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1.
Ecotoxicol Environ Saf ; 208: 111688, 2021 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-33396020

RESUMEN

Elemental defense hypothesis suggests that toxic metals accumulated in plant tissues could enhance plant defense against herbivores and pathogens. Since over-accumulation of metals in plant organs will pose negative effects on plant health, it is necessary to find a way to alleviate metal-induced toxicity in plants while keeping or even improving plant resistance. Exogenous nitrogen (N) application was reported to have such alleviation effect while stimulating metal accumulation in plant tissues. In this study, we examined whether soil N addition in three different doses to a poplar species under cadmium (Cd) stress can simultaneously improve plant growth and resistance to four herbivorous insects and a leaf pathogen. The results showed that N application to Cd-amended soil prominently enhanced plant growth and leaf Cd accumulation. While N addition in three doses all remarkably reduced herbivore growth than control plants, only the highest N dose exerted stronger inhibition than the sole Cd-treated plants. In the paired-choice experiment, plants supplied with the highest N dose showed an enhanced deterrent effect on herbivore preference than plants exposed to sole Cd. Furthermore, plant resistance to the leaf pathogen infection was strongly enhanced as the levels of N addition increased. Leaf sugar and three main defensive chemicals were not affected by N application implied that such enhanced effect of N on plant resistance was due to increased leaf Cd accumulation. Our results suggested that the application of exogenous N over a certain amount could enhance the resistance of Cd-treated plants to leaf herbivory and pathogen infection.


Asunto(s)
Cadmio/toxicidad , Nitrógeno/farmacología , Hojas de la Planta/efectos de los fármacos , Populus/efectos de los fármacos , Contaminantes del Suelo/toxicidad , Animales , Cadmio/metabolismo , Herbivoria/efectos de los fármacos , Lepidópteros/efectos de los fármacos , Enfermedades de las Plantas/microbiología , Enfermedades de las Plantas/prevención & control , Hojas de la Planta/crecimiento & desarrollo , Hojas de la Planta/microbiología , Populus/crecimiento & desarrollo , Populus/microbiología , Suelo/química , Contaminantes del Suelo/metabolismo
2.
Int J Food Microbiol ; 339: 109014, 2021 Feb 02.
Artículo en Inglés | MEDLINE | ID: mdl-33333444

RESUMEN

The objective of this study was to develop a method with improved sensitivity for Campylobacter jejuni detection in foods. Nitrogen-doped carbon nanodots (N-CNDs) were synthesized and added to an enrichment medium (Bolton broth) at a concentration of 10 mg/mL. A light-emitting diode (LED) at a wavelength of 425 nm was used to irradiate the N-CNDs-supplemented enrichment medium to induce an exothermic reaction for 1 h. Additionally, a monoclonal antibody specific to C. jejuni NCTC11168 was developed using hybridoma cells to aid detection. The C. jejuni detection capabilities of N-CNDs-supplemented enrichment medium and the conventional Bolton broth enrichment, were compared using duck samples. C. jejuni in the enrichment was detected with the monoclonal antibody based-indirect enzyme-linked immunosorbent assay (ID-ELISA). The N-CNDs-supplemented enrichment medium showed a better C. jejuni detection capability than the conventional Bolton broth enrichment. Additionally, data from ID-ELISA showed excellent detection efficiency and a shortened detection time in the N-CNDs-supplemented enrichment medium after LED irradiation at 425 nm. These results indicate that 1-h LED irradiation at 425 nm to Bolton broth supplemented with the N-CNDs increased the detection efficiency and shortened the detection time with the monoclonal antibody for C. jejuni in food.


Asunto(s)
Campylobacter jejuni/aislamiento & purificación , Ensayo de Inmunoadsorción Enzimática , Microbiología de Alimentos/métodos , Carne/microbiología , Nanopartículas/química , Animales , Anticuerpos Monoclonales/metabolismo , Bacterias/efectos de los fármacos , Carbono/química , Carbono/farmacología , Medios de Cultivo , Patos/microbiología , Nitrógeno/química , Nitrógeno/farmacología
3.
Proc Natl Acad Sci U S A ; 117(52): 33317-33324, 2020 12 29.
Artículo en Inglés | MEDLINE | ID: mdl-33318221

RESUMEN

Whether and how CO2 and nitrogen (N) availability interact to influence carbon (C) cycling processes such as soil respiration remains a question of considerable uncertainty in projecting future C-climate feedbacks, which are strongly influenced by multiple global change drivers, including elevated atmospheric CO2 concentrations (eCO2) and increased N deposition. However, because decades of research on the responses of ecosystems to eCO2 and N enrichment have been done largely independently, their interactive effects on soil respiratory CO2 efflux remain unresolved. Here, we show that in a multifactor free-air CO2 enrichment experiment, BioCON (Biodiversity, CO2, and N deposition) in Minnesota, the positive response of soil respiration to eCO2 gradually strengthened at ambient (low) N supply but not enriched (high) N supply for the 12-y experimental period from 1998 to 2009. In contrast to earlier years, eCO2 stimulated soil respiration twice as much at low than at high N supply from 2006 to 2009. In parallel, microbial C degradation genes were significantly boosted by eCO2 at low but not high N supply. Incorporating those functional genes into a coupled C-N ecosystem model reduced model parameter uncertainty and improved the projections of the effects of different CO2 and N levels on soil respiration. If our observed results generalize to other ecosystems, they imply widely positive effects of eCO2 on soil respiration even in infertile systems.


