Role of gut nutrient sensing in stimulating appetite and conditioning food preferences

PubMed Central

Ackroff, Karen

2012-01-01

The discovery of taste and nutrient receptors (chemosensors) in the gut has led to intensive research on their functions. Whereas oral sugar, fat, and umami taste receptors stimulate nutrient appetite, these and other chemosensors in the gut have been linked to digestive, metabolic, and satiating effects that influence nutrient utilization and inhibit appetite. Gut chemosensors may have an additional function as well: to provide positive feedback signals that condition food preferences and stimulate appetite. The postoral stimulatory actions of nutrients are documented by flavor preference conditioning and appetite stimulation produced by gastric and intestinal infusions of carbohydrate, fat, and protein. Recent findings suggest an upper intestinal site of action, although postabsorptive nutrient actions may contribute to flavor preference learning. The gut chemosensors that generate nutrient conditioning signals remain to be identified; some have been excluded, including sweet (T1R3) and fatty acid (CD36) sensors. The gut-brain signaling pathways (neural, hormonal) are incompletely understood, although vagal afferents are implicated in glutamate conditioning but not carbohydrate or fat conditioning. Brain dopamine reward systems are involved in postoral carbohydrate and fat conditioning but less is known about the reward systems mediating protein/glutamate conditioning. Continued research on the postoral stimulatory actions of nutrients may enhance our understanding of human food preference learning. PMID:22442194

Microarray analysis of pancreatic gene expression during biotin repletion in biotin-deficient rats.

PubMed

Dakshinamurti, Krishnamurti; Bagchi, Rushita A; Abrenica, Bernard; Czubryt, Michael P

2015-12-01

Biotin is a B vitamin involved in multiple metabolic pathways. In humans, biotin deficiency is relatively rare but can cause dermatitis, alopecia, and perosis. Low biotin levels occur in individuals with type-2 diabetes, and supplementation with biotin plus chromium may improve blood sugar control. The acute effect on pancreatic gene expression of biotin repletion following chronic deficiency is unclear, therefore we induced biotin deficiency in adult male rats by feeding them a 20% raw egg white diet for 6 weeks. Animals were then randomized into 2 groups: one group received a single biotin supplement and returned to normal chow lacking egg white, while the second group remained on the depletion diet. After 1 week, pancreata were removed from biotin-deficient (BD) and biotin-repleted (BR) animals and RNA was isolated for microarray analysis. Biotin depletion altered gene expression in a manner indicative of inflammation, fibrosis, and defective pancreatic function. Conversely, biotin repletion activated numerous repair and anti-inflammatory pathways, reduced fibrotic gene expression, and induced multiple genes involved in pancreatic endocrine and exocrine function. A subset of the results was confirmed by quantitative real-time PCR analysis, as well as by treatment of pancreatic AR42J cells with biotin. The results indicate that biotin repletion, even after lengthy deficiency, results in the rapid induction of repair processes in the pancreas.

Effects of temperature and nutrient regimes on biomass and lipid production by six oleaginous microalgae in batch culture employing a two-phase cultivation strategy.

PubMed

Roleda, Michael Y; Slocombe, Stephen P; Leakey, Raymond J G; Day, John G; Bell, Elanor M; Stanley, Michele S

2013-02-01

Commercial success of algal-based biofuels depends on growth characteristics and lipid metabolism of the production species. The oleaginous microalgae, Thalassiosira pseudonana, Odontella aurita, Nannochloropsis oculata, Isochrysis galbana, Chromulina ochromonoides, and Dunaliella tertiolecta, were cultivated under a matrix of two temperatures (10 and 20 °C) and two nutrient regimes (deplete and replete). For all species, a strong negative correlation between growth rate and lipid content was observed. Multiple stressors have no additive effect on lipid accumulation. Total oil content (fatty acid methyl esters, FAMEs, pg cell(-1)) was increased more by nutrient limitation than by temperature stress. In response to nutrient stress, N. oculata emerged as the most robust species with an increase in lipid accumulation of up to three to four-fold compared to the accumulation under nutrient sufficient conditions. Although stress conditions led to reduced fatty acid unsaturation in most taxa due to increased triacylglycerol (TAG) production, a high proportion of eicosapentaenoic acid (EPA) was maintained in O. aurita. Copyright © 2012 Elsevier Ltd. All rights reserved.

Nutrient resorption helps drive intra-specific coupling of foliar nitrogen and phosphorus under nutrient-enriched conditions

USGS Publications Warehouse

Xiao-Tao, Lü; Reed, Sasha C.; Yu, Qiang; Han, Xing-Guo

2016-01-01

Taken together, the results suggest plants in this ecosystem are much more responsive to changing N cycles than P cycles and emphasize the significance of nutrient resorption as an important plant control over the stoichiometric coupling of N and P under nutrient enriched conditions.

Conserved Transcriptional Responses to Nutrient Stress in Bloom-Forming Algae

PubMed Central

Harke, Matthew J.; Juhl, Andrew R.; Haley, Sheean T.; Alexander, Harriet; Dyhrman, Sonya T.

2017-01-01

The concentration and composition of bioavailable nitrogen (N) and phosphorus (P) in the upper ocean shape eukaryotic phytoplankton communities and influence their physiological responses. Phytoplankton are known to exhibit similar physiological responses to limiting N and P conditions such as decreased growth rates, chlorosis, and increased assimilation of N and P. Are these responses similar at the molecular level across multiple species? To interrogate this question, five species from biogeochemically important, bloom-forming taxa (Bacillariophyta, Dinophyta, and Haptophyta) were grown under similar low N, low P, and replete nutrient conditions to identify transcriptional patterns and associated changes in biochemical pools related to N and P stress. Metabolic profiles, revealed through the transcriptomes of these taxa, clustered together based on species rather than nutrient stressor, suggesting that the global metabolic response to nutrient stresses was largely, but not exclusively, species-specific. Nutrient stress led to few transcriptional changes in the two dinoflagellates, consistent with other research. An orthologous group analysis examined functionally conserved (i.e., similarly changed) responses to nutrient stress and therefore focused on the diatom and haptophytes. Most conserved ortholog changes were specific to a single nutrient treatment, but a small number of orthologs were similarly changed under both N and P stress in 2 or more species. Many of these orthologs were related to photosynthesis and may represent generalized stress responses. A greater number of orthologs were conserved across more than one species under low P compared to low N. Screening the conserved orthologs for functions related to N and P metabolism revealed increased relative abundance of orthologs for nitrate, nitrite, ammonium, and amino acid transporters under N stress, and increased relative abundance of orthologs related to acquisition of inorganic and organic P

Risk Factors for Vitamin D Deficiency and Impact of Repletion in a Tertiary Care Inflammatory Bowel Disease Population.

PubMed

Zullow, Samantha; Jambaulikar, Guruprasad; Rustgi, Ankur; Quezada, Sandra; Cross, Raymond K

2017-08-01

Many patients with inflammatory bowel disease (IBD) are vitamin D deficient. The purpose of our study was to identify risk factors for vitamin D deficiency in IBD and to assess the impact of vitamin D repletion on disease activity and quality of life (QOL). Patients with at least one 25-OH vitamin D level measured between 2004 and 2011 were included. Patients with a level <30 ng/ml at baseline were followed until the time of repletion. QOL and disease activity scores were measured at baseline and repletion. A total of 255 patients were identified. 33, 29, and 39% had a vitamin D level of ≥30, 20-29, and <20 ng/ml, respectively. When adjusting for disease type and duration, gender, smoking, and race, non-Caucasians had 5.3 (2.3-12.3) and UC patients had a 0.59 (0.33-1.03) odds of having a vitamin D <30 ng/ml. Women were 1.7 times more likely to have a 25-OH vitamin D level <20 ng/ml than men. 55 patients underwent repletion. In CD patients, the HBI and SIBDQ prior to repletion was 5.5 ± 4.9 and 44.3 ± 16.4, respectively; these improved to 3.6 ± 3.4 and 48.6 ± 14.2 after repletion (p = 0.0154 and p = 0.0684). In this tertiary care IBD cohort, the majority of patients have low vitamin D levels. Non-Caucasian race and female gender are associated with low vitamin D. UC was associated with lower risk of vitamin D insufficiency. In CD, vitamin D repletion is associated with decreased disease activity and increased QOL.

Physiological studies of chloramine resistance developed by Klebsiella pneumoniae under low-nutrient growth conditions.

PubMed Central

Stewart, M H; Olson, B H

1992-01-01

This study investigated the physiological mechanisms of resistance to chloramines developed by Klebsiella pneumoniae grown in a nutrient-limited environment. Growth under these conditions resulted in cells that were smaller than cells grown under high-nutrient conditions and extensively aggregated. Cellular aggregates ranged from 10 to more than 10,000 cells per aggregate, with a mean population aggregate size of 90 cells. This aggregation may have been facilitated by the presence of extracellular polymer material. By using glucose as a reference of capsule content, it was determined that growth under low-nutrient conditions produced cells with 8 x 10(-14) to 41 x 10(-14) g of carbohydrate per cell, with a mean +/- standard deviation of 27 x 10(-14) +/- 16 x 10(-14) g of carbohydrate per cell. In comparison, growth under high-nutrient conditions resulted in 2.7 x 10(-14) to 5.9 x 10(-14) g of carbohydrate per cell, with a mean and standard deviation of 4.3 x 10(-14) +/- 1.2 x 10(-14) g of carbohydrate per cell. Cell wall and cell membrane lipids also varied with growth conditions. The ratio of saturated to unsaturated fatty acids in cells grown under low-nutrient conditions was approximately five times greater than that in cells grown under high-nutrient conditions, suggesting possible differences in membrane permeability. An analysis of sulfhydryl (-SH) groups revealed no quantitative difference with respect to growth conditions. However, upon exposure to chloramines, only 33% of the -SH groups of cells grown under low-nutrient conditions were oxidized, compared with 80% oxidization of -SH groups in cells grown under high-nutrient conditions. The reduced effectiveness of chloramine oxidization of -SH groups in cells grown under low-nutrient conditions may be due to restricted penetration of chloramines into the cells, conformational changes of enzymes, or a combination of both factors. The results of this study suggest that chloramine resistance developed under

Surface-water nutrient conditions and sources in the United States Pacific Northwest

USGS Publications Warehouse

Wise, D.R.; Johnson, H.M.

2011-01-01

The SPAtially Referenced Regressions On Watershed attributes (SPARROW) model was used to perform an assessment of surface-water nutrient conditions and to identify important nutrient sources in watersheds of the Pacific Northwest region of the United States (U.S.) for the year 2002. Our models included variables representing nutrient sources as well as landscape characteristics that affect nutrient delivery to streams. Annual nutrient yields were higher in watersheds on the wetter, west side of the Cascade Range compared to watersheds on the drier, east side. High nutrient enrichment (relative to the U.S. Environmental Protection Agency's recommended nutrient criteria) was estimated in watersheds throughout the region. Forest land was generally the largest source of total nitrogen stream load and geologic material was generally the largest source of total phosphorus stream load generated within the 12,039 modeled watersheds. These results reflected the prevalence of these two natural sources and the low input from other nutrient sources across the region. However, the combined input from agriculture, point sources, and developed land, rather than natural nutrient sources, was responsible for most of the nutrient load discharged from many of the largest watersheds. Our results provided an understanding of the regional patterns in surface-water nutrient conditions and should be useful to environmental managers in future water-quality planning efforts.

Enzyme-mediated Nutrient Regeneration Following Lysis of Synechococcus WH7803

NASA Astrophysics Data System (ADS)

Mine, A. H.; Coleman, M.; Colman, A. S.

2016-02-01

Phosphate availability plays a pivotal role in limiting primary production in large regions of the oceans. In order to meet their metabolic needs, microbes use a variety of strategies to overcome phosphate stress. Expression of enzymes such as alkaline phosphatase (APase) allows cells to hydrolyze and use certain ambient dissolved organic phosphorus (DOP) compounds to meet their P demand. Cell lysis releases a range of nutrient forms and enzymes into the ambient environment and is an essential component of the microbial loop. Yet very few studies have attempted to characterize both the immediate and sustained nutrient remineralization linked to the milieu of organophosphorus compounds and enzymatic activity in lysate. We conducted experiments using Synechococcus WH7803 grown under nutrient replete and starved conditions to quantify the release of phosphate during viral lysis and lysis by lysozyme treatment. Dissolved inorganic and organic phosphorus concentrations and APase activity were monitored over time following lysis. We observed a significant initial release of orthophosphate that accompanies lysis. Following lysis, phosphate concentrations continue to rise for a period of hours to days as organophosphorus compounds continue to hydrolyze. Our observations suggest this is due to a combination of direct hydrolysis of DOP released during lysis, solubilization of POP followed by hydrolysis, and possibly polyphosphate decomposition. Size fractionated enzymatic assays suggest cellular debris associated enzymes and dissolved fractions are both important in DOP hydrolysis in the viral lysate, whereas particle associated APase activity dominates in the lysozyme treatments. Moreover, nutrient status prior to lysis has important controls on the initial nutrient release and subsequent regenerative flux. These findings underscore the significance of lysis and subsequent enzyme-mediated hydrolysis in nutrient regeneration and biogeochemical dynamics in marine ecosystems.

Surface-Water Nutrient Conditions and Sources in the United States Pacific Northwest1

PubMed Central

Wise, Daniel R; Johnson, Henry M

2011-01-01

Abstract The SPAtially Referenced Regressions On Watershed attributes (SPARROW) model was used to perform an assessment of surface-water nutrient conditions and to identify important nutrient sources in watersheds of the Pacific Northwest region of the United States (U.S.) for the year 2002. Our models included variables representing nutrient sources as well as landscape characteristics that affect nutrient delivery to streams. Annual nutrient yields were higher in watersheds on the wetter, west side of the Cascade Range compared to watersheds on the drier, east side. High nutrient enrichment (relative to the U.S. Environmental Protection Agency's recommended nutrient criteria) was estimated in watersheds throughout the region. Forest land was generally the largest source of total nitrogen stream load and geologic material was generally the largest source of total phosphorus stream load generated within the 12,039 modeled watersheds. These results reflected the prevalence of these two natural sources and the low input from other nutrient sources across the region. However, the combined input from agriculture, point sources, and developed land, rather than natural nutrient sources, was responsible for most of the nutrient load discharged from many of the largest watersheds. Our results provided an understanding of the regional patterns in surface-water nutrient conditions and should be useful to environmental managers in future water-quality planning efforts. PMID:22457584

Freshwater bacteria are stoichiometrically flexible with a nutrient composition similar to seston

USGS Publications Warehouse

Cotner, James B.; Hall, Edward K.; Scott, J. Thad; Heldal, Mikal

2010-01-01

Although aquatic bacteria are assumed to be nutrient-rich, they out-compete other foodweb osmotrophs for nitrogen (N) and phosphorus (P) an apparent contradiction to resource ratio theory. This paradox could be resolved if aquatic bacteria were demonstrated to be nutrient-poor relative other portions of the planktonic food web. In a survey of >120 lakes in the upper Midwest of the USA, the nutrient content of bacteria was lower than previously reported and very similar to the Redfield ratio, with a mean biomass composition of 102:12:1 (C:N:P). Individual freshwater bacterial isolates grown under P-limiting and P-replete conditions had even higher C:P and N:P ratios with a mean community biomass composition ratio of 875C:179N:1P suggesting that individual strains can be extremely nutrient-poor, especially with respect to P. Cell-specific measurements of individual cells from one lake confirmed that low P content could be observed at the community level in natural systems with a mean biomass composition of 259C:69N:1P. Variability in bacterial stoichiometry is typically not recognized in the literature as most studies assume constant and nutrient-rich bacterial biomass composition. We present evidence that bacteria can be extremely P-poor in individual systems and in culture, suggesting that bacteria in freshwater ecosystems can either play a role as regenerators or consumers of inorganic nutrients and that this role could switch depending on the relationship between bacterial biomass stoichiometry and resource stoichiometry. This ability to switch roles between nutrient retention and regeneration likely facilitates processing of terrestrial organic matter in lakes and rivers and has important implications for a wide range of bacterially mediated biogeochemical processes.

Carbon storage in seagrass soils: long-term nutrient history exceeds the effects of near-term nutrient enrichment

NASA Astrophysics Data System (ADS)

Armitage, A. R.; Fourqurean, J. W.

2016-01-01

The carbon sequestration potential in coastal soils is linked to aboveground and belowground plant productivity and biomass, which in turn, is directly and indirectly influenced by nutrient input. We evaluated the influence of long-term and near-term nutrient input on aboveground and belowground carbon accumulation in seagrass beds, using a nutrient enrichment (nitrogen and phosphorus) experiment embedded within a naturally occurring, long-term gradient of phosphorus availability within Florida Bay (USA). We measured organic carbon stocks in soils and above- and belowground seagrass biomass after 17 months of experimental nutrient addition. At the nutrient-limited sites, phosphorus addition increased the carbon stock in aboveground seagrass biomass by more than 300 %; belowground seagrass carbon stock increased by 50-100 %. Soil carbon content slightly decreased ( ˜ 10 %) in response to phosphorus addition. There was a strong but non-linear relationship between soil carbon and Thalassia testudinum leaf nitrogen : phosphorus (N : P) or belowground seagrass carbon stock. When seagrass leaf N : P exceeded an approximate threshold of 75 : 1, or when belowground seagrass carbon stock was less than 100 g m-2, there was less than 3 % organic carbon in the sediment. Despite the marked difference in soil carbon between phosphorus-limited and phosphorus-replete areas of Florida Bay, all areas of the bay had relatively high soil carbon stocks near or above the global median of 1.8 % organic carbon. The relatively high carbon content in the soils indicates that seagrass beds have extremely high carbon storage potential, even in nutrient-limited areas with low biomass or productivity.

Carbon storage in seagrass soils: long-term nutrient history exceeds the effects of near-term nutrient enrichment

NASA Astrophysics Data System (ADS)

Armitage, A. R.; Fourqurean, J. W.

2015-10-01

The carbon sequestration potential in coastal soils is linked to aboveground and belowground plant productivity and biomass, which in turn, is directly and indirectly influenced by nutrient input. We evaluated the influence of long-term and near-term nutrient input on aboveground and belowground carbon accumulation in seagrass beds, using a nutrient enrichment (nitrogen and phosphorus) experiment embedded within a naturally occurring, long-term gradient of phosphorus availability within Florida Bay (USA). We measured organic carbon stocks in soils and above- and belowground seagrass biomass after 17 months of experimental nutrient addition. At the nutrient-limited sites, phosphorus addition increased the carbon stock in aboveground seagrass biomass by more than 300 %; belowground seagrass carbon stock increased by 50-100 %. Soil carbon content slightly decreased (~ 10 %) in response to phosphorus addition. There was a strong but non-linear relationship between soil carbon and Thalassia testudinum leaf nitrogen: phosphorus (N : P) or belowground seagrass carbon stock. When seagrass leaf N : P exceeded a threshold of 75 : 1, or when belowground seagrass carbon stock was less than 100 g m-2, there was less than 3 % organic carbon in the sediment. Despite the marked difference in soil carbon between phosphorus-limited and phosphorus-replete areas of Florida Bay, all areas of the bay had relatively high soil carbon stocks near or above the global median of 1.8 % organic carbon. The relatively high carbon content in the soils indicates that seagrass beds have extremely high carbon storage potential, even in nutrient-limited areas with low biomass or productivity.

Oxygen Consumption Rates of Bacteria under Nutrient-Limited Conditions

PubMed Central

Riedel, Timothy E.; Nealson, Kenneth H.; Finkel, Steven E.

2013-01-01

Many environments on Earth experience nutrient limitation and as a result have nongrowing or very slowly growing bacterial populations. To better understand bacterial respiration under environmentally relevant conditions, the effect of nutrient limitation on respiration rates of heterotrophic bacteria was measured. The oxygen consumption and population density of batch cultures of Escherichia coli K-12, Shewanella oneidensis MR-1, and Marinobacter aquaeolei VT8 were tracked for up to 200 days. The oxygen consumption per CFU (QO2) declined by more than 2 orders of magnitude for all three strains as they transitioned from nutrient-abundant log-phase growth to the nutrient-limited early stationary phase. The large reduction in QO2 from growth to stationary phase suggests that nutrient availability is an important factor in considering environmental respiration rates. Following the death phase, during the long-term stationary phase (LTSP), QO2 values of the surviving population increased with time and more cells were respiring than formed colonies. Within the respiring population, a subpopulation of highly respiring cells increased in abundance with time. Apparently, as cells enter LTSP, there is a viable but not culturable population whose bulk community and per cell respiration rates are dynamic. This result has a bearing on how minimal energy requirements are met, especially in nutrient-limited environments. The minimal QO2 rates support the extension of Kleiber's law to the mass of a bacterium (100-fg range). PMID:23770901

Consequences of dietary calcium and phosphorus depletion and repletion feeding sequences on growth performance and body composition of growing pigs.

PubMed

Gonzalo, E; Létourneau-Montminy, M P; Narcy, A; Bernier, J F; Pomar, C

2018-06-01

The effect of a calcium (Ca) and phosphorus (P) depletion and repletion strategy was studied in four consecutive feeding phases of 28 days each. In all, 60 castrated male pigs (14±1.6 kg initial BW) received 60% (low (L) diet; depletion) or 100% (control (C) diet; repletion) of their Ca and digestible P requirements according to six feeding sequences (CCCC, CCCL, CLCC, CCLC, LCLC and LLLL; subsequent letters indicate the diet received in phases 1, 2, 3 and 4, respectively). Pigs bone mineral content in whole-body (BMCb) and lumbar vertebrae L2 to L4 (BMCv) was measured in every feeding phase by dual-energy X-ray absorptiometry. Growth performance was slightly (<10%) affected by depletion, however, dietary treatments did not affect overall growth. Compared with control pigs, depletion reduced BMCb (34%, 38%, 33% and 22%) and BMCv (46%, 54%, 38% and 26%) in phases 1 to 4, respectively. Depletion increased however digestible P retention efficiency from the second to the fourth phases allowing LLLL pigs to present no differences in BMCb and BMCv gain compared with CCCC pigs in phase 4. Growth performance in repleted compared with control pigs was lower in phase 2, was no different in phase 3 and was lower in CLCC pigs in phase 4. Repletion increased body P and Ca retention efficiency when compared with control pigs (respectively, 8% and 10% for LC v. CC, P<0.01; 8% and 10% for CLC v. CCC, P<0.10; 18% and 25% for CLCC, CCLC, LCLC v. CCCC, P<0.001). Moreover, BMCv gain was higher in CLC pigs (P<0.001) and gains of body P, Ca, BMCb and BMCv in phase 4 were also higher in repleted than in CCCC pigs (respectively, 14%, 20%, 20% and 52%; P⩽0.02). Repletion reduced body P, Ca, BMCb and BMCv masses in phase 2 but no differences were found in phase 4 compared with control pigs. Lumbar vertebrae L2 to L4 bone mineral content was more sensitive to depletion and repletion sequences than BMCb especially in the first phase probably due to a higher proportion of metabolically

Ocean acidification impacts bacteria-phytoplankton coupling at low-nutrient conditions

NASA Astrophysics Data System (ADS)

Hornick, Thomas; Bach, Lennart T.; Crawfurd, Katharine J.; Spilling, Kristian; Achterberg, Eric P.; Woodhouse, Jason N.; Schulz, Kai G.; Brussaard, Corina P. D.; Riebesell, Ulf; Grossart, Hans-Peter

2017-01-01

The oceans absorb about a quarter of the annually produced anthropogenic atmospheric carbon dioxide (CO2), resulting in a decrease in surface water pH, a process termed ocean acidification (OA). Surprisingly little is known about how OA affects the physiology of heterotrophic bacteria or the coupling of heterotrophic bacteria to phytoplankton when nutrients are limited. Previous experiments were, for the most part, undertaken during productive phases or following nutrient additions designed to stimulate algal blooms. Therefore, we performed an in situ large-volume mesocosm ( ˜ 55 m3) experiment in the Baltic Sea by simulating different fugacities of CO2 (fCO2) extending from present to future conditions. The study was conducted in July-August after the nominal spring bloom, in order to maintain low-nutrient conditions throughout the experiment. This resulted in phytoplankton communities dominated by small-sized functional groups (picophytoplankton). There was no consistent fCO2-induced effect on bacterial protein production (BPP), cell-specific BPP (csBPP) or biovolumes (BVs) of either free-living (FL) or particle-associated (PA) heterotrophic bacteria, when considered as individual components (univariate analyses). Permutational Multivariate Analysis of Variance (PERMANOVA) revealed a significant effect of the fCO2 treatment on entire assemblages of dissolved and particulate nutrients, metabolic parameters and the bacteria-phytoplankton community. However, distance-based linear modelling only identified fCO2 as a factor explaining the variability observed amongst the microbial community composition, but not for explaining variability within the metabolic parameters. This suggests that fCO2 impacts on microbial metabolic parameters occurred indirectly through varying physicochemical parameters and microbial species composition. Cluster analyses examining the co-occurrence of different functional groups of bacteria and phytoplankton further revealed a separation of

Effect of phosphorus on biodiesel production from Scenedesmus obliquus under nitrogen-deficiency stress.

PubMed

Chu, Fei-Fei; Chu, Pei-Na; Shen, Xiao-Fei; Lam, Paul K S; Zeng, Raymond J

2014-01-01

In order to study the effect of phosphorus on biodiesel production from Scenedesmus obliquus especially under nitrogen deficiency conditions, six types of media with combinations of nitrogen repletion/depletion and phosphorus repletion/limitation/depletion were investigated in this study. It was found that nitrogen starvation compared to nitrogen repletion enhanced biodiesel productivity. Moreover, biodiesel productivity was further strengthened by varying the supply level of phosphorus from depletion, limitation, through to repletion. The maximum FAMEs productivity of 24.2 mg/L/day was obtained in nitrogen depletion with phosphorus repletion, which was two times higher than that in nutrient complete medium. More phosphorus was accumulated in cells under the nitrogen starvation with sufficient phosphorus condition, but no polyphosphate was formed. This study indicated that nitrogen starvation plus sufficient P supply might be the real "lipid trigger". Furthermore, results of the current study suggest a potential application for utilizing microalgae to combine phosphorus removal from wastewater with biodiesel production. Copyright © 2013 Elsevier Ltd. All rights reserved.

Durable graft-versus-leukaemia effects without donor lymphocyte infusions - results of a phase II study of sequential T-replete allogeneic transplantation for high-risk acute myeloid leukaemia and myelodysplasia.

PubMed

Davies, Jeff K; Hassan, Sandra; Sarker, Shah-Jalal; Besley, Caroline; Oakervee, Heather; Smith, Matthew; Taussig, David; Gribben, John G; Cavenagh, Jamie D

2018-02-01

Allogeneic haematopoietic stem-cell transplantation remains the only curative treatment for relapsed/refractory acute myeloid leukaemia (AML) and high-risk myelodysplasia but has previously been limited to patients who achieve remission before transplant. New sequential approaches employing T-cell depleted transplantation directly after chemotherapy show promise but are burdened by viral infection and require donor lymphocyte infusions (DLI) to augment donor chimerism and graft-versus-leukaemia effects. T-replete transplantation in sequential approaches could reduce both viral infection and DLI usage. We therefore performed a single-arm prospective Phase II clinical trial of sequential chemotherapy and T-replete transplantation using reduced-intensity conditioning without planned DLI. The primary endpoint was overall survival. Forty-seven patients with relapsed/refractory AML or high-risk myelodysplasia were enrolled; 43 proceeded to transplantation. High levels of donor chimerism were achieved spontaneously with no DLI. Overall survival of transplanted patients was 45% and 33% at 1 and 3 years. Only one patient developed cytomegalovirus disease. Cumulative incidences of treatment-related mortality and relapse were 35% and 20% at 1 year. Patients with relapsed AML and myelodysplasia had the most favourable outcomes. Late-onset graft-versus-host disease protected against relapse. In conclusion, a T-replete sequential transplantation using reduced-intensity conditioning is feasible for relapsed/refractory AML and myelodysplasia and can deliver graft-versus-leukaemia effects without DLI. © 2017 John Wiley & Sons Ltd.

Comparison of nitrogen depletion and repletion on lipid production in yeast and fungal species

DOE PAGES

Yang, Shihui; Wang, Wei; Wei, Hui; ...

2016-08-29

Although it is well known that low nitrogen stimulates lipid accumulation, especially for algae and some oleaginous yeast, few studies have been conducted in fungal species, especially on the impact of different nitrogen deficiency strategies. In this study, we use two promising consolidated bioprocessing (CBP) candidates to examine the impact of two nitrogen deficiency strategies on lipid production, which are the extensively investigated oleaginous yeast Yarrowia lipolytica, and the commercial cellulase producer Trichoderma reesei. We first utilized bioinformatics approaches to reconstruct the fatty acid metabolic pathway and demonstrated the presence of a triacylglycerol (TAG) biosynthesis pathway in Trichoderma reesei. Wemore » then examined the lipid production of Trichoderma reesei and Y. lipomyces in different media using two nitrogen deficiency strategies of nitrogen natural repletion and nitrogen depletion through centrifugation. Our results demonstrated that nitrogen depletion was better than nitrogen repletion with about 30% lipid increase for Trichoderma reesei and Y. lipomyces, and could be an option to improve lipid production in both oleaginous yeast and filamentous fungal species. The resulting distinctive lipid composition profiles indicated that the impacts of nitrogen depletion on yeast were different from those for fungal species. Under three types of C/N ratio conditions, C16 and C18 fatty acids were the predominant forms of lipids for both Trichoderma reesei and Y. lipolytica. In addition, while the overall fatty acid methyl ester (FAME) profiles of Trichoderma reesei were similar, the overall FAME profiles of Y. lipolytica observed a shift. The fatty acid metabolic pathway reconstructed in this work supports previous reports of lipid production in T. reesei, and provides a pathway for future omics studies and metabolic engineering efforts. Further investigation to identify the genetic targets responsible for the effect of nitrogen depletion

Comparison of nitrogen depletion and repletion on lipid production in yeast and fungal species

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Shihui; Wang, Wei; Wei, Hui

Although it is well known that low nitrogen stimulates lipid accumulation, especially for algae and some oleaginous yeast, few studies have been conducted in fungal species, especially on the impact of different nitrogen deficiency strategies. In this study, we use two promising consolidated bioprocessing (CBP) candidates to examine the impact of two nitrogen deficiency strategies on lipid production, which are the extensively investigated oleaginous yeast Yarrowia lipolytica, and the commercial cellulase producer Trichoderma reesei. We first utilized bioinformatics approaches to reconstruct the fatty acid metabolic pathway and demonstrated the presence of a triacylglycerol (TAG) biosynthesis pathway in Trichoderma reesei. Wemore » then examined the lipid production of Trichoderma reesei and Y. lipomyces in different media using two nitrogen deficiency strategies of nitrogen natural repletion and nitrogen depletion through centrifugation. Our results demonstrated that nitrogen depletion was better than nitrogen repletion with about 30% lipid increase for Trichoderma reesei and Y. lipomyces, and could be an option to improve lipid production in both oleaginous yeast and filamentous fungal species. The resulting distinctive lipid composition profiles indicated that the impacts of nitrogen depletion on yeast were different from those for fungal species. Under three types of C/N ratio conditions, C16 and C18 fatty acids were the predominant forms of lipids for both Trichoderma reesei and Y. lipolytica. In addition, while the overall fatty acid methyl ester (FAME) profiles of Trichoderma reesei were similar, the overall FAME profiles of Y. lipolytica observed a shift. The fatty acid metabolic pathway reconstructed in this work supports previous reports of lipid production in T. reesei, and provides a pathway for future omics studies and metabolic engineering efforts. Further investigation to identify the genetic targets responsible for the effect of nitrogen depletion

[Interaction among the trace elements zinc, copper and iron after depletion and repletion of dairy cows with zinc].

PubMed

Kirchgessner, M; Schwarz, F J; Roth, H P; Schwarz, W A

1978-12-01

Imbalances in the supply with trace elements may be caused by the excessive administration of one or several elements or the insufficient administration in relation to other trace elements. This article deals with the interactions between the trace elements zinc and copper resp. zinc and iron under the conditions of the insufficient supply with Zn (6 mg per kg dry matter of the fodder) and the supply according to the demand with other trace elements (14 mg copper resp. 83 mg iron per dry matter of the fodder). For this purpose we investigated the copper, iron and zinc content of the milk and the serum of cows that were first depleted of zinc through a semi-synthetic zinc deficiency diet and then repleted with extra allowances of zinc. The closest connections exist between the copper and zinc content of the milk. Thus extreme Zn-deficiency feeding conditions the decreased Zn-content on the one hand and increased Cu-content on the other. In contrast to this, the cows' Zn-excretion in the milk increases after Zn-repletion whereas the Cu-content decreases. This shows a distinctly negative correlation. A loose connection could only be detected for the Cu- and Zn-content of the serum. Though the Zn-content changed considerably in dependence on the Zn-supply, the Cu-content remained largely uninfluenced. The Fe-content of both milk and serum shows no interaction with the nutritive Zn-supply. Only after 19 test weeks of extreme Zn-deficiency could a slight increase of the Fe-concentration be indicated.

ACANTHAMOEBA SP.S-11 PHAGOCYTOTIC ACTIVITY ON MYCOBACTERIUM LEPRAE IN DIFFERENT NUTRIENT CONDITIONS.

PubMed

Paling, Sepling; Wahyuni, Ratna; Ni'matuzahroh; Winarni, Dwi; Iswahyudi; Astari, Linda; Adriaty, Dinar; Agusni, Indropo; Izumi, Shinzo

2018-01-01

Mycobacterium leprae ( M. leprae ) is a pathogenic bacterium that causes leprosy. The presence of M. leprae in the environment is supported by microorganisms that act as the new host for M. leprae . Acanthamoeba 's potential to be a host of M. leprae in the environment. Acanthamoeba sp. is Free Living Amoeba (FLA) that classified as holozoic, saprophytic, and saprozoic. The existence of nutrients in the environment influence Acanthamoeba ability to phagocytosis or pinocytosis. This study is aimed to determine Acanthamoeba sp.S-11 phagocytic activity to Mycobacterium leprae ( M. leprae ) which cultured in non-nutrient media and riched-nutrient media. This research conducted by culturing Acanthamoeba sp.S-11 and M. leprae on different nutrient media conditions. M. leprae intracellular DNA were isolated and amplified by M. leprae specific primers through Real Time PCR (Q-PCR). The results showed that Acanthamoeba co-cultured on non-nutrient media were more active to phagocyte M. leprae than on rich-nutrient media. The use of non-nutrient media is recommended to optimize Acanthamoeba sp. phagocytic activity to M. leprae .

Losses of nutrients and anti-nutrients in red and white sorghum cultivars after decorticating in optimised conditions.

PubMed

Galán, María Gimena; Llopart, Emilce Elina; Drago, Silvina Rosa

2018-05-01

The aims were to optimise pearling process of red and white sorghum by assessing the effects of pearling time and grain moisture on endosperm yield and flour ash content and to assess nutrient and anti-nutrient losses produced by pearling different cultivars in optimised conditions. Both variables significantly affected both responses. Losses of ashes (58%), proteins (9.5%), lipids (54.5%), Na (37%), Mg (48.5%) and phenolic compounds (43%) were similar among red and white hybrids. However, losses of P (30% vs. 51%), phytic acid (47% vs. 66%), Fe (22% vs. 55%), Zn (32% vs. 62%), Ca (60% vs. 66%), K (46% vs. 61%) and Cu (51% vs. 71%) were lower for red than white sorghum due to different degree of extraction and distribution of components in the grain. Optimised pearling conditions were extrapolated to other hybrids, indicating these criteria could be applied at industrial level to obtain refined flours with proper quality and good endosperm yields.

Ascorbic Acid Repletion: A Possible Therapy for Diabetic Macular Edema?

PubMed Central

May, James M.

2016-01-01

Macular edema poses a significant risk for visual loss in persons with diabetic retinopathy. It occurs when plasma constituents and fluid leak out of damaged retinal microvasculature in the area of the macula, causing loss of central vision. Apoptotic loss of pericytes surrounding capillaries is perhaps the earliest feature of diabetic vascular damage in the macula, which is also associated with dysfunction of the endothelium and loss of the otherwise very tight endothelial permeability barrier. Increased oxidative stress is a key feature of damage to both cell types, mediated by excess superoxide from glucose-induced increases in mitochondrial metabolism, as well as by activation of the receptor for advanced glycation end products (RAGE). The latter in turn activates multiple pathways, some of which lead to increased oxidative stress, such as those involving NF-κB, NADPH oxidase, and endothelial nitric oxide synthase. Such cellular oxidative stress is associated with low cellular and plasma ascorbic acid levels in many subjects with diabetes in poor glycemic control. Whether repletion of low ascorbate in retinal endothelium and pericytes might help to prevent diabetic macular edema is unknown. However, cell culture studies show that the vitamin prevents high-glucose and RAGE-induced apoptosis in both cell types, that it preserves nitric oxide generated by endothelial cells, and that it tightens the leaky endothelial permeability barrier. Although these findings need to be confirmed in pre-clinical animal studies, it is worth considering clinical trials to determine whether adequate ascorbate repletion is possible and whether it might help to delay or even reverse early diabetic macular edema. PMID:26898503

Alachlor transformation patterns in aquatic field mesocosms under variable oxygen and nutrient conditions

USGS Publications Warehouse

Graham, D.W.; Miley, M.K.; Denoyelles, F.; Smith, Val H.; Thurman, E.M.; Carter, R.

2000-01-01

Alachlor is one of the most commonly used herbicides in both Europe and North America. Because of its toxic properties, its fate and attenuation in natural waters is practically important. This paper assesses factors that affect alachlor decay rate in aquatic systems using field-scale experimental units. In particular, we used field mesocosms (11.3 m3 outdoor fiberglass tanks) to examine the affect of oxygen level and other factors on decay rate in water columns. This is one of the first studies ever performed where diverse water column conditions have been successfully simulated using common mesocosm-scale facilities. Four treatments were assessed, including aerobic systems (aerobic); low nutrient, oxygen-stratified systems (stratified-LN); moderate nutrient, oxygen-stratified systems (stratified-HN); and anaerobic systems (anaerobic). The lowest half-lives were observed in the anaerobic units (9.7 days) followed by the aerobic (21 days), stratified-HN (22 days), and stratified-LN (46 days) units. Our results indicate that alachlor is transformed most rapidly under anaerobic conditions, although the ambient phosphorus level also appears to influence decay rate. In this study, two common alachlor breakdown products, ethane sulfonic acid (ESA) and oxanilic acid, were also monitored. Oxanilic acid was produced in greater quantities than ESA under all treatments with the highest levels being produced in the stratified-HN units. In general, our results suggest that previous laboratory data, which indicated that high rates of alachlor decay can occur under oxygen-free methanogenic conditions, is translatable to field-scale applications. Copyright (C) 2000 Elsevier Science Ltd.Alachlor is one of the most commonly used herbicides in both Europe and North America. Because of its toxic properties, its fate and attenuation in natural waters is practically important. This paper assesses factors that affect alachlor decay rate in aquatic systems using field-scale experimental

Supplemental levels of iron and calcium interfere with repletion of zinc status in zinc-deficient animals.

PubMed

Jayalakshmi, S; Platel, Kalpana

2016-05-18

Negative interactions between minerals interfering with each other's absorption are of concern when iron and calcium supplements are given to pregnant women and children. We have previously reported that supplemental levels of iron and calcium inhibit the bioaccessibility of zinc, and compromise zinc status in rats fed diets with high levels of these two minerals. The present study examined the effect of supplemental levels of iron and calcium on the recovery of zinc status during a zinc repletion period in rats rendered zinc-deficient. Iron and calcium, both individually and in combination, significantly interfered with the recovery of zinc status in zinc deficient rats during repletion with normal levels of zinc in the diet. Rats maintained on diets containing supplemental levels of these two minerals had significantly lower body weight, and the concentration of zinc in serum and organs was significantly lower than in zinc-deficient rats not receiving the supplements. Iron and calcium supplementation also significantly inhibited the activity of zinc-containing enzymes in the serum as well as liver. Both iron and calcium independently exerted this negative effect on zinc status, while their combination seemed to have a more prominent effect, especially on the activities of zinc containing enzymes. This investigation is probably the first systematic study on the effect of these two minerals on the zinc status of zinc deficient animals and their recovery during repletion with normal amounts of zinc.

Boosted Regression Tree Models to Explain Watershed Nutrient Concentrations and Biological Condition

EPA Science Inventory

Boosted regression tree (BRT) models were developed to quantify the nonlinear relationships between landscape variables and nutrient concentrations in a mesoscale mixed land cover watershed during base-flow conditions. Factors that affect instream biological components, based on ...

Integrating themes, evidence gaps, and research needs identified by workshop on iron screening and supplementation in iron-replete pregnant women and young children.

PubMed

Brannon, Patsy M; Stover, Patrick J; Taylor, Christine L

2017-12-01

This report addresses the evidence and the uncertainties, knowledge gaps, and research needs identified by participants at the NIH workshop related to iron screening and routine iron supplementation of largely iron-replete pregnant women and young children (6-24 mo) in developed countries. The workshop presentations and panel discussions focused on current understanding and knowledge gaps related to iron homeostasis, measurement of and evidence for iron status, and emerging concerns about supplementing iron-replete members of these vulnerable populations. Four integrating themes emerged across workshop presentations and discussion and centered on 1 ) physiologic or developmental adaptations of iron homeostasis to pregnancy and early infancy, respectively, and their implications, 2 ) improvement of the assessment of iron status across the full continuum from iron deficiency anemia to iron deficiency to iron replete to iron excess, 3 ) the linkage of iron status with health outcomes beyond hematologic outcomes, and 4 ) the balance of benefit and harm of iron supplementation of iron-replete pregnant women and young children. Research that addresses these themes in the context of the full continuum of iron status is needed to inform approaches to the balancing of benefits and harms of screening and routine supplementation. © 2017 American Society for Nutrition.

Shoot Development and Extension of Quercus serrata Saplings in Response to Insect Damage and Nutrient Conditions

PubMed Central

MIZUMACHI, ERI; MORI, AKIRA; OSAWA, NAOYA; AKIYAMA, REIKO; TOKUCHI, NAOKO

2006-01-01

• Background and Aims Plants have the ability to compensate for damage caused by herbivores. This is important to plant growth, because a plant cannot always avoid damage, even if it has developed defence mechanisms against herbivores. In previous work, we elucidated the herbivory-induced compensatory response of Quercus (at both the individual shoot and whole sapling levels) in both low- and high-nutrient conditions throughout one growing season. In this study, we determine how the compensatory growth of Quercus serrata saplings is achieved at different nutrient levels. • Methods Quercus serrata saplings were grown under controlled conditions. Length, number of leaves and percentage of leaf area lost on all extension units (EUs) were measured. • Key Results Both the probability of flushing and the length of subsequent EUs significantly increased with an increase in the length of the parent EU. The probability of flushing increased with an increase in leaf damage of the parent EU, but the length of subsequent EUs decreased. This indicates that EU growth is fundamentally regulated at the individual EU level. The probabilities of a second and third flush were significantly higher in plants in high-nutrient soil than those in low-nutrient soil. The subsequent EUs of damaged saplings were also significantly longer at high-nutrient conditions. • Conclusions An increase in the probability of flushes in response to herbivore damage is important for damaged saplings to produce new EUs; further, shortening the length of EUs helps to effectively reproduce foliage lost by herbivory. The probability of flushing also varied according to soil nutrient levels, suggesting that the compensatory growth of individual EUs in response to local damage levels is affected by the nutrients available to the whole sapling. PMID:16709576

C4 Photosynthesis in the Rice Paddy: Insights from the Noxious Weed Echinochloa glabrescens1[OPEN

PubMed Central

Covshoff, Sarah; Szecowka, Marek; Hughes, Thomas E.; Kelly, Steven; Bailey, Karen J.; Sage, Tammy L.; Pachebat, Justin A.; Leegood, Richard

2016-01-01

The C4 pathway is a highly complex trait that increases photosynthetic efficiency in more than 60 plant lineages. Although the majority of C4 plants occupy disturbed, arid, and nutrient-poor habitats, some grow in high-nutrient, waterlogged conditions. One such example is Echinochloa glabrescens, which is an aggressive weed of rice paddies. We generated comprehensive transcriptome datasets for C4 E. glabrescens and C3 rice to identify genes associated with adaption to waterlogged, nutrient-replete conditions, but also used the data to better understand how C4 photosynthesis operates in these conditions. Leaves of E. glabrescens exhibited classical Kranz anatomy with lightly lobed mesophyll cells having low chloroplast coverage. As with rice and other hygrophytic C3 species, leaves of E. glabrescens accumulated a chloroplastic phosphoenolpyruvate carboxylase protein, albeit at reduced amounts relative to rice. The arid-grown species Setaria italica (C4) and Brachypodium distachyon (C3) were also found to accumulate chloroplastic phosphoenolpyruvate carboxylase. We identified a molecular signature associated with C4 photosynthesis in nutrient-replete, waterlogged conditions that is highly similar to those previously reported from C4 plants that grow in more arid conditions. We also identified a cohort of genes that have been subjected to a selective sweep associated with growth in paddy conditions. Overall, this approach highlights the value of using wild species such as weeds to identify adaptions to specific conditions associated with high-yielding crops in agriculture. PMID:26527656

Profiles of selected nutrients affecting skin condition in children with atopic dermatitis.

PubMed

Strucińska, Małgorzata; Rowicka, Grażyna; Riahi, Agnieszka

2015-01-01

Atopic dermatitis (AD) is a chronic inflammation of the skin recognised to be one of the first clinical signs of allergy. In the first years of life, epidemiological evidence has demonstrated that common causative foods of a child's diet are: cow's milk, hen's eggs, wheat and soya. Children with AD being treated with elimination diets are at risk of nutritional deficiencies that include those nutrients required for ensuring proper skin structure and function. The aim of the study was to assess dietary intake of nutrients which affect skin condition in children with AD being treated with a milk-free diet. Subjects were 25 children aged 4-6 years with AD undergoing the milk exclusion diet and 25 age-matched healthy controls. The energy and nutritional value of diets were evaluated that included those components affecting skin condition; ie. vitamins A, D, E, B2 and C; minerals iron (Fe) and zinc (Zn); polyunsaturated fatty acids (PUFAs). The Dieta 5.0 programme was used for dietary assessment and outcomes were then related to dietary recommendations. There were no significant differences between groups in mean energy values and mean intakes of protein, fats and carbohydrates (p>0.05). The percentage of subjects with low energy value were 44% and 36% in respectively Groups I and II. Deficiencies of fat intake were observed in 60% in Group I and 44% in Group II. There were however no risks in the dietary intakes of protein, carbohydrate, vitamins A, B2 and C nor of Fe and Zn. Deficiencies of dietary intakes were observed in respectively Groups I and II in the following; vitamin E (24% vs 64%), vitamin D (36% vs 92%), linoleic acid (36% vs 72%), α-linolenic acid (36% vs 40%) and long chain PUFAs (96% in both groups). Ensuring recommended dietary supply of those nutrients affecting skin condition is required for both groups of children. Children with AD had better balanced diets in respect of the studied nutrients that may reflect the influence of continuous healthcare

Mycobacterium fortuitum and Mycobacterium chelonae biofilm formation under high and low nutrient conditions.

PubMed

Hall-Stoodley, L; Keevil, C W; Lappin-Scott, H M

1998-12-01

The rapidly growing mycobacteria (RGM) are broadly disbursed in the environment. They have been recovered from freshwater, seawater, wastewater and even potable water samples and are increasingly associated with non-tuberculous mycobacterial disease. There is scant evidence that non-tuberculous mycobacteria (NTM) and RGM form biofilms. Therefore, an experimental system was designed to assess the ability of RGM to form biofilms under controlled laboratory conditions. A flat plate reactor flow cell was attached to either a high or low nutrient reservoir and monitored by image analysis over time. Two surfaces were chosen for assessment of biofilm growth: silastic which is commonly used in medical settings and high density polyethylene (HDPE) which is prevalent in water distribution systems. The results show that Mycobacterium fortuitum and M. chelonae formed biofilms under both high and low nutrient conditions on both surfaces studied. These results suggest that RGM may form biofilms under a variety of conditions in industrial and medical environments. 1998 Society of Applied Microbiology.

Variation in elemental stoichiometry of the marine diatom Thalassiosira weissflogii (Bacillariophyceae) in response to combined nutrient stress and changes in carbonate chemistry.

PubMed

Clark, Darren R; Flynn, Kevin J; Fabian, Heiner

2014-08-01

The combined consequences of the multi-stressors of pH and nutrient availability upon the growth of a marine diatom were investigated. Thalassiosira weissflogii was grown in N- or P-limited batch culture in sealed systems, with pH commencing at 8.2 ("extant" conditions) or 7.6 ("ocean acidification" [OA] conditions), and then pH was allowed to either drift with growth, or was held fixed. Results indicated that within the pH range tested, the stability of environmental pH rather than its value (i.e., OA vs. extant) fundamentally influenced biomass accumul-ation and C:N:P stoichiometry. Despite large changes in total alkalinity in the fixed pH systems, final biomass production was consistently greater in these systems than that in drifting pH systems. In drift systems, pH increased to exceed pH 9.5, a level of alkalinity that was inhibitory to growth. No statis-tically significant differences between pH treatments were measured for N:C, P:C or N:P ratios during nutrient-replete growth, although the diatom expre-ssed greater plasticity in P:C and N:P ratios than in N:C during this growth phase. During nutrient-deplete conditions, the capacity for uncoupled carbon fixa-tion at fixed pH was considerably greater than that measured in drift pH systems, leading to strong contrasts in C:N:P stoichiometry between these treatments. Whether environmental pH was stable or drifted directly influenced the extent of physiological stress. In contrast, few distinctions could be drawn between "extant" versus "OA" conditions for cell physiology. © 2014 The Authors. Journal of Phycology published by Wiley Periodicals, Inc. on behalf of Phycological Society of America.

Enhanced flavor-nutrient conditioning in obese rats on a high-fat, high-carbohydrate choice diet.

PubMed

Wald, Hallie S; Myers, Kevin P

2015-11-01

Through flavor-nutrient conditioning rats learn to prefer and increase their intake of flavors paired with rewarding, postingestive nutritional consequences. Since obesity is linked to altered experience of food reward and to perturbations of nutrient sensing, we investigated flavor-nutrient learning in rats made obese using a high fat/high carbohydrate (HFHC) choice model of diet-induced obesity (ad libitum lard and maltodextrin solution plus standard rodent chow). Forty rats were maintained on HFHC to induce substantial weight gain, and 20 were maintained on chow only (CON). Among HFHC rats, individual differences in propensity to weight gain were studied by comparing those with the highest proportional weight gain (obesity prone, OP) to those with the lowest (obesity resistant, OR). Sensitivity to postingestive food reward was tested in a flavor-nutrient conditioning protocol. To measure initial, within-meal stimulation of flavor acceptance by post-oral nutrient sensing, first, in sessions 1-3, baseline licking was measured while rats consumed grape- or cherry-flavored saccharin accompanied by intragastric (IG) water infusion. Then, in the next three test sessions they received the opposite flavor paired with 5 ml of IG 12% glucose. Finally, after additional sessions alternating between the two flavor-infusion contingencies, preference was measured in a two-bottle choice between the flavors without IG infusions. HFHC-OP rats showed stronger initial enhancement of intake in the first glucose infusion sessions than CON or HFHC-OR rats. OP rats also most strongly preferred the glucose-paired flavor in the two-bottle choice. These differences between OP versus OR and CON rats suggest that obesity is linked to responsiveness to postoral nutrient reward, consistent with the view that flavor-nutrient learning perpetuates overeating in obesity. Copyright © 2015 Elsevier Inc. All rights reserved.

The human serum metabolome of vitamin B-12 deficiency and repletion, and associations with neurological function

USDA-ARS?s Scientific Manuscript database

We characterize the human serum metabolome in sub-clinical vitamin B-12 (B-12) deficiency and repletion. A pre-post treatment study provided one injection of 10 mg B-12 to 27 community-dwelling elderly Chileans with B-12 deficiency evaluated with serum B-12, plasma homocysteine, methylmalonic acid a...

A Nested Nearshore Nutrient Model (N&Sup3;M) for Nearshore Condition Assessment and Management

EPA Science Inventory

Nearshore conditions drive phenomena like harmful algal blooms (HABs), and the nearshore and coastal margin are the parts of the Great Lakes most used by humans. To assess conditions, optimize monitoring, and evaluate management options, a model of nearshore nutrient transport an...

Pseudomonas fluorescens transportome is linked to strain-specific plant growth promotion in Aspen seedlings under nutrient stress

DOE PAGES

Shinde, Shalaka; Cumming, Jonathan R.; Collart, Frank R.; ...

2017-03-21

Diverse communities of bacteria colonize plant roots and the rhizosphere. Many of these rhizobacteria are symbionts and provide plant growth promotion (PGP) services, protecting the plant from biotic and abiotic stresses and increasing plant productivity by providing access to nutrients that would otherwise be unavailable to roots. In return, these symbiotic bacteria receive photosynthetically-derived carbon (C), in the form of sugars and organic acids, from plant root exudates. PGP activities have been characterized for a variety of forest tree species and are important in C cycling and sequestration in terrestrial ecosystems. The molecular mechanisms of these PGP activities, however, aremore » less well-known. In a previous analysis of Pseudomonas genomes, we found that the bacterial transportome, the aggregate activity of a bacteria's transmembrane transporters, was most predictive for the ecological niche of Pseudomonads in the rhizosphere. Here, we used Populus tremuloides Michx. (trembling aspen) seedlings inoculated with one of three Pseudomonas fluorescens strains (Pf0-1, SBW25, and WH6) and one Pseudomonas protegens (Pf-5) as a laboratory model to further investigate the relationships between the predicted transportomic capacity of a bacterial strain and its observed PGP effects in laboratory cultures. Conditions of low nitrogen (N) or low phosphorus (P) availability and the corresponding replete media conditions were investigated. We measured phenotypic and biochemical parameters of P. tremuloides seedlings and correlated P fluorescens strain-specific transportomic capacities with P. tremuloides seedling phenotype to predict the strain and nutrient environment-specific transporter functions that lead to experimentally observed, strain, and media-specific PGP activities and the capacity to protect plants against nutrient stress. These predicted transportomic functions fall in three groups: (i) transport of compounds that modulate aspen seedling root

Pseudomonas fluorescens transportome is linked to strain-specific plant growth promotion in Aspen seedlings under nutrient stress

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shinde, Shalaka; Cumming, Jonathan R.; Collart, Frank R.

Diverse communities of bacteria colonize plant roots and the rhizosphere. Many of these rhizobacteria are symbionts and provide plant growth promotion (PGP) services, protecting the plant from biotic and abiotic stresses and increasing plant productivity by providing access to nutrients that would otherwise be unavailable to roots. In return, these symbiotic bacteria receive photosynthetically-derived carbon (C), in the form of sugars and organic acids, from plant root exudates. PGP activities have been characterized for a variety of forest tree species and are important in C cycling and sequestration in terrestrial ecosystems. The molecular mechanisms of these PGP activities, however, aremore » less well-known. In a previous analysis of Pseudomonas genomes, we found that the bacterial transportome, the aggregate activity of a bacteria's transmembrane transporters, was most predictive for the ecological niche of Pseudomonads in the rhizosphere. Here, we used Populus tremuloides Michx. (trembling aspen) seedlings inoculated with one of three Pseudomonas fluorescens strains (Pf0-1, SBW25, and WH6) and one Pseudomonas protegens (Pf-5) as a laboratory model to further investigate the relationships between the predicted transportomic capacity of a bacterial strain and its observed PGP effects in laboratory cultures. Conditions of low nitrogen (N) or low phosphorus (P) availability and the corresponding replete media conditions were investigated. We measured phenotypic and biochemical parameters of P. tremuloides seedlings and correlated P fluorescens strain-specific transportomic capacities with P. tremuloides seedling phenotype to predict the strain and nutrient environment-specific transporter functions that lead to experimentally observed, strain, and media-specific PGP activities and the capacity to protect plants against nutrient stress. These predicted transportomic functions fall in three groups: (i) transport of compounds that modulate aspen seedling root

Centrosome misorientation mediates slowing of the cell cycle under limited nutrient conditions in Drosophila male germline stem cells

PubMed Central

Roth, Therese M.; Chiang, C.-Y. Ason; Inaba, Mayu; Yuan, Hebao; Salzmann, Viktoria; Roth, Caitlin E.; Yamashita, Yukiko M.

2012-01-01

Drosophila male germline stem cells (GSCs) divide asymmetrically, balancing self-renewal and differentiation. Although asymmetric stem cell division balances between self-renewal and differentiation, it does not dictate how frequently differentiating cells must be produced. In male GSCs, asymmetric GSC division is achieved by stereotyped positioning of the centrosome with respect to the stem cell niche. Recently we showed that the centrosome orientation checkpoint monitors the correct centrosome orientation to ensure an asymmetric outcome of the GSC division. When GSC centrosomes are not correctly oriented with respect to the niche, GSC cell cycle is arrested/delayed until the correct centrosome orientation is reacquired. Here we show that induction of centrosome misorientation upon culture in poor nutrient conditions mediates slowing of GSC cell proliferation via activation of the centrosome orientation checkpoint. Consistently, inactivation of the centrosome orientation checkpoint leads to lack of cell cycle slowdown even under poor nutrient conditions. We propose that centrosome misorientation serves as a mediator that transduces nutrient information into stem cell proliferation, providing a previously unappreciated mechanism of stem cell regulation in response to nutrient conditions. PMID:22357619

Establishment of stream nutrient criteria by comparing reference conditions with ecological thresholds in a typical eutrophic lake basin.

PubMed

Cao, Xiaofeng; Wang, Jie; Jiang, Dalin; Sun, Jinhua; Huang, Yi; Luan, Shengji

2017-12-13

The establishment of numeric nutrient criteria is essential to aid the control of nutrient pollution and for protecting and restoring healthy ecological conditions. However, it's necessary to determine whether regional nutrient criteria can be defined in stream ecosystems with a poor ecological status. A database of periphytic diatom samples was collected in July and August 2011 and 2012. In total 172 samples were included in the database with matching environmental variables. Here, percentile estimates, nonparametric change-point analysis (nCPA) and Threshold Indicator Taxa ANalysis (TITAN) were conducted to detect the reference conditions and ecological thresholds along a total nitrogen (TN) and total phosphorus (TP) gradient and ammonia nitrogen (NH 3 -N) for the development of nutrient criteria in the streams of the Lake Dianchi basin. The results highlighted the possibility of establishing regional criteria for nutrient concentrations, which we recommended to be no more than 1.39 mg L -1 for TN, 0.04 mg L -1 for TP and 0.17 mg L -1 for NH 3 -N to prevent nuisance growths of tolerant taxa, and 0.38 mg L -1 for TN, 0.02 mg L -1 for TP and 0.02 mg L -1 for NH 3 -N to maintain high quality waters in streams. Additionally, the influence of excessive background nutrient enrichment on the threshold response, and the ecological interaction with other stressors (HQI, etc.) in the nutrient dynamic process need to be considered to establish the eventual nutrient criteria, regardless of which technique is applied.

Nematodes enhance plant growth and nutrient uptake under C and N-rich conditions.

PubMed

Gebremikael, Mesfin T; Steel, Hanne; Buchan, David; Bert, Wim; De Neve, Stefaan

2016-09-08

The role of soil fauna in crucial ecosystem services such as nutrient cycling remains poorly quantified, mainly because of the overly reductionistic approach adopted in most experimental studies. Given that increasing nitrogen inputs in various ecosystems influence the structure and functioning of soil microbes and the activity of fauna, we aimed to quantify the role of the entire soil nematode community in nutrient mineralization in an experimental set-up emulating nutrient-rich field conditions and accounting for crucial interactions amongst the soil microbial communities and plants. To this end, we reconstructed a complex soil foodweb in mesocosms that comprised largely undisturbed native microflora and the entire nematode community added into defaunated soil, planted with Lolium perenne as a model plant, and amended with fresh grass-clover residues. We determined N and P availability and plant uptake, plant biomass and abundance and structure of the microbial and nematode communities during a three-month incubation. The presence of nematodes significantly increased plant biomass production (+9%), net N (+25%) and net P (+23%) availability compared to their absence, demonstrating that nematodes link below- and above-ground processes, primarily through increasing nutrient availability. The experimental set-up presented allows to realistically quantify the crucial ecosystem services provided by the soil biota.

Nematodes enhance plant growth and nutrient uptake under C and N-rich conditions

NASA Astrophysics Data System (ADS)

Gebremikael, Mesfin T.; Steel, Hanne; Buchan, David; Bert, Wim; de Neve, Stefaan

2016-09-01

The role of soil fauna in crucial ecosystem services such as nutrient cycling remains poorly quantified, mainly because of the overly reductionistic approach adopted in most experimental studies. Given that increasing nitrogen inputs in various ecosystems influence the structure and functioning of soil microbes and the activity of fauna, we aimed to quantify the role of the entire soil nematode community in nutrient mineralization in an experimental set-up emulating nutrient-rich field conditions and accounting for crucial interactions amongst the soil microbial communities and plants. To this end, we reconstructed a complex soil foodweb in mesocosms that comprised largely undisturbed native microflora and the entire nematode community added into defaunated soil, planted with Lolium perenne as a model plant, and amended with fresh grass-clover residues. We determined N and P availability and plant uptake, plant biomass and abundance and structure of the microbial and nematode communities during a three-month incubation. The presence of nematodes significantly increased plant biomass production (+9%), net N (+25%) and net P (+23%) availability compared to their absence, demonstrating that nematodes link below- and above-ground processes, primarily through increasing nutrient availability. The experimental set-up presented allows to realistically quantify the crucial ecosystem services provided by the soil biota.

Arbuscular mycorrhizas enhance nutrient uptake in different wheat genotypes at high salinity levels under field and greenhouse conditions.

PubMed

Mardukhi, Baran; Rejali, Farhad; Daei, Gudarz; Ardakani, Mohammad Reza; Malakouti, Mohammad Javad; Miransari, Mohammad

2011-07-01

Since most experiments regarding the symbiosis between arbuscular mycorrhizal (AM) fungi and their host plants under salinity stress have been performed only under greenhouse conditions, this research work was also conducted under field conditions. The effects of three AM species including Glomus mosseae, G. etunicatum and G. intraradices on the nutrient uptake of different wheat cultivars (including Roshan, Kavir and Tabasi) under field and greenhouse (including Chamran and Line 9) conditions were determined. At field harvest, the concentrations of N, Ca, Mg, Fe, Cu, and Mn, and at greenhouse harvest, plant growth, root colonization and concentrations of different nutrients including N, K, P, Ca, Mg, Mn, Cu, Fe, Zn, Na and Cl were determined. The effects of wheat cultivars on the concentrations of N, Ca, and Mn, and of all nutrients were significant at field and greenhouse conditions, respectively. In both experiments, AM fungi significantly enhanced the concentrations of all nutrients including N, K, P, Ca, Mg, Mn, Cu, Fe, Zn, Na and Cl. The synergistic and enhancing effects of co-inoculation of AM species on plant growth and the inhibiting effect of AM species on Na(+) rather than on Cl(-) uptake under salinity are also among the important findings of this research work. Copyright © 2011 Académie des sciences. Published by Elsevier SAS. All rights reserved.

Antarctic Ocean Nutrient Conditions During the Last Two Glacial Cycles

NASA Astrophysics Data System (ADS)

Studer, A.; Sigman, D. M.; Martinez-Garcia, A.; Benz, V.; Winckler, G.; Kuhn, G.; Esper, O.; Lamy, F.; Jaccard, S.; Wacker, L.; Oleynik, S.; Gersonde, R.; Haug, G. H.

2014-12-01

The high concentration of the major nutrients nitrate and phosphate in the Antarctic Zone of the Southern Ocean dictates the nature of Southern Ocean ecosystems and permits these nutrients to be carried from the deep ocean into the nutrient-limited low latitudes. Incomplete nutrient consumption in the Antarctic also allows the leakage of deeply sequestered carbon dioxide (CO2) back to the atmosphere, and changes in this leakage may have driven glacial/interglacial cycles in atmospheric CO2. In a sediment core from the Pacific sector of the Antarctic Ocean, we report diatom-bound N isotope (δ15Ndb) records for total recoverable diatoms and two assemblages of diatom species. These data indicate tight coupling between the degree of nitrate consumption and Antarctic climate across the last two glacial cycles, with δ15Ndb (and thus the degree of nitrate consumption) increasing at each major Antarctic cooling event. Measurements in the same sediment core indicate that export production was reduced during ice ages, pointing to an ice age reduction in the supply of deep ocean-sourced nitrate to the Antarctic Ocean surface. The reduced export production of peak ice ages also implies a weaker winter-to-summer decline (i.e. reduced seasonality) in mixed layer nitrate concentration, providing a plausible explanation for an observed reduction in the inter-assemblage δ15Ndb difference during these coldest times. Despite the weak summertime productivity, the reduction in wintertime nitrate supply from deep waters left the Antarctic mixed layer with a low nitrate concentration, and this wintertime change also would have reduced the outgassing of CO2. Relief of light limitation fails to explain the intermediate degree of nitrate consumption that characterizes early glacial conditions, as improved light limitation coincident with reduced nitrate supply would drive nitrate consumption to completion. Thus, the data favor iron availability as the dominant control on annual Antarctic

Connecting the dots in the Gulf of the Farallones: linking physical ocean conditions and nutrients to the ecological success of planktivorous predators

NASA Astrophysics Data System (ADS)

Hartnett, R. J.; Jahncke, J.; Wilkerson, F. P.; Nielsen, K. J.; Nur, N.

2016-02-01

Nutrients are essential for phytoplankton to thrive and drive bottom-up forcing of ecosystem production. Upwelling of deep water from the shelf break delivers pulses of nutrients resulting in recurring blooms of phytoplankton and zooplankton in the Gulf of the Farallones (GoF) region of the California Current Ecosystem, supporting a diversity of pelagic predators. Anomalies in ocean conditions are often associated with booms and crashes of these predator populations, such as the recent mortality of thousands of Cassin's Auklets. These anomalies are often associated with changes in physical conditions affecting the Pacific Ocean, as well as more localized physical conditions along the California coastline that drive nutrient availability, but the specific role of nutrients in driving the abundances of top predators has not been directly examined. Using a ten-year multivariate time series from the GoF, including nutrient concentrations, we test the hypothesis that nutrients regulate the abundance of plankton and planktivorous predators, as a result of physical forcing. Using path analysis we test alternate interaction webs, including the direct and indirect effects of physical and biological factors on pelagic predator abundances. Insights from this work may be useful to marine resource managers in understanding how future variability in ocean conditions may drive ecosystem conditions including the abundance of pelagic predators in the GoF Marine Sanctuary.

Placentomal differentiation may compensate for maternal nutrient restriction in ewes adapted to harsh range conditions.

PubMed

Vonnahme, K A; Hess, B W; Nijland, M J; Nathanielsz, P W; Ford, S P

2006-12-01

Maternal nutrient restriction from early to midgestation can lead to fetal growth retardation, with long-term impacts on offspring growth, physiology, and metabolism. We hypothesized that ewes from flocks managed under markedly different environmental conditions and levels of nutrition might differ in their ability to protect their own fetus from a bout of maternal nutrient restriction. We utilized multiparous ewes of similar breeding, age, and parity from 2 flocks managed as 1) ewes adapted to a nomadic existence and year-long, limited nutrition near Baggs, WY (Baggs ewes), and 2) University of Wyoming ewes with a sedentary lifestyle and continuous provision of more than adequate nutrition (UW ewes). Groups of Baggs ewes and UW ewes were fed 50 (nutrient restricted) or 100% (control fed) of National Research Council recommendations from d 28 to 78 of gestation, then necropsied, and fetal and placental data were obtained. Although there was a marked decrease (P < 0.05) in fetal weight and blood glucose concentrations in nutrient-restricted vs. control fed UW ewes, there was no difference in these fetal measurements between nutrient-restricted and control-fed Baggs ewes. Nutrient-restricted and control-fed UW ewes exhibited predominantly type A placentomes on d 78, but there were fewer (P c0.05) type A and greater (P < 0.05) numbers of type B, C, and D placentomes in nutrient-restricted than control-fed Baggs ewes. Placental efficiency (fetal weight/placentomal weight) was reduced (P = 0.04) in d 78 nutrient-restricted UW ewes when compared with control-fed UW ewes. In contrast, nutrient-restricted and control-fed Baggs ewes exhibited similar placental efficiencies on d 78. This is the first report of different placental responses to a nutritional challenge during pregnancy when ewes were selected under different management systems. These data are consistent with the concept that Baggs ewes or their conceptuses, which were adapted to both harsh environments and

Imbalanced nutrient regimes increase Prymnesium parvum resilience to herbicide exposure.

