Retention Of Carbohydrates Research Articles

Response of carbon fixation, allocation, and growth to source-sink manipulation by defoliation in vegetative citrus trees.

Source-sink balance in plants determines carbon distribution, and altering it can impact carbon fixation, transport, and allocation. We aimed to investigate the effect of altered source-sink ratios on carbon fixation, transport, and distribution in 'Valencia' sweet orange (Citrus x sinensis) by various defoliation treatments (0%, 33%, 66%, and 83% leaf removal). Gas exchange parameters were measured on 0 and 10 days after defoliation using A/Ci response curves, and leaf export was measured two days after defoliation using radioisotope tracer techniques. Greater defoliation increased the maximum rate of carboxylation (Vcmax), electron transport rate (J1200), and triose-phosphate utilization rate (TPU). Leaf export was unaffected by defoliation but increased in leaves closer to the shoot apex. Basipetal translocation velocity in the trunk remained unaltered, indicating that more photosynthates remained in the shoot rather than being transported directly to the root sink. Defoliated plants initiated more new flush shoots but accumulated less shoot biomass per plant after 8 weeks. Carbon allocation to fine roots was smaller in defoliated plants, suggesting defoliation led to retention of carbohydrates in aboveground organs such as the trunk and other shoots from previous growing cycles. In conclusion, the low source-sink ratio increased carbon fixation without impacting individual leaf export in citrus. The results suggest that intermediate sinks such as the aboveground perennial organs play a role in mediating the translocation velocity. Further research is necessary to better understand the dynamics of source-sink regulation in citrus trees.

How does adsorptive fractionation of dissolved black carbon on ferrihydrite affect its copper binding behaviors? A molecular-scale investigation

Adsorptive fractionation of dissolved black carbon (DBC) on minerals is proven to alter its molecular composition, which will inevitably affect the environment fate of heavy metals. However, the effects of molecular fractionation on the interaction between DBC and heavy metals remain unclear. Herein, we observed that the selective adsorption of ferrihydrite caused molecular changes of DBC from high molecular weight/unsaturation/aromaticity to low molecular weight/saturation/aliphatics. This process accompanied by a retention of carbohydrate and a reduction of oxygen-rich functional groups (e.g., polyphenols and carboxyl) and long carbon chain in DBC. The residual DBC in aqueous phase demonstrated a weaker binding affinity to copper compared to the original DBC. This decrease in binding affinity was primarily attributed to the adsorption of polycyclic condensed aromatic compounds of 200–250 Da, oxygen-rich polycyclic condensed aromatic compounds of 250–300 Da, oxygen-rich non-polycyclic aromatic compounds of 300–450 Da, and non-polycyclic aromatic compounds of 450–700 Da in DBC by ferrihydrite. Additionally, the retention of carbohydrates and aliphatic compounds of 300–450 Da also made a significant contribution. Notably, carboxylic groups rather than phenolic groups were the dominant oxygen-containing functional groups responsible for this affinity reduction. This study has significant implications for understanding of the biogeochemical processes of DBC at soil-water interface and surface water, especially its role in the transportation of heavy metals.

Retention behavior of carbohydrates on metal loaded chelating stationary phase under conditions of hydrophilic interaction liquid chromatography

The chromatographic retention of carbohydrates on chelating stationary phase loaded with different metal ions was studied under conditions of hydrophilic interaction chromatography (HILIC). The chelating stationary phases represented silica microparticles with immobilized 2-hydroxyethyliminodiacetic acid (HEIDA) groups in loose form and saturated with Ca2+, Pb2+, and La3+form. The role of loaded metal ion, the acetonitrile and methanol content in the mobile phase, buffer pH and column temperature on the retention of l-(+)-arabinose, d-(+)-maltose, l-(+)-rhamnose, d-(+)-lactose, d-(+)-xylose, glucose, fructose, sucrose, mannose, maltotriose and d-(+) raffinose was studied. The investigation was mainly focused on possible contribution of the complexation in the stationary phase on retention of carbohydrates as well as on effect of the presence metal ion in HEIDA-silica on resulting HILIC behavior of. It is shown that adsorbents with immobilized metal complexes have a good potential for the separation of organic ligands under HILIC mode.

