51 research outputs found
Amplitude and frequency of wetting and drying cycles drive N and NO emissions from a subtropical pasture
This study investigated the effects of irrigation frequency on N and NO emissions from an intensively managed pasture in the subtropics. Irrigation volumes were estimated to replace evapotranspiration and were applied either once (low frequency) or split into four applications (high frequency). To test for legacy effects, a large rainfall event was simulated at the end of the experiment. Over 15 days, 7.9 ± 2.7 kg N + NO-N ha was emitted on average regardless of irrigation frequency, with NO accounting for 25% of overall N + NO. Repeated, small amounts of irrigation produced an equal amount of N + NO losses as a single, large irrigation event. The increase in NO emissions after the large rainfall event was smaller in the high-frequency treatment, shifting the NO/(NO + N) ratio towards N, indicating a treatment legacy effect. Cumulative losses of NO and N did not differ between treatments, but higher CO emissions were observed in the high-frequency treatment. Our results suggest that the increase in microbial activity and related O consumption in response to small and repeated wetting events can offset the effects of increased soil gas diffusivity on denitrification, explaining the lack of treatment effect on cumulative NO and N emissions and the abundance of N cycling marker genes. The observed legacy effect may be linked to increased mineralisation and subsequent increased dissolved organic carbon availability, suggesting that increased irrigation frequency can reduce the environmental impact (NO), but not overall magnitude of NO and N emissions from intensively managed pastures
Effect of the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on N-turnover, the NO reductase-gene nosZ and NO:N partitioning from agricultural soils
Nitrification inhibitors (NIs) have been shown to reduce emissions of the greenhouse gas nitrous oxide (NO) from agricultural soils. However, their NO reduction efficacy varies widely across different agro-ecosystems, and underlying mechanisms remain poorly understood. To investigate effects of the NI 3,4-dimethylpyrazole-phosphate (DMPP) on N-turnover from a pasture and a horticultural soil, we combined the quantification of N and NO emissions with N tracing analysis and the quantification of the NO-reductase gene (nosZ) in a soil microcosm study. Nitrogen fertilization suppressed nosZ abundance in both soils, showing that high nitrate availability and the preferential reduction of nitrate over NO is responsible for large pulses of NO after the fertilization of agricultural soils. DMPP attenuated this effect only in the horticultural soil, reducing nitrification while increasing nosZ abundance. DMPP reduced NO emissions from the horticultural soil by >50% but did not affect overall N + NO losses, demonstrating the shift in the NO:N ratio towards N as a key mechanism of NO mitigation by NIs. Under non-limiting NO availability, the efficacy of NIs to mitigate NO emissions therefore depends on their ability to reduce the suppression of the NO reductase by high NO concentrations in the soil, enabling complete denitrification to N
Evolution of CDC42, a putative virulence factor triggering meristematic growth in black yeasts
The cell division cycle gene (CDC42) controlling cellular
polarization was studied in members of Chaetothyriales. Based on
ribosomal genes, ancestral members of the order exhibit meristematic growth in
view of their colonization of inert surfaces such as rock, whereas in derived
members of the order the gene is a putative virulence factor involved in
expression of the muriform cell, the invasive phase in human
chromoblastomycosis. Specific primers were developed to amplify a portion of
the gene of 32 members of the order with known position according to ribosomal
phylogeny. Phylogeny of CDC42 proved to be very different. In all
members of Chaetohyriales the protein sequence is highly conserved.
In most species, distributed all over the phylogenetic tree, introns and
3rd codon positions are also invariant. However, a number of
species had paralogues with considerable deviation in non-coding exon
positions, and synchronous variation in introns, although non-synonomous
variation had remained very limited. In some strains both orthologues and
paralogues were present. It is concluded that CDC42 does not show any
orthologous evolution, and that its paralogues haves the same function but are
structurally relaxed. The variation or absence thereof could not be linked to
ecological changes, from rock-inhabiting to pathogenic life style. It is
concluded that eventual pathogenicity in Chaetothyriales is not
expressed at the DNA level in CDC42 evolution
Heat stored in the Earth system 1960–2020: where does the energy go?