PubMed

Flood, Stacie L; Burkholder, JoAnn M

2018-05-01

The toxigenic haptophyte Prymnesium parvum is a mixotrophic phytoplankter with an extensive historic record of forming nearly monospecific, high-biomass, ecosystem-disrupting blooms, and it has been responsible for major fish kills in brackish waters and aquaculture facilities in many regions of the world. Little is known about how this species responds to commonly occurring environmental contaminants, or how nutrient (nitrogen, phosphorus) pollution may interact with environmentally relevant pesticide exposures to affect this harmful algal species. Here, standard algal toxicity bioassays from pesticide hazard assessments were used along with modified erythrocyte lysis assays to evaluate how atrazine exposures, imbalanced nutrient supplies, and salinity interact to influence the growth and toxicity in P. parvum isolates from three different regions. In nutrient-replete media, P. parvum 96 h IC 50 s ranged from 73.0 to 88.3 μg atrazine L -1 at salinity 10 and from 118 to >200 μg atrazine μg L -1 at salinity 20, and the response depended on the strain and the test duration. Relative hemolytic activity, used as an indication of toxicity, was a function of herbicide exposure, nutrient availability, salinity, geographic origin, and interactions among these factors. Highest levels of hemolytic activity were measured from a South Carolina strain in low-nitrogen media with high atrazine concentrations. Herbicide concentration was related to relative hemolytic activity, although a consistent relationship between growth phase and toxicity was not observed. Overall, these findings suggest that increasing chemical contamination is helping to promote ecosystem-disruptive, strongly mixotrophic algal blooms. Copyright © 2018 Elsevier B.V. All rights reserved.

In Vivo Kinetics of Formate Metabolism in Folate-deficient and Folate-replete Rats*

PubMed Central

Morrow, Gregory P.; MacMillan, Luke; Lamarre, Simon G.; Young, Sara K.; MacFarlane, Amanda J.; Brosnan, Margaret E.; Brosnan, John T.

2015-01-01

It is now established that the mitochondrial production of formate is a major process in the endogenous generation of folate-linked one-carbon groups. We have developed an in vivo approach involving the constant infusion of [13C]formate until isotopic steady state is attained to measure the rate of endogenous formate production in rats fed on either a folate-replete or folate-deficient diet. Formate was produced at a rate of 76 μmol·h−1·100 g of body weight−1 in the folate-replete rats, and this was decreased by 44% in folate-deficient rats. This decreased formate production was confirmed in isolated rat liver mitochondria where formate production from serine, the principal precursor of one-carbon groups, was decreased by 85%, although formate production from sarcosine and dimethylglycine (choline metabolites) was significantly increased. We attribute this unexpected result to the demonstrated production of formaldehyde by sarcosine dehydrogenase and dimethylglycine dehydrogenase from their respective substrates in the absence of tetrahydrofolate and subsequent formation of formate by formaldehyde dehydrogenase. Comparison of formate production with the ingestion of dietary formate precursors (serine, glycine, tryptophan, histidine, methionine, and choline) showed that ∼75% of these precursors were converted to formate, indicating that formate is a significant, although underappreciated end product of choline and amino acid oxidation. Ingestion of a high protein diet did not result in increased production of formate, suggesting a regulation of the conversion of these precursors at the mitochondrial level to formate. PMID:25480787

Application of the SPARROW model to assess surface-water nutrient conditions and sources in the United States Pacific Northwest

USGS Publications Warehouse

Wise, Daniel R.; Johnson, Henry M.

2013-01-01

The watershed model SPARROW (Spatially Referenced Regressions on Watershed attributes) was used to estimate mean annual surface-water nutrient conditions (total nitrogen and total phosphorus) and to identify important nutrient sources in catchments of the Pacific Northwest region of the United States for 2002. Model-estimated nutrient yields were generally higher in catchments on the wetter, western side of the Cascade Range than in catchments on the drier, eastern side. The largest source of locally generated total nitrogen stream load in most catchments was runoff from forestland, whereas the largest source of locally generated total phosphorus stream load in most catchments was either geologic material or livestock manure (primarily from grazing livestock). However, the highest total nitrogen and total phosphorus yields were predicted in the relatively small number of catchments where urban sources were the largest contributor to local stream load. Two examples are presented that show how SPARROW results can be applied to large rivers—the relative contribution of different nutrient sources to the total nitrogen load in the Willamette River and the total phosphorus load in the Snake River. The results from this study provided an understanding of the regional patterns in surface-water nutrient conditions and should be useful to researchers and water-quality managers performing local nutrient assessments.

Effects of Nutrient Dynamics, Light and Temperature on the Patchiness of Phytoplankton and Primary Production in the Estuarine and Coastal Zones of Liaodong Bay, China: A Typical Case Study

NASA Astrophysics Data System (ADS)

Pei, S.; Laws, E. A.; Ye, S.

2017-12-01

Fluvial inputs of nutrients and efficient nutrient recycling mechanisms make estuarine and coastal zones highly productive bodies of water. For the same reasons, they are susceptible to eutrophication problems. In China, eutrophication problems along coasts are becoming serious because of discharges of domestic sewage and industrial wastewater and runoff of agricultural fertilizer. Addressing these problems requires an informed assessment of the factors that controlling algal production. Our study aims at determining the factors that controlling patchiness of phytoplankton and primary production in Liaodong Bay, China that receives large inputs of nutrients from human activities in its watershed, and examining the variation patterns of phytoplankton photosynthesis under both stressors of climate change and human activities. Results of our field study suggest that nutrient concentrations were above growth-rate-saturating concentrations throughout Liaodong bay, with the possible exception of phosphate at some stations. This assessment was consistent with the results of nutrient enrichment experiments and the values of light-saturated photosynthetic rates and areal photosynthetic rates. Two large patches of high biomass and production with dimensions on the order of 10 km reflect the effects of water temperature and variation of light penetration restricted by water turbidity. To examine the effects of irradiance and temperature on light-saturated photosynthetic rates normalized to chlorophyll a concentrations (Popt), light-conditioned Popt values were modeled as a function of the temperature with a satisfactory fit to our field data (R2 = 0.60, p = 0.003). In this model, light-conditioned Popt values increased with temperatures from 22°C to roughly 25°C but declined precipitously at higher temperatures. The relatively high Popt values and low ratios of light absorbed to photosynthesis at coastal stations suggest the highly efficient usage of absorbed light by

Utilization of urea and expression profiles of related genes in the dinoflagellate Prorocentrum donghaiense.

PubMed

Jing, Xiaoli; Lin, Senjie; Zhang, Huan; Koerting, Claudia; Yu, Zhigang

2017-01-01

Urea has been shown to contribute more than half of total nitrogen (N) required by phytoplankton in some estuaries and coastal waters and to provide a substantial portion of the N demand for many harmful algal blooms (HABs) of dinoflagellates. In this study, we investigated the physiological and transcriptional responses in Prorocentrum donghaiense to changes in nitrate and urea availability. We found that this species could efficiently utilize urea as sole N source and achieve comparable growth rate and photosynthesis capability as it did under nitrate. These physiological parameters were markedly lower in cultures grown under nitrate- or urea-limited conditions. P. donghaiense N content was similarly low under nitrate- or urea-limited culture condition, but was markedly higher under urea-replete condition than under nitrate-replete condition. Carbon (C) content was consistently elevated under N-limited condition. Consequently, the C:N ratio was as high as 21:1 under nitrate- or urea-limitation, but 7:1 under urea-replete condition and 9:1 to 10:1 under nitrate-replete condition. Using quantitative reverse transcription PCR, we investigated the expression pattern for four genes involved in N transport and assimilation. The results indicated that genes encoding nitrate transport, urea hydrolysis, and nickel transporter gene were sensitive to changes in general N nutrient availability whereas the urea transporter gene responded much more strongly to changes in urea concentration. Taken together, our study shows the high bioavailability of urea, its impact on C:N stoichiometry, and the sensitivity of urea transporter gene expression to urea availability.

Utilization of urea and expression profiles of related genes in the dinoflagellate Prorocentrum donghaiense

PubMed Central

Jing, Xiaoli; Lin, Senjie; Zhang, Huan; Koerting, Claudia; Yu, Zhigang

2017-01-01

Urea has been shown to contribute more than half of total nitrogen (N) required by phytoplankton in some estuaries and coastal waters and to provide a substantial portion of the N demand for many harmful algal blooms (HABs) of dinoflagellates. In this study, we investigated the physiological and transcriptional responses in Prorocentrum donghaiense to changes in nitrate and urea availability. We found that this species could efficiently utilize urea as sole N source and achieve comparable growth rate and photosynthesis capability as it did under nitrate. These physiological parameters were markedly lower in cultures grown under nitrate- or urea-limited conditions. P. donghaiense N content was similarly low under nitrate- or urea-limited culture condition, but was markedly higher under urea-replete condition than under nitrate-replete condition. Carbon (C) content was consistently elevated under N-limited condition. Consequently, the C:N ratio was as high as 21:1 under nitrate- or urea-limitation, but 7:1 under urea-replete condition and 9:1 to 10:1 under nitrate-replete condition. Using quantitative reverse transcription PCR, we investigated the expression pattern for four genes involved in N transport and assimilation. The results indicated that genes encoding nitrate transport, urea hydrolysis, and nickel transporter gene were sensitive to changes in general N nutrient availability whereas the urea transporter gene responded much more strongly to changes in urea concentration. Taken together, our study shows the high bioavailability of urea, its impact on C:N stoichiometry, and the sensitivity of urea transporter gene expression to urea availability. PMID:29117255

Assessing the nutrient intake of a low-carbohydrate, high-fat (LCHF) diet: a hypothetical case study design

PubMed Central

Zinn, Caryn; Rush, Amy; Johnson, Rebecca

2018-01-01

Objective The low-carbohydrate, high-fat (LCHF) diet is becoming increasingly employed in clinical dietetic practice as a means to manage many health-related conditions. Yet, it continues to remain contentious in nutrition circles due to a belief that the diet is devoid of nutrients and concern around its saturated fat content. This work aimed to assess the micronutrient intake of the LCHF diet under two conditions of saturated fat thresholds. Design In this descriptive study, two LCHF meal plans were designed for two hypothetical cases representing the average Australian male and female weight-stable adult. National documented heights, a body mass index of 22.5 to establish weight and a 1.6 activity factor were used to estimate total energy intake using the Schofield equation. Carbohydrate was limited to <130 g, protein was set at 15%–25% of total energy and fat supplied the remaining calories. One version of the diet aligned with the national saturated fat guideline threshold of <10% of total energy and the other included saturated fat ad libitum. Primary outcomes The primary outcomes included all micronutrients, which were assessed using FoodWorks dietary analysis software against national Australian/New Zealand nutrient reference value (NRV) thresholds. Results All of the meal plans exceeded the minimum NRV thresholds, apart from iron in the female meal plans, which achieved 86%–98% of the threshold. Saturated fat intake was logistically unable to be reduced below the 10% threshold for the male plan but exceeded the threshold by 2 g (0.6%). Conclusion Despite macronutrient proportions not aligning with current national dietary guidelines, a well-planned LCHF meal plan can be considered micronutrient replete. This is an important finding for health professionals, consumers and critics of LCHF nutrition, as it dispels the myth that these diets are suboptimal in their micronutrient supply. As with any diet, for optimal nutrient achievement, meals need to

Phosphorylated Akt Protein at Ser473 Enables HeLa Cells to Tolerate Nutrient-Deprived Conditions

PubMed

Fathy, Moustafa; Awale, Suresh; Nikaido, Toshio

2017-12-29

Background: Despite angiogenesis, many tumours remain hypovascular and starved of nutrients while continuing to grow rapidly. The specific biochemical mechanisms associated with starvation resistance, austerity, may be new biological characters of cancer that are critical for cancer progression. Objective: This study aim was to investigate the effect of nutrient starvation on HeLa cells and the possible mechanism by which the cells are able to tolerate nutrient-deprived conditions. Methods: Nutrient starvation was achieved by culturing HeLa cells in nutrient-deprived medium (NDM) and cell survival was estimated by using cell counting kit-8. The effect of starvation on cell cycle distribution and the quantitative analysis of apoptotic cells were investigated by flow cytometry using propidium iodide staining. Western blotting was used to detect the expression levels of Akt and phosphorylated Akt at Ser473 (Ser473p-Akt) proteins. Results: HeLa cells displayed extremely long survival when cultured in NDM. The percentage of apoptotic HeLa cells was significantly increased by starvation in a time-dependent manner. A significant increase in the expression of Ser473p-Akt protein after starvation was also observed. Furthermore, it was found that Akt inhibitor III molecule inhibited the cells proliferation in a concentration- and time-dependent manner. Conclusion: Results of the present study provide evidence that Akt activation may be implicated in the tolerance of HeLa cells for nutrient starvation and may help to suggest new therapeutic strategies designed to prevent austerity of cervical cancer cells through inhibition of Akt activation. Creative Commons Attribution License

Nutrient enrichment and fish nutrient tolerance: Assessing biologically relevant nutrient criteria

USGS Publications Warehouse

Meador, Michael R.

2013-01-01

Relationships between nutrient concentrations and fish nutrient tolerance were assessed relative to established nutrient criteria. Fish community, nitrate plus nitrite (nitrate), and total phosphorus (TP) data were collected during summer low-flow periods in 2003 and 2004 at stream sites along a nutrient-enrichment gradient in an agricultural basin in Indiana and Ohio and an urban basin in the Atlanta, Georgia, area. Tolerance indicator values for nitrate and TP were assigned for each species and averaged separately for fish communities at each site (TIVo). Models were used to predict fish species expected to occur at a site under minimally disturbed conditions and average tolerance indicator values were determined for nitrate and TP separately for expected communities (TIVe). In both areas, tolerance scores (TIVo/TIVe) for nitrate increased significantly with increased nitrate concentrations whereas no significant relationships were detected between TP tolerance scores and TP concentrations. A 0% increase in the tolerance score (TIVo/TIVe = 1) for nitrate corresponded to a nitrate concentration of 0.19 mg/l (compared with a USEPA summer nitrate criterion of 0.17 mg/l) in the urban area and 0.31 mg/l (compared with a USEPA summer nitrate criterion of 0.86 mg/l) in the agricultural area. Fish nutrient tolerance values offer the ability to evaluate nutrient enrichment based on a quantitative approach that can provide insights into biologically relevant nutrient criteria.

Phytoplankton succession in an isolated upwelled Benguela water body in relation to different initial nutrient conditions

NASA Astrophysics Data System (ADS)

Wasmund, Norbert; Nausch, Günther; Hansen, Anja

2014-11-01

Freshly upwelled water is poor in phytoplankton biomass but rich in nutrients. With its ageing, phytoplankton biomass increases whereas the nutrients are consumed. The overall aim of our investigation was to check the succession in the phytoplankton composition as a consequence of changing nutrient conditions. The experiments were carried out in mesocosms filled with surface water in the northern Benguela region and installed on board of R/V "Maria S. Merian". In the freshly upwelled water, phytoplankton took up nitrogen at a higher rate than phosphorus if compared with the Redfield ratio. Therefore, nitrogen was exhausted already by day 6. Nitrogen limitation after day 6 was indicated by decreasing chlorophyll a (chla) concentrations, primary production rates and productivity indices and increasing C/N ratios in particulate matter. Despite nitrogen limitation, phosphorus addition stimulated further growth, mainly of diatoms, pointing to luxury uptake. Cyanobacteria did not develop and nitrogen fixation was zero even with phosphorus and iron addition. Diatoms stay the most important group in the freshly upwelled water, but autotrophic and heterotrophic dinoflagellates increase strongly in the matured upwelled water. Mesocosms excluded disturbances by advective water transports, which influence the study of succssions under field conditions.

Towards Defining Nutrient Conditions Encountered by the Rice Blast Fungus during Host Infection

PubMed Central

Wilson, Richard A.; Fernandez, Jessie; Quispe, Cristian F.; Gradnigo, Julien; Seng, Anya; Moriyama, Etsuko; Wright, Janet D.

2012-01-01

Fungal diseases cause enormous crop losses, but defining the nutrient conditions encountered by the pathogen remains elusive. Here, we generated a mutant strain of the devastating rice pathogen Magnaporthe oryzae impaired for de novo methionine biosynthesis. The resulting methionine-requiring strain grew strongly on synthetic minimal media supplemented with methionine, aspartate or complex mixtures of partially digested proteins, but could not establish disease in rice leaves. Live-cell-imaging showed the mutant could produce normal appressoria and enter host cells but failed to develop, indicating the availability or accessibility of aspartate and methionine is limited in the plant. This is the first report to demonstrate the utility of combining biochemical genetics, plate growth tests and live-cell-imaging to indicate what nutrients might not be readily available to the fungal pathogen in rice host cells. PMID:23071797

Repletion of branched chain amino acids reverses mTORC1 signaling but not improved metabolism during dietary protein dilution.

PubMed

Maida, Adriano; Chan, Jessica S K; Sjøberg, Kim A; Zota, Annika; Schmoll, Dieter; Kiens, Bente; Herzig, Stephan; Rose, Adam J

2017-08-01

Dietary protein dilution (PD) has been associated with metabolic advantages such as improved glucose homeostasis and increased energy expenditure. This phenotype involves liver-induced release of FGF21 in response to amino acid insufficiency; however, it has remained unclear whether dietary dilution of specific amino acids (AAs) is also required. Circulating branched chain amino acids (BCAAs) are sensitive to protein intake, elevated in the serum of obese humans and mice and thought to promote insulin resistance. We tested whether replenishment of dietary BCAAs to an AA-diluted (AAD) diet is sufficient to reverse the glucoregulatory benefits of dietary PD. We conducted AA profiling of serum from healthy humans and lean and high fat-fed or New Zealand obese (NZO) mice following dietary PD. We fed wildtype and NZO mice one of three amino acid defined diets: control, total AAD, or the same diet with complete levels of BCAAs (AAD + BCAA). We quantified serum AAs and characterized mice in terms of metabolic efficiency, body composition, glucose homeostasis, serum FGF21, and tissue markers of the integrated stress response (ISR) and mTORC1 signaling. Serum BCAAs, while elevated in serum from hyperphagic NZO, were consistently reduced by dietary PD in humans and murine models. Repletion of dietary BCAAs modestly attenuated insulin sensitivity and metabolic efficiency in wildtype mice but did not restore hyperglycemia in NZO mice. While hepatic markers of the ISR such as P-eIF2α and FGF21 were unabated by dietary BCAA repletion, hepatic and peripheral mTORC1 signaling were fully or partially restored, independent of changes in circulating glucose or insulin. Repletion of BCAAs in dietary PD is sufficient to oppose changes in somatic mTORC1 signaling but does not reverse the hepatic ISR nor induce insulin resistance in type 2 diabetes during dietary PD.

Sucrose ingestion after exhaustive exercise accelerates liver, but not muscle glycogen repletion compared with glucose ingestion in trained athletes.

PubMed

Fuchs, Cas J; Gonzalez, Javier T; Beelen, Milou; Cermak, Naomi M; Smith, Fiona E; Thelwall, Pete E; Taylor, Roy; Trenell, Michael I; Stevenson, Emma J; van Loon, Luc J C

2016-06-01

The purpose of this study was to assess the effects of sucrose vs. glucose ingestion on postexercise liver and muscle glycogen repletion. Fifteen well-trained male cyclists completed two test days. Each test day started with glycogen-depleting exercise, followed by 5 h of recovery, during which subjects ingested 1.5 g·kg(-1)·h(-1) sucrose or glucose. Blood was sampled frequently and (13)C magnetic resonance spectroscopy and imaging were employed 0, 120, and 300 min postexercise to determine liver and muscle glycogen concentrations and liver volume. Results were as follows: Postexercise muscle glycogen concentrations increased significantly from 85 ± 27 (SD) vs. 86 ± 35 mmol/l to 140 ± 23 vs. 136 ± 26 mmol/l following sucrose and glucose ingestion, respectively (no differences between treatments: P = 0.673). Postexercise liver glycogen concentrations increased significantly from 183 ± 47 vs. 167 ± 65 mmol/l to 280 ± 72 vs. 234 ± 81 mmol/l following sucrose and glucose ingestion, respectively (time × treatment, P = 0.051). Liver volume increased significantly over the 300-min period after sucrose ingestion only (time × treatment, P = 0.001). As a result, total liver glycogen content increased during postexercise recovery to a greater extent in the sucrose treatment (from 53.6 ± 16.2 to 86.8 ± 29.0 g) compared with the glucose treatment (49.3 ± 25.5 to 65.7 ± 27.1 g; time × treatment, P < 0.001), equating to a 3.4 g/h (95% confidence interval: 1.6-5.1 g/h) greater repletion rate with sucrose vs. glucose ingestion. In conclusion, sucrose ingestion (1.5 g·kg(-1)·h(-1)) further accelerates postexercise liver, but not muscle glycogen repletion compared with glucose ingestion in trained athletes. Copyright © 2016 the American Physiological Society.

Biocorrosion and biofilm formation in a nutrient limited heating system subjected to alternating microaerophilic conditions.

PubMed

Kjellerup, B V; Kjeldsen, K U; Lopes, F; Abildgaard, L; Ingvorsen, K; Frølund, B; Sowers, K R; Nielsen, P H

2009-11-01

Severe biofilm formation and biocorrosion have been observed in heating systems even when the water quality complied with existing standards. The coupling between water chemistry, biofilm formation, species composition, and biocorrosion in a heating system was investigated by adding low concentrations of nutrients and oxygen under continuous and alternating dosing regimes. Molecular analysis of 16S rRNA gene fragments demonstrated that the amendments did not cause changes in the overall bacterial community composition. The combined alternating dosing of nutrients and oxygen caused increased rates of pitting (bio-) corrosion. Detection of bacteria involved in sulfide production and oxidation by retrieval of the functional dsrAB and apsA genes revealed the presence of Gram-positive sulfate- and sulfite-reducers and an unknown sulfur-oxidizer. Therefore, to control biocorrosion, sources of oxygen and nutrients must be limited, since the effect of the alternating operational conditions apparently is more important than the presence of potentially corrosive biofilm bacteria.

Excessive iodine intake does not increase the recurrence rate of graves' disease after withdrawal of the antithyroid drug in an iodine-replete area.

PubMed

Park, Sun Mi; Cho, Yoon Young; Joung, Ji Young; Sohn, Seo Young; Kim, Sun Wook; Chung, Jae Hoon

2015-03-01

The relationship between iodine intake and effects of antithyroid drugs (ATD) for Graves' disease, especially in iodine-deficient areas, has been demonstrated in many studies. However, it was not clear how chronic high iodine intake influenced the effectiveness of ATD in an iodine-replete area. This study aimed to clarify the effect of iodine intake on clinical outcomes of Graves' disease after discontinuation of ATD in Korea, an iodine-replete area. A total of 142 patients with Graves' disease who visited the outpatient clinic regularly and stopped their ATD between October 2011 and April 2013 were enrolled in our study. Urinary iodine concentration (UIC) was measured just before and after the discontinuation of ATD. Median UIC was not significantly different between the remission and relapse groups, as well as among the four treatment groups (group 1, remission after initial treatment; group 2, remission after repeated treatment; group 3, early relapse within a year; group 4, late relapse after a year). Remission rates did not show a significant difference between the excessive iodine intake (UIC ≥300 μg/l) and average iodine intake groups (UIC <300 μg/l). The present study suggests that excessive iodine intake does not have an effect on the clinical outcomes of Graves' disease in an iodine-replete area, and therefore diet control with iodine restriction might not be necessary in the management of Graves' disease.

Fiber optic spectrophotometry monitoring of plant nutrient deficiency under hydroponic culture conditions

NASA Astrophysics Data System (ADS)

Liew, Oi Wah; Boey, William S. L.; Asundi, Anand K.; Chen, Jun-Wei; He, Duo-Min

1999-05-01

In this paper, fiber optic spectrophotometry (FOSpectr) was adapted to provide early detection of plant nutrient deficiency by measuring leaf spectral reflectance variation resulting from nutrient stress. Leaf reflectance data were obtained form a local vegetable crop, Brassica chinensis var parachinensis (Bailey), grown in nitrate-nitrogen (N)- and calcium (Ca)- deficient hydroponics nutrient solution. FOSpectr analysis showed significant differences in leaf reflectance within the first four days after subjecting plants to nutrient-deficient media. Recovery of the nutrient-stressed plants could also be detected after transferring them back to complete nutrient solution. In contrast to FOSpectr, plant response to nitrogen and calcium deficiency in terms of reduced growth and tissue elemental levels was slower and less pronounced. Thus, this study demonstrated the feasibility of using FOSpectr methodology as a non-destructive alternative to augment current methods of plant nutrient analysis.

Drug-nutrient interactions.

PubMed

Thomas, J A

1995-10-01

Nutrition status plays a significant role in a drug's pharmacodynamics. Some disease states and other special conditions affect nutrient status and a drug's therapeutic efficacy. Many classes of drugs, including antimicrobials, hypoglycemics, and hypocholesterolemic agents, can be affected by the presence of food, with the geriatric patient particularly at risk. While a drug's pharmacokinetic profile can usually be predicted, it can be modified by nutrients and by certain pathophysiologic conditions, including aging, hepatic dysfunction, and micronutrients.

Diatoms morphology and gene expression in turbulence

NASA Astrophysics Data System (ADS)

Iudicone, D.; Amato, A.; Ferrante, M. I.; Ribera, M.

2016-02-01

Diatoms are an ecologically important algal group that prospers in turbulent environments. Despite previous efforts, a general scenario that explains mesocosm and in situ observations is missing. Importantly, according to the present theories, the main effect of microscale turbulence is the increase of nutrient uptake efficiency in nutrient-depleted conditions and for very large cells. We will present evidences from laboratory experiments in nutrient-repleted conditions that chain-forming diatoms sense and respond to turbulence by varying their chain length spectra and tuning their metabolism. Further, we compared growth and gene expressions of small-sized cells in turbulent and in still conditions and found that turbulence sensing activates a series of pathways suggesting a partial metabolic switch in response to agitation. In addition, a long-time exposure experiment showed that when silicates become depleted these same diatoms take up other nutrients differently than in still condition. This implies that in natural environment prolonged turbulence would shape the phytoplankton community structure and succession.

Coupling of the spatial-temporal distributions of nutrients and physical conditions in the southern Yellow Sea

NASA Astrophysics Data System (ADS)

Wei, Qin-Sheng; Yu, Zhi-Gang; Wang, Bao-Dong; Fu, Ming-Zhu; Xia, Chang-Shui; Liu, Lu; Ge, Ren-Feng; Wang, Hui-Wu; Zhan, Run

2016-04-01

This study investigated the coupling of the spatial-temporal variations in nutrient distributions and physical conditions in the southern Yellow Sea (SYS) using data compiled from annual-cycle surveys conducted in 2006-2007 as well as satellite-derived sea-surface temperature (SST) images. The influence of physical dynamics on the distribution and transport of nutrients varied spatially and seasonally in the SYS. The Changjiang Diluted Water (CDW) plume (in summertime), the Subei Coastal Water (SCW) (year-round), and the Lubei Coastal Current (LCC) (in wintertime) served as important sources of nutrients in the inshore area in a dynamic environment. The saline Taiwan Warm Current (TWC) might transport nutrients to the northeast region of the Changjiang Estuary in the summer, and this nutrient source began to increase from spring to summer and decrease when autumn arrived. Three types of nutrient fronts, i.e., estuarine, offshore, and coastal, were identified. A circular nutrient front caused by cross-shelf transport of SCW in the southeast shelf bank area in the winter and spring was observed. The southeastward flow of western coastal cold water in the SYS might be an important conduit for cross-shelf nutrient exchange between the SYS and the East China Sea (ECS). The tongue-shaped low-nutrient region in the western study area in the wintertime was driven by the interaction of the southward Yellow Sea Western Coastal Current (YSWCC) and the biological activity. The vertically variable SCM (subsurface Chl-a maximum) in the central SYS was controlled by coupled physical-chemical processes that involved stratification and associated nutricline. The average nutrient fluxes into the euphotic zone due to upwelling near the frontal zone of the Yellow Sea Cold Water Mass (YSCWM) in the summer are estimated here for the first time: 1.4 ± 0.9 × 103 μmol/m2/d, 0.1 ± 0.1 × 103 μmol/m2/d, and 2.0 ± 1.3 × 103 μmol/m2/d for DIN, PO4-P, and SiO3-Si, respectively. The

Manure Application under Winter Conditions: Nutrient Runoff and Leaching Losses

USDA-ARS?s Scientific Manuscript database

Winter application of manure is commonly practiced and potential nutrient losses can be difficult to predict due to wide variations in weather within a year and between years. This study was conducted to determine nutrient losses via surface runoff and subsurface leachate from winter-applied manure ...

Manure application under winter conditions: Nutrient runoff and leaching losses

USDA-ARS?s Scientific Manuscript database

Winter application of manure is commonly practiced and potential nutrient losses are difficult to predict. This study was conducted in order to determine nutrient losses via surface runoff and subsurface leachate from winter-applied manure based on its relative placement with respect to snow. A labo...

Manure Application Under Winter Conditions: Nutrient Runoff and Leaching Losses

USDA-ARS?s Scientific Manuscript database

Winter application of manure is commonly practiced and potential nutrient losses are difficult to predict. This study was conducted in order to determine nutrient losses via surface runoff and subsurface leachate from winter-applied manure based on its relative placement with respect to snow. A labo...

Reference Condition Approach for Numeric Nutrient Criteria for Oregon Estuaries

EPA Science Inventory

Development of nutrient criteria for all water body types of the US remains a top priority for EPA. Estuaries in the Pacific Northwest receive nutrients from both the watershed and the coastal ocean, and thus are particularly complex systems in which to establish water quality c...

A greater foraging scale, not a higher foraging precision, may facilitate invasion by exotic plants in nutrient-heterogeneous conditions.

PubMed

Chen, Bao-Ming; Su, Jin-Quan; Liao, Hui-Xuan; Peng, Shao-Lin

2018-03-05

Soil nutrient heterogeneity has been proposed to influence competitive outcomes among different plant species. Thus, it is crucial to understand the effects of environmental heterogeneity on competition between exotic invasive and native species. However, the effects of soil nutrient heterogeneity on the competition between invasive and native plants have rarely been linked to root foraging behaviour. In this study, a competition experiment was performed with two invasive-native species pairs (BP-VC, Bidens pilosa vs. Vernonia cinerea; MM-PS, Mikania micrantha vs. Paederia scandens) grown under homogeneous and heterogeneous conditions in a common greenhouse environment. Root activity was assessed by determining the amount of strontium (Sr) taken up by the shoot of each species. The invasive species exhibited a greater foraging scale, whereas the native species exhibited a higher foraging precision. A trade-off between foraging scale and precision was observed within each pair of invasive-native species. Compared with soil homogeneity, soil heterogeneity significantly increased the biomass of the two invasive species, B. pilosa and M. micrantha, under competitive conditions. Within each pair, the invasive species exhibited greater relative competitive ability with respect to shoot mass, and considerably more Sr taken up by the invasive species compared with the native species. The Sr acquisition results indicate that nutrient-poor conditions may facilitate the competitive ability of the native species V. cinerea, whereas M. micrantha may possess a stronger competitive ability regardless of soil nutrient conditions. Soil nutrient heterogeneity has the potential to promote the invasion of these two exotic species due to their larger foraging scale, stronger competitive ability and greater root activity relative to their counterpart native species. The present work highlights the importance of soil heterogeneity in plant invasion, particularly with regards to root

Excessive Iodine Intake Does Not Increase the Recurrence Rate of Graves' Disease after Withdrawal of the Antithyroid Drug in an Iodine-Replete Area

PubMed Central

Park, Sun Mi; Cho, Yoon Young; Joung, Ji Young; Sohn, Seo Young; Kim, Sun Wook; Chung, Jae Hoon

2015-01-01

Background and Objectives The relationship between iodine intake and effects of antithyroid drugs (ATD) for Graves' disease, especially in iodine-deficient areas, has been demonstrated in many studies. However, it was not clear how chronic high iodine intake influenced the effectiveness of ATD in an iodine-replete area. This study aimed to clarify the effect of iodine intake on clinical outcomes of Graves' disease after discontinuation of ATD in Korea, an iodine-replete area. Methods A total of 142 patients with Graves' disease who visited the outpatient clinic regularly and stopped their ATD between October 2011 and April 2013 were enrolled in our study. Urinary iodine concentration (UIC) was measured just before and after the discontinuation of ATD. Results Median UIC was not significantly different between the remission and relapse groups, as well as among the four treatment groups (group 1, remission after initial treatment; group 2, remission after repeated treatment; group 3, early relapse within a year; group 4, late relapse after a year). Remission rates did not show a significant difference between the excessive iodine intake (UIC ≥300 μg/l) and average iodine intake groups (UIC <300 μg/l). Conclusions The present study suggests that excessive iodine intake does not have an effect on the clinical outcomes of Graves' disease in an iodine-replete area, and therefore diet control with iodine restriction might not be necessary in the management of Graves' disease. PMID:25960960

NAD+ repletion improves muscle function in muscular dystrophy and counters global PARylation

PubMed Central

Ryu, Dongryeol; Zhang, Hongbo; Ropelle, Eduardo R.; Sorrentino, Vincenzo; Mázala, Davi A. G.; Mouchiroud, Laurent; Marshall, Philip L.; Campbell, Matthew D.; Ali, Amir Safi; Knowels, Gary M.; Bellemin, Stéphanie; Iyer, Shama R.; Wang, Xu; Gariani, Karim; Sauve, Anthony A.; Cantó, Carles; Conley, Kevin E.; Walter, Ludivine; Lovering, Richard M.; Chin, Eva R.; Jasmin, Bernard J.; Marcinek, David J.; Menzies, Keir J.; Auwerx, Johan

2017-01-01

Neuromuscular diseases are often caused by inherited mutations that lead to progressive skeletal muscle weakness and degeneration. In diverse populations of normal healthy mice, we observed correlations between the abundance of mRNA transcripts related to mitochondrial biogenesis, the dystrophin-sarcoglycan complex, and nicotinamide adenine dinucleotide (NAD+) synthesis, consistent with a potential role for the essential cofactor NAD+ in protecting muscle from metabolic and structural degeneration. Furthermore, the skeletal muscle transcriptomes of patients with Duchene’s muscular dystrophy (DMD) and other muscle diseases were enriched for various poly[adenosine 5’-diphosphate (ADP)–ribose] polymerases (PARPs) and for nicotinamide N-methyltransferase (NNMT), enzymes that are major consumers of NAD+ and are involved in pleiotropic events, including inflammation. In the mdx mouse model of DMD, we observed significant reductions in muscle NAD+ levels, concurrent increases in PARP activity, and reduced expression of nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme for NAD+ biosynthesis. Replenishing NAD+ stores with dietary nicotinamide riboside supplementation improved muscle function and heart pathology in mdx and mdx/Utr−/− mice and reversed pathology in Caenorhabditis elegans models of DMD. The effects of NAD+ repletion in mdx mice relied on the improvement in mitochondrial function and structural protein expression (α-dystrobrevin and δ-sarcoglycan) and on the reductions in general poly(ADP)-ribosylation, inflammation, and fibrosis. In combination, these studies suggest that the replenishment of NAD+ may benefit patients with muscular dystrophies or other neuromuscular degenerative conditions characterized by the PARP/NNMT gene expression signatures. PMID:27798264

NAD+ repletion improves muscle function in muscular dystrophy and counters global PARylation.

PubMed

Ryu, Dongryeol; Zhang, Hongbo; Ropelle, Eduardo R; Sorrentino, Vincenzo; Mázala, Davi A G; Mouchiroud, Laurent; Marshall, Philip L; Campbell, Matthew D; Ali, Amir Safi; Knowels, Gary M; Bellemin, Stéphanie; Iyer, Shama R; Wang, Xu; Gariani, Karim; Sauve, Anthony A; Cantó, Carles; Conley, Kevin E; Walter, Ludivine; Lovering, Richard M; Chin, Eva R; Jasmin, Bernard J; Marcinek, David J; Menzies, Keir J; Auwerx, Johan

2016-10-19

Neuromuscular diseases are often caused by inherited mutations that lead to progressive skeletal muscle weakness and degeneration. In diverse populations of normal healthy mice, we observed correlations between the abundance of mRNA transcripts related to mitochondrial biogenesis, the dystrophin-sarcoglycan complex, and nicotinamide adenine dinucleotide (NAD + ) synthesis, consistent with a potential role for the essential cofactor NAD + in protecting muscle from metabolic and structural degeneration. Furthermore, the skeletal muscle transcriptomes of patients with Duchene's muscular dystrophy (DMD) and other muscle diseases were enriched for various poly[adenosine 5'-diphosphate (ADP)-ribose] polymerases (PARPs) and for nicotinamide N-methyltransferase (NNMT), enzymes that are major consumers of NAD + and are involved in pleiotropic events, including inflammation. In the mdx mouse model of DMD, we observed significant reductions in muscle NAD + levels, concurrent increases in PARP activity, and reduced expression of nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme for NAD + biosynthesis. Replenishing NAD + stores with dietary nicotinamide riboside supplementation improved muscle function and heart pathology in mdx and mdx/Utr -/- mice and reversed pathology in Caenorhabditis elegans models of DMD. The effects of NAD + repletion in mdx mice relied on the improvement in mitochondrial function and structural protein expression (α-dystrobrevin and δ-sarcoglycan) and on the reductions in general poly(ADP)-ribosylation, inflammation, and fibrosis. In combination, these studies suggest that the replenishment of NAD + may benefit patients with muscular dystrophies or other neuromuscular degenerative conditions characterized by the PARP/NNMT gene expression signatures. Copyright © 2016, American Association for the Advancement of Science.

Survival of pathogenic bacteria under nutrient starvation conditions. [aboard orbiting space stations

NASA Technical Reports Server (NTRS)

Boyle, Michael; Ford, Tim; Mitchell, Ralph; Maki, James

1990-01-01

The survival of opportunistic pathogenic microorganisms in water, under nutrient-limiting conditions, has been investigated in order to ascertain whether human pathogens can survive within a water-distribution system of the kind proposed for the NASA Space Station. Cultures of a strain of pseudomonas aeruginosa and two strains of staphylococcus aureus were incubated at 10, 25, or 37 C, and samples at 1 day, 1 week, 1 month, and six weeks. While neither of the staphylococcus strains tested were detected after 1 week of starvation, the pseudomonas strain can survive in deionized water at all three temperatures.

Approaches in the determination of plant nutrient uptake and distribution in space flight conditions

NASA Technical Reports Server (NTRS)

Heyenga, A. G.; Forsman, A.; Stodieck, L. S.; Hoehn, A.; Kliss, M.

2000-01-01

The effective growth and development of vascular plants rely on the adequate availability of water and nutrients. Inefficiency in either the initial absorption, transportation, or distribution of these elements are factors which impinge on plant structure and metabolic integrity. The potential effect of space flight and microgravity conditions on the efficiency of these processes is unclear. Limitations in the available quantity of space-grown plant material and the sensitivity of routine analytical techniques have made an evaluation of these processes impractical. However, the recent introduction of new plant cultivating methodologies supporting the application of radionuclide elements and subsequent autoradiography techniques provides a highly sensitive investigative approach amenable to space flight studies. Experiments involving the use of gel based 'nutrient packs' and the radionuclides calcium-45 and iron-59 were conducted on the Shuttle mission STS-94. Uptake rates of the radionuclides between ground and flight plant material appeared comparable.

Approaches in the Determination of Plant Nutrient Uptake and Distribution in Space Flight Conditions

NASA Technical Reports Server (NTRS)

Heyenga, A. G.; Forsman, A.; Stodieck, L. S.; Hoehn, A.; Kliss, Mark

1998-01-01

The effective growth and development of vascular plants rely on the adequate availability of water and nutrients. Inefficiency in either the initial absorption, transportation, or distribution of these elements are factors which may impinge on plant structure and metabolic integrity. The potential effect of space flight and microgravity conditions on the efficiency of these processes is unclear. Limitations in the available quantity of space-grown plant material and the sensitivity of routine analytical techniques have made an evaluation of these processes impractical. However, the recent introduction of new plant cultivating methodologies supporting the application of radionuclide elements and subsequent autoradiography techniques provides a highly sensitive investigative approach amenable to space flight studies. Experiments involving the use of gel based 'nutrient packs' and the nuclides Ca45 and Fe59 were conducted on the Shuttle mission STS-94. Uptake rates of the radionuclides between ground and flight plant material appeared comparable.

Available nutrients in biochar

USDA-ARS?s Scientific Manuscript database

Biochar technology may contribute to the recovery and recycling of plant nutrients and thus add a fertilizer value to the biochar. Total nutrient content in biochars varies greatly and is mainly dependent on feedstock elemental composition and to a lesser extent on pyrolysis conditions. Availability...

Dual role of starvation signaling in promoting growth and recovery

PubMed Central

Leshkowitz, Dena; Barkai, Naama

2017-01-01

Growing cells are subject to cycles of nutrient depletion and repletion. A shortage of nutrients activates a starvation program that promotes growth in limiting conditions. To examine whether nutrient-deprived cells prepare also for their subsequent recovery, we followed the transcription program activated in budding yeast transferred to low-phosphate media and defined its contribution to cell growth during phosphate limitation and upon recovery. An initial transcription wave was induced by moderate phosphate depletion that did not affect cell growth. A second transcription wave followed when phosphate became growth limiting. The starvation program contributed to growth only in the second, growth-limiting phase. Notably, the early response, activated at moderate depletion, promoted recovery from starvation by increasing phosphate influx upon transfer to rich medium. Our results suggest that cells subject to nutrient depletion prepare not only for growth in the limiting conditions but also for their predicted recovery once nutrients are replenished. PMID:29236696

Use of glucose biosensors to measure extracellular glucose exudation by intertidal microphytobenthos in southern Tasmania.

PubMed

McMinn, Andrew; Lee, Shihong

2018-06-01

Micro glucose biosensors were used to measure net extracellular glucose produced by natural microphytobenthos and three diatom cultures (Amphora coffeaeformis, Navicula menisculus, Nitzschia longissima) from southern Tasmania, Australia. They were exposed to a light gradient in either nutrient-replete or nutrient-limiting conditions. Glucose exudation in the natural communities increased with increased light but the response in the cultures was variable. Similarly, nutrient-replete conditions elicited lower rates of glucose exudation in the natural communities but produced variable species-specific responses in the cultures. Increased glucose exudation mostly correlated with a reduction in maximum quantum yield (F v /F m ). The same trend was observed in the natural communities for relative maximum electron transfer rates (rETR max ) but responses in the cultures were again variable and species-specific. Responses of the three species to increased light and nutrient deficiency were variable, although glucose exudation, F v /F m and rETR max was mostly lower in the nutrient-limited media. In a second set of experiments species/communities were treated with/without antibiotics. In the dark, glucose concentrations in treatments with antibiotics remained unchanged, while in those with bacteria, it fell rapidly. In the sediment communities, glucose consumption in the dark was ~25% the rate of exudation at the highest light level. In culture, exudation rates were up to 100% greater than those with active bacteria. Rates of glucose consumption in the dark in the antibiotic-treated samples were negligible and up to 10 4 times lower than those with active bacteria. These results demonstrate the important role extracellular glucose exudation has on maintaining an active microbial loop. © 2018 Phycological Society of America.

T-cell-replete haploidentical stem cell transplantation is highly efficacious for relapsed and refractory childhood acute leukaemia.

PubMed

Kobayashi, S; Ito, M; Sano, H; Mochizuki, K; Akaihata, M; Waragai, T; Ohara, Y; Hosoya, M; Ohto, H; Kikuta, A

2014-10-01

Despite improvements in first-line therapies, the outcomes of relapsed or refractory childhood acute leukaemia that has not achieved complete remission after relapse, has relapsed after stem cell transplantation (SCT), has primary induction failure and has relapsed with a very unfavourable cytogenetic risk profile, are dismal. We evaluated the feasibility and efficacy of T-cell-replete haploidentical peripheral blood stem cell transplantation (haplo-SCT) with low-dose anti-human thymocyte immunoglobulin (ATG), tacrolimus, methotrexate and prednisolone (PSL) in 14 paediatric patients with high-risk childhood acute leukaemia. All patients achieved complete engraftment. The median time to reaching an absolute neutrophil count of more than 0.5 × 10(9) L(-1) was 14 days. Acute graft-vs-host disease (aGVHD) of grades II-IV and III-IV developed in 10 (71%) and 2 (14%) patients, respectively. Treatment-related mortality and relapse occurred in one (7%) patient and six (43%) patients, respectively. Eleven patients were alive and seven of them were disease-free with a median follow-up of 36 months (range: 30-159 months). The probability of event-free survival after 2 years was 50%. These findings indicate that T-cell-replete haplo-SCT, with low-dose ATG and PSL, provides sustained remission with an acceptable risk of GVHD in paediatric patients with advanced haematologic malignancies. © 2014 The Authors. Transfusion Medicine published by John Wiley & Sons Ltd on behalf of British Blood Transfusion Society.

Nutrient-limited conditions determine the responses of foliar nitrogen and phosphorus stoichiometry to nitrogen addition: A global meta-analysis.

PubMed

You, Chengming; Wu, Fuzhong; Yang, Wanqin; Xu, Zhenfeng; Tan, Bo; Yue, Kai; Ni, Xiangyin

2018-06-08

To test the hypothesis that nutrient-limited conditions can determine the responses of nitrogen (N) and phosphorus (P) stoichiometry to N addition, a meta-analysis was conducted to identify the different responses of foliar N and P concentrations and N-to-P ratios to N addition under N limitation, N and P co-limitation and P limitation. N addition increased the foliar N-to-P ratios and N concentrations by 46.2% and 30.2%, respectively, under N limitation, by 18.7% and 19.7% under N and P co-limitation, and by 4.7% and 12.9% under P limitation. However, different responses of foliar P concentrations to N addition were observed under different nutrient limitations, and negative, positive, and neutral effects on P concentrations were observed under N limitation, P limitation and N and P co-limitation, respectively. Generally, the effects of N addition on N-to-P ratios and N concentrations in herbaceous plants were dramatically larger than those in woody plants (with the exception of the N-to-P ratio under N limitation), but the opposite situation was true for P concentrations. The changes in N-to-P ratios were closely correlated with the changes in N and P concentrations, indicating that the changes in both N and P concentrations due to N addition can drive N and P stoichiometry, but the relative sizes of the contributions of N and P varied greatly with different nutrient limitations. Specifically, the changes in N-to-P ratios may indicate a minimum threshold, which is consistent with the homeostatic mechanism. In brief, increasing N deposition may aggravate P limitation under N-limited conditions but improve P limitation under P-limited conditions. The findings highlight the importance of nutrient-limited conditions in the stoichiometric response to N addition, thereby advancing our ability to predict global plant growth with increasing N deposition in the future. Copyright © 2018 Elsevier Ltd. All rights reserved.

Spatiotemporal variability of inorganic nutrients during wastewater effluent dominated streamflow conditions in Indian Creek, Johnson County, Kansas, 2012–15

USGS Publications Warehouse

Foster, Guy M.; Graham, Jennifer L.; Williams, Thomas J.; King, Lindsey R.

2016-10-31

Nutrients, particularly nitrogen and phosphorus, are a leading cause of water-quality impairment in Kansas and the Nation. Indian Creek is one of the most urban drainage basins in Johnson County, Kansas, and environmental and biological conditions are affected by contaminants from point and other urban sources. The Johnson County Douglas L. Smith Middle Basin (hereinafter Middle Basin) wastewater treatment facility (WWTF) is the largest point-source discharge on Indian Creek. A second facility, the Tomahawk Creek WWTF, discharges into Indian Creek approximately 11.6 kilometers downstream from the Middle Basin WWTF. To better characterize the spatiotemporal variability of nutrients in Indian Creek, the U.S. Geological Survey, in cooperation with the Kansas Department of Health and Environment and Johnson County Wastewater, collected high-resolution spatial and temporal (a large number of samples collected over the entire reach or at single locations over a long period of time) inorganic nutrient (nitrate plus nitrite and orthophosphorus) data using a combination of discrete samples and sensor-measured data during 2012 through 2015.Nutrient patterns observed in Indian Creek along the upstream-downstream gradient during wastewater effluent dominated streamflow conditions were largely affected by the WWTFs and by travel time of the parcels of water. Nitrate plus nitrite concentrations in the Middle Basin WWTF effluent and at downstream sites varied by as much as 6 milligrams per liter over a 24-hour period. The cyclical variability in the Middle Basin WWTF effluent generated a nitrate plus nitrite pulse that could be tracked for approximately 11.5 kilometers downstream in Indian Creek, until the effect was masked by the Tomahawk Creek WWTF effluent discharge. All longitudinal surveys showed the same general patterns along the upstream-downstream gradient, though streamflows, wastewater effluent contributions to streamflow, and nutrient concentrations spanned a wide

Temperature and nutrient effects on periphyton associated ...

EPA Pesticide Factsheets

Nutrient pollution is a leading cause of water quality impairments and degraded aquatic ecosystem condition. Reliable and reproducible indicators of ecosystem condition are needed to help manage nutrient pollution. The diatom component of periphyton has been used as a water quality indicator due to identifiable cell morphology and existence of relationships between nutrient concentration and diatom community composition. However, morphological identification of diatoms requires highly specialized personnel, is very time consuming, and can produce variable results, suggesting the need for alternative methods that are less expensive and more reproducible. DNA sequencing of the bacterial 16S rRNA gene is well documented and provides genus-level resolution of the community structure. The goal of this study was to evaluate the effects of nutrient loading and temperature on periphyton-associated bacterial communities using standard periphytometer techniques and next generation sequencing technologies. Continuous flow mesocosms were established in an eight tank system consisting of two temperature conditions (10°C and 20°C) and four nutrient conditions (1x to 6x ambient concentrations). Experimental conditions were replicated in July/August 2013 and September 2013. Replicate DNA samples were extracted and the 16S rRNA gene was sequenced using universal Bacterial primers. Initial analyses revealed strong differences in community structure based on temperature (p <

[Adaptive adjustment of rhizome and root system on morphology, biomass and nutrient in Phyllostachys rivalis under long-term waterlogged condition].

PubMed

Liu, Yu-fang; Chen, Shuang-lin; Li Ying-chun; Guo, Zi-wu; Li, Ying-chun; Yang, Qing-ping

2015-12-01

The research was to approach the growth strategy of rhizome and roots based on the morphology, biomass and nutrient in Phyllostachys rivalis under long-term waterlogged conditions, and provided a theoretical basis for its application for vegetation restoration in wetland and water-level fluctuation belts. The morphological characteristics, physiological and biochemical indexes of annual bamboo rhizome and roots were investigated with an experiment using individually potted P. rivalis which was treated by artificial water-logging for 3, 6, and 12 months. Accordingly the morphological characteristics, biomass allocation, nutrient absorption and balance in rhizome and roots of P. rivalis were analyzed. The results showed that there was no obvious impact of long-term water-logging on the length and diameter of rhizomes, diameter of roots in P. rivalis. The morphological characteristics of rhizome had been less affected generally under water-logging for 3 months. And less rhizomes were submerged, while the growth of roots was inhibited to some extent. Furthermore, with waterlogging time extended, submerged roots and rhizomes grew abundantly, and the roots and rhizomes in soil were promoted. Moreover for ratios of rhizome biomass in soil and water, there were no obvious variations, the same for the root biomass in soil to total biomass. The ratio of root biomass in water to total biomass and the ratio of root biomass in water to root biomass in soil both increased significantly. The results indicated that P. rivalis could adapt to waterlogged conditions gradually through growth regulation and reasonable biomass distribution. However, the activity of rhizome roots in soil decreased and the nutrient absorption was inhibited by long-term water-logging, although it had no effect on stoichiometric ratios of root nutrient in soil. The activity of rhizome root in water increased and the stoichiometric ratios adjusted adaptively to waterlogged conditions, the ratio of N

Identification, Expression Analysis, and Target Prediction of Flax Genotroph MicroRNAs Under Normal and Nutrient Stress Conditions

PubMed Central

Melnikova, Nataliya V.; Dmitriev, Alexey A.; Belenikin, Maxim S.; Koroban, Nadezhda V.; Speranskaya, Anna S.; Krinitsina, Anastasia A.; Krasnov, George S.; Lakunina, Valentina A.; Snezhkina, Anastasiya V.; Sadritdinova, Asiya F.; Kishlyan, Natalya V.; Rozhmina, Tatiana A.; Klimina, Kseniya M.; Amosova, Alexandra V.; Zelenin, Alexander V.; Muravenko, Olga V.; Bolsheva, Nadezhda L.; Kudryavtseva, Anna V.

2016-01-01

Cultivated flax (Linum usitatissimum L.) is an important plant valuable for industry. Some flax lines can undergo heritable phenotypic and genotypic changes (LIS-1 insertion being the most common) in response to nutrient stress and are called plastic lines. Offspring of plastic lines, which stably inherit the changes, are called genotrophs. MicroRNAs (miRNAs) are involved in a crucial regulatory mechanism of gene expression. They have previously been assumed to take part in nutrient stress response and can, therefore, participate in genotroph formation. In the present study, we performed high-throughput sequencing of small RNAs (sRNAs) extracted from flax plants grown under normal, phosphate deficient and nutrient excess conditions to identify miRNAs and evaluate their expression. Our analysis revealed expression of 96 conserved miRNAs from 21 families in flax. Moreover, 475 novel potential miRNAs were identified for the first time, and their targets were predicted. However, none of the identified miRNAs were transcribed from LIS-1. Expression of seven miRNAs (miR168, miR169, miR395, miR398, miR399, miR408, and lus-miR-N1) with up- or down-regulation under nutrient stress (on the basis of high-throughput sequencing data) was evaluated on extended sampling using qPCR. Reference gene search identified ETIF3H and ETIF3E genes as most suitable for this purpose. Down-regulation of novel potential lus-miR-N1 and up-regulation of conserved miR399 were revealed under the phosphate deficient conditions. In addition, the negative correlation of expression of lus-miR-N1 and its predicted target, ubiquitin-activating enzyme E1 gene, as well as, miR399 and its predicted target, ubiquitin-conjugating enzyme E2 gene, was observed. Thus, in our study, miRNAs expressed in flax plastic lines and genotrophs were identified and their expression and expression of their targets was evaluated using high-throughput sequencing and qPCR for the first time. These data provide new insights

Repletion of TNFα or leptin in calorically restricted mice suppresses post-restriction hyperphagia

PubMed Central

Hambly, Catherine; Duncan, Jacqueline S.; Archer, Zoë A.; Moar, Kim M.; Mercer, Julian G.; Speakman, John R.

2012-01-01

SUMMARY The causes of post-restriction hyperphagia (PRH) represent a target for drug-based therapies to prevent obesity. However, the factors causing PRH are poorly understood. We show that, in mice, the extent of PRH was independent of the time under restriction, but depended on its severity, suggesting that PRH was driven by signals from altered body composition. Signals related to fat mass were important drivers. Circulating levels of leptin and TNFα were significantly depleted following caloric restriction (CR). We experimentally repleted their levels to match those of controls, and found that in both treatment groups the level of PRH was significantly blunted. These data establish a role for TNFα and leptin in the non-pathological regulation of energy homeostasis. Signals from adipose tissue, including but not limited to leptin and TNFα, regulate PRH and might be targets for therapies that support people engaged in CR to reduce obesity. PMID:21954068

The role of missing killer cell immunoglobulin-like receptor ligands in T cell replete peripheral blood stem cell transplantation from HLA-identical siblings.

PubMed

Clausen, Johannes; Kircher, Brigitte; Auberger, Jutta; Schumacher, Petra; Ulmer, Hanno; Hetzenauer, Gabriele; Wolf, Dominik; Gastl, Günther; Nachbaur, David

2010-02-01

The contribution of natural killer (NK) cells to graft-versus-malignancy (GVM) effects following hematopoietic stem cell transplantation (HSCT) remains uncertain, particularly in the HLA-identical setting. A model considering missing HLA ligands to the donor's inhibitory killer cell immunoglobulin-like receptor (KIR), termed the missing KIR ligand model, has been established in T cell depleted bone marrow transplantation (BMT), but lacks validity in other cohorts with different treatment characteristics. We hypothesized that the impact of missing KIR ligands on relapse-free survival (RFS) and overall survival (OS) in T cell replete peripheral blood SCT (PBSCT) differs from that in the T cell depleted BMT setting, and retrospectively evaluated 100 consecutive, HLA-identical sibling transplantations for hematologic malignancies. In addition to KIR ligand status, we considered the donors' activating KIRs and grafted NK, T, and CD34(+) cell doses. Our findings demonstrate noninferiority for OS (P = .005) and RFS (P = .002) for the heterozygous HLA-C group KIR ligand status (C1/2; n = 47) compared with patients missing either C1 or C2 (n = 53). Similarly, OS (P = .031) and RFS (P = .034) of Bw4-positive patients was noninferior to that of patients missing a Bw4 ligand to KIR3DL1. By multivariate analysis, C1/2 heterozygous patients had a favorable risk ratio (RR) for relapse (RR = 0.28; P = .003), RFS (RR = 0.56; P = .046), and acute graft-versus-host disease grade II-IV (RR = 0.36; P = .05). Following reduced-intensity conditioning (RIC), but not standard-intensity conditioning, myeloablative (MA) transplantation, a grafted NK cell dose above the median (3.4 x 10(7)/kg) was associated with a lower risk of relapse (RR = 0.57; P = .003) and improved survival (RR = 0.78; P = .03). Overall, our findings support a role for NK alloreactivity in HLA-identical HSCT, but argue against a favorable impact of missing KIR ligands in the given setting. We conclude that the mechanism

Effect of berberine on the viability of adipose tissue-derived mesenchymal stem cells in nutrients deficient condition.

PubMed

Ghorbani, Ahmad; Baradaran Rahimi, Vafa; Sadeghnia, Hamid Reza; Hosseini, Azar

2018-03-01

This study was designed to examine whether berberine protects rat adipose tissue-derived stem cells (ASCs) against glucose and serum deprivation (GSD)-induced cell death. ASCs were cultured for 24 h in GSD condition in the presence of berberine and then cell viability, apoptosis and generation of reactive oxygen species (ROS) were evaluated. The GSD condition significantly decreased ASCs viability and increased ROS generation and apoptosis. Incubation with 0.75-3 μM berberine partially increased cell viability and decreased ROS generation and apoptosis in GSD condition. In conclusion, berberine partially protects ASCs in nutrients deficient condition and may help ASCs to preserve their survival during cell therapy of ischemia.

Analysis of doramectin in the serum of repeatedly treated pastured cattle used to predict the probability of cattle fever ticks (Acari: Ixodidae) feeding to repletion

USDA-ARS?s Scientific Manuscript database

Doramectin concentration in the serum of pastured cattle treated repeatedly at 28 d intervals at two dosage rates was used to predict the probability that cattle fever ticks could successfully feed to repletion during the interval between treatments. At ~270 µg/kg, the doramectin concentration dropp...

Physico-chemical characteristics, nutrient composition and consumer acceptability of wheat varieties grown under organic and inorganic farming conditions.

PubMed

Nitika; Punia, Darshan; Khetarpaul, N

2008-05-01

The aim of the investigation was to analyse physico-chemical characteristics, nutrient composition and consumer acceptability of wheat varieties grown under organic and inorganic farming conditions. The seeds of five varieties of wheat (C-306, WH-283, WH-711, WH-896 and WH-912) grown under organic and inorganic farming conditions were ground in a Junior Mill to pass through 60-mesh sieves and were stored in air-tight containers until use. Standard methods were used to estimate the physico-chemical characteristics and nutrient composition. Consumer acceptability was studied by carrying out the organoleptic evaluation of wheat chapatis, a common item in diets of the Indian population. The results of study revealed that inorganically grown wheat varieties had significantly higher 1,000-grain weight and more grain hardness as compared with organically grown wheat varieties, and a non-significant difference was observed in their gluten content, water absorption capacity and hydration capacity. On average, wheat varieties grown under inorganic conditions contained significantly higher protein and crude fibre content as compared with varieties grown under organic conditions. WH-711 variety had maximum protein content. Protein fractions (i.e. albumin, globulin, prolamin and glutelin) were significantly higher in varieties grown under inorganic conditions than those of varieties grown under organic conditions. The variety WH-711 had the highest total soluble sugars and variety WH-912 had the highest starch content. Phytic acid and polyphenol contents were significantly higher in inorganically grown wheat varieties as compared with organically grown wheat varieties. The wheat varieties grown under organic conditions had significantly higher protein and starch digestibility than the wheat grown under inorganic conditions. The data revealed that there were significant differences in total calcium and phosphorus contents of wheat varieties grown under organic and inorganic

Contribution of water hyacinth (Eichhornia crassipes (Mart.) Solms) grown under different nutrient conditions to Fe-removal mechanisms in constructed wetlands.

PubMed

Jayaweera, Mahesh W; Kasturiarachchi, Jagath C; Kularatne, Ranil K A; Wijeyekoon, Suren L J

2008-05-01

Severe contamination of water resources including groundwater with iron (Fe) due to various anthropogenic activities has been a major environmental problem in industrial areas of Sri Lanka. Hence, the use of the obnoxious weed, water hyacinth (Eichhornia crassipes (Mart.) Solms) in constructed wetlands (floating aquatic macrophyte-based plant treatment systems) to phytoremediate Fe-rich wastewaters seems to be an appealing option. Although several studies have documented that hyacinths are good metal-accumulating plants none of these studies have documented the ability of this plant grown under different nutrient conditions to remove heavy metals from wastewaters. This paper, therefore, reports the phytoremediation efficiencies of water hyacinth grown under different nutrient conditions for Fe-rich wastewaters in batch-type constructed wetlands. This study was conducted for 15 weeks after 1-week acclimatization by culturing young water hyacinth plants (average height of 20+/-2cm) in 590L capacity fiberglass tanks under different nutrient concentrations of 1-fold [28 and 7.7mg/L of total nitrogen (TN) and total phosphorous (TP), respectively], 2-fold, 1/2-fold, 1/4-fold and 1/8-fold with synthetic wastewaters containing 9.27Femg/L. Another set-up of hyacinths containing only Fe as a heavy metal but without any nutrients (i.e., 0-fold) was also studied. A mass balance was carried out to investigate the phytoremediation efficiencies and to determine the different mechanisms governing Fe removal from the wastewaters. Fe removal was largely due to phytoremediation mainly through the process of rhizofiltration and chemical precipitation of Fe2O3 and FeOH3 followed by flocculation and sedimentation. However, chemical precipitation was more significant especially during the first 3 weeks of the study. Plants grown in the 0-fold set-up showed the highest phytoremediation efficiency of 47% during optimum growth at the 6th week with a highest accumulation of 6707Femg/kg dry

The effect of nitrate and phosphate availability on Emiliania huxleyi (NZEH) physiology under different CO2 scenarios.

PubMed

Rouco, Mónica; Branson, Oscar; Lebrato, Mario; Iglesias-Rodríguez, M Débora

2013-01-01

Growth and calcification of the marine coccolithophorid Emiliania huxleyi is affected by ocean acidification and macronutrients limitation and its response varies between strains. Here we investigated the physiological performance of a highly calcified E. huxleyi strain, NZEH, in a multiparametric experiment. Cells were exposed to different CO2 levels (ranging from 250 to 1314 μatm) under three nutrient conditions [nutrient replete (R), nitrate limited (-N), and phosphate limited (-P)]. We focused on calcite and organic carbon quotas and on nitrate and phosphate utilization by analyzing the activity of nitrate reductase (NRase) and alkaline phosphatase (APase), respectively. Particulate inorganic (PIC) and organic (POC) carbon quotas increased with increasing CO2 under R conditions but a different pattern was observed under nutrient limitation. The PIC:POC ratio decreased with increasing CO2 in nutrient limited cultures. Coccolith length increased with CO2 under all nutrient conditions but the coccosphere volume varied depending on the nutrient treatment. Maximum APase activity was found at 561 μatm of CO2 (pH 7.92) in -P cultures and in R conditions, NRase activity increased linearly with CO2. These results suggest that E. huxleyi's competitive ability for nutrient uptake might be altered in future high-CO2 oceans. The combined dataset will be useful in model parameterizations of the carbon cycle and ocean acidification.

Characterization of Pseudomonas putida Genes Responsive to Nutrient Limitation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Syn, Chris K.; Magnuson, Jon K.; Kingsley, Mark T.

2004-06-01

The low bioavailability of nutrients and oxygen in the soil environment has hampered successful expression of biodegradation/biocontrol genes that are driven by promoters highly active during routine laboratory conditions of high nutrient- and oxygen-availability. Hence, in the present study, expression of the gus-tagged genes in 12 Tn5-gus mutants of the soil microbe Pseudomonas putida PNL-MK25 was examined under various conditions chosen to mimic the soil environment: low carbon, phosphate, nitrate, or oxygen, and in the rhizosphere. Based on their expression profiles, three nutrient-responsive mutant (NRM) strains, NRM5, NRM7, and NRM17, were selected for identification of the tagged genes. In themore » mutant strain NRM5, expression of the glutamate dehydrogenase (gdhA) gene was increased between 4.9- to 26.4-fold under various low nutrient conditions. In NRM7, expression of the novel NADPH:quinone oxidoreductase-like (nql) gene was consistently amongst the highest and was synergistically upregulated by low nutrient and anoxic conditions. The cyoD gene in NRM17, which encodes the fourth subunit of the cytochrome o ubiquinol oxidase complex, had decreased expression in low nutrient conditions but its absolute expression levels was still amongst the highest. Additionally, it was independent of oxygen availability, in contrast to that in E. coli.« less

Toxicity of titanium dioxide nanoparticles to Chlorella vulgaris Beyerinck (Beijerinck) 1890 (Trebouxiophyceae, Chlorophyta) under changing nitrogen conditions.

PubMed

Dauda, Suleiman; Chia, Mathias Ahii; Bako, Sunday Paul

2017-06-01

The broad application of titanium dioxide nanoparticles (n-TiO 2 ) in many consumer products has resulted in the release of substantial quantities into aquatic systems. While n-TiO 2 have been shown to induce some unexpected toxic effects on aquatic organisms such as microalgae, the influence of changing nutrient conditions on the toxicity of the metal has not been investigated. We evaluated the toxicity of n-TiO 2 to Chlorella vulgaris under varying nitrogen conditions. Limited nitrogen (2.2μM) decreased growth and biomass (dry weight and pigment content), while lipid peroxidation (malondialdehyde content), glutathione S-transferase activity (GST) and peroxidase (POD) activity were increased. Similarly, exposure to n-TiO 2 under replete nitrogen condition resulted in a general decrease in growth and biomass, while GST and POD activities were significantly increased. The combination of limited nitrogen with n-TiO 2 exposure further decreased growth and biomass, and increased GST and POD activities of the microalga. These results suggest that in addition to the individual effects of each investigated condition, nitrogen limitation makes C. vulgaris more susceptible to the effects of n-TiO 2 with regard to some physiological parameters. This implies that the exposure of C. vulgaris and possibly other green algae to this nanoparticle under limited or low nitrogen conditions may negatively affect their contribution to primary production in oligotrophic aquatic ecosystems. Copyright © 2017 Elsevier B.V. All rights reserved.

Optimal N:P ratios of growth media: quantification of nutrient-replete growth rates in five ion hyperspace for Chlorella vulgaris (Dinophyceae) and Peridinium cinctum (Dinophyceae).

USDA-ARS?s Scientific Manuscript database

In this study our principal goal was to quantify the main effects and interactions of several primary nutrient and bulk solution ions. The total ion concentration range chosen spans fresh to brackish waters (1-30 milliMolar) and explores most of the hypervolume delineated by the five ion/concentrat...

Artificial Soil With Build-In Plant Nutrients

NASA Technical Reports Server (NTRS)

Ming, Douglas W.; Allen, Earl; Henninger, Donald; Golden, D. C.

1995-01-01

Nutrients contained in sandlike material. Artificial soil provides nutrients to plants during several growing seasons without need to add fertilizer or nutrient solution. When watered, artificial soil slowly releases all materials a plant needs to grow. Developed as medium for growing crops in space. Also used to grow plants on Earth under controlled conditions or even to augment natural soil.

Proximate and Ultimate Limiting Nutrients in the Mississippi River Plume: Implications for Hypoxia Reduction Through Nutrient Management

NASA Astrophysics Data System (ADS)

Fennel, K.; Laurent, A.

2016-02-01

A large hypoxic area (15,000 km2 on average) forms every summer over the Texas-Louisiana shelf in the northern Gulf of Mexico due to decay of organic matter that is primarily derived from nutrient inputs from the Mississippi/Atchafalaya River System. Efforts are underway to reduce the extent of hypoxic conditions through nutrient management in the watershed; for example, an interagency Hypoxia Task Force is developing Action Plans with input from various stakeholders that set out targets for hypoxia reduction. An open question is by how much nutrient loads would have to be decreased in order to produce the desired reductions in hypoxia and when these would be measurable over natural variability. We have performed a large number of multi-year nutrient load reduction scenarios with a regional biogeochemical model for the region. The model is based on the Regional Ocean Modeling System (ROMS), explicitly includes nitrogen (N) and phosphorus (P) species as inorganic nutrients, and has been shown to realistically reproduce the key processes responsible for hypoxia generation. We have quantified the effects of differential reductions in river N and P loads on hypoxic extent. An assessment of the effects of N versus P reductions is important because, thus far, nutrient management efforts have focused on N, yet P is known to limit primary production in spring and early summer. A debate is ongoing as to whether targets for P reductions should be set and whether nutrient reduction efforts should focus solely on P, which results primarily from urban and industrial point sources and is uncoupled from agricultural fertilizer application. Our results strongly indicate that N is the `ultimate' limiting nutrient to primary production determining the areal extent and duration of hypoxic conditions in a cumulative sense, while P is temporarily limiting in spring. Although reductions in river P load would decrease hypoxic extent in early summer, they would have a much smaller effect

Parasite and nutrient enrichment effects on Daphnia interspecific competition.

