Iron deficiency anemia(IDA)is a major global health problem.Tegillarca granosa has been considered as an excellent source of iron given its high content of iron-binding protein,ferritin.The aim of the present study wa...Iron deficiency anemia(IDA)is a major global health problem.Tegillarca granosa has been considered as an excellent source of iron given its high content of iron-binding protein,ferritin.The aim of the present study was to determine the physicochemical properties,protein structures,and iron uptake of ferritin extracted from T.granosa,and to evaluate the potential impacts of chitosan glycosylation on these characteristics.Based on Box-Behnken design and response surface methodology,the optimal conditions for glycosylation included a ferritin/chitosan mass ratio of 4:1,a pH of 5.5,a reaction time of 10 min,and a reaction temperature of 50℃.Glycosylation caused decreased surface hydrophobicity and elevated water-holding capacity of ferritin due to the introduction of hydrophilic groups.Additionally,glycosylation improved antioxidant capacity of ferritin by 20.69%–189.66%,likely owing to the protons donated by saccharide moiety to terminate free radical chain reaction.The in vitro digestibility of ferritin was elevated by 22.56%–104.85%after glycosylation,which could be associated with lessβ-sheet content in secondary structure that made the glycosylated protein less resistant to enzymatic digestion.The results of the iron bioavailability in Caco-2 cells revealed that ferritin(78.85–231.77 ngmg^(−1))exhibited better iron bioavailability than FeSO4(51.48–114.37 ngmg^(−1))and the values were further elevated by glycosylation with chitosan(296.23–358.20 ngmg^(−1)),which may be related to the physicochemical properties of ferritin via glycosylation modification.These results provide a basis for the development of T.granosa derived ferritin and its glycosylated products,and can promote the utilization of aquatic resources.展开更多
Mature-green tomato fruit (Solanum lycopersicum cv. Zhenfen 202) were exposed to different UV-C irradiation at 2, 4, 8, and 16 kJ m-2 and then stored under the dark at 14°C and 95% relative humidity (RH) for ...Mature-green tomato fruit (Solanum lycopersicum cv. Zhenfen 202) were exposed to different UV-C irradiation at 2, 4, 8, and 16 kJ m-2 and then stored under the dark at 14°C and 95% relative humidity (RH) for 35 d. Of these four doses, UV-C irradiation at 4 and 8 kJ m-2 significantly increased total phenolic contents in present tomato fruit by 21.2 and 20.2%, respectively. Furthermore, UV-C irradiation at 4 or 8 kJ m-2 promoted the accumulation of total flavonoids and increased the antioxidant activity. 2 or 16 kJ m-2 UV-C irradiation also enhanced antioxidant activity, but to a lesser extent. Seven phenolic compounds, viz., gallic acid, (+)-catechin, chlorogenic acid, cafferic acid, syringic acid, p-coumaric acid, and quercetin in tomato fruit were identified and quantified by HPLC. Gallic acid was the major phenolic compound in tomato fruit and significantly correlated with antioxidant activity. 4 or 8 kJ m-2 UV-C irradiation significantly increased the contents of gallic acid, chlorogenic acid, syringic acid, p-coumaric acid, and quercetin. The optimum dose of UV-C irradiation in terms of increased phenolic compound content and enhanced Antioxidant activity was determined to be 4 or 8 kJ m-2.展开更多
The interactions between konjac glucomannan(KGM) and soy protein isolate (SPI) were studied with the method of molecular dynamics simulation. Part representative structures segments of KGM and SPI were used as mod...The interactions between konjac glucomannan(KGM) and soy protein isolate (SPI) were studied with the method of molecular dynamics simulation. Part representative structures segments of KGM and SPI were used as mode, and the force-field was FF03. The stability and sites of KGM/SPI interactions in water were researched at 363 K with the following results: the potential energy (EPOT) of the mixed gel dropped, while that of single KGM gel increased. The surface area (SA) of KGM in the mixed system was decreased to 401.41 from 1 267.54 Az, and that of SPI to 484.94 from 1 943.28 A2. The sum potential energy of KGM and soy protein in the mixed system was decreased to -13 402.41 from -5 768.56 kcal mol^-1. The variations of two parameters showed that the stability of compound gel KGM/SPI was improved, which was consistent with the previous studies. The sites of interactions in the mixed gel were the -OH groups on C(2) in KGM mannose and glucose, and the amide linkage group on Histidine, Asparagine and Leucine in SPI. The hydrogen bond was formed directly or indirectly by the bridge of waters.展开更多
The interactions between konjac glucomannan and carrageenan were studied with the method of molecular dynamics simulation. Part representative structure segments of KGM and two unit structures of κ-carrageenan (Fig...The interactions between konjac glucomannan and carrageenan were studied with the method of molecular dynamics simulation. Part representative structure segments of KGM and two unit structures of κ-carrageenan (Fig. 2) were used as mode, and the force-field was AMBER2. The stability and sites of konjac glucomannan/carrageenan interactions in water were researched at 373 K with the following results: the potential energy (EPOT) of the mixed gel was dropped, while those of single-konjac glucomannan gel and single carrageenan were increased. The surface area (SA) of KGM in the mixed system was decreased to 1002.2A^°^2, and that of carrageenan to 800.9 A^°^2. The variations of two parameters showed that the stability of compound gel konjac glucomannan/carrageenan was improved, which is consistent with the previous studies. The sites of interactions in the mixed gel were the -OH groups on C(2), C(4) and C(6), the acetyl group in KGM mannose, and the -OH group on C(6) in carrageenan. The hydrogen bond was formed directly or indirectly by the bridge of waters.展开更多