One-Pot Protolignin Extraction by Targeted Unlocking Lignin-Carbohydrate Esters via Nucleophilic Addition-Elimination Strategy.

Protolignin extraction can facilitate structure elucidation and valorization of lignin in biorefinery, but is rather challenging due to the complex chemical bonds present. Here, we developed the insitu generated NH3-reline (IGNR) system to realize one-pot protolignin extraction from lignocellulose. In the IGNR system, reline consisting of choline chloride and urea acted as both a solvent and a nucleophile generator, and the nucleophilic addition-elimination mechanism was verified by model compound studies. The insitu generated NH3 could precisely cleave the lignin-carbohydrate esters in lignocellulose with a near-quantitative retention of carbohydrates. The extracted IGNR-Protolignin exhibited native lignin substructure with high molecular weight and high β-O-4' content (41.5 per 100 aromatic units). In addition, the up-scaled kilogram reaction demonstrated the feasibility of the IGNR system for potential industrial application in a green and sustainable pathway. This work represents a breakthrough toward protolignin extraction in practice with the future goal of achieving total biorefinery.

Anomeric Retention of Carbohydrates in Multistage Cyclic Ion Mobility (IMSn): De Novo Structural Elucidation of Enzymatically Produced Mannosides

Carbohydrates are complex structures that still challenge analysts today because of their different levels of isomerism, notably the anomerism of the glycosidic bond. It has been shown recently that anomerism is preserved upon gas-phase fragmentation and that high-resolution ion mobility (IMS) can distinguish anomers. However, these concepts have yet to be applied to complex biological products. We have used high-resolution IMS on a cyclic device to characterize the reaction products of Uhgb_MS, a novel mannoside synthase of the GH130 family. We designed a so-called IMSn sequence consisting of (i) separating and isolating specific IMS peaks, (ii) ejecting ions to a pre-array store cell depending on their arrival time, (iii) inducing collisional activation upon reinjection, and (iv) performing multistage IMS analysis of the fragments. First, we applied IMS2 sequences to purely linked α1,2- and β1,2-mannooligosaccharides, which provided us with reference drift times for fragments of known conformation. Then, we performed IMSn analyses of enzymatically produced mannosides and, by comparison with the references, we succeeded in determining the intrachain anomerism of a α1,2-mannotriose and a mix-linked β/α1,2-mannotetraose-a first for a crude biological medium. Our results show that the anomerism of glycosides is maintained through multiple stages of collisional fragmentation, and that standalone high-resolution IMS and IMSn can be used to characterize the intrachain anomerism in tri- and tetrasaccharides in a biological medium. This is also the first evidence that a single carbohydrate-active enzyme can synthesize both α- and β-glycosidic linkages.

Carbohydrate concentrations and enzyme activities as influenced by exchangeable cations, mineralogy and clay content

Abstract Enzymes can exist in bound or free form within the soil, but the impact of interactions between extracellular enzymes with the amount and type of clay minerals and exchangeable cations on the activities of enzymes and decomposition or retention of carbohydrates in soil is still poorly understood. Appropriate amounts of homoionic Na-, Ca- and Al-clay minerals from Georgia kaolinite, Illinois illite and Wyoming montmorillonite were mixed with pure sand to prepare artificial soils with different clay contents, exchange cations and clay types to examine the effects of exchangeable cations, mineralogy and clay content on the concentrations of hot water and dilute acid extractable carbohydrates and activities of acid and alkaline phosphatases and CM-cellulase. There was a significant effect of clay content on the concentrations of carbohydrates and activities of enzymes. The concentrations of carbohydrates increased when the clay contents of soils increased from 0 to 5 and 10%, respectively, showing that the clay contents influence the capacity of soils for stabilization of carbohydrates. But opposite trends were found in enzyme activities. The enzyme activities decreased significantly as the clay contents of the artificial soils increased. The concentrations of carbohydrates and activities of enzymes were significantly affected by exchangeable cations. In soils with 5 and 10% clay, the concentrations of carbohydrates were maximum in Al-soils and minimum in Ca-soils, in contrast, the activities of enzymes were maximum in Ca-soils and minimum in Al-soils. There was a significant effect of clay mineralogy on the concentrations of carbohydrates and activities of enzymes. The concentrations of carbohydrates were highest in soils with Wyoming montmorillonite clay mineral and lowest in soils with Georgia kaolinite clay mineral. But the activities of enzymes were lower in soils with Wyoming montmorillonite clay mineral than soils with Georgia kaolinite and Illinois illite clay minerals, indicating the influence of specific surface area (SSA) and cation exchange capacity (CEC) of clay minerals on carbohydrate retention and enzyme activities. The results of this study indicate that carbohydrates are stabilized in soils through the interaction with clay minerals and a small amount of clay (5%) significantly increases carbohydrate retention and reduces enzyme activities in soils. Exchangeable cations exert their influence on enzyme activities and hence carbohydrate dynamics by controlling the activities of enzymes through modifying the physicochemical characteristics of soils.