PubMed

Decaestecker, Ellen; Verreydt, Dino; De Meester, Luc; Declerck, Steven A J

2015-05-01

Increased productivity due to nutrient enrichment is hypothesized to affect density-dependent processes, such as transmission success of horizontally transmitting parasites. Changes in nutrient availability can also modify the stoichiometry and condition of individual hosts, which may affect their susceptibility for parasites as well as the growth conditions for parasites within the host. Consequently, if not balanced by increased host immuno-competence or life history responses, changes in the magnitude of parasite effects with increasing nutrient availability are expected. If these parasite effects are host-species specific, this may lead to shifts in the host community structure. We here used the Daphnia- parasite model system to study the effect of nutrient enrichment on parasite-mediated competition in experimental mesocosms. In the absence of parasites, D. magna was competitively dominant to D. pulex at both low and high nutrient levels. Introduction of parasites resulted in infections of D. magna, but not of D. pulex and, as such, reversed the competitive hierarchy between these two species. Nutrient addition resulted in an increased prevalence and infection intensity of some of the parasites on D. magna. However, there was no evidence that high nutrient levels enhanced negative effects of parasites on the hosts. Costs associated with parasite infections may have been compensated by better growth conditions for D. magna in the presence of high nutrient levels.

Growth on ATP Elicits a P-Stress Response in the Picoeukaryote Micromonas pusilla

PubMed Central

Whitney, LeAnn P.; Lomas, Michael W.

2016-01-01

The surface waters of oligotrophic oceans have chronically low phosphate (Pi) concentrations, which renders dissolved organic phosphorus (DOP) an important nutrient source. In the subtropical North Atlantic, cyanobacteria are often numerically dominant, but picoeukaryotes can dominate autotrophic biomass and productivity making them important contributors to the ocean carbon cycle. Despite their importance, little is known regarding the metabolic response of picoeukaryotes to changes in phosphorus (P) source and availability. To understand the molecular mechanisms that regulate P utilization in oligotrophic environments, we evaluated transcriptomes of the picoeukaryote Micromonas pusilla grown under Pi-replete and -deficient conditions, with an additional investigation of growth on DOP in replete conditions. Genes that function in sulfolipid substitution and Pi uptake increased in expression with Pi-deficiency, suggesting cells were reallocating cellular P and increasing P acquisition capabilities. Pi-deficient M. pusilla cells also increased alkaline phosphatase activity and reduced their cellular P content. Cells grown with DOP were able to maintain relatively high growth rates, however the transcriptomic response was more similar to the Pi-deficient response than that seen in cells grown under Pi-replete conditions. The results demonstrate that not all P sources are the same for growth; while M. pusilla, a model picoeukaryote, may grow well on DOP, the metabolic demand is greater than growth on Pi. These findings provide insight into the cellular strategies which may be used to support growth in a stratified future ocean predicted to favor picoeukaryotes. PMID:27167623

Degradation of polychlorinated biphenyl mixtures in soil using phanerochaete chrysosporium in nutrient rich, non-ligninolytic conditions

DOEpatents

Yadav, Jagjit S.; Reddy, Chilekampalli A.; Quensen, John F.; Tiedje, James M.

2000-01-01

Substantial degradation of polychlorinated biphenyl (PCB) mixtures is carried out using the white rot fungus Phanerochaete chrysosporium, under nutrient, carbon and nitrogen source rich, non-ligninolytic conditions. The PCBs with various numbers of ortho, meta, and para chlorines were extensively degraded, indicating relative nonspecificity for the position of chlorine substitutions on the biphenyl ring. Maximal degradation of PCBs in a mixture was observed in malt extract medium (18.4% on a molar basis), in which most of the individual PCBs were degraded.

Sensitivity of bacterioplankton nitrogen metabolism to eutrophication in sub-tropical coastal waters of Key West, Florida.

PubMed

Hoch, Matthew P; Dillon, Kevin S; Coffin, Richard B; Cifuentes, Luis A

2008-05-01

Expression of intracellular ammonium assimilation enzymes were used to assess the response of nitrogen (N) metabolism in bacterioplankton to N-loading of sub-tropical coastal waters of Key West, Florida. Specific activities of glutamine synthetase (GS) and total glutamate dehydrogenase (GDHT) were measured on the bacterial size fraction (<0.8 microm) to assess N-deplete versus N-replete metabolic states, respectively. Enzyme results were compared to concentrations of dissolved organic matter and nutrients and to the biomass and production of phytoplankton and bacteria. Concentrations of dissolved inorganic N (DIN), dissolved organic N (DON), and dissolved organic carbon (DOC) positively correlated with specific activities of GDHT and negatively correlated with that of GS. Total dissolved N (TDN) concentration explained 81% of variance in bacterioplankton GDHT:GS activity ratio. The GDHT:GS ratio, TDN, DOC, and bacterial parameters decreased in magnitude along a tidally dynamic trophic gradient from north of Key West to south at the reef tract, which is consistent with the combined effects of localized coastal eutrophication and tidal exchange of seawater from the Southwest Florida Shelf and Florida Strait. The N-replete bacterioplankton north of Key West can regenerate ammonium which sustains primary production transported south to the reef. The range in GDHT:GS ratios was 5-30 times greater than that for commonly used indicators of planktonic eutrophication, which emphasizes the sensitivity of bacterioplankton N-metabolism to changes in N-bioavailability caused by nutrient pollution in sub-tropical coastal waters and utility of GDHT:GS ratio as an bioindicator of N-replete conditions.

Proximate versus ultimate limiting nutrients in the Mississippi River Plume and Implications for Hypoxia Reductions through Nutrient Management

NASA Astrophysics Data System (ADS)

Fennel, Katja; Laurent, Arnaud

2016-04-01

A large hypoxic area (15,000 km2 on average) forms every summer over the Texas-Louisiana shelf in the northern Gulf of Mexico due to decay of organic matter that is primarily derived from nutrient inputs from the Mississippi/Atchafalaya River System. Efforts are underway to reduce the extent of hypoxic conditions through nutrient management in the watershed; for example, an interagency Hypoxia Task Force is developing Action Plans with input from various stakeholders that set out targets for hypoxia reduction. An open question is how far nutrient loads would have to be decreased in order to produce the desired reductions in hypoxia and when these would be measurable given significant natural variability. We have simulated a large number of multi-year nutrient load reduction scenarios with a regional biogeochemical model for the region. The model is based on the Regional Ocean Modeling System (ROMS), explicitly includes nitrogen (N) and phosphorus (P) species as inorganic nutrients, and has been shown to realistically reproduce the key processes responsible for hypoxia generation. We have quantified the effects of differential reductions in river N and P loads on hypoxic extent. An assessment of the effects of N versus P reductions is important because, thus far, nutrient management efforts have focused on N, yet P is known to limit primary production in spring and early summer. A debate is ongoing as to whether targets for P reductions should be set and whether nutrient reduction efforts should focus solely on P, which results primarily from urban and industrial point sources and is uncoupled from agricultural fertilizer application. Our results strongly indicate that N is the 'ultimate' limiting nutrient to primary production determining the areal extent and duration of hypoxic conditions in a cumulative sense, while P is temporarily limiting in spring. Although reductions in river P load would decrease hypoxic extent in early summer, they would have a much

Nutrient and algal responses to winterkilled fish-derived nutrient subsidies in eutrophic lakes

USGS Publications Warehouse

Schoenebeck, Casey W.; Brown, Michael L.; Chipps, Steven R.; German, David R.

2012-01-01

Fishes inhabiting shallow, glacial lakes of the Prairie Pothole Region in the United States and Canada periodically experience hypoxia in severe winters that can lead to extensive fish mortality resulting in high biomasses of dead fish. However, the role of carcass-derived nutrient subsidies in shallow, eutrophic lakes translocated to pelagic primary producers is not well documented. This study quantified the influence of winterkill events on nutrient contributions from decaying fish carcasses of common carp (Cyprinus carpio) and the phytoplankton response among pre- and postwinterkill years and compared seasonal patterns of nutrient limitation and phytoplankton community composition between winterkill and nonwinterkill lakes. We found that fish carcasses contributed an estimated 2.5–4.3 kg/ha of total (Kjeldahl) nitrogen (N) and 0.3–0.5 kg/ha of total phosphorus (P) to lakes that experienced winterkill conditions. Nutrient bioassays showed that winterkill lakes were primarily N limited, congruent with the low N:P ratios produced by fish carcasses corrected for the disproportionate release of N and P (8.6). Nutrient subsidies translocated from decomposed fish to pelagic primary producers seemed to have little immediate influence on the seasonal phytoplankton community composition, but total N and subsequent chlorophyll-a increased the year following the winterkill event. Cyanobacteria density varied seasonally but was higher in winterkill lakes, presumably due to the integration of nutrients released from fish decomposition. This study provides evidence that large inputs of autochthonous fish-derived nutrients contribute to nutrient availability within winterkilled systems and increase the maximum attainable biomass of the phytoplankton community.

Microgravity alters the physiological characteristics of Escherichia coli O157:H7 ATCC 35150, ATCC 43889, and ATCC 43895 under different nutrient conditions.

PubMed

Kim, H W; Matin, A; Rhee, M S

2014-04-01

The aim of this study is to provide understanding of microgravity effects on important food-borne bacteria, Escherichia coli O157:H7 ATCC 35150, ATCC 43889, and ATCC 43895, cultured in nutrient-rich or minimal medium. Physiological characteristics, such as growth (measured by optical density and plating), cell morphology, and pH, were monitored under low-shear modeled microgravity (LSMMG; space conditions) and normal gravity (NG; Earth conditions). In nutrient-rich medium, all strains except ATCC 35150 showed significantly higher optical density after 6 h of culture under LSMMG conditions than under NG conditions (P < 0.05). LSMMG-cultured cells were approximately 1.8 times larger than NG-cultured cells at 24 h; therefore, it was assumed that the increase in optical density was due to the size of individual cells rather than an increase in the cell population. The higher pH of the NG cultures relative to that of the LSMMG cultures suggests that nitrogen metabolism was slower in the latter. After 24 h of culturing in minimal media, LSMMG-cultured cells had an optical density 1.3 times higher than that of NG-cultured cells; thus, the higher optical density in the LSMMG cultures may be due to an increase in both cell size and number. Since bacteria actively grew under LSMMG conditions in minimal medium despite the lower pH, it is of some concern that LSMMG-cultured E. coli O157:H7 may be able to adapt well to acidic environments. These changes may be caused by changes in nutrient metabolism under LSMMG conditions, although this needs to be demonstrated in future studies.

CO2 and vitamin B12 interactions determine bioactive trace metal requirements of a subarctic Pacific diatom.

PubMed

King, Andrew L; Sañudo-Wilhelmy, Sergio A; Leblanc, Karine; Hutchins, David A; Fu, Feixue

2011-08-01

Phytoplankton growth can be limited by numerous inorganic nutrients and organic growth factors. Using the subarctic diatom Attheya sp. in culture studies, we examined how the availability of vitamin B(12) and carbon dioxide partial pressure (pCO(2)) influences growth rate, primary productivity, cellular iron (Fe), cobalt (Co), zinc (Zn) and cadmium (Cd) quotas, and the net use efficiencies (NUEs) of these bioactive trace metals (mol C fixed per mol cellular trace metal per day). Under B(12)-replete conditions, cells grown at high pCO(2) had lower Fe, Zn and Cd quotas, and used those trace metals more efficiently in comparison with cells grown at low pCO(2). At high pCO(2), B(12)-limited cells had ~50% lower specific growth and carbon fixation rates, and used Fe ~15-fold less efficiently, and Zn and Cd ~3-fold less efficiently, in comparison with B(12)-replete cells. The observed higher Fe, Zn and Cd NUE under high pCO(2)/B(12)-replete conditions are consistent with predicted downregulation of carbon-concentrating mechanisms. Co quotas of B(12)-replete cells were ∼5- to 14-fold higher in comparison with B(12)-limited cells, suggesting that >80% of cellular Co of B(12)-limited cells was likely from B(12). Our results demonstrate that CO(2) and vitamin B(12) interactively influence growth, carbon fixation, trace metal requirements and trace metal NUE of this diatom. This suggests the need to consider complex feedback interactions between multiple environmental factors for this biogeochemically critical group of phytoplankton in the last glacial maximum as well as the current and future changing ocean.

Variation in defence strategies in two species of the genus Beilschmiedia under differing soil nutrient and rainfall conditions.

PubMed

Simon, J; Miller, R E; Woodrow, I E

2007-01-01

The relationships between various leaf functional traits that are important in plant growth (e.g., specific leaf area) have been investigated in recent studies; however, research in this context on plants that are highly protected by chemical defences, particularly resource-demanding nitrogen-based defence, is lacking. We collected leaves from cyanogenic (N-defended) Beilschmiedia collina B. Hyland and acyanogenic (C-defended) Beilschmiedia tooram (F. M. Bailey) B. Hyland at high- and low-soil nutrient sites in two consecutive years that varied significantly in rainfall. We then measured the relationships between chemical defence and morphological and functional leaf traits under the different environmental conditions. We found that the two species differed significantly in their resource allocation to defence as well as leaf morphology and function. The N defended species had a higher leaf nitrogen concentration, whereas the C-defended species had higher amounts of C-based chemical defences (i.e., total phenolics and condensed tannins). The C-defended species also tended to have higher force to fracture and increased leaf toughness. In B. collina, cyanogenic glycoside concentration was higher with higher rainfall, but not with higher soil nutrients. Total phenolic concentration was higher at the high soil nutrient site in B. tooram, but lower in B. collina; however, with higher rainfall an increase was found in B. tooram, while phenolics decreased in B. collina. Condensed tannin concentration decreased in both species with rainfall and nutrient availability. We conclude that chemical defence is correlated with leaf functional traits and that variation in environmental resources affects this correlation.

The permissive effect of zinc deficiency on uroguanylin and inducible nitric oxide synthase gene upregulation in rat intestine induced by interleukin 1alpha is rapidly reversed by zinc repletion.

PubMed

Cui, Li; Blanchard, Raymond K; Cousins, Robert J

2003-01-01

Deficient intake of zinc from the diet upregulates both uroguanylin (UG) and inducible nitric oxide synthase (iNOS) expression in rats. Because these changes influence intestinal fluid secretion and intestinal cell pathophysiology, they relate to the incidence of diarrheal disease and its reversal by zinc as well as intestinal inflammation in general. A model of moderate zinc deficiency in rats, which changes molecular indices of zinc deficiency, was used to further explore the effects of the proinflammatory cytokine interleukin (IL)-1alpha and zinc repletion on these changes. IL-1alpha has been shown to have a role in the intestinal inflammation that occurs with bacterial infection. Our results showed a permissive effect of zinc deficiency on both UG and iNOS expression. Specifically, UG expression was responsive to zinc deficiency and IL-1alpha challenge, which were additive when combined, whereas iNOS expression was upregulated by IL-1alpha only during the deficiency. Immunohistochemistry showed that the increase in UG was limited to enterocytes of the upper villus but, in contrast, the increase in iNOS was principally in cells of the lamina propria of IL-1alpha-treated rats. Cells exhibiting UG upregulation did not co-express serotonin. Repletion with zinc reversed upregulation of the iNOS gene within 1 d, whereas UG upregulation required 3-4 d to return to normal. This differential response to repletion suggests that mechanisms of UG and iNOS dysregulation are different. Dysregulation of both genes may contribute to the severity of zinc-responsive diarrheal disease and intestinal inflammatory disease.

Microbial Enzyme Activities of Wetland Soils as Indicators of Nutrient Condition: A Test in Wetlands of Gulf of Mexico Coastal Watershed

EPA Science Inventory

Microbial enzyme activities measured from wetland soils are being tested as indicators of wetland nutrient function and human disturbance. This is part of an assessment of condition of wetlands being conducted by the U.S. EPA Gulf Ecology Division in coastal watersheds along the...

T-cell-replete haploidentical HSCT with low-dose anti-T-lymphocyte globulin compared with matched sibling HSCT and unrelated HSCT.

PubMed

Luo, Yi; Xiao, Haowen; Lai, Xiaoyu; Shi, Jimin; Tan, Yamin; He, Jingsong; Xie, Wanzhuo; Zheng, Weiyan; Zhu, Yuanyuan; Ye, Xiujin; Yu, Xiaohong; Cai, Zhen; Lin, Maofang; Huang, He

2014-10-23

We developed an approach of T-cell-replete haploidentical hematopoietic stem cell transplantation (HSCT) with low-dose anti-T-lymphocyte globulin and prospectively compared outcomes of all contemporaneous T-cell-replete HSCT performed at our center using matched sibling donors (MSDs), unrelated donors (URDs), and haploidentical related donors (HRDs). From 2008 to 2013, 90 patients underwent MSD-HSCT, 116 underwent URD-HSCT, and 99 underwent HRD-HSCT. HRDs were associated with higher incidences of grades 2 to 4 (42.4%) and severe acute graft-versus-host disease (17.2%) and nonrelapse mortality (30.5%), compared with MSDs (15.6%, 5.6%, and 4.7%, respectively; P < .05), but were similar to URDs, even fully 10/10 HLA-matched URDs. For high-risk patients, a superior graft-versus-leukemia effect was observed in HRD-HSCT, with 5-year relapse rates of 15.4% in HRD-HSCT, 28.2% in URD-HSCT (P = .07), and 49.9% in MSD-HSCT (P = .002). Furthermore, 5-year disease-free survival rates were not significantly different for patients undergoing transplantation using 3 types of donors, with 63.6%, 58.4%, and 58.3% for MSD, URD, and HRD transplantation, respectively (P = .574). Our data indicate that outcomes after HSCT from suitably matched URDs and HRDs with low-dose anti-T-lymphocyte globulin are similar and that HRD improves outcomes of patients with high-risk leukemia. This trial was registered at www.chictr.org (Chinese Clinical Trial Registry) as #ChiCTR-OCH-12002490. © 2014 by The American Society of Hematology.

Generalized Nutrient Taxes Can Increase Consumer Welfare.

PubMed

Bishai, David

2015-11-01

Certain nutrients can stimulate appetite making them fattening in a way that is not fully conveyed by the calorie content on the label. For rational eaters, this information gap could be corrected by more labeling. As an alternative, this paper proposes a set of positive and negative taxes on the fattening and slimming nutrients in food rather than on the food itself. There are conditions under which this tax plus subsidy system could increase welfare by stopping unwanted weight gain while leaving the final retail price of food unchanged. A nutrient tax system could improve welfare if fattening nutrients, net of their effect on weight, are inferior goods and the fiscal cost of administering the tax is sufficiently low. More data on the price elasticity of demand for nutrients as well as data on how specific nutrients affect satiety and how total calorie intake would be necessary before one could be sure a nutrient tax would work in practice. Copyright © 2014 John Wiley & Sons, Ltd.

Trends in the nutrient enrichment of U.S. rivers during the late 20th century and their relation to changes in probable stream trophic conditions

USGS Publications Warehouse

Alexander, R.B.; Smith, R.A.

2006-01-01

We estimated trends in concentrations of total phosphorus (TP) and total nitrogen (TN) and the related change in the probabilities of trophic conditions from 1975 to 1994 at 250 nationally representative riverine monitoring locations in the U.S. with drainage areas larger than about 1,000 km2. Statistically significant (p < 0.05) declines were detected in TP and TN concentrations at 44% and 37% of the monitoring sites, and significant increases were detected at 3% and 9% of the sites, respectively. We used a statistical model to assess changes in the probable trophic-state classification of the sites after adjusting for climate-related variability in nutrient concentrations. The probabilistic assessment accounts for current knowledge of the trophic response of streams to nutrient enrichment, based on a recently proposed definition of "eutrophic," "mesotrophic," and "oligotrophic" conditions in relation to total nutrient concentrations. Based on these trophic definitions, we found that the trophic state improved at 25% of the monitoring sites and worsened at fewer than 5% of the sites; about 70% of the sites were unchanged. Improvements in trophic-state related to declines in TP were more common in predominantly forested and shrub-grassland watersheds, whereas the trophic state of predominantly agricultural sites was unchanged. Despite the declines in TP concentrations at many sites, about 50% of all monitoring sites, and more than 60% of the sites in predominantly agricultural and urban watersheds, were classified as eutrophic in 1994 based on TP concentrations. Contemporaneous reductions in major nutrient sources to streams, related to wastewater treatment upgrades, phosphate detergent bans, and declines in some agricultural sources, may have contributed to the declines in riverine nutrient concentrations and associated improvements in trophic conditions. ?? 2006, by the American Society of Limnology and Oceanography, Inc.

Nutrient pollution disrupts key ecosystem functions on coral reefs.

PubMed

Silbiger, Nyssa J; Nelson, Craig E; Remple, Kristina; Sevilla, Jessica K; Quinlan, Zachary A; Putnam, Hollie M; Fox, Michael D; Donahue, Megan J

2018-06-13

There is a long history of examining the impacts of nutrient pollution and pH on coral reefs. However, little is known about how these two stressors interact and influence coral reef ecosystem functioning. Using a six-week nutrient addition experiment, we measured the impact of elevated nitrate (NO - 3 ) and phosphate (PO 3- 4 ) on net community calcification (NCC) and net community production (NCP) rates of individual taxa and combined reef communities. Our study had four major outcomes: (i) NCC rates declined in response to nutrient addition in all substrate types, (ii) the mixed community switched from net calcification to net dissolution under medium and high nutrient conditions, (iii) nutrients augmented pH variability through modified photosynthesis and respiration rates, and (iv) nutrients disrupted the relationship between NCC and aragonite saturation state documented in ambient conditions. These results indicate that the negative effect of NO - 3 and PO 3- 4 addition on reef calcification is likely both a direct physiological response to nutrients and also an indirect response to a shifting pH environment from altered NCP rates. Here, we show that nutrient pollution could make reefs more vulnerable to global changes associated with ocean acidification and accelerate the predicted shift from net accretion to net erosion. © 2018 The Author(s).

Stable isotope-labelled feed nutrients to assess nutrient-specific feed passage kinetics in ruminants.

PubMed

Warner, Daniel; Dijkstra, Jan; Hendriks, Wouter H; Pellikaan, Wilbert F

2014-03-30

Knowledge of digesta passage kinetics in ruminants is essential to predict nutrient supply to the animal in relation to optimal animal performance, environmental pollution and animal health. Fractional passage rates (FPR) of feed are widely used in modern feed evaluation systems and mechanistic rumen models, but data on nutrient-specific FPR are scarce. Such models generally rely on conventional external marker techniques, which do not always describe digesta passage kinetics in a satisfactory manner. Here the use of stable isotope-labelled dietary nutrients as a promising novel tool to assess nutrient-specific passage kinetics is discussed. Some major limitations of this technique include a potential marker migration, a poor isotope distribution in the labelled feed and a differential disappearance rate of isotopes upon microbial fermentation in non-steady state conditions. Such limitations can often be circumvented by using intrinsically stable isotope-labelled plant material. Data are limited but indicate that external particulate markers overestimate rumen FPR of plant fibre compared with the internal stable isotope markers. Stable isotopes undergo the same digestive mechanism as the labelled feed components and are thus of particular interest to specifically measure passage kinetics of digestible dietary nutrients. © 2013 Society of Chemical Industry.

Nutrient Enhancement of Fruit and Effects of Storage Conditions

DTIC Science & Technology

1998-05-01

Cubed, peeled apples, approximately 0.25 in (0.6 cm) Ingredients - apples, high fructose corn syrup , ascorbic and citric acid, (to...addition, a field study of the products also showed high acceptability. Samples stored at 40, 70 and 100 °F were tested at zero time, 1,3, 6, 9, and 12...foods of good nutrition and high sensory acceptability with a reduced cost of processing. Such foods will deliver a high density of nutrients

Response of saliva Na/K ratio to changing Na supply of lactating cows under tropical conditions.

PubMed

Thiangtum, Wandee; Schonewille, J Thomas; Verstegen, Martin Wa; Arsawakulsudhi, Supot; Rukkwamsuk, Theera; Hendriks, Wouter H

2017-06-01

Factorial determination of the sodium (Na) requirement of heat-stressed lactating cows is hindered by accurate estimates of the Na losses through sweat. Direct studies, therefore, may be needed requiring information on the time course of healthy animals to become Na depleted and the subsequent rate of repletion. The rate of Na depletion and subsequent rate of Na repletion with two levels of dietary Na to lactating dairy cows housed under tropical conditions were investigated using the salivary Na/K. The 12 lactating cows (salivary Na/K ratio 14.6) rapidly developed clinical signs of Na deficiency, including pica, polyuria and polydipsia, reduced body weight and reduced milk yield when fed a low-Na ration (0.33 g kg -1 dry matter (DM)) for 3 weeks. Deficiency symptoms were associated with a rapid decrease in salivary Na/K ratio to <4.3 from 7 to 21 days. Subsequent repletion of the cows with NaCl to a ration concentration of 1.1 or 1.6 g Na kg -1 DM for 5 weeks did not restore salivary Na/K ratio to values of >6. A daily Na intake of heat-stressed lactating cows to a ration intake of 1.6 g Na kg -1 DM was insufficient to restore Na deficiency. One week was sufficient to deplete heat-stressed lactating cows of Na, allowing for rapid dose-response studies utilizing the salivary Na/K ratio as a parameter for Na status of cows under tropical conditions. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Accounting for heterogeneity of nutrient dynamics in riverscapes through spatially distributed models

NASA Astrophysics Data System (ADS)

Wollheim, W. M.; Stewart, R. J.

2011-12-01

Numerous types of heterogeneity exist within river systems, leading to hotspots of nutrient sources, sinks, and impacts embedded within an underlying gradient defined by river size. This heterogeneity influences the downstream propagation of anthropogenic impacts across flow conditions. We applied a river network model to explore how nitrogen saturation at river network scales is influenced by the abundance and distribution of potential nutrient processing hotspots (lakes, beaver ponds, tributary junctions, hyporheic zones) under different flow conditions. We determined that under low flow conditions, whole network nutrient removal is relatively insensitive to the number of hotspots because the underlying river network structure has sufficient nutrient processing capacity. However, hotspots become more important at higher flows and greatly influence the spatial distribution of removal within the network at all flows, suggesting that identification of heterogeneity is critical to develop predictive understanding of nutrient removal processes under changing loading and climate conditions. New temporally intensive data from in situ sensors can potentially help to better understand and constrain these dynamics.

In vitro immune functions in thiamine-replete and -depleted lake trout (Salvelinus namaycush)

USGS Publications Warehouse

Ottinger, Christopher A.; Honeyfield, Dale C.; Densmore, Christine L.; Iwanowicz, Luke R.

2014-01-01

In this study we examined the impacts of in vivo thiamine deficiency on lake trout leukocyte function measured in vitro. When compared outside the context of individual-specific thiamine concentrations no significant differences were observed in leukocyte bactericidal activity or in concanavalin A (Con A), and phytohemagglutinin-P (PHA-P) stimulated leukocyte proliferation. Placing immune functions into context with the ratio of in vivo liver thiamine monophosphate (TMP – biologically inactive form) to thiamine pyrophosphate (TPP – biologically active form) proved to be the best indicator of thiamine depletion impacts as determined using regression modeling. These observed relationships indicated differential effects on the immune measures with bactericidal activity exhibiting an inverse relationship with TMP to TPP ratios, Con A stimulated mitogenesis exhibiting a positive relationship with TMP to TPP ratios and PHA-P stimulated mitogenesis exhibiting no significant relationships. In addition, these relationships showed considerable complexity which included the consistent observation of a thiamine-replete subgroup with characteristics similar to those seen in the leukocytes from thiamine-depleted fish. When considered together, our observations indicate that lake trout leukocytes experience cell-type specific impacts as well as an altered physiologic environment when confronted with a thiamine-limited state.

Excess nutrients in hydroponic solutions alter nutrient content of rice, wheat, and potato.

PubMed

McKeehen, J D; Mitchell, C A; Wheeler, R M; Bugbee, B; Nielsen, S S

1996-01-01

Environment has significant effects on the nutrient content of field-grown crop plants. Little is known, however, about compositional changes caused by controlled environments in which plants receive only artificial radiation and soilless, hydroponic culture. This knowledge is essential for developing a safe, nutritious diet in a Controlled Ecological Life-Support System (CELSS). Three crops that are candidates for inclusion in a CELSS (rice, wheat, and white potato) were grown both in the field and in controlled environments where the hydroponic nutrient solution, photosynthetic photon flux (PPF), and CO2 level were manipulated to achieve rapid growth rates. Plants were harvested at maturity, separated into discrete parts, and dried prior to analysis. Plant materials were analyzed for proximate composition (protein, fat, ash, and carbohydrate), total nitrogen (N), nitrate, minerals, and amino-acid composition. The effect of environment on nutrient content varied by crop and plant part. Total N and nonprotein N (NPN) contents of plant biomass generally increased under controlled-environment conditions compared to field conditions, especially for leafy plant parts and roots. Nitrate levels were increased in hydroponically-grown vegetative tissues, but nitrate was excluded from grains and tubers. Mineral content changes in plant tissue included increased phosphorus and decreased levels of certain micronutrient elements under controlled-environment conditions. These findings suggest that cultivar selection, genetic manipulation, and environmental control could be important to obtain highly nutritious biomass in a CELSS.

Excess nutrients in hydroponic solutions alter nutrient content of rice, wheat, and potato

NASA Technical Reports Server (NTRS)

McKeehen, J. D.; Mitchell, C. A.; Wheeler, R. M.; Bugbee, B.; Nielsen, S. S.

1996-01-01

Environment has significant effects on the nutrient content of field-grown crop plants. Little is known, however, about compositional changes caused by controlled environments in which plants receive only artificial radiation and soilless, hydroponic culture. This knowledge is essential for developing a safe, nutritious diet in a Controlled Ecological Life-Support System (CELSS). Three crops that are candidates for inclusion in a CELSS (rice, wheat, and white potato) were grown both in the field and in controlled environments where the hydroponic nutrient solution, photosynthetic photon flux (PPF), and CO2 level were manipulated to achieve rapid growth rates. Plants were harvested at maturity, separated into discrete parts, and dried prior to analysis. Plant materials were analyzed for proximate composition (protein, fat, ash, and carbohydrate), total nitrogen (N), nitrate, minerals, and amino-acid composition. The effect of environment on nutrient content varied by crop and plant part. Total N and nonprotein N (NPN) contents of plant biomass generally increased under controlled-environment conditions compared to field conditions, especially for leafy plant parts and roots. Nitrate levels were increased in hydroponically-grown vegetative tissues, but nitrate was excluded from grains and tubers. Mineral content changes in plant tissue included increased phosphorus and decreased levels of certain micronutrient elements under controlled-environment conditions. These findings suggest that cultivar selection, genetic manipulation, and environmental control could be important to obtain highly nutritious biomass in a CELSS.

Excess nutrients in hydroponic solutions alter nutrient content of rice, wheat, and potato

NASA Astrophysics Data System (ADS)

McKeehen, J. D.; Mitchell, C. A.; Wheeler, R. M.; Bugbee, B.; Nielsen, S. S.

Environment has significant effects on the nutrient content of field-grown crop plants. Little is known, however, about compositional changes caused by controlled environments in which plants receive only artificial radiation and soilless, hydroponic culture. This knowledge is essential for developing a safe, nutritious diet in a Controlled Ecological Life-Support System (CELSS). Three crops that are candidates for inclusion in a CELSS (rice, wheat, and white potato) were grown both in the field and in controlled environments where the hydroponic nutrient solution, photosynthetic photon flux (PPF), and CO_2 level were manipulated to achieve rapid growth rates. Plants were harvested at maturity, separated into discrete parts, and dried prior to analysis. Plant materials were analyzed for proximate composition (protein, fat, ash, and carbohydrate), total nitrogen (N), nitrate, minerals, and amino-acid composition. The effect of environment on nutrient content varied by crop and plant part. Total N and nonprotein N (NPN) contents of plant biomass generally increased under controlled-environment conditions compared to field conditions, especially for leafy plant parts and roots. Nitrate levels were increased in hydroponically-grown vegetative tissues, but nitrate was excluded from grains and tubers. Mineral content changes in plant tissue included increased phosphorus and decreased levels of certain micronutrient elements under controlled-environment conditions. These findings suggest that cultivar selection, genetic manipulation, and environmental control could be important to obtain highly nutritious biomass in a CELSS.

Interactive Effects of Nutrient and Mechanical Stresses on Plant Morphology

PubMed Central

Puijalon, Sara; Lena, Jean-Paul; Bornette, Gudrun

2007-01-01

Background and Aims Plant species frequently encounter multiple stresses under natural conditions, and the way they cope with these stresses is a major determinant of their ecological breadth. The way mechanical (e.g. wind, current) and resource stresses act simultaneously on plant morphological traits has been poorly addressed, even if both stresses often interact. This paper aims to assess whether hydraulic stress affects plant morphology in the same way at different nutrient levels. Methods An examination was made of morphological variations of an aquatic plant species growing under four hydraulic stress (flow velocity) gradients located in four habitats distributed along a nutrient gradient. Morphological traits covering plant size, dry mass allocation, organ water content and foliage architecture were measured. Key Results Significant interactive effects of flow velocity and nutrient level were observed for all morphological traits. In particular, increased flow velocity resulted in size reductions under low nutrient conditions, suggesting an adaptive response to flow stress (escape strategy). On the other hand, moderate increases in flow velocity resulted in increased size under high nutrient conditions, possibly related to an inevitable growth response to a higher nutrient supply induced by water renewal at the plant surface. For some traits (e.g. dry mass allocation), a consistent sense of variation as a result of increasing flow velocity was observed, but the amount of variation was either reduced or amplified under nutrient-rich compared with nutrient-poor conditions, depending on the traits considered. Conclusions These results suggest that, for a given species, a stress factor may result, in contrasting patterns and hence strategies, depending on a second stress factor. Such results emphasize the relevance of studies on plant responses to multiple stresses for understanding the actual ecological breadth of species. PMID:17913725

Soil Properties, Nutrient Dynamics, and Soil Enzyme Activities Associated with Garlic Stalk Decomposition under Various Conditions

PubMed Central

Han, Xu; Cheng, Zhihui; Meng, Huanwen

2012-01-01

The garlic stalk is a byproduct of garlic production and normally abandoned or burned, both of which cause environmental pollution. It is therefore appropriate to determine the conditions of efficient decomposition, and equally appropriate to determine the impact of this decomposition on soil properties. In this study, the soil properties, enzyme activities and nutrient dynamics associated with the decomposition of garlic stalk at different temperatures, concentrations and durations were investigated. Stalk decomposition significantly increased the values of soil pH and electrical conductivity. In addition, total nitrogen and organic carbon concentration were significantly increased by decomposing stalks at 40°C, with a 5∶100 ratio and for 10 or 60 days. The highest activities of sucrase, urease and alkaline phosphatase in soil were detected when stalk decomposition was performed at the lowest temperature (10°C), highest concentration (5∶100), and shortest duration (10 or 20 days). The evidence presented here suggests that garlic stalk decomposition improves the quality of soil by altering the value of soil pH and electrical conductivity and by changing nutrient dynamics and soil enzyme activity, compared to the soil decomposition without garlic stalks. PMID:23226411

Carbon Metabolism of Prochlorococcus sp. Under Nitrogen Limitation

NASA Astrophysics Data System (ADS)

Szul, M.

2016-02-01

Phytoplankton growth rates are limited by nutrient availability in the world's euphotic oligotrophic oceans. In these vast biomes, convergent evolutions of the dominant planktonic populations suggest traits such as small genome and cell size provide selective advantages. While these traits have been shown to improve both thrift and competition for scarce nutrients, how fitness is manifest through reductive evolution on metabolisms remains poorly understood. To develop a better understanding of carbon fate and flux under nutrient limitation, we grew axenic Prochlorococcus under nitrogen-limited and nitrogen-replete conditions and measured metabolite pools, the flux of carbon through these pools as well as photosynthesis, photosystem health and efficiency. Our data show cells under nitrogen limitation reduce rates of both metabolite flux and total carbon fixation while maintaining elevated metabolite pool levels and releasing a larger proportion of total fixed carbon to the environment. Accounting for these observations, potential metabolic mechanisms that contribute to the fitness of Prochlorococcus in the nutrient limited oceans will be discussed.

Comparison of stream nutrient conditions in a subtropical lowland watershed to EPA suggested criteria

Treesearch

April Mason; Y. Jun Xu; Johnny M. Grace

2007-01-01

Nutrients such as nitrogen, phosphorus and organic carbon are essential to the health and diversity of stream ecosystems. However, excess nutrients can cause eutrophication, resulting in overgrowth of aquatic plants and decline of the ecosystem diversity. A paired-watershed study was initiated in a subtropical forested watershed within the Ouachita River Basin in...

Growth on ATP elicits a P-stress response in the picoeukaryote Micromonas pusilla

DOE PAGES

Whitney, LeAnn P.; Lomas, Michael W.

2016-05-11

The surface waters of oligotrophic oceans have chronically low phosphate (P i) concentrations, which renders dissolved organic phosphorus (DOP) an important nutrient source. In the subtropical North Atlantic, cyanobacteria are often numerically dominant, but picoeukaryotes can dominate autotrophic biomass and productivity making them important contributors to the ocean carbon cycle. Despite their importance, little is known regarding the metabolic response of picoeukaryotes to changes in phosphorus (P) source and availability. To understand the molecular mechanisms that regulate P utilization in oligotrophic environments, we evaluated transcriptomes of the picoeukaryote Micromonas pusilla grown under P i-replete and -deficient conditions, with an additionalmore » investigation of growth on DOP in replete conditions. Genes that function in sulfolipid substitution and P i uptake increased in expression with P i-deficiency, suggesting cells were reallocating cellular P and increasing P acquisition capabilities. P i-deficient M. pusilla cells also increased alkaline phosphatase activity and reduced their cellular P content. Cells grown with DOP were able to maintain relatively high growth rates, however the transcriptomic response was more similar to the P i-deficient response than that seen in cells grown under P i-replete conditions. The results demonstrate that not all P sources are the same for growth; while M. pusilla, a model picoeukaryote, may grow well on DOP, the metabolic demand is greater than growth on P i. Lastly, these findings provide insight into the cellular strategies which may be used to support growth in a stratified future ocean predicted to favor picoeukaryotes.« less

Real-time monitoring of nutrients in the Changjiang Estuary reveals short-term nutrient-algal bloom dynamics

NASA Astrophysics Data System (ADS)

Wang, Kui; Chen, Jianfang; Ni, Xiaobo; Zeng, Dingyong; Li, Dewang; Jin, Haiyan; Glibert, Patricia M.; Qiu, Wenxian; Huang, Daji

2017-07-01

The Changjiang Estuary is a large-river estuary ecosystem in the East China Sea, and its plume, the Changjiang Diluted Water (CDW), transports a large mass of nutrients (NO3- + NO2-, PO43-, SiO32-) to the shelf sea, leading to substantial eutrophication; the CDW also supports high primary production. However, relationships between nutrient delivery and phytoplankton responses have been difficult to establish, as many nutrient delivery events and algal blooms are episodic, and the CDW may expand or become detached with changing winds. To study the relationship between nutrient delivery events, algal blooms and estuarine metabolism dynamics, a buoy system was deployed in the CDW from 9 September to 10 October 2013, with measurements of chlorophyll a and dissolved nutrients. Day-to-day nutrient increases covaried with salinity decreases, regulated by both the spring-neap tidal cycle and wind events. Several specific nutrient injection periods were detected, each followed by nutrient drawdown and chlorophyll a accumulation (algal blooms). Each algal bloom had its own unique pattern of nutrient uptake based on change in nutrient ratios (ΔN:ΔP; ΔN:ΔSi) and appeared to be dominated by different algal groups. These events occurred under weak wind and stable hydrodynamic conditions. Ecosystem metabolism based on net community production (NCP) showed that the upper estuarine ecosystem was autotrophic when chlorophyll a accumulated, but heterotrophic when wind-induced mixing strengthened, and upwelling brought organic-rich water to the near surface. In spite of several short-lived algal blooms, the average NCPdaily was negative during the observation period, indicating a net source of CO2 to the atmosphere.

Multicellular behavior of environmental Escherichia coli isolates grown under nutrient-poor and low-temperature conditions.

PubMed

Di Sante, Laura; Pugnaloni, Armanda; Biavasco, Francesca; Giovanetti, Eleonora; Vignaroli, Carla

2018-05-01

The multicellular behavior designated "red dry and rough" (rdar) morphotype-characterized by production of extracellular matrix mainly comprising curli fimbriae and cellulose-is a potential survival strategy of Escherichia coli outside the host. This study documents the ability of Escherichia cryptic clades, which have recently been recognized as new lineages genetically divergent from E. coli, to grow in unfavorable conditions through expression of distinct phenotypes. Growth under low-temperature and nutrient-poor conditions induced the rdar morphotype in all cryptic clade strains tested, especially after preincubation in broth supplemented with uracil. Such phenotypic response to harsh growth conditions was clearly detected by transmission and scanning electron microscopy, which showed that bacteria were encased in a fibrous matrix. Conversely, cells incubated in rich medium at 37 °C showed no matrix. Uracil enhanced the biosynthesis of matrix components, fostering biofilm production and strain adhesion to abiotic surfaces, as demonstrated by the increase of strong biofilm producers in biofilm assays. Harsh growth conditions also induced catalase activity, resulting in clade strain resistance to hydrogen peroxide oxidative stress. The present findings further support the 'environmental hypothesis' whereby cryptic clades would be able to persist in natural habitats outside the host through the expression of distinct survival phenotypes. Copyright © 2018 Elsevier GmbH. All rights reserved.

The interplay between estuarine transport and biogeochemical processes in determining the nutrient conditions in bottom layers of non-tidal Gulf of Finland

NASA Astrophysics Data System (ADS)

Kõuts, Mariliis; Raudsepp, Urmas; Maljutenko, Ilja

2017-04-01

In coastal areas, especially estuaries, spatial distribution and seasonal cycling of chemical and biological variables is largely determined by local biogeochemical processes and water transport of different properties. In tidal estuaries, however, biogeochemical processes are affected by tides as frequent water exchange alters nutrient and oxygen concentrations. In wide and deep non-tidal estuary-type marginal seas spatial distribution and seasonal cycling are determined by the mixture of water transport and local biogeochemistry. The Baltic Sea is a stratified water basin where halocline divides the water column into two parts: upper layer, which is horizontally uniform in terms of distribution of chemical and biological parameters, and has clear seasonal cycle; and bottom part, where nutrient and oxygen dynamics is more complex. There water transport and sediment-water interface fluxes play a major role. Our prime focus is the Gulf of Finland in the Baltic Sea. It is a wide, non-tidal and stratified sub-basin known for its high nutrient concentrations and severe oxygen deficiency in summer. We modelled the Baltic Sea (including Gulf of Finland) using ERGOM, a biogeochemical model coupled with circulation model GETM. Seasonal cycling and water circulation were observed with a 40-year simulation from 1966 to 2006. Our results show that in shallow areas above halocline the seasonal cycle of phytoplankton, nutrients and oxygen concentrations is uniform in space. Water circulation does not create inhomogeneous distribution pattern of biogeochemical parameters and their seasonal cycle. The circulation in the Gulf of Finland is strongly modulated by the seasonality of estuarine transport. Below the halocline saline low-oxygen and nutrient-rich water is transported from the open Baltic Proper to the Gulf of Finland in spring and early summer. This results in the highest nutrient concentrations and the poorest oxygen conditions by the end of August. In the shallow area

Nutrient sensing modulates malaria parasite virulence

PubMed Central

Mancio-Silva, Liliana; Slavic, Ksenija; Grilo Ruivo, Margarida T.; Grosso, Ana Rita; Modrzynska, Katarzyna K.; Vera, Iset Medina; Sales-Dias, Joana; Gomes, Ana Rita; MacPherson, Cameron Ross; Crozet, Pierre; Adamo, Mattia; Baena-Gonzalez, Elena; Tewari, Rita; Llinás, Manuel; Billker, Oliver; Mota, Maria M.

2017-01-01

The lifestyle of intracellular pathogens, such as malaria parasites, is intimately connected to that of their host(s), primarily for nutrient supply. Nutrients act not only as primary sources of energy but also as regulators of gene expression, metabolism and growth, through various signaling networks that confer to cells the ability to sense and adapt to varying environmental conditions1,2. Canonical nutrient-sensing pathways are presumably absent in the causing agent of malaria Plasmodium3–5, thus raising the question of whether these parasites possess the capacity to sense and cope with host nutrient fluctuations. Here, we show that Plasmodium blood-stage parasites actively respond to host dietary calorie alterations through a rearrangement of their transcriptome accompanied by a significant adjustment of their multiplication rate. A kinome analysis combined with chemical and genetic approaches identified KIN as a critical regulator that mediates sensing of nutrients and controls a transcriptional response to the host nutritional status. KIN shares homology to SNF1/AMPKα and yeast complementation studies suggest functional conservation of an ancient cellular energy sensing pathway. Overall, these findings reveal a key parasite nutrient-sensing mechanism that is critical to modulate parasite replication and virulence. PMID:28678779

Nutrient sensing modulates malaria parasite virulence.

PubMed

Mancio-Silva, Liliana; Slavic, Ksenija; Grilo Ruivo, Margarida T; Grosso, Ana Rita; Modrzynska, Katarzyna K; Vera, Iset Medina; Sales-Dias, Joana; Gomes, Ana Rita; MacPherson, Cameron Ross; Crozet, Pierre; Adamo, Mattia; Baena-Gonzalez, Elena; Tewari, Rita; Llinás, Manuel; Billker, Oliver; Mota, Maria M

2017-07-13

The lifestyle of intracellular pathogens, such as malaria parasites, is intimately connected to that of their host, primarily for nutrient supply. Nutrients act not only as primary sources of energy but also as regulators of gene expression, metabolism and growth, through various signalling networks that enable cells to sense and adapt to varying environmental conditions. Canonical nutrient-sensing pathways are presumed to be absent from the causative agent of malaria, Plasmodium, thus raising the question of whether these parasites can sense and cope with fluctuations in host nutrient levels. Here we show that Plasmodium blood-stage parasites actively respond to host dietary calorie alterations through rearrangement of their transcriptome accompanied by substantial adjustment of their multiplication rate. A kinome analysis combined with chemical and genetic approaches identified KIN as a critical regulator that mediates sensing of nutrients and controls a transcriptional response to the host nutritional status. KIN shares homology with SNF1/AMPKα, and yeast complementation studies suggest that it is part of a functionally conserved cellular energy-sensing pathway. Overall, these findings reveal a key parasite nutrient-sensing mechanism that is critical for modulating parasite replication and virulence.

Nutrients Turned into Toxins: Microbiota Modulation of Nutrient Properties in Chronic Kidney Disease

PubMed Central

Fernandez-Prado, Raul; Esteras, Raquel; Perez-Gomez, Maria Vanessa; Gracia-Iguacel, Carolina; Gonzalez-Parra, Emilio; Sanz, Ana B.; Ortiz, Alberto; Sanchez-Niño, Maria Dolores

2017-01-01

In chronic kidney disease (CKD), accumulation of uremic toxins is associated with an increased risk of death. Some uremic toxins are ingested with the diet, such as phosphate and star fruit-derived caramboxin. Others result from nutrient processing by gut microbiota, yielding precursors of uremic toxins or uremic toxins themselves. These nutrients include l-carnitine, choline/phosphatidylcholine, tryptophan and tyrosine, which are also sold over-the-counter as nutritional supplements. Physicians and patients alike should be aware that, in CKD patients, the use of these supplements may lead to potentially toxic effects. Unfortunately, most patients with CKD are not aware of their condition. Some of the dietary components may modify the gut microbiota, increasing the number of bacteria that process them to yield uremic toxins, such as trimethylamine N-Oxide (TMAO), p-cresyl sulfate, indoxyl sulfate and indole-3 acetic acid. Circulating levels of nutrient-derived uremic toxins are associated to increased risk of death and cardiovascular disease and there is evidence that this association may be causal. Future developments may include maneuvers to modify gut processing or absorption of these nutrients or derivatives to improve CKD patient outcomes. PMID:28498348

Nutrients Turned into Toxins: Microbiota Modulation of Nutrient Properties in Chronic Kidney Disease.

PubMed

Fernandez-Prado, Raul; Esteras, Raquel; Perez-Gomez, Maria Vanessa; Gracia-Iguacel, Carolina; Gonzalez-Parra, Emilio; Sanz, Ana B; Ortiz, Alberto; Sanchez-Niño, Maria Dolores

2017-05-12

In chronic kidney disease (CKD), accumulation of uremic toxins is associated with an increased risk of death. Some uremic toxins are ingested with the diet, such as phosphate and star fruit-derived caramboxin. Others result from nutrient processing by gut microbiota, yielding precursors of uremic toxins or uremic toxins themselves. These nutrients include l-carnitine, choline/phosphatidylcholine, tryptophan and tyrosine, which are also sold over-the-counter as nutritional supplements. Physicians and patients alike should be aware that, in CKD patients, the use of these supplements may lead to potentially toxic effects. Unfortunately, most patients with CKD are not aware of their condition. Some of the dietary components may modify the gut microbiota, increasing the number of bacteria that process them to yield uremic toxins, such as trimethylamine N-Oxide (TMAO), p-cresyl sulfate, indoxyl sulfate and indole-3 acetic acid. Circulating levels of nutrient-derived uremic toxins are associated to increased risk of death and cardiovascular disease and there is evidence that this association may be causal. Future developments may include maneuvers to modify gut processing or absorption of these nutrients or derivatives to improve CKD patient outcomes.

The response of epiphytic bacteria on Vallisneria natans (Lour.) Hara (Hydrocharitaceae) to increasing nutrient loadings.

PubMed

Cai, Xianlei; Yao, Ling; Gao, Guang; Xie, Yinfeng; Zhang, Yingying; Tang, Xiangming

2016-06-01

To investigate the effects of water column nutrient loading on epiphytic bacteria, we determined the abundance and community composition of epiphytic bacteria on the submerged macrophyte Vallisneria natans (Lour.) Hara during the growth season (June-October) under four different nutrient concentrations (nitrogen (N)-phosphorus (P) in mg L(-1) : 0.5-0.05, 1.0-0.1, 5.0-0.5, 10.0-1.0; hereafter NP-1, NP-2, NP-3, NP-4, respectively), using epifluorescence microscopy method and terminal restriction fragment length polymorphism (T-RFLP) analysis, respectively. Relative to low nutrient conditions (NP-1), there was no significant effect on the epiphytic bacterial community, and even a decrease in the number of epiphytic bacteria, which linked to the well growth status of host macrophytes at moderate nutrient conditions (NP-2). However, further nutrient enrichment induced significant increase in the abundance of epiphytic bacteria, and marked changes in the community structures of epiphytic bacteria. Furthermore, at high nutrient conditions, epiphytic bacterial communities varied widely temporally, and were not stable compared with those at the lower nutrient conditions. These results indicated that the effects of nutrient enrichment on epiphytic bacteria were nonlinear and dependent on the nutrient concentrations in the water. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

SIRT4 coordinates the balance between lipid synthesis and catabolism by repressing malonyl CoA decarboxylase

PubMed Central

Laurent, Gaëlle; German, Natalie J.; Saha, Asish K.; de Boer, Vincent C. J.; Davies, Michael; Koves, Timothy R.; Dephoure, Noah; Fischer, Frank; Boanca, Gina; Vaitheesvaran, Bhavapriya; Lovitch, Scott B.; Sharpe, Arlene H.; Kurland, Irwin J.; Steegborn, Clemens; Gygi, Steven P.; Muoio, Deborah M.; Ruderman, Neil B.; Haigis, Marcia C.

2013-01-01

Summary Lipid metabolism is tightly controlled by the nutritional state of the organism. Nutrient-rich conditions increase lipogenesis whereas nutrient deprivation promotes fat oxidation. In this study, we identify the mitochondrial sirtuin, SIRT4, as a novel regulator of lipid homeostasis. SIRT4 is active in nutrient-replete conditions to repress fatty acid oxidation while promoting lipid anabolism. SIRT4 deacetylates and inhibits malonyl CoA decarboxylase (MCD), an enzyme that produces acetyl CoA from malonyl CoA. Malonyl CoA provides the carbon skeleton for lipogenesis and also inhibits fat oxidation. Mice lacking SIRT4 display elevated MCD activity and decreased malonyl CoA in skeletal muscle and white adipose tissue. Consequently, SIRT4 KO mice display deregulated lipid metabolism leading to increased exercise tolerance and protection against diet-induced obesity. In sum, this work elucidates SIRT4 as an important regulator of lipid homeostasis, identifies MCD as a novel SIRT4 target, and deepens our understanding of the malonyl CoA regulatory axis. PMID:23746352

SIRT4 coordinates the balance between lipid synthesis and catabolism by repressing malonyl CoA decarboxylase.

PubMed

Laurent, Gaëlle; German, Natalie J; Saha, Asish K; de Boer, Vincent C J; Davies, Michael; Koves, Timothy R; Dephoure, Noah; Fischer, Frank; Boanca, Gina; Vaitheesvaran, Bhavapriya; Lovitch, Scott B; Sharpe, Arlene H; Kurland, Irwin J; Steegborn, Clemens; Gygi, Steven P; Muoio, Deborah M; Ruderman, Neil B; Haigis, Marcia C

2013-06-06

Lipid metabolism is tightly controlled by the nutritional state of the organism. Nutrient-rich conditions increase lipogenesis, whereas nutrient deprivation promotes fat oxidation. In this study, we identify the mitochondrial sirtuin, SIRT4, as a regulator of lipid homeostasis. SIRT4 is active in nutrient-replete conditions to repress fatty acid oxidation while promoting lipid anabolism. SIRT4 deacetylates and inhibits malonyl CoA decarboxylase (MCD), an enzyme that produces acetyl CoA from malonyl CoA. Malonyl CoA provides the carbon skeleton for lipogenesis and also inhibits fat oxidation. Mice lacking SIRT4 display elevated MCD activity and decreased malonyl CoA in skeletal muscle and white adipose tissue. Consequently, SIRT4 KO mice display deregulated lipid metabolism, leading to increased exercise tolerance and protection against diet-induced obesity. In sum, this work elucidates SIRT4 as an important regulator of lipid homeostasis, identifies MCD as a SIRT4 target, and deepens our understanding of the malonyl CoA regulatory axis. Copyright © 2013 Elsevier Inc. All rights reserved.

Macroalgal-sediment nutrient interactions and their importance to macroalgal nutrition in a eutrophic estuary

NASA Astrophysics Data System (ADS)

Lavery, Paul S.; McComb, A. J.

1991-03-01

The potential for algal banks to influence water quality and sediment nutrient flux was examined through laboratory experiments and in situ monitoring of algal banks. Loose macroalgal banks displayed seasonal changes in tissue nutrient concentrations suggesting a strong dependence on water column nutrients. These banks fail to generate conditions suitable to sediment nutrient release. Dense banks generated low oxygen conditions in the inter-algal water (0-1 mg l -1), corresponding to zones of high, and relatively stable, phosphate and ammonium concentrations (up to 96 μg l -1 PO 4P and 166 μg l -1 NH 4N). Laboratory experiments confirmed that macroalgal banks can generate reducing conditions at the sediment surface, regardless of the aeration regime, through the decomposition of macroalgal tissue. Platinum electrode potentials as low as -200 mV were recorded in the inter-algal water. In such banks, redox-dependent sediment nutrient release and anaerobic accumulation of nitrogen accounted for inter-algal nutrient concentrations of over 60 μg l -1 phosphate and 800 μg l -1 ammonium. The generation of reducing conditions in inter-algal water required 7 days of still conditions and so this mechanism of nutrient generation is unlikely to be important in winter, when strong winds frequently shift the algal banks. It is suggested that in summer this mechanism may provide a source of nutrients to dense algal banks, supplementing reserves stored in winter.

Dietary potassium diformate did not affect growth and survival but did reduce nutrient digestibility of Pacific white shrimp cultured under clean water conditions

USDA-ARS?s Scientific Manuscript database

This study investigated the effect of a dietary supplement potassium diformate (PDF) on growth performance, survival and nutrient digestibility of Pacific white shrimp cultured under clean water conditions. We found that weight gain was not significantly (P>0.05) affected by the different levels of ...

In vitro immune functions in thiamine-replete and -depleted lake trout (Salvelinus namaycush).

PubMed

Ottinger, Christopher A; Honeyfield, Dale C; Densmore, Christine L; Iwanowicz, Luke R

2014-05-01

In this study we examined the impacts of in vivo thiamine deficiency on lake trout leukocyte function measured in vitro. When compared outside the context of individual-specific thiamine concentrations no significant differences were observed in leukocyte bactericidal activity or in concanavalin A (Con A), and phytohemagglutinin-P (PHA-P) stimulated leukocyte proliferation. Placing immune functions into context with the ratio of in vivo liver thiamine monophosphate (TMP--biologically inactive form) to thiamine pyrophosphate (TPP--biologically active form) proved to be the best indicator of thiamine depletion impacts as determined using regression modeling. These observed relationships indicated differential effects on the immune measures with bactericidal activity exhibiting an inverse relationship with TMP to TPP ratios, Con A stimulated mitogenesis exhibiting a positive relationship with TMP to TPP ratios and PHA-P stimulated mitogenesis exhibiting no significant relationships. In addition, these relationships showed considerable complexity which included the consistent observation of a thiamine-replete subgroup with characteristics similar to those seen in the leukocytes from thiamine-depleted fish. When considered together, our observations indicate that lake trout leukocytes experience cell-type specific impacts as well as an altered physiologic environment when confronted with a thiamine-limited state. Published by Elsevier Ltd.

Nutrient uptake of peanut genotypes under different water regimes

USDA-ARS?s Scientific Manuscript database

Drought is a serious environmental stress limiting growth and productivity in peanut and other crops. Nutrient uptake of peanut is reduced under drought conditions, which reduces yield. The objectives of this study were to investigate nutrient uptake of peanut genotypes in response to drought and ...

Effect of supranutritional organic selenium supplementation on postpartum blood micronutrients, antioxidants, metabolites, and inflammation biomarkers in selenium-replete dairy cows.

PubMed

Hall, Jean A; Bobe, Gerd; Vorachek, William R; Kasper, Katherine; Traber, Maret G; Mosher, Wayne D; Pirelli, Gene J; Gamroth, Mike

2014-12-01

Dairy cows have increased nutritional requirements for antioxidants postpartum. Supranutritional organic Se supplementation may be beneficial because selenoproteins are involved in regulating oxidative stress and inflammation. Our objective was to determine whether feeding Se-yeast above requirements to Se-replete dairy cows during late gestation affects blood micronutrients, antioxidants, metabolites, and inflammation biomarkers postpartum. During the last 8-weeks before calving, dairy cows at a commercial farm were fed either 0 (control) or 105 mg Se-yeast once weekly (supranutritional Se-yeast), in addition to Na selenite at 0.3 mg Se/kg dry matter in their rations. Concentrations of whole-blood (WB) Se and serum Se, erythrocyte glutathione (GSH), and serum albumin, cholesterol, α-tocopherol, haptoglobin, serum amyloid A (SAA), calcium, magnesium, phosphorus, non-esterified fatty acids, and β-hydroxybutyrate were measured directly after calving, at 48 h, and 14 days of lactation in 10 cows of each group. Supranutritional Se-yeast supplementation affected indicators of antioxidant status and inflammation. Cows fed a supranutritional Se-yeast supplement during the last 8-weeks of gestation had higher Se concentrations in WB (overall 52 % higher) and serum (overall 36 % higher) at all-time points, had higher SAA concentrations at 48 h (98 % higher), had higher erythrocyte GSH (38 % higher) and serum albumin concentrations (6.6 % higher) at 14 days, and had lower serum cholesterol concentrations and higher α-tocopherol/cholesterol ratios at calving and at 48 h compared with control cows. In conclusion, feeding Se-replete cows during late gestation a supranutritional Se-yeast supplement improves antioxidant status and immune responses after calving without negatively impacting other micronutrients and energy status.

Limnology of Blue Mesa, Morrow Point, and Crystal Reservoirs, Curecanti National Recreation area, during 1999, and a 25-year retrospective of nutrient conditions in Blue Mesa Reservoir, Colorado

USGS Publications Warehouse

Bauch, Nancy J.; Malick, Matt

2003-01-01

The U.S. Geological Survey and the National Park Service conducted a water-quality investigation in Curecanti National Recreation Area in Colorado from April through December 1999. Current (as of 1999) limnological characteristics, including nutrients, phytoplankton, chlorophyll-a, trophic status, and the water quality of stream inflows and reservoir outflows, of Blue Mesa, Morrow Point, and Crystal Reservoirs were assessed, and a 25-year retrospective of nutrient conditions in Blue Mesa Reservoir was conducted. The three reservoirs are in a series on the Gunnison River, with an upstream to downstream order of Blue Mesa, Morrow Point, and Crystal Reservoirs. Physical properties and water-quality samples were collected four times during 1999 from reservoir, inflow, and outflow sites in and around the recreation area. Samples were analyzed for nutrients, phytoplankton and chlorophyll-a (reservoir sites only), and suspended sediment (stream inflows only). Nutrient concentrations in the reservoirs were low; median total nitrogen and phosphorus concentrations were less than 0.4 and 0.06 milligram per liter, respectively. During water-column stratification, samples collected at depth had higher nutrient concentrations than photic-zone samples. Phytoplankton community and density were affected by water temperature, nutrients, and water residence time. Diatoms were the dominant phytoplankton throughout the year in Morrow Point and Crystal Reservoirs and during spring and early winter in Blue Mesa Reservoir. Blue-green algae were dominant in Blue Mesa Reservoir during summer and fall. Phytoplankton density was highest in Blue Mesa Reservoir and lowest in Crystal Reservoir. Longer residence times and warmer temperatures in Blue Mesa Reservoir were favorable for phytoplankton growth and development. Shorter residence times and cooler temperatures in the downstream reservoirs probably limited phytoplankton growth and development. Median chlorophyll-a concentrations were higher

Nutrient control of eukaryote cell growth: a systems biology study in yeast.

PubMed

Gutteridge, Alex; Pir, Pinar; Castrillo, Juan I; Charles, Philip D; Lilley, Kathryn S; Oliver, Stephen G

2010-05-24

To elucidate the biological processes affected by changes in growth rate and nutrient availability, we have performed a comprehensive analysis of the transcriptome, proteome and metabolome responses of chemostat cultures of the yeast, Saccharomyces cerevisiae, growing at a range of growth rates and in four different nutrient-limiting conditions. We find significant changes in expression for many genes in each of the four nutrient-limited conditions tested. We also observe several processes that respond differently to changes in growth rate and are specific to each nutrient-limiting condition. These include carbohydrate storage, mitochondrial function, ribosome synthesis, and phosphate transport. Integrating transcriptome data with proteome measurements allows us to identify previously unrecognized examples of post-transcriptional regulation in response to both nutrient and growth-rate signals. Our results emphasize the unique properties of carbon metabolism and the carbon substrate, the limitation of which induces significant changes in gene regulation at the transcriptional and post-transcriptional level, as well as altering how many genes respond to growth rate. By comparison, the responses to growth limitation by other nutrients involve a smaller set of genes that participate in specific pathways. See associated commentary http://www.biomedcentral.com/1741-7007/8/62.

Competition between autotrophic and heterotrophic microbial plankton for inorganic nutrients induced by variability in estuarine biophysicochemical conditions

NASA Astrophysics Data System (ADS)

Williams, A.; Quigg, A.

2016-02-01

Competition for inorganic nutrients between autotrophic and heterotrophic fractions of microbial plankton (0.2-20μm) was investigated at two stations in a sub-tropical estuary, Galveston Bay, Texas. Competition potential between these groups is enhanced because individuals are similar in size, reducing variability among their nutrient uptake efficiencies. Further, in estuaries, allochthonous supplements to autochthonous carbon may satisfy heterotrophic requirements, allowing alternative factors to limit abundance. The relative abundance of autotrophs and heterotrophs stained with SYBR Green I and enumerated on a Beckman Coulter Gallios flow cytometer were evaluated monthly during a year-long study. Shifts in the relative in situ abundance were significantly related to temperature, dissolved inorganic nitrogen (DIN), phosphorous (Pi), and total organic carbon (TOC) concentrations revealing opposing gradients of limitation by different abiotic factors. In corresponding in vitro nutrient enrichment bioassays the relative contribution of autotrophic or heterotrophic microbial plankton to significant enrichment responses varied. Only during macro- (>20μm) phytoplankton blooms do autotrophic microbial plankton respond to nutrient enrichment. Contrastingly, the heterotrophic microbial plankton responded to nutrient enrichment primarily when temperature limitation was alleviated. Therefore, the potential for autotrophic and heterotrophic microbial plankton competition for limiting nutrients is highest when autotrophic microbial plankton are also competing with larger phytoplankton during bloom events. Based on this evidence, we hypothesize that the autotrophic microbial fraction has a competitive advantage over the heterotrophs for inorganic nutrients in Galveston Bay. The observed microbial competition during estuarine phytoplankton blooms may have important consequences on biogeochemical processes including carbon and nutrient cycling.

Nutrient removal and starch production through cultivation of Wolffia arrhiza.

PubMed

Fujita, M; Mori, K; Kodera, T

1999-01-01

Wolffia arrhiza, a small weed found mostly in tropical and subtropical water environments, exhibits a high growth rate and consequently absorbs large amounts of nitrogen and phosphorus. Its vegetative frond contains 40% protein on a dry weight basis and its turion, which is the dormant form, has a similar starch content. The applicability of this weed to nutrient removal from secondary-treated waste water combined with starch resource production was evaluated. The nitrogen and phosphorus removal capabilities of the vegetative frond and the optimal conditions for inducing of the formation of turions from harvested biomass of vegetative fronds for the production of starch were investigated using artificial nutrient solutions. The vegetative frond showed high contents of nitrogen (6-7% of the total dry weight) and phosphorus (1-2% of the total dry weight). The nutrient removal rates of the vegetative frond were estimated to be 126 mg-N/m(2)/d and 38 mg-P/m(2)/d under a continuous flow condition. For turion formation from the vegetative fronds, a low nutrient concentration and a high plant density were most effective. Under the optimum conditions, the starch production rate was estimated to be 6 g-starch/m(2) (nutrient removal tank)/d.

A new insight into root responses to external cues: Paradigm shift in nutrient sensing

PubMed Central

Bhardwaj, Deepak; Medici, Anna; Gojon, Alain; Lacombe, Benoît; Tuteja, Narendra

2015-01-01

Higher plants are sessile and their growth relies on nutrients present in the soil. The acquisition of nutrients is challenging for plants. Phosphate and nitrate sensing and signaling cascades play significant role during adverse conditions of nutrient unavailability. Therefore, it is important to dissect the mechanism by which plant roots acquire nutrients from the soil. Root system architecture (RSA) exhibits extensive developmental flexibility and changes during nutrient stress conditions. Growth of root system in response to external concentration of nutrients is a joint operation of sensor or receptor proteins along with several other cytoplasmic accessory proteins. After nutrient sensing, sensor proteins start the cellular relay involving transcription factors, kinases, ubiquitin ligases and miRNA. The complexity of nutrient sensing is still nebulous and many new players need to be better studied. This review presents a survey of recent paradigm shift in the advancements in nutrient sensing in relation to plant roots. PMID:26146897

Successional dynamics drive tropical forest nutrient limitation

NASA Astrophysics Data System (ADS)

Chou, C.; Hedin, L. O. O.

2017-12-01

It is increasingly recognized that nutrients such as N and P may significantly constrain the land carbon sink. However, we currently lack a complete understanding of these nutrient cycles in forest ecosystems and how to incorporate them into Earth System Models. We have developed a framework of dynamic forest nutrient limitation, focusing on the role of secondary forest succession and canopy gap disturbances as bottlenecks of high plant nutrient demand and limitation. We used succession biomass data to parameterize a simple ecosystem model and examined the dynamics of nutrient limitation throughout tropical secondary forest succession. Due to the patterns of biomass recovery in secondary tropical forests, we found high nutrient demand from rapid biomass accumulation in the earliest years of succession. Depending on previous land use scenarios, soil nutrient availability may also be low in this time period. Coupled together, this is evidence that there may be high biomass nutrient limitation early in succession, which is partially met by abundant symbiotic nitrogen fixation from certain tree species. We predict a switch from nitrogen limitation in early succession to one of three conditions: (i) phosphorus only, (ii) phosphorus plus nitrogen, or (iii) phosphorus, nitrogen, plus light co-limitation. We will discuss the mechanisms that govern the exact trajectory of limitation as forests build biomass. In addition, we used our model to explore scenarios of tropical secondary forest impermanence and the impacts of these dynamics on ecosystem nutrient limitation. We found that secondary forest impermanence exacerbates nutrient limitation and the need for nitrogen fixation early in succession. Together, these results indicate that biomass recovery dynamics early in succession as well as their connection to nutrient demand and limitation are fundamental for understanding and modeling nutrient limitation of the tropical forest carbon sink.

Probiotics for Plants? Growth Promotion by the Entomopathogenic Fungus Beauveria bassiana Depends on Nutrient Availability.

