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C/N Ratio (c + ratio)
Kinds of C/N Ratio Selected AbstractsDevelopment of a Novel Oxidative Hair Color Based on a System with an Optimized Ratio of Higher Alcohol to Cationic SurfactantINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2006T. Yamashita Oxidative hair color, the most commonly used for coloring hair, is characterized by its bleaching effect. This effect enables dark hair to be dyed in various bright colors. In order to enhance this bleaching effect, the concentration of either the alkalizing or oxidizing agent in the hair color base is generally increased. However, this method causes chemical damage to the hair. With the aim of finding methods to obtain an improved bleaching effect without increasing the amount of bleaching ingredients, the authors investigated the permeation mechanism. Cationic bases showed the highest bleaching effect and allowed greater penetration, permitting bleaching ingredients to enter the cortex of the hair more easily and diffuse more quickly. In addition, the molar ratios of higher alcohol (A) to cationic surfactant (C) as a function of the bleaching effect were also evaluated. The results showed an optimum range for this A/C ratio. The smoothness of the hair was also evaluated, revealing an optimum range for the A/C ratio. Based on these findings, a product with an A/C ratio that maximizes the bleaching effect and the smoothness of the hair was successfully developed. Comparison of this newly developed product with a conventional product verified that the new product has a greater bleaching effect and gives a beautiful depth of color while maintaining the silky smoothness of the texture of the hair. Part of this study was presented at the 23rd IFSCC Congress 2004, Orlando, Florida USA. [source] Trophic mass balanced models and dynamic simulations of benthic communities from La Rinconada Marine Reserve off northern Chile: network properties and multispecies harvest scenario assessmentsAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 1 2010Marco Ortiz Abstract 1.Mass balanced trophic models and dynamic simulations of two benthic ecological systems from La Rinconada Marine Reserve (Antofagasta Bay, SE Pacific) were constructed. 2.The scallop Argopecten purpuratus is the most important benthic resource in La Rinconada Marine Reserve, followed by the carnivorous snail Thais chocolata, and the filter-feeder bivalves Tagelus dombeii and Transennella pannosa. 3.Information on biomass, P/B ratios, catches, food spectrum, consumption, and dynamics of commercial and non-commercial species was obtained and examined using Ecopath with an Ecosim software package. 4.The bivalves A. purpuratus and T. dombeii represented the most abundant compartments in the studied subsystems. Of the carnivores, the snail T. chocolata was dominant, followed by the crabs Cancer spp. and the functional group of large epifauna. 5.The two subsystems presented similar values of system throughput. The mean trophic level of their fisheries also reached similar magnitudes (2.0), showing that the harvests in each system concentrated on secondary producers. Likewise, both subsystems presented similar A/C ratios (29.9 and 30.3), suggesting that they were immature. 6.The results obtained using mixed trophic impact (MTI) and Ecosim (increasing the fishing mortality Fi by four times) showed that only four species propagated the highest direct and indirect effects. Coincidentally, these species are the most economically important and the changes produced by the scallop A. purpuratus are noteworthy. 7.With regard to the system recovery time (SRT) estimates, only three species or functional groups presented the highest magnitudes, from highest to lowest: the sea star Luidia magallanica, the scallop A. purpuratus, and the crabs Cancer spp. 8.The topological keystone indexes of Jordán and Libralato had divergent results. According to Jordán's index, the keystone species were L. magallanica, Cancer spp., and detritus; whereas Libralato's index showed phytoplankton to be the keystone species. 9.Based on the results obtained, it is concluded that trophic mass balanced models and simulated management scenarios have considerable value for planning interventions and manipulations or for planning more sustainable management strategies in La Rinconada Marine Reserve. Copyright © 2009 John Wiley & Sons, Ltd. [source] Uterine adenosarcoma detected by Papanicolaou smear: A Case report,DIAGNOSTIC CYTOPATHOLOGY, Issue 7 2006F.R.C.P.C., Sylvia Pasternak M.D. Abstract Adenosarcoma is a rare uterine biphasic tumor composed of benign epithelial elements and a sarcomatous stroma. Although it is well described histologically, its cytological features are rarely mentioned in the literature. We describe a case of uterine adenosarcoma that was first detected by Papanicolau (Pap) smear. Numerous crowded clusters of spindle cells were present within a bloody background, as well as a few smaller, dyscohesive groups with cells showing high N:C ratio and oval to round nuclei with coarse chromatin and small nucleoli. A few nuclear grooves were identified. Adenosarcomas are rare lesions but should be considered in the differential diagnosis when spindled cells are noted in a pap smear. Diagn. Cytopathol. 2006;34:495,498. © 2006 Wiley-Liss, Inc. [source] Stoichiometric impacts of increased carbon dioxide on a planktonic herbivoreGLOBAL CHANGE BIOLOGY, Issue 6 2003JOTARO URABE Abstract The partial pressure of carbon dioxide (pCO2) in lake ecosystems varies over four orders of magnitude and is affected by local and global environmental perturbations associated with both natural and anthropogenic processes. Little is known, however, about how changes in pCO2 extend into the function and structure of food webs in freshwater ecosystems. To fill this gap, we performed laboratory experiments using the ecologically important planktonic herbivore Daphnia and its algal prey under a natural range of pCO2 with low light and phosphorus supplies. The experiment showed that increased pCO2 stimulated algal growth but reduced algal P : C ratio. When feeding on algae grown under high pCO2, herbivore growth decreased regardless of algal abundance. Thus, high CO2 -raised algae were poor food for Daphnia. Short-term experimental supplementation of PO4 raised the P content of the high CO2 -raised algae and improved Daphnia growth, indicating that low Daphnia growth rates under high pCO2 conditions were due to lowered P content in the algal food. These results suggest that, in freshwater ecosystems with