Effect of 3-nitrooxypropanol on enteric methane emissions of feedlot cattle fed with a tempered barley-based diet with canola oil.

A dose-response experiment was designed to examine the effect of 3-nitrooxypropanol (3-NOP) on methane (CH4) emissions, rumen function and performance of feedlot cattle fed a tempered barley-based diet with canola oil. Twenty Angus steers of initial body weight (BW) of 356 ±â€…14.4 kg were allocated in a randomized complete block design. Initial BW was used as the blocking criterion. Cattle were housed in individual indoor pens for 112 d, including the first 21 d of adaptation followed by a 90-d finishing period when five different 3-NOP inclusion rates were compared: 0 mg/kg dry matter (DM; control), 50 mg/kg DM, 75 mg/kg DM, 100 mg/kg DM, and 125 mg/kg DM. Daily CH4 production was measured on day 7 (last day of starter diet), day 14 (last day of the first intermediate diet), and day 21 (last day of the second intermediate diet) of the adaptation period and on days 28, 49, 70, 91, and 112 of the finisher period using open circuit respiration chambers. Rumen digesta samples were collected from each steer on the day prior to chamber measurement postfeeding, and prefeeding on the day after the chamber measurement, for determination of rumen volatile fatty acids (VFA), ammonium-N, protozoa enumeration, pH, and reduction potential. Dry matter intake (DMI) was recorded daily and BW weekly. Data were analyzed in a mixed model including period, 3-NOP dose and their interaction as fixed effects, and block as a random effect. Our results demonstrated both a linear and quadratic (decreasing rate of change) effect on CH4 production (g/d) and CH4 yield (g/kg DMI) as 3-NOP dose increased (P < 0.01). The achieved mitigation for CH4 yield in our study ranged from approximately 65.5% up to 87.6% relative to control steers fed a finishing feedlot diet. Our results revealed that 3-NOP dose did not alter rumen fermentation parameters such as ammonium-N, VFA concentration nor VFA molar proportions. Although this experimental design was not focused on the effect of 3-NOP dose on feedlot performance, no negative effects of any 3-NOP dose were detected on animal production parameters. Ultimately, the knowledge on the CH4 suppression pattern of 3-NOP may facilitate sustainable pathways for the feedlot industry to lower its carbon footprint.

Livestock methane (CH4) is the main source of greenhouse gases (GHGs) in agriculture, contributing to 11.6% of global GHGs emissions from human-related activities. Therefore, mitigating CH4 emissions from ruminant animals is a great opportunity for meeting the current climate targets. In this experiment, increasing inclusion rates of a promising CH4-mitigating compound, 3-nitrooxypropanol (3-NOP, from 50 to 125 mg of 3-NOP/kg of dry matter [DM]), were added to a barley-based feedlot diet containing 25 ppm of monensin and 7% fat (DM-basis) and fed to Angus steers. Under these conditions, increasing inclusion rate of 3-NOP reduced both production and yield of CH4 by up to 90%. Rumen fermentation, feed intake, and average daily gain were not affected by the 3-NOP dose. Our results on the potential CH4 suppression of 3-NOP may assist the feedlot industry towards sustainability by lowering its GHG output.

Ecological Responses of Maize Rhizosphere to Antibiotics Entering the Agricultural System in an Area with High Arsenicals Geological Background.

