Soil Moisture ; Glycine ; Denitrification
    ISSN: 0038-0717
    Source: Cengage Learning, Inc.
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  • 6
    Language: English
    In: Soil Biology and Biochemistry, 2011, Vol.43(9), pp.1837-1847
    Description: Grassland ecosystems contain ∼12% of global soil organic carbon (C) stocks and are located in regions where global climate change will likely alter the timing and size of precipitation events, increasing soil moisture variability. In response to increased soil moisture variability and other forms of stress, microorganisms can induce ecosystem-scale alterations in C and N cycling processes through alterations in their function. We explored the influence of physiological stress on microbial communities by manipulating moisture variability in soils from four grassland sites in the Great Plains, representing a precipitation gradient of 485–1003 mm y . Keeping water totals constant, we manipulated the frequency and size of water additions and dry down periods in these soils by applying water in two different, two-week long wetting–drying cycles in a 72-day laboratory incubation. To assess the effects of the treatments on microbial community function, we measured C mineralization, N dynamics, extracellular enzyme activities (EEA) and a proxy for substrate use efficiency. In soils from all four sites undergoing a long interval (LI) treatment for which added water was applied once at the beginning of each two-week cycle, 1.4–2.0 times more C was mineralized compared to soils undergoing a short interval (SI) treatment, for which four wetting events were evenly distributed over each two-week cycle. A proxy for carbon use efficiency (CUE) suggests declines in this parameter with the greater soil moisture stress imposed in LI soils from all four different native soil moisture regimes. A decline in CUE in LI soils may have been related to an increased effort by microbes to obtain N-rich organic substrates for use as protection against osmotic shock, consistent with EEA data. These results contrast with similar studies of response to increased soil moisture variability and may indicate divergent autotrophic vs. heterotrophic responses to increased moisture variability. Increases in microbial N demand and decreases in microbial CUE with increased moisture variability observed in this study, regardless of the soils’ site of origin, imply that these systems may experience enhanced heterotrophic CO release and declines in plant-available N with climate change. This has particularly important implications for C budgets in these grasslands when coupled with the declines in net primary productivity reported in other studies as a result of increases in precipitation variability across the region. ► We observed decreased carbon use efficiency with increased soil moisture variability. ► Changes in microbial function were consistent across the precipitation gradient. ► Increased moisture variability may lead to net carbon losses from grassland systems.
    Keywords: Grassland ; Soil Carbon ; Soil Nitrogen ; Carbon Use Efficiency ; Soil Moisture Variability ; Precipitation Regime ; Climate Change ; Agriculture ; Chemistry
    ISSN: 0038-0717
    E-ISSN: 1879-3428
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  • 7
    In: Journal of Geophysical Research: Biogeosciences, March 2011, Vol.116(G1), pp.n/a-n/a
    Description: To assess how microbial processing of organic C inputs to forest soils may be influenced by elevated CO and altered N dynamics, we followed the fate of C‐labeled substrates in soils from the Duke Free Air Carbon Enrichment site where differences in soil N status have been imposed by 7 years of N amendments. Heterotrophic respiration and C of respired CO‐C and phospholipid fatty acids (PLFA) were measured to track activities of microbial groups and estimate a relative measure of substrate use efficiency (PLFA‐based SUE). Results indicate an increased proportion of fungal and actinomycete activity in elevated CO soils, which varied with substrate. The negative effect of N on vanillin phenolic‐C incorporation into actinomycete PLFA suggests legacies of fertilization can mitigate increased C flow into actinomycetes with elevated CO. Further, the fourfold increase in PLFA‐based SUE for vanillin phenolic‐C in elevated CO soils that received N suggests future enhanced N limitation in elevated CO soils may promote enhanced respiratory loss relative to incorporation of some C‐substrates into microbial biomass. These short‐term incubations did not reveal greater loss of soil organic carbon via respiration or shifts in SUE with elevated CO. However, observed relative increases in activity of actinomycetes and fungi with elevated CO and mitigation of this effect on actinomycetes with N amendments suggests that elevated CO and predicted N limitation may alter the fate of slow‐turnover soil organic matter (SOM) in two competing ways. Investigations need to focus on how these microorganisms may increase slow‐turnover substrate use while possibly enhancing the prevalence of microbial cell wall structures that can serve as precursors of stabilized SOM.