Sweet potato (Ipomoea batatas Lam.) leaf stalks were cut into 20 cm length, and stored at 20, 6, and 2℃. The respiration rate, ethylene production, ascorbic acid, free amino acid, total chlorophyll content, freshne...Sweet potato (Ipomoea batatas Lam.) leaf stalks were cut into 20 cm length, and stored at 20, 6, and 2℃. The respiration rate, ethylene production, ascorbic acid, free amino acid, total chlorophyll content, freshness, and shelf life were determined during storage to investigate the effect of storage temperatures on the quality and physiological responses in sweet potato leaf stalks. Wound responses were observed as high respiration rate and ethylene production immediately after cutting. Sweet potato leaf stalks were found to be sensitive to chilling injury manifested as browning and water-soaking on the surface at 2℃. In contrast, sweet potato leaf stalks were susceptible to senescence, exhibited by etiolating and yellowing, at 20℃. Loss in weight and chlorophyll was minimized under low temperatures. High temperatures also caused the accumulation of amino acids with a significant loss of ascorbic acid and chlorophyll. Sweet potato leaf stalks had a storage life of 16 days at 6℃, 8 days at 2℃, and 6 days at 20℃, respectively.展开更多
The method for preparing low molecular weight fucosylated chondroitin sulfate from sea cucumber lsostichopus badionotus using partial acid hydrolysis was reported, and its hydrolysis mechanism was also investigated. T...The method for preparing low molecular weight fucosylated chondroitin sulfate from sea cucumber lsostichopus badionotus using partial acid hydrolysis was reported, and its hydrolysis mechanism was also investigated. The sea cucumber chondroitin sulfate FCS was hydrolyzed under different conditions (80℃3 h and 6 h), then isolated and purified on a Bio-P-4 geltration to prepare low molecular weight fractions (LMWF-FCS). The chemical compositions of LMWF-FCS showed the branched fucose (Fuc) was cleaved during acid hydrolysis process, whereas the mole ratio of acetyl-galactosamine (GalNAc) and glucuronic acid (GlcA) in the backbone remained the same, which indicated the backbone was a typical chondroitin sulfate structure. The disaccharide composition analysis of LMWF-FCS suggested that the sulfation patterns of GalNAc in the backbone chain changed and the substitution value was reduced. Furthermore, the 1D NMR analysis illustrated the branched-Fuc was cleaved during acid hydrolysis, but their substitution patterns were not influenced, which was distinct from the previous reports that the substitutions of branched-Fuc in FCS were easy to change. Simultaneously, the sulfation pattern of GalNAc in backbone chain changed obviously in the acid hydrolysis process. The anticoagulant activity in vitro illuminated the anticoagulant activity of the degradation products over time in the acid hydrolysis are gradually declined, but still kept good. Therefore, the LMWF-FCS prepared could be developed as a new anticoagulant and antithrombotic drug like low molecular weight heparin.展开更多
In this paper, the hydrogen bonding network models of konjac glucomannan (KGM) are predicted in the approach of molecular dynamics (MD). These models have been proved by experiments whose results are consistent wi...In this paper, the hydrogen bonding network models of konjac glucomannan (KGM) are predicted in the approach of molecular dynamics (MD). These models have been proved by experiments whose results are consistent with those from simulation. The results show that the hydrogen bonding network structures of KGM are stable and the key linking points of hydrogen bonding network are at the O(6) and O(2) positions on KGM ring. Moreover, acety has significant influence on hydrogen bonding network and hydrogen bonding network structures are more stable after deacetylation.展开更多
The effects of different drying methods (hot-air drying, microwave drying and vacuum-freeze drying) on the antioxidant activity and antioxidants in sweet potato (lpomoea batatas L. Lain.) tubers were investigated ...The effects of different drying methods (hot-air drying, microwave drying and vacuum-freeze drying) on the antioxidant activity and antioxidants in sweet potato (lpomoea batatas L. Lain.) tubers were investigated to determine the potential drying process. Sweet potato tubers were cut into 5 mm thick slices, steamed at 100℃ for 10 rain, then dried in either hotair, microwave, or vacuum-freeze. The dried sweet potatoes in microwave possessed the highest antioxidant activity, while the lowest activity was observed in hot-air dried samples. The phenolic contents were positively correlated with scavenging activity and reducing power of DPPH^+. The microwave drying retains the highest antioxidant activity with the highest content of phenolic compounds in dried sweet potatoes. β-carotene and ascorbic acid showed minor contribution to the antioxidant activity in dried sweet potatoes.展开更多
Molecular dynamics (MD) method is adopted to simulate the conformation variations of konjac glucomannan (KGM) saline solution at different temperatures, and structurally analyze the trends and reasons of viscosity...Molecular dynamics (MD) method is adopted to simulate the conformation variations of konjac glucomannan (KGM) saline solution at different temperatures, and structurally analyze the trends and reasons of viscosity change in KGM saline solution with temperature. The experimental results have been analyzed to find out that the sum of formative hydrogen bonds decreases with the rise of temperature and the amount of intramolecular hydrogen bonds suddenly increases at 323 K. Besides, in terms of molecular orbital data obtained from simulation, we can know that hydrogen bonding energy also decreases with the rise of temperature. Therefore, we can predict the viscosity of KGM saline solution decreases gradually when rising the temperature.展开更多
Acidic polysaccharide, which has various biological activities, is one of the most important components of sea cucumber. In the present study, crude polysaccharide was extracted from four species of sea cucumber from ...Acidic polysaccharide, which has various biological activities, is one of the most important components of sea cucumber. In the present study, crude polysaccharide was extracted from four species of sea cucumber from three different geographical zones, Pearsonothuria graeffei(Pg) from Indo-Pacific, Holothuria vagabunda(Hv) from Norwegian Coast, Stichopus tremulu(St) from Western Indian Ocean, and Isostichopus badionotu(Ib) from Western Atlantic. The polysaccharide extract was separated and purified with a cellulose DEAE anion-exchange column to obtain corresponding sea cucumber fucans(SC-Fucs). The chemical property of these SC-Fucs, including molecular weight, monosaccharide composition and sulfate content, was determined. Their structure was compared simply with fourier infrared spectrum analyzer and identified with high temperature 1H nuclear magnetic resonance spectrum analyzer(NMR) and room temperature 13 C NMR. The results indicated that Fuc-Pg obtained from the torrid zone mainly contained 2,4-O-disulfated and non-sulfated fucose residue, whereas Fuc-Ib from the temperate zone contained non-, 2-O- and 2,4-O-disulfated fucose residue; Fuc-St from the frigid zone and Fuc-Hv from the torrid zone contained mainly non-sulfated fucose residue. The proton of SC-Fucs was better resolved via high temperature 1H NMR than via room temperature 1H NMR. The fingerprint of sea cucumber in different sea regions was established based on the index of anomer hydrogen signal in SC-Fucs. Further work will help to understand whether there exists a close relationship between the geographical area of sea cucumber and the sulfation pattern of SC-Fucs.展开更多
