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Sample records for exogenous fibrolytic enzymes

  1. Considerations on the Use of Exogenous Fibrolytic Enzymes to Improve Forage Utilization

    PubMed Central

    Mendoza, Germán D.; Plata-Pérez, Fernando X.

    2014-01-01

    Digestion of cell wall fractions of forage in the rumen is incomplete due to the complex links which limit their degradation. It is therefore necessary to find options to optimize the use of forages in ruminant production systems. One alternative is to use exogenous enzymes. Exogenous fibrolytic enzymes are of fungal or bacterial origin and increase nutrient availability from the cell wall, which consists of three fractions in different proportions depending on the species of forage: digestible, potentially digestible, and indigestible. The response to addition of exogenous enzymes varies with the type of forage; many researchers infer that there are enzyme-forage interactions but fail to explain the biological mechanism. We hypothesize that the response is related to the proportion of the potentially digestible fraction. The exogenous enzyme activity depends on several factors but if the general conditions for enzyme action are available, the potentially digestible fraction may determine the magnitude of the response. Results of experiments with exogenous fibrolytic enzymes in domestic ruminants are inconsistent. This, coupled with their high cost, has made their use unattractive to farmers. Development of cheaper products exploring other microorganisms with fibrolytic activity, such as Fomes fomentarius or Cellulomonas flavigena, is required. PMID:25379525

  2. Effect of exogenous fibrolytic enzymes on ruminal fermentation and nutrient digestion in dairy cows.

    PubMed

    Peters, Anja; Lebzien, Peter; Meyer, Ulrich; Borchert, Ulrike; Bulang, Michael; Flachowsky, Gerhard

    2010-06-01

    The aim of the present study was to examine the effects of an exogenous fibrolytic enzyme product applied to a total mixed ration (TMR) prior to feeding on ruminal fermentation, microbial protein synthesis, nutrient digestion, and milk yield and composition. Six multiparous lactating Holstein cows (598 +/- 29 kg initial live weight and 98 +/- 30 days in milk) fitted with rumen and duodenal cannulae were allocated to two treatments in a crossover design over three consecutive 28-d periods. The TMR containing 50% concentrates, 30% corn silage and 20% grass silage on dry matter (DM) basis, was mixed once daily and fed twice a day. Treatments were TMR alone (Control) or TMR with an enzyme product containing primarily cellulase and xylanase activities (9000 U endo-1,4-beta glucanase, 24000 U endo-1,3(4)-beta glucanase and 40000 U 1,4-beta xylanase per ml). The enzyme product was applied at a rate of 6.2 ml/kg TMR (DM basis). It was diluted at a rate of 1:5 with water and applied daily to the TMR. During the control period the cows received a TMR supplemented with 36 ml water/kg TMR on DM basis. Duodenal digesta flow was measured using Cr2O3 as flow marker and microbial protein in the duodenal digesta was estimated by near-infrared spectroscopy (NIRS). There were no significant differences in ruminal pH-values, NH3-N concentrations, total SCFA concentrations and molar proportions of SCFA. No treatment effects on microbial N flow to the duodenum and efficiency of microbial protein synthesis were observed. The apparent ruminal digestibilities of DM, organic matter, NDF and ADF, milk yield and composition were also not affected by the enzyme supplementation. In this study the application of exogenous fibrolytic enzymes fed to dairy cows did not show a significant effect on any parameter tested.

  3. In vitro evaluation of total mixed ration supplemented with exogenous fibrolytic enzymes for crossbred cows

    PubMed Central

    Lunagariya, Pravin Mohan; Gupta, Ram Sharan; Parnerkar, Subhash

    2017-01-01

    Aim: The study was conducted to evaluate the levels of exogenous fibrolytic enzymes (EFE) on in vitro digestibilities of dry matter (DM) and organic matter (OM), total gas production (TGP), metabolizable energy (ME) content, and microbial biomass production (MBP). Materials and Methods: The total mixed ration (TMR) was prepared using 30% each of sorghum hay and groundnut straw and 40% compound concentrate mixture to meet nutritional requirement of cow (500 kg) producing 12 kg fat corrected milk. The EFE was incorporated at 0, 40, 60, 80, 100, 120, 140, 160, 180, 200, 220, 240, 260, 280, 300, 320, 340, 360, 380, and 400 mg/kg TMR. The TMR substrates with different levels of EFE were in vitro incubated to ascertain their effect on digestibility, gas production, and nutritive values. Results: The significantly (p<0.05) higher and optimum in vitro digestibilities of DM (63.03%) and OM (63.62%) as well as TGP (72.35 ml/500 mg TMR) were observed at supplementation of 240 mg EFE/kg TMR, while ME (7.16 MJ/kg DM) and MBP (97.63 mg/500 mg TMR) were also better. Conclusion: The incorporation of EFE at 240 mg/kg TMR resulted significantly (p<0.05) higher and optimum in vitro digestibilities of DM and OM. The TGP, ME, and MBP were also better. The levels of EFE 240 mg/kg TMR were found suitable for further in vivo study in crossbred cows. PMID:28435189

  4. In vitro gas production of foliage from three browse tree species treated with different dose levels of exogenous fibrolytic enzymes.

    PubMed

    López, D; Vázquez-Armijo, J F; López-Villalobos, N; Lee-Rangel, H A; Salem, A Z M; Borquez-Gastelum, J L; Domínguez-Vara, I A; Rojo-Rubio, R

    2016-10-01

    The aim of this study was to evaluate the effect of different dose levels of exogenous fibrolytic enzymes (EFE) on in vitro ruminal fermentation kinetics and energy utilization of foliages from three browse trees (Pithecellobium dulce, Heliocarpus velutinus and Guazuma ulmifolia). Mixture of EFE product was added to the leaves of the three browse tree species at three dose levels: 0 (control), 3.5 and 7.0 mg/g of DM. Chemical composition of the foliages, including plant secondary metabolites such as total phenolics (TP), saponins (SAP) and aqueous fraction (AF), was determined. In addition, in vitro assaying of ruminal gas production kinetics was determined for the three browse three foliages treated with EFE. P. dulce had the highest crude protein content (p < 0.05), whereas G. ulmifolia had the highest content of neutral detergent fibre and SAP (p < 0.05) and H. velutinus had the lowest content of TP (p < 0.05). The interaction between tree species and dose level of EFE was significant (p < 0.05) for gas production (GP) at 24 h of incubation, parameters b and c of the accumulated GP curve, short-chain fatty acids (SCFA) and metabolizable energy (ME). The lowest (p < 0.01) extent of accumulated GP as well as the b and c values occurred in G. ulmifolia at 0 mg EFE/g DM. P. dulce had the highest (p < 0.05) values for ME and SCFA at the highest dose of EFE. Tree species and dose level had significant (p < 0.05) effects on all parameters describing in vitro ruminal fermentation kinetics and energy utilization. Addition of EFE improved the fermentation kinetics of the browse species considered in this study.

  5. Effect of Exogenous Fibrolytic Enzyme Application on the Microbial Attachment and Digestion of Barley Straw In vitro

    PubMed Central

    Wang, Y.; Ramirez-Bribiesca, J. E.; Yanke, L. J.; Tsang, A.; McAllister, T. A.

    2012-01-01

    The effects of exogenous fibrolytic enzymes (EFE; a mixture of two preparations from Trichoderma spp., with predominant xylanase and β-glucanase activities, respectively) on colonization and digestion of ground barley straw and alfalfa hay by Fibrobacter succinogenes S85 and Ruminococcus flavefaciens FD1 were studied in vitro. The two levels (28 and 280 μg/ml) of EFE tested and both bacteria were effective at digesting NDF of hay and straw. With both substrates, more NDF hydrolysis (p<0.01) was achieved with EFE alone at 280 than at 28 μg/ml. A synergistic effect (p<0.01) of F. succinogenes S85 and EFE on straw digestion was observed at 28 but not 280 μg/ml of EFE. Strain R. flavefaciens FD1 digested more (p<0.01) hay and straw with higher EFE than with lower or no EFE, but the effect was additive rather than synergistic. Included in the incubation medium, EFE showed potential to improve fibre digestion by cellulolytic ruminal bacteria. In a second batch culture experiment using mixed rumen microbes, DM disappearance (DMD), gas production and incorporation of 15N into particle-associated microbial N (15N-PAMN) were higher (p<0.001) with ammoniated (5% w/w; AS) than with native (S) ground barley straw. Application of EFE to the straws increased (p<0.001) DMD and gas production at 4 and 12 h, but not at 48 h of the incubation. EFE applied onto S increased (p<0.01) 15N-PAMN at 4 h only, but EFE on AS increased (p<0.001) 15N-PAMN at all time points. Prehydrolysis increased (p<0.01) DMD from both S and AS at 4 and 12 h, but reduced (p<0.01) 15N-PAMN in the early stage (4 h) of the incubation, as compared to non-prehydrolyzed samples. Application of EFE to barley straw increased rumen bacterial colonization of the substrate, but excessive hydrolytic action of EFE prior to incubation decreased it. PMID:25049480

  6. Effect of adding cofactors to exogenous fibrolytic enzymes on preingestive hydrolysis, in vitro digestibility, and fermentation of bermudagrass haylage.

    PubMed

    Romero, J J; Ma, Z X; Gonzalez, C F; Adesogan, A T

    2015-07-01

    Our objectives were to examine if adding metal ion cofactors (COF) to exogenous fibrolytic enzymes (EFE) would increase the beneficial effects of the EFE on the preingestive hydrolysis and in vitro digestibility and fermentation of bermudagrass haylage. In experiment 1, 5 COF (Mn(2+), Co(2+), Fe(2+), Ca(2+), and Mg(2+)) were screened to select the best candidates for synergistically enhancing release of water-soluble carbohydrates (WSC) from bermudagrass haylage by 5 EFE. The 5 EFE (1A, 2A, 11C, 13D, and 15D) were sourced from Trichoderma reesei and Aspergillus oryzae and they were the most effective of 12 EFE at increasing the neutral detergent fiber digestibility of bermudagrass haylage in a previous trial. Adding 1mM of each of the COF to EFE 2A or 11C synergistically increased release of WSC from bermudagrass haylage, as did adding (1mM) Fe(2+) to 1A, Mn(2+), Co(2+), or Fe(2+) to 13D, or Co(2+)or Fe(2+) to 15D. The greatest release of WSC responses were obtained by adding Mn(2+) to 11C (38%) or by adding Fe(2+) to 2A or 13D (10 and 21.9%, respectively). In experiment 2, the effect of increasing the COF dose on in vitro digestibility and fermentation of bermudagrass haylage was examined using the best EFE-COF combinations from experiment 1. Effects of adding increasing doses of these COF on EFE-mediated changes in vitro digestibility depended on the COF-EFE combination. Adding 10mM Mn(2+) alone to bermudagrass haylage increased DMD and NDFD by 2.7 and 6.3% and adding 11C alone increased these measures by 6.6 and 15.5%, respectively. However, adding 10mM Mn(2+) with 11C resulted in 3.5 and 8.1% increases in DMD and NDFD, respectively, beyond the increases caused by adding 11C alone. Adding Fe(2+) to 2A had no effects on EFE-mediated digestibility responses, but 2A prevented adverse effects of adding Fe(2+) alone on DMD and NDFD. In contrast, adding Fe(2+) to 13D reduced the increases in DMD and NDFD caused by adding the EFE alone. This study shows that adding COF

  7. A meta-analysis on the effect of dietary application of exogenous fibrolytic enzymes on the performance of dairy cows.

    PubMed

    Arriola, Kathy G; Oliveira, Andre S; Ma, Zhengxin X; Lean, Ian J; Giurcanu, Mihai C; Adesogan, Adegbola T

    2017-06-01

    The aim of this study was to use meta-analytical methods to estimate effects of adding exogenous fibrolytic enzymes (EFE) to dairy cow diets on their performance and to determine which factors affect the response. Fifteen studies with 17 experiments and 36 observations met the study selection criteria for inclusion in the meta-analysis. The effects were compared by using random-effect models to examine the raw mean difference (RMD) and standardized mean difference between EFE and control treatments after both were weighted with the inverse of the study variances. Heterogeneity sources evaluated by meta-regression included experimental duration, EFE type and application rate, form (liquid or solid), and method (application to the forage, concentrate, or total mixed ration). Only the cellulase-xylanase (C-X) enzymes had a substantial number of observations (n = 13 studies). Application of EFE, overall, did not affect dry matter intake, feed efficiency but tended to increase total-tract dry matter digestibility and neutral detergent fiber digestibility (NDFD) by relatively small amounts (1.36 and 2.30%, respectively, or <0.31 standard deviation units). Application of EFE increased yields of milk (0.83 kg/d), 3.5% fat-corrected milk (0.55 kg/d), milk protein (0.03 kg/d), and milk lactose (0.05 kg/d) by moderate to small amounts (<0.30 standard deviation units). Low heterogeneity (I (2) statistic <25%) was present for yields and concentrations of milk fat and protein and lactose yield. Moderate heterogeneity (I (2) = 25 to 50%) was detected for dry matter intake, milk yield, 3.5% fat-corrected milk, and feed efficiency (kg of milk/kg of dry matter intake), whereas high heterogeneity (I (2) > 50%) was detected for total-tract dry matter digestibility and NDFD. Milk production responses were higher for the C-X enzymes (RMD = 1.04 kg/d; 95% confidence interval: 0.33 to 1.74), but were still only moderate, about 0.35 standardized mean difference. A 24% numerical

  8. Treatment of tropical forages with exogenous fibrolytic enzymes: effects on chemical composition and in vitro rumen fermentation.

    PubMed

    Díaz, A; Ranilla, M J; Giraldo, L A; Tejido, M L; Carro, M D

    2015-04-01

    The effects of three treatments of fibrolytic enzymes (cellulase from Trichoderma longibrachiatum (CEL), xylanase from rumen micro-organisms (XYL) and a 1:1 mixture of CEL and XYL (MIX) on the in vitro fermentation of two samples of Pennisetum clandestinum (P1 and P2), two samples of Dichanthium aristatum (D1 and D2) and one sample of each Acacia decurrens and Acacia mangium (A1 and A2) were investigated. The first experiment compared the effects of two methods of applying the enzymes to forages, either at the time of incubation or 24 h before, on the in vitro gas production. In general, the 24 h pre-treatment resulted in higher values of gas production rate, and this application method was chosen for a second study investigating the effects of enzymes on chemical composition and in vitro fermentation of forages. The pre-treatment with CEL for 24 h reduced (p < 0.05) the content of neutral detergent fibre (NDF) of P1, P2, D1 and D2, and that of MIX reduced the NDF content of P1 and D1, but XYL had no effect on any forage. The CEL treatment increased (p < 0.05) total volatile fatty acid (VFA) production for all forages (ranging from 8.6% to 22.7%), but in general, no effects of MIX and XYL were observed. For both P. clandestinum samples, CEL treatment reduced (p < 0.05) the molar proportion of acetate and increased (p < 0.05) that of butyrate, but only subtle changes in VFA profile were observed for the rest of forages. Under the conditions of the present experiment, the treatment of tropical forages with CEL stimulated their in vitro ruminal fermentation, but XYL did not produce any positive effect. These results showed clearly that effectiveness of enzymes varied with the incubated forage and further study is warranted to investigate specific, optimal enzyme-substrate combinations. Journal of Animal Physiology and Animal Nutrition © 2014 Blackwell Verlag GmbH.

  9. Effect of the dose of exogenous fibrolytic enzyme preparations on preingestive fiber hydrolysis, ruminal fermentation, and in vitro digestibility of bermudagrass haylage.

    PubMed

    Romero, J J; Zarate, M A; Adesogan, A T

    2015-01-01

    Our objectives were to evaluate the effects of the dose rates of 5 Trichoderma reesei and Aspergillus oryzae exogenous fibrolytic enzymes (EFE; 1A, 2A, 11C, 13D, and 15D) on in vitro digestibility, fermentation characteristics, and preingestive hydrolysis of bermudagrass haylage and to identify the optimal dose of each EFE for subsequent in vitro and in vivo studies. In experiment 1, EFE were diluted in citrate-phosphate buffer (pH 6) and applied in quadruplicate in each of 2 runs at 0× (control), 0.5×, 1×, 2×, and 3×; where 1× was the respective manufacturer-recommended dose (2.25, 2.25, 10, 15, and 15g of EFE/kg of dry matter). The suspension was incubated for 24h at 25°C and for a further 24h at 39°C after the addition of ruminal fluid. In experiment 2, a similar approach to that in experiment 1 was used to evaluate simulated preingestive effects, except that sodium azide (0.02% wt/vol) was added to the EFE solution. The suspension was incubated for 24h at 25°C and then 15mL of water was added before filtration to extract water-soluble compounds. For both experiments, data for each enzyme were analyzed separately as a completely randomized block design with a model that included effects of EFE dose, run, and their interaction. In experiment 1, increasing the EFE dose rate nonlinearly increased the DM digestibility of 1A, 2A, 11C, and 13D and the neutral detergent fiber digestibility (NDFD) of 1A, 2A, 11C, and 13D. Optimal doses of 1A, 2A, 11C, 13D, and 15D, as indicated by the greatest increases in NDFD at the lowest dose tested, were 2×, 2×, 1×, 0.5×, and 0.5×, respectively. Increasing the dose rate of 2A, 11C, and 13D nonlinearly increased concentrations of total volatile fatty acids and propionate (mM), decreased their acetate-to-propionate ratios and linearly decreased those of samples treated with 1A and 15D. In experiment 2, increasing the dose rate of each EFE nonlinearly decreased concentrations of netural detergent fiber; also, increasing

  10. Influence of supplementary fibrolytic enzymes on the fermentation of corn and grass silages by mixed ruminal microorganisms in vitro.

    PubMed

    Wallace, R J; Wallace, S J; McKain, N; Nsereko, V L; Hartnell, G F

    2001-07-01

    activity, probably a type of endo-(beta-1,4)-glucanase activity, limits the rate of fermentation of corn and grass silage in the rumen. Enzyme supplements of the type used in these experiments are unlikely to possess sufficient activity to overcome this limitation by direct application to ruminal digesta, implying that treatment of the ration prefeeding will be key to harnessing the potential of exogenous fibrolytic enzymes in ruminant nutrition.

  11. Effect of feeding supplemental fibrolytic enzymes or soluble sugars with malic acid on milk production.

    PubMed

    Vicini, J L; Bateman, H G; Bhat, M K; Clark, J H; Erdman, R A; Phipps, R H; Van Amburgh, M E; Hartnell, G F; Hintz, R L; Hard, D L

    2003-02-01

    Two trials were conducted to evaluate effects of feeding supplemental fibrolytic enzymes or soluble sugars and malic acid on milk production. In trial 1, 257 cows at four sites were fed a basal diet consisting of no more than 60% of forage DM as corn silage and less than 40% as alfalfa hay. Cows were assigned randomly within site, parity, and two stages of lactation to: 1) control; 2) enzyme A; 3) enzyme B; and 4) soluble sugars and malic acid. There was a 14-d pretreatment and an 84-d treatment period. Enzyme solutions were sprayed on either the forage component or the TMR each day while mixing feed. Trial 2 was similar, except 122 cows at one site in the United Kingdom were fed diets containing forage that was 75% corn silage and 25% grass silage, and all cows began the study between 25 to 31 DIM. Mean milk productions for 233 cows that completed trial 1 were 32.9, 32.5, 32.4, and 32.9 kg/d for control, enzyme A, enzyme B, and soluble sugars and malic acid, respectively. Mean milk productions for 116 cows that completed trial 2 were 28.2, 27.9, 28.8, and 28.4 kg/d, respectively. In vitro analyses of the activities of enzyme solutions indicated that all major cellulose and hemicellulose degrading activities were present; however, the pH optima (approximate pH = 4 to 5) were more acidic, and the temperature optimum (approximately 50 degrees C) was greater than normal pH and temperature in the rumen. If fibrolytic activity in the rumen is a major mechanism of action of supplemental fibrolytic enzymes, it appears that considerable activity of these preparations was lost due to conditions in the rumen. In conclusion, feeding supplemental fibrolytic enzymes or malic acid with soluble sugars had no effect on milk production under the conditions used in this study.

  12. Effects of yeast culture and fibrolytic enzyme supplementation on in vitro fermentation characteristics of low-quality cereal straws.

    PubMed

    Tang, S X; Tayo, G O; Tan, Z L; Sun, Z H; Shen, L X; Zhou, C S; Xiao, W J; Ren, G P; Han, X F; Shen, S B

    2008-05-01

    The effects of yeast culture and fibrolytic enzyme preparation (containing cellulase and xylanase) on in vitro fermentation characteristics of rice straw, wheat straw, maize stover, and maize stover silage were examined using an in vitro gas production technique. Four levels of yeast culture and fibrolytic enzyme supplements (0, 2.5, 5.0, and 7.5 g/kg of straw DM, respectively) were tested in a 4 x 4 factorial arrangement. Supplementation of yeast culture increased the cumulative gas production, theoretical maximum of gas production, rate of gas production, IVDMD, and in vitro OM disappearance (IVOMD), and decreased the lag time for each type of straw. Fibrolytic enzyme supplementation tended to increase cumulative gas production, theoretical maximum of gas production, and rate of gas production; prolonged lag time of gas production; and enhanced IVDMD and IVOMD for 4 types of cereal straws, with the significance of this effect being dependent on the level of supplemented enzymes. There were significant interactions between fibrolytic enzymes and yeast on all in vitro gas production parameters, IVDMD, and IVOMD of each type of straw. The outcome of this research indicated that the application of fibrolytic enzyme preparation and yeast culture could improve in vitro gas production fermentation of cereal straws.

  13. Metagenomic insights into the rumen microbial fibrolytic enzymes in Indian crossbred cattle fed finger millet straw.

    PubMed

    Jose, V Lyju; Appoothy, Thulasi; More, Ravi P; Arun, A Sha

    2017-12-01

    The rumen is a unique natural habitat, exhibiting an unparalleled genetic resource of fibrolytic enzymes of microbial origin that degrade plant polysaccharides. The objectives of this study were to identify the principal plant cell wall-degrading enzymes and the taxonomic profile of rumen microbial communities that are associated with it. The cattle rumen microflora and the carbohydrate-active enzymes were functionally classified through a whole metagenomic sequencing approach. Analysis of the assembled sequences by the Carbohydrate-active enzyme analysis Toolkit identified the candidate genes encoding fibrolytic enzymes belonging to different classes of glycoside hydrolases(11,010 contigs), glycosyltransferases (6366 contigs), carbohydrate esterases (4945 contigs), carbohydrate-binding modules (1975 contigs), polysaccharide lyases (480 contigs), and auxiliary activities (115 contigs). Phylogenetic analysis of CAZyme encoding contigs revealed that a significant proportion of CAZymes were contributed by bacteria belonging to genera Prevotella, Bacteroides, Fibrobacter, Clostridium, and Ruminococcus. The results indicated that the cattle rumen microbiome and the CAZymes are highly complex, structurally similar but compositionally distinct from other ruminants. The unique characteristics of rumen microbiota and the enzymes produced by resident microbes provide opportunities to improve the feed conversion efficiency in ruminants and serve as a reservoir of industrially important enzymes for cellulosic biofuel production.

  14. Fibrolytic enzyme and ammonia application effects on the nutritive value, intake, and digestion kinetics of bermudagrass hay in beef cattle.

    PubMed

    Romero, J J; Zarate, M A; Queiroz, O C M; Han, J H; Shin, J H; Staples, C R; Brown, W F; Adesogan, A T

    2013-09-01

    The objectives were to compare the effect of exogenous fibrolytic enzyme (Biocellulase A20) or anhydrous ammonia (4% DM) treatment on the nutritive value, voluntary intake, and digestion kinetics of bermudagrass (Cynodon dactylon cultivar Coastal) hay harvested after 2 maturities (5- and 13-wk regrowths). Six individually housed, ruminally cannulated Brangus steers (BW 325 ± 10 kg) were used in an experiment with a 6 × 6 Latin square design with a 3 (additives) × 2 (maturities) factorial arrangement of treatments. Each period consisted of 14 d of adaptation and 7, 4, 1, 1, and 4 d for measuring in vivo digestibility, in situ degradability, no measurements, rumen liquid fermentation and passage indices, and rate of solid passage, respectively. Steers were fed hay for ad libitum intake and supplemented with sugarcane molasses and distillers grain (supplement total of 2.88 kg DM/d). Enzyme did not affect the nutritional composition of hay but ammonia treatment decreased hay NDF, hemicellulose, and ADL concentrations and increased the CP concentration particularly for the mature lignified 13-wk hay. The enzyme increased NDF and hemicellulose digestibility of the 5-wk hay but decreased those of the 13-wk hay. Ammoniation decreased intake of hay but increased digestibility of DM, OM, NDF, hemicellulose, ADF, and cellulose and increased the ruminal in situ soluble and potentially digestible fractions and the rate of DM degradation of the 13-wk hay. Also, ammoniation increased the concentrations of ruminal NH3, total VFA, acetate, and butyrate but enzyme treatment did not. Neither enzyme addition nor ammoniation affected rate of liquid and solid passage. In conclusion, ammoniation decreased the concentration of most fiber fractions, decreased the intake of hays, and increased their CP concentration, in vivo digestibility, and in situ degradability at both maturities whereas enzyme application increased fiber digestibility of the 5-wk hay but decreased it in the case of

  15. Effect of fortifying concentrate supplement with fibrolytic enzymes on nutrient utilization, milk yield and composition in lactating goats.

    PubMed

    Bala, Prokasananda; Malik, Raman; Srinivas, Bandla

    2009-06-01

    Thirty lactating Beetle-sannen crossbred goats were randomly divided into 3 groups based on first fortnight milk yield, and then adjusted to body weights to study the effect of fibrolytic enzyme supplementation on digestibility and milk production. Goats in the control group (C) were fed 500 g of concentrate supplement (CS) without exogenous fibrolytic enzymes (control; CG) or CS fortified with cellulase and xylanases @ of 4000 and 12500 (EG(1)) or 8000 and 18 750 IU/kg (EG(2)), respectively. CS was offered in two equal proportions just after milking at 7 and 17 h. After feeding CS, goats were fed 1200 g of wheat straw as roughage in two equal parts at 08.00 and 18.00 hours. Milk yield was studied for 3 1/2 months. Milking was done by hand. Changes in body weight were also recorded. After a preliminary period of 60 days of feeding, a 7-day digestibility trial was conducted in two intervals with 5 animals from each group at a time. The increase in either wheat straw or NDF intake due to the enzyme mixture was only 3%. There was significant improvement (P < 0.05) in the diet digestibility of DM, OM, CP, NDF, ADF and total carbohydrates (TC) between the control and EG(1) and EG(2) goats. Improvements were greater (P < 0.05) in the latter group. Microbial protein (MBP) was estimated based on purine derivatives and creatinine excreted in spot urine samples. MBP increased about 10 and 15% in EG(1) and EG(2), but these values were statistically invalid. Phenomenally milk yield, fat and SNF were significantly (P < 0.001) changed with progression of lactation. On a temporal basis, fortnightly changes in FCM yield of this study could be grouped as 1 month each of first and last and 1 1/2 of middle phase of lactation. Repeated measure analysis showed 180 to 260 mL/day of higher FCM and 16 to 20 g/day of higher SNF yield (P < 0.001) in EG(2) than control or even EG(1) during 5 to 7th fortnight. However, no significant impact (P > 0.05) was noticed on TF. Feed intake, g/kg FCM

  16. Influence of direct-fed fibrolytic enzymes on diet digestibility and ruminal activity in sheep fed a grass hay-based diet.

    PubMed

    Giraldo, L A; Tejido, M L; Ranilla, M J; Ramos, S; Carro, M D

    2008-07-01

    Six rumen-fistulated Merino sheep were used in a crossover design experiment to evaluate the effects of an exogenous fibrolytic enzyme preparation (12 g/d; ENZ), delivered directly into the rumen, on diet digestibility, ruminal fermentation, and microbial protein synthesis. The enzyme contained endoglucanase and xylanase activities. Sheep were fed a mixed grass hay:concentrate (70:30; DM basis) diet at a daily rate of 46.1 g/kg of BW(0.75). Samples of grass hay were incubated in situ in the rumen of each sheep to measure DM and NDF degradation. The supplementation with ENZ did not affect diet digestibility (P = 0.30 to 0.66), urinary excretion of purine derivatives (P = 0.34), ruminal pH (P = 0.46), or concentrations of NH(3)-N (P = 0.69) and total VFA (P = 0.97). In contrast, molar proportion of propionate were greater (P = 0.001) and acetate:propionate ratio was lower (P < 0.001) in ENZ-supplemented sheep. In addition, ENZ supplementation tended to increase (P = 0.06) numbers of cellulolytic bacteria at 4 h after feeding. Both the ruminally insoluble potentially degradable fraction of grass hay DM and its fractional rate of degradation were increased (P = 0.002 and 0.05, respectively) by ENZ treatment. Supplementation with ENZ also increased (P = 0.01 to 0.02) effective and potential degradability of grass hay DM and NDF. Ruminal fluid endoglucanase and xylanase activities were greater (P < 0.001 and 0.03, respectively) in ENZ-supplemented sheep than in control animals. It was found that ENZ supplementation did not affect either exoglucanase (P = 0.12) or amylase (P = 0.83) activity. The results indicate that supplementing ENZ directly into the rumen increased the fibrolytic activity and stimulated the growth of cellulolytic bacteria without a prefeeding feed-enzyme interaction.

  17. Development of Appropriate Fibrolytic Enzyme Combination for Maize Stover and Its Effect on Rumen Fermentation in Sheep

    PubMed Central

    Bhasker, T. Vijay; Nagalakshmi, D.; Rao, D. Srinivasa

    2013-01-01

    In vitro studies were undertaken to develop an appropriate fibrolytic enzymes cocktail comprising of cellulase, xylanase and β-D-glucanase for maize stover with an aim to increase its nutrient utilization in sheep. Cellulase and xylanase added individually to ground maize stover at an increasing dose rates (0, 100, 200, 400, 800, 1,600, 3,200, 6,400, 12,800, 25,600, 32,000, 38,400, and 44,800 IU/g DM), increased (p<0.01) the in vitro dry matter digestibility and in vitro sugar release. The doses selected for studying the combination effect of enzymes were 6,400 to 32,000 IU/g of cellulase and 12,800 to 44,800 IU/g of xylanase. At cellulase concentration of 6,400 IU/g, IVDMD % was higher (p<0.01) at higher xylanase doses (25,600 to 44,800 IU/g). While at cellulase doses (12,800 to 32,000 IU/g), IVDMD % was higher at lower xylanase doses (12,800 and 25,600 IU/g) compared to higher xylanase doses (32,000 to 44,800 IU/g). At cellulase concentration of the 6,400 to 32,000 IU/g, the amount of sugar released increased (p<0.01) with increasing levels of xylanase concentrations except for the concentration of 44,800 IU/g. No effect of β-D-glucanase (100 to 300 IU/g) was observed at lower cellulase-xylanase dose (cellulase-xylanase 12,800 to 12,800 IU/g). Based on the IVDMD, the enzyme combination cellulase-xylanase 12,800 to 12,800 IU/g was selected to study its effect on feed intake and rumen fermentation pattern, conducted on 12 rams (6 to 8 months; 20.34±2.369 kg body weight) fed 50% maize stover based TMR. The total volatile fatty acids (p<0.01) and ammonia-N concentration was higher in enzyme supplemented group, while no effect was observed on dry matter intake, ruminal pH and total nitrogen concentration. PMID:25049872

  18. Using a fibrolytic enzyme in barley-based diets containing wheat dried distillers grains with solubles: ruminal fermentation, digestibility, and growth performance of feedlot steers.

    PubMed

    He, Z X; He, M L; Walker, N D; McAllister, T A; Yang, W Z

    2014-09-01

    Two experiments were conducted to evaluate the effects of adding an exogenous fibrolytic enzyme (FE) on ruminal pH and fermentation, digestibility, and growth performance of feedlot beef cattle fed a finishing diet containing wheat dried distillers grains with solubles (DDGS). In Exp. 1, 4 ruminally cannulated Angus heifers (average BW of 807 ± 93.9 kg) were used in a replicated 4 × 4 Latin square design. Treatments were 1) control (CON; 10% barley silage and 90% barley grain-based concentrate), 2) CON diet substituting 30% wheat DDGS for barley grain (WDG), 3) WDG diet supplemented with low FE (WDGL), and 4) WDG diet supplemented with high FE (WDGH). Heifers fed WDG had less (P = 0.01) total tract DM digestibility than heifers fed CON. Increasing FE linearly (P < 0.05) increased starch digestibility without affecting digestibility of other nutrients. Addition of FE also reduced (P = 0.03) ruminal ammonia-N (NH3-N) concentration but did not affect VFA concentration. Moreover, application of FE to wheat DDGS linearly increased in situ ruminal DM (P < 0.01) and NDF (P = 0.02) disappearance after 48 h of incubation. In Exp. 2, 160 yearling steers (initial BW = 495 ± 37.9 kg) were fed the same diets as in Exp. 1. No differences in DMI, final BW, ADG, dietary NEg, or carcass characteristics were observed among diets. However, the steers fed WDG had less (P < 0.05) G:F and greater number of (P < 0.01) abscessed livers than steers fed CON. Increasing FE application in wheat DDGS diets did not affect DMI, final BW, or ADG but tended (P < 0.09) to linearly improve feed efficiency and decreased (P = 0.03) the incidence of abscessed livers. These results demonstrated adverse effects of including wheat DDGS in finishing diets on feed digestion, feed efficiency, and animal health. Application of FE in wheat DDGS-based diets potentially improved starch digestion, protein metabolism in the rumen, feed efficiency, and animal health.

  19. Effect of fibrolytic enzymes added to a Andropogon gayanus grass silage-concentrate diet on rumen fermentation in batch cultures and the artificial rumen (Rusitec).

    PubMed

    Ribeiro, G O; Gonçalves, L C; Pereira, L G R; Chaves, A V; Wang, Y; Beauchemin, K A; McAllister, T A

    2015-07-01

    In vitro batch cultures were used to screen four fibrolytic enzyme mixtures at two dosages added to a 60 : 40 silage : concentrate diet containing the C(4) tropical grass Andropogon gayanus grass ensiled at two maturities - vegetative stage (VS) and flowering stage (FS). Based on these studies, one enzyme mixture was selected to treat the same diets and evaluate its impact on fermentation using an artificial rumen (Rusitec). In vitro batch cultures were conducted as a completely randomized design with two runs, four replicates per run and 12 treatments in a factorial arrangement (four enzyme mixtures×three doses). Enzyme additives (E1, E2, E3 and E4) were commercial products and contained a range of endoglucanase, exoglucanase and xylanase activities. Enzymes were added to the complete diet 2 h before incubation at 0, 2 and 4 μl/g of dry matter (DM). Gas production (GP) was measured after 3, 6, 12, 24 and 48 h of incubation. Disappearance of DM (DMD), NDF (NDFD) and ADF (ADFD) were determined after 24 and 48 h. For all four enzyme mixtures, a dosage effect (P>0.05) DM, N, NDF or ADF disappearance after 48 h of incubation nor daily ammonia-N, volatile fatty acids or CH(4) production. However, enzyme application increased (P<0.05) microbial N production in feed particle-associated (loosely-associated) and silage feed particle-bound (firmly associated) fractions. With A. gayanus silage diets, degradation may not be limited by microbial colonization, but rather by the ability of fibrolytic enzymes to degrade plant cell walls within this recalcitrant forage.

  20. The dynamics of major fibrolytic microbes and enzyme activity in the rumen in response to short- and long-term feeding of Sapindus rarak saponins.

    PubMed

    Wina, E; Muetzel, S; Becker, K

    2006-01-01

    To investigate the short- and long-term effects of an extract of Sapindus rarak saponins (SE) on the rumen fibrolytic enzyme activity and the major fibrolytic micro-organisms. Two feeding trials were conducted. In the short-term trial, four fistulated goats were fed a basal diet containing sugar cane tops and wheat pollard (65:35, w/w) and were supplemented for 7 days with SE at a level of 0.6 g kg(-1) body weight. Rumen liquor was taken before, during and after SE feeding. In the long-term trial, 28 sheep were fed the same basal diet as the goats and were supplemented for 105 days with 0.24, 0.48 and 0.72 g kg(-1) body mass of the extract. Rumen liquor was taken on days 98 and 100. Protozoal numbers were counted under the microscope. Cell wall degradation was determined by enzyme assays and the major fibrolytic micro-organisms were quantified by dot blot hybridization. Sapindus extract significantly depressed rumen xylanase activity in both trials and carboxymethylcellulase activity in the long-term trial (P < 0.01). Fibrobacter sp. were not affected by the SE in both trials, while ruminococci and the anaerobic fungi showed a short-term response to the application of saponins. Protozoal counts were decreased only in the long-term trial with sheep. These data suggest that there is an adaptation of Ruminococcus albus, Ruminococcus flavefaciens and Chytridiomycetes (fungi) to saponin when fed over a long period. The fact that no correlation between the cell wall degrading enzyme activities and the cell wall degrading micro-organisms was observed suggests that the organisms tracked in this experiment are not the only key players in ruminal cell wall degradation. Sapindus rarak saponins partially defaunate the rumen flora. Their negative effect on cell wall degradation, however, is not related to rumen organisms currently recognized as the major cell wall degrading species. The adaptation of microbes in the long-term feeding experiment suggests that the results from

  1. Conservation, fiber digestibility, and nutritive value of corn harvested at 2 cutting heights and ensiled with fibrolytic enzymes, either alone or with a ferulic acid esterase-producing inoculant.

    PubMed

    Lynch, J P; Baah, J; Beauchemin, K A

    2015-02-01

    The aim of this study was to determine the effects of the use of a fibrolytic enzyme product, applied at ensiling either alone or in combination with a ferulic acid esterase-producing bacterial additive, on the chemical composition, conservation characteristics, and in vitro degradability of corn silage harvested at either conventional or high cutting height. Triplicate samples of corn were harvested to leave stubble of either a conventional (15cm; NC) or high (45cm; HC) height above ground. Sub-samples of chopped herbage were ensiled untreated or with a fibrolytic enzyme product containing xylanases and cellulases applied either alone (ENZ) or in combination with a ferulic acid esterase-producing silage inoculant (ENZ+FAEI). The fibrolytic enzyme treatment was applied at 2mL of enzyme product/kg of herbage dry matter (DM), and the inoculant was applied at 1.3×10(5) cfu/g of fresh herbage. Samples were packed into laboratory-scale silos, stored for 7, 28, or 70 d, and analyzed for fermentation characteristics, and samples ensiled for 70 d were also analyzed for DM losses, chemical composition, and in vitro ruminal degradability. After 70 d of ensiling, the fermentation characteristics of corn silages were generally unaffected by cutting height, whereas the neutral detergent fiber, acid detergent fiber, and ash concentrations were lower and the starch concentration greater for silages made with crops harvested at HC compared with NC. After 70 d of ensiling, the acetic acid, ethanol concentrations, and the number of yeasts were greater, and the pH and neutral detergent fiber concentrations were lower, in silages produced using ENZ or ENZ+FAEI than the untreated silages, whereas ENZ+FAEI silages also incurred higher DM losses. No effect of additive treatment was observed on in vitro degradability indices after 48h ruminal incubation. The use of a fibrolytic enzyme product, either alone or in combination with a ferulic acid esterase-producing inoculant, at ensiling

  2. Effects of an exogenous enzyme preparation on microbial protein synthesis, enzyme activity and attachment to feed in the Rumen Simulation Technique (Rusitec).

    PubMed

    Wang, Y; McAllister, T A; Rode, L M; Beauchemin, K A; Morgavi, D P; Nsereko, V L; Iwaasa, A D; Yang, W

    2001-03-01

    The effects of an exogenous enzyme preparation, the application method and feed type on ruminal fermentation and microbial protein synthesis were investigated using the rumen simulation technique (Rusitec). Steam-rolled barley grain and chopped alfalfa hay were sprayed with water (control, C), an enzyme preparation with a predominant xylanase activity (EF), or autoclaved enzyme (AEF) 24 h prior to feeding, or the enzyme was supplied in the buffer infused into the Rusitec (EI). Microbial N incorporation was measured using (15NH4)2SO4 in the buffer. Spent feed bags were pummelled mechanically in buffer to segregate the feed particle-associated (FPA) and feed particle-bound (FPB) bacterial fractions. Enzymes applied to feed reduced neutral-detergent fibre content, and increased the concentration of reducing sugars in barley grain, but not alfalfa hay. Ruminal cellulolytic bacteria were more numerous with EF than with C. Disappearance of DM from barley grain was higher with EF than with C, but alfalfa was unaffected by EF. Treatment EF increased incorporation of 15N into FPA and FPB fractions at 24 and 48 h. In contrast, AEF reduced the 24 h values, relative to C; AEF and C were similar at 48 h. Infused enzyme (EI) did not affect 15N incorporation. Xylanase activity in effluent was increased by EF and EI, compared to C, but not by AEF. Xylanase activity in FPA was higher at 48 h than at 24 h with all treatments; it was higher with EF than C at 24 and 48 h, but was not altered by AEF or EI. Applying enzymes onto feeds before feeding was more effective than dosing directly into the artificial rumen for increasing ruminal fibrolytic activity.

  3. Notable fibrolytic enzyme production by Aspergillus spp. isolates from the gastrointestinal tract of beef cattle fed in lignified pastures

    PubMed Central

    Abrão, Flávia Oliveira; Pessoa, Moisés Sena; dos Santos, Vera Lúcia; de Freitas Júnior, Luiz Fernando; Barros, Katharina de Oliveira; Hughes, Alice Ferreira da Silva; Silva, Thiago Dias; Rodriguez, Norberto Mário

    2017-01-01

    Fungi have the ability to degrade vegetal cell wall carbohydrates, and their presence in the digestive tract of ruminants can minimize the effects of lignified forage on ruminal fermentation. Here, we evaluated enzyme production by Aspergillus spp. isolates from the digestive tracts of cattle grazed in tropical pastures during the dry season. Filamentous fungi were isolated from rumen and feces by culture in cellulose-based medium. Ninety fungal strains were isolated and identified by rDNA sequence analysis, microculture, or both. Aspergillus terreus was the most frequently isolated species, followed by Aspergillus fumigatus. The isolates were characterized with respect to their cellulolytic, xylanolytic, and lignolytic activity through qualitative evaluation in culture medium containing a specific corresponding carbon source. Carboxymethyl cellulase (CMCase) activity was quantified by the reducing sugar method. In the avicel and xilan degradation test, the enzyme activity (EA) at 48 h was significantly higher other periods (P < 0.05). Intra- and inter-specific differences in EA were verified, and high levels of phenoloxidases, which are crucial for lignin degradation, were observed in 28.9% of the isolates. Aspergillus terreus showed significantly higher EA for avicelase (3.96 ±1.77) and xylanase (3.13 ±.091) than the other Aspergillus species at 48 h of incubation. Isolates AT13 and AF69 showed the highest CMCase specific activity (54.84 and 33.03 U mg-1 protein, respectively). Selected Aspergillus spp. isolates produced remarkable levels of enzymes involved in vegetal cell wall degradation, suggesting their potential as antimicrobial additives or probiotics in ruminant diets. PMID:28850605

  4. Effect of wheat dried distillers grains with solubles and fibrolytic enzymes on ruminal fermentation, digestibility, growth performance, and feeding behavior of beef cattle.

    PubMed

    He, Z X; Walker, N D; McAllister, T A; Yang, W Z

    2015-03-01

    Two experiments were conducted to evaluate the effect of wheat dried distillers grains with solubles (DDGS) and fibrolytic enzymes (FE) on ruminal fermentation, in situ ruminal and in vivo total tract digestibility, growth performance, and feeding behavior of growing beef cattle. In Exp. 1, 6 ruminally cannulated Angus heifers (average BW of 794 ± 44.2 kg) were used in a 6 × 6 Latin square design with 2 × 3 factorial arrangement of treatments. Treatments were a control diet consisting of 50% barley silage, 10% grass hay, and 40% barley grain-based concentrate (CON) and the CON with 15% DDGS substituted for barley grain (WDG) combined with either 0, 1, or 2 mL FE/kg diet DM, respectively. Inclusion of DDGS increased total tract digestibility of CP ( < 0.01), NDF ( = 0.04), and ADF ( = 0.03). Increasing FE linearly ( = 0.03) increased CP digestibility without affecting the digestibility of other nutrients. There were no effects of DDGS inclusion or FE on ruminal pH or VFA concentration except that propionate was greater ( = 0.04) with the WDG. In situ ruminal DM and NDF disappearance of barley silage was greater ( < 0.04) in heifers fed the WDG than in heifers fed the CON after 24 h of incubation. Increasing FE linearly ( = 0.03) increased in situ NDF disappearance of barley silage after 24 h of incubation. In Exp. 2, 120 weaned steers (initial BW of 289 ± 11.0 kg) were fed diets similar to those in Exp. 1. The steers fed the WDG had greater ( < 0.01) final BW, ADG, DMI, and G:F compared with steers fed the CON. Increasing FE did not alter ADG or G:F but tended ( < 0.07) to linearly decrease DMI. There were interactions ( < 0.02) between DDGS and FE on eating rate and the time spent at the feed bunk. Supplementing FE decreased ( < 0.01) time at the bunk and increased ( < 0.01) eating rate for steers fed the WDG but not for steers fed the CON. Eating rate ( < 0.01) and meal frequency ( = 0.02) were greater but eating duration was shorter ( < 0.01) for steers fed

  5. Controlled exogenous enzyme imbibition and activation in whole chickpea seed enzyme reactor (SER).

    PubMed

    Kliger, Eynav; Fischer, Lutz; Lutz-Wahl, Sabine; Saguy, I Sam

    2011-05-01

    Chickpeas are of excellent quality (protein, vitamins, minerals, unsaturated fatty acids) and very low in phytoestrogen, making them a potentially promising source for vegetarian-based infant formula (VBIF). However, their high starch and fiber concentration could hinder their utilization for infants. To overcome this natural shortcoming, a solid-state "enzymation" (SSE) process was developed in which imbibition of exogenous enzyme facilitates hydrolysis within the intact chickpea seed. The process was termed seed enzyme reactor (SER). Liquid imbibition data of dry chickpeas during soaking were fitted with the Weibull distribution model. The derived Weibull shape parameter, β, value (0.77 ± 0.11) indicated that the imbibition mechanism followed Fickian diffusion. Imbibition occurred through the coat and external layers. The process was tested using green fluorescent protein (GFP) as an exogenous marker, and involved soaking, thermal treatment, peeling, microwave partial drying, rehydration in enzyme solution, and SSE at an adjusted pH, time, and temperature. Amylases, or a combination of amylases and cellulases, resulted in significant carbohydrate hydrolysis (23% and 47% of the available starch, respectively). In addition, chickpea initial raffinose and stachyose concentration was significantly reduced (91% and 92%, respectively). The process could serve as a proof of concept, requiring additional development and optimization to become a full industrial application.

  6. Intraruminal supplementation with increasing levels of exogenous polysaccharide-degrading enzymes: effects on nutrient digestion in cattle fed a barley grain diet.

    PubMed

    Hristov, A N; McAllister, T A; Cheng, K J

    2000-02-01

    The effects of supplying increasing ruminal doses of exogenous polysaccharide-degrading enzymes (EPDE) on rumen fermentation and nutrient digestion were studied using eight ruminally cannulated heifers, four of which were also duodenally cannulated, in a replicated Latin square. The heifers were fed a diet of 85.5% rolled barley grain and 14% barley silage (DM basis), and once daily they were given intraruminal doses of 0 (Control), 100, 200, or 400 g of a preparation containing polysaccharide-degrading enzymes. Enzyme treatment decreased ruminal pH (linear, P<.001) and increased ammonia N (quadratic, P<.001) concentration. The ruminally soluble fraction and effective degradability of feed DM in situ were increased (quadratic response, P<.001) by enzyme treatment. Ruminal administration of EPDE increased ruminal fluid carboxymethylcellulase and xylanase activities linearly (P<.001) and beta-glucanase activity quadratically (P<.01), decreased (quadratic response, P<.05) ruminal fluid viscosity, and did not affect (P>.05) ruminal fluid amylase activity. Elevated levels of fibrolytic activities in the rumen resulted in increased (quadratic, P<.001) carboxymethylcellulase, xylanase, and beta-glucanase (P<.01) activities in duodenal digesta. Duodenal amylase activity and reducing sugar concentration were also increased (quadratic responses, P<.001 and P<.05, respectively) by EPDE. Xylanase activity of fecal DM was increased linearly (P<.05) with increasing ruminal EPDE levels. Apparent digestibilities of DM, crude protein, and NDF were not affected by EPDE supplementation. Enzyme treatment did not affect (P>.05) urinary excretion of allantoin and uric acid, or concentrations of glucose and urea in blood.

  7. Effects of treating sorghum wet distillers grains with solubles with fibrolytic enzymes on nutrient digestibility and performance in finishing beef steers

    USDA-ARS?s Scientific Manuscript database

    Two experiments were conducted to determine the effects of treating sorghum WDG with solubles (SWDG) with an enzyme, or enzyme-buffer combination on diet digestibility and feedlot performance. Experimental treatments are; 1) untreated SWDG (control), 2) addition of an enzyme complex to SWDG (enzyme...

  8. Exogenous DNA internalisation by sperm cells is improved by combining lipofection and restriction enzyme mediated integration.

    PubMed

    Churchil, R R; Gupta, J; Singh, A; Sharma, D

    2011-06-01

    1. Three types of exogenous DNA inserts, i.e. complete linearised pVIVO2-GFP/LacZ vector (9620 bp), the LacZ gene (5317 bp) and the GFP gene (2152 bp) were used to transfect chicken spermatozoa through simple incubation of sperm cells with insert. 2. PCR assay, Dot Blot hybridisation and Southern hybridisation showed the successful internalisation of exogenous DNA by chicken sperm cells. 3. Lipofection and Restriction Enzyme Mediated Integration (REMI) were used to improve the rate of internalisation of exogenous DNA by sperm cells. 4. Results from dot blot as well as Southern hybridisation were semi-quantified and improved exogenous DNA uptake by sperm cells through lipofection and REMI. Stronger signals were observed from hybridisation of LacZ as well as GFP specific probe with the DNA from lipofected exogenous DNA transfected sperm DNA in comparison with those transfected with nude exogenous DNA.

  9. Exogenous enzymes upgrade transgenesis and genetic engineering of farm animals.

    PubMed

    Bosch, Pablo; Forcato, Diego O; Alustiza, Fabrisio E; Alessio, Ana P; Fili, Alejandro E; Olmos Nicotra, María F; Liaudat, Ana C; Rodríguez, Nancy; Talluri, Thirumala R; Kues, Wilfried A

    2015-05-01

    Transgenic farm animals are attractive alternative mammalian models to rodents for the study of developmental, genetic, reproductive and disease-related biological questions, as well for the production of recombinant proteins, or the assessment of xenotransplants for human patients. Until recently, the ability to generate transgenic farm animals relied on methods of passive transgenesis. In recent years, significant improvements have been made to introduce and apply active techniques of transgenesis and genetic engineering in these species. These new approaches dramatically enhance the ease and speed with which livestock species can be genetically modified, and allow to performing precise genetic modifications. This paper provides a synopsis of enzyme-mediated genetic engineering in livestock species covering the early attempts employing naturally occurring DNA-modifying proteins to recent approaches working with tailored enzymatic systems.

  10. Production of fibrolytic enzymes by Aspergillus japonicus C03 using agro-industrial residues with potential application as additives in animal feed.

    PubMed

    Facchini, Fernanda Dell Antonio; Vici, Ana Claudia; Reis, Victor Ricardo Amin; Jorge, João Atilio; Terenzi, Héctor Francisco; Reis, Ricardo Andrade; Polizeli, Maria de Lourdes Teixeira de Moraes

    2011-03-01

    Solid-state fermentation obtained from different and low-cost carbon sources was evaluated to endocellulases and endoxylanases production by Aspergillus japonicus C03. Regarding the enzymatic production the highest levels were observed at 30 °C, using soy bran added to crushed corncob or wheat bran added to sugarcane bagasse, humidified with salt solutions, and incubated for 3 days (xylanase) or 6 days (cellulase) with 70% relative humidity. Peptone improved the xylanase and cellulase activities in 12 and 29%, respectively. The optimum temperature corresponded to 60 °C and 50-55 °C for xylanase and cellulase, respectively, both having 4.0 as optimum pH. Xylanase was fully stable up to 40 °C, which is close to the rumen temperature. The enzymes were stable in pH 4.0-7.0. Cu++ and Mn++ increased xylanase and cellulase activities by 10 and 64%, respectively. A. japonicus C03 xylanase was greatly stable in goat rumen fluid for 4 h during in vivo and in vitro experiments.

  11. Why is it important to understand substrates if we are to optimize exogenous enzyme efficacy?

    PubMed

    Angel, R; Sorbara, J O B

    2014-09-01

    The use of exogenous enzymes in feeds for poultry has increased dramatically between 1990 and 2013. Today, the use of enzymes is broad, going beyond phytases and β-glucanases and xylanases to include other carbohydrases and proteases as well as lipases. The number of scientific articles and publications related to enzymes in feed clearly shows that this has been an area of intense and broad interest for scientists and nutritionists. However, knowledge of the different substrates available in the feed and how these substrates change depending on feed ingredient selection has not received the same level of attention. Understanding substrates is key to better developing and implementing exogenous enzymes. Of importance today is to potentiate endogenous digestive capabilities and use exogenous enzymes to optimize nutrient digestion and use. Our aim with this symposium was to call attention to the importance of having a more in-depth knowledge about substrates and to fill the large gaps in our current understanding of the digestive processes in poultry.

  12. Screening of exogenous enzymes for ruminant diets: relationship between biochemical characteristics and in vitro ruminal degradation.

    PubMed

    Colombatto, D; Morgavi, D P; Furtado, A F; Beauchemin, K A

    2003-10-01

    With the objective of developing a rational approach for the selection of feed enzymes for ruminants, 22 commercial enzyme products were examined in terms of protein concentration, enzymic activities on model substrates, and hydrolytic capacity, the latter determined from the release of reducing sugars from alfalfa hay and corn silage. An in vitro ruminal degradation assessment was carried out using the same substrates, untreated or treated with the 22 enzyme products at 1.5 microL/g forage DM. Stepwise regressions were then performed to establish relationships between these factors. Protein concentration and enzymic activities explained at least 84% (P < 0.01) of the variation in the release of reducing sugars from alfalfa and corn silage. Alfalfa DM degradation after incubation with ruminal fluid for 18 h was positively related to xylanase activity (R2 = 0.29, P < 0.01), but the same activity was negatively related to DM degradation of corn silage (R2 = 0.19, P < 0.05). Protease activity explained a further 10% of the alfalfa DM degradation (P < 0.10). Following sequential steps involving the determination of rate and extent of DM and fiber degradation, the best candidates for alfalfa and corn silage were selected. Enzyme products effective with alfalfa hay seemed to exert part of their effect during the pretreatment period, whereas enzymes effective with corn silage worked exclusively after ruminal fluid was added. This finding suggests that different modes of action of exogenous enzymes are attacking different substrates and may partly explain enzyme-feed specificity. In alfalfa, it seems that effective enzymes work by removing structural barriers that retard the microbial colonization of digestible fractions, increasing the rate of degradation. In corn silage, effective enzymes seem to interact with ruminal enzymes to degrade the forage more rapidly, which is consistent with previous findings of synergism between exogenous and ruminal enzymes.

