Optimization of Solid-State Fermentation with Lactobacillus brevis and Aspergillus oryzae for Trypsin Inhibitor Degradation in Soybean Meal

The aim of the present study was to optimize trypsin inhibitor degradation in soybean meal by solid-state fermentation(SSF) with Lactobacillus brevis and Aspergillus oryzae,and to determine the effect of SSF on phytic acid,crude protein,crude fat,and amino acid profile.Response surface methodology(RSM) with Box-Behnken design was used to optimize SSF.The optimal conditions derived from RSM for L.brevis fermentation were:pH=5.1;inoculum size=10%;duration=72 h;substrate to water ratio=1.5.The minimum content of trypsin inhibitors was 6.4 mg g-1 dry matter.The optimal conditions derived from RSM for A.oryzae fermentation were:substrate to water ratio= 0.81;inoculum size=4%;duration=120 h.The minimum content of trypsin inhibitors was 1.6 mg g-1 dry matter.Both L.brevis and A.oryzae decreased trypsin inhibitors dramatically(57.1 and 89.2% respectively).L.brevis fermentation did not affect phytic acid(0.4%) and crude fat(5.2%) considerably,whereas A.oryzae fermentation degraded phytic acid(34.8%) and crude fat(22.0%) contents to a certain extent.Crude protein content was increased after both fermentation(6.4 and 12.9% for L.brevis and A.oryzae respectively).Urease activity was reduced greatly(83.3 and 58.3% for L.brevis and A.oryzae respectively).In conclusion,SSF with A.oryzae and L.brevis reduced trypsin inhibitor content and modified major macronutrients in soybean meal.     

Inhibitory Effects of Kojic Acid on Phenoloxidase of Diamondback Moth Plutella xylostella

The effects of kojic acid on phenoloxidase (PO) of Plutella xylostella were investigated, when it had been partially purified by 40% saturated [(NH4)2SO4] and Sephadex G-100 gel filtration. Kojic acid showed inhibitory effects on both monophenolase and o-diphenolase activity of the PO. The inhibitor concentrations leading to 50% (IC50) activity lost were estimated to be 0.07 mmol L^-1 for monophenolase and 1 mmol L^-1 for diphenolase, respectively. Kojic acid can also prolong the lag time of PO for oxidation of L-tyrosine. The inhibition kinetics were analyzed by Lineweaver-Burk plots and kojic acid was found to be a reversible competitive inhibitor with the ki of 0.47 mmol L^-1. The ability of kojic acid to inhibit the enzyme activity may be associated with its ability to chlate copper at the active site. In addition, the iron ion was found to shorten the lag time obviously, but have no important effect on the monophenolase activity.     

Study on Variation of Endogenous Hormonesat the Germinating Stage of Tea Spring Shoot

An HPLC method was used to analyze the contents and variation of IAA, GA3, ABA and ZT at five stages around the tea shoot germinating in spring. The contents of GA3 and ABA had a top value during the winter and decreased with the growth of tea shoots, while the contents of IAA and ZT had a low value during the winter and increased quickly at the beginning of shoot growth, but soon afterwards increased slowly or decreesed a little. The ratio of hormones was closely related to the growth of tea plant. The study indicated that the ratlos of GA3 to ABA and IAA to ABA were at low values during the winter and went up with the shoot germinating. When the activity of roots was weak, the ratio of ZT to IAA had a top value, but went down gradually with lmmriant activity of roots. The ratio d GA3 to ZT had a certain relativity with the shoot germinating, which was at a top value during the winter but went down suddenly at the begin-ning of shoot gerrminating.     