Asunto(s)
Dióxido de Carbono/farmacología , Pradera , Nitrógeno/farmacología , Suelo/química , Aerobiosis , Simulación por Computador , Microbiología del Suelo
4.
Int J Nanomedicine ; 15: 6961-6973, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33061362

RESUMEN

Background: Although graphene quantum dots (GQDs) have received considerable research attention for their applications in various fields, the use of GQDs, such as nitrogen-doped GQDs (N-GQDs) and amino-functionalized N-GQDs (amino-N-GQDs), as photosensitizers to facilitate photodynamic therapy (PDT) has received limited research intention. To address this research gap, this study prepared novel amino-N-GQDs and investigated their properties. Methods: The amino-N-GQDs subjected to two-photon excitation (TPE) exhibited remarkable bactericidal capability in PDT. The bonding compositions of nitrogen and the amino-functionalized group played a critical role in their antimicrobial effects. Results: Compared with amino-group-free N-GQDs and amino-N-free GQDs, the amino-N-GQDs generated a higher amount of reactive oxygen species, demonstrating their superior efficacy for two-photon PDT. Additionally, the intrinsic luminescence properties and high photostability of the amino-N-GQDs demonstrate their suitability as an effective two-photon contrast agent for tracking bacteria during two-photon biomedical imaging. Conclusion: The amino-N-GQD and their remarkable properties may provide an efficient alternative approach for observing and easily eliminating malignant microbes in the future.


Asunto(s)
Antibacterianos/farmacología , Medios de Contraste/química , Nitrógeno/farmacología , Fotoquimioterapia/métodos , Puntos Cuánticos/química , Antibacterianos/química , Bacillus subtilis/efectos de los fármacos , Grafito/química , Luminiscencia , Nitrógeno/química , Fotones , Fármacos Fotosensibilizantes/química , Fármacos Fotosensibilizantes/farmacología
5.
PLoS One ; 15(9): e0238362, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32877452

RESUMEN

Water and nutrient absorption from soil by crops mainly depend on the morphological traits and distribution of the crop roots. Dense planting with reduced nitrogen is a sustainable strategy for improving grain yield and nitrogen use efficiency. However, there is little information on the effects of dense planting with reduced nitrogen on direct-seeded inbred rice. Two-year field experiments were conducted with minirhizotron techniques to characterize the root morphological traits and distributions under different nitrogen application rates and sowing densities in two representative inbred rice varieties, Huanghuazhan (HHZ) and Yuenongsimiao (YNSM), grown under three nitrogen application rates (N0: 0 kg ha-1, LN: 135 kg ha-1, HN: 180 kg ha-1) and two sowing densities (LD: 18.75 kg ha-1, HD: 22.5 kg ha-1). Our study showed that dense planting with low nitrogen improved grain yield partly due to the increased panicle number. The higher sowing density with low nitrogen significantly affected the total root number (TRN), total root length (TRL), total root surface area (TRSA), and total root volume (TRV). There was a significant positive correlation between grain yield and TRL in the 10-20-cm soil layer (P < 0.05). The root morphological indexes were positively correlated with dry matter accumulation (P < 0.05) and negatively correlated with nitrogen content (P < 0.05) at the maturity stage. This study showed that a high sowing density with low nitrogen application can improve root morphology and distribution and increase grain yield and nitrogen use efficiency in direct-seeded inbred rice.


Asunto(s)
Nitrógeno/farmacología , Oryza/fisiología , Raíces de Plantas/anatomía & histología , Raíces de Plantas/fisiología , Semillas/fisiología , Suelo/química , Agua/química , Oryza/efectos de los fármacos , Fenotipo , Raíces de Plantas/efectos de los fármacos , Estaciones del Año , Semillas/efectos de los fármacos
6.
PLoS Biol ; 18(8): e3000757, 2020 08.
Artículo en Inglés | MEDLINE | ID: mdl-32833957

RESUMEN

In eukaryotes, conserved mechanisms ensure that cell growth is coordinated with nutrient availability. Overactive growth during nutrient limitation ("nutrient-growth dysregulation") can lead to rapid cell death. Here, we demonstrate that cells can adapt to nutrient-growth dysregulation by evolving major metabolic defects. Specifically, when yeast lysine-auxotrophic mutant lys- encountered lysine limitation, an evolutionarily novel stress, cells suffered nutrient-growth dysregulation. A subpopulation repeatedly evolved to lose the ability to synthesize organosulfurs (lys-orgS-). Organosulfurs, mainly reduced glutathione (GSH) and GSH conjugates, were released by lys- cells during lysine limitation when growth was dysregulated, but not during glucose limitation when growth was regulated. Limiting organosulfurs conferred a frequency-dependent fitness advantage to lys-orgS- by eliciting a proper slow growth program, including autophagy. Thus, nutrient-growth dysregulation is associated with rapid organosulfur release, which enables the selection of organosulfur auxotrophy to better tune cell growth to the metabolic environment. We speculate that evolutionarily novel stresses can trigger atypical release of certain metabolites, setting the stage for the evolution of new ecological interactions.