  13. Management of pain in chronic pancreatitis with emphasis on exogenous pancreatic enzymes

    PubMed Central

    Hobbs, Paul M; Johnson, William G; Graham, David Y

    2016-01-01

    One of the most challenging issues arising in patients with chronic pancreatitis is the management of abdominal pain. Many competing theories exist to explain pancreatic pain including ductal hypertension from strictures and stones, increased interstitial pressure from glandular fibrosis, pancreatic neuritis, and ischemia. This clinical problem is superimposed on a background of reduced enzyme secretion and altered feedback mechanisms. Throughout history, investigators have used these theories to devise methods to combat chronic pancreatic pain including: Lifestyle measures, antioxidants, analgesics, administration of exogenous pancreatic enzymes, endoscopic drainage procedures, and surgical drainage and resection procedures. While the value of each modality has been debated over the years, pancreatic enzyme therapy remains a viable option. Enzyme therapy restores active enzymes to the small bowel and targets the altered feedback mechanism that lead to increased pancreatic ductal and tissue pressures, ischemia, and pain. Here, we review the mechanisms and treatments for chronic pancreatic pain with a specific focus on pancreatic enzyme replacement therapy. We also discuss different approaches to overcoming a lack of clinical response update ideas for studies needed to improve the clinical use of pancreatic enzymes to ameliorate pancreatic pain. PMID:27602238

  14. [Impact of exogenous paraquat on enzyme exudation and biochemical changes of lignin degradation fungi].

    PubMed

    Zhao, Yunchen; Li, Jianlong; Chen, Yuru; Huang, Haixia; Yu, Zui

    2009-08-01

    To study the effect of exogenous oxygen, we added water solution of paraquat to 7 d cultures of Coriolus versicolor for the next 148 h. Enzyme exudation and biochemical process were investigated on the addition of paraquat. We found that compared with the control (without paraquat), the addition of 30 micromol/L paraquat stimulated the activity of manganese dependent peroxidase (MnP), lignin peroxidase (LiP), and laccases (Lac) 7, 2.5 and 1.3 times, respectively. Also, addition of paraquat enhanced activity of superoxide dismutase (SOD) and catalase (CAT) in the first 48 h. Impact of paraquat on ligninolytic enzymes was significant than that on antioxidant enzyme. Addition of paraquat enhanced phenolic compounds and formaldehyde of cultures too. And concentration of malondialdehyde was increased in the first 24 h. The results showed that addition of paraquat promoted oxidative stress, but the antioxidant systems of the fungal strain are sufficient to prevent mycelia from oxidative stress. As exogenous oxygen, paraquat might be a useful substrate in degradation of lignocellulose.

  15. Fermentative characteristics and fibrolytic activities of anaerobic gut fungi isolated from wild and domestic ruminants.

    PubMed

    Paul, Shyam S; Kamra, Devki N; Sastry, Vadali R B

    2010-08-01

    Fermentative characteristics and fibrolytic enzyme activities of anaerobic gut fungi from wild (17 isolates) and domestic ruminants (15 isolates) were examined. In a medium containing 0.5% wheat straw and 0.02% cellobiose as energy source, activities of carboxymethyl cellulase (CMCase), avicelase, xylanase, acetyl esterase and protease produced by the fungal isolates were investigated. Average activity of CMCase (17.4 vs. 8.25 mIU ml(-1)), acetyl esterase (134 vs. 57 mIU ml(-1)) and protease (4400 vs. 1683 mIU ml(-1)) were significantly higher in isolates from wild ruminants than those from domestic ruminants. Xylanase and avicelase activities were comparable. When compared irrespective of source, fungal isolates having monocentric growth pattern produced more fibrolytic enzymes than isolates having polycentric growth pattern. CMCase, xylanase, avicelase activities were highest in Neocallimastix isolates. Acetyl esterase activity was highest in Piromyces and Neocallimastix isolates. Protease activity was highest in Piromyces isolates followed closely by Neocallimastix isolates. Between isolates from wild and domestic ruminants few differences were observed in pattern of carbohydrate utilisation and end products of fermentation. Inter-strain differences in the end product formation were apparent. All of the isolates produced acetate, lactate and formate; only a few isolates produced succinate. For isolation of superior fibrolytic isolates of anaerobic fungi, greater emphasis should be given to the screening of enzyme activities of isolates of genera Neocallimastix and Piromyces.

  16. Exogenous enzyme complex prevents intestinal soybean meal-induced enteritis in Mugil liza (Valenciennes, 1836) juvenile.

    PubMed

    Ramos, Leonardo R V; Pedrosa, Virgínia F; Mori, Agnes; Andrade, Carlos F F DE; Romano, Luis A; Abreu, Paulo C; Tesser, Marcelo B

    2017-02-09

    Four soybean meal-based diets containing increasing levels of an enzyme complex (E50, E100, E150 and E200 at 50, 100, 150 and 200 g ton-1, respectively) and one soybean meal-based diet without the enzyme complex (E0) were fed in triplicate to M. liza juveniles in a semi-static flow system with 20 fish per tank for 75 days. There were no differences between the treatments for animal performance parameters, but fish fed the enzyme complex treatment exhibited significantly (P<0.05) higher values of calcium bone retention compared with control fish. Although there was no relationship between bacterial counts in different sections of the gastrointestinal tract or enzyme levels, filamentous bacteria were increased in E50 compared with E150. All of the treatments resulted in higher bacterial counts in the stomach than in intestinal segments. Histological screening showed serious to moderate infiltration of inflammatory cells, modification in villus morphology and necrosis in some cases in fish fed the E0 diet. In addition, fish from the E0 treatment exhibited significantly (P<0.05) lower lipid deposition in the peritoneal cavity. Therefore, the use of low levels of exogenous enzyme is recommended in diets for M. liza when soybean meal is used as the main source of protein.

  17. Dry-grind processing using amylase corn and superior yeast to reduce the exogenous enzyme requirements in bioethanol production.

    PubMed

    Kumar, Deepak; Singh, Vijay

    2016-01-01

    Conventional corn dry-grind ethanol production process requires exogenous alpha and glucoamylases enzymes to breakdown starch into glucose, which is fermented to ethanol by yeast. This study evaluates the potential use of new genetically engineered corn and yeast, which can eliminate or minimize the use of these external enzymes, improve the economics and process efficiencies, and simplify the process. An approach of in situ ethanol removal during fermentation was also investigated for its potential to improve the efficiency of high-solid fermentation, which can significantly reduce the downstream ethanol and co-product recovery cost. The fermentation of amylase corn (producing endogenous α-amylase) using conventional yeast and no addition of exogenous α-amylase resulted in ethanol concentration of 4.1 % higher compared to control treatment (conventional corn using exogenous α-amylase). Conventional corn processed with exogenous α-amylase and superior yeast (producing glucoamylase or GA) with no exogenous glucoamylase addition resulted in ethanol concentration similar to control treatment (conventional yeast with exogenous glucoamylase addition). Combination of amylase corn and superior yeast required only 25 % of recommended glucoamylase dose to complete fermentation and achieve ethanol concentration and yield similar to control treatment (conventional corn with exogenous α-amylase, conventional yeast with exogenous glucoamylase). Use of superior yeast with 50 % GA addition resulted in similar increases in yield for conventional or amylase corn of approximately 7 % compared to that of control treatment. Combination of amylase corn, superior yeast, and in situ ethanol removal resulted in a process that allowed complete fermentation of 40 % slurry solids with only 50 % of exogenous GA enzyme requirements and 64.6 % higher ethanol yield compared to that of conventional process. Use of amylase corn and superior yeast in the dry-grind processing industry

  18. In vivo fluorescence imaging of exogenous enzyme activity in the gastrointestinal tract.

    PubMed

    Fuhrmann, Gregor; Leroux, Jean-Christophe

    2011-05-31

    Exogenous enzymes are administered orally to treat several diseases, such as pancreatic insufficiency and lactose intolerance. Due to the proteinaceous nature of enzymes, they are subject to inactivation and/or digestion in the gastrointestinal (GI) tract. Here we describe a convenient fluorescence-based assay to monitor the activity of therapeutic enzymes in real time in vivo in the GI tract. To establish the proof of principle, the assay was applied to proline-specific endopeptidases (PEPs), a group of enzymes recently proposed as adjuvant therapy for celiac disease (a highly prevalent immunogenetic enteropathy). A short PEP-specific peptide sequence which is part of larger immunotoxic sequences of gluten was labeled with a fluorescent dye and a corresponding quencher. Upon enzymatic cleavage, the fluorescence emission was dequenched and detected with an in vivo imaging system. PEPs originating from Flavobacterium meningosepticum (FM) and Myxococcus xanthus (MX) were evaluated after oral administration in rats. While MX PEP could not cleave the peptide in the stomach, FM PEP showed significant gastric activity reaching 40-60% of the maximal in vivo signal intensity. However, both enzymes produced comparable fluorescence signals in the small intestine. Coadministration of an antacid drug significantly enhanced MX PEP's gastric activity due to increased pH and/or inhibition of stomach proteases. With this simple procedure, differences in the in vivo performance of PEPs, which could not be identified under in vitro conditions, were detected. This imaging assay could be used to study other oral enzymes in vivo and therefore be instrumental in improving their therapeutic efficiency.

  19. In vivo fluorescence imaging of exogenous enzyme activity in the gastrointestinal tract

    PubMed Central

    Fuhrmann, Gregor; Leroux, Jean-Christophe

    2011-01-01

    Exogenous enzymes are administered orally to treat several diseases, such as pancreatic insufficiency and lactose intolerance. Due to the proteinaceous nature of enzymes, they are subject to inactivation and/or digestion in the gastrointestinal (GI) tract. Here we describe a convenient fluorescence-based assay to monitor the activity of therapeutic enzymes in real time in vivo in the GI tract. To establish the proof of principle, the assay was applied to proline-specific endopeptidases (PEPs), a group of enzymes recently proposed as adjuvant therapy for celiac disease (a highly prevalent immunogenetic enteropathy). A short PEP-specific peptide sequence which is part of larger immunotoxic sequences of gluten was labeled with a fluorescent dye and a corresponding quencher. Upon enzymatic cleavage, the fluorescence emission was dequenched and detected with an in vivo imaging system. PEPs originating from Flavobacterium meningosepticum (FM) and Myxococcus xanthus (MX) were evaluated after oral administration in rats. While MX PEP could not cleave the peptide in the stomach, FM PEP showed significant gastric activity reaching 40–60% of the maximal in vivo signal intensity. However, both enzymes produced comparable fluorescence signals in the small intestine. Coadministration of an antacid drug significantly enhanced MX PEP’s gastric activity due to increased pH and/or inhibition of stomach proteases. With this simple procedure, differences in the in vivo performance of PEPs, which could not be identified under in vitro conditions, were detected. This imaging assay could be used to study other oral enzymes in vivo and therefore be instrumental in improving their therapeutic efficiency. PMID:21576491

  20. [Effects of exogenous enzymes on the degradation of adhesive-dentin interfaces].

    PubMed

    Deng, D L; Yang, H Y; Guo, J M; Huang, C; Gan, J; Song, F F

    2016-04-09

    To compare the effects of exogenous enzymes on the degradation of adhesive-dentin interface. Forty molars were sectioned to expose the middle-coronal dentin surface and randomly divided into two adhesive systems: an etch-and-rinse adhesive Adper Single Bond 2 and a self-etching adhesive G-Bond. After composite building up, the specimens were then randomly assigned to four groups(n=5 for each group)as follows: group 1, 24 h of water storage(the control group); group 2, six months of water storage; group 3, twelve weeks storage in artificial saliva containing clostridium histolyticum collagenase; group 4, twelve weeks storage in artificial saliva containing cholesterolesterase. The microtensile bond strengths(MTBS)were then tested. The failure modes and nanoleakage were analyzed. After aging treatments, the three aging groups showed significantly lower MTBS compared with the control group in both adhesive systems(P<0.05). For etch-and-rinse adhesive Adper Single Bond 2, the MTBS of group 3([19.6±3.5]MPa)was lower than that of group 2([23.4±4.2]MPa)and group 4([24.2±4.2]MPa)(P<0.05). For self-etching adhesive G-Bond, there was no difference on MTBS among different aging groups(P>0.05). SEM observation showed that, compared with the control group, water storage(group 2)and the exogenous enzymes(group 3 and 4)increased the nanoleakage expression(silver deposition)of both adhesive systems. Adhesive failure was the predominant fracture modes in all groups. Storage in artificial saliva containing clostridium histolyticum collagenase or cholesterol esterase could be used to accelerate the degradation process of adhesive-dentine interface.

  1. Chitosan Nanoencapsulated Exogenous Trypsin Biomimics Zymogen-Like Enzyme in Fish Gastrointestinal Tract

    PubMed Central

    Singh, Arvind R.; Ferosekhan, S.; Kothari, Dushyant C.; Pal, Asim Kumar; Jadhao, Sanjay Balkrishna

    2013-01-01

    Exogenous proteolytic enzyme supplementation is required in certain disease conditions in humans and animals and due to compelling reasons on use of more plant protein ingredients and profitability in animal feed industry. However, limitations on their utility in diet are imposed by their pH specificity, thermolabile nature, inhibition due to a variety of factors and the possibility of intestinal damage. For enhancing the efficacy and safety of exogenous trypsin, an efficient chitosan (0.04%) nanoencapsulation-based controlled delivery system was developed. An experiment was conducted for 45 days to evaluate nanoencapsulated trypsin (0.01% and 0.02%) along with 0.02% bare trypsin and 0.4% chitosan nanoparticles against a control diet on productive efficiency (growth rate, feed conversion and protein efficiency ratio), organo-somatic indices, nutrient digestibility, tissue enzyme activities, hematic parameters and intestinal histology of the fish Labeo rohita. All the synthesized nanoparticles were of desired characteristics. Enhanced fish productive efficiency using nanoencapsulated trypsin over its bare form was noticed, which corresponded with enhanced (P<0.01) nutrient digestibility, activity of intestinal protease, liver and muscle tissue transaminases (alanine and aspartate) and dehydrogenases (lactate and malate), serum blood urea nitrogen and serum protein profile. Intestinal tissues of fish fed with 0.02% bare trypsin showed broadened, marked foamy cells with lipid vacuoles. However, villi were healthier in appearance with improved morphological features in fish fed with nanoencapsulated trypsin than with bare trypsin, and the villi were longer in fish fed with 0.01% nanoencapsulated trypsin than with 0.02% nanoencapsulated trypsin. The result of this premier experiment shows that nanoencapsulated trypsin mimics zymogen-like proteolytic activity via controlled release, and hence the use of 0.01% nanoencapsulated trypsin (in chitosan nanoparticles) over bare

  2. The effects of exogenous hormones on rooting process and the activities of key enzymes of Malus hupehensis stem cuttings.

    PubMed

    Zhang, Wangxiang; Fan, Junjun; Tan, Qianqian; Zhao, Mingming; Zhou, Ting; Cao, Fuliang

    2017-01-01

    Malus hupehensis is an excellent Malus rootstock species, known for its strong adverse-resistance and apomixes. In the present study, stem cuttings of M. hupehensis were treated with three types of exogenous hormones, including indole acetic acid (IAA), naphthalene acetic acid (NAA), or green growth regulator (GGR). The effects and mechanisms of exogenous hormone treatment and antioxidant enzyme activity on adventitious root formation were investigated. The results showed that the apparent morphology of the adventitious root had four stages, including root pre-emergence stage (S0), early stage of root formation (S1), massive root formation stage (S2), and later stage of root formation (S3). The suitable concentrations of the three exogenous hormones, IAA, NAA and GGR, were 100 mg·L-1, 300 mg·L-1, and 300 mg·L-1, respectively. They shortened the rooting time by 25-47.4% and increased the rooting percentages of cuttings by 0.9-1.3 times, compared with that in the control. The dispersion in S0 stage was 3.6 times of that in the S1 stage after exogenous hormone application. The earlier the third critical point (P3) appeared, the shorter the rooting time and the greater the rooting percentage of the cuttings. During rhizogenesis, the activities of three antioxidant enzymes (POD, SOD, and PPO) showed an A-shaped trend. However, peak values of enzyme activity appeared at different points, which were 9 d before the P3, P3, and the fourth critical point (P4), respectively. Exogenous hormone treatment reduced the time to reach the peak value by 18 days, although the peak values of the enzymatic activities did not significantly changed. Our results suggested that exogenous hormone treatment mainly acted during the root pre-emergence stage, accelerated the synthesis of antioxidant enzymes, reduced the rooting time, and consequently promoted root formation. The three kinds of antioxidant enzymes acted on different stages of rooting.

  3. Effect of exogenous amylolytic enzymes on the accumulation of chlorogenic acid isomers in wounded potato tubers.

    PubMed

    Torres-Contreras, Ana Mariel; Nair, Vimal; Cisneros-Zevallos, Luis; Jacobo-Velázquez, Daniel A

    2014-08-06

    Potato tubers under wounding stress synthesize chlorogenic acid isomers, which are phenolic compounds that prevent chronic diseases. The biosynthesis of phenolic compounds in plants requires aromatic amino acids that are produced from sugars. Therefore, in this study, we hypothesized that the wound-induced accumulation of chlorogenic acid isomers in potatoes could be enhanced if the availability of sugars is increased by exogenous amylolytic enzymes applied to the surface of the site of wounding. To test this hypothesis, wounded potatoes stored at 20 °C were treated with amylolytic enzymes (pullulanase and amyloglucosidase, 282 units/mL, 10 mL/kg) after being stored for 0 (E0h), 48 (E48h), or 96 h (E96h). The highest level of accumulation of total chlorogenic acid isomers (∼210% higher than that of time 0 h samples) was observed after storage for 120 h for the E96h treatment. The results suggest that increasing the availability of carbon sources needed for the biosynthesis of phenolic compounds would trigger their accumulation in wounded plants.

  4. The effect of exogenous calcium on mitochondria, respiratory metabolism enzymes and ion transport in cucumber roots under hypoxia.

    PubMed

    He, Lizhong; Li, Bin; Lu, Xiaomin; Yuan, Lingyun; Yang, Yanjuan; Yuan, Yinghui; Du, Jing; Guo, Shirong

    2015-08-25

    Hypoxia induces plant stress, particularly in cucumber plants under hydroponic culture. In plants, calcium is involved in stress signal transmission and growth. The ultimate goal of this study was to shed light on the mechanisms underlying the effects of exogenous calcium on the mitochondrial antioxidant system, the activity of respiratory metabolism enzymes, and ion transport in cucumber (Cucumis sativus L. cv. Jinchun No. 2) roots under hypoxic conditions. Our experiments revealed that exogenous calcium reduces the level of reactive oxygen species (ROS) and increases the activity of antioxidant enzymes in mitochondria under hypoxia. Exogenous calcium also enhances the accumulation of enzymes involved in glycolysis and the tricarboxylic acid (TCA) cycle. We utilized fluorescence and ultrastructural cytochemistry methods to observe that exogenous calcium increases the concentrations of Ca(2+) and K(+) in root cells by increasing the activity of plasma membrane (PM) H(+)-ATPase and tonoplast H(+)-ATPase and H(+)-PPase. Overall, our results suggest that hypoxic stress has an immediate and substantial effect on roots. Exogenous calcium improves metabolism and ion transport in cucumber roots, thereby increasing hypoxia tolerance in cucumber.

  5. The effect of exogenous calcium on mitochondria, respiratory metabolism enzymes and ion transport in cucumber roots under hypoxia

    PubMed Central

    He, Lizhong; Li, Bin; Lu, Xiaomin; Yuan, Lingyun; Yang, Yanjuan; Yuan, Yinghui; Du, Jing; Guo, Shirong

    2015-01-01

    Hypoxia induces plant stress, particularly in cucumber plants under hydroponic culture. In plants, calcium is involved in stress signal transmission and growth. The ultimate goal of this study was to shed light on the mechanisms underlying the effects of exogenous calcium on the mitochondrial antioxidant system, the activity of respiratory metabolism enzymes, and ion transport in cucumber (Cucumis sativus L. cv. Jinchun No. 2) roots under hypoxic conditions. Our experiments revealed that exogenous calcium reduces the level of reactive oxygen species (ROS) and increases the activity of antioxidant enzymes in mitochondria under hypoxia. Exogenous calcium also enhances the accumulation of enzymes involved in glycolysis and the tricarboxylic acid (TCA) cycle. We utilized fluorescence and ultrastructural cytochemistry methods to observe that exogenous calcium increases the concentrations of Ca2+ and K+ in root cells by increasing the activity of plasma membrane (PM) H+-ATPase and tonoplast H+-ATPase and H+-PPase. Overall, our results suggest that hypoxic stress has an immediate and substantial effect on roots. Exogenous calcium improves metabolism and ion transport in cucumber roots, thereby increasing hypoxia tolerance in cucumber. PMID:26304855

  6. Effect of exogenous protease enzymes on the fermentation and nutritive value of corn silage.

    PubMed

    Young, K M; Lim, J M; Der Bedrosian, M C; Kung, L

    2012-11-01

    The objective of this study was to evaluate the effects of adding experimental formulations of exogenous protease enzymes on the fermentation and nutritive value of whole-plant corn ensiled in laboratory silos. Chopped and processed whole-plant corn (36.8% DM) was ensiled without enzymes or treated with 1 of 2 experimental proteases (E85 or E86; AB Vista, Wiltshire, UK) at 20 or 2,000 mg/kg (wet-weight basis). Forages were packed in vacuumed and heat-sealed bags and ensiled for 45 and 150 d at 23±1°C. When compared with untreated silage, addition of proteases and length of ensiling time had no effect on silage pH or concentration of crude protein. The results were similar for the concentrations of acid detergent fiber, neutral detergent fiber, and starch, although protease × time interactions were observed for these components, which were biologically minor. When compared with untreated silages, only treatment with the 2,000-mg/kg application amount of E 0425 resulted in lower neutral detergent fiber after 45 d of ensiling. Proteases did not affect NDF digestibility after 150 d of ensiling when compared with untreated silage. Similarly, treatment with enzymes did not affect the concentrations of lactic and acetic acids or ethanol when compared with untreated silage. Concentrations of NH(3)-N and soluble protein (% of crude protein) increased with storage time compared with concentrations at harvest and were greater for the 2,000-mg/kg doses of proteases when compared with untreated silage at both 45 and 150 d. In vitro ruminal digestibility of starch after 7 h of incubation was 66.3% for freshly chopped corn plants. After 45 d of ensiling, starch digestion was greater for E 0430 applied at the 2,000-mg/kg dose (80.6%) than in all other treatments, with the exception that it was similar to the 2,000-mg/kg dose of E85. After 150 d of ensiling, the 20-mg/kg dose of E 0425 (81.9%), the 2,000-mg/kg dose of E 0425 (82.9%), and the 2,000-mg/kg dose of E 0430 (88

  7. Effects of exogenous enzymes and dietary energy on performance and digestive physiology of broilers

    PubMed Central

    2013-01-01

    The study was conducted to compare the effects of XG with AG and BM at different metabolizable energy diets on growth performance, digestive physiology and energy utilization of broilers fed with corn-SBM diet. A 2 × 4 factorial design was used with two basal diets (the positive control group, PC; negative control with ME reduction 100 kcal/kg, NC) and with or without the addition of three exogenous enzymes (0.02% BM; 0.01% AG; 0.05% XG) respectively. 1,200 one-day-old broilers were randomly allocated to 8 treatments with 10 pens of 15 broilers. There was no significant difference on BW, BWG, and FI at 0-21d, 21-42d or 0-42d for diet, enzymes or their interactions, but FI at 22-42d and 0-42d were tend to be decreased with the addition of enzymes. The F/G was significantly improved by the addition of enzymes especially in NC diet. The dietary AME and TME in PC or NC diet were significantly increased by XG or AG in NC diet. The villus length and V/C of ileum were significantly increased by the addition of BM or XG. XG improved the activities of trypsin, chymotrypsin and amylase, BM improved the activity of trypsin at 21d, and AG improved the activity of chymotrypsin at 21d. Comparing to PC diet, the addition of enzymes in PC or NC diet decreased feed cost per kg body weight gain especially in NC diet (except AG in PC diet) with the highest profits for XG in NC diet. In conclusion, supplementation of 0.02% BM or 0.01% AG or 0.05% XG could improve feed conversion of broilers in corn-soybean meal diet by improving energy utilization and digestive physiology, and also supplementation of 0.05% XG had a preferable efficacy in low energy diet. PMID:23556436

  8. Effects of exogenous enzymes and dietary energy on performance and digestive physiology of broilers.

    PubMed

    Zou, Jialing; Zheng, Ping; Zhang, Keying; Ding, Xuemei; Bai, Shiping

    2013-01-01

    The study was conducted to compare the effects of XG with AG and BM at different metabolizable energy diets on growth performance, digestive physiology and energy utilization of broilers fed with corn-SBM diet. A 2 × 4 factorial design was used with two basal diets (the positive control group, PC; negative control with ME reduction 100 kcal/kg, NC) and with or without the addition of three exogenous enzymes (0.02% BM; 0.01% AG; 0.05% XG) respectively. 1,200 one-day-old broilers were randomly allocated to 8 treatments with 10 pens of 15 broilers. There was no significant difference on BW, BWG, and FI at 0-21d, 21-42d or 0-42d for diet, enzymes or their interactions, but FI at 22-42d and 0-42d were tend to be decreased with the addition of enzymes. The F/G was significantly improved by the addition of enzymes especially in NC diet. The dietary AME and TME in PC or NC diet were significantly increased by XG or AG in NC diet. The villus length and V/C of ileum were significantly increased by the addition of BM or XG. XG improved the activities of trypsin, chymotrypsin and amylase, BM improved the activity of trypsin at 21d, and AG improved the activity of chymotrypsin at 21d. Comparing to PC diet, the addition of enzymes in PC or NC diet decreased feed cost per kg body weight gain especially in NC diet (except AG in PC diet) with the highest profits for XG in NC diet. In conclusion, supplementation of 0.02% BM or 0.01% AG or 0.05% XG could improve feed conversion of broilers in corn-soybean meal diet by improving energy utilization and digestive physiology, and also supplementation of 0.05% XG had a preferable efficacy in low energy diet.

  9. The effects of exogenous hormones on rooting process and the activities of key enzymes of Malus hupehensis stem cuttings

    PubMed Central

    Tan, Qianqian; Zhao, Mingming; Zhou, Ting; Cao, Fuliang

    2017-01-01

    Malus hupehensis is an excellent Malus rootstock species, known for its strong adverse-resistance and apomixes. In the present study, stem cuttings of M. hupehensis were treated with three types of exogenous hormones, including indole acetic acid (IAA), naphthalene acetic acid (NAA), or green growth regulator (GGR). The effects and mechanisms of exogenous hormone treatment and antioxidant enzyme activity on adventitious root formation were investigated. The results showed that the apparent morphology of the adventitious root had four stages, including root pre-emergence stage (S0), early stage of root formation (S1), massive root formation stage (S2), and later stage of root formation (S3). The suitable concentrations of the three exogenous hormones, IAA, NAA and GGR, were 100 mg·L-1, 300 mg·L-1, and 300 mg·L-1, respectively. They shortened the rooting time by 25–47.4% and increased the rooting percentages of cuttings by 0.9–1.3 times, compared with that in the control. The dispersion in S0 stage was 3.6 times of that in the S1 stage after exogenous hormone application. The earlier the third critical point (P3) appeared, the shorter the rooting time and the greater the rooting percentage of the cuttings. During rhizogenesis, the activities of three antioxidant enzymes (POD, SOD, and PPO) showed an A-shaped trend. However, peak values of enzyme activity appeared at different points, which were 9 d before the P3, P3, and the fourth critical point (P4), respectively. Exogenous hormone treatment reduced the time to reach the peak value by 18 days, although the peak values of the enzymatic activities did not significantly changed. Our results suggested that exogenous hormone treatment mainly acted during the root pre-emergence stage, accelerated the synthesis of antioxidant enzymes, reduced the rooting time, and consequently promoted root formation. The three kinds of antioxidant enzymes acted on different stages of rooting. PMID:28231330

  10. Ultrasensitive self-powered cytosensors based on exogenous redox-free enzyme biofuel cells as point-of-care tools for early cancer diagnosis.

    PubMed

    Gai, Panpan; Song, Rongbin; Zhu, Cheng; Ji, Yusheng; Wang, Wengjing; Zhang, Jian-Rong; Zhu, Jun-Jie

    2015-12-07

    An exogenous redox-free, membrane-less enzyme biofuel cell-based ultrasensitive self-powered cytosensing platform was fabricated. With the ultrahigh sensitivity and the merits of not requiring external power sources or exogenous reagents, the device has great potential as a point-of-care tool for early diagnosis of cancer in vivo.

  11. Effect of Dietary Exogenous Enzyme Supplementation on Enteric Mucosal Morphological Development and Adherent Mucin Thickness in Turkeys

    PubMed Central

    Ayoola, Ayuub A.; Malheiros, Ramon D.; Grimes, Jesse L.; Ferket, Peter R.

    2015-01-01

    Anti-nutritional factors (ANFs) in feed ingredients can challenge gut health and reduce nutrient utilization. Birds typically activate their innate immune system as a protective response against the adverse effects of ANF, which often involves the secretion of mucin. Although dietary supplementation of exogenous enzymes are commonly used to alleviate the adverse effects of ANF on apparent nutrient digestibility, little is known about how they affect gut health, particularly in relation to the morphological development and mucin secretion of enteric mucosa. We carried out two trials to examine the effect of dietary supplementation of different types of exogenous enzymes on gut health of by accessing the effect of jejunum morphological development and ileal enteric adherent mucin thickness layer in turkeys. Dietary β-mannanase supplementation reduced ileal adherent mucin thickness layer (804 vs 823 μg/g; p < 0.05), while a commercial blend of xylanase, amylase, and protease (XAP) reduced ileal adherent mucin layer thickness (589 vs 740 μg/g; p < 0.05); thus reducing the apparent endogenous loss of nutrients. Both enzyme supplements also affected gut morphological characteristics. In comparison to the control treatment, dietary β-mannanase supplementation improved the jejunum tip width (219 vs 161; p < 0.05), base width (367 vs 300; p < 0.05), surface area (509,870 vs 380, 157; p < 0.05) and villi height/crypt depth ratio (7.49 vs 5.70; p < 0.05), and XAP improved the crypt depth (p < 0.05). In conclusion, dietary supplementation of exogenous enzymes may help alleviate the adverse effects of ANF on nutrient utilization by directly or indirectly removing the mucosal irritation that stimulates enteric mucin secretion. PMID:26664972

  12. The effectiveness of dietary sunflower meal and exogenous enzyme on growth, digestive enzymes, carcass traits, and blood chemistry of broilers.

    PubMed

    Alagawany, Mahmoud; Attia, Adel I; Ibrahim, Zenat A; Mahmoud, Reda A; El-Sayed, Sabry A

    2017-03-29

    High costs of conventional protein feed sources including soybean meal (SBM) generated the need for finding other alternatives. Thus, the present study was designed to evaluate the impact of graded replacements of SBM by sunflower seed meal (SFM) with or without enzyme supplementation on growth performance, digestive enzymes, carcass traits, and blood profile of broiler chickens. A total of 240 unsexed 1-week-old broiler chicks (Hubbard) were randomly divided into eight treatment groups of 30 chicks each in five replicates each of six chicks in a factorial design (4 × 2) arrangement, including four levels of SFM (0, 25, 50, and 75% replacing SBM) and two levels of enzyme (0- or 0.1-g/kg diet) supplementation. Performance traits including feed conversion ratio, body weight, and weight gain were significantly (P < 0.01) improved with increasing SFM up to 50% substitution for SBM or with enzyme supplementation in broiler diet during the experiment. However, feed intake of broiler chicks was decreased with enzyme supplementation (P < 0.05). The activities of digestive enzymes (protease and amylase) were significantly (P < 0.05) influenced and enhanced by SFM and enzyme inclusion in diets, respectively. The activities of protease and amylase were improved with SFM diet supplemented with 0.1 g/kg enzyme in comparison with those with the un-supplemented diet. The evaluated carcass traits were not statistically (P > 0.05) influenced by feeding SFM meal or enzyme addition. Biochemical blood parameters were significantly (P < 0.01) affected by SFM, enzyme, or their interaction in broiler diets, except for globulin that was not affected by dietary enzyme. It is concluded that increasing SFM level in the diet up to 50% replacing SBM with the supplementation of enzyme improved the growth performance and enhanced positively carcass traits as well as the activity of digestive enzymes in broiler chickens.

  13. [Effects of exogenous NO3- on cherry root function and enzyme activities related to nitrogen metabolism under hypoxia stress].

    PubMed

    Feng, Li-guo; Sheng, Li-xi; Shu, Huai-rui

    2010-12-01

    A water culture experiment with controlled dissolved oxygen concentration was conducted to explore the effects of exogenous NO3- on the root function and enzyme activities related to nitrogen metabolism of cherry (Prunun cerasus x P. canescens) seedlings under hypoxia stress. Comparing with the control (7.5 mmol NO3- x L(-1)), treatments 15 and 22.5 mmol NO3- x L(-1) made the materials for plant metabolism abundant, ensured the synthesis of enzyme proteins, increased root activity, maintained root respiration, improved the activities of enzymes related to nitrogen metabolism, such as nitrate reductase (NR), glutamine synthethase (GS), and glutamate dehydrogenase (NADH-GDH) in roots, and thereby, supplied enough energy for root respiration and NAD+ to glycolytic pathway, ensured electron transfer, and avoid ammonium toxicity under hypoxia stress. As a result, the injury of hypoxia stress to cherry plant was alleviated. Applying NO3- at the concentration of 22.5 mmol x L(-1) was more advisable. However, NO3- deficiency (0 mmol x L(-1)) showed opposite results. The above results suggested that applying exogenous NO3- to growth medium could regulate cherry root function and nitrogen metabolism, and antagonize the damage of hypoxia stress on cherry roots.

  14. Effect of sorghum type and malting on production of free amino nitrogen in conjunction with exogenous protease enzymes.

    PubMed

    Dlamini, Bhekisisa C; Buys, Elna M; Taylor, John R N

    2015-01-01

    Sorghum types suitable for brewing and bioethanol production are required. The effect of sorghum type (white non-tannin versus white type II tannin) on free amino nitrogen (FAN) production from sorghum grain and malt using exogenous protease enzymes was investigated over extended incubation at moderate temperature (45 °C). With grain in the absence of exogenous proteases, white non-tannin sorghum produced substantially higher levels of FAN than white type II tannin sorghum, due to the tannins in the latter. Incubating sorghum grain with neutral proteinase and amino-peptidase in combination improved FAN production. The two sorghum types produced similar FAN levels when malted and incubated in the absence of the exogenous proteases. When both sorghums were malted and incubated with neutral proteinase alone substantially more FAN yield (124-126 mg 100 g(-1)) occurred than with grains (61-84 mg 100 g(-1)). The combination of amino-peptidase and proteinase did not improve FAN further. Neither, did malting influence wort free amino acid profile. Group B amino acids constituted the highest percentage (42-47%). With grain, white non-tannin sorghum plus proteinase and amino-peptidase yields the highest FAN, with malt both white non-tannin and white type II tannin sorghums plus proteinase yield the highest FAN. © 2014 Society of Chemical Industry.

  15. [Effect of exogenic proteolytic enzymes on transfer of plasmid genes in mixed bacterial biofilms].

    PubMed

    Tets, G V; Artemenko, N K; Zaslavskaia, N V; Artemenko, K L; Knorring, G Iu; Tets, V V; Sternin, Iu I

    2009-01-01

    The effect of the enzyme complex from Vobenzin on transfer of plasmid genes in biofilms of gramnegative bacteria was studied. The extracellular matrix of the bacterial biofilms was shown to contain extracellular DNA carrying the antibiotic resistance markers. The action of the enzyme complex resulted in lower frequency of the antibiotic resistance genes transfer in mixed bacterial biofilms.

  16. [Impact of exogenous proteolytic enzymes on immunogenesis in patients with urogenital infections].

    PubMed

    Khrianin, A A; Reshetnikov, O V; Safronov, I D

    2012-01-01

    The use of systemic enzyme therapy in combination with antibiotics in the treatment of urogenital chlamydia infection in patients of both sexes proved to improve the therapeutic efficacy and to reduce the risk of the side effects.

  17. Enzyme-functionalized vascular grafts catalyze in-situ release of nitric oxide from exogenous NO prodrug.

    PubMed

    Wang, Zhihong; Lu, Yaxin; Qin, Kang; Wu, Yifan; Tian, Yingping; Wang, Jianing; Zhang, Jimin; Hou, Jingli; Cui, Yun; Wang, Kai; Shen, Jie; Xu, Qingbo; Kong, Deling; Zhao, Qiang

    2015-07-28

    Nitric oxide (NO) is an important signaling molecule in cardiovascular system, and the sustained release of NO by endothelial cells plays a vital role in maintaining patency and homeostasis. In contrast, lack of endogenous NO in artificial blood vessel is believed to be the main cause of thrombus formation. In this study, enzyme prodrug therapy (EPT) technique was employed to construct a functional vascular graft by immobilization of galactosidase on the graft surface. The enzyme-functionalized grafts exhibited excellent catalytic property in decomposition of the exogenously administrated NO prodrug. Localized and on-demand release of NO was demonstrated by in vitro release assay and fluorescent probe tracing in an ex vivo model. The immobilized enzyme retained catalytic property even after subcutaneous implantation of the grafts for one month. The functional vascular grafts were implanted into the rat abdominal aorta with a 1-month monitoring period. Results showed effective inhibition of thrombus formation in vivo and enhancement of vascular tissue regeneration and remodeling on the grafts. Thus, we create an enzyme-functionalized vascular graft that can catalyze prodrug to release NO locally and sustainably, indicating that this approach may be useful to develop new cell-free vascular grafts for treatment of vascular diseases. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Transmembrane Movement of Exogenous Long-Chain Fatty Acids: Proteins, Enzymes, and Vectorial Esterification

    PubMed Central

    Black, Paul N.; DiRusso, Concetta C.

    2003-01-01

    The processes that govern the regulated transport of long-chain fatty acids across the plasma membrane are quite distinct compared to counterparts involved in the transport of hydrophilic solutes such as sugars and amino acids. These differences stem from the unique physical and chemical properties of long-chain fatty acids. To date, several distinct classes of proteins have been shown to participate in the transport of exogenous long-chain fatty acids across the membrane. More recent work is consistent with the hypothesis that in addition to the role played by proteins in this process, there is a diffusional component which must also be considered. Central to the development of this hypothesis are the appropriate experimental systems, which can be manipulated using the tools of molecular genetics. Escherichia coli and Saccharomyces cerevisiae are ideally suited as model systems to study this process in that both (i) exhibit saturable long-chain fatty acid transport at low ligand concentrations, (ii) have specific membrane-bound and membrane-associated proteins that are components of the transport apparatus, and (iii) can be easily manipulated using the tools of molecular genetics. In both systems, central players in the process of fatty acid transport are fatty acid transport proteins (FadL or Fat1p) and fatty acyl coenzyme A (CoA) synthetase (FACS; fatty acid CoA ligase [AMP forming] [EC 6.2.1.3]). FACS appears to function in concert with FadL (bacteria) or Fat1p (yeast) in the conversion of the free fatty acid to CoA thioesters concomitant with transport, thereby rendering this process unidirectional. This process of trapping transported fatty acids represents one fundamental mechanism operational in the transport of exogenous fatty acids. PMID:12966144

  19. Transmembrane movement of exogenous long-chain fatty acids: proteins, enzymes, and vectorial esterification.

    PubMed

    Black, Paul N; DiRusso, Concetta C

    2003-09-01

    The processes that govern the regulated transport of long-chain fatty acids across the plasma membrane are quite distinct compared to counterparts involved in the transport of hydrophilic solutes such as sugars and amino acids. These differences stem from the unique physical and chemical properties of long-chain fatty acids. To date, several distinct classes of proteins have been shown to participate in the transport of exogenous long-chain fatty acids across the membrane. More recent work is consistent with the hypothesis that in addition to the role played by proteins in this process, there is a diffusional component which must also be considered. Central to the development of this hypothesis are the appropriate experimental systems, which can be manipulated using the tools of molecular genetics. Escherichia coli and Saccharomyces cerevisiae are ideally suited as model systems to study this process in that both (i) exhibit saturable long-chain fatty acid transport at low ligand concentrations, (ii) have specific membrane-bound and membrane-associated proteins that are components of the transport apparatus, and (iii) can be easily manipulated using the tools of molecular genetics. In both systems, central players in the process of fatty acid transport are fatty acid transport proteins (FadL or Fat1p) and fatty acyl coenzyme A (CoA) synthetase (FACS; fatty acid CoA ligase [AMP forming] [EC 6.2.1.3]). FACS appears to function in concert with FadL (bacteria) or Fat1p (yeast) in the conversion of the free fatty acid to CoA thioesters concomitant with transport, thereby rendering this process unidirectional. This process of trapping transported fatty acids represents one fundamental mechanism operational in the transport of exogenous fatty acids.

  20. Effect of dietary or abomasal supplementation of exogenous polysaccharide-degrading enzymes on rumen fermentation and nutrient digestibility.

    PubMed

    Hristov, A N; McAllister, T A; Cheng, K J

    1998-12-01

    The effect of site of supplementation of a mixture of two crude preparations (Enzyme C and Enzyme X) of exogenous polysaccharide-degrading enzymes (EPDE) was studied in vivo using four ruminally and duodenally cannulated heifers (Exp. 1). The treatments were as follows: control (no EPDE), EPDE supplied through the diet (EF, 47.0 g/d), and EPDE infused continuously into the abomasum (EA, 41.6 g/d). Enzyme treatment increased the concentration of soluble reducing sugars (P < .05) and decreased NDF content (P < .05) in the treated feed, but this did not increase the rate or extent of in sacco disappearance of DM from the feed. Compared with control, ruminal fermentation was not affected by EF, but abomasal infusion increased (P < .05) rumen ammonia levels and shifted ruminal VFA patterns. Ruminal carboxymethylcellulase (CMCase) and xylanase activities were not affected by treatment. Abomasal infusion increased (P < .05) duodenal xylanase activity as compared with control and EF, but apparent digestion of DM, NDF, and CP were not affected by treatment. Negligible levels of CMCase and amylase reached the duodenum. During an in vitro experiment (Exp. 2), abomasal stability of the two EPDE was studied over a range of pH from 3.39 to .85, with or without pepsin. Carboxymethylcellulase activity (in Enzymes C and X) and beta-glucanase activity (in Enzyme C) were largely unstable against pepsin proteolysis (P < .001) and low pH (P < .001). Xylanase and amylase activities were resistant to pepsin but irreversibly inactivated at low pH. These two experiments showed that abomasal supplementation of EPDE did not successfully supply cellulases and amylases to the intestine, due partially to their limited resistance to low pH and pepsin proteolysis. Although EPDE significantly increased the level of xylanase activity at the duodenum, this did not significantly improve total tract digestion.

  1. Effects of exogenous enzymes and application method on nutrient intake, digestibility and growth performance of Pelibuey lambs.

    PubMed

    López-Aguirre, Daniel; Hernández-Meléndez, Javier; Rojo, Rolando; Sánchez-Dávila, Fernando; López-Villalobos, Nicolás; Salem, Abdel-Fattah Z M; Martínez-González, Juan Carlos; Vázquez-Armijo, José Fernando; Ruíz, Salomón

    2016-01-01

    Pelibuey sheep is the main breed in the tropical and subtropical regions of Mexico, and high demand of sheep meat has favored the finishing of lambs in feedlots with diets containing high levels of grains. The objective of this study was to evaluate the effects of exogenous enzymes (EE) and application method on nutrient intake and digestibility and performance of growing Pelibuey lambs. Treatments were based on comparison of two different methods of adding an enzyme product (sprayed on the total mixed ration or applied orally to the lambs) versus control treatment (no added enzyme). Twenty-one Pelibuey lambs, weighing 15.7 kg (SD = 1.8 kg) initial body weight, were individually housed in shaded pens and assigned randomly to one of the three enzyme treatments. At the end of study (lasting for 45 days), three lambs from each treatment were randomly selected and adapted to a pants and harness designed for fecal collection to measure nutrient digestibilities. Total body gain and average daily gain were affected (P < 0.05) by supplemental EE. The application method of EE had significant (P < 0.05) effect on FCE and FCR, but no effects were observed on nutrient intake. Supplemental EE did improve (P < 0.05) the digestibilities of dry matter, organic matter, neutral and acid detergent fiber, but no differences were observed in crude protein digestibility. The application method of EE had significant (P < 0.05) effect on the digestibility of acid detergent fiber. Supplemental EE can improve body weight gain and nutrient digestibilities without affecting nutrient intake in Pelibuey lambs, but the results of feed conversion efficiency and acid detergent fiber digestibility depend on the application method used of the EE.

  2. Effect of exogenous hormones on transcription levels of pyridoxal 5'-phosphate biosynthetic enzymes in the silkworm (Bombyx mori).

    PubMed

    Huang, ShuoHao; Yang, HuanHuan; Yao, LiLi; Zhang, JianYun; Huang, LongQuan

    2016-01-01

    Vitamin B6 includes 6 pyridine derivatives, among which pyridoxal 5'-phosphate is a coenzyme for over 140 enzymes. Animals acquire their vitamin B6 from food. Through a salvage pathway, pyridoxal 5'-phosphate is synthesized from pyridoxal, pyridoxine or pyridoxamine, in a series of reactions catalyzed by pyridoxal kinase and pyridoxine 5'-phosphate oxidase. The regulation of pyridoxal 5'-phospahte biosynthesis and pyridoxal 5'-phospahte homeostasis are at the center of study for vitamin B6 nutrition. How pyridoxal 5'-phosphate biosynthesis is regulated by hormones has not been reported so far. Our previous studies have shown that pyridoxal 5'-phosphate level in silkworm larva displays cyclic developmental changes. In the current study, effects of exogenous juvenile hormone and molting hormone on the transcription level of genes coding for the enzymes involved in the biosynthesis of pyridoxal 5'-phospahte were examined. Results show that pyridoxal kinase and pyridoxine 5'-phosphate oxidase are regulated at the transcription level by development and are responsive to hormones. Molting hormone stimulates the expression of genes coding for pyridoxal kinase and pyridoxine 5'-phosphate oxidase, and juvenile hormone appears to work against molting hormone. Whether pyridoxal 5'-phosphate biosynthesis is regulated by hormones in general is an important issue for further studies. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Effects of exogenous enzymes (phytase, non-starch polysaccharide enzyme) in diets on growth, feed utilization, nitrogen and phosphorus excretion of Japanese seabass, Lateolabrax japonicus.

    PubMed

    Ai, Qinghui; Mai, Kangsen; Zhang, Wenbing; Xu, Wei; Tan, Beiping; Zhang, Chunxiao; Li, Huitao

    2007-06-01

    A feeding experiment was conducted to investigate the effects of exogenous enzymes (phytase, non-starch polysaccharide enzymes: WX and VP, supplied by DSM) on growth performance and excretion of Japanese seabass (Lateolabrax japonicus) (initial mass 6.26+/-0.10 g). A basal diet was used as a control that contained a mixed protein source, and lysine, methionine and valine were supplemented to simulate the essential amino acid pattern of fish meal. Four other diets were supplemented with 200 mg phytase (500 IU), 400 mg VP, 800 mg WX, or a combination of 800 mg WX and 400 mg VP per kg diet, respectively. Each diet was assigned to triplicate groups of fish in floating sea cages, and each cage was stocked with 60 fish. The results showed specific growth rate (SGR) and feed efficiency ratio (FER) were not significantly improved by the phytase supplementation. However, supplementations with WX and VP significantly enhanced the SGR and FER (P<0.05). Phosphorus retention was significantly increased by the supplementation with phytase, whereas nitrogen retention was also enhanced by supplementations of non-starch polysaccharide enzymes (P<0.05). The excretion experiment showed that the soluble phosphorus and ammonia nitrogen in starved fish were constant, irrespective of dietary treatments. The total phosphorus effluent in fish fed the diet with phytase supplementation was significantly lower compared with the control group after feeding to satiation (P<0.05), but soluble phosphorus excretion was still independent of dietary treatments. The ammonia excretion in satiated fish significantly decreased with supplementations of non-starch polysaccharide enzymes.

  4. Exogenous phospholipase enzymes mimic effects of phenylephrine on Ca2+ transport in hepatocytes.

    PubMed Central

    Barritt, G J; Whiting, J A

    1983-01-01

    Phospholipase C from Clostridium perfringens induced the release of 45Ca2+ from isolated rat hepatocytes incubated at 0.1 mM extracellular Ca2+ with a time course similar to that for the action of phenylephrine. Under the conditions of these experiments, no significant damage to the plasma membrane was detected in the presence of phospholipase C. Little 45Ca2+ release was induced by bee venom phospholipase A2. At 1.3 mM extracellular Ca2+, both phospholipase enzymes stimulated the initial rate of 45Ca2+ exchange. Concentrations of phospholipase C comparable with those that stimulated 45Ca2+ release increased the rates of glucose release and O2 utilization by 70 and 20% respectively. An increase in the rate of O2 utilization but not glucose release was observed after the addition of phospholipase A2 to hepatocytes. The possible role for a cellular phospholipase C in the mechanism by which phenylephrine stimulates glycogenolysis in the liver cell is briefly discussed. PMID:6847637

  5. Metatranscriptomics Reveals the Active Bacterial and Eukaryotic Fibrolytic Communities in the Rumen of Dairy Cow Fed a Mixed Diet

    PubMed Central

    Comtet-Marre, Sophie; Parisot, Nicolas; Lepercq, Pascale; Chaucheyras-Durand, Frédérique; Mosoni, Pascale; Peyretaillade, Eric; Bayat, Ali R.; Shingfield, Kevin J.; Peyret, Pierre; Forano, Evelyne

    2017-01-01

    Ruminants have a unique ability to derive energy from the degradation of plant polysaccharides through the activity of the rumen microbiota. Although this process is well studied in vitro, knowledge gaps remain regarding the relative contribution of the microbiota members and enzymes in vivo. The present study used RNA-sequencing to reveal both the expression of genes encoding carbohydrate-active enzymes (CAZymes) by the rumen microbiota of a lactating dairy cow and the microorganisms forming the fiber-degrading community. Functional analysis identified 12,237 CAZymes, accounting for 1% of the transcripts. The CAZyme profile was dominated by families GH94 (cellobiose-phosphorylase), GH13 (amylase), GH43 and GH10 (hemicellulases), GH9 and GH48 (cellulases), PL11 (pectinase) as well as GH2 and GH3 (oligosaccharidases). Our data support the pivotal role of the most characterized fibrolytic bacteria (Prevotella, Ruminocccus and Fibrobacter), and highlight a substantial, although most probably underestimated, contribution of fungi and ciliate protozoa to polysaccharide degradation. Particularly these results may motivate further exploration of the role and the functions of protozoa in the rumen. Moreover, an important part of the fibrolytic bacterial community remains to be characterized since one third of the CAZyme transcripts originated from distantly related strains. These findings are used to highlight limitations of current metatranscriptomics approaches to understand the functional rumen microbial community and opportunities to circumvent them. PMID:28197133

  6. Effect of exogenous sucrose on the enzymes of starch degradation and sucrose metabolism in cowpea (Vigna unguiculata L.) seedlings.

    PubMed

    Kaur, Narinder; Kaur, Harpreet; Gupta, Anil K

    2005-10-01

    Addition of exogenous sucrose and mannitol in the growth medium decreased the germination and growth of cowpea (Vigna unguiculata L. cv C-88) seedlings. The reduced seedling growth appeared to be due to the decreased acid invertase activity in growing parts of the seedlings. An exogenous supply of sucrose upregulated the sucrose phosphate synthase (SPS) activity in different parts of seedlings. Decreased amylase activity in cotyledons and the mobilization of starch from cotyledons to the growing axis was observed in the presence of exogenous sucrose and mannitol. High sucrose content observed in different tissues in the presence of exogenous sucrose and mannitol was possibly due to high SPS and low acid invertase activities and reduced conversion of sucrose to starch. It appears that exogenous sucrose acts mainly as an osmoticum, rather than a source of carbon for the growing seedlings.

  7. Exogenous abscisic acid increases antioxidant enzymes and related gene expression in pepper (Capsicum annuum) leaves subjected to chilling stress.

    PubMed

    Guo, W L; Chen, R G; Gong, Z H; Yin, Y X; Ahmed, S S; He, Y M

    2012-11-28

    To elucidate how physiological and biochemical mechanisms of chilling stress are regulated by abscisic acid (ABA) pretreatment, pepper variety (cv. 'P70') seedlings were pretreated with 0.57 mM ABA for 72 h and then subjected to chilling stress at 10°/6°C (day/night). Chilling stress caused severe necrotic lesions on the leaves and increased malondialdehyde and H(2)O(2) levels. Activities of monodehydroascorbate reductase (DHAR), dehydroascorbate reductase, glutathione reductase, guaiacol peroxidase, ascorbate peroxidase, ascorbate, and glutathione increased due to chilling stress during the 72 h, while superoxide dismutase and catalase activities decreased during 24 h, suggesting that chilling stress activates the AsA-GSH cycle under catalase deactivation in pepper leaves. ABA pretreatment induced significant increases in the above-mentioned enzyme activities and progressive decreases in ascorbate and glutathione levels. On the other hand, ABA-pretreated seedlings under chilling stress increased superoxide dismutase and guaiacol peroxidase activities and lowered concentrations of other antioxidants compared with untreated chilling-stressed plants. These seedlings showed concomitant decreases in foliage damage symptoms, and levels of malondialdehyde and H(2)O(2). Induction of Mn-SOD and POD was observed in chilling-stressed plants treated with ABA. The expression of DHAR1 and DHAR2 was altered by chilling stress, but it was higher in the presence than in the absence of ABA at 24 h. Overall, the results indicate that exogenous application of ABA increases tolerance of plants to chilling-induced oxidative damage, mainly by enhancing superoxide dismutase and guaiacol peroxidase activities and related gene expression.

  8. Exogenous proline mediates alleviation of cadmium stress by promoting photosynthetic activity, water status and antioxidative enzymes activities of young date palm (Phoenix dactylifera L.).

    PubMed

    Zouari, M; Ben Ahmed, Ch; Zorrig, W; Elloumi, N; Rabhi, M; Delmail, D; Ben Rouina, B; Labrousse, P; Ben Abdallah, F

    2016-06-01

    The ability of exogenous compatible solutes, such as proline, to counteract cadmium (Cd) inhibitory effects in young date palm plants (Phoenix dactylifera L. cv Deglet Nour) was investigated. Two-year-old date palm plants were subjected for five months at different Cd stress levels (0, 10 and 30 mg CdCl2 kg(-1) soil) whether supplied or not with exogenous proline (20mM) added through the irrigation water. Different levels of Cd stress altered plant growth, gas exchanges and chlorophyll content as well as water status, but at different extent among them. In contrast, an increase of antioxidant enzymes activities of Cd-treated plants in association with high amounts of proline content, hydrogen peroxide (H2O2), thiobarbituric acid reactive substances (TBARS) and electrolyte leakage (EL) were observed. Interestingly, exogenous proline mitigated the adverse effects of Cd on young date palm. Indeed, it alleviated the oxidative damage induced by Cd accumulation and established better levels of plant growth, water status and photosynthetic activity. Moreover, proline-treated plants showed high antioxidant enzymes activities (superoxide dismutase, catalase and glutathione peroxydase) in roots and leaves as compared to Cd-treated plants. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Influence of Palm Kernel Meal Inclusion and Exogenous Enzyme Supplementation on Growth Performance, Energy Utilization, and Nutrient Digestibility in Young Broilers

    PubMed Central

    Abdollahi, M. R.; Hosking, B. J.; Ning, D.; Ravindran, V.