Antifungal Flavonoids from Ficus sarmentosa var. henryi （King） Corner

The methanol extract of Ficus sarmentosa var. henryi （King） Corner was found to detect potent inhibitory activities against 6 crop pathogenic fungi, Fusarium graminearum, Pumpkin fusarium Wilt, Curvularia lunata （Wakker） Boed, Septoria zeicola Stout, Botrytis cinerea, and Rhizoctonia solani. Four flavonoids were isolated from the extract of F. sarmentosa var. henryi by activity-guided fractionation and they were identified as eriodictyol （1）, homoeriodictyol （2）, dihydroquercetin （3）, and luteolin （4） by spectroscopic means and displayed excellent inhibitory activity against F. graminearum and S. zeicola. Among them, luteolin （4） showed the strongest inhibitory activity with IC50 values of 56.38 and 81.48 mg L^-1, to the fungi, respectively. The in vitro inhibitory activity of F. sarmentosa var. henryi （King） Corner was reported for the first time and the inhibitory action mechanism of luteolin （4） was worthy of further research.     

Changes of oxidative metabolism in the roots of wheat(Triticum aestivum L.) seedlings in response to elevated ammonium concentrations

To elucidate the response of oxidative metabolism, triggered by elevated ammonium(NH_4~+) concentrations, on root growth of wheat seedlings, Yumai 49(NH_4~+-tolerant) and Lumai 15(NH_4~+-sensitive) cultivars were supplied with either 5.0 mmol L~(–1) NH_4~+-N(EAC) or 5.0 mmol L–1 NO_3–-N(CON) under hydroponic conditions. Root growth in both cultivars was significantly reduced under EAC, and the negative effect was greater in Lumai 15. EAC enhanced the activities of monodehydroascorbate reductase and dehydroascorbate reductase in the roots of both cultivars, while it decreased ascorbic acid(ASA) content and GDP-mannose pyrophosphorylase(GMPase) activity at the 12 th day after treatment in Lumai 15 by 62.0 and 71.4%; and in Yumai 49 by 38.8 and 62.2%, respectively, indicating that the regeneration of ASA was increased, but the biosynthesis of ASA was reduced under EAC treatment. Moreover, EAC increased DHA/ASA, reactive oxygen species(ROS), and malondialdehyde contents, as well as antioxidant enzyme activities in the roots of both cultivars. Relatively greater increases in ROS and soluble sugar, and lower antioxidant enzyme activities in Lumai 15 indicate severe disruption of oxidative metabolism when compared to Yumai 49. Results reveal that the reduction of ASA biosynthesis via decreased GMPase activity under the EAC condition probably acts as a trigger for accumulated ROS and imbalanced redox status, resulting in root growth inhibition during wheat seedling growth stage. Yumai 49, being an NH_4~+-tolerant cultivar, had the stronger capacity to protect itself from oxidative stress, which allowed it to retain a lower DHA to ASA ratio by maintaining a better redox homeostasis than could be maintained in the NH_4~+-sensitive cultivar Lumai 15.     

Influences of Seed Source,Pre-chilling,Light and Temperature on the Germination of South African Pelargonium sidoides

Pelargonium sidoides DC is used in herbal medicine for the treatment of various infections. The roots are being indiscriminately harvested for local and export trade and the collection rate is becoming unsustainable. Seed germination dynamics of this species was studied with the aim to reveal factors that influence its survival in the wild in order to adopt the appropriate germination conditions for use in ex-situ propagation and conservation program. Germination was affected by age of seeds, temperature and pre-chilling conditions. Temperature higher than 25 oC reduced germination by 60%. When seeds of P. sidoides were subjected to pre-chilling treatment for seven days, there was a significant drop in final germination by 29% compared to the other treatments. Although, final germination was not affected by different light treatments, continuous light significantly promoted germination velocity Seeds harvested from the plants grown in the green house performed better in germination than those collected from the field. The ecological implications of these observations on the propagation and conservation ofP. sidoides are discussed.     

Genetic transformation ofpopulusxeuramericana cv. guariento with chitinase gene

In this paper, populus xeuramericana cv. Guariento was transformed with bean chitinase by Agrobacterium tumefaciens-mediated leaf disc method. Firstly, the leaf explants were pre-cultured at 25℃ for 2d. Secondly, they were infected in Agrobacterium tumefaciens suspension （OD600=0.5） for 20 rain, then were co-cultured for 3d in the dark. Thirdly, the explants were transferred to the selection culture medium （containing Kanamycin 40 mg.L^-1 and Cefotaxime Sodium 800 mg-L1） and incubated at 25℃ until resistance buds formed. Chitinase activity was determined for the positive plants by PCR and PCR-Southern blot hybridization analysis. And, chitinase activity of positive plants was significantly higher than that of control plant, and the highest ratio of activity of NO.4 to that of control was 3.41. It showed that bean chitinase gene had been expressed in the plant genome.     