Asunto(s)
Adaptación Fisiológica/genética , Lisina/farmacología , Redes y Vías Metabólicas/efectos de los fármacos , Nutrientes/farmacología , Saccharomyces cerevisiae/metabolismo , Autofagia/efectos de los fármacos , Autofagia/genética , Evolución Biológica , Glucosa/metabolismo , Glucosa/farmacología , Lisina/deficiencia , Redes y Vías Metabólicas/genética , Nitrógeno/metabolismo , Nitrógeno/farmacología , Nutrientes/metabolismo , Ribosomas/efectos de los fármacos , Ribosomas/metabolismo , Saccharomyces cerevisiae/efectos de los fármacos , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/crecimiento & desarrollo , Sirolimus/farmacología , Estrés Fisiológico
7.
PLoS One ; 15(7): e0235755, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32649709

RESUMEN

As a widespread phytoplankton species, the coccolithophore Gephyrocapsaoceanica has a significant impact on the global biogeochemical cycle through calcium carbonate precipitation and photosynthesis. As global change continues, marine phytoplankton will experience alterations in multiple parameters, including temperature, pH, CO2, and nitrogen sources, and the interactive effects of these variables should be examined to understand how marine organisms will respond to global change. Here, we show that the specific growth rate of G. oceanica is reduced by elevated CO2 (1000 µatm) in [Formula: see text]-grown cells, while it is increased by high CO2 in [Formula: see text]-grown ones. This difference was related to intracellular metabolic regulation, with decreased cellular particulate organic carbon and particulate organic nitrogen (PON) content in the [Formula: see text] and high CO2 condition compared to the low CO2 condition. In contrast, no significant difference was found between the high and low CO2 levels in [Formula: see text] cultures (p > 0.05). The temperature increase from 20°C to 25°C increased the PON production rate, and the enhancement was more prominent in [Formula: see text] cultures. Enhanced or inhibited particulate inorganic carbon production rate in cells supplied with [Formula: see text] relative to [Formula: see text] was observed, depending on the temperature and CO2 condition. These results suggest that a greater disruption of the organic carbon pump can be expected in response to the combined effects of increased [Formula: see text]/[Formula: see text] ratio, temperature, and CO2 level in the oceans of the future. Additional experiments conducted under nutrient limitation conditions are needed before we can extrapolate our findings to the global oceans.


Asunto(s)
Dióxido de Carbono/farmacología , Haptophyta/crecimiento & desarrollo , Nitrógeno/farmacología , Dióxido de Carbono/análisis , Haptophyta/efectos de los fármacos , Nitrógeno/análisis , Temperatura
8.
Ecotoxicol Environ Saf ; 202: 110875, 2020 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-32580081

RESUMEN

Nitrification inhibitors (NIs) are used to retard the nitrification process and reduce nitrogen (N) losses. However, the effects of soil properties on NI efficacy are less clear. Moreover, the direct and indirect effects of soil property variations on NI efficiency in minimizing carbon dioxide (CO2) emissions have not been previously studied. An incubation experiment was conducted for 40 days with two treatments, N (200 mg N-urea kg-1) and N + dicyandiamide (DCD) (20 mg DCD kg-1), and a control group (without the N) to investigate the response of ammonia-oxidizing bacteria (AOB) and archaea (AOA) to DCD application and the consequences for CO2, nitrous oxide (N2O) and ammonia (NH3) emissions from six soils from the Loess Plateau with different properties. The nitrification process completed within 6-18 days for the N treatment and within 30->40 days for the N + DCD treatment. AOB increased significantly with N fertilizer application, while this effect was inhibited in soils when DCD was applied. AOA was not sensitive to N fertilizer and DCD application. The nitrification rate was positively correlated with the clay (p < 0.05) and SOM contents (p < 0.01); DCD was more effective in loam soil with low SOM and high soil pH. Soil pH significantly was decreased with N fertilizer application, while it increased when DCD was applied. Moreover, DCD application decreased CO2 emissions from soils by 22%-172%; CO2 emissions were negatively correlated with the clay and SOM contents. DCD application decreased N2O emissions in each soil by 1.0- to 94-fold compared with those after N fertilizer application. In contrast, DCD application increased NH3 release from soils by 59-278%. NH3 volatilization was negatively correlated with clay (p < 0.05) and SOM (p < 0.01) contents and positively correlated with soil pH (p < 0.01). Therefore, soil texture, SOM and soil pH have significant effects on the DCD performance, nitrification process and gaseous emissions.