    2016-01-01

    The objective of the present study was to investigate the influence of palm kernel meal (PKM) inclusion and exogenous enzyme supplementation on growth performance, nitrogen-corrected apparent metabolizable energy (AMEn), coefficient of apparent ileal digestibility (CAID) and total tract retention of nutrients in young broilers fed corn-based diets. Four inclusion levels of PKM (no PKM [PKM0], 8% [PKM8], 16% [PKM16], and 24% [PKM24]) and two enzyme additions were evaluated in a 4×2 factorial arrangement of treatments. A total of 384, one-d-old male broilers (Ross 308) were individually weighed and allocated to 48 cages (eight broilers/cage), and cages were randomly assigned to eight dietary treatments. Results indicated that the inclusion of 8% and 16% PKM increased (p<0.05) the weight gain compared to the PKM0 diet. Birds fed the PKM8 diets had the highest (p<0.05) feed intake. Weight gain and feed intake were severely reduced (p<0.05) by feeding the PKM24 diet. Enzyme supplementation increased weight gain (p<0.05), independent of PKM inclusion level. In PKM0 and PKM8 diets, enzyme addition significantly (p<0.05) lowered feed conversion ratio (FCR); whereas enzyme addition had no effect on FCR of birds fed PKM16 and PKM24 diets. In PKM0 and PKM16 diets, enzyme addition significantly (p<0.05) increased CAID of nitrogen and energy but had no effect in the PKM8 and PKM24 diets. Inclusion of PKM into the basal diet, irrespective of inclusion level, enhanced (p<0.05) starch and fat digestibility. Inclusion of PKM at 16% and 24% resulted in similar CAID of neutral detergent fiber (NDF) but higher (p<0.05) than that of the PKM0 and PKM8 diets. Enzyme addition, regardless of the level of PKM inclusion, significantly (p<0.05) increased CAID of NDF. There was a significant (p<0.05) decrease in AMEn with PKM inclusion of 24%. The present data suggest that inclusion of PKM in broiler diets could be optimized if PKM-containing diets are formulated based on digestible amino

  10. Effect of exogenous H2O2 on antioxidant enzymes of Brassica juncea L. seedlings in relation to 24-epibrassinolide under chilling stress.

    PubMed

    Kumar, Manish; Sirhindi, Geetika; Bhardwaj, Renu; Kumar, Sandeep; Jain, Gagandeep

    2010-12-01

    Hydrogen peroxide is most stable molecule among reactive oxygen species, which play a vital role in growth and development of plant as signaling molecule at low concentration in response to various abiotic and biotic stresses. Exogenous application of H2O2 is known to induce chilling tolerance in plants. Brassinosteroids are plant steroid hormones known for their anti-stress properties. In this study, effect of exogenous H2O2 on antioxidant defense system of Brassica juncea L. seedlings was investigated in 24-epibrassinolide (24-EBL) treated and untreated seedlings under chilling stress. The surface sterilized seeds of B. juncea L. were germinated in petriplates containing different concentrations of H2O2 alone and in combination with 10(-8) M 24-EBL. Chilling treatment (4 degrees C) was given to 10-days old seedlings grown in different treatments for 6 h daily up to 3 days. 24 h recovery period was given to chilling treated seedlings by placing at 25 degrees C + 2 degrees C and harvested for antioxidant enzymes on 14th day after sowing (DAS). Treatment of 24-EBL in combination with H2O2 (15 and 20 mM) helped in reducing the toxicity of seed and seedlings due to H2O2 exposure on their germination rate, shoot and root length respectively. 24-EBL treatment at seed and seedling stage helped in alleviating the toxic effect of H2O2 through antioxidant defense system by increasing the activities of various enzymes involved in antioxidant defense system such as catalase (CAT, E.C. 1.11.1.6), ascorbate peroxidase (APOX, E.C. 1.11.1.11), and superoxide dismutase (SOD, E.C. 1.15.1.1). In conclusion, exogenous pretreatment of H2O2 to seeds of B. juncea L. adapted the seedlings to tolerate chilling stress, which was further ameliorated in combination of H2O2 with 24-EBL.

  11. Addition of exogenous enzymes to diets containing grape pomace: Effects on intestinal utilization of catechins and antioxidant status of chickens.

    PubMed

    Chamorro, S; Viveros, A; Rebolé, A; Arija, I; Romero, C; Alvarez, I; Rey, A; Brenes, A

    2017-06-01

    Grape pomace (GP) is a rich source of polyphenols with antioxidant capacity. An experiment was conducted to study the effect of GP phenolic compounds included at 5 and 10%, and the addition (individually or combined) of hydrolyzing enzymes (carbohydrase enzyme complex and tannase at 500ppm) on intestinal utilization of catechins and antioxidant status in broiler chickens. A diet supplemented with 200ppm of α-tocopheryl acetate was also used. Our findings demonstrate the capacity of chickens to digest the monomeric (catechin, epicatechin, gallic acid, and epicatechin-O-gallate) and dimeric (procyanidin B1 and procyanidin B2) catechins present in grape pomace. The addition of enzymes (mainly tannase) hydrolyzed the polymeric structures into smaller catechins, but also promoted a lower digestibility of the monomeric and dimeric catechins suggesting that polymeric structures might favour the intestinal utilization of these catechins. The intestinal accumulation of phenolic compounds generated with tannase and with 10% GP reversed the antimicrobial effect against Clostridium perfringens observed with 5% of GP. Grape pomace improved the antioxidant status of the bird, increasing the α-tocopherol and reducing the iron content on plasma, not affecting the plasma gluthatione. Enzymes modified the intestinal utilization of catechins but not additional protective effect was detected on any of the parameters analyzed to evaluate the antioxidant status. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Performance, intestinal microflora, and amino acid digestibility altered by exogenous enzymes in broilers fed wheat- or sorghum-based diets.

    PubMed

    Wu, D; Wu, S B; Choct, M; Swick, R A

    2017-02-01

    The objective of the current study was to compare the effects of dietary enzymes and nutrient restriction on performance and bone mineralization in birds fed wheat- or sorghum-based diets. A total of 720 d-old male broiler chicks were randomly allocated to 8 treatments, with 6 replicates per treatment and 15 birds per replicate. Birds were reared in floor pens from 0 to 35 d. The study used a 2 × 4 factorial arrangement with 2 grains (sorghum or wheat) and 4 diets: positive control (no enzyme and ME, digestible Lys, Ca, and P sufficient, negative control (NC; no enzyme and reduced ME [-100 kcal/kg], digestible AA [-2%], Ca [-0.12 percentage points], and available P [-0.18 percentage points in the starter phase and -0.22 percentage points in the grower phase]), NC + nonstarch polysaccharide-degrading enzymes + phytase (500 phytase units [FTU]; NCCP), and NC + phytase (1,000 FTU; NCP). From 0 to 35 d, birds fed wheat-based diets had greater G:F (4.5%), BW gain (9.2%), breast meat yield (6.8%), and tibia ash (2.0%) compared with birds fed sorghum-based diets. Across grain types, the NCCP treatment improved BW gain ( < 0.001), feed intake ( < 0.001), G:F ( < 0.05), and livability ( < 0.001) compared with the NC treatment. Birds fed NCP had greater BW gain ( < 0.001), feed intake ( < 0.001), G:F ( < 0.001), and livability ( < 0.001) compared with birds fed NC. Birds fed the NCP diet had greater BW gain ( < 0.001), toe ash ( < 0.01), and tibia ash ( < 0.001) compared with birds fed the NCCP diet. There was a grain × diet interaction for feed intake ( < 0.01), BW gain ( < 0.001), tibia ash ( < 0.01), and tibia breaking strength ( < 0.05). The influence of enzymes was more pronounced in sorghum-based diets than in wheat-based diets. Birds fed wheat-based diets had greater ileal digestibility of His, Met, Val, Phe, Ile, Leu, Trp, Glu, Pro, Ala, Tyr, and Cys compared with those fed sorghum-based diets ( < 0.05). Across grain types, NCP had greater apparent ileal

  13. Exogenous calcium induces tolerance to atrazine stress in Pennisetum seedlings and promotes photosynthetic activity, antioxidant enzymes and psbA gene transcripts.

    PubMed

    Erinle, Kehinde Olajide; Jiang, Zhao; Ma, Bingbing; Li, Jinmei; Chen, Yukun; Ur-Rehman, Khalil; Shahla, Andleeb; Zhang, Ying

    2016-10-01

    Calcium (Ca) has been reported to lessen oxidative damages in plants by upregulating the activities of antioxidant enzymes. However, atrazine mediated reactive oxygen species (ROS) reduction by Ca is limited. This study therefore investigated the effect of exogenously applied Ca on ROS, antioxidants activity and gene transcripts, the D1 protein (psbA gene), and chlorophyll contents in Pennisetum seedlings pre-treated with atrazine. Atrazine toxicity increased ROS production and enzyme activities (ascorbate peroxidase APX, peroxidase POD, Superoxide dismutase SOD, glutathione-S-transferase GST); but decreased antioxidants (APX, POD, and Cu/Zn SOD) and psbA gene transcripts. Atrazine also decreased the chlorophyll contents, but increased chlorophyll (a/b) ratio. Contrarily, Ca application to atrazine pre-treated seedlings lowered the harmful effects of atrazine by reducing ROS levels, but enhancing the accumulation of total chlorophyll contents. Ca-protected seedlings in the presence of atrazine manifested reduced APX and POD activity, whereas SOD and GST activity was further increased with Ca application. Antioxidant gene transcripts that were down-regulated by atrazine toxicity were up-regulated with the application of Ca. Calcium application also resulted in up-regulation of the D1 protein. In conclusion, ability of calcium to reverse atrazine-induced oxidative damage and calcium regulatory role on GST in Pennisetum was presented. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Effects of Methylcellulose on Fibrolytic Bacterial Detachment and In vitro Degradation of Rice Straw.

    PubMed

    Kim, Min Ji; Sung, Ha Guyn; Upadhaya, Santi Devi; Ha, Jong K; Lee, Sung Sill

    2013-10-01

    Two in vitro experiments were conducted to evaluate the effect of methylcellulose (MC) on i) bacterial detachment from rice straw as well as ii) inhibition of bacterial attachment and fiber digestibility. To evaluate the effect of MC on fibrolytic bacterial detachment (Exp 1), in vitro bacterial cultures with 0.1% (w/v) MC solution were compared with cultures without MC after 8 h incubation. The effect of MC on inhibition of bacterial attachment was determined by comparing with real-time PCR the populations of F. succinogenes, R. flavefaciens and R. albus established on rice straw pre-treated with 0.1% MC with those on untreated straw after incubation for 0, 6 and 12 h (Exp 2). The major fibrolytic bacterial attachment on rice straw showed significantly lower populations with either the addition of MC to the culture or pre-treated rice straw compared to controls (p<0.05). Also, the digestibility of rice straw with MC was significantly lower compared with control (p<0.05). The F. succinogenes population did not show detachment from rice straw, but showed an inhibition of attachment and proliferation on rice straw in accordance with a decrease of fiber digestion. The detachments of Ruminococcus species co-existed preventing the proliferations with subsequent reduction of fiber degradation by MC during the incubation. Their detachments were induced from stable colonization as well as the initial adhesion on rice straw by MC in in vitro ruminal fermentation. Furthermore, the detachment of R. albus was more sensitive to MC than was R. flavefaciens. These results showed the certain evidence that attachment of major fibrolytic bacteria had an effect on fiber digestion in the rumen, and each of fibrolytic bacteria, F. succinogenes, R. flavefaciens and R. albus had a specific mechanism of attachment and detachment to fiber.

  15. Effects of Methylcellulose on Fibrolytic Bacterial Detachment and In vitro Degradation of Rice Straw

    PubMed Central

    Kim, Min Ji; Sung, Ha Guyn; Upadhaya, Santi Devi; Ha, Jong K.; Lee, Sung Sill

    2013-01-01

    Two in vitro experiments were conducted to evaluate the effect of methylcellulose (MC) on i) bacterial detachment from rice straw as well as ii) inhibition of bacterial attachment and fiber digestibility. To evaluate the effect of MC on fibrolytic bacterial detachment (Exp 1), in vitro bacterial cultures with 0.1% (w/v) MC solution were compared with cultures without MC after 8 h incubation. The effect of MC on inhibition of bacterial attachment was determined by comparing with real-time PCR the populations of F. succinogenes, R. flavefaciens and R. albus established on rice straw pre-treated with 0.1% MC with those on untreated straw after incubation for 0, 6 and 12 h (Exp 2). The major fibrolytic bacterial attachment on rice straw showed significantly lower populations with either the addition of MC to the culture or pre-treated rice straw compared to controls (p<0.05). Also, the digestibility of rice straw with MC was significantly lower compared with control (p<0.05). The F. succinogenes population did not show detachment from rice straw, but showed an inhibition of attachment and proliferation on rice straw in accordance with a decrease of fiber digestion. The detachments of Ruminococcus species co-existed preventing the proliferations with subsequent reduction of fiber degradation by MC during the incubation. Their detachments were induced from stable colonization as well as the initial adhesion on rice straw by MC in in vitro ruminal fermentation. Furthermore, the detachment of R. albus was more sensitive to MC than was R. flavefaciens. These results showed the certain evidence that attachment of major fibrolytic bacteria had an effect on fiber digestion in the rumen, and each of fibrolytic bacteria, F. succinogenes, R. flavefaciens and R. albus had a specific mechanism of attachment and detachment to fiber. PMID:25049729

  16. Supplementation of diets containing pea meal with exogenous enzymes: effects on weight gain, feed conversion, nutrient digestibility and gross morphology of the gastrointestinal tract of growing broiler chicks.

    PubMed

    Cowieson, A J; Acamovic, T; Bedford, M R

    2003-07-01

    1. The potential for the nutritional improvement of pea-based diets by supplementation with a cocktail of exogenous carbohydrases was investigated using growing broiler chicks. 2. Pea meals (grown in the UK) were included in wheat-based diets at 300 g/kg as a partial replacement for an approximately isonitrogenous mixture of wheat and soybean meal. A wheat/soybean meal diet served as a control and each diet was supplemented with a cocktail of alpha-amylase, pectinase and cellulase. The diets were fed to 1-d-old broiler chicks for a period of 21 d. Weight gain and feed conversion were monitored weekly and excreta were collected during the final week in order to determine nutrient digestibility coefficients and metabolisable energy. On d 21, the gastrointestinal (GI) tract was excised and gross morphology measured. 3. Inclusion of pea meal reduced weight gain, feed conversion, nutrient digestibility and also increased the relative sizes of the distal sections of the GI tract. 4. Enzyme addition partially ameliorated the detrimental effects of pea meal inclusion although similar improvements were also noted for birds fed on the control diet. 5. It is concluded that the nutritive value of pea-meal-based diets can be improved by the addition of carbohydrases, and that some pea cultivars show considerable potential as vegetable protein sources for broiler chicks.

  17. Exogenous application of nitric oxide modulates osmolyte metabolism, antioxidants, enzymes of ascorbate-glutathione cycle and promotes growth under cadmium stress in tomato.

    PubMed

    Ahmad, Parvaiz; Ahanger, Mohammed Abass; Alyemeni, Mohammed Nasser; Wijaya, Leonard; Alam, Pravej

    2017-06-22

    Experiments were carried out to investigate the role of nitric oxide (NO) in ameliorating the negative effects of cadmium stress in tomato seedlings. Plants treated with cadmium (CdCl2, 150 μM) showed reduced growth, biomass yield, pigment content, chlorophyll fluorescence, and gas exchange parameters. Exogenous application of NO donor (sodium nitroprusside) with nutrient solution protected chlorophyll pigments, restored chlorophyll fluorescence and gas exchange parameters, and caused significant enhancements in growth and biomass yield. Cadmium triggered the synthesis of proline and glycine betaine; however, application of NO caused further enhancement of their accumulation, reflecting an obvious amelioration of the cadmium-induced decline in relative water content. Activities of the antioxidant enzymes superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase, monodehydroascorbate reductase, dehydroascorbate reductase, and other enzymatic activities of ascorbate-glutathione cycle were enhanced following the application of NO, as compared with those in untreated seedlings under control and cadmium stress conditions. NO increased the flavonoid and total phenol content in Cd-stressed tomato plants. Moreover, NO application restricted the uptake of cadmium and enhanced the accumulation of nutrients in different parts of tomato plants. On the basis of the findings of the present study, we propose that NO has a potential role as a growth promoter for tomato under cadmium stress.

  18. [Alleviated affect of exogenous CaCl2 on the growth, antioxidative enzyme activities and cadmium absorption efficiency of Wedelia trilobata hairy roots under cadmium stress].

    PubMed

    Shi, Heping; Wang, Yunling; Tsang, PoKeung Eric; Chan, LeeWah Andrew

    2012-06-01

    In order to study the physiological mechanism of exogenous calcium on the toxicity of heavy metal cadmium (Cd) to Wedelia trilobata hairy roots, the effects of Cd alone, and in combination with different concentrations of Ca on growth, contents of soluble protein and malondialdehyde (MDA), activities of superoxide dismutase (SOD) and peroxidase (POD), Cd2+ absorption in W. trilobata hairy roots were investigated. Cd concentrations lower than 50 micromol/L enhanced the growth of hairy roots, while concentrations higher than 100 micromol/L inhibited growth, making the branched roots short and small, and also turning the root tips brown, even black. In comparison with the control (0 micromol/L Cd), the soluble protein content in hairy roots was found to increase when cultured with 10-50 micromol/L Cd, and decrease when exposed to a cadmium concentration higher than 100 micromol/L Cd. In addition, the activities of POD and SOD activity and MDA content were significantly higher than the control. Compared to the control (hairy roots cultured without 10-30 mmol/L Ca), 100 micromol/L Cd or 300 micromol/L Cd in combination with 10-30 mmol/L Ca resulted in increased growth, causing the main root and secondary roots thicker and also an increase in soluble protein content. On the contrary, MDA content and POD and SOD activities decreased. Quantitative analysis by Atomic Absorption Spectrophotometry showed that W. trilobata hairy roots can absorb and adsorb heavy metal Cd in the ionic form of Cd2+. The maximum content of Cd2+ absorbed by the hairy roots was obtained with a concentration 100 micromol/L Cd2+ while that of Cd2+ adsorbed by hairy roots was achieved with a concentration of 300 micromol/L Cd2+. The exogenous addition of 10-30 mmol/L Ca2+ was found to reduce the absorption, adsorption of Cd2+ and the toxicity of Cd significantly. This reduction in toxicity was caused by the reduction in the absorption of Cd and decreasing the lipid peroxidation through regulating the

  19. Exogenous Ochronosis.

    PubMed

    Bhattar, Prachi A; Zawar, Vijay P; Godse, Kiran V; Patil, Sharmila P; Nadkarni, Nitin J; Gautam, Manjyot M

    2015-01-01

    Exogenous ochronosis (EO) is a cutaneous disorder characterized by blue-black pigmentation resulting as a complication of long-term application of skin-lightening creams containing hydroquinone but may also occur due to topical contact with phenol or resorcinol in dark-skinned individuals. It can also occur following the use of systemic antimalarials such as quinine. EO is clinically and histologically similar to its endogenous counterpart viz., alkaptonuria, which, however, exhibits systemic effects and is an inherited disorder. Dermoscopy and in vivo skin reflectance confocal microscopy are noninvasive in vivo diagnostic tools. It is very difficult to treat EO, a cosmetically disfiguring and troubling disorder with disappointing treatment options.

  20. Enzyme

    MedlinePlus

    Enzymes are complex proteins that cause a specific chemical change in all parts of the body. For ... use them. Blood clotting is another example of enzymes at work. Enzymes are needed for all body ...

  1. Exogenous Ochronosis

    PubMed Central

    Bhattar, Prachi A; Zawar, Vijay P; Godse, Kiran V; Patil, Sharmila P; Nadkarni, Nitin J; Gautam, Manjyot M

    2015-01-01

    Exogenous ochronosis (EO) is a cutaneous disorder characterized by blue-black pigmentation resulting as a complication of long-term application of skin-lightening creams containing hydroquinone but may also occur due to topical contact with phenol or resorcinol in dark-skinned individuals. It can also occur following the use of systemic antimalarials such as quinine. EO is clinically and histologically similar to its endogenous counterpart viz., alkaptonuria, which, however, exhibits systemic effects and is an inherited disorder. Dermoscopy and in vivo skin reflectance confocal microscopy are noninvasive in vivo diagnostic tools. It is very difficult to treat EO, a cosmetically disfiguring and troubling disorder with disappointing treatment options. PMID:26677264

  2. Detection and identification of rumen bacteria constituting a fibrolytic consortium dominated by Fibrobacter succinogenes.

    PubMed

    Shinkai, Takumi; Ueki, Takaaki; Kobayashi, Yasuo

    2010-02-01

    A fibrolytic consortium, dominated by the rumen cellulolytic bacterium Fibrobacter succinogenes, was artificially constructed on hay stems to detect and identify rumen bacteria that can potentially interact with F. succinogenes. Consortium-bacterial members were determined by DGGE and sequencing analysis targeted bacterial 16S rDNA. An artificial consortium was formed in a 2-step incubation of hay stems; the first step with group 1, 2 or 3 F. succinogenes strains, the second step with rumen fluid. After consortium formation, morphologically different bacteria were observed in association with F. succinogenes. DGGE exhibited more than 30 bands, the pattern of which depended on the F. succinogenes group. Sequencing suggested that Butyrivibrio fibrisolvens, Pseudobutyrivibrio ruminis, Clostridium sp., F. succinogenes group 2, Prevotella ruminicola and unclassified Bacteroides were prominent in the group 1 consortium and that Treponema bryantii, B. fibrisolvens, Acinetobacter sp, and Wolinella succinogenes were prominent in the group 2 consortium. However, in the group 3 consortium, F. succinogenes-like bacteria were microscopically undetectable, whereas cellulolytic Ruminococcus albus and F. succinogenes group 1 were prominent, suggesting that the group 3 cannot be a core member of this consortium. This study is the first attempt to identify bacterial members of a fibrolytic consortium dominated by a specific bacterium.

  3. H.p.l.c. of oligo(sialic acids). Application to the determination of the minimal chain length serving as exogenous acceptor in the enzymic synthesis of colominic acid.

    PubMed

    Ferrero, M A; Luengo, J M; Reglero, A

    1991-12-15

    A rapid, sensitive and easy h.p.l.c. method was developed for the quantitative analysis of oligosialic acids. This procedure which permits the complete separation (in 23 min) of several sialyloligomers with a degree of polymerization of between 1 and 16, has been employed to establish the minimal chain length of oligomer accepted, as an exogenous acceptor, by Escherichia coli K-235 sialytransferase complex (ST) leading to the synthesis in vitro of colominic acid. We showed that this membrane-bound enzyme catalyses the direct transfer of Neu5Ac residues (one by one) from CMP-Neu5Ac to an exogenous acceptor molecule which contains at least three Neu5Ac residues. Free Neu5Ac or (Neu5Ac)2 were not recognized as substrates, whereas the maximal rate of polymer elongation was achieved when (Neu5Ac)5 was used as substrate.

  4. H.p.l.c. of oligo(sialic acids). Application to the determination of the minimal chain length serving as exogenous acceptor in the enzymic synthesis of colominic acid.

    PubMed Central

    Ferrero, M A; Luengo, J M; Reglero, A

    1991-01-01

    A rapid, sensitive and easy h.p.l.c. method was developed for the quantitative analysis of oligosialic acids. This procedure which permits the complete separation (in 23 min) of several sialyloligomers with a degree of polymerization of between 1 and 16, has been employed to establish the minimal chain length of oligomer accepted, as an exogenous acceptor, by Escherichia coli K-235 sialytransferase complex (ST) leading to the synthesis in vitro of colominic acid. We showed that this membrane-bound enzyme catalyses the direct transfer of Neu5Ac residues (one by one) from CMP-Neu5Ac to an exogenous acceptor molecule which contains at least three Neu5Ac residues. Free Neu5Ac or (Neu5Ac)2 were not recognized as substrates, whereas the maximal rate of polymer elongation was achieved when (Neu5Ac)5 was used as substrate. PMID:1764020

  5. Exogenous proteases for meat tenderization.

    PubMed

    Bekhit, Alaa A; Hopkins, David L; Geesink, Geert; Bekhit, Adnan A; Franks, Philip

    2014-01-01

    The use of exogenous proteases to improve meat tenderness has attracted much interest recently, with a view to consistent production of tender meat and added value to lower grade meat cuts. This review discusses the sources, characteristics, and use of exogenous proteases in meat tenderization to highlight the specificity of the proteases toward meat proteins and their impact on meat quality. Plant enzymes (such as papain, bromelain, and ficin) have been extensively investigated as meat tenderizers. New plant proteases (actinidin and zingibain) and microbial enzyme preparations have been of recent interest due to controlled meat tenderization and other advantages. Successful use of these enzymes in fresh meat requires their enzymatic kinetics and characteristics to be determined, together with an understanding of the impact of the surrounding environmental conditions of the meat (pH, temperature) on enzyme function. This enables the optimal conditions for tenderizing fresh meat to be established, and the elimination or reduction of any negative impacts on other quality attributes.

  6. Influence of forage phenolics on ruminal fibrolytic bacteria and in vitro fiber degradation.

    PubMed

    Varel, V H; Jung, H J

    1986-08-01

    In vitro cultures of ruminal microorganisms were used to determine the effect of cinnamic acid and vanillin on the digestibility of cellulose and xylan. Cinnamic acid and vanillin depressed in vitro dry matter disappearance of cellulose 14 and 49%, respectively, when rumen fluid was the inoculum. The number of viable Bacteroides succinogenes cells, the predominant cellulolytic organism, was threefold higher for fermentations which contained vanillin than for control fermentations. When xylan replaced cellulose as the substrate, a 14% decrease in the digestibility of xylan was observed with vanillin added; however, the number of viable xylanolytic bacteria cultured from the batch fermentation was 10-fold greater than that of control fermentations. The doubling time of B. succinogenes was increased from 2.32 to 2.58 h when vanillin was added to cellobiose medium, and absorbance was one-half that of controls after 18 h. The growth rate of Ruminococcus albus and Ruminococcus flavefaciens was inhibited more by p-coumaric acid than by vanillin, although no reduction of final absorbance was observed in their growth cycles. Vanillin, and to a lesser extent cinnamic acid, appeared to prevent the attachment of B. succinogenes cells to cellulose particles, but did not affect dissociation of cells from the particles. B. succinogenes, R. albus, R. flavefaciens, and Butyrivibrio fibrisolvens all modified the parent monomers cinnamic acid, p-coumaric acid, ferulic acid, and vanillin, with B. fibrisolvens causing the most extensive modification. These results suggest that phenolic monomers can inhibit digestibility of cellulose and xylan, possibly by influencing attachment of the fibrolytic microorganisms to fiber particles. The reduced bacterial attachment to structural carbohydrates in the presence of vanillin may generate more free-floating fibrolytic organisms, thus giving a deceptively higher viable count.

  7. The efficacy of using exogenous enzymes cocktail on production, egg quality, egg nutrients and blood metabolites of laying hens fed distiller's dried grains with solubles.

    PubMed

    Abd El-Hack, M E; Chaudhry, M T; Mahrose, K M; Noreldin, A; Emam, M; Alagawany, M

    2017-10-08

    An experiment was performed using 120 Hisex Brown laying hens for evaluating the effects of different inclusion levels of corn distiller's dried grains with solubles (DDGS) as a replacement of soybean meal (SBM) with or without enzyme cocktail on performance, egg quality, egg nutrients and blood metabolites in laying hens through 22-42 weeks of age. A 4 × 2 factorial design experiment was performed including four substitution levels of DDGS (0, 250, 500 and 750 g/kg respectively) and two enzyme cocktail levels (0 and 250 mg/kg diet). The used enzyme in this study "Gallazyme" composed of xylanase, Trichoderma longibrachiatum (600 units/g), protease, Bacillus subtilis (8,000 units/g) and amylase and Bacillus amyloliquofaciens (800 units/g). The control diet showed the best feed efficiency followed by the intermediate levels of DDGS. The lowest value of feed efficiency was found in the group fed the highest level of DDGS. Enzyme addition improved feed efficiency and decreased laying rate. Increasing DDGS levels was associated with albumin and shell thickness increases. Dietary DDGS depressed all egg components except the organic matter which maximised in enzyme-treated groups. Increasing DDGS level was accompanied by increase in yolk cholesterol and total lipids. No significant impacts were detected with enzymes supplementation on yolk lipids profile. Excepting serum calcium and phosphorous, all serum constituents increased with increasing level of DDGS. Using enzyme markedly depressed serum ammonia by 15.02% and increased calcium by 6.44% compared with enzyme-free diets. Interaction between DDGS and enzyme was significant on most of studied parameters. It could be concluded that using enzyme cocktail in DDGS-based diets may improve feed efficiency and egg quality, in addition to lowering blood ammonia and increasing blood calcium. It is recommended to substitute SBM by DDGS up to 500 g/kg diet. © 2017 Blackwell Verlag GmbH.

  8. Short communication: The effect of an exogenous enzyme with amylolytic activity on gas production and in vitro rumen starch degradability of small and large particles of corn or barley meals.

    PubMed

    Gallo, A; Giuberti, G; Duval, S; Moschini, M; Masoero, F

    2016-05-01

    The objective of this study was to evaluate the effect of exogenous amylase supplementation on gas production and on in vitro rumen starch degradability (IVSD) of different sized particles of corn and barley meals (Cm and Bm, respectively). An aqueous liquid amylase formulation from Bacillus licheniformis was tested at 3 enzyme doses (EnzD; 0, 300 and 1,500 kilo novo units/kg of dry matter) on small (<750 µm) and large (≥750 µm) particle size (PS) of Cm and Bm. Data were analyzed according to a randomized complete block design with a factorial arrangement of treatments; the main tested effects were PS, EnzD, and their interaction. Fermentation run entered in the model as random effect. The mixed rumen fluid was collected from 2 rumen-fistulated Holstein dry dairy cows fed at maintenance (forage:concentrate ratio of 80:20; 12% crude protein; 55% amylase-treated neutral detergent fiber). Small particles of both Cm and Bm had a greater rate of fermentation and shorter lag time than large particles. The rate of starch degradation was greater for small than for large particles of Bm, being 0.187 and 0.125 1/h, respectively. Conversely, the rate of starch degradation of Cm averaged 0.063 1/h and was similar among treatments. Enzyme supplementation tended to reduce lag time and to increase rate of fermentation for both PS of Cm and Bm, with a more pronounced effect for small PS. A limited EnzD effect was measured for IVSD data and rate of starch degradation; PS influenced fermentation parameters and the magnitude of starch degradation more than EnzD. Supplementation with exogenous amylase influenced the rumen fermentation pattern of small and large PS of Cm and Bm, even if the effect of the enzyme supplementation differed according to the PS of cereal meals.

  9. Human T cell microparticles circulate in blood of hepatitis patients and induce fibrolytic activation of hepatic stellate cells

    PubMed Central

    Kornek, Miroslaw; Popov, Yury; Libermann, Towia A.; Afdhal, Nezam H.; Schuppan, Detlef

    2010-01-01

    Microparticles (MP) are small cell membrane vesicles which are released from cells during apoptosis or activation. While circulating platelet MP have been studied in some detail, the existence and functional role of T cell MP remain elusive. We show that blood from patients with active hepatitis C (ALT>100 IU/ml) contains elevated numbers of T cell MP compared to patients with mild hepatitis C (ALT<40 IU/ml) and healthy controls. T cell MP fuse with cell membranes of hepatic stellate cells (HSC), the major effector cells for excess matrix deposition in liver fibrosis and cirrhosis. MP uptake is partly ICAM-1 dependent and leads to activation of NFkB and ERK1/2 and subsequent upregulation of fibrolytic genes in HSC, to downregulation of procollagen α1(I) mRNA, and blunting of profibrogenic activities of TGFβ1. Ex vivo the induced fibrolytic activity is evident in MP derived from activated CD4+ T cells, and highest with MP from activated and apoptotic CD8+ T cells. Mass spectrometry, FACS analysis and function blocking antibodies revealed CD147/Emmprin as candidate transmembrane molecule in HSC fibrolytic activation by CD8+ T cell MP. We conclude that 1) circulating T cell MP are a novel diagnostic marker for inflammatory liver diseases, and 2) in vivo induction of T cell MP may be a novel strategy to induce regression of liver fibrosis. PMID:20979056

  10. Stunting syndrome in broilers: effect of age and exogenous amylase and protease on performance, development of the digestive tract, digestive enzyme activity, and apparent digestibility.

    PubMed

    Shapiro, F; Nir, I

    1995-12-01

    Day-old male, meat-type chicks raised in brooder batteries were infected by orally administering an inoculum prepared from intestines of broiler chicks infected with stunting syndrome (SS). Naive controls were kept in a parallel room. The chicks were fed a commercial starter diet supplemented with two levels of enzyme preparations to 14 d of age. The experiment was continued to the age of 6 wk in order to estimate compensatory feed intake and growth. In a parallel study, digestibility of the feed was determined from 1 to 3 wk of age with control or inoculated chicks. The enzymes amylase and proteases were produced by Bacillus subtilis and Penicillium emersonii. Enzyme supplementation had no effect on feed intake, growth, or feed utilization, or on digestibility of fat, starch, protein, or energy. Because enzyme supplementation did not consistently affect performance of chicks and no interactions were observed between enzyme supplementation and infection status, data are presented for effects of infection only. Inoculation of SS-infective material reduced performance to 4 wk. Compensatory growth and feed intake were observed from the age of 4 wk onward. At the age of 6 wk the slight retardation of the inoculated chicks was not significant. On Week 1, retention of fat, starch, protein, and energy was significantly depressed in the inoculated chicks. At the age of 2 wk, retention of starch was not depressed, and at the age of 3 wk, the only consistent depression was that observed for fat. The proventriculus weight and content were consistently higher in inoculated chicks, as were the small intestine and intestinal content. The pH of the gizzard content was higher, and that of the small intestine content was lower, in the inoculated birds than in their control counterparts. Stunting syndrome infection was accompanied by a significant depression of trypsin activity in the pancreas at the age of 1 and 2 wk. At these periods, amylase and chymotrypsin were not affected. At

  11. Influence of canola meal-based diets supplemented with exogenous enzyme and digestible lysine on performance, digestibility, carcass, and immunity responses of broiler chickens.

    PubMed

    Mushtaq, T; Sarwar, M; Ahmad, G; Mirza, M A; Nawaz, H; Mushtaq, M M Haroon; Noreen, U

    2007-10-01

    The response of broiler chickens to 2 levels of endo-1,4-beta xylanase and endo-1,3-beta glucanase combination (with and without), 3 levels of digestible Lys (0.8, 0.9, and 1.0%), and 2 levels of canola meal (CM; 20 and 30%) were evaluated in 2 x 3 x 2 factorial arrangement. A total of 2,448 male Hubbard broiler chicks were fed on practical mash diets having 2,750 kcal of ME.kg(-1) and 19.6% CP from 1 to 42 d of age. The BW gain was significantly reduced when 30% CM was added in the diets during 1 to 21 d. Feed:gain and mortality were also observed to be high. No significant effect of enzyme addition or Lys level was observed on feed intake, BW gain, feed:gain, and mortality during the starter phase. When the data were pooled for 42 d, BW gain and feed:gain were unaffected by enzyme addition or Lys levels. A depression in breast weight was observed due to 30% CM or 0.8 and 0.9% digestible Lys at 43 d. Leg weights were significantly depressed by enzyme addition or increasing digestible Lys to 1.0% of the diets. The AME, nitrogen digestibility, and antibody titers against Newcastle and infectious bursal diseases were also unaffected by the dietary treatments. In conclusion, the 30% CM is not recommended in broiler diets especially during starter phase (1 to 21 d). However, the CM may be used up to 30% of the diets during finishing phase. The digestible Lys can be lowered to 0.8% when amino acids in proportion to digestible Lys follow the ideal AA ratio. The glucanase and xylanase cocktail have no pronounced effect on the growth performance, nutrient digestibility, and carcass characteristics.

  12. Characterization of fibrolytic and lipid accumulating fungi isolated from fresh cattle feces.

    PubMed

    Liu, Yupei; Tan, Hongming; Deng, Qingli; Cao, Lixiang

    2014-01-01

    To characterize coprophilous fungi for converting lignocellulose into lipids, four fungal strains utilizing cellulose microcrystalline and xylan were screened. The fungi were identified as Cladosporium sp. F1, Circinella sp. F6, Mycocladus sp. F49, and Byssochlamys sp. F52 based on the ITS1-5.8S-ITS2 sequence similarity. The strain F52 accumulated 336.0 mg/L reducing sugars on cottonseed shells treated with ethanol. The combination of F1+F52 increased the reducing sugar accumulating rates. However, the activities of avicelase and xylanase were not correlated with the reducing sugars accumulated by the test strains. Strains F6 and F52 produced higher cellular lipids (above 530.7 mg/L) than other strains. However, the strain F52 could produce more cellular lipids with xylose and mannose as the sole carbon sources. The results indicated that the reducing sugar contents accumulated by the different strains were influenced by the fungal taxa and ligocellulosic types. With fibrolytic and lipid accumulating activities, diverse fungi harboring in herbivore feces need to be further characterized.

  13. Modulation of GSH with exogenous agents leads to changes in glyoxalase 1 enzyme activity in VL-17A cells exposed to chronic alcohol plus high glucose.

    PubMed

    Kumar, S Mathan; Swaminathan, Kavitha; Clemens, Dahn L; Dey, Aparajita

    2014-02-01

    Gluthathione (GSH) is a major cellular antioxidant. The present study utilizing VL-17A cells exposed to chronic alcohol plus high glucose investigated the changes in oxidative stress, toxicity, and glyoxalase 1 activity as a detoxification pathway due to changes in GSH level through GSH supplementation with N-acetyl cysteine (NAC) or ursodeoxycholic acid (UDCA) and its depletion through buthionine sulfoximine (BSO) or diethyl maleate (DEM). Glyoxalase 1 plays an important role in detoxification of methylglyoxal which is formed as a precursor of advanced glycated end products formed due to high glucose mediated oxidative stress. Significant changes in glyoxalase 1 activity utilizing methylglyoxal or glyoxal as substrates occurred with NAC or UDCA or BSO or DEM supplementation in chronic alcohol plus high glucose treated VL-17A cells. NAC or UDCA administration in chronic alcohol plus high glucose treated VL-17A cells increased viability and decreased ROS levels, lipid peroxidation and 3-nitrotyrosine adduct formation. Similarly, GSH depletion with BSO or DEM had an opposite effect on the parameters in chronic alcohol plus high glucose treated VL-17A cells. In conclusion, modulation of GSH with NAC or UDCA or BSO or DEM leads to significant changes in oxidative stress, glyoxalase 1 enzyme activity and toxicity in chronic alcohol plus high glucose treated VL-17A cells.

  14. The role of endogenous and exogenous enzymes in chronic wounds: a focus on the implications of aberrant levels of both host and bacterial proteases in wound healing.

    PubMed

    McCarty, Sara M; Cochrane, Christine A; Clegg, Peter D; Percival, Steven L

    2012-01-01

    Cutaneous wound healing is orchestrated by a number of physiological pathways that ultimately lead to reformation of skin integrity and the production of functional scar tissue. The remodeling of a wound is significantly affected by matrix metalloproteinases (MMPs), which act to control the degradation of the extracellular matrix (ECM). Regulation of MMPs is imperative for wound healing as excessive levels of MMPs can lead to disproportionate destruction of the wound ECM compared to ECM deposition. In addition to human MMPs, bacterial proteases have been found to be influential in tissue breakdown and, as such, have a role to play in the healing of infected wounds. For example, the zinc-metalloproteinase, elastase, produced by Pseudomonas aeruginosa, induces degradation of fibroblast proteins and proteoglycans in chronic wounds and has also been shown to degrade host immune cell mediators. Microbial extracellular enzymes have also been shown to degrade human wound fluid and inhibit fibroblast cell growth. It is now being acknowledged that host and bacterial MMPs may act synergistically to cause tissue breakdown within the wound bed. Several studies have suggested that bacterial-derived secreted proteases may act to up-regulate the levels of MMPs produced by the host cells. Together, these findings indicate that bacterial phenotype in terms of protease producing potential of bacteria should be taken into consideration during diagnostic and clinical intervention of infected wound management. Furthermore, both host MMPs and those derived from infecting bacteria need to be targeted in order to increase the healing capacity of the injured tissue. The aim of this review is to investigate the evidence suggestive of a relationship between unregulated levels of both host and bacterial proteases and delayed wound healing. © 2012 by the Wound Healing Society.

  15. Effect of beta-glucans contained in barley- and oat-based diets and exogenous enzyme supplementation on gastrointestinal fermentation of finisher pigs and subsequent manure odor and ammonia emissions.

    PubMed

    O'Shea, C J; Sweeney, T; Lynch, M B; Gahan, D A; Callan, J J; O'Doherty, J V

    2010-04-01

    The objective of the current experiment was to evaluate the influence of dietary cereal sources of beta(1,3)(1,4)-d-glucan (beta-glucan) and enzyme supplementation on indices of environmental pollution from finisher pigs. An experiment with a 2 x 2 factorial arrangement of treatments was initiated to investigate the effect of dietary source of beta-glucan (barley vs. oats) and enzyme supplementation (no vs. yes) on nutrient digestibility, N utilization, intestinal fermentation, and manure odor and ammonia emissions from finisher boars (n = 4; BW = 73.9 kg; SD = 4.7). Sixteen boars were assigned to 1 of 4 dietary treatments (n = 4/treatment): 1) barley-based diet, 2) barley-based diet + exogenous enzyme, 3) oat-based diet, and 4) oat-based diet + enzyme. The enzyme supplement used contained endo-1,3(4)-beta-glucanase and endo-1,4-beta-xylanase. Experimental diets were formulated to contain similar concentrations of DE (13.5 MJ/kg) and digestible lysine (8.8 g/kg). Pigs offered oat-based diets had reduced digestibility of DM (0.795 vs. 0.849; SEM 0.007; P = 0.001), OM (0.808 vs. 0.865; SEM 0.007; P = 0.001), GE (0.806 vs. 0.845; SEM 0.006; P = 0.002), and NDF (0.233 vs. 0.423; SEM 0.033; P < 0.003) compared with those offered barley-based diets. Oat-based diets increased populations of Bifidobacterium spp. (7.26 vs. 6.38 log cfu/g of digesta; SEM 0.201; P = 0.005) and Lactobacillus spp. (6.99 vs. 6.18 log cfu/g of digesta; SEM 0.234; P = 0.022) in the proximal colon and decreased manure odor emissions [2,179.6 vs. 4,984.6 Ou(E)/m(3) (where Ou(E) refers to European odor units); SEM 653.7; P < 0.011] compared with barley-based diets. There was an interaction between cereal type and enzyme inclusion on manure ammonia emissions from 0 to 96 h (P = 0.050). Pigs offered barley-based diets containing an enzyme supplement had increased manure ammonia emissions compared with those offered unsupplemented barley-based diets. However, there was no effect of enzyme inclusion on

  16. Cereal supplementation modified the fibrolytic activity but not the structure of the cellulolytic bacterial community associated with rumen solid digesta.

    PubMed

    Martin, C; Millet, L; Fonty, G; Michalet-Doreau, B

    2001-01-01

    4 ruminally cannulated cows were fed a forage diet (93% hay + 7% straw) and a mixed diet (33 % hay + 7% straw + 40% barley) in a 2 x 2 crossover experimental design. In sacco degradation of forage, fibrolytic activities (polysaccharidases and glycosidases) of the solid-associated bacteria (SAB), and distribution of the 3 main cellulolytic bacterial species (Fibrobacter succinogenes, Ruminococcus albus, Ruminococcus flavefaciens) were determined for both diets. Barley supplementation decreased the hay degradation rate and mainly the polysaccharidase activities of the SAB (30% on average). The sum of rRNA of the 3 cellulolytic bacterial species represented on average 17% of the total bacterial signal and R. albus was the dominant cellulolytic bacterial species of the 3 studied. Barley supplementation did not modify the proportion of the 3 cellulolytic bacteria attached to plant particles. The negative effect of barley on the ruminal hay degradation rate is due to a decrease in fibrolytic activity of the SAB, and not to a modification of the balance of the three cellulolytic bacterial species examined.

  17. Presence of Selected Methanogens, Fibrolytic Bacteria, and Proteobacteria in the Gastrointestinal Tract of Neonatal Dairy Calves from Birth to 72 Hours

    PubMed Central

    Guzman, Cesar E.; Bereza-Malcolm, Lara T.; De Groef, Bert; Franks, Ashley E.

    2015-01-01

    The microbial communities in the gastrointestinal tract of a young calf are essential for the anatomical and physiological development that permits a transition from milk to solid feed. Selected methanogens, fibrolytic bacteria, and proteobacteria were quantified in the rumen fluid and tissue, abomasum fluid, cecum fluid and tissue, and feces of Holstein bull calves on day 0 (0–20 mins after birth), day 1 (24 ± 1 h after birth), day 2 (48 ± 1 h after birth), and day 3 (72 ± 1 h after birth). Methanogens, fibrolytic bacteria, and Geobacter spp. were found to be already present from birth, indicating that microbial colonization of the gastrointestinal tract occurred before or during delivery. The abundance of methanogens and Geobacter spp. differed between the days tested and between compartments of the digestive tract and feces, but such difference was not observed for fibrolytic bacteria. Our findings suggests that methanogens might have an alternative hydrogen provider such as Geobacter spp. during these early stages of postnatal development. In addition, fibrolytic bacteria were present in the rumen well before the availability of fibrous substrates, suggesting that they might use nutrients other than cellulose and hemicellose. PMID:26186002

  18. The rumen: a unique source of enzymes for enhancing livestock production.

    PubMed

    Selinger, L B; Forsberg, C W; Cheng, K J

    1996-10-01

    Increasing competition in the livestock industry has forced producers to cut costs by adopting new technologies aimed at increasing production efficiency. One particularly promising technology is feeding enzymes as supplements for animal diets. Supplementation of diets for non-ruminants (e.g., swine and poultry) with fibrolytic enzymes, such as cellulases, xylanases and beta-glucanases, increases the feed conversion efficiency and growth rate of the animals. Enzymatic hydrolysis of plant cell wall polymers (e.g., cellulose, xylan, beta-glucans) releases glucose and xylose and eliminates the antinutritional effects of beta-glucans and arabinoxylans. Enzyme supplementation of diets for ruminants has also been shown to improve growth performance, even though the rumen itself represents the most potent fibrolytic fermentation system known. Implementation of this technology in the livestock industry has been limited largely because of the cost of development and production of enzymes. Over the last decade, however, developments in recombinant DNA technology have increased the efficiency of existing microbial production systems and facilitated exploitation of alternative sources of industrial enzymes. The ruminal ecosystem is among the novel enzyme sources currently being explored. Understanding the role of enzymes in feed digestion through characterization of the enzymology and genetics involved in digestion of feedstuffs by ruminants will provide insight required to improve the products currently available to producers. Characterization of genes encoding a variety of hydrolytic enzymes, such as cellulases, xylanases, beta-glucanases, amylases, pectinases, proteases, phytases and tannases, will foster the development of more efficacious enzyme supplements and enzyme expression systems for enhancing nutrient utilization by domestic animals. Characteristics of the original source organism need no longer restrict the production of a useful enzyme. Recent reports of

  19. Exploring the sheep rumen microbiome for carbohydrate-active enzymes.

    PubMed

    Lopes, Lucas Dantas; de Souza Lima, André Oliveira; Taketani, Rodrigo Gouvêa; Darias, Phillip; da Silva, Lília Raquel Fé; Romagnoli, Emiliana Manesco; Louvandini, Helder; Abdalla, Adibe Luiz; Mendes, Rodrigo

    2015-07-01

    The rumen is a complex ecosystem enriched for microorganisms able to degrade biomass during the animal's digestion process. The recovery of new enzymes from naturally evolved biomass-degrading microbial communities is a promising strategy to overcome the inefficient enzymatic plant destruction in industrial production of biofuels. In this context, this study aimed to describe the bacterial composition and functions in the sheep rumen microbiome, focusing on carbohydrate-active enzymes (CAE). Here, we used phylogenetic profiling analysis (inventory of 16S rRNA genes) combined with metagenomics to access the rumen microbiome of four sheep and explore its potential to identify fibrolytic enzymes. The bacterial community was dominated by Bacteroidetes and Firmicutes, followed by Proteobacteria. As observed for other ruminants, Prevotella was the dominant genus in the microbiome, comprising more than 30 % of the total bacterial community. Multivariate analysis of the phylogenetic profiling data and chemical parameters showed a positive correlation between the abundance of Prevotellaceae (Bacteroidetes phylum) and organic matter degradability. A negative correlation was observed between Succinivibrionaceae (Proteobacteria phylum) and methane production. An average of 2 % of the shotgun metagenomic reads was assigned to putative CAE when considering nine protein databases. In addition, assembled contigs allowed recognition of 67 putative partial CAE (NCBI-Refseq) representing 12 glycosyl hydrolase families (Pfam database). Overall, we identified a total of 28 lignocellulases, 22 amylases and 9 other putative CAE, showing the sheep rumen microbiome as a promising source of new fibrolytic enzymes.

  20. Effect of non-starch-polysaccharide-degrading enzymes as feed additive on the rumen bacterial population in non-lactating cows quantified by real-time PCR.

    PubMed

    Zeitz, J O; Guertler, P; Pfaffl, M W; Eisenreich, R; Wiedemann, S; Schwarz, F J

    2013-12-01

    The effects of non-starch-polysaccharide-degrading enzymes, added to a maize silage- and grass silage-based total mixed ration (TMR) at least 14 h before feeding, on the rumen bacterial population were investigated. Six non-lactating Holstein Friesian cows were allocated to three treatment groups using a duplicate 3 × 3 Latin square design with three 31-day periods (29 days of adaptation and 2 days of sampling). Treatments were control TMR [69% forage and 31% concentrates on a dry matter (DM) basis] or TMR with 13.8 or 27.7 ml/kg of feed DM of Roxazyme G2 liquid with activities (U/ml enzyme preparation) of xylanase 260 000, β-glucanase 180 000 and cellulase 8000 (DSM Nutritional Products, Basel, Switzerland). The concentrations of 16S rDNA of Anaerovibrio lipolytica, Fibrobacter succinogenes, Prevotella ruminicola, Ruminococcus flavefaciens, Selenomonas ruminantium and Treponema bryantii, and their relative percentage of total bacteria in rumen samples obtained before feeding and 3 and 7 h after feeding and from two rumen fractions were determined using real-time PCR. Sampling time had only little influence, but bacterial numbers and the composition of the population differed between the transition layer between rumen fluid and the fibre mat (fraction A) and the rumen fluid (fraction B) highlighting the importance to standardize sampling. The 16S rDNA copies of total bacteria and the six bacterial species as well as the population composition were mainly unaffected by the high levels of exogenous enzymes supplemented at all sampling times and in both rumen fractions. Occasionally, the percentages of the non-fibrolytic species P. ruminicola and A. lipolytica changed in response to enzyme supplementation. Some increases in the potential degradability of the diet and decreases in lag time which occurred collaterally indicate that other factors than changes in numbers of non-particle-associated bacteria are mainly responsible for the effects of

  1. Fibrolytic Bacteria Isolated from the Rumen of North American Moose (Alces alces) and Their Use as a Probiotic in Neonatal Lambs.

    PubMed

    Ishaq, Suzanne L; Kim, Christina J; Reis, Doug; Wright, André-Denis G

    2015-01-01

    Fibrolytic bacteria were isolated from the rumen of North American moose (Alces alces), which eat a high-fiber diet of woody browse. It was hypothesized that fibrolytic bacteria isolated from the moose rumen could be used as probiotics to improve fiber degradation and animal production. Thirty-one isolates (Bacillus, n = 26; Paenibacillus, n = 1; and Staphylococcus, n = 4) were cultured from moose rumen digesta samples collected in Vermont. Using Sanger sequencing of the 16S rRNA gene, culturing techniques, and optical densities, isolates were identified and screened for biochemical properties important to plant carbohydrate degradation. Five isolates were selected as candidates for use as a probiotic, which was administered daily to neonate lambs for 9 weeks. It was hypothesized that regular administration of a probiotic to improve fibrolysis to neonate animals through weaning would increase the developing rumen bacterial diversity, increase animal production, and allow for long-term colonization of the probiotic species. Neither weight gain nor wool quality was improved in lambs given a probiotic, however, dietary efficiency was increased as evidenced by the reduced feed intake (and rearing costs) without a loss to weight gain. Experimental lambs had a lower acetate to propionate ratio than control lambs, which was previously shown to indicate increased dietary efficiency. Fibrolytic bacteria made up the majority of sequences, mainly Prevotella, Butyrivibrio, and Ruminococcus. While protozoal densities increased over time and were stable, methanogen densities varied greatly in the first six months of life for lambs. This is likely due to the changing diet and bacterial populations in the developing rumen.

  2. Fibrolytic Bacteria Isolated from the Rumen of North American Moose (Alces alces) and Their Use as a Probiotic in Neonatal Lambs

    PubMed Central

    Ishaq, Suzanne L.; Kim, Christina J.; Reis, Doug; Wright, André-Denis G.

    2015-01-01

    Fibrolytic bacteria were isolated from the rumen of North American moose (Alces alces), which eat a high-fiber diet of woody browse. It was hypothesized that fibrolytic bacteria isolated from the moose rumen could be used as probiotics to improve fiber degradation and animal production. Thirty-one isolates (Bacillus, n = 26; Paenibacillus, n = 1; and Staphylococcus, n = 4) were cultured from moose rumen digesta samples collected in Vermont. Using Sanger sequencing of the 16S rRNA gene, culturing techniques, and optical densities, isolates were identified and screened for biochemical properties important to plant carbohydrate degradation. Five isolates were selected as candidates for use as a probiotic, which was administered daily to neonate lambs for 9 weeks. It was hypothesized that regular administration of a probiotic to improve fibrolysis to neonate animals through weaning would increase the developing rumen bacterial diversity, increase animal production, and allow for long-term colonization of the probiotic species. Neither weight gain nor wool quality was improved in lambs given a probiotic, however, dietary efficiency was increased as evidenced by the reduced feed intake (and rearing costs) without a loss to weight gain. Experimental lambs had a lower acetate to propionate ratio than control lambs, which was previously shown to indicate increased dietary efficiency. Fibrolytic bacteria made up the majority of sequences, mainly Prevotella, Butyrivibrio, and Ruminococcus. While protozoal densities increased over time and were stable, methanogen densities varied greatly in the first six months of life for lambs. This is likely due to the changing diet and bacterial populations in the developing rumen. PMID:26716685

  3. Fibrolytic potential of anaerobic fungi (Piromyces sp.) isolated from wild cattle and blue bulls in pure culture and effect of their addition on in vitro fermentation of wheat straw and methane emission by rumen fluid of buffaloes.

    PubMed

    Paul, Shyam S; Deb, Sitangshu M; Punia, Balbir S; Singh, Dharminder; Kumar, Rajiv

    2010-05-01

    Ten isolates of anaerobic fungi of Piromyces genus from wild cattle and blue bulls (five isolates from each host species) were evaluated for their fibrolytic ability in pure culture, their suitability for use as a microbial additive in buffaloes and their effect on methane emission. In pure culture, only two out of five isolates from wild cattle degraded wheat straw efficiently, whereas all five isolates from wild blue bulls did. Isolate CF1 (from cattle) showed the highest apparent digestibility (53.4%), true digestibility (70.8%) and neutral detergent fibre digestibility (75.0%) of wheat straw after 5 days of incubation. When added to buffalo rumen fluid, all five isolates from cattle increased (P < 0.05) in vitro apparent digestibility of wheat straw compared with the control (received autoclaved culture), but all five isolates from blue bulls failed to influence in vitro digestibility of wheat straw. Isolate CF1 showed the highest stimulating effect on straw digestion by buffalo rumen fluid microbes and increased apparent digestibility (51.9 vs 29.4%, P < 0.05), true digestibility (57.9 vs 36.5%, P < 0.05) and neutral detergent fibre digestibility (51.5 vs 26.9%, P < 0.05) of wheat straw compared with the control after 24 h of fermentation. There were also significant increases in fungal count and enzyme activities of carboxymethylcellulase and xylanase in the CF1-added group compared with the control group. Gas and methane production g(-1) truly digested dry matter of straw were comparable among all groups including the control. Wild cattle and blue bulls harbour some anaerobic fungal strains with strong capability to hydrolyse fibre. The fungal isolate CF1 has high potential for use as a microbial feed additive in buffaloes to improve digestibility of fibrous feeds without increasing methane emission per unit of digested feed.