Metal(loid)s can promote the spread and enrichment of antibiotic resistance in the environmental ecosystem through a co-selection effect. Little is known about the ecological effects of entering antibiotics into the environment with long-term metal(loid)s' resistance profiles. Here, cow manure containing oxytetracycline (OTC) or sulfadiazine (SA) at four concentrations (0 (as control), 1, 10, and 100 mg/kg) was loaded to a maize cropping system in an area with high a arsenicals geological background. Results showed that exogenous antibiotics entering significantly changed the nutrient conditions, such as the concentration of nitrate nitrogen, ammonium nitrogen, and available phosphorus in the maize rhizosphere soil, while total arsenic and metals did not display any differences in antibiotic treatments compared with control. Antibiotics exposure significantly influenced nitrate and nitrite reductase activities to reflect the inhibition of denitrification rates but did not affect the soil urease and acid phosphatase activities. OTC treatment also did not change soil dehydrogenase activities, while SA treatment posed promotion effects, showing a tendency to increase with exposure concentration. Both the tested antibiotics (OTC and SA) decreased the concentration of arsenite and arsenate in rhizosphere soil, but the inhibition effects of the former were higher than that of the latter. Moreover, antibiotic treatment impacted arsenite and arsenate levels in maize root tissue, with positive effects on arsenite and negative effects on arsenate. As a result, both OTC and SA treatments significantly increased bioconcentration factors and showed a tendency to first increase and then decrease with increasing concentration. In addition, the treatments decreased translocation capacity of arsenic from roots to shoots and showed a tendency to increase translocation factors with increasing concentration. Microbial communities with arsenic-resistance profiles may also be resistant to antibiotics entering.

Ammonium improved cell wall and cell membrane P reutilization and external P uptake in a putrescine and ethylene dependent pathway.

Ammonium promotes rice P uptake and reutilization better than nitrate, under P starvation conditions; however, the underlying mechanism remains unclear. In this study, ammonium treatment significantly increased putrescine and ethylene content in rice roots under P deficient conditions, by increasing the protein content of ornithine decarboxylase and 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase compared with nitrate treatment. Ammonium treatment increased rice root cell wall P release by increasing pectin content and pectin methyl esterase (PME) activity, increased rice shoot cell membrane P release by decreasing phosphorus-containing lipid components, and maintained internal P homeostasis by increasing OsPT2/6/8 expression compared with nitrate treatment. Ammonium also improved external P uptake by regulating root morphology and increased rice grain yield by increasing the panicle number compared with nitrate treatment. The application of putrescine and ethylene synthesis precursor ACC further improved the above process. Our results demonstrate for the first time that ammonium increases rice P acquisition, reutilization, and homeostasis, and rice grain yield, in a putrescine- and ethylene-dependent manner, better than nitrate, under P starvation conditions.

Mechanism of nonylphenol induced gastric inflammation through NF-κB/NLRP3 signaling pathway.

Studies have found that the intake of environmental endocrine disruptors was positively correlated with the occurrence of gastric diseases. The aim of this study was to determine whether nonylphenol (NP) exposure can induce gastric inflammation and whether its mechanism was related to NF-κB/NLRP3 signaling pathway. In vivo, male SD rats were randomly divided into 4 groups (12 rats/group): control group (corn oil), NP low (0.4 mg/kg), medium (4 mg/kg), and high (40 mg/kg) dose groups. After 33 weeks of NP chronic exposure, it was found pathological changes in gastric tissues, increase the release of inflammatory factors, and effects expressions of genes related to the NF-κB/NLRP3 signaling pathway. In vitro, the GES-1 cell experiments, which included four groups: control (0 µmol/L NP), L (2.5 µmol/L NP), M (40 µmol/L NP), and H (60 µmol/L NP), confirmed that NP increased the release of inflammatory factors in the cells, and up-regulated the expression of proteins related to NF-κB/NLRP3 signaling pathway. Furthermore, when pyrrolidinedithiocarbamate ammonium (PDTC) blocked the NF-κB signaling pathway, it was found that the expression of related proteins in the NF-κB/NLRP3 signaling pathway was decreased, and the release of inflammatory factors in GES-1 cells caused by NP was also attenuated. The results of this study indicated that NP can induce inflammation in the stomach in vivo and in vitro, and its mechanism was related to the NF-κB/NLRP3 signaling pathway. These findings provided a new perspective on the mechanism of inflammatory response induced by exposure to environmental endocrine disruptors. Also, these findings indicated that therapeutic strategies for the NF-κB/NLRP3 signaling pathway may be new methods to treat inflammatory diseases.

[Enhancing effects of chemical permeation enhancer propylene glycol and ultrasonic technology on transdermal permeation of Baimai Ointment].