PubMed

Tall, Susanna; Meyling, Nicolai V

2018-03-28

Cultivation of crops requires nutrient supplements which are costly and impact the environment. Furthermore, global demands for increased crop production call for sustainable solutions to increase yield and utilize resources such as nutrients more effectively. Some entomopathogenic fungi are able to promote plant growth, but studies over such effects have been conducted under optimal conditions where nutrients are abundantly available. We studied the effects of Beauveria bassiana (strain GHA) seed treatment on the growth of maize (Zea mays) at high and low nutrient conditions during 6 weeks in greenhouse. As expected, B. bassiana seed treatment increased plant growth, but only at high nutrient conditions. In contrast, the seed treatment did not benefit plant growth at low nutrient conditions where the fungus potentially constituted a sink and tended to reduce plant growth. The occurrence of endophytic B. bassiana in experimental plant tissues was evaluated by PCR after 6 weeks, but B. bassiana was not documented in any of the above-ground plant tissues indicating that the fungus-plant interaction was independent of endophytic establishment. Our results suggest that B. bassiana seed treatment could be used as a growth promoter of maize when nutrients are abundantly available, while the fungus does not provide any growth benefits when nutrients are scarce.

Growth of Coccolithophores Controlled by Internal Nutrient Stores in Light- and Nutrient-Limited Batch Reactors: Relevance for the BIOSOPE Deep Ecological Niche of Coccolithophores.

NASA Astrophysics Data System (ADS)

Laura, P.; Probert, I.; Langer, G.; Aloisi, G.

2016-02-01

Coccolithophores are unicellular, calcifying marine algae that play a fundamental role in the oceanic carbon cycle. Recent research has focused on investigating the effect of ocean acidification on cellular calcification. However, the success of this important phytoplankton group in the future ocean will depend on how cellular growth reacts to changes in a combination of environmental variables. We carried out batch culture experiments in conditions of light- and nutrient- (nitrate and phosphate) limitation that reproduce the in situ conditions of a deep ecological niche of coccolithophores in the South Pacific Gyre (BIOSOPE cruise, 2004). We modelled nutrient acquisition and cellular growth in our batch experiments using a Droop internal-stores model. We show that nutrient acquisition and growth are decoupled in coccolithophores; this ability may be key in making life possible in oligotrophic conditions such as the deep BIOSOPE biological niche. Combining the results of our culture experiments with those of Langer et al. (2013), we used the model to obtain estimates of fundamental physiological parameters such as the Monod constant for nutrient uptake, the maximum growth rate and the minimum cellular nutrient quota. These parameters are characteristic of different phytoplankton groups and are needed to simulate phytoplankton growth in biogeochemical models. Our results suggest that growth of coccolithophores in the BIOSOPE deep ecological niche is light-limited rather than nutrient-limited. Our work also shows that simple batch experiments and straightforward numerical modelling are capable of providing estimates of physiological parameters usually obtained in more costly and complicated chemostat experiments.

T-cell replete haploidentical donor transplantation using post-transplant CY: an emerging standard-of-care option for patients who lack an HLA-identical sibling donor.

PubMed

Bashey, A; Solomon, S R

2014-08-01

Availability of an HLA-identical sibling (MRD) or suitably matched unrelated donor (MUD) has historically been a limiting factor in the application of allogeneic hematopoietic transplantation. Although almost all patients have an HLA-haploidentical family donor, prior attempts at transplantation from such donors using T-cell replete grafts and conventional immunosuppression were associated with unacceptable rates of GVHD, and when stringent ex vivo T-cell depletion was used to control GVHD, rates of graft rejection and post-transplant infections were prohibitive. The recent approach to HLA-haploidentical donor transplantation developed in Baltimore that uses T-cell replete grafts and post-transplant CY (Haplo-post-HCT-CY) to control post-transplant allo-reactivity appears to have overcome many of the obstacles historically associated with haploidentical donor transplantation. In particular, TRM rates of <10% are usual and rapid reconstitution of immunity leads to a low rate of post-transplant infections and no post-tranplant lymphoproliferative disorders (PTLD), consistent with the hypothesis that post-transplant CY selectively depletes proliferating alloreactive T cells responsible for GVHD and graft rejection while preserving resting memory T cells essential for post-transplant immunologic recovery. In parallel trials using similar non-myeloablative conditioning regimens, Haplo-post-HCT-CY produced similar overall survival to double umbilical cord blood transplantation(DUCBT) in adult patients (62% vs 54%), with low rates of TRM (7% vs 24%), severe acute GVHD (0% vs 21%) and chronic GVHD (13% vs 25%). Furthermore, recent non-randomized comparisons adjusted for risk factors show that Haplo-post-HCT-CY achieve at least equivalent outcomes to conventional MRD and MUD transplants. Although most experience has been obtained using BM, emerging data suggest that a G-CSF mobilized PBSC graft can also safely be used for Haplo-post-HCT-CY. Haplo-post-HCT-CY also avoids the

BIO-OPTICAL CHARACTERIZATION OF THE DINOFLAGELLATE GYMNODINIUM BREVE AND THE DIATOM THALASSIOSIRA WEISSFLOGII IN OUTDOOR TANKS

EPA Science Inventory

The bio-optical signatures of harmful algal blooms can be used to define ocean color satellite algorithms. We characterized the bio-optical properties of nutrient-replete cultures of the red tide dinoflagellate Gymnodinium breve and the diatom Thalassiosira weissflogii. We cultur...

Climate modifies response of non-native and native species richness to nutrient enrichment.

PubMed

Flores-Moreno, Habacuc; Reich, Peter B; Lind, Eric M; Sullivan, Lauren L; Seabloom, Eric W; Yahdjian, Laura; MacDougall, Andrew S; Reichmann, Lara G; Alberti, Juan; Báez, Selene; Bakker, Jonathan D; Cadotte, Marc W; Caldeira, Maria C; Chaneton, Enrique J; D'Antonio, Carla M; Fay, Philip A; Firn, Jennifer; Hagenah, Nicole; Harpole, W Stanley; Iribarne, Oscar; Kirkman, Kevin P; Knops, Johannes M H; La Pierre, Kimberly J; Laungani, Ramesh; Leakey, Andrew D B; McCulley, Rebecca L; Moore, Joslin L; Pascual, Jesus; Borer, Elizabeth T

2016-05-19

Ecosystem eutrophication often increases domination by non-natives and causes displacement of native taxa. However, variation in environmental conditions may affect the outcome of interactions between native and non-native taxa in environments where nutrient supply is elevated. We examined the interactive effects of eutrophication, climate variability and climate average conditions on the success of native and non-native plant species using experimental nutrient manipulations replicated at 32 grassland sites on four continents. We hypothesized that effects of nutrient addition would be greatest where climate was stable and benign, owing to reduced niche partitioning. We found that the abundance of non-native species increased with nutrient addition independent of climate; however, nutrient addition increased non-native species richness and decreased native species richness, with these effects dampened in warmer or wetter sites. Eutrophication also altered the time scale in which grassland invasion responded to climate, decreasing the importance of long-term climate and increasing that of annual climate. Thus, climatic conditions mediate the responses of native and non-native flora to nutrient enrichment. Our results suggest that the negative effect of nutrient addition on native abundance is decoupled from its effect on richness, and reduces the time scale of the links between climate and compositional change. © 2016 The Author(s).

Climate modifies response of non-native and native species richness to nutrient enrichment

PubMed Central

Flores-Moreno, Habacuc; Reich, Peter B.; Lind, Eric M.; Sullivan, Lauren L.; Seabloom, Eric W.; Yahdjian, Laura; MacDougall, Andrew S.; Reichmann, Lara G.; Alberti, Juan; Báez, Selene; Bakker, Jonathan D.; Cadotte, Marc W.; Caldeira, Maria C.; Chaneton, Enrique J.; D'Antonio, Carla M.; Fay, Philip A.; Firn, Jennifer; Hagenah, Nicole; Harpole, W. Stanley; Iribarne, Oscar; Kirkman, Kevin P.; Knops, Johannes M. H.; La Pierre, Kimberly J.; Laungani, Ramesh; Leakey, Andrew D. B.; McCulley, Rebecca L.; Moore, Joslin L.; Pascual, Jesus; Borer, Elizabeth T.

2016-01-01

Ecosystem eutrophication often increases domination by non-natives and causes displacement of native taxa. However, variation in environmental conditions may affect the outcome of interactions between native and non-native taxa in environments where nutrient supply is elevated. We examined the interactive effects of eutrophication, climate variability and climate average conditions on the success of native and non-native plant species using experimental nutrient manipulations replicated at 32 grassland sites on four continents. We hypothesized that effects of nutrient addition would be greatest where climate was stable and benign, owing to reduced niche partitioning. We found that the abundance of non-native species increased with nutrient addition independent of climate; however, nutrient addition increased non-native species richness and decreased native species richness, with these effects dampened in warmer or wetter sites. Eutrophication also altered the time scale in which grassland invasion responded to climate, decreasing the importance of long-term climate and increasing that of annual climate. Thus, climatic conditions mediate the responses of native and non-native flora to nutrient enrichment. Our results suggest that the negative effect of nutrient addition on native abundance is decoupled from its effect on richness, and reduces the time scale of the links between climate and compositional change. PMID:27114575

Plant litter decomposition and nutrient release in peatlands

NASA Astrophysics Data System (ADS)

Bragazza, Luca; Buttler, Alexandre; Siegenthaler, Andy; Mitchell, Edward A. D.

Decomposition of plant litter is a crucial process in controlling the carbon balance of peatlands. Indeed, as long as the rate of litter decomposition remains lower than the rate of above- and belowground litter production, a net accumulation of peat and, thus, carbon will take place. In addition, decomposition controls the release of important nutrients such as nitrogen, phosphorus, and potassium, the availability of which affects the structure and the functioning of plant communities. This chapter describes the role of the main drivers in affecting mass loss and nutrient release from recently deposited plant litter. In particular, the rate of mass loss of Sphagnum litter and vascular plant litter is reviewed in relation to regional climatic conditions, aerobic/anaerobic conditions, and litter chemistry. The rate of nutrient release is discussed in relation to the rate of mass loss and associated litter chemistry by means of a specific case study.

Insight into litter decomposition driven by nutrient demands of symbiosis system through the hypha bridge of arbuscular mycorrhizal fungi.

PubMed

Kong, Xiangshi; Jia, Yanyan; Song, Fuqiang; Tian, Kai; Lin, Hong; Bei, Zhanlin; Jia, Xiuqin; Yao, Bei; Guo, Peng; Tian, Xingjun

2018-02-01

Arbuscular mycorrhizal fungi (AMF) play an important role in litter decomposition. This study investigated how soil nutrient level affected the process. Results showed that AMF colonization had no significant effect on litter decomposition under normal soil nutrient conditions. However, litter decomposition was accelerated significantly under lower nutrient conditions. Soil microbial biomass in decomposition system was significantly increased. Especially, in moderate lower nutrient treatment (condition of half-normal soil nutrient), litters exhibited the highest decomposition rate, AMF hypha revealed the greatest density, and enzymes (especially nitrate reductase) showed the highest activities as well. Meanwhile, the immobilization of nitrogen (N) in the decomposing litter remarkably decreased. Our results suggested that the roles AMF played in ecosystem were largely affected by soil nutrient levels. At normal soil nutrient level, AMF exhibited limited effects in promoting decomposition. When soil nutrient level decreased, the promoting effect of AMF on litter decomposition began to appear, especially on N mobilization. However, under extremely low nutrient conditions, AMF showed less influence on decomposition and may even compete with decomposer microorganisms for nutrients.

Plasticity of the Arabidopsis Root System under Nutrient Deficiencies1[C][W][OPEN

PubMed Central

Gruber, Benjamin D.; Giehl, Ricardo F.H.; Friedel, Swetlana; von Wirén, Nicolaus

2013-01-01

Plant roots show a particularly high variation in their morphological response to different nutrient deficiencies. Although such changes often determine the nutrient efficiency or stress tolerance of plants, it is surprising that a comprehensive and comparative analysis of root morphological responses to different nutrient deficiencies has not yet been conducted. Since one reason for this is an inherent difficulty in obtaining nutrient-deficient conditions in agar culture, we first identified conditions appropriate for producing nutrient-deficient plants on agar plates. Based on a careful selection of agar specifically for each nutrient being considered, we grew Arabidopsis (Arabidopsis thaliana) plants at four levels of deficiency for 12 nutrients and quantified seven root traits. In combination with measurements of biomass and elemental concentrations, we observed that the nutritional status and type of nutrient determined the extent and type of changes in root system architecture (RSA). The independent regulation of individual root traits further pointed to a differential sensitivity of root tissues to nutrient limitations. To capture the variation in RSA under different nutrient supplies, we used principal component analysis and developed a root plasticity chart representing the overall modulations in RSA under a given treatment. This systematic comparison of RSA responses to nutrient deficiencies provides a comprehensive view of the overall changes in root plasticity induced by the deficiency of single nutrients and provides a solid basis for the identification of nutrient-sensitive steps in the root developmental program. PMID:23852440

Autophagy sustains the survival of human pancreatic cancer PANC-1 cells under extreme nutrient deprivation conditions.

PubMed

Kim, Sang Eun; Park, Hye-Jin; Jeong, Hye Kyoung; Kim, Mi-Jung; Kim, Minyeong; Bae, Ok-Nam; Baek, Seung-Hoon

2015-07-31

Pancreatic ductal adenocarcinomas are an extremely aggressive and devastating type of cancer with high mortality. Given the dense stroma and poor vascularization, accessibility to nutrients is limited in the tumor microenvironment. Here, we aimed to elucidate the role of autophagy in promoting the survival of human pancreatic cancer PANC-1 cells exposed to nutrient-deprived media (NDM) lacking glucose, amino acids, and serum. NDM inhibited Akt activity and phosphorylation of p70 S6K, and induced AMPK activation and mitochondrial depolarization. NDM also time-dependently increased LC3-II accumulation, number of GFP-LC3 puncta, and colocalization between GFP-LC3 and lysosomes. These results suggested that autophagy was progressively activated through Akt- and AMPK-mTOR pathway in nutrient-deficient PANC-1 cells. Autophagy inhibitors (chloroquine and wortmannin) or silencing of Atg5 augmented PANC-1 cell death in NDM. In cells exposed to NDM, chloroquine and wortmannin induced apoptosis and Z-VAD-fmk inhibited cytotoxicity of these inhibitors. These data demonstrate that autophagy is anti-apoptotic and sustains the survival of PANC-1 cells following extreme nutrient deprivation. Autophagy modulation may be a viable therapeutic option for cancer cells located in the core of solid tumors with a nutrient-deficient microenvironment. Copyright © 2015 Elsevier Inc. All rights reserved.

Variable primary producer responses to nutrient and ...

EPA Pesticide Factsheets

Mesocosm experiments have been used to evaluate the impacts of nutrient loading on estuarine plant communities in order to develop nutrient response relationships. Mesocosm eutrophication studies tend to focus on long residence time systems. In the Pacific Northwest, many estuaries have high nutrient loads, short water residence times, seasonal macroalgal blooms, while intertidal seagrass meadows persist under what appear to be largely naturally-derived eutrophic conditions. Using experimental mesocosms, we examined how primary producer communities in rapidly flushed systems respond to a range of temperature (10 and 20 °C) and nutrient loads (ambient, 1.5, 3 and 6 x ambient). Thermal and nutrient loading regimes were maintained for three sets of 3 week-duration experiments during the summer of 2013. Statistical analysis was performed using an information criterion approach to evaluate the best fit model. Green macroalgal (GMA) growth and tissue N increased in response to nutrient loading. Irrespective of nutrient load, GMA at 10 °C remained intercalated among seagrass shoots, but at 20 °C formed floating mats that overtopped seagrass. Outgassing of O2 in combination with photosynthetic O2 production likely induced floating mat formation. No phytoplankton blooms were observed. Zostera japonica leaf biomass and C:N responded to temperature while other metrics exhibited no statistically significant difference. Z. marina growth, wasting disease, and morphological

NPKS uptake, sensing, and signaling and miRNAs in plant nutrient stress.

PubMed

Nath, Manoj; Tuteja, Narendra

2016-05-01

Sessile nature of higher plants consequently makes it highly adaptable for nutrient absorption and acquisition from soil. Plants require 17 essential elements for their growth and development which include 14 minerals (macronutrients: N, P, K, Mg, Ca, S; micronutrients: Cl, Fe, B, Mn, Zn, Cu, Ni, Mo) and 3 non-mineral (C, H, O) elements. The roots of higher plants must acquire these macronutrients and micronutrients from rhizosphere and further allocate to other plant parts for completing their life cycle. Plants evolved an intricate series of signaling and sensing cascades to maintain nutrient homeostasis and to cope with nutrient stress/availability. The specific receptors for nutrients in root, root system architecture, and internal signaling pathways help to develop plasticity in response to the nutrient starvation. Nitrogen (N), phosphorus (P), potassium (K), and sulfur (S) are essential for various metabolic processes, and their deficiency negatively effects the plant growth and yield. Genes coding for transporters and receptors for nutrients as well as some small non-coding RNAs have been implicated in nutrient uptake and signaling. This review summarizes the N, P, K, and S uptake, sensing and signaling events in nutrient stress condition especially in model plant Arabidopsis thaliana and involvement of microRNAs in nutrient deficiency. This article also provides a framework of uptake, sensing, signaling and to highlight the microRNA as an emerging major players in nutrient stress condition. Nutrient-plant-miRNA cross talk may help plant to cope up nutrient stress, and understanding their precise mechanism(s) will be necessary to develop high yielding smart crop with low nutrient input.

Modelling of the Nutrient Medium for Plants Cultivation in Spaceflight

NASA Astrophysics Data System (ADS)

Nechitailo, Galina S.

2016-07-01

MODELLING OF THE NUTRIENT MEDIUM FOR PLANTS CULTIVATION IN SPACEFLIGHT Nechitajlo G.S.*, Rakhmetova A.A.**, Bogoslovskaja O.A.**, Ol'hovskay I.P.**, Glushchenko N.N.** *Emanuel Institute of Biochemical Physics of Russian Academy of Sciences (IBCP RAS) mail: spacemal@mail.ru **V.L. Talrose Institute for Energy Problems of Chemical Physics of Russian Academy of Science (INEPCP RAS) mail: nnglu@ mail.ru The valuable life and fruitful activity of cosmonauts and researchers in conditions of spaceflights and prolonged work at space stations are only possible with creating life area providing fresh air, natural food, comfortable psychological conditions, etc. The solution of that problem under space conditions seems impossible without use of high nano- and biotechnologies for plants growth. A priority should be given not only to choose species of growth plants in space, but also to improve conditions for their growth which includes optimal nourishing components for plants, preparation of nutrient mediums, illumination and temperature. We are deeply convinced that just manipulations with growing conditions for cultivated plants, but not genes changes, is a guarantee of success in the decision of this problem. For improving the method of plants growing on the artificial nutrient medium with balanced content of components, being necessary for growth and development of plants, we added essential metal elements: Fe, Zn, Cu - in an electroneutral state in the form of nanoparticles instead of sulfates or other easily dissolving salts. Nanoparticulated metals are known to have a number of advantages in comparison with salts: metals in an electroneutral form are characterized with the prolonged and multifunctional action, low toxicity per se and appearing to be much below the toxicity of the same metals in the ionic forms, accumulation as a reserve being used in biotic dozes, active distribution in bodies and organs of plants and stimulation of vital processes. A high reactivity

Setting nutrient thresholds to support an ecological assessment based on nutrient enrichment, potential primary production and undesirable disturbance.

PubMed

Devlin, Michelle; Painting, Suzanne; Best, Mike

2007-01-01

The EU Water Framework Directive recognises that ecological status is supported by the prevailing physico-chemical conditions in each water body. This paper describes an approach to providing guidance on setting thresholds for nutrients taking account of the biological response to nutrient enrichment evident in different types of water. Indices of pressure, state and impact are used to achieve a robust nutrient (nitrogen) threshold by considering each individual index relative to a defined standard, scale or threshold. These indices include winter nitrogen concentrations relative to a predetermined reference value; the potential of the waterbody to support phytoplankton growth (estimated as primary production); and detection of an undesirable disturbance (measured as dissolved oxygen). Proposed reference values are based on a combination of historical records, offshore (limited human influence) nutrient concentrations, literature values and modelled data. Statistical confidence is based on a number of attributes, including distance of confidence limits away from a reference threshold and how well the model is populated with real data. This evidence based approach ensures that nutrient thresholds are based on knowledge of real and measurable biological responses in transitional and coastal waters.

[Nutrient content and adequacy of roughage for horse nutrition: an investigation under Swiss conditions].

PubMed

Nater, S; Wanner, M; Wichert, B

2007-03-01

For horses no special tables related to nutrients for Swiss roughage exist. For this reason samples of hay, straw, silage/haylage and green forage were taken from 46 horse keeping farms in 22 cantons. The samples were judged by sense and following the nutrient--and macromineral--content as well as the content of fructans were analysed. Regarding its quality no sample was totally inadequate for horses. The mean contents of crude protein in Swiss hay for horses were clearly lower than in hay for ruminants and in German hay for horses. The mineral contents (calcium, magnesium, phosphorus) showed a wide range. On average they were also lower than the values provided in tables for ruminants. Except for one sample the silages/haylages showed a dry matter content of more than 40 %. No nutrient tables for silage or haylage, which are such high in dry matter contents, were found in the literature. The contents offructans in silage/haylage and green forage also showed a wide range with a maximum of 94 g/kg DM fructan.

NUTRIENT CONTAMINATION AS A RESULT OF POINT SOURCE DISCHARGES: A SURVEY

EPA Science Inventory

Nutrients are common contaminants in Gulf of Mexico estuaries and when present in high concentrations, they can cause excessive algal growths and hypoxic conditions. The magnitude and biological significance of nutrient loading to estuarine waters receiving treated wastewaters is...

Abundance of the iron containing biomolecule, heme b, during the progression of a spring phytoplankton bloom in a mesocosm experiment

PubMed Central

Bellworthy, Jessica; Esposito, Mario; Achterberg, Eric P.

2017-01-01

Concentrations of heme b were determined in a mesocosm experiment situated in Gullmar Fjord off Sweden. The mesocosm experiment lasted for ca. one hundred days and was characterised by the growth of a primary nutrient replete and a secondary nutrient deplete phytoplankton bloom. Heme b varied between 40 ± 10 pmol L-1 in the prebloom period up to a maximum of 700 ± 400 pmol L-1 just prior to the time of the primary chlorophyll a maximum. Thereafter, heme b concentrations decreased again to an average of 120 ± 60 pmol L-1. When normalised to total particulate carbon, heme b was most abundant during the initiation of the nutrient replete spring bloom, when ratios reached 52 ± 24 μmol mol-1; ten times higher than values observed both pre and post the primary bloom. Concentrations of heme b correlated with those of chlorophyll a. Nevertheless, differences were observed in the relative concentrations of the two parameters, with heme b concentrations increasing relative to chlorophyll a during the growth of the primary bloom, decreasing over the period of the secondary bloom and increasing again through the latter period of the experiment. Heme b abundance was therefore influenced by nutrient concentrations and also likely by changing community composition. In half of the mesocosms, pCO2 was elevated and maintained at ca.1000 μatm, however we observed no significant differences between heme b in plus or ambient pCO2 mesocosms, either in absolute terms, or relative to total particulate carbon and chlorophyll a. The results obtained in this study contribute to our understanding of the distribution of this significant component of the biogenic iron pool, and provide an iron replete coastal water end member that aids the interpretation of the distributions of heme b in more iron deplete open ocean waters. PMID:28426768

What's Upstream? GIS's critical role in developing nutrient ...

EPA Pesticide Factsheets

Eutrophication due to excess levels of nitrogen and phosphorus can seriously impair ecological function in estuaries. Protective criteria for nutrients are difficult to establish because the source can vary spatially and seasonally, originate either from the watershed or the ocean, and be natural or anthropogenic. GIS tools and processes can help in developing nutrient criteria by establishing reference conditions representative of natural background nutrient levels. Along the Oregon Coast in the Pacific Northwest, the primary source of nutrients in the wet season (November-April) is generally riverine. We delineated and extracted explicit spatial data from watersheds upstream of riverine water quality monitoring stations for parametric comparison to recorded nutrient levels. The SPARROW model (Wise and Johnson, 2011) was used to estimate relative contributions of nutrient sources at each station. Both raster and vector spatial data were used and include land use / land cover, demography, geology, terrain, precipitation and forest type. The relationships of nutrients to spatial data were then explored as an approach to establishing the reference expectation. The abstract introduces Geographic Information Systems (GIS) tools and processes employed for research conducted under the Safe and Sustainable Water Resources (SSWR) Task 2.3A, entitled “Nutrient Management for Sustainability of Aquatic Ecosystems.” One of the goals of the EPA Office of Water is to

Current understanding on ethylene signaling in plants: the influence of nutrient availability.

PubMed

Iqbal, Noushina; Trivellini, Alice; Masood, Asim; Ferrante, Antonio; Khan, Nafees A

2013-12-01

The plant hormone ethylene is involved in many physiological processes, including plant growth, development and senescence. Ethylene also plays a pivotal role in plant response or adaptation under biotic and abiotic stress conditions. In plants, ethylene production often enhances the tolerance to sub-optimal environmental conditions. This role is particularly important from both ecological and agricultural point of views. Among the abiotic stresses, the role of ethylene in plants under nutrient stress conditions has not been completely investigated. In literature few reports are available on the interaction among ethylene and macro- or micro-nutrients. However, the published works clearly demonstrated that several mineral nutrients largely affect ethylene biosynthesis and perception with a strong influence on plant physiology. The aim of this review is to revisit the old findings and recent advances of knowledge regarding the sub-optimal nutrient conditions on the effect of ethylene biosynthesis and perception in plants. The effect of deficiency or excess of the single macronutrient or micronutrient on the ethylene pathway and plant responses are reviewed and discussed. The synergistic and antagonist effect of the different mineral nutrients on ethylene plant responses is critically analyzed. Moreover, this review highlights the status of information between nutritional stresses and plant response, emphasizing the topics that should be further investigated. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Investment in secreted enzymes during nutrient-limited growth is utility dependent.

PubMed

Cezairliyan, Brent; Ausubel, Frederick M

2017-09-12

Pathogenic bacteria secrete toxins and degradative enzymes that facilitate their growth by liberating nutrients from the environment. To understand bacterial growth under nutrient-limited conditions, we studied resource allocation between cellular and secreted components by the pathogenic bacterium Pseudomonas aeruginosa during growth on a protein substrate that requires extracellular digestion by secreted proteases. We identified a quantitative relationship between the rate of increase of cellular biomass under nutrient-limiting growth conditions and the rate of increase in investment in secreted proteases. Production of secreted proteases is stimulated by secreted signals that convey information about the utility of secreted proteins during nutrient-limited growth. Growth modeling using this relationship recapitulated the observed kinetics of bacterial growth on a protein substrate. The proposed regulatory strategy suggests a rationale for quorum-sensing-dependent stimulation of the production of secreted enzymes whereby investment in secreted enzymes occurs in proportion to the utility they confer. Our model provides a framework that can be applied toward understanding bacterial growth in many environments where growth rate is limited by the availability of nutrients.

A novel P450-initiated biphasic process for sustainable biodegradation of benzo[a]pyrene in soil under nutrient-sufficient conditions by the white rot fungus Phanerochaete chrysosporium

PubMed Central

Bhattacharya, Sukanta S.; Syed, Khajamohiddin; Shann, Jodi; Yadav, Jagjit S.

2013-01-01

High molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) such as benzo[a]pyrene (BaP) are resistant to biodegradation in soil. Conventionally, white rot fungus Phanerochaete chrysosporium has been investigated for HMW-PAH degradation in soil primarily using nutrient-deficient (ligninolytic) conditions, albeit with limited and non-sustainable biodegradation outcomes. In this study, we report development of an alternative novel biphasic process initiated under nutrient-sufficient (non-ligninolytic) culture conditions, by employing an advanced experimental design strategy. During the initial nutrient-sufficient non-ligninolytic phase (16 days), the process showed upregulation (3.6-and 22.3-fold, respectively) of two key PAH-oxidizing P450 monooxygenases pc2 (CYP63A2) and pah4 (CYP5136A3) and formation of typical P450-hydroxylated metabolite. This along with abrogation (84.9%) of BaP degradation activity in response to a P450-specific inhibitor implied key role of these monooxygenases. The subsequent phase triggered on continued incubation (to 25 days) switched the process from non-ligninolytic to ligninolytic resulting in a significantly higher net degradation (91.6% as against 67.4% in the control nutrient-limited set) of BaP with concomitant de novo ligninolytic enzyme expression making it a biphasic process yielding improved sustainable bioremediation of PAH-contaminated soil. To our knowledge this is the first report on development of such biphasic process for bioremediation application of a white rot fungus. PMID:24051002

Nutrient removal by root zone treatment systems: a review.

PubMed

Sonavane, P G; Munavalli, G R; Ranade, S V

2008-07-01

The Root Zone Treatment System (RZTS) has been used widely for nutrient removal in European countries. In spite of having its more adaptability in tropical region like India its use to address nutrient induced issues in the country is very less. The lack of widely accepted data, non consensus of scientists over nutrient removal mechanism and inability to apply performance standards observed in other countries directly might have hampered the acceptance of this technology in India. A few technology assessment programs are being conducted in collaboration with other countries to engineer this technology but nutrient removal aspects are not essentially focused. In this context, there is need to direct lab scale research to identify potential wetland plants, bed media and comparative study of their combination specific performance under similar conditions. The field application of the data will help to understand variability in performance and disparities in the mechanism. The systems would be amended based on these studies to establish combination specific performance standards for typical Indian conditions. Maintenance strategy and optimization of design will help to foster the technology. The development strategy should give due consideration to the contributions of other countries so as to avoid repetition of work which will save time, money and efforts, and help for the real acceptance of RZTS in Indian conditions.

Nutrient vectors and riparian nutrient processing in African semiarid savanna ecosystems

USGS Publications Warehouse

Jacobs, Shayne M.; Bechtold, J.S.; Biggs, Harry C.; Grimm, N. B.; McClain, M.E.; Naiman, R.J.; Perakis, Steven S.; Pinay, G.; Scholes, M.C.

2007-01-01

This review article describes vectors for nitrogen and phosphorus delivery to riparian zones in semiarid African savannas, the processing of nutrients in the riparian zone and the effect of disturbance on these processes. Semiarid savannas exhibit sharp seasonality, complex hillslope hydrology and high spatial heterogeneity, all of which ultimately impact nutrient fluxes between riparian, upland and aquatic environments. Our review shows that strong environmental drivers such as fire and herbivory enhance nitrogen, phosphorus and sediment transport to lower slope positions by shaping vegetative patterns. These vectors differ significantly from other arid and semiarid ecosystems, and from mesic ecosystems where the impact of fire and herbivory are less pronounced and less predictable. Also unique is the presence of sodic soils in certain hillslopes, which substantially alters hydrological flowpaths and may act as a trap where nitrogen is immobilized while sediment and phosphorus transport is enhanced. Nutrients and sediments are also deposited in the riparian zone during seasonal, intermittent floods while, during the dry season, subsurface movement of water from the stream into riparian soils and vegetation further enrich riparian zones with nutrients. As is found in mesic ecosystems, nutrients are immobilized in semiarid riparian corridors through microbial and plant uptake, whereas dissimilatory processes such as denitrification may be important where labile nitrogen and carbon are in adequate supply and physical conditions are suitablea??such as in seeps, wallows created by animals, ephemeral wetlands and stream edges. Interaction between temporal hydrologic connectivity and spatial heterogeneity are disrupted by disturbances such as large floods and extended droughts, which may convert certain riparian patches from sinks to sources for nitrogen and phosphorus. In the face of increasing anthropogenic pressure, the scientific challenges are to provide a basic

Effects of raw material extrusion and steam conditioning on feed pellet quality and nutrient digestibility of growing meat rabbits.

PubMed

Liao, Kuoyao; Cai, Jingyi; Shi, Zhujun; Tian, Gang; Yan, Dong; Chen, Delin

2017-06-01

This study was conducted to investigate the effects of raw material extrusion and steam conditioning on feed pellet quality and nutrient digestibility of growing meat rabbits, in order to determine appropriate rabbit feed processing methods and processing parameters. In Exp. 1, an orthogonal design was adopted. Barrel temperature, material moisture content and feed rate were selected as test factors, and acid detergent fiber (ADF) content was selected as an evaluation index to research the optimum extrusion parameters. In Exp. 2, a two-factor design was adopted. Four kinds of rabbit feeds were processed and raw material extrusion adopted optimum extrusion parameters of Exp. 1. A total of 40 healthy and 42-day-old rabbits with similar weight were used in a randomized design, which consisted of 4 groups and 10 replicates in each group (1 rabbits in each replicate). The adaptation period lasted for 7 d, and the digestion trial lasted for 4 d. The results showed as follows: 1) ADF was significantly affected by barrel temperature ( P  < 0.05); the optimum extrusion parameters were barrel temperature 125 °C, moisture content 16% and feed rate 9 Hz. 2) Raw material extrusion and steam conditioning both significantly decreased powder percentage, pulverization ratio and protein solubility ( P  < 0.05), significantly improved hardness and starch gelatinization degree of rabbit feed ( P  < 0.05). They both had significant interaction effects on the processing quality of rabbit feed ( P  < 0.05). 3) Extrusion significantly improved the apparent digestibility of dry matter and total energy ( P  < 0.05). Extrusion and steam conditioning both significantly improved the apparent digestibility of crude fiber (CF), ADF and NDF ( P  < 0.05), but they had no interaction effects on the apparent digestibility of rabbit feed. Thus, using extrusion and steam conditioning technology at the same time in the weaning rabbits feed processing can improve the pellet quality and

Amino acid repletion does not decrease muscle protein catabolism during hemodialysis.

PubMed

Raj, Dominic S C; Adeniyi, Oladipo; Dominic, Elizabeth A; Boivin, Michel A; McClelland, Sandra; Tzamaloukas, Antonios H; Morgan, Nancy; Gonzales, Lawrence; Wolfe, Robert; Ferrando, Arny

2007-06-01

Intradialytic protein catabolism is attributed to loss of amino acids in the dialysate. We investigated the effect of amino acid infusion during hemodialysis (HD) on muscle protein turnover and amino acid transport kinetics by using stable isotopes of phenylalanine, leucine, and lysine in eight patients with end-stage renal disease (ESRD). Subjects were studied at baseline (pre-HD), 2 h of HD without amino acid infusion (HD-O), and 2 h of HD with amino acid infusion (HD+AA). Amino acid depletion during HD-O augmented the outward transport of amino acids from muscle into the vein. Increased delivery of amino acids to the leg during HD+AA facilitated the transport of amino acids from the artery into the intracellular compartment. Increase in muscle protein breakdown was more than the increase in synthesis during HD-O (46.7 vs. 22.3%, P < 0.001). Net balance (nmol.min(-1).100 ml (-1)) was more negative during HD-O compared with pre-HD (-33.7 +/- 1.5 vs. -6.0 +/- 2.3, P < 0.001). Despite an abundant supply of amino acids, the net balance (-16.9 +/- 1.8) did not switch from net release to net uptake. HD+AA induced a proportional increase in muscle protein synthesis and catabolism. Branched chain amino acid catabolism increased significantly from baseline during HD-O and did not decrease during HD+AA. Protein synthesis efficiency, the fraction of amino acid in the intracellular pool that is utilized for muscle protein synthesis decreased from 42.1% pre-HD to 33.7 and 32.6% during HD-O and HD+AA, respectively (P < 0.01). Thus amino acid repletion during HD increased muscle protein synthesis but did not decrease muscle protein breakdown.

Goat milk consumption modulates liver divalent metal transporter 1 (DMT1) expression and serum hepcidin during Fe repletion in Fe-deficiency anemia.

PubMed

Díaz-Castro, J; Pulido, M; Alférez, M J M; Ochoa, J J; Rivas, E; Hijano, S; López-Aliaga, I

2014-01-01

Iron deficiency is the most prevalent micronutrient deficiency worldwide. In spite of the crucial role of hepatocyte divalent metal transporter 1 (DMT1) and hepcidin in Fe metabolism, to date, no studies have directly tested the role of these proteins in liver Fe metabolism during Fe repletion after induced Fe-deficiency anemia. Therefore, the aim of the current study was to assess the effect of goat or cow milk-based diets on Fe metabolism in one of the main body storage organs, the liver, during the course of Fe repletion with goat or cow milk-based diets in anemic rats. Animals were placed on a preexperimental period of 40 d, a control group receiving a normal-Fe diet and the Fe-deficient group receiving a low-Fe diet (5 mg of Fe/kg of diet). Rats were fed for 30 d with goat or cow milk-based diets with normal Fe content (45 mg of Fe/kg of diet). The hematological parameters, serum hepcidin, hepatosomatic index, liver Fe content, and liver DMT1 expression were determined. During the recovery of the anemia with milk-based diets, the restoration of liver Fe content and hematological parameters, especially with goat milk, increased the red blood cell count, favoring the oxygen supply and weight gain. Moreover, goat milk consumption potentiates liver DMT1 expression, enhancing Fe metabolism and storage. In addition, the increase in serum hepcidin in anemic rats observed in the current study also explains and supports the higher liver Fe content after supplying goat milk, because it blocks the liberation of Fe from hepatocytes, increasing its storage in liver. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Temperature and nutrient effects on periphyton associated bacterial communities in continuous flow-through estuarine mesocosms

EPA Science Inventory

Nutrient pollution is a leading cause of water quality impairments and degraded aquatic ecosystem condition. Reliable and reproducible indicators of ecosystem condition are needed to help manage nutrient pollution. The diatom component of periphyton has been used as a water qua...

Drug-nutrient interactions.

PubMed

Chan, Lingtak-Neander

2013-07-01

Drug-nutrient interactions are defined as physical, chemical, physiologic, or pathophysiologic relationships between a drug and a nutrient. The causes of most clinically significant drug-nutrient interactions are usually multifactorial. Failure to identify and properly manage drug-nutrient interactions can lead to very serious consequences and have a negative impact on patient outcomes. Nevertheless, with thorough review and assessment of the patient's history and treatment regimens and a carefully executed management strategy, adverse events associated with drug-nutrient interactions can be prevented. Based on the physiologic sequence of events after a drug or a nutrient has entered the body and the mechanism of interactions, drug-nutrient interactions can be categorized into 4 main types. Each type of interaction can be managed using similar strategies. The existing data that guide the clinical management of most drug-nutrient interactions are mostly anecdotal experience, uncontrolled observations, and opinions, whereas the science in understanding the mechanism of drug-nutrient interactions remains limited. The challenge for researchers and clinicians is to increase both basic and higher level clinical research in this field to bridge the gap between the science and practice. The research should aim to establish a better understanding of the function, regulation, and substrate specificity of the nutrient-related enzymes and transport proteins present in the gastrointestinal tract, as well as assess how the incidence and management of drug-nutrient interactions can be affected by sex, ethnicity, environmental factors, and genetic polymorphisms. This knowledge can help us develop a true personalized medicine approach in the prevention and management of drug-nutrient interactions.

Assessment of Nutrient Stability in Space Foods

NASA Technical Reports Server (NTRS)

Zwart, S. R.; Perchonok, M.; Braby, L. A.; Kloeris, V. A.; Smith, S. M.

2009-01-01

Maintaining an intact nutrient supply in the food system flown on spacecraft is a critical issue for mission success and crew health and safety. Early polar expeditions and exploration expeditions by sailing vessels have taught us that a deficiency, or excess, of even a single vitamin in the food supply can be catastrophic. Evidence from ground-based research indicates that some vitamins are destroyed and fatty acids are oxidized (and therefore rendered dangerous or useless) by different types of radiation and by conditions of long-term storage. We hypothesize that radiation and long-term storage in the space-flight environment will affect the stability of vitamins, amino acids, and fatty acids in the space food system. The research objectives of our ongoing stability studies are to determine the stability of water- and fat-soluble vitamins, fatty acids, and amino acids in the space food supply before and after space flight on the International Space Station (ISS). Foods were analyzed after 2 weeks (a flight control), 11, 19, and 28 months of flight. Along with the space-flown foods, ground-based controls matched for time, light, and temperature are analyzed. The flight studies complement planned ground-based studies of the effects of radiation on vitamins, amino acids, and fatty acids. Flight studies are needed because a model based on ground-based data cannot predict all of the effects of the space-flight environment. Flight studies provide a more accurate test system to determine the effects on these nutrients of the temperature, and radiation conditions in the space-flight environment. Ground studies are required to evaluate longer missions and higher radiation levels expected outside low-Earth orbit. In addition to providing information about nutrient stability in space, the results of these studies will help NASA determine if a need exists to develop special packaging that can ensure stability of foods and nutrients in space, or if further studies of nutrient

Bulk water phase and biofilm growth in drinking water at low nutrient conditions.

PubMed

Boe-Hansen, Rasmus; Albrechtsen, Hans-Jørgen; Arvin, Erik; Jørgensen, Claus

2002-11-01

In this study, the bacterial growth dynamics of a drinking water distribution system at low nutrient conditions was studied in order to determine bacterial growth rates by a range of methods, and to compare growth rates in the bulk water phase and the biofilm. A model distribution system was used to quantify the effect of retention times at hydraulic conditions similar to those in drinking water distribution networks. Water and pipe wall samples were taken and examined during the experiment. The pipes had been exposed to drinking water at approximately 13 degrees C, for at least 385 days to allow the formation of a mature quasi-stationary biofilm. At retention times of 12 h, total bacterial counts increased equivalent to a net bacterial growth rate of 0.048 day(-1). The bulk water phase bacteria exhibited a higher activity than the biofilm bacteria in terms of culturability, cell-specific ATP content, and cell-specific leucine incorporation rate. Bacteria in the bulk water phase incubated without the presence of biofilm exhibited a bacterial growth rate of 0.30 day(-1). The biofilm was radioactively labelled by the addition of 14C-benzoic acid. Subsequently, a biofilm detachment rate of 0.013 day(-1) was determined by measuring the release of 14C-labelled bacteria of the biofilm. For the quasi-stationary phase biofilm, the detachment rate was equivalent to the net growth rate. The growth rates determined in this study by different independent experimental approaches were comparable and within the range of values reported in the literature.

Nutrient mitigation in a temporary river basin.

PubMed

Tzoraki, Ourania; Nikolaidis, Nikolaos P; Cooper, David; Kassotaki, Elissavet

2014-04-01

We estimate the nutrient budget in a temporary Mediterranean river basin. We use field monitoring and modelling tools to estimate nutrient sources and transfer in both high and low flow conditions. Inverse modelling by the help of PHREEQC model validated the hypothesis of a losing stream during the dry period. Soil and Water Assessment Tool model captured the water quality of the basin. The 'total daily maximum load' approach is used to estimate the nutrient flux status by flow class, indicating that almost 60% of the river network fails to meet nitrogen criteria and 50% phosphate criteria. We recommend that existing well-documented remediation measures such as reforestation of the riparian area or composting of food process biosolids should be implemented to achieve load reduction in close conjunction with social needs.

Respiration, and growth-efficiency of coastal prokaryote communities in continuous cultures under different growth rates and temperatures.

NASA Astrophysics Data System (ADS)

Maske, H.; Cajal-Medrano, R.; Villegas-Mendoza, J.

2016-02-01

Organotrophic prokaryotes in aquatic environments account for about half of community respiration in surface oceans and are key trophic links in the plankton food web connecting dissolved organics and higher trophic levels. The transfer efficiency is partially characterized by the ratio of prokaryote respiration rates (r, day-1) to growth rates (m, day-1) and the resulting growth efficiency (Y). Much literature has been published about the response of these parameters to temperature in monospecific cultures, but little is known about the response of a community of pelagic prokaryotes were the sum of the genotypes and phenotype define the physiological potential. We inoculated 10 turbidostats and 39 chemostats with coastal bacteria and measured CO2 production, carbon biomass and cell abundance, with m ranging from 0.05 to 62 day-1 between 10 and 26oC. Under substrate limited conditions, common in the ocean, r showed no significant trend with temperature and was proportional to m implying constant Y. Under temperature-limited, nutrient replete growth the m of coastal prokaryote communities increased with temperature but r decreased (Q10: 0.4), resulting in an increase of Y with temperature (Q10: 2.5). The carbon demand rate (b, fmol C (cell day)-1) of turbidostat cultures showed a very high Q10 of 8.4. Casting the data in the framework of the metabolic theory of ecology (MTE), the physiological rates normalized to cell carbon showed no significant changes with temperature using either respiration or carbon demand as a proxy for physiological rate. Our results suggest that physiological patterns related to temperature are very different under nutrient limited or replete conditions and under neither condition it followed the pattern expected by MTE.

Nutrient signaling and developmental timing of maturation.

PubMed

Danielsen, E Thomas; Moeller, Morten E; Rewitz, Kim F

2013-01-01

In animals, developmental timing of sexual maturation is tightly linked to nutrition and growth. Maturation only occurs once the juvenile has acquired sufficient nutrients and completed enough growth to produce a reproductively mature adult with a genetically predefined body size. Animals therefore adjust the duration of juvenile development to the dietary conditions. When nutrients are scarce the juvenile growth phase is extended to compensate for slow growth. Conversely, development is accelerated in nutrient rich environments where animals rapidly reach their genetic target size. To achieve such flexibility, nutrient-dependent growth regulators must feed into the endocrine system that controls the timing of maturation. Work on the fruit fly Drosophila has revealed a central role of secreted signal molecules with similarity to the conserved insulin-like growth factors (IGFs) in the decision making process. These molecules are involved in checkpoints that allow the endocrine system to decide whether to release the steroid hormone, ecdysone, that triggers maturation or extent development, depending on nutrient levels and growth status. Importantly, different dietary components influence timing of maturation in Drosophila, with proteins having the greatest impact; fat and sugar play a minor role, at least within the limits of what can be considered a balanced diet. Remarkably, excess dietary sugar concentrations that mimic physiological conditions associated with diabetes, negatively affect growth and delays maturation. Altogether, this shows that the source of energy in the diet is important for timing and may provide a paradigm for understanding the emerging links between diet, obesity and diabetes, and the onset of puberty. Here, we provide an overview of the system underlying developmental timing of maturation in Drosophila and review recent success in understanding its coupling to nutrition and growth. © 2013 Elsevier Inc. All rights reserved.

Temperature and Nutrient Effects on Periphyton Associated Bacterial Communities in Continuous Flow-Through Estuarine Mesocosms

NASA Astrophysics Data System (ADS)

Houghton, K.; James, J. B.; Devereux, R.; Friedman, S. D.

2016-02-01

Nutrient pollution is a leading cause of water quality impairments and degraded aquatic ecosystem condition. Reliable and reproducible indicators of ecosystem condition are needed to help manage nutrient pollution. The diatom component of periphyton has been used as a water quality indicator due to identifiable cell morphology and existence of relationships between nutrient concentration and diatom community composition. However, morphological identification of diatoms requires highly specialized personnel, is very time consuming, and can produce variable results, suggesting the need for alternative methods that are less expensive and more reproducible. DNA sequencing of the bacterial 16S rRNA gene is well documented and provides genus-level resolution of the community structure. The goal of this study was to evaluate the effects of nutrient loading and temperature on periphyton-associated bacterial communities using standard periphytometer techniques and next generation sequencing technologies. Continuous flow mesocosms were established in an eight tank system consisting of two temperature conditions (10°C and 20°C) and four nutrient conditions (1x to 6x ambient concentrations). Experimental conditions were replicated in July/August 2013 and September 2013. Replicate DNA samples were extracted and the 16S rRNA gene was sequenced using universal Bacterial primers. Initial analyses revealed strong differences in community structure based on temperature (p < 0.01, R = 0.997) and sampling month (p < 0.01, R = 0.993) while no significant differences were detected between nutrient treatments. These results suggest that the method can detect changes in periphyton associated bacterial communities based on temperature but a more refined approach, as might be based on functional genes instead of structural genes, may be needed to differentiate nutrient effects.

Neuronal Calcium Signaling in Metabolic Regulation and Adaptation to Nutrient Stress.

PubMed

Jayakumar, Siddharth; Hasan, Gaiti

2018-01-01

All organisms can respond physiologically and behaviorally to environmental fluxes in nutrient levels. Different nutrient sensing pathways exist for specific metabolites, and their inputs ultimately define appropriate nutrient uptake and metabolic homeostasis. Nutrient sensing mechanisms at the cellular level require pathways such as insulin and target of rapamycin (TOR) signaling that integrates information from different organ systems like the fat body and the gut. Such integration is essential for coordinating growth with development. Here we review the role of a newly identified set of integrative interneurons and the role of intracellular calcium signaling within these neurons, in regulating nutrient sensing under conditions of nutrient stress. A comparison of the identified Drosophila circuit and cellular mechanisms employed in this circuit, with vertebrate systems, suggests that the identified cell signaling mechanisms may be conserved for neural circuit function related to nutrient sensing by central neurons. The ideas proposed are potentially relevant for understanding the molecular basis of metabolic disorders, because these are frequently linked to nutritional stress.

Enabling nutrient security and sustainability through systems research.

PubMed

Kaput, Jim; Kussmann, Martin; Mendoza, Yery; Le Coutre, Ronit; Cooper, Karen; Roulin, Anne

2015-05-01

Human and companion animal health depends upon nutritional quality of foods. Seed varieties, seasonal and local growing conditions, transportation, food processing, and storage, and local food customs can influence the nutrient content of food. A new and intensive area of investigation is emerging that recognizes many factors in these agri-food systems that influence the maintenance of nutrient quality which is fundamental to ensure nutrient security for world populations. Modeling how these systems function requires data from different sectors including agricultural, environmental, social, and economic, but also must incorporate basic nutrition and other biomedical sciences. Improving the agri-food system through advances in pre- and post-harvest processing methods, biofortification, or fortifying processed foods will aid in targeting nutrition for populations and individuals. The challenge to maintain and improve nutrient quality is magnified by the need to produce food locally and globally in a sustainable and consumer-acceptable manner for current and future populations. An unmet requirement for assessing how to improve nutrient quality, however, is the basic knowledge of how to define health. That is, health cannot be maintained or improved by altering nutrient quality without an adequate definition of what health means for individuals and populations. Defining and measuring health therefore becomes a critical objective for basic nutritional and other biomedical sciences.

ULK1, mammalian target of rapamycin, and mitochondria: linking nutrient availability and autophagy.

PubMed

Kundu, Mondira

2011-05-15

A fundamental function of autophagy conserved from yeast to mammals is mobilization of macromolecules during times of limited nutrient availability, permitting organisms to survive under starvation conditions. In yeast, autophagy is initiated following nitrogen or carbon deprivation, and autophagy mutants die rapidly under these conditions. Similarly, in mammals, autophagy is upregulated in most organs following initiation of starvation, and is critical for survival in the perinatal period following abrupt termination of the placental nutrient supply. The nutrient-sensing kinase, mammalian target of rapamycin, coordinates cellular proliferation and growth with nutrient availability, at least in part by regulating protein synthesis and autophagy-mediated degradation. This review focusses on the regulation of autophagy by Tor, a mammalian target of rapamycin, and Ulk1, a mammalian homolog of Atg1, in response to changes in nutrient availability. Given the importance of mitochondria in maintaining bioenergetic homestasis, and potentially as a source of membrane for autophagosomes during starvation, possible roles for mitochondria in this process are also discussed.

Drug-nutrient interactions.

PubMed

Trovato, A; Nuhlicek, D N; Midtling, J E

1991-11-01

Drug-nutrient interactions are a commonly overlooked aspect of the prescribing practices of physicians. As more pharmaceutical agents become available, attention should be focused on interactions of drugs with foods and nutrients. Although drug-nutrient interactions are not as common as drug-drug interactions, they can have an impact on therapeutic outcome. Drugs can affect nutritional status by altering nutrient absorption, metabolism, utilization or excretion. Food, beverages and mineral or vitamin supplements can affect the absorption and effectiveness of drugs. Knowledge of drug-nutrient interactions can help reduce the incidence of these effects. Physicians should question patients about their dietary habits so that patients can be informed about possible interactions between a prescribed drug and foods and nutrients.

Roots bridge water to nutrients: a study of utilizing hydraulic redistribution through root systems to extract nutrients in the dry soils

NASA Astrophysics Data System (ADS)

Yan, J.; Ghezzehei, T. A.

2017-12-01

The rhizosphere is the region of soil that surrounds by individual plant roots. While its small volume and narrow region compared to bulk soil, the rhizosphere regulates numerous processes that determine physical structure, nutrient distribution, and biodiversity of soils. One of the most important and distinct functions of the rhizosphere is the capacity of roots to bridge and redistribute soil water from wet soil layers to drier layers. This process was identified and defined as hydraulic lift or hydraulic redistribution, a passive process driven by gradients in water potentials and it has attracted much research attention due to its important role in global water circulation and agriculture security. However, while previous studies mostly focused on the hydrological or physiological impacts of hydraulic redistribution, limited research has been conducted to elucidate its role in nutrient cycling and uptake. In this study, we aim to test the possibility of utilizing hydraulic redistribution to facilitate the nutrient movement and uptake from resource segregated zone. Our overarching hypothesis is that plants can extract nutrients from the drier but nutrient-rich regions by supplying sufficient amounts of water from the wet but nutrient-deficient regions. To test our hypothesis, we designed split-root systems of tomatoes with unequal supply of water and nutrients in different root compartments. More specifically, we transplanted tomato seedlings into sand or soil mediums, and grew them under conditions with alternate 12-h lightness and darkness. We continuously monitored the temperature, water and nutrient content of soils in these separated compartments. The above and below ground biomass were also quantified to evaluate the impacts on the plant growth. The results were compared to a control with evenly supply of water and nutrients to assess the plant growth, nutrient leaching and uptake without hydraulic redistribution.

Using Bacterial Growth on Insects to Assess Nutrient Impacts in Streams

Treesearch

A. Dennis Lemly

2000-01-01

A combination field and laboratory study was conducted to evaluate the ability of a recently developed bioindicator to detect detrimental nutrient conditions in streams. The method utilizes bacterial growth on aquatic insects to determine nutrient impacts. Field investigations indicated that elevated concentrations of nitrate and phosphate were associated with growth...

Maximizing the accuracy of field-derived numeric nutrient criteria in water quality regulations.

PubMed

McLaughlin, Douglas B

2014-01-01

High levels of the nutrients nitrogen and phosphorus can cause unhealthy biological or ecological conditions in surface waters and prevent the attainment of their designated uses. Regulatory agencies are developing numeric criteria for these nutrients in an effort to ensure that the surface waters in their jurisdictions remain healthy and productive, and that water quality standards are met. These criteria are often derived using field measurements that relate nutrient concentrations and other water quality conditions to expected biological responses such as undesirable growth or changes in aquatic plant and animal communities. Ideally, these numeric criteria can be used to accurately "diagnose" ecosystem health and guide management decisions. However, the degree to which numeric nutrient criteria are useful for decision making depends on how accurately they reflect the status or risk of nutrient-related biological impairments. Numeric criteria that have little predictive value are not likely to be useful for managing nutrient concerns. This paper presents information on the role of numeric nutrient criteria as biological health indicators, and the potential benefits of sufficiently accurate criteria for nutrient management. In addition, it describes approaches being proposed or adopted in states such as Florida and Maine to improve the accuracy of numeric criteria and criteria-based decisions. This includes a preference for developing site-specific criteria in cases where sufficient data are available, and the use of nutrient concentration and biological response criteria together in a framework to support designated use attainment decisions. Together with systematic planning during criteria development, the accuracy of field-derived numeric nutrient criteria can be assessed and maximized as a part of an overall effort to manage nutrient water quality concerns. © 2013 SETAC.

Groundwater – The disregarded component in lake water and nutrient budgets. Part 2: effects of groundwater on nutrients

USGS Publications Warehouse

Lewandowski, Jörg; Meinikmann, Karin; Nützmann, Gunnar; Rosenberry, Donald O.

2015-01-01

Lacustrine groundwater discharge (LGD) transports nutrients from a catchment to a lake, which may fuel eutrophication, one of the major threats to our fresh waters. Unfortunately, LGD has often been disregarded in lake nutrient studies. Most measurement techniques are based on separate determinations of volume and nutrient concentration of LGD: Loads are calculated by multiplying seepage volumes by concentrations of exfiltrating water. Typically low phosphorus (P) concentrations of pristine groundwater often are increased due to anthropogenic sources such as fertilizer, manure or sewage. Mineralization of naturally present organic matter might also increase groundwater P. Reducing redox conditions favour P transport through the aquifer to the reactive aquifer-lake interface. In some cases, large decreases of P concentrations may occur at the interface, for example, due to increased oxygen availability, while in other cases, there is nearly no decrease in P. The high reactivity of the interface complicates quantification of groundwater-borne P loads to the lake, making difficult clear differentiation of internal and external P loads to surface water. Anthropogenic sources of nitrogen (N) in groundwater are similar to those of phosphate. However, the environmental fate of N differs fundamentally from P because N occurs in several different redox states, each with different mobility. While nitrate behaves essentially conservatively in most oxic aquifers, ammonium's mobility is similar to that of phosphate. Nitrate may be transformed to gaseous N2 in reducing conditions and permanently removed from the system. Biogeochemical turnover of N is common at the reactive aquifer-lake interface. Nutrient loads from LGD were compiled from the literature. Groundwater-borne P loads vary from 0.74 to 2900 mg PO4-P m−2 year−1; for N, these loads vary from 0.001 to 640 g m−2 year−1. Even small amounts of seepage can carry large nutrient loads due to often high

New studies initiated by the U.S. Geological Survey - Effects of nutrient enrichment on stream ecosystems

USGS Publications Warehouse

Munn, Mark D.; Hamilton, Pixie A.

2003-01-01

In 2001, the U.S. Geological Survey’s National Water-Quality Assessment (NAWQA) Program began an intensive study of nutrient enrichment elevated concentrations of nitrogen and phosphorus in streams in five agricultural basins across the Nation (see map, p. 2). This study is providing nationally consistent and comparable data and analyses of nutrient conditions, including how these conditions vary as a result of natural and human-related factors, and how nutrient conditions affect algae and other biological communities. This information will benefit stakeholders, including the U.S. Environmental Protection Agency (USEPA) and its partners, who are developing nutrient criteria to protect the aquatic health of streams in different geographic regions.Nutrient enrichment is one of five national priority topics addressed by NAWQA in its second decade of studies, which began in 2001. During its first round of assessments in 51 major river basins (referred to as “Study Units”), NAWQA scientists collected data on water chemistry, stream hydrology and habitat, and biological communities; currently, NAWQA is revisiting selected basins and focusing on (1) trends, (2) factors that affect water quality and aquatic health, and (3) national priority water issues related to, for example, the development of nutrient criteria, source-water protection strategies, and stream restoration plans.The nutrient enrichment study has four major objectives that address nutrient conditions, dissolved oxygen, aquatic communities, and geographic and landscape features in agricultural basins (see inset). The focus on agricultural streams is a starting point. As the study progresses, streams draining other land uses, such as those in residential and urban areas, will likely be added.

Nutrient fluxes at the landscape level and the R* rule

USGS Publications Warehouse

Ju, Shu; DeAngelis, Donald L.

2010-01-01

Nutrient cycling in terrestrial ecosystems involves not only the vertical recycling of nutrients at specific locations in space, but also biologically driven horizontal fluxes between different areas of the landscape. This latter process can result in net accumulation of nutrients in some places and net losses in others. We examined the effects of such nutrient-concentrating fluxes on the R* rule, which predicts that the species that can survive in steady state at the lowest level of limiting resource, R*, can exclude all competing species. To study the R* rule in this context, we used a literature model of plant growth and nutrient cycling in which both nutrients and light may limit growth, with plants allocating carbon and nutrients between foliage and roots according to different strategies. We incorporated the assumption that biological processes may concentrate nutrients in some parts of the landscape. We assumed further that these processes draw nutrients from outside the zone of local recycling at a rate proportional to the local biomass density. Analysis showed that at sites where there is a sufficient biomass-dependent accumulation of nutrients, the plant species with the highest biomass production rates (roughly corresponding to the best competitors) do not reduce locally available nutrients to a minimum concentration level (that is, minimum R*), as expected from the R* rule, but instead maximize local nutrient concentration. These new results require broadening of our understanding of the relationships between nutrients and vegetation competition on the landscape level. The R* rule is replaced by a more complex criterion that varies across a landscape and reduces to the R* rule only under certain limiting conditions.

HYDRAULIC FRACTURING TO IMPROVE NUTRIENT AND OXYGEN DELIVERY FOR IN SITU BIORECLAMATION

EPA Science Inventory

The in situ delivery of nutrients and oxygen in soil is a serious problem in implementing in situ biodegradation. Current technology requires ideal site conditions to provide the remediating organisms with the nutrients and oxygen required for their metabolism, but...

Importance of Nutrients and Nutrient Metabolism on Human Health

PubMed Central

Chen, Yiheng; Michalak, Marek; Agellon, Luis B.

2018-01-01

Nutrition transition, which includes a change from consumption of traditional to modern diets that feature high-energy density and low nutrient diversity, is associated with acquired metabolic syndromes. The human diet is comprised of diverse components which include both nutrients, supplying the raw materials that drive multiple metabolic processes in every cell of the body, and non-nutrients. These components and their metabolites can also regulate gene expression and cellular function via a variety of mechanisms. Some of these components are beneficial while others have toxic effects. Studies have found that persistent disturbance of nutrient metabolism and/or energy homeostasis, caused by either nutrient deficiency or excess, induces cellular stress leading to metabolic dysregulation and tissue damage, and eventually to development of acquired metabolic syndromes. It is now evident that metabolism is influenced by extrinsic factors (e.g., food, xenobiotics, environment), intrinsic factors (e.g., sex, age, gene variations) as well as host/microbiota interaction, that together modify the risk for developing various acquired metabolic diseases. It is also becoming apparent that intake of diets with low-energy density but high in nutrient diversity may be the key to promoting and maintaining optimal health.

Plants may alter competition by modifying nutrient bioavailability in rhizosphere: a modeling approach.

PubMed

Raynaud, Xavier; Jaillard, Benoît; Leadley, Paul W

2008-01-01

Plants modify nutrient availability by releasing chemicals in the rhizosphere. This change in availability induced by roots (bioavailability) is known to improve nutrient uptake by individual plants releasing such compounds. Can this bioavailability alter plant competition for nutrients and under what conditions? To address these questions, we have developed a model of nutrient competition between plant species based on mechanistic descriptions of nutrient diffusion, plant exudation, and plant uptake. The model was parameterized using data of the effects of root citrate exudation on phosphorus availability. We performed a sensitivity analysis for key parameters to test the generality of these effects. Our simulations suggest the following. (1) Nutrient uptake depends on the number of roots when nutrients and exudates diffuse little, because individual roots are nearly independent in terms of nutrient supply. In this case, bioavailability profits only species with exudates. (2) Competition for nutrients depends on the spatial arrangement of roots when nutrients diffuse little but exudates diffuse widely. (3) Competition for nutrients depends on the nutrient uptake capacity of roots when nutrients and exudates diffuse widely. In this case, bioavailability profits all species. Mechanisms controlling competition for bioavailable nutrients appear to be diverse and strongly depend on soil, nutrient, and plant properties.

Role of the fish astyanax aeneus (Characidae) as a keystone nutrient recycler in low-nutrient neotropical streams

USGS Publications Warehouse

Small, G.E.; Pringle, C.M.; Pyron, M.; Duff, J.H.

2011-01-01

Nutrient recycling by animals is a potentially important biogeochemical process in both terrestrial and aquatic ecosystems. Stoichiometric traits of individual species may result in some taxa playing disproportionately important roles in the recycling of nutrients relative to their biomass, acting as keystone nutrient recyclers. We examined factors controlling the relative contribution of 12 Neotropical fish species to nutrient recycling in four streams spanning a range of phosphorus (P) levels. In high-P conditions (135 ??g/L soluble reactive phosphorus, SRP), most species fed on P-enriched diets and P excretion rates were high across species. In low-P conditions (3 ??g/L SRP), aquatic food resources were depleted in P, and species with higher body P content showed low rates of P recycling. However, fishes that were subsidized by terrestrial inputs were decoupled from aquatic P availability and therefore excreted P at disproportionately high rates. One of these species, Astyanax aeneus (Characidae), represented 12% of the total population and 18% of the total biomass of the fish assemblage in our focal low-P study stream but had P excretion rates >10-fold higher than other abundant fishes. As a result, we estimated that P excretion by A. aeneus accounted for 90% of the P recycled by this fish assemblage and also supplied ???90% of the stream P demand in this P-limited ecosystem. Nitrogen excretion rates showed little variation among species, and the contribution of a given species to ecosystem N recycling was largely dependent upon the total biomass of that species. Because of the high variability in P excretion rates among fish species, ecosystem-level P recycling could be particularly sensitive to changes in fish community structure in P-limited systems. ?? 2011 by the Ecological Society of America.

Applications of AnnAGNPS model for soil loss estimation and nutrient loading for Malaysian conditions

NASA Astrophysics Data System (ADS)

Shamshad, A.; Leow, C. S.; Ramlah, A.; Wan Hussin, W. M. A.; Sanusi, S. A. Mohd.

2008-09-01

The study evaluated the performance and suitability of AnnAGNPS model in assessing runoff, sediment loading and nutrient loading under Malaysian conditions. The watershed of River Kuala Tasik in Malaysia, a combination of two sub-watersheds, was selected as the area of study. The data for the year 2004 was used to calibrate the model and the data for the year 2005 was used for validation purposes. Several input parameters were computed using methods suggested by other researchers and studies carried out in Malaysia. The study shows that runoff was predicted well with an overall R2 value of 0.90 and E value of 0.70. Sediment loading was able to produce a moderate result of R2 = 0.66 and E = 0.49, nitrogen loading predictions were slightly better with R2 = 0.68 and E = 0.53, and phosphorus loading performance was slightly poor with an R2 = 0.63 and E = 0.33. The erosion map developed was in agreement with the erosion risk map produced by the Department of Agriculture, Malaysia. Rubber estates and urban areas were found to be the main contributors to soil erosion. The simulation results showed that AnnAGNPS has the potential to be used as a valuable tool for planning and management of watersheds under Malaysian conditions.

Data-driven nutrient analysis and reality check: Human inputs, catchment delivery and management effects

NASA Astrophysics Data System (ADS)

Destouni, G.

2017-12-01

Measures for mitigating nutrient loads to aquatic ecosystems should have observable effects, e.g, in the Baltic region after joint first periods of nutrient management actions under the Baltic Sea Action Plan (BASP; since 2007) and the EU Water Framework Directive (WFD; since 2009). Looking for such observable effects, all openly available water and nutrient monitoring data since 2003 are compiled and analyzed for Sweden as a case study. Results show that hydro-climatically driven water discharge dominates the determination of waterborne loads of both phosphorus and nitrogen. Furthermore, the nutrient loads and water discharge are all similarly well correlated with the ecosystem status classification of Swedish water bodies according to the WFD. Nutrient concentrations, which are hydro-climatically correlated and should thus reflect human effects better than loads, have changed only slightly over the study period (2003-2013) and even increased in moderate-to-bad status waters, where the WFD and BSAP jointly target nutrient decreases. These results indicate insufficient distinction and mitigation of human-driven nutrient components by the internationally harmonized applications of both the WFD and the BSAP. Aiming for better general identification of such components, nutrient data for the large transboundary catchments of the Baltic Sea and the Sava River are compared. The comparison shows cross-regional consistency in nutrient relationships to driving hydro-climatic conditions (water discharge) for nutrient loads, and socio-economic conditions (population density and farmland share) for nutrient concentrations. A data-driven screening methodology is further developed for estimating nutrient input and retention-delivery in catchments. Its first application to nested Sava River catchments identifies characteristic regional values of nutrient input per area and relative delivery, and hotspots of much larger inputs, related to urban high-population areas.

Drainage and fertilization effects on nutrient availability in an ombrotrophic peatland.

PubMed

Wang, Meng; Talbot, Julie; Moore, Tim R

2018-04-15

Nutrient availability is an important control on the vegetation distribution, productivity and functioning of peatland ecosystems and we examined spatial and temporal patterns of nutrient availability through ion exchange at Mer Bleue bog, southeast Ontario, Canada. We installed ion exchange probes at 5-15cm for 4weeks and determined nutrient sorption at undisturbed sites as well as those affected by nitrogen (N), phosphorus (P), potassium (K) fertilization and drainage. Under undisturbed conditions, the bog had very small amount of available nutrients, especially N (ammonium>nitrate) and P, and exhibited small variations in nutrient availability during the growing season (May to October). The increase in NPK availability upon fertilization was short-lived over the season and the stoichiometry of available NPK captured by the probes was mismatched with the vegetation. The increase in nutrient availability with drainage was confounded by substantial changes in vegetation. We compare these results with data from other Canadian bogs and fens to provide baseline data on nutrient availability in peatlands. Copyright © 2017 Elsevier B.V. All rights reserved.

7 CFR 205.203 - Soil fertility and crop nutrient management practice standard.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 3 2014-01-01 2014-01-01 false Soil fertility and crop nutrient management practice... Requirements § 205.203 Soil fertility and crop nutrient management practice standard. (a) The producer must..., and biological condition of soil and minimize soil erosion. (b) The producer must manage crop...

7 CFR 205.203 - Soil fertility and crop nutrient management practice standard.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 3 2013-01-01 2013-01-01 false Soil fertility and crop nutrient management practice... Requirements § 205.203 Soil fertility and crop nutrient management practice standard. (a) The producer must..., and biological condition of soil and minimize soil erosion. (b) The producer must manage crop...

7 CFR 205.203 - Soil fertility and crop nutrient management practice standard.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 3 2012-01-01 2012-01-01 false Soil fertility and crop nutrient management practice... Requirements § 205.203 Soil fertility and crop nutrient management practice standard. (a) The producer must..., and biological condition of soil and minimize soil erosion. (b) The producer must manage crop...