  4. Live yeasts enhance fibre degradation in the cow rumen through an increase in plant substrate colonization by fibrolytic bacteria and fungi.

    PubMed

    Chaucheyras-Durand, F; Ameilbonne, A; Bichat, A; Mosoni, P; Ossa, F; Forano, E

    2016-03-01

    To monitor the effect of a live yeast additive on feedstuff colonization by targeted fibrolytic micro-organisms and fibre degradation in the cow rumen. Abundance of adhering fibrolytic bacteria and fungi on feedstuffs incubated in sacco in the cow rumen was quantified by qPCR and neutral detergent fibre (NDF) degradation was measured. Saccharomyces cerevisiae I-1077 (SC) increased the abundance of fibre-associated Fibrobacter succinogenes on wheat bran (WB) and that of Ruminococcus flavefaciens on alfalfa hay (AH) and wheat silage (WS). The greatest effect was observed on the abundance of Butyrivibrio fibrisolvens on AH and soya hulls (SH) (P < 0·001). Fungal biomass increased on AH, SH, WS and WB in the presence of SC. NDF degradation of AH and SH was improved (P < 0·05) with SC supplementation. Live yeasts enhanced microbial colonization of fibrous materials, the degree of enhancement depended on their nature and composition. As an effect on rumen pH was not likely to be solely involved, the underlying mechanisms could involve nutrient supply or oxygen scavenging by the live yeast cells. Distribution of this microbial additive could be an interesting tool to increase fibre digestion in the rumen and thereby improve cow feed efficiency. © 2015 The Society for Applied Microbiology.

  5. Use of bean husk as an easily digestible fiber source for activating the fibrolytic rumen bacterium Fibrobacter succinogenes and rice straw digestion.

    PubMed

    Fuma, Ryosuke; Oyaizu, Shinya; Nukui, Yoko; Ngwe, Tin; Shinkai, Takumi; Koike, Satoshi; Kobayashi, Yasuo

    2012-10-01

    A series of in sacco and in vitro studies were carried out to evaluate bean husks for activation of fibrolytic rumen bacteria and rice straw digestion. First, lablab bean husk, chickpea husk and rice straw were suspended in the rumen of sheep to analyze the bacterial consortium developed on each fiber source. Known members of fiber-associating bacteria were found on both lablab bean husk and rice straw, but some of these bacteria were lacking on chickpea husk. Second, a pure culture study was carried out using six strains of Fibrobacter succinogenes. Both husks stimulated the growth of all tested strains, including a strain that did not grow on rice straw. The strain OS128 that showed the highest growth on rice straw displayed even higher growth on lablab bean husk without a time lag. Finally, two-step incubations were carried out to determine whether prior incubation of rumen fluid with husks stimulates subsequent rice straw digestion. Higher digestibility of rice straw was recorded in the second-round incubation following the first incubation with bean husks. These results suggest that the tested bean husks improve the digestion of rice straw by activating fibrolytic F. succinogenes and other associated bacteria.

  6. Effect of ciliate protozoa on the activity of polysaccharide-degrading enzymes and fibre breakdown in the rumen ecosystem.

    PubMed

    Williams, A G; Withers, S E

    1991-02-01

    The effect of ciliate protozoa on the activity of polysaccharide-degrading enzymes in microbial populations from the digesta solids and liquor fractions of rumen contents was examined after the refaunation of ciliate-free sheep with an A-type rumen protozoal population. Although the culturable rumen bacterial population was reduced after refaunation the number of fibrolytic micro-organisms detected was higher; the xylanolytic bacterial population and numbers of fungal zoospores were increased after refaunation. The proportion of propionic acid was lower in the refaunated animals, whereas the concentration of ammonia and the acidic metabolites acetate, butyrate and valerate were all increased. The range of enzyme activities present in the digesta subpopulations were the same in defaunated and refaunated animals. The activities of the polysaccharide-degrading enzymes, however, were increased in the microbial populations associated with the digesta solids after refaunation, and at 16 h after feeding the activities were 4-8 times (beta-D-xylosidase 20 times) higher than the levels detected in the adherent population from defaunated sheep. The protozoa, either directly through their own enzymes or indirectly as a consequence of their effects on the population size and activity of the other fibrolytic micro-organisms present, have an important role in determining the level of activity of polysaccharide-degrading enzymes in the rumen ecosystem. Although the extent of ryegrass (Lolium perenne) hay digestion was similar after 24 h in the absence or presence of protozoa, the initial ruminal degradation was higher in refaunated sheep.

  7. Exogenous methionine increases levels of mRNAs transcribed from pcbAB, pcbC, and cefEF genes, encoding enzymes of the cephalosporin biosynthetic pathway, in Acremonium chrysogenum.

    PubMed Central

    Velasco, J; Gutierrez, S; Fernandez, F J; Marcos, A T; Arenos, C; Martin, J F

    1994-01-01

    Methionine stimulated cephalosporin production in cultures of three different strains of Acremonium chrysogenum when added either at inoculation time or at 72 h to cells grown previously in the absence of methionine. When methionine was added at 72 h, the stimulation of cephalosporin biosynthesis was observed only 12 h later and required de novo protein synthesis. Methionine increased the levels of enzymes (isopenicillin N synthase and deacetylcephalosporin C acetyltransferase) expressed from genes (pcbC and cefG, respectively) located in the two clusters of cephalosporin biosynthesis genes in the wild-type A. chrysogenum strain and also in the two improved strains, CW19 and C10. Methionine-supplemented cells showed higher levels of transcripts of the four known genes (pcbAB, pcbC, cefEF and, to a slight extent, cefG) of the cephalosporin biosynthetic pathway than cells grown in the absence of methionine. The levels of the cefG transcript were much lower than those of the pcbAB, pcbC, and cefEF transcripts. The induction by methionine of transcription of the four cephalosporin biosynthesis genes and the known effect of this amino acid on the differentiation of A. chrysogenum indicate that methionine exerts a pleiotropic effect that coordinately regulates cephalosporin biosynthesis and differentiation. Images PMID:8106341

  8. Effect of exogenous xylanase on rumen in vitro gas production and degradability of wheat straw.

    PubMed

    Togtokhbayar, Norovsambuu; Cerrillo, María A; Rodríguez, Germán Buendía; Elghandour, Mona M M Y; Salem, Abdelfattah Z M; Urankhaich, Chuluunbaatar; Jigjidpurev, Sukhbaatar; Odongo, Nicholas E; Kholif, Ahmed E

    2015-08-01

    The objective of this study was to determine effects of xylanase on in vitro gas production (GP) and in sacco degradability of wheat straw. Rumen fluid was obtained from three Mongolian native goats fitted with permanent rumen cannulas. The trial consisted of five doses (0, 0.5, 1.0, 1.5, 2.0 μL/g of substrate) of a commercial xylanase (Dyadic® xylanase PLUS, Dyadic International, Inc., Jupiter, FL, USA). For the in sacco degradability, different levels of xylanase enzyme were added directly onto 2 g of wheat straw in nylon bags and incubated in the rumen for 3, 6, 12, 24 and 48 h to estimate degradability of wheat straw. Total GP increased (P < 0.001) at all times of incubation at intermediate levels of xylanase. Methane production had a similar pattern at 3 and 12 h of incubation; increased linearly at 24 h of incubation, and was unaffected at 6 and 48 h of incubation. Rumen NH3 -N concentration increased linearly at 3 h and the highest values were observed with intermediate enzyme levels. All ruminal volatile fatty acids increased linearly with intermediate levels of the fibrolytic enzyme. The in sacco rate of dry matter degradation decreased linearly (P = 0.020) with increasing enzymes. Intermediate levels of xylanase improved rumen kinetic fermentation and degradability. The outcome of this research indicated that the application of xylanase enzyme could improve in vitro GP fermentation of wheat straw.

  9. Exogenous Attention Enables Perceptual Learning.

    PubMed

    Szpiro, Sarit F A; Carrasco, Marisa

    2015-12-01

    Practice can improve visual perception, and these improvements are considered to be a form of brain plasticity. Training-induced learning is time-consuming and requires hundreds of trials across multiple days. The process of learning acquisition is understudied. Can learning acquisition be potentiated by manipulating visual attentional cues? We developed a protocol in which we used task-irrelevant cues for between-groups manipulation of attention during training. We found that training with exogenous attention can enable the acquisition of learning. Remarkably, this learning was maintained even when observers were subsequently tested under neutral conditions, which indicates that a change in perception was involved. Our study is the first to isolate the effects of exogenous attention and to demonstrate its efficacy to enable learning. We propose that exogenous attention boosts perceptual learning by enhancing stimulus encoding.

  10. Expressing exogenous genes in newts by transgenesis.

    PubMed

    Casco-Robles, Martin Miguel; Yamada, Shouta; Miura, Tomoya; Nakamura, Kenta; Haynes, Tracy; Maki, Nobuyasu; Del Rio-Tsonis, Katia; Tsonis, Panagiotis A; Chiba, Chikafumi

    2011-05-01

    The great regenerative abilities of newts provide the impetus for studies at the molecular level. However, efficient methods for gene regulation have historically been quite limited. Here we describe a protocol for transgenically expressing exogenous genes in the newt Cynops pyrrhogaster. This method is simple: a reaction mixture of I-SceI meganuclease and a plasmid DNA carrying a transgene cassette flanked by the enzyme recognition sites is directly injected into fertilized eggs. The protocol achieves a high efficiency of transgenesis, comparable to protocols used in other animal systems, and it provides a practical number of transgenic newts (∼20% of injected embryos) that survive beyond metamorphosis and that can be applied to regenerative studies. The entire protocol for obtaining transgenic adult newts takes 4-5 months.

  11. Exogenous attention to unseen objects?

    PubMed

    Norman, Liam J; Heywood, Charles A; Kentridge, Robert W

    2015-09-01

    Attention and awareness are closely related phenomena, but recent evidence has shown that not all attended stimuli give rise to awareness. Controversy still remains over whether, and the extent to which, a dissociation between attention and awareness encompasses all forms of attention. For example, it has been suggested that attention without awareness is more readily demonstrated for voluntary, endogenous attention than its reflexive, exogenous counterpart. Here we examine whether exogenous attentional cueing can have selective behavioural effects on stimuli that nevertheless remain unseen. Using a task in which object-based attention has been shown in the absence of awareness, we remove all possible contingencies between cues and target stimuli to ensure that any cueing effects must be under purely exogenous control, and find evidence of exogenous object-based attention without awareness. In a second experiment we address whether this dissociation crucially depends on the method used to establish that the objects indeed remain unseen. Specifically, to confirm that objects are unseen we adopt appropriate signal detection task procedures, including those that retain parity with the primary attentional task (by requiring participants to discriminate the two types of trial that are used to measure an effect of attention). We show a significant object-based attention effect is apparent under conditions where the selected object indeed remains undetectable.

  12. Improvement in Saccharification Yield of Mixed Rumen Enzymes by Identification of Recalcitrant Cell Wall Constituents Using Enzyme Fingerprinting.

    PubMed

    Badhan, Ajay; Wang, Yu-Xi; Gruninger, Robert; Patton, Donald; Powlowski, Justin; Tsang, Adrian; McAllister, Tim A

    2015-01-01

    Identification of recalcitrant factors that limit digestion of forages and the development of enzymatic approaches that improve hydrolysis could play a key role in improving the efficiency of meat and milk production in ruminants. Enzyme fingerprinting of barley silage fed to heifers and total tract indigestible fibre residue (TIFR) collected from feces was used to identify cell wall components resistant to total tract digestion. Enzyme fingerprinting results identified acetyl xylan esterases as key to the enhanced ruminal digestion. FTIR analysis also suggested cross-link cell wall polymers as principal components of indigested fiber residues in feces. Based on structural information from enzymatic fingerprinting and FTIR, enzyme pretreatment to enhance glucose yield from barley straw and alfalfa hay upon exposure to mixed rumen-enzymes was developed. Prehydrolysis effects of recombinant fungal fibrolytic hydrolases were analyzed using microassay in combination with statistical experimental design. Recombinant hemicellulases and auxiliary enzymes initiated degradation of plant structural polysaccharides upon application and improved the in vitro saccharification of alfalfa and barley straw by mixed rumen enzymes. The validation results showed that microassay in combination with statistical experimental design can be successfully used to predict effective enzyme pretreatments that can enhance plant cell wall digestion by mixed rumen enzymes.

  13. Exogenous melatonin improves Malus resistance to Marssonina apple blotch.

    PubMed

    Yin, Lihua; Wang, Ping; Li, Mingjun; Ke, Xiwang; Li, Cuiying; Liang, Dong; Wu, Shan; Ma, Xinli; Li, Chao; Zou, Yangjun; Ma, Fengwang

    2013-05-01

    We examined whether exogenously applied melatonin could improve resistance to Marssonina apple blotch (Diplocarpon mali) by apple [Malus prunifolia (Willd.) Borkh. cv. Donghongguo]. This serious disease leads to premature defoliation in the main regions of apple production. When plants were pretreated with melatonin, resistance was increased in the leaves. We investigated the potential roles for melatonin in modulating levels of hydrogen peroxide (H2O2), as well the activities of antioxidant enzymes and pathogenesis-related proteins during these plant-pathogen interactions. Pretreatment enabled plants to maintain intracellular H2O2 concentrations at steady-state levels and enhance the activities of plant defence-related enzymes, possibly improving disease resistance. Because melatonin is safe and beneficial to animals and humans, exogenous pretreatment might represent a promising cultivation strategy to protect plants against this pathogen infection. © 2012 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

  14. Exogenic and endogenic Europa minerals

    NASA Astrophysics Data System (ADS)

    Maynard-Casely, H. E.; Brand, H. E. A.; Wilson, S. A.

    2016-12-01

    The Galileo Near Infrared Mapping Spectrometer (NIMS) identified a significant `non-ice' component upon the surface of Jupiter's moon Europa. Current explanations invoke both endogenic and exogenic origins for this material. It has long been suggested that magnesium and sodium sulfate minerals could have leached from the rock below a putative ocean (endogenic) 1 and that sulfuric acid hydrate minerals could have been radiologically produced from ionised sulfur originally from Io's volcanoes (exogenic) 2. However, a more recent theory proposes that the `non-ice' component could be radiation damaged NaCl leached from Europa's speculative ocean 3. What if the minerals are actually from combination of both endogenic and exogenic sources? To investigate this possibility we have focused on discovering new minerals that might form in the combination of the latter two cases, that is a mixture of leached sulfates hydrates with radiologically produced sulfuric acid. To this end we have explored a number of solutions in the MgSO4-H2SO4-H2O and Na2SO4-H2SO4-H2O systems, between 80 and 280 K with synchrotron x-ray powder diffraction. We report a number of new materials formed in this these ternary systems. This suggests that it should be considered that the `non-ice' component of the Europa's surface could be a material derived from endogenic and exogenic components. 1 Kargel, J. S. Brine volcanism and the interior structures of asteroids and icy satellites. Icarus 94, 368-390 (1991). 2 Carlson, R. W., Anderson, M. S., Mehlman, R. & Johnson, R. E. Distribution of hydrate on Europa: Further evidence for sulfuric acid hydrate. Icarus 177, 461-471, doi:10.1016/j.icarus.2005.03.026 (2005). 3 Hand, K. P. & Carlson, R. W. Europa's surface color suggests an ocean rich with sodium chloride. Geophysical Research Letters, 2015GL063559, doi:10.1002/2015gl063559 (2015).

  15. Alleviation of cadmium toxicity to Cole (Brassica campestris L. Cruciferae) by exogenous glutathione

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Huang, Bin; Chen, Xin; Shi, Yi

    2017-04-01

    In this study, we determined the influence of exogenous GSH on cadmium toxicity to cole. GSH addition had beneficial effect on plant development and growth, especially on aboveground biomass and root length. Despite that exogenous GSH insignificantly promoted Cd uptake by the plant, it could decrease of Cd root-to-shoot transport and ameliorate Cd toxicity to the plant. At 6 mg Cd kg-1 soil, GSH addition well countered the Cd-induced significant reduction in CAT activity, but only insignificantly decreased MDA content, suggesting exogenous GSH might indirectly protect plant against oxidative stress via regulating antioxidative enzyme activities. However, at 12 mg Cd kg-1 soil, GSH application insignificantly increased the antioxidant activities but significantly decreased MDA content, indicating external GSH could directly participate in removing radical oxygen species. The results suggest exogenous GSH may have the potential of decreasing Cd accumulation in the edible parts of cultivars and alleviating Cd toxicity.

  16. Motivation sharpens exogenous spatial attention.

    PubMed

    Engelmann, Jan B; Pessoa, Luiz

    2007-08-01

    Although both attention and motivation affect behavior, how these 2 systems interact is currently unknown. To address this question, 2 experiments were conducted in which participants performed a spatially cued forced-choice localization task under varying levels of motivation. Participants were asked to indicate the location of a peripherally cued target while ignoring a distracter. Motivation was manipulated by varying magnitude and valence (reward and punishment) of an incentive linked to task performance. Attention was manipulated via a peripheral cue, which correctly predicted the presence of a target stimulus on 70% of the trials. Taken together, our findings revealed that the signal detection measure, reflecting perceptual sensitivity, increased as a function of incentive value during both valid and invalid trials. In addition, trend analyses revealed a linear increase in detection sensitivity as a function of incentive magnitude for both reward and punishment conditions. Our results suggest that elevated motivation leads to improved efficiency in orienting and reorienting of exogenous spatial attention and that one mechanism by which attention and motivation interact involves the sharpening of attention during motivationally salient conditions.

  17. Exogenous fatty acid metabolism in bacteria.

    PubMed

    Yao, Jiangwei; Rock, Charles O

    2017-10-01

    Bacterial type II fatty acid synthesis (FASII) is a target for novel antibiotic development. All bacteria encode for mechanisms to incorporate exogenous fatty acids, and some bacteria can use exogenous fatty acids to bypass FASII inhibition. Bacteria encode three different mechanisms for activating exogenous fatty acids for incorporation into phospholipid synthesis. Exogenous fatty acids are converted into acyl-CoA in Gammaproteobacteria such as E. coli. Acyl-CoA molecules constitute a separate pool from endogenously synthesized acyl-ACP. Acyl-CoA can be used for phospholipid synthesis or broken down by β-oxidation, but cannot be used for lipopolysaccharide synthesis. Exogenous fatty acids are converted into acyl-ACP in some Gram-negative bacteria. The resulting acyl-ACP undergoes the same fates as endogenously synthesized acyl-ACP. Exogenous fatty acids are converted into acyl-phosphates in Gram-positive bacteria, and can be used for phospholipid synthesis or become acyl-ACP. Only the order Lactobacillales can use exogenous fatty acids to bypass FASII inhibition. FASII shuts down completely in presence of exogenous fatty acids in Lactobacillales, allowing Lactobacillales to synthesize phospholipids entirely from exogenous fatty acids. Inhibition of FASII cannot be bypassed in other bacteria because FASII is only partially down-regulated in presence of exogenous fatty acid or FASII is required to synthesize essential metabolites such as β-hydroxyacyl-ACP. Certain selective pressures such as FASII inhibition or growth in biofilms can select for naturally occurring one step mutations that attenuate endogenous fatty acid synthesis. Although attempts have been made to estimate the natural prevalence of these mutants, culture-independent metagenomic methods would provide a better estimate. Copyright © 2017 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

  18. [Effect of cadmium stress on physiological characteristics of garlic seedlings and the alleviation effects of exogenous calcium].

    PubMed

    Li, He; Lian, Hai-feng; Liu, Shi-qi; Yu, Xin-hui; Sun, Ya-li; Guo, Hui-ping

    2015-04-01

    In the experiment, the effects of exogenous cadmium (Cd2+) and calcium (Ca2+) in nutrient solution on growth, photosynthetic characteristics, enzymes activities, main mineral elements absorption of garlic seedlings were studied. The results showed that cadmium could obviously inhibit the growth of garlic seedlings, decrease the pigment contents and photosynthetic parameters (P(n), E, g(s)) of leaves, reduced the enzymes (SOD, POD, CAT) activities and increase the MDA content of leaves, and also could reduce the N, P, K, Ca, Mg contents and increase the Cd content of roots. The growth was promoted after adding exogenous calcium to garlic seedlings under cadmium stress, which reflected that the morphological indexes were increased at first and then decreased with the increase of exogenous calcium concentrations, and were maximized when the exogenous calcium was 2 or 3 mmol x L(-1). At the same time, the pigment contents and photosynthetic parameters (P(n), E, g(s)) of leaves showed a similar tendency with the morphological indexes, and they were the highest when the exogenous calcium was 2 or 3 mmol x L(-1). In addition, adding exogenous calcium to garlic seedlings under cadmium stress enhanced the enzymes (SOD, POD, CAT) activities and decreased the MDA content of leaves, also added the N, P, K, Ca, Mg contents and reduced the Cd content of roots, and the effect was best when the exogenous calcium concentration was 2 or 3 mmol x L(-1).

  19. Exogenous spatial attention decreases audiovisual integration.

    PubMed

    Van der Stoep, N; Van der Stigchel, S; Nijboer, T C W

    2015-02-01

    Multisensory integration (MSI) and spatial attention are both mechanisms through which the processing of sensory information can be facilitated. Studies on the interaction between spatial attention and MSI have mainly focused on the interaction between endogenous spatial attention and MSI. Most of these studies have shown that endogenously attending a multisensory target enhances MSI. It is currently unclear, however, whether and how exogenous spatial attention and MSI interact. In the current study, we investigated the interaction between these two important bottom-up processes in two experiments. In Experiment 1 the target location was task-relevant, and in Experiment 2 the target location was task-irrelevant. Valid or invalid exogenous auditory cues were presented before the onset of unimodal auditory, unimodal visual, and audiovisual targets. We observed reliable cueing effects and multisensory response enhancement in both experiments. To examine whether audiovisual integration was influenced by exogenous spatial attention, the amount of race model violation was compared between exogenously attended and unattended targets. In both Experiment 1 and Experiment 2, a decrease in MSI was observed when audiovisual targets were exogenously attended, compared to when they were not. The interaction between exogenous attention and MSI was less pronounced in Experiment 2. Therefore, our results indicate that exogenous attention diminishes MSI when spatial orienting is relevant. The results are discussed in terms of models of multisensory integration and attention.

  20. Restoration of in situ fiber degradation and the role of fibrolytic microbes and ruminal pH in cows fed grain-rich diets transiently or continuously.

    PubMed

    Pourazad, P; Khiaosa-Ard, R; Metzler-Zebeli, B U; Klevenhusen, F; Zebeli, Q

    2017-05-22

    In this study, we used two different grain-rich feeding models (continuous or transient) to determine their effects on in situ fiber degradation and abundances of important rumen fibrolytic microbes in the rumen. The role of the magnitude of ruminal pH drop during grain feeding in the fiber degradation was also determined. The study was performed in eight rumen-fistulated dry cows. They were fed forage-only diet (baseline), and then challenged with a 60% concentrate diet for 4 weeks, either continuously (n=4 cows) or transiently (n=4 cows). The cows of transient feeding had 1 week off concentrate in between. Ruminal degradation of grass silage and fiber-rich hay was determined by the in situ technique, and microbial abundances attached to incubated samples were analyzed by quantitative PCR. The in situ trials were performed at the baseline and in the 1st and the last week of concentrate feeding in the continuous model. The in situ trials were done in cows of the transient model at the baseline and in the 1st week of the re-challenge with concentrate. In situ degradation of NDF and ADF of the forage samples, and microbial abundances were determined at 0, 4, 8, 24 and 48 h of the incubation. Ruminal pH and temperature during the incubation were recorded using indwelling pH sensors. Compared with the respective baseline, both grain-rich feeding models lowered ruminal pH and increased the duration of pH below 5.5 and 5.8. Results of the grass silage incubation showed that in the continuous model the extent of NDF and ADF degradation was lower in the 1st, but not in the last week compared with the baseline. For the transient model, degradation of NDF of the silage was lower during the re-challenge compared with the baseline. Degradation of NDF and ADF of the hay was suppressed by both feeding models compared with the respective baseline. Changes in fiber degradation of either grass silage or hay were not related to the magnitude of ruminal pH depression during grain

  1. Tendon Fibroplasia Induction by Exogenous Electrical Fields.

    DTIC Science & Technology

    1986-08-10

    AD-A172 279 TENDON FIEROPLASIA INDUCTION BY EXOGENOUS ELECTRICAL 1/𔃻 FIELDS(U) MEDICAL COLL OF VIRGINIA RICHMOND DEPT OF PHYSIOLOGY AND BIOPHYSICS S...Security Classification) Tendon Fibroplasia Induction by Exogenous Electrical Fields l2dAL 9I F.; Liu, Li-Ming. 134. TYPE PF REPORT 13b. TIME COVERED 14... tendon explant fibroplasia, collagen synthesis and oriented migration. Independent variables are: pulse repetition rate, pulse duration, peak current

  2. Exogenous polyamines promote osteogenic differentiation by reciprocally regulating osteogenic and adipogenic gene expression.

    PubMed

    Lee, Mon-Juan; Chen, Yuhsin; Huang, Yuan-Pin; Hsu, Yi-Chiang; Chiang, Lan-Hsin; Chen, Tzu-Yu; Wang, Gwo-Jaw

    2013-12-01

    Polyamines are naturally occurring organic polycations that are ubiquitous in all organisms, and are essential for cell proliferation and differentiation. Although polyamines are involved in various cellular processes, their roles in stem cell differentiation are relatively unexplored. In this study, we found that exogenous polyamines, putrescine, spermidine, and spermine, promoted osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBMSCs) without inducing cell death or apoptosis. Alkaline phosphatase (ALP) activity and the mRNA level of osteogenic genes, including Runx2, ALP, osteopontin, and osteocalcin, were up-regulated by exogenous polyamines. When hBMSCs were cultured at high cell density favoring adipocyte formation, exogenous polyamines resulted in down-regulation of adipogenic genes such as PPARγ, aP2, and adipsin. Extracellular matrix mineralization, a marker for osteoblast maturation, was enhanced in the presence of exogenous polyamines, while lipid accumulation, an indication of adipogenic differentiation, was attenuated. Exogenous polyamines increased the mRNA expression of polyamine-modulated factor 1 (PMF-1) and its downstream effector, spermidine/spermine N(1)-acetyltransferase (SSAT), while that of ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine biosynthesis, was suppressed. These results lead to possible connections between polyamine metabolism and osteogenic differentiation pathways. To summarize, this study provides evidence for the involvement of polyamines in osteogenic differentiation of hBMSCs, and is the first to demonstrate that osteogenic and adipogenic differentiation are reciprocally regulated by exogenous polyamines.

  3. Functional analyses of multiple lichenin-degrading enzymes from the rumen bacterium Ruminococcus albus 8.

    PubMed

    Iakiviak, Michael; Mackie, Roderick I; Cann, Isaac K O

    2011-11-01

    Ruminococcus albus 8 is a fibrolytic ruminal bacterium capable of utilization of various plant cell wall polysaccharides. A bioinformatic analysis of a partial genome sequence of R. albus revealed several putative enzymes likely to hydrolyze glucans, including lichenin, a mixed-linkage polysaccharide of glucose linked together in β-1,3 and β-1,4 glycosidic bonds. In the present study, we demonstrate the capacity of four glycoside hydrolases (GHs), derived from R. albus, to hydrolyze lichenin. Two of the genes encoded GH family 5 enzymes (Ra0453 and Ra2830), one gene encoded a GH family 16 enzyme (Ra0505), and the last gene encoded a GH family 3 enzyme (Ra1595). Each gene was expressed in Escherichia coli, and the recombinant protein was purified to near homogeneity. Upon screening on a wide range of substrates, Ra0453, Ra2830, and Ra0505 displayed different hydrolytic properties, as they released unique product profiles. The Ra1595 protein, predicted to function as a β-glucosidase, preferred cleavage of a nonreducing end glucose when linked by a β-1,3 glycosidic bond to the next glucose residue. The major product of Ra0505 hydrolysis of lichenin was predicted to be a glucotriose that was degraded only by Ra0453 to glucose and cellobiose. Most importantly, the four enzymes functioned synergistically to hydrolyze lichenin to glucose, cellobiose, and cellotriose. This lichenin-degrading enzyme mix should be of utility as an additive to feeds administered to monogastric animals, especially those high in fiber.

  4. Endogenous versus Exogenous Origins of Crises

    NASA Astrophysics Data System (ADS)

    Sornette, Didier

    Are large biological extinctions such as the Cretaceous/Tertiary KT boundary due to a meteorite, extreme volcanic activity or self-organized critical extinction cascades? Are commercial successes due to a progressive reputation cascade or the result of a well orchestrated advertisement? Determining the chain of causality for Xevents in complex systems requires disentangling interwoven exogenous and endogenous contributions with either no clear signature or too many signatures. Here, I review several efforts carried out with collaborators which suggest a general strategy for understanding the organizations of several complex systems under the dual effect of endogenous and exogenous fluctuations. The studied examples are: internet download shocks, book sale shocks, social shocks, financial volatility shocks, and financial crashes. Simple models are offered to quantitatively relate the endogenous organization to the exogenous response of the system. Suggestions for applications of these ideas to many other systems are offered.

  5. Enzyme assays.

    PubMed

    Reymond, Jean-Louis; Fluxà, Viviana S; Maillard, Noélie

    2009-01-07

    Enzyme assays are analytical tools to visualize enzyme activities. In recent years a large variety of enzyme assays have been developed to assist the discovery and optimization of industrial enzymes, in particular for "white biotechnology" where selective enzymes are used with great success for economically viable, mild and environmentally benign production processes. The present article highlights the aspects of fluorogenic and chromogenic substrates, sensors, and enzyme fingerprinting, which are our particular areas of interest.

  6. Improved abiotic stress tolerance of bermudagrass by exogenous small molecules.

    PubMed

    Chan, Zhulong; Shi, Haitao

    2015-01-01

    As a widely used warm-season turfgrass in landscapes and golf courses, bermudagrass encounters multiple abiotic stresses during the growth and development. Physiology analysis indicated that abiotic stresses induced the accumulation of ROS and decline of photosynthesis, resulting in increased cell damage and inhibited growth. Proteomic and metabolomic approaches showed that antioxidant enzymes and osmoprotectant contents (sugar, sucrose, dehydrin, proline) were extensively changed under abiotic stress conditions. Exogenous application of small molecules, such as ABA, NO, CaCl2, H2S, polyamine and melatonin, could effectively alleviate damages caused by multiple abiotic stresses, including drought, salt, heat and cold. Based on high through-put RNA seq analysis, genes involved in ROS, transcription factors, hormones, and carbohydrate metabolisms were largely enriched. The data indicated that small molecules induced the accumulation of osmoprotectants and antioxidants, kept cell membrane integrity, increased photosynthesis and kept ion homeostasis, which protected bermudagrass from damages caused by abiotic stresses.

  7. [Exogenous NO mediated GSH-PCs synthesis pathway in tomato under copper stress].

    PubMed

    Wang, Jian; Yu, Shi-Xin; Zhang, Min; Cui, Xiu-Min

    2014-09-01

    Nitric oxide (NO), as a biologically active molecule, widely involved in the biotic and abiotic stresses. By using solution culture, this paper reported the dynamic changes in enzyme activity and metabolites related to GSH-PCs synthesis way mediated by exogenous NO in tomato (Lycopersicon esculentum). The results showed that exogenous NO could affect the metabolic pathway of GSH-PCs in tomato seedlings under copper stress. Compared with CK, the activity of γ-ECS and GS was significantly activated, consequently resulting in a sharp rise in GSH and PCs contents in tomato root. Moreover, γ-ECS and GS activity, GSH and PCs contents constantly rise with the extension of processing time under copper stress. Adding exogenous SNP could further improve γ-ECS and GS activity in tomato, and promote the production of GSH and PCs, which contributed to enhancing the ability of removing superoxide and chelating excess Cu2+ to reduce its biological toxicity. To a certain extent, GSH-PCs metabolic changes in leaf lagged behind that in roots. Exogenous BSO could significantly inhibit γ-ECS activity, and applying SNP could significantly reverse the inhibition on GSH and PCs synthesis by BSO. BSO had little effects on PCs content in leaf. Under copper stress, exogenous NO may initiate a signal mechanism and reduce the biotoxicity and oxidative damage caused by excessive Cu2+ by activating or enhancing the enzymatic and non-enzymatic systems in the GSH-PCs synthesis path.

  8. Spotlight failure effect in exogenous orienting.

    PubMed

    Milán, E G; Tornay, F J

    2001-12-01

    Many experimental results about spatial attention have been explained by assuming the existence of an attentional "spotlight" which can move from one location in visual space to another. Such an account has been recently challenged by findings which show the influence of nonspatial factors in spatial attention. In particular, the so-called "spotlight failure" effect refers to the influence of the probability of occurrence of different stimuli. However, such an effect has only been reported in the case of endogenous (or central) orientation, rather than on exogenous (or peripheral) orienting. We present evidence showing that the spotlight failure effect can be obtained with exogenous orienting, even at a short SOA (100 ms). Besides, experimental instructions can modulate the effect, which agrees with theoretical accounts proposing that top-down factors can influence attentional capture.

  9. Exogenous ochronosis following hydroquinone for melasma.

    PubMed

    Zawar, V P; Mhaskar, S T

    2004-12-01

    A female Indian farmer with melasma developed progressive worsening of facial pigmentation while using topical hydroquinone. It manifested as bluish-black pigmentation, confirmed microscopically as ochronotic change, i.e. exogenous ochronosis (EO). Failure to follow adequate sun protective measures and usage of overly high concentrations of hydroquinone were the most likely causes of EO in this case. It is necessary to recognize this disorder at the earliest stage to avoid treatment disappointments.

  10. [The cellular receptors of exogenous RNA].

    PubMed

    Reniewicz, Patryk; Zyzak, Joanna; Siednienko, Jakub

    2016-04-21

    One of the key determinants of survival for organisms is proper recognition of exogenous and endogenous nucleic acids. Therefore, high eukaryotes developed a number of receptors that allow for discrimination between friend or foe DNA and RNA. Appearance of exogenous RNA in cytoplasm provides a signal of danger and triggers cellular responses that facilitate eradication of a pathogen. Recognition of exogenous RNA is additionally complicated by fact that large amount of endogenous RNA is present in cytoplasm Thus, number of different receptors, found in eukaryotic cells, is able to recognize that nucleic acid. First group of those receptors consist endosomal Toll like receptors, namely TLR3, TLR7, TLR8 and TLR13. Those receptors recognize RNA released from pathogens that enter the cell by endocytosis. The second group includes cytoplasmic sensors like PKR and the family of RLRs comprised of RIG-I, MDA5 and LGP2. Cytoplasmic receptors recognize RNA from pathogens invading the cell by non-endocytic pathway. In both cases binding of RNA by its receptors results in activation of the signalling cascades that lead to the production of interferon and other cytokines.

  11. Elongation of exogenous fatty acids by the bioluminescent bacterium Vibrio harveyi

    SciTech Connect

    Byers, D.M.

    1989-01-01

    Bioluminescent bacteria require myristic acid (C14:0) to produce the myristaldehyde substrate of the light-emitting luciferase reaction. Since both endogenous and exogenous C14:0 can be used for this purpose, the metabolism of exogenous fatty acids by luminescent bacteria has been investigated. Both Vibrio harveyi and Vibrio fischeri incorporated label from (1-14C)myristic acid (C14:0) into phospholipid acyl chains as well as into CO2. In contrast, Photobacterium phosphoreum did not exhibit phospholipid acylation or beta-oxidation using exogenous fatty acids. Unlike Escherichia coli, the two Vibrio species can directly elongate fatty acids such as octanoic (C8:0), lauric (C12:0), and myristic acid, as demonstrated by radio-gas liquid chromatography. The induction of bioluminescence in late exponential growth had little effect on the ability of V. harveyi to elongate fatty acids, but it did increase the amount of C14:0 relative to C16:0 labeled from (14C)C8:0. This was not observed in a dark mutant of V. harveyi that is incapable of supplying endogenous C14:0 for luminescence. Cerulenin preferentially decreased the labeling of C16:0 and of unsaturated fatty acids from all 14C-labeled fatty acid precursors as well as from (14C)acetate, suggesting that common mechanisms may be involved in elongation of fatty acids from endogenous and exogenous sources. Fatty acylation of the luminescence-related synthetase and reductase enzymes responsible for aldehyde synthesis exhibited a chain-length preference for C14:0, which also was indicated by reverse-phase thin-layer chromatography of the acyl groups attached to these enzymes. The ability of V. harveyi to activate and elongate exogenous fatty acids may be related to an adaptive requirement to metabolize intracellular C14:0 generated by the luciferase reaction during luminescence development.

  12. Effect of Exogenous Phytase Addition on Soil Phosphatase Activities: a Fluorescence Spectroscopy Study.

    PubMed

    Yang, Xiao-zhu; Chen, Zhen-hua; Zhang, Yu-lan; Chen, Li-jun

    2015-05-01

    The utilization of organic phosphorus (P) has directly or indirectly improved after exogenous phytase was added to soil. However, the mechanism by which exogenous phytase affected the soil phosphatases (phosphomonoesterase and phosphodiesterase) activities was not clear. The present work was aimed to study red soil, brown soil and cinnamon soil phosphomonoesterase (acid and alkaline) (AcP and AlP) and phosphodiesterase (PD) activities responding to the addition of exogenous phytase (1 g phytase/50 g air dry soil sample) based on the measurements performed via a fluorescence detection method combined with 96 microplates using a TECAN Infinite 200 Multi-Mode Microplate Reader. The results indicated that the acid phosphomonoesterase activity was significantly enhanced in red soil (p≤0. 01), while it was significantly reduced in cinnamon soil; alkaline phosphomonoesterase activity was significantly enhanced in cinnamon soil (p≤ 0. 01), while it was significantly reduced in red soil; phosphodiesterase activity was increased in three soils but it was significantly increased in brown soil (p≤0. 01) after the addition of exogenous phytase. The activities still remained strong after eight days in different soils, which indicated that exogenous phytase addition could be enhance soil phosphatases activities effectively. This effect was not only related to soil properties, such as pH and phosphorus forms, but might also be related to the excreted enzyme amount of the stimulating microorganism. Using fluorescence spectroscopy to study exogenous phytase addition influence on soil phosphatase activities was the first time at home and abroad. Compared with the conventional spectrophotometric method, the fluorescence microplate method is an accurate, fast and simple to use method to determine the relationships among the soil phosphatases activities.

  13. Enzyme Kinetics.

    ERIC Educational Resources Information Center

    Moe, Owen; Cornelius, Richard

    1988-01-01

    Conveys an appreciation of enzyme kinetic analysis by using a practical and intuitive approach. Discusses enzyme assays, kinetic models and rate laws, the kinetic constants (V, velocity, and Km, Michaels constant), evaluation of V and Km from experimental data, and enzyme inhibition. (CW)

  14. Enzyme Kinetics.

    ERIC Educational Resources Information Center

    Moe, Owen; Cornelius, Richard

    1988-01-01

    Conveys an appreciation of enzyme kinetic analysis by using a practical and intuitive approach. Discusses enzyme assays, kinetic models and rate laws, the kinetic constants (V, velocity, and Km, Michaels constant), evaluation of V and Km from experimental data, and enzyme inhibition. (CW)

  15. [Effects of exogenous AsA and GSH on the growth of Dianthus chinensis seedlings exposed to Cd].

    PubMed

    Ding, Ji-Jun; Liu, Shi-Liang; Pan, Yuan-Zhi; Li, Li

    2014-02-01

    A pot experiment was carried out under greenhouse condition to investigate the effects of different concentrations (0, 20, 40, 60, 80 and 100 mg x L(-1)) of exogenous AsA, GSH on Dianthus chinensis seedlings which were stressed by 50 mg x kg(-1) Cd in the soil. The results indicated that 50 mg x kg(-1) of Cd significantly inhibited the growth of D. chinensis seedlings. An appropriate concentration of exogenous AsA significantly improved the biomass, plant height, tiller number, GAT and APX activities, and AsA and GSH contents. However, with the increase of exogenous AsA concentration, the ameliorating effect decreased and prooxidant effect occurred. Exogenous GSH could replenish the non-enzymatic antioxidants of D. chinensis seedlings, but the changes of antioxidant enzyme activities were relatively slight. The main mechanisms of GSH to alleviate Cd toxicity might be promoting root PCs synthesis, thereby reducing the Cd concentration in the seedlings. Both 35-45 mg x L(-1) exogenous AsA and 55-65 mg x L(-1) exogenous GSH could alleviate the Cd toxicity on D. chinensis seedlings, and the former was superior to the latter.

  16. Exogenous carbonaceous matter in ancient martian sediments

    NASA Astrophysics Data System (ADS)

    Mojzsis, S. J.; Abramov, O.; Kereszturi, A.

    2015-12-01

    We re-evaluate the early evolution of an organic-matter rich (~10 wt. %) interplanetary dust particle flux to early Mars. Our work builds upon physical models that rely on plausible sources of exogenous debris and their dynamical rates of decay, the martian cratering record, and preservation of Noachian-Hesperian sedimentary units that have the potential to host organics. Post primary-accretionary scenarios that would have delivered abundant exogenous carbon to Mars can be imagined in two ways: a simple exponential decay with an approximately 100 Myr half-life, or as a "Sawtooth" timeline characterized by both faster-than-exponential decay from primary accretion and reduced total delivered mass. Indications are that a late bombardment spike was superposed on an otherwise broadly monotonic decline from primary accretion, of which two types are explored: a classical "Late Heavy Bombardment" (LHB) peak of impactors centered at ca. 3950 Ma and lasting 100 Myr, and a protracted bombardment typified by a sudden increase in impactor flux at ca. 4240-4100 Ma with a correspondingly longer decay time (400 Myr). Numerical models for each of the four bombardment scenarios explored in this work shows that exogenous organic matter could be a significant component of Noachian (ca. 4200-3700 Ma) and pre-Noachian (4500-4200 Ma) sediments. The discovery of organic-matter in martian sediments will be obfuscated by material of extra-areological origin. We predict that an earmark for the origin of this carbon would be correlated siderophile element abundances (e.g. Ni, Cr, and the platinoids). A time-dependent compositional relationship of C:HSEs would allow us to derive a chemochronology for pre-Hesperian (pre-3700 Ma) sedimentary units.

  17. Exogenous kallikrein protects against diabetic nephropathy.

    PubMed

    Liu, Wenjuan; Yang, Yeping; Liu, Yemei; Lu, Xiaolan; Guo, Shizhe; Wu, Meng; Wang, Meng; Yan, Linling; Wang, Qinghua; Zhao, Xiaolong; Tong, Xian; Hu, Ji; Li, Yiming; Hu, Renming; Stanton, Robert C; Zhang, Zhaoyun

    2016-11-01

    The kallikrein-kinin system has been shown to be involved in the development of diabetic nephropathy, but specific mechanisms are not fully understood. Here, we determined the renal-protective role of exogenous pancreatic kallikrein in diabetic mice and studied potential mechanisms in db/db type 2 diabetic and streptozotocin-induced type 1 diabetic mice. After the onset of diabetes, mice were treated with either pancreatic kallikrein (db/db+kallikrein, streptozotocin+kallikrein) or saline (db/db+saline, streptozotocin+saline) for 16 weeks, while another group of streptozotocin-induced diabetic mice received the same treatment after onset of albuminuria (streptozotocin'+kallikrein, streptozotocin'+saline). Db/m littermates or wild type mice were used as non-diabetic controls. Pancreatic kallikrein had no effects on body weight, blood glucose and blood pressure, but significantly reduced albuminuria among all three groups. Pathological analysis showed that exogenous kallikrein decreased the thickness of the glomerular basement membrane, protected against the effacement of foot process, the loss of endothelial fenestrae, and prevented the loss of podocytes in diabetic mice. Renal fibrosis, inflammation and oxidative stress were reduced in kallikrein-treated mice compared to diabetic controls. The expression of kininogen1, tissue kallikrein, kinin B1 and B2 receptors were all increased in the kallikrein-treated compared to saline-treated mice. Thus, exogenous pancreatic kallikrein both prevented and ameliorated diabetic nephropathy, which may be mediated by activating the kallikrein-kinin system.

  18. Enzyme Informatics

    PubMed Central

    Alderson, Rosanna G.; Ferrari, Luna De; Mavridis, Lazaros; McDonagh, James L.; Mitchell, John B. O.; Nath, Neetika

    2012-01-01

    Over the last 50 years, sequencing, structural biology and bioinformatics have completely revolutionised biomolecular science, with millions of sequences and tens of thousands of three dimensional structures becoming available. The bioinformatics of enzymes is well served by, mostly free, online databases. BRENDA describes the chemistry, substrate specificity, kinetics, preparation and biological sources of enzymes, while KEGG is valuable for understanding enzymes and metabolic pathways. EzCatDB, SFLD and MACiE are key repositories for data on the chemical mechanisms by which enzymes operate. At the current rate of genome sequencing and manual annotation, human curation will never finish the functional annotation of the ever-expanding list of known enzymes. Hence there is an increasing need for automated annotation, though it is not yet widespread for enzyme data. In contrast, functional ontologies such as the Gene Ontology already profit from automation. Despite our growing understanding of enzyme structure and dynamics, we are only beginning to be able to design novel enzymes. One can now begin to trace the functional evolution of enzymes using phylogenetics. The ability of enzymes to perform secondary functions, albeit relatively inefficiently, gives clues as to how enzyme function evolves. Substrate promiscuity in enzymes is one example of imperfect specificity in protein-ligand interactions. Similarly, most drugs bind to more than one protein target. This may sometimes result in helpful polypharmacology as a drug modulates plural targets, but also often leads to adverse side-effects. Many cheminformatics approaches can be used to model the interactions between druglike molecules and proteins in silico. We can even use quantum chemical techniques like DFT and QM/MM to compute the structural and energetic course of enzyme catalysed chemical reaction mechanisms, including a full description of bond making and breaking. PMID:23116471

  19. Marine enzymes.

    PubMed

    Debashish, Ghosh; Malay, Saha; Barindra, Sana; Joydeep, Mukherjee

    2005-01-01

    Marine enzyme biotechnology can offer novel biocatalysts with properties like high salt tolerance, hyperthermostability, barophilicity, cold adaptivity, and ease in large-scale cultivation. This review deals with the research and development work done on the occurrence, molecular biology, and bioprocessing of marine enzymes during the last decade. Exotic locations have been accessed for the search of novel enzymes. Scientists have isolated proteases and carbohydrases from deep sea hydrothermal vents. Cold active metabolic enzymes from psychrophilic marine microorganisms have received considerable research attention. Marine symbiont microorganisms growing in association with animals and plants were shown to produce enzymes of commercial interest. Microorganisms isolated from sediment and seawater have been the most widely studied, proteases, carbohydrases, and peroxidases being noteworthy. Enzymes from marine animals and plants were primarily studied for their metabolic roles, though proteases and peroxidases have found industrial applications. Novel techniques in molecular biology applied to assess the diversity of chitinases, nitrate, nitrite, ammonia-metabolizing, and pollutant-degrading enzymes are discussed. Genes encoding chitinases, proteases, and carbohydrases from microbial and animal sources have been cloned and characterized. Research on the bioprocessing of marine-derived enzymes, however, has been scanty, focusing mainly on the application of solid-state fermentation to the production of enzymes from microbial sources.

  20. Denitrifying SUP05 Require Exogenous Nitrogen

    NASA Astrophysics Data System (ADS)

    Shah, V.; Chang, B. X.; Morris, R. M.

    2016-02-01

    Members of the SUP05 clade of gamma-proteobacteria are among the most abundant chemoautotrophs in the ocean. Environmental sequencing studies suggest that they have critical roles in mediating carbon fixation, denitrification, and sulfur oxidation in oxygen minimum zones (OMZs). They have evaded cultivation and little is known about the specific growth requirements or substrate ranges that determine their abundance, distribution and impact on marine biogeochemical cycles. We evaluated the genetic potential of an isolate from the SUP05 clade "Ca. Thioglobus autotrophica strain EF1" to fix carbon, reduce nitrogen and oxidize sulfur under anaerobic growth conditions. Growth experiments support genomic predictions, indicating that strain EF1 is a facultatively anaerobic sulfur-oxidizing chemolithoautotroph that reduces nitrate to nitrite and nitric oxide to nitrous oxide. These experiments also revealed that strain EF1 is limited for growth by ammonium, which indicates that it requires an exogenous source of nitrogen for biosynthesis. Evidence that SUP05 cells produce nitrite and nitrous oxide and require exogenous nitrogen suggests that they have important roles in nitrogen cycling and that their growth is ultimately limited by the degradation of sinking organic matter.

  1. Understanding Enzymes.

    ERIC Educational Resources Information Center

    Sinnott, M. L.

    1979-01-01

    Describes the way enzymes operate through reaction energetics, and explains that most of the catalytic power of enzymes lies in the strong noncovalent forces responsible for initial binding of substrate, which are only manifested at the transition state of the reaction. (Author/GA)

  2. Enzymes, Industrial

    USDA-ARS?s Scientific Manuscript database

    Enzymes serve key roles in numerous biotechnology processes and products that are commonly encountered in the forms of food and beverages, cleaning supplies, clothing, paper products, transportation fuels, pharmaceuticals, and monitoring devices. Enzymes can display regio- and stereo-specificity, p...

  3. Exogenous amino acids as fuel in shock.

    PubMed

    Daniel, A M; Kapadia, B; MacLean, L D

    1982-01-01

    It has been suggested that in shock branched-chain amino acids are preferentially oxidized resulting in continued proteolysis and stimulated gluconeogenesis. To determine if exogenous amino acids could be used as fuel in shock, dogs rendered hypotensive by controlled cardiac tamponade and normotensive controls were infused with amino acid mixtures and individual amino acids. When Nephramine, a mixture rich in branched-chain amino acids, was infused, plasma alpha-amino nitrogen levels rose but urea output did not increase in either the control state or in shock, suggesting that these amino acids were not rapidly deaminated to serve as fuels. Travasol, which in addition contained large amounts of alanine and glycine, tripled urea output in the controls and doubled it in shock. The limit of urea production was reached in both groups at 35 mumoles urea/minute/kg. In the Travasol-infused animals plasma alpha-amino nitrogen levels were maintained in normotension but rose sharply in shock. When glycine alone was infused into five dogs in shock urea production rate was 30.6 + 2.1 mumoles/minute/kg; with alanine the same value was 22.5 + 2.2 mumoles/minute/kg. In both cases plasma alpha-amino nitrogen levels were high, suggesting that transport of these amino acids into the cell was slow in shock. In four dogs in shock glycine-14C was added to the glycine infusate as a tracer. At radioactive equilibrium 28% of the label infused appeared in CO2; another 22% appeared in glucose. It is concluded that of all the amino acids tested only glycine and alanine are deaminated rapidly enough to serve as exogenous fuels in shock.

  4. The future of exogenous surfactant therapy.

    PubMed

    Willson, Douglas F; Notter, Robert H

    2011-09-01

    Since the identification of surfactant deficiency as the putative cause of the infant respiratory distress syndrome (RDS) by Avery and Mead in 1959, our understanding of the role of pulmonary surfactant in respiratory physiology and the pathophysiology of acute lung injury (ALI) has advanced substantially. Surfactant replacement has become routine for the prevention and treatment of infant RDS and other causes of neonatal lung injury. The role of surfactant in lung injury beyond the neonatal period, however, has proven more complex. Relative surfactant deficiency, dysfunction, and inhibition all contribute to the disturbed physiology seen in ALI and acute respiratory distress syndrome (ARDS). Consequently, exogenous surfactant, while a plausible therapy, has proven to be less effective in ALI/ARDS than in RDS, where simple deficiency is causative. This failure may relate to a number of factors, among them inadequacy of pharmaceutical surfactants, insufficient dosing or drug delivery, poor drug distribution, or simply an inability of the drug to substantially impact the underlying pathophysiology of ALI/ARDS. Both animal and human studies suggest that direct types of ALI (eg, aspiration, pneumonia) may be more responsive to surfactant therapy than indirect lung injury (eg, sepsis, pancreatitis). Animal studies are needed, however, to further clarify aspects of drug composition, timing, delivery, and dosing before additional human trials are pursued, as the results of human trials to date have been inconsistent and largely disappointing. Further study and perhaps the development of more robust pharmaceutical surfactants offer promise that exogenous surfactant will find a place in our armamentarium of treatment of ALI/ARDS in the future.

  5. Exogenous calcium improves viability of biocontrol yeasts under heat stress by reducing ROS accumulation and oxidative damage of cellular protein.

    PubMed

    An, Bang; Li, Boqiang; Qin, Guozheng; Tian, Shiping

    2012-08-01

    In this article, we investigated the effect of exogenous calcium on improving viability of Debaryomyces hansenii and Pichia membranaefaciens under heat stress, and evaluated the role of calcium in reducing oxidant damage of proteins in the yeast cells. The results indicated that high concentration of exogenous calcium in culture medium was beneficial for enhancing the tolerance of the biocontrol yeasts to heat stress. The possible mechanism of calcium improving the viability of yeasts was attributed to enhancement of antioxidant enzyme activities, decrease in ROS accumulation and reduction of oxidative damage of intracellular protein in yeast cells under heat stress. D. hansenii is more sensitive to calcium as compared to P. membranaefaciens. Our results suggest that application of exogenous calcium combined with biocontrol yeasts is a practical approach for the control of postharvest disease in fruit.

  6. Exogenous spermidine is enhancing tomato tolerance to salinity-alkalinity stress by regulating chloroplast antioxidant system and chlorophyll metabolism.

