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1.
Moving beyond inclusion: Methodological considerations for the menstrual cycle and menopause in research evaluating effects of dietary nitrate on vascular function.
Baranauskas, MN, Freemas, JA, Tan, R, Carter, SJ
Nitric oxide : biology and chemistry. 2022;:39-48
Abstract
Recent reports have acknowledged the underrepresentation of women in the field of dietary nitrate (NO3-) research. Undoubtedly, greater participation from women is warranted to clarify potential sex differences in the responses to dietary NO3- interventions. However, careful consideration for the effects of sex hormones - principally 17β-estradiol - on endogenous nitric oxide (NO) synthesis and dietary NO3- reductase capacity is necessary for improved interpretation and reproducibility of such investigations. From available literature, we present a narrative review describing how hormonal variations across the menstrual cycle, as well as with menopause, may impact NO biosynthesis catalyzed by NO synthase enzymes and NO3- reduction via the enterosalivary pathway. In doing so, we address methodological considerations related to the menstrual cycle and hormonal contraceptive use relevant for the inclusion of premenopausal women along with factors to consider when testing postmenopausal women. Adherence to such methodological practices may explicate the utility of dietary NO3- supplementation as a means to improve vascular function among women across the lifespan.
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2.
Aerosol microphysics and chemistry reveal the COVID19 lockdown impact on urban air quality.
Eleftheriadis, K, Gini, MI, Diapouli, E, Vratolis, S, Vasilatou, V, Fetfatzis, P, Manousakas, MI
Scientific reports. 2021;(1):14477
Abstract
Air quality in urban areas and megacities is dependent on emissions, physicochemical process and atmospheric conditions in a complex manner. The impact on air quality metrics of the COVID-19 lockdown measures was evaluated during two periods in Athens, Greece. The first period involved stoppage of educational and recreational activities and the second severe restrictions to all but necessary transport and workplace activities. Fresh traffic emissions and their aerosol products in terms of ultrafine nuclei particles and nitrates showed the most significant reduction especially during the 2nd period (40-50%). Carbonaceous aerosol both from fossil fuel emissions and biomass burning, as well as aging ultrafine and accumulation mode particles showed an increase of 10-20% of average before showing a decline (5 to 30%). It is found that removal of small nuclei and Aitken modes increased growth rates and migration of condensable species to larger particles maintaining aerosol volume.
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3.
Calcium signaling networks mediate nitrate sensing and responses in Arabidopsis.
Liu, L, Gao, H, Li, S, Han, Z, Li, B
Plant signaling & behavior. 2021;(10):1938441
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Abstract
Nitrate signaling integrates and coordinates the expression of a wide range of genes, metabolic pathways and ultimately, plant growth and development. Calcium signaling is proved to be involved in the primary nitrate response pathway. However, it is much less understood how calcium signaling mediates nitrate sensing and responses from the extracellular space to cytoplasm, then to the nucleus. In this review, we describe how transceptor-channel complex (cyclic nucleotide-gated channel protein 15 interacting with nitrate transceptor, CNGC15-NRT1.1), calcineurin B-like proteins (CBLs, CBL1, CBL9), CBL-interacting protein kinases (CIPKs), phospholipase C (PLC) and calcium-dependent protein kinases (CDPKs, also CPKs), acting as key players, complete a potential backbone of the nitrate-signaling pathway, from the plasma membrane to the nucleus. NRT1.1 together with CBL1/9-CIPK23 and CBL-CIPK8 links the NO3- signaling to cytoplasmic and nuclear regulators and triggers downstream NO3- responses. PLCs and inositol 1, 4, 5-triphosphate (IP3) connect NO3- signaling and cytoplasmic Ca2+ signature. CPK10/30/32 fill the gap between NRT1.1 and NIN-like protein (NLP) transcription factors. The arabidopsis nitrate regulated1 (ANR1) is induced from the endosome by the Ca2+-CPKs-NLPs signaling pathway activated by the unphosphorylated form of NRT1.1 (NRT1.1 T101A) at high nitrate condition. Understanding how calcium signaling interconnects the upstream nitrate sensor complex with downstream multiple sensors of the nitrate-signaling pathway is key to completing the nutrient-growth regulatory networks.