low nutrient supplies, natural processes as well as anthropogenic perturbations resulting in increased pCO2 enhance algal production but reduce energy and mass transfer efficiency to herbivores by decreasing algal nutritional quality. [source] Constraints on the glacial operation of the atlantic ocean's conveyor circulationISRAEL JOURNAL OF CHEMISTRY, Issue 1 2002Wallace S. BroeckerArticle first published online: 8 MAR 2010 Circulation in the Atlantic Ocean is currently dominated by a northward flow of upper waters balanced by a return flow of deep water (i.e., the conveyor). Paleoproxies tell us that, unlike today, during the glacial age the deep Atlantic was stratified. Rather than being flooded with one nearly homogeneous water mass, there were two distinctly different ones. In this paper, the paleoproxy results are analyzed in an attempt to constrain the sources and ventilation rate of the deeper of these two glacial Atlantic water masses. Taken together, the cadmium and carbon isotope measurements on benthic foraminifera and the radiocarbon measurements on coexisting benthic and planktonic foraminifera appear to require a conveyor-like circulation no weaker than half of today's. This conclusion is at odds with geostrophic reconstructions. This seeming disagreement could be eliminated if, as suggested by Keigwin and Schlegel, the radiocarbon measurements by Broecker et al. significantly underestimate the difference between the 14C to C ratio for glacialage surface water and deep water in the equatorial Atlantic. [source] Use of mid-infrared spectroscopy in the diffuse-reflectance mode for the prediction of the composition of organic matter in soil and litterJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2008Bernard Ludwig Abstract Mid-infrared spectroscopy (MIRS) is assumed to be superior to near-infrared spectroscopy (NIRS) for the prediction of soil constituents, but its usefulness is still not sufficiently explored. The objective of this study was to evaluate the ability of MIRS to predict the chemical and biological properties of organic matter in soils and litter. Reflectance spectra of the mid-infrared region including part of the near-infrared region (7000,400,cm,1) were recorded for 56 soil and litter samples from agricultural and forest sites. Spectra were used to predict general and biological characteristics of the samples as well as the C composition which was measured by 13C CPMAS-NMR spectroscopy. A partial least-square method and cross-validation were used to develop equations for the different constituents over selected spectra ranges after several mathematical treatments of the spectra. Mid-infrared spectroscopy predicted well the C : N ratio: the modeling efficiency EF was 0.95, the regression coefficient (a) of a linear regression (measured against predicted values) was 1.0, and the correlation coefficient (r) was 0.98. Satisfactorily (EF , 0.70, 0.8 , a , 1.2, r , 0.80) assessed were the contents of C, N, and lignin, the production of dissolved organic carbon, and the contents of carbonyl C, aromatic C, O-alkyl C, and alkyl C. However, the N mineralization rate, the microbial biomass and the alkyl,to,aromatic C ratio were predicted less satisfactorily (EF < 0.70). Limiting the sample set to mineral soils did generally not result in improved predictions. The good and satisfactory predictions reported above indicate a marked usefulness of MIRS in the assessment of chemical characteristics of soils and litter, but the accuracies of the MIRS predictions in the diffuse-reflectance mode were generally not superior to those of NIRS. [source] Influence of growth stage and postharvest storage on ascorbic acid and carotenoid content and visual quality of baby spinach (Spinacia oleracea L.)JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 3 2006Sara ĹM Bergquist Abstract To investigate the variations in quality with growth stage and postharvest storage, spinach was sown on three occasions. For each occasion, the spinach was harvested at three growth stages at 6-day intervals. The second stage corresponded to a growth period used for baby spinach by commercial growers. After harvest, the leaves were stored in polypropylene bags at 2 °C or 10 °C. The highest ascorbic acid content in fresh material was found at stage I. During storage, the ascorbic acid content decreased considerably and the dehydroascorbic acid/vitamin C ratio increased. Storage at 2 °C gave a smaller reduction in ascorbic acid content than storage at 10 °C. Total carotenoid content increased or remained stable during storage. Lutein was the major carotenoid, making up about 39% of the total carotenoid content, followed by violaxanthin, ,-carotene and neoxanthin. Visual quality decreased during storage in most cases, and was correlated to initial ascorbic acid and dry matter contents. The initial AA content might therefore be used as a parameter for predicting the shelf-life of baby spinach. The results also indicate that by harvesting baby spinach a few days earlier than the current commercial stage of harvest the postharvest visual quality and nutritional quality may be improved. Copyright © 2005 Society of Chemical Industry [source] Quantification of prostate MRSI data by model-based time domain fitting and frequency domain analysisNMR IN BIOMEDICINE, Issue 2 2006Pieter Pels Abstract This paper compares two spectral processing methods for obtaining quantitative measures from in vivo prostate spectra, evaluates their effectiveness, and discusses the necessary modifications for accurate results. A frequency domain analysis (FDA) method based on peak integration was compared with a time domain fitting (TDF) method, a model-based nonlinear least squares fitting algorithm. The accuracy of both methods at estimating the choline,+,creatine,+,polyamines to citrate ratio (CCP:C) was tested using Monte Carlo simulations, empirical phantom MRSI data and in vivo MRSI data. The paper discusses the different approaches employed to achieve the quantification of the overlapping choline, creatine and polyamine resonances. Monte Carlo simulations showed induced biases on the estimated CCP:C ratios. Both methods were successful in identifying tumor tissue, provided that the CCP:C ratio was greater than a given (normal) threshold. Both methods predicted the same voxel condition in 94% of the in vivo voxels (68 out of 72). Both TDF and FDA methods had the ability to identify malignant voxels in an artifact-free case study using the estimated CCP:C ratio. Comparing the ratios estimated by the TDF and the FDA, the methods predicted the same spectrum type in 17 out of 18 voxels of the in vivo case study (94.4%). Copyright © 2006 John Wiley & Sons, Ltd. [source] The effects of nutritional imbalance on compensatory feeding for cellulose-mediated dietary dilution in a generalist caterpillarPHYSIOLOGICAL ENTOMOLOGY, Issue 2 2004Kwang Pum Lee Abstract. The interactive effects of macronutrient balance [protein (P) : carbohydrate (C) ratio] and dietary dilution by cellulose on nutritional regulation and performance were investigated in the generalist caterpillar Spodoptera littoralis (Boisduval). Caterpillars were reared through the final stadium on one of 20 foods varying factorially in macronutrient content (P + C%: 42, 33.6. 