Effect of continuous negative pressure water supply on the growth,development and physiological mechanism of Capsicum annuum L.

Effects of continuous negative pressure water supply on water consumption, growth and development, as well as physiological mechanism and quality of Capsicum annuum L. were investigated in this paper. Meanwhile, the optimal negative pressure water supply conditions for growth of C. annuum L. were screened out to achieve the goals of water conservation, high yield and high quality, thus providing theoretical foundation for its field production. The pot experiment within the greenhouse was utilized; the continuous negative pressure water supply was adopted; the four treatments, artificial watering(CK), –5 k Pa(T1), –10 k Pa(T2), and –15 k Pa(T3) were set; and the daily water consumption, yield, as well as the biomass, nitrate reductase, root activity, vitamin C, capsaicin, and nutrient uptakes of nitrogen(N), phosphorus(P) and potassium(K) during various stages of its growth were determined. Compared with CK, when the water supply pressure was controlled at –5 to –15 k Pa in the experiment, the total water consumption of C. annuum L. reduced by 53.42 to 67.75%, the total water consumption intensity reduced by 54.29 to 67.14%, and the water use efficiency increased by 12.66 to 124.67%. The N accumulation in a single strain of C. annuum L. from the color turning stage to the red ripe stage increased by 15.99 to 100.55%, respectively, compared with that of CK; the P accumulation increased by 20.47 to 154.00% relative to that of CK, and the K accumulation increased by 64.92 to 144.9% compared with that of CK. Compared with CK, C. annuum L. yield was remarkably improved by 13.79% at T1, and contents of vitamin C, capsaicin as well as carotenoids at all growth stages were enhanced by 13.42–147.01%, 11.54–71.01%, and 41.1–568.06%, respectively. Nitrate reductase activity, root activity and chlorophyll(a+b) were markedly increased by 335.78–500%, 79.6–140.68% and 114.95–676.19%, respectively, from immature stage to full ripe stage. Adopting the continuous negative pressure water supply for C. annuum L. has a significant water-saving effect, and the water supply pressure being stable at –5 k Pa contributes to its growth and development, improves yield, enhances root activity, promotes nutrient uptake, and improves its quality, thus achieving the effects of water conservation, high yield, high quality and high efficiency.     

Drying Technology of Angiotensin Converting Enzyme Inhibitory Peptide Derived from Bovine Casein

Drying technology of angiotensin converting enzyme （ACE） inhibitory peptides derived from bovine casein was investigated. No significance was observed on ACE inhibitory activity of products prepared by spay drying and freeze drying （P〉0.05）. Spay drying was the best drying process for practical industry production. The inlet temperature ranged from 140℃ to 160℃ and the exit temperature ranged from 70 ℃ to 90 ℃ during the spay drying process. Under the optimal conditions, scale-up of angiotensin converted enzyme inhibitory peptide from 1 L to 10 L and the experiment was successively conducted. Peptide yield was 29% and half inhibitory concentration （IC50） was 0.53 g. L^-1.     

Changes of Nitrate Reductase Activity in Cucumber Seedlings in Response to Nitrate Stress