Asunto(s)
Dióxido de Carbono/análisis , Guanidinas/análisis , Nitrificación/efectos de los fármacos , Amoníaco/análisis , Archaea/efectos de los fármacos , Betaproteobacteria , Fertilizantes/análisis , Nitrógeno/farmacología , Óxido Nitroso , Suelo/química , Microbiología del Suelo , Urea
9.
PLoS One ; 15(6): e0234544, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32555670

RESUMEN

Controlled-release and slow-release fertilizers can effectively supply nitrogen (N) while mitigating N loss. To determine the suitability of these fertilizers for plants in semi-arid environments, these fertilizers need to be evaluated under varying placement and temperature conditions. Several urea fertilizers were evaluated, including: uncoated, sulfur-coated (SCU), polymer-coated-sulfur-coated (PCSCU), and polymer-coated (PCU) with projected release timings between 45 and 180 d. Nitrogen release was measured under daily fluctuating or static temperatures applied either to the surface or buried in the soil. A second experiment consisted of two PCU sources and added a hanging bag placement comparison and low and high soil moisture treatments. For the first Experiment, the N in uncoated urea released shortly after application. The SCU and PCSCU treatments released > 80% of the N before the first sampling date. With fluctuating temperatures, the PCU 45, 75, 120, and 180 incorporated into the soil released N within +9, +9, -22, and -68 d of their expected timing. However, they released their N within 35 d when surface applied. Conversely, with static temperatures, PCU products released slowly, releasing under 80% for the entire study. The second experiment verified these results and showed no difference between low and high moisture and minimal release with fertilizer not in contact with soil. Each coated fertilizer in these studies exhibited slow/control release properties, but the PCU (surface applied) and SCU/PCSCU (surface applied or incorporated in soil) release was much more rapid than expected. Our research suggests that, although the SCU and PCSCU showed minimal slow-release properties (regardless of placement), the PCU fertilizers incorporated in the soil do have a controlled release approximate to what is expected, but have a much more rapid release when surface applied.


Asunto(s)
Agricultura , Preparaciones de Acción Retardada/farmacología , Fertilizantes , Nitrógeno/farmacología , Preparaciones de Acción Retardada/química , Nitrógeno/química , Polímeros/química , Suelo/química , Azufre/química , Temperatura , Urea/química , Urea/farmacología
10.
PLoS One ; 15(5): e0232011, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32374731

RESUMEN

Nitrogen (N) is critical to the growth and productivity of crops. To understand the molecular mechanisms influenced by N stress, we used RNA-Sequencing (RNA-Seq) to analyze differentially expressed genes (DEGs) in root and leaf tissues of spinach. N stress negatively influenced photosynthesis, biomass accumulation, amino acid profiles, and partitioning of N across tissues. RNA-seq analysis revealed that N stress caused most transcriptomic changes in roots, identifying 1,346 DEGs. High-affinity nitrate transporters (NRT2.1, NRT2.5) and glutamine amidotransferase (GAT1) genes were strongly induced in roots in response to N deplete and replete conditions, respectively. GO and KEGG analyses revealed that the functions associated with metabolic pathways and nutrient reservoir activity were enriched due to N stress. Whereas KEGG pathway enrichment analysis indicated the upregulation of DEGs associated with DNA replication, pyrimidine, and purine metabolism in the presence of high N in leaf tissue. A subset of transcription factors comprising bHLH, MYB, WRKY, and AP2/ERF family members was over-represented in both tissues in response to N perturbation. Interesting DEGs associated with N uptake, amino acid metabolism, hormonal pathway, carbon metabolism, along with transcription factors, were highlighted. The results provide valuable information about the underlying molecular processes in response to N stress in spinach and; could serve as a resource for functional analysis of candidate genes/pathways and enhancement of nitrogen use efficiency.


Asunto(s)
Nitrógeno/metabolismo , Spinacia oleracea/genética , Spinacia oleracea/metabolismo , Estrés Fisiológico/genética , Transcriptoma , Perfilación de la Expresión Génica , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Redes y Vías Metabólicas/efectos de los fármacos , Redes y Vías Metabólicas/genética , Nitrógeno/deficiencia , Nitrógeno/farmacología , Especificidad de Órganos/efectos de los fármacos , Especificidad de Órganos/genética , Fotosíntesis/efectos de los fármacos , Fotosíntesis/genética , Hojas de la Planta/efectos de los fármacos , Hojas de la Planta/genética , Hojas de la Planta/metabolismo , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/genética , Raíces de Plantas/metabolismo , RNA-Seq/métodos , Análisis de Secuencia de ARN/métodos , Spinacia oleracea/efectos de los fármacos , Estrés Fisiológico/efectos de los fármacos , Transcriptoma/efectos de los fármacos
11.
Plant Physiol Biochem ; 151: 743-750, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32361224

RESUMEN

Split application could improve nitrogen (N) uptake and increase sweetpotato yields under reduced N supply; however, little is known about how it affects the process of starch production in storage roots. An experiment was conducted to determine the effects of three N management strategies [conventional basal N management; 80% of the conventional N rate applied as a basal fertilizer; 80% of the conventional N rate equally split at transplanting and 35 days after transplanting] on starch accumulation, enzyme activity and genes expression in the conversion of sucrose to starch and the relationships among them. The results showed that, compared with conventional basal N management, split application decreased sucrose accumulation by 11.78%, but increased starch accumulation by 11.12% through improving the starch accumulation rate under reduced N supply. The ratio of sucrose synthetase to sucrose phosphate synthase, the enzymatic activity of ADP-glucose pyrophosphorylase (AGPP), starch synthase, and the expression of their corresponding genes were promoted by split application under reduced N supply and were positively correlated with starch accumulation rate. AGPP is the rate-limiting enzyme in starch synthesis in storage roots under different N management strategies. These results indicate that starch accumulation was enhanced by split application through regulating the activity and gene expression of key enzymes involved in the conversion of sucrose to starch under reduced N supply.