The Earth climate system is out of energy balance, and heat has accumulated continuously over the past decades, warming the ocean, the land, the cryosphere, and the atmosphere. According to the Sixth Assessment Report by Working Group I of the Intergovernmental Panel on Climate Change, this planetary warming over multiple decades is human-driven and results in unprecedented and committed changes to the Earth system, with adverse impacts for ecosystems and human systems. The Earth heat inventory provides a measure of the Earth energy imbalance (EEI) and allows for quantifying how much heat has accumulated in the Earth system, as well as where the heat is stored. Here we show that the Earth system has continued to accumulate heat, with 381±61 ZJ accumulated from 1971 to 2020. This is equivalent to a heating rate (i.e., the EEI) of 0.48±0.1 W m−2. The majority, about 89 %, of this heat is stored in the ocean, followed by about 6 % on land, 1 % in the atmosphere, and about 4 % available for melting the cryosphere. Over the most recent period (2006–2020), the EEI amounts to 0.76±0.2 W m−2. The Earth energy imbalance is the most fundamental global climate indicator that the scientific community and the public can use as the measure of how well the world is doing in the task of bringing anthropogenic climate change under control. Moreover, this indicator is highly complementary to other established ones like global mean surface temperature as it represents a robust measure of the rate of climate change and its future commitment. We call for an implementation of the Earth energy imbalance into the Paris Agreement's Global Stocktake based on best available science. The Earth heat inventory in this study, updated from von Schuckmann et al. (2020), is underpinned by worldwide multidisciplinary collaboration and demonstrates the critical importance of concerted international efforts for climate change monitoring and community-based recommendations and we also call for urgently needed actions for enabling continuity, archiving, rescuing, and calibrating efforts to assure improved and long-term monitoring capacity of the global climate observing system. The data for the Earth heat inventory are publicly available, and more details are provided in Table 4
Community profiling and gene expression of fungal assimilatory nitrate reductases in agricultural soil
Although fungi contribute significantly to the microbial biomass in terrestrial ecosystems, little is known about their contribution to biogeochemical nitrogen cycles. Agricultural soils usually contain comparably high amounts of inorganic nitrogen, mainly in the form of nitrate. Many studies focused on bacterial and archaeal turnover of nitrate by nitrification, denitrification and assimilation, whereas the fungal role remained largely neglected. To enable research on the fungal contribution to the biogeochemical nitrogen cycle tools for monitoring the presence and expression of fungal assimilatory nitrate reductase genes were developed. To the ∼100 currently available fungal full-length gene sequences, another 109 partial sequences were added by amplification from individual culture isolates, representing all major orders occurring in agricultural soils. The extended database led to the discovery of new horizontal gene transfer events within the fungal kingdom. The newly developed PCR primers were used to study gene pools and gene expression of fungal nitrate reductases in agricultural soils. The availability of the extended database allowed affiliation of many sequences to known species, genera or families. Energy supply by a carbon source seems to be the major regulator of nitrate reductase gene expression for fungi in agricultural soils, which is in good agreement with the high energy demand of complete reduction of nitrate to ammonium
Prediction of Dementia in Primary Care Patients
BACKGROUND: Current approaches for AD prediction are based on biomarkers, which are however of restricted availability in primary care. AD prediction tools for primary care are therefore needed. We present a prediction score based on information that can be obtained in the primary care setting. METHODOLOGY/PRINCIPAL FINDINGS: We performed a longitudinal cohort study in 3.055 non-demented individuals above 75 years recruited via primary care chart registries (Study on Aging, Cognition and Dementia, AgeCoDe). After the baseline investigation we performed three follow-up investigations at 18 months intervals with incident dementia as the primary outcome. The best set of predictors was extracted from the baseline variables in one randomly selected half of the sample. This set included age, subjective memory impairment, performance on delayed verbal recall and verbal fluency, on the Mini-Mental-State-Examination, and on an instrumental activities of daily living scale. These variables were aggregated to a prediction score, which achieved a prediction accuracy of 0.84 for AD. The score was applied to the second half of the sample (test cohort). Here, the prediction accuracy was 0.79. With a cut-off of at least 80% sensitivity in the first cohort, 79.6% sensitivity, 66.4% specificity, 14.7% positive predictive value (PPV) and 97.8% negative predictive value of (NPV) for AD were achieved in the test cohort. At a cut-off for a high risk population (5% of individuals with the highest risk score in the first cohort) the PPV for AD was 39.1% (52% for any dementia) in the test cohort. CONCLUSIONS: The prediction score has useful prediction accuracy. It can define individuals (1) sensitively for low cost-low risk interventions, or (2) more specific and with increased PPV for measures of prevention with greater costs or risks. As it is independent of technical aids, it may be used within large scale prevention programs
Heat stored in the Earth system 1960–2020: where does the energy go?
The Earth climate system is out of energy balance, and heat has
accumulated continuously over the past decades, warming the ocean, the land,
the cryosphere, and the atmosphere. According to the Sixth Assessment Report
by Working Group I of the Intergovernmental Panel on Climate Change,
this planetary warming over multiple decades is human-driven and results in
unprecedented and committed changes to the Earth system, with adverse
impacts for ecosystems and human systems. The Earth heat inventory provides
a measure of the Earth energy imbalance (EEI) and allows for quantifying
how much heat has accumulated in the Earth system, as well as where the heat is
stored. Here we show that the Earth system has continued to accumulate
heat, with 381±61 ZJ accumulated from 1971 to 2020. This is equivalent to a
heating rate (i.e., the EEI) of 0.48±0.1 W m−2. The majority,
about 89 %, of this heat is stored in the ocean, followed by about 6 %
on land, 1 % in the atmosphere, and about 4 % available for melting
the cryosphere. Over the most recent period (2006–2020), the EEI amounts to
0.76±0.2 W m−2. The Earth energy imbalance is the most
fundamental global climate indicator that the scientific community and the
public can use as the measure of how well the world is doing in the task of
bringing anthropogenic climate change under control. Moreover, this
indicator is highly complementary to other established ones like global mean
surface temperature as it represents a robust measure of the rate of climate
change and its future commitment. We call for an implementation of the
Earth energy imbalance into the Paris Agreement's Global Stocktake based on
best available science. The Earth heat inventory in this study, updated from
von Schuckmann et al. (2020), is underpinned by worldwide multidisciplinary
collaboration and demonstrates the critical importance of concerted
international efforts for climate change monitoring and community-based
recommendations and we also call for urgently needed actions for enabling
continuity, archiving, rescuing, and calibrating efforts to assure improved
and long-term monitoring capacity of the global climate observing system. The data for the Earth heat inventory are publicly available, and more details are provided in Table 4.</p
CREST - Classification Resources for Environmental Sequence Tags
10.1371/journal.pone.0049334PLoS ONE711e4933
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