In order that the mechanism designed meets the requirements of kinematics with optimal dynamics behaviors, a quadratic optimization method is proposed based on the different characteristics of kinematic and dynamic op...In order that the mechanism designed meets the requirements of kinematics with optimal dynamics behaviors, a quadratic optimization method is proposed based on the different characteristics of kinematic and dynamic optimization. This method includes two steps of optimization, that is, kinematic and dynamic optimization. Meanwhile, it uses the results of the kinematic optimization as the constraint equations of dynamic optimization. This method is used in the parameters optimization of transplanting mechanism with elliptic planetary gears of high-speed rice seedling transplanter with remarkable significance. The parameters spectrum, which meets to the kinematic requirements, is obtained through visualized human-computer interactions in the kinematics optimization, and the optimal parameters are obtained based on improved genetic algorithm in dynamic optimization. In the dynamic optimization, the objective function is chosen as the optimal' dynamic behavior and the constraint equations are from the results of the kinematic optimization, This method is suitable for multi-objective optimization when both the kinematic and dynamic performances act as objective functions.展开更多
A species of mushroom, Termitomyces albuminosus, was cultured in liquid medium for production of chromium-enriched mycelium. The influence of chromium (Ⅲ ) on mycelial growth of T. albuminosus was investigated. An op...A species of mushroom, Termitomyces albuminosus, was cultured in liquid medium for production of chromium-enriched mycelium. The influence of chromium (Ⅲ ) on mycelial growth of T. albuminosus was investigated. An optimum medium composed of 5.6g/L yeast extract, 51.6g/L hydrolyzed rice, 2g/L KH2PO4, and 20mg/L chromium(Ⅲ ) with initial pH of 4.5 was obtained by using method of central composite design (CCD). After incubation of 84h, the maximal biomass of chromium-enriched mycelia reached 24.23g DMW(dried mycelial weight)/L with 272μg/g DMW chromium content in 500mL flasks containing 100mL medium with an inoculum of 8% on a shaker of 100r/min under an optimized cultivation condition at 28℃.展开更多
Carotenoids are a family of effective active oxygen scavengers, which can reduce the danger of occurrence of chronic diseases such as cardiovascular disease, cataract, cancer, and so on. The quantitative structure-act...Carotenoids are a family of effective active oxygen scavengers, which can reduce the danger of occurrence of chronic diseases such as cardiovascular disease, cataract, cancer, and so on. The quantitative structure-activity relationship (QSAR) equation between carotenoids and antioxidant activity was established by quantum chemistry AM1, molecular mechanism (MM+) and stepwise regression analysis methods, and the model was evaluated by leave-one-out approach. The results showed that the significant molecular descriptors related to the antioxidant activity of carotenoids were the energy difference (E_HL) between the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) and ionization energy (Eiso). The model showed a good predictive ability (Q^2 〉 0.5).展开更多
Plant height can be used for assessing plant vigor and predicting biomass and yield. Manual measurement of plant height is time-consuming and labor-intensive. We describe a method for measuring maize plant height usin...Plant height can be used for assessing plant vigor and predicting biomass and yield. Manual measurement of plant height is time-consuming and labor-intensive. We describe a method for measuring maize plant height using an RGB-D camera that captures a color image and depth information of plants under field conditions. The color image was first processed to locate its central area using the S component in HSV color space and the Density-Based Spatial Clustering of Applications with Noise algorithm. Testing showed that the central areas of plants could be accurately located. The point cloud data were then clustered and the plant was extracted based on the located central area. The point cloud data were further processed to generate skeletons, whose end points were detected and used to extract the highest points of the central leaves. Finally, the height differences between the ground and the highest points of the central leaves were calculated to determine plant heights. The coefficients of determination for plant heights manually measured and estimated by the proposed approach were all greater than 0.95. The method can effectively extract the plant from overlapping leaves and estimate its plant height. The proposed method may facilitate maize height measurement and monitoring under field conditions.展开更多