In China, nitrogen fertilizer application rates in intensive agricultural systems have increased dramatically in recent years, especially in protected vegetable production systems. This excessive use of nitrogen fertilizer has resulted in soil secondary salinization, which has become a significant environmental stress for crops such as cucumber, in the protected farmland of China. So it is necessary to illuminate how crops respond to nitrate stress. The objective of this work was to examine the effects of increased nitrate concentration [14 （CK） and 140 mmol L^-1 （T）] on NO3- concentration, and in vitro and in vivo nitrate reductase activities in the roots and leaves of cucumber （Cucumis sativus L. cv. Xintaimici） seedlings with hydroponic culture. The results showed that the NO3- concentration in the roots and leaves of T seedlings significantly increased over treatment course, and at 12 d increased by 1.08 and 1.72 times with respect to CK seedlings, respectively; in vitro nitrate reductase activity of T was increased dramatically to 1.74 times of CK in the roots at 2 d and 1.56 times of CK in the leaves at 6 d, and then decreased. At 12 d, in vitro activity was still 24.3% higher in the roots and only 9.9% lower in the leaves than CK. Compared with in vitro nitrate reductase activity, in vivo activity responded differently to the increase of treatment time. At the beginning, in vivo nitrate reductase activity in the roots and leaves of T had no significant difference from CK, whereas with the increase of treatment duration, the activity decreased. At 12 d, in vivo activity in the roots and leaves of T lowered by 20.1 and 52.8% with respect to CK, respectively. This evidence suggests that posttranslational activation of nitrate reductase in cucumber seedlings may be seriously inhibited by nitrate stress.     

The effects of the unsaturated degree of long-chain fatty acids on the rumen microbial protein content and the activities of transaminases and dehydrogenase in vitro

This study investigated the effects of the degree of unsaturation(unsaturity) of long-chain fatty acids on microbial protein content and the activities of transaminases and dehydrogenase in vitro using goat rumen fluid as the cultural medium.Six types of fatty acids,stearic acid(C18:0,group A,control group),oleic acid(C18:1,n-9,group B),linoleic acid(C18:2,n-6,group C),α-linolenic acid(C18:3,n-3,group D),arachidonic acid(C20:4,n-6,group E),and eicosapentaenoic acid(C20:5,n-3,group F),were tested,and the inclusion ratio of each fatty acid was 3%(w/w) in total of culture substrate.Samples were taken at 0,3,6,9,12,18 and 24 h,respectively,during culture for analyses.Compared with stearic acid,linoleic acid,a-linolenic acid,and arachidonic acid increased the bacterial protein content,while oleic acid and eicosapentaenoic acid had no significant effects;the protozoal protein content was reduced for all the unsaturated fatty acids,and the magnitude of the reduction appeared to be associated with the degree of unsaturity of fatty acids.The total microbial protein content was dominantly accounted by the protozoal protein content(about 4-9 folds of the bacterial protein),and only increased by linoleic acid,but reduced by oleic acid,arachidonic acid and eicosapentaenoic acid.There were no significant effects in the activities of both glutamic oxaloacetic transaminase(GOT) and glutamic-pyruvic transaminase(GPT) for all the other fatty acids,except for arachidonic acid which enhanced GOT activity and oleic acid which enhanced GPT activity.The total dehydrogenase activity was positively correlated with the degree of unsaturation of fatty acids.In conclusion,the inclusion of 3%of long-chain unsaturated fatty acids increased bacterial protein content,whereas reduced protozoal protein content and enhanced dehydrogenase activity.The fatty acids with more than three double bonds had detrimental effects on the microbial protein content.This work demonstrates for the first time the effect rule of the unsaturation degree of long-chain fatty acids on the rumen microbial protein in vitro.     

Expression of HSP72 in Mouse Preimplantation Embryos with Heat Shock

The objective of the paper was to detect HSP72 expression and HSP72 gene sequence in heat shocked mouse preimplantation embryos and the effects of different thermo conditions on hatching rates of embryos. The mouse blastocysts cultured in vitro were heat treated at 40℃ and 38℃ for 1 h, 2 h and 3 h and then recovered at 370C for 3 h, 2 h and 1 h, respectively, to detect their HSP72 gene expression by using RT-PCR after the total R.NA extraction. The hatching rate of the blastocysts for different treated groups was recorded and the expression of liSP72 in the blastocysts was determined by Western blot. The results showed that all the groups of blastocysts, including the control, had the expression of HSP72 gene. The expression of HSP72 protein had the highest level in the embryos stressed at 38℃ for 2 h, and it was significantly higher than that in the control group. The expression of HSP72 in the groups of blastocysts treated at 40℃ was not significantly different from that in the control group. The embryos with induction of mild heat shock at 38℃ for 2 h, then subjected to heat shock at 40℃ for 2 h, had a significant higher （P〈0.05） hatching rate of 54.74% compared to 47.85% in the embryos treated directly at 40℃ for 2 h. The above results indicated that the mouse blastocysts were sensitive to heat shock and a mild heat shock induced HSP72 gene expression. Induction of HSP72 expression with mild heat shock helped embryos to tolerate more severe heat shocks.     

