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Ceratium furcoides is a dinoflagellate that exhibits invasive behavior in aquatic ecosystems of South America and its presence alters local phytoplankton communities. It may coexist with Microcystis, together constituting a functional assemblage in temperate regions. However, their interaction in the subtropics is still unclear. In this study, 151 southern Brazilian municipalities were monitored between 2012 and 2022, aiming to understand whether both species co-occur and given their co-occurrence, how it progresses, as well as to investigate which variables drive the observed patterns. The results indicated that both present similar spatial preferences, occurring and blooming in the same hydrographic regions. Distribution models showed that they responded similarly to the same predictors, the most important being temperature (seasonality, annual range, and mean diurnal range), in addition to flow accumulation. Despite this, co-occurrence analysis showed high segregation at all scales, driven by shifts in precipitation and temperature provided by El Niño and La Niña, associated with nutritional increase. In the subtropics, C. furcoides was dominant, in terms of frequency and abundance, with organic matter being key for its development and dominance; in contrast, Microcystis was sensitive to disturbances, with sporadic blooms supported by nitrites and nitrates.

Organonitrates are important species in the atmosphere due to their impacts on NO.sub.x, HO.sub.x, and O.sub.3 budgets, and their potential to contribute to secondary organic aerosol (SOA) mass. This work presents a steady-state modelling approach to assess the impacts of changes in NO.sub.x and O.sub.3 concentrations on the organonitrates produced from isoprene oxidation. The diverse formation pathways to isoprene organonitrates dictate the responses of different groups of organonitrates to changes in O.sub.3 and NO.sub.x . For example, organonitrates predominantly formed from the OH-initiated oxidation of isoprene favour formation under lower-ozone and moderate-NO.sub.x concentrations, whereas organonitrates formed via daytime NO.sub.3 oxidation show the highest formation under high-O.sub.3 concentrations with little dependence on NO.sub.x concentrations. Investigating the response of total organonitrates reveals complex and nonlinear behaviour with implications that could inform expectations of changes to organonitrate concentrations as efforts are made to reduce NO.sub.x and O.sub.3 concentrations, including a region of NO.sub.x -O.sub.3 space where total organonitrate concentration is relatively insensitive to changes in NO.sub.x and O.sub.3 . These conclusions are further contextualised by estimating the volatility of the isoprene organonitrates revealing the potential for high concentrations of low-volatility species under high-ozone conditions.

C.sub.1 -C.sub.4 alkyl nitrates (RONO.sub.2) were measured concurrently at a mountain site, Tai Mo Shan (TMS), and an urban site, Tsuen Wan (TW), at the base of the same mountain in Hong Kong from September to November 2010. Although the levels of parent hydrocarbons were much lower at TMS (p  <  0.05), similar alkyl nitrate levels were found at both sites regardless of the elevation difference, suggesting various source contributions of alkyl nitrates at the two sites. Prior to using a positive matrix factorization (PMF) model, the data at TW were divided into \"meso\" and \"non-meso\" scenarios for the investigation of source apportionments with the influence of mesoscale circulation and regional transport, respectively. Secondary formation was the prominent contributor of alkyl nitrates in the meso scenario (60 ± 2 %, 60.2 ± 1.2 pptv), followed by biomass burning and oceanic emissions, while biomass burning and secondary formation made comparable contributions to alkyl nitrates in the non-meso scenario, highlighting the strong emissions of biomass burning in the inland Pearl River delta (PRD) region. In contrast to TW, the alkyl nitrate levels measured at TMS mainly resulted from the photooxidation of the parent hydrocarbons at TW during mesoscale circulation, i.e., valley breezes, corresponding to 52-86 % of the alkyl nitrate levels at TMS. Furthermore, regional transport from the inland PRD region made significant contributions to the levels of alkyl nitrates (∼  58-82 %) at TMS in the non-meso scenario, resulting in similar levels of alkyl nitrates observed at the two sites. The simulation of secondary formation pathways using a photochemical box model found that the reaction of alkyl peroxy radicals (RO.sub.2) with nitric oxide (NO) dominated the formation of RONO.sub.2 at both sites, and the formation of alkyl nitrates contributed negatively to O.sub.3 production, with average reduction rates of 4.1 and 4.7 pptv pptv.sup.-1 at TMS and TW, respectively.