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4.
Nitrate- and Nitrite-Sensing Histidine Kinases: Function, Structure, and Natural Diversity.
Gushchin, I, Aleksenko, VA, Orekhov, P, Goncharov, IM, Nazarenko, VV, Semenov, O, Remeeva, A, Gordeliy, V
International journal of molecular sciences. 2021;(11)
Abstract
Under anaerobic conditions, bacteria may utilize nitrates and nitrites as electron acceptors. Sensitivity to nitrous compounds is achieved via several mechanisms, some of which rely on sensor histidine kinases (HKs). The best studied nitrate- and nitrite-sensing HKs (NSHKs) are NarQ and NarX from Escherichia coli. Here, we review the function of NSHKs, analyze their natural diversity, and describe the available structural information. In particular, we show that around 6000 different NSHK sequences forming several distinct clusters may now be found in genomic databases, comprising mostly the genes from Beta- and Gammaproteobacteria as well as from Bacteroidetes and Chloroflexi, including those from anaerobic ammonia oxidation (annamox) communities. We show that the architecture of NSHKs is mostly conserved, although proteins from Bacteroidetes lack the HAMP and GAF-like domains yet sometimes have PAS. We reconcile the variation of NSHK sequences with atomistic models and pinpoint the structural elements important for signal transduction from the sensor domain to the catalytic module over the transmembrane and cytoplasmic regions spanning more than 200 Å.
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Effects of Nitrate Supplementation on Exercise Performance in Humans: A Narrative Review.
Macuh, M, Knap, B
Nutrients. 2021;(9)
Abstract
Nitrates have become increasingly popular for their potential role as an ergogenic aid. The purpose of this article was to review the current scientific evidence of nitrate supplementation on human performance. The current recommendation of nitrate supplementation is discussed, as well as possible health complications associated with nitrate intake for athletes, and dietary strategies of covering nitrate needs through sufficient intake of nitrate-rich foods alone are presented. Pubmed, Scopus, and Web of Science were searched for articles on the effects of nitrate supplementation in humans. Nitrates are an effective ergogenic aid when taken acutely or chronically in the range of ~5-16.8 mmol (~300-1041 mg) 2-3 h before exercise and primarily in the case of exercise duration of ~10-17 min in less trained individuals (VO2max < 65 mL/kg/min). Nitrate needs are most likely meet by ingesting approximately 250-500 g of leafy and root vegetables per day; however, dietary supplements might represent a more convenient and accurate way of covering an athlete's nitrate needs. Athletes should refrain from mouthwash usage when nitrate supplementation benefits are desired. Future research should focus on the potential beneficial effects of nitrate supplementation on brain function, possible negative impacts of chronic nitrate supplementation through different nitrate sources, and the effectiveness of nitrate supplementation on strength and high-intensity intermittent exercise.
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6.
Nitrate Respiration in Thermus thermophilus NAR1: from Horizontal Gene Transfer to Internal Evolution.
Sánchez-Costa, M, Blesa, A, Berenguer, J
Genes. 2020;(11)
Abstract
Genes coding for enzymes of the denitrification pathway appear randomly distributed among isolates of the ancestral genus Thermus, but only in few strains of the species Thermus thermophilus has the pathway been studied to a certain detail. Here, we review the enzymes involved in this pathway present in T. thermophilus NAR1, a strain extensively employed as a model for nitrate respiration, in the light of its full sequence recently assembled through a combination of PacBio and Illumina technologies in order to counteract the systematic errors introduced by the former technique. The genome of this strain is divided in four replicons, a chromosome of 2,021,843 bp, two megaplasmids of 370,865 and 77,135 bp and a small plasmid of 9799 pb. Nitrate respiration is encoded in the largest megaplasmid, pTTHNP4, within a region that includes operons for O2 and nitrate sensory systems, a nitrate reductase, nitrate and nitrite transporters and a nitrate specific NADH dehydrogenase, in addition to multiple insertion sequences (IS), suggesting its mobility-prone nature. Despite nitrite is the final product of nitrate respiration in this strain, the megaplasmid encodes two putative nitrite reductases of the cd1 and Cu-containing types, apparently inactivated by IS. No nitric oxide reductase genes have been found within this region, although the NorR sensory gene, needed for its expression, is found near the inactive nitrite respiration system. These data clearly support that partial denitrification in this strain is the consequence of recent deletions and IS insertions in genes involved in nitrite respiration. Based on these data, the capability of this strain to transfer or acquire denitrification clusters by horizontal gene transfer is discussed.