Systematic evaluation of retention behavior of carbohydrates in hydrophilic interaction liquid chromatography

A systematic evaluation of retention behavior of carbohydrates in hydrophilic interaction liquid chromatography (HILIC) was performed. The influences of mobile phase, stationary phase and buffer salt on the retention of carbohydrates were investigated. According to the results, the retention time of carbohydrates decreased as the proportion of acetonitrile in mobile phase decreased. Increased time of carbohydrates was observed as the concentration of buffer salt in mobile phase increased. The retention behavior of carbohydrates was also affected by organic solvent and HILIC stationary phase. Furthermore, an appropriate retention equation was used in HILIC mode. The retention equation lnk = a + blnC(B) + cC(B) could quantitatively describe the retention factors of carbohydrates of plant origin with good accuracy: the relative error of the predicted time to actual time was less than 0.3%. The evaluation results could provide guidance for carbohydrates to optimize the experimental conditions in HILIC method development especially for carbohydrate separation

RUMINANT NUTRITION SYMPOSIUM: Productivity, digestion, and health responses to hindgut acidosis in ruminants1

Microbial fermentation of carbohydrates in the hindgut of dairy cattle is responsible for 5 to 10% of total-tract carbohydrate digestion. When dietary, animal, or environmental factors contribute to abnormal, excessive flow of fermentable carbohydrates from the small intestine, hindgut acidosis can occur. Hindgut acidosis is characterized by increased rates of production of short-chain fatty acids including lactic acid, decreased digesta pH, and damage to gut epithelium as evidenced by the appearance of mucin casts in feces. Hindgut acidosis is more likely to occur in high-producing animals fed diets with relatively greater proportions of grains and lesser proportions of forage. In these animals, ruminal acidosis and poor selective retention of fermentable carbohydrates by the rumen will increase carbohydrate flow to the hindgut. In more severe situations, hindgut acidosis is characterized by an inflammatory response; the resulting breach of the barrier between animal and digesta may contribute to laminitis and other disorders. In a research setting, effects of increased hindgut fermentation have been evaluated using pulse-dose or continuous abomasal infusions of varying amounts of fermentable carbohydrates. Continuous small-dose abomasal infusions of 1 kg/d of pectin or fructans into lactating cows resulted in decreased diet digestibility and decreased milk fat percentage without affecting fecal pH or VFA concentrations. The decreased diet digestibility likely resulted from increased bulk in the digestive tract or from increased digesta passage rate, reducing exposure of the digesta to intestinal enzymes and epithelial absorptive surfaces. The same mechanism is proposed to explain the decreased milk fat percentage because only milk concentrations of long-chain fatty acids were decreased. Pulse-dose abomasal fructan infusions (1 g/kg of BW) into steers resulted in watery feces, decreased fecal pH, and increased fecal VFA concentrations, without causing an inflammatory response. Daily 12-h abomasal infusions of a large dose of starch (~4 kg/d) have also induced hindgut acidosis as indicated by decreased fecal pH and watery feces. On the farm, watery or foamy feces or presence of mucin casts in feces may indicate hindgut acidosis. In summary, hindgut acidosis occurs because of relatively high rates of large intestinal fermentation, likely due to digestive dysfunction in other parts of the gut. A better understanding of the relationship of this disorder to other animal health disorders is needed.