    PubMed

    Li, Jianming; Hu, Lipan; Zhang, Li; Pan, Xiongbo; Hu, Xiaohui

    2015-12-29

    Salinity-alkalinity stress is known to adversely affect a variety of processes in plants, thus inhibiting growth and decreasing crop yield. Polyamines protect plants against a variety of environmental stresses. However, whether exogenous spermidine increases the tolerance of tomato seedlings via effects on chloroplast antioxidant enzymes and chlorophyll metabolism is unknown. In this study, we examined the effect of exogenous spermidine on chlorophyll synthesis and degradation pathway intermediates and related enzyme activities, as well as chloroplast ultrastructure, gene expression, and antioxidants in salinity-alkalinity-stressed tomato seedlings. Salinity-alkalinity stress disrupted chlorophyll metabolism and hindered uroorphyrinogen III conversion to protoporphyrin IX. These effects were more pronounced in seedlings of cultivar Zhongza No. 9 than cultivar Jinpengchaoguan. Under salinity-alkalinity stress, exogenous spermidine alleviated decreases in the contents of total chlorophyll and chlorophyll a and b in seedlings of both cultivars following 4 days of stress. With extended stress, exogenous spermidine reduced the accumulation of δ-aminolevulinic acid, porphobilinogen, and uroorphyrinogen III and increased the levels of protoporphyrin IX, Mg-protoporphyrin IX, and protochlorophyllide, suggesting that spermidine promotes the conversion of uroorphyrinogen III to protoporphyrin IX. The effect occurred earlier in cultivar Jinpengchaoguan than in cultivar Zhongza No. 9. Exogenous spermidine also alleviated the stress-induced increases in malondialdehyde content, superoxide radical generation rate, chlorophyllase activity, and expression of the chlorophyllase gene and the stress-induced decreases in the activities of antioxidant enzymes, antioxidants, and expression of the porphobilinogen deaminase gene. In addition, exogenous spermidine stabilized the chloroplast ultrastructure in stressed tomato seedlings. The tomato cultivars examined exhibited different

  7. Exogenous glutathione improves high root-zone temperature tolerance by modulating photosynthesis, antioxidant and osmolytes systems in cucumber seedlings

    PubMed Central

    Ding, Xiaotao; Jiang, Yuping; He, Lizhong; Zhou, Qiang; Yu, Jizhu; Hui, Dafeng; Huang, Danfeng

    2016-01-01

    To investigate the physiological responses of plants to high root-zone temperature (HT, 35 °C) stress mitigated by exogenous glutathione (GSH), cucumber (Cucumis sativus L.) seedlings were exposed to HT with or without GSH treatment for 4 days and following with 4 days of recovery. Plant physiological variables, growth, and gene expression related to antioxidant enzymes and Calvin cycle were quantified. The results showed that HT significantly decreased GSH content, the ratio of reduced to oxidized glutathione (GSH/GSSG), chlorophyll content, photosynthesis and related gene expression, shoot height, stem diameter, as well as dry weight. The exogenous GSH treatment clearly lessened the HT stress by increasing the above variables. Meanwhile, HT significantly increased soluble protein content, proline and malondialdehyde (MDA) content as well as O2•− production rate, the gene expression and activities of antioxidant enzymes. The GSH treatment remarkably improved soluble protein content, proline content, antioxidant enzymes activities, and antioxidant enzymes related gene expression, and reduced the MDA content and O2•− production rate compared to no GSH treatment in the HT condition. Our results suggest that exogenous GSH enhances cucumber seedling tolerance of HT stress by modulating the photosynthesis, antioxidant and osmolytes systems to improve physiological adaptation. PMID:27752105

  8. Roles of exogenous divalent metals in the nucleolytic activity of Cu,Zn superoxide dismutase.

    PubMed

    Jiang, Wei; Han, Yingchun; Pan, Qunhui; Shen, Tao; Liu, Changlin

    2007-04-01

    It is well known that the wild type Cu,Zn superoxide dismutase (holo SOD) catalyzes the conversion of superoxide anion to peroxide hydrogen and dioxygen. However, a new function of holo SOD, i.e., nucleolytic activity has been found [W. Jiang, T. Shen, Y. Han, Q. Pan, C. Liu, J. Biol. Inorg. Chem. 11 (2006) 835-848], which is linked to the incorporation of exogenous divalent metals into the enzyme-DNA complex. In this study, the roles of exogenous divalent metals in the nucleolytic activity were explored in detail by a series of biochemical experiments. Based on a non-equivalent multi-site binding model, affinity of a divalent metal for the enzyme-DNA complex was determined by absorption titration, indicating that the complex can provide at least a high and a low affinity site for the metal ion. These mean that the holo SOD may use a "two exogenous metal ion pathway" as a mechanism in which both metal ions are directly involved in the catalytic process of DNA cleavage. In addition, the pH versus DNA cleavage rate profiles can be fitted to two ionizing-group models, indicating the presence of a general acid and a general base in catalysis. A model that requires histidine residues, metal-bound water molecules and two hydrated metal ions to operate in concert could be used to interpret the catalysis of DNA hydrolysis, supported by the dependences of loss of the nucleolytic activity on time and on the concentration of the specific chemical modifier to the histidine residues on the enzyme.

  9. Explaining Cigarette Smoking: An Endogenous-Exogenous Analysis.

    ERIC Educational Resources Information Center

    McKillip, Jack

    Kruglanski's endogenous-exogenous partition, when applied to reasons given by smokers for smoking cigarettes, distinguishes two types of actions: (1) endogenous reasons implying that the behavior of consuming the cigarette is the goal of the action and the actor is positive toward the behavior, and (2) exogenous reasons implying that the behavior…

  10. Exogenous glutamine--compensating a shortage?

    PubMed

    Tjader, Inga; Berg, Agneta; Wernerman, Jan

    2007-09-01

    There is still insufficient knowledge about in vivo glutamine metabolism and the regulation of glutamine homeostasis, particularly during metabolic stress. A shortage of glutamine is associated with a poor outcome, whereas for septic patients in the intensive care unit an increased availability of glutamine can prevent mortality and morbidity. Cellular defense mechanisms depend on normal glutamine availability to respond adequately to challenges presented. In clinical practice, treatment of plasma glutamine depletion improves outcome for the critically ill patient. An increased metabolic need for glutamine must be met with an increased consumption of glutamine. Ordinary food is not a sufficient supply of glutamine for the patient with multiple organ failure in the intensive care unit, but that is also true for several other nutrients. It is, therefore, debatable whether an exogenous supply of glutamine should be regarded as a pharmacologic treatment or whether this just represents physiology in stressed states. If a glutamine shortage requires substitution, supplementation to the normal concentration is compensation of a shortage, and the effect is physiological.

  11. Short Term Exogenic Climate Change Forcing

    NASA Astrophysics Data System (ADS)

    Krahenbuhl, Daniel

    Several short term exogenic forcings affecting Earth's climate are but recently identified. Lunar nutation periodicity has implications for numerical meteorological prediction. Abrupt shifts in solar wind bulk velocity, particle density, and polarity exhibit correlation with terrestrial hemispheric vorticity changes, cyclonic strengthening and the intensification of baroclinic disturbances. Galactic Cosmic ray induced tropospheric ionization modifies cloud microphysics, and modulates the global electric circuit. This dissertation is constructed around three research questions: (1): What are the biweekly declination effects of lunar gravitation upon the troposphere? (2): How do United States severe weather reports correlate with heliospheric current sheet crossings? and (3): How does cloud cover spatially and temporally vary with galactic cosmic rays? Study 1 findings show spatial consistency concerning lunar declination extremes upon Rossby longwaves. Due to the influence of Rossby longwaves on synoptic scale circulation, our results could theoretically extend numerical meteorological forecasting. Study 2 results indicate a preference for violent tornadoes to occur prior to a HCS crossing. Violent tornadoes (EF3+) are 10% more probable to occur near, and 4% less probable immediately after a HCS crossing. The distribution of hail and damaging wind reports do not mirror this pattern. Polarity is critical for the effect. Study 3 results confirm anticorrelation between solar flux and low-level marine-layer cloud cover, but indicate substantial regional variability between cloud cover altitude and GCRs. Ultimately, this dissertation serves to extend short term meteorological forecasting, enhance climatological modeling and through analysis of severe violent weather and heliospheric events, protect property and save lives.

  12. Interactions between endogenous and exogenous attention on cortical visual processing.

    PubMed

    Hopfinger, Joseph B; West, Vicki M

    2006-06-01

    Sensory processing is affected by both endogenous and exogenous mechanisms of attention, although how these mechanisms interact in the brain has remained unclear. In the present study, we recorded event-related potentials (ERPs) to investigate how multiple stages of information processing in the brain are affected when endogenous and exogenous mechanisms are concurrently engaged. We found that the earliest stage of cortical visual processing, the striate-cortex-generated C1, was immune to attentional modulation, even when endogenous and exogenous attention converged on a common location. The earliest stage of processing to be affected in this experiment was the late phase of the extrastriate-cortex-generated P1 component, which was dominated by exogenous attention. Processing at this stage was enhanced by exogenous attention, regardless of where endogenous attention had been oriented. Endogenous attention, however, dominated a later, higher-order stage of processing indexed by an enhancement of the P300 that was unaffected by exogenous attention. Critically, between these early and late stages, an interaction was found wherein endogenous and exogenous attention produced distinct, and overlapping, effects on information processing. At the same time that exogenous attention was producing an extended enhancement of the late-P1, endogenous attention was enhancing the occipital-parietal N1 component. These results provide neurophysiological support for theories suggesting that endogenous and exogenous mechanisms represent two attention systems that can affect information processing in the brain in distinct ways. Furthermore, these data provide new evidence regarding the precise stages of neural processing that are, and are not, affected when endogenous and exogenous attentions interact.

  13. Human CD4+ T cells require exogenous cystine for glutathione and DNA synthesis.

    PubMed

    Levring, Trine B; Kongsbak, Martin; Rode, Anna K O; Woetmann, Anders; Ødum, Niels; Bonefeld, Charlotte Menné; Geisler, Carsten

    2015-09-08

    Adaptive immune responses require activation and expansion of antigen-specific T cells. Whereas early T cell activation is independent of exogenous cystine (Cys2), T cell proliferation is dependent of Cys2. However, the exact roles of Cys2 in T cell proliferation still need to be determined. The aim of this study was to elucidate why activated human T cells require exogenous Cys2 in order to proliferate. We activated purified naïve human CD4+ T cells and found that glutathione (GSH) levels and DNA synthesis were dependent on Cys2 and increased in parallel with increasing concentrations of Cys2. Vice-versa, the GSH synthesis inhibitor L-buthionine-sulfoximine (BSO) and inhibition of Cys2 uptake with glutamate inhibited GSH and DNA synthesis in parallel. We further found that thioredoxin (Trx) can partly substitute for GSH during DNA synthesis. Finally, we show that GSH or Trx is required for the activity of ribonucleotide reductase (RNR), the enzyme responsible for generation of the deoxyribonucleotide DNA building blocks. In conclusion, we show that activated human T cells require exogenous Cys2 to proliferate and that this is partly explained by the fact that Cys2 is required for production of GSH, which in turn is required for optimal RNR-mediated deoxyribonucleotide synthesis and DNA replication.

  14. Exogenous surfactant suppresses inflammation in experimental endotoxin-induced lung injury.

    PubMed

    Mittal, Neha; Sanyal, Sankar Nath

    2009-01-01

    Our objective was to evaluate the anti-inflammatory effects of exogenous surfactant and surfactant phospholipids on the lipopolysaccharide (LPS)-induced lung injury. Exogenous surfactant (porcine surfactant) and surfactant phospholipid (dipalmitoyl phospholipid DPPC, hexadecanol, tylaxopol) were instilled intratracheally with LPS in rats. Expression of surfactant apoproteins (SP-A) and the cyclooxygenase enzymes (COX-1 and -2) was studied by immunohistochemistry, and apoptosis was analyzed by in situ terminal dUTP nick end labeling TUNEL assay. The intracellular reactive oxygen species (ROS) was measured in the isolated macrophages by fluorescence measurement with dichlorofluorescein diacetate (DCFH-DA). LPS-induced oxidative burst and apoptosis at 72 hours were reduced by both porcine and synthetic surfactant. SP-A as well as COX-1 and -2 expressions were suppressed with synthetic surfactant treatment, whereas with porcine surfactant (P-SF) the SP-A expression was enhanced in response to LPS administration. These results indicate that exogenous surfactant inhibits LPS-induced inflammation. This anti-inflammatory activity may be an important outcome of surfactant therapy in endotoxin-induced respiratory distress.

  15. Engineered Assimilation of Exogenous and Endogenous Formate in Escherichia coli.

    PubMed

    Yishai, Oren; Goldbach, Leander; Tenenboim, Hezi; Lindner, Steffen N; Bar-Even, Arren

    2017-09-15

    Decoupling biorefineries from land use and agriculture is a major challenge. As formate can be produced from various sources, e.g., electrochemical reduction of CO2, microbial formate-assimilation has the potential to become a sustainable feedstock for the bioindustry. However, organisms that naturally grow on formate are limited by either a low biomass yield or by a narrow product spectrum. The engineering of a model biotechnological microbe for growth on formate via synthetic pathways represents a promising approach to tackle this challenge. Here, we achieve a critical milestone for two such synthetic formate-assimilation pathways in Escherichia coli. Our engineering strategy involves the division of the pathways into metabolic modules; the activity of each module-providing at least one essential building block-is selected for in an appropriate auxotrophic strain. We demonstrate that formate can serve as a sole source of all cellular C1-compounds, including the beta-carbon of serine. We further show that by overexpressing the native threonine cleavage enzymes, the entire cellular glycine requirement can be provided by threonine biosynthesis and degradation. Together, we confirm the simultaneous activity of all pathway segments of the synthetic serine-threonine cycle. We go beyond the formate bioeconomy concept by showing that, under anaerobic conditions, formate produced endogenously by pyruvate formate-lyase can replace exogenous formate. The resulting prototrophic strain constitutes a substantial rewiring of central metabolism in which C1, glycine, and serine metabolism proceed via a unique set of pathways. This strain can serve as a platform for future metabolic-engineering efforts and could further pave the way for investigating the plasticity of metabolic networks.

  16. P450 enzymes of estrogen metabolism.

    PubMed

    Martucci, C P; Fishman, J

    1993-01-01

    Endogenous and exogenous estrogens undergo extensive oxidative metabolism by specific cytochrome P450 enzymes. Certain drugs and xenobiotics have been found to be potent inducers of estrogen hydroxylating enzymes with C-2 hydroxylase induction being greater than that of C-16 hydroxylase. Oxygenated estrogen metabolites have different biological activities, with C-2 metabolites having limited or no activity and C-4 and C-16 metabolites having similar potency to estradiol. Pathophysiological roles for some of the oxygenated estrogen metabolites have been proposed, e.g. 16 alpha-hydroxyestrone and 4-hydroxyestrone. These reactive estrogens are capable of damaging cellular proteins and DNA and may be carcinogenic in specific cells.

  17. [Roles of exogenous spermidine in improving Salvinia natans tolerance towards cadmium stress].

    PubMed

    Xu, Qin-song; Shi, Guo-xin; Wang, Hong-xia; Yang, Hai-yan; Zhao, Juan; Xu, Ye

    2008-11-01

    In this study, the effects of foliar spraying different concentration (0.05-1 mmol L(-1)) spermidine (Spd) on the photosynthetic pigments, soluble protein content, antioxidant system, and mineral nutrition of Salvinia natans leaves under cadmium (Cd) stress were investigated, aimed to approach the action mechanisms of exogenous polyamines (PAs) in improving the adaptability of aquatic plants to heavy metals stress. The results showed that exogenous Spd could markedly mitigate the Cd stress to S. natans. It retarded the chlorosis, with chlorophyll a/b and total chlorophyll content increased by 18.97% and 43.96%, respectively, and increased the soluble protein content by 27.83%, compared with the control. SDS-PAGE revealed that the increase of soluble protein content was mainly of the expression increase of 5 polypeptides with apparent molecular weights 202.15, 77.67, 52.69, 41.83, and 25.35 kD. Exogenous Spd increased the activities of antioxidant enzymes SOD, POD and CAT and the contents of low molecular weight protective compounds AsA, GSH and Car, with an average increase of 12.44%, 66.90% and 51.23%, and 11.21%, 17.60% and 24.81%, respectively, and effectively maintained the balanced absorption of P, K, Fe, Na, Mg, Zn and Mn (with exception of Ca). In general, the optimum concentration range of exogenous Spd was 0.05-0.1 mmol x L(-1), which could enhance the resistance of S. natans to Cd toxicity by improving photosynthesis, stimulating the expression of protein, promoting the activity/content of antioxidant system, and keeping the balanced absorption of nutrient elements, etc.

  18. The Effect of Exogenous Spermidine Concentration on Polyamine Metabolism and Salt Tolerance in Zoysiagrass (Zoysia japonica Steud) Subjected to Short-Term Salinity Stress

    PubMed Central

    Li, Shucheng; Jin, Han; Zhang, Qiang

    2016-01-01

    Salt stress, particularly short-term salt stress, is among the most serious abiotic factors limiting plant survival and growth in China. It has been established that exogenous spermidine (Spd) stimulates plant tolerance to salt stress. The present study utilized two zoysiagrass cultivars commonly grown in China that exhibit either sensitive (cv. Z081) or tolerant (cv. Z057) adaptation capacity to salt stress. The two cultivars were subjected to 200 mM salt stress and treated with different exogenous Spd concentrations for 8 days. Polyamine [diamine putrescine (Put), tetraamine spermine (Spm), and Spd], H2O2 and malondialdehyde (MDA) contents and polyamine metabolic (ADC, ODC, SAMDC, PAO, and DAO) and antioxidant (superoxide dismutase, catalase, and peroxidase) enzyme activities were measured. The results showed that salt stress induced increases in Spd and Spm contents and ornithine decarboxylase (ODC), S-adenosylmethionine decarboxylase (SAMDC), and diamine oxidase (DAO) activities in both cultivars. Exogenous Spd application did not alter polyamine contents via regulation of polyamine-degrading enzymes, and an increase in polyamine biosynthetic enzyme levels was observed during the experiment. Increasing the concentration of exogenous Spd resulted in a tendency of the Spd and Spm contents and ODC, SAMDC, DAO, and antioxidant enzyme activities to first increase and then decrease in both cultivars. H2O2 and MDA levels significantly decreased in both cultivars treated with Spd. Additionally, in both cultivars, positive correlations between polyamine biosynthetic enzymes (ADC, SAMDC), DAO, and antioxidant enzymes (SOD, POD, CAT), but negative correlations with H2O2 and MDA levels, and the Spd + Spm content were observed with an increase in the concentration of exogenous Spd. PMID:27582752

  19. Zinc Enzymes.

    ERIC Educational Resources Information Center

    Bertini, I.; And Others

    1985-01-01

    Discusses the role of zinc in various enzymes concerned with hydration, hydrolysis, and redox reactions. The binding of zinc to protein residues, properties of noncatalytic zinc(II) and catalytic zinc, and the reactions catalyzed by zinc are among the topics considered. (JN)

  20. Food Enzymes

    ERIC Educational Resources Information Center

    McBroom, Rachel; Oliver-Hoyo, Maria T.

    2007-01-01

    Many students view biology and chemistry as two unrelated, separate sciences; how these courses are generally taught in high schools may do little to change that impression. The study of enzymes provide a great opportunity for both biology and chemistry teachers to share with students the interdisciplinary nature of science. This article describes…

  1. Zinc Enzymes.

    ERIC Educational Resources Information Center

    Bertini, I.; And Others

    1985-01-01

    Discusses the role of zinc in various enzymes concerned with hydration, hydrolysis, and redox reactions. The binding of zinc to protein residues, properties of noncatalytic zinc(II) and catalytic zinc, and the reactions catalyzed by zinc are among the topics considered. (JN)

  2. Engineering enzymes.

    PubMed

    Dutton, P Leslie; Moser, Christopher C

    2011-01-01

    Fundamental research into bioinorganic catalysis of the kind presented at this Faraday Discussion has the potential to turn inspiration drawn from impressive natural energy and chemical transformations into artificial catalyst constructions useful to mankind. Creating bio-inspired artificial constructions requires a level of understanding well beyond simple description of structures and mechanisms of natural enzymes. To be useful, such description must be augmented by a practical sense of structural and energetic engineering tolerances of the mechanism. Significant barriers to achieving an engineering understanding of enzyme mechanisms arise from natural protein complexity. In certain cases we can surmount these barriers to understanding, such as natural electron tunneling, coupling of electron tunneling to light capture and proton exchange as well as simpler bond breaking redox catalysis. Hope for similar solutions of more complex bioinorganic enzymes is indicated in several papers presented in this Discussion. Armed with an engineering understanding of mechanism, the current serious frustrations to successful creation of functional artificial proteins that are rooted in protein complexity can fall away. Here we discuss the genetic and biological roots of protein complexity and show how to dodge and minimize the effects of complexity. In the best-understood cases, artificial enzymes can be designed from scratch using the simplest of protein scaffolds.

  3. Food Enzymes

    ERIC Educational Resources Information Center

    McBroom, Rachel; Oliver-Hoyo, Maria T.

    2007-01-01

    Many students view biology and chemistry as two unrelated, separate sciences; how these courses are generally taught in high schools may do little to change that impression. The study of enzymes provide a great opportunity for both biology and chemistry teachers to share with students the interdisciplinary nature of science. This article describes…

  4. Alleviating effects of exogenous NO on tomato seedlings under combined Cu and Cd stress.

    PubMed

    Wang, Yi-Jun; Dong, Yu-Xiu; Wang, Juan; Cui, Xiu-Min

    2016-03-01

    To investigate the effect of NO on the different origin and regulation of oxidative stress of Cu and/or Cd, tomato seedlings were treated with Cu, Cd, or Cu + Cd in a nutrient solution culture system. The main effect of Cu(2+) was a significant reduction in root activity and nitrate reductase (NR) activity, which was similar to that under 50 μM Cd treatment, but promoted Cu accumulation. The supply of Cu under Cd treatment decreased Cd concentration, while not altered Cu concentration by contrast with Cu treatment, which is suggestive of a replacement of Cu(2+) with Cd(2+) and effective decrease in the boiotoxicity of 50 μM Cd(2+) to tomato seedlings. However, NO alleviated the restriction to NR activity significantly and made the biomass of tomato seedlings recover under Cd treatment, and also increased root activity under Cu and Cu + Cd treatment. Exogenous NO markedly reduced the absorption and transportation of Cu but did not obviously change the translocation of Cd to the aboveground parts under Cu + Cd treatment. Both metals induced lipid peroxidation via the decreasing activation of antioxidant enzymes. The antioxidant enzyme system worked differently under Cu, Cd, or Cu + Cd stress. The activities of peroxidase (POD) and catalase (CAT) were higher under single Cd stress than under the control. Meanwhile, Cu + Cd treatment decreased the activities of POD, superoxide dismutase (SOD), and ascorbic acid peroxidase (APX). Exogenous NO increased POD and SOD activities in the leaves and roots, and CAT activity in the roots under combined Cu and Cd stress. These results suggest that a different response and regulation mechanism that involves exogenous NO is present in tomato seedlings under Cu and Cd stress.

  5. Feed enzyme technology: present status and future developments.

    PubMed

    Ravindran, Velmurugu; Son, Jang-Ho

    2011-05-01

    Exogenous enzymes are now well accepted as a class of feed additives in diet formulations for poultry and pigs to overcome the negative effects of anti-nutritional factors, and to improve digestion of dietary components and animal performance. An overview of the current status of feed enzyme technology, including the different type of enzymes and modes of action, is provided. Variable response to enzyme supplementation is an important reason limiting the widespread acceptance of feed enzymes. The major reasons contributing to these variable responses are discussed. Main features of the next generation of feed enzymes and the various trends that will drive the future use of enzymes are highlighted. The use of feed enzymes in poultry and pig feed formulations is expected to increase in the future and this will be driven by on-going changes in the world animal production. Aquaculture and ruminant industries are emerging markets for exogenous feed enzymes. The article presents some promising patents on feed enzyme technology.

  6. Impact of exogenous ascorbic acid on biochemical activities of rice callus treated with salt stress

    NASA Astrophysics Data System (ADS)

    Alhasnawi, Arshad Naji; Zain, Che Radziah Che Mohd; Kadhimi, Ahsan A.; Isahak, Anizan; Mohamad, Azhar; Ashraf, Mehdi Farshad; Doni, Febri; Yusoff, Wan Mohtar Wan

    2016-11-01

    The application of in vitro systems can lead to new methods of crop amelioration. This method has been widely utilized for breeding tenacities, particularly for stress tolerance selection. Salinity causes oxidative stress in callus by enhancing the production of Reactive Oxygen Species (ROS), resulting in an efficient antioxidant system. The exogenous application of ascorbic acid (AsA) is an important requirement for tolerance. The present study aimed to examine in vitro selection strategy for callus induction in rice mature embryo culture on MS culture medium and to produce salt-tolerant callus under sodium chloride (NaCl) and AsA conditions in callus rice variety, MR269. This study also highlights changes in the activities of proline and antioxidants peroxidase (POD), catalase (CAT) and superoxide dismutase (SOD) of callus under NaCl stress to understand their possible role in salt tolerance. However, various levels of exogenously applied AsA under saline conditions improved callus, and the antioxidant enzyme activities of AsA are related to resistance to oxidative stress. Our results provide strong support for the hypothesis that AsA-dependent antioxidant enzymes play a significant role in the salinity tolerance of callus rice.

  7. Exogenous and endogenous protease inhibitors in the gut of the fall armyworm larvae, Spodoptera frugiperda.

    PubMed

    Lwalaba, Digali; Weidlich, Sandy; Hoffmann, Klaus H; Woodring, Joseph

    2010-06-01

    A dose-dependent inhibition of endogenous trypsin and aminopeptidase occurs in the lumen of Spodoptera frugiperda after feeding L6 larvae exogenous inhibitors soybean trypsin inhibitor (SBTI), tosyl-L-lysine chloromethyl ketone-HCl (TLCK), or bestatin, respectively, for 3 days. TLCK inhibits trypsin in tissue extracts and in secretions more strongly than SBTI. The aminopeptidase released into the lumen (containing the peritrophic membrane) is strongly inhibited by bestatin, but the membrane-bound enzyme is not. A bound enzyme may be more resistant to an inhibitor than unbound. A cross-class elevation of aminopeptidase activity occurs in response to ingested trypsin inhibitor, but there was no cross-class effect of aminopeptidase inhibitor (bestatin) on trypsin activity. An endogenous trypsin and aminopeptidase inhibitor is present in the lumen and ventricular cells. The strength of the endogenous trypsin inhibition seems to be in the same range as that resulting from ingestion of the exogenous inhibitor SBTI. In some insect species, considerable trypsin secretion occurs in unfed as well as in fed animals, and endogenous protease inhibitors might function to protect the ventricular epithelium by inactivation of trypsin when less food is available.

  8. Effects of exogenous glutathione and cysteine on growth, lead accumulation, and tolerance of Iris lactea var. chinensis.

    PubMed

    Yuan, Haiyan; Zhang, Yongxia; Huang, Suzhen; Yang, Yongheng; Gu, Chunsun

    2015-02-01

    Effects of exogenous reduced glutathione (GSH) and cysteine (Cys) on growth, lead (Pb) accumulation, and nonprotein thiol (NPT) contents of Iris lactea var. chinensis under 100 and 500 mg L(-1) Pb stress were studied. Our results showed that 500 mg L(-1) Pb stress caused a dramatical decline in fresh weights, while the reduction of aboveground biomass was alleviated by exogenous GSH and Cys even though keeping higher Pb contents in roots and shoots. Exogenous GSH and Cys could enhance Pb accumulation in the shoots and roots compared with single Pb treatment. The promoting effect of GSH to Pb accumulation was larger than the effect of Cys, and the Pb contents in the shoots and roots treated with 500 mg L(-1) Pb + GSH reached 1,712 and 14,603 mg kg(-1), about 4.19 and 2.78 times of single 500 mg L(-1) Pb treatment, respectively. Microscopic imaging of Pb in roots and leaves showed that higher intensive fluorescence was observed in cell wall of root epidermis, stele, vascular tissues of the roots, and sclerenchyma cells of leaves treated with 500 mg L(-1) Pb + GSH and treated with 500 mg L(-1) Pb + Cys. Exogenous GSH had an apparent promoting effect on root and shoot GSH synthesis, while exogenous Cys reduced the synthesis of cellular GSH in shoot and increased Cys contents. Pb only induced the synthesis of phytochelatin (PC)2 in roots, and the PC2 content declined in GSH- and Cys-treated plant roots. These results suggested that GSH synthesis was a more effective approach to improve Pb accumulation and translocation of I. lactea var. chinensis. Further analysis of protein expression in plants by exogenous GSH and buthionine sulfoximine (BSO) application showed that the proteins regulated by GSH and BSO may constitute various enzymes involved in GSH biosynthesis and play certain roles in Pb accumulation and tolerance of I. lactea var. chinensis.

  9. Effect of glucose addition and N sources in defined media on fibrolytic activity profiles of Neocallimastix sp. YQ1 grown on corn stover.

    PubMed

    Yang, H J; Yue, Q

    2012-08-01

    Cleavage of plant cell wall arabinoxylans occurs by the action of ferulic acid esterase (FAE) and acetyl esterase (AE), which cleave feruloyl groups substituted at the 5'-OH group of arabinosyl residues and acetyl groups substituted at O-2/O-3 of the xylan backbone, respectively. In this study, we examined the enzyme profiles of the anaerobic rumen fungus Neocallimastix sp. YQ1 for FAE, AE and polysaccharide hydrolases when grown on corn stover, a lignin-rich waste biomaterial. A 2 × 4 factorial experiment in 10-days pure cultures was used to test glucose addition (G(+) : glucose at 1.0 g/l, G(-) : no glucose) and four N sources (N1: 1.0 g/l yeast extract, 1.0 g/l tryptone and 0.5 g/l (NH(4))(2) SO(4); N2: 2.8 g/l yeast extract and 0.5 g/l (NH(4))(2) SO(4) ; N3: 1.6 g/l tryptone and 0.5 g/l (NH(4))(2) SO(4); N4: 1.4 g/l tryptone and 1.7 g/l yeast extract) in defined media. The optimal combinations of glucose and N sources to promote FAE and AE activity were G(+) N2 and G(+) N4, respectively. The peak activities of FAE and AE occurred on days 9 and 10, respectively. Addition of glucose and an increase in yeast extract and/or tryptone to a Hungate's medium favoured fungal production of volatile fatty acids, which could be just a consequence of more organic matter available to digest. This suggests that enzymatic release of ferulic acid by a synergistic action of lignin hydrolytic esterase and polysaccharide hydrolases may be essential for plant cell wall biodegradation in the rumen. © 2011 Blackwell Verlag GmbH.

  10. Isolation, identification and fibrolytic characteristics of rumen fungi grown with indigenous methanogen from yaks (Bos grunniens) grazing on the Qinghai-Tibetan Plateau.

    PubMed

    Wei, Y-Q; Yang, H-J; Luan, Y; Long, R-J; Wu, Y-J; Wang, Z-Y

    2016-03-01

    To obtain co-cultures of anaerobic fungi and their indigenously associated methanogens from the rumen of yaks grazing on the Qinghai-Tibetan Plateau and investigate their morphology features and ability to degrade lignocellulose. Twenty fungus-methanogen co-cultures were obtained by Hungate roll-tube technique. The fungi were identified as Orpinomyces, Neocallimastix and Piromyces genera based on the morphological characteristics and internal transcribed spacer 1 sequences analysis. All methanogens were identified as Methanobrevibacter sp. by 16S rRNA gene sequencing. There were four types of co-cultures: Neocallimastix with Methanobrevibacter ruminantium, Orpinomyces with M. ruminantium, Orpinomyces with Methanobrevibacter millerae and Piromyces with M. ruminantium among 20 co-cultures. In vitro studies with wheat straw as substrate showed that the Neocallimastix with M. ruminantium co-cultures and Piromyces with M. ruminantium co-cultures exhibited higher xylanase, filter paper cellulase (FPase), ferulic acid esterase, acetyl esterase activities, in vitro dry matter digestibility, gas, CH4 , acetate production, ferulic acid and p-coumaric acid releases. The Neocallimastix frontalis Yak16 with M. ruminantium co-culture presented the strongest lignocellulose degradation ability among 20 co-cultures. Twenty fungus-methanogen co-cultures were obtained from the rumen of grazing yaks. The N. frontalis with M. ruminantium co-cultures were highly effective combination for developing a fermentative system that bioconverts lignocellulose to high activity fibre-degrading enzyme, CH4 and acetate. The N. frontalis with M. ruminantium co-cultures from yaks grazing on the Qinghai-Tibetan Plateau present great potential in lignocellulose biodegradation industry. © 2015 The Society for Applied Microbiology.

  11. Functional annotation of Fibrobacter succinogenes S85 carbohydrate active enzymes

    USDA-ARS?s Scientific Manuscript database

    Fibrobacter succinogenes is a cellulolytic bacterium that degrades plant cell wall biomass in ruminant animals and is among the most rapidly fibrolytic of all mesophilic bacteria. The complete genome sequence of Fisuc was completed by the DOE Joint Genome Institute in late 2009. Using new expression...

  12. Functional annotation of Fibrobacter succinogenes carbohydrate active enzymes

    USDA-ARS?s Scientific Manuscript database

    Fibrobacter succinogenes (Fisuc) is a cellulolytic bacterium that degrades plant cell wall biomass in ruminant animals, and is among the most rapidly fibrolytic of all mesophilic bacteria. The complete genome sequence of Fisuc was completed by the DOE Joint Genome Institute in late 2009. Using new e...

  13. Exogenic and endogenic albedo and color patterns on Europa

    NASA Technical Reports Server (NTRS)

    Mcewen, A. S.

    1986-01-01

    New global and high-resolution multispectral mosaics of Europa have been produced from the Voyager imaging data. Photometric normalizations are based on multiple-image techniques that explicitly account for intrinsic albedo variations through pixel-by-pixel solutions. The exogenic color and albedo pattern on Europa is described by a second-order function of the cosine of the angular distance from the apex of orbital motion. On the basis of this second-order function and of color trends that are different on the leading and trailing hemispheres, the exogenic pattern is interpreted as being due to equilibrium between two dominant processes: (1) impact gardening and (2) magnetospheric interactions, including sulfur-ion implantation and sputtering redistribution. Removal of the model exogenic pattern in the mosaics reveals the endogenic variations, consisting of only two major units: darker (redder) and bright materials. Therefore Europa's visual spectral reflectivity is simple, having one continuous exogenic pattern and two discrete endogenic units.

  14. Exogenic and endogenic albedo and color patterns on Europa

    NASA Technical Reports Server (NTRS)

    Mcewen, A. S.

    1986-01-01

    New global and high-resolution multispectral mosaics of Europa have been produced from the Voyager imaging data. Photometric normalizations are based on multiple-image techniques that explicitly account for intrinsic albedo variations through pixel-by-pixel solutions. The exogenic color and albedo pattern on Europa is described by a second-order function of the cosine of the angular distance from the apex of orbital motion. On the basis of this second-order function and of color trends that are different on the leading and trailing hemispheres, the exogenic pattern is interpreted as being due to equilibrium between two dominant processes: (1) impact gardening and (2) magnetospheric interactions, including sulfur-ion implantation and sputtering redistribution. Removal of the model exogenic pattern in the mosaics reveals the endogenic variations, consisting of only two major units: darker (redder) and bright materials. Therefore Europa's visual spectral reflectivity is simple, having one continuous exogenic pattern and two discrete endogenic units.

  15. Isolating Exogenous and Endogenous Modes of Temporal Attention

    ERIC Educational Resources Information Center

    Lawrence, Michael A.; Klein, Raymond M.

    2013-01-01

    The differential allocation of information processing resources over time, here termed "temporal attention," may be achieved by relatively automatic "exogenous" or controlled "endogenous" mechanisms. Over 100 years of research has confounded these theoretically distinct dimensions of temporal attention. The current…

  16. Exogenous lipoid pneumonia caused by facial application of petrolatum.

    PubMed

    Cohen, Mark A; Galbut, Brian; Kerdel, Francisco A

    2003-12-01

    Exogenous lipoid pneumonia is a well-described entity in the literature. To our knowledge, this is the first reported case that occurred secondary to external application of petrolatum to the face for erythrodermic psoriasis.

  17. Isolating Exogenous and Endogenous Modes of Temporal Attention

    ERIC Educational Resources Information Center

    Lawrence, Michael A.; Klein, Raymond M.

    2013-01-01

    The differential allocation of information processing resources over time, here termed "temporal attention," may be achieved by relatively automatic "exogenous" or controlled "endogenous" mechanisms. Over 100 years of research has confounded these theoretically distinct dimensions of temporal attention. The current…

  18. Functional Analyses of Multiple Lichenin-Degrading Enzymes from the Rumen Bacterium Ruminococcus albus 8▿†

    PubMed Central

    Iakiviak, Michael; Mackie, Roderick I.; Cann, Isaac K. O.

    2011-01-01

    Ruminococcus albus 8 is a fibrolytic ruminal bacterium capable of utilization of various plant cell wall polysaccharides. A bioinformatic analysis of a partial genome sequence of R. albus revealed several putative enzymes likely to hydrolyze glucans, including lichenin, a mixed-linkage polysaccharide of glucose linked together in β-1,3 and β-1,4 glycosidic bonds. In the present study, we demonstrate the capacity of four glycoside hydrolases (GHs), derived from R. albus, to hydrolyze lichenin. Two of the genes encoded GH family 5 enzymes (Ra0453 and Ra2830), one gene encoded a GH family 16 enzyme (Ra0505), and the last gene encoded a GH family 3 enzyme (Ra1595). Each gene was expressed in Escherichia coli, and the recombinant protein was purified to near homogeneity. Upon screening on a wide range of substrates, Ra0453, Ra2830, and Ra0505 displayed different hydrolytic properties, as they released unique product profiles. The Ra1595 protein, predicted to function as a β-glucosidase, preferred cleavage of a nonreducing end glucose when linked by a β-1,3 glycosidic bond to the next glucose residue. The major product of Ra0505 hydrolysis of lichenin was predicted to be a glucotriose that was degraded only by Ra0453 to glucose and cellobiose. Most importantly, the four enzymes functioned synergistically to hydrolyze lichenin to glucose, cellobiose, and cellotriose. This lichenin-degrading enzyme mix should be of utility as an additive to feeds administered to monogastric animals, especially those high in fiber. PMID:21890664

  19. Proteomic Analysis Reveals the Positive Effect of Exogenous Spermidine in Tomato Seedlings' Response to High-Temperature Stress

    PubMed Central

    Sang, Qinqin; Shan, Xi; An, Yahong; Shu, Sheng; Sun, Jin; Guo, Shirong

    2017-01-01

    Polyamines are phytohormones that regulate plant growth and development as well as the response to environmental stresses. To evaluate their functions in high-temperature stress responses, the effects of exogenous spermidine (Spd) were determined in tomato leaves using two-dimensional electrophoresis and MALDI-TOF/TOF MS. A total of 67 differentially expressed proteins were identified in response to high-temperature stress and/or exogenous Spd, which were grouped into different categories according to biological processes. The four largest categories included proteins involved in photosynthesis (27%), cell rescue, and defense (24%), protein synthesis, folding and degradation (22%), and energy and metabolism (13%). Exogenous Spd up-regulated most identified proteins involved in photosynthesis, implying an enhancement in photosynthetic capacity. Meanwhile, physiological analysis showed that Spd could improve net photosynthetic rate and the biomass accumulation. Moreover, an increased high-temperature stress tolerance by exogenous Spd would contribute to the higher expressions of proteins involved in cell rescue and defense, and Spd regulated the antioxidant enzymes activities and related genes expression in tomato seedlings exposed to high temperature. Taken together, these findings provide a better understanding of the Spd-induced high-temperature resistance by proteomic approaches, providing valuable insight into improving the high-temperature stress tolerance in the global warming epoch. PMID:28220137

  20. Production of Bacteriolytic Enzymes by Streptomyces globisporus Regulated by Exogenous Bacterial Cell Walls

    PubMed Central

    Brönneke, Volker; Fiedler, Franz

    1994-01-01

    Mutanolysin biosynthesis and pigment production in Streptomyces globisporus ATCC 21553 were stimulated by adding bacterial cell walls to the medium. The increased bacteriolytic activity in the supernatant correlated with an increased de novo synthesis of mutanolysin and was between 4- and 20-fold higher than in cultures grown without bacterial cell walls. The increase in mutanolysin synthesis was brought about by enhanced transcription of the mutanolysin gene. The stimulation was only observed in medium which contained dextrin or starch as the carbon source. Glucose abolished the stimulation and also inhibited the low constitutive synthesis of mutanolysin. The induction of lytic activity was observed to require minimally 0.4 mg of bacterial cell walls per ml, whereas 0.6 mg of bacterial cell walls per ml yielded maximal lytic activity. Further supplements of bacterial cell walls did not result in enhanced lytic activity. The stimulation could be achieved independently of the phase of growth of the Streptomyces strain. Cultures grown in the presence of bacterial cell walls exhibited a higher growth yield. However, the accelerated growth was not the reason for the increased amount of mutanolysin produced. The growth of cultures with peptidoglycan monomers added to the medium instead of cell walls was similarly increased, but an effect on the biosynthesis of mutanolysin was not observed. All bacterial cell walls tested were capable of eliciting the stimulation of lytic activity, including cell walls of archaea, which contained pseudomurein. Images PMID:16349213

  1. Exogenous proline application ameliorates toxic effects of arsenate in Solanum melongena L. seedlings.

    PubMed

    Singh, Madhulika; Pratap Singh, Vijay; Dubey, Gunjan; Mohan Prasad, Sheo

    2015-07-01

    Hydroponic experiments were conducted to investigate an effect of exogenous application of proline (Pro; 25 µM) in alleviating arsenate (As(V); 5 and 25 µM) toxicity in Solanum melongena L. (eggplant) seedlings. Exposure of As(V) declined growth of eggplant, which was coincided with an enhanced accumulation of As. However, exogenous Pro application alleviated As(V) toxicity in eggplant seedlings by reducing the accumulation of As. The fluorescence characteristics (JIP-test): φP0, Ψ0, φE0, PIABS, ABS/RC, TR0/RC, ET0/RC, DI0/RC, NPQ and qP were also affected by As(V). However, the effects of As(V) were more prominent on PIABS DI0/RC and NPQ. In Pro treated seedlings, following parameters viz. φP0, Ψ0, φE0 and PIABS were stimulated, while, energy flux parameters (ABS/RC, TR0/RC, ET0/RC and DI0/RC) were inhibited. Toxic effects of As(V) on photochemistry of photosystem II (PS II) were ameliorated by an exogenous application of Pro. Oxidative stress markers: superoxide radical, hydrogen peroxide and malondialdehyde (lipid peroxidation) were enhanced by As(V) exposure, however, their levels were significantly diminished by an exogenous application of Pro. Treatment of As(V) stimulated the activities of superoxide dismutase, peroxidase and catalase except that of glutathione-S-transferase. Exogenous Pro application improved the activities of enzymatic antioxidants. The level of endogenous Pro was higher in As(V) treated as well as in Pro fed seedlings. The activity of a key enzyme of Pro biosynthesis: Δ(1)-pyrroline-5-carboxylate synthetase was higher in Pro fed seedlings. The activity of Pro dehydrogenase was inhibited under As(V) stress, and its activity was minimum in case of Pro+As(V) combination. These results indicate that Pro metabolism could play a key role in regulating the accumulation of As and levels of antioxidants, which concomitantly result into a better growth of eggplant seedlings when compared to the As(V) treatments alone. Copyright © 2015

  2. Primary enzyme quantitation

    DOEpatents

    Saunders, G.C.

    1982-03-04

    The disclosure relates to the quantitation of a primary enzyme concentration by utilizing a substrate for the primary enzyme labeled with a second enzyme which is an indicator enzyme. Enzyme catalysis of the substrate occurs and results in release of the indicator enzyme in an amount directly proportional to the amount of primary enzyme present. By quantifying the free indicator enzyme one determines the amount of primary enzyme present.

  3. Interactions between endogenous and exogenous attention during vigilance.

    PubMed

    MacLean, Katherine A; Aichele, Stephen R; Bridwell, David A; Mangun, George R; Wojciulik, Ewa; Saron, Clifford D

    2009-07-01

    The ability to remain vigilant over long periods of time is critical for many everyday tasks, but controlled studies of visual sustained attention show that performance declines over time when observers are required to respond to rare stimulus events (targets) occurring in a sequence of standard stimulus events (nontargets). When target discrimination is perceptually difficult, this vigilance decrement manifests as a decline in perceptual sensitivity. We examined whether sudden-onset stimuli could act as exogenous attentional cues to improve sensitivity during a traditional sustained attention task. Sudden-onset cues presented immediately before each stimulus attenuated the sensitivity decrement, but only when stimulus timing (the interstimulus interval [ISI]) was constant. When stimulus timing was variable, exogenous cues increased overall sensitivity but did not prevent performance decline. Finally, independent of the effects of sudden onsets, a constant ISI improved vigilance performance. Our results demonstrate that exogenous attention enhances perceptual sensitivity during vigilance performance, but that this effect is dependent on observers' being able to predict the timing of stimulus events. Such a result indicates a strong interaction between endogenous and exogenous attention during vigilance. We relate our findings to a resource model of vigilance, as well as to theories of endogenous and exogenous attention over short time periods.

  4. Exogenous (automatic) attention to emotional stimuli: a review.

    PubMed

    Carretié, Luis

    2014-12-01

    Current knowledge on the architecture of exogenous attention (also called automatic, bottom-up, or stimulus-driven attention, among other terms) has been mainly obtained from studies employing neutral, anodyne stimuli. Since, from an evolutionary perspective, exogenous attention can be understood as an adaptive tool for rapidly detecting salient events, reorienting processing resources to them, and enhancing processing mechanisms, emotional events (which are, by definition, salient for the individual) would seem crucial to a comprehensive understanding of this process. This review, focusing on the visual modality, describes 55 experiments in which both emotional and neutral irrelevant distractors are presented at the same time as ongoing task targets. Qualitative and, when possible, meta-analytic descriptions of results are provided. The most conspicuous result is that, as confirmed by behavioral and/or neural indices, emotional distractors capture exogenous attention to a significantly greater extent than do neutral distractors. The modulatory effects of the nature of distractors capturing attention, of the ongoing task characteristics, and of individual differences, previously proposed as mediating factors, are also described. Additionally, studies reviewed here provide temporal and spatial information-partially absent in traditional cognitive models-on the neural basis of preattention/evaluation, reorienting, and sensory amplification, the main subprocesses involved in exogenous attention. A model integrating these different levels of information is proposed. The present review, which reveals that there are several key issues for which experimental data are surprisingly scarce, confirms the relevance of including emotional distractors in studies on exogenous attention.

  5. Exogenous hydrogen peroxide reversibly inhibits root gravitropism and induces horizontal curvature of primary root during grass pea germination.

    PubMed

    Jiang, Jinglong; Su, Miao; Wang, Liyan; Jiao, Chengjin; Sun, Zhengxi; Cheng, Wei; Li, Fengmin; Wang, Chongying

    2012-04-01

    During germination in distilled water (dH(2)O) on a horizontally positioned Petri dish, emerging primary roots of grass pea (Lathyrus sativus L.) grew perpendicular to the bottom of the Petri dish, due to gravitropism. However, when germinated in exogenous hydrogen peroxide (H(2)O(2)), the primary roots grew parallel to the bottom of the Petri dish and asymmetrically, forming a horizontal curvature. Time-course experiments showed that the effect was strongest when H(2)O(2) was applied prior to the emergence of the primary root. H(2)O(2) failed to induce root curvature when applied post-germination. Dosage studies revealed that the frequency of primary root curvature was significantly enhanced with increased H(2)O(2) concentrations. This curvature could be directly counteracted by dimethylthiourea (DMTU), a scavenger of H(2)O(2), but not by diphenylene iodonium (DPI) and pyridine, inhibitors of H(2)O(2) production. Exogenous H(2)O(2) treatment caused both an increase in the activities of H(2)O(2)-scavenging enzymes [including ascorbate peroxidase (APX: EC 1.11.1.11), catalase (CAT: EC 1.11.1.6) and peroxidase (POD: EC 1.11.1.7)] and a reduction in endogenous H(2)O(2) levels and root vitality. Although grass pea seeds absorbed exogenous H(2)O(2) during seed germination, DAB staining of paraffin sections revealed that exogenous H(2)O(2) only entered the root epidermis and not inner tissues. These data indicated that exogenously applied H(2)O(2) could lead to a reversible loss of the root gravitropic response and a horizontal curvature in primary roots during radicle emergence of the seedling.

  6. Alleviating CTAC and Flu combined pollution damage in Chlorella vulgaris by exogenous nitric oxide.

    PubMed

    Li, Qi; Liang, Zhijie; Ge, Fei; Xu, Yin; Yang, Liang; Zeng, Hui

    2014-02-01

    This study investigates the effect of sodium nitroprussiate (SNP), an exogenous NO-donor, on the joint toxicity of binary mixtures of cetyltrimethylammonium chloride (CTAC) and fluoranthene (Flu) (CTAC/Flu), which are representatives for surfactants and polycyclic aromatic hydrocarbons (PAHs) respectively, in a unicellular green alga Chlorella vulgaris (C. vulgaris). The results showed that the addition of low SNP (20μM) alleviated the CTAC/Flu combined pollution damage in C. vulgaris. Supplement of low SNP significantly increased the algae biomass, chlorophyll content, soluble protein content and the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) as compared to CTAC/Flu treatment alone. SNP also reduced the content of malondialdehyde (MDA) and the reactive oxygen species (ROS), as compared with CTAC/Flu treated alone. On the contrary, the above phenomena were reversed when high concentration of SNP (100μM) was added. Our study indicated that the damage of the joint action of surfactants and PAHs on hydrobios can be alleviated through protecting against oxidant substances and increasing the activity of antioxidant enzymes with an exogenous supply of NO in certain concentration range.

  7. Exogenous jasmonic acid induces stress tolerance in tobacco (Nicotiana tabacum) exposed to imazapic.

    PubMed

    Kaya, Armagan; Doganlar, Zeynep Banu

    2016-02-01

    Jasmonic acid (JA) is one of the important phytohormones, regulating the stress responses as well as plant growth and development. The aim of this study is to determine the effects of exogenous JA application on stress responses of tobacco plant exposed to imazapic. In this study, phytotoxic responses resulting from both imazapic and imazapic combined with JA treatment are investigated comparatively for tobacco plants. For plants treated with imazapic at different concentrations (0.030, 0.060 and 0.120mM), antioxidant enzyme activities (catalase, ascorbate peroxidase, glutathione S-transferase and glutathione reductase), carotenoids, glutathione and malondialdehyte (MDA) contents, jasmonic acid, abscisic acid and indole-3-acetic acid levels as well as herbicide residue amounts on leaves increased in general compared to the control group. In the plants treated with 45µM jasmonic acid, pigment content, antioxidant activity and phytohormone level increased whereas MDA content and the amount of herbicidal residue decreased compared to the non-treated plants. Our findings show that imazapic treatment induces some phytotoxic responses on tobacco leaves and that exogenous jasmonic acid treatment alleviates the negative effects of herbicide treatment by regulating these responses. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Uptake and accumulation of exogenous docosahexaenoic acid by Chlorella.

    PubMed

    Hayashi, M; Yukino, T; Maruyama, I; Kido, S; Kitaoka, S

    2001-01-01

    Tuna oil or its hydrolysate was added to a culture of Chlorella for its nutritional fortification as a feed for rotifer. Exogenous docosahexaenoic acid (DHA) in its free form was taken up by the cells of Chlorella vulgaris strain K-22 and by other strains, but tuna oil was not taken up by the cells. Accumulated DHA was found by electron microscopy in the cells in oil droplets. All strains of Chlorella used in these experiments took up exogenous DHA into the cells. It seems that the structure of the cell wall did not affect the uptake of DHA into the Chlorella cells.

  9. Exogenous lipoid pneumonia (ELP): when radiologist makes the difference

    PubMed Central

    Rea, G; Perna, F; Calabrese, G; Molino, A; Valente, T; Vatrella, A

    2016-01-01

    Lipoid pneumonia is an uncommon disorder characterized by accumulation of lipid components into the interstitial and alveolar compartment. The usual classification distinguishes endogenous and exogenous and acute or chronic forms, related to the type of fats, the amount of damage and the time of exposure. We describe a case of exogenous lipoid pneumonia by inhalation of vaseline used for cleaning of the tracheostoma in a 63-year-old female, presenting as cough, worsening dyspnea in few weeks. The diagnosis was finally established with a re-evaluation of BAL with specific staining for lipids, revealing the presence of foamy macrophages lipids rich, according to HRCT findings. PMID:27326397

  10. Neuropsychiatric findings in Cushing syndrome and exogenous glucocorticoid administration.

    PubMed

    Starkman, Monica N

    2013-09-01

    This article reviews the neuropsychiatric presentations elicited by spontaneous hypercortisolism and exogenous supraphysiologic glucocorticoids. Patients with Cushing disease and syndrome develop a depressive syndrome: irritable and depressed mood, decreased libido, disrupted sleep and cognitive decrements. Exogenous short-term glucocorticoid administration may elicit a hypomanic syndrome with mood, sleep and cognitive disruptions. Treatment options are discussed. Brain imaging and neuropsychological studies indicate elevated cortisol and other glucocorticoids are especially deleterious to hippocampus and frontal lobe. The research findings also shed light on neuropsychiatric abnormalities in conditions that have substantial subgroups exhibiting elevated and dysregulated cortisol: aging, major depressive disorder and Alzheimer's disease.

  11. The effect of enzyme treatment on the in vitro fermentation of lucerne incubated with equine faecal inocula.

    PubMed

    Murray, Jo-Anne M D; Longland, Annette C; Moore-Colyer, Meriel J S; Dunnett, Catherine

    2005-11-01

    A series of experiments was conducted to determine the effects of a fibrolytic enzyme preparation (enzyme 1; E1) on the in vitro fermentation of lucerne incubated with equine faecal inocula. In experiment 1, high-temperature-dried (HT) lucerne was treated with five levels of E1 (0 to 2.4 ml/g DM) and incubated at 50 degrees C for 20 h. Samples then received a simulated foregut digestion (SFD) treatment before DM and NSP analysis. In experiment 2, HT lucerne was treated with the same enzyme levels used in experiment 1. Samples were then split into two groups; plus or minus an SFD treatment before in vitro fermentation using an equine faecal inoculum. In experiment 3, fresh and wilted lucerne were treated with the same levels of E1 as experiments 1 and 2, incubated at 50 degrees C for 20 h, then fermented in vitro. For experiment 4, fresh and wilted lucerne were treated with low levels (0 to 0.008 ml/g DM) of E1 before fermentation. E1 significantly (P<0.05) enhanced DM and NSP losses from HT lucerne following SFD treatment compared with the control. High levels of E1 significantly (P<0.05) enhanced the rate, but not extent, of fermentation of HT, wilted and fresh lucerne; however, low levels of E1 were ineffective. At higher application levels, E1 appears to have considerable potential to enhance the nutritive value of lucerne for horses. Information on the fermentation kinetics of the substrates was valuable; all end-point measurements showed no effect of enzyme treatment.

  12. Targeted disruption of exogenous EGFP gene in medaka using zinc-finger nucleases.

    PubMed

    Ansai, Satoshi; Ochiai, Hiroshi; Kanie, Yuta; Kamei, Yasuhiro; Gou, Yuki; Kitano, Takeshi; Yamamoto, Takashi; Kinoshita, Masato

    2012-06-01

    Zinc-finger nucleases (ZFNs) are artificial enzymes that create site-specific double-strand breaks and thereby induce targeted genome editing. Here, we demonstrated successful gene disruption in somatic and germ cells of medaka (Oryzias latipes) using ZFN to target exogenous EGFP genes. Embryos that were injected with an RNA sequence pair coding for ZFNs showed mosaic loss of green fluorescent protein fluorescence in skeletal muscle. A number of mutations that included both deletions and insertions were identified within the ZFN target site in each embryo, whereas no mutations were found at the non-targeted sites. In addition, ZFN-induced mutations were introduced in germ cells and efficiently transmitted to the next generation. The mutation frequency varied (6-100%) in the germ cells from each founder, and a founder carried more than two types of mutation in germ cells. Our results have introduced the possibility of targeted gene disruption and reverse genetics in medaka.

  13. Recent Advances in Endogenous and Exogenous Stimuli-Responsive Nanocarriers for Drug Delivery and Therapeutics.

    PubMed

    Hatakeyama, Hiroto

    2017-01-01

    Significant progress has been achieved in the development of stimuli-responsive nanocarriers for drug delivery, diagnosis, and therapy. Various types of triggers are utilized in the development of nanocarrier delivery. Endogenous factors such as changes in pH, redox, gradient, and enzyme concentration which are linked to disease progression have been utilized for controlling biodistribution and releasing drugs from nanocarriers, as well as increasing subsequent pharmacological activity at the disease site. Nanocarriers which respond to artificially-induced exogenous factors (such as temperature, light, magnetic field, and ultrasound) have also been developed. This review aims to discuss recent advances in the design of stimuli-responsive nanocarriers which appear to have a promising future in medicine.

  14. Altering the phenolics profile of a green tea leaves extract using exogenous oxidases.

    PubMed

    Verloop, Annewieke J W; Gruppen, Harry; Bisschop, Robbin; Vincken, Jean-Paul

    2016-04-01

    Transformation from green tea leaves into black tea involves oxidation of catechins into theaflavins and other complex phenolics by endogenous enzymes in tea leaves. By employing tyrosinase and laccase, both from Agaricus bisporus, on green tea catechins, the oxidation process was directed towards a higher theaflavins content, which is considered an important quality parameter in tea. The main tea catechins were incubated with tyrosinase and laccase, and product formation was monitored by RP-UHPLC-PDA-ESI-MS. The kind of catechin, their substitution with a galloyl group, and the type of oxidase used were important factors determining theaflavin concentrations. In particular, incubation of epicatechin with epigallocatechin with tyrosinase gave a high, stable theaflavin content. In a green tea extract, tyrosinase increased the proportion of theaflavins by twofold compared to black tea. Laccase mainly formed insoluble complexes. Our results indicate that the phenolic profile of tea can be modulated by using commercially available exogenous oxidases.