This study aimed to improve the transdermal permeation quantity of Baimai Ointment by investigating the enhancing effects of physical and chemical permeation promoting methods on transdermal permeation of Baimai Ointment. The improved Franz diffusion cell method was used for in vitro transdermal experiment. The abdominal skin of mice was used, and the skin was treated with 3% propylene glycol in the chemical enhancement group. Ultrasonic technology was introduced in the physical enhancement group. The conditions of ultrasonic technology were optimized by single factor trial. Taking Q_(EF) and ER as the indexes of penetration promotion performance, the enhancing effects of the two methods were compared. The results showed that the promotion performance of 3% propylene glycol for ammonium glycyrrhizinate, nardosinone and curcumin of the chemical enhancement group were 1.74, 1.60, and 3.73 times higher than those of the blank group, respectively. The overall permeation efficiency of the Baimai Ointment was significantly improved. The comprehensive promoting effect on each component was curcumin>ammonium glycyrrhizinate>nardosinone. In the physical enhancement group, the penetration promoting effect of ultrasonic power 1.0 W was better than that of 2.0 W and 0.5 W, ultrasonic time 5 min was better than 3 min and 8 min, and the ultrasonic frequency 1 MHz was better than 3 MHz. Therefore, the optimal ultrasonic condition was 1.0 W-5 min-1 MHz. Under this condition, in terms of the transdermal permeation for ammonium glycyrrhizinate, the Q_(EF) and ER of the ultrasonic technology were better than those of 3% propylene glycol. In terms of the transdermal permeation for nardosinone and curcumin, the QEF and ER of 3% propylene glycol were better than those of the ultrasonic technology. Therefore, 3% propylene glycol combined with ultrasonic technology can be used to promote permeation of Baimai Ointment that contains both water-soluble and fat-soluble components in the clinical application. This study provides a theoretical basis for the clinical application of Baimai Ointment and other transdermal preparations.

Asymmetric physiological response of a reef-building coral to pulsed versus continuous addition of inorganic nutrients.

Coral reefs, especially those located near-shore, are increasingly exposed to anthropogenic, eutrophic conditions that are often chronic. Yet, corals under unperturbed conditions may frequently receive natural and usually temporary nutrient supplementation through biological sources such as fishes. We compared physiological parameters indicative of long- and short-term coral health (day and night calcification, fragment surface area, productivity, energy reserves, and tissue stoichiometry) under continuous and temporary nutrient enrichment. The symbiotic coral Acropora intermedia was grown for 7 weeks under continuously elevated (press) levels of ammonium (14 µmol L-1) and phosphate (10 µmol L-1) as separate and combined treatments, to discern the individual and interactive nutrient effects. Another treatment exposed A. intermedia twice-daily to an ammonium and phosphate pulse of the same concentrations as the press treatments to simulate natural biotic supplementation. Press exposure to elevated ammonium or phosphate produced mixed effects on physiological responses, with little interaction between the nutrients in the combined treatment. Overall, corals under press exposure transitioned resources away from calcification. However, exposure to nutrient pulses often enhanced physiological responses. Our findings indicate that while continuous nutrient enrichment may pose a threat to coral health, episodic nutrient pulses that resemble natural nutrient supplementation may significantly benefit coral health and physiology.

Feeding tricarboxylic acid cycle intermediates improves lactate consumption and antibody production in Chinese hamster ovary cell cultures.

Media components play an important role in modulating cell metabolism and improving product titer in mammalian cell cultures. To sustain cell productivity, highly active oxidative metabolism is desired. Here we explored the effect of tricarboxylic acid (TCA) cycle intermediates supplementation on lactate metabolism and productivity in Chinese hamster ovary fed-batch cultures. Direct addition of 5 mM alpha-ketoglutarate (α-KG), malic acid, or succinic acid in the basal medium did not have any significant impact on culture performance. On the other hand, feeding α-KG, malic acid, and succinic acid in the stationary phase, either as a single solution or as a mixture, significantly improved lactate consumption, reduced ammonium accumulation, and led to higher cell specific productivity and antibody titer (~35% increase for the best condition). Delivering those intermediates as an acidic solution for pH control eliminated CO2 sparging and accumulation. Feeding TCA cycle intermediates was also demonstrated to be superior to feeding lactic acid or pyruvic acid in titer improvement. Taken together, feeding TCA cycle intermediates was effective in improving lactate consumption and increasing product titer, which is likely due to enhanced oxidative metabolism in an extended duration.