Purpose Dietary nitrate supplementation increases nitric oxide (NO) bioavailability and reduces blood pressure (BP). Inter-individual differences in these responses are suspected but have not been investigated using robust designs, e.g., replicate crossover, and appropriate statistical models. We examined the within-individual consistency of the effects of dietary nitrate supplementation on NO biomarkers and BP, and quantified inter-individual response differences. Methods Fifteen healthy males visited the laboratory four times. On two visits, participants consumed 140 ml nitrate-rich beetroot juice (~ 14.0mmol nitrate) and, on the other two visits, they consumed 140 ml nitrate-depleted beetroot juice (~ 0.03mmol nitrate). Plasma nitrate and nitrite concentrations were measured 2.5 h post-supplementation. BP was measured pre- and 2.5 h post-supplementation. Between-replicate correlations were quantified for the placebo-adjusted post-supplementation plasma nitrate and nitrite concentrations and pre-to-post changes in BP. Within-participant linear mixed models and a meta-analytic approach estimated participant-by-condition treatment response variability. Results Nitrate-rich beetroot juice supplementation elevated plasma nitrate and nitrite concentrations and reduced systolic (mean:-7mmHg, 95%CI: -3 to -11mmHg) and diastolic (mean:-6mmHg, 95%CI: -2 to -9mmHg) BP versus placebo. The participant-by-condition interaction response variability from the mixed model was ± 7mmHg (95%CI: 3 to 9mmHg) for systolic BP and consistent with the treatment effect heterogeneity t = ± 7mmHg (95%CI: 5 to 12mmHg) derived from the meta-analytic approach. The between-replicate correlations were moderate-to-large for plasma nitrate, nitrite and systolic BP ( r  = 0.55 to 0.91). Conclusions The effects of dietary nitrate supplementation on NO biomarkers and systolic BP varied significantly from participant to participant. The causes of this inter-individual variation deserve further investigation. Trial registration: https://clinicaltrials.gov/study/NCT05514821 .

The indica and japonica rice ( Oryza sativa ) subspecies differ in nitrate (NO 3 − ) assimilation capacity and nitrogen (N) use efficiency (NUE). Here, we show that a major component of this difference is conferred by allelic variation at OsNR2 , a gene encoding a NADH/NADPH-dependent NO 3 − reductase (NR). Selection-driven allelic divergence has resulted in variant indica and japonica OsNR2 alleles encoding structurally distinct OsNR2 proteins, with indica OsNR2 exhibiting greater NR activity. Indica OsNR2 also promotes NO 3 − uptake via feed-forward interaction with OsNRT1.1B , a gene encoding a NO 3 − uptake transporter. These properties enable indica OsNR2 to confer increased effective tiller number, grain yield and NUE on japonica rice, effects enhanced by interaction with an additionally introgressed indica OsNRT1.1B allele. In consequence, indica OsNR2 provides an important breeding resource for the sustainable increases in japonica rice yields necessary for future global food security. Indica rice has higher nitrate assimilation and nitrogen use efficiency (NUE) than japonica rice, but the mechanism is unclear. Here, the authors reveal that the difference is partly due to allelic variation of a nitrate reductase encoding gene and this indica allele can increase yield potential and NUE.

Epidemiological studies suggest that green leafy vegetables, which are high in dietary nitrate, are protective against CVD such as stroke. High blood pressure (BP) is a major risk factor for stroke and inorganic nitrate has been shown to reduce BP. The objective of the present study was to test the hypothesis that diets containing high-nitrate (HN) vegetables would increase plasma nitrate and nitrite concentrations and reduce BP in healthy women. A randomized, crossover trial, where participants received HN vegetables (HN diet) or avoided HN vegetables (Control diet) for 1 week. Before and after each intervention, resting BP and plasma nitrate and nitrite concentrations were measured. University of Exeter, UK. Nineteen healthy women (mean age 20 (sd 2) years; mean BMI 22·5 (sd 3·8) kg/m2). The HN diet significantly increased plasma nitrate concentration (before HN diet: mean 24·4 (sd 5·6) µmol/l; after HN diet: mean 61·0 (sd 44·1) µmol/l, P<0·05) and plasma nitrite concentration (before HN diet: mean 98 (sd 91) nmol/l; after HN diet: mean 185 (sd 34) nmol/l, P<0·05). No significant change in plasma nitrate or nitrite concentration was observed after the Control diet. The HN diet significantly reduced resting systolic BP (before HN diet: mean 107 (sd 9) mmHg; after HN diet: mean 103 (sd 6) mmHg, P<0·05). No significant change in systolic BP was observed after the Control diet (before Control diet: mean 106 (sd 8) mmHg; after Control diet: mean 106 (sd 8) mmHg). Consumption of HN vegetables significantly increased plasma nitrate and nitrite concentrations and reduced BP in normotensive women.