  15. Molecular pharmacology of aromatase and its regulation by endogenous and exogenous agents.

    PubMed

    Brueggemeier, R W; Richards, J A; Joomprabutra, S; Bhat, A S; Whetstone, J L

    2001-12-01

    Aromatase (estrogen synthase) is the cytochrome P450 enzyme complex that converts C19 androgens to C18 estrogens. Aromatase activity has been demonstrated in breast tissue in vitro, and expression of aromatase is highest in or near breast tumor sites. Thus, local regulation of aromatase by both endogenous factors as well as exogenous medicinal agents will influence the levels of estrogen available for breast cancer growth. The prostaglandin E2 (PGE2) increases intracellular cAMP levels and stimulates estrogen biosynthesis, and our recent studies have shown a strong linear association between CYP19 expression and the sum of COX-1 and COX-2 expression in breast cancer specimens. PGE2 can bind to four receptor subtypes, EP1-EP4, which are coupled to different intracellular signaling pathways. In primary human breast stromal cell cultures, aromatase activity was significantly induced by PGE2, dexamethasone, and agonists for the EP1 and EP2 receptor subtypes. An EP1 antagonist, SC-19220, inhibited the induction of enzyme activity by PGE2 or 17-phenyltrinor-PGE2, an EP1 agonist. Sulprostone, an EP3 agonist, did not alter aromatase activity levels. Investigations are also underway on the regulation of aromatase by exogenous medicinal agents. Selective steroidal and nonsteroidal agents are effective in inhibiting breast tissue aromatase. The benzopyranone ring system is a molecular scaffold of considerable interest, and this scaffold is found in certain flavonoid natural products that have weak aromatase inhibitory activity. Our novel synthetic route for benzopyranones utilizes readily available salicylic acids and terminal alkynes as starting materials. The synthesis of flavones with diversity on the benzopyranone moiety and at the C-2 position occurs with good to excellent yields using these reaction conditions, resulting in an initial benzopyranone library of thirty compounds exhibiting enhanced and differential aromatase inhibition. Current medicinal chemistry efforts

  16. Exogenous malic acid alleviates cadmium toxicity in Miscanthus sacchariflorus through enhancing photosynthetic capacity and restraining ROS accumulation.

    PubMed

    Guo, Haipeng; Chen, Houming; Hong, Chuntao; Jiang, Dean; Zheng, Bingsong

    2017-03-18

    Malic acid (MA) plays an important role in the regulation of plant growth, stomatal aperture, nutrition elements homeostasis and toxic metals tolerance. However, little is known about the effects of exogenous MA on physiological and biochemical responses to toxic metals in plants. To measure the alleviation roles of exogenous MA against cadmium (Cd), we determined the effects of MA on plant growth, net photosynthetic rate (Pn), reactive oxygen species (ROS) accumulation and the activities of anti-oxidant enzymes in the leaves of Miscanthus sacchariflorus (M. sacchariflorus) under Cd stress. The Cd exposure alone significantly inhibited plant growth and Pn, but increased the accumulation of ROS even though the anti-oxidant enzymes were markedly activated in the leaves of M. sacchariflorus. Treatment with MA significantly enhanced plant growth and decreased Cd accumulation accompanied by increasing Pn under Cd stress as compared to Cd stress alone, especially when treatment with high concentration of MA (200μM) was used. In addition, Cd and MA indicated synergistic effects by further increasing the activities and genes expression of partial anti-oxidant enzymes, thus resulting in higher glutathione accumulation and reduction of ROS production. The results showed that application of MA alleviated Cd-induced phytotoxicity and oxidant damage through the regulation of both enzymatic and non-enzymatic anti-oxidants under Cd stress in M. sacchariflorus.

  17. Accounting for Exogenous Influences in Performance Evaluations of Teachers

    ERIC Educational Resources Information Center

    De Witte, Kristof; Rogge, Nicky

    2011-01-01

    Students' evaluations of teacher performance (SETs) are increasingly used by universities. However, SETs are controversial mainly due to two issues: (1) teachers value various aspects of excellent teaching differently, and (2) SETs should not be determined on exogenous influences. Therefore, this paper constructs SETs using a tailored version of…

  18. EFFECTS OF EXOGENOUS ESTROGEN ON MATE SELECTION OF HOUSE FINCHES

    EPA Science Inventory

    Concern about the potential for endocrine disrupting chemicals to interfere with normal breeding behaviors of wildlife has prompted this study of effects of exogenous estrogen on mate selection in songbirds. The house finch (Carpodacus mexicanus) was selected as a model as it is ...

  19. Endogenous versus Exogenous Growth Factor Regulation of Articular Chondrocytes

    PubMed Central

    Shi, Shuiliang; Chan, Albert G.; Mercer, Scott; Eckert, George J.; Trippel, Stephen B.

    2014-01-01

    Anabolic growth factors that regulate the function of articular chondrocytes are candidates for articular cartilage repair. Such factors may be delivered by pharmacotherapy in the form of exogenous proteins, or by gene therapy as endogenous proteins. It is unknown whether delivery method influences growth factor effectiveness in regulating articular chondrocyte reparative functions. We treated adult bovine articular chondrocytes with exogenous recombinant insulin-like growth factor-I (IGF-I) and transforming growth factor-beta1 (TGF-β1), or with the genes encoding these growth factors for endogenous production. Treatment effects were measured as change in chondrocyte DNA content, glycosaminoglycan production, and aggrecan gene expression. We found that IGF-I stimulated chondrocyte biosynthesis similarly when delivered by either exogenous or endogenous means. In contrast, exogenous TGF-ß1 stimulated these reparative functions, while endogenous TGF-ß1 had little effect. Endogenous TGF-ß1 became more bioactive following activation of the transgene protein product. These data indicate that effective mechanisms of growth factor delivery for articular cartilage repair may differ for different growth factors. In the case of IGF-I, gene therapy or protein therapy appear to be viable options. In contrast, TGF-ß1 gene therapy may be constrained by a limited ability of chondrocytes to convert latent complexes to an active form. PMID:24105960

  20. [Exogenic proteins in the human exhaled breath condensate].

    PubMed

    Kurova, V S; Kononikhin, A S; Sakharov, D A; Popov, I A; Larina, I M; Tonevitskiĭ, A G; Varfolomeev, S D; Nikolaev, E N

    2011-01-01

    The analysis of the protein composition of exhaled breath to diagnose diseases of the respiratory system raises a problem of differentiation proteins of expressed in the tissues of the lungs and respiratory tract (endogenous) and got in the respiratory system from the ambient air in the process of respiration (exogenous). In this work an attempt was made to estimate a set of exhaled exogenic proteins by mass spectrometry coupled with nanoflow HPLC. Six-month isolation of healthy donors indoors with air cleaned of dust leads to removal from the spectrum of exhaled proteins of some keratins that are considered therefore to be exogenic. Non-keratin proteins may also circulate between the ambient air and human respiratory ways, but their concentration appears to be significantly lower the keratin concentrations (especially epidermis keratin). Among non-keratins dermcidin seems to be the most significant exogenic protein of exhaled air. The conclusion of the diagnostic value of exhaled proteins can be done only after careful comparison of the results of quantitative and qualitative analysis of their composition in norm and pathology for a statistically significant sample of donors.

  1. Influence of Exogenous Progestin on Ovarian Function in Beef Cows

    USDA-ARS?s Scientific Manuscript database

    The ability to precisely regulate follicle recruitment and selection is critical to improving methods to control ovulation in beef cows. The objectives of the current study were to investigate the influence of exogenous progestins, commonly used in synchronization protocols, on ovarian function and...

  2. EFFECTS OF EXOGENOUS ESTROGEN ON MATE SELECTION OF HOUSE FINCHES

    EPA Science Inventory

    Concern about the potential for endocrine disrupting chemicals to interfere with normal breeding behaviors of wildlife has prompted this study of effects of exogenous estrogen on mate selection in songbirds. The house finch (Carpodacus mexicanus) was selected as a model as it is ...

  3. Exogenous ethylene inhibits sprout growth in onion bulbs

    PubMed Central

    Bufler, Gebhard

    2009-01-01

    Background and Aims Exogenous ethylene has recently gained commercial interest as a sprouting inhibitor of onion bulbs. The role of ethylene in dormancy and sprouting of onions, however, is not known. Methods A cultivar (Allium cepa ‘Copra’) with a true period of dormancy was used. Dormant and sprouting states of onion bulbs were treated with supposedly saturating doses of ethylene or with the ethylene-action inhibitor 1-methylcyclopropene (1-MCP). Initial sprouting was determined during storage at 18 °C by monitoring leaf blade elongation in a specific size class of leaf sheaths. Changes in ATP content and sucrose synthase activity in the sprout leaves, indicators of the sprouting state, were determined. CO2 and ethylene production of onion bulbs during storage were recorded. Key results Exogenous ethylene suppressed sprout growth of both dormant and already sprouting onion bulbs by inhibiting leaf blade elongation. In contrast to this growth-inhibiting effect, ethylene stimulated CO2 production by the bulbs about 2-fold. The duration of dormancy was not significantly affected by exogenous ethylene. However, treatment of dormant bulbs with 1-MCP caused premature sprouting. Conclusions Exogenous ethylene proved to be a powerful inhibitor of sprout growth in onion bulbs. The dormancy breaking effect of 1-MCP indicates a regulatory role of endogenous ethylene in onion bulb dormancy. PMID:18940850

  4. The Development of Exogenous Orienting: Mechanisms of Control.

    ERIC Educational Resources Information Center

    Wainwright, Ann; Bryson, Susan E.

    2002-01-01

    Examined which of the attentional operations underlying exogenous orienting (disengaging, shifting, and/or engaging) improves with age in children from 6 to 14 years old. Found that disengaging attention alone distinguished between younger and older children's performance, regardless of whether attention alone or attention and associated sensory…

  5. Exogenous lipoid pneumonia due to nasal application of petroleum jelly.

    PubMed

    Brown, A C; Slocum, P C; Putthoff, S L; Wallace, W E; Foresman, B H

    1994-03-01

    We describe a patient who presented with a history of unexplained exertional dyspnea and pulmonary infiltrates. She was evaluated for interstitial lung disease, presumed to be idiopathic and underwent an open lung biopsy. The pathologic findings were compatible with exogenous lipoid pneumonia and her history revealed longstanding use of intranasal petroleum jelly (Vaseline) at bedtime.

  6. Do Endogenous and Exogenous Action Control Compete for Perception?

    ERIC Educational Resources Information Center

    Pfister, Roland; Heinemann, Alexander; Kiesel, Andrea; Thomaschke, Roland; Janczyk, Markus

    2012-01-01

    Human actions are guided either by endogenous action plans or by external stimuli in the environment. These two types of action control seem to be mediated by neurophysiologically and functionally distinct systems that interfere if an endogenously planned action suddenly has to be performed in response to an exogenous stimulus. In this case, the…

  7. Accounting for Exogenous Influences in Performance Evaluations of Teachers

    ERIC Educational Resources Information Center

    De Witte, Kristof; Rogge, Nicky

    2011-01-01

    Students' evaluations of teacher performance (SETs) are increasingly used by universities. However, SETs are controversial mainly due to two issues: (1) teachers value various aspects of excellent teaching differently, and (2) SETs should not be determined on exogenous influences. Therefore, this paper constructs SETs using a tailored version of…

  8. Double agents and secret agents: the emerging fields of exogenous chemical exchange saturation transfer and T2-exchange magnetic resonance imaging contrast agents for molecular imaging.

    PubMed

    Daryaei, Iman; Pagel, Mark D

    2015-01-01

    Two relatively new types of exogenous magnetic resonance imaging contrast agents may provide greater impact for molecular imaging by providing greater specificity for detecting molecular imaging biomarkers. Exogenous chemical exchange saturation transfer (CEST) agents rely on the selective saturation of the magnetization of a proton on an agent, followed by chemical exchange of a proton from the agent to water. The selective detection of a biomarker-responsive CEST signal and an unresponsive CEST signal, followed by the ratiometric comparison of these signals, can improve biomarker specificity. We refer to this improvement as a "double-agent" approach to molecular imaging. Exogenous T2-exchange agents also rely on chemical exchange of protons between the agent and water, especially with an intermediate rate that lies between the slow exchange rates of CEST agents and the fast exchange rates of traditional T1 and T2 agents. Because of this intermediate exchange rate, these agents have been relatively unknown and have acted as "secret agents" in the contrast agent research field. This review exposes these secret agents and describes the merits of double agents through examples of exogenous agents that detect enzyme activity, nucleic acids and gene expression, metabolites, ions, redox state, temperature, and pH. Future directions are also provided for improving both types of contrast agents for improved molecular imaging and clinical translation. Therefore, this review provides an overview of two new types of exogenous contrast agents that are becoming useful tools within the armamentarium of molecular imaging.

  9. Double agents and secret agents: the emerging fields of exogenous chemical exchange saturation transfer and T2-exchange magnetic resonance imaging contrast agents for molecular imaging

    PubMed Central

    Daryaei, Iman; Pagel, Mark D

    2016-01-01

    Two relatively new types of exogenous magnetic resonance imaging contrast agents may provide greater impact for molecular imaging by providing greater specificity for detecting molecular imaging biomarkers. Exogenous chemical exchange saturation transfer (CEST) agents rely on the selective saturation of the magnetization of a proton on an agent, followed by chemical exchange of a proton from the agent to water. The selective detection of a biomarker-responsive CEST signal and an unresponsive CEST signal, followed by the ratiometric comparison of these signals, can improve biomarker specificity. We refer to this improvement as a “double-agent” approach to molecular imaging. Exogenous T2-exchange agents also rely on chemical exchange of protons between the agent and water, especially with an intermediate rate that lies between the slow exchange rates of CEST agents and the fast exchange rates of traditional T1 and T2 agents. Because of this intermediate exchange rate, these agents have been relatively unknown and have acted as “secret agents” in the contrast agent research field. This review exposes these secret agents and describes the merits of double agents through examples of exogenous agents that detect enzyme activity, nucleic acids and gene expression, metabolites, ions, redox state, temperature, and pH. Future directions are also provided for improving both types of contrast agents for improved molecular imaging and clinical translation. Therefore, this review provides an overview of two new types of exogenous contrast agents that are becoming useful tools within the armamentarium of molecular imaging. PMID:27747191

  10. Exogenous low-dose hydrogen peroxide enhances drought tolerance of soybean (Glycine max L.) through inducing antioxidant system.

    PubMed

    Guler, Neslihan Saruhan; Pehlivan, Necla

    2016-06-01

    Hydrogen peroxide (H(2)O(2)) functions as a signal molecule in plants under abiotic and biotic stress. In this study, the role of exogenous H(2)O(2) in improving drought tolerance in two soybean cultivars (Glycine max L. Merrill) differing in their tolerance to drought was evaluated. Plants were grown in plastic pots with normal irrigation in a phytotron. Four weeks after radicle emergence, either 1 mM H(2)O(2) or distilled water was sprayed as foliar onto the leaves of each plant, after drought stress was applied. Leaf samples were harvested on the 4(th) and 7(th) days of the drought. Antioxidant-related enzyme activity, such as the superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), hydrogen peroxide (H(2)O(2)) and malondialdehyde (MDA) content was measured during the drought period. Drought stress decreased leaf water potential, relative water content and photosynthetic pigment content but enhanced lipid peroxidation and endogenous H(2)O(2) concentration. By contrast, exogenous low dose H(2)O(2) improved water status, pigment content and lipid peroxidation under drought stress. Endogenous H(2)O(2) concentration was reduced by exogenous H(2)O(2) as compared to drought treatment alone. H(2)O(2) pre-treatment induced all the antioxidant enzyme activities, to a greater extent than the control leaves, during drought. H(2)O(2) pretreatment further enhanced the activities of antioxidant enzymes in the tolerant cultivar compared to the sensitive cultivar. Results suggested that low dose H(2)O(2) pre-treatment alleviated water loss and H(2)O(2) content and increased drought stress tolerance by inducing the antioxidant system.

  11. The analgesic effects of exogenous melatonin in humans.

    PubMed

    Andersen, Lars Peter Holst

    2016-10-01

    The hormone, melatonin is produced with circadian rhythm by the pineal gland in humans. The melatonin rhythm provides an endogenous synchronizer, modulating e.g. blood pressure, body temperature, cortisol rhythm, sleep-awake-cycle, immune function and anti-oxidative defence. Interestingly, a number of experimental animal studies demonstrate significant dose-dependent anti-nociceptive effects of exogenous melatonin. Similarly, recent experimental- and clinical studies in humans indicate significant analgesic effects. In study I, we systematically reviewed all randomized studies investigating clinical effects of perioperative melatonin. Meta-analyses demonstrated significant analgesic and anxiolytic effects of melatonin in surgical patients, equating reductions of 20 mm and 19 mm, respectively on a VAS, compared with placebo. Profound heterogeneity between the included studies was, however, present. In study II, we aimed to investigate the analgesic, anti-hyperalgesic and anti-inflammatory effects of exogenous melatonin in a validated human inflammatory pain model, the human burn model. The study was performed as a randomized, double blind placebo-controlled crossover study. Primary outcomes were pain during the burn injury and areas of secondary hyperalgesia. No significant effects of exogenous melatonin were observed with respect to primary or secondary outcomes, compared to placebo. Study III and IV estimated the pharmacokinetic variables of exogenous melatonin. Oral melatonin demonstrated a tmax value of 41 minutes. Bioavailability of oral melatonin was only 3%. Elimination t1/2 were approximately 45 minutes following both oral and intravenous administration, respectively. High-dose intravenous melatonin was not associated with increased sedation, in terms of simple reaction times, compared to placebo. Similarly, no other adverse effects were reported. In Study V, we aimed to re-analyse data obtained from a randomized analgesic drug trial by a selection of

  12. A combination of He-Ne laser irradiation and exogenous NO application efficiently protect wheat seedling from oxidative stress caused by elevated UV-B stress.

    PubMed

    Li, Yongfeng; Gao, Limei; Han, Rong

    2016-12-01

    The elevated ultraviolet-B (UV-B) stress induces the accumulation of a variety of intracellular reactive oxygen species (ROS), which seems to cause oxidative stress for plants. To date, very little work has been done to evaluate the biological effects of a combined treatment with He-Ne laser irradiation and exogenous nitric oxide (NO) application on oxidative stress resulting from UV-B radiation. Thus, our study investigated the effects of a combination with He-Ne laser irradiation and exogenous NO treatment on oxidative damages in wheat seedlings under elevated UV-B stress. Our data showed that the reductions in ROS levels, membrane damage parameters, while the increments in antioxidant contents and antioxidant enzyme activity caused by a combination with He-Ne laser and exogenous NO treatment were greater than those of each individual treatment. Furthermore, these treatments had a similar effect on transcriptional activities of plant antioxidant enzymes. This implied that the protective effects of a combination with He-Ne laser irradiation and exogenous NO treatment on oxidative stress resulting from UV-B radiation was more efficient than each individual treatment with He-Ne laser or NO molecule. Our findings might provide beneficial theoretical references for identifying some effective new pathways for plant UV-B protection.

  13. [Superoxide dismutase and catalase activity in the winter wheat sprout leaves under the effect of exogenous hydrogen peroxide].

    PubMed

    Batsmanova, L M

    2008-01-01

    Exogenous hydrogen peroxide action in concentration of 500 microM on antioxidation enzyme activity of photosynthetic tissues of 7-day winter wheat sprouts was investigated. It is established, that catalase activity increased at the second hour of exposition, and it constrained development of lipid peroxidation at the first stages of stress. Superoxide dismutase activity increased at the forth hour of the experiment and the maximum values were reached in 24 hours. Treated plants restored their physiological status in 24 hours and supported it at the 48th hour of exposition. Protective reactions were stimulated by hydrogen peroxide.

  14. Substitution of glutamine for lysine at the pyridoxal phosphate binding site of bacterial D-amino acid transaminase. Effects of exogenous amines on the slow formation of intermediates.

    PubMed

    Futaki, S; Ueno, H; Martinez del Pozo, A; Pospischil, M A; Manning, J M; Ringe, D; Stoddard, B; Tanizawa, K; Yoshimura, T; Soda, K

    1990-12-25

    In bacterial D-amino acid transaminase, Lys-145, which binds the coenzyme pyridoxal 5'-phosphate in Schiff base linkage, was changed to Gln-145 by site-directed mutagenesis (K145Q). The mutant enzyme had 0.015% the activity of the wild-type enzyme and was capable of forming a Schiff base with D-alanine; this external aldimine was formed over a period of minutes depending upon the D-alanine concentration. The transformation of the pyridoxal-5'-phosphate form of the enzyme to the pyridoxamine-5'-phosphate form (i.e. the half-reaction of transamination) occurred over a period of hours with this mutant enzyme. Thus, information on these two steps in the reaction and on the factors that influence them can readily be obtained with this mutant enzyme. In contrast, these reactions with the wild-type enzyme occur at much faster rates and are not easily studied separately. The mutant enzyme shows distinct preference for D- over L-alanine as substrates but it does so about 50-fold less effectively than the wild-type enzyme. Thus, Lys-145 probably acts in concert with the coenzyme and other functional side chain(s) to lead to efficient and stereochemically precise transamination in the wild-type enzyme. The addition of exogenous amines, ethanolamine or methyl amine, increased the rate of external aldimine formation with D-alanine and the mutant enzyme but the subsequent transformation to the pyridoxamine-5'-phosphate form of the enzyme was unaffected by exogenous amines. The wild-type enzyme displayed a large negative trough in the circular dichroic spectrum at 420 nm, which was practically absent in the mutant enzyme. However, addition of D-alanine to the mutant enzyme generated this negative Cotton effect (due to formation of the external aldimine with D-alanine). This circular dichroism band gradually collapsed in parallel with the transformation to the pyridoxamine-5'-phosphate enzyme. Further studies on this mutant enzyme, which displays the characteristics of the wild

  15. Exogenous 3,3'-diindolylmethane increases Brassica napus L. seedling shoot growth through modulation of superoxide and hydrogen peroxide content.

    PubMed

    Gokul, Arun; Roode, Enrico; Klein, Ashwil; Keyster, Marshall

    2016-06-01

    Brassica napus L. (cv. AV Garnet) seeds were pre-treated with 15μM 3,3'-diindolylmethane (DIM) to investigate whether DIM could enhance seed germination. Further treatment of seedlings with 15μM DIM for 14days explored the effects on seedling shoot growth. Exogenous DIM led to improved germination percentage, increased seedling shoot lengths, and increased fresh and dry weights. Furthermore, DIM triggered induction of superoxide radical (O2(-)) and hydrogen peroxide (H2O2) content however, no change in malondialdehyde (MDA) content and cell death (assessed with Evans Blue assay) was detected for both the control and DIM treated seedling shoots. We also observed increases in superoxide dismutase (SOD) activity and ascorbate peroxidase (APX) activity in response to exogenous DIM, two fundamental enzymes in the control of reactive oxygen species (ROS) in plants. These results indicate that exogenous DIM treatment enhances seed germination and improves seedling shoot growth through possible activation of a reactive oxygen species signalling pathway involving O2(-) and H2O2 in B. napus. Copyright © 2016 Elsevier GmbH. All rights reserved.

  16. Alleviation of exogenous 6-benzyladenine on two genotypes of eggplant (Solanum melongena Mill.) growth under salt stress.

    PubMed

    Wu, Xuexia; He, Jie; Chen, Jianlin; Yang, Shaojun; Zha, Dingshi

    2014-01-01

    Cytokinins were recently shown to control plant adaptation to environmental stresses. To characterize the roles of cytokinins in the tolerance of eggplant (Solanum melongena Mill.) to salt stress, the protective effects of 6-benzyladenine (6-BA) on the growth, photosynthesis, and antioxidant capacity in the leaves of two eggplant cultivars Huqie12 (salt-sensitive) and Huqie4 (salt-tolerant) were investigated. Under 90 mM NaCl stress, Huqie4 showed higher biomass accumulation and less oxidative damage compared to the Huqie12. Application of exogenous 10 μM 6-BA significantly alleviated the growth suppression caused by salt stress in two eggplant genotypes. In parallel with the growth, 6-BA application in salt-stressed plants resulted in enhanced chlorophyll contents, as well as photosynthetic parameters such as net CO2 assimilation rate (P n), stomatal conductance (g s), transpiration rate (E), and intercellular CO2 concentration (C i). Furthermore, exogenous 6-BA also significantly reduced the O2 (-) production rate and malondialdehyde content and markedly increased the antioxidant enzymes superoxide dismutase and peroxidase, the antioxidant metabolites ascorbate and reduced glutathione (GSH), and proline in both genotypes under salt stress. The results indicate that exogenous 6-BA is useful to improve the salt resistance of eggplant, which is most likely related to the increase in photosynthesis and antioxidant capacity.

  17. [Interaction between CYP450 enzymes and metabolism of traditional Chinese medicine as well as enzyme activity assay].

    PubMed

    Lu, Tu-lin; Su, Lian-lin; Ji, De; Gu, Wei; Mao, Chun-qin

    2015-09-01

    Drugs are exogenous compounds for human bodies, and will be metabolized by many enzymes after administration. CYP450 enzyme, as a major metabolic enzyme, is an important phase I drug metabolizing enzyme. In human bodies, about 75% of drug metabolism is conducted by CYP450 enzymes, and CYP450 enzymes is the key factor for drug interactions between traditional Chinese medicine( TCM) -TCM, TCM-medicine and other drug combination. In order to make clear the interaction between metabolic enzymes and TCM metabolism, we generally chose the enzymatic activity as an evaluation index. That is to say, the enhancement or reduction of CYP450 enzyme activity was used to infer the inducing or inhibitory effect of active ingredients and extracts of traditional Chinese medicine on enzymes. At present, the common method for measuring metabolic enzyme activity is Cocktail probe drugs, and it is the key to select the suitable probe substrates. This is of great significance for study drug's absorption, distribution, metabolism and excretion (ADME) process in organisms. The study focuses on the interaction between TCMs, active ingredients, herbal extracts, cocktail probe substrates as well as CYP450 enzymes, in order to guide future studies.

  18. Fructose and Sucrose Intake Increase Exogenous Carbohydrate Oxidation during Exercise

    PubMed Central

    Trommelen, Jorn; Fuchs, Cas J.; Beelen, Milou; Lenaerts, Kaatje; Jeukendrup, Asker E.; Cermak, Naomi M.; van Loon, Luc J. C.

    2017-01-01

    Peak exogenous carbohydrate oxidation rates typically reach ~1 g·min−1 during exercise when ample glucose or glucose polymers are ingested. Fructose co-ingestion has been shown to further increase exogenous carbohydrate oxidation rates. The purpose of this study was to assess the impact of fructose co-ingestion provided either as a monosaccharide or as part of the disaccharide sucrose on exogenous carbohydrate oxidation rates during prolonged exercise in trained cyclists. Ten trained male cyclists (VO2peak: 65 ± 2 mL·kg−1·min−1) cycled on four different occasions for 180 min at 50% Wmax during which they consumed a carbohydrate solution providing 1.8 g·min−1 of glucose (GLU), 1.2 g·min−1 glucose + 0.6 g·min−1 fructose (GLU + FRU), 0.6 g·min−1 glucose + 1.2 g·min−1 sucrose (GLU + SUC), or water (WAT). Peak exogenous carbohydrate oxidation rates did not differ between GLU + FRU and GLU + SUC (1.40 ± 0.06 vs. 1.29 ± 0.07 g·min−1, respectively, p = 0.999), but were 46% ± 8% higher when compared to GLU (0.96 ± 0.06 g·min−1: p < 0.05). In line, exogenous carbohydrate oxidation rates during the latter 120 min of exercise were 46% ± 8% higher in GLU + FRU or GLU + SUC compared with GLU (1.19 ± 0.12, 1.13 ± 0.21, and 0.82 ± 0.16 g·min−1, respectively, p < 0.05). We conclude that fructose co-ingestion (0.6 g·min−1) with glucose (1.2 g·min−1) provided either as a monosaccharide or as sucrose strongly increases exogenous carbohydrate oxidation rates during prolonged exercise in trained cyclists. PMID:28230742

  19. Elevated Liver Enzymes

    MedlinePlus

    Symptoms Elevated liver enzymes By Mayo Clinic Staff Elevated liver enzymes may indicate inflammation or damage to cells in the liver. Inflamed or ... than normal amounts of certain chemicals, including liver enzymes, into the bloodstream, which can result in elevated ...

  20. Exogenous folates stimulate growth and budding of Candida glabrata

    PubMed Central

    Porzoor, Afsaneh; Macreadie, Ian G.

    2015-01-01

    Folate, vitamin B9, is well recognized as being essential for cell growth. The utilization of folate is common to all cells, but the source of it may be quite different. For example, mammalian cells depend on exogenous uptake of folates, while plants and microbes can synthesize them. There has been little consideration of uptake of folate in microbial cells, and studies on the effects of folates in mammalian cells, where conditions are restricted. This study shows that exogenous folates (folic acid or folinic acid), causes Candida glabrata cells suspended in water alone to undergo two cycles of cell division and to form multiple buds. The effect was limited to cells in the stationary phase and more profound in quiescent cells. These data indicate a novel response of yeast to folates that may increase the utility of yeast as a model to study folate transport and signaling. PMID:28357288

  1. Exogenous nitric oxide activates the endothelial glucocorticoid receptor.

    PubMed

    Ji, Julie Y; Diamond, Scott L

    2004-05-21

    This study investigated the effect of exogenous nitric oxide (NO) on endothelial glucocorticoid receptor (GR) function. The NO donor diethylenetriamine NONOate (DETA, 50-500microM) caused concentration dependent nuclear localization of transfected chimeric green fluorescent protein GFP-GR and elevated expression of secreted alkaline phosphatase (SEAP) from a glucocorticoid response element (GRE) promoter construct in bovine aortic endothelial cells. Other weaker NO donors (S-nitroso-N-acetylpenicillamine and spermine NONOate) failed to induce GFP-GR nuclear localization, but all the NO donors activated GRE-SEAP expression, a response unaffected by the antioxidant N-acetyl-L-cysteine. Overall, exogenous NO from high concentration donors can directly activate GR, suggesting a potential feedback mechanism for NO to regulate endothelial inducible nitric oxide synthase (iNOS) expression.

  2. Endogenous versus exogenous change: change detection, self and agency.

    PubMed

    Berberian, Bruno; Cleeremans, Axel

    2010-03-01

    The goal of this study is to characterize observers' abilities to discriminate between endogenous (i.e., self-produced) and exogenous changes. To do so, we developed a new experimental paradigm. On each trial, participants were shown a dot pattern on the screen. Next, the pattern disappeared and participants were to reproduce it. Changes were surreptuously introduced in the stimulus, either by presenting participants anew with the dot pattern they had themselves produced on the previous trial (endogenous change) or by presenting participants with a slightly different dot pattern (exogenous changes). We analyzed awareness of the changes and behavioral adaptation to them in a dynamical manner. We observe (1) signal attenuation in the presence of endogenous change, (2) dissociation between self-attribution reports and behavioral effect of agency. We discuss the source of this sensitive attenuation as well as the relation between a minimal or core self and an extended, narrative or autobiographical self.

  3. Exogenous Lipoid Pneumonia in Laryngectomy Patients: Radiological Findings.

    PubMed

    García Latorre, Raquel; Rodríguez Díaz, Ricardo; Barrios Barreto, Deisy; Ayala Carbonero, Ana; García Gómez-Muriel, María Isabel; Gorospe Sarasúa, Luis

    2015-07-01

    Exogenous lipoid pneumonia (ELP) is a rare (incidence 1.0%-2.5%), often under-diagnosed disease, caused by the aspiration and accumulation of exogenous lipids within the pulmonary alveoli. Various cases have been described due to inhalation of lubricants via the nasal passages and oropharynx, aspiration of mineral oils in laxatives in patients with eating disorders, application of lip gloss, occupational exposure to liquid paraffin or mineral oils ("fire-eaters", industrial use in washing of machinery, automobile workshops, plastic paints, etc.) and application of Vaseline during the insertion of nasogastric tubes and in the care of tracheotomy patients. ELP usually presents radiologically as areas of low-attenuation peribronchial consolidation and ground glass opacities, with a predominantly bibasal distribution. We present 5 cases of long-standing laryngectomy patients diagnosed with ELP who admitted using Vaseline in their tracheal stoma care. Copyright © 2014 SEPAR. Published by Elsevier Espana. All rights reserved.

  4. Exogenous attention facilitates location transfer of perceptual learning

    PubMed Central

    Donovan, Ian; Szpiro, Sarit; Carrasco, Marisa

    2015-01-01

    Perceptual skills can be improved through practice on a perceptual task, even in adulthood. Visual perceptual learning is known to be mostly specific to the trained retinal location, which is considered as evidence of neural plasticity in retinotopic early visual cortex. Recent findings demonstrate that transfer of learning to untrained locations can occur under some specific training procedures. Here, we evaluated whether exogenous attention facilitates transfer of perceptual learning to untrained locations, both adjacent to the trained locations (Experiment 1) and distant from them (Experiment 2). The results reveal that attention facilitates transfer of perceptual learning to untrained locations in both experiments, and that this transfer occurs both within and across visual hemifields. These findings show that training with exogenous attention is a powerful regime that is able to overcome the major limitation of location specificity. PMID:26426818

  5. Exogenous factors in panic disorder: clinical and research implications.

    PubMed

    Roy-Byrne, P P; Uhde, T W

    1988-02-01

    Because panic disorder has an underlying biologic and probably genetic basis, the role of factors outside the organism in initiating and sustaining panic is often overlooked. The authors review certain exogenous factors that seem capable of triggering attacks and/or increasing their frequency and intensity: self-administered pharmacologic agents (caffeine, alcohol, nicotine, over-the-counter cold preparations, cannabis, cocaine); habits (sleep deprivation, diet, exercise, relaxation, hyperventilation); and aspects of the environment (fluorescent lighting, life stressors). There may be a specificity to the action of some of these factors, because certain factors previously thought to trigger panic attacks (e.g., pain, hypoglycemia) have been proved not to have this effect. Although the clinical significance of many of the exogenous factors discussed still awaits empirical confirmation, attention to such factors during the initial evaluation of a patient with panic disorder may be helpful in formulating a successful treatment plan.

  6. Control of exogenous factors affecting plasma homovanillic acid concentration.

    PubMed

    Davidson, M; Giordani, A B; Mohs, R C; Mykytyn, V V; Platt, S; Aryan, Z S; Davis, K L

    1987-04-01

    Measurements of plasma homovanillic acid (pHVA) concentrations appear to be a valid research strategy in psychiatric disorders in which a central dopamine (DA) abnormality has been implicated. This study provides guidance about the control of some of the exogenous factors affecting pHVA concentrations. Fasting for 14 hours eliminates the dietary effects on pHVA in healthy human subjects. Changing position, walking for 30 minutes, or smoking two cigarettes has no effect on pHVA concentrations.

  7. Chemical-shift MRI of exogenous lipoid pneumonia

    SciTech Connect

    Cox, J.E.; Choplin, R.H.; Chiles, C.

    1996-05-01

    Exogenous lipoid pneumonia results from the aspiration or inhalation of fatty substances, such as mineral oil found in laxatives or nasal medications containing liquid paraffin. We present standard and lipid-sensitive (chemical-shift) MR findings in a patient with histologically confirmed lipoid pneumonia. The loss of signal intensity in an area of airspace disease on opposed-phase imaging was considered specific for the presence of lipid. 14 refs., 3 figs.

  8. Exogenous normal mammary epithelial mitochondria suppress glycolytic metabolism and glucose uptake of human breast cancer cells.

    PubMed

    Jiang, Xian-Peng; Elliott, Robert L; Head, Jonathan F

    2015-10-01

    We hypothesized that normal mitochondria inhibited cancer cell proliferation and increased drug sensitivity by the mechanism of suppression of cancer aerobic glycolysis. To demonstrate the mechanism, we used real-time PCR and glycolysis cell-based assay to measure gene expression of glycolytic enzymes and glucose transporters, and extracellular lactate production of human breast cancer cells. We found that isolated fluorescent probe-stained mitochondria of MCF-12A (human mammary epithelia) could enter into human breast cancer cell lines MCF-7, T47D, and MDA-MB-231, confirmed by fluorescent and confocal microscopy. Mitochondria from the untransformed human mammary epithelia increased drug sensitivity of MCF-7 cells to paclitaxel. Real-time PCR showed that exogenous normal mitochondria of MCF-12A suppressed gene expression of glycolytic enzymes, lactate dehydrogenase A, and glucose transporter 1 and 3 of MCF-7 and MDA-MB-231 cells. Glycolysis cell-based assay revealed that normal mitochondria significantly suppressed lactate production in culture media of MCF-7, T47D, and MDA-MB-231 cells. In conclusion, normal mitochondria suppress cancer proliferation and increase drug sensitivity by the mechanism of inhibition of cancer cell glycolysis and glucose uptake.

  9. Intestinal microbiota as a tetrahydrobiopterin exogenous source in hph-1 mice

    PubMed Central

    Belik, Jaques; Shifrin, Yulia; Arning, Erland; Bottiglieri, Teodoro; Pan, Jingyi; Daigneault, Michelle C.; Allen-Vercoe, Emma

    2017-01-01

    Tetrahydrobiopterin (BH4) is a cofactor of a number of regulatory enzymes. Although there are no known BH4 exogenous sources, the tissue content of this biopterin increases with age in GTP cyclohydrolase 1-deficient hyperphenylalaninemia-1 (hph-1) mice. Since certain bacteria are known to generate BH4, we hypothesize that generation of this biopterin by the intestinal microbiota contributes to its tissue increase in hph-1 adult mice. The goal of this study was to comparatively evaluate hph-1 mice and wild-type C57Bl/6 controls for the presence of intestinal BH4-producing bacteria. Newborn and adult mice fecal material was screened for 6-pyruvoyltetrahydropterin synthase (PTPS-2) an enzyme only present in BH4-generating bacteria. Adult, but not newborn, wild-type control and hph-1 mouse fecal material contained PTPS-2 mRNA indicative of the presence of BH4-generating bacteria. Utilizing chemostat-cultured human fecal bacteria, we identified the PTPS-2-producing bacteria as belonging to the Actinobacteria phylum. We further confirmed that at least two PTPS-2-producing species, Aldercreutzia equolifaciens and Microbacterium schleiferi, generate BH4 and are present in hph-1 fecal material. In conclusion, intestinal Actinobacteria generate BH4. This finding has important translational significance, since manipulation of the intestinal flora in individuals with congenital biopterin deficiency may allow for an increase in total body BH4 content. PMID:28079055

  10. [Exogenous Sr2+ sedimentation on otolith of chum salmon embryos].

    PubMed

    Wang, Chen; Liu, Wei; Zhan, Pei-rong; Wang, Ji-long; Li, Pei-lun

    2015-10-01

    To explore the exogenous Sr2+ sedimentation on otolith of chum salmon embryos, chum salmon embryos were exposed to culture water contained Sr2+ at Sr2+ concentration of 50, 100, 200 or 400 mg . L-1 for 48 h to imitate Sr2+ sedimentation. After a culturing period of 12 d and 100 d, the otoliths of the chum salmon were taken to detect exogenous Sr2+ sedimentation with electro-probe microanalyzer (EPMA). The results showed that obvious deep red strontium signatures were produced in the otolith of chum salmon at different concentrations of Sr2+. The mean and extreme values of peak strontium area were not stable for the same Sr2+ dose, but the lowest of all the peak values was 35.1 times as much as that of control. Overall, the strontium value increased with the increase of Sr2+concentration. The strontium peak had no signs of abating after a culture period of 100 d. The results also showed that strontium was gradually deposited in the otolith, and had obvious hysteresis to immersion. Strontium sedimentation could also return to a normal level after the peak. These characteristics accorded exactly with the requirement of discharge tag technology, which indicated that exogenous Sr2+ was suitable in the marking of salmon otolith.

  11. Exogenous Glutamine in Respiratory Diseases: Myth or Reality?

    PubMed Central

    Oliveira, Gisele P.; de Abreu, Marcelo Gama; Pelosi, Paolo; Rocco, Patricia R. M.

    2016-01-01

    Several respiratory diseases feature increased inflammatory response and catabolic activity, which are associated with glutamine depletion; thus, the benefits of exogenous glutamine administration have been evaluated in clinical trials and models of different respiratory diseases. Recent reviews and meta-analyses have focused on the effects and mechanisms of action of glutamine in a general population of critical care patients or in different models of injury. However, little information is available about the role of glutamine in respiratory diseases. The aim of the present review is to discuss the evidence of glutamine depletion in cystic fibrosis (CF), asthma, chronic obstructive pulmonary disease (COPD), acute respiratory distress syndrome (ARDS), and lung cancer, as well as the results of exogenous glutamine administration in experimental and clinical studies. Exogenous glutamine administration might be beneficial in ARDS, asthma, and during lung cancer treatment, thus representing a potential therapeutic tool in these conditions. Further experimental and large randomized clinical trials focusing on the development and progression of respiratory diseases are necessary to elucidate the effects and possible therapeutic role of glutamine in this setting. PMID:26861387

  12. Exogenous Glutamine in Respiratory Diseases: Myth or Reality?

    PubMed

    Oliveira, Gisele P; de Abreu, Marcelo Gama; Pelosi, Paolo; Rocco, Patricia R M

    2016-02-04

    Several respiratory diseases feature increased inflammatory response and catabolic activity, which are associated with glutamine depletion; thus, the benefits of exogenous glutamine administration have been evaluated in clinical trials and models of different respiratory diseases. Recent reviews and meta-analyses have focused on the effects and mechanisms of action of glutamine in a general population of critical care patients or in different models of injury. However, little information is available about the role of glutamine in respiratory diseases. The aim of the present review is to discuss the evidence of glutamine depletion in cystic fibrosis (CF), asthma, chronic obstructive pulmonary disease (COPD), acute respiratory distress syndrome (ARDS), and lung cancer, as well as the results of exogenous glutamine administration in experimental and clinical studies. Exogenous glutamine administration might be beneficial in ARDS, asthma, and during lung cancer treatment, thus representing a potential therapeutic tool in these conditions. Further experimental and large randomized clinical trials focusing on the development and progression of respiratory diseases are necessary to elucidate the effects and possible therapeutic role of glutamine in this setting.

  13. Exogenous antioxidants—Double-edged swords in cellular redox state

    PubMed Central

    Bohn, Torsten

    2010-01-01

    The balance between oxidation and antioxidation is believed to be critical in maintaining healthy biological systems. Under physiological conditions, the human antioxidative defense system including e.g., superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione (GSH) and others, allows the elimination of excess reactive oxygen species (ROS) including, among others superoxide anions (O2.-), hydroxyl radicals (OH.), alkoxyl radicals (RO.) and peroxyradicals (ROO.). However, our endogenous antioxidant defense systems are incomplete without exogenous originating reducing compounds such as vitamin C, vitamin E, carotenoids and polyphenols, playing an essential role in many antioxidant mechanisms in living organisms. Therefore, there is continuous demand for exogenous antioxidants in order to prevent oxidative stress, representing a disequilibrium redox state in favor of oxidation. However, high doses of isolated compounds may be toxic, owing to prooxidative effects at high concentrations or their potential to react with beneficial concentrations of ROS normally present at physiological conditions that are required for optimal cellular functioning. This review aims to examine the double-edged effects of dietary originating antioxidants with a focus on the most abundant compounds, especially polyphenols, vitamin C, vitamin E and carotenoids. Different approaches to enrich our body with exogenous antioxidants such as via synthetic antioxidants, diets rich in fruits and vegetables and taking supplements will be reviewed and experimental and epidemiological evidences discussed, highlighting that antioxidants at physiological doses are generally safe, exhibiting interesting health beneficial effects. PMID:20972369

  14. Exogenous γ-aminobutyric Acid (GABA) Application Improved Early Growth, Net Photosynthesis, and Associated Physio-Biochemical Events in Maize

    PubMed Central

    Li, Wu; Liu, Jianhua; Ashraf, Umair; Li, Gaoke; Li, Yuliang; Lu, Wenjia; Gao, Lei; Han, Fuguang; Hu, Jianguang

    2016-01-01

    γ-aminobutyric acid (GABA) is an endogenous signaling molecule and involved in growth regulations and plant development, however, a little information is available on the consequences of exogenous GABA application on growth, development, and associated physio-biochemical processes in maize. The present study examined the GABA-induced regulations in early growth, net photosynthetic rate, gas exchange, osmoregulation, and enzymatic activities in three maize cultivars, i.e., Yuecainuo 6, Zhengtian 68, and Yuecainuo 2. Two levels of GABA, i.e., 0 mg L-1 and 50 mg L-1, in solution form, with total application volume of 100 ml per pot containing 15 maize seedlings were exogenously applied. Results revealed that exogenous GABA application improved seedling growth in terms of seedling length and biomass accumulation in all maize cultivars at both 3 and 7 days after treatment (DAT). It also promoted net photosynthesis and variably affected gas exchange attributes, i.e., stomatal conductance (Gs), intercellular CO2 concentration (Ci), and transpiration rate (Tr), as well as leaves SPAD value. Furthermore, lipid peroxidation [in terms of malondialdehyde (MDA)] under GABA treated maize seedlings were also remained variable; however, osmolyte accumulation (protein and proline) and activities of anti-oxidants enzymes, i.e., super-oxide dismutase and peroxidase were also affected differently at both 3 and 7 DAT in all maize cultivars. Furthermore, enzymes involved in nitrogen metabolism, e.g., nitrate reductase and glutamine synthetase were improved. These results suggest the involvement of GABA in various physio-metablical mechanisms which might lead to improvement in morphological growth of maize. In future, research is still needed at molecular and genetic levels to unravel the involvement of GABA-mediated regulations in growth and its associated physio-biochemical mechanisms. PMID:27446149

  15. Exogenous γ-aminobutyric Acid (GABA) Application Improved Early Growth, Net Photosynthesis, and Associated Physio-Biochemical Events in Maize.

    PubMed

    Li, Wu; Liu, Jianhua; Ashraf, Umair; Li, Gaoke; Li, Yuliang; Lu, Wenjia; Gao, Lei; Han, Fuguang; Hu, Jianguang

    2016-01-01

    γ-aminobutyric acid (GABA) is an endogenous signaling molecule and involved in growth regulations and plant development, however, a little information is available on the consequences of exogenous GABA application on growth, development, and associated physio-biochemical processes in maize. The present study examined the GABA-induced regulations in early growth, net photosynthetic rate, gas exchange, osmoregulation, and enzymatic activities in three maize cultivars, i.e., Yuecainuo 6, Zhengtian 68, and Yuecainuo 2. Two levels of GABA, i.e., 0 mg L(-1) and 50 mg L(-1), in solution form, with total application volume of 100 ml per pot containing 15 maize seedlings were exogenously applied. Results revealed that exogenous GABA application improved seedling growth in terms of seedling length and biomass accumulation in all maize cultivars at both 3 and 7 days after treatment (DAT). It also promoted net photosynthesis and variably affected gas exchange attributes, i.e., stomatal conductance (Gs), intercellular CO2 concentration (Ci), and transpiration rate (Tr), as well as leaves SPAD value. Furthermore, lipid peroxidation [in terms of malondialdehyde (MDA)] under GABA treated maize seedlings were also remained variable; however, osmolyte accumulation (protein and proline) and activities of anti-oxidants enzymes, i.e., super-oxide dismutase and peroxidase were also affected differently at both 3 and 7 DAT in all maize cultivars. Furthermore, enzymes involved in nitrogen metabolism, e.g., nitrate reductase and glutamine synthetase were improved. These results suggest the involvement of GABA in various physio-metablical mechanisms which might lead to improvement in morphological growth of maize. In future, research is still needed at molecular and genetic levels to unravel the involvement of GABA-mediated regulations in growth and its associated physio-biochemical mechanisms.

  16. [A preliminary study on the effects of the exogenous creatine phosphate on rat masseter muscle after unilateral chew].

    PubMed

    Xu, Long-bo; Wang, Zi-xian; Qi, Dong; Lin, Xue-fen; Ying, Wang-gui; Sun, Sheng-jun; Chen, Bin; Ji, Ping

    2010-08-01

    To study the effect of energy therapy on Ca2+ concentration and Ca2+ -ATP enzyme activity in rat master muscle after unilateral chew, and to discuss the protective action of the exogenous creatine phosphate on rat masseter muscle after unilateral chew. The 20 rats were randomly divided into 4 groups, A: Creatine phosphate normal control group; B: Creatine phosphate experimental group; C: Saline normal control group; D: Saline experimental group. The Ca2+ concentration were determined by atomic absorption spectrophotometry, the activity of the Ca2+ -ATP enzyme were determined by super-micro volume Ca2+ -ATP enzyme kit. (1) The Ca2+ concentration of the extraction side of group D which received the saline injection had significant difference compared with the non-extraction side (P = 0.007), the group C (P = 0.009) and the extraction side of group B (P = 0.01); (2) Ca2+ -ATP enzyme activity of group D were higher than its non-extraction side (P = 0.001), group C (P = 0.003) and the extraction side of group B (P = 0.001); (3) The ultrastructural changes of the rat masseter muscle under transmission electron microscope were as follows: The extraction side of group D have more severe pathological manifestations than non-extraction side. Both the extraction side and the non-extraction side of group B had a similar manifestation to the normal control group. Exogenous energy material, creatine phosphate, may have certain degree of protective effect on rat masseter muscles after unilateral chew. And it may become a possible way to improve the injury of the masseter muscle.

  17. Effects of extracts of spices on rumen methanogenesis, enzyme activities and fermentation of feeds in vitro.

    PubMed

    Patra, Amlan Kumar; Kamra, Devki Nandan; Agarwal, Neeta

    2010-02-01

    An experiment was conducted to study the effects of boiling water, methanol and ethanol extracts (0, 0.25 and 0.50 mL) of seeds of Foeniculum vulgare (fennel), flower buds of Syzygium aromaticum (clove), bulbs of Allium sativum (garlic), bulbs of Allium cepa (onion) and roots of Zingiber officinalis (ginger) on rumen methanogenesis, fibrolytic enzyme activities and fermentation characteristics in vitro. Ethanol and methanol extracts of fennel, clove and garlic at 0.50 mL and clove at 0.25 mL inhibited (P < 0.05) methane production. Carboxymethylcellulase activity was reduced (P < 0.05) by ethanol and methanol extracts (0.50 mL) of fennel and clove (0.25 and 0.50 mL). The extracts of clove reduced (0.25 and 0.50 mL) xylanase and acetylesterase activities, and the fennel extract (0.50 mL) reduced (P < 0.05) xylanase activity. However, the extracts of garlic (0.50 mL) increased (P < 0.05) acetylesterase activity. Concentrations of volatile fatty acids were reduced (P < 0.05) by the extracts of garlic and onion. The extracts of garlic caused a decrease (P < 0.05) in acetate:propionate ratio (A:P) at 0.50 mL, whereas A:P was increased (P < 0.05) by the inclusion of 0.50 mL extracts of clove. Methanol and ethanol extracts of clove decreased (P < 0.05) in vitro organic matter degradability. Extracts (0.50 mL) of clove decreased (P < 0.05) the numbers of total protozoa, small entodiniomorphs and holotrichs, whereas extracts of onion, ginger and garlic enhanced (P < 0.05) protozoal numbers (both entodiniomorphs and holotrichs). Ethanol and methanol extracts of fennel and garlic have potential to inhibit rumen methanogenesis without adversely affecting rumen fermentation.

  18. Exogenous jasmonic acid can enhance tolerance of wheat seedlings to salt stress.

    PubMed

    Qiu, ZongBo; Guo, JunLi; Zhu, AiJing; Zhang, Liang; Zhang, ManMan

    2014-06-01

    Jasmonic acid (JA) is regarded as endogenous regulator that plays an important role in regulating stress responses, plant growth and development. To investigate the physiological mechanisms of salt stress mitigated by exogenous JA, foliar application of 2mM JA was done to wheat seedlings for 3days and then they were subjected to 150mM NaCl. Our results showed that 150mM NaCl treatment significantly decreased plant height, root length, shoot dry weight, root dry weight, the concentration of glutathione (GSH), chlorophyll b (Chl b) and carotenoid (Car), the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), enhanced the concentration of malondialdehyde (MDA), hydrogen peroxide (H2O2) and the rate of superoxide radical (O2•-) generation in the wheat seedlings when compared with the control. However, treatments with exogenous JA for 3 days significantly enhanced salt stress tolerance in wheat seedlings by decreasing the concentration of MDA and H2O2, the production rate of O2•- and increasing the transcript levels and activities of SOD, POD, CAT and APX and the contents of GSH, Chl b and Car, which, in turn, enhanced the growth of salt stressed seedlings. These results suggested that JA could effectively protect wheat seedlings from salt stress damage by enhancing activities of antioxidant enzymes and the concentration of antioxidative compounds to quench the excessive reactive oxygen species caused by salt stress and presented a practical implication for wheat cultivation in salt-affected soils. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Poliovirus polypeptide precursors: expression in vitro and processing by exogenous 3C and 2A proteinases.

    PubMed Central

    Nicklin, M J; Kräusslich, H G; Toyoda, H; Dunn, J J; Wimmer, E

    1987-01-01

    Plasmids have been constructed to generate substrates for the study of proteinases 2A and 3C of poliovirus. They contain the P1 (capsomer precursor) region of the poliovirus genome or P1 and part of P2 (a nonstructural precursor), which can be transcribed and translated in vitro. A transcript containing the entire 5' nontranslated region and the P1 region of the viral RNA gave poor translation in a reticulocyte translation system. Truncation of the 5' nontranslated region to its 3'-most segment gave acceptably good yields of radiolabeled P1. P1 was specifically processed to yield capsomer proteins by enzymes supplied in a postmitochondrial supernatant from poliovirus-infected cells. Thus, proteinase 3C can be supplied exogenously (in trans) and effect processing. This system may be used to provide P1 for the assay of proteinase 3C. Precursors that lacked either the 1A or 1D regions were poor substrates for proteinase 3C--observations that demonstrated a stringent structural requirement in processing by 3C. The translation product of a transcript encoding P1 and part of P2 was rapidly cleaved at the P1-P2 site in the absence of infected-cell extract. A transcript that contained a mutated 2A region gave a stable P1-P2 precursor that could be processed specifically by exogenous proteinase from infected-cell fractions. Processing of P1 appeared to require cleavage of the P1-P2 bond. These results support our previous data that 2A is the second polioviral proteinase and also provides a means of assaying proteinase 2A in vitro. Images PMID:3035560

  20. Application of Exogenous Ethylene Inhibits Postharvest Peel Browning of 'Huangguan' Pear.

    PubMed

    Ma, Yurong; Yang, Mengnan; Wang, Jingjing; Jiang, Cai-Zhong; Wang, Qingguo

    2016-01-01

    Peel browning disorder has an enormous impact on the exterior quality of 'Huangguan' pear whereas the underlying mechanism is still unclear. Although different methods have been applied for inhibiting the peel browning of 'Huangguan' pear, there are numerous issues associated with these approaches, such as time cost, efficacy, safety and stability. In this study, to develop a rapid, efficient and safe way to protect 'Huangguan' pear from skin browning, the effect of exogenous ethylene on peel browning of pear fruits stored at 0°C was evaluated. Results showed that ethylene treatments at 0.70-1.28 μL/L significantly decreased the browning rate and browning index from 73.80% and 0.30 to 6.80% and 0.02 after 20 days storage at 0°C, respectively, whereas ethylene treatments at 5 μL/L completely inhibited the occurrence of browning. In addition, ethylene treatments at 5 μL/L decreased the electrolyte leakage and respiration rate, delayed the loss of total phenolic compounds. Furthermore, ethylene (5 μL/L) treatment significantly enhanced the activity of catalase (CAT), ascorbate peroxidase (APX) and superoxide dismutase (SOD) and increased the 1, 1-diphenyl-2-picrylhydrazyl inhibition rate, but inhibited the activity of polyphenol oxidase (PPO) and peroxidase (POD). Our data revealed that ethylene prevented the peel browning through improving antioxidant enzymes (CAT, APX and SOD) activities and reducing PPO activity, electrolyte leakage rate and respiration rate. This study demonstrates that exogenous ethylene application may provide a safe and effective alternative method for controlling browning, and contributes to the understanding of peel browning of 'Huangguan' pear.