Asunto(s)
Ipomoea batatas , Nitrógeno , Almidón , Sacarosa , Activación Enzimática/efectos de los fármacos , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Glucosa-1-Fosfato Adenililtransferasa/genética , Glucosa-1-Fosfato Adenililtransferasa/metabolismo , Ipomoea batatas/efectos de los fármacos , Ipomoea batatas/enzimología , Ipomoea batatas/genética , Ipomoea batatas/metabolismo , Nitrógeno/farmacología , Almidón/biosíntesis , Sacarosa/metabolismo
12.
Biochem Biophys Res Commun ; 526(4): 1138-1142, 2020 06 11.
Artículo en Inglés | MEDLINE | ID: mdl-32317185

RESUMEN

Brown macroalgae is a promising marine biomass for the production of bioethanol and biodiesel fuels. Here we investigate the biochemical processes used by marine oleaginous yeast for assimilating the major carbohydrate found in brown macroalgae. Briefly, yeast Rhodosporidiobolus fluvialis strain Y2 was isolated from seawater and grown in minimal medium containing reduced sugar alcohol mannitol as the sole carbon source with a salinity comparable to seawater. Conditions limiting nitrogen were used to facilitate lipid synthesis. R. fluvialis Y2 yielded 55.1% (w/w) and 39.1% (w/w) of lipids, per dry cell weight, from mannitol in the absence and presence of salinity, respectively. Furthermore, mannitol, as a sugar source, led to an increase in the composition of polyunsaturated fatty acids, linoleic acid (C18:2) and linolenic acid (C18:3), compared to glucose. This suggests that oxidation of mannitol leads to the activation of NADH-dependent fatty acid desaturases in R. fluvialis Y2. Such fatty acid composition may contribute to the cold-flow properties of biodiesel fuels. Our results identified a salt-tolerant oleaginous yeast species with unique metabolic traits, demonstrating a key role as a decomposer in the global carbon cycle through marine ecosystems. This is the first study on mannitol-induced synthesis of lipids enriched with polyunsaturated fatty acids by marine yeast.


Asunto(s)
Organismos Acuáticos/metabolismo , Basidiomycota/metabolismo , Ácidos Grasos Insaturados/metabolismo , Manitol/metabolismo , Organismos Acuáticos/ultraestructura , Basidiomycota/efectos de los fármacos , Basidiomycota/aislamiento & purificación , Basidiomycota/ultraestructura , Ácidos Grasos Insaturados/biosíntesis , Nitrógeno/farmacología , Oxidación-Reducción
13.
PLoS One ; 15(4): e0224588, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32236110

RESUMEN

Nitrogen (N), phosphorus (P), potassium (K), and water are four crucial factors that have significant effects on strawberry yield and fruit quality. We used a 11 that involved 36 treatments with five levels of each of the four variables (N, P, and K fertilizers and water) to optimize fertilization and water combination for high yield and quality. Moreover, we used the SSC/TA ratio (the ratio of soluble solid content to titratable acid) as index of quality. Results showed that N fertilizer was the most important factor, followed by water and P fertilizer, and the N fertilizer had significant effect on yield and SSC/TA ratio. By contrast, the K fertilizer had significant effect only on yield. N×K fertilizer interacted significantly on yield, whereas the other interactions among the four factors had no significant effects on yield or SSC/TA ratio. The effects of the four factors on yield and SSC/TA ratio were ranked as N fertilizer > water > K fertilizer > P fertilizer and N fertilizer > P fertilizer > water > K fertilizer, respectively. The yield and SSC/TA ratio increased when NPK fertilizer and water increased, but then decreased when excessive NPK fertilizer and water were applied. The optimal fertilizer and water combination were 22.28-24.61 g plant-1 Ca (NO3)2·4H2O, 1.75-2.03 g plant-1 NaH2PO4, 12.41-13.91 g plant-1 K2SO4, and 12.00-13.05 L water plant-1 for yields of more than 110 g plant-1 and optimal SSC/TA ratio of 8.5-14.