7 CFR 205.203 - Soil fertility and crop nutrient management practice standard.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 3 2011-01-01 2011-01-01 false Soil fertility and crop nutrient management practice... Requirements § 205.203 Soil fertility and crop nutrient management practice standard. (a) The producer must..., and biological condition of soil and minimize soil erosion. (b) The producer must manage crop...

ULK1, Mammalian Target of Rapamycin, and Mitochondria: Linking Nutrient Availability and Autophagy

PubMed Central

2011-01-01

Abstract A fundamental function of autophagy conserved from yeast to mammals is mobilization of macromolecules during times of limited nutrient availability, permitting organisms to survive under starvation conditions. In yeast, autophagy is initiated following nitrogen or carbon deprivation, and autophagy mutants die rapidly under these conditions. Similarly, in mammals, autophagy is upregulated in most organs following initiation of starvation, and is critical for survival in the perinatal period following abrupt termination of the placental nutrient supply. The nutrient-sensing kinase, mammalian target of rapamycin, coordinates cellular proliferation and growth with nutrient availability, at least in part by regulating protein synthesis and autophagy-mediated degradation. This review focusses on the regulation of autophagy by Tor, a mammalian target of rapamycin, and Ulk1, a mammalian homolog of Atg1, in response to changes in nutrient availability. Given the importance of mitochondria in maintaining bioenergetic homestasis, and potentially as a source of membrane for autophagosomes during starvation, possible roles for mitochondria in this process are also discussed. Antioxid. Redox Signal. 14, 1953–1958. PMID:21235397

The Nutrient Density of Snacks: A Comparison of Nutrient Profiles of Popular Snack Foods Using the Nutrient-Rich Foods Index.

PubMed

Hess, Julie; Rao, Goutham; Slavin, Joanne

2017-01-01

Background: Although Americans receive almost a quarter of their daily energy from snacks, snacking remains a poorly defined and understood eating occasion. However, there is little dietary guidance about choosing snacks. Families, clinicians, and researchers need a comprehensive approach to assessing their nutritional value. Objective: To quantify and compare the nutrient density of commonly consumed snacks by their overall nutrient profiles using the Nutrient-Rich Foods (NRF) Index 10.3. Methods: NRF Index scores were calculated for the top 3 selling products (based on 2014 market research data) in different snack categories. These NRF scores were averaged to provide an overall nutrient-density score for each category. Results: Based on NRF scores, yogurt (55.3), milk (52.5), and fruit (30.1) emerged as the most nutrient-dense snacks. Ice cream (-4.4), pies and cakes (-11.1), and carbonated soft drinks (-17.2) emerged as the most nutrient-poor snacks. Conclusions: The NRF Index is a useful tool for assessing the overall nutritional value of snacks based on nutrients to limit and nutrients to encourage.

Nutrient fluxes across sediment-water interface in Bohai Bay Coastal Zone, China.

PubMed

Mu, Di; Yuan, Dekui; Feng, Huan; Xing, Fangwei; Teo, Fang Yenn; Li, Shuangzhao

2017-01-30

Sediment cores and overlying water samples were collected at four sites in Tianjin Coastal Zone, Bohai Bay, to investigate nutrient (N, P and Si) exchanges across the sediment-water interface. The exchange fluxes of each nutrient species were estimated based on the porewater profiles and laboratory incubation experiments. The results showed significant differences between the two methods, which implied that molecular diffusion alone was not the dominant process controlling nutrient exchanges at these sites. The impacts of redox conditions and bioturbation on the nutrient fluxes were confirmed by the laboratory incubation experiments. The results from this study showed that the nutrient fluxes measured directly from the incubation experiment were more reliable than that predicted from the porewater profiles. The possible impacts causing variations in the nutrient fluxes include sewage discharge and land reclamation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Uniform modeling of bacterial colony patterns with varying nutrient and substrate

NASA Astrophysics Data System (ADS)

Schwarcz, Deborah; Levine, Herbert; Ben-Jacob, Eshel; Ariel, Gil

2016-04-01

Bacteria develop complex patterns depending on growth condition. For example, Bacillus subtilis exhibit five different patterns depending on substrate hardness and nutrient concentration. We present a unified integro-differential model that reproduces the entire experimentally observed morphology diagram at varying nutrient concentrations and substrate hardness. The model allows a comprehensive and quantitative comparison between experimental and numerical variables and parameters, such as colony growth rate, nutrient concentration and diffusion constants. As a result, the role of the different physical mechanisms underlying and regulating the growth of the colony can be evaluated.

The Genome-Wide Interaction Network of Nutrient Stress Genes in Escherichia coli.

PubMed

Côté, Jean-Philippe; French, Shawn; Gehrke, Sebastian S; MacNair, Craig R; Mangat, Chand S; Bharat, Amrita; Brown, Eric D

2016-11-22

Conventional efforts to describe essential genes in bacteria have typically emphasized nutrient-rich growth conditions. Of note, however, are the set of genes that become essential when bacteria are grown under nutrient stress. For example, more than 100 genes become indispensable when the model bacterium Escherichia coli is grown on nutrient-limited media, and many of these nutrient stress genes have also been shown to be important for the growth of various bacterial pathogens in vivo To better understand the genetic network that underpins nutrient stress in E. coli, we performed a genome-scale cross of strains harboring deletions in some 82 nutrient stress genes with the entire E. coli gene deletion collection (Keio) to create 315,400 double deletion mutants. An analysis of the growth of the resulting strains on rich microbiological media revealed an average of 23 synthetic sick or lethal genetic interactions for each nutrient stress gene, suggesting that the network defining nutrient stress is surprisingly complex. A vast majority of these interactions involved genes of unknown function or genes of unrelated pathways. The most profound synthetic lethal interactions were between nutrient acquisition and biosynthesis. Further, the interaction map reveals remarkable metabolic robustness in E. coli through pathway redundancies. In all, the genetic interaction network provides a powerful tool to mine and identify missing links in nutrient synthesis and to further characterize genes of unknown function in E. coli Moreover, understanding of bacterial growth under nutrient stress could aid in the development of novel antibiotic discovery platforms. With the rise of antibiotic drug resistance, there is an urgent need for new antibacterial drugs. Here, we studied a group of genes that are essential for the growth of Escherichia coli under nutrient limitation, culture conditions that arguably better represent nutrient availability during an infection than rich

Influence of tryptophan and indole-3-acetic acid on starch accumulation in the synthetic mutualistic Chlorella sorokiniana-Azospirillum brasilense system under heterotrophic conditions.

PubMed

Palacios, Oskar A; Choix, Francisco J; Bashan, Yoav; de-Bashan, Luz E

2016-06-01

This study measured the relations between tryptophan production, the phytohormone indole-3-acetic acid (IAA) and the metabolism and accumulation of starch during synthetic mutualism between the microalgae Chlorella sorokiniana and the microalgae growth-promoting bacteria Azospirillum brasilense, created by co-immobilization in alginate beads. Experiments used two wild-type A. brasilense strains (Cd and Sp6) and an IAA-attenuated mutant (SpM7918) grown under nitrogen-replete and nitrogen-starved conditions tested under dark, heterotrophic and aerobic growth conditions. Under all incubating conditions, C. sorokiniana, but not A. brasilense, produced tryptophan. A significant correlation between IAA-production by A. brasilense and starch accumulation in C. sorokiniana was found, since the IAA-attenuated mutant was not producing increased starch levels. The highest ADP-glucose pyrophosphorylase (AGPase) activity, starch content and glucose uptake were found during the interaction of A. brasilense wild type strains with the microalgae. When the microalgae were grown alone, they produced only small amounts of starch. Supplementation with synthetic IAA to C. sorokiniana grown alone enhanced the above parameters, but only transiently. Activity of α-amylase decreased under nitrogen-replete conditions, but increased under nitrogen-starved conditions. In summary, this study demonstrated that, during synthetic mutualism, the exchange of tryptophan and IAA between the partners is a mechanism that governs several changes in starch metabolism of C. sorokiniana, yielding an increase in starch content. Copyright © 2016 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Climate Variability Impacts on Watershed Nutrient Delivery and Reservoir Production

NASA Astrophysics Data System (ADS)

White, J. D.; Prochnow, S. J.; Zygo, L. M.; Byars, B. W.

2005-05-01

Reservoirs in agricultural dominated watersheds tend to exhibit pulse-system behavior especially if located in climates dominated by summer convective precipitation inputs. Concentration and bulk mass of nutrient and sediment inputs into reservoir systems vary in terms of timing and magnitude of delivery from watershed sources to reservoirs under these climate conditions. Reservoir management often focuses on long-term average inputs without considering short and long-term impacts of variation in loading. In this study we modeled a watershed-reservoir system to assess how climate variability affects reservoir primary production through shifts in external loading and internal recycling of limiting nutrients. The Bosque watershed encompasses 423,824 ha in central Texas which delivers water to Lake Waco, a 2900 ha reservoir that is the primary water source for the city of Waco and surrounding areas. Utilizing the Soil Water Assessment Tool for the watershed and river simulations and the CE-Qual-2e model for the reservoir, hydrologic and nutrient dynamics were simulated for a 10 year period encompassing two ENSO cycles. The models were calibrated based on point measurement of water quality attributes for a two year time period. Results indicated that watershed delivery of nutrients was affected by the presence and density of small flood-control structure in the watershed. However, considerable nitrogen and phosphorus loadings were derived from soils in the upper watershed which have had long-term waste-application from concentrated animal feeding operations. During El Niño years, nutrient and sediment loads increased by 3 times above non-El Niño years. The simulated response within the reservoir to these nutrient and sediment loads had both direct and indirect. Productivity evaluated from chlorophyll a and algal biomass increased under El Niño conditions, however species composition shifts were found with an increase in cyanobacteria dominance. In non-El Niño years

Interactive effects of nutrient additions and predation on infaunal communities

USGS Publications Warehouse

Posey, M.H.; Alphin, T.D.; Cahoon, L.; Lindquist, D.; Becker, M.E.

1999-01-01

Nutrient additions represent an important anthropogenic stress on coastal ecosystems. At moderate levels, increased nutrients may lead to increased primary production and, possibly, to increased biomass of consumers although complex trophic interactions may modify or mask these effects. We examined the influence of nutrient additions and interactive effects of trophic interactions (predation) on benthic infaunal composition and abundances through small-scale field experiments in 2 estuaries that differed in ambient nutrient conditions. A blocked experimental design was used that allowed an assessment of direct nutrient effects in the presence and absence of predation by epibenthic predators as well as an assessment of the independent effects of predation. Benthic microalgal production increased with experimental nutrient additions and was greater when infaunal abundances were lower, but there were no significant interactions between these factors. Increased abundances of one infaunal taxa, Laeonereis culveri, as well as the grazer feeding guild were observed with nutrient additions and a number of taxa exhibited higher abundances with predator exclusion. In contrast to results from freshwater systems there were no significant interactive effects between nutrient additions and predator exclusion as was predicted. The infaunal responses observed here emphasize the importance of both bottom-up (nutrient addition and primary producer driven) and top-down (predation) controls in structuring benthic communities. These processes may work at different spatial and temporal scales, and affect different taxa, making observation of potential interactive effects difficult.

Variation in nutrients formulated and nutrients supplied on 5 California dairies.

PubMed

Rossow, H A; Aly, S S

2013-01-01

Computer models used in ration formulation assume that nutrients supplied by a ration formulation are the same as the nutrients presented in front of the cow in the final ration. Deviations in nutrients due to feed management effects such as dry matter changes (i.e., rain), loading, mixing, and delivery errors are assumed to not affect delivery of nutrients to the cow and her resulting milk production. To estimate how feed management affects nutrients supplied to the cow and milk production, and determine if nutrients can serve as indexes of feed management practices, weekly total mixed ration samples were collected and analyzed for 4 pens (close-up cows, fresh cows, high-milk-producing, and low-milk-producing cows, if available) for 7 to 12 wk on 5 commercial California dairies. Differences among nutrient analyses from these samples and nutrients from the formulated rations were analyzed by PROC MIXED of SAS (SAS Institute Inc., Cary, NC). Milk fat and milk protein percentages did not vary as much [coefficient of variation (CV) = 18 to 33%] as milk yield (kg; CV = 16 to 47 %) across all dairies and pens. Variability in nutrients delivered were highest for macronutrient fat (CV = 22%), lignin (CV = 15%), and ash (CV = 11%) percentages and micronutrients Fe (mg/kg; CV = 48%), Na (%; CV = 42%), and Zn (mg/kg; CV = 38%) for the milking pens across all dairies. Partitioning of the variability in random effects of nutrients delivered and intraclass correlation coefficients showed that variability in lignin percentage of TMR had the highest correlation with variability in milk yield and milk fat percentage, followed by fat and crude protein percentages. But, variability in ash, fat, and lignin percentages of total mixed ration had the highest correlation with variability in milk protein percentage. Therefore, lignin, fat, and ash may be the best indices of feed management to include effects of variability in nutrients on variability in milk yield, milk fat, and milk

Effect of supranutritional maternal and colostral selenium supplementation on passive absorption of immunoglobulin G in selenium-replete dairy calves.

PubMed

Hall, Jean A; Bobe, Gerd; Vorachek, William R; Estill, Charles T; Mosher, Wayne D; Pirelli, Gene J; Gamroth, Mike

2014-07-01

Selenium (Se) is an essential micronutrient for ruminant animals affecting both performance and immune functions. Adding 3 mg of Se/L (in the form of Na selenite) to colostrum has been shown to improve IgG absorption in Se-deficient newborn dairy calves. The objective of our study was to determine the effect of supranutritional maternal and colostral Se supplementation on IgG status of Se-replete dairy calves. The study design was a 2 × 2 × 2 factorial design. During the last 8 wk before calving, dairy cows at a commercial dairy were fed either 0 (control cows) or 105 mg of Se-yeast once weekly (supranutritional Se-yeast-supplemented cows), in addition to Na selenite at 0.3 mg of Se/kg of DM in their ration. After birth, calves were fed pooled colostrum from control or supranutritional Se-yeast-supplemented cows to which 0 or 3 mg of Se/L (in the form of Na selenite) was added. Concentrations of whole-blood (WB) Se and serum Se measured at birth and at 48 h and 14 d of age, and serum IgG concentrations measured at 48 h and 14 and 60 d of age were determined. Calves born to Se-yeast-supplemented cows had higher WB-Se and serum-Se concentrations for the first 2 wk, and higher IgG absorption efficiency (62% at 48 h), resulting in higher serum-IgG concentrations (43% at 48 h and 65% at 14 d) and higher total serum-IgG content (50% at 48 h and 75% at 14 d), compared with calves born to control cows. Calves that received colostrum with added Na selenite had higher WB-Se concentrations for the first 2 wk, but only at 14 d of age were serum-Se concentrations, serum-IgG concentrations (53% higher), and total serum-IgG content (56% higher) higher, compared with calves that were fed colostrum without added Na selenite. Calves born to Se-yeast-supplemented cows that received colostrum from Se-yeast cows without added Na selenite had a higher IgG absorption efficiency compared with all other treatment groups. Our results support that feeding cows supranutritional Se

What’s Upstream? GIS’s critical role in developing nutrient reference conditions for estuaries

EPA Science Inventory

Eutrophication due to excess levels of nitrogen and phosphorus can seriously impair ecological function in estuaries. Protective criteria for nutrients are difficult to establish because the source can vary spatially and seasonally, originate either from the watershed or the oce...

Mathematical analysis of a nutrient-plankton system with delay.

PubMed

Rehim, Mehbuba; Zhang, Zhenzhen; Muhammadhaji, Ahmadjan

2016-01-01

A mathematical model describing the interaction of nutrient-plankton is investigated in this paper. In order to account for the time needed by the phytoplankton to mature after which they can release toxins, a discrete time delay is incorporated into the system. Moreover, it is also taken into account discrete time delays which indicates the partially recycled nutrient decomposed by bacteria after the death of biomass. In the first part of our analysis the sufficient conditions ensuring local and global asymptotic stability of the model are obtained. Next, the existence of the Hopf bifurcation as time delay crosses a threshold value is established and, meanwhile, the phenomenon of stability switches is found under certain conditions. Numerical simulations are presented to illustrate the analytical results.

Analysis of blocking of flavor-preference conditioning based on nutrients and palatable tastes in rats.

PubMed

González, Felisa; Garcia-Burgos, David; Hall, Geoffrey

2014-09-01

In Experiment 1 rats were given training in which a mixture of two flavors was paired with sucrose. This established a substantial preference for each of the flavors; however, when rats were given prior experience with just one of the flavors paired with sucrose, training with the compound produced only a weak preference for the other - an example of the blocking effect, well known in other associative learning paradigms. Both the palatable taste of sucrose and its nutrient properties contribute to its ability to reinforce preference acquisition. The role of these two forms of learning was examined in two further experiments in which the reinforcer used was fructose (which is considered to support preference learning because it is palatable but not through its nutrient properties) or maltodextrin (thought to support preference learning by way of its nutrient properties). In neither case was blocking observed. At the theoretical level, this outcome constitutes a challenge to the attempt to explain flavor-preference learning in terms of the standard principles of associative learning theory. Its implication at the level of application is that the potential of the blocking procedure as a technique for preventing the development of unwanted flavor preferences may be limited. Copyright © 2014 Elsevier Ltd. All rights reserved.

Identifying nutrient reference sites in nutrient-enriched regions-Using algal, invertebrate, and fish-community measures to identify stressor-breakpoint thresholds in Indiana rivers and streams, 2005-9

USGS Publications Warehouse

Caskey, Brian J.; Bunch, Aubrey R.; Shoda, Megan E.; Frey, Jeffrey W.; Selvaratnam, Shivi; Miltner, Robert J.

2013-01-01

Excess nutrients in aquatic ecosystems can lead to shifts in species composition, reduced dissolved oxygen concentrations, fish kills, and toxic algal blooms. In this study, nutrients, periphyton chlorophyll a (CHLa), and invertebrate- and fishcommunity data collected during 2005-9 were analyzed from 318 sites on Indiana rivers and streams. The objective of this study was to determine which invertebrate and fish-taxa attributes best reflect the conditions of streams in Indiana along a gradient of nutrient concentrations by (1) determining statistically and ecologically significant relations among the stressor (total nitrogen, total phosphorus, and periphyton CHLa) and response (invertebrate and fish community) variables; and (2) determining the levels at which invertebrate- and fish-community measures change in response to nutrients or periphyton CHLa. For water samples at the headwater sites, total nitrogen (TN) concentrations ranged from 0.343 to 21.6 milligrams per liter (mg/L) (median 2.12 mg/L), total phosphorus (TP) concentrations ranged from 0.050 to 1.44 mg/L (median 0.093 mg/L), and periphyton CHLa ranged from 0.947 to 629 mg/L (median 69.7 mg/L). At the wadable sites, TN concentrations ranged from 0.340 to 10.0 mg/L (median 2.31 mg/L), TP concentrations ranged from 0.050 to 1.24 mg/L (median 0.110 mg/L), and periphyton CHLa ranged from 0.383 to 719 mg/L (median 44.7 mg/L). Recursive partitioning identified statistically significant low and high breakpoint thresholds on invertebrate and fish measures, which demonstrated the ecological response in enriched conditions. The combined community (invertebrate and fish) mean low and high TN breakpoint thresholds were 1.03 and 2.61 mg/L, respectively. The mean low and high breakpoint thresholds for TP were 0.083 and 0.144 mg/L, respectively. The mean low and high breakpoint thresholds for periphyton CHLa were 20.9 and 98.6 milligrams per square meter (mg/m2), respectively. Additive quantile regression analysis

Increased Toxicity of Karenia brevis during Phosphate Limited Growth: Ecological and Evolutionary Implications

PubMed Central

Hardison, Donnie Ransom; Sunda, William G.; Shea, Damian; Litaker, Richard Wayne

2013-01-01

Karenia brevis is the dominant toxic red tide algal species in the Gulf of Mexico. It produces potent neurotoxins (brevetoxins [PbTxs]), which negatively impact human and animal health, local economies, and ecosystem function. Field measurements have shown that cellular brevetoxin contents vary from 1–68 pg/cell but the source of this variability is uncertain. Increases in cellular toxicity caused by nutrient-limitation and inter-strain differences have been observed in many algal species. This study examined the effect of P-limitation of growth rate on cellular toxin concentrations in five Karenia brevis strains from different geographic locations. Phosphorous was selected because of evidence for regional P-limitation of algal growth in the Gulf of Mexico. Depending on the isolate, P-limited cells had 2.3- to 7.3-fold higher PbTx per cell than P-replete cells. The percent of cellular carbon associated with brevetoxins (%C-PbTx) was ∼ 0.7 to 2.1% in P-replete cells, but increased to 1.6–5% under P-limitation. Because PbTxs are potent anti-grazing compounds, this increased investment in PbTxs should enhance cellular survival during periods of nutrient-limited growth. The %C-PbTx was inversely related to the specific growth rate in both the nutrient-replete and P-limited cultures of all strains. This inverse relationship is consistent with an evolutionary tradeoff between carbon investment in PbTxs and other grazing defenses, and C investment in growth and reproduction. In aquatic environments where nutrient supply and grazing pressure often vary on different temporal and spatial scales, this tradeoff would be selectively advantageous as it would result in increased net population growth rates. The variation in PbTx/cell values observed in this study can account for the range of values observed in the field, including the highest values, which are not observed under N-limitation. These results suggest P-limitation is an important factor regulating cellular

Nutrient management effects on sweetpotato genotypes under controlled environment

NASA Technical Reports Server (NTRS)

David, P. P.; Bonsi, C. K.; Trotman, A. A.; Douglas, D. Z.

1996-01-01

Sweetpotato is one of several crops recommended by National Aeronautics and Space Administration (NASA) for bioregenerative life support studies. One of the objectives of the Tuskegee University NASA Center is to optimize growth conditions for adaptability of sweetpotatoes for closed bioregenerative systems. The role of nutrient solution management as it impacts yield has been one of the major thrusts in these studies. Nutrient solution management protocol currently used consists of a modified half Hoagland solution that is changed at 14-day intervals. Reservoirs are refilled with deionized water if the volume of the nutrient solution was reduced to 8 liters or less before the time of solution change. There is the need to recycle and replenish nutrient solution during crop growth, rather than discard at 14 day intervals as previously done, in order to reduce waste. Experiments were conducted in an environmental growth room to examine the effects of container size on the growth of several sweetpotato genotypes grown under a nutrient replenishment protocol. Plants were grown from vine cuttings of 15cm length and were planted in 0.15 x 0.15 x 1.2m growth channels using a closed nutrient film technique system. Nutrient was supplied in a modified half strength Hoagland's solution with a 1:2.4 N:K ratio. Nutrient replenishment protocol consisted of daily water replenishment to a constant volume of 30.4 liters in the small containers and 273.6 liters in the large container. Nutrients were replenished as needed when the EC of the nutrient solution fell below 1200 mhos/cm. The experimental design used was a split-plot with the main plot being container size and genotypes as the subplot. Nine sweetpotato genotypes were evaluated. Results showed no effect of nutrient solution container size on storage root yield, foliage fresh and dry mass, leaf area or vine length. However, plants grown using the large nutrient solution container accumulated more storage root dry mass than

Proposal for a method to estimate nutrient shock effects in bacteria

PubMed Central

2012-01-01

Background Plating methods are still the golden standard in microbiology; however, some studies have shown that these techniques can underestimate the microbial concentrations and diversity. A nutrient shock is one of the mechanisms proposed to explain this phenomenon. In this study, a tentative method to assess nutrient shock effects was tested. Findings To estimate the extent of nutrient shock effects, two strains isolated from tap water (Sphingomonas capsulata and Methylobacterium sp.) and two culture collection strains (E. coli CECT 434 and Pseudomonas fluorescens ATCC 13525) were exposed both to low and high nutrient conditions for different times and then placed in low nutrient medium (R2A) and rich nutrient medium (TSA). The average improvement (A.I.) of recovery between R2A and TSA for the different times was calculated to more simply assess the difference obtained in culturability between each medium. As expected, A.I. was higher when cells were plated after the exposition to water than when they were recovered from high-nutrient medium showing the existence of a nutrient shock for the diverse bacteria used. S. capsulata was the species most affected by this phenomenon. Conclusions This work provides a method to consistently determine the extent of nutrient shock effects on different microorganisms and hence quantify the ability of each species to deal with sudden increases in substrate concentration. PMID:22873690

Oil and eicosapentaenoic acid production by the diatom Phaeodactylum tricornutum cultivated outdoors in Green Wall Panel (GWP®) reactors.

PubMed

Rodolfi, Liliana; Biondi, Natascia; Guccione, Alessia; Bassi, Niccolò; D'Ottavio, Massimo; Arganaraz, Gimena; Tredici, Mario R

2017-10-01

Phaeodactylum tricornutum is a widely studied diatom and has been proposed as a source of oil and polyunsaturated fatty acids (PUFA), particularly eicosapentaenoic acid (EPA). Recent studies indicate that lipid accumulation occurs under nutritional stress. Aim of this research was to determine how changes in nitrogen availability affect productivity, oil yield, and fatty acid (FA) composition of P. tricornutum UTEX 640. After preliminary laboratory trials, outdoor experiments were carried out in 40-L GWP® reactors under different nitrogen regimes in batch. Nitrogen replete cultures achieved the highest productivity of biomass (about 18 g m -2  d -1 ) and EPA (about 0.35 g m -2  d -1 ), whereas nitrogen-starved cultures achieved the highest FA productivity (about 2.6 g m -2  d -1 ). The annual potential yield of P. tricornutum grown outdoors in GWP® reactors is 730 kg of EPA per hectare under nutrient-replete conditions and 5,800 kg of FA per hectare under nitrogen starvation. Biotechnol. Bioeng. 2017;114: 2204-2210. © 2017 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc. © 2017 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc.

Microbial enzyme activity, nutrient uptake and nutrient limitation in forested streams

Treesearch

Brian H. Hill; Frank H. McCormick; Bret C. Harvey; Sherri L. Johnson; Melvin L. Warren; Colleen M. Elonen

2010-01-01

The flow of organic matter and nutrients from catchments into the streams draining them and the biogeochemical transformations of organic matter and nutrients along flow paths are fundamental processes instreams (Hynes,1975; Fisher, Sponseller & Heffernan, 2004). Microbial biofilms are often the primary interface for organic matter and nutrient uptake and...

Effects of elevated nutrients and CO2 emission scenarios on three coral reef macroalgae.

PubMed

Bender-Champ, Dorothea; Diaz-Pulido, Guillermo; Dove, Sophie

2017-05-01

Coral reef macroalgae are expected to thrive in the future under conditions that are deleterious to the health of reef-building corals. Here we examined how macroalgae would be affected by exposure to future CO 2 emission scenarios (pCO 2 and temperature), enriched nutrients and combinations of both. The species tested, Laurencia intricata (Rhodophyta), Turbinaria ornata and Chnoospora implexa (both Phaeophyceae), have active carbon-concentrating mechanisms but responded differently to the treatments. L. intricata showed high mortality under nutrient enriched RCP4.5 ("reduced" CO 2 emission) and RCP8.5 ("business-as-usual" CO 2 emission) and grew best under pre-industrial (PI) conditions, where it could take up carbon using external carbonic anhydrase combined, potentially, with proton extrusion. T. ornata's growth rate showed a trend for reduction under RCP8.5 but was unaffected by nutrient enrichment. In C. implexa, highest growth was observed under PI conditions, but highest net photosynthesis occurred under RCP8.5, suggesting that under RCP8.5, carbon is stored and respired at greater rates while it is directed to growth under PI conditions. None of the species showed growth enhancement under future scenarios, nutrient enrichment or combinations of both. This leads to the conclusion that under such conditions these species are unlikely to pose an increasing threat to coral reefs. Copyright © 2017 Elsevier B.V. All rights reserved.

Time-scale Dependence of Response of an Estuarine Water Quality Model to Nutrient Loading

EPA Science Inventory

We describe calibration and evaluation of a water quality model being implemented for Narragansett Bay to quantify the response of concentrations of nutrients, phytoplankton chlorophyll a and dissolved oxygen in the Bay to loading rates of nutrients and other boundary conditions....

Soil nutrient availability and reproductive effort drive patterns in nutrient resorption in Pentachlethra macroloba

Treesearch

K. L. Tully; Tana Wood; A. M. Schwantes; D. Lawrence

2013-01-01

The removal of nutrients from senescing tissues, nutrient resorption, is a key strategy for conserving nutrients in plants. However, our understanding of what drives patterns of nutrient resorption in tropical trees is limited. We examined the effects of nutrient sources (stand-level and tree-level soil fertility) and sinks (reproductive effort) on nitrogen (N) and...

Significant drug-nutrient interactions.

PubMed

Kirk, J K

1995-04-01

Many nutrients substantially interfere with pharmacotherapeutic goals. The presence of certain nutrients in the gastrointestinal tract affects the bioavailability and disposition of many oral medications. Drug-nutrient interactions can also have positive effects that result in increased drug absorption or reduced gastrointestinal irritation. Knowing the significant drug-nutrient interactions can help the clinician identify the nutrients to avoid with certain medications, as well as the therapeutic agents that should be administered with food. This information can be used to educate patients and optimize pharmacotherapy.

Relationships Among Watershed Condition, Nutrients, and Algae in New England Streams Affected by Urbanization

EPA Science Inventory

We examined algal metrics as indicators of altered watershed land cover and nutrients to inform their potential use in monitoring programs. Multiple regression models, in which impervious cover explained the most variation, indicated concentrations <0.202 mg/l NO3 and <0.015 mg/l...

Nutrient availability at Mer Bleue bog measured by PRSTM probes

NASA Astrophysics Data System (ADS)

Wang, M.; Moore, T. R.; Talbot, J.

2015-12-01

Bogs, covering ~0.7 million km2 in Canada, store a large amount of C and N. As nutrient deficient ecosystems, it's critical to examine the nutrient availabilities and seasonal dynamics. We used Plant Root Simulators (PRSTM) at Mer Bleue bog to provide some baseline data on nutrient availability and its variability. In particular, we focused on ammonium, nitrate, phosphate, calcium, magnesium and potassium, iron, sulphate and aluminum. We placed PRS probes at a depth of 5 - 15 cm in pristine plots and plots with long term N, P and K fertilization for 4 weeks and determined the availability of these nutrients, from spring through to fall. Probes were also placed beneath the water table in hummock and hollow microtopography and along a transect including part of the bog which had been drained through the creation of a ditch 80 years ago. The result showed that there was limited available ammonium, nitrate and phosphate in the bog, the seasonal variation of nutrient availabilities probably due to mineralization, an increase in the availability of some nutrients between different water table depths or as a result of drainage, and the relative availability of nutrients compared to the input from fertilization. We suggest that PRS probes could be a useful tool to examine nutrient availability and dynamics in wetlands, with careful consideration of installing condition, for example, proper exposure period, depth relative to water table etc.

Transcriptional and Physiological Responses to Nutrient Loading on Toxin Formation and Photosynthesis in Microcystis Aeruginosa FACHB-905

PubMed Central

Peng, Guotao; Lin, Sijie; Fan, Zhengqiu; Wang, Xiangrong

2017-01-01

An important goal of understanding harmful algae blooms is to determine how environmental factors affect the growth and toxin formation of toxin-producing species. In this study, we investigated the transcriptional responses of toxin formation gene (mcyB) and key photosynthesis genes (psaB, psbD and rbcL) of Microcystis aeruginosa FACHB-905 in different nutrient loading conditions using real-time reverse transcription quantitative polymerase chain reaction (RT-qPCR). Three physio-biochemical parameters (malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione (GSH)) were also evaluated to provide insight into the physiological responses of Microcystis cells. We observed an upregulation of mcyB gene in nutrient-deficient conditions, especially in nitrogen (N) limitation condition, and the transcript abundance declined after the nutrient were resupplied. Differently, high transcription levels were seen in phosphorus (P) deficient treatments for key photosynthesis genes throughout the culture period, while those in N-deficient cells varied with time, suggesting an adaptive regulation of Microsystis cells to nutrient stress. Increased contents of antioxidant enzymes (SOD and GSH) were seen in both N and P-deficient conditions, suggesting the presence of excess amount of free radical generation caused by nutrient stress. The amount of SOD and GSH continued to increase even after the nutrient was reintroduced and a strong correlation was seen between the MDA and enzyme activities, indicating the robust effort of rebalancing the redox system in Microcystis cells. Based on these transcriptional and physiological responses of M. aeruginosa to nutrient loading, these results could provide more insight into Microcystis blooms management and toxin formation regulation. PMID:28513574

Transcriptional and Physiological Responses to Nutrient Loading on Toxin Formation and Photosynthesis in Microcystis Aeruginosa FACHB-905.

PubMed

Peng, Guotao; Lin, Sijie; Fan, Zhengqiu; Wang, Xiangrong

2017-05-17

An important goal of understanding harmful algae blooms is to determine how environmental factors affect the growth and toxin formation of toxin-producing species. In this study, we investigated the transcriptional responses of toxin formation gene ( mcyB ) and key photosynthesis genes ( psaB , psbD and rbcL) of Microcystis aeruginosa FACHB-905 in different nutrient loading conditions using real-time reverse transcription quantitative polymerase chain reaction (RT-qPCR). Three physio-biochemical parameters (malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione (GSH)) were also evaluated to provide insight into the physiological responses of Microcystis cells. We observed an upregulation of mcyB gene in nutrient-deficient conditions, especially in nitrogen (N) limitation condition, and the transcript abundance declined after the nutrient were resupplied. Differently, high transcription levels were seen in phosphorus (P) deficient treatments for key photosynthesis genes throughout the culture period, while those in N-deficient cells varied with time, suggesting an adaptive regulation of Microsystis cells to nutrient stress. Increased contents of antioxidant enzymes (SOD and GSH) were seen in both N and P-deficient conditions, suggesting the presence of excess amount of free radical generation caused by nutrient stress. The amount of SOD and GSH continued to increase even after the nutrient was reintroduced and a strong correlation was seen between the MDA and enzyme activities, indicating the robust effort of rebalancing the redox system in Microcystis cells. Based on these transcriptional and physiological responses of M. aeruginosa to nutrient loading, these results could provide more insight into Microcystis blooms management and toxin formation regulation.

A novel approach to selecting and weighting nutrients for nutrient profiling of foods and diets.

PubMed

Arsenault, Joanne E; Fulgoni, Victor L; Hersey, James C; Muth, Mary K

2012-12-01

Nutrient profiling of foods is the science of ranking or classifying foods based on their nutrient composition. Most profiling systems use similar weighting factors across nutrients due to lack of scientific evidence to assign levels of importance to nutrients. Our aim was to use a statistical approach to determine the nutrients that best explain variation in Healthy Eating Index (HEI) scores and to obtain β-coefficients for the nutrients for use as weighting factors for a nutrient-profiling algorithm. We used a cross-sectional analysis of nutrient intakes and HEI scores. Our subjects included 16,587 individuals from the National Health and Nutrition Examination Survey 2005-2008 who were 2 years of age or older and not pregnant. Our main outcome measure was variation (R(2)) in HEI scores. Linear regression analyses were conducted with HEI scores as the dependent variable and all possible combinations of 16 nutrients of interest as independent variables, with covariates age, sex, and ethnicity. The analyses identified the best 1-nutrient variable model (with the highest R(2)), the best 2-nutrient variable model, and up to the best 16-nutrient variable model. The model with 8 nutrients explained 65% of the variance in HEI scores, similar to the models with 9 to 16 nutrients, but substantially higher than previous algorithms reported in the literature. The model contained five nutrients with positive β-coefficients (ie, protein, fiber, calcium, unsaturated fat, and vitamin C) and three nutrients with negative coefficients (ie, saturated fat, sodium, and added sugar). β-coefficients from the model were used as weighting factors to create an algorithm that generated a weighted nutrient density score representing the overall nutritional quality of a food. The weighted nutrient density score can be easily calculated and is useful for describing the overall nutrient quality of both foods and diets. Copyright © 2012 Academy of Nutrition and Dietetics. Published by

Nutrient Concentrations and Their Relations to the Biotic Integrity of Nonwadeable Rivers in Wisconsin

USGS Publications Warehouse

Robertson, Dale M.; Weigel, Brian M.; Graczyk, David J.

2008-01-01

Excessive nutrient [phosphorus (P) and nitrogen (N)] input from point and nonpoint sources is frequently associated with degraded water quality in streams and rivers. Point-source discharges of nutrients are fairly constant and are controlled by the U.S. Environmental Protection Agency's (USEPA) National Pollutant Discharge Elimination System. To reduce inputs from nonpoint sources, agricultural performance standards and regulations for croplands and livestock operations are being proposed by various States. In addition, the USEPA is establishing regionally based nutrient criteria that can be refined by each State to determine whether actions are needed to improve water quality. More confidence in the environmental benefits of the proposed performance standards and nutrient criteria would be possible with improved understanding of the biotic responses to a range of nutrient concentrations in different environmental settings. To achieve this general goal, the U.S. Geological Survey and the Wisconsin Department of Natural Resources collected data from 282 streams and rivers throughout Wisconsin during 2001 through 2003 to: (1) describe how nutrient concentrations and biotic-community structure differ throughout the State, (2) determine which environmental characteristics are most strongly related to the distribution of nutrient concentrations and biotic-community structure, (3) determine reference conditions for water quality and biotic indices for streams and rivers in the State, (4) determine how the biotic communities in streams and rivers in different areas of the State respond to differences in nutrient concentrations, (5) determine the best regionalization scheme to describe the patterns in reference conditions and the corresponding responses in water quality and the biotic communities (primarily for smaller streams), and (6) develop algorithms to estimate nutrient concentrations in streams and rivers from a combination of biotic indices. The ultimate goal of

Research to Inform Nutrient Thresholds and Prioritization of Watersheds for Nutrient Management

EPA Science Inventory

The information in this presentation focuses on SSWR's 4.02 project, which will advance the science needed to inform decisions to prioritize watersheds and nutrient sources for nutrient management and define appropriate nutrient levels for the nation’s waters, two importan...

Responses of spinach to salinity and nutrient deficiency in growth, physiology and nutritional value

USDA-ARS?s Scientific Manuscript database

Salinity and nutrient depleted soil are major constraints to crop production, especially for vegetable crops. The effects of salinity and nutrient deficiency on spinach were evaluated in sand cultures under greenhouse conditions. Plants were watered every day with Hoagland nutrition solution, depriv...

Biomass and nutrient allocation strategies in a desert ecosystem in the Hexi Corridor, northwest China.

PubMed

Zhang, Ke; Su, YongZhong; Yang, Rong

2017-07-01

The allocation of biomass and nutrients in plants is a crucial factor in understanding the process of plant structures and dynamics to different environmental conditions. In this study, we present a comprehensive scaling analysis of data from a desert ecosystem to determine biomass and nutrient (carbon (C), nitrogen (N), and phosphorus (P)) allocation strategies of desert plants from 40 sites in the Hexi Corridor. We found that the biomass and levels of C, N, and P storage were higher in shoots than in roots. Roots biomass and nutrient storage were concentrated at a soil depth of 0-30 cm. Scaling relationships of biomass, C storage, and P storage between shoots and roots were isometric, but that of N storage was allometric. Results of a redundancy analysis (RDA) showed that soil nutrient densities were the primary factors influencing biomass and nutrient allocation, accounting for 94.5% of the explained proportion. However, mean annual precipitation was the primary factor influencing the roots biomass/shoots biomass (R/S) ratio. Furthermore, Pearson's correlations and regression analyses demonstrated that although the biomass and nutrients that associated with functional traits primarily depended on soil conditions, mean annual precipitation and mean annual temperature had greater effects on roots biomass and nutrient storage.

Nutrient management

USDA-ARS?s Scientific Manuscript database

Nutrient management has been defined as “the science and art directed to link soil, crop, weather and hydrologic factors with cultural, irrigation and soil and water conservation practices to achieve the goals of optimizing nutrient use efficiency, yields, crop quality, and economic returns, while r...

Diagnosing oceanic nutrient deficiency

PubMed Central

2016-01-01

The supply of a range of nutrient elements to surface waters is an important driver of oceanic production and the subsequent linked cycling of the nutrients and carbon. Relative deficiencies of different nutrients with respect to biological requirements, within both surface and internal water masses, can be both a key indicator and driver of the potential for these nutrients to become limiting for the production of new organic material in the upper ocean. The availability of high-quality, full-depth and global-scale datasets on the concentrations of a wide range of both macro- and micro-nutrients produced through the international GEOTRACES programme provides the potential for estimation of multi-element deficiencies at unprecedented scales. Resultant coherent large-scale patterns in diagnosed deficiency can be linked to the interacting physical–chemical–biological processes which drive upper ocean nutrient biogeochemistry. Calculations of ranked deficiencies across multiple elements further highlight important remaining uncertainties in the stoichiometric plasticity of nutrient ratios within oceanic microbial systems and caveats with regards to linkages to upper ocean nutrient limitation. This article is part of the themed issue ‘Biological and climatic impacts of ocean trace element chemistry’. PMID:29035255

Diagnosing oceanic nutrient deficiency

NASA Astrophysics Data System (ADS)

Moore, C. Mark

2016-11-01

The supply of a range of nutrient elements to surface waters is an important driver of oceanic production and the subsequent linked cycling of the nutrients and carbon. Relative deficiencies of different nutrients with respect to biological requirements, within both surface and internal water masses, can be both a key indicator and driver of the potential for these nutrients to become limiting for the production of new organic material in the upper ocean. The availability of high-quality, full-depth and global-scale datasets on the concentrations of a wide range of both macro- and micro-nutrients produced through the international GEOTRACES programme provides the potential for estimation of multi-element deficiencies at unprecedented scales. Resultant coherent large-scale patterns in diagnosed deficiency can be linked to the interacting physical-chemical-biological processes which drive upper ocean nutrient biogeochemistry. Calculations of ranked deficiencies across multiple elements further highlight important remaining uncertainties in the stoichiometric plasticity of nutrient ratios within oceanic microbial systems and caveats with regards to linkages to upper ocean nutrient limitation. This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'.

Linking environmental nutrient enrichment and disease emergence in humans and wildlife

PubMed Central

Johnson, Pieter T. J.; Townsend, Alan R.; Cleveland, Cory C.; Glibert, Patricia M.; Howarth, Robert W.; McKenzie, Valerie J.; Rejmankova, Eliska; Ward, Mary H.

2009-01-01

Worldwide increases in the numbers of human and wildlife diseases present ecologists with the challenge of understanding how large-scale environmental changes affect host-parasite interactions. One of the most profound changes to Earth’s ecosystems is the alteration of global nutrient cycles, including those of phosphorus (P) and especially nitrogen (N). Alongside the obvious direct benefits of nutrient application for food production, growing evidence suggests that anthropogenic inputs of N and P can indirectly affect the abundance of infectious and noninfectious pathogens, sometimes leading to epidemic conditions. However, the mechanisms underpinning observed correlations, and how such patterns vary with disease type, have long remained conjectural. Here, we discuss recent experimental advances in this area to critically evaluate the relationship between environmental nutrient enrichment and disease. Given the inter-related nature of human and wildlife disease emergence, we include a broad range of human and wildlife examples from terrestrial, marine and freshwater ecosystems. We examine the consequences of nutrient pollution on directly transmitted, vector-borne, complex life cycle, and noninfectious pathogens, including West Nile virus, malaria, harmful algal blooms, coral reef diseases and amphibian malformations. Our synthetic examination suggests that the effects of environmental nutrient enrichment on disease are complex and multifaceted, varying with the type of pathogen, host species and condition, attributes of the ecosystem and the degree of enrichment; some pathogens increase in abundance whereas others decline or disappear. Nevertheless, available evidence indicates that ecological changes associated with nutrient enrichment often exacerbate infection and disease caused by generalist parasites with direct or simple life cycles. Observed mechanisms include changes in host/vector density, host distribution, infection resistance, pathogen virulence or

An investigation of siderophore production by oceanic Synechococcus

NASA Astrophysics Data System (ADS)

Wisniewski, R. J.; Webb, E. A.; Moffett, J. W.

2003-04-01

Cyanobacteria are significant contributors to global primary production. They can be found in warm high-nutrient, low-chlorophyll regions where low concentrations of iron are thought to limit primary productivity. Determining how these organisms obtain iron is critical to understanding the biogeochemical cycle of iron and its role as a determinant of marine primary production. Siderophore production has been observed in halotolerant freshwater cyanobacteria (see C.G. Trick and co-authors) and marine heterotrophic bacteria (see A. Butler, M.G. Haygood and co-authors), but to date, siderophore production in truly marine cyanobacteria has not been demonstrated. We examined the response of two marine Synechococcus species (WH7803 and WH8102) to iron stress. Axenic cultures of both Synechococcus species were grown under iron-stressed and iron-replete conditions. The supernatants of these cultures were examined using competitive ligand exchange-cathodic stripping voltammetry (CLE-CSV), a sensitive method of quantitative ligand detection. Observing ligand accumulation in culture is an analytical challenge due to the low cell densities and reduced growth rates of iron stressed marine cyanobacteria. Preliminary results suggest the presence of an iron-binding ligand in the iron-stressed cultures which was not present under iron-replete conditions. The amount of ligand produced by Synechococcus was approximately 1 × 10-18 mol/cell, comparable with the amount produced by marine heterotrophic bacteria (K. Barbeau, pers. comm.).

Role of Sediments and Nutrients in the Condition of a Coral Reef Under Tourist Pressure: Akumal México.

NASA Astrophysics Data System (ADS)

Naranjo-Garcia, M. J.; Vadés Lozano, D. S.; Real-De-Leon, E.; Lopez-Aguiar, K.; Garza-Perez, J. R.

2014-12-01

Akumal, Mexico, was the first tourist resort in the Mexican Caribbean mainland, its highly developed coastal zone lies directly above the phreatic, and it is directly connected to the sub-littoral waters. Akumal is also known as a well-developed fringing coral reef, now in a critical condition. The main objective of this study was to explore the relationship between two of the main indicators of human pressure (nutrients and sedimentation, linked to coastal development and water run-offs) and the condition of the reef benthos, during a year. The sampling design used four transects perpendicular to shore, associated to different tourist and water run-off exposure, for a total of 12 stations distributed in three different reef zones (transition zone, shallow and deep spurs and grooves). Monthly samples were collected: water samples close to the reef lagoon drain channels and at bottom depth at each station, and sediment traps were recovered and replaced also at each station. Reef Benthos videotransects were recorded bi-monthly at each station to assess its condition. Macroalgae and filamentous algae dominate benthic cover (up to 50%), hard-coral cover ranges from 5-9%. Five coral-diseases were recorded, affecting 10.16% of the coral colonies: Caribbean Ciliate Infection, White Band, Purple Spots, White Spots and Yellow Band. The sedimentation rate -sr- ranged from 0.13 to 83.7 mg/cm2/day during the year; 86% of the samples had a sr ≤ 10 mg/cm2/day (reefs not stressed); 13% of the samples had a sr ranging from 10 to 50 mg/cm2/day (stressed reefs); and 1% of the samples were over the critical threshold (>50 mg/cm2/day). Dissolved Inorganic Nitrogen concentrations during the year were above those recorded previously in Caribbean reefs. The most abundant fraction was ammonium, surpassing both Mexican norms: For protection of aquatic life in coastal zones (0.01 mg/L), and the critical threshold for aquatic life (0.4 mg/L). These concentration limits are considered as

The role of aquatic fungi in transformations of organic matter mediated by nutrients

Treesearch

Cynthia J. Tant; Amy D. Rosemond; Andrew S. Mehring; Kevin A. Kuehn; John M. Davis

2015-01-01

1. We assessed the key role of aquatic fungi in modifying coarse particulate organic matter (CPOM) by affecting its breakdown rate, nutrient concentration and conversion to fine particulate organic matter (FPOM). Overall, we hypothesised that fungal-mediated conditioning and breakdown of CPOM would be accelerated when nutrient concentrations are increased and tested...

Impact of Salt and Nutrient Content on Biofilm Formation by Vibrio fischeri.

PubMed

Marsden, Anne E; Grudzinski, Kevin; Ondrey, Jakob M; DeLoney-Marino, Cindy R; Visick, Karen L

2017-01-01

Vibrio fischeri, a marine bacterium and symbiont of the Hawaiian bobtail squid Euprymna scolopes, depends on biofilm formation for successful colonization of the squid's symbiotic light organ. Here, we investigated if culture conditions, such as nutrient and salt availability, affect biofilm formation by V. fischeri by testing the formation of wrinkled colonies on solid media. We found that V. fischeri forms colonies with more substantial wrinkling when grown on the nutrient-dense LBS medium containing NaCl relative to those formed on the more nutrient-poor, seawater-salt containing SWT medium. The presence of both tryptone and yeast extract was necessary for the production of "normal" wrinkled colonies; when grown on tryptone alone, the colonies displayed a divoting phenotype and were attached to the agar surface. We also found that the type and concentration of specific seawater salts influenced the timing of biofilm formation. Of the conditions assayed, wrinkled colony formation occurred earliest in LBS(-Tris) media containing 425 mM NaCl, 35 mM MgSO4, and 5 mM CaCl2. Pellicle formation, another measure of biofilm development, was also enhanced in these growth conditions. Therefore, both nutrient and salt availability contribute to V. fischeri biofilm formation. While growth was unaffected, these optimized conditions resulted in increased syp locus expression as measured by a PsypA-lacZ transcriptional reporter. We anticipate these studies will help us understand how the natural environment of V. fischeri affects its ability to form biofilms and, ultimately, colonize E. scolopes.

Zinc: an essential but elusive nutrient123

PubMed Central

King, Janet C

2011-01-01

Zinc is essential for multiple aspects of metabolism. Physiologic signs of zinc depletion are linked with diverse biochemical functions rather than with a specific function, which makes it difficult to identify biomarkers of zinc nutrition. Nutrients, such as zinc, that are required for general metabolism are called type 2 nutrients. Protein and magnesium are examples of other type 2 nutrients. Type 1 nutrients are required for one or more specific functions: examples include iron, vitamin A, iodine, folate, and copper. When dietary zinc is insufficient, a marked reduction in endogenous zinc loss occurs immediately to conserve the nutrient. If zinc balance is not reestablished, other metabolic adjustments occur to mobilize zinc from small body pools. The location of those pools is not known, but all cells probably have a small zinc reserve that includes zinc bound to metallothionein or zinc stored in the Golgi or in other organelles. Plasma zinc is also part of this small zinc pool that is vulnerable to insufficient intakes. Plasma zinc concentrations decline rapidly with severe deficiencies and more moderately with marginal depletion. Unfortunately, plasma zinc concentrations also decrease with a number of conditions (eg, infection, trauma, stress, steroid use, after a meal) due to a metabolic redistribution of zinc from the plasma to the tissues. This redistribution confounds the interpretation of low plasma zinc concentrations. Biomarkers of metabolic zinc redistribution are needed to determine whether this redistribution is the cause of a low plasma zinc rather than poor nutrition. Measures of metallothionein or cellular zinc transporters may fulfill that role. PMID:21715515

Limited impact of ocean acidification on phytoplankton community structure and carbon export in an oligotrophic environment: Results from two short-term mesocosm studies in the Mediterranean Sea

NASA Astrophysics Data System (ADS)

Gazeau, F.; Sallon, A.; Pitta, P.; Tsiola, A.; Maugendre, L.; Giani, M.; Celussi, M.; Pedrotti, M. L.; Marro, S.; Guieu, C.

2017-02-01

Modifications in the strength of the biological pump as a consequence of ocean acidification, whether positive or negative, have the potential to impact atmospheric CO2 and therefore climate. So far, most plankton community perturbation studies have been performed in nutrient-rich areas although there are some indications that CO2-dependent growth could differ in nutrient-replete vs. -limited regions and with different community compositions. Two in situ mesocosm experiments were performed in the NW Mediterranean Sea during two seasons with contrasted environmental conditions: summer oligotrophic stratified waters in the Bay of Calvi vs. winter mesotrophic well-mixed waters in the Bay of Villefranche. Nine mesocosms were deployed for 20 and 12 d, respectively, and subjected to seven CO2 levels (3 controls, 6 elevated levels). Both phytoplankton assemblages were dominated by pico- and nano-phytoplankton cells. Although haptophyceae and dinoflagellates benefited from short-term CO2 enrichment in summer, their response remained small with no consequences on organic matter export due to strong environmental constraints (nutrient availability). In winter, most of the plankton growth and associated nutrient consumption occurred during the 4-day acidification period (before the experimental phase). During the remaining experimental period, characterized by low nutrient availability, plankton growth was minimal and no clear CO2-dependency was found for any of the tested parameters. While there is a strong confidence on the absence of significant effect of short-term CO2 addition under oligotrophic conditions, more investigations are needed to assess the response of plankton communities in winter when vertical mixing and weather conditions are major factors controlling plankton dynamics.

Numerical simulations of river discharges, nutrient flux and nutrient dispersal in Jakarta Bay, Indonesia.

PubMed

van der Wulp, Simon A; Damar, Ario; Ladwig, Norbert; Hesse, Karl-J

2016-09-30

The present application of numerical modelling techniques provides an overview of river discharges, nutrient flux and nutrient dispersal in Jakarta Bay. A hydrological model simulated river discharges with a total of 90 to 377m(3)s(-1) entering Jakarta Bay. Daily total nitrogen and total phosphorus loads ranged from 40 to 174tons and 14 to 60tons, respectively. Flow model results indicate that nutrient gradients are subject to turbulent mixing by tides and advective transport through circulation driven by wind, barotropic and baroclinic pressure gradients. The bulk of nutrient loads originate from the Citarum and Cisadane rivers flowing through predominantly rural areas. Despite lower nutrient loads, river discharges from the urban area of Jakarta exhibit the highest impact of nutrient concentrations in the near shore area of Jakarta Bay and show that nutrient concentrations were not only regulated by nutrient loads but were strongly regulated by initial river concentrations and local flow characteristics. Copyright © 2016 Elsevier Ltd. All rights reserved.

Harmonization of nutrient intake values.

PubMed

King, Janet C; Garza, Cutberto

2007-03-01

The conceptual framework for the various NIVs is depicted in figure 1 along with the methodological approaches and applications. The NIVs consist of two values derived from a statistical evaluation of data on nutrient requirements, the average nutrient requirement (ANR), or nutrient toxicities, the upper nutrient level (UNL). The individual nutrient levelx (INLx) is derived from the distribution of average nutrient requirements. The percentile chosen is often 98%, which is equivalent to 2 SD above the mean requirement. Concepts underlying the NIVs include criteria for establishing a nutrient requirement, e.g., ferritin stores, nitrogen balance, or serum vitamin C. Once the requirement for the absorbed nutrient is determined, it may be necessary to adjust the value for food sources, i.e., bioavailability, or host factors, such as the effect of infection on nutrient utilization. Other concepts that committees may want to consider when establishing NIVs include the effects of genetic variation on nutrient requirements and the role of the nutrient in preventing long-term disease. Two fundamental uses of NIVs are for assessing the adequacy of nutrient intakes and for planning diets for individuals and populations. Establishing the NIV using the statistical framework proposed in this report improves the efficacy of the values for identifying risks of nutrient deficiency or excess among individuals and populations. NIVs also are applied to a number of aspects of food and nutrition policy. Some examples include regulatory issues and trade, labeling, planning programs for alleviating public health nutrition problems, food fortification, and dietary guidance.

Thermally Induced Encapsulation of Food Nutrients into Phytoferritin through the Flexible Channels without Additives.

PubMed

Yang, Rui; Tian, Jing; Liu, Yuqian; Yang, Zhiying; Wu, Dandan; Zhou, Zhongkai

2017-11-22

The cavity of phytoferritin provides a nanospace to encapsulate and deliver food nutrient molecules. However, tranditional methods to prepare the ferritin-nutrient complexes must undergo acid/alkaline conditions or apply additives. In this work, we provide a novel guideline that thermal treatment at 60 °C can expand ferritin channels by uncoiling the surrounding α-helix. Upon reduction of the temperature to 20 °C, food nutrient rutin can be encapsulated in apo-soybean seed ferritin (apoSSF) at pH 7.0 through channels without disassembly of the protein cage and with no addition of additives. Results indicated that one apoSSF could encapsulate about 10.5 molecules of rutin, with an encapsulation ratio of 8.08% (w/w). In addition, the resulting rutin-loaded SSF complexes were monodispersed in a size of 12 nm in aqueous solution. This work provides a novel pathway for the encapsulation of food nutrient molecules into the nanocavity of ferritin under a neutral pH condition induced by thermal treatment.

Parent's responses to nutrient claims and sports celebrity endorsements on energy-dense and nutrient-poor foods: an experimental study.

PubMed

Dixon, Helen; Scully, Maree; Wakefield, Melanie; Kelly, Bridget; Chapman, Kathy; Donovan, Robert

2011-06-01

To assess parents' responses to common, potentially misleading strategies for marketing energy-dense and nutrient-poor (EDNP) child-oriented foods. Between-subjects online experiment to test whether nutrient claims and sports celebrity endorsements on the front of packs of EDNP products lead parents to prefer and rate these foods more favourably. Australia. A total of 1551 parents of children aged 5-12 years, who were the main household grocery buyers. Inclusion of nutrient claims or sports celebrity endorsements on EDNP products led parents to perceive these products to be more nutritious than if they did not include such promotions. When asked to choose between a pair of different products (EDNP v. healthier), 56 % of parents did not read a nutrition information panel (NIP) before making their choice and this did not differ by promotion condition. These parents were more likely to choose an EDNP product if it included a nutrient claim (OR = 1.83, 95 % CI 1.31, 2.56; P < 0.001) or sports celebrity endorsement (OR = 2.37, 95 % CI 1.70, 3.32; P < 0.001). Sports celebrity endorsements also enhanced parent's perceptions of typical consumers of the product, perceptions of product healthiness and quality, as well as purchase intentions. Nutrient claims and sports celebrity endorsements tip consumer preferences towards EDNP products bearing such promotions, especially among the majority who do not read the NIP. As parents largely determine what foods are available to children at home, it is critical that initiatives aimed at reducing the persuasive impact of food marketing include this target group.

Clonal foraging in perennial wheatgrasses: A strategy for exploiting patchy soil nutrients

USGS Publications Warehouse

Humphrey, L. David; Pyke, David A.

1997-01-01

1. Foraging by means of plasticity in placement of tillers in response to low- and high-nutrient patches was examined in the rhizomatous wheatgrass Elymus lanceolatus ssp. lanceolatus. Its ability to exploit soil nutrient patches was compared to that of the closely related but caespitose E. lanceolatus ssp. wawawaiensis.2. Clones of 14 genets of each taxon were planted in boxes consisting of two 30 × 30 cm cells: the `origin cell' where clones were planted, and the adjacent `destination cell', with each cell containing soil with either low or high levels of nutrients.3. The rhizomatous taxon, which can produce intravaginal, short-rhizome and long-rhizome tillers, preferentially produced short-rhizome and intravaginal tillers in high-nutrient destination cells. Effects of nutrient status of the origin cell as well as of the destination cell on total tiller numbers indicated clonal integration, yet tiller placement responded to local conditions.4. Roots of both taxa accessed nutrients in destination cells (the caespitose subspecies by root growth only), and above-ground biomass of both taxa increased to a similar extent with high-nutrient destination cells. With the patch sizes used in this experiment, root growth was as important as ramet placement in exploiting nutrients in destination cells. 5 There was no relationship between degree of plasticity in ramet placement and biomass of the clone when high-nutrient destination cells were present.

Herbivores and nutrients control grassland plant diversity via light limitation

USGS Publications Warehouse

Borer, Elizabeth T.; Seabloom, Eric W.; Gruner, Daniel S.; Harpole, W. Stanley; Hillebrand, Helmut; Lind, Eric M.; Alder, Peter B.; Alberti, Juan; Anderson, T. Michael; Bakker, Jonathan D.; Biederman, Lori; Blumenthal, Dana; Brown, Cynthia S.; Brudvig, Lars A.; Buckley, Yvonne M.; Cadotte, Marc; Chu, Cheng-Jin; Cleland, Elsa E.; Crawley, Michael J.; Daleo, Pedro; Damschen, Ellen Ingman; Davies, Kendi F.; DeCrappeo, Nicole M.; Du, Guozhen; Firn, Jennifer; Hautier, Yann; Heckman, Robert W.; Hector, Andy; HilleRisLambers, Janneke; Iribarne, Oscar; Klein, Julia A.; Knops, Johannes M.H.; La Pierre, Kimberly J.; Leakey, Andrew D.B.; Li, Wei; MacDougall, Andrew S.; McCulley, Rebecca L.; Melbourne, Brett A.; Mitchell, Charles E.; Moore, Joslin L.; Mortensen, Brent; O'Halloran, Lydia R.; Orrock, John L.; Pascual, Jesús; Prober, Suzanne M.; Pyke, David A.; Risch, Anita C.; Schuetz, Martin; Smith, Melinda D.; Stevens, Carly J.; Sullivan, Lauren L.; Williams, Ryan J.; Wragg, Peter D.; Wright, Justin P.; Yang, Louie H.

2014-01-01

Human alterations to nutrient cycles and herbivore communities are affecting global biodiversity dramatically. Ecological theory predicts these changes should be strongly counteractive: nutrient addition drives plant species loss through intensified competition for light, whereas herbivores prevent competitive exclusion by increasing ground-level light, particularly in productive systems. Here we use experimental data spanning a globally relevant range of conditions to test the hypothesis that herbaceous plant species losses caused by eutrophication may be offset by increased light availability due to herbivory. This experiment, replicated in 40 grasslands on 6 continents, demonstrates that nutrients and herbivores can serve as counteracting forces to control local plant diversity through light limitation, independent of site productivity, soil nitrogen, herbivore type and climate. Nutrient addition consistently reduced local diversity through light limitation, and herbivory rescued diversity at sites where it alleviated light limitation. Thus, species loss from anthropogenic eutrophication can be ameliorated in grasslands where herbivory increases ground-level light.

Herbivores and nutrients control grassland plant diversity via light limitation.

PubMed

Borer, Elizabeth T; Seabloom, Eric W; Gruner, Daniel S; Harpole, W Stanley; Hillebrand, Helmut; Lind, Eric M; Adler, Peter B; Alberti, Juan; Anderson, T Michael; Bakker, Jonathan D; Biederman, Lori; Blumenthal, Dana; Brown, Cynthia S; Brudvig, Lars A; Buckley, Yvonne M; Cadotte, Marc; Chu, Chengjin; Cleland, Elsa E; Crawley, Michael J; Daleo, Pedro; Damschen, Ellen I; Davies, Kendi F; DeCrappeo, Nicole M; Du, Guozhen; Firn, Jennifer; Hautier, Yann; Heckman, Robert W; Hector, Andy; HilleRisLambers, Janneke; Iribarne, Oscar; Klein, Julia A; Knops, Johannes M H; La Pierre, Kimberly J; Leakey, Andrew D B; Li, Wei; MacDougall, Andrew S; McCulley, Rebecca L; Melbourne, Brett A; Mitchell, Charles E; Moore, Joslin L; Mortensen, Brent; O'Halloran, Lydia R; Orrock, John L; Pascual, Jesús; Prober, Suzanne M; Pyke, David A; Risch, Anita C; Schuetz, Martin; Smith, Melinda D; Stevens, Carly J; Sullivan, Lauren L; Williams, Ryan J; Wragg, Peter D; Wright, Justin P; Yang, Louie H

2014-04-24

Human alterations to nutrient cycles and herbivore communities are affecting global biodiversity dramatically. Ecological theory predicts these changes should be strongly counteractive: nutrient addition drives plant species loss through intensified competition for light, whereas herbivores prevent competitive exclusion by increasing ground-level light, particularly in productive systems. Here we use experimental data spanning a globally relevant range of conditions to test the hypothesis that herbaceous plant species losses caused by eutrophication may be offset by increased light availability due to herbivory. This experiment, replicated in 40 grasslands on 6 continents, demonstrates that nutrients and herbivores can serve as counteracting forces to control local plant diversity through light limitation, independent of site productivity, soil nitrogen, herbivore type and climate. Nutrient addition consistently reduced local diversity through light limitation, and herbivory rescued diversity at sites where it alleviated light limitation. Thus, species loss from anthropogenic eutrophication can be ameliorated in grasslands where herbivory increases ground-level light.

Development of methods for establishing nutrient criteria in lakes and reservoirs: A review.

PubMed

Huo, Shouliang; Ma, Chunzi; Xi, Beidou; Zhang, Yali; Wu, Fengchang; Liu, Hongliang

2018-05-01

Nutrient criteria provide a scientific foundation for the comprehensive evaluation, prevention, control and management of water eutrophication. In this review, the literature was examined to systematically evaluate the benefits, drawbacks, and applications of statistical analysis, paleolimnological reconstruction, stressor-response model, and model inference approaches for nutrient criteria determination. The developments and challenges in the determination of nutrient criteria in lakes and reservoirs are presented. Reference lakes can reflect the original states of lakes, but reference sites are often unavailable. Using the paleolimnological reconstruction method, it is often difficult to reconstruct the historical nutrient conditions of shallow lakes in which the sediments are easily disturbed. The model inference approach requires sufficient data to identify the appropriate equations and characterize a waterbody or group of waterbodies, thereby increasing the difficulty of establishing nutrient criteria. The stressor-response model is a potential development direction for nutrient criteria determination, and the mechanisms of stressor-response models should be studied further. Based on studies of the relationships among water ecological criteria, eutrophication, nutrient criteria and plankton, methods for determining nutrient criteria should be closely integrated with water management requirements. Copyright © 2017. Published by Elsevier B.V.

Plant Growth Environments with Programmable Relative Humidity and Homogeneous Nutrient Availability

PubMed Central

Lind, Kara R.; Lee, Nigel; Sizmur, Tom; Siemianowski, Oskar; Van Bruggen, Shawn; Ganapathysubramaniam, Baskar

2016-01-01

We describe the design, characterization, and use of “programmable”, sterile growth environments for individual (or small sets of) plants. The specific relative humidities and nutrient availability experienced by the plant is established (RH between 15% and 95%; nutrient concentration as desired) during the setup of the growth environment, which takes about 5 minutes and <1$ in disposable cost. These systems maintain these environmental parameters constant for at least 14 days with minimal intervention (one minute every two days). The design is composed entirely of off-the-shelf components (e.g., LEGO® bricks) and is characterized by (i) a separation of root and shoot environment (which is physiologically relevant and facilitates imposing specific conditions on the root system, e.g., darkness), (ii) the development of the root system on a flat surface, where the root enjoys constant contact with nutrient solution and air, (iii) a compatibility with root phenotyping. We demonstrate phenotyping by characterizing root systems of Brassica rapa plants growing in different relative humidities (55%, 75%, and 95%). While most phenotypes were found to be sensitive to these environmental changes, a phenotype tightly associated with root system topology–the size distribution of the areas encircled by roots–appeared to be remarkably and counterintuitively insensitive to humidity changes. These setups combine many of the advantages of hydroponics conditions (e.g., root phenotyping, complete control over nutrient composition, scalability) and soil conditions (e.g., aeration of roots, shading of roots), while being comparable in cost and setup time to Magenta® boxes. PMID:27304431

Drug-nutrient interactions: a review.

PubMed

Maka, D A; Murphy, L K

2000-11-01

Concurrent administration of medications and nutrients can lead to interactions that change the absorption or metabolism of the medication or nutrient. Some of these interactions have little or no impact on the patient while others may be fatal. The objective of this article is to review the mechanisms of various drug-nutrient interactions. Topics to be discussed include specific populations at risk of interactions, nutrients that have a positive and negative effect on drug absorption, nutrients that result in alterations of drug metabolism, and a variety of pharmacologic interactions of medications with nutrients. It is vital that healthcare providers are familiar with drug-nutrient interactions and continue to educate themselves and their patients to optimize the effectiveness and minimize the toxicities of medications.

Chlorophyll fluorescence as a tool for nutrient status identification in rapeseed plants.

PubMed

Kalaji, Hazem M; Bąba, Wojciech; Gediga, Krzysztof; Goltsev, Vasilij; Samborska, Izabela A; Cetner, Magdalena D; Dimitrova, Stella; Piszcz, Urszula; Bielecki, Krzysztof; Karmowska, Kamila; Dankov, Kolyo; Kompała-Bąba, Agnieszka

2018-06-01

In natural conditions, plants growth and development depends on environmental conditions, including the availability of micro- and macroelements in the soil. Nutrient status should thus be examined not by establishing the effects of single nutrient deficiencies on the physiological state of the plant but by combinations of them. Differences in the nutrient content significantly affect the photochemical process of photosynthesis therefore playing a crucial role in plants growth and development. In this work, an attempt was made to find a connection between element content in (i) different soils, (ii) plant leaves, grown on these soils and (iii) changes in selected chlorophyll a fluorescence parameters, in order to find a method for early detection of plant stress resulting from the combination of nutrient status in natural conditions. To achieve this goal, a mathematical procedure was used which combines principal component analysis (a tool for the reduction of data complexity), hierarchical k-means (a classification method) and a machine-learning method-super-organising maps. Differences in the mineral content of soil and plant leaves resulted in functional changes in the photosynthetic machinery that can be measured by chlorophyll a fluorescent signals. Five groups of patterns in the chlorophyll fluorescent parameters were established: the 'no deficiency', Fe-specific deficiency, slight, moderate and strong deficiency. Unfavourable development in groups with nutrient deficiency of any kind was reflected by a strong increase in F o and ΔV/Δt 0 and decline in φ Po , φ Eo δ Ro and φ Ro . The strong deficiency group showed the suboptimal development of the photosynthetic machinery, which affects both PSII and PSI. The nutrient-deficient groups also differed in antenna complex organisation. Thus, our work suggests that the chlorophyll fluorescent method combined with machine-learning methods can be highly informative and in some cases, it can replace much more

PREDICTING PRESENCE OF NUTRIENTS AND PESTICIDES IN BASE FLOW CONDITIONS OF FIRST ORDER STREAMS IN THE MID-ATLANTIC COASTAL PLAIN

EPA Science Inventory

Excess nutrients and pesticides in the environment can cause a variety of ecological and human-health effects. When nutrients are unused by plants, or pesticides remain after use on their intended target, these compounds can be transported to streams, either directly through over...