Active nitrogen fixation by Crocosphaera expands their niche despite the presence of ammonium - A case study.

Unicellular nitrogen fixer Crocosphaera contributes substantially to nitrogen fixation in oligotrophic subtropical gyres. They fix nitrogen even when significant amounts of ammonium are available. This has been puzzling since fixing nitrogen is energetically inefficient compared with using available ammonium. Here we show that by fixing nitrogen, Crocosphaera can increase their population and expand their niche despite the presence of ammonium. We have developed a simple but mechanistic model of Crocosphaera based on their growth in steady state culture. The model shows that the growth of Crocosphaera can become nitrogen limited despite their capability to fix nitrogen. When they fix nitrogen, the population increases by up to 78% relative to the case without nitrogen fixation. When we simulate a simple ecological situation where Crocosphaera exists with non-nitrogen-fixing phytoplankton, the relative abundance of Crocosphaera increases with nitrogen fixation, while the population of non-nitrogen-fixing phytoplankton decreases since a larger fraction of fixed nitrogen is consumed by Crocosphaera. Our study quantitatively supports the benefit of nitrogen fixation despite the high electron/energy costs, even when an energetically efficient alternative is available. It demonstrates a competitive aspect of Crocosphaera, permitting them to be regionally significant nitrogen fixers.

Ammonium triggered the response mechanism of lysine crotonylome in tea plants.

BACKGROUND: Lysine crotonylation, as a novel evolutionarily conserved type of post-translational modifications, is ubiquitous and essential in cell biology. However, its functions in tea plants are largely unknown, and the full functions of lysine crotonylated proteins of tea plants in nitrogen absorption and assimilation remains unclear. Our study attempts to describe the global profiling of nonhistone lysine crotonylation in tea leaves and to explore how ammonium (NH4+) triggers the response mechanism of lysine crotonylome in tea plants. RESULTS: Here, we performed the global analysis of crotonylome in tea leaves under NH4+ deficiency/resupply using high-resolution LC-MS/MS coupled with highly sensitive immune-antibody. A total of 2288 lysine crotonylation sites on 971 proteins were identified, of which contained in 15 types of crotonylated motifs. Most of crotonylated proteins were located in chloroplast (37%) and cytoplasm (33%). Compared with NH4+ deficiency, 120 and 151 crotonylated proteins were significantly changed at 3 h and 3 days of NH4+ resupply, respectively. Bioinformatics analysis showed that differentially expressed crotonylated proteins participated in diverse biological processes such as photosynthesis (PsbO, PsbP, PsbQ, Pbs27, PsaN, PsaF, FNR and ATPase), carbon fixation (rbcs, rbcl, TK, ALDO, PGK and PRK) and amino acid metabolism (SGAT, GGAT2, SHMT4 and GDC), suggesting that lysine crotonylation played important roles in these processes. Moreover, the protein-protein interaction analysis revealed that the interactions of identified crotonylated proteins diversely involved in photosynthesis, carbon fixation and amino acid metabolism. Interestingly, a large number of enzymes were crotonylated, such as Rubisco, TK, SGAT and GGAT, and their activities and crotonylation levels changed significantly by sensing ammonium, indicating a potential function of crotonylation in the regulation of enzyme activities. CONCLUSIONS: The results indicated that the crotonylated proteins had a profound influence on metabolic process of tea leaves in response to NH4+ deficiency/resupply, which mainly involved in diverse aspects of primary metabolic processes by sensing NH4+, especially in photosynthesis, carbon fixation and amino acid metabolism. The data might serve as important resources for exploring the roles of lysine crotonylation in N metabolism of tea plants. Data were available via ProteomeXchange with identifier PXD011610.

Nitric oxide synthase-mediated early nitric oxide burst alleviates water stress-induced oxidative damage in ammonium-supplied rice roots.