  1. Application of Exogenous Ethylene Inhibits Postharvest Peel Browning of ‘Huangguan’ Pear

    PubMed Central

    Ma, Yurong; Yang, Mengnan; Wang, Jingjing; Jiang, Cai-Zhong; Wang, Qingguo

    2017-01-01

    Peel browning disorder has an enormous impact on the exterior quality of ‘Huangguan’ pear whereas the underlying mechanism is still unclear. Although different methods have been applied for inhibiting the peel browning of ‘Huangguan’ pear, there are numerous issues associated with these approaches, such as time cost, efficacy, safety and stability. In this study, to develop a rapid, efficient and safe way to protect ‘Huangguan’ pear from skin browning, the effect of exogenous ethylene on peel browning of pear fruits stored at 0°C was evaluated. Results showed that ethylene treatments at 0.70–1.28 μL/L significantly decreased the browning rate and browning index from 73.80% and 0.30 to 6.80% and 0.02 after 20 days storage at 0°C, respectively, whereas ethylene treatments at 5 μL/L completely inhibited the occurrence of browning. In addition, ethylene treatments at 5 μL/L decreased the electrolyte leakage and respiration rate, delayed the loss of total phenolic compounds. Furthermore, ethylene (5 μL/L) treatment significantly enhanced the activity of catalase (CAT), ascorbate peroxidase (APX) and superoxide dismutase (SOD) and increased the 1, 1-diphenyl-2-picrylhydrazyl inhibition rate, but inhibited the activity of polyphenol oxidase (PPO) and peroxidase (POD). Our data revealed that ethylene prevented the peel browning through improving antioxidant enzymes (CAT, APX and SOD) activities and reducing PPO activity, electrolyte leakage rate and respiration rate. This study demonstrates that exogenous ethylene application may provide a safe and effective alternative method for controlling browning, and contributes to the understanding of peel browning of ‘Huangguan’ pear. PMID:28149298

  2. Fundamentals of enzyme kinetics.

    PubMed

    Seibert, Eleanore; Tracy, Timothy S

    2014-01-01

    This chapter provides a general introduction to the kinetics of enzyme-catalyzed reactions, with a focus on drug-metabolizing enzymes. A prerequisite to understanding enzyme kinetics is having a clear grasp of the meanings of "enzyme" and "catalysis." Catalysts are reagents that can increase the rate of a chemical reaction without being consumed in the reaction. Enzymes are proteins that form a subset of catalysts. These concepts are further explored below.

  3. Effect of pancreatic enzyme supplements on iron absorption.

    PubMed

    Zempsky, W T; Rosenstein, B J; Carroll, J A; Oski, F A

    1989-08-01

    Iron deficiency has been reported in one third of patients with cystic fibrosis. There are data that suggest that iron absorption is increased with exocrine pancreatic deficiency and that administration of pancreatic enzymes may impair oral iron absorption. We compared oral iron absorption over a 3-hour period in the presence and absence of exogenous pancreatic enzymes in 13 stable young-adult patients with cystic fibrosis and 9 age-matched control patients. Although none of the patients with cystic fibrosis had a hemoglobin level less than 119 g/L, serum ferritin levels were less than 25 micrograms/L in 5 of the 13 patients, and the mean corpuscular volume was significantly lower in the patient group (86.1 +/- 2.7 vs 90.9 +/- 5 fL). Baseline mean serum iron levels were higher in controls (18.9 +/- 5.9 mumol/L) than in patients (11.9 +/- 6.3 mumol/L). There was no difference in iron absorption in the absence of exogenous pancreatic enzymes. Significant impairment of iron absorption was detected in both patients with cystic fibrosis and controls after administration of a preparation of pancreatic enzymes. There was an inverse relationship between iron stores, as measured by serum ferritin, and iron absorption. These findings suggest that long-term consumption of pancreatic enzymes by patients with cystic fibrosis may contribute to iron deficiency.

  4. Static magnetic field reduced exogenous oligonucleotide uptake by spermatozoa using magnetic nanoparticle gene delivery system

    NASA Astrophysics Data System (ADS)

    Katebi, Samira; Esmaeili, Abolghasem; Ghaedi, Kamran

    2016-03-01

    Spermatozoa could introduce exogenous oligonucleotides of interest to the oocyte. The most important reason of low efficiency of sperm mediated gene transfer (SMGT) is low uptake of exogenous DNA by spermatozoa. The aim of this study was to evaluate the effects of static magnetic field on exogenous oligonucleotide uptake of spermatozoa using magnetofection method. Magnetic nanoparticles (MNPs) associated with the labeled oligonucleotides were used to increase the efficiency of exogenous oligonucleotide uptake by rooster spermatozoa. We used high-field/high-gradient magnet (NdFeB) to enhance and accelerate exogenous DNA sedimentation at the spermatozoa surface. Flow cytometry analysis was performed to measure viability and percentage of exogenous oligonucleotide uptake by sperm. Flow cytometry analysis showed a significant increase in exogenous oligonucleotide uptake by rooster spermatozoa (P<0.001) when spermatozoa were incubated in exogenous oligonucleotide solution and MNPs. However, by applying static magnetic field during magnetofection method, a significant decrease in exogenous oligonucleotide uptake was observed (P<0.05). Findings of this study showed that MNPs were effective to increase exogenous oligonucleotide uptake by rooster spermatozoa; however unlike others studies, static magnetic field, was not only ineffective to enhance exogenous oligonucleotide uptake by rooster spermatozoa but also led to reduction in efficiency of magnetic nanoparticles in gene transfer.

  5. [Response of reactive oxygen metabolism in melon chloroplasts to short-term salinity-alkalinity stress regulated by exogenous γ-aminobutyric acid].

    PubMed

    Xiang, Li-xia; Hu, Li-pan; Hu, Xiao-hui; Pan, Xiong-bo; Ren, Wen-qi

    2015-12-01

    The regulatory effect of exogenous γ-aminobutyric acid (GABA) on metabolism of reactive oxygen species (ROS) in melon chloroplasts under short-term salinity-alkalinity stress were investigated in melon variety 'Jinhui No. 1', which was cultured with deep flow hydroponics. The result showed that under salinity-alkalinity stress, the photosynthetic pigment content, MDA content, superoxide anion (O₂·) production rate and hydrogen peroxide (H₂O₂) content in chloroplast increased significantly, the contents of antioxidants ascorbic acid (AsA) and glutathione (GSH) increased, and the activities of H⁺-ATPase and H⁺-PPiase were inhibited obviously. With exogenous GABA application, the accumulations of O₂·, MDA and H₂O₂ induced by salinity-alkalinity stress were inhibited. Exogenous GABA alleviated the increase of photosynthetic pigment content, improved the activity of SOD, enzymes of AsA-GSH cycle, total AsA and total GSH while decreased the AsA/DHA ratio and GSH/GSSH ratio. Foliar GABA could enhance the H⁺-ATPase and H⁺-PPiase activities. Our results suggested that the exogenous GABA could accelerate the ROS metabolism in chloroplast, promote the recycle of AsA-GSH, and maintain the permeability of cell membrane to improve the ability of melon chloroplast against salinity-alkalinity stress.

  6. Improved control of exogenous attention in action video game players

    PubMed Central

    Cain, Matthew S.; Prinzmetal, William; Shimamura, Arthur P.; Landau, Ayelet N.

    2014-01-01

    Action video game players (VGPs) have demonstrated a number of attentional advantages over non-players. Here, we propose that many of those benefits might be underpinned by improved control over exogenous (i.e., stimulus-driven) attention. To test this we used an anti-cueing task, in which a sudden-onset cue indicated that the target would likely appear in a separate location on the opposite side of the fixation point. When the time between the cue onset and the target onset was short (40 ms), non-players (nVGPs) showed a typical exogenous attention effect. Their response times were faster to targets presented at the cued (but less probable) location compared with the opposite (more probable) location. VGPs, however, were less likely to have their attention drawn to the location of the cue. When the onset asynchrony was long (600 ms), VGPs and nVGPs were equally able to endogenously shift their attention to the likely (opposite) target location. In order to rule out processing-speed differences as an explanation for this result, we also tested VGPs and nVGPs on an attentional blink (AB) task. In a version of the AB task that minimized demands on task switching and iconic memory, VGPs and nVGPs did not differ in second target identification performance (i.e., VGPs had the same magnitude of AB as nVGPs), suggesting that the anti-cueing results were due to flexible control over exogenous attention rather than to more general speed-of-processing differences. PMID:24575061

  7. Exogenous attention enhances 2nd-order contrast sensitivity

    PubMed Central

    Barbot, Antoine; Landy, Michael S.; Carrasco, Marisa

    2011-01-01

    Natural scenes contain a rich variety of contours that the visual system extracts to segregrate the retinal image into perceptually coherent regions. Covert spatial attention helps extract contours by enhancing contrast sensitivity for 1st-order, luminance-defined patterns at attended locations, while reducing sensitivity at unattended locations, relative to neutral attention allocation. However, humans are also sensitive to 2nd-order patterns such as spatial variations of texture, which are predominant in natural scenes and cannot be detected by linear mechanisms. We assess whether and how exogenous attention—the involuntary and transient capture of spatial attention—affects the contrast sensitivity of channels sensitive to 2nd-order, texture-defined patterns. Using 2nd-order, texture-defined stimuli, we demonstrate that exogenous attention increases 2nd-order contrast sensitivity at the attended location, while decreasing it at unattended locations, relative to a neutral condition. By manipulating both 1st- and 2nd-order spatial frequency, we find that the effects of attention depend both on 2nd-order spatial frequency of the stimulus and the observer’s 2nd-order spatial resolution at the target location. At parafoveal locations, attention enhances 2nd-order contrast sensitivity to high, but not to low 2nd-order spatial frequencies; at peripheral locations attention also enhances sensitivity to low 2nd-order spatial frequencies. Control experiments rule out the possibility that these effects might be due to an increase in contrast sensitivity at the 1st-order stage of visual processing. Thus, exogenous attention affects 2nd-order contrast sensitivity at both attended and unattended locations. PMID:21356228

  8. Improved control of exogenous attention in action video game players.

    PubMed

    Cain, Matthew S; Prinzmetal, William; Shimamura, Arthur P; Landau, Ayelet N

    2014-01-01

    Action video game players (VGPs) have demonstrated a number of attentional advantages over non-players. Here, we propose that many of those benefits might be underpinned by improved control over exogenous (i.e., stimulus-driven) attention. To test this we used an anti-cueing task, in which a sudden-onset cue indicated that the target would likely appear in a separate location on the opposite side of the fixation point. When the time between the cue onset and the target onset was short (40 ms), non-players (nVGPs) showed a typical exogenous attention effect. Their response times were faster to targets presented at the cued (but less probable) location compared with the opposite (more probable) location. VGPs, however, were less likely to have their attention drawn to the location of the cue. When the onset asynchrony was long (600 ms), VGPs and nVGPs were equally able to endogenously shift their attention to the likely (opposite) target location. In order to rule out processing-speed differences as an explanation for this result, we also tested VGPs and nVGPs on an attentional blink (AB) task. In a version of the AB task that minimized demands on task switching and iconic memory, VGPs and nVGPs did not differ in second target identification performance (i.e., VGPs had the same magnitude of AB as nVGPs), suggesting that the anti-cueing results were due to flexible control over exogenous attention rather than to more general speed-of-processing differences.

  9. Exogenous ammonium inhibits petal pigmentation and expansion in Gerbera hybrida.

    PubMed

    Huang, Zhigang; Liang, Minting; Peng, Jianzong; Xing, Tim; Wang, Xiaojing

    2008-06-01

    Petal pigmentation is the most important aspect in natural flower coloration. In the present study, the inhibition of petal pigmentation by exogenous ammonium was investigated. Ray floret petals detached from inflorescences of Gerbera hybrida (Shenzhen No. 5) were cultured in vitro on media supplied with different forms of nitrogen and its assimilated compounds. The expression of a set of genes involved in anthocyanin biosynthesis and regulation was determined by Northern blotting assay. It was found that ammonium (NH4+), not nitrate (NO3-), in millimolar concentrations inhibited anthocyanin accumulation. The expressions of Gerbera chalcone synthase 1 (GCHS1), Gerbera chalcone synthase 2 (GCHS2) and Gerbera dihydroflavonol-4-reductase (GDFR) decreased, while six other related genes showed no significant changes after NH4+ treatment. Further studies on NH4+ function indicated that glutamine (Gln) acted as a downstream factor of NH4+ to suppress petal pigmentation. Both exogenous Gln and NH4+ were found to inhibit anthocyanin accumulation in the petals, and the application of Gln was also found to inhibit the expressions of GCHS1, GCHS2 and GDFR. The application of NH4+ also resulted in an increase in the activity of Gerbera glutamine synthetase (EC 6.3.1.2) along with a rapid increase of Gln content. When methionine sulfoximine, an inhibitor of glutamine synthetase (GS), was added, it was found to block the NH4+-induced inhibition of pigmentation. From these experiments, we conclude that the NH4+-induced suppression of petal pigmentation is not because of NH4+ toxicity, and the inhibition of pigmentation caused by the addition of exogenous NH4+ is the result of its assimilation into Gln.

  10. Exogenous attention enhances 2nd-order contrast sensitivity.

    PubMed

    Barbot, Antoine; Landy, Michael S; Carrasco, Marisa

    2011-05-11

    Natural scenes contain a rich variety of contours that the visual system extracts to segregate the retinal image into perceptually coherent regions. Covert spatial attention helps extract contours by enhancing contrast sensitivity for 1st-order, luminance-defined patterns at attended locations, while reducing sensitivity at unattended locations, relative to neutral attention allocation. However, humans are also sensitive to 2nd-order patterns such as spatial variations of texture, which are predominant in natural scenes and cannot be detected by linear mechanisms. We assess whether and how exogenous attention--the involuntary and transient capture of spatial attention--affects the contrast sensitivity of channels sensitive to 2nd-order, texture-defined patterns. Using 2nd-order, texture-defined stimuli, we demonstrate that exogenous attention increases 2nd-order contrast sensitivity at the attended location, while decreasing it at unattended locations, relative to a neutral condition. By manipulating both 1st- and 2nd-order spatial frequency, we find that the effects of attention depend both on 2nd-order spatial frequency of the stimulus and the observer's 2nd-order spatial resolution at the target location. At parafoveal locations, attention enhances 2nd-order contrast sensitivity to high, but not to low 2nd-order spatial frequencies; at peripheral locations attention also enhances sensitivity to low 2nd-order spatial frequencies. Control experiments rule out the possibility that these effects might be due to an increase in contrast sensitivity at the 1st-order stage of visual processing. Thus, exogenous attention affects 2nd-order contrast sensitivity at both attended and unattended locations. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. Glucose polymer molecular weight does not affect exogenous carbohydrate oxidation.

    PubMed

    Rowlands, David S; Wallis, Gareth A; Shaw, Chris; Jentjens, Roy L P G; Jeukendrup, Asker E

    2005-09-01

    To compare the effects of high (HMW) versus low molecular weight (LMW) glucose polymer solutions on the pattern of substrate oxidation during exercise. Eight cyclists (VO(2max): 63 +/- 8 mL.kg(-1).min(-1)) performed three 150-min cycling trials at 64 +/- 5% VO(2max) while ingesting 11.25% HMW (500-750 kg.mol(-1), 21 mOsm.kg(-1)) or LMW (8 kg.mol(-1), 110 mOsm.kg(-1)) solutions providing 1.8 g of carbohydrate per minute, or plain water. Substrate oxidation was determined using stable-isotope methods and indirect calorimetry. Exogenous carbohydrate oxidation rate was not affected by carbohydrate molecular weight (P = 0.89, peak rate: 0.93 x// 1.37 g.min(-1)). There was no effect of carbohydrate molecular weight on endogenous carbohydrate or fat oxidation rates (P = 0.30), plasma free fatty acid (P = 0.14), lactate (P = 0.38), or glucose concentrations (P = 0.98), nor were there any serious gastrointestinal complaints reported for either of the two solutions during exercise. Despite previous reports of faster gastric emptying and glycogen resynthesis suggesting enhanced glucose delivery, a markedly hypotonic HMW glucose polymer solution had no effect on exogenous and endogenous substrate oxidation rates during exercise, relative to a LMW glucose polymer solution. These data are consistent with there being no effect of carbohydrate structure or solution osmolality or viscosity on exogenous glucose oxidation and that ingested glucose polymers can only be oxidized on average up to 1.0 g.min during exercise.

  12. Response of firm agent network to exogenous shock

    NASA Astrophysics Data System (ADS)

    Ikeda, Yuichi; Aoyama, Hideaki; Iyetomi, Hiroshi; Fujiwara, Yoshi; Souma, Wataru; Kaizoji, Taisei

    2007-08-01

    This paper describes an agent-based model of interacting firms, in which interacting firm agents rationally invest capital and labor in order to maximize payoff. Both transactions and production are taken into account in this model. First, the performance of individual firms on a real transaction network was simulated. The simulation quantitatively reproduced the cumulative probability distribution of revenue, material cost, capital, and labor. Then, the response of the firms to a given exogenous shock, defined as a sudden change of gross domestic product, is discussed. The longer tail in cumulative probability and skewed distribution of growth rate are observed for a high growth scenario.

  13. Development of a universal RNA beacon for exogenous gene detection.

    PubMed

    Guo, Yuanjian; Lu, Zhongju; Cohen, Ira Stephen; Scarlata, Suzanne

    2015-05-01

    Stem cell therapy requires a nontoxic and high-throughput method to achieve a pure cell population to prevent teratomas that can occur if even one cell in the implant has not been transformed. A promising method to detect and separate cells expressing a particular gene is RNA beacon technology. However, developing a successful, specific beacon to a particular transfected gene can take months to develop and in some cases is impossible. Here, we report on an off-the-shelf universal beacon that decreases the time and cost of applying beacon technology to select any living cell population transfected with an exogenous gene. ©AlphaMed Press.

  14. Development of a Universal RNA Beacon for Exogenous Gene Detection

    PubMed Central

    Guo, Yuanjian; Lu, Zhongju; Cohen, Ira Stephen

    2015-01-01

    Stem cell therapy requires a nontoxic and high-throughput method to achieve a pure cell population to prevent teratomas that can occur if even one cell in the implant has not been transformed. A promising method to detect and separate cells expressing a particular gene is RNA beacon technology. However, developing a successful, specific beacon to a particular transfected gene can take months to develop and in some cases is impossible. Here, we report on an off-the-shelf universal beacon that decreases the time and cost of applying beacon technology to select any living cell population transfected with an exogenous gene. PMID:25769653

  15. Exogenous agents that target transmembrane domains of proteins.

    PubMed

    Yin, Hang

    2008-01-01

    Although membrane proteins account for approximately one third of all proteins encoded in the human genome, the functions and structures of their transmembrane domains are much less understood than the water-soluble regions. A major hurdle in studying these transmembrane domains is the lack of appropriate exogenous agents that can be used as specific probes. Despite the daunting challenges, major strides have recently been made in targeting the transmembrane domains of a variety of membrane proteins. High affinity and selectivity have been achieved in model biophysical systems, membranes of bacteria, and mammalian cells.

  16. Switched linear model predictive controllers for periodic exogenous signals

    NASA Astrophysics Data System (ADS)

    Wang, Liuping; Gawthrop, Peter; Owens, David. H.; Rogers, Eric

    2010-04-01

    This article develops switched linear controllers for periodic exogenous signals using the framework of a continuous-time model predictive control. In this framework, the control signal is generated by an algorithm that uses receding horizon control principle with an on-line optimisation scheme that permits inclusion of operational constraints. Unlike traditional repetitive controllers, applying this method in the form of switched linear controllers ensures bumpless transfer from one controller to another. Simulation studies are included to demonstrate the efficacy of the design with or without hard constraints.

  17. Comparative proteomic and physiological analyses reveal the protective effect of exogenous calcium on the germinating soybean response to salt stress.

    PubMed

    Yin, Yongqi; Yang, Runqiang; Han, Yongbin; Gu, Zhenxin

    2015-01-15

    Calcium enhances salt stress tolerance of soybeans. Nevertheless, the molecular mechanism of calcium's involvement in resistance to salt stress is unclear. A comparative proteomic approach was used to investigate protein profiles in germinating soybeans under NaCl-CaCl2 and NaCl-LaCl3 treatments. A total of 80 proteins affected by calcium in 4-day-old germinating soybean cotyledons and 71 in embryos were confidently identified. The clustering analysis showed proteins were subdivided into 5 and 6 clusters in cotyledon and embryo, respectively. Among them, proteins involved in signal transduction and energy pathways, in transportation, and in protein biosynthesis were largely enriched while those involved in proteolysis were decreased. Abundance of nucleoside diphosphate kinase and three antioxidant enzymes were visibly increased by calcium. Accumulation of gamma-aminobutyric acid and polyamines was also detected after application of exogenous calcium. This was consistent with proteomic results, which showed that proteins involved in the glutamate and methionine metabolism were mediated by calcium. Calcium could increase the salt stress tolerance of germinating soybeans via enriching signal transduction, energy pathway and transportation, promoting protein biosynthesis, inhibiting proteolysis, redistributing storage proteins, regulating protein processing in endoplasmic reticulum, enriching antioxidant enzymes and activating their activities, accumulating secondary metabolites and osmolytes, and other adaptive responses. Biological significance Soybean (Glycine max L.), as a traditional edible legume, is being targeted for designing functional foods. During soybean germination under stressful conditions especially salt stress, newly discovered functional components such as gamma-aminobutyric acid (GABA) are rapidly accumulated. However, soybean plants are relatively salt-sensitive and the growth, development and biomass of germinating soybeans are significantly

  18. Role of Lysosomal Enzyme Release in Circulatory Shock and Critical Illness.

    DTIC Science & Technology

    1978-06-01

    association of lysosomal enzyme release and the severity of shock in the human system in states of circulatory shocl4 and conditions of critical...antereo) 6-iI SUMMARY To determine the association of lysosomal enzyme release and the severity of shock in the human system in states of circulatory...The results, however, do not show any adverse effects from the introduction of exogenous cathepsin D into the systemic circulation during hemorrhagic

  19. Insolubilization process increases enzyme stability

    NASA Technical Reports Server (NTRS)

    Billingham, J.; Lyn, J.

    1971-01-01

    Enzymes complexed with polymeric matrices contain properties suggesting application to enzyme-controlled reactions. Stability of insolubilized enzyme derivatives is markedly greater than that of soluble enzymes and physical form of insolubilized enzymes is useful in column and batch processes.

  20. Exogenous spermidine improves seed germination of white clover under water stress via involvement in starch metabolism, antioxidant defenses and relevant gene expression.

    PubMed

    Li, Zhou; Peng, Yan; Zhang, Xin-Quan; Ma, Xiao; Huang, Lin-Kai; Yan, Yan-Hong

    2014-11-05

    This study was designed to determine the effect of exogenous spermidine (Spd) (30 μM) on white clover seed germination under water stress induced by polyethylene glycol 6000. Use of seed priming with Spd improved seed germination percentage, germination vigor, germination index, root viability and length, and shortened mean germination time under different water stress conditions. Seedling fresh weight and dry weight also increased significantly in Spd-treated seeds compared with control (seeds primed with distilled water). Improved starch metabolism was considered a possible reason for this seed invigoration, since seeds primed with Spd had significantly increased α-amylase/β-amylase activities, reducing sugar, fructose and glucose content and transcript level of β-amylase gene but not transcript level of α-amylase gene. In addition, the physiological effects of exogenous Spd on improving seeds' tolerance to water deficit during germination were reflected by lower lipid peroxidation levels, better cell membrane stability and significant higher seed vigour index in seedlings. Enhanced antioxidant enzyme activities (superoxide dismutase, peroxidase, catalase and ascorbate peroxidase), ascorbate-glutathione cycle (ASC-GSH cycle) and transcript level of genes encoding antioxidant enzymes induced by exogenous Spd may be one of the critical reasons behind acquired drought tolerance through scavenging of reactive oxygen species (ROS) in water-stressed white clover seeds. The results indicate that Spd plays an important function as a stress-protective compound or physiological activator.

  1. Exogenously applied nitrate improves the photosynthetic performance and nitrogen metabolism in tomato (Solanumlycopersicum L. cv Pusa Rohini) under arsenic (V) toxicity.

    PubMed

    Agnihotri, Ashish; Seth, Chandra Shekhar

    2016-07-01

    Tomato (Solanum lycopersicum L.) being a widespread and most commonly consumed vegetable all over the world has an important economic value for its producers and related food industries. It is a serious matter of concern as its production is affected by arsenic present in soil. So, the present study, investigated the toxicity of As(V) on photosynthetic performance along with nitrogen metabolism and its alleviation by exogenous application of nitrate. Plants were grown under natural conditions using soil spiked with 25 mg and 20 mM, As(V) and nitrate, respectively. Our results revealed that plant growth indices, photosynthetic pigments, and other major photosynthetic parameters like net photosynthetic rate and maximum quantum efficiency (Fv/Fm ) of photosystem II (PSII) were significantly (P ≤ 0.05) reduced under As(V) stress. However, nitrate application significantly (P ≤ 0.05) alleviated As(V) toxicity by improving the aforesaid plant responses and also restored the abnormal shape of guard cells. Nitrogen metabolism was assessed by studying the key nitrogen-metabolic enzymes. Exogenous nitrate revamped nitrogen metabolism through a major impact on activities of NR, NiR, GS and GOGAT enzymes and also enhanced the total nitrogen and NO content while malondialdehyde content, and membrane electrolytic leakage were remarkably reduced. Our study suggested that exogenous nitrate application could be considered as a cost effective approach in ameliorating As(V) toxicity.

  2. Dynamic Financial Constraints: Distinguishing Mechanism Design from Exogenously Incomplete Regimes*

    PubMed Central

    Karaivanov, Alexander; Townsend, Robert M.

    2014-01-01

    We formulate and solve a range of dynamic models of constrained credit/insurance that allow for moral hazard and limited commitment. We compare them to full insurance and exogenously incomplete financial regimes (autarky, saving only, borrowing and lending in a single asset). We develop computational methods based on mechanism design, linear programming, and maximum likelihood to estimate, compare, and statistically test these alternative dynamic models with financial/information constraints. Our methods can use both cross-sectional and panel data and allow for measurement error and unobserved heterogeneity. We estimate the models using data on Thai households running small businesses from two separate samples. We find that in the rural sample, the exogenously incomplete saving only and borrowing regimes provide the best fit using data on consumption, business assets, investment, and income. Family and other networks help consumption smoothing there, as in a moral hazard constrained regime. In contrast, in urban areas, we find mechanism design financial/information regimes that are decidedly less constrained, with the moral hazard model fitting best combined business and consumption data. We perform numerous robustness checks in both the Thai data and in Monte Carlo simulations and compare our maximum likelihood criterion with results from other metrics and data not used in the estimation. A prototypical counterfactual policy evaluation exercise using the estimation results is also featured. PMID:25246710

  3. Whole body autoradiographic distribution of exogenously administered renin in mice

    SciTech Connect

    Iwao, H.; Nakamura, N.; Ikemoto, F.; Yamamoto, K.

    1983-06-01

    The distribution of exogenously administered renin was investigated using whole body autoradiography. Purified renin from mouse submaxillary gland (SR) was labeled with radioactive iodine (/sup 125/I). This labeled renin (/sup 125/I-SR) and Na/sup 125/I were administered into the tail vein of male ddY mice, in doses of 10.2 and 16.4 mu Ci/30 g body weight, respectively. Mice were killed by an overdose of ether, and autoradiography was performed on whole body sections. To separate free /sup 125/I liberated from /sup 125/I-SR, sections were treated with perchloric acid. A major accumulation of /sup 125/I-SR, acid-insoluble, was evident in the renal cortex, whereas the hepatic accumulation of /sup 125/I-SR was minor. Radioactivity in the thyroid and submaxillary glands, in the stomach, and in urine was also apparent, but disappeared after acid treatment, except in the thyroid glands. Radioactivity in the brain, intestinal content, spleen, and adrenal glands was nil. These autoradiograms provide the first evidence that exogenously administered renin is mainly distributed in the renal cortex.

  4. Partial Granger causality--eliminating exogenous inputs and latent variables.

    PubMed

    Guo, Shuixia; Seth, Anil K; Kendrick, Keith M; Zhou, Cong; Feng, Jianfeng

    2008-07-15

    Attempts to identify causal interactions in multivariable biological time series (e.g., gene data, protein data, physiological data) can be undermined by the confounding influence of environmental (exogenous) inputs. Compounding this problem, we are commonly only able to record a subset of all related variables in a system. These recorded variables are likely to be influenced by unrecorded (latent) variables. To address this problem, we introduce a novel variant of a widely used statistical measure of causality--Granger causality--that is inspired by the definition of partial correlation. Our 'partial Granger causality' measure is extensively tested with toy models, both linear and nonlinear, and is applied to experimental data: in vivo multielectrode array (MEA) local field potentials (LFPs) recorded from the inferotemporal cortex of sheep. Our results demonstrate that partial Granger causality can reveal the underlying interactions among elements in a network in the presence of exogenous inputs and latent variables in many cases where the existing conditional Granger causality fails.

  5. Saccade latency indexes exogenous and endogenous object-based attention.

    PubMed

    Şentürk, Gözde; Greenberg, Adam S; Liu, Taosheng

    2016-10-01

    Classic studies of object-based attention have utilized keypress responses as the main dependent measure. However, people typically make saccades to fixate important objects. Recent work has shown that attention may act differently when it is deployed covertly versus in advance of a saccade. We further investigated the link between saccades and attention by examining whether object-based effects can be observed for saccades. We adapted the classical double-rectangle cueing paradigm of Egly, Driver, and Rafal (1994), and measured both the first saccade latency and the keypress reaction time (RT) to a target that appeared at the end of one of the two rectangles. Our results showed that saccade latencies exhibited higher sensitivity than did RTs for detecting effects of attention. We also assessed the generality of the attention effects by testing three types of cues: hybrid (predictive and peripheral), exogenous (nonpredictive and peripheral), and endogenous (predictive and central). We found that both RTs and saccade latencies exhibited effects of both space-based and object-based attentional selection. However, saccade latencies showed a more robust attentional modulation than RTs. For the exogenous cues, we observed a spatial inhibition of return along with an object-based effect, implying that object-based attention is independent of space-based attention. Overall, our results revealed an oculomotor correlate of object-based attention, suggesting that, in addition to spatial priority, object-level priority also affects saccade planning.

  6. Exogenic geomorphic processes dynamics at the Black Sea coast, Russia

    NASA Astrophysics Data System (ADS)

    Kuznetsova, Yulia; Tsvetkova, Daria

    2017-04-01

    Nowadays there is an obvious grow of anthropogenic load going on in many areas worldwide. Under such conditions, intensive activation of a number of exogenic geomorphic processes may be observed. Moreover, if natural environment is aggressive itself their dynamics and rates may reach enormous values. Our work is conducted at the Black Sea coast, known for its mountainous topography, wet subtropical climate and intensive anthropogenic development (especially during the last decade due to the recent Olympic games). We chose two key basins near Sochi, Russia to study a number of presented exogenic processes, including rill, gully and channel erosion, weathering, suffusion and piping, soil creep. A set of field study methods is used to monitor the processes dynamics since 2005 (and late 1970s for soil creep). In addition, soil erosion rates and landslide susceptibility were modelled to get information of the watersheds dynamics. This is ongoing work, but the results of the passed period of observations will be resented. Special attention is paid to the processes connectivity and their input into sediment redistribution over the river basins.

  7. Role of Exogenous Hsp72 on Liver Dysfunction during Sepsis.

    PubMed

    Tsai, Tsen-Ni; Ho, Jia-Jing; Liu, Maw-Shung; Lee, Tzu-Ying; Lu, Mei-Chin; Liu, Chia-Jen; Huang, Li-Ju; Lue, Sheng-I; Yang, Rei-Chen

    2015-01-01

    This study examined the role of exogenous heat shock protein 72 (Hsp72) in reversing sepsis-induced liver dysfunction. Sepsis was induced by cecal ligation and puncture. Liver function was determined on the basis of the enzymatic activities of serum glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT). Apoptosis was determined using terminal deoxynucleotidyl transferase dUTP nick end labeling staining. B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), cleaved caspase-3 and caspase-9, and cleaved poly (ADP-ribose) polymerase (PARP) protein expressions were analyzed using Western blotting. Results showed GOT and GPT levels increased during sepsis, and levels were restored following the administration of human recombinant Hsp72 (rhHsp72). Increased liver tissue apoptosis was observed during sepsis, and normal apoptosis resumed on rhHsp72 administration. The Bcl-2/Bax ratio, cleaved caspase-3, caspase-9, and PARP protein expressions in the liver tissues were upregulated during sepsis and normalized after rhHsp72 treatment. We conclude that, during sepsis, exogenous Hsp72 restored liver dysfunction by inhibiting apoptosis via the mitochondria-initiated caspase pathway.

  8. The interactions of multisensory integration with endogenous and exogenous attention.

    PubMed

    Tang, Xiaoyu; Wu, Jinglong; Shen, Yong

    2016-02-01

    Stimuli from multiple sensory organs can be integrated into a coherent representation through multiple phases of multisensory processing; this phenomenon is called multisensory integration. Multisensory integration can interact with attention. Here, we propose a framework in which attention modulates multisensory processing in both endogenous (goal-driven) and exogenous (stimulus-driven) ways. Moreover, multisensory integration exerts not only bottom-up but also top-down control over attention. Specifically, we propose the following: (1) endogenous attentional selectivity acts on multiple levels of multisensory processing to determine the extent to which simultaneous stimuli from different modalities can be integrated; (2) integrated multisensory events exert top-down control on attentional capture via multisensory search templates that are stored in the brain; (3) integrated multisensory events can capture attention efficiently, even in quite complex circumstances, due to their increased salience compared to unimodal events and can thus improve search accuracy; and (4) within a multisensory object, endogenous attention can spread from one modality to another in an exogenous manner.

  9. Ultrastructure of exogenous surfactants using cryogenic scanning electron microscopy.

    PubMed

    Banerjee, R; Bellare, J R

    2001-01-01

    Therapy with specialised biomaterials, exogenous surfactants, is known to significantly decrease the mortality rates in Respiratory Distress Syndrome (RDS). Surfactants available commercially vary widely in composition and biophysical properties. The present paper studies the ultrastructure of three exogenous surfactants used for the treatment of Respiratory Distress Syndrome, namely, Survanta, ALEC and Exosurf Neonatal with respect to their ability to form liposomes using cryogenic scanning electron microscopy. Liposomal organisation is more obvious in Exosurf than in Survanta and is most pronounced in ALEC. ALEC forms closed regular liposomes with an onion-ring-like internal bilayer arrangement. Survanta forms open membranous structures with wavy ribbon-like membranes. The complex membrane-like structures seen with Survanta may be due to the interaction of lipids with surfactant-specific proteins present in this surfactant which is derived from natural lung extracts and might indicate superior spreading at the lipid-water interface. Artificial protein-free surfactants (ALEC and Exosurf) did not appear to form these open membranous structures. Further study of the ultrastructure of possible biomaterials as surfactants could help in the development of new, improved artificial protein-free surfactants with open membranous structures that might facilitate spreading at the air-liquid interface of lungs.

  10. The interactions of multisensory integration with endogenous and exogenous attention

    PubMed Central

    Tang, Xiaoyu; Wu, Jinglong; Shen, Yong

    2016-01-01

    Stimuli from multiple sensory organs can be integrated into a coherent representation through multiple phases of multisensory processing; this phenomenon is called multisensory integration. Multisensory integration can interact with attention. Here, we propose a framework in which attention modulates multisensory processing in both endogenous (goal-driven) and exogenous (stimulus-driven) ways. Moreover, multisensory integration exerts not only bottom-up but also top-down control over attention. Specifically, we propose the following: (1) endogenous attentional selectivity acts on multiple levels of multisensory processing to determine the extent to which simultaneous stimuli from different modalities can be integrated; (2) integrated multisensory events exert top-down control on attentional capture via multisensory search templates that are stored in the brain; (3) integrated multisensory events can capture attention efficiently, even in quite complex circumstances, due to their increased salience compared to unimodal events and can thus improve search accuracy; and (4) within a multisensory object, endogenous attention can spread from one modality to another in an exogenous manner. PMID:26546734

  11. Exogenous sucrose supply changes sugar metabolism and reduces photosynthesis of sugarcane through the down-regulation of Rubisco abundance and activity.

    PubMed

    Lobo, Ana Karla Moreira; de Oliveira Martins, Marcio; Lima Neto, Milton Costa; Machado, Eduardo Caruso; Ribeiro, Rafael Vasconcelos; Silveira, Joaquim Albenisio Gomes

    2015-05-01

    Photosynthetic modulation by sugars has been known for many years, but the biochemical and molecular comprehension of this process is lacking. We studied how the exogenous sucrose supplied to leaves could affect sugar metabolism in leaf, sheath and stalk and inhibit photosynthesis in four-month old sugarcane plants. Exogenous sucrose 50mM sprayed on attached leaves strongly impaired the net CO2 assimilation (PN) and decreased the instantaneous carboxylation efficiency (PN/Ci), suggesting that the impairment in photosynthesis was caused by biochemical restrictions. The photosystem II activity was also affected by excess sucrose as indicated by the reduction in the apparent electron transport rate, effective quantum yield and increase in non-photochemical quenching. In leaf segments, sucrose accumulation was related to increases in the activities of soluble acid and neutral invertases, sucrose synthase and sucrose phosphate synthase, whereas the contents of fructose increased and glucose slightly decreased. Changes in the activities of sucrose hydrolyzing and synthesizing enzymes in leaf, sheath and stalk and sugar profile in intact plants were not enough to identify which sugar(s) or enzyme(s) were directly involved in photosynthesis modulation. However, exogenous sucrose was able to trigger down-regulation in the Rubisco abundance, activation state and enzymatic activity. Despite the fact that PN/Ci had been notably decreased by sucrose, in vitro activity and abundance of PEPCase did not change, suggesting an in vivo modulation of this enzyme. The data reveal that sucrose and/or other derivative sugars in leaves inhibited sugarcane photosynthesis by down-regulation of Rubisco synthesis and activity. Our data also suggest that sugar modulation was not exerted by a feedback mechanism induced by the accumulation of sugars in immature sugarcane stalk. Copyright © 2015. Published by Elsevier GmbH.

  12. Developments in Enzyme Technology.

    ERIC Educational Resources Information Center

    Chaplin, M. F.

    1984-01-01

    Enzyme technology has a well-established industrial base, with applications that have survived competition. The most prominent applications of enzymes in biotechnology are examined with an explanation of some theoretical background. Topics include extending an enzyme's useful life, partition and diffusion, industrial uses, and therapeutic uses.…

  13. Developments in Enzyme Technology.

    ERIC Educational Resources Information Center

    Chaplin, M. F.

    1984-01-01

    Enzyme technology has a well-established industrial base, with applications that have survived competition. The most prominent applications of enzymes in biotechnology are examined with an explanation of some theoretical background. Topics include extending an enzyme's useful life, partition and diffusion, industrial uses, and therapeutic uses.…

  14. Exogenous γ-aminobutyric acid (GABA) affects pollen tube growth via modulating putative Ca2+-permeable membrane channels and is coupled to negative regulation on glutamate decarboxylase

    PubMed Central

    Yu, Guang-Hui; Zou, Jie; Feng, Jing; Peng, Xiong-Bo; Wu, Ju-You; Wu, Ying-Liang; Palanivelu, Ravishankar; Sun, Meng-Xiang

    2014-01-01

    γ-Aminobutyric acid (GABA) is implicated in pollen tube growth, but the molecular and cellular mechanisms that it mediates are largely unknown. Here, it is shown that exogenous GABA modulates putative Ca2+-permeable channels on the plasma membranes of tobacco pollen grains and pollen tubes. Whole-cell voltage-clamp experiments and non-invasive micromeasurement technology (NMT) revealed that the influx of Ca2+ increases in pollen tubes in response to exogenous GABA. It is also demonstrated that glutamate decarboxylase (GAD), the rate-limiting enzyme of GABA biosynthesis, is involved in feedback controls of Ca2+-permeable channels to fluctuate intracellular GABA levels and thus modulate pollen tube growth. The findings suggest that GAD activity linked with Ca2+-permeable channels relays an extracellular GABA signal and integrates multiple signal pathways to modulate tobacco pollen tube growth. Thus, the data explain how GABA mediates the communication between the style and the growing pollen tubes. PMID:24799560

  15. Exogenous Application of Citric Acid Ameliorates the Adverse Effect of Heat Stress in Tall Fescue (Lolium arundinaceum)

    PubMed Central

    Hu, Longxing; Zhang, Zhifei; Xiang, Zuoxiang; Yang, Zhijian

    2016-01-01

    Citric acid may be involved in plant response to high temperature. The objective of this study was to investigate whether exogenous citric acid could improve heat tolerance in a cool-season turfgrass species, tall fescue (Lolium arundinaceum), and to determine the physiological mechanisms of citric acid effects on heat stress tolerance. The grasses were subjected to four citric acid levels (0, 0.2, 2, and 20 mM) and two temperature levels (25/20 and 35/30 ± 0.5°C, day/night) treatments in growth chambers. Heat stress increased an electrolyte leakage (EL) and malonaldehyde (MDA) content, while reduced plant growth, chlorophyll (Chl) content, photochemical efficiency (Fv/Fm), root activity and antioxidant enzyme activities (superoxide dismutase, SOD; catalase, CAT; peroxidase, POD). External citric acid alleviated the detrimental effects of heat stress on tall fescue, which was evidenced by decreased EL and MDA content, and improved plant growth under stress conditions. Additionally, the reduction in Chl content, Fv/Fm, SOD, POD, CAT and root activity were ameliorated in citric acid treated plants under heat stressed conditions. High temperature induced the expression of heat shock protein (HSP) genes, which exhibited greater expression levels after citric acid treatment under heat stress. These results suggest that exogenous citric acid application may alleviate growth and physiological damage caused by high temperature. In addition, the exogenously applied citric acid might be responsible for maintaining membrane stability, root activity, and activation of antioxidant response and HSP genes which could contribute to the protective roles of citric acid in tall fescue responses to heat stress. PMID:26925085

  16. Exogenous Melatonin Mitigates Photoinhibition by Accelerating Non-photochemical Quenching in Tomato Seedlings Exposed to Moderate Light during Chilling.

    PubMed

    Ding, Fei; Wang, Meiling; Liu, Bin; Zhang, Shuoxin

    2017-01-01

    Melatonin plays an important role in tolerance to multiple stresses in plants. Recent studies have shown that melatonin relieves photoinhibition in plants under cold stress; however, the mechanisms are not fully understood. Non-photochemical quenching (NPQ) is a key process thermally dissipating excess light energy that plants employ as a protective mechanism to prevent the over reduction of photosystem II. Here, we report the effects of exogenous melatonin on NPQ and mitigation of photoinhibition in tomato seedlings exposed to moderate light during chilling. In response to moderate light during chilling, the maximum quantum yield (Fv/Fm) and the effective photochemical efficiency (F'v/F'm) of PSII were both substantially reduced, showing severe photoinhibition in tomato seedlings, whereas exogenous application of melatonin effectively alleviated the photoinhibition. Further experiment showed that melatonin accelerated the induction of NPQ in response to moderate light and maintained higher level of NPQ upon longer exposure to light during chilling. Consistent with the increased NPQ was the elevated de-epoxidation state of xanthophyll pigments in melatonin-pretreated seedlings exposed to light during chilling. Enzyme activity assay showed that violaxanthin de-epoxidase (VDE), which catalyzes the de-epoxidation reaction in the xanthophyll cycle, was activated by light and the activity was further enhanced by application of melatonin. Further analysis revealed that melatonin induced the expression of VDE gene in tomato seedlings under moderate light and chilling conditions. Ascorbic acid is an essential cofactor of VDE and the level of it was found to be increased in melatonin-pretreated seedlings. Feeding tomato seedlings with dithiothreitol, an inhibitor of VDE, blocked the effects of melatonin on the de-epoxidation state of xanthophyll pigments and the induction of NPQ. Collectively, these results suggest that exogenous melatonin mitigates photoinhibition by

  17. Exogenous Melatonin Mitigates Photoinhibition by Accelerating Non-photochemical Quenching in Tomato Seedlings Exposed to Moderate Light during Chilling

    PubMed Central

    Ding, Fei; Wang, Meiling; Liu, Bin; Zhang, Shuoxin

    2017-01-01

    Melatonin plays an important role in tolerance to multiple stresses in plants. Recent studies have shown that melatonin relieves photoinhibition in plants under cold stress; however, the mechanisms are not fully understood. Non-photochemical quenching (NPQ) is a key process thermally dissipating excess light energy that plants employ as a protective mechanism to prevent the over reduction of photosystem II. Here, we report the effects of exogenous melatonin on NPQ and mitigation of photoinhibition in tomato seedlings exposed to moderate light during chilling. In response to moderate light during chilling, the maximum quantum yield (Fv/Fm) and the effective photochemical efficiency (F′v/F′m) of PSII were both substantially reduced, showing severe photoinhibition in tomato seedlings, whereas exogenous application of melatonin effectively alleviated the photoinhibition. Further experiment showed that melatonin accelerated the induction of NPQ in response to moderate light and maintained higher level of NPQ upon longer exposure to light during chilling. Consistent with the increased NPQ was the elevated de-epoxidation state of xanthophyll pigments in melatonin-pretreated seedlings exposed to light during chilling. Enzyme activity assay showed that violaxanthin de-epoxidase (VDE), which catalyzes the de-epoxidation reaction in the xanthophyll cycle, was activated by light and the activity was further enhanced by application of melatonin. Further analysis revealed that melatonin induced the expression of VDE gene in tomato seedlings under moderate light and chilling conditions. Ascorbic acid is an essential cofactor of VDE and the level of it was found to be increased in melatonin-pretreated seedlings. Feeding tomato seedlings with dithiothreitol, an inhibitor of VDE, blocked the effects of melatonin on the de-epoxidation state of xanthophyll pigments and the induction of NPQ. Collectively, these results suggest that exogenous melatonin mitigates photoinhibition by

  18. Attenuation of experimental autoimmune hepatitis by exogenous and endogenous cannabinoids: involvement of regulatory T cells.

    PubMed

    Hegde, Venkatesh L; Hegde, Shweta; Cravatt, Benjamin F; Hofseth, Lorne J; Nagarkatti, Mitzi; Nagarkatti, Prakash S

    2008-07-01

    Immune-mediated liver diseases including autoimmune and viral hepatitis are a major health problem worldwide. Natural cannabinoids such as Delta(9)-tetrahydrocannabinol (THC) effectively modulate immune cell function, and they have shown therapeutic potential in treating inflammatory diseases. We investigated the effects of THC in a murine model of concanavalin A (ConA)-induced hepatitis. Intraperitoneal administration of THC after ConA challenge inhibited hepatitis as shown by significant decrease in liver enzymes and reduced liver tissue injury. Furthermore, THC treatment resulted in significant suppression of crucial inflammatory cytokines in ConA-induced hepatitis. It is noteworthy that THC treatment in ConA-injected mice led to significant increase in absolute number of Forkhead helix transcription factor p3+ T regulatory cells in liver. We were surprised to find that select cannabinoid receptor (CB1 or CB2) agonists were not able to block hepatitis either independently or in combination. However, CB1/CB2 mixed agonists were able to efficiently attenuate hepatitis similar to THC. The modulatory effect of THC in ConA-induced hepatitis was reversed by both CB1 and CB2 antagonists. We also observed that endogenous cannabinoid anandamide was able to reduce hepatitis by suppressing cytokine levels. In addition, deficiency or inhibition of endocannabinoid hydrolyzing enzyme fatty acid amide hydrolase (FAAH), which leads to increased levels of endogenous cannabinoids, resulted in decreased liver injury upon ConA challenge. Our data demonstrate that targeting cannabinoid receptors using exogenous or endogenous cannabinoids and use of FAAH inhibitors may constitute novel therapeutic modalities to treat immune-mediated liver inflammation.

  19. Bile acids cause secretory phospholipase A2 activity enhancement, revertible by exogenous surfactant administration.

    PubMed

    De Luca, Daniele; Minucci, Angelo; Zecca, Enrico; Piastra, Marco; Pietrini, Domenico; Carnielli, Virgilio P; Zuppi, Cecilia; Tridente, Ascanio; Conti, Giorgio; Capoluongo, Ettore D

    2009-02-01

    Bile acids have been implicated in some forms of acute lung injury, including meconium aspiration and bile acid pneumonia in neonates, or aspiration related ARDS in adults. Secretory phospholipase A2 (sPLA2) is now known as a key enzyme in the lung injury pathways and is supposed to be responsible for surfactant dysfunction. Our aim was to investigate the interaction between bile acids and sPLA2 in an extracellular environment representing an in vitro model of aspiration. In vitro study using broncho-alveolar lavage (BAL) of 23 neonates/infants (<6 m) with healthy lungs. BAL supernatants were assayed for sPLA2 activity in basal condition and after addition of randomly assigned concentrations of bile acids (BA) or normal saline. Samples coming from neonates were then challenged with poractant-alfa up to a phospholipid concentration equal to that found in babies after the surfactant treatment for respiratory distress syndrome. sPLA2 activity was again measured, being corrected for serum/supernatant urea ratio and for confounding factors. High concentrations of BA (5 micromol/l) significantly increased (P = 0.012) sPLA2 activity, leading to increased surfactant catabolism. This finding was not observed with lower BA concentration and this is consistent with available literature data and may indicate an anionic activation of the enzyme by bile acids. Increased activity was significantly reverted by the addition of exogenous surfactant (P = 0.004) which was able to reduce sPLA2 activity almost to the baseline level. BA are likely to contribute to lung injury, causing surfactant inactivation through the increased sPLA2 activity. Other mechanisms cannot be excluded and require further studies to be clarified.

  20. Photosynthesis is improved by exogenous calcium in heat-stressed tobacco plants.

    PubMed

    Tan, Wei; Meng, Qing wei; Brestic, Marian; Olsovska, Katarina; Yang, Xinghong

    2011-11-15

    Effects of exogenous calcium chloride (CaCl(2)) (20 mM) on photosynthetic gas exchange, photosystem II photochemistry, and the activities of antioxidant enzymes in tobacco plants under high temperature stress (43°C for 2 h) were investigated. Heat stress resulted in a decrease in net photosynthetic rate (P(n)), stomatal conductance as well as the apparent quantum yield (AQY) and carboxylation efficiency (CE) of photosynthesis. Heat stress also caused a decrease of the maximal photochemical efficiency of primary photochemistry (F(v)/F(m)). On the other hand, CaCl(2) application improved P(n), AQY, and CE as well as F(v)/F(m) under high temperature stress. Heat stress reduced the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD), whereas the activities of these enzymes either decreased less or increased in plants pretreated with CaCl(2); glutathione reductase (GR) activity increased under high temperature, and it increased more in plants pretreated with CaCl(2). There was an obvious accumulation of H(2)O(2) and O(2)(-) under high temperature, but CaCl(2) application decreased the contents of H(2)O(2) and O(2)(-) under heat stress conditions. Heat stress induced the level of heat shock protein 70 (HSP70), while CaCl(2) pretreatment enhanced it. These results suggested that photosynthesis was improved by CaCl(2) application in heat-stressed plants and such an improvement was associated with an improvement in stomatal conductance and the thermostability of oxygen-evolving complex (OEC), which might be due to less accumulation of reactive oxygen species.

  1. Exogenous subclinical hyperthyroidism: effect on the cardiovascular system.

    PubMed

    Federico Moreno, Karol; Paoli de Valeri, Mariela; Odreman, Rodolfo; Núñez, Tulio; Arata-Bellabarba, Gabriela

    2008-06-01

    To evaluate the effects of exogenous subclinical hyperthyroidism on left ventricular structure and function. Twenty-three patients of both sexes, aged 27 to 70 years, with a diagnosis of exogenous subclinical hyperthyroidism (serum thyroid-stimulating hormone [TSH] ≤ 0.4mU/ml and normal free thyroxine [FT4]) were evaluated. The patients had been taking levothyroxine in suppressive doses for an average of 6.7 years (1 to 35 years). Twenty euthyroid individuals matched for age, sex and body mass index were selected as controls. A medical history was obtained and symptoms of thyrotoxicosis were quantified in all subjects. To evaluate left ventricular structure and function, as well as atrial conduction time, a two-dimensional echocardiogram and pulsed echo and tissue echo Doppler with electrocardiography monitoring were performed. The index of hemodynamic compensation of the left ventricular mass was calculated. Hyperthyroid symptom scores were significantly higher in patients than in controls (p=0.0001). A positive correlation was found between hyperthyroidism scores and FT4 (p=0.005) and ejection fraction (p=0.04) and a negative correlation was found with TSH levels (p=0.03). End-diastolic volume, stroke volume, cardiac output and stroke work were significantly higher in patients with SH (p=0.04, p=0.02, p=0.05 and p=0.01, respectively). A positive correlation was found between fractional shortening and FT4 level (p=0.022) and levothyroxine dose (p=0.016) and between stroke work and FT4 level (p=0.034). Left ventricular mass, diastolic function and atrial conduction time were similar in patients and controls. Our study suggests that patients with exogenous subclinical hyperthyroidism have hemodynamic changes resulting from adaptation to the biological effects of levothyroxine on the cardiovascular system. However, structural changes are not produced. Copyright © 2008 Sociedad Española de Endocrinología y Nutrición. Published by Elsevier Espana. All rights

  2. Catabolism of exogenously supplied thymidine to thymine and dihydrothymine by platelets in human peripheral blood

    SciTech Connect

    Pero, R.W.; Johnson, D.; Olsson, A.

    1984-11-01

    The interference of platelets with the estimation of unscheduled DNA synthesis in human peripheral mononuclear leukocytes following genotoxic exposure was studied. A 96% reduction in the unscheduled DNA synthesis value was achieved by incubating (/sup 3/H)thymidine with platelet-rich plasma for 5 hr at 37 degrees. Using radioactive thymine-containing compounds, together with quantitative analyses based on thin-layer and ion-exchange chromatographies, we have shown that thymidine was converted to thymine which, in turn, was converted to dihydrothymine in platelet-rich plasma. The enzymes responsible were separated from platelet lysates by gel filtration and were identified as thymidine phosphorylase and dihydrothymine dehydrogenase. The phosphorylase reversibly catalyzed the formation of thymine from thymidine and converted bromodeoxyuridine to bromouracil. The dehydrogenase reversibly catalyzed the interconversion of thymine and dihydrothymine in a reaction dependent on NADP(H), and it was inhibited by diazouracil and by thymine. Nearly all the thymidine-catabolizing activity found in whole blood samples supplied exogenously with thymidine was accounted for by the platelets. Since most genetic toxicological tests that use blood samples do not involve removing platelets from the blood cell cultures, then it is concluded that precautions should be taken in the future to determine the influence of platelets on these test systems. This is particularly true for methods dependent on thymidine pulses such as unscheduled DNA synthesis, or those dependent on bromodeoxyuridine, such as sister chromatid exchanges, since this nucleoside is also a substrate for thymidine phosphorylase.