The gene expression pattems of antioxidative enzymes in cucumber (Cucumis sativus L.) fruits at four different maturity stages, immature (3-8 d after anthesis (DAA), mature (9-16 DAA), breaker (17-22 DAA), an...The gene expression pattems of antioxidative enzymes in cucumber (Cucumis sativus L.) fruits at four different maturity stages, immature (3-8 d after anthesis (DAA), mature (9-16 DAA), breaker (17-22 DAA), and yellow (35-40 DAA), were determined before and after cold storage at 2℃ for 9 d and after subsequent rewarming at 20℃ for 2 d. The electrolyte leakage and malondialdehyde content in cucumber fruits were increased after cold storage and subsequent rewarming. Increased expressions of peroxidase, ascorbate peroxidase (APX), and monodehydroascorbate reductase after cold storage played an important role in cucumber fruits to cope with chilling injury. The elevated cyt-superoxide dismutase, catalase, APX and dehydroascorbate reductase after subsequent rewarming in cucumber fruits facilitated the recovery from chilling stress. The highest expression levels of all the seven antioxidative enzyme genes in yellow fruits might be responsible for the enhanced chilling tolerance. Cucumber fruits at earlier developmental stages was more susceptible to chilling stress than those at later stages. The relative higher gene expressions of antioxidative enzymes genes at earlier developmental stages may be the responses to the sever oxidative stress caused by chilling injury.展开更多
The near infrared (NIR) spectroscopy technique has been applied in many fields because of its advantages of simple preparation, fast response, and non-destructiveness. We investigated the potential of NIR spectroscopy...The near infrared (NIR) spectroscopy technique has been applied in many fields because of its advantages of simple preparation, fast response, and non-destructiveness. We investigated the potential of NIR spectroscopy in diffuse reflectance mode for determining the soluble solid content (SSC) and acidity (pH) of intact loquats. Two cultivars of loquats (Dahongpao and Jiajiaozhong) harvested from two orchards (Tangxi and Chun'an, Zhejiang, China) were used for the measurement of NIR spectra between 800 and 2500 nm. A total of 400 loquats (100 samples of each cultivar from each orchard) were used in this study. Re- lationships between NIR spectra and SSC and acidity of loquats were evaluated using partial least square (PLS) method. Spectra preprocessing options included the first and second derivatives, multiple scatter correction (MSC), and the standard normal variate (SNV). Three separate spectral windows identified as full NIR (800~2500 nm), short NIR (800~1100 nm), and long NIR (1100~2500 nm) were studied in factorial combination with the preprocessing options. The models gave relatively good predic- tions of the SSC of loquats, with root mean square error of prediction (RMSEP) values of 1.21, 1.00, 0.965, and 1.16 °Brix for Tangxi-Dahongpao, Tangxi-Jiajiaozhong, Chun'an-Dahongpao, and Chun'an-Jiajiaozhong, respectively. The acidity prediction was not satisfactory, with the RMSEP of 0.382, 0.194, 0.388, and 0.361 for the above four loquats, respectively. The results indicate that NIR diffuse reflectance spectroscopy can be used to predict the SSC and acidity of loquat fruit.展开更多
Due to their toxicity,the increased distribution of microcystins(MCs) has become an important worldwide problem.MCs have been recognized as inhibitors of protein phosphatase 2A(PP2A) through their binding to the PP2A ...Due to their toxicity,the increased distribution of microcystins(MCs) has become an important worldwide problem.MCs have been recognized as inhibitors of protein phosphatase 2A(PP2A) through their binding to the PP2A catalytic subunit.However,the exact mechanism of MC toxicity has not been elucidated,especially concerning the cellular response and its autoregulation.To further dissect the role of PP2A in MC-induced toxicity,the present study was undertaken to determine the response of PP2A in human amniotic epithelial(FL) cells treated with microcystin-LR(MCLR),one of the MC congeners.The results show that a low-dose treatment of MCLR in FL cells for 6 h induced an increase in PP2A activity,and a high-dose treatment of MCLR for 24 h decreased the activity of PP2A,as expected.The increased mRNA and protein levels of the PP2A C subunit may explain the increased activity of PP2A.Furthermore,MCLR altered microtubule post-translational modifications through PP2A.These results further clarify the underlying mechanism how MCLR affects PP2A and may be helpful for elucidating the complex toxicity of MCLR.展开更多
Three cooking methods,namely boiling,steaming,and stir-frying for 5 to 10 min,were used to evaluate the effect on nutrient components,free amino acids,L-ascorbic acid,total phenolic contents,and antioxidant capacities...Three cooking methods,namely boiling,steaming,and stir-frying for 5 to 10 min,were used to evaluate the effect on nutrient components,free amino acids,L-ascorbic acid,total phenolic contents,and antioxidant capacities of bamboo shoots(Phyllostachys praecox).Results showed that boiling and stir-frying had a great effect on the nutrient components and they decreased the contents of protein,soluble sugar,and ash,and caused a great loss in the total free amino acids(decreased by 38.35% and 34.86%,respectively).Significant differences(P<0.05) in free amino acids were observed in the samples cooked by different methods.Stir-fried bamboo shoots had a high fat content which increased by 528.57% because of the addition of edible oil.After boiling,the L-ascorbic acid and total phenolic contents were significantly reduced,while steaming increased total phenolic content by 3.98% and stir-frying well-preserved L-ascorbic acid(78.87% of its previous content).Results of the antioxidative property study showed that stir-frying could increase antioxidant capacities of bamboo shoots.It is concluded that stir-frying is more suitable for bamboo shoots because it could obtain the maximum retention of antioxidant capacities.展开更多
We investigated the higher structure of konjac glucomannan (KGM) in the amorphous state and solution using a laser particle size analyzer and a water activity meter. The results show that the thermodynamic structures ...We investigated the higher structure of konjac glucomannan (KGM) in the amorphous state and solution using a laser particle size analyzer and a water activity meter. The results show that the thermodynamic structures of native KGM were primarily composed of the lamella structure units, which involve both granular crystalline and amorphous regions, and that the connection zones of such units contained both loose and tight aggregation regions. The value of surface tension (σ) of native KGM, resting with the density of its hydroxyl groups' self-association, was an important parameter to analyze the higher structures of native KGM in the thermodynamic swelling model of native KGM.展开更多
基金supported by the National Key R&D Program of China(No.2018YFD0901105).