Contributions to the Nutrient Toolbox: Identifying Drivers, Nutrient Sources, and Attribution of Exceedances

EPA Science Inventory

Nutrients are a leading cause of impairments in the United States, and as a result tools are needed to identify drivers of nutrients and response variables (such as chlorophyll a), nutrient sources, and identify causes of exceedances of water quality thresholds. This presentatio...

A nutrient dependant switch explains mutually exclusive existence of meiosis and mitosis initiation in budding yeast.

PubMed

Wannige, C T; Kulasiri, D; Samarasinghe, S

2014-01-21

Nutrients from living environment are vital for the survival and growth of any organism. Budding yeast diploid cells decide to grow by mitosis type cell division or decide to create unique, stress resistant spores by meiosis type cell division depending on the available nutrient conditions. To gain a molecular systems level understanding of the nutrient dependant switching between meiosis and mitosis initiation in diploid cells of budding yeast, we develop a theoretical model based on ordinary differential equations (ODEs) including the mitosis initiator and its relations to budding yeast meiosis initiation network. Our model accurately and qualitatively predicts the experimentally revealed temporal variations of related proteins under different nutrient conditions as well as the diverse mutant studies related to meiosis and mitosis initiation. Using this model, we show how the meiosis and mitosis initiators form an all-or-none type bistable switch in response to available nutrient level (mainly nitrogen). The transitions to and from meiosis or mitosis initiation states occur via saddle node bifurcation. This bidirectional switch helps the optimal usage of available nutrients and explains the mutually exclusive existence of meiosis and mitosis pathways. © 2013 Elsevier Ltd. All rights reserved.

[Effects nutrients on the seedlings root hair development and root growth of Poncirus trifoliata under hydroponics condition].

PubMed

Cao, Xiu; Xia, Ren-Xue; Zhang, De-Jian; Shu, Bo

2013-06-01

Ahydroponics experiment was conducted to study the effects of nutrients (N, P, K, Ca, Mg, Fe, and Mn) deficiency on the length of primary root, the number of lateral roots, and the root hair density, length, and diameter on the primary root and lateral roots of Poncirus trifoliata seedlings. Under the deficiency of each test nutrient, root hair could generate, but was mainly concentrated on the root base and fewer on the root tip. The root hair density on lateral roots was significantly larger than that on primary root, but the root hair length was in adverse. The deficiency of each test nutrient had greater effects on the growth and development of root hairs, with the root hair density on primary root varied from 55.0 to 174.3 mm(-2). As compared with the control, Ca deficiency induced the significant increase of root hair density and length on primary root, P deficiency promoted the root hair density and length on the base and middle part of primary root and on the lateral roots significantly, Fe deficiency increased the root hair density but decreased the root hair length on the tip of primary root significantly, K deficiency significantly decreased the root hair density, length, and diameter on primary root and lateral roots, whereas Mg deficiency increased the root hair length of primary root significantly. In all treatments of nutrient deficiency, the primary root had the similar growth rate, but, with the exceptions of N and Mg deficiency, the lateral roots exhibited shedding and regeneration.

Effect of Temperature and Nutrient Manipulations on eelgrass ...

EPA Pesticide Factsheets

Global climate change will have a large impact on the three predominate drivers of estuarine seagrass productivity, temperature, light and nutrients. I experimentally evaluate the response of Pacific Northwest Z. marina to interactive effects of temperature and nutrient conditions. Experimental manipulations were conducted hydroponically in acrylic chambers and spanned a range of temperatures and nutrient concentrations. Preliminary single factor experiments were conducted to evaluate physiological tolerances to temperature and nitrogen concentrations. Eelgrass exhibited a linear increase in specific growth with increasing NH4 concentration (range from 10 to 1000 µM); in contrast, there was no significant relationship between specific growth rate and increasing NO3 concentration over the same concentration range. Leaf growth metrics all exhibited strong linear relationships with increasing water temperature (temperature range 4-25 ºC). In the factorial experiment, plants were exposed to 3 temperatures (10, 18 and 25 ºC) and 3 nitrate concentrations (10, 30 and 100 µM) with 3 replicate chambers per treatment combination. Most metrics (leaf elongation, growth, specific growth, wasting index) exhibited a significant temperature effect indicating the importance of temperature on metabolic rates. Tissue stable isotope ratios and C:N values exhibited a significant nutrient effect and in some cases a significant temperature effect. Whole plant non structur

Nutrient depletion modifies cell wall adsorption activity of wine yeast.

PubMed

Sidari, R; Caridi, A

2016-06-01

Yeast cell wall is a structure that helps yeasts to manage and respond to many environmental stresses. The mannosylphosphorylation is a modification in response to stress that provides the cell wall with negative charges able to bind compounds present in the environment. Phenotypes related to the cell wall modification such as the filamentous growth in Saccharomyces cerevisiae are affected by nutrient depletion. The present work aimed at describing the effect of carbon and/or nitrogen limitation on the aptitude of S. cerevisiae strains to bind coloured polyphenols. Carbon- and nitrogen-rich or deficient media supplemented with grape polyphenols were used to simulate different grape juice conditions-early, mid, 'adjusted' for nitrogen, and late fermentations. In early fermentation condition, the R+G+B values range from 106 (high adsorption, strain Sc1128) to 192 (low adsorption, strain Σ1278b), in mid-fermentation the values range from 111 (high adsorption, strain Sc1321) to 258 (low adsorption, strain Sc2306), in 'adjusted' for nitrogen conditions the values range from 105 (high adsorption, strain Sc1321) to 194 (low adsorption, strain Sc2306) while in late fermentation conditions the values range from 101 (high adsorption, strain Sc384) to 293 (low adsorption, strain Sc2306). The effect of nutrient availability is not univocal for all the strains and the different media tested modified the strains behaviour. In all the media the strains show significant differences. Results demonstrate that wine yeasts decrease/increase their parietal adsorption activity according to the nutrient availability. The wide range of strain variability observed could be useful in selecting wine starters.

Nutrient Density Scores.

ERIC Educational Resources Information Center

Dickinson, Annette; Thompson, William T.

1979-01-01

Announces a nutrient density food scoring system called the Index of Nutritional Quality (INQ). It expresses the ratio between the percent RDA of a nutrient and the percent daily allowance of calories in a food. (Author/SA)

Reliability analysis of nutrient removal from stormwater runoff with green sorption media under varying influent conditions.

PubMed

Jones, Jamie; Chang, Ni-Bin; Wanielista, Martin P

2015-01-01

To support nutrient removal, various stormwater treatment technologies have been developed via the use of green materials, such as sawdust, tire crumbs, sand, clay, sulfur, and limestone, as typical constituents of filter media mixes. These materials aid in the physiochemical sorption and precipitation of orthophosphates as well as in the biological transformation of ammonia, nitrates and nitrites. However, these processes are dependent upon influent conditions such as hydraulic residence time, influent orthophosphate concentrations, and other chemical species present in the inflow. This study aims to compare the physiochemical removal of orthophosphate by isotherm and column tests under differing influent conditions to realize the reliability of orthophosphate removal process with the aid of green sorption media. The green sorption media of interest in this study is composed of a 5:2:2:1 (by volume) mixture of cement sand, tire crumb, fine expanded clay, and limestone. Scenarios of manipulating the hydraulic residence time of the water from 18 min and 60 min, the influent dissolved phosphorus concentrations of 1.0 mg·L(-1) and 0.5 mg·L(-1), and influent water types of distilled and pond water, were all investigated in the column tests. Experimental data were compared with the outputs from the Thomas Model based on orthophosphate removal to shed light on the equilibrium condition versus kinetic situation. With ANOVA tests, significant differences were confirmed between the experimental data sets of the breakthrough curves in the column tests. SEM imaging analysis helps to deepen the understanding of pore structures and pore networks of meta-materials being used in the green sorption media. Life expectancy curves derived from the output of Thomas Model may be applicable for future system design of engineering processes. Copyright © 2014 Elsevier B.V. All rights reserved.

The Nutrient Density of Snacks

PubMed Central

Hess, Julie; Rao, Goutham; Slavin, Joanne

2017-01-01

Background: Although Americans receive almost a quarter of their daily energy from snacks, snacking remains a poorly defined and understood eating occasion. However, there is little dietary guidance about choosing snacks. Families, clinicians, and researchers need a comprehensive approach to assessing their nutritional value. Objective: To quantify and compare the nutrient density of commonly consumed snacks by their overall nutrient profiles using the Nutrient-Rich Foods (NRF) Index 10.3. Methods: NRF Index scores were calculated for the top 3 selling products (based on 2014 market research data) in different snack categories. These NRF scores were averaged to provide an overall nutrient-density score for each category. Results: Based on NRF scores, yogurt (55.3), milk (52.5), and fruit (30.1) emerged as the most nutrient-dense snacks. Ice cream (−4.4), pies and cakes (−11.1), and carbonated soft drinks (−17.2) emerged as the most nutrient-poor snacks. Conclusions: The NRF Index is a useful tool for assessing the overall nutritional value of snacks based on nutrients to limit and nutrients to encourage. PMID:28491924

Soluble organic nutrient fluxes

Treesearch

Robert G. Qualls; Bruce L. Haines; Wayne Swank

2014-01-01

Our objectives in this study were (i) compare fluxes of the dissolved organic nutrients dissolved organic carbon (DOC), DON, and dissolved organic phosphorus (DOP) in a clearcut area and an adjacent mature reference area. (ii) determine whether concentrations of dissolved organic nutrients or inorganic nutrients were greater in clearcut areas than in reference areas,...

Scaling Dissolved Nutrient Removal in River Networks: A Comparative Modeling Investigation

NASA Astrophysics Data System (ADS)

Ye, Sheng; Reisinger, Alexander J.; Tank, Jennifer L.; Baker, Michelle A.; Hall, Robert O.; Rosi, Emma J.; Sivapalan, Murugesu

2017-11-01

Along the river network, water, sediment, and nutrients are transported, cycled, and altered by coupled hydrological and biogeochemical processes. Our current understanding of the rates and processes controlling the cycling and removal of dissolved inorganic nutrients in river networks is limited due to a lack of empirical measurements in large, (nonwadeable), rivers. The goal of this paper was to develop a coupled hydrological and biogeochemical process model to simulate nutrient uptake at the network scale during summer base flow conditions. The model was parameterized with literature values from headwater streams, and empirical measurements made in 15 rivers with varying hydrological, biological, and topographic characteristics, to simulate nutrient uptake at the network scale. We applied the coupled model to 15 catchments describing patterns in uptake for three different solutes to determine the role of rivers in network-scale nutrient cycling. Model simulation results, constrained by empirical data, suggested that rivers contributed proportionally more to nutrient removal than headwater streams given the fraction of their length represented in a network. In addition, variability of nutrient removal patterns among catchments was varied among solutes, and as expected, was influenced by nutrient concentration and discharge. Net ammonium uptake was not significantly correlated with any environmental descriptor. In contrast, net daily nitrate removal was linked to suspended chlorophyll a (an indicator of primary producers) and land use characteristics. Finally, suspended sediment characteristics and agricultural land use were correlated with net daily removal of soluble reactive phosphorus, likely reflecting abiotic sorption dynamics. Rivers are understudied relative to streams, and our model suggests that rivers can contribute more to network-scale nutrient removal than would be expected based upon their representative fraction of network channel length.

Nutrient Status and Criteria Development for the Saint John River, Canada, Using a Weight of Evidence Approach

NASA Astrophysics Data System (ADS)

Culp, J. M.; Luiker, E. A.; Noel, L.; Curry, A. R.; Hryn, D.; Heard, K.

2005-05-01

The Saint John River is the largest in Maine/New Brunswick (673 km in length, draining 55,000 km2) with a history of natural resource use and nutrient effluent release to the watershed since the late 17th century. Our objective was to obtain a basic understanding of the contemporary nutrient conditions of the non-tidal portion of the river in relation to historical conditions, and to consider how the contemporary river is affected by point and non-point source nutrient loadings. The study included review of historical provincial and federal water quality databases dating back to the 1960s. Current water quality monitoring programs have focused on nitrogen (nitrite, nitrate, ammonia, TKN), phosphorus (total, dissolved, and soluble reactive phosphorus), DIC/DOC, and biomass of periphyton and phytoplankton. To determine nutrient limitation, nutrient diffusing substrate studies were conducted in river reaches of known nutrient enrichment. Oxygen stable isotopes were also used to provide information on the photosynthesis to respiration ratio. A weight of evidence approach combining the results of these studies was used to determine trophic status of river reaches and to highlight areas of eutrophication. From this information nutrient criteria for the Saint John River will be proposed.

Quantifying Periphyton Community Responses to Nutrients in a Southeast Coastal Plain Watershed using a Molecular Approach

EPA Science Inventory

Nutrient (nitrogen and phosphorus) pollution is a water quality issue in the US, including within the southeastern states that comprise US EPA Region 4. Biotic condition of southeastern streams with respect to nutrients has been evaluated using biological indicators based on mac...

Computational study of culture conditions and nutrient supply in a hollow membrane sheet bioreactor for large-scale bone tissue engineering.

PubMed

Khademi, Ramin; Mohebbi-Kalhori, Davod; Hadjizadeh, Afra

2014-03-01

Successful bone tissue culture in a large implant is still a challenge. We have previously developed a porous hollow membrane sheet (HMSh) for tissue engineering applications (Afra Hadjizadeh and Davod Mohebbi-Kalhori, J Biomed. Mater. Res. Part A [2]). This study aims to investigate culture conditions and nutrient supply in a bioreactor made of HMSh. For this purpose, hydrodynamic and mass transport behavior in the newly proposed hollow membrane sheet bioreactor including a lumen region and porous membrane (scaffold) for supporting and feeding cells with a grooved section for accommodating gel-cell matrix was numerically studied. A finite element method was used for solving the governing equations in both homogenous and porous media. Furthermore, the cell resistance and waste production have been included in a 3D mathematical model. The influences of different bioreactor design parameters and the scaffold properties which determine the HMSh bioreactor performance and various operating conditions were discussed in detail. The obtained results illustrated that the novel scaffold can be employed in the large-scale applications in bone tissue engineering.

Insufficient evidence for association of NOD2/CARD15 or other inflammatory bowel disease–associated markers on GVHD incidence or other adverse outcomes in T-replete, unrelated donor transplantation

PubMed Central

Nguyen, Yume; Al-Lehibi, Abed; Gorbe, Elizabeth; Li, Ellen; Haagenson, Michael; Wang, Tao; Spellman, Stephen; Lee, Stephanie J.

2010-01-01

Previous European studies suggest NOD2/CARD15 and interleukin-23 receptor (IL-23R) donor or recipient variants are associated with adverse clinical outcomes in allogeneic hematopoietic stem cell transplantation. We reexamined these findings as well as the role of another inflammatory bowel disease (IBD) susceptibility gene (immunity-related GTPase family, M [IRGM]) on transplantation outcomes in 390 US patients and their matched unrelated donors, accrued between 1995 and 2004. Patients received T-replete grafts with mostly myeloablative conditioning regimens. Multivariate analyses were performed for overall survival, disease-free survival, transplantation-related mortality, relapse, and acute and chronic graft-versus-host disease. Of 390 pairs, NOD2/CARD15 variant single nucleotide polymorphisms (SNPs) were found in 14% of donors and 17% of recipients. In 3% both donor and recipient had a mutant SNP. Thirteen percent of donors and 16% of recipients had variant IL23R SNPs, with 3% having both donor and recipient variants. Twenty-three percent of both donors and recipients had variant IRGM SNPs. None of the 3 IBD-associated alleles showed a statistically significant association with any adverse clinical outcomes. Our results do not support an association between the 3 IBD-associated SNPs and adverse outcomes after matched unrelated donor hematopoietic cell transplantations in US patients. PMID:20177049

Nutrient concentrations and their relations to the biotic integrity of wadeable streams in Wisconsin

USGS Publications Warehouse

Robertson, Dale M.; Graczyk, David J.; Garrison, Paul J.; Wang, Lizhu; LaLiberte, Gina; Bannerman, Roger

2006-01-01

Excessive nutrient (phosphorus and nitrogen) loss from watersheds is frequently associated with degraded water quality in streams. To reduce this loss, agricultural performance standards and regulations for croplands and livestock operations are being proposed by various States. In addition, the U.S. Environmental Protection Agency is establishing regionally based nutrient criteria that can be refined by each State to determine whether actions are needed to improve a stream's water quality. More confidence in the environmental benefits of the proposed performance standards and nutrient criteria will be possible with a better understanding of the biotic responses to a range of nutrient concentrations in different environmental settings. The U.S. Geological Survey and the Wisconsin Department of Natural Resources collected data from 240 wadeable streams throughout Wisconsin to: 1) describe how nutrient concentrations and biotic-community structure vary throughout the State; 2) determine which environmental characteristics are most strongly related to the distribution of nutrient concentrations; 3) determine reference water-quality and biotic conditions for different areas of the State; 4) determine how the biotic community of streams in different areas of the State respond to changes in nutrient concentrations; 5) determine the best regionalization scheme to describe the patterns in reference conditions and the responses in water quality and the biotic community; and 6) develop new indices to estimate nutrient concentrations in streams from a combination of biotic indices. The ultimate goal of this study is to provide the information needed to guide the development of regionally based nutrient criteria for Wisconsin streams. For total nitrogen (N) and suspended chlorophyll (SCHL) concentrations and water clarity, regional variability in reference conditions and in the responses in water quality to changes in land use are best described by subdividing wadeable streams

Nutrient concentrations and fluxes in tributaries to the Swan-Canning estuary, Western Australia

USGS Publications Warehouse

Peters, N.E.; Donohue, R.

1999-01-01

In Western Australia, catchment nutrient availability on an areal basis is primarily controlled by the disposal of animal waste and the type and rate of fertilizer application, particularly in coastal areas. The coastal areas receive notably higher rainfall and have more intense horticulture and animal production than inland areas, and are undergoing rapid urbanization, particularly adjacent to the estuary. Also, the surficial aquifers on the coastal plain are generally sandy having a low nutrient retention capacity and rapidly transmit soluble and colloidal material through the subsurface. In the Swan-Canning basin, high air and soil temperatures and seasonally arid conditions cause rapid mineralization of nitrogen and phosphorus. The nutrients are subsequently available for transport during the onset of seasonal wet weather, which typically begins during the period from late April to June. In addition to the rapid mobility of nutrients in streamwater from agricultural areas during the wet season, drains in urban areas, which typically have high nutrient concentrations, also are an important source of nutrients as the drains flow directly to the estuary throughout the year.

Sensitivity analysis of a pulse nutrient addition technique for estimating nutrient uptake in large streams

Treesearch

Laurence Lin; J.R. Webster

2012-01-01

The constant nutrient addition technique has been used extensively to measure nutrient uptake in streams. However, this technique is impractical for large streams, and the pulse nutrient addition (PNA) has been suggested as an alternative. We developed a computer model to simulate Monod kinetics nutrient uptake in large rivers and used this model to evaluate the...

Removal of nutrient limitations by long-term fertilization decreases nocturnal water loss in savanna trees.

Treesearch

F.G. Scholz; S.J. Bucci; G. Goldstein; F.C. Meinzer; A.C. Franco; F. Miralles-Wilhelm

2007-01-01

Under certain environmental conditions, nocturnal transpiration can be relatively high in temperate and tropical woody species. In nutrient-poor systems such as the Brazilian Cerrado, nocturnal transpiration may enhance delivery of nutrients to roots. We compared nocturnal transpiration of three dominant Cerrado tree species growing in unfertilized plots and plots to...

Effect of the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus fasciculatum on the essential oil yield related characters and nutrient acquisition in the crops of different cultivars of menthol mint (Mentha arvensis) under field conditions.

PubMed

Gupta, M L; Prasad, Arun; Ram, Muni; Kumar, Sushil

2002-01-01

The effects of inoculation with vesicular-arbuscular mycorrhizal (VAM) fungus Glomusfasciculatum on the root colonization, growth, essential oil yield and nutrient acquisition of three cultivars of menthol mint (Mentha arvensis); Kalka, Shivalik and Gomti, were studied under field conditions. The VAM inoculation significantly increased the root colonization, plant height, fresh herbage and dry matter yield. oil content and oil yield as compared to non-inoculated cultivars. The effect of VAM inoculation on the root colonization, growth and yield of mint was more pronounced with the cv Shivalik than the cvs Kalka and Gomati, indicating Shivalik as a highly mycorrhizal dependent genotype. VAM inoculation significantly increased the uptake of N, P and K by shoot tissues of mint, but most markedly increased the uptake of P. The VAM-inoculated mint plants depleted the available N, P and K in the rhizosphere soil as compared to non-inoculated control plants, however the extent of nutrient depletion was greater for P than N and K. We conclude that the VAM inoculation could significantly increase the root colonization, growth, essential oil yield and nutrient acquisition of mint for obtaining economic production under field conditions.

Nutrient acquisition strategies of mammalian cells.

PubMed

Palm, Wilhelm; Thompson, Craig B

2017-06-07

Mammalian cells are surrounded by diverse nutrients, such as glucose, amino acids, various macromolecules and micronutrients, which they can import through transmembrane transporters and endolysosomal pathways. By using different nutrient sources, cells gain metabolic flexibility to survive periods of starvation. Quiescent cells take up sufficient nutrients to sustain homeostasis. However, proliferating cells depend on growth-factor-induced increases in nutrient uptake to support biomass formation. Here, we review cellular nutrient acquisition strategies and their regulation by growth factors and cell-intrinsic nutrient sensors. We also discuss how oncogenes and tumour suppressors promote nutrient uptake and thereby support the survival and growth of cancer cells.

The Coupling of Solution Chemistry to Plant Nutrient Demand in an on Demand Nutrient Delivery System

NASA Technical Reports Server (NTRS)

Savage, Wayne

1998-01-01

The goal of the proposal will be to determine the suitability of the DASI instrument in providing a signal that can be recognized and be utilized as an indicator of plant stress. The method to be utilized for evaluating stress is the presentation of an every increasing level of nutrient deficiency and salinity stress (addition of salt (NACl) or increasing concentration of balanced nutrient) while simultaneously recording spectral reflectance using the DASI instrument and monitoring the traditional processes of gas exchange and nutrient uptake parameters. In this manner, we will be able to directly compare the DASI measurements with known stresses as determined by the traditional gas exchange and nutrient uptake measures of stress. We anticipate that the DASI will provide a sensitive identifier of plant stress; recording signals of the resulting changes in plant metabolism in real time, far before any visible effects of stress could be observed. Thus, there is a potential for very early management intervention to correct a stress condition before damage could develop. The present response time for the observation of visual symptoms of plant stress is considerable and only provides an indication that a stress is present after it has been present for an extended period of time. Thus, the impact of a plant-based life support function will have already been significant. An additional benefit of this research to regenerative life support will be the characterization of a potential recovery scenario from various degrees of stress. The experimental approach to be employed includes the removal of the stress at various points in the stress gradient and the characterization of plant performance and reflectance spectra during recovery from various degrees of stress. Spectral reflectance imaging techniques have been developed and used to measure the biochemical composition of plants and relate these characteristics to the fluxes of biochemical elements within the ecosystem.

Species richness alters spatial nutrient heterogeneity effects on above-ground plant biomass.

PubMed

Xi, Nianxun; Zhang, Chunhui; Bloor, Juliette M G

2017-12-01

Previous studies have suggested that spatial nutrient heterogeneity promotes plant nutrient capture and growth. However, little is known about how spatial nutrient heterogeneity interacts with key community attributes to affect plant community production. We conducted a meta-analysis to investigate how nitrogen heterogeneity effects vary with species richness and plant density. Effect size was calculated using the natural log of the ratio in plant biomass between heterogeneous and homogeneous conditions. Effect sizes were significantly above zero, reflecting positive effects of spatial nutrient heterogeneity on community production. However, species richness decreased the magnitude of heterogeneity effects on above-ground biomass. The magnitude of heterogeneity effects on below-ground biomass did not vary with species richness. Moreover, we detected no modification in heterogeneity effects with plant density. Our results highlight the importance of species richness for ecosystem function. Asynchrony between above- and below-ground responses to spatial nutrient heterogeneity and species richness could have significant implications for biotic interactions and biogeochemical cycling in the long term. © 2017 The Author(s).

Recipient-donor KIR ligand matching prevents CMV reactivation post-haploidentical T cell-replete transplantation.

PubMed

Zhao, Xiang-Yu; Luo, Xue-Yi; Yu, Xing-Xing; Zhao, Xiao-Su; Han, Ting-Ting; Chang, Ying-Jun; Huo, Ming-Rui; Xu, Lan-Ping; Zhang, Xiao-Hui; Liu, Kai-Yan; Li, Dan; Jiang, Zheng-Fan; Huang, Xiao-Jun

2017-06-01

Licensed natural killer (NK) cells have been demonstrated to have anti-cytomegalovirus (CMV) activity. We prospectively analysed the human leucocyte antigen typing of donor-recipient pairs and the killer cell immunoglobulin-like receptor (KIR) typing of donors for 180 leukaemia patients to assess the predictive roles of licensed NK cells on CMV reactivation post-T-cell-replete haploidentical stem cell transplantation. Multivariate analysis showed that donor-recipient KIR ligand graft-versus-host or host-versus-graft direction mismatch was associated with increased refractory CMV infection (Hazard ratio = 2·556, 95% confidence interval, 1·377-4·744, P = 0·003) post-transplantation. Donor-recipient KIR ligand matching decreased CMV reactivation [51·65% (46·67, 56·62%) vs. 75·28% (70·87, 79·69%), P = 0·012], refractory CMV infection [17·58% (13·77, 21·40%) vs. 35·96% (31·09, 40·82%), P = 0·004] and CMV disease [3·30% (1·51, 5·08%) vs. 11·24% (8·04, 14·43%), P = 0·024] by day 100 post-transplantation. In addition, the percentage of γ-interferon expression on donor-derived NK cells was significantly higher in the recipients among the recipient-donor pairs with a KIR ligand match compared with that in the recipients among the pairs with a KIR ligand graft-versus-host or host-versus-graft direction mismatch on days 30 and 100 post-transplantation (P = 0·036 and 0·047, respectively). These findings have suggested that donor-recipient KIR ligand matching might promote the NK cell licensing process, thereby increasing NK cell-mediated protection against CMV reactivation. © 2017 John Wiley & Sons Ltd.

Time-dependent Variation in Life Cycle Assessment of Microalgal Biorefinery Co-products

NASA Astrophysics Data System (ADS)

Montazeri, Mahdokht

Microalgae can serve as a highly productive biological feedstock for fuels and chemicals. The lipid fraction of algal seeds has been the primary target of research for biofuel production. However, numerous assessments have found that valorization of co-products is essential to achieve economic and environmental goals. The relative proportion of co-products depends on the biomolecular composition of algae at the time of harvesting. In the present study the productivity of lipid, starch, and protein fractions were shown through growth experiments to vary widely with species, feeding regime, and harvesting time. Four algae species were cultivated under nitrogen-replete and -deplete conditions and analyzed at regular harvesting intervals. Dynamic growth results were then used for life cycle assessment using the U.S. Department of Energy's GREET model to determine optimal growth scenarios that minimize life cycle greenhouse gas (GHG) emissions, eutrophication, and cumulative energy demand (CED), while aiming for an energy return on investment (EROI) greater than unity. Per kg of biodiesel produced, C. sorokiniana in N-replete conditions harvested at 12 days was most favorable for GHG emissions and CED, despite having a lipid content of <20%. N. oculata under the same conditions had the lowest life cycle eutrophication impacts, driven by efficient nutrient cycling and valorization of microalgal protein and anaerobic digester residue co-products. The results indicate that growth cycle times that maximize a single fraction do not necessarily result in the most favorable environmental performance on a life cycle basis, underscoring the importance of designing biorefinery systems that simultaneously optimize for lipid and non-lipid fractions.

Drug-nutrient interactions and their implications for safety evaluations.

PubMed

Conner, M W; Newberne, P M

1984-06-01

In order to assess the relevance of the drug-nutrient interactions described in this chapter to routine toxicologic studies, the range of nutrient concentrations within which these interactions may occur must be compared to the range of nutrient concentrations found in routinely used rodent diets. While obviously deficient levels of some nutrients were supplied to demonstrate some of the interactions, others occur when the nutrients are present in adequate or excess levels, such as might be found in commercially available diets. These diets are known to vary from batch to batch in nutrient content. A lifetime toxicity/carcinogenicity bioassay using rodents may last longer than 2 years, during which time several batches of diet will be used. The variation in diet composition, coupled with inadequate diet description, makes nutrient-toxin interactions not only possible, but difficult to recognize. These considerations raise the practical and philosophical question as to what type of diet is most appropriate for rodents used for safety evaluation of drugs and chemicals. Is it appropriate to use diets that vary unpredictably in nutrient content, that infer a degree of protection against chemical carcinogenesis and which supply some nutrients such as protein in great excess of dietary needs? Is the increase in sensitivity to chemical carcinogens of animals fed purified diets desirable or does this increased sensitivity of the bioassay exceed that required to assess the risk of human exposure? In other words, is the use of purified diets likely to increase the number of false positive results? Proper interpretation and extrapolation of safety evaluation studies requires adequate description of the test system. Given the profound influence of diet on the response to some toxins, the composition of the diet should, ideally, be defined with the same rigor as are the test compound and the strain, age, sex, and housing conditions of the animals. It is likely, however, that

The effects of CO2 and nutrient fertilisation on the growth and temperature response of the mangrove Avicennia germinans.

PubMed

Reef, Ruth; Slot, Martijn; Motro, Uzi; Motro, Michal; Motro, Yoav; Adame, Maria F; Garcia, Milton; Aranda, Jorge; Lovelock, Catherine E; Winter, Klaus

2016-08-01

In order to understand plant responses to both the widespread phenomenon of increased nutrient inputs to coastal zones and the concurrent rise in atmospheric CO2 concentrations, CO2-nutrient interactions need to be considered. In addition to its potential stimulating effect on photosynthesis and growth, elevated CO2 affects the temperature response of photosynthesis. The scarcity of experiments testing how elevated CO2 affects the temperature response of tropical trees hinders our ability to model future primary productivity. In a glasshouse study, we examined the effects of elevated CO2 (800 ppm) and nutrient availability on seedlings of the widespread mangrove Avicennia germinans. We assessed photosynthetic performance, the temperature response of photosynthesis, seedling growth and biomass allocation. We found large synergistic gains in both growth (42 %) and photosynthesis (115 %) when seedlings grown under elevated CO2 were supplied with elevated nutrient concentrations relative to their ambient growing conditions. Growth was significantly enhanced under elevated CO2 only under high-nutrient conditions, mainly in above-ground tissues. Under low-nutrient conditions and elevated CO2, root volume was more than double that of seedlings grown under ambient CO2 levels. Elevated CO2 significantly increased the temperature optimum for photosynthesis by ca. 4 °C. Rising CO2 concentrations are likely to have a significant positive effect on the growth rate of A. germinans over the next century, especially in areas where nutrient availability is high.

Temporal responses of coastal hypoxia to nutrient loading and physical controls

NASA Astrophysics Data System (ADS)

Kemp, W. M.; Testa, J. M.; Conley, D. J.; Gilbert, D.; Hagy, J. D.

2009-12-01

The incidence and intensity of hypoxic waters in coastal aquatic ecosystems has been expanding in recent decades coincident with eutrophication of the coastal zone. Worldwide, there is strong interest in reducing the size and duration of hypoxia in coastal waters, because hypoxia causes negative effects for many organisms and ecosystem processes. Although strategies to reduce hypoxia by decreasing nutrient loading are predicated on the assumption that this action would reverse eutrophication, recent analyses of historical data from European and North American coastal systems suggest little evidence for simple linear response trajectories. We review published parallel time-series data on hypoxia and loading rates for inorganic nutrients and labile organic matter to analyze trajectories of oxygen (O2) response to nutrient loading. We also assess existing knowledge of physical and ecological factors regulating O2 in coastal marine waters to facilitate analysis of hypoxia responses to reductions in nutrient (and/or organic matter) inputs. Of the 24 systems identified where concurrent time series of loading and O2 were available, half displayed relatively clear and direct recoveries following remediation. We explored in detail 5 well-studied systems that have exhibited complex, non-linear responses to variations in loading, including apparent "regime shifts". A summary of these analyses suggests that O2 conditions improved rapidly and linearly in systems where remediation focused on organic inputs from sewage treatment plants, which were the primary drivers of hypoxia. In larger more open systems where diffuse nutrient loads are more important in fueling O2 depletion and where climatic influences are pronounced, responses to remediation tended to follow non-linear trends that may include hysteresis and time-lags. Improved understanding of hypoxia remediation requires that future studies use comparative approaches and consider multiple regulating factors. These analyses

Nutrient depletion in Bacillus subtilis biofilms triggers matrix production

NASA Astrophysics Data System (ADS)

Zhang, Wenbo; Seminara, Agnese; Suaris, Melanie; Brenner, Michael P.; Weitz, David A.; Angelini, Thomas E.

2014-01-01

Many types of bacteria form colonies that grow into physically robust and strongly adhesive aggregates known as biofilms. A distinguishing characteristic of bacterial biofilms is an extracellular polymeric substance (EPS) matrix that encases the cells and provides physical integrity to the colony. The EPS matrix consists of a large amount of polysaccharide, as well as protein filaments, DNA and degraded cellular materials. The genetic pathways that control the transformation of a colony into a biofilm have been widely studied, and yield a spatiotemporal heterogeneity in EPS production. Spatial gradients in metabolites parallel this heterogeneity in EPS, but nutrient concentration as an underlying physiological initiator of EPS production has not been explored. Here, we study the role of nutrient depletion in EPS production in Bacillus subtilis biofilms. By monitoring simultaneously biofilm size and matrix production, we find that EPS production increases at a critical colony thickness that depends on the initial amount of carbon sources in the medium. Through studies of individual cells in liquid culture we find that EPS production can be triggered at the single-cell level by reducing nutrient concentration. To connect the single-cell assays with conditions in the biofilm, we calculate carbon concentration with a model for the reaction and diffusion of nutrients in the biofilm. This model predicts the relationship between the initial concentration of carbon and the thickness of the colony at the point of internal nutrient deprivation.

Nutrient sequestration in Aquitaine lakes (SW France) limits nutrient flux to the coastal zone

NASA Astrophysics Data System (ADS)

Buquet, Damien; Anschutz, Pierre; Charbonnier, Céline; Rapin, Anne; Sinays, Rémy; Canredon, Axel; Bujan, Stéphane; Poirier, Dominique

2017-12-01

Oligotrophic coastal zones are disappearing from increased nutrient loading. The quantity of nutrients reaching the coast is determined not only by their original source (e.g. fertilizers used in agriculture, waste water discharges) and the land use, but also by the pathways through which nutrients are cycled from the source to the river mouth. In particular, lakes sequester nutrients and, hence, reduce downstream transfer of nutrients to coastal environments. Here, we quantify the impact of Aquitaine great lakes on the fluxes of dissolved macro-nutrients (N, P, Si) to the Bay of Biscay. For that, we have measured nutrient concentrations and fluxes in 2014 upstream and downstream lakes of Lacanau and Carcans-Hourtin, which belongs to the catchment of the Arcachon Bay, which is the largest coastal lagoon of the Bay of Biscay French coast. Data were compared to values obtained from the Leyre river, the main freshwater and nutrient source for the lagoon. Results show that processes in lakes greatly limit nutrient flux to the lagoon compared to fluxes from Leyre river, although the watershed is similar in terms of land cover. In lakes, phosphorus and silicon are trapped for long term in the sediment, silicon as amorphous biogenic silica and phosphorus as organic P and P associated with Fe-oxides. Nitrogen that enters lakes mostly as nitrate is used for primary production. N is mineralized in the sediment; a fraction diffuses as ammonium. N2 production through benthic denitrification extracts only 10% of dissolved inorganic nitrogen from the aquatic system. The main part is sequestered in organic-rich sediment that accumulates below 5 m depth in both lakes.

Interactions among irradiance, nutrients, and herbivores constrain a stream algal community.

PubMed

Rosemond, A D

1993-07-01

Using stream-side, flow-through channels, I tested for the effects of nutrients (NU) (nitrogen plus phosphorus), irradiance (L), and snail grazing (G) on a benthic algal community in a small, forested stream. Grazed communities were-dominated by a chlorophyte (basal cells ofStigeoclonium) and a cyanophyte (Chamaesiphon investiens), whereas ungrazed communities were comprised almost entirely of diatoms, regardless of nutrient and light levels. Snails maintained low algal biomass in all grazed treatments, presumably by consuming increased algal production in treatments to which L and NU were increased. When nutrients were increased, cellular nutrient content increased under ambient conditions (shaded, grazed) and biomass and productivity increased when snails were removed and light was increased. Together, nutrients and light had positive effects and grazing had negative effects on biomass (chlorophylla, AFDM, algal biovolume) and chlorophyll-and areal-specific productivity in ANOVAs. However, in most cases, only means from treatments in which all three factors were manipulated (ungrazed, +NU&L treatments) were significantly different from controls; effects of single factors were generally undetectable. These results indicate that all three factors simultaneously limited algal biomass and productivity in this stream during the summer months. Additionally, the effects of these factors in combination were in some cases different from the effects of single factors. For example, light had slight negative effects on some biomass parameters when added at ambient snail densities and nutrient concentrations, but had strong positive effects in conjunction with nutrient addition and snail removal. This study demonstrates that algal biomass and productivity can be under multiple constraints by irradiance, nutrients, and herbivores and indicates the need to employ multifactor experiments to test for such interactive effects.

The nutrient-load hypothesis: patterns of resource limitation and community structure driven by competition for nutrients and light.

PubMed

Brauer, Verena S; Stomp, Maayke; Huisman, Jef

2012-06-01

Resource competition theory predicts that the outcome of competition for two nutrients depends on the ratio at which these nutrients are supplied. Yet there is considerable debate whether nutrient ratios or absolute nutrient loads determine the species composition of phytoplankton and plant communities. Here we extend the classical resource competition model for two nutrients by including light as additional resource. Our results suggest the nutrient-load hypothesis, which predicts that nutrient ratios determine the species composition in oligotrophic environments, whereas nutrient loads are decisive in eutrophic environments. The underlying mechanism is that nutrient enrichment shifts the species interactions from competition for nutrients to competition for light, which favors the dominance of superior light competitors overshadowing all other species. Intermediate nutrient loads can generate high biodiversity through a fine-grained patchwork of two-species and three-species coexistence equilibria. Depending on the species traits, however, competition for nutrients and light may also produce multiple alternative stable states, suppressing the predictability of the species composition. The nutrient-load hypothesis offers a solution for several discrepancies between classical resource competition theory and field observations, explains why eutrophication often leads to diversity loss, and provides a simple conceptual framework for patterns of biodiversity and community structure observed in nature.

N-ViroTech--a novel process for the treatment of nutrient limited wastewaters.

PubMed

Slade, A H; Gapes, D J; Stuthridge, T R; Anderson, S M; Dare, P H; Pearson, H G W; Dennis, M

2004-01-01

As pulp and paper wastewaters are mostly deficient in nitrogen and phosphorus, historical practice has dictated that they cannot be effectively treated using microbiological processes without the addition of supplementary nutrients, such as urea and phosphoric acid. Supplementation is a difficult step to manage efficiently, requiring extensive post-treatment monitoring and some degree of overdosing to ensure sufficient nutrient availability under all conditions. As a result, treated wastewaters usually contain excess amounts of both nutrients, leading to potential impacts on the receiving waters such as eutrophication. N-ViroTech is a highly effective alternative treatment technology which overcomes this nutrient deficiency/excess paradox. The process relies on communities of nitrogen-fixing bacteria, which are able to directly fix nitrogen from the atmosphere, thus satisfying their cellular nitrogen requirements. The process relies on manipulation of growth conditions within the biological system to maintain a nitrogen-fixing population whilst achieving target wastewater treatment performance. The technology has significant advantages over conventional activated sludge operation, including: Improved environmental performance. Nutrient loadings in the final treated effluent for selected nitrogen and phosphorus species (particularly ammonium and orthophosphate) may be reduced by over 90% compared to conventional systems; Elimination of nitrogen supplementation, and minimisation of phosphorus supplementation, thus achieving significant chemical savings and resulting in between 25% and 35% savings in operational costs for a typical system; Self-regulation of nutrient requirements, as the bacteria only use as much nitrogen as they require, allowing for substantially less operator intervention and monitoring. This paper will summarise critical performance outcomes of the N-ViroTech process utilising results from laboratory-, pilot-scale and recent alpha-adopter, full

Impacts of elevated atmospheric CO₂ on nutrient content of important food crops.

PubMed

Dietterich, Lee H; Zanobetti, Antonella; Kloog, Itai; Huybers, Peter; Leakey, Andrew D B; Bloom, Arnold J; Carlisle, Eli; Fernando, Nimesha; Fitzgerald, Glenn; Hasegawa, Toshihiro; Holbrook, N Michele; Nelson, Randall L; Norton, Robert; Ottman, Michael J; Raboy, Victor; Sakai, Hidemitsu; Sartor, Karla A; Schwartz, Joel; Seneweera, Saman; Usui, Yasuhiro; Yoshinaga, Satoshi; Myers, Samuel S

2015-01-01

One of the many ways that climate change may affect human health is by altering the nutrient content of food crops. However, previous attempts to study the effects of increased atmospheric CO2 on crop nutrition have been limited by small sample sizes and/or artificial growing conditions. Here we present data from a meta-analysis of the nutritional contents of the edible portions of 41 cultivars of six major crop species grown using free-air CO2 enrichment (FACE) technology to expose crops to ambient and elevated CO2 concentrations in otherwise normal field cultivation conditions. This data, collected across three continents, represents over ten times more data on the nutrient content of crops grown in FACE experiments than was previously available. We expect it to be deeply useful to future studies, such as efforts to understand the impacts of elevated atmospheric CO2 on crop macro- and micronutrient concentrations, or attempts to alleviate harmful effects of these changes for the billions of people who depend on these crops for essential nutrients.

Impact of Nutrient Restriction on the Structure of Listeria monocytogenes Biofilm Grown in a Microfluidic System.

PubMed

Cherifi, Tamazight; Jacques, Mario; Quessy, Sylvain; Fravalo, Philippe

2017-01-01

Biofilm formation by the pathogen Listeria monocytogenes is a major concern in food industries. The aim of this work was to elucidate the effect of nutrient limitation on both biofilm architecture and on the viability of the bacteria in microfluidic growth conditions. Biofilm formation by two L. monocytogenes strains was performed in a rich medium (BHI) and in a 10-fold diluted BHI (BHI/10) at 30°C for 24 h by using both static conditions and the microfluidic system Bioflux. In dynamic conditions, biofilms grown in rich and poor medium showed significant differences as well in structure and in the resulting biovolume. In BHI/10, biofilm was organized in a knitted network where cells formed long chains, whereas in the rich medium, the observed structure was homogeneous cellular multilayers. Biofilm biovolume production in BHI/10 was significantly higher than in BHI in these dynamic conditions. Interestingly, biovolume of dead cells in biofilms formed under limited nutrient conditions (BHI/10) was significantly higher than in biofilms formed in the BHI medium. In the other hand, in static conditions, biofilm is organized in a multilayer cells and dispersed cells in a rich medium BHI and poor medium BHI/10 respectively. There was significantly more biomass in the rich medium compared to BHI/10 but no difference was noted in the dead/damaged subpopulation showing how L. monocytogenes biofilm could be affected by the growth conditions. This work demonstrated that nutrient concentration affects biofilm structure and the proportion of dead cells in biofilms under microfluidic condition. Our study also showed that limited nutrients play an important role in the structural stability of L. monocytogenes biofilm by enhancing cell death and liberating extracellular DNA.

Impact of Nutrient Restriction on the Structure of Listeria monocytogenes Biofilm Grown in a Microfluidic System

PubMed Central

Cherifi, Tamazight; Jacques, Mario; Quessy, Sylvain; Fravalo, Philippe

2017-01-01

Biofilm formation by the pathogen Listeria monocytogenes is a major concern in food industries. The aim of this work was to elucidate the effect of nutrient limitation on both biofilm architecture and on the viability of the bacteria in microfluidic growth conditions. Biofilm formation by two L. monocytogenes strains was performed in a rich medium (BHI) and in a 10-fold diluted BHI (BHI/10) at 30°C for 24 h by using both static conditions and the microfluidic system Bioflux. In dynamic conditions, biofilms grown in rich and poor medium showed significant differences as well in structure and in the resulting biovolume. In BHI/10, biofilm was organized in a knitted network where cells formed long chains, whereas in the rich medium, the observed structure was homogeneous cellular multilayers. Biofilm biovolume production in BHI/10 was significantly higher than in BHI in these dynamic conditions. Interestingly, biovolume of dead cells in biofilms formed under limited nutrient conditions (BHI/10) was significantly higher than in biofilms formed in the BHI medium. In the other hand, in static conditions, biofilm is organized in a multilayer cells and dispersed cells in a rich medium BHI and poor medium BHI/10 respectively. There was significantly more biomass in the rich medium compared to BHI/10 but no difference was noted in the dead/damaged subpopulation showing how L. monocytogenes biofilm could be affected by the growth conditions. This work demonstrated that nutrient concentration affects biofilm structure and the proportion of dead cells in biofilms under microfluidic condition. Our study also showed that limited nutrients play an important role in the structural stability of L. monocytogenes biofilm by enhancing cell death and liberating extracellular DNA. PMID:28567031

Effects of grassland management practices and environmental conditions on nutrient concentrations in overland flow

NASA Astrophysics Data System (ADS)

Kurz, Isabelle; Coxon, Catherine; Tunney, Hubert; Ryan, Declan

2005-03-01

The loss of nutrients from agricultural land to water bodies is a serious concern in river basin management in many countries. To gain information on the contributions of agricultural grassland to the eutrophication of water bodies, this study set out to assess phosphorus (P) loss from grassland areas on poorly drained soils. A second aim was to look at the impact of grassland management practices on nutrient concentrations in overland flow. Edge-of-field measurements of overland flow quantity and of P and nitrogen (N) concentrations in overland flow were carried out at three study sites with different soil P levels. The amounts of overland flow and the P concentrations in overland flow varied considerably during events, and among sites and events. Despite this variability, there was a clear increase in P loss in overland flow from the low to the medium and high soil P sites. The inter-site variability of the P concentrations in overland flow greatly exceeded the variability of the amounts of overland flow from the different sites. Thus, P concentrations had a larger impact than the volume of overland flow on the differences in P exports from the three sites. Management practices which, at times, influenced the P and N concentrations in overland flow were grazing and N fertilisation.

Lycopersicon esculentum submitted to Cd-stressful conditions in nutrition solution: Nutrient contents and translocation.

PubMed

Carvalho Bertoli, Alexandre; Gabriel Cannata, Marcele; Carvalho, Ruy; Ribeiro Bastos, Ana Rosa; Puggina Freitas, Matheus; dos Santos Augusto, Amanda

2012-12-01

The increasing number of cases on soil contamination by heavy metals has affected crop yields, besides representing an imminent risk to food. Some of these contaminants, such as cadmium, are very similar to micronutrients and thus more easily absorbed by the plants. This study assessed the effect of increasing amounts of cadmium on the content and translocation of micro and macronutrients in tomato. Tomatoes were grown in Clark's nutrient solution and subjected to increasing levels of Cd: 0, 0.025, 0.1, 0.5 and 1.0mg L(-1). The plants contaminated by cadmium had a maximum reduction in the aerial part compared to the control of: 2.25g kg(-1), 2.80g kg(-1), 18.93mg kg(-1) and 14.15mg kg(-1) for K, Ca, Mn and Zn, respectively. In other parts of the tomato were reduced from 2.3g kg(-1) K in fruits and 280.5mg kg(-1) of Mn in the roots. In addition to changes in the levels of some nutrients, the restricted Cd translocation in 1.15 percent P and 2.8 percent Cu to shoots compared to control, but did not affect the translocation of K, Ca, Mg and Zn. Copyright © 2012 Elsevier Inc. All rights reserved.

Effects of irradiation intensity and pH on nutrients release and solids destruction of waste activated sludge using the microwave-enhanced advanced oxidation process.

PubMed

Chan, W I; Liao, P H; Lo, K V

2010-11-01

Using the microwave-enhanced advanced oxidation process (MW/H2O2-AOP), the pH and irradiation intensity on waste activated sludge samples were investigated to provide insight to the athermal effects on nutrients release, solids destruction, particle size distribution and dewaterability, and to demonstrate their interrelationships. Carbonaceous matters and nutrients released into solution depended on the irradiation intensity and time. Higher irradiation levels tended to be more effective in the solubilization of nutrients and had more pronounced effects in the dewaterability of sludge. In terms of particle size distribution, detectable particles increased in size for treatments in acidic conditions, while the dewaterability of treated sludge was improved. In treatments under neutral and alkaline conditions, the particle size range increased, with more small particles formed, thereby significantly deteriorating the dewaterability of sludge treated in alkaline conditions. The best results for the solubilization of nutrients were in alkaline conditions with high irradiation power, but dewaterability of the sludge was compromised. Sludge treatment with the MW/H2O2-AOP in acidic conditions with high irradiation power yielded the best dewaterable sludge and significant nutrient solubilization; therefore, it is the recommended treatment condition for activated sludge.

Enteral feeding: drug/nutrient interaction.

PubMed

Lourenço, R

2001-04-01

Enteral nutrition support via a feeding tube is the first choice for artificial nutrition. Most patients also require simultaneous drug therapy, with the potential risk for drug-nutrient interactions which may become relevant in clinical practice. During enteral nutrition, drug-nutrient interactions are more likely to occur than in patients fed orally. However, there is a lack of awareness about its clinical significance, which should be recognised and prevented in order to optimise nutritional and pharmacological therapeutic goals of safety and efficacy. To raise the awareness of potential drug-nutrient interactions and influence on clinical outcomes. To identify factors that can promote drug-nutrient interactions and contribute to nutrition and/or therapeutic failure. To be aware of different types of drug-nutrient interactions. To understand complex underlying mechanisms responsible for drug-nutrient interactions. To learn basic rules for the administration of medications during tube-feeding. Copyright 2001 Harcourt Publishers Ltd.

Transovarial silencing of the subolesin gene in three-host ixodid tick species after injection of replete females with subolesin dsRNA.

PubMed

Kocan, Katherine M; Manzano-Roman, Raúl; de la Fuente, José

2007-05-01

RNA interference (RNAi) has become the most powerful experimental tool for the study of gene function in ticks. Subolesin, initially called 4D8, was found to be protective against tick infestations when used as a vaccine and was shown to be highly conserved among ixodid tick species at the nucleotide and protein levels. RNAi caused systemic silencing of subolesin and demonstrated that this protein is involved in regulation of tick feeding, reproduction, and development. Recently, these results were extended to the one-host tick Rhipicephalus (Boophilus) microplus in which injection of dsRNA into replete females resulted in transovarial silencing of subolesin expression in eggs and larvae. Herein, we report transovarial silencing of subolesin by RNAi in the three-host ticks, Amblyomma americanum, Dermacentor variabilis, and Ixodes scapularis. Silencing of subolesin expression by RNAi in these tick species also affected subolesin expression in eggs and larvae. Transovarial RNAi appears to be a common mechanism in ixodid ticks and provides a simple method for the rapid characterization of tick genes involved in oviposition, embryogenesis, and larval development.

Nutrient Management in Recirculating Hydroponic Culture

NASA Technical Reports Server (NTRS)

Bugbee, Bruce

2004-01-01

There is an increasing need to recirculate and reuse nutrient solutions in order to reduce environmental and economic costs. However, one of the weakest points in hydroponics is the lack of information on managing the nutrient solution. Many growers and research scientists dump out nutrient solutions and refill at weekly intervals. Other authors have recommended measuring the concentrations of individual nutrients in solution as a key to nutrient control and maintenance. Dumping and replacing solution is unnecessary. Monitoring ions in solution is not always necessary; in fact the rapid depletion of some nutrients often causes people to add toxic amounts of nutrients to the solution. Monitoring ions in solution is interesting, but it is not the key to effective maintenance.

Pilot plant demonstration of stable and efficient high rate biological nutrient removal with low dissolved oxygen conditions.

PubMed

Keene, Natalie A; Reusser, Steve R; Scarborough, Matthew J; Grooms, Alan L; Seib, Matt; Santo Domingo, Jorge; Noguera, Daniel R

2017-09-15

Aeration in biological nutrient removal (BNR) processes accounts for nearly half of the total electricity costs at many wastewater treatment plants. Even though conventional BNR processes are usually operated to have aerated zones with high dissolved oxygen (DO) concentrations, recent research has shown that nitrification can be maintained using very low-DO concentrations (e.g., below 0.2 mg O 2 /L), and therefore, it may be possible to reduce energy use and costs in BNR facilities by decreasing aeration. However, the effect of reduced aeration on enhanced biological phosphorus removal (EBPR) is not understood. In this study, we investigated, at the pilot-scale level, the effect of using minimal aeration on the performance of an EBPR process. Over a 16-month operational period, we performed stepwise decreases in aeration, reaching an average DO concentration of 0.33 mg O 2 /L with stable operation and nearly 90% phosphorus removal. Under these low-DO conditions, nitrification efficiency was maintained, and nearly 70% of the nitrogen was denitrified, without the need for internal recycling of high nitrate aeration basin effluent to the anoxic zone. At the lowest DO conditions used, we estimate a 25% reduction in energy use for aeration compared to conventional BNR operation. Our improved understanding of the efficiency of low-DO BNR contributes to the global goal of reducing energy consumption during wastewater treatment operations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Polyploid Titan Cells Produce Haploid and Aneuploid Progeny To Promote Stress Adaptation

PubMed Central

Gerstein, Aleeza C.; Fu, Man Shun; Mukaremera, Liliane; Li, Zhongming; Ormerod, Kate L.; Fraser, James A.; Berman, Judith

2015-01-01

ABSTRACT Cryptococcus neoformans is a major life-threatening fungal pathogen. In response to the stress of the host environment, C. neoformans produces large polyploid titan cells. Titan cell production enhances the virulence of C. neoformans, yet whether the polyploid aspect of titan cells is specifically influential remains unknown. We show that titan cells were more likely to survive and produce offspring under multiple stress conditions than typical cells and that even their normally sized daughters maintained an advantage over typical cells in continued exposure to stress. Although polyploid titan cells generated haploid daughter cell progeny upon in vitro replication under nutrient-replete conditions, titan cells treated with the antifungal drug fluconazole produced fluconazole-resistant diploid and aneuploid daughter cells. Interestingly, a single titan mother cell was capable of generating multiple types of aneuploid daughter cells. The increased survival and genomic diversity of titan cell progeny promote rapid adaptation to new or high-stress conditions. PMID:26463162

Biochar-enhanced composts reduce the potential leaching of nutrients and heavy metals and suppress plant-parasitic nematodes in excessively fertilized cucumber soils.

PubMed

Cao, Yune; Gao, Yanming; Qi, Yanbin; Li, Jianshe

2018-03-01

Excessive fertilization is a common agricultural practice that has largely reduced soil nutrient retention capacity and led to nutrient leaching in China. To reduce nutrient leaching, in this study, we evaluated the application of biochar, compost, and biochar-compost on soil properties, leaching water quality, and cucumber plant growth in soils with different nutrient levels. In general, the concentrations of nutrients and heavy metals in leaching water were higher under high-nutrient conditions than under low-nutrient conditions. Both biochar and compost efficiently enhanced soil cation exchange capacity (CEC), water holding capacity (WHC), and microbial biomass carbon (MBC), nitrogen (MBN), and phosphorus (MBP), reduced the potential leaching of nutrients and heavy metals, and improved plant growth. The efficiency of biochar and compost in soil CEC, WHC, MBC, MBN, and MBP and plant growth was enhanced when applied jointly. In addition, biochar and biochar-enhanced compost efficiently suppressed plant-parasitic nematode infestation in a soil with high levels of both N and P. Our results suggest that biochar-enhanced compost can reduce the potential environmental risks in excessively fertilized vegetable soils.

Control of Breast Carcinoma Angiogenesis by Nutrient Stress Mechanisms

DTIC Science & Technology

2004-08-01

phosphorylated and degraded in response to ponent of the curry spice turmeric and has been used in traditional NFKB-activating conditions. Overexpression of IKBM...to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, DC 20503 1. AGENCY USE ONLY 2. REPORT DATE 3. REPORT TYPE...under nutrient/oxygen deprivation conditions in the presence of ATF6 wt or ATF6 DN proteins. The results shown in Figures 1 and 2 led us to conclude

Yield Gap, Indigenous Nutrient Supply and Nutrient Use Efficiency for Maize in China.

PubMed

Xu, Xinpeng; Liu, Xiaoyan; He, Ping; Johnston, Adrian M; Zhao, Shicheng; Qiu, Shaojun; Zhou, Wei

2015-01-01

Great achievements have been attained in agricultural production of China, while there are still many difficulties and challenges ahead that call for put more efforts to overcome to guarantee food security and protect environment simultaneously. Analyzing yield gap and nutrient use efficiency will help develop and inform agricultural policies and strategies to increase grain yield. On-farm datasets from 2001 to 2012 with 1,971 field experiments for maize (Zea mays L.) were collected in four maize agro-ecological regions of China, and the optimal management (OPT), farmers' practice (FP), a series of nutrient omission treatments were used to analyze yield gap, nutrient use efficiency and indigenous nutrient supply by adopting meta-analysis and ANOVA analysis. Across all sites, the average yield gap between OPT and FP was 0.7 t ha-1, the yield response to nitrogen (N), phosphorus (P), and potassium (K) were 1.8, 1.0, and 1.2 t ha-1, respectively. The soil indigenous nutrient supply of N, P, and K averaged 139.9, 33.7, and 127.5 kg ha-1, respectively. As compared to FP, the average recovery efficiency (RE) of N, P, and K with OPT increased by percentage point of 12.2, 5.5, and 6.5, respectively. This study indicated that there would be considerable potential to further improve yield and nutrient use efficiency in China, and will help develop and inform agricultural policies and strategies, while some management measures such as soil, plant and nutrient are necessary and integrate with advanced knowledge and technologies.

Yield Gap, Indigenous Nutrient Supply and Nutrient Use Efficiency for Maize in China

PubMed Central

Xu, Xinpeng; Liu, Xiaoyan; He, Ping; Johnston, Adrian M.; Zhao, Shicheng; Qiu, Shaojun; Zhou, Wei

2015-01-01

Great achievements have been attained in agricultural production of China, while there are still many difficulties and challenges ahead that call for put more efforts to overcome to guarantee food security and protect environment simultaneously. Analyzing yield gap and nutrient use efficiency will help develop and inform agricultural policies and strategies to increase grain yield. On-farm datasets from 2001 to 2012 with 1,971 field experiments for maize (Zea mays L.) were collected in four maize agro-ecological regions of China, and the optimal management (OPT), farmers’ practice (FP), a series of nutrient omission treatments were used to analyze yield gap, nutrient use efficiency and indigenous nutrient supply by adopting meta-analysis and ANOVA analysis. Across all sites, the average yield gap between OPT and FP was 0.7 t ha-1, the yield response to nitrogen (N), phosphorus (P), and potassium (K) were 1.8, 1.0, and 1.2 t ha-1, respectively. The soil indigenous nutrient supply of N, P, and K averaged 139.9, 33.7, and 127.5 kg ha-1, respectively. As compared to FP, the average recovery efficiency (RE) of N, P, and K with OPT increased by percentage point of 12.2, 5.5, and 6.5, respectively. This study indicated that there would be considerable potential to further improve yield and nutrient use efficiency in China, and will help develop and inform agricultural policies and strategies, while some management measures such as soil, plant and nutrient are necessary and integrate with advanced knowledge and technologies. PMID:26484543

Nutrient status and plant growth effects of forest soils in the Basin of Mexico

Treesearch

Mark E. Fenn; V.M. Perea-Estrada; L.I. de Bauer; M. Pérez-Suárez; D.R. Parker; V.M. Cetina-Alcalá

2006-01-01

The nutrient status of forest soils in the Mexico City Air Basin was evaluated by observing plant growth responses to fertilization with N, P or both nutrients combined. P deficiency was the most frequent condition for soil from two high pollution sites and N deficiency was greatest at a low N deposition site. Concentrations of Pb and Ni, and to a lesser extent Zn and...

Effect of Temperature and Nutrient Concentration on Survival of Foodborne Pathogens in Deciduous Fruit Processing Environments for Effective Hygiene Management.

PubMed

Duvenage, Stacey; Korsten, Lise

2016-11-01

Temperature and good sanitation practices are important factors for controlling growth of microorganisms. Fresh produce is stored at various temperatures to ensure quality and to prolong shelf life. When foodborne pathogens survive and grow on fresh produce at storage temperatures, then additional control strategies are needed to inactivate these pathogens. The aim of this study was to determine how temperatures associated with deciduous fruit processing and storage facilities (0.5, 4, and 21°C) affect the growth and/or survival of Escherichia coli O157:H7, Listeria monocytogenes , Salmonella enterica subsp. enterica serovar Typhimurium, and Staphylococcus aureus under different nutrient conditions (nutrient rich and nutrient poor) and on simulated contact surfaces (vinyl coupons). Information on the growth and survival of foodborne pathogens at specific deciduous fruit processing and storage temperatures (0.5°C) is not available. All pathogens except E. coli O157:H7 were able to survive on vinyl coupons at all temperatures. L. monocytogenes proliferated under both nutrient conditions independent of temperature. S. aureus was the pathogen least affected by nutrient conditions. The survival of foodborne pathogens on the vinyl coupons, a model system for studying surfaces in fruit preparation and storage environments, indicates the potential for cross-contamination of deciduous fruit products under poor sanitation conditions. Foodborne pathogens that can proliferate and survive at various temperatures under different nutrient conditions could lead to fruit cross-contamination. Temperature mismanagement, which could allow pathogen proliferation in contaminated fruit packing houses and storage environments, is a concern. Therefore, proper hygiene and sanitation practices, removal of possible contaminants, and proper food safety management systems are needed to ensure food safety.

Biochar as carrier for plant nutrients and microorganisms - techniques of agro-activation

NASA Astrophysics Data System (ADS)

Schmidt, H.-P.

2012-04-01

The soil enhancing qualities of biochar are strongly linked to its influence on nutrient cycling dynamics, sorption dynamics and to changing habitat condition for soil fauna. But as shown in multiple studies, the addition of pure biochar to agricultural soils may provoke reduced plant growth caused by the immobilisation of plant nutrients. The very potent sorption dynamics of biochar makes it an effective carrier for plant nutrients and plant-root symbiotic microorganisms. At the Delinat-Institute, we tried sundry methods of charging biochars with organic and mineral plant nutrients as well as with microorganisms. This includes the use of biochar as bulk agent in aerobic composting, in malolactic fermentation and as treatment for liquid manure, but also formulations of mineral carbon-fertilizers. Those biochar products are tested in pot and also large scale field trials. Results and experiences of these trials as well as different activation methods will be explained. A short overview of industrial designing of biochar based products will be given.

Analysis of Gene Expression in Escherichia coli in Response to Changes of Growth-Limiting Nutrient in Chemostat Cultures

PubMed Central

Hua, Qiang; Yang, Chen; Oshima, Taku; Mori, Hirotada; Shimizu, Kazuyuki

2004-01-01

Studies of steady-state metabolic fluxes in Escherichia coli grown in nutrient-limited chemostat cultures suggest remarkable flux alterations in response to changes of growth-limiting nutrient in the medium (Hua et al., J. Bacteriol. 185:7053-7067, 2003). To elucidate the physiological adaptation of cells to the nutrient condition through the flux change and understand the molecular mechanisms underlying the change in the flux, information on gene expression is of great importance. DNA microarray analysis was performed to investigate the global transcriptional responses of steady-state cells grown in chemostat cultures with limited glucose or ammonia while other environmental conditions and the growth rate were kept constant. In slow-growing cells (specific growth rate of 0.10 h−1), 9.8% of a total of 4,071 genes investigated, especially those involved in amino acid metabolism, central carbon and energy metabolism, transport system and cell envelope, were observed to be differentially expressed between the two nutrient-limited cultures. One important characteristic of E. coli grown under nutrient limitation was its capacity to scavenge carbon or nitrogen from the medium through elevating the expression of the corresponding transport and assimilation genes. The number of differentially expressed genes in faster-growing cells (specific growth rate of 0.55 h−1), however, decreased to below half of that in slow-growing cells, which could be explained by diverse transcriptional responses to the growth rate under different nutrient limitations. Independent of the growth rate, 92 genes were identified as being differentially expressed. Genes tightly related to the culture conditions were highlighted, some of which may be used to characterize nutrient-limited growth. PMID:15066832

Root cortical aerenchyma inhibits radial nutrient transport in maize (Zea mays).

PubMed

Hu, Bo; Henry, Amelia; Brown, Kathleen M; Lynch, Jonathan P

2014-01-01

Formation of root cortical aerenchyma (RCA) can be induced by nutrient deficiency. In species adapted to aerobic soil conditions, this response is adaptive by reducing root maintenance requirements, thereby permitting greater soil exploration. One trade-off of RCA formation may be reduced radial transport of nutrients due to reduction in living cortical tissue. To test this hypothesis, radial nutrient transport in intact roots of maize (Zea mays) was investigated in two radiolabelling experiments employing genotypes with contrasting RCA. In the first experiment, time-course dynamics of phosphate loading into the xylem were measured from excised nodal roots that varied in RCA formation. In the second experiment, uptake of phosphate, calcium and sulphate was measured in seminal roots of intact young plants in which variation in RCA was induced by treatments altering ethylene action or genetic differences. In each of three paired genotype comparisons, the rate of phosphate exudation of high-RCA genotypes was significantly less than that of low-RCA genotypes. In the second experiment, radial nutrient transport of phosphate and calcium was negatively correlated with the extent of RCA for some genotypes. The results support the hypothesis that RCA can reduce radial transport of some nutrients in some genotypes, which could be an important trade-off of this trait.

Quantifying stream nutrient uptake from ambient to saturation with instantaneous tracer additions

NASA Astrophysics Data System (ADS)

Covino, T. P.; McGlynn, B. L.; McNamara, R.

2009-12-01

Stream nutrient tracer additions and spiraling metrics are frequently used to quantify stream ecosystem behavior. However, standard approaches limit our understanding of aquatic biogeochemistry. Specifically, the relationship between in-stream nutrient concentration and stream nutrient spiraling has not been characterized. The standard constant rate (steady-state) approach to stream spiraling parameter estimation, either through elevating nutrient concentration or adding isotopically labeled tracers (e.g. 15N), provides little information regarding the stream kinetic curve that represents the uptake-concentration relationship analogous to the Michaelis-Menten curve. These standard approaches provide single or a few data points and often focus on estimating ambient uptake under the conditions at the time of the experiment. Here we outline and demonstrate a new method using instantaneous nutrient additions and dynamic analyses of breakthrough curve (BTC) data to characterize the full relationship between spiraling metrics and nutrient concentration. We compare the results from these dynamic analyses to BTC-integrated, and standard steady-state approaches. Our results indicate good agreement between these three approaches but we highlight the advantages of our dynamic method. Specifically, our new dynamic method provides a cost-effective and efficient approach to: 1) characterize full concentration-spiraling metric curves; 2) estimate ambient spiraling metrics; 3) estimate Michaelis-Menten parameters maximum uptake (Umax) and the half-saturation constant (Km) from developed uptake-concentration kinetic curves, and; 4) measure dynamic nutrient spiraling in larger rivers where steady-state approaches are impractical.

Effects of Irrigating Tree Seedlings with a Nutrient Solution

Treesearch

R. P. Belanger; C. B. Briscoe

1963-01-01

Subsurface irrigation with nutrient solution was found to be biologically feasible under the conditions tested. Growth of seedlings was satisfactory, but not unusually good. On the bases of total height growth, and growth in fresh weight, the various fertilizers tested produced statistically different results. The species tested, members of three different families and...

Electric-field-enhanced nutrient consumption in dielectric biomaterials that contain anchorage-dependent cells.