Asunto(s)
Riego Agrícola/métodos , Producción de Cultivos/métodos , Fertilizantes/normas , Fragaria/crecimiento & desarrollo , Riego Agrícola/normas , Biomasa , Producción de Cultivos/normas , Fragaria/efectos de los fármacos , Frutas/crecimiento & desarrollo , Frutas/normas , Nitrógeno/farmacología , Fósforo/farmacología , Potasio/farmacología
14.
Sci Rep ; 10(1): 4047, 2020 03 04.
Artículo en Inglés | MEDLINE | ID: mdl-32132568

RESUMEN

Haze and cloudy weather reduce photo-synthetically active radiation (PAR), which affects the formation of crop yield and nitrogen (N) fertilizer utilization.. We conducted field trails in normal year and severe winter haze year, aiming to compare the difference of photosynthesis and N uptake in winter rapeseed under different N levels. Daily sunshine hours and averaged radiation intensity in winter haze year decreased by 54.1% and 33.3% respectively as compared with the past 30 years. Diurnal variation of net photosynthetic rate in winter haze day was 16.2% lower than that of sunny day. Leaf area and photosynthetic capacity decreased significantly during winter haze year. The shoot biomass and N uptake at the rosette stage accounted for only 9.6% and 26.6% of the total growth period in winter haze year, while 24.4% and 70.5% in normal year, respectively. However, in winter haze year, as the top dressing of N application increasing after the rosette stage, shoot biomass increased gradually. In order to achieve the target yield of 2.5 t ha-1, after suffering winter haze, it is necessary to apply additional 73.1 kg N ha-1. In conclusion, the haze climate reduced the radiation intensity and stability, leading to a decline in photosynthetic productivity in winter oilseed rape. Applying higher N fertilizer after winter haze can compensate the negative influence and ensure rapeseed yield.


Asunto(s)
Biomasa , Brassica napus/crecimiento & desarrollo , Fertilizantes , Nitrógeno , Fotosíntesis/efectos de los fármacos , Estaciones del Año , Tiempo (Meteorología) , Nitrógeno/metabolismo , Nitrógeno/farmacología
15.
Sci Rep ; 10(1): 3917, 2020 03 03.
Artículo en Inglés | MEDLINE | ID: mdl-32127596

RESUMEN

Nitrogenous fertilizers have nearly doubled global grain yields, but have also increased losses of reactive N to the environment. Current public investments to improve soil health seek to balance productivity and environmental considerations. However, data integrating soil biological health and crop N response to date is insufficient to reliably drive conservation policy and inform management. Here we used multilevel structural equation modeling and N fertilizer rate trials to show that biologically healthier soils produce greater corn yields per unit of fertilizer. We found the effect of soil biological health on corn yield was 18% the magnitude of N fertilization, Moreover, we found this effect was consistent for edaphic and climatic conditions representative of 52% of the rainfed acreage in the Corn Belt (as determined using technological extrapolation domains). While N fertilization also plays a role in building or maintaining soil biological health, soil biological health metrics offer limited a priori information on a site's responsiveness to N fertilizer applications. Thus, increases in soil biological health can increase corn yields for a given unit of N fertilizer, but cannot completely replace mineral N fertilization in these systems. Our results illustrate the potential for gains in productivity through investment in soil biological health, independent of increases in mineral N fertilizer use.


Asunto(s)
Fertilizantes/análisis , Nitrógeno/farmacología , Suelo/química , Zea mays/efectos de los fármacos , Zea mays/crecimiento & desarrollo
16.
Proc Natl Acad Sci U S A ; 117(14): 7719-7728, 2020 04 07.
Artículo en Inglés | MEDLINE | ID: mdl-32213582

RESUMEN

Chitin is the most abundant renewable nitrogenous material on earth and is accessible to humans in the form of crustacean shell waste. Such waste has been severely underutilized, resulting in both resource wastage and disposal issues. Upcycling chitin-containing waste into value-added products is an attractive solution. However, the direct conversion of crustacean shell waste-derived chitin into a wide spectrum of nitrogen-containing chemicals (NCCs) is challenging via conventional catalytic processes. To address this challenge, in this study, we developed an integrated biorefinery process to upgrade shell waste-derived chitin into two aromatic NCCs that currently cannot be synthesized from chitin via any chemical process (tyrosine and l-DOPA). The process involves a pretreatment of chitin-containing shell waste and an enzymatic/fermentative bioprocess using metabolically engineered Escherichia coli The pretreatment step achieved an almost 100% recovery and partial depolymerization of chitin from shrimp shell waste (SSW), thereby offering water-soluble chitin hydrolysates for the downstream microbial process under mild conditions. The engineered E. coli strains produced 0.91 g/L tyrosine or 0.41 g/L l-DOPA from 22.5 g/L unpurified SSW-derived chitin hydrolysates, demonstrating the feasibility of upcycling renewable chitin-containing waste into value-added NCCs via this integrated biorefinery, which bypassed the Haber-Bosch process in providing a nitrogen source.