Expression and characterization of a codon-optimized butyrylcholinesterase for analysis of organophosphate insecticide residues

Organophosphate insecticide residues on vegetable, fruit, tea and even grains are primary cause of food poisoning. Organophosphate compounds can cause irreversible inhibition of the activity of acetylcholinesterase and butyrylcholinesterase(BChE, EC 3.1.1.8), which are both candidates for rapid detection of organophosphate pesticides. To develop an easy-tohandle method for detecting organophosphate pesticides using BChE, BChE from human was optimized according to the codon usage bias of Pichia pastoris and successfully expressed in P. pastoris GS115. The codon-optimized cDNA shared 37.3% of the codon identity with the native one. However, the amino acid sequence was identical to that of the native human butyrylcholinesterase gene(h BCh E) as published. The ratio of guanine and cytosine in four kinds of bases((G+C) ratio) was simultaneously increased from 40 to 47%. The recombinant hBChE expression reached a total protein concentration of 292 mg m L~(–1) with an activity of 14.7 U m L~(–1), which was purified 3.2×10~3-fold via nickel affinity chromatography with a yield of 68% and a specific activity of 8.1 U mg~(–1). Recombinant hBChE was optimally active at pH 7.4 and 50°C and exhibited high activity at a wide pH range(60% activity at pH 4.0 to 8.0). Moreover, it had a good adaptability to high temperature(60% activity at both 50 and 60°C up to 60 min) and good stability at 70°C. The enzyme can be activated by Li~+, Co~+, Zn~(2+) and ethylene diamine tetraacetic acid(EDTA), but inhibited by Mg~(2+), Mn~(2+), Fe~(2+), Ag~+ and Ca~(2+). Na~+ had little effect on its activity. The values of h BChE of the Michaelis constant(K_m) and maximum reaction velocity(V_m) were 89.4 mmol L~(–1) and 1 721 mmol min~(–1) mg~(–1), respectively. The bim olecular rate constants(K_i) of the hBChE to four pesticides were similar with that of electric eel AChE(EeAChE) and higher than that of horse BChE(HoBChE). All values of the half maximal inhibitory concentration of a substance(IC_(50)) for hBChE were lower than those for HoBChE, but most IC_(50) for hBChE were lower than those for EeAChE except dichlorvos. The applicability of the hBChE was further verified by successful detection of organophosphate insecticide residues in six kinds of vegetable samples. Thus, hBChE heterologously over-expressed by P. pastoris would provide a sufficient material for development of a rapid detection method of organophosphate on spot and produce the organophosphate detection kit.     

Effect of Inoculation Rhizobium and Response of Soybean-Rhizobium System to Insoluble Phosphate

In order to produce efficiently symbiotic system in acid soils which could be used for the recovery of insoluble phosphate soil and improvement of the fertility,etc.,host range of Rhizobium was isolated from the root nodules of wild and cultivated soybean varieties growing in south China,evaluated the effects of Rhizobium on enhance nitrogen fixing activities,phosphorus(P),nitrogen (N)uptakes,growth and yield of soybean under pot and field conditions.The results showed that combined Rhizobium inoculation was more effective than individual Rhizobium inoculation. The combined Rhizobium of CW54 strains had the highest effect, nodule number, nodule weight and nodule nitrogenase activity were markedly stimulated as compared to those of the control U110, respectively. The nitrogen contents in the plants treated with CW54 strains were significantly increased by 43.2% as compared to those of the control U110 in Al-P soil, but statistical significance was not observed in Fe-P soil. By contrast, inoculation with CW54 significantly enhanced phosphorus uptake of plant in Fe-P soil than that in Al-P soil. The effects of inoculation of CW54 strains in a field condition were similar to those of in a pot condition. The total biomass and yield in the plants treated with CW54 strains were significantly increased by 86.4% and 51.4% as compared to those of the control at the time of soybean podding in a field condition, respectively.These results suggested that inoculation Rhizobium was beneficial for soybean nutrient uptake,growth and yield under insoluble phosphate soil conditions.     