25.2 or 16.8%) and P : C ratio (5 : 1, 2 : 1, 1 : 1, 1 : 2 or 1 : 5). The animals compensate by eating more of diluted foods, but suffer reduced nutrient intake in proportion to the degree of dilution. Increase in food intake with dilution is greater on balanced than imbalanced foods and this is reflected in greater reduction of dry pupal mass with dilution in the latter. Whereas dilution results in a reduction in the amount of whichever macronutrient is in excess in the food, by contrast, the ability to compensate for the deficient macronutrient in the food is unaffected by nutrient imbalance. Excess protein intake due to nutritional imbalance (diets with high P : C ratios) results in a regulatory decrease in the efficiency of retention of ingested nitrogen relative to restricted protein intake on oppositely imbalanced foods (low P : C ratios). By contrast, decreased protein intake due to dietary dilution is associated with a non-regulatory reduction in the efficiency of retention, irrespective of P : C ratio. Dilution is similarly associated with reduced utilization efficiency of ingested carbohydrate. The ecological implications of these results are discussed. [source] Impact of nitrate supply in C and N assimilation in the parasitic plant Striga hermonthica (Del.) Benth (Scrophulariaceae) and its host Sorghum bicolor L.PLANT CELL & ENVIRONMENT, Issue 4 2006P. SIMIER ABSTRACT The threshold of tolerance for nitrate of the parasitic weed Striga hermonthica (Del.) Benth and the host plant Sorghum bicolor L. was determined by estimating the impact of increasing nitrate loads on plant growth and various parameters of C and N assimilation. Nitrate supply improved chlorophyll (Chl) content and photosystem II (PSII) photochemistry of infected S. bicolor that, in comparison to S. hermonthica, displayed a low imbalance between C and N assimilation when nitrate was supplied up to 1500 mg N per plant. Indeed, nitrate supplies increased strongly the leaf N:C ratio of the parasite. The higher nitrate load induced strong accumulation of nitrate, nitrite and ammonium, and consequently the death of S. hermonthica. Nevertheless, lower nitrate loads (up to 500 mg N per S. bicolor in this study) promoted leaf expansion, PSII photochemistry and N metabolism of S. hermonthica mature (M) plants, as attested by the significant rise in soluble protein and free amino-acid contents. Following these N supplies, the nitrate tolerance of S. hermonthica was correlated with an increase in PSII activity and a high incorporation of N excess into asparagine. This confirmed the central role of asparagine in the N metabolism of S. hermonthica, although this detoxification pathway was insufficient to limit ammonium accumulation under higher nitrate loads. [source] Quantification of prostate MRSI data by model-based time domain fitting and frequency domain analysisNMR IN BIOMEDICINE, Issue 2 2006Pieter Pels Abstract This paper compares two spectral processing methods for obtaining quantitative measures from in vivo prostate spectra, evaluates their effectiveness, and discusses the necessary modifications for accurate results. A frequency domain analysis (FDA) method based on peak integration was compared with a time domain fitting (TDF) method, a model-based nonlinear least squares fitting algorithm. The accuracy of both methods at estimating the choline,+,creatine,+,polyamines to citrate ratio (CCP:C) was tested using Monte Carlo simulations, empirical phantom MRSI data and in vivo MRSI data. The paper discusses the different approaches employed to achieve the quantification of the overlapping choline, creatine and polyamine resonances. Monte Carlo simulations showed induced biases on the estimated CCP:C ratios. Both methods were successful in identifying tumor tissue, provided that the CCP:C ratio was greater than a given (normal) threshold. Both methods predicted the same voxel condition in 94% of the in vivo voxels (68 out of 72). Both TDF and FDA methods had the ability to identify malignant voxels in an artifact-free case study using the estimated CCP:C ratio. Comparing the ratios estimated by the TDF and the FDA, the methods predicted the same spectrum type in 17 out of 18 voxels of the in vivo case study (94.4%). Copyright © 2006 John Wiley & Sons, Ltd. [source] The effects of nutritional imbalance on compensatory feeding for cellulose-mediated dietary dilution in a generalist caterpillarPHYSIOLOGICAL ENTOMOLOGY, Issue 2 2004Kwang Pum Lee Abstract. The interactive effects of macronutrient balance [protein (P) : carbohydrate (C) ratio] and dietary dilution by cellulose on nutritional regulation and performance were investigated in the generalist caterpillar Spodoptera littoralis (Boisduval). Caterpillars were reared through the final stadium on one of 20 foods varying factorially in macronutrient content (P + C%: 42, 33.6. 25.2 or 16.8%) and P : C ratio (5 : 1, 2 : 1, 1 : 1, 1 : 2 or 1 : 5). The animals compensate by eating more of diluted foods, but suffer reduced nutrient intake in proportion to the degree of dilution. Increase in food intake with dilution is greater on balanced than imbalanced foods and this is reflected in greater reduction of dry pupal mass with dilution in the latter. Whereas dilution results in a reduction in the amount of whichever macronutrient is in excess in the food, by contrast, the ability to compensate for the deficient macronutrient in the food is unaffected by nutrient imbalance. Excess protein intake due to nutritional imbalance (diets with high P : C ratios) results in a regulatory decrease in the efficiency of retention of ingested nitrogen relative to restricted protein intake on oppositely imbalanced foods (low P : C ratios). By contrast, decreased protein intake due to dietary dilution is associated with a non-regulatory reduction in the efficiency of retention, irrespective of P : C ratio. Dilution is similarly