BACKGROUND: Nutrition with ammonium (NH4+) can enhance the drought tolerance of rice seedlings in comparison to nutrition with nitrate (NO3-). However, there are still no detailed studies investigating the response of nitric oxide (NO) to the different nitrogen nutrition and water regimes. To study the intrinsic mechanism underpinning this relationship, the time-dependent production of NO and its protective role in the antioxidant defense system of NH4+- or NO3--supplied rice seedlings were studied under water stress. RESULTS: An early NO burst was induced by 3 h of water stress in the roots of seedlings subjected to NH4+ treatment, but this phenomenon was not observed under NO3- treatment. Root oxidative damage induced by water stress was significantly higher for treatment with NO3- than with NH4+ due to reactive oxygen species (ROS) accumulation in the former. Inducing NO production by applying the NO donor 3 h after NO3- treatment alleviated the oxidative damage, while inhibiting the early NO burst by applying the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO) increased root oxidative damage in NH4+ treatment. Application of the nitric oxide synthase (NOS) inhibitor N(G)-nitro-L-arginine methyl ester(L-NAME) completely suppressed NO synthesis in roots 3 h after NH4+ treatment and aggravated water stress-induced oxidative damage. Therefore, the aggravation of oxidative damage by L-NAME might have resulted from changes in the NOS-mediated early NO burst. Water stress also increased the activity of root antioxidant enzymes (catalase, superoxide dismutase, and ascorbate peroxidase). These were further induced by the NO donor but repressed by the NO scavenger and NOS inhibitor in NH4+-treated roots. CONCLUSION: These findings demonstrate that the NOS-mediated early NO burst plays an important role in alleviating oxidative damage induced by water stress by enhancing the antioxidant defenses in roots supplemented with NH4+.

Ammonium mitigates Cd toxicity in rice (Oryza sativa) via putrescine-dependent alterations of cell wall composition.

In plants, different forms of nitrogen (NO3- or NH4+) affect nutrient uptake and environmental stress responses. In the present study, we tested whether NO3- and NH4+ affect the ability of rice (Oryza sativa) to tolerate the toxic heavy metal cadmium (Cd). Compared with NO3-, NH4+ treatment significantly increased chlorophyll contents and reduced Cd2+ levels in rice cultivars Nipponbare (japonica) and Kasalath (indica) grown in 0.2 mM Cd2+. NH4+ significantly reduced the pectin and hemicellulose contents and inhibited the pectin methylesterase (PME) activity in rice roots, thereby reducing the negative charges in the cell wall and decreasing the accumulation of Cd2+ in roots. In addition, NH4+ reduced the absorption and root-to-shoot translocation of Cd2+ by decreasing the expression of OsHMA2 and OsNramp5 in the root. Levels of the signaling molecule putrescine were significantly higher in the roots of both rice cultivars provided with NH4+ compared with NO3-. The addition of putrescine reduced Cd2+ contents in both rice cultivars and increased the chlorophyll content in shoots by reducing root cell wall pectin and hemicellulose contents, inhibiting PME activity and suppressing the expression of OsHMA2 and OsNramp5 in the root. Taken together, these results indicate that NH4+ treatment alleviated Cd toxicity, enabling rice to withstand the noxious effects of Cd by modifying the cell wall Cd-binding capacity due to alterations of pectin and hemicellulose contents and Cd transport, processes induced by increasing putrescine levels. Our findings suggest methods to decrease Cd accumulation in rice by applying NH4+ fertilizers.

Doxycycline and its quaternary ammonium derivative for adjuvant therapies of chondrosarcoma.