Technological Study on Instant Date Powder in Natural Ziziphus jujuba through Vacuum Freeze-drying

[Objective] The aim was to get optimized conditions for date powder with good color and taste.[Method] The pectinase enzymolysis and vacuum freeze-drying technology were used in the extract process of date powder.[Result] The production boasts of superior quality were with rich fragrance and uniform particle under certain process conditions.The optimized conditions for pectinase enzymolysis were：the amount of pectinase reached to 0.1% of that of date syrup,enzymolysis temperature and time were 50 ℃ and 50 min respectively,the pH value was 4.0.The optimized conditions for vaccum freeze-drying were：10% altodextrin,three times volumn of water with the thickness of 7 mm.[Conclusion] The optimized conditions were obtained in this study to produce instant date powder from Ziziphus jujuba.     

Purification and Trypsin Inhibitor Activity of a Sporamin B from Sweet Potato （Ipomoea batatas Lam. 55-2）

Sporamin is a soluble protein in sweet potato, and falls into two distinct homology groups, subfamilies A and B. In this research, a sporamin B was purified and its amino acid sequences, trypsin inhibitor activity （Ti activity） were analyzed. This sporamin B was isolated from sweet potato tubers [Ipomoea batatas （L.） Lam cv. 55-2] through extraction of the water-soluble fraction, dialysis, ultrafiltration and ion-exchange chromatography. Homology determined by polyacrylamide gel electrophoresis showed that mainly one bond appeared in gel after being reduced by SDS （sodium dodecyl sulfate）, or by SDS and 2-mercaptoethanol, or in native situation. By comparing the data of the polypeptide mass Matrix-assisted laser desorption/ionization time-of-flight （MALDI-TOF） mass spectrometry with those of the mass of the theoretical amino acid sequences from NCBI protein database, it was revealed that it was Q40091｜Q40091_IPOBA, sweet potato sporamin B - Ipomoea Batatas （sweet potato） （Batate）. The sequence coverage was 70.6%. N-terminal sequence was SETPV （Ser-Glu-Thr-Pro-Val）. There is a linear relationship between trypsin inhibitor activity （Ti activity） and amounts of this sporamin B （3-18 μg mL-1）. The equation of linear regression was y = 2.5809x ＋ 17.049 （r2 = 0.9966）. There was a curvilinear relationship between Ti activity and amounts of this sporamin B （21-150 μg mL-1）. The equation of curvilinear regression is y = 14.417ln（x） ＋ 23.26 （r2 = 0.9924）. The concentration of sporamin B with Ti activity after heating at 40°C may induce part denature of this sporamin B, and there was no statistic difference after heating at 40, 50, 60°C for 20 min. Heat treatment at more than 90°C leads to a dramatic decrease of trypsin inhibitor efficiency. The results suggested that Q40091｜Q40091_IPOBA was the major sporamin B in sweet potato tubers [Ipomoea Batatas （L.） Lam cv. 55-2], which had strong Ti activity, and was stable to both thermal and DTT （DL-dithiothreitol） relatively.     

Determination of the Content of Total Alkaloids in Different Solvent Extracts from Climbing Groundsel Herb Produced in Guizhou Province and Their Antibacterial Activity