associated with reduced utilization efficiency of ingested carbohydrate. The ecological implications of these results are discussed. [source] Increasing amino acid supply in pea embryos reveals specific interactions of N and C metabolism, and highlights the importance of mitochondrial metabolismTHE PLANT JOURNAL, Issue 6 2008Kathleen Weigelt Summary The application of nitrogen to legumes regulates seed metabolism and composition. We recently showed that the seed-specific overexpression of amino acid permease VfAAP1 increases amino acid supply, and the levels of N and protein in the seeds. Two consecutive field trials using Pisum sativum AAP1 lines confirmed increases in the levels of N and globulin in seed; however, compensatory changes of sucrose/starch and individual seed weight were also observed. We present a comprehensive analysis of AAP1 seeds using combinatorial transcript and metabolite profiling to monitor the effects of nitrogen supply on seed metabolism. AAP1 seeds have increased amino acids and stimulated gene expression associated with storage protein synthesis, maturation, deposition and vesicle trafficking. Transcript/metabolite changes reveal the channelling of surplus N into the transient storage pools asparagine and arginine, indicating that asparagine synthase is transcriptionally activated by high N levels and/or C limitation. Increased C-acceptor demand for amino acid synthesis, resulting from elevated levels of N in seeds, initiates sucrose mobilization and sucrose-dependent pathways via sucrose synthase, glycolysis and the TCA cycle. The AAP1 seeds display a limitation in C, which leads to the catabolism of arginine, glutamic acid and methionine to putrescine, ,-alanine and succinate. Mitochondria are involved in the coordination of C/N metabolism, with branched-chain amino acid catabolism and a ,-amino-butyric acid shunt. AAP1 seeds contain higher levels of ABA, which is possibly involved in storage-associated gene expression and the N-dependent stimulation of sucrose mobilization, indicating that a signalling network of C, N and ABA is operating during seed maturation. These results demonstrate that legume seeds have a high capacity to regulate N:C ratios, and highlight the importance of mitochondria in the control of N,C balance and amino acid homeostasis. [source] Catalysts for water,gas shift processing of coal-derived syngases,ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2010San Shwe Hla Abstract Although the gasification of coal is an efficient means of producing syngas, the carbon content of coal is such that gasification produces significantly higher ratios of carbon oxides to hydrogen than those obtained by the steam reforming of natural gas. The CO:H2 ratio can be adjusted, and more hydrogen produced, by the subsequent application of the water,gas shift (WGS) reaction. This article presents a review of technologies associated with the catalytic WGS reaction in a fixed-bed reactor that might be incorporated into a coal gasification-based system for H2 production with CO2 capture. The main output from this review is the identification of key project areas requiring further research. The performance of existing, commercially available catalysts,designed for use in natural gas reforming processes,with coal-derived syngases is an important aspect of developing technologies for coal-based H2 production. This article presents an experimental assessment of the performance of selected commercially available WGS catalysts, two high-temperature catalysts (HT01 and HT02) and a sour shift catalyst (SS01), with such syngases. For the three commercial catalysts investigated in this study, CO reaction order is found to be in a range of 0.75,1. The effect of changes in H2O concentration over HT01 is insignificant, whereas H2O reaction orders determined using HT02 and SS01 are found to be significantly positive even at high H2O:C ratios. The CO conversion rate is significantly reduced by increasing CO2 concentration, whereas increasing H2 concentration also causes a slight reduction in CO conversion rate for the three commercial catalysts investigated. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd. [source] What do dung beetles eat?ECOLOGICAL ENTOMOLOGY, Issue 6 2007PETER HOLTER Abstract 1.,Most adult coprophagous beetles feed on fresh dung of mammalian herbivores, confining ingestion to small particles with measured maximum diameters from 2,5 to 130 ,m, according to body size and kind of beetle. This study explores benefits and costs of selective feeding in a ,typical' dung beetle with a maximum diameter of ingested particles (MDIP) of 20 ,m. 2.,Examined dung types (from Danish domestic sheep, cattle and horse, and African wild buffalo, white rhino and elephant) contained 76,89% water. Costs of a 20 ,m MDIP were often low, since 69,87% of the total nitrogen in bulk dung other than that of elephant and rhino (40,58%) was available to selective feeders. 3.,Nitrogen concentrations were high , and C/N ratios low , in most types of bulk dung compared with the average food of terrestrial detritivores or herbivores. Exceptions were elephant and rhino dung with low nitrogen concentrations and high C/N ratios. 4.,Estimated C/N ratios of 13,39 in bulk dung (sheep,elephant) were decreased by selective feeding to 7.3,12.6 in the ingested material. In assimilated food, ratios are probably only 5,7, as most assimilable nitrogen and carbon may be of microbial origin. If so, the assimilable food contains a surplus of nitrogen relative to carbon. 5.,The primary advantage of selective feeding, particularly in dung with a high C/N ratio, may be to concentrate assimilable carbon in the ingested food. Effects of changing the MDIP within 20,106 ,m are modest, especially in dung with a low C/N ratio. [source] Respiratory protection of nitrogenase in Azotobacter species: is a widely held hypothesis unequivocally supported by experimental evidence?FEMS MICROBIOLOGY REVIEWS, Issue 4 2000Jürgen Oelze Abstract The hypothesis of respiratory protection, originally formulated on the basis of results obtained with Azotobacter species, postulates that consumption of O2 at the surface of diazotrophic prokaryotes protects nitrogenase from inactivation by O2. Accordingly, it is assumed that, at increased ambient O2 concentrations, nitrogenase activity depends on increased activities of a largely uncoupled respiratory electron transport system. The present review compiles evidence indicating that cellular O2 consumption as well as both the activity and the formation of the respiratory system of Azotobacter vinelandii