文摘Iron deficiency anemia(IDA)is a major global health problem.Tegillarca granosa has been considered as an excellent source of iron given its high content of iron-binding protein,ferritin.The aim of the present study was to determine the physicochemical properties,protein structures,and iron uptake of ferritin extracted from T.granosa,and to evaluate the potential impacts of chitosan glycosylation on these characteristics.Based on Box-Behnken design and response surface methodology,the optimal conditions for glycosylation included a ferritin/chitosan mass ratio of 4:1,a pH of 5.5,a reaction time of 10 min,and a reaction temperature of 50℃.Glycosylation caused decreased surface hydrophobicity and elevated water-holding capacity of ferritin due to the introduction of hydrophilic groups.Additionally,glycosylation improved antioxidant capacity of ferritin by 20.69%–189.66%,likely owing to the protons donated by saccharide moiety to terminate free radical chain reaction.The in vitro digestibility of ferritin was elevated by 22.56%–104.85%after glycosylation,which could be associated with lessβ-sheet content in secondary structure that made the glycosylated protein less resistant to enzymatic digestion.The results of the iron bioavailability in Caco-2 cells revealed that ferritin(78.85–231.77 ngmg^(−1))exhibited better iron bioavailability than FeSO4(51.48–114.37 ngmg^(−1))and the values were further elevated by glycosylation with chitosan(296.23–358.20 ngmg^(−1)),which may be related to the physicochemical properties of ferritin via glycosylation modification.These results provide a basis for the development of T.granosa derived ferritin and its glycosylated products,and can promote the utilization of aquatic resources.
基金Supported by the National Natural Science Foundation of China (30972036)
文摘Mature-green tomato fruit (Solanum lycopersicum cv. Zhenfen 202) were exposed to different UV-C irradiation at 2, 4, 8, and 16 kJ m-2 and then stored under the dark at 14°C and 95% relative humidity (RH) for 35 d. Of these four doses, UV-C irradiation at 4 and 8 kJ m-2 significantly increased total phenolic contents in present tomato fruit by 21.2 and 20.2%, respectively. Furthermore, UV-C irradiation at 4 or 8 kJ m-2 promoted the accumulation of total flavonoids and increased the antioxidant activity. 2 or 16 kJ m-2 UV-C irradiation also enhanced antioxidant activity, but to a lesser extent. Seven phenolic compounds, viz., gallic acid, (+)-catechin, chlorogenic acid, cafferic acid, syringic acid, p-coumaric acid, and quercetin in tomato fruit were identified and quantified by HPLC. Gallic acid was the major phenolic compound in tomato fruit and significantly correlated with antioxidant activity. 4 or 8 kJ m-2 UV-C irradiation significantly increased the contents of gallic acid, chlorogenic acid, syringic acid, p-coumaric acid, and quercetin. The optimum dose of UV-C irradiation in terms of increased phenolic compound content and enhanced Antioxidant activity was determined to be 4 or 8 kJ m-2.
基金supported by the National Natural Science Foundation of China(30871749,30901004)
文摘The interactions between konjac glucomannan(KGM) and soy protein isolate (SPI) were studied with the method of molecular dynamics simulation. Part representative structures segments of KGM and SPI were used as mode, and the force-field was FF03. The stability and sites of KGM/SPI interactions in water were researched at 363 K with the following results: the potential energy (EPOT) of the mixed gel dropped, while that of single KGM gel increased. The surface area (SA) of KGM in the mixed system was decreased to 401.41 from 1 267.54 Az, and that of SPI to 484.94 from 1 943.28 A2. The sum potential energy of KGM and soy protein in the mixed system was decreased to -13 402.41 from -5 768.56 kcal mol^-1. The variations of two parameters showed that the stability of compound gel KGM/SPI was improved, which was consistent with the previous studies. The sites of interactions in the mixed gel were the -OH groups on C(2) in KGM mannose and glucose, and the amide linkage group on Histidine, Asparagine and Leucine in SPI. The hydrogen bond was formed directly or indirectly by the bridge of waters.
基金supported by the National Natural Science Foundation of China (30371009, 30471218)
文摘The interactions between konjac glucomannan and carrageenan were studied with the method of molecular dynamics simulation. Part representative structure segments of KGM and two unit structures of κ-carrageenan (Fig. 2) were used as mode, and the force-field was AMBER2. The stability and sites of konjac glucomannan/carrageenan interactions in water were researched at 373 K with the following results: the potential energy (EPOT) of the mixed gel was dropped, while those of single-konjac glucomannan gel and single carrageenan were increased. The surface area (SA) of KGM in the mixed system was decreased to 1002.2A^°^2, and that of carrageenan to 800.9 A^°^2. The variations of two parameters showed that the stability of compound gel konjac glucomannan/carrageenan was improved, which is consistent with the previous studies. The sites of interactions in the mixed gel were the -OH groups on C(2), C(4) and C(6), the acetyl group in KGM mannose, and the -OH group on C(6) in carrageenan. The hydrogen bond was formed directly or indirectly by the bridge of waters.