PubMed

Belfiore, Laurence A; Floren, Michael L; Belfiore, Carol J

2012-02-01

This research contribution addresses electric-field stimulation of intra-tissue mass transfer and cell proliferation in viscoelastic biomaterials. The unsteady state reaction-diffusion equation is solved according to the von Kármán-Pohlhausen integral method of boundary layer analysis when nutrient consumption and tissue regeneration occur in response to harmonic electric potential differences across a parallel-plate capacitor in a dielectric-sandwich configuration. The partial differential mass balance with diffusion and electro-kinetic consumption contains the Damköhler (Λ(2)) and Deborah (De) numbers. Zero-field and electric-field-sensitive Damköhler numbers affect nutrient boundary layer growth. Diagonal elements of the 2nd-rank diffusion tensor are enhanced in the presence of weak electric fields, in agreement with the formalism of equilibrium and nonequilibrium thermodynamics. Induced dipole polarization density within viscoelastic biomaterials is calculated via the real and imaginary components of the complex dielectric constant, according to the Debye equation, to quantify electro-kinetic stimulation. Rates of nutrient consumption under zero-field conditions are described by third-order kinetics that include local mass densities of nutrients, oxygen, and attached cells. Thinner nutrient boundary layers are stabilized at shorter dimensionless diffusion times when the zero-field intra-tissue Damköhler number increases above its initial-condition-sensitive critical value [i.e., {Λ(2)(zero-field)}(critical)≥53, see Eq. (23)], such that the biomaterial core is starved of essential ingredients required for successful proliferation. When tissue regeneration occurs above the critical electric-field-sensitive intra-tissue Damköhler number, the electro-kinetic contribution to nutrient consumption cannot be neglected. The critical electric-field-sensitive intra-tissue Damköhler number is proportional to the Deborah number. Copyright © 2011 Elsevier B

Nutrient foraging strategies are associated with productivity and population growth in forest shrubs

PubMed Central

Stone, Bram W. G.; Faillace, Cara A.; Lafond, Jonathan J.; Baumgarten, Joni M.; Mozdzer, Thomas J.; Dighton, John; Meiners, Scott J.; Grabosky, Jason C.; Ehrenfeld, Joan G.

2017-01-01

Background and Aims Temperate deciduous forest understoreys are experiencing widespread changes in community composition, concurrent with increases in rates of nitrogen supply. These shifts in plant abundance may be driven by interspecific differences in nutrient foraging (i.e. conservative vs. acquisitive strategies) and, thus, adaptation to contemporary nutrient loading conditions. This study sought to determine if interspecific differences in nutrient foraging could help explain patterns of shrub success and decline in eastern North American forests. Methods Using plants grown in a common garden, fine root traits associated with nutrient foraging were measured for six shrub species. Traits included the mean and skewness of the root diameter distribution, specific root length (SRL), C:N ratio, root tissue density, arbuscular mycorrhizal colonization and foraging precision. Above- and below-ground productivity were also determined for the same plants, and population growth rates were estimated using data from a long-term study of community dynamics. Root traits were compared among species and associations among root traits, measures of productivity and rates of population growth were evaluated. Key Results Species fell into groups having thick or thin root forms, which correspond to conservative vs. acquisitive nutrient foraging strategies. Interspecific variation in root morphology and tissue construction correlated with measures of productivity and rates of cover expansion. Of the four species with acquisitive traits, three were introduced species that have become invasive in recent decades, and the fourth was a weedy native. In contrast, the two species with conservative traits were historically dominant shrubs that have declined in abundance in eastern North American forests. Conclusions In forest understoreys of eastern North America, elevated nutrient availability may impose a filter on species success in addition to above-ground processes such as herbivory

USA Nutrient managment forecasting via the "Fertilizer Forecaster": linking surface runnof, nutrient application and ecohydrology.

NASA Astrophysics Data System (ADS)

Drohan, Patrick; Buda, Anthony; Kleinman, Peter; Miller, Douglas; Lin, Henry; Beegle, Douglas; Knight, Paul

2017-04-01

USA and state nutrient management planning offers strategic guidance that strives to educate farmers and those involved in nutrient management to make wise management decisions. A goal of such programs is to manage hotspots of water quality degradation that threaten human and ecosystem health, water and food security. The guidance provided by nutrient management plans does not provide the day-to-day support necessary to make operational decisions, particularly when and where to apply nutrients over the short term. These short-term decisions on when and where to apply nutrients often make the difference between whether the nutrients impact water quality or are efficiently utilized by crops. Infiltrating rainfall events occurring shortly after broadcast nutrient applications are beneficial, given they will wash soluble nutrients into the soil where they are used by crops. Rainfall events that generate runoff shortly after nutrients are broadcast may wash off applied nutrients, and produce substantial nutrient losses from that site. We are developing a model and data based support tool for nutrient management, the Fertilizer Forecaster, which identifies the relative probability of runoff or infiltrating events in Pennsylvania (PA) landscapes in order to improve water quality. This tool will support field specific decisions by farmers and land managers on when and where to apply fertilizers and manures over 24, 48 and 72 hour periods. Our objectives are to: (1) monitor agricultural hillslopes in watersheds representing four of the five Physiographic Provinces of the Chesapeake Bay basin; (2) validate a high resolution mapping model that identifies soils prone to runoff; (3) develop an empirically based approach to relate state-of-the-art weather forecast variables to site-specific rainfall infiltration or runoff occurrence; (4) test the empirical forecasting model against alternative approaches to forecasting runoff occurrence; and (5) recruit farmers from the four

Nutrient Budgets Calculated in Floodwaters Using a Whole-Ecosystem Experimental Manipulation

NASA Astrophysics Data System (ADS)

Talbot, C. J.; Paterson, M. J.; Xenopoulos, M. A.

2017-12-01

Flooding provides pathways for nutrients to move into surface waters and alter nutrient concentrations, therefore influencing downstream ecosystems and increasing events of eutrophication. Nutrient enrichment will likely affect water quality, primary production, and overall ecosystem function. Quantifying nutrient movement post-flood will help evaluate the risks or advantages that flooding will have on ecosystem processes. Here we constructed nutrient budgets using data collected as part of the Flooded Upland Dynamics Experiment (FLUDEX) at the Experimental Lakes Area (ELA) in northwestern Ontario. Three experimental reservoirs with varying amounts of stored carbon were created by flooding forested land from May through September annually from 1999 to 2003. Organic matter became a significant source of nutrients under flooded conditions and elevated reservoir total nitrogen (TN) and total phosphorus (TP) concentrations within one week of flooding. The highest TN (2.6 mg L-1) and TP (579 µg L-1) concentrations throughout the entire flooding experiment occurred in the medium carbon reservoir within the first two weeks of flooding in 1999. TN and TP fluxes were positive in all years of flooding. TP fluxes decreased after each flooding season therefore, TP production may be less problematic in floodplains subject to frequent repeated flooding. However, TN fluxes remained large even after repeated flooding. Therefore, flooding, whether naturally occurring or from anthropogenic flow alteration, may be responsible for producing significant amounts of nitrogen and phosphorus in aquatic ecosystems.

Placental Nutrient Transport and Intrauterine Growth Restriction

PubMed Central

Gaccioli, Francesca; Lager, Susanne

2016-01-01

Intrauterine growth restriction refers to the inability of the fetus to reach its genetically determined potential size. Fetal growth restriction affects approximately 5–15% of all pregnancies in the United States and Europe. In developing countries the occurrence varies widely between 10 and 55%, impacting about 30 million newborns per year. Besides having high perinatal mortality rates these infants are at greater risk for severe adverse outcomes, such as hypoxic ischemic encephalopathy and cerebral palsy. Moreover, reduced fetal growth has lifelong health consequences, including higher risks of developing metabolic and cardiovascular diseases in adulthood. Numerous reports indicate placental insufficiency as one of the underlying causes leading to altered fetal growth and impaired placental capacity of delivering nutrients to the fetus has been shown to contribute to the etiology of intrauterine growth restriction. Indeed, reduced expression and/or activity of placental nutrient transporters have been demonstrated in several conditions associated with an increased risk of delivering a small or growth restricted infant. This review focuses on human pregnancies and summarizes the changes in placental amino acid, fatty acid, and glucose transport reported in conditions associated with intrauterine growth restriction, such as maternal undernutrition, pre-eclampsia, young maternal age, high altitude and infection. PMID:26909042

Microbial nutrient niches in the gut

PubMed Central

Pereira, Fátima C.

2017-01-01

Summary The composition and function of the mammalian gut microbiota has been the subject of much research in recent years, but the principles underlying the assembly and structure of this complex community remain incompletely understood. Processes that shape the gut microbiota are thought to be mostly niche‐driven, with environmental factors such as the composition of available nutrients largely determining whether or not an organism can establish. The concept that the nutrient landscape dictates which organisms can successfully colonize and persist in the gut was first proposed in Rolf Freter's nutrient niche theory. In a situation where nutrients are perfectly mixed and there is balanced microbial growth, Freter postulated that an organism can only survive if it is able to utilize one or a few limiting nutrients more efficiently than its competitors. Recent experimental work indicates, however, that nutrients in the gut vary in space and time. We propose that in such a scenario, Freter's nutrient niche theory must be expanded to account for the co‐existence of microorganisms utilizing the same nutrients but in distinct sites or at different times, and that metabolic flexibility and mixed‐substrate utilization are common strategies for survival in the face of ever‐present nutrient fluctuations. PMID:28035742

Steady-State Growth under Inorganic Carbon Limitation Conditions Increases Energy Consumption for Maintenance and Enhances Nitrous Oxide Production in Nitrosomonas europaea.

PubMed

Mellbye, Brett L; Giguere, Andrew; Chaplen, Frank; Bottomley, Peter J; Sayavedra-Soto, Luis A

2016-06-01

Nitrosomonas europaea is a chemolithoautotrophic bacterium that oxidizes ammonia (NH3) to obtain energy for growth on carbon dioxide (CO2) and can also produce nitrous oxide (N2O), a greenhouse gas. We interrogated the growth, physiological, and transcriptome responses of N. europaea to conditions of replete (>5.2 mM) and limited inorganic carbon (IC) provided by either 1.0 mM or 0.2 mM sodium carbonate (Na2CO3) supplemented with atmospheric CO2 IC-limited cultures oxidized 25 to 58% of available NH3 to nitrite, depending on the dilution rate and Na2CO3 concentration. IC limitation resulted in a 2.3-fold increase in cellular maintenance energy requirements compared to those for NH3-limited cultures. Rates of N2O production increased 2.5- and 6.3-fold under the two IC-limited conditions, increasing the percentage of oxidized NH3-N that was transformed to N2O-N from 0.5% (replete) up to 4.4% (0.2 mM Na2CO3). Transcriptome analysis showed differential expression (P ≤ 0.05) of 488 genes (20% of inventory) between replete and IC-limited conditions, but few differences were detected between the two IC-limiting treatments. IC-limited conditions resulted in a decreased expression of ammonium/ammonia transporter and ammonia monooxygenase subunits and increased the expression of genes involved in C1 metabolism, including the genes for RuBisCO (cbb gene cluster), carbonic anhydrase, folate-linked metabolism of C1 moieties, and putative C salvage due to oxygenase activity of RuBisCO. Increased expression of nitrite reductase (gene cluster NE0924 to NE0927) correlated with increased production of N2O. Together, these data suggest that N. europaea adapts physiologically during IC-limited steady-state growth, which leads to the uncoupling of NH3 oxidation from growth and increased N2O production. Nitrification, the aerobic oxidation of ammonia to nitrate via nitrite, is an important process in the global nitrogen cycle. This process is generally dependent on ammonia

Steady-State Growth under Inorganic Carbon Limitation Conditions Increases Energy Consumption for Maintenance and Enhances Nitrous Oxide Production in Nitrosomonas europaea

PubMed Central

Giguere, Andrew; Chaplen, Frank; Bottomley, Peter J.

2016-01-01

ABSTRACT Nitrosomonas europaea is a chemolithoautotrophic bacterium that oxidizes ammonia (NH3) to obtain energy for growth on carbon dioxide (CO2) and can also produce nitrous oxide (N2O), a greenhouse gas. We interrogated the growth, physiological, and transcriptome responses of N. europaea to conditions of replete (>5.2 mM) and limited inorganic carbon (IC) provided by either 1.0 mM or 0.2 mM sodium carbonate (Na2CO3) supplemented with atmospheric CO2. IC-limited cultures oxidized 25 to 58% of available NH3 to nitrite, depending on the dilution rate and Na2CO3 concentration. IC limitation resulted in a 2.3-fold increase in cellular maintenance energy requirements compared to those for NH3-limited cultures. Rates of N2O production increased 2.5- and 6.3-fold under the two IC-limited conditions, increasing the percentage of oxidized NH3-N that was transformed to N2O-N from 0.5% (replete) up to 4.4% (0.2 mM Na2CO3). Transcriptome analysis showed differential expression (P ≤ 0.05) of 488 genes (20% of inventory) between replete and IC-limited conditions, but few differences were detected between the two IC-limiting treatments. IC-limited conditions resulted in a decreased expression of ammonium/ammonia transporter and ammonia monooxygenase subunits and increased the expression of genes involved in C1 metabolism, including the genes for RuBisCO (cbb gene cluster), carbonic anhydrase, folate-linked metabolism of C1 moieties, and putative C salvage due to oxygenase activity of RuBisCO. Increased expression of nitrite reductase (gene cluster NE0924 to NE0927) correlated with increased production of N2O. Together, these data suggest that N. europaea adapts physiologically during IC-limited steady-state growth, which leads to the uncoupling of NH3 oxidation from growth and increased N2O production. IMPORTANCE Nitrification, the aerobic oxidation of ammonia to nitrate via nitrite, is an important process in the global nitrogen cycle. This process is generally dependent

Eliciting the mitochondrial unfolded protein response by nicotinamide adenine dinucleotide repletion reverses fatty liver disease in mice

PubMed Central

Gariani, Karim; Menzies, Keir J.; Ryu, Dongryeol; Wegner, Casey J.; Wang, Xu; Ropelle, Eduardo R.; Moullan, Norman; Zhang, Hongbo; Perino, Alessia; Lemos, Vera; Kim, Bohkyung; Park, Young‐Ki; Piersigilli, Alessandra; Pham, Tho X.; Yang, Yue; Ku, Chai Siah; Koo, Sung I.; Fomitchova, Anna; Cantó, Carlos; Schoonjans, Kristina; Sauve, Anthony A.

2015-01-01

With no approved pharmacological treatment, nonalcoholic fatty liver disease (NAFLD) is now the most common cause of chronic liver disease in Western countries and its worldwide prevalence continues to increase along with the growing obesity epidemic. Here, we show that a high‐fat high‐sucrose (HFHS) diet, eliciting chronic hepatosteatosis resembling human fatty liver, lowers hepatic nicotinamide adenine dinucleotide (NAD+) levels driving reductions in hepatic mitochondrial content, function, and adenosine triphosphate (ATP) levels, in conjunction with robust increases in hepatic weight, lipid content, and peroxidation in C57BL/6J mice. To assess the effect of NAD+ repletion on the development of steatosis in mice, nicotinamide riboside, a precursor of NAD+ biosynthesis, was added to the HFHS diet, either as a preventive strategy or as a therapeutic intervention. We demonstrate that NR prevents and reverts NAFLD by inducing a sirtuin (SIRT)1‐ and SIRT3‐dependent mitochondrial unfolded protein response, triggering an adaptive mitohormetic pathway to increase hepatic β‐oxidation and mitochondrial complex content and activity. The cell‐autonomous beneficial component of NR treatment was revealed in liver‐specific Sirt1 knockout mice (Sirt1hep−/−), whereas apolipoprotein E‐deficient mice (Apoe −/−) challenged with a high‐fat high‐cholesterol diet affirmed the use of NR in other independent models of NAFLD. Conclusion: Our data warrant the future evaluation of NAD+ boosting strategies to manage the development or progression of NAFLD. (Hepatology 2016;63:1190–1204) PMID:26404765

Modeling nutrient in-stream processes at the watershed scale using Nutrient Spiralling metrics

NASA Astrophysics Data System (ADS)

Marcé, R.; Armengol, J.

2009-01-01

One of the fundamental problems of using large-scale biogeochemical models is the uncertainty involved in aggregating the components of fine-scale deterministic models in watershed applications, and in extrapolating the results of field-scale measurements to larger spatial scales. Although spatial or temporal lumping may reduce the problem, information obtained during fine-scale research may not apply to lumped categories. Thus, the use of knowledge gained through fine-scale studies to predict coarse-scale phenomena is not straightforward. In this study, we used the nutrient uptake metrics defined in the Nutrient Spiralling concept to formulate the equations governing total phosphorus in-stream fate in a watershed-scale biogeochemical model. The rationale of this approach relies on the fact that the working unit for the nutrient in-stream processes of most watershed-scale models is the reach, the same unit used in field research based on the Nutrient Spiralling concept. Automatic calibration of the model using data from the study watershed confirmed that the Nutrient Spiralling formulation is a convenient simplification of the biogeochemical transformations involved in total phosphorus in-stream fate. Following calibration, the model was used as a heuristic tool in two ways. First, we compared the Nutrient Spiralling metrics obtained during calibration with results obtained during field-based research in the study watershed. The simulated and measured metrics were similar, suggesting that information collected at the reach scale during research based on the Nutrient Spiralling concept can be directly incorporated into models, without the problems associated with upscaling results from fine-scale studies. Second, we used results from our model to examine some patterns observed in several reports on Nutrient Spiralling metrics measured in impaired streams. Although these two exercises involve circular reasoning and, consequently, cannot validate any hypothesis, this

Nutrient Sensing at the Plasma Membrane of Fungal Cells.

PubMed

Van Dijck, Patrick; Brown, Neil Andrew; Goldman, Gustavo H; Rutherford, Julian; Xue, Chaoyang; Van Zeebroeck, Griet

2017-03-01

To respond to the changing environment, cells must be able to sense external conditions. This is important for many processes including growth, mating, the expression of virulence factors, and several other regulatory effects. Nutrient sensing at the plasma membrane is mediated by different classes of membrane proteins that activate downstream signaling pathways: nontransporting receptors, transceptors, classical and nonclassical G-protein-coupled receptors, and the newly defined extracellular mucin receptors. Nontransporting receptors have the same structure as transport proteins, but have lost the capacity to transport while gaining a receptor function. Transceptors are transporters that also function as a receptor, because they can rapidly activate downstream signaling pathways. In this review, we focus on these four types of fungal membrane proteins. We mainly discuss the sensing mechanisms relating to sugars, ammonium, and amino acids. Mechanisms for other nutrients, such as phosphate and sulfate, are discussed briefly. Because the model yeast Saccharomyces cerevisiae has been the most studied, especially regarding these nutrient-sensing systems, each subsection will commence with what is known in this species.

Soil nutrient additions increase invertebrate herbivore abundances, but not herbivory, across three grassland systems.

PubMed

La Pierre, Kimberly J; Smith, Melinda D

2016-02-01

Resource availability may influence invertebrate communities, with important consequences for ecosystem function, such as biomass production. We assessed: (1) the effects of experimental soil nutrient additions on invertebrate abundances and feeding rates and (2) the resultant changes in the effects of invertebrates on aboveground plant biomass at three grassland sites spanning the North American Central Plains, across which plant tissue chemistry and biomass vary. Invertebrate communities and rates of herbivory were sampled within a long-term nutrient-addition experiment established at each site along the broad Central Plains precipitation gradient. Additionally, the effects of invertebrates on aboveground plant biomass were determined under ambient and elevated nutrient conditions. At the more mesic sites, invertebrate herbivore abundances increased and their per capita rate of herbivory decreased with nutrient additions. In contrast, at the semi-arid site where plant biomass is low and plant nutrient concentrations are high, invertebrate herbivore abundances did not vary and per capita rates of herbivory increased with nutrient additions. No change in the effect of invertebrate herbivores on aboveground plant biomass was observed at any of the sites. In sum, nutrient additions induced shifts in both plant biomass and leaf nutrient content, which altered invertebrate abundances and feeding rate. However, due to the inverse relationship between changes in herbivore abundance and per capita rates of herbivory, nutrient additions did not alter the effect of invertebrates on aboveground biomass. Overall, we suggest that this inverse response of herbivore abundance and per capita feeding rate may buffer ecosystems against changes in invertebrate damage in response to fluctuations in nutrient levels.

The convergence of psychology and neurobiology in flavor-nutrient learning.

PubMed

Myers, Kevin P

2018-03-01

Flavor evaluation is influenced by learning from experience with foods. One main influence is flavor-nutrient learning (FNL), a Pavlovian process whereby a flavor acts as a conditioned stimulus (CS) that becomes associated with the postingestive effects of ingested nutrients (the US). As a result that flavor becomes preferred and intake typically increases. This learning powerfully influences food choice and meal patterning. This paper summarizes how research elucidating the physiological and neural substrates of FNL has progressed in parallel with work characterizing how FNL affects perception, motivation, and behavior. The picture that emerges from this work is of a robust system of appetition (a term coined by Sclafani in contrast to the better-understood satiation signals) whereby ingested nutrients sensed in the gut evoke positive motivational responses. Appetition signals act within a meal to promote continued intake in immediate response to gut feedback, and act in the longer term to steer preference towards sensory cues that predict nutritional consequences. Copyright © 2017 Elsevier Ltd. All rights reserved.

Nutrient additions to mitigate for loss of Pacific salmon: consequences for stream biofilm and nutrient dynamics

USGS Publications Warehouse

Marcarelli, Amy M.; Baxter, Colden V.; Wipfli, Mark S.

2014-01-01

Mitigation activities designed to supplement nutrient and organic matter inputs to streams experiencing decline or loss of Pacific salmon typically presuppose that an important pathway by which salmon nutrients are moved to fish (anadromous and/or resident) is via nutrient incorporation by biofilms and subsequent bottom-up stimulation of biofilm production, which is nutrient-limited in many ecosystems where salmon returns have declined. Our objective was to quantify the magnitude of nutrient incorporation and biofilm dynamics that underpin this indirect pathway in response to experimental additions of salmon carcasses and pelletized fish meal (a.k.a., salmon carcass analogs) to 500-m reaches of central Idaho streams over three years. Biofilm standing crops increased 2–8-fold and incorporated marine-derived nutrients (measured using 15N and 13C) in the month following treatment, but these responses did not persist year-to-year. Biofilms were nitrogen (N) limited before treatments, and remained N limited in analog, but not carcass-treated reaches. Despite these biofilm responses, in the month following treatment total N load was equal to 33–47% of the N added to the treated reaches, and N spiraling measurements suggested that as much as 20%, but more likely 2–3% of added N was taken up by microbes. Design of biologically and cost-effective strategies for nutrient addition will require understanding the rates at which stream microbes take up nutrients and the downstream distance traveled by exported nutrients.

Lake nutrient stoichiometry is less predictable than nutrient concentrations at regional and sub-continental scales

USGS Publications Warehouse

Collins, Sarah M.; Oliver, Samantha K.; Lapierre, Jean-Francois; Stanley, Emily H.; Jones, John R.; Wagner, Tyler; Soranno, Patricia A.

2017-01-01

Production in many ecosystems is co-limited by multiple elements. While a known suite of drivers associated with nutrient sources, nutrient transport, and internal processing controls concentrations of phosphorus (P) and nitrogen (N) in lakes, much less is known about whether the drivers of single nutrient concentrations can also explain spatial or temporal variation in lake N:P stoichiometry. Predicting stoichiometry might be more complex than predicting concentrations of individual elements because some drivers have similar relationships with N and P, leading to a weak relationship with their ratio. Further, the dominant controls on elemental concentrations likely vary across regions, resulting in context dependent relationships between drivers, lake nutrients and their ratios. Here, we examine whether known drivers of N and P concentrations can explain variation in N:P stoichiometry, and whether explaining variation in stoichiometry differs across regions. We examined drivers of N:P in ~2,700 lakes at a sub-continental scale and two large regions nested within the sub-continental study area that have contrasting ecological context, including differences in the dominant type of land cover (agriculture vs. forest). At the sub-continental scale, lake nutrient concentrations were correlated with nutrient loading and lake internal processing, but stoichiometry was only weakly correlated to drivers of lake nutrients. At the regional scale, drivers that explained variation in nutrients and stoichiometry differed between regions. In the Midwestern U.S. region, dominated by agricultural land use, lake depth and the percentage of row crop agriculture were strong predictors of stoichiometry because only phosphorus was related to lake depth and only nitrogen was related to the percentage of row crop agriculture. In contrast, all drivers were related to N and P in similar ways in the Northeastern U.S. region, leading to weak relationships between drivers and stoichiometry

Impacts of elevated atmospheric CO2 on nutrient content of important food crops

NASA Astrophysics Data System (ADS)

Dietterich, Lee H.; Zanobetti, Antonella; Kloog, Itai; Huybers, Peter; Leakey, Andrew D. B.; Bloom, Arnold J.; Carlisle, Eli; Fernando, Nimesha; Fitzgerald, Glenn; Hasegawa, Toshihiro; Holbrook, N. Michele; Nelson, Randall L.; Norton, Robert; Ottman, Michael J.; Raboy, Victor; Sakai, Hidemitsu; Sartor, Karla A.; Schwartz, Joel; Seneweera, Saman; Usui, Yasuhiro; Yoshinaga, Satoshi; Myers, Samuel S.

2015-07-01

One of the many ways that climate change may affect human health is by altering the nutrient content of food crops. However, previous attempts to study the effects of increased atmospheric CO2 on crop nutrition have been limited by small sample sizes and/or artificial growing conditions. Here we present data from a meta-analysis of the nutritional contents of the edible portions of 41 cultivars of six major crop species grown using free-air CO2 enrichment (FACE) technology to expose crops to ambient and elevated CO2 concentrations in otherwise normal field cultivation conditions. This data, collected across three continents, represents over ten times more data on the nutrient content of crops grown in FACE experiments than was previously available. We expect it to be deeply useful to future studies, such as efforts to understand the impacts of elevated atmospheric CO2 on crop macro- and micronutrient concentrations, or attempts to alleviate harmful effects of these changes for the billions of people who depend on these crops for essential nutrients.

Impacts of elevated atmospheric CO2 on nutrient content of important food crops

PubMed Central

Dietterich, Lee H.; Zanobetti, Antonella; Kloog, Itai; Huybers, Peter; Leakey, Andrew D. B.; Bloom, Arnold J.; Carlisle, Eli; Fernando, Nimesha; Fitzgerald, Glenn; Hasegawa, Toshihiro; Holbrook, N. Michele; Nelson, Randall L.; Norton, Robert; Ottman, Michael J.; Raboy, Victor; Sakai, Hidemitsu; Sartor, Karla A.; Schwartz, Joel; Seneweera, Saman; Usui, Yasuhiro; Yoshinaga, Satoshi; Myers, Samuel S.

2015-01-01

One of the many ways that climate change may affect human health is by altering the nutrient content of food crops. However, previous attempts to study the effects of increased atmospheric CO2 on crop nutrition have been limited by small sample sizes and/or artificial growing conditions. Here we present data from a meta-analysis of the nutritional contents of the edible portions of 41 cultivars of six major crop species grown using free-air CO2 enrichment (FACE) technology to expose crops to ambient and elevated CO2 concentrations in otherwise normal field cultivation conditions. This data, collected across three continents, represents over ten times more data on the nutrient content of crops grown in FACE experiments than was previously available. We expect it to be deeply useful to future studies, such as efforts to understand the impacts of elevated atmospheric CO2 on crop macro- and micronutrient concentrations, or attempts to alleviate harmful effects of these changes for the billions of people who depend on these crops for essential nutrients. PMID:26217490

Phytoplankton Diversity Effects on Community Biomass and Stability along Nutrient Gradients in a Eutrophic Lake.

PubMed

Tian, Wang; Zhang, Huayong; Zhao, Lei; Zhang, Feifan; Huang, Hai

2017-01-20

The relationship between biodiversity and ecosystem functioning is a central issue in ecology, but how this relationship is affected by nutrient stress is still unknown. In this study, we analyzed the phytoplankton diversity effects on community biomass and stability along nutrient gradients in an artificial eutrophic lake. Four nutrient gradients, varying from slightly eutrophic to highly eutrophic states, were designed by adjusting the amount of polluted water that flowed into the lake. Mean phytoplankton biomass, species richness, and Shannon diversity index all showed significant differences among the four nutrient gradients. Phytoplankton community biomass was correlated with diversity (both species richness and Shannon diversity index), varying from positive to negative along the nutrient gradients. The influence of phytoplankton species richness on resource use efficiency (RUE) also changed from positive to negative along the nutrient gradients. However, the influence of phytoplankton Shannon diversity on RUE was not significant. Both phytoplankton species richness and Shannon diversity had a negative influence on community turnover (measured as community dissimilarity), i.e., a positive diversity-stability relationship. Furthermore, phytoplankton spatial stability decreased along the nutrient gradients in the lake. With increasing nutrient concentrations, the variability (standard deviation) of phytoplankton community biomass increased more rapidly than the average total biomass. Results in this study will be helpful in understanding the phytoplankton diversity effects on ecosystem functioning and how these effects are influenced by nutrient conditions in aquatic ecosystems.

Grassland productivity limited by multiple nutrients.

PubMed

Fay, Philip A; Prober, Suzanne M; Harpole, W Stanley; Knops, Johannes M H; Bakker, Jonathan D; Borer, Elizabeth T; Lind, Eric M; MacDougall, Andrew S; Seabloom, Eric W; Wragg, Peter D; Adler, Peter B; Blumenthal, Dana M; Buckley, Yvonne M; Chu, Chengjin; Cleland, Elsa E; Collins, Scott L; Davies, Kendi F; Du, Guozhen; Feng, Xiaohui; Firn, Jennifer; Gruner, Daniel S; Hagenah, Nicole; Hautier, Yann; Heckman, Robert W; Jin, Virginia L; Kirkman, Kevin P; Klein, Julia; Ladwig, Laura M; Li, Qi; McCulley, Rebecca L; Melbourne, Brett A; Mitchell, Charles E; Moore, Joslin L; Morgan, John W; Risch, Anita C; Schütz, Martin; Stevens, Carly J; Wedin, David A; Yang, Louie H

2015-07-06

Terrestrial ecosystem productivity is widely accepted to be nutrient limited(1). Although nitrogen (N) is deemed a key determinant of aboveground net primary production (ANPP)(2,3), the prevalence of co-limitation by N and phosphorus (P) is increasingly recognized(4-8). However, the extent to which terrestrial productivity is co-limited by nutrients other than N and P has remained unclear. Here, we report results from a standardized factorial nutrient addition experiment, in which we added N, P and potassium (K) combined with a selection of micronutrients (K+μ), alone or in concert, to 42 grassland sites spanning five continents, and monitored ANPP. Nutrient availability limited productivity at 31 of the 42 grassland sites. And pairwise combinations of N, P, and K+μ co-limited ANPP at 29 of the sites. Nitrogen limitation peaked in cool, high latitude sites. Our findings highlight the importance of less studied nutrients, such as K and micronutrients, for grassland productivity, and point to significant variations in the type and degree of nutrient limitation. We suggest that multiple-nutrient constraints must be considered when assessing the ecosystem-scale consequences of nutrient enrichment.

Linkages between nutrients and assemblages of macroinvertebrates and fish in wadeable streams: Implication to nutrient criteria development

USGS Publications Warehouse

Wang, L.; Robertson, Dale M.; Garrison, P.J.

2007-01-01

We sampled 240 wadeable streams across Wisconsin for different forms of phosphorus and nitrogen, and assemblages of macroinvertebrates and fish to (1) examine how macroinvertebrate and fish measures correlated with the nutrients; (2) quantify relationships between key biological measures and nutrient forms to identify potential threshold levels of nutrients to support nutrient criteria development; and (3) evaluate the importance of nutrients in influencing biological assemblages relative to other physicochemical factors at different spatial scales. Twenty-three of the 35 fish and 18 of the 26 macroinvertebrate measures significantly correlated (P < 0.05) with at least one nutrient measure. Percentages of carnivorous, intolerant, and omnivorous fishes, index of biotic integrity, and salmonid abundance were fish measures correlated with the most nutrient measures and had the highest correlation coefficients. Percentages of Ephemeroptera-Plecoptera-Trichoptera individuals and taxa, Hilsenhoff biotic index, and mean tolerance value were macroinvertebrate measures that most strongly correlated with the most nutrient measures. Selected biological measures showed clear trends toward degradation as concentrations of phosphorus and nitrogen increased, and some measures showed clear thresholds where biological measures changed drastically with small changes in nutrient concentrations. Our selected environmental factors explained 54% of the variation in the fish assemblages. Of this explained variance, 46% was attributed to catchment and instream habitat, 15% to nutrients, 3% to other water quality measures, and 36% to the interactions among all the environmental variables. Selected environmental factors explained 53% of the variation in macroinvertebrate assemblages. Of this explained variance, 42% was attributed to catchment and instream habitat, 22% to nutrients, 5% to other water quality measures, and 32% to the interactions among all the environmental variables. ?? 2006

Linkages Between Nutrients and Assemblages of Macroinvertebrates and Fish in Wadeable Streams: Implication to Nutrient Criteria Development

NASA Astrophysics Data System (ADS)

Wang, Lizhu; Robertson, Dale M.; Garrison, Paul J.

2007-02-01

We sampled 240 wadeable streams across Wisconsin for different forms of phosphorus and nitrogen, and assemblages of macroinvertebrates and fish to (1) examine how macroinvertebrate and fish measures correlated with the nutrients; (2) quantify relationships between key biological measures and nutrient forms to identify potential threshold levels of nutrients to support nutrient criteria development; and (3) evaluate the importance of nutrients in influencing biological assemblages relative to other physicochemical factors at different spatial scales. Twenty-three of the 35 fish and 18 of the 26 macroinvertebrate measures significantly correlated ( P < 0.05) with at least one nutrient measure. Percentages of carnivorous, intolerant, and omnivorous fishes, index of biotic integrity, and salmonid abundance were fish measures correlated with the most nutrient measures and had the highest correlation coefficients. Percentages of Ephemeroptera-Plecoptera-Trichoptera individuals and taxa, Hilsenhoff biotic index, and mean tolerance value were macroinvertebrate measures that most strongly correlated with the most nutrient measures. Selected biological measures showed clear trends toward degradation as concentrations of phosphorus and nitrogen increased, and some measures showed clear thresholds where biological measures changed drastically with small changes in nutrient concentrations. Our selected environmental factors explained 54% of the variation in the fish assemblages. Of this explained variance, 46% was attributed to catchment and instream habitat, 15% to nutrients, 3% to other water quality measures, and 36% to the interactions among all the environmental variables. Selected environmental factors explained 53% of the variation in macroinvertebrate assemblages. Of this explained variance, 42% was attributed to catchment and instream habitat, 22% to nutrients, 5% to other water quality measures, and 32% to the interactions among all the environmental variables.

Background Nutrients Affect the Biotransformation of Tetracycline by Stenotrophomonas maltophilia as Revealed by Genomics and Proteomics.

PubMed

Leng, Yifei; Bao, Jianguo; Song, Dandan; Li, Jing; Ye, Mao; Li, Xu

2017-09-19

Certain bacteria are resistant to antibiotics and can even transform antibiotics in the environment. It is unclear how the molecular mechanisms underlying the resistance and biotransformation processes vary under different environmental conditions. The objective of this study is to investigate the molecular mechanisms of tetracycline resistance and biotransformation by Stenotrophomonas maltophilia strain DT1 under various background nutrient conditions. Strain DT1 was exposed to tetracycline for 7 days with four background nutrient conditions: no background (NB), peptone (P), peptone plus citrate (PC), and peptone plus glucose (PG). The biotransformation rate follows the order of PC > P > PG > NB ≈ 0. Genomic analysis showed that strain DT1 contained tet(X1), a gene encoding an FAD-binding monooxygenase, and eight peroxidase genes that could be relevant to tetracycline biotransformation. Quantitative proteomic analyses revealed that nodulation protein transported tetracycline outside of cells; hypoxanthine-guanine phosphoribosyltransferase facilitated the activation of the ribosomal protection proteins to prevent the binding of tetracycline to the ribosome and superoxide dismutase and peroxiredoxin-modified tetracycline molecules. Comparing different nutrient conditions showed that the biotransformation rates of tetracycline were positively correlated with the expression levels of superoxide dismutase.

Microbial nutrient niches in the gut.

PubMed

Pereira, Fátima C; Berry, David

2017-04-01

The composition and function of the mammalian gut microbiota has been the subject of much research in recent years, but the principles underlying the assembly and structure of this complex community remain incompletely understood. Processes that shape the gut microbiota are thought to be mostly niche-driven, with environmental factors such as the composition of available nutrients largely determining whether or not an organism can establish. The concept that the nutrient landscape dictates which organisms can successfully colonize and persist in the gut was first proposed in Rolf Freter's nutrient niche theory. In a situation where nutrients are perfectly mixed and there is balanced microbial growth, Freter postulated that an organism can only survive if it is able to utilize one or a few limiting nutrients more efficiently than its competitors. Recent experimental work indicates, however, that nutrients in the gut vary in space and time. We propose that in such a scenario, Freter's nutrient niche theory must be expanded to account for the co-existence of microorganisms utilizing the same nutrients but in distinct sites or at different times, and that metabolic flexibility and mixed-substrate utilization are common strategies for survival in the face of ever-present nutrient fluctuations. © 2017 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

Lesser scaup winter foraging and nutrient reserve acquisition in east-central Florida

USGS Publications Warehouse

Herring, G.; Collazo, J.A.

2006-01-01

Lesser scaup (Aythya affinis) populations have been declining since the late 1970s. One of the explanations to account for this decline, the spring-condition hypothesis (SCH), is based on the premise that scaup are limited by their ability to acquire or maintain nutrient reserves during migration to the breeding grounds, leading to an impairment of their reproductive potential. Available evidence suggests that endogenous reserves required for reproduction are obtained at a later stage of migration or after arrival at the breeding grounds, not wintering sites. However, only one study has addressed body-condition levels on a southern wintering site in the last decade, with results limited to the wintering grounds on the Mississippi Flyway. We documented foraging behavior, nutrient levels, and body mass of lesser scaup in east-central Florida, USA, where 62% of the Atlantic Flyway population overwinters, during the winters of 2002 and 2003. Diurnal foraging did not increase seasonally. Nocturnal foraging increased seasonally by 76% or 43 minutes per night in females and by 478% or 1.9 hours per night in males. Measures of body condition did not change seasonally during 2002 for either sex. Between early and later winter in 2003 corrected body mass (CBM) and lipid reserves of male scaup increased 77 g and 39 g, respectively. Our results suggest that lesser scaup maintain or may slightly improve their physiological condition in east-central Florida during winter. Lower body mass and differences in nutrient levels in east-central Florida, compared to a wintering site in Louisiana, likely stem from geographic variation and lower thermal requirements associated with the warmer Florida environment. Lesser scaup depart Florida with sufficient reserves to initiate spring migration, but they maximize nutrient reserves used during reproduction elsewhere during migration or on the breeding grounds. These results suggest that maintaining the ecological integrity of this wintering

Spatial dynamics of a nutrient-phytoplankton system with toxic effect on phytoplankton.

PubMed

Chakraborty, Subhendu; Tiwari, P K; Misra, A K; Chattopadhyay, J

2015-06-01

The production of toxins by some species of phytoplankton is known to have several economic, ecological, and human health impacts. However, the role of toxins on the spatial distribution of phytoplankton is not well understood. In the present study, the spatial dynamics of a nutrient-phytoplankton system with toxic effect on phytoplankton is investigated. We analyze the linear stability of the system and obtain the condition for Turing instability. In the presence of toxic effect, we find that the distribution of nutrient and phytoplankton becomes inhomogeneous in space and results in different patterns, like stripes, spots, and the mixture of them depending on the toxicity level. We also observe that the distribution of nutrient and phytoplankton shows spatiotemporal oscillation for certain toxicity level. Copyright © 2015 Elsevier Inc. All rights reserved.

Impact of Temperature and Nutrients on Carbon: Nutrient Tissue Stoichiometry of Submerged Aquatic Plants: An Experiment and Meta-Analysis.

PubMed

Velthuis, Mandy; van Deelen, Emma; van Donk, Ellen; Zhang, Peiyu; Bakker, Elisabeth S

2017-01-01

Human activity is currently changing our environment rapidly, with predicted temperature increases of 1-5°C over the coming century and increased nitrogen and phosphorus inputs in aquatic ecosystems. In the shallow parts of these ecosystems, submerged aquatic plants enhance water clarity by resource competition with phytoplankton, provide habitat, and serve as a food source for other organisms. The carbon:nutrient stoichiometry of submerged aquatic plants can be affected by changes in both temperature and nutrient availability. We hypothesized that elevated temperature leads to higher carbon:nutrient ratios through enhanced nutrient-use efficiency, while nutrient addition leads to lower carbon:nutrient ratios by the luxurious uptake of nutrients. We addressed these hypotheses with an experimental and a meta-analytical approach. We performed a full-factorial microcosm experiment with the freshwater plant Elodea nuttallii grown at 10, 15, 20, and 25°C on sediment consisting of pond soil/sand mixtures with 100, 50, 25, and 12.5% pond soil. To address the effect of climatic warming and nutrient addition on the carbon:nutrient stoichiometry of submerged freshwater and marine plants we performed a meta-analysis on experimental studies that elevated temperature and/or added nutrients (nitrogen and phosphorus). In the microcosm experiment, C:N ratios of Elodea nuttallii decreased with increasing temperature, and this effect was most pronounced at intermediate nutrient availability. Furthermore, higher nutrient availability led to decreased aboveground C:P ratios. In the meta-analysis, nutrient addition led to a 25, 22, and 16% reduction in aboveground C:N and C:P ratios and belowground C:N ratios, accompanied with increased N content. No consistent effect of elevated temperature on plant stoichiometry could be observed, as very few studies were found on this topic and contrasting results were reported. We conclude that while nutrient addition consistently leads to

Use of nutrient supplements to increase the microbial degradation of PAH in contaminated soils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carmichael, L.M.; Pfaender, F.K.

1994-12-31

The microbial degradation of polycyclic aromatic hydrocarbons (PAH) is often low in soils due to unavailability of PAH and/or to conditions in the soil that are not favorable to microbial activity. As a result, successful bioremediation of PAH contaminated soils may require the addition of supplements to impact PAH availability or soil conditions. This paper reports on the addition of supplements (Triton X-100, Inopol, nutrient buffer, an organic nutrient solution, salicylic acid) on the fate of (9-{sup 14}C) phenanthrene, a model PAH, in creosote contaminated soils. Phenanthrene metabolism was assessed using a mass balance approach that accounts for metabolism ofmore » phenanthrene to CO{sub 2}, relative metabolite production, and uptake of phenanthrene into cells. Most of the supplements did not drastically alter the fate of phenanthrene in the contaminated soils. Additions of Inopol, however, increased phenanthrene mineralization, while salicylic acid decreased phenanthrene mineralization but greatly increased the production of polar and water soluble metabolites. All supplements (excluding salicylic acid and the organic nutrient solution) increased populations of heterotrophic microorganisms, as measured by plate counts. Phenanthrene degrader populations, however, were only slightly increased by additions of the nutrient buffer, as measured by the Most Probable Number assay.« less

Optimization of pilot high rate algal ponds for simultaneous nutrient removal and lipids production.

PubMed

Arbib, Zouhayr; de Godos, Ignacio; Ruiz, Jesús; Perales, José A

2017-07-01

Special attention is required to the removal of nitrogen and phosphorous in treated wastewaters. Although, there are a wide range of techniques commercially available for nutrient up-take, these processes entail high investment and operational costs. In the other hand, microalgae growth can simultaneously remove inorganic constituents of wastewater and produce energy rich biomass. Among all the cultivation technologies, High Rate Algae Ponds (HRAPs), are accepted as the most appropriate system. However, the optimization of the operation that maximizes the productivity, nutrient removal and lipid content in the biomass generated has not been established. In this study, the effect of two levels of depth and the addition of CO 2 were evaluated. Batch essays were used for the calculation of the kinetic parameters of microbial growth that determine the optimum conditions for continuous operation. Nutrient removal and lipid content of the biomass generated were analyzed. The best conditions were found at depth of 0.3m with CO 2 addition (biomass productivity of 26.2gTSSm -2 d -1 and a lipid productivity of 6.0glipidsm -2 d -1 ) in continuous mode. The concentration of nutrients was in all cases below discharge limits established by the most restrictive regulation for wastewater discharge. Copyright © 2017 Elsevier B.V. All rights reserved.

Explanatory characteristics for nutrient concentrations and loads in the Sava River Catchment and cross-regionally

NASA Astrophysics Data System (ADS)

Levi, L.; Cvetkovic, V.; Destouni, G.

2015-12-01

This study compiles estimates of waterborne nutrient concentrations and loads in the Sava River Catchment (SRC). Based on this compilation, we investigate hotspots of nutrient inputs and retention along the river, as well as concentration and load correlations with river discharge and various human drivers of excess nutrient inputs to the SRC. For cross-regional assessment and possible generalization, we also compare corresponding results between the SRC and the Baltic Sea Drainage Basin (BSDB). In the SRC, one small incremental subcatchment, which is located just downstream of Zagreb and has the highest population density among the SRC subcatchments, is identified as a major hotspot for net loading (input minus retention) of both total nitrogen (TN) and total phosphorus (TP) to the river and through it to downstream areas of the SRC. The other SRC subcatchments exhibit relatively similar characteristics with smaller net nutrient loading. The annual loads of both TN and TP along the Sava River exhibit dominant temporal variability with considerably higher correlation with annual river discharge (R2 = 0.51 and 0.28, respectively) than that of annual average nutrient concentrations (R2 = 0.0 versus discharge for both TN and TP). Nutrient concentrations exhibit instead dominant spatial variability with relatively high correlation with population density among the SRC subcatchments (R2=0.43-0.64). These SRC correlation characteristics compare well with corresponding ones for the BSDB, even though the two regions are quite different in their hydroclimatic, agricultural and wastewater treatment conditions. Such cross-regional consistency in dominant variability type and explanatory catchment characteristics may be a useful generalization basis, worthy of further investigation, for at least first-order estimation of nutrient concentration and load conditions in less data-rich regions.

The Chlorella vulgaris S-Nitrosoproteome under Nitrogen-Replete and -Deplete Conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Henard, Calvin A.; Guarnieri, Michael T.; Knoshaug, Eric P.

Oleaginous microalgae synthesize and accumulate large quantities of lipids that are promising feedstocks for the production of biofuels (Hu et al., 2008; Williams and Laurens, 2010; Day et al., 2012; Quinn and Davis, 2015). The algal species Chlorella vulgaris accumulates triacylglycerides that dominate its cellular composition (>60% lipid based on dry cell weight) when cultured in medium lacking a nitrogen source (Guarnieri et al., 2011; Ikaran et al., 2015), which is a 'lipid trigger' in an array of microalgae. As such, C. vulgaris represents a model algal species for examination of lipid accumulation mechanisms and a potential deployment organism inmore » industrial algal biofuels applications. C. vulgaris has been extensively characterized biochemically and physiologically (Converti et al., 2009; Liang et al., 2009), and de novo-generated transcriptomic and proteomic datasets have indicated that post-transcriptional and -translational mechanisms likely govern lipid accumulation in response to nitrogen starvation (Guarnieri et al., 2011, 2013). However, the specific mechanisms underlying lipid biosynthesis in response to nitrogen stress remain elusive.« less

The Chlorella vulgaris S-Nitrosoproteome under Nitrogen-Replete and -Deplete Conditions

DOE PAGES

Henard, Calvin A.; Guarnieri, Michael T.; Knoshaug, Eric P.

2017-01-17

Oleaginous microalgae synthesize and accumulate large quantities of lipids that are promising feedstocks for the production of biofuels (Hu et al., 2008; Williams and Laurens, 2010; Day et al., 2012; Quinn and Davis, 2015). The algal species Chlorella vulgaris accumulates triacylglycerides that dominate its cellular composition (>60% lipid based on dry cell weight) when cultured in medium lacking a nitrogen source (Guarnieri et al., 2011; Ikaran et al., 2015), which is a 'lipid trigger' in an array of microalgae. As such, C. vulgaris represents a model algal species for examination of lipid accumulation mechanisms and a potential deployment organism inmore » industrial algal biofuels applications. C. vulgaris has been extensively characterized biochemically and physiologically (Converti et al., 2009; Liang et al., 2009), and de novo-generated transcriptomic and proteomic datasets have indicated that post-transcriptional and -translational mechanisms likely govern lipid accumulation in response to nitrogen starvation (Guarnieri et al., 2011, 2013). However, the specific mechanisms underlying lipid biosynthesis in response to nitrogen stress remain elusive.« less

Differential response of carbon cycling to long-term nutrient input and altered hydrological conditions in a continental Canadian peatland

NASA Astrophysics Data System (ADS)

Berger, Sina; Praetzel, Leandra S. E.; Goebel, Marie; Blodau, Christian; Knorr, Klaus-Holger

2018-02-01

Peatlands play an important role in global carbon cycling, but their responses to long-term anthropogenically changed hydrologic conditions and nutrient infiltration are not well known. While experimental manipulation studies, e.g., fertilization or water table manipulations, exist on the plot scale, only few studies have addressed such factors under in situ conditions. Therefore, an ecological gradient from the center to the periphery of a continental Canadian peatland bordering a eutrophic water reservoir, as reflected by increasing nutrient input, enhanced water level fluctuations, and increasing coverage of vascular plants, was used for a case study of carbon cycling along a sequence of four differently altered sites. We monitored carbon dioxide (CO2) and methane (CH4) surface fluxes and dissolved inorganic carbon (DIC) and CH4 concentrations in peat profiles from April 2014 through September 2015. Moreover, we studied bulk peat and pore-water quality and we applied δ13C-CH4 and δ13C-CO2 stable isotope abundance analyses to examine dominant CH4 production and emission pathways during the growing season of 2015. We observed differential responses of carbon cycling at the four sites, presumably driven by abundances of plant functional types and vicinity to the reservoir. A shrub-dominated site in close vicinity to the reservoir was a comparably weak sink for CO2 (in 1.5 years: -1093 ± 794, in 1 year: +135 ± 281 g CO2 m-2; a net release) as compared to two graminoid-moss-dominated sites and a moss-dominated site (in 1.5 years: -1552 to -2260 g CO2 m-2, in 1 year: -896 to -1282 g CO2 m-2). Also, the shrub-dominated site featured notably low DIC pore-water concentrations and comparably 13C-enriched CH4 (δ13C- CH4: -57.81 ± 7.03 ‰) and depleted CO2 (δ13C-CO2: -15.85 ± 3.61 ‰) in a more decomposed peat, suggesting a higher share of CH4 oxidation and differences in predominant methanogenic pathways. In comparison to all other sites, the graminoid

Pilot Plant Demonstration of Stable and Efficient High Rate Biological Nutrient Removal with Low Dissolved Oxygen Conditions

EPA Science Inventory

Aeration in biological nutrient removal (BNR) processes accounts for nearly half of the total electricity costs at many wastewater treatment plants. Even though conventional BNR processes are usually operated to have aerated zones with high dissolved oxygen (DO) concentrations, r...

What’s Upstream? GIS’s critical role in developing nutrient reference conditions for estuaries - April 2, 2015

EPA Science Inventory

Eutrophication due to excess levels of nitrogen and phosphorus can seriously impair ecological function in estuaries. Protective criteria for nutrients are difficult to establish because the source can vary spatially and seasonally, originate either from the watershed or the oce...

CADDIS Volume 2. Sources, Stressors and Responses: Nutrients

EPA Pesticide Factsheets

Introduction to the nutrients module, when to list nutrients as a candidate cause, ways to measure nutrients, simple and detailed conceptual diagrams for nutrients, nutrients module references and literature reviews.

Ecophysiological and metabolic responses to interactive exposure to nutrients and copper excess in the brown macroalga Cystoseira tamariscifolia.

PubMed

Celis-Plá, Paula S M; Brown, Murray T; Santillán-Sarmiento, Alex; Korbee, Nathalie; Sáez, Claudio A; Figueroa, Félix L

2018-03-01

Global scenarios evidence that contamination due to anthropogenic activities occur at different spatial-temporal scales, being important stressors: eutrophication, due to increased nutrient inputs; and metal pollution, mostly derived from industrial activities. In this study, we investigated ecophysiological and metabolic responses to copper and nutrient excess in the brown macroalga Cystoseira tamariscifolia. Whole plants were incubated in an indoor system under control conditions, two levels of nominal copper (0.5 and 2.0μM), and two levels of nutrient supply for two weeks. Maximal quantum yield (F v /F m ) and maximal electron transport rate (ETR max ) increased under copper exposure. Photosynthetic pigments and phenolic compounds (PC) increased under the highest copper levels. The intra-cellular copper content increased under high copper exposure in both nutrient conditions. C. tamariscifolia from the Atlantic displayed efficient metal exclusion mechanisms, since most of the total copper accumulated by the cell was bound to the cell wall. Copyright © 2018 Elsevier Ltd. All rights reserved.

Nutrient starvation leading to triglyceride accumulation activates the Entner Doudoroff pathway in Rhodococcus jostii RHA1.

PubMed

Juarez, Antonio; Villa, Juan A; Lanza, Val F; Lázaro, Beatriz; de la Cruz, Fernando; Alvarez, Héctor M; Moncalián, Gabriel

2017-02-27

Rhodococcus jostii RHA1 and other actinobacteria accumulate triglycerides (TAG) under nutrient starvation. This property has an important biotechnological potential in the production of sustainable oils. To gain insight into the metabolic pathways involved in TAG accumulation, we analysed the transcriptome of R jostii RHA1 under nutrient-limiting conditions. We correlate these physiological conditions with significant changes in cell physiology. The main consequence was a global switch from catabolic to anabolic pathways. Interestingly, the Entner-Doudoroff (ED) pathway was upregulated in detriment of the glycolysis or pentose phosphate pathways. ED induction was independent of the carbon source (either gluconate or glucose). Some of the diacylglycerol acyltransferase genes involved in the last step of the Kennedy pathway were also upregulated. A common feature of the promoter region of most upregulated genes was the presence of a consensus binding sequence for the cAMP-dependent CRP regulator. This is the first experimental observation of an ED shift under nutrient starvation conditions. Knowledge of this switch could help in the design of metabolomic approaches to optimize carbon derivation for single cell oil production.

Real-time nutrient monitoring in rivers: adaptive sampling strategies, technological challenges and future directions

NASA Astrophysics Data System (ADS)

Blaen, Phillip; Khamis, Kieran; Lloyd, Charlotte; Bradley, Chris

2016-04-01

Excessive nutrient concentrations in river waters threaten aquatic ecosystem functioning and can pose substantial risks to human health. Robust monitoring strategies are therefore required to generate reliable estimates of river nutrient loads and to improve understanding of the catchment processes that drive spatiotemporal patterns in nutrient fluxes. Furthermore, these data are vital for prediction of future trends under changing environmental conditions and thus the development of appropriate mitigation measures. In recent years, technological developments have led to an increase in the use of continuous in-situ nutrient analysers, which enable measurements at far higher temporal resolutions than can be achieved with discrete sampling and subsequent laboratory analysis. However, such instruments can be costly to run and difficult to maintain (e.g. due to high power consumption and memory requirements), leading to trade-offs between temporal and spatial monitoring resolutions. Here, we highlight how adaptive monitoring strategies, comprising a mixture of temporal sample frequencies controlled by one or more 'trigger variables' (e.g. river stage, turbidity, or nutrient concentration), can advance our understanding of catchment nutrient dynamics while simultaneously overcoming many of the practical and economic challenges encountered in typical in-situ river nutrient monitoring applications. We present examples of short-term variability in river nutrient dynamics, driven by complex catchment behaviour, which support our case for the development of monitoring systems that can adapt in real-time to rapid environmental changes. In addition, we discuss the advantages and disadvantages of current nutrient monitoring techniques, and suggest new research directions based on emerging technologies and highlight how these might improve: 1) monitoring strategies, and 2) understanding of linkages between catchment processes and river nutrient fluxes.

Nutrient and phytoplankton analysis of a Mediterranean coastal area.

PubMed

Sebastiá, M T; Rodilla, M

2013-01-01

Identifying and quantifying the key anthropogenic nutrient input sources are essential to adopting management measures that can target input for maximum effect in controlling the phytoplankton biomass. In this study, three systems characterized by distinctive main nutrient sources were sampled along a Mediterranean coast transect. These sources were groundwater discharge in the Ahuir area, the Serpis river discharge in the Venecia area, and a submarine wastewater outfall 1,900 m from the coast. The study area includes factors considered important in determining a coastal area as a sensitive area: it has significant nutrient sources, tourism is a major source of income in the region, and it includes an area of high water residence time (Venecia area) which is affected by the harbor facilities and by wastewater discharges. We found that in the Ahuir and the submarine wastewater outfall areas, the effects of freshwater inputs were reduced because of a greater water exchange with the oligotrophic Mediterranean waters. On the other hand, in the Venecia area, the highest levels of nutrient concentration and phytoplankton biomass were attributed to the greatest water residence time. In this enclosed area, harmful dinoflagellates were detected (Alexandrium sp. and Dinophysis caudata). If the planned enlargement of the Gandia Harbor proceeds, it may increase the vulnerability of this system and provide the proper conditions of confinement for the dinoflagellate blooms' development. Management measures should first target phosphorus inputs as this is the most potential-limiting nutrient in the Venecia area and comes from a point source that is easier to control. Finally, we recommend that harbor environmental management plans include regular monitoring of water quality in adjacent waters to identify adverse phytoplankton community changes.

Nutrients and Narragansett Bay

EPA Science Inventory

Narragansett Bay has been heavily fertilized by anthropogenic nutrients for almost 120 years. This presentation discusses the first introductions of human sources of nutrients to the Bay, via sewage and urban runoff, in the late 1890s through to the recent reductions in sewage ef...

Upland and in-stream controls on baseflow nutrient dynamics in tile-drained agroecosystem watersheds

NASA Astrophysics Data System (ADS)

Ford, William I.; King, Kevin; Williams, Mark R.

2018-01-01

In landscapes with low residence times (e.g., rivers and reservoirs), baseflow nutrient concentration dynamics during sensitive timeframes can contribute to deleterious environmental conditions downstream. This study assessed upland and in-stream controls on baseflow nutrient concentrations in a low-gradient, tile-drained agroecosystem watershed. We conducted time-series analysis using Empirical mode decomposition of seven decade-long nutrient concentration time-series in the agricultural Upper Big Walnut Creek watershed (Ohio, USA). Four tributaries of varying drainage areas and three main-stem sites were monitored, and nutrient grab samples were collected weekly from 2006 to 2016 and analyzed for dissolved reactive phosphorus (DRP), nitrate-nitrogen (NO3-N), total nitrogen (TN), and total phosphorus (TP). Statistically significant seasonal fluctuations were compared with seasonality of baseflow, watershed characteristics (e.g., tile-drain density), and in-stream water quality parameters (pH, DO, temperature). Findings point to statistically significant seasonality of all parameters with peak P concentrations in summer and peak N in late winter-early spring. Results suggest that upland processes exert strong control on DRP concentrations in the winter and spring months, while coupled upland and in-stream conditions control watershed baseflow DRP concentrations during summer and early fall. Conversely, upland flow sources driving streamflow exert strong control on baseflow NO3-N, and in-stream attenuation through transient and permanent pathways impacts the magnitude of removal. Regarding TN and TP, we found that TN was governed by NO3-N, while TP was governed by DRP in summer and fluvial erosion of P-rich benthic sediments during higher baseflow conditions. Findings of the study highlight the importance of coupled in-stream and upland management for mitigating eutrophic conditions during environmentally sensitive timeframes.

Decomposition of jellyfish carrion in situ: Short-term impacts on infauna, benthic nutrient fluxes and sediment redox conditions.

PubMed

Chelsky, Ariella; Pitt, Kylie A; Ferguson, Angus J P; Bennett, William W; Teasdale, Peter R; Welsh, David T

2016-10-01

Jellyfish often form blooms that persist for weeks to months before they collapse en masse, resulting in the sudden release of large amounts of organic matter to the environment. This study investigated the biogeochemical and ecological effects of the decomposition of jellyfish in a shallow coastal lagoon in New South Wales, Australia. Catostylus mosaicus carrion was added to the surface of shallow sub-tidal sediments and biogeochemical parameters and macrofaunal abundance immediately below the jellyfish carrion were measured over three days. Sediment plots without jellyfish served as controls. Sediment oxygen demand and carbon and nitrogen efflux increased by up to 60-fold in the jellyfish plots, compared to control plots, and dissolved organic nutrient fluxes were more sustained than in previous studies due to the use of fresh rather than frozen biomass. The decomposing jellyfish progressively altered sediment redox conditions, indicated by an increase in porewater iron (II) and sulfide concentrations measured by high-resolution in situ diffusive samplers. Abundance of some macrofaunal taxa in the jellyfish plots decreased relative to controls, however, the abundance of a carnivorous gastropod, which was presumably feeding on the carrion, increased in the jellyfish plots. While jellyfish carrion may be a food source for some macrofauna, low oxygen conditions coupled with the accumulation of toxic dissolved sulfides in the near-surface sediments may explain the overall change in the macroinfaunal community. Copyright © 2016 Elsevier B.V. All rights reserved.

Siletz River nutrients: Effects of biosolids application

EPA Science Inventory

Stream water nutrients were measured in the Siletz River, Oregon, with the goal of comparing dissolved nutrient concentrations, primarily the nitrogenous nutrients nitrate and ammonium, with previously collected data for the Yaquina and Alsea Rivers for the nutrient criteria prog...

Drug-nutrient interactions in transplant recipients.

PubMed

Chan, L N

2001-01-01

Drug-nutrient interaction refers to an alteration of kinetics or dynamics of a drug or a nutritional element, or a compromise in nutritional status as a result of the addition of a drug. The potentials for drug-nutrient interaction increase with the number of drugs taken by the patient. Organ transplant recipients are therefore at high risk for drug-nutrient interactions because multiple medications are used to manage graft rejection, opportunistic infections, and other associated complications. Unrecognized or unmanaged drug-nutrient interactions in this patient population can have an adverse impact on their outcomes. This paper reviews the importance of recognizing drug-nutrient interaction when using cyclosporine-based regimens.

Lake nutrient stoichiometry is less predictable than nutrient concentrations at regional and sub-continental scales.

PubMed

Collins, Sarah M; Oliver, Samantha K; Lapierre, Jean-Francois; Stanley, Emily H; Jones, John R; Wagner, Tyler; Soranno, Patricia A

2017-07-01

Production in many ecosystems is co-limited by multiple elements. While a known suite of drivers associated with nutrient sources, nutrient transport, and internal processing controls concentrations of phosphorus (P) and nitrogen (N) in lakes, much less is known about whether the drivers of single nutrient concentrations can also explain spatial or temporal variation in lake N:P stoichiometry. Predicting stoichiometry might be more complex than predicting concentrations of individual elements because some drivers have similar relationships with N and P, leading to a weak relationship with their ratio. Further, the dominant controls on elemental concentrations likely vary across regions, resulting in context dependent relationships between drivers, lake nutrients and their ratios. Here, we examine whether known drivers of N and P concentrations can explain variation in N:P stoichiometry, and whether explaining variation in stoichiometry differs across regions. We examined drivers of N:P in ~2,700 lakes at a sub-continental scale and two large regions nested within the sub-continental study area that have contrasting ecological context, including differences in the dominant type of land cover (agriculture vs. forest). At the sub-continental scale, lake nutrient concentrations were correlated with nutrient loading and lake internal processing, but stoichiometry was only weakly correlated to drivers of lake nutrients. At the regional scale, drivers that explained variation in nutrients and stoichiometry differed between regions. In the Midwestern U.S. region, dominated by agricultural land use, lake depth and the percentage of row crop agriculture were strong predictors of stoichiometry because only phosphorus was related to lake depth and only nitrogen was related to the percentage of row crop agriculture. In contrast, all drivers were related to N and P in similar ways in the Northeastern U.S. region, leading to weak relationships between drivers and stoichiometry

A novel nanoparticle approach for imaging nutrient uptake by soil bacteria

NASA Astrophysics Data System (ADS)

O'Brien, S. L.; Whiteside, M. D.; Sholto-Douglas, D.; Antonopoulos, D. A.; Boyanov, M.; Durall, D. M.; Jones, M. D.; Lai, B.; O'Loughlin, E. J.; Kemner, K. M.

2014-12-01

The metabolic activities of soil microbes are the primary drivers of biogeochemical processes controlling the terrestrial carbon cycle, nutrient availability to plants, contaminant remediation, water quality, and other ecosystem services. However, we have a limited understanding of microbial metabolic processes such as nutrient uptake rates, substrate preferences, or how microbes and microbial metabolism are distributed throughout their habitat. Here we use a novel imaging technique with quantum dots (QDs, engineered semiconductor nanoparticles that produce size or composition-dependent fluorescence) to measure bacterial uptake of substrates of varying complexity. Cultures of two organisms differing in cell wall structure — Bacillus subtilis and Pseudomonas fluorescens — were grown in one of four ecologically relevant experimental conditions: nitrogen (N) limitation, phosphorus (P) limitation, N and P limitation, or no nutrient limitation. The cultures were then exposed to QDs with and without organic nutrients attached. X-ray fluorescence imaging was performed at 2ID-D at the Advanced Photon Source (APS) to determine the elemental distributions within both planktonic and surface-adhered (i.e, biofilms) cells. Uptake of unconjugated QDs was neglibible, and QDs conjugated to organic substrates varied depending on growth conditions and substrate, suggesting that they are a useful indicator of bacterial ecology. Cellular uptake was similar for the two bacterial species (2212 ± 273 nanoparticles per cm3 of cell volume for B. subtilis and 1682 ± 264 for P. fluorescens). On average, QD assimilation was six times greater when N or P was limiting, and cells took up about twice as much phosphoserine compared to other substrates, likely because it was the only compound providing both N and P. These results showed that regardless of their cell wall structure, bacteria can selectively take up quantifiable levels of QDs based on substrate and environmental conditions. APS

An evaluation of the sustainability of onsite wastewater treatment systems for nutrient management.

PubMed

Diaz-Elsayed, Nancy; Xu, Xiaofan; Balaguer-Barbosa, Maraida; Zhang, Qiong

2017-09-15

The impairment of water bodies from nutrient pollution is a challenging environmental problem that could lead to high eutrophic conditions, fish kills, and human illness, while negatively impacting industries that rely on thriving water bodies. Onsite wastewater treatment systems (OWTSs) are a major source of nutrients, however no prior studies have conducted a holistic sustainability assessment of OWTSs that considers their ability to manage nutrients at the household-level in the United States. The aim of this study is therefore to evaluate the environmental and economic impacts of conventional and advanced OWTSs with respect to their ability to remove total nitrogen (TN). Septic tank and drainfield materials were varied for conventional systems, and the advanced systems evaluated consisted of aerobic treatment units (ATUs) and passive nitrogen reduction systems (PNRSs) with nitrification and denitrification stages. Life cycle assessment and life cycle cost analysis were performed to evaluate OWTSs operating in different soil and temperature conditions. Nutrient management of the advanced OWTSs outperformed the conventional systems (96.7-100% vs. 61-65% TN removal), and resulted in less than 40% of the freshwater (0.06-0.14 vs. 0.37-0.40 kg P-eq/kg TN) and marine eutrophication (0.04-0.06 vs. 0.54-0.65 kg N-eq/kg TN). However, the tradeoff for nutrient management was higher life cycle costs ($101-$121 vs. $45-$58 USD 2015/kg TN) and environmental impacts for the remaining impact categories. Lastly, when the TN removed by the drainfield was <20%, the advanced system had lower impacts than conventional OWTSs across all impact categories except ecotoxicity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Relationships between nutrient enrichment, pleurocerid snail density and trematode infection rate in streams

USGS Publications Warehouse

Ciparis, Serena; Iwanowicz, Deborah D.; Voshell, J. Reese

2013-01-01

Summary 1. Nutrient enrichment is a widespread environmental problem in freshwater ecosystems. Eutrophic conditions caused by nutrient enrichment may result in a higher prevalence of infection by trematode parasites in host populations, due to greater resource availability for the molluscan first intermediate hosts. 2. This study examined relationships among land use, environmental variables indicating eutrophication, population density of the pleurocerid snail, Leptoxis carinata, and trematode infections. Fifteen study sites were located in streams within the Shenandoah River catchment (Virginia, U.S.A.), where widespread nutrient enrichment has occurred. 3. Snail population density had a weak positive relationship with stream water nutrient concentration. Snail population density also increased as human activities within stream catchments increased, but density did not continue to increase in catchments where anthropogenic disturbance was greatest. 4. Cercariae from five families of trematodes were identified in L. carinata, and infection rate was generally low (<10%). Neither total infection rate nor the infection rate of individual trematode types showed a positive relationship with snail population density, nutrients or land use. 5. There were statistically significant but weak relationships between the prevalence of infection by two trematode families and physical and biological variables. The prevalence of Notocotylidae was positively related to water depth, which may be related to habitat use by definitive hosts. Prevalence of Opecoelidae had a negative relationship with orthophosphate concentration and a polynomial relationship with chlorophyll a concentration. Transmission of Opecoelid trematodes between hosts may be inhibited by eutrophic conditions. 6. Leptoxis carinata appears to be a useful species for monitoring the biological effects of eutrophication and investigating trematode transmission dynamics in lotic systems.

Future nutrient load scenarios for the Baltic Sea due to climate and lifestyle changes.