PURPOSE: This study was conducted during the development of innovative treatment targeting the microenvironment of chondrosarcoma. In this context, MMP inhibitors were conjugated with a quaternary ammonium (QA) function as a targeting ligand to proteoglycans of chondrosarcoma extracellular matrix. Here we report the proof of concept of this strategy applied to the MMP13 inhibitor, doxycycline (Dox). METHODS: A quaternary ammonium derivative of the MMP13 inhibitor doxycycline (QA-Dox) was synthesized, and its anticancer activity was evaluated in the Swarm rat chondrosarcoma (SRC) model compared with the parent drug doxycycline, in vitro and in vivo. In vivo, dox and QA-Dox efficiency was assessed at equimolar doses according to a q4dx4 schedule by monitoring tumour volume by MRI and PG-targeted scintigraphy. Molecular mechanism (MMP13 expression, proteoglycan level) and histology studies were performed on tumours. RESULTS: The link of QA targeting function to Dox maintained the MMP13 inhibitory activity in vitro. Interestingly, the bacteriostatic activity was lost. SRC cells incubated with both drugs were blocked in S and G2 M phases. Tumour growth inhibition (confirmed by histology) was observed for both Dox and QA-Dox. Undesirable blood effects (leukocyte decrease) were reduced when Dox was targeted to tumour tissue using the QA function. CONCLUSIONS: In the SRC model, the MMP13 inhibitor Dox and its QA derivative are promising as adjuvant therapies for chondrosarcoma management.

Transcriptome and metabolite analysis identifies nitrogen utilization genes in tea plant (Camellia sinensis).

Applied nitrogen (N) fertilizer significantly increases the leaf yield. However, most N is not utilized by the plant, negatively impacting the environment. To date, little is known regarding N utilization genes and mechanisms in the leaf production. To understand this, we investigated transcriptomes using RNA-seq and amino acid levels with N treatment in tea (Camellia sinensis), the most popular beverage crop. We identified 196 and 29 common differentially expressed genes in roots and leaves, respectively, in response to ammonium in two tea varieties. Among those genes, AMT, NRT and AQP for N uptake and GOGAT and GS for N assimilation were the key genes, validated by RT-qPCR, which expressed in a network manner with tissue specificity. Importantly, only AQP and three novel DEGs associated with stress, manganese binding, and gibberellin-regulated transcription factor were common in N responses across all tissues and varieties. A hypothesized gene regulatory network for N was proposed. A strong statistical correlation between key genes' expression and amino acid content was revealed. The key genes and regulatory network improve our understanding of the molecular mechanism of N usage and offer gene targets for plant improvement.

The use of NH4+ rather than NO3- affects cell stoichiometry, C allocation, photosynthesis and growth in the cyanobacterium Synechococcus sp. UTEX LB 2380, only when energy is limiting.

The assimilation of N-NO3- requires more energy than that of N-NH4+ . This becomes relevant when energy is limiting and may impinge differently on cell energy budget depending on depth, time of the day and season. We hypothesize that N-limited and energy-limited cells of the oceanic cyanobacterium Synechococcus sp. differ in their response to the N source with respect to growth, elemental stoichiometry and carbon allocation. Under N limitation, cells retained almost absolute homeostasis of elemental and organic composition, and the use of NH4+ did not stimulate growth. When energy was limiting, however, Synechococcus grew faster in NH4+ than in NO3- and had higher C (20%), N (38%) and S (30%) cell quotas. Furthermore, more C was allocated to protein, whereas the carbohydrate and lipid pool size did not change appreciably. Energy limitation also led to a higher photosynthetic rate relative to N limitation. We interpret these results as an indication that, under energy limitation, the use of the least expensive N source allowed a spillover of the energy saved from N assimilation to the assimilation of other nutrients. The change in elemental stoichiometry influenced C allocation, inducing an increase in cell protein, which resulted in a stimulation of photosynthesis and growth.

Transcriptome-guided gene isolation and functional characterization of UDP-xylose synthase and UDP-D-apiose/UDP-D-xylose synthase families from Ornithogalum caudatum Ait.