    Keywords: Soil Organic Carbon ; Heterotrophic Respiration ; Elevated Co ; Progressive N Limitation ; Phospholipid Fatty Acids ; Stable Carbon Isotopes
    ISSN: 0148-0227
    E-ISSN: 2156-2202
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  • 8
    Language: English
    In: Soil Biology and Biochemistry, June 2012, Vol.49, pp.11-22
    Description: Changes in soil moisture with cycles of soil wetting and drying are associated with shifts in osmotic potentials that can induce physiological stress for microbial communities. These instances of soil moisture stress can be of sufficient magnitude to alter flows of C and N at an ecosystem scale. In this study we manipulated the duration and severity of soil moisture stress and disturbance in grassland soils from four sites along a precipitation gradient. After subjecting soils to a two-month long incubation under two different wetting-drying regimes, one of high and one of low stress and disturbance, we moistened soils with C- and N-labeled glycine solution to trace C and N though the soil and its microbial communities as they dried. Contrary to our predictions, we found evidence for preferential use of N-free osmolytes with increased soil moisture stress in soils from the mesic end of the precipitation gradient. Soils from the western, semi-arid end of the gradient were less sensitive to soil moisture stress and did not differ in N demand under high and low stress. Specific respiration rates were higher in all soils under greater soil moisture stress immediately after re-wetting, then returned to levels equal to or below rates in soils under low soil moisture stress regimes. Nitrification outpaced denitrification processes in soils under the highest levels of soil moisture stress. These results suggest increases in both soil CO release and N losses as stress induced by greater soil moisture variability increases in relatively mesic grassland systems, a predicted consequence of climate change in this region. ► Microbial sensitivity to moisture variability increases with grassland MAP. ► Microbial communities in mesic grassland soils utilized N-free protective solutes. ► Upon osmotic downshock microbes rapidly catabolized protective solutes. ► High moisture variability led to temporal decoupling of nitrification and denitrification. ► Protective solutes represent a significant proportion of total C and N cycling.
    Keywords: Grassland ; Soil Carbon ; Soil Nitrogen ; Carbon Use Efficiency ; Soil Moisture Variability ; Precipitation Regime ; Climate Change ; Agriculture ; Chemistry
    ISSN: 0038-0717
    E-ISSN: 1879-3428
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  • 9
    Language: English
    In: New Phytologist, 2015, Vol.206(3), p.900(13)
    Description: To purchase or authenticate to the full-text of this article, please visit this link: http://onlinelibrary.wiley.com/doi/10.1111/nph.13338/abstract Byline: Daniel deB. Richter, Sharon A. Billings Keywords: biogeochemistry; biogeosciences; ecohydrology; ecosystem ecology; ecosystem metabolism; soil respiration; weathering profile 900 I. [I.] 900 II. [II.] 901 III. [III.] 901 IV. [IV. 1. 2.] 902 V. [V. 1. 2.] 905 VI. [VI.] 908 [Acknowledg] 909 References 909 Summary Integrative concepts of the biosphere, ecosystem, biogeocenosis and, recently, Earth's critical zone embrace scientific disciplines that link matter, energy and organisms in a systems-level understanding of our remarkable planet. Here, we assert the congruence of Tansley's (1935) venerable ecosystem concept of 'one physical system' with Earth science's critical zone. Ecosystems and critical zones are congruent across spatial-temporal scales from vegetation-clad weathering profiles and hillslopes, small catchments, landscapes, river basins, continents, to Earth's whole terrestrial surface. What may be less obvious is congruence in the vertical dimension. We use ecosystem metabolism to argue that full accounting of photosynthetically fixed carbon includes respiratory CO.sub.2 and carbonic acid that propagate to the base of the critical zone itself. Although a small fraction of respiration, the downward diffusion of CO.sub.2 helps determine rates of soil formation and, ultimately, ecosystem evolution and resilience. Because life in the upper portions of terrestrial ecosystems significantly affects biogeochemistry throughout weathering profiles, the lower boundaries of most terrestrial ecosystems have been demarcated at depths too shallow to permit a complete understanding of ecosystem structure and function. Opportunities abound to explore connections between upper and lower components of critical-zone ecosystems, between soils and streams in watersheds, and between plant-derived CO.sub.2 and deep microbial communities and mineral weathering.
    Keywords: Terrestrial Ecosystems – Environmental Aspects ; Biogeochemistry – Environmental Aspects
    ISSN: 0028-646X
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  • 10
    Language: English
    In: Forest Ecology and Management, Oct 15, 2015, Vol.354, p.190(16)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.foreco.2015.06.019 Byline: Laurel J. Haavik, Sharon A. Billings, James M. Guldin, Fred M. Stephen Abstract: Display Omitted Article History: Received 23 March 2015; Revised 9 June 2015; Accepted 14 June 2015
    Keywords: Droughts
    ISSN: 0378-1127
    Source: Cengage Learning, Inc.
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