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1.
Nitrogen Balance During Venovenous Extracorporeal Membrane Oxygenation Support: Preliminary Results of a Prospective, Observational Study.
Pelekhaty, S, Galvagno, SM, Hochberg, E, Herr, DL, Lantry, JH, Kon, ZN, Deatrick, KB, Menaker, J
JPEN. Journal of parenteral and enteral nutrition. 2020;(3):548-553
Abstract
BACKGROUND Current literature is insufficient to support specific guidelines for estimating nutrition needs during extracorporeal membrane oxygenation (ECMO). The purpose of this single-center observational study was to investigate protein catabolism during venovenous (VV) ECMO support and assess whether current nutrition recommendations were adequate. METHODS All patients admitted to the Lung Rescue Unit between November 2016 and June 2017 were screened for eligibility. Patients with a documented nitrogen balance (NB) study were included in the data set. NB results were excluded for a change in blood urea nitrogen ≥10 mg/dL during the urine collection or unquantified nitrogen losses. Demographics, ECMO-specific data, NB, nutrition prescription, and infusion were recorded in a prospective, observational manner. RESULTS After exclusions, 25 NB results in 16 patients were included for analysis. Nonobese (body mass index [BMI] ˂ 30 kg/m2 ) and obese (BMI ≥ 30 kg/m2 ) patients received 85% and 84% of their prescribed protein, respectively. Nonobese patients had a mean NB of -1.7 ± 5.7, whereas obese patients had a mean NB of -11.5 ± 9.6. Obese patients displayed significantly higher urine urea nitrogen (26.7 ± 7.7 vs 13.5 ± 4.3; P = .00004). CONCLUSIONS These preliminary findings suggest that current guidelines for estimating protein needs in critically ill patients may be adequate for nonobese patients receiving VV ECMO. However, current protein recommendations for critically ill obese patients may not be adequate during VV ECMO support, possibly related to significantly higher rates of catabolism. Future studies with a larger cohort of patients are needed to confirm these results.
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2.
Improving nitrogen uptake efficiency by chitin nanofiber promotes growth in tomato.
Egusa, M, Matsukawa, S, Miura, C, Nakatani, S, Yamada, J, Endo, T, Ifuku, S, Kaminaka, H
International journal of biological macromolecules. 2020;:1322-1331
Abstract
Chitin, an N-acetyl-D-glucosamine polymer, has been known to enhance plant growth. However, this polysaccharide has not been used extensively in experimental work or agriculture practices because its hydrophobic nature makes it difficult to handle. Chitin nanofiber (CNF), which disperses well in water, can feasibly be used to evaluate the effect of chitin on the promotion of plant growth. In this study, we analysed the contents of inorganic elements and global gene expression to obtain an overview of the growth-promoting action of chitins in plants. Significant increases in the biomass of aerial parts and concentration of chlorophyll following treatment with CNF or short-chain chitin oligomers were observed in tomatoes that were hydroponically cultivated under ultralow nutrient concentrations. The results of the quantification of inorganic elements demonstrated that concentrations of nitrogen and carbon significantly increased in whole tomato plant under chitin treatment. Transcriptome analysis of CNF-treated tomatoes by RNA sequencing showed that the expression levels of genes related to nitrogen acquisition and assimilation, nutrient allocation and photosynthesis were altered. These results indicate that the growth-promoting action of chitin treatment is caused by an improvement in nitrogen uptake efficiency and that CNF could be a useful material for nutrient management in tomato production.
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3.
Emerging concepts of potassium homeostasis in plants.
Srivastava, AK, Shankar, A, Nalini Chandran, AK, Sharma, M, Jung, KH, Suprasanna, P, Pandey, GK
Journal of experimental botany. 2020;(2):608-619
Abstract
Potassium (K+) is an essential cation in all organisms that influences crop production and ecosystem stability. Although most soils are rich in K minerals, relatively little K+ is present in forms that are available to plants. Moreover, leaching and run-off from the upper soil layers contribute to K+ deficiencies in agricultural soils. Hence, the demand for K fertilizer is increasing worldwide. K+ regulates multiple processes in cells and organs, with K+ deficiency resulting in decreased plant growth and productivity. Here, we discuss the complexity of the reactive oxygen species-calcium-hormone signalling network that is responsible for the sensing of K+ deficiency in plants, together with genetic approaches using K+ transporters that have been used to increase K+ use efficiency (KUE) in plants, particularly under environmental stress conditions such as salinity and heavy metal contamination. Publicly available rice transcriptome data are used to demonstrate the two-way relationship between K+ and nitrogen nutrition, highlighting how each nutrient can regulate the uptake and root to shoot translocation of the other. Future research directions are discussed in terms of this relationship, as well as prospects for molecular approaches for the generation of improved varieties and the implementation of new agronomic practices. An increased knowledge of the systems that sense and take up K+, and their regulation, will not only improve current understanding of plant K+ homeostasis but also facilitate new research and the implementation of measures to improve plant KUE for sustainable food production.