Asunto(s)
Quitina/química , Nitrógeno/química , Residuos/análisis , Acetilglucosamina/metabolismo , Animales , Carbono/farmacología , Quitosano/química , Crustáceos , Escherichia coli/genética , Ingeniería Genética , Glucosa/metabolismo , Hidrólisis , Levodopa/metabolismo , Minerales/química , Nitrógeno/farmacología , Polimerizacion , Tirosina/metabolismo
17.
Sci Rep ; 10(1): 3305, 2020 02 24.
Artículo en Inglés | MEDLINE | ID: mdl-32094371

RESUMEN

Excessive nitrogen (N) input and irrigation exacerbate N leaching in winter wheat production in the North China Plain (NCP). To explore the optimal N for better N remobilization and higher N utilization of wheat under water-saving irrigation will be conductive to less environmental contamination. A field experiment was conducted at 300 (N300), 240 (N240), 180 (N180), and 0 (N0) kg N ha-1 of N application under supplemental irrigation (SI) that brought the relative soil water content (RSWC) to 70% at jointing and 65% at anthesis. Compared with N0, N180 improved the free amino acid content in the flag leaf and grain after anthesis, dry matter and plant N accumulation at maturity, N translocation amount of vegetable organs and its contribution to grain from anthesis to maturity. Compared to N240 and N300, N180 increased the N translocation efficiency of vegetable organs, and reduced the soil NO3-N residue in the 60-180 cm soil layer, which contributing to no significant reduction in grain yield and grain protein yield, but higher grain N recovery efficiency (GREN), N recovery efficiency (REN), and N partial factor productivity (PFPN). Positive relationships were found between leaf N translocation efficiency and grain yield, grain protein yield, PFPN, GREN, and REN. Therefore, N180 is appropriate to obtain a steady grain yield over 7.5 t ha-1 for at least 2 years under SI based on RSWC in the NCP.


Asunto(s)
Riego Agrícola , Nitrógeno/farmacología , Triticum/fisiología , Aminoácidos/análisis , Biomasa , China , Nitratos/metabolismo , Especificidad de Órganos/efectos de los fármacos , Hojas de la Planta/química , Suelo/química , Triticum/efectos de los fármacos , Triticum/crecimiento & desarrollo
18.
Sci Rep ; 10(1): 2918, 2020 02 19.
Artículo en Inglés | MEDLINE | ID: mdl-32075995

RESUMEN

Microbial flocculant (MBF), an environmentally friendly water treatment agent, can be widely used in various water treatments. However, its use is limited by low yield and high cost. This problem can be solved by clarifying its biosynthesis mechanism and regulating it. Paenibacillus shenyangensis A9, a flocculant-producing bacterium, was used to produce polysaccharide-type MBFA9 by regulating the nitrogen source (nitrogen adequacy/nitrogen deficiency). In this study, RNA-Seq high-throughput sequencing technology and bioinformatic approaches were used to investigate the fermentation and biosynthesis of polysaccharide-type MBFA9 by regulating the nitrogen source (high nitrogen/low nitrogen) in the flocculant-producing bacteria Paenibacillus shenyangensis A9. Differentially expressed genes, functional clustering, and functional annotation of key genes were assessed. Then the MBFA9 biosynthesis and metabolic pathway were reconstructed. Our results showed that when cultured under different nitrogen conditions, bacterial strain A9 had a greater ability to synthesize polysaccharide-type MBFA9 under low nitrogen compared to high nitrogen conditions, with the yield of MBFA9 reaching 4.2 g/L at 36 h of cultivation. The quality of transcriptome sequencing data was reliable, with a matching rate of 85.38% and 85.48% when L36/H36 was mapped to the reference genome. The total expressed genes detected were 4719 and 4730, with 265 differentially expressed genes. The differentially expressed genes were classified into 3 categories: molecular function (MF), cell component (CC), and biological process (BP), and can be further divided into 22 subcategories. There were 192 upregulated genes and 73 downregulated genes, with upregulation being predominant under low nitrogen. UDP-Gal, UDP-Glc, UDP-GlcA, and UDP-GlcNAc, which are in the polysaccharide metabolic pathway, could all be used as precursors for MBFA9 biosynthesis, and murA, wecB, pgm, galU/galF, fcl, gmd, and glgC were the main functional genes capable of affecting the growth of bacteria and the biosynthesis of MBF. Results from this study provide evidence that high-level expression of key genes in MBFA9 biosynthesis, regulation, and control can achieve MBFA9 directional synthesis for large-scale applications.


Asunto(s)
Perfilación de la Expresión Génica , Nitrógeno/farmacología , Paenibacillus/química , Paenibacillus/genética , Polisacáridos/farmacología , Vías Biosintéticas/efectos de los fármacos , Vías Biosintéticas/genética , Carbono/farmacología , Floculación , Regulación Bacteriana de la Expresión Génica/efectos de los fármacos , Ontología de Genes , Genes Bacterianos , Paenibacillus/efectos de los fármacos , Paenibacillus/crecimiento & desarrollo
19.
mBio ; 11(1)2020 02 11.
Artículo en Inglés | MEDLINE | ID: mdl-32047133