are controlled by the C/N ratio, that is to say the ratio at which the organism consumes the substrate (i.e. the source of carbon, reducing equivalents and ATP) per source of compound nitrogen. The maximal respiratory capacity which can be attained at increased C/N ratios, however, is controlled, within limits, by the ambient O2 concentration. When growth becomes N-limited at increased C/N ratios, cells synthesize nitrogenase and fix N2. Under these diazotrophic conditions, cellular O2 consumption remains constant at a level controlled by the O2 concentration. Control by O2 has been studied on the basis of both whole cell respiration and defined segments of the respiratory electron transport chain. The results demonstrate that the effect of O2 on the respiratory system is restricted to the lower range of O2 concentrations up to about 70 ,M. Nevertheless, azotobacters are able to grow diazotrophically at dissolved O2 concentrations of up to about 230 ,M indicating that respiratory protection is not warranted at increased ambient O2 concentrations. This conclusion is supported and extended by a number of results largely excluding an obvious relationship between nitrogenase activity and the actual rate of cellular O2 consumption. On the basis of theoretical calculations, it is assumed that the rate of O2 diffusion into the cells is not significantly affected by respiration. All of these results lead to the conclusion that, in the protection of nitrogenase from O2 damage, O2 consumption at the cell surface is less effective than generally assumed. It is proposed that alternative factors like the supply of ATP and reducing equivalents are more important. [source] CO2 and nitrogen, but not population density, alter the size and C/N ratio of Phytolacca americana seedsFUNCTIONAL ECOLOGY, Issue 3 2005J.-S. HE Summary 1Plants can provision seeds by optimizing seed size, number and nutrient content to maximize parental fitness. According to the McGinley,Charnov hypothesis, seed size should be determined by the ratio of carbon to nitrogen (C/N) available to the plant, with larger seed size correlating with larger C/N ratios and smaller absolute N content. 2This hypothesis was tested by establishing monocultures of Phytolacca americana L. (Phytolaccaceae) at three population densities under ambient and elevated CO2 environments, with two availabilities of soil N. 3Elevated CO2 reduced both seed size and N concentration while increasing the C/N ratio; high soil N availability produced the opposite result for N concentration and C/N ratio. Higher planting densities reduced plant biomass, but did not alter seed size. 4In accordance with the McGinley,Charnov hypothesis, larger seeds had both larger C/N ratios and smaller N content. However, the increase in C/N ratio caused by elevated CO2 corresponded with smaller seeds overall: elevated CO2 reduced seed size, although the seed size,C/N relationship remained positive. 5These results suggest an alternative mechanism to explain variation in seed size, and suggest that future climate conditions may alter seed quality and plant reproductive behaviour. [source] Effects of temperature and fertilization on nitrogen cycling and community composition of an urban lawnGLOBAL CHANGE BIOLOGY, Issue 9 2008NEETA S. BIJOOR Abstract We examined the influence of temperature and management practices on the nitrogen (N) cycling of turfgrass, the largest irrigated crop in the United States. We measured nitrous oxide (N2O) fluxes, and plant and soil N content and isotopic composition with a manipulative experiment of temperature and fertilizer application. Infrared lamps were used to increase surface temperature by 3.5±1.3 °C on average and control and heated plots were split into high and low fertilizer treatments. The N2O fluxes increased following fertilizer application and were also directly related to soil moisture. There was a positive effect of warming on N2O fluxes. Soils in the heated plots were enriched in nitrogen isotope ratio (,15N) relative to control plots, consistent with greater gaseous losses of N. For all treatments, C4 plant C/N ratio was negatively correlated with plant ,15N, suggesting that low leaf N was associated with the use of isotopically depleted N sources such as mineralized organic matter. A significant and unexpected result was a large, rapid increase in the proportion of C4 plants in the heated plots relative to control plots, as measured by the carbon isotope ratio (,13C) of total harvested aboveground biomass. The C4 plant biomass was dominated by crabgrass, a common weed in C3 fescue lawns. Our results suggest that an increase in temperature caused by climate change as well as the urban heat island effect may result in increases in N2O emissions from fertilized urban lawns. In addition, warming may exacerbate weed invasions, which may require more intensive management, e.g. herbicide application, to manage species composition. [source] Nitrogen-regulated effects of free-air CO2 enrichment on methane emissions from paddy rice fieldsGLOBAL CHANGE BIOLOGY, Issue 9 2006XUNHUA ZHENG Abstract Using the free-air CO2 enrichment (FACE) techniques, we carried out a 3-year mono-factorial experiment in temperate paddy rice fields of Japan (1998,2000) and a 3-year multifactorial experiment in subtropical paddy rice fields in the Yangtze River delta in China (2001,2003), to investigate the methane (CH4) emissions in response to an elevated atmospheric CO2 concentration (200±40 mmol mol,1 higher than that in the ambient atmosphere). No significant effect of the elevated CO2 upon seasonal accumulative CH4 emissions was observed in the first rice season, but significant stimulatory effects (CH4 increase ranging from 38% to 188%, with a mean of 88%) were observed in the second and third rice seasons in the fields with or without organic matter addition. The stimulatory effects of the elevated CO2 upon seasonal accumulative CH4 emissions were negatively correlated with the addition rates of decomposable organic carbon (P<0.05), but positively with the rates of nitrogen fertilizers applied in either the current rice season (P<0.05) or the whole year (P<0.01). Six mechanisms were proposed to explain collectively the observations. Soil nitrogen availability was identified as an important regulator. The effect of soil nitrogen availability on the observed relation between elevated CO2 and CH4 emission can be explained by (a) modifying the C/N ratio of the plant residues formed in the previous growing season(s); (b) changing the inhibitory effect of high C/N ratio on plant residue