[Objective] This study aimed to compare the contents of total alkaloids in different solvent extracts from climbing groundsel herb produced in Guizhou Province and their antibacterial activity. [Method] The content of total alkaloids was measured by UV spectrophotometry, and Oxford cups were used to investigate the antibacterial activity of each solvent extract. [Result] There was a good linear correlation between the absorbance measured by the UV spectrophotometer and the content of total al- kaloids within the concentration of 0.011 0-0.054 8 mg/ml at 207 nm, and the re- gression equation was Y=23.654X＋0.021, R=0. 999 7 and the average recovery rate was 99.2%. The contents of total alkaloids in 60% ethanol extract, 95% ethanol and water ethanol were 38.71, 52.25 and 60.50 mg/g, respectively. The 60% ethanol ex- tract had strong antibacterial activity against Streptococcus pneumoniae, Staphylo- coccus aureus and Escherichia coil; the water extractive had stronger antibacterial activity against Escherichia colr, 95% ethanol extract had weak antibacterial activity, with no inhibition of Pseudomonas aeruginosa. [Conclusion] This method is accurate, simple, with good repeatability, which can be used for the determination of alkaloids content of the climbing groundsel herb; there is no positive correlation between the content of total alkaloids in different solvent extracts of climbing groundsel herb and their antibacterial activity.     

Comparsion of the Effects of Succinate and NADH on Postmortem Metmyoglobin Redcutase Activity and Beef Colour Stability

In two experiments, the effects of succinate and NADH（reduced nicotinamide adenine dinucleotide） on metmyoglobin reductase activity and electron transport chain-linked metmyoglobin reduction were investigated and compared. In experiment 1, metmyoglobin（MetMb）, substrate and inhibitors were incubated with mitochondria. Comparsion of the effects of succinate and NADH on MetMb reduction was investigated. The MetMb percentage in sample treated with 8 mol L-1 succinate decreased by about 69% after 3 h incubation, and the effect was inhibited by the addition of 10 mol L-1 electron transfer chain complex II inhibitor malonic acid; the MetMb percentage in samples treated with 2 mol L-1 NADH decreased by 56% and the effect was inhibited by the addition of 0.02 mol L-1 electron transport chain complex I inhibitor rotenone. These results indicated that electron transport chain played an important role in MetMb reduction. Both complex II and complex I take part in the MetMb reduction in mitochondria through different pathways. NADH-MetMb reduction system was less stable than succinateMetMb system. In experiment 2, the beef longissimus dorsi muscle was blended with different concentrations of succinate or NADH. Enhancing patties with higher concentration of succinate or NADH improved colour stability in vacuum packaged samples（P〈0.05）. These results verified that mitochondria electron transport chain is related to the MetMb reduction in meat system.     

The Differentiation-and Proliferation-Inhibitory Effects of Sporamin from Sweet Potato in 3T3-L1 Preadipocytes

The aim of this study was to investigate the effect of different concentrations of sporamin on the differentiation and proliferation of 3T3-LI preadipocytes, providing the theoretical basis for the development of food to treat obesity and diabetes, The isolation and purification of sporamin from sweet potato species 55-2 were performed by ammonium sulphate precipitation in combination with ion-exchange and gel filtration chromatography. With berberine as a positive control, different concentrations ofsporamin （0.000, 0.125, 0.025, 0.250, 0.500, and 1.000 mg·mL^-1 were used to treat 3T3-L1 preadipocytes. Intracellular fat accumulation and the degree of adipogenesis were quantified using Oil Red O staining and colorimetry, Preadipocytes differentiation was measured by 3（4,5-dimethylthiazolyl-2-yl）-2,5-diphenyltetrazolium bromide （MTT） spectrophotometric assay. Two sporamin proteins, which were separated into sporamin A （31 kD） and sporamin B （22 kD）, could be purified by ion-exchange and gel filtration chromatography. After being treated by different concentrations of sporamin, the differentiation of 3T3-L1 preadipocytes was significantly inhibited, compared with the positive control. When the sporamin solution concentration was 0.500 mg mL-1, the accumulation of lipid droplets within the cells was significantly decreased and the optical density （OD） value of the solution from destained Oil Red O reached to 0.35, which was the lowest value （P〈 0.05）. The proliferation of 3T3-L1 preadipocytes was significantly inhibited by treating at higher sporamin concentrations. In addition, the inhibitory effect was more obvious with the prolonged treatment time （P〈 0.05）. The differentiation and proliferation of 3T3-L1 preadipocytes could be inhibited significantly by the addition of higher concentration sporamin. It was, therefore, suggested that the sporamin was potentially effective for weight loss.