KEY MESSAGE: The present study first identified the involvement of OcUAXS2 and OcUXS1-3 in anticancer polysaccharides biosynthesis in O. caudatum. UDP-xylose synthase (UXS) and UDP-D-apiose/UDP-D-xylose synthase (UAXS), both capable of converting UDP-D-glucuronic acid to UDP-D-xylose, are believed to transfer xylosyl residue to anticancer polysaccharides biosynthesis in Ornithogalum caudatum Ait. However, the cDNA isolation and functional characterization of genes encoding the two enzymes from O. caudatum has never been documented. Previously, the transcriptome sequencing of O. caudatum was performed in our laboratory. In this study, a total of six and two unigenes encoding UXS and UAXS were first retrieved based on RNA-Seq data. The eight putative genes were then successfully isolated from transcriptome of O. caudatum by reverse transcription polymerase chain reaction (RT-PCR). Phylogenetic analysis revealed the six putative UXS isoforms can be classified into three types, one soluble and two distinct putative membrane-bound. Moreover, the two UAXS isoenzymes were predicted to be soluble forms. Subsequently, these candidate cDNAs were characterized to be bona fide genes by functional expression in Escherichia coli individually. Although UXS and UAXS catalyzed the same reaction, their biochemical properties varied significantly. It is worth noting that a ratio switch of UDP-D-xylose/UDP-D-apiose for UAXS was established, which is assumed to be helpful for its biotechnological application. Furthermore, a series of mutants were generated to test the function of NAD+ binding motif GxxGxxG. Most importantly, the present study determined the involvement of OcUAXS2 and OcUXS1-3 in xylose-containing polysaccharides biosynthesis in O. caudatum. These data provide a comprehensive knowledge for UXS and UAXS families in plants.

Genome-wide transcriptome analysis of expression in rice seedling roots in response to supplemental nitrogen.

Nitrogen (N) is the most important macronutrient for plant growth and grain yields. For rice crops, nitrate and ammonium are the major N sources. To explore the genomic responses to ammonium supplements in rice roots, we used 17-day-old seedlings grown in the absence of external N that were then exposed to 0.5mM (NH4)2SO4 for 3h. Transcriptomic profiles were examined by microarray experiments. In all, 634 genes were up-regulated at least two-fold by the N-supplement when compared with expression in roots from untreated control plants. Gene Ontology (GO) enrichment analysis revealed that those upregulated genes are associated with 23 GO terms. Among them, metabolic processes for diverse amino acids (i.e., aspartate, threonine, tryptophan, glutamine, l-phenylalanine, and thiamin) as well as nitrogen compounds are highly over-represented, demonstrating that our selected genes are suitable for studying the N-response in roots. This enrichment analysis also indicated that nitrogen is closely linked to diverse transporter activities by primary metabolites, including proteins (amino acids), lipids, and carbohydrates, and is associated with carbohydrate catabolism and cell wall organization. Integration of results from omics analysis of metabolic pathways and transcriptome data using the MapMan tool suggested that the TCA cycle and pathway for mitochondrial electron transport are co-regulated when rice roots are exposed to ammonium. We also investigated the expression of N-responsive marker genes by performing a comparative analysis with root samples from plants grown under different NH4(+) treatments. The diverse responses to such treatment provide useful insight into the global changes related to the shift from an N-deficiency to an enhanced N-supply in rice, a model crop plant.

Altered cell wall properties are responsible for ammonium-reduced aluminium accumulation in rice roots.

The phytotoxicity of aluminium (Al) ions can be alleviated by ammonium (NH4(+)) in rice and this effect has been attributed to the decreased Al accumulation in the roots. Here, the effects of different nitrogen forms on cell wall properties were compared in two rice cultivars differing in Al tolerance. An in vitro Al-binding assay revealed that neither NH4(+) nor NO3(-) altered the Al-binding capacity of cell walls, which were extracted from plants not previously exposed to N sources. However, cell walls extracted from NH4(+)-supplied roots displayed lower Al-binding capacity than those from NO3(-)-supplied roots when grown in non-buffered solutions. Fourier-transform infrared microspectroscopy analysis revealed that, compared with NO3(-)-supplied roots, NH4(+)-supplied roots possessed fewer Al-binding groups (-OH and COO-) and lower contents of pectin and hemicellulose. However, when grown in pH-buffered solutions, these differences in the cell wall properties were not observed. Further analysis showed that the Al-binding capacity and properties of cell walls were also altered by pHs alone. Taken together, our results indicate that the NH4(+)-reduced Al accumulation was attributed to the altered cell wall properties triggered by pH decrease due to NH4(+) uptake rather than direct competition for the cell wall binding sites between Al(3+) and NH4(+).