PubMed

Hägg, Hanna Eriksson; Lyon, Steve W; Wällstedt, Teresia; Mörth, Carl-Magnus; Claremar, Björn; Humborg, Christoph

2014-04-01

Dynamic model simulations of the future climate and projections of future lifestyles within the Baltic Sea Drainage Basin (BSDB) were considered in this study to estimate potential trends in future nutrient loads to the Baltic Sea. Total nitrogen and total phosphorus loads were estimated using a simple proxy based only on human population (to account for nutrient sources) and stream discharges (to account for nutrient transport). This population-discharge proxy provided a good estimate for nutrient loads across the seven sub-basins of the BSDB considered. All climate scenarios considered here produced increased nutrient loads to the Baltic Sea over the next 100 years. There was variation between the climate scenarios such that sub-basin and regional differences were seen in future nutrient runoff depending on the climate model and scenario considered. Regardless, the results of this study indicate that changes in lifestyle brought about through shifts in consumption and population potentially overshadow the climate effects on future nutrient runoff for the entire BSDB. Regionally, however, lifestyle changes appear relatively more important in the southern regions of the BSDB while climatic changes appear more important in the northern regions with regards to future increases in nutrient loads. From a whole-ecosystem management perspective of the BSDB, this implies that implementation of improved and targeted management practices can still bring about improved conditions in the Baltic Sea in the face of a warmer and wetter future climate.

Octopamine connects nutrient cues to lipid metabolism upon nutrient deprivation.

PubMed

Tao, Jun; Ma, Yi-Cheng; Yang, Zhong-Shan; Zou, Cheng-Gang; Zhang, Ke-Qin

2016-05-01

Starvation is probably the most common stressful situation in nature. In vertebrates, elevation of the biogenic amine norepinephrine levels is common during starvation. However, the precise role of norepinephrine in nutrient deprivation remains largely unknown. We report that in the free-living nematode Caenorhabditis elegans, up-regulation of the biosynthesis of octopamine, the invertebrate counterpart of norepinephrine, serves as a mechanism to adapt to starvation. During nutrient deprivation, the nuclear receptor DAF-12, known to sense nutritional cues, up-regulates the expression of tbh-1 that encodes tyramine β-hydroxylase, a key enzyme for octopamine biosynthesis, in the RIC neurons. Octopamine induces the expression of the lipase gene lips-6 via its receptor SER-3 in the intestine. LIPS-6, in turn, elicits lipid mobilization. Our findings reveal that octopamine acts as an endocrine regulator linking nutrient cues to lipolysis to maintain energy homeostasis, and suggest that such a mechanism may be evolutionally conserved in diverse organisms.

Octopamine connects nutrient cues to lipid metabolism upon nutrient deprivation

PubMed Central

Tao, Jun; Ma, Yi-Cheng; Yang, Zhong-Shan; Zou, Cheng-Gang; Zhang, Ke-Qin

2016-01-01

Starvation is probably the most common stressful situation in nature. In vertebrates, elevation of the biogenic amine norepinephrine levels is common during starvation. However, the precise role of norepinephrine in nutrient deprivation remains largely unknown. We report that in the free-living nematode Caenorhabditis elegans, up-regulation of the biosynthesis of octopamine, the invertebrate counterpart of norepinephrine, serves as a mechanism to adapt to starvation. During nutrient deprivation, the nuclear receptor DAF-12, known to sense nutritional cues, up-regulates the expression of tbh-1 that encodes tyramine β-hydroxylase, a key enzyme for octopamine biosynthesis, in the RIC neurons. Octopamine induces the expression of the lipase gene lips-6 via its receptor SER-3 in the intestine. LIPS-6, in turn, elicits lipid mobilization. Our findings reveal that octopamine acts as an endocrine regulator linking nutrient cues to lipolysis to maintain energy homeostasis, and suggest that such a mechanism may be evolutionally conserved in diverse organisms. PMID:27386520

Eutrophication of Buttermilk Bay, a cape cod coastal embayment: Concentrations of nutrients and watershed nutrient budgets

NASA Astrophysics Data System (ADS)

Valiela, Ivan; Costa, Joseph E.

1988-07-01

Nutrient concentrations in Buttermilk Bay, a coastal embayment on the northern end of Buzzards Bay, MA, are higher in the nearshore where salinities are lower. This pattern suggests that freshwater sources may contribute significantly to nutrient inputs into Buttermilk Bay. To evaluate the relative importance of the various sources we estimated inputs of nutrients by each major source into the watershed and into the bay itself. Septic systems contributed about 40% of the nitrogen and phosphorus entering the watershed, with precipitation and fertilizer use adding the remainder. Groundwater transported over 85% of the nitrogen and 75% of the phosphorus entering the bay. Most nutrients entering the watershed failed to reach the bay; uptake by forests, soils, denitrification, and adsorption intercepted two-thirds of the nitrogen and nine-tenths of the phosphorus that entered the watershed. The nutrients that did reach the bay most likely originated from subsoil injections into groundwater by septic tanks, plus some leaching of fertilizers. Buttermilk Bay water has relatively low nutrient concentrations, probably because of uptake of nutrients by macrophytes and because of relatively rapid tidal flushing. Annual budgets of nutrients entering the watershed showed a low nitrogen-to-phosphorus ratio of 6, but passage of nutrients through the watershed raised N/P to 23, probably because of adsorption of PO4 during transit. The N/P ratio of water that leaves the watershed and presumably enters the bay is probably high enough to maintain active growth of nitrogenlimited coastal producers. There is a seasonal shift in N/P in the water column of Buttermilk Bay. N/P exceeded the 16∶1 Redfield ratio during midwinter; the remainder of the year N/P fell below 16∶1. This suggests that annual budgets do not provide sufficiently detailed data with which to interpret nutrient-limitation of producers. Further, some idea of water turnover is also needed to evaluate impact of loading

Sequential nutrient uptake as a potential mechanism for phytoplankton to maintain high primary productivity and balanced nutrient stoichiometry

NASA Astrophysics Data System (ADS)

Yin, Kedong; Liu, Hao; Harrison, Paul J.

2017-05-01

We hypothesize that phytoplankton have the sequential nutrient uptake strategy to maintain nutrient stoichiometry and high primary productivity in the water column. According to this hypothesis, phytoplankton take up the most limiting nutrient first until depletion, continue to draw down non-limiting nutrients and then take up the most limiting nutrient rapidly when it is available. These processes would result in the variation of ambient nutrient ratios in the water column around the Redfield ratio. We used high-resolution continuous vertical profiles of nutrients, nutrient ratios and on-board ship incubation experiments to test this hypothesis in the Strait of Georgia. At the surface in summer, ambient NO3- was depleted with excess PO43- and SiO4- remaining, and as a result, both N : P and N : Si ratios were low. The two ratios increased to about 10 : 1 and 0. 45 : 1, respectively, at 20 m. Time series of vertical profiles showed that the leftover PO43- continued to be removed, resulting in additional phosphorus storage by phytoplankton. The N : P ratios at the nutricline in vertical profiles responded differently to mixing events. Field incubation of seawater samples also demonstrated the sequential uptake of NO3- (the most limiting nutrient) and then PO43- and SiO4- (the non-limiting nutrients). This sequential uptake strategy allows phytoplankton to acquire additional cellular phosphorus and silicon when they are available and wait for nitrogen to become available through frequent mixing of NO3- (or pulsed regenerated NH4). Thus, phytoplankton are able to maintain high productivity and balance nutrient stoichiometry by taking advantage of vigorous mixing regimes with the capacity of the stoichiometric plasticity. To our knowledge, this is the first study to show the in situ dynamics of continuous vertical profiles of N : P and N : Si ratios, which can provide insight into the in situ dynamics of nutrient stoichiometry in the water column and the inference of

Phytoplankton Diversity Effects on Community Biomass and Stability along Nutrient Gradients in a Eutrophic Lake

PubMed Central

Tian, Wang; Zhang, Huayong; Zhao, Lei; Zhang, Feifan; Huang, Hai

2017-01-01

The relationship between biodiversity and ecosystem functioning is a central issue in ecology, but how this relationship is affected by nutrient stress is still unknown. In this study, we analyzed the phytoplankton diversity effects on community biomass and stability along nutrient gradients in an artificial eutrophic lake. Four nutrient gradients, varying from slightly eutrophic to highly eutrophic states, were designed by adjusting the amount of polluted water that flowed into the lake. Mean phytoplankton biomass, species richness, and Shannon diversity index all showed significant differences among the four nutrient gradients. Phytoplankton community biomass was correlated with diversity (both species richness and Shannon diversity index), varying from positive to negative along the nutrient gradients. The influence of phytoplankton species richness on resource use efficiency (RUE) also changed from positive to negative along the nutrient gradients. However, the influence of phytoplankton Shannon diversity on RUE was not significant. Both phytoplankton species richness and Shannon diversity had a negative influence on community turnover (measured as community dissimilarity), i.e., a positive diversity–stability relationship. Furthermore, phytoplankton spatial stability decreased along the nutrient gradients in the lake. With increasing nutrient concentrations, the variability (standard deviation) of phytoplankton community biomass increased more rapidly than the average total biomass. Results in this study will be helpful in understanding the phytoplankton diversity effects on ecosystem functioning and how these effects are influenced by nutrient conditions in aquatic ecosystems. PMID:28117684

Effect of imbalanced nutrients and immigration on Prymnesium parvum community dominance and toxicity: Results from in-lake microcosm experiments

USGS Publications Warehouse

Errera, R.M.; Roelke, D.L.; Kiesling, R.L.; Brooks, B.W.; Grover, J.P.; Schwierzke, L.; Urena-Boeck, F.; Baker, J.W.; Pinckney, J.L.

2008-01-01

Prymnesium parvum, a haptophyte species, forms harmful blooms, including those that have caused severe fish kills in Texas, USA, over the past 6 yr. We studied P. parvum dynamics using in situ microcosm experiments at Lake Possum Kingdom, Texas, during 3 seasons (fall 2004, winter and spring 2005). Experimental treatments included full and partial nutrient enrichment (encompassing nitrogen [N] and phosphorus [P] deficient treatments), P. parvum immigration and combinations of these factors. In the control and N and P deficient treatments, P. parvum populations dominated the community, but only in the N deficient treatments did P. parvum experience a significant growth in the population. In contrast, when nutrients were not limiting, P. parvum tended to lose its competitive edge to other taxa such as chlorophytes, euglenophytes and diatoms, which then dominated the community. Population growth of P. parvum was also stimulated through immigration, but only during the winter experiment, a period of the year when bloom initiation is common. This finding suggests that movement into the water column may be an important process leading to P. parvum bloom initiation. Toxicity of P. parvum to fish was also affected by the nutrient changes: during conditions of no nutrient addition P. parvum was most toxic; intermediate toxicity was observed under N and P deficient conditions, and full nutrient enrichments resulted in nearly non-toxic conditions. ?? Inter-Research 2008.

Research to Inform Nutrient Thresholds and Prioritization of ...

EPA Pesticide Factsheets

The information in this presentation focuses on SSWR's 4.02 project, which will advance the science needed to inform decisions to prioritize watersheds and nutrient sources for nutrient management and define appropriate nutrient levels for the nation’s waters, two important elements of EPA’s framework for managing nutrient pollution. The information in this presentation focuses on SSWR's 4.02 project, which will advance the science needed to inform decisions to prioritize watersheds and nutrient sources for nutrient management and define appropriate nutrient levels for the nation’s waters, two important elements of EPA’s framework for managing nutrient pollution.

Relationship between soil nutrients and mycorrhizal associations of two Bipinnula species (Orchidaceae) from central Chile

PubMed Central

Mujica, María Isabel; Saez, Nicolás; Cisternas, Mauricio; Manzano, Marlene; Armesto, Juan J.; Pérez, Fernanda

2016-01-01

Background and Aims Mycorrhizal associations are influenced by abiotic and biotic factors, including climate, soil conditions and the identity of host plants. However, the effect of environmental conditions on orchid mycorrhizal associations remains poorly understood. The present study examined how differences in soil nutrient availability are related to the diversity and composition of mycorrhizal fungi associated with two terrestrial orchid species from central Chile. Methods For 12 populations of Bipinnula fimbriata and B. plumosa, OTU (operational taxonomic unit) richness, phylogenetic diversity and community composition of mycorrhizal fungi in root samples were estimated using internal transcribed spacer (ITS) sequences. Then, these mycorrhizal diversity variables were related to soil nutrients and host species using generalized linear models and non-metric multidimensional scaling. Key Results Variation in OTU composition of mycorrhizal fungi among sites was explained mainly by orchid host species. Fungi in Tulasnellaceae and Ceratobasidiaceae were isolated from both orchid species, but the former were more frequent in B. fimbriata and the latter in B. plumosa. Soil nutrients and orchid host species had significant effects on OTU richness and phylogenetic diversity. Mycorrhizal diversity decreased in habitats with higher N in both species and increased with P availability only in B. fimbriata. Conclusions The results suggest that soil nutrient availability modulates orchid mycorrhizal associations and provide support for the hypothesis that specialization is favoured by higher soil nutrient availability. Inter-specific differences in mycorrhizal composition can arise due to a geographical pattern of distribution of orchid mycorrhizal fungi, host preferences for fungal partners or differential performance of mycorrhizal fungi under different nutrient availabilities. Further experiments are needed to evaluate these hypotheses. PMID:27311572

Phytoplankton productivity, respiration, and nutrient uptake and regeneration in the Potomac River, August 1977 - August 1978

USGS Publications Warehouse

Cole, B.E.; Harmon, D.D.

1981-01-01

Rates of phytoplankton productivity, respiration, and nutrient uptake and regeneration are presented. These observations were made on the Potomac River estuary (POTE) during four cruises between August 1977 and August 1978. Four experimental methods were used: carbon uptake using carbon-14, carbon uptake and respiration by a pH method, productivity and respiration by the dissolved oxygen method, and nutrient (NH4+, NO3-, NO2-, PO4=, and SiO2=) uptake and regeneration by colorimetry. The experiments were made at sites representative of conditions in four principal reaches of the tidal Potomac River estuary: near the mouth, seaward of the summer nutrient and phytoplankton maximum, near the region of maximum phytoplankton standing stock , and near the maximum anthropogenic nutrient source. (USGS)

Nutrient concentrations within and below root zones from applied chicken manure in selected Hawaiian soils.

PubMed

Ahmad, Amjad A; Fares, Ali; Abbas, Farhat; Deenik, Jonathan L

2009-11-01

The objective of this study was to evaluate the effects of chicken manure (CM) application rates on nutrient concentrations within and below the root zone of sweet corn (Zea mays L. subsp. mays) under Hawaiian conditions. The research was conducted in leeward (Poamoho) and windward (Waimanalo) areas of Oahu, Hawaii, where contrasts exist in both climatic and soil conditions. Suction cup were used to collect soil solutions from 30 and 60 cm depths. Soil solutions were collected six times during the growing season at each location and analyzed for different nutrients (N, P, K, Ca, Mg, Na, Fe, Mn, Zn, and Cu), nitrate-nitrogen (NO(3)-N), ammonium-nitrogen (NH(4)-N), electrical conductivity (EC), and pH. Analysis showed that CM rates significantly affected the concentration of macro-nutrients below the root zone at Poamoho and within the root zone at Waimanalo. In general, nutrient concentration increased with the increasing rates of CM application. There was a significant effect of CM on micro-nutrients except below the root zone at Poamoho. CM significantly affected NO(3)-N concentration within the root zone for 15, 60 days after planting (DAP) at Poamoho, and 16, 28 DAP at Waimanalo. The effect was also significant on total nitrogen (N) concentration in the root zone across the two growing seasons at Waimanalo. There was a highly significant correlation between total N and NO(3)-N, and EC within and below the root zone.

Metabolic Reprogramming During Purine Stress in the Protozoan Pathogen Leishmania donovani

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, Jessica L.; Yates, Phillip A.; Soysa, Radika

The ability of Leishmania to survive in their insect or mammalian host is dependent upon an ability to sense and adapt to changes in the microenvironment. However, little is known about the molecular mechanisms underlying the parasite response to environmental changes, such as nutrient availability. To elucidate nutrient stress response pathways in Leishmania donovani, we have used purine starvation as the paradigm. The salvage of purines from the host milieu is obligatory for parasite replication; nevertheless, purine-starved parasites can persist in culture without supplementary purine for over 3 months, indicating that the response to purine starvation is robust and engendersmore » parasite survival under conditions of extreme scarcity. To understand metabolic reprogramming during purine starvation we have employed global approaches. Whole proteome comparisons between purine-starved and purine-replete parasites over a 6-48 h span have revealed a temporal and coordinated response to purine starvation. Purine transporters and enzymes involved in acquisition at the cell surface are upregulated within a few hours of purine removal from the media, while other key purine salvage components are upregulated later in the time-course and more modestly. After 48 h, the proteome of purine-starved parasites is extensively remodeled and adaptations to purine stress appear tailored to deal with both purine deprivation and general stress. To probe the molecular mechanisms affecting proteome remodeling in response to purine starvation, comparative RNA-seq analyses, qRT-PCR, and luciferase reporter assays were performed on purine-starved versus purine-replete parasites. While the regulation of a minority of proteins tracked with changes at the mRNA level, for many regulated proteins it appears that proteome remodeling during purine stress occurs primarily via translational and/or post-translational mechanisms.« less

Effects of hydrology on short term plant decomposition and nutrient content in a re-created Everglades wetland

NASA Astrophysics Data System (ADS)

Serna, A.; Richards, J.; Scinto, L.

2012-12-01

The effect of water depth and flow on tissue nutrients and decomposition rates of marsh plant species, and soil chemistry in vegetated plots was measured in the Loxahatchee Impoundment Landscape Assessment (LILA) facility in Boynton Beach, Florida, USA. The LILA facility consists of replicated wetland macrocosms that mimic Everglades ridge-and-slough landscape features. The experiments were conducted in two macrocosms that each had three habitats at different water depths (ridge, shallow slough and deep slough) but differed in flow. Decomposition rates of three common Everglades species, Cladium jamaicense (sawgrass), Eleocharis cellulosa (spikerush), and Nymphaea odorata (white water lily), were measured using litter bags incubated during both a wet and dry condition. Litter bag losses were more pronounced under wet conditions, and decomposition rates were not affected by the hydrologic conditions in this experiment, but rather by litter nutrient content and species. Litter nutrient (TC, TN, TP) concentrations varied over time. Species rich in the limiting nutrient (P) in the ecosystem decomposed faster. Therefore, N. odorata decomposed faster than C. jamaicense and E. cellulosa, confirming the importance of P availability in controlling microbial processes in the Everglades. Planted species had no effect on soil nutrient content over the 3 yrs period of plant growth in these plots. Our results have contributed to defining potential flow targets for restoration in Florida's Everglades by showing that average water velocities of 0.5 cm s-1 may not be sufficient to drive ecosystem changes in decomposition rates for the native species and soil chemistry.

Nutrient effects of broodstocks on the larvae in Patinopecten yessoensis

NASA Astrophysics Data System (ADS)

Bai, Yucen; Zhang, Tao; Qiu, Tianlong; Gao, Yan; Zhang, Xiaofang

2015-07-01

Patinopecten yessoensis is a commercial valuable species. This study deals with the effect of nutrient effects of the broodstock (mainly ovaries) on the larvae. Concentrations of total carbohydrate, total protein and total lipid in the gonads of P. yessoensis from three Hatcheries (Hatchery 1, Hatchery 2, and Hatchery 3) were determined before and after spawning. The relationship between the nutrient concentration in ovaries before spawning (BC) and that of larvae (LC) was assessed as well as the change in nutrient levels in ovaries after spawning (DC). Results indicate that the BC of total carbohydrate (7.66%) and total lipid (14.48%) in ovaries were significantly higher than in testes (5.20%, 5.20% respectively), whereas the BC of total protein in the ovaries was lower (61.76%) than in the testes (81.67%). The different gonadal composition suggests the different nutrient demands between male and female broodstocks in breeding season. Patinopecten yessoensis gonads contained a higher proportion of lipids, in comparison to other bivalves, which might be a response to the low ambient water temperatures. Further analysis of fatty acids showed that the concentrations of n-3PUFA, EPA and DHA in larvae (LC) were positively correlated with BC and DC, indicating the significant nutrient influence of broodstocks on the larvae. As these fatty acids are important in metabolism, and have been demonstrated to be influential to the viability of the larvae, larval growth and the settlement, spat growth, and juvenile survival in many bivalves, they could possibly be used as indexes to evaluate, and predict condition of broodstocks and larvae.

Nutrient cycling, connectivity, and free-floating plant abundance in backwater lakes of the Upper Mississippi River

USGS Publications Warehouse

Houser, Jeff N.; Giblin, Shawn M.; James, William F.; Langrehr, H.A.; Rogala, James T.; Sullivan, John F.; Gray, Brian R.

2013-01-01

River eutrophication may cause the formation of dense surface mats of free floating plants (FFP; e.g., duckweeds and filamentous algae) which may adversely affect the ecosystem. We investigated associations among hydraulic connectivity to the channel, nutrient cycling, FFP, submersed aquatic vegetation (SAV), and dissolved oxygen concentration (DO) in ten backwater lakes of the Upper Mississippi River (UMR) that varied in connectivity to the channel. Greater connectivity was associated with higher water column nitrate (NO3-N) concentration, higher rates of sediment phosphorus (P) release, and higher rates of NO3-N flux to the sediments. Rates of sediment P and N (as NH4-N) release were similar to those of eutrophic lakes. Water column nutrient concentrations were high, and FFP tissue was nutrient rich suggesting that the eutrophic condition of the UMR often facilitated abundant FFP. However, tissue nutrient concentrations, and the associations between FFP biomass and water column nutrient concentrations, suggested that nutrients constrained FFP abundance at some sites. FFP abundance was positively associated with SAV abundance and negatively associated with dissolved oxygen concentration. These results illustrate important connections among hydraulic connectivity, nutrient cycling, FFP, SAV, and DO in the backwaters of a large, floodplain river.

Nutrient foraging strategies are associated with productivity and population growth in forest shrubs.

PubMed

Caplan, Joshua S; Stone, Bram W G; Faillace, Cara A; Lafond, Jonathan J; Baumgarten, Joni M; Mozdzer, Thomas J; Dighton, John; Meiners, Scott J; Grabosky, Jason C; Ehrenfeld, Joan G

2017-04-01

Temperate deciduous forest understoreys are experiencing widespread changes in community composition, concurrent with increases in rates of nitrogen supply. These shifts in plant abundance may be driven by interspecific differences in nutrient foraging (i.e. conservative vs. acquisitive strategies) and, thus, adaptation to contemporary nutrient loading conditions. This study sought to determine if interspecific differences in nutrient foraging could help explain patterns of shrub success and decline in eastern North American forests. Using plants grown in a common garden, fine root traits associated with nutrient foraging were measured for six shrub species. Traits included the mean and skewness of the root diameter distribution, specific root length (SRL), C:N ratio, root tissue density, arbuscular mycorrhizal colonization and foraging precision. Above- and below-ground productivity were also determined for the same plants, and population growth rates were estimated using data from a long-term study of community dynamics. Root traits were compared among species and associations among root traits, measures of productivity and rates of population growth were evaluated. Species fell into groups having thick or thin root forms, which correspond to conservative vs. acquisitive nutrient foraging strategies. Interspecific variation in root morphology and tissue construction correlated with measures of productivity and rates of cover expansion. Of the four species with acquisitive traits, three were introduced species that have become invasive in recent decades, and the fourth was a weedy native. In contrast, the two species with conservative traits were historically dominant shrubs that have declined in abundance in eastern North American forests. In forest understoreys of eastern North America, elevated nutrient availability may impose a filter on species success in addition to above-ground processes such as herbivory and overstorey canopy conditions. Shrubs that have

Digital data used to relate nutrient inputs to water quality in the Chesapeake Bay watershed, version 3.0

USGS Publications Warehouse

Brakebill, John W.; Preston, Stephen D.

2004-01-01

atmospheric deposition, point-source locations, land-use, land-cover, and agricultural sources such as commercial fertilizer and manure applications. Watershed-characteristics datasets representing factors that affect the transport of nutrients also were compiled from previous applications of the SPARROW models in the Chesapeake Bay watershed. Datasets include average-annual precipitation and temperature, slope, soil permeability, and hydrogeomorphic regions. Nutrient-input and watershed-characteristics datasets representing conditions during the late 1990s were merged with a connected network of stream reaches and watersheds to provide the spatial detail required by SPARROW. Stream-nutrient load estimates for 125 sampling sites (87 for total nitrogen and 103 for total phosphorus) served as the dependent variables for the regressions, and were used to calibrate models of total nitrogen and total phosphorus depicting late 1990s conditions in the Chesapeake Bay watershed. Spatial data generated for the models can be used to identify the location of nutrient sources, while the models' nutrient estimates can be used to evaluate stream-nutrient load contributed locally by each source evaluated, the amount of local load generated that is transported to the Bay, and the factors that affect the nutrient transport. Applying the SPARROW methodology to late 1990s information completes three time periods (late 1980s, early 1990s, and late 1990s) of viable data that resource managers can use to evaluate the water-quality conditions within the Bay watershed in order to refine restoration goals and nutrient-reduction strategies.

Factors affecting nutrient trends in major rivers of the Chesapeake Bay Watershed

USGS Publications Warehouse

Sprague, Lori A.; Langland, M.J.; Yochum, S.E.; Edwards, R.E.; Blomquist, J.D.; Phillips, S.W.; Shenk, G.W.; Preston, S.D.

2000-01-01

watershed. The loads of nutrients, however, were not reduced significantly at most of the monitoring stations. This is due primarily to higher streamflow in the latter years of the monitoring period, which led to higher loading in those years.Results of this study indicate a need for more detailed information on BMP effectiveness under a full range of hydrologic conditions and in different areas of the watershed; an internally consistent fertilizer data set; greater consideration of the effects of watershed processes on nutrient transport; a refinement of current modeling efforts; and an expansion of the non-tidal monitoring network in the Chesapeake Bay Watershed.

Eliciting the mitochondrial unfolded protein response by nicotinamide adenine dinucleotide repletion reverses fatty liver disease in mice.

PubMed

Gariani, Karim; Menzies, Keir J; Ryu, Dongryeol; Wegner, Casey J; Wang, Xu; Ropelle, Eduardo R; Moullan, Norman; Zhang, Hongbo; Perino, Alessia; Lemos, Vera; Kim, Bohkyung; Park, Young-Ki; Piersigilli, Alessandra; Pham, Tho X; Yang, Yue; Ku, Chai Siah; Koo, Sung I; Fomitchova, Anna; Cantó, Carlos; Schoonjans, Kristina; Sauve, Anthony A; Lee, Ji-Young; Auwerx, Johan

2016-04-01

With no approved pharmacological treatment, nonalcoholic fatty liver disease (NAFLD) is now the most common cause of chronic liver disease in Western countries and its worldwide prevalence continues to increase along with the growing obesity epidemic. Here, we show that a high-fat high-sucrose (HFHS) diet, eliciting chronic hepatosteatosis resembling human fatty liver, lowers hepatic nicotinamide adenine dinucleotide (NAD(+) ) levels driving reductions in hepatic mitochondrial content, function, and adenosine triphosphate (ATP) levels, in conjunction with robust increases in hepatic weight, lipid content, and peroxidation in C57BL/6J mice. To assess the effect of NAD(+) repletion on the development of steatosis in mice, nicotinamide riboside, a precursor of NAD(+) biosynthesis, was added to the HFHS diet, either as a preventive strategy or as a therapeutic intervention. We demonstrate that NR prevents and reverts NAFLD by inducing a sirtuin (SIRT)1- and SIRT3-dependent mitochondrial unfolded protein response, triggering an adaptive mitohormetic pathway to increase hepatic β-oxidation and mitochondrial complex content and activity. The cell-autonomous beneficial component of NR treatment was revealed in liver-specific Sirt1 knockout mice (Sirt1(hep-/-) ), whereas apolipoprotein E-deficient mice (Apoe(-/-) ) challenged with a high-fat high-cholesterol diet affirmed the use of NR in other independent models of NAFLD. Our data warrant the future evaluation of NAD(+) boosting strategies to manage the development or progression of NAFLD. © 2015 The Authors. Hepatology published by Wiley Periodicals, Inc., on behalf of the American Association for the Study of Liver Diseases.

Long-term reductions in anthropogenic nutrients link to improvements in Chesapeake Bay habitat

USGS Publications Warehouse

Ruhl, H.; Rybicki, N.B.

2010-01-01

Great effort continues to focus on ecosystem restoration and reduction of nutrient inputs thought to be responsible, in part, for declines in estuary habitats worldwide. The ability of environmental policy to address restoration is limited, in part, by uncertainty in the relationships between costly restoration and benefits. Here, we present results from an 18-y field investigation (1990-2007) of submerged aquatic vegetation (SAV) community dynamics and water quality in the Potomac River, a major tributary of the Chesapeake Bay. River and anthropogenic discharges lower water clarity by introducing nutrients that stimulate phytoplankton and epiphyte growth as well as suspended sediments. Efforts to restore the Chesapeake Bay are often viewed as failing. Overall nutrient reduction and SAV restoration goals have not been met. In the Potomac River, however, reduced in situ nutrients, wastewater-treatment effluent nitrogen, and total suspended solids were significantly correlated to increased SAV abundance and diversity. Species composition and relative abundance also correlated with nutrient and water-quality conditions, indicating declining fitness of exotic species relative to native species during restoration. Our results suggest that environmental policies that reduce anthropogenic nutrient inputs do result in improved habitat quality, with increased diversity and native species abundances. The results also help elucidate why SAV cover has improved only in some areas of the Chesapeake Bay.

Influence of conditioning temperature on the performance, nutrient utilisation and digestive tract development of broilers fed on maize- and wheat-based diets.

PubMed

Abdollahi, M R; Ravindran, V; Wester, T J; Ravindran, G; Thomas, D V

2010-10-01

1. The influence of conditioning temperature on the performance, nutrient utilisation and digestive tract development of broilers fed on maize- and wheat-based diets was examined up to 21 d of age. The experimental design was a 2 × 3 factorial arrangement of treatments evaluating two grain types (maize and wheat) and three conditioning temperatures (60°C, 75°C and 90°C). Broiler starter diets, each based on one grain (maize or wheat), were formulated and pelleted at the three temperatures. 2. Increasing conditioning temperature decreased the body-weight gain and feed intake in wheat-based diets, but birds fed on maize-based diets conditioned at 60°C and 90°C had higher body-weight gain and feed intake than those fed on the diet conditioned at 75°C. Increasing conditioning temperature increased feed per body-weight gain in both grain-type diets but improved pellet durability index (PDI) only in wheat-based diets; PDI was unaffected in maize-based diets. 3. In wheat-based diets, increasing conditioning temperature decreased the ileal digestibility of nitrogen and starch. Ileal nitrogen digestibility of maize-based diets conditioned at 60°C and 90°C was higher than at 75°C. Starch digestibility was unaffected by conditioning temperature in maize-based diets. No effect of conditioning temperature was found for apparent metabolisable energy (AME). Increasing conditioning temperature decreased digestible protein and AME intakes in wheat-based diets but, in maize-based diets, birds fed on the diet conditioned at 75°C had lower digestible protein and AME intakes compared to those fed on diets conditioned at 60°C and 90°C. 4. Small intestine was longer in birds fed on diets conditioned at 75°C and 90°C compared with those fed on diets conditioned at 60°C. 5. Overall, the data suggest that while the effects of conditioning temperature on body-weight gain and feed intake of broilers to 21 d of age differed depending on the grain type, feed per body-weight gain

Cation Uptake and Allocation by Red Pine Seedlings under Cation-Nutrient Stress in a Column Growth Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Zhenqing; Balogh-Brunstad, Zsuzsanna; Grant, Michael R.

Background and Aims Plant nutrient uptake is affected by environmental stress, but how plants respond to cation-nutrient stress is poorly understood. We assessed the impact of varying degrees of cation-nutrient limitation on cation uptake in an experimental plant-mineral system. Methods Column experiments, with red pine (Pinus resinosa Ait.) seedlings growing in sand/mineral mixtures, were conducted for up to nine months under a range of Ca- and K-limited conditions. The Ca and K were supplied from both minerals and nutrient solutions with varying Ca and K concentrations. Results Cation nutrient stress had little impact on carbon allocation after nine months ofmore » plant growth and K was the limiting nutrient for biomass production. The Ca/Sr and K/Rb ratio results allowed independent estimation of dissolution incongruency and discrimination against Sr and Rb during cation uptake processes. The fraction of K in biomass from biotite increased with decreasing K supply from nutrient solutions. The mineral anorthite was consistently the major source of Ca, regardless of nutrient treatment. Conclusions Red pine seedlings exploited more mineral K in response to more severe K deficiency. This did not occur for Ca. Plant discrimination factors must be carefully considered to accurately identify nutrient sources using cation tracers.« less

Energy-neutral sustainable nutrient recovery incorporated with the wastewater purification process in an enlarged microbial nutrient recovery cell

NASA Astrophysics Data System (ADS)

Sun, Dongya; Gao, Yifan; Hou, Dianxun; Zuo, Kuichang; Chen, Xi; Liang, Peng; Zhang, Xiaoyuan; Ren, Zhiyong Jason; Huang, Xia

2018-04-01

Recovery of nutrient resources from the wastewater is now an inevitable strategy to maintain the supply of both nutrient and water for our huge population. While the intensive energy consumption in conventional nutrient recovery technologies still remained as the bottleneck towards the sustainable nutrient recycle. This study proposed an enlarged microbial nutrient recovery cell (EMNRC) which was powered by the energy contained in wastewater and achieved multi-cycle nutrient recovery incorporated with in situ wastewater treatment. With the optimal recovery solution of 3 g/L NaCl and the optimal volume ratio of wastewater to recovery solution of 10:1, >89% of phosphorus and >62% of ammonium nitrogen were recovered into struvite. An extremely low water input ratio of <1% was required to obtain the recovered fertilizer and the purified water. It was proved the EMNRC system was a promising technology which could utilize the chemical energy contained in wastewater itself and energy-neutrally recover nutrient during the continuous wastewater purification process.

Growing duckweed in swine wastewater for nutrient recovery and biomass production.

PubMed

Xu, Jiele; Shen, Genxiang

2011-01-01

Spirodela oligorrhiza, a promising duckweed identified in previous studies, was examined under different cropping conditions for nutrient recovery from swine wastewater and biomass production. To prevent algae bloom during the start-up of a duckweed system, inoculating 60% of the water surface with duckweed fronds was required. In the growing season, the duckweed system was capable of removing 83.7% and 89.4% of total nitrogen (TN) and total phosphorus (TP) respectively from 6% swine lagoon water in eight weeks at a harvest frequency of twice a week. The total biomass harvested was 5.30 times that of the starting amount. In winter, nutrients could still be substantially removed in spite of the limited duckweed growth, which was probably attributed to the improved protein accumulation of duckweed plants and the nutrient uptake by the attached biofilm (algae and bacteria) on duckweed and walls of the system. Copyright © 2010 Elsevier Ltd. All rights reserved.

Drug-nutrient interaction.

PubMed

Matsui, M S; Rozovski, S J

1982-01-01

The effect of certain drugs on nutrient metabolism is discussed. Antituberculotic drugs such as INH and cycloserine interfere with vitamin B6 metabolism and may produce a secondary niacin deficiency. Oral contraceptives interfere with the metabolism of folic acid and ascorbic acid, and in cases of deficient nutrition, they also seem to interfere with riboflavin. Anticonvulsants can act as folate antagonists and precipitate folic acid deficiency. Therefore, in some cases, supplementation with folate has been recommended simultaneously with anticonvulsant therapy. Cholestyramine therapy has been associated with malabsorption of vitamins; several reports suggest that cholestyramine affects absorption of the fat-soluble vitamins K and D and, in addition, may alter water-soluble vitamins, including folic acid. The study of the interaction of drugs and nutrients is an area that deserves a greater attention in the future, especially in groups where nutrient deficiencies may be prevalent.

Overview: Cross-habitat flux of nutrients and detritus

USGS Publications Warehouse

Vanni, M.J.; DeAngelis, D.L.; Schindler, D.E.; Huxel, G.R.; Polis, G.A.; Power, M.E.; Huxel, G.R.

2004-01-01

Ecologists have long known that all ecosystems receive considerable quantities of materials from outside their boundaries (e.g., Elton 1927), and quantifying the magnitude of such fluxes has long been a central tenet of ecosystem ecology (e.g., Odum 1971). Thus, one might think that the consequences of such fluxes for food webs would be well understood. However, food webs have traditionally been viewed as if they were isolated from surrounding habitats, a habit that has been particularly persistent in the modeling of food webs. When fluxes from the outside have been considered, they have largely been restricted to constant inputs directly affecting the base of the food web (e.g., solar energy or nutrients), and usually only such issues as their effects on equilibrium conditions have been considered (e.g., the well-known relationships between nutrient inputs and average densities of various food web members).

Environmental Nutrient Supply Directly Alters Plant Traits but Indirectly Determines Virus Growth Rate

PubMed Central

Lacroix, Christelle; Seabloom, Eric W.; Borer, Elizabeth T.

2017-01-01

Ecological stoichiometry and resource competition theory both predict that nutrient rates and ratios can alter infectious disease dynamics. Pathogens such as viruses hijack nutrient rich host metabolites to complete multiple steps of their epidemiological cycle. As the synthesis of these molecules requires nitrogen (N) and phosphorus (P), environmental supply rates, and ratios of N and P to hosts can directly limit disease dynamics. Environmental nutrient supplies also may alter virus epidemiology indirectly by changing host phenotype or the dynamics of coinfecting pathogens. We tested whether host nutrient supplies and coinfection control pathogen growth within hosts and transmission to new hosts, either directly or through modifications of plant tissue chemistry (i.e., content and stoichiometric ratios of nutrients), host phenotypic traits, or among-pathogen interactions. We examined two widespread plant viruses (BYDV-PAV and CYDV-RPV) in cultivated oats (Avena sativa) grown along a range of N and of P supply rates. N and P supply rates altered plant tissue chemistry and phenotypic traits; however, environmental nutrient supplies and plant tissue content and ratios of nutrients did not directly alter virus titer. Infection with CYDV-RPV altered plant traits and resulted in thicker plant leaves (i.e., higher leaf mass per area) and there was a positive correlation between CYDV-RPV titer and leaf mass per area. CYDV-RPV titer was reduced by the presence of a competitor, BYDV-PAV, and higher CYDV-RPV titer led to more severe chlorotic symptoms. In our experimental conditions, virus transmission was unaffected by nutrient supply rates, co-infection, plant stoichiometry, or plant traits, although nutrient supply rates have been shown to increase infection and coinfection rates. This work provides a robust test of the role of plant nutrient content and ratios in the dynamics of globally important pathogens and reveals a more complex relationship between within

Sources and cycling of major ions and nutrients in Devils Lake, North Dakota

USGS Publications Warehouse

Lent, R.M.

1994-01-01

Devils Lake is a saline lake in a large, closed drainage basin in northeastern North Dakota. Previous studies determined that major-ion and nutrient concentrations in Devils Lake are strongly affected by microbially mediated sulfate reduction and dissolution of sulfate and carbonate minerals in the bottom sediments. These studies documented substantial spatial variability in the magnitude of calculated benthic fluxes coincident with the horizontal salinity gradient in Devils Lake. The purpose of the present study is to evaluate seasonal variability in benthic-flux rates, and to understand the effect of these fluxes on the major-ion and nutrient chemistries in Devils Lake between May and October 1991. During the study period, the water column was well mixed, and specific conductance, pH, and temperature did not vary with depth. Dissolved oxygen was enriched near the lake surface due to photosynthesis. Major-ion concentrations and nutrient concentrations did not vary with depth. Because the water-quality data were obtained during open-water periods, the vertical profiles reflect well-mixed conditions. However, the first and last profiles for the study period did document near-bottom maxima of major cations. Secchi-disk depth varied from 0.82 meter on May 7,1991, to 2.13 meters on June 5, 1991. The mean Secchi-disk depth during the study period was 1.24 meters. Seasonal variations in Secchi-disk depths were attributed to variations in primary productivity and phytoplankton communities. Nutrient cycles in Devils Lake were evaluated using gross primary productivity rate data, sediment trap data, and major-ion and nutrient benthic-flux rate data. Gross primary productivity rate was smallest in May (0.076 gram of carbon per square meter per day) and largest in September (1.8 grams of carbon per square meter per day). Average gross primary productivity for the study period was 0.87 gram of carbon per square meter per day. Average gross primary productivity is consistent

Recent land cover history and nutrient retention in riparian wetlands

USGS Publications Warehouse

Hogan, D.M.; Walbridge, M.R.

2009-01-01

Wetland ecosystems are profoundly affected by altered nutrient and sediment loads received from anthropogenic activity in their surrounding watersheds. Our objective was to compare a gradient of agricultural and urban land cover history during the period from 1949 to 1997, with plant and soil nutrient concentrations in, and sediment deposition to, riparian wetlands in a rapidly urbanizing landscape. We observed that recent agricultural land cover was associated with increases in Nitrogen (N) and Phosphorus (P) concentrations in a native wetland plant species. Conversely, recent urban land cover appeared to alter receiving wetland environmental conditions by increasing the relative availability of P versus N, as reflected in an invasive, but not a native, plant species. In addition, increases in surface soil Fe content suggests recent inputs of terrestrial sediments associated specifically with increasing urban land cover. The observed correlation between urban land cover and riparian wetland plant tissue and surface soil nutrient concentrations and sediment deposition, suggest that urbanization specifically enhances the suitability of riparian wetland habitats for the invasive species Japanese stiltgrass [Microstegium vimenium (Trinius) A. Camus]. ?? 2009 Springer Science+Business Media, LLC.

Vertical patterns and controls of soil nutrients in alpine grassland: Implications for nutrient uptake.

PubMed

Tian, Liming; Zhao, Lin; Wu, Xiaodong; Fang, Hongbing; Zhao, Yonghua; Yue, Guangyang; Liu, Guimin; Chen, Hao

2017-12-31

Vertical patterns and determinants of soil nutrients are critical to understand nutrient cycling in high-altitude ecosystems; however, they remain poorly understood in the alpine grassland due to lack of systematic field observations. In this study, we examined vertical distributions of soil nutrients and their influencing factors within the upper 1m of soil, using data of 68 soil profiles surveyed in the alpine grassland of the eastern Qinghai-Tibet Plateau. Soil organic carbon (SOC) and total nitrogen (TN) stocks decreased with depth in both alpine meadow (AM) and alpine steppe (AS), but remain constant along the soil profile in alpine swamp meadow (ASM). Total phosphorus, Ca 2+ , and Mg 2+ stocks slightly increased with depth in ASM. K + stock decreased with depth, while Na + stock increased slightly with depth among different vegetation types; however, SO 4 2- and Cl - stocks remained relatively uniform throughout different depth intervals in the alpine grassland. Except for SOC and TN, soil nutrient stocks in the top 20cm soils were significantly lower in ASM compared to those in AM and AS. Correlation analyses showed that SOC and TN stocks in the alpine grassland positively correlated with vegetation coverage, soil moisture, clay content, and silt content, while they negatively related to sand content and soil pH. However, base cation stocks revealed contrary relationships with those environmental variables compared to SOC and TN stocks. These correlations varied between vegetation types. In addition, no significant relationship was detected between topographic factors and soil nutrients. Our findings suggest that plant cycling and soil moisture primarily control vertical distributions of soil nutrients (e.g. K) in the alpine grassland and highlight that vegetation types in high-altitude permafrost regions significantly affect soil nutrients. Copyright © 2017 Elsevier B.V. All rights reserved.

Recent insights into physiological responses to nutrients by the cylindrospermopsin producing cyanobacterium, Cylindrospermopsis raciborskii

NASA Astrophysics Data System (ADS)

Burford, Michele A.; Willis, Anusuya; Chuang, Ann; Man, Xiao; Orr, Phil

2017-11-01

The harmful cyanobacterium Cylindrospermopsis raciborskii is a widespread species increasingly being recorded in freshwater systems around the world. Studies have demonstrated some key attributes of this species which may explain its global dominance. It has a high level of flexibility with respect to light and nutrients, being capable of growth under low and variable light conditions. However, it is the strategy with respect to nutrient utilization that has received more attention. Unlike many bloom forming species, the dominance of this species is not simply linked to higher nutrient loads. In fact it appears that it is more competitive when phosphorus and nitrogen availability is low and/or variable. An important component of this flexibility appears to be the result of within-population strain variability in responses to nutrients, as well as key physiological adaptations. Strain variability also appears to have an effect on the population-level cell quota of toxins, specifically cylindrospermopsins (CYNs). Field studies in Australia showed that populations had the highest proportion of toxic strains when dissolved inorganic phosphorus was added, resulting in stoichiometrically balanced nitrogen and phosphorus within the cells. These strategies are part of an arsenal of responses to environmental conditions, making it a challenging species to manage. However, our ability to improve bloom prediction will rely on a more detailed understanding of the complex physiology and ecology of this species.

Assessing the impact of nutrient enrichment in estuaries: susceptibility to eutrophication.

PubMed

Painting, S J; Devlin, M J; Malcolm, S J; Parker, E R; Mills, D K; Mills, C; Tett, P; Wither, A; Burt, J; Jones, R; Winpenny, K

2007-01-01

The main aim of this study was to develop a generic tool for assessing risks and impacts of nutrient enrichment in estuaries. A simple model was developed to predict the magnitude of primary production by phytoplankton in different estuaries from nutrient input (total available nitrogen and/or phosphorus) and to determine likely trophic status. In the model, primary production is strongly influenced by water residence times and relative light regimes. The model indicates that estuaries with low and moderate light levels are the least likely to show a biological response to nutrient inputs. Estuaries with a good light regime are likely to be sensitive to nutrient enrichment, and to show similar responses, mediated only by site-specific geomorphological features. Nixon's scale was used to describe the relative trophic status of estuaries, and to set nutrient and chlorophyll thresholds for assessing trophic status. Estuaries identified as being eutrophic may not show any signs of eutrophication. Additional attributes need to be considered to assess negative impacts. Here, likely detriment to the oxygen regime was considered, but is most applicable to areas of restricted exchange. Factors which limit phytoplankton growth under high nutrient conditions (water residence times and/or light availability) may favour the growth of other primary producers, such as macrophytes, which may have a negative impact on other biological communities. The assessment tool was developed for estuaries in England and Wales, based on a simple 3-category typology determined by geomorphology and relative light levels. Nixon's scale needs to be validated for estuaries in England and Wales, once more data are available on light levels and primary production.

Tank cultivation of the red algae Palmaria mollis: Effects of nutrients on growth rate, biochemical quality, and epiphytic growth

NASA Astrophysics Data System (ADS)

Ben, D.; Langdon, C. J.

2016-02-01

Pacific dulse (Palmaria mollis) is a candidate for aquaculture production in Oregon due to its high protein content, fast growth rate, and ability to fare in cold water conditions. Current cultivation methods use the F/2 medium to supply nutrients to macroalgae cultures. The F/2 medium is a costly mixture of nitrate, phosphate, trace metals and vitamins. The F/2 medium has been the standard for microalgae cultivation, but research has lacked on the necessity of all or part of this mixture for macroalgae cultivation. This study is designed to contribute to the development of Pacific dulse cultivation by measuring how different fertilizer regimens affect the growth, biochemical composition, and quality of Palmaria mollis (C-3 variety) in hopes to reduce the production cost. I hypothesis that dulse will not require additional nutrients during summer cultivation, due to summer upwelling conditions. Experiments were conducted in a flow-through water system, controlling for flow rate, stocking density, and nutrient supplementation. To test this, two replicates of four nutrient regimes were organized: no supplemental nutrients, all nutrients (standard F/2 medium), nitrate/phosphate only, and nitrate/phosphate with trace metals. Each tank was monitored weekly for color quality, epiphytic growth, specific growth rate, production and a final biochemical analysis. This study has preliminarily concluded that supplemental nutrients have no significant effect on production or biochemical quality, but does have an effect quality of epiphytic growth.

Nutrient cycle benchmarks for earth system land model

NASA Astrophysics Data System (ADS)

Zhu, Q.; Riley, W. J.; Tang, J.; Zhao, L.

2017-12-01

Projecting future biosphere-climate feedbacks using Earth system models (ESMs) relies heavily on robust modeling of land surface carbon dynamics. More importantly, soil nutrient (particularly, nitrogen (N) and phosphorus (P)) dynamics strongly modulate carbon dynamics, such as plant sequestration of atmospheric CO2. Prevailing ESM land models all consider nitrogen as a potentially limiting nutrient, and several consider phosphorus. However, including nutrient cycle processes in ESM land models potentially introduces large uncertainties that could be identified and addressed by improved observational constraints. We describe the development of two nutrient cycle benchmarks for ESM land models: (1) nutrient partitioning between plants and soil microbes inferred from 15N and 33P tracers studies and (2) nutrient limitation effects on carbon cycle informed by long-term fertilization experiments. We used these benchmarks to evaluate critical hypotheses regarding nutrient cycling and their representation in ESMs. We found that a mechanistic representation of plant-microbe nutrient competition based on relevant functional traits best reproduced observed plant-microbe nutrient partitioning. We also found that for multiple-nutrient models (i.e., N and P), application of Liebig's law of the minimum is often inaccurate. Rather, the Multiple Nutrient Limitation (MNL) concept better reproduces observed carbon-nutrient interactions.

Distributions of Competing Container Mosquitoes Depend on Detritus Types, Nutrient Ratios, and Food Availability

PubMed Central

Murrell, Ebony G.; Damal, Kavitha; Lounibos, L. P.; Juliano, Steven A.

2012-01-01

Coexistence of competitors may result if resources are sufficiently abundant to render competition unimportant, or if species differ in resource requirements. Detritus type has been shown to affect interspecific competitive outcomes between Aedes albopictus (Skuse) and Aedes aegypti (L.) larvae under controlled conditions. We assessed the relationships among spatial distributions of detritus types, nutrients, and aquatic larvae of these species in nature. We collected mosquitoes, water, and detritus from artificial containers across 24 Florida cemeteries that varied in relative abundances of Ae. aegypti and Ae. albopictus.We measured nutrient content of fine particulate organic matter in water samples as total N, P, and C and ratios of these nutrients. We quantified food availability via a bioassay, raising individual Aedes larvae in the laboratory in standard volumes of field-collected, particulate-containing water from each cemetery. Quantities of detritus types collected in standard containers were significant predictors of nutrients and nutrient ratios. Nutrient abundances were significant predictors of relative abundance of Ae. aegypti, and of larval survival and development by both species in the bioassay. Survival and development of larvae reared in particulate-containing water from sites decreased with decreasing relative abundance of Ae. aegypti. These data suggest that N, P, and C availabilities are determined by detritus inputs to containers and that these nutrients in turn determine the feeding environment encountered by larvae, the intensity of interspecific competition among larvae, and subsequent relative abundances of species at sites. Detritus inputs, nutrients, and food availability thus seem to contribute to distributions of Ae. aegypti and Ae. albopictus in cemetery containers throughout Florida. PMID:22707761

Genetic and nutrient modulation of acetyl-CoA levels in Synechocystis for n-butanol production.

PubMed

Anfelt, Josefine; Kaczmarzyk, Danuta; Shabestary, Kiyan; Renberg, Björn; Rockberg, Johan; Nielsen, Jens; Uhlén, Mathias; Hudson, Elton P

2015-10-16

There is a strong interest in using photosynthetic cyanobacteria as production hosts for biofuels and chemicals. Recent work has shown the benefit of pathway engineering, enzyme tolerance, and co-factor usage for improving yields of fermentation products. An n-butanol pathway was inserted into a Synechocystis mutant deficient in polyhydroxybutyrate synthesis. We found that nitrogen starvation increased specific butanol productivity up to threefold, but cessation of cell growth limited total n-butanol titers. Metabolite profiling showed that acetyl-CoA increased twofold during nitrogen starvation. Introduction of a phosphoketolase increased acetyl-CoA levels sixfold at nitrogen replete conditions and increased butanol titers from 22 to 37 mg/L at day 8. Flux balance analysis of photoautotrophic metabolism showed that a Calvin-Benson-Bassham-Phosphoketolase pathway had higher theoretical butanol productivity than CBB-Embden-Meyerhof-Parnas and a reduced butanol ATP demand. These results demonstrate that phosphoketolase overexpression and modulation of nitrogen levels are two attractive routes toward increased production of acetyl-CoA derived products in cyanobacteria and could be implemented with complementary metabolic engineering strategies.

A case study of precision farming for nutrient management of corn

NASA Astrophysics Data System (ADS)

Blanco, Alfonso; Hunt, Ray; Gomez, Richard B.; Roper, William E.

2003-08-01

Precision farming relies on the cost effectiveness of collecting and interpreting data, which describes the variations of agricultural conditions such as crop stresses, nutrient deficiencies, water stresses, or pest infestation. Hyperspectral remote sensing from satellites and airborne sensors can be a way to obtain data needed to develop site-specific farming management strategies. The primary objective of the hyperspectral applications in precision farming is to provide farmers with a technology, which can detect specific crop conditions that can be used to program variable-rate applications. Applications of water, pesticides, and fertilizer can be tailored to the needs of the agricultural crops, based on the conditions reflected on the imagery. This paper presents an experimental study performed in Beltsville, Maryland for assessing the plant density and nutrient uptake of corn using a simple photographic method from a model airplane versus obtaining hyperspectral imagery from an airborne sensor. The hyperspectral sensor utilized in this study was the AISA sensor. These remote sensors can measure the temperature of plants; or to be more specific, they can measure how much energy plants emit at the visible and near-infrared wavelengths of the spectrum, such as water and vegetation.

Proximate and ultimate controls on carbon and nutrient dynamics of small agricultural catchments

NASA Astrophysics Data System (ADS)

Thomas, Zahra; Abbott, Benjamin W.; Troccaz, Olivier; Baudry, Jacques; Pinay, Gilles

2016-03-01

Direct and indirect effects from human activity have dramatically increased nutrient loading to aquatic inland and estuarine ecosystems. Despite an abundance of studies investigating the impact of agricultural activity on water quality, our understanding of what determines the capacity of a watershed to remove or retain nutrients remains limited. The goal of this study was to identify proximate and ultimate controls on dissolved organic carbon and nutrient dynamics in small agricultural catchments by investigating the relationship between catchment characteristics, stream discharge, and water chemistry. We analyzed a 5-year, high-frequency water chemistry data set from three catchments in western France ranging from 2.3 to 10.8 km2. The relationship between hydrology and solute concentrations differed between the three catchments and was associated with hedgerow density, agricultural activity, and geology. The catchment with thicker soil and higher surface roughness had relatively invariant carbon and nutrient chemistry across hydrologic conditions, indicating high resilience to human disturbance. Conversely, the catchments with smoother, thinner soils responded to both intra- and interannual hydrologic variation with high concentrations of phosphate (PO43-) and ammonium (NH4+) in streams during low flow conditions and strong increases in dissolved organic carbon (DOC), sediment, and particulate organic matter during high flows. Despite contrasting agricultural activity between catchments, the physical context (geology, topography, and land-use configuration) appeared to be the most important determinant of catchment solute dynamics based on principle components analysis. The influence of geology and accompanying topographic and geomorphological factors on water quality was both direct and indirect because the distribution of agricultural activity in these catchments is largely a consequence of the geologic and topographic context. This link between inherent

Quantifying the Urban and Rural Nutrient Fluxes to Lake Erie Using a Paired Watershed Approach

NASA Astrophysics Data System (ADS)

Hopkins, M.; Beck, M.; Rossi, E.; Luh, N.; Allen-King, R. M.; Lowry, C.

2016-12-01

Excess nutrients have a detrimental impact on the water quality of Lake Erie, specifically nitrate and phosphate, which can lead to toxic algae blooms. Algae blooms have negatively impacted Lake Erie, which is the main source of drinking water for many coastal Great Lake communities. In 2014 the city of Toledo, Ohio was forced to shut down its water treatment plant due to these toxic algae blooms. The objective of this research is to quantify surface water nutrient fluxes to the eastern basin of Lake Erie using a paired watershed approach. Three different western New York watersheds that feed Lake Erie were chosen based on land use and areal extent: one small urban, one small rural, and one large rural. These paired watersheds were chosen to represent a range of sources of potential nutrient loading to the lake. Biweekly water samples were taken from the streams during the 2015-2016 winter to summer seasonal transition to quantify springtime snow melt effects on nutrient fluxes. These results were compared to the previous year samples, collected over the summer of 2015, which represented wetter conditions. Phosphorous levels were assessed using the ascorbic acid colorimetric assay, while nitrate was analyzed by anion-exchange chromatography. Stream gaging was used to obtain flow measurements and establish a rating curve, which was incorporated to quantify seasonal nutrient fluxes entering the lake. Patterns in the nutrient levels show higher level of nutrients in the rural watersheds with a decrease in concentration over the winter to spring transition. However, nutrient patterns in the urban stream show relatively constant patters of nutrient flux, which is independent of seasonal transition or stream discharge. A comparison of wet and dry seasons shows higher nutrient concentrations during summers with greater rainfall. By identifying the largest contributors of each nutrient, we can better allocate limited attenuation resources.

Haemophilus Responses to Nutritional Immunity: Epigenetic and Morphological Contribution to Biofilm Architecture, Invasion, Persistence and Disease Severity

PubMed Central

Szelestey, Blake R.; Heimlich, Derek R.; Raffel, Forrest K.; Justice, Sheryl S.; Mason, Kevin M.

2013-01-01

In an effort to suppress microbial outgrowth, the host sequesters essential nutrients in a process termed nutritional immunity. However, inflammatory responses to bacterial insult can restore nutritional resources. Given that nutrient availability modulates virulence factor production and biofilm formation by other bacterial species, we hypothesized that fluctuations in heme-iron availability, particularly at privileged sites, would similarly influence Haemophilus biofilm formation and pathogenesis. Thus, we cultured Haemophilus through sequential heme-iron deplete and heme-iron replete media to determine the effect of transient depletion of internal stores of heme-iron on multiple pathogenic phenotypes. We observed that prior heme-iron restriction potentiates biofilm changes for at least 72 hours that include increased peak height and architectural complexity as compared to biofilms initiated from heme-iron replete bacteria, suggesting a mechanism for epigenetic responses that participate in the changes observed. Additionally, in a co-infection model for human otitis media, heme-iron restricted Haemophilus, although accounting for only 10% of the inoculum (90% heme-iron replete), represented up to 99% of the organisms recovered at 4 days. These data indicate that fluctuations in heme-iron availability promote a survival advantage during disease. Filamentation mediated by a SulA-related ortholog was required for optimal biofilm peak height and persistence during experimental otitis media. Moreover, severity of disease in response to heme-iron restricted Haemophilus was reduced as evidenced by lack of mucosal destruction, decreased erythema, hemorrhagic foci and vasodilatation. Transient restriction of heme-iron also promoted productive invasion events leading to the development of intracellular bacterial communities. Taken together, these data suggest that nutritional immunity, may, in fact, foster long-term phenotypic changes that better equip bacteria for

Nutrients in Streams and Rivers Across the Nation -- 1992-2001

USGS Publications Warehouse

Mueller, David K.; Spahr, Norman E.

2006-01-01

cropland to streams (Midwest, Northern Plains, and western areas of the United States). Concentrations were lower in the Southeast, where more denitrification occurs during transport of nitrogen compounds in shallow ground water. At urban sites, high concentrations of ammonia and orthophosphate were more prevalent downstream from wastewater-treatment plants. At sites with large watersheds and high mean-annual streamflow ('large-watershed' sites), concentrations of most nutrients were significantly less than at sites downstream from agricultural or urban areas. Total nitrogen concentrations at large-watershed sites were higher in Midwest agricultural areas and lower in the Western United States, where agricultural and urban development is less extensive. Total phosphorus concentrations at large-watershed sites were higher in areas of greater potential erosion and low overall runoff such as the arid areas in the West. Although not as distinct as seasonal patterns of streamflow, geographic patterns of seasonally high and low concentrations of total nitrogen and total phosphorus were identified in the data. Seasonal patterns in concentrations of total nitrogen generally mirror seasonal patterns in streamflow in the humid Eastern United States but are inverse to seasonal patterns in streamflow in the semiarid interior West. Total phosphorus concentrations typically have the opposite regional relation with streamflow; high concentrations coincide with high streamflows in the interior West. In the NAWQA Program, sites downstream from relatively undeveloped areas were selected to provide a baseline for comparison to sites with potential effects of urban development and agriculture. Concentrations of nitrate, total nitrogen, and total phosphorus at NAWQA undeveloped sites were found to be greater than values reported by other studies for conditions of essentially no development (background conditions). Concentrations at NAWQA undeveloped sites represent conditions

Are nutrient databases and nutrient analysis systems ready for the International implications of nutrigenomics?

USDA-ARS?s Scientific Manuscript database

Our objective is to discuss the implications internationally of the increased focus on nutrigenomics as the underlying basis for individualized health promotion and chronic disease prevention and the challenges presented to existing nutrient database and nutrient analysis systems by these trends. De...

A Nutrient-Tunable Bistable Switch Controls Motility in Salmonella enterica Serovar Typhimurium

PubMed Central

Koirala, Santosh; Mears, Patrick; Sim, Martin; Golding, Ido; Chemla, Yann R.; Aldridge, Phillip D.

2014-01-01

ABSTRACT Many bacteria are motile only when nutrients are scarce. In contrast, Salmonella enterica serovar Typhimurium is motile only when nutrients are plentiful, suggesting that this bacterium uses motility for purposes other than foraging, most likely for host colonization. In this study, we investigated how nutrients affect motility in S. enterica and found that they tune the fraction of motile cells. In particular, we observed coexisting populations of motile and nonmotile cells, with the distribution being determined by the concentration of nutrients in the growth medium. Interestingly, S. enterica responds not to a single nutrient but apparently to a complex mixture of them. Using a combination of experimentation and mathematical modeling, we investigated the mechanism governing this behavior and found that it results from two antagonizing regulatory proteins, FliZ and YdiV. We also found that a positive feedback loop involving the alternate sigma factor FliA is required, although its role appears solely to amplify FliZ expression. We further demonstrate that the response is bistable: that is, genetically identical cells can exhibit different phenotypes under identical growth conditions. Together, these results uncover a new facet of the regulation of the flagellar genes in S. enterica and further demonstrate how bacteria employ phenotypic diversity as a general mechanism for adapting to change in their environment. PMID:25161191

Cell survival under nutrient stress is dependent on metabolic conditions regulated by Akt and not by autophagic vacuoles.

PubMed

Bruno, P; Calastretti, A; Priulla, M; Asnaghi, L; Scarlatti, F; Nicolin, A; Canti, G

2007-10-01

Akt activation assists tumor cell survival and promotes resistance to chemotherapy. Here we show that constitutively active Akt (CA-Akt) cells are highly sensitized to cell death induced by nutrient and growth factor deprivation, whereas dominant-negative Akt (DN-Akt) cells have a high rate of survival. The content of autophagosomes in starved CA-Akt cells was high, while DN-Akt cells expressed autophagic vacuoles constitutively, independently of nutrition conditions. Thus Akt down-regulation and downstream events can induce autophagosomes which were not directly determinants of cell death. Biochemical analysis in Akt-mutated cells show that (i) Akt and mTOR proteins were degraded more rapidly than the housekeeping proteins, (ii) mTOR phosphorylation at position Thr(2446) was relatively high in DN-Akt and low in CA-Akt cells, induced by starvation in mock cells only, which suggests reduced autoregulation of these pathways in Akt-mutated cells, (iii) both protein synthesis and protein degradation were significantly higher in starved CA-Akt cells than in starved DN-Akt cells or mock cells. In conclusion, constitutively active Akt, unable to control synthesis and wasting of proteins, accelerates the death of starved cells.

Effect of Fenton pre-oxidation on mobilization of nutrients and efficient subsequent bioremediation of crude oil-contaminated soil.

PubMed

Xu, Jinlan; Kong, Fanxing; Song, Shaohua; Cao, Qianqian; Huang, Tinglin; Cui, Yiwei

2017-08-01

Fenton pre-oxidation and a subsequent bioremediation phase of 80 days were used to investigate the importance of matching concentration of residual indigenous bacteria and nutrient levels on subsequent bioremediation of crude oil. Experiments were performed using either high (>10 7.7 ± 0.2  CFU/g soil) or low (<10 5.9 ± 0.1  CFU/g soil) concentrations of bacteria and three different nutrient levels: enough (C/N > 9.8), moderate (C/N:5-9.8), and lacking nutrient level (C/N < 5) conditions. Weak Fenton pre-oxidation (225 mM H 2 O 2 and 2.9 mM Fe 2+ ) resulted in highly matching between nutrient level and the population of residual indigenous bacteria. Up to 53% of total petroleum hydrocarbon (TPH) and 58% of main hydrocarbon (C 15 C 25 , during the first 10 days) were removed from the soil. Under matching conditions, the activity of indigenous bacteria and nutrient mobilization were enhanced, promoting the bioremediation of crude oil. In addition, the biodegradation of long chain molecules (C 26 C 30 ) required a high level of NH 4 + -N. Copyright © 2017 Elsevier Ltd. All rights reserved.

Relationship between soil nutrients and mycorrhizal associations of two Bipinnula species (Orchidaceae) from central Chile.

PubMed

Mujica, María Isabel; Saez, Nicolás; Cisternas, Mauricio; Manzano, Marlene; Armesto, Juan J; Pérez, Fernanda

2016-07-01

Mycorrhizal associations are influenced by abiotic and biotic factors, including climate, soil conditions and the identity of host plants. However, the effect of environmental conditions on orchid mycorrhizal associations remains poorly understood. The present study examined how differences in soil nutrient availability are related to the diversity and composition of mycorrhizal fungi associated with two terrestrial orchid species from central Chile. For 12 populations of Bipinnula fimbriata and B. plumosa, OTU (operational taxonomic unit) richness, phylogenetic diversity and community composition of mycorrhizal fungi in root samples were estimated using internal transcribed spacer (ITS) sequences. Then, these mycorrhizal diversity variables were related to soil nutrients and host species using generalized linear models and non-metric multidimensional scaling. Variation in OTU composition of mycorrhizal fungi among sites was explained mainly by orchid host species. Fungi in Tulasnellaceae and Ceratobasidiaceae were isolated from both orchid species, but the former were more frequent in B. fimbriata and the latter in B. plumosa. Soil nutrients and orchid host species had significant effects on OTU richness and phylogenetic diversity. Mycorrhizal diversity decreased in habitats with higher N in both species and increased with P availability only in B. fimbriata The results suggest that soil nutrient availability modulates orchid mycorrhizal associations and provide support for the hypothesis that specialization is favoured by higher soil nutrient availability. Inter-specific differences in mycorrhizal composition can arise due to a geographical pattern of distribution of orchid mycorrhizal fungi, host preferences for fungal partners or differential performance of mycorrhizal fungi under different nutrient availabilities. Further experiments are needed to evaluate these hypotheses. © The Author 2016. Published by Oxford University Press on behalf of the Annals of

Adsorption of mixtures of nutrients and heavy metals in simulated urban stormwater by different filter materials.

PubMed

Reddy, Krishna R; Xie, Tao; Dastgheibi, Sara

2014-01-01

In recent years, several best management practices have been developed for the removal of different types of pollutants from stormwater runoff that lead to effective stormwater management. Filter materials that remove a wide range of contaminants have great potential for extensive use in filtration systems. In this study, four filter materials (calcite, zeolite, sand, and iron filings) were investigated for their adsorption and efficiency in the removal of nutrients and heavy metals when they exist individually versus when they co-exist. Laboratory batch experiments were conducted separately under individual and mixed contaminants conditions at different initial concentrations. Adsorption capacities varied under the individual and mixed contaminant conditions due to different removal mechanisms. Most filter materials showed lower removal efficiency under mixed contaminant conditions. In general, iron filings were found effective in the removal of nutrients and heavy metals simultaneously to the maximum levels. Freundlich and Langmuir isotherms were used to model the batch adsorption results and the former better fitted the experimental results. Overall, the results indicate that the filter materials used in this study have the potential to be effective media for the treatment of nutrients and heavy metals commonly found in urban stormwater runoff.

Soil moisture and texture primarily control the soil nutrient stoichiometry across the Tibetan grassland.

PubMed

Tian, Liming; Zhao, Lin; Wu, Xiaodong; Fang, Hongbing; Zhao, Yonghua; Hu, Guojie; Yue, Guangyang; Sheng, Yu; Wu, Jichun; Chen, Ji; Wang, Zhiwei; Li, Wangping; Zou, Defu; Ping, Chien-Lu; Shang, Wen; Zhao, Yuguo; Zhang, Ganlin

2018-05-01

Soil nutrient stoichiometry and its environmental controllers play vital roles in understanding soil-plant interaction and nutrient cycling under a changing environment, while they remain poorly understood in alpine grassland due to lack of systematic field investigations. We examined the patterns and controls of soil nutrients stoichiometry for the top 10cm soils across the Tibetan ecosystems. Soil nutrient stoichiometry varied substantially among vegetation types. Alpine swamp meadow had larger topsoil C:N, C:P, N:P, and C:K ratios compared to the alpine meadow, alpine steppe, and alpine desert. In addition, the presence or absence of permafrost did not significantly impact soil nutrient stoichiometry in Tibetan grassland. Moreover, clay and silt contents explained approximately 32.5% of the total variation in soil C:N ratio. Climate, topography, soil properties, and vegetation combined to explain 10.3-13.2% for the stoichiometry of soil C:P, N:P, and C:K. Furthermore, soil C and N were weakly related to P and K in alpine grassland. These results indicated that the nutrient limitation in alpine ecosystem might shifts from N-limited to P-limited or K-limited due to the increase of N deposition and decrease of soil P and K contents under the changing climate conditions and weathering stages. Finally, we suggested that soil moisture and mud content could be good predictors of topsoil nutrient stoichiometry in Tibetan grassland. Copyright © 2017 Elsevier B.V. All rights reserved.