Tie-dyed1 and Sucrose export defective1 act independently to promote carbohydrate export from maize leaves

tie-dyed1 (tdy1) and sucrose export defective1 (sxd1) are recessive maize (Zea mays) mutants with nonclonal chlorotic leaf sectors that hyperaccumulate starch and soluble sugars. In addition, both mutants display similar growth-related defects such as reduced plant height and inflorescence development due to the retention of carbohydrates in leaves. As tdy1 and sxd1 are the only variegated leaf mutants known to accumulate carbohydrates in any plant, we investigated whether Tdy1 and Sxd1 function in the same pathway. Using aniline blue staining for callose and transmission electron microscopy to inspect plasmodesmatal ultrastructure, we determined that tdy1 does not have any physical blockage or alteration along the symplastic transport pathway as found in sxd1 mutants. To test whether the two genes function in the same genetic pathway, we constructed F2 families segregating both mutations. Double mutant plants showed an additive interaction for growth related phenotypes and soluble sugar accumulation, and expressed the leaf variegation pattern of both single mutants indicating that Tdy1 and Sxd1 act in separate genetic pathways. Although sxd1 mutants lack tocopherols, we determined that tdy1 mutants have wild-type tocopherol levels, indicating that Tdy1 does not function in the same biochemical pathway as Sxd1. From these and other data we conclude that Tdy1 and Sxd1 function independently to promote carbon export from leaves. Our genetic and cytological studies implicate Tdy1 functioning in veins, and a model discussing possible functions of TDY1 is presented.Electronic supplementary materialThe online version of this article (doi:10.1007/s00425-007-0636-6) contains supplementary material, which is available to authorized users.

Tie-dyed1 Regulates carbohydrate accumulation in maize leaves.

Acquisition of cell identity requires communication among neighboring cells. To dissect the genetic pathways regulating cell signaling in later leaf development, a screen was performed to identify mutants with chloroplast pigmentation sectors that violate cell lineage boundaries in maize (Zea mays) leaves. We have characterized a recessive mutant, tie-dyed1 (tdy1), which develops stable, nonclonal variegated yellow and green leaf sectors. Sector formation requires high light, occurs during a limited developmental time, and is restricted to leaf blade tissue. Yellow tdy1 sectors accumulate excessive soluble sugars and starch, whereas green sectors appear unaffected. Significantly, starch accumulation precedes chlorosis in cells that will become a yellow sector. Retention of carbohydrates in tdy1 leaves is associated with a delay in reproductive maturity, decreased stature, and reduced yield. To explain the tdy1 sectoring pattern, we propose a threshold model that incorporates the light requirement and the hyperaccumulation of photoassimilates. A possible function consistent with this model is that TDY1 acts as a sugar sensor to regulate an inducible sugar export pathway as leaves develop under high light conditions.

Effect of temperature on the retention of amino acids and carbohydrates in high-performance anion-exchange chromatography

Effect of temperature on the retention of amino acids and carbohydrates in high-performance anion-exchange chromatography (HPAEC) was investigated. Amino acids retention exhibited both exothermic and endothermic behavior. Significant selectivity variations of some weakly retained amino acids were achieved through changing temperature. However, temperature was almost ineffective at changing the selectivity of strongly retained amino acids. Sugars retention exhibited only exothermic behavior. However, individual carbohydrates showed different relative changes in retention time with increased temperature. There is the general regularity, which is the variation of retention time increases as the sequence of monosaccharide, disaccharide, trisaccharide and tetrasaccharide when the column temperature is increased. Selectivity changes of carbohydrates, including elution order reversal, were also achieved by varying temperature. Temperature was effective at changing the selectivity of between amino acids and carbohydrates. In achieving optimal separation of amino acids and carbohydrates, temperature is a valuable tool.

Retention of cellulose, xylan and lignin in kraft pulping of eucalyptus studied by multivariate data analysis: influences on physicochemical and mechanical properties of pulp

Effects of pulping variables on the retention of carbohydrates and lignin in fast kraft pulping of eucalyptus were investigated using a complete factorial design. Influences of pulp chemical composition on physicochemical and mechanical properties were evaluated using Principal Component Analysis. Active alkali (AA) significantly affected the macromolecular degradation of cellulose and retention of xylan and lignin. Cellulose retention was unaffected. The use of low AA in pulping improved all mechanical properties, but increased the kappa number and reduced ISO brightness. The degree of polymerization of cellulose was related to tensile index and elastic modulus while xylan affected the apparent sheet density. Tear index had a positive influence of fiber length and uronic acid groups, which were preserved in xylan by a combination of low AA, thin wood chips and a short pulping cycle. The characteristics, rather than the content of xylan, were suggested to be relevant to tear index.