decomposition in the current growing season; and (c) altering the stimulatory effects of CO2 enrichment upon plant growth, as well as nitrogen uptake in the current growing season. This study implies that the concurrent enrichment of reactive nitrogen in the global ecosystems may accelerate the increase of atmospheric methane by initiating a stimulatory effect of the ongoing dramatic atmospheric CO2 enrichment upon methane emissions from nitrogen-poor paddy rice ecosystems and further amplifying the existing stimulatory effect in nitrogen-rich paddy rice ecosystems. [source] Consequences of simultaneous elevation of carbon dioxide and temperature for plant,herbivore interactions: a metaanalysisGLOBAL CHANGE BIOLOGY, Issue 1 2006E. L. ZVEREVA Abstract The effects of elevated carbon dioxide on plant,herbivore interactions have been summarized in a number of narrative reviews and metaanalyses, while accompanying elevation of temperature has not received sufficient attention. The goal of our study is to search, by means of metaanalysis, for a general pattern in responses of herbivores, and plant characteristics important for herbivores, to simultaneous experimental increase of carbon dioxide and temperature (ECET) in comparison with both ambient conditions and responses to elevated CO2 (EC) and temperature (ET) applied separately. Our database includes 42 papers describing studies of 31 plant species and seven herbivore species. Nitrogen concentration and C/N ratio in plants decreased under both EC and ECET treatments, whereas ET had no significant effect. Concentrations of nonstructural carbohydrates and phenolics increased in EC, decreased in ET and did not change in ECET treatments, whereas terpenes did not respond to EC but increased in both ET and ECET; leaf toughness increased in both EC and ECET. Responses of defensive secondary compounds to treatments differed between woody and green tissues as well as between gymnosperm and angiosperm plants. Insect herbivore performance was adversely affected by EC, favoured by ET, and not modified by ECET. Our analysis allowed to distinguish three types of relationships between CO2 and temperature elevation: (1) responses to EC do not depend on temperature (nitrogen, C/N, leaf toughness, phenolics in angiosperm leaves), (2) responses to EC are mitigated by ET (sugars and starch, terpenes in needles of gymnosperms, insect performance) and (3) effects emerge only under ECET (nitrogen in gymnosperms, and phenolics and terpenes in woody tissues). This result indicates that conclusions of CO2 elevation studies cannot be directly extrapolated to a more realistic climate change scenario. The predicted negative effects of CO2 elevation on herbivores are likely to be mitigated by temperature increase. [source] Effects of influent C/N ratio, C/P ratio and volumetric exchange ratio on biological phosphorus removal in UniFed SBR processJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 12 2008Chen-hong Zhao Abstract BACKGROUND: UniFed SBR is a novel process that can achieve high levels of nitrogen and phosphorus removal simultaneously in a simple single SBR tank. In this study, effects of influent C/N ratio, influent C/P ratio and volumetric exchange ratio on biological phosphorus removal in UniFed SBR process were investigated in a lab-scale UniFed apparatus treating real domestic wastewater. RESULTS: The results showed that phosphorus removal efficiency increased as C/N ratio increased from 27% at 2.8 to 88% at 5.7. For C/N ratios 6.5 and above, complete phosphorus removal could be achieved. When C/N ratios and volumetric exchange ratio were fixed at 6 and 33%, respectively, phosphorus removal efficiency remained at 100% for C/P ratios higher than 33; effluent phosphate concentration was below the detection limit. For C/P ratios lower than 33, phosphorus removal efficiency decreased linearly with C/P ratio. Under the same influent C/N ratio and C/P ratio, the following factors all contributed to better phosphorus removal performance: greater volumetric exchange ratio; more organic substrate for PAOs to utilize, less inhibition by NOx, of phosphorus release during the feed/decant period; more PHB synthesized; and more aerobic phosphate uptake. CONCLUSION: High influent C/N ratio, high C/P ratio and high volumetric exchange ratio were beneficial to phosphorus removal in this process. Copyright © 2008 Society of Chemical Industry [source] Effects of organic matter and initial carbon,nitrogen ratio on the bioconversion of volatile fatty acids from sewage sludgeJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2008Xiaoling Liu Abstract BACKGROUND: The biodegradable organic matter and the initial carbon,nitrogen ratio can be substantially different in different batches of sewage sludge, which results in a difference in the acidification efficiency of sludge. Using sewage sludge from three different sources, batch tests were performed to analyze the relationship between volatile fatty acids (VFAs) and consumed organic matter, and to investigate the effects of initial carbon,nitrogen (C/N) ratio on the acidification efficiency of sludge. RESULTS: Maximum yields of 152.1 ± 3.5 mg total VFAs-COD per gram volatile solid (VS) added and 22.4 ± 1.2 mg butyric acid-COD g,1 VS added were obtained from the sludge with the highest initial C/N ratio. Statistical analysis indicated that protein was the major substrate for the produced VFAs. The sludge with the least initial C/N ratio (5.01) had the least yield, and only acetic acid, which was also mainly related to protein, was detected. CONCLUSION: The initial carbon,nitrogen ratio was one of the most important factors influencing the distribution patterns of VFAs and the yield of total VFAs produced from sewage sludge. A high C/N ratio could not only improve the yield of total VFAs but also enhance the yield of butyric acid. Copyright © 2008 Society of Chemical Industry [source] EFFECT OF NUTRIENT DEPRIVATION AND RESUPPLY ON METABOLITES AND ENZYMES RELATED TO CARBON ALLOCATION IN GRACILARIA TENUISTIPITATA (RHODOPHYTA),JOURNAL OF PHYCOLOGY, Issue 2 2004Pi Nyvall Collén The starch content of red algae normally increases during nitrogen limitation. Based on this we hypothesized that nutrient deprivation would result in an increased activity of starch-synthesizing enzymes and a decrease in the activity of starch-degrading enzymes, with the opposite scenario when nutrients were sufficient. We therefore examined the effect of the nutrient status of Gracilaria tenuistipitata Chang et Xia on the content of starch and floridoside and on the