RESUMEN

Bacterial persisters exhibit noninherited antibiotic tolerance and are linked to the recalcitrance of bacterial infections. It is very urgent but also challenging to develop antipersister strategies. Here, we report that 10-s freezing with liquid nitrogen dramatically enhances the bactericidal action of aminoglycoside antibiotics by 2 to 6 orders of magnitude against many Gram-negative pathogens, with weaker potentiation effects on Gram-positive bacteria. In particular, antibiotic-tolerant Escherichia coli and Pseudomonas aeruginosa persisters-which were prepared by treating exponential-phase cells with ampicillin, ofloxacin, the protonophore cyanide m-chlorophenyl hydrazone (CCCP), or bacteriostatic antibiotics-can be effectively killed. We demonstrated, as a proof of concept, that freezing potentiated the aminoglycosides' killing of P. aeruginosa persisters in a mouse acute skin wound model. Mechanistically, freezing dramatically increased the bacterial uptake of aminoglycosides regardless of the presence of CCCP, indicating that the effects are independent of the proton motive force (PMF). In line with these results, we found that the effects were linked to freezing-induced cell membrane damage and were attributable, at least partly, to the mechanosensitive ion channel MscL, which was able to directly mediate such freezing-enhanced aminoglycoside uptake. In view of these results, we propose that the freezing-induced aminoglycoside potentiation is achieved by freezing-induced cell membrane destabilization, which, in turn, activates the MscL channel, which is able to effectively take up aminoglycosides in a PMF-independent manner. Our work may pave the way for the development of antipersister strategies that utilize the same mechanism as freezing but do so without causing any injury to animal cells.IMPORTANCE Antibiotics have long been used to successfully kill bacterial pathogens, but antibiotic resistance/tolerance usually has led to the failure of antibiotic therapy, and it has become a severe threat to human health. How to improve the efficacy of existing antibiotics is of importance for combating antibiotic-resistant/tolerant pathogens. Here, we report that 10-s rapid freezing with liquid nitrogen dramatically enhanced the bactericidal action of aminoglycoside antibiotics by 2 to 6 orders of magnitude against many bacterial pathogens in vitro and also in a mouse skin wound model. In particular, such combined treatment was able to effectively kill persister cells of Escherichia coli and Pseudomonas aeruginosa, which are per se tolerant of conventional treatment with bactericidal antibiotics for several hours. We also demonstrated that freezing-induced aminoglycoside potentiation was apparently linked to freezing-induced cell membrane damage that may have activated the mechanosensitive ion channel MscL, which, in turn, was able to effectively uptake aminoglycoside antibiotics in a proton motive force-independent manner. Our report sheds light on the development of a new strategy against bacterial pathogens by combining existing antibiotics with a conventional physical treatment or with MscL agonists.


Asunto(s)
Aminoglicósidos/farmacología , Antibacterianos/farmacología , Bacterias/efectos de los fármacos , Congelación , Aminoglicósidos/química , Animales , Bacterias/crecimiento & desarrollo , Biopelículas/efectos de los fármacos , Escherichia coli/efectos de los fármacos , Proteínas de Escherichia coli/metabolismo , Canales Iónicos/metabolismo , Masculino , Ratones , Ratones Endogámicos ICR , Pruebas de Sensibilidad Microbiana , Nitrógeno/farmacología , Fuerza Protón-Motriz , Pseudomonas aeruginosa/efectos de los fármacos , Piel/efectos de los fármacos , Piel/microbiología
20.
Nat Cell Biol ; 22(2): 159-166, 2020 02.
Artículo en Inglés | MEDLINE | ID: mdl-32029894

RESUMEN

Nuclear pore complexes (NPCs) are very large proteinaceous assemblies that consist of more than 500 individual proteins1,2. NPCs are essential for nucleocytoplasmic transport of different cellular components, and disruption of the integrity of NPCs has been linked to aging, cancer and neurodegenerative diseases3-7. However, the mechanism by which membrane-embedded NPCs are turned over is currently unknown. Here we show that, after nitrogen starvation or genetic interference with the architecture of NPCs, nucleoporins are rapidly degraded in the budding yeast Saccharomyces cerevisiae. We demonstrate that NPC turnover involves vacuolar proteases and the core autophagy machinery. Autophagic degradation is mediated by the cytoplasmically exposed Nup159, which serves as intrinsic cargo receptor and directly binds to the autophagy marker protein Atg8. Autophagic degradation of NPCs is therefore inducible, enabling the removal of individual NPCs from the nuclear envelope.


Asunto(s)
Familia de las Proteínas 8 Relacionadas con la Autofagia/genética , Autofagia/genética , Regulación Fúngica de la Expresión Génica , Complejos Multiproteicos/genética , Proteínas de Complejo Poro Nuclear/genética , Proteínas de Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/genética , Transporte Activo de Núcleo Celular/efectos de los fármacos , Secuencia de Aminoácidos , Autofagia/efectos de los fármacos , Familia de las Proteínas 8 Relacionadas con la Autofagia/metabolismo , Citoplasma/metabolismo , Glucosa/farmacología , Complejos Multiproteicos/metabolismo , Nitrógeno/farmacología , Poro Nuclear/metabolismo , Proteínas de Complejo Poro Nuclear/metabolismo , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Proteolisis/efectos de los fármacos , Saccharomyces cerevisiae/efectos de los fármacos , Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/ultraestructura , Proteínas de Saccharomyces cerevisiae/metabolismo , Sirolimus/farmacología
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