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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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Signalling Overlaps between Nitrate and Auxin in Regulation of The Root System Architecture: Insights from the Arabidopsis thaliana.
Asim, M, Ullah, Z, Oluwaseun, A, Wang, Q, Liu, H
International journal of molecular sciences. 2020;(8)
Abstract
Nitrate (NO3-) and auxin are key regulators of root growth and development, modulating the signalling cascades in auxin-induced lateral root formation. Auxin biosynthesis, transport, and transduction are significantly altered by nitrate. A decrease in nitrate (NO3-) supply tends to promote auxin translocation from shoots to roots and vice-versa. This nitrate mediated auxin biosynthesis regulating lateral roots growth is induced by the nitrate transporters and its downstream transcription factors. Most nitrate responsive genes (short-term and long-term) are involved in signalling overlap between nitrate and auxin, thereby inducing lateral roots initiation, emergence, and development. Moreover, in the auxin signalling pathway, the varying nitrate supply regulates lateral roots development by modulating the auxin accumulation in the roots. Here, we focus on the roles of nitrate responsive genes in mediating auxin biosynthesis in Arabidopsis root, and the mechanism involved in the transport of auxin at different nitrate levels. In addition, this review also provides an insight into the significance of nitrate responsive regulatory module and their downstream transcription factors in root system architecture in the model plant Arabidopsis thaliana.
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How does nitrate regulate plant senescence?
Wen, B, Xiao, W, Mu, Q, Li, D, Chen, X, Wu, H, Li, L, Peng, F
Plant physiology and biochemistry : PPB. 2020;:60-69
Abstract
Nitrogen is an essential macronutrient for plant growth and development and plays an important role in the whole life process of plants. Nitrogen is an important component of amino acids, chlorophyll, plant hormones and secondary metabolites. Nitrogen deficiency leads to early senescence in plants, which is accompanied by changes in gene expression, metabolism, growth, development, and physiological and biochemical traits, which ensures efficient nitrogen recycling and enhances the plant's tolerance to low nitrogen. Therefore, it is very important to understand the adaptation mechanisms of plants under nitrogen deficiency for the efficient utilization of nitrogen and gene regulation. With the popularization of molecular biology, bioinformatics and transgenic technology, the metabolic pathways of nitrogen-deficient plants have been verified, and important progress has been made. However, how the responses of plants to nitrogen deficiency affect the biological processes of the plants is not well understood. The current research also cannot completely explain how the metabolic pathways identified show other reactions or phenotypes through interactions or cascades after nitrogen inhibition. Nitrate is the main form of nitrogen absorption. In this review, we discuss the role of nitrate in plant senescence. Understanding how nitrate inhibition affects nitrate absorption, transport, and assimilation; chlorophyll synthesis; photosynthesis; anthocyanin synthesis; and plant hormone synthesis is key to sustainable agriculture.
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Mitochondrial NAD(P)H oxidation pathways and nitrate/ammonium redox balancing in plants.
Rasmusson, AG, Escobar, MA, Hao, M, Podgórska, A, Szal, B
Mitochondrion. 2020;:158-165
Abstract
Plant mitochondrial oxidative phosphorylation is characterised by alternative electron transport pathways with different energetic efficiencies, allowing turnover of cellular redox compounds like NAD(P)H. These electron transport chain pathways are profoundly affected by soil nitrogen availability, most commonly as oxidized nitrate (NO3-) and/or reduced ammonium (NH4+). The bioenergetic strategies involved in assimilating different N sources can alter redox homeostasis and antioxidant systems in different cellular compartments, including the mitochondria and the cell wall. Conversely, changes in mitochondrial redox systems can affect plant responses to N. This review explores the integration between N assimilation, mitochondrial redox metabolism, and apoplast metabolism.