activity of enzymes involved in the allocation of carbon into starch, floridoside, and agar; floridoside phosphate synthase and ,-galactosidase involved in synthesis and degradation of floridoside; starch synthase and starch phosphorylase involved in the metabolism of starch; uridine 5,-diphosphate (UDP)-glucose pyrophosphorylase; adenosine 5,-diphosphate-glucose pyrophosphorylase; UDP-glucose 4-epimerase; and phosphoglucomutase. During the period of nutrient limitation the starch and floridoside content increased, as did dry weight and C/N ratio, whereas growth rate and protein content decreased. A general decrease in the enzyme activities during nutrient limitation was also observed, indicating a decrease in overall cellular metabolism. The addition of nutrients caused an increase in enzyme activities and a decrease in the contents of starch and floridoside. Of the enzymes examined, only the activity of UDP-glucose pyrophosphorylase increased during nutrient limitation and decreased abruptly after nutrient addition. This implies a regulatory role for this enzyme in the supply of UDP-glucose for starch synthesis. It also supports our suggestion that UDP-glucose is the substrate for starch synthesis in red algae. This assertion is further strengthened by the observation that of the potential starch synthases only the UDP-glucose starch synthase could support the observed rate of starch synthesis. [source] Multi-scale analysis of soil erosion dynamics in Kwazulu-Natal, South AfricaLAND DEGRADATION AND DEVELOPMENT, Issue 3 2005M. P. W. Sonneveld Abstract For a case study area in the Okhombe catchment in the province of KwaZulu-Natal, South Africa, a multi-scale analysis of soil erosion dynamics was performed. At sub-catchment level, the dynamics of erosional features were investigated by means of aerial photographs. At site level, the changes in soil physical and chemical properties were investigated by means of a fence-line contrast study. Attention was paid to both surface and subsurface erosion phenomena. The number of erosional features in the study area in 2000 was not substantially different from the number of features in 1945. At sub-catchment level, an increase in the number of gullies was observed from 1975 to 2000 but this followed a substantial inactivation of most erosional features from 1962 to 1975. Increases in erosional activity in 1962 compared to 1945 were mainly related to abandoned cultivated fields. At site level, a significant decrease in soil C/N ratio was observed within the fenced site within three years. For the same site, total carbon, saturated hydraulic conductivity and bulk density were not significantly different for the topsoil inside the fenced area compared with outside. Subsurface erosion phenomena mainly occur in the communal grazing areas and are mostly related to transitions between permeable and less permeable layers. The complex relationships between soil erosion, land use change and climate might further be understood by involving local people in the development, monitoring and evaluation of alternative types of land use, which is also likely to facilitate future steps in controlled grazing management. Copyright © 2005 John Wiley & Sons, Ltd. [source] Variability in the nutritional value of the major copepods in Cape Cod Bay (Massachusetts, USA) with implications for right whalesMARINE ECOLOGY, Issue 2 2006Amy DeLorenzo Costa Abstract The North Atlantic right whale, a seriously endangered species, is found in Cape Cod Bay (Massachusetts, USA) during the winter and early spring. During their residency in these waters, these whales are frequently observed feeding. This study evaluated spatial and temporal changes in the chemical composition (carbon weight and C/N ratio) of the food resource targeted by the right whales in Cape Cod Bay. The three taxa measured (Centropages typicus, Pseudocalanus spp., and Calanus finmarchicus) had highly variable chemical compositions resulting from the different life strategies and from fluctuations in their surrounding environment. The impact of seasonal variability in the energy densities of the food resource of right whales was calculated and compared to the energetic requirements of these whales. Calculations indicated that differences in the nutritional content of the zooplankton prey in Cape Cod Bay could have a considerable effect on the nutrition available to the right whales. Therefore, it is likely that using more precise estimates of the energetic densities of the prey of right whales would lead to a re-evaluation of the adequacy of the food resource available to these whales in the North Atlantic. [source] Modification of Primary and Secondary Metabolism of Potato Plants by Nitrogen Application Differentially Affects Resistance to Phytophthora infestans and Alternaria solaniPLANT BIOLOGY, Issue 5 2006K. Mittelstraß Abstract: Potato plants (Solanum tuberosum L. cv. Indira) were grown at two levels of N supply in the greenhouse. Plants supplied with 0.8 g N per plant (high N variant) showed significantly increased biomass as compared to plants without additional N fertilisation (low N variant). C/N ratio was lower and protein content was higher in leaves of the high N variant. The concentration of chlorogenic acids and flavonols was significantly lower in leaves from the high N variant. Whereas resistance to Alternaria solani increased when plants were supplied with additional nitrogen, these plants were more susceptible to Phytophthora infestans. After infection with both pathogens, we found a strong induction of p-coumaroylnoradrenaline and p-coumaroyloctopamine, which are identified for the first time in potato leaves and are discussed as resistance factors of other solanaceous plants. [source] ,15N of soil N and plants in a N-saturated, subtropical forest of southern ChinaRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 17 2010K. Koba We investigated the ,15N profile of N (extractable NH, NO, and organic N (EON)) in the soil of a N-saturated subtropical forest. The order of ,15N in the soil was EON,>,NH,>,NO. Although the ,15N of EON had been expected to be similar to that of bulk soil N, it was higher than that of bulk soil N by 5,. The difference in ,15N between bulk soil N and EON (,15Nbulk-EON) was correlated significantly with the soil C/N ratio. This correlation implies that carbon availability, which determines the balance between N assimilation and dissimilation of soil microbes, is responsible for the high ,15N of EON, as in the case of soil microbial biomass ,15N. A thorough ,15N survey of available N (NH, NO, and