A biochemical-based model for the dosimetry of dietary organically bound tritium--Part 1: Physiological criteria.

In this paper the physiological criteria for a novel form of model are described whose biokinetics are governed by the overall metabolic reactions of the principal nutrients: carbohydrates, fats, and proteins. The biokinetics of a particular element are based primarily on the oxidation of glucose, fatty acids, and amino acids and the formation of water, carbon dioxide, and urea. The compartmental models proposed follow the pathways of the major elements including hydrogen and, hence, tritium. The parameters for two models of differing complexity--called the HCNO-S and HCNO-C models--were evaluated here on the basis of biochemical reactions; the results of compartmental analysis are reported in an accompanying paper. The simpler form of the HCNO model has single compartments representing the principal nutrients. The more complex model includes compartments representing the longer-term retention of carbohydrates as glycogen, fats as adipose tissue, and proteins in bone and soft tissues. The pool sizes and hydrogen transfer rates are estimated. The incorporation of biochemical reactions and important metabolic parameters serve to give the models a greater semblance of physiological merit than those currently available. For example, ingestion of carbohydrates results in a respiratory quotient of 1.0 and 100% of the hydrogen content oxidized to water, which are the same as values published in the literature. This form of metabolic model enables development of models for other isotopes, besides 3H, of the major elements of the body, e.g., 14C, 15N, 18O.

A BIOCHEMICAL-BASED MODEL FOR THE DOSIMETRY OF DIETARY ORGANICALLY BOUND TRITIUM—PART 2: DOSIMETRIC EVALUATION

In this paper the dosimetry for a novel form of physiological model, whose biokinetics are governed by the overall metabolic reactions of the principal nutrients carbohydrates, fats and proteins, is evaluated by compartmental analysis. Two models of differing complexity, called the HCNO-S and HCNO-C models, were developed from parameters evaluated in an accompanying paper. The simpler form has single compartments representing the principal nutrients. The more complex model includes compartments representing the longer-term retention of carbohydrates as glycogen, fats as adipose tissue, and proteins in bone and soft tissues. The effective doses for various tritiated intakes are the same, or similar, as calculated by the two HCNO models, except for tritiated protein. The dose coefficient for an intake of tritiated water is approximately 8% greater than that recommended by the ICRP when the tritium body burden is considered as a homogenous pool. However, when the composition of individual organs is taken into account, the dose coefficient for an HTO intake is approximately 22% greater than the ICRP value. The HCNO-C dose coefficient for OBT in a normal diet is 5.0 x 10(-11) Sv Bq(-1), which is 1.2-fold greater than the ICRP dose coefficient for an OBT intake. The HCNO-C composition model gave organ and tissue doses with the largest range for a tritiated Reference Man dietary intake, the highest dose (red marrow, then breast) being around three-fold the lowest. A property of the HCNO models, important for bioassay analyses, is that a major part (> 90%) of an OBT intake is oxidized and excreted as HTO, which is physiologically more accurate than the current ICRP OBT model. The effective dose of specific tritiated foods, e.g., rice and wheat, was evaluated on the basis of their constituents.

Transformation of organic matter from maize residues into labile and humic fractions of three European soils as revealed by 13C distribution and CPMAS‐NMR spectra