基金supported bythe National Natural Science Foundation of China.
文摘Sweet potato (Ipomoea batatas Lam.) leaf stalks were cut into 20 cm length, and stored at 20, 6, and 2℃. The respiration rate, ethylene production, ascorbic acid, free amino acid, total chlorophyll content, freshness, and shelf life were determined during storage to investigate the effect of storage temperatures on the quality and physiological responses in sweet potato leaf stalks. Wound responses were observed as high respiration rate and ethylene production immediately after cutting. Sweet potato leaf stalks were found to be sensitive to chilling injury manifested as browning and water-soaking on the surface at 2℃. In contrast, sweet potato leaf stalks were susceptible to senescence, exhibited by etiolating and yellowing, at 20℃. Loss in weight and chlorophyll was minimized under low temperatures. High temperatures also caused the accumulation of amino acids with a significant loss of ascorbic acid and chlorophyll. Sweet potato leaf stalks had a storage life of 16 days at 6℃, 8 days at 2℃, and 6 days at 20℃, respectively.
基金Sponsored by the National Natural Sciences Foundation of China(Nos.30871944 and 30971923)
文摘The method for preparing low molecular weight fucosylated chondroitin sulfate from sea cucumber lsostichopus badionotus using partial acid hydrolysis was reported, and its hydrolysis mechanism was also investigated. The sea cucumber chondroitin sulfate FCS was hydrolyzed under different conditions (80℃3 h and 6 h), then isolated and purified on a Bio-P-4 geltration to prepare low molecular weight fractions (LMWF-FCS). The chemical compositions of LMWF-FCS showed the branched fucose (Fuc) was cleaved during acid hydrolysis process, whereas the mole ratio of acetyl-galactosamine (GalNAc) and glucuronic acid (GlcA) in the backbone remained the same, which indicated the backbone was a typical chondroitin sulfate structure. The disaccharide composition analysis of LMWF-FCS suggested that the sulfation patterns of GalNAc in the backbone chain changed and the substitution value was reduced. Furthermore, the 1D NMR analysis illustrated the branched-Fuc was cleaved during acid hydrolysis, but their substitution patterns were not influenced, which was distinct from the previous reports that the substitutions of branched-Fuc in FCS were easy to change. Simultaneously, the sulfation pattern of GalNAc in backbone chain changed obviously in the acid hydrolysis process. The anticoagulant activity in vitro illuminated the anticoagulant activity of the degradation products over time in the acid hydrolysis are gradually declined, but still kept good. Therefore, the LMWF-FCS prepared could be developed as a new anticoagulant and antithrombotic drug like low molecular weight heparin.
基金supported by the National Natural Science Foundation of China(30371009, 30471218) Science Foundation of Fujian Department of Education (JA03059)
文摘In this paper, the hydrogen bonding network models of konjac glucomannan (KGM) are predicted in the approach of molecular dynamics (MD). These models have been proved by experiments whose results are consistent with those from simulation. The results show that the hydrogen bonding network structures of KGM are stable and the key linking points of hydrogen bonding network are at the O(6) and O(2) positions on KGM ring. Moreover, acety has significant influence on hydrogen bonding network and hydrogen bonding network structures are more stable after deacetylation.
基金supported by the Science and Technology Project of Zhejiang Province,China(2009C12031)
文摘The effects of different drying methods (hot-air drying, microwave drying and vacuum-freeze drying) on the antioxidant activity and antioxidants in sweet potato (lpomoea batatas L. Lain.) tubers were investigated to determine the potential drying process. Sweet potato tubers were cut into 5 mm thick slices, steamed at 100℃ for 10 rain, then dried in either hotair, microwave, or vacuum-freeze. The dried sweet potatoes in microwave possessed the highest antioxidant activity, while the lowest activity was observed in hot-air dried samples. The phenolic contents were positively correlated with scavenging activity and reducing power of DPPH^+. The microwave drying retains the highest antioxidant activity with the highest content of phenolic compounds in dried sweet potatoes. β-carotene and ascorbic acid showed minor contribution to the antioxidant activity in dried sweet potatoes.
基金Supported by the National Natural Science Foundation of China (30371009)Science Foundation of Fujian Department of Education (JA03059)Key Project of Science and Technology of Fujian Province (2003Y008)
文摘Molecular dynamics (MD) method is adopted to simulate the conformation variations of konjac glucomannan (KGM) saline solution at different temperatures, and structurally analyze the trends and reasons of viscosity change in KGM saline solution with temperature. The experimental results have been analyzed to find out that the sum of formative hydrogen bonds decreases with the rise of temperature and the amount of intramolecular hydrogen bonds suddenly increases at 323 K. Besides, in terms of molecular orbital data obtained from simulation, we can know that hydrogen bonding energy also decreases with the rise of temperature. Therefore, we can predict the viscosity of KGM saline solution decreases gradually when rising the temperature.