Ammonium reduces chromium toxicity in the freshwater alga Chlorella vulgaris.

The aim of the present study was to investigate the protective effect of ammonium (NH4 (+)) on Cr toxicity to the freshwater alga Chlorella vulgaris. We followed an array of cellular functions and biomolecules in C. vulgaris cells exposed to 50 or 100 µM Cr at three different initial NH4 (+) concentrations (0.5, 3, and 10 mM). The results showed that Cr strongly inhibited cell yield of C. vulgaris, but 10 mM NH4 (+) could decrease by more than two-fold Cr toxicity on cell yield compared to exposure to 0.5 mM NH4 (+). Cr toxicity on gene transcripts and cellular substructure was also much lower at high than at low NH4 (+). Our results suggest that this protecting effect of NH4 (+) on intracellular Cr toxicity could be due to several factors, such as enhance uptake of phosphorus, increase in C and N assimilation efficiency, and increase transcription of photosynthesis-related genes.

[Effects of nitrogen form on growth and quality of Chrysanthemums morifolium].

This paper is aimed to study the effects of nitrogen form on the growth and quality of Chrysanthemums morifolium at the same nitrogen level. In order to provide references for nutrition regulation of Ch. morifolium in field production, pot experiments were carried out in the greenhouse at experimental station of Nanjing Agricultural University. Five proportions of ammonium and nitrate nitrogen were set up and a randomized block design was applied four times repeatedly. The results showed that the growth and quality of Ch. morifolium were significantly influenced by the nitrogen form. The content of chlorophyll and photosynthesis rate were the highest at the NH4(+) -N /NO3(-) -N ratio of 25:75; The activities of NR in different parts of Ch. -morifolium reached the highest at the NH4(+) - N/NO3(-) -N ratio of 0: 100. The contents of nitrate nitrogen in the root and leaves reached the highest at the NH4(+) -N/NO3(-) -N ratio of 50:50. The activities of GS, GOGAT and the content of amylum increased with the ratio of NO3(-) -N decreasing and reached it's maximum at the NH4 + -N/NO3 - -N ratio of 100: 0. The content of ammonium nitrogen were the highest at the NH4 + -N /NO3 --N ratio of 75: 25, while the content of soluble sugar reached the highest at the NH4(+)-N/NO3(-) -N ratio of 25: 75. The content of flavones, chlorogenic acid and 3,5-O-dicoffeoylqunic acid were 57.2 mg x g(-1), 0.673% and 1.838% respectively, reaching the maximum at the NH4(+) -N /NO3(-) -N ratio of 25:75; The content of luteoloside increased with the ratio of NO3(-) -N increasing and reached it's maximum at the NH4(+) -N/NO3(-) -N ratio of 0: 100. The yield of Ch. morifolium reached it's maximum at the NH4(+) -N /NO3(-) -N ratio of 25:75. Nitrogen form has some remarkable influence on the nitrogen metabolism, photosynthesis and growth, Nitrogen form conducive to the growth and quality of Ch. morifolium at the NH4(+) -N /NO3(-) -N ratio of 25: 75.

The influence of duckweed species diversity on biomass productivity and nutrient removal efficiency in swine wastewater.

The effect of temperature, light intensity, nitrogen and phosphorus concentrations on the biomass and starch content of duckweed (Landoltia punctata OT, Lemna minor OT) in monoculture and mixture were assessed. Low light intensity promoted more starch accumulation in mixture than in monoculture. The duckweed in mixture had higher biomass and nutrient removal efficiency than those in monoculture in swine wastewater. Moreover, the ability of L. punctata C3, L. minor C2, Spirodela polyrhiza C1 and their mixtures to recovery nutrients and their biomass were analyzed. Results showed that L. minor C2 had the highest N and P content, while L. punctata C3 had the highest starch content, and the mixture of L. punctata C3 and L. minor C2 had the greatest nutrient removal rate and the highest biomass. Compared with L. punctata C3 and L. minor C2 in monoculture, their biomass in mixture increased by 17.0% and 39.8%, respectively.