EON) in the soil profiles from the organic layer to 100,cm depth revealed that the ,15N of the available N forms did not fully overlap with the ,15N of plants. This mismatch in ,15N between that of available N and that of plants reflects apparent isotopic fractionation during N uptake by plants, emphasizing the high N availability in this N-saturated forest. Copyright © 2010 John Wiley & Sons, Ltd. [source] Analysing the isotopic life history of the alpine ungulates Capra ibex and Rupicapra rupicapra rupicapra through their hornsRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 15 2009Inęs C. R. Barbosa The horn of ungulate grazers offers a valuable isotopic record of their diet and environment. However, there have been no reports of the spatio-temporal variation of the isotopic composition of horns. We investigated patterns of carbon (,13C) and nitrogen (,15N) isotopic composition along and perpendicular to the horn axis in Capraibex and Rupicaprarupicaprarupicapra to assess the effects of animal age, within-year (seasonal) and inter-annual variation, natural contamination and sampling position on horn isotope composition. Horns of male C. ibex (n,=,23) and R. r. rupicapra (n,=,1) were sampled longitudinally on the front (only R. r. rupicapra) and back side and on the surface and sub-surface. The sides of the R. r. rupicapra horn did not differ in ,13C. In both species, the horn surface had a 0.15, lower ,13C and a higher carbon-to-nitrogen (C/N) ratio than the sub-surface. Washing the horn with water and organic solvents removed material that caused these differences. With age, the ,15N of C. ibex horns increased (+0.1, year,1), C/N ratio increased, and 13C discrimination relative to atmospheric CO2 (13,) increased slightly (+0.03, year,1). Geostatistical analysis of one C. ibex horn revealed systematic patterns of inter-annual and seasonal 13C changes, but 15N changed only seasonally. The work demonstrates that isotopic signals in horns are influenced by natural contamination (,13C), age effects (13, and ,15N), and seasonal (,13C and ,15N) and inter-annual variation (,13C). The methods presented allow us to distinguish between these effects and thus allow the use of horns as isotopic archives of the ecology of these species and their habitat. Copyright © 2009 John Wiley & Sons, Ltd. [source] Non-symbiotic nitrogen fixation during leaf litter decomposition in an old-growth temperate rain forest of Chiloé Island, southern Chile: Effects of single versus mixed species litterAUSTRAL ECOLOGY, Issue 2 2010CECILIA A. PÉREZ Abstract Heterotrophic nitrogen fixation is a key ecosystem process in unpolluted, temperate old-growth forests of southern South America as a source of new nitrogen to ecosystems. Decomposing leaf litter is an energy-rich substrate that favours the occurrence of this energy demanding process. Following the niche ,complementarity hypothesis', we expected that decomposing leaf litter of a single tree species would support lower rates of non-symbiotic N fixation than mixed species litter taken from the forest floor. To test this hypothesis we measured acetylene reduction activity in the decomposing monospecific litter of three evergreen tree species (litter C/N ratios, 50,79) in an old-growth rain forest of Chiloé Island, southern Chile. Results showed a significant effect of species and month (anova, Tukey's test, P < 0.05) on decomposition and acetylene reduction rates (ARR), and a species effect on C/N ratios and initial % N of decomposing leaf litter. The lowest litter quality was that of Nothofagus nitida (C/N ratio = 78.7, lignin % = 59.27 ± 4.09), which resulted in higher rates of acetylene reduction activity (mean = 34.09 ± SE = 10.34 nmol h,1 g,1) and a higher decomposition rate (k = 0.47) than Podocarpus nubigena (C/N = 54.4, lignin % = 40.31 ± 6.86, Mean ARR = 4.11 ± 0.71 nmol h,1 g,1, k = 0.29), and Drimys winteri (C/N = 50.6, lignin % = 45.49 ± 6.28, ARR = 10.2 ± 4.01 nmol h,1 g,1, k = 0.29), and mixed species litter (C/N = 60.7, ARR = 8.89 ± 2.13 nmol h,1g,1). We interpret these results as follows: in N-poor litter and high lignin content of leaves (e.g. N. nitida) free-living N fixers would be at competitive advantage over non-fixers, thereby becoming more active. Lower ARR in mixed litter can be a consequence of a lower litter C/N ratio compared with single species litter. We also found a strong coupling between in situ acetylene reduction and net N mineralization in surface soils, suggesting that as soon N is fixed by diazotroph bacteria it may be immediately incorporated into mineral soil by N mineralizers, thus reducing N immobilization. [source] Litterfall dynamics and nitrogen use efficiency in two evergreen temperate rainforests of southern ChileAUSTRAL ECOLOGY, Issue 6 2003CECILIA A. PEREZ Abstract In unpolluted regions, where inorganic nitrogen (N) inputs from the atmosphere are minimal, such as remote locations in southern South America, litterfall dynamics and N use efficiency of tree species should be coupled to the internal N cycle of forest ecosystems. This hypothesis was examined in two evergreen temperate forests in southern Chile (42°30'S), a mixed broad-leaved forest (MBF) and a conifer forest (CF). Although these forests grow under the same climate and on the same parental material, they differ greatly in floristic structure and canopy dynamics (slower in the CF). In both forests, biomass, N flux, and C/N ratios of fine litterfall were measured monthly from May 1995 to March 1999. There was a continuous litter flux over the annual cycle in both forests, with a peak during autumn in the CF. In the MBF, litterfall decreased during spring. In both forests, the C/N ratios of litterfall varied over the annual cycle with a maximum in autumn. Annual litterfall biomass flux (Mean ± SD = 3.3 ± 0.5 vs 2.0 ± 0.5 Mg ha -1) and N return (34.8 ± 16 vs 9.1 ± 2.8 kg N ha -1) were higher in the MBF than in the CF. At the ecosystem level, litterfall C/N was lower in the MBF (mean C/N ratio = 60.1 ± 15, n= 3 years) suggesting decreased N use efficiency compared with CF (mean C/N ratio = 103 ± 19.6, n= 3 years). At the species level, subordinated (subcanopy) tree species in the MBF had significantly lower C/N ratios (<50) of litterfall than the dominant trees in the CF and MBF (>85). The litterfall C/N ratio and percentage N retranslocated were significantly correlated and were lower in the MBF. The higher net N mineralization in soils of the MBF is related to a lower N use efficiency at the ecosystem and species level. [source] | ||||||||||||||||||||||||||||||||||||||||