基金supported by the Public Service Project of Zhejiang Province (2011C22026)the Special Award Funding for Postdoc in China (16000-X91009 and 316000 -X91005)+1 种基金the National Natural Science Foundation of China (30972282),the National Natural Science Foundation of China (31301417)the Zhejiang Province Public Service Project (2011C11016)
文摘Acidic polysaccharide, which has various biological activities, is one of the most important components of sea cucumber. In the present study, crude polysaccharide was extracted from four species of sea cucumber from three different geographical zones, Pearsonothuria graeffei(Pg) from Indo-Pacific, Holothuria vagabunda(Hv) from Norwegian Coast, Stichopus tremulu(St) from Western Indian Ocean, and Isostichopus badionotu(Ib) from Western Atlantic. The polysaccharide extract was separated and purified with a cellulose DEAE anion-exchange column to obtain corresponding sea cucumber fucans(SC-Fucs). The chemical property of these SC-Fucs, including molecular weight, monosaccharide composition and sulfate content, was determined. Their structure was compared simply with fourier infrared spectrum analyzer and identified with high temperature 1H nuclear magnetic resonance spectrum analyzer(NMR) and room temperature 13 C NMR. The results indicated that Fuc-Pg obtained from the torrid zone mainly contained 2,4-O-disulfated and non-sulfated fucose residue, whereas Fuc-Ib from the temperate zone contained non-, 2-O- and 2,4-O-disulfated fucose residue; Fuc-St from the frigid zone and Fuc-Hv from the torrid zone contained mainly non-sulfated fucose residue. The proton of SC-Fucs was better resolved via high temperature 1H NMR than via room temperature 1H NMR. The fingerprint of sea cucumber in different sea regions was established based on the index of anomer hydrogen signal in SC-Fucs. Further work will help to understand whether there exists a close relationship between the geographical area of sea cucumber and the sulfation pattern of SC-Fucs.
基金This project is supported by National Natural Science Foundation of China (No.50275137)Basic Research Major Project of China Science and Technology Ministry(No.2004CCA05700)Provincial Natural Science Foundation of Zhejiang, China (No. Z105706).
文摘In order that the mechanism designed meets the requirements of kinematics with optimal dynamics behaviors, a quadratic optimization method is proposed based on the different characteristics of kinematic and dynamic optimization. This method includes two steps of optimization, that is, kinematic and dynamic optimization. Meanwhile, it uses the results of the kinematic optimization as the constraint equations of dynamic optimization. This method is used in the parameters optimization of transplanting mechanism with elliptic planetary gears of high-speed rice seedling transplanter with remarkable significance. The parameters spectrum, which meets to the kinematic requirements, is obtained through visualized human-computer interactions in the kinematics optimization, and the optimal parameters are obtained based on improved genetic algorithm in dynamic optimization. In the dynamic optimization, the objective function is chosen as the optimal' dynamic behavior and the constraint equations are from the results of the kinematic optimization, This method is suitable for multi-objective optimization when both the kinematic and dynamic performances act as objective functions.
文摘A species of mushroom, Termitomyces albuminosus, was cultured in liquid medium for production of chromium-enriched mycelium. The influence of chromium (Ⅲ ) on mycelial growth of T. albuminosus was investigated. An optimum medium composed of 5.6g/L yeast extract, 51.6g/L hydrolyzed rice, 2g/L KH2PO4, and 20mg/L chromium(Ⅲ ) with initial pH of 4.5 was obtained by using method of central composite design (CCD). After incubation of 84h, the maximal biomass of chromium-enriched mycelia reached 24.23g DMW(dried mycelial weight)/L with 272μg/g DMW chromium content in 500mL flasks containing 100mL medium with an inoculum of 8% on a shaker of 100r/min under an optimized cultivation condition at 28℃.
基金Supported by the Chinese National Key Technologies R & D Program of 11th Five-year Plan (2006BAD27B06)Education Foundation of Innovative Engineering Key Project of Education Department (707034)
文摘Carotenoids are a family of effective active oxygen scavengers, which can reduce the danger of occurrence of chronic diseases such as cardiovascular disease, cataract, cancer, and so on. The quantitative structure-activity relationship (QSAR) equation between carotenoids and antioxidant activity was established by quantum chemistry AM1, molecular mechanism (MM+) and stepwise regression analysis methods, and the model was evaluated by leave-one-out approach. The results showed that the significant molecular descriptors related to the antioxidant activity of carotenoids were the energy difference (E_HL) between the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) and ionization energy (Eiso). The model showed a good predictive ability (Q^2 〉 0.5).
基金supported by the Key Project of Intergovernmental Collaboration for Science and Technology Innovation under the National Key R&D Plan (2019YFE0103800)CAU Special Fund to Build World-class University (in disciplines) and Guide Distinctive Development (2021AC006)。
文摘Plant height can be used for assessing plant vigor and predicting biomass and yield. Manual measurement of plant height is time-consuming and labor-intensive. We describe a method for measuring maize plant height using an RGB-D camera that captures a color image and depth information of plants under field conditions. The color image was first processed to locate its central area using the S component in HSV color space and the Density-Based Spatial Clustering of Applications with Noise algorithm. Testing showed that the central areas of plants could be accurately located. The point cloud data were then clustered and the plant was extracted based on the located central area. The point cloud data were further processed to generate skeletons, whose end points were detected and used to extract the highest points of the central leaves. Finally, the height differences between the ground and the highest points of the central leaves were calculated to determine plant heights. The coefficients of determination for plant heights manually measured and estimated by the proposed approach were all greater than 0.95. The method can effectively extract the plant from overlapping leaves and estimate its plant height. The proposed method may facilitate maize height measurement and monitoring under field conditions.