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4.
Disentangling the genetic bases of Saccharomyces cerevisiae nitrogen consumption and adaptation to low nitrogen environments in wine fermentation.
Kessi-Pérez, EI, Molinet, J, Martínez, C
Biological research. 2020;(1):2
Abstract
The budding yeast Saccharomyces cerevisiae has been considered for more than 20 years as a premier model organism for biological sciences, also being the main microorganism used in wide industrial applications, like alcoholic fermentation in the winemaking process. Grape juice is a challenging environment for S. cerevisiae, with nitrogen deficiencies impairing fermentation rate and yeast biomass production, causing stuck or sluggish fermentations, thus generating sizeable economic losses for wine industry. In the present review, we summarize some recent efforts in the search of causative genes that account for yeast adaptation to low nitrogen environments, specially focused in wine fermentation conditions. We start presenting a brief perspective of yeast nitrogen utilization under wine fermentative conditions, highlighting yeast preference for some nitrogen sources above others. Then, we give an outlook of S. cerevisiae genetic diversity studies, paying special attention to efforts in genome sequencing for population structure determination and presenting QTL mapping as a powerful tool for phenotype-genotype correlations. Finally, we do a recapitulation of S. cerevisiae natural diversity related to low nitrogen adaptation, specially showing how different studies have left in evidence the central role of the TORC1 signalling pathway in nitrogen utilization and positioned wild S. cerevisiae strains as a reservoir of beneficial alleles with potential industrial applications (e.g. improvement of industrial yeasts for wine production). More studies focused in disentangling the genetic bases of S. cerevisiae adaptation in wine fermentation will be key to determine the domestication effects over low nitrogen adaptation, as well as to definitely proof that wild S. cerevisiae strains have potential genetic determinants for better adaptation to low nitrogen conditions.
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5.
Nitrate in 2020: Thirty Years from Transport to Signaling Networks.
Vidal, EA, Alvarez, JM, Araus, V, Riveras, E, Brooks, MD, Krouk, G, Ruffel, S, Lejay, L, Crawford, NM, Coruzzi, GM, et al
The Plant cell. 2020;(7):2094-2119
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Abstract
Nitrogen (N) is an essential macronutrient for plants and a major limiting factor for plant growth and crop production. Nitrate is the main source of N available to plants in agricultural soils and in many natural environments. Sustaining agricultural productivity is of paramount importance in the current scenario of increasing world population, diversification of crop uses, and climate change. Plant productivity for major crops around the world, however, is still supported by excess application of N-rich fertilizers with detrimental economic and environmental impacts. Thus, understanding how plants regulate nitrate uptake and metabolism is key for developing new crops with enhanced N use efficiency and to cope with future world food demands. The study of plant responses to nitrate has gained considerable interest over the last 30 years. This review provides an overview of key findings in nitrate research, spanning biochemistry, molecular genetics, genomics, and systems biology. We discuss how we have reached our current view of nitrate transport, local and systemic nitrate sensing/signaling, and the regulatory networks underlying nitrate-controlled outputs in plants. We hope this summary will serve not only as a timeline and information repository but also as a baseline to define outstanding questions for future research.
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Nitrogen-phosphorus interplay: old story with molecular tale.
Hu, B, Chu, C
The New phytologist. 2020;(4):1455-1460
Abstract
Nitrogen (N) and phosphorus (P) are the two most abundant mineral nutrients used by plants, and are also the mostly widely used fertilizer elements driving crop yield improvement in agricultural production. The coordinated utilization of N and P is essential to maintain optimal plant growth and achieve maximal crop yield. The signaling pathways of N and P are generally studied separately, so our understanding of N-P interactions is very limited. A series of recent studies have revealed the critical components regulating N-P interactions in both Arabidopsis thaliana and rice (Oryza sativa), and have shed light on our in-depth understanding of the network integrating N and P signaling pathways. Here, we summarize recent progress on N-P interaction and propose possible working mechanisms integrating these N-P interactive regulation pathways. We further discuss future work that might reveal the N-P interactive regulation network in plants.