SummaryThe dynamics of incorporation of fresh organic residues into the various fractions of soil organic matter have yet to be clarified in terms of chemical structures and mechanisms involved. We studied by 13C‐dilution analysis and CPMAS‐13C‐NMR spectroscopy the distribution of organic carbon from mixed or mulched maize residues into specific defined fractions such as carbohydrates and humic fractions isolated by selective extractants in a year‐long incubation of three European soils. The contents of carbohydrates in soil particle size fractions and relative δ13C values showed no retention of carbohydrates from maize but rather decomposition of those from native organic matter in the soil. By contrast, CPMAS‐13C‐NMR spectra of humic (HA) and fulvic acids (FA) extracted by alkaline solution generally indicated the transfer of maize C (mostly carbohydrates and peptides) into humic materials, whereas spectra of organic matter extracted with an acetone solution (HE) indicated solubilization of an aliphatic‐rich, hydrophobic fraction that seemed not to contain any C from maize. The abundance of 13C showed that all humic fractions behaved as a sink for C from maize residues but the FA fraction was related to the turnover of fresh organic matter more than the HA. Removal of hydrophobic components from incubated soils by acetone solution allowed a subsequent extraction of HA and, especially, FA still containing much C from maize. The combination of isotopic measurements and NMR spectra indicated that while hydrophilic compounds from maize were retained in HA and FA, hydrophobic components in the HE fraction had chemical features similar to those of humin. Our results show that the organic compounds released in soils by mineralization of fresh plant residues are stored mainly in the hydrophilic fraction of humic substances which are, in turn, stabilized against microbial degradation by the most hydrophobic humic matter. Our findings suggest that native soil humic substances contribute to the accumulation of new organic matter in soils.

Ion-pair LC of carbohydrates at alkaline pH. Separation and retention behaviour of glycoconjugates

A new technique for the separation of carbohydrates as ion-pairs in strongly alkaline solution is presented. Carbohydrates are weakly acidic and partly present as anions at pH≥12 [1]. They are retained as ion-pairs on polymeric solid phases (PRP-1 and PLRP-S) with a hydrophobic quaternary ammonium counter ion present in the mobile phase. The effects of nature and concentration of mobile phase components on the retention of carbohydrates have been investigated and an ion-pair distribution model is proposed. The influence of temperature indicated no changes in retention mechanism with high counter ion concentration, but the resolution decreased with increasing temperature. Saccharides added to the mobile phase were shown to increase the retention and the selectivity.

Plaque pH and oral retention after consumption of starchy snack products at normal and low salivary secretion rate.

The effect of plain potato chips, sugar-free cheese doodles, and sweetened crackers on plaque pH and oral retention was tested in 10 volunteers and compared with 5% starch and 5% sucrose, during both normal and low salivary secretion rate. The first 30 min 5% sucrose gave the most and 5% starch the least attenuated pH drop, but the three snack products reached or even passed the level seen by sucrose during the second 30-min phase. All products resulted in greater pH falls and remained at a low level for a longer period during low secretion rate. There were no differences in concentration of carbohydrates in saliva after consumption of potato chips, cheese doodles, and a cracker. However, low secretion rate increased the oral retention for all three products. To conclude, this study showed that low salivary secretion rate accentuated the pH decrease in dental plaque and prolonged the oral retention of carbohydrates.

Energieumsatzmessungen am adulten Schwein bei Verfütterung von Rationen mit Kartoffelstärke, Kartoffeln, Rüben, Preßschnitzeln und Grobfuttermitteln als Zulagen zu einer Grundration

Energy metabolism measurings of male castrates of a live weight between 90 and 180 kg after feeding rations with a wide variety in the content of various carbohydrates (crude fibre 36-185, water soluble carbohydrates 25-306, starch 272-683 g/kg DM) formed the experimental basis of the considerations. Energy retention depended significantly on the digestibility and metabolizability of the energy, on energy concentration and the crude fibre content of the rations. By means of multiple regression analyses the energetic effect of 1 g digested matter of the carbohydrate fraction was assessed as follows: 12.9 kJ for starch, 12.1 kJ for disaccharides, 11.5 kJ for the remaining water soluble carbohydrates and 10.4 kJ for bacterially fermentable carbohydrates (BFC). There was a difference between the energetic effective value of starch and BFC. This corresponds completely to the difference in the utilization of metabolizable energy between exclusively precaecal and postileal digestion. The following conclusions are drawn for the further development of the energetic feed evaluation for pigs in the framework of the GDR feed evaluation system: --There are to be differentiated fixed values for the retention of digestible carbohydrates for the fractions starch, water soluble carbohydrates (pectin) and bacterially fermentable carbohydrates. --The influence of the digestibility of the energy in the ration on the energetic retention effect of BFC is small. The integration of these variables into an estimation equation for the energetic feed value is therefore not necessary.

Retention of carbohydrates on silica and amine-bonded silica stationary phases: application of the hydration model

Retention of carbohydrates on silica and amine-bonded silica stationary phases: application of the hydration model