基金supported by the National Natural Science Foundation of China(31172006)the PhD Programs Foundation of Ministry of Education of China(20100101110139)
文摘The gene expression pattems of antioxidative enzymes in cucumber (Cucumis sativus L.) fruits at four different maturity stages, immature (3-8 d after anthesis (DAA), mature (9-16 DAA), breaker (17-22 DAA), and yellow (35-40 DAA), were determined before and after cold storage at 2℃ for 9 d and after subsequent rewarming at 20℃ for 2 d. The electrolyte leakage and malondialdehyde content in cucumber fruits were increased after cold storage and subsequent rewarming. Increased expressions of peroxidase, ascorbate peroxidase (APX), and monodehydroascorbate reductase after cold storage played an important role in cucumber fruits to cope with chilling injury. The elevated cyt-superoxide dismutase, catalase, APX and dehydroascorbate reductase after subsequent rewarming in cucumber fruits facilitated the recovery from chilling stress. The highest expression levels of all the seven antioxidative enzyme genes in yellow fruits might be responsible for the enhanced chilling tolerance. Cucumber fruits at earlier developmental stages was more susceptible to chilling stress than those at later stages. The relative higher gene expressions of antioxidative enzymes genes at earlier developmental stages may be the responses to the sever oxidative stress caused by chilling injury.
基金Project supported by the National Natural Science Foundation of China(No.30825027)the National Key Technology R&D Program of China(No.2006BAD11A12)
文摘The near infrared (NIR) spectroscopy technique has been applied in many fields because of its advantages of simple preparation, fast response, and non-destructiveness. We investigated the potential of NIR spectroscopy in diffuse reflectance mode for determining the soluble solid content (SSC) and acidity (pH) of intact loquats. Two cultivars of loquats (Dahongpao and Jiajiaozhong) harvested from two orchards (Tangxi and Chun'an, Zhejiang, China) were used for the measurement of NIR spectra between 800 and 2500 nm. A total of 400 loquats (100 samples of each cultivar from each orchard) were used in this study. Re- lationships between NIR spectra and SSC and acidity of loquats were evaluated using partial least square (PLS) method. Spectra preprocessing options included the first and second derivatives, multiple scatter correction (MSC), and the standard normal variate (SNV). Three separate spectral windows identified as full NIR (800~2500 nm), short NIR (800~1100 nm), and long NIR (1100~2500 nm) were studied in factorial combination with the preprocessing options. The models gave relatively good predic- tions of the SSC of loquats, with root mean square error of prediction (RMSEP) values of 1.21, 1.00, 0.965, and 1.16 °Brix for Tangxi-Dahongpao, Tangxi-Jiajiaozhong, Chun'an-Dahongpao, and Chun'an-Jiajiaozhong, respectively. The acidity prediction was not satisfactory, with the RMSEP of 0.382, 0.194, 0.388, and 0.361 for the above four loquats, respectively. The results indicate that NIR diffuse reflectance spectroscopy can be used to predict the SSC and acidity of loquat fruit.
基金Project supported by the National Natural Science Foundation of China (Nos. 30771827 and 20777067)the Key Special Program on the S & T of China for the Pollution Control and Treatment of Water Bodies (No. 2008ZX07421-001)
文摘Due to their toxicity,the increased distribution of microcystins(MCs) has become an important worldwide problem.MCs have been recognized as inhibitors of protein phosphatase 2A(PP2A) through their binding to the PP2A catalytic subunit.However,the exact mechanism of MC toxicity has not been elucidated,especially concerning the cellular response and its autoregulation.To further dissect the role of PP2A in MC-induced toxicity,the present study was undertaken to determine the response of PP2A in human amniotic epithelial(FL) cells treated with microcystin-LR(MCLR),one of the MC congeners.The results show that a low-dose treatment of MCLR in FL cells for 6 h induced an increase in PP2A activity,and a high-dose treatment of MCLR for 24 h decreased the activity of PP2A,as expected.The increased mRNA and protein levels of the PP2A C subunit may explain the increased activity of PP2A.Furthermore,MCLR altered microtubule post-translational modifications through PP2A.These results further clarify the underlying mechanism how MCLR affects PP2A and may be helpful for elucidating the complex toxicity of MCLR.
基金Project supported by the Fundamental Research Funds for the Central Universities (No. KYJD09033)the National Key Technology R & DProgram of China (No. 2008BAD91B04)the Science and Technology Department of Zhejiang Province (Nos. 2010C12012 and 2008C02015),China
文摘Three cooking methods,namely boiling,steaming,and stir-frying for 5 to 10 min,were used to evaluate the effect on nutrient components,free amino acids,L-ascorbic acid,total phenolic contents,and antioxidant capacities of bamboo shoots(Phyllostachys praecox).Results showed that boiling and stir-frying had a great effect on the nutrient components and they decreased the contents of protein,soluble sugar,and ash,and caused a great loss in the total free amino acids(decreased by 38.35% and 34.86%,respectively).Significant differences(P<0.05) in free amino acids were observed in the samples cooked by different methods.Stir-fried bamboo shoots had a high fat content which increased by 528.57% because of the addition of edible oil.After boiling,the L-ascorbic acid and total phenolic contents were significantly reduced,while steaming increased total phenolic content by 3.98% and stir-frying well-preserved L-ascorbic acid(78.87% of its previous content).Results of the antioxidative property study showed that stir-frying could increase antioxidant capacities of bamboo shoots.It is concluded that stir-frying is more suitable for bamboo shoots because it could obtain the maximum retention of antioxidant capacities.
文摘We investigated the higher structure of konjac glucomannan (KGM) in the amorphous state and solution using a laser particle size analyzer and a water activity meter. The results show that the thermodynamic structures of native KGM were primarily composed of the lamella structure units, which involve both granular crystalline and amorphous regions, and that the connection zones of such units contained both loose and tight aggregation regions. The value of surface tension (σ) of native KGM, resting with the density of its hydroxyl groups' self-association, was an important parameter to analyze the higher structures of native KGM in the thermodynamic swelling model of native KGM.