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Dynamics in plant roots and shoots minimize stress, save energy and maintain water and nutrient uptake.
Arsova, B, Foster, KJ, Shelden, MC, Bramley, H, Watt, M
The New phytologist. 2020;(3):1111-1119
Abstract
Plants are inherently dynamic. Dynamics minimize stress while enabling plants to flexibly acquire resources. Three examples are presented for plants tolerating saline soil: transport of sodium chloride (NaCl), water and macronutrients is nonuniform along a branched root; water and NaCl redistribute between shoot and soil at night-time; and ATP for salt exclusion is much lower in thinner branch roots than main roots, quantified using a biophysical model and geometry from anatomy. Noninvasive phenotyping and precision agriculture technologies can be used together to harness plant dynamics, but analytical methods are needed. A plant advancing in time through a soil and atmosphere space is proposed as a framework for dynamic data and their relationship to crop improvement.
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Development of a low-cost culture medium for the rapid production of plant growth-promoting Rhodopseudomonas palustris strain PS3.
Lo, KJ, Lee, SK, Liu, CT
PloS one. 2020;(7):e0236739
Abstract
Rhodopseudomonas palustris PS3 is one of the purple phototrophic non-sulfur bacteria (PNSB), which have plant growth-promoting effects on various plants. To expand the scale of PS3 fermentation in a time- and cost-effective fashion, the purpose of this work was to evaluate the use of low-cost materials as culture media and to optimize the culture conditions via response surface methodology. Corn steep liquor (CSL) and molasses were identified as potential materials to replace the nitrogen and carbon sources, respectively, in the conventional growth medium. The optimum culture conditions identified through central composite design were CSL, 39.41 mL/L; molasses, 32.35 g/L; temperature, 37.9°C; pH, 7.0; and DO 30%. Under the optimized conditions, the biomass yield reached 2.18 ± 0.01 g/L at 24 hours, which was 7.8-fold higher than that under the original medium (0.28 ± 0.01 g/L). The correlation between the predicted and experimental values of the model was over 98%, which verified the validity of the response models. Furthermore, we verified the effectiveness of the R. palustris PS3 inoculant grown under the newly developed culture conditions for plant growth promotion. This study provides a potential strategy for improving the fermentation of R. palustris PS3 in low-cost media for large-scale industrial production.
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Comparing Molecular Mechanisms in Solar NH3 Production and Relations with CO2 Reduction.
Mallamace, D, Papanikolaou, G, Perathoner, S, Centi, G, Lanzafame, P
International journal of molecular sciences. 2020;(1)
Abstract
Molecular mechanisms for N2 fixation (solar NH3) and CO2 conversion to C2+ products in enzymatic conversion (nitrogenase), electrocatalysis, metal complexes and plasma catalysis are analyzed and compared. It is evidenced that differently from what is present in thermal and plasma catalysis, the electrocatalytic path requires not only the direct coordination and hydrogenation of undissociated N2 molecules, but it is necessary to realize features present in the nitrogenase mechanism. There is the need for (i) a multi-electron and -proton simultaneous transfer, not as sequential steps, (ii) forming bridging metal hydride species, (iii) generating intermediates stabilized by bridging multiple metal atoms and (iv) the capability of the same sites to be effective both in N2 fixation and in COx reduction to C2+ products. Only iron oxide/hydroxide stabilized at defective sites of nanocarbons was found to have these features. This comparison of the molecular mechanisms in solar NH3 production and CO2 reduction is proposed to be a source of inspiration to develop the next generation electrocatalysts to address the challenging transition to future sustainable energy and chemistry beyond fossil fuels.
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Evaluation of efficient carbon, nitrogen sources, micro and macro nutrients for dextran production by Weissella cibaria CMGDEX3 by utilizing a modified multifactorial Placket-Burman statistical design.
Siddiqui, K, Fatima, S, Akhtar, J, Shoeb, E, Badar, U, Qureshi, FM
Pakistan journal of pharmaceutical sciences. 2020;(5(Supplementary)):2351-2353
Abstract
In the present study previously isolated Weissella cibaria CMG DEX3 capable of producing high molecular weight, water soluble dextran (Ahmed et al., 2012) is characterized for most efficient less expensive carbon, nitrogen sources, micro and macro nutrients by utilizing a multifactorial Placket-Burman statistical design for optimization of dextran production. A twelve run Plackett-Burman experimental model with slight modification was utilized to evaluate the impact of ten diverse nutrients on the production of dextran by the bacterial isolate Weissella cibaria CMG DEX3.