  3. Exogenous Melatonin Confers Salt Stress Tolerance to Watermelon by Improving Photosynthesis and Redox Homeostasis

    PubMed Central

    Li, Hao; Chang, Jingjing; Chen, Hejie; Wang, Zhongyuan; Gu, Xiurong; Wei, Chunhua; Zhang, Yong; Ma, Jianxiang; Yang, Jianqiang; Zhang, Xian

    2017-01-01

    Melatonin, a pleiotropic signal molecule, has been shown to play important roles in the regulation of plant growth, development, and responses to environmental stresses. Since a few species have been investigated to unveil the effect of exogenous melatonin on salt stress, the underlying mechanism of melatonin-mediated salt stress tolerance in other plant species still remains largely unknown. In this study, the effects of melatonin on leaf photosynthesis and redox homeostasis in watermelon were examined under salt stress (300 mM NaCl) along with different doses of melatonin (50, 150, and 500 μM) pretreatment. NaCl stress inhibited photosynthesis and increased accumulation of reactive oxygen species and membrane damage in leaves of watermelon seedlings. However, pretreatment with melatonin on roots alleviated NaCl-induced decrease in photosynthetic rate and oxidative stress in a dose-dependent manner. The protection of photosynthesis by melatonin was closely associated with the inhibition of stomatal closure and improved light energy absorption and electron transport in photosystem II, while the reduction of oxidative stress by melatonin was attributed to the improved redox homeostasis coupled with the enhanced activities of antioxidant enzymes. This study unraveled crucial role of melatonin in salt stress mitigation and thus can be implicated in the management of salinity in watermelon cultivation. PMID:28298921

  4. Cold stratification and exogenous nitrates entail similar functional proteome adjustments during Arabidopsis seed dormancy release.

    PubMed

    Arc, Erwann; Chibani, Kamel; Grappin, Philippe; Jullien, Marc; Godin, Béatrice; Cueff, Gwendal; Valot, Benoit; Balliau, Thierry; Job, Dominique; Rajjou, Loïc

    2012-11-02

    Despite having very similar initial pools of stored mRNAs and proteins in the dry state, mature Arabidopsis seeds can either proceed toward radicle protrusion or stay in a dormant state upon imbibition. Dormancy breaking, a prerequisite to germination completion, can be induced by different treatments though the underlying mechanisms remain elusive. Thus, we investigated the consequence of such treatments on the seed proteome. Two unrelated dormancy-releasing treatments were applied to dormant seeds, namely, cold stratification and exogenous nitrates, in combination with differential proteomic tools to highlight the specificities of the imbibed dormant state. The results reveal that both treatments lead to highly similar proteome adjustments. In the imbibed dormant state, enzymes involved in reserve mobilization are less accumulated and it appears that several energetically costly processes associated to seed germination and preparation for subsequent seedling establishment are repressed. Our data suggest that dormancy maintenance is associated to an abscisic-acid-dependent recapitulation of the late maturation program resulting in a higher potential to cope with environmental stresses. The comparison of the present results with previously published -omic data sets reinforces and extends the assumption that post-transcriptional, translational, and post-translational regulations are determinant for seed germination.

  5. Homologous recombination of exogenous DNA with the Sulfolobus acidocaldarius genome: properties and uses.

    PubMed

    Kurosawa, Norio; Grogan, Dennis W

    2005-12-01

    In order to quantify recombination between exogenous DNA and the Sulfolobus acidocaldarius chromosome, we electroporated pyrE (uracil-auxtotrophic) recipient strains with functional pyrE sequences and counted Pyr+ transformants by direct plating. Certain culture and post-electroporation conditions increased the yield of Pyr+ recombinants from non-replicating pyrE plasmid, whereas cognate methylation of SuaI restriction sites in the plasmid decreased it. Recombination of linear DNAs with the S. acidocaldarius genome was proportional to the length of a limiting overlap, but even synthetic oligonucleotides produced reasonable numbers of recombinants with appropriate recipient strains. To investigate uses of this latter property, we electroporated an 18-bp pyrE deletion mutant with mixtures of synthetic oligonucleotides altering glycine-55 of the orotate phosphoribosyl transferase encoded by pyrE. Pyr+ transformants were recovered in which this codon was converted to each of the alternatives encoded by the oligonucleotide mixtures, thereby identifying five amino acid substitutions tolerated at this position of the thermostable enzyme.

  6. Exogenous salicylic acid alleviates the toxicity of chlorpyrifos in wheat plants (Triticum aestivum).

    PubMed

    Wang, Caixia; Zhang, Qingming

    2017-03-01

    The role of exogenous salicylic acid (SA) in protecting wheat plants (Triticum aestivum) from contamination by the insecticide chlorpyrifos was investigated in this study. The wheat plants were grown in soils with different concentrations (5, 10, 20, and 40mgkg(-1)) of chlorpyrifos. When the third leaf emerged, the wheat leaves were sprayed with 1, 2, 4, 8, and 16mgL(-1) of SA once a day for 6 days. The results showed that wheat exposed to higher concentrations of chlorpyrifos (≥20mgkg(-1)) caused declines in growth and chlorophyll content and altered the activities of a series of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX). Interestingly, treatments with different concentrations of SA mitigated the stress generated by chlorpyrifos and improved the measured parameters to varying degrees. Furthermore, a reverse transcription and quantitative PCR experiment revealed that the activities of SOD and CAT can be regulated by their target gene in wheat when treated with SA. We also found that SA is able to block the accumulation of chlorpyrifos in wheat. However, the effect of SA was related to its concentration. In this study, the application of 2mgL(-1) of SA had the greatest ameliorating effect on chlorpyrifos toxicity in wheat plants.

  7. The mitigation effects of exogenous melatonin on salinity-induced stress in Malus hupehensis.

    PubMed

    Li, Chao; Wang, Ping; Wei, Zhiwei; Liang, Dong; Liu, Changhai; Yin, Lihua; Jia, Dongfeng; Fu, Mingyang; Ma, Fengwang

    2012-10-01

    As an indoleamine molecule, melatonin mediates many physiological processes in plants. We investigated its role in regulating growth, ion homeostasis, and the response to oxidative stress in Malus hupehensis Rehd. under high-salinity conditions. Stressed plants had reduced growth and a marked decline in their net photosynthetic rates and chlorophyll contents. However, pretreatment with 0.1μm melatonin significantly alleviated this growth inhibition and enabled plants to maintain an improved photosynthetic capacity. The addition of melatonin also lessened the amount of oxidative damage brought on by salinity, perhaps by directly scavenging H(2) O(2) or enhancing the activities of antioxidative enzymes such as ascorbate peroxidase, catalase, and peroxidase. We also investigated whether melatonin might control the expression of ion-channel genes under salinity. Here, MdNHX1 and MdAKT1 were greatly up-regulated in the leaves, which possibly contributed to the maintenance of ion homeostasis and, thus, improved salinity resistance in plants exposed to exogenous melatonin.

  8. Improvement in cadmium tolerance of edible rape (Brassica rapa L.) with exogenous application of chitooligosaccharide.

    PubMed

    Zong, Haiying; Li, Kecheng; Liu, Song; Song, Lin; Xing, Ronge; Chen, Xiaolin; Li, Pengcheng

    2017-08-01

    Cadmium (Cd) is one of the most toxic heavy metals, which is readily taken up by plant roots and has deleterious effects on crop yield and quality. The study investigated the potential cross-protection roles of chitooligosaccharide (COS) in alleviating Cd toxicity in edible rape (Brassica rapa L.) under greenhouse conditions. The results demonstrated that spraying COS onto the leaves of edible rape could promote the plant growth and leaf chlorophyll contents, decrease the malondialdehyde (MDA) level in leaves as well as the Cd(2+) concentration in shoots and roots of edible rape under Cd stress. Moreover, exogenous COS could obviously enhance the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX) in edible rape leaves under Cd-toxicity. The alleviation effect of COS on Cd stress was concentration-dependent and COS of 50-100 mg L(-1) showed the best activity. Subcellular distribution experiments further revealed that COS of 50 mg L(-1) decreased the proportion of Cd in the organelle fraction of leaves by 40.1% while increased the proportion of Cd in the soluble fraction by 13.2%. These results indicated that COS had a potential to enhance plant resistance to Cd through promoting antioxidant enzyme activities and altering Cd subcellular distribution. Copyright © 2017. Published by Elsevier Ltd.

  9. Exogenous Melatonin Confers Salt Stress Tolerance to Watermelon by Improving Photosynthesis and Redox Homeostasis.

    PubMed

    Li, Hao; Chang, Jingjing; Chen, Hejie; Wang, Zhongyuan; Gu, Xiurong; Wei, Chunhua; Zhang, Yong; Ma, Jianxiang; Yang, Jianqiang; Zhang, Xian

    2017-01-01

    Melatonin, a pleiotropic signal molecule, has been shown to play important roles in the regulation of plant growth, development, and responses to environmental stresses. Since a few species have been investigated to unveil the effect of exogenous melatonin on salt stress, the underlying mechanism of melatonin-mediated salt stress tolerance in other plant species still remains largely unknown. In this study, the effects of melatonin on leaf photosynthesis and redox homeostasis in watermelon were examined under salt stress (300 mM NaCl) along with different doses of melatonin (50, 150, and 500 μM) pretreatment. NaCl stress inhibited photosynthesis and increased accumulation of reactive oxygen species and membrane damage in leaves of watermelon seedlings. However, pretreatment with melatonin on roots alleviated NaCl-induced decrease in photosynthetic rate and oxidative stress in a dose-dependent manner. The protection of photosynthesis by melatonin was closely associated with the inhibition of stomatal closure and improved light energy absorption and electron transport in photosystem II, while the reduction of oxidative stress by melatonin was attributed to the improved redox homeostasis coupled with the enhanced activities of antioxidant enzymes. This study unraveled crucial role of melatonin in salt stress mitigation and thus can be implicated in the management of salinity in watermelon cultivation.

  10. Exogenous methyl jasmonate regulates cytokinin content by modulating cytokinin oxidase activity in wheat seedlings under salinity.

    PubMed

    Avalbaev, Azamat; Yuldashev, Ruslan; Fedorova, Kristina; Somov, Kirill; Vysotskaya, Lidiya; Allagulova, Chulpan; Shakirova, Farida

    2016-02-01

    The treatment of 4-days-old wheat seedlings with methyl jasmonate (MeJA) in concentration optimal for their growth (0.1 μM) resulted in a rapid transient almost two-fold increase in the level of cytokinins (CKs). MeJA-induced accumulation of CKs was due to inhibition of both cytokinin oxidase (CKX) (cytokinin oxidase/dehydrogenase, EC 1.5.99.12) gene expression and activity of this enzyme. Pretreatment of wheat seedlings with MeJA decreased the growth-retarding effect of sodium chloride salinity and accelerated growth recovery after withdrawal of NaCl from the incubation medium. We speculate that this protective effect of the hormone might be due to MeJA's ability to prevent the salinity-induced decline in CK concentration that was caused by inhibition of gene expression and activity of CKX in wheat seedlings. The data might indicate an important role for endogenous cytokinins in the implementation of growth-promoting and protective effects of exogenous MeJA application on wheat plants.

  11. The average enzyme principle

    PubMed Central

    Reznik, Ed; Chaudhary, Osman; Segrè, Daniel

    2013-01-01

    The Michaelis-Menten equation for an irreversible enzymatic reaction depends linearly on the enzyme concentration. Even if the enzyme concentration changes in time, this linearity implies that the amount of substrate depleted during a given time interval depends only on the average enzyme concentration. Here, we use a time re-scaling approach to generalize this result to a broad category of multi-reaction systems, whose constituent enzymes have the same dependence on time, e.g. they belong to the same regulon. This “average enzyme principle” provides a natural methodology for jointly studying metabolism and its regulation. PMID:23892076

  12. Aromatase and cyclooxygenases: enzymes in breast cancer.

    PubMed

    Brueggemeier, Robert W; Richards, Jeanette A; Petrel, Trevor A

    2003-09-01

    Aromatase (estrogen synthase) is the cytochrome P450 enzyme complex that converts C19 androgens to C18 estrogens. Aromatase activity has been demonstrated in breast tissue in vitro, and expression of aromatase is highest in or near breast tumor sites. Thus, local regulation of aromatase by both endogenous factors as well as exogenous medicinal agents will influence the levels of estrogen available for breast cancer growth. The prostaglandin PGE2 increases intracellular cAMP levels and stimulates estrogen biosynthesis, and previous studies in our laboratories have shown a strong linear association between aromatase (CYP19) expression and expression of the cyclooxygenases (COX-1 and COX-2) in breast cancer specimens. To further investigate the pathways regulating COX and CYP19 gene expression, studies were performed in normal breast stromal cells, in breast cancer cells from patients, and in breast cancer cell lines using selective pharmacological agents. Enhanced COX enzyme levels results in increased production of prostaglandins, such as PGE2. This prostaglandin increased aromatase activity in breast stromal cells, and studies with selective agonists and antagonists showed that this regulation of signaling pathways occurs through the EP1 and EP2 receptor subtypes. COX-2 gene expression was enhanced in breast cancer cell lines by ligands for the various peroxisome proliferator-activated receptors (PPARs), and differential regulation was observed between hormone-dependent and -independent breast cancer cells. Thus, the regulation of both enzymes in breast cancer involves complex paracrine interactions, resulting in significant consequences on the pathogenesis of breast cancer.

  13. The phytotoxic effect of exogenous ethanol on Euphorbia heterophylla L.

    PubMed

    Kern, Kátia Aparecida; Pergo, Erica Marusa; Kagami, Fernanda Lima; Arraes, Luis Saraiva; Sert, Maria Aparecida; Ishii-Iwamoto, Emy Luiza

    2009-01-01

    This study investigated the effects of exogenously applied ethanol on Euphorbia heterophylla L., a troublesome weed in field and plantation crops. Ethanol at concentrations ranging from 0.25 to 1.5% caused a dose-dependent inhibition of germination and growth of E. heterophylla. Measurements of respiratory activity and alcohol dehydrogenase (E.C. 1.1.1.1) activity during seed imbibition and initial seedling growth revealed that ethanol induces a prolongation of hypoxic conditions in the growing tissues. In isolated mitochondria, ethanol inhibited the respiration coupled to ADP phosphorylation, an action that probably contributed to modifications observed in the respiratory activity of embryos. A comparison of the effects of methanol, ethanol, propanol and acetaldehyde on germination and growth of E. heterophylla indicates that alcohol dehydrogenase activity is required for the observed effects, with the conversion of ethanol to acetaldehyde playing a role in the ethanol-induced injuries.

  14. Effect of exogenous erythritol on growth and survival of Brucella.

    PubMed

    Jain, Neeta; Boyle, Stephen M; Sriranganathan, Nammalwar

    2012-12-07

    Erythritol has been considered as an important factor for the pathogenesis of Brucella abortus 2308 and its ability to cause abortion in ruminants. There is a lack of laboratory models to study the Brucella-erythritol relationship, as commonly used murine models do not have erythritol. We tested the effect of exogenous erythritol on the growth of Brucella in iron minimal medium (IMM), in infected macrophage culture and in infected mice to determine if these models can be used to study the relationship between Brucella and erythritol. An effect of erythritol on Brucella growth was only seen in IMM. There appear to be no effect of erythritol on Brucella growth in macrophage cell cultures or in mice. This shows that administration of erythritol to the mice or macrophages cannot mimic the environment in ruminants during pregnancy and thus cannot be used as models to understand the effect of erythritol on Brucella pathogenesis. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Subdividing tinnitus into bruits and endogenous, exogenous, and other forms.

    PubMed

    Claussen, Claus F

    2005-01-01

    Tinnitus is an important complaint or disease or a combination, especially within our aging population. Neurootologists clinically deal with many different disorders of the human cranial senses, of which tinnitus is a very frequent type. With respect to neurootological clinical work, we delineate at least three groups of tinnitus. In bruits, patients complain of noise within the head (e.g., bubbling, hissing, pulsating); the bruit can be recorded as a physically existing sound in the human skull and is heard by patients. Endogenous tinnitus can be treated by external masking to suppress noise within the ears, whereas in exogenous tinnitus, patients seek to avoid any outside noise or sounds; they report that tinnitus decreases as soon as they go, for instance, into the cellar of a house or other soundproof place.

  16. Exogenous melatonin affects photosynthesis in characeae Chara australis.

    PubMed

    Lazár, Dušan; Murch, Susan J; Beilby, Mary J; Al Khazaaly, Sabah

    2013-03-01

    Melatonin was found in the fresh water characeae Chara australis. The concentrations (~4 μg/g of tissue) were similar in photosynthesizing cells, independent of their position on the plant and rhizoids (roots) without chloroplasts. Exogenous melatonin, added at 10 μM to the artificial pond water, increased quantum yield of photochemistry of photosystem II by 34%. The increased efficiency appears to be due to the amount of open reaction centers of photosystem II, rather than increased efficiency of each reaction center. More open reaction centers reflect better functionality of all photosynthetic transport chain constituents. We suggest that melatonin protection against reactive oxygen species covers not only chlorophyll, but also photosynthetic proteins in general.

  17. Exogenous gene integration mediated by genome editing technologies in zebrafish.

    PubMed

    Morita, Hitoshi; Taimatsu, Kiyohito; Yanagi, Kanoko; Kawahara, Atsuo

    2017-03-08

    Genome editing technologies, such as transcription activator-like effector nuclease (TALEN) and the clustered regularly interspaced short palindromic repeat (CRISPR)/ CRISPR-associated protein (Cas) systems, can induce DNA double-strand breaks (DSBs) at the targeted genomic locus, leading to frameshift-mediated gene disruption in the process of DSB repair. Recently, the technology-induced DSBs followed by DSB repairs are applied to integrate exogenous genes into the targeted genomic locus in various model organisms. In addition to a conventional knock-in technology mediated by homology-directed repair (HDR), novel knock-in technologies using refined donor vectors have also been developed with the genome editing technologies based on other DSB repair mechanisms, including non-homologous end joining (NHEJ) and microhomology-mediated end joining (MMEJ). Therefore, the improved knock-in technologies would contribute to freely modify the genome of model organisms.

  18. Exogenous melatonin affects photosynthesis in characeae Chara australis

    PubMed Central

    Lazár, Dušan; Murch, Susan J.; Beilby, Mary J.; Al Khazaaly, Sabah

    2013-01-01

    Melatonin was found in the fresh water characeae Chara australis. The concentrations (~4 μg/g of tissue) were similar in photosynthesizing cells, independent of their position on the plant and rhizoids (roots) without chloroplasts. Exogenous melatonin, added at 10 μM to the artificial pond water, increased quantum yield of photochemistry of photosystem II by 34%. The increased efficiency appears to be due to the amount of open reaction centers of photosystem II, rather than increased efficiency of each reaction center. More open reaction centers reflect better functionality of all photosynthetic transport chain constituents. We suggest that melatonin protection against reactive oxygen species covers not only chlorophyll, but also photosynthetic proteins in general. PMID:23299331

  19. [Influence of exogenous substance on germination of Platycodon grandiflorum seeds].

    PubMed

    Zhao, Rong-mei; Liu, Li; Guo, Qiao-sheng

    2006-06-01

    To study of exogenous substances on the germination rate of Platycodon grandiflorum and offer the basis for the standardized culture of P. grandiflorum. At 25 degrees C, under darkness and lightness, do pretreatmeats on seeds by using GA3, H2O2, KMnO4, PEG at different concentrations. The results indicated that the pretreatments with GA3 at a concentrating of 50-250 mg x L(-1) and 1%-2% of H2O2 could increase germination of P. grandiflorum seed at a certain degree. Contrariwise 0.1%-0.5% of KMnO4 and 15%-35% of PEG inhibited the germination. Pretreatment with 50-250 mg x L(-1)GA3 and H2O2 at a low cencontration could increase the seed germination of P. grandiflorum.

  20. Transient expression of exogenous gus gene in Porphyra yezoensis (Rhodophyta)

    NASA Astrophysics Data System (ADS)

    Kuang, Mei; Wang, Su-Juan; Li, Yao; Shen, Da-Leng; Zeng, Cheng-Kui

    1998-03-01

    Electroporation, PEC, PEG plus electroporation and Biolistics methods were tested in gene transformation of P. yezoensis. The exogenous gus was from plasmid of pBI121 and pCAMBIA1301, both contain the CaMV35S promoter. The receptors included the protoplasts, tissues and free-living conchocelis filaments of P. yezoensis. Several factors, for example, the voltage, capacitance and bivalent cations, etc., were studied. Results show that these four methods are all efficient for gene transformation in P. yezoensis; and that PEG is the best one, with transformation efficiency of up to 4×10-5. GUS activity was detected 26 days after transformation by using PEG method.

  1. Profiling the orphan enzymes.

    PubMed

    Sorokina, Maria; Stam, Mark; Médigue, Claudine; Lespinet, Olivier; Vallenet, David

    2014-06-06

    The emergence of Next Generation Sequencing generates an incredible amount of sequence and great potential for new enzyme discovery. Despite this huge amount of data and the profusion of bioinformatic methods for function prediction, a large part of known enzyme activities is still lacking an associated protein sequence. These particular activities are called "orphan enzymes". The present review proposes an update of previous surveys on orphan enzymes by mining the current content of public databases. While the percentage of orphan enzyme activities has decreased from 38% to 22% in ten years, there are still more than 1,000 orphans among the 5,000 entries of the Enzyme Commission (EC) classification. Taking into account all the reactions present in metabolic databases, this proportion dramatically increases to reach nearly 50% of orphans and many of them are not associated to a known pathway. We extended our survey to "local orphan enzymes" that are activities which have no representative sequence in a given clade, but have at least one in organisms belonging to other clades. We observe an important bias in Archaea and find that in general more than 30% of the EC activities have incomplete sequence information in at least one superkingdom. To estimate if candidate proteins for local orphans could be retrieved by homology search, we applied a simple strategy based on the PRIAM software and noticed that candidates may be proposed for an important fraction of local orphan enzymes. Finally, by studying relation between protein domains and catalyzed activities, it appears that newly discovered enzymes are mostly associated with already known enzyme domains. Thus, the exploration of the promiscuity and the multifunctional aspect of known enzyme families may solve part of the orphan enzyme issue. We conclude this review with a presentation of recent initiatives in finding proteins for orphan enzymes and in extending the enzyme world by the discovery of new activities.

  2. Impaired ovarian response to exogenous gonadotropins in female rat offspring born to mothers perinatally exposed to Bisphenol A.

    PubMed

    Santamaría, C G; Rodriguez, H A; Abud, J E; Rivera, O E; Muñoz-de-Toro, M; Luque, E H

    2017-06-23

    The ovary is sensitive to disruption by the environmental estrogen Bisphenol A (BPA). Our aim was to investigate whether perinatal exposure to BPA (50μg/kgday), orally administered, affects ovarian response to exogenous gonadotrophins (PMSG or PMSG+hCG) in prepubertal female offspring. An altered response to gonadotrophins was observed in BPA-exposed rats. Increased proportion of antral follicles, altered levels of ovarian steroidogenic enzymes, gonadotropin receptors, AR and ERβ were observed in PMSG group. Besides that, in response to PMSG+hCG, a persistent high Fshr mRNA expression and a decreased number of follicles with high expression of PR before ovulation were observed. After ovulation, there was an increase in antral atretic follicles, reduced Lhcgr mRNA expression and high serum levels of E2. Therefore, an early exposure to a low dose of BPA during perinatal period induces ovarian changes leading to an altered response to exogenous gonadotropin treatment later in life. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Exogenous application of hydrogen sulfide donor sodium hydrosulfide enhanced multiple abiotic stress tolerance in bermudagrass (Cynodon dactylon (L). Pers.).

    PubMed

    Shi, Haitao; Ye, Tiantian; Chan, Zhulong

    2013-10-01

    As a gaseous molecule, hydrogen sulfide (H2S) has been recently found to be involved in plant responses to multiple abiotic stress. In this study, salt (150 and 300 mM NaCl), osmotic (15% and 30% PEG6000) and cold (4 °C) stress treatments induced accumulation of endogenous H2S level, indicating that H2S might play a role in bermudagrass responses to salt, osmotic and cold stresses. Exogenous application of H2S donor (sodium hydrosulfide, NaHS) conferred improved salt, osmotic and freezing stress tolerances in bermudagrass, which were evidenced by decreased electrolyte leakage and increased survival rate under stress conditions. Additionally, NaHS treatment alleviated the reactive oxygen species (ROS) burst and cell damage induced by abiotic stress, via modulating metabolisms of several antioxidant enzymes [catalase (CAT), peroxidase (POD) and GR (glutathione reductase)] and non-enzymatic glutathione antioxidant pool and redox state. Moreover, exogenous NaHS treatment led to accumulation of osmolytes (proline, sucrose and soluble total sugars) in stressed bermudagrass plants. Taken together, all these data indicated the protective roles of H2S in bermudagrass responses to salt, osmotic and freezing stresses, via activation of the antioxidant response and osmolyte accumulation. These findings might be applicable to grass and crop engineering to improve abiotic stress tolerance.

  4. A trypsin-sensitive protein is required for utilization of exogenous cholesterol for pregnenolone synthesis by placental mitochondria.

    PubMed

    Espinosa-García, M T; Strauss, J F; Martínez, F

    2000-09-01

    The utilization of cholesterol for steroid hormone synthesis by human placental mitochondria is poorly understood. The human placenta does not express the steroidogenic acute regulator protein, which is critical for cholesterol delivery to the cholesterol side chain cleavage system in adrenal and gonadal mitochondria. We explored the mechanism underlying cholesterol transport in human placental mitochondria by measuring its transformation into pregnenolone. Mitochondria of syncytiotrophoblast from human term placenta were isolated by centrifugation through a sucrose gradient. The synthesis of pregnenolone in the presence of exogenous cholesterol was increased two-fold in syncytiotrophoblast mitochondria. Treatment of mitochondria with trypsin prevented the increase in the synthesis of pregnenolone in the presence of exogenous cholesterol. However, when 22-OH cholesterol, a substrate that readily crosses membranes, was added, the trypsin-treated mitochondria synthesized increased amounts of pregnenolone. The trypsin-treated mitochondria were intact, since oxygen consumption, succinate dehydrogenase and the adenine nucleotide translocase activities were not significantly different from in untreated mitochondria. However, activity of NADH cytochrome c oxidoreductase, an outer mitochondrial membrane enzyme, was reduced in the trypsin-treated mitochondria, reflecting the selective degradation of proteins. In addition, SDS-PAGE analysis revealed the loss of a prominent 34 kDa band which proved to be a novel porin-like protein that binds to cholesterol. These results support our previous assumption that human placental mitochondria employ a novel protein(s)-mediated the mechanism to take up cholesterol for steroidogenesis. Copyright 2000 Harcourt Publishers Ltd.

  5. Exogenous methyl jasmonate induces volatile emissions in cotton plants.

    PubMed

    Rodriguez-Saona, C; Crafts-Brandner, S J; Paré, P W; Henneberry, T J

    2001-04-01

    We investigated the effect of exogenous methyl jasmonate (MeJA) on the emission of herbivore-induced volatiles; these volatile chemicals can signal natural enemies of the herbivore to the damaged plant. Exogenous treatment of cotton cv. Deltapine 5415 plants with MeJA induced the emission of the same volatile compounds as observed for herbivore-damaged plants. Cotton plants treated with MeJA emitted elevated levels of the terpenes (E)-beta-ocimene, linalool, (3E)-4,8-dimethyl-1,3,7-nonatriene, (E,E)-alpha-farnesene, (E)-beta-farnesene, and (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene compared to untreated controls. Other induced components included (Z)-3-hexenyl acetate, methyl salicylate, and indole. Methyl jasmonate treatment did not cause the release of any of the stored terpenes such as alpha-pinene, beta-pinene, alpha-humulene, and (E)-beta-caryophyllene. In contrast, these compounds were emitted in relatively large amounts from cotton due to physical disruption of glands by the herbivores. The timing of volatile release from plants treated with MeJA or herbivores followed a diurnal pattern, with maximal volatile release during the middle of the photoperiod. Similar to herbivore-treated plants, MeJA treatment led to the systemic induction of (Z)-3-hexenyl acetate, (E)-beta-ocimene, linalool, (3E)-4,8-dimethyl-1,3,7-nonatriene, (E,E)-alpha-farnesene, (E)-beta-farnesene, and (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene. Our results indicate that treatment of cotton with MeJA can directly and systemically induce the emission of volatiles that may serve as odor cues in the host-search behavior of natural enemies.

  6. Evaluation of photosynthetic electrons derivation by exogenous redox mediators.

    PubMed

    Longatte, Guillaume; Fu, Han-Yi; Buriez, Olivier; Labbé, Eric; Wollman, Francis-André; Amatore, Christian; Rappaport, Fabrice; Guille-Collignon, Manon; Lemaître, Frédéric

    2015-10-01

    Oxygenic photosynthesis is the complex process that occurs in plants or algae by which the energy from the sun is converted into an electrochemical potential that drives the assimilation of carbon dioxide and the synthesis of carbohydrates. Quinones belong to a family of species commonly found in key processes of the Living, like photosynthesis or respiration, in which they act as electron transporters. This makes this class of molecules a popular candidate for biofuel cell and bioenergy applications insofar as they can be used as cargo to ship electrons to an electrode immersed in the cellular suspension. Nevertheless, such electron carriers are mostly selected empirically. This is why we report on a method involving fluorescence measurements to estimate the ability of seven different quinones to accept photosynthetic electrons downstream of photosystem II, the first protein complex in the light-dependent reactions of oxygenic photosynthesis. To this aim we use a mutant of Chlamydomonas reinhardtii, a unicellular green alga, impaired in electron downstream of photosystem II and assess the ability of quinones to restore electron flow by fluorescence. In this work, we defined and extracted a "derivation parameter" D that indicates the derivation efficiency of the exogenous quinones investigated. D then allows electing 2,6-dichlorobenzoquinone, 2,5-dichlorobenzoquinone and p-phenylbenzoquinone as good candidates. More particularly, our investigations suggested that other key parameters like the partition of quinones between different cellular compartments and their propensity to saturate these various compartments should also be taken into account in the process of selecting exogenous quinones for the purpose of deriving photoelectrons from intact algae.

  7. Impact of Exogenous Galectin-9 on Human T Cells

    PubMed Central

    Lhuillier, Claire; Barjon, Clément; Niki, Toshiro; Gelin, Aurore; Praz, Françoise; Morales, Olivier; Souquere, Sylvie; Hirashima, Mitsuomi; Wei, Ming; Dellis, Olivier; Busson, Pierre

    2015-01-01

    Galectin-9 (gal-9) is a multifunctional β-galactoside-binding lectin, frequently released in the extracellular medium, where it acts as a pleiotropic immune modulator. Despite its overall immunosuppressive effects, a recent study has reported bimodal action of gal-9 on human resting blood T cells with apoptosis occurring in the majority of them, followed by a wave of activation and expansion of Th1 cells in the surviving population. Our knowledge of the signaling events triggered by exogenous gal-9 in T cells remains limited. One of these events is cytosolic calcium (Ca2+) release reported in some murine and human T cells. The aim of this study was to investigate the contribution of Ca2+ mobilization to apoptotic and nonapoptotic effects of exogenous gal-9 in human T cells. We found that the T cell receptor (TCR)-CD3 complex and the Lck kinase were required for Ca2+ mobilization but not for apoptosis induction in Jurkat cells. These data were confirmed in human CD4+ T cells from peripheral blood as follows: a specific Lck chemical inhibitor abrogated Ca2+ mobilization but not apoptosis induction. Moreover, Lck activity was also required for the production of Th1-type cytokines, i.e. interleukin-2 and interferon-γ, which resulted from gal-9 stimulation in peripheral CD4+ T cells. These findings indicate that gal-9 acts on T cells by two distinct pathways as follows: one mimicking antigen-specific activation of the TCR with a mandatory contribution of proximal elements of the TCR complex, especially Lck, and another resulting in apoptosis that is independent of this complex. PMID:25947381

  8. Exogenous nitric oxide prevents cardiovascular collapse during hemorrhagic shock.

    PubMed

    Nachuraju, Parimala; Friedman, Adam J; Friedman, Joel M; Cabrales, Pedro

    2011-05-01

    This study investigated the systemic and microvascular hemodynamic changes related to increased nitric oxide (NO) availability following significant hemorrhage, made available by administration of NO releasing nanoparticles (NO-nps). Hemodynamic responses to hemorrhagic shock were studied in the hamster window chamber. Acute hemorrhage was induced by arterial controlled bleeding of 50% of blood volume, and the resulting hemodynamic parameters were followed over 90 min. Exogenous NO was administered in the form of NO-nps (5mg/kg suspended in 50 μl saline) 10 min following induced hemorrhage. Control groups received equal dose of NO free nanoparticles (Control-nps) and Vehicle solution. Animals treated with NO-nps partially maintained systemic and microvascular function during hypovolemic shock compared to animals treated with Control-nps or the Vehicle (50 μl saline). The continuous NO released by the NO-nps reverted arteriolar vasoconstriction, partially recovered both functional capillary density and microvascular blood flows. Additionally, NO supplementation post hemorrhage prevented cardiac decompensation, and thereby maintained and stabilized the heart rate. Paradoxically, the peripheral vasodilation induced by the NO-nps did not decrease blood pressure, and combined with NO's effects on vascular resistance, NO-nps promoted intravascular pressure redistribution and blood flow, avoiding tissue ischemia. Therefore, by increasing NO availability with NO-nps during hypovolemic shock, it is possible that cardiac stability and microvascular perfusion can be preserved, ultimately increasing survivability and local tissue viability, and reducing hemorrhagic shock sequelae. The relevance, stability, and efficacy of exogenous NO therapy in the form of NO-nps will potentially facilitate the intended use in battlefield and trauma situations. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  9. Binding of exogenous brain protein kinase C to liver nuclei

    SciTech Connect

    Misra, U.K.; Wolf, M.; Besterman, J.; Cuatrecasas, P.; Sahyoun, N.

    1986-05-01

    Protein kinase C is found both in the cytosol and bound to membranes. Binding of the enzyme to plasma membranes is controlled by calcium whereas enzyme activators regulate both its membrane binding and enzyme catalysis. Activation of protein kinase C has been implicated in several regulatory processes including gene expression. Accordingly, the possibility of direct interaction of protein kinase C with the nucleus was examined utilizing /sup 3/H-PDBu binding to detect the enzyme. Purified protein kinase C from rat brain could bind to purified rat liver nuclei at 4/sup 0/C or at 21/sup 0/C, and the reaction was completed by 20 min. The binding was linearly dependent on protein kinase C concentration and required free Ca/sup 2 +/ with a K/sub m/sub app// of 0.5 ..mu..M. Chelation of Ca/sup 2 +/ with EGTA resulted in a rapid dissociation of protein kinase C from the nuclei. Differential extraction experiments suggested that about 50% of the enzyme was bound to chromatin and 25% was associated with the nuclear matrix. Moreover, protein kinase C bound to nuclei was able to phosphorylate several endogenous nuclear substrates, including chromatin proteins, in a Ca/sup 2 +/ phosphatidyl serine dependent reaction.

  10. Enzyme kinetics of conjugating enzymes: PAPS sulfotransferase.

    PubMed

    James, Margaret O

    2014-01-01

    The sulfotransferase (SULT) enzymes catalyze the formation of sulfate esters or sulfamates from substrates that contain hydroxy or amine groups, utilizing 3'-phosphoadenosyl-5'-phosphosulfate (PAPS) as the donor of the sulfonic group. The rate of product formation depends on the concentrations of PAPS and substrate as well as the sulfotransferase enzyme; thus, if PAPS is held constant while varying substrate concentration (or vice versa), the kinetic constants derived are apparent constants. When studied over a narrow range of substrate concentrations, classic Michaelis-Menten kinetics can be observed with many SULT enzymes and most substrates. Some SULT enzymes exhibit positive or negative cooperativity during conversion of substrate to product, and the kinetics fit the Hill plot. A characteristic feature of most sulfotransferase-catalyzed reactions is that, when studied over a wide range of substrate concentrations, the rate of product formation initially increases as substrate concentration increases, then decreases at high substrate concentrations, i.e., they exhibit substrate inhibition or partial substrate inhibition. This chapter gives an introduction to sulfotransferases, including a historical note, the nomenclature, a description of the function of SULTs with different types of substrates, presentation of examples of enzyme kinetics with SULTs, and a discussion of what is known about mechanisms of substrate inhibition in the sulfotransferases.

  11. Structural and functional comparison of polysaccharide-degrading enzymes.

    PubMed

    Jedrzejas, M J

    2000-01-01

    Sugar molecules as well as enzymes degrading them are ubiquitously present in physiological systems, especially for vertebrates. Polysaccharides have at least two aspects to their function, one due to their mechanical properties and the second one involves multiple regulatory processes or interactions between molecules, cells, or extracellular space. Various bacteria exert exogenous pressures on their host organism to diversity glycans and their structures in order for the host organism to evade the destructive function of such microbes. Many bacterial organism produce glycan-degrading enzymes in order to facilitate their invasion of host tissues. Such polysaccharide degrading enzymes utilize mainly two modes of polysaccharide-degradation, a hydrolysis and a beta-elimination process. The three-dimensional structures of several of these enzymes have been elucidated recently using X-ray crystallography. There are many common structural motifs among these enzymes, mainly the presence of an elongated cleft transversing these molecules which functions as a polysaccharide substrate binding site as well as the catalytic site for these enzymes. The detailed structural information obtained about these enzymes allowed formulation of proposed mechanisms of their action. The polysaccharide lyases utilize a proton acceptance and donation mechanism (PAD), whereas polysaccharide hydrolases use a direct double displacement (DD) mechanism to degrade their substrates.

  12. Incorporation of molybdenum in rubredoxin: models for mononuclear molybdenum enzymes.

    PubMed

    Maiti, Biplab K; Maia, Luisa B; Silveira, Célia M; Todorovic, Smilja; Carreira, Cintia; Carepo, Marta S P; Grazina, Raquel; Moura, Isabel; Pauleta, Sofia R; Moura, José J G

    2015-07-01

    Molybdenum is found in the active site of enzymes usually coordinated by one or two pyranopterin molecules. Here, we mimic an enzyme with a mononuclear molybdenum-bis pyranopterin center by incorporating molybdenum in rubredoxin. In the molybdenum-substituted rubredoxin, the metal ion is coordinated by four sulfurs from conserved cysteine residues of the apo-rubredoxin and two other exogenous ligands, oxygen and thiol, forming a Mo((VI))-(S-Cys)4(O)(X) complex, where X represents -OH or -SR. The rubredoxin molybdenum center is stabilized in a Mo(VI) oxidation state, but can be reduced to Mo(IV) via Mo(V) by dithionite, being a suitable model for the spectroscopic properties of resting and reduced forms of molybdenum-bis pyranopterin-containing enzymes. Preliminary experiments indicate that the molybdenum site built in rubredoxin can promote oxo transfer reactions, as exemplified with the oxidation of arsenite to arsenate.

  13. THESIS-ABSTRACT Supplementation levels of exogenous alpha-amylase in broilers diets.

    PubMed

    Oliveira, H B; Silva, M I A; Mesquita, F R

    2017-08-17

    This study aimed to evaluate the supplementation levels of an exogenous alpha-amylase in broilers diets and compare two indicators in determining the diets energy. The experiment was divided into two parallel evaluations, being one of performance and the other of metabolism. In performance assay, 1,700 one-day-old Cobb-500 male chicks were used. The animals were distributed in 50 experimental plots and evaluated five treatments with ten replicates in a completely randomized design (CRD). The treatments were: a positive control (PC), a negative control (NC) and three alpha-amylase supplementation levels 200, 400 and 600 g/t, and the NC was formulated with 50 and 90 kcal of energy reduction in relation to the PC to the phases from 1 to 21 days and from 22 to 42 days, respectively. In the metabolism assay were used 240 animals, 150 birds for stage from 14 to 21 days and 90 birds to stage from 35 to 42 days of age and the treatments were the same as the performance assay, with six replicates per treatment in CRD. All diets of metabolism test contained the digestibility indicators Lipe(®) (eucalyptus purified lignin) and chromic oxide (Cr2O3), in concentrations of 0.05 and 1.0%, respectively. In the period from 1 to 21 days old, no significant differences were observed in weight gain (WG) (P > 0.05), however, feed intake (FI) was found higher by using 200 ppm of enzyme (P < 0.05) and better feed conversion (FC) with the PC (P < 0.05). From 22 to 42 days, no significant differences were observed on the WG (P > 0.05), but were observed lower FI and better FC to PC treatment (P < 0.05). In the period from 1 to 42 days of age, significant differences were also not observed on the WG (P > 0.05), but there was lower FI and better FC for the PC treatment (P < 0.05). The AMEn (apparent metabolizable energy corrected for nitrogen balance), determined using the total collection, reaffirmed the values ​​calculated for the PC and NC with intermediate data obtained from the

  14. Exogenous administration of DLK1 ameliorates hepatic steatosis and regulates gluconeogenesis via activation of AMPK.

    PubMed

    Lee, Y-H; Yun, M R; Kim, H M; Jeon, B H; Park, B-C; Lee, B-W; Kang, E S; Lee, H C; Park, Y W; Cha, B-S

    2016-02-01

    Activation of Notch signaling pathologically enhances lipogenesis and gluconeogenesis in the liver causing non-alcoholic fatty liver disease (NAFLD) and diabetes. Delta-like 1 homolog (DLK1), an imprinted gene that can modulate adipogenesis and muscle development in mice, was found as an inhibitory regulator of Notch signaling. Therefore, we investigated the metabolic effect of exogenous DLK1 in vitro and in vivo. A soluble DLK1 peptide was generated with fusion between a human Fc fragment and extracellular domain of DLK1. Male db/db mice were randomly assigned to two groups: vehicle treated and DLK1-treated group (25 mg kg(-1), intraperitoneal injection, twice a week for 4 weeks). Primary mice hepatocytes and HepG2 cells were used for in vitro experiments. After 4 weeks of DLK1 administration, hepatic triglyceride content and lipid droplets in liver tissues, as well as serum levels of liver enzymes, were markedly decreased in db/db mice. DLK1 treatment induced phosphorylation of AMPK and ACC and suppressed nuclear expression of SREBP-1c in the mouse liver or hepatocytes, indicating regulation of fatty acid oxidation and synthesis pathways. Furthermore, DLK1-treated mice showed significantly lower levels of fasting and random glucose, with improved glucose and insulin tolerance compared with the vehicle-treated group. Macrophage infiltration and proinflammatory cytokine levels in the epididymal fat were decreased in DLK1-treated db/db mice. Moreover, DLK1 suppressed glucose production from hepatocytes, which was blocked after co-administration of an AMPK inhibitor, compound C. DLK1-treated hepatocytes and mouse liver tissues showed lower PEPCK and G6Pase expression. DLK1 triggered AKT phosphorylation followed by cytosolic translocation of FOXO1 from the nucleus in hepatocytes. The present study demonstrated that exogenous administration of DLK1 reduced hepatic steatosis and hyperglycemia via AMPK activation in the liver. This result suggests that DLK1 may be a

  15. Sulfation patterns of exogenous chondroitin sulfate affect chondrogenic differentiation of ATDC5 cells.

    PubMed

    Kawamura, Daisuke; Funakoshi, Tadanao; Mizumoto, Shuji; Sugahara, Kazuyuki; Iwasaki, Norimasa

    2014-11-01

    Chondroitin sulfate (CS) has been used in cartilage tissue engineering techniques as a positive modulator of scaffolds. CS is a linear polysaccharide consisting of variously sulfated repeating disaccharides. The sulfation patterns of CS are closely related to their biological functions, but only monosulfated CS has been applied to scaffolds. In this study, we investigated the effects of various sulfation patterns of CS on chondrogenic differentiation using ATDC5 chondroprogenitor cells. Disaccharide composition analysis of CS produced by ATDC5 cells at various differentiation steps was performed using high-performance liquid chromatography. ATDC5 cells were cultured with exogenously added, variously sulfated CS. Cell proliferation was analyzed by the 2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium monosodium salt (WST-8) assay. Extracellular matrix production was evaluated by Alcian blue staining. Alkaline phosphatase (ALP) activity was evaluated using an ALP assay kit. Expression of chondrogenic markers was evaluated by real-time reverse transcription polymerase chain reaction (RT-PCR) or an enzyme-linked immunosorbent assay (ELISA) using a Type II Collagen Detection kit. The major components of CS produced by ATDC5 cells were 4-O-monosulfated disaccharides throughout chondrogenic differentiation. Low proportions of 4,6-O-disulfated disaccharides were also detected. Compared to the control group, which did not contain GAGs, the WST-8 assay indicated fewer viable cells when treated with CS-E, which are rich in 4,6-O-disulfated disaccharides. CS-E significantly enhanced Alcian blue staining in a dose-dependent manner and decreased ALP activity after 21 days of culture. Real-time RT-PCR showed that CS-E significantly enhanced all chondrogenic markers, col2a1, aggrecan, and sox9, either at day 4 or day 14 of culture. The results of ELISA analysis confirmed that CS-E significantly enhanced the production of type II collagen. ATDC5

  16. Efficacy of exogenous oral zinc in treatment of patients with carbonic anhydrase VI deficiency.

    PubMed

    Henkin, R I; Martin, B M; Agarwal, R P

    1999-12-01

    We previously described a disorder in 18 patients with decreased parotid saliva gustin/carbonic anhydrase (CA) VI secretion associated with loss of taste (hypogeusia) and smell (hyposmia) and distorted taste (dysgeusia) and smell (dysosmia). Because gustin/CAVI is a zinc-dependent enzyme we instituted a study of treatment with exogenous zinc to attempt to stimulate synthesis/secretion of gustin/CAVI and thereby attempt to correct the symptoms of this disorder. Fourteen of the 18 patients with this disorder completed the study. They were treated with 100 mg of exogenous zinc daily for 4 to 6 months, in an open clinical trial. Both before and after treatment, measurements were obtained of parotid saliva gustin/CAVI, parotid saliva, serum and urine zinc, taste and smell function, and, in some patients, examination of circumvallate taste buds by electron microscopy. Treatment success was predicated upon significant increases in parotid saliva gustin/CAVI. This occurred in 10 of the 14 patients who were labeled responders; they also exhibited improvement in taste and smell acuity, a diminution in dysgeusia and dysosmia and increased zinc concentrations in parotid saliva, serum, and urine. Taste bud morphology returned to normal in each responder in whom it was measured. No increase in gustin/CAVI occurred in 4 patients who were labeled nonresponders; they exhibited no improvement in taste or smell acuity and no increases in parotid saliva zinc. However, serum and urine zinc increased to levels similar to those measured in the 10 responders. Two of 4 nonresponders reported diminution in dysgeusia and dysosmia. Taste bud morphology did not change from the abnormal state in the 1 nonresponder in whom it was measured. Zinc treatment is effective in patients in whom this trace metal increases synthesis/secretion of gustin/CAVI and ineffective in those in whom it does not. Increased gustin/CAVI in this disorder is probably associated with zinc stimulation of the gene

  17. Evolutionary dynamics of enzymes.

    PubMed

    Demetrius, L

    1995-08-01

    This paper codifies and rationalizes the large diversity in reaction rates and substrate specificity of enzymes in terms of a model which postulates that the kinetic properties of present-day enzymes are the consequence of the evolutionary force of mutation and selection acting on a class of primordial enzymes with poor catalytic activity and broad substrate specificity. Enzymes are classified in terms of their thermodynamic parameters, activation enthalpy delta H* and activation entropy delta S*, in their kinetically significant transition states as follows: type 1, delta H* > 0, delta S* < 0; type 2, delta H* < or = 0, delta S* < or = 0; type 3, delta H* > 0, delta S* > 0. We study the evolutionary dynamics of these three classes of enzymes subject to mutation, which acts at the level of the gene which codes for the enzyme and selection, which acts on the organism that contains the enzyme. Our model predicts the following evolutionary trends in the reaction rate and binding specificity for the three classes of molecules. In type 1 enzymes, evolution results in random, non-directional changes in the reaction rate and binding specificity. In type 2 and 3 enzymes, evolution results in a unidirectional increase in both the reaction rate and binding specificity. We exploit these results in order to codify the diversity in functional properties of present-day enzymes. Type 1 molecules will be described by intermediate reaction rates and broad substrate specificity. Type 2 enzymes will be characterized by diffusion-controlled rates and absolute substrate specificity. The type 3 catalysts can be further subdivided in terms of their activation enthalpy into two classes: type 3a (delta H* small) and type 3b (delta H* large). We show that type 3a will be represented by the same functional properties that identify type 2, namely, diffusion-controlled rates and absolute substrate specificity, whereas type 3b will be characterized by non-diffusion-controlled rates and absolute

  18. Exogenous folate ameliorates ethanol-induced brain hyperhomocysteinemia and exogenous ethanol reduces taurine levels in chick embryos.

    PubMed

    Barnett, Robert K; Booms, Stephanie L; Gura, Tracy; Gushrowski, Mara; Miller, Robert R

    2009-07-01

    The effects of exogenous ethanol and/or folic acid on endogenous homocysteine (HoCys) and SAM (S-adenosylmethionine)/SAH (S-adenosylhomocysteine) levels in chick brains were studied at 11 days of development. Embryonic EtOH (3.0 mmol/kg egg) exposure caused a 1.6-fold increase in brain HoCys levels and a 9-fold decrease in brain SAM/SAH levels as compared to controls (pexogenous EtOH on the remethylation pathway, as measured by 10-formyltetrahydrofolate dehydrogenase (10-FTHF DH) activities, and the transsulfuration pathway, as measured by taurine levels, were studied at 18 days of development. A single dosage of EtOH (3.0 mmol/kg egg; E(0)) and two daily dosages of EtOH (E(0-1)) failed to influence brain and hepatic 10-FTHF DH activities when compared to controls. However, three daily dosages of EtOH (E(0-2)) caused approximately a two-fold increase in brain 10-FTHF DH activities and a three-fold increase in hepatic 10-FTHF DH activities as compared to controls (p

  19. [Effects of exogenous nitric oxide on physiological characteristics of longan (Dimocarpus longana) seedlings under acid rain stress].

    PubMed

    Liu, Jian-fu; Wang, Ming-yuan; Yang, Chen; Zhu, Ai-jun

    2013-08-01

    This paper studied the effects of exogenous nitric oxide donor sodium nitroprusside (SNP) on the chlorophyll content, antioxidant enzyme activities, and osmotic regulation substances of longan (Dimocarpus longana 'Fuyan') seedlings under acid rain (pH 3.0) stress. Under the acid rain stress, the seedling leaf superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities and chlorophyll, soluble protein and soluble sugar contents decreased obviously, while the leaf malondialdedyde content had a remarkable increase, suggesting the toxic effect of the acid rain on the seedlings. Exogenous nitric oxide had dual nature on the physiological characteristics of longan seedlings under acid rain stress. Applying 0.1-0.5 mmol x L(-1) of SNP improved the SOD, POD and CAT activities and the chlorophyll, soluble protein and soluble sugar contents significantly, and decreased the malondialdedyde content. Low concentrations SNP reduced the oxidative damage caused by the acid rain stress, and 0.5 mmol x L(-1) of SNP had the best effect. Under the application of 0.5 mmol x L(-1) of SNP, the total chlorophyll, soluble protein, and soluble sugar contents and the SOD, POD and CAT activities increased by 76.0%, 107.0%, 216.1%, 150. 0%, 350.9% and 97.1%, respectively, and the malondialdedyde content decreased by 46.4%. It was suggested that low concentration (0.1-0.5 mmol x L(-1)) SNP could alleviate the toxic effect of acid rain stress on longan seedlings via activating the leaf antioxidant enzyme activities and reducing oxidative stress, while high concentration SNP (1.0 mmol x L(-1)) lowered the mitigation effect.

  20. Effect of exogenous phytase on feed inositol phosphate hydrolysis in an in vitro rumen fluid buffer system.

    PubMed

    Brask-Pedersen, D N; Glitsø, L V; Skov, L K; Lund, P; Sehested, J

    2011-02-01

    Three in vitro experiments using a rumen fluid buffer system were performed to investigate the effect of addition of 4 experimental phytases (Phy1, Phy2, Phy3, and Phy4) compared with no addition of phytase on feed inositol phosphate hydrolysis in wheat and rapeseed cake to determine which of the 4 phytases was most suitable under rumen-like conditions. The feedstuffs were incubated with a mixture of physiological buffer, ruminal fluid, and exogenous phytase at pH 6.2, after which the samples were incubated for different periods. Incubations were stopped using HCl, and the samples were analyzed for inositol phosphates via high performance ion chromatography. Addition of phytase (Phy1) resulted in enhanced degradation of myo-inositol hexakisphosphate (InsP(6)) in rapeseed cake, whereas addition of exogenous phytase did not improve the degradation of InsP(6) in wheat. Only rapeseed cake was therefore used subsequently. All 4 phytases increased degradation of InsP(6) in rapeseed cake in the in vitro system, and degradability of InsP(6) increased with higher incubation time and higher phytase dosages, independent of phytase. Addition of 2 units of phytase per gram of substrate of the phytases Phy1, Phy2, Phy3, and Phy4 led to an undegraded InsP(6) content of 56, 49, 70, and 18%, respectively, when incubated with rapeseed cake for 6h, indicating that Phy2 and Phy4 were the most effective phytases. However, Phy2 had a higher specific activity than Phy4, as 60% of the original InsP(6) content was remaining after 3h when 5mg of enzyme protein per gram of substrate of Phy2 was added to rapeseed cake, whereas 150 mg of enzyme protein per gram of substrate of Phy4 was necessary to achieve a similar result. Therefore, Phy2 appeared to be most applicable under rumen-like conditions.

  1. Catalyzed enzyme electrodes

    DOEpatents

    Zawodzinski, Thomas A.; Wilson, Mahlon S.; Rishpon, Judith; Gottesfeld, Shimshon

    1993-01-01

    An enzyme electrode is prepared with a composite coating on an electrical conductor. The composite coating is formed from a casting solution of a perfluorosulfonic acid polymer, an enzyme, and a carbon supported catalyst. The solution may be cast directly on the conductor surface or may be formed as a membrane and applied to the surface. The perfluorosulfonic acid ionomer formed from the casting solution provides an insoluble biocompatible protective matrix for the enzyme and acts to retain the enzyme for long term availability in the electrode structure. The carbon supported catalyst provides catalytic sites throughout the layer for the oxidation of hydrogen peroxide from the enzyme reactions. The carbon support then provides a conductive path for establishing an electrical signal to the electrical conductor. In one embodiment, the electrical conductor is a carbon cloth that permits oxygen or other gas to be introduced to the perfluorosulfonic polymer to promote the enzyme reaction independent of oxygen in the solution being tested.

  2. Rational enzyme redesign

    SciTech Connect

    Ornstein, R.L.

    1994-05-01

    Protein engineering is first a means of elucidating structure-function relations in an enzyme, and second, a means of changing a protein to make it serve a different, but generally related, purpose. In principle, one may change the functional characteristics of an enzyme by altering its substrate specificity, kinetics, optimum range of activity, and chemical mechanism. Obviously one cannot make all possible combinations of amino acid changes for even the smallest enzyme, so the essential question is which changes to make. The intent of rational protein/enzyme redesign is to alter a protein/enzyme in a timely and premeditated fashion. This article provides an outline of the process of rational enzyme redesign.

  3. Magnetically responsive enzyme powders

    NASA Astrophysics Data System (ADS)

    Pospiskova, Kristyna; Safarik, Ivo

    2015-04-01

    Powdered enzymes were transformed into their insoluble magnetic derivatives retaining their catalytic activity. Enzyme powders (e.g., trypsin and lipase) were suspended in various liquid media not allowing their solubilization (e.g., saturated ammonium sulfate and highly concentrated polyethylene glycol solutions, ethanol, methanol, 2-propanol) and subsequently cross-linked with glutaraldehyde. Magnetic modification was successfully performed at low temperature in a freezer (-20 °C) using magnetic iron oxides nano- and microparticles prepared by microwave-assisted synthesis from ferrous sulfate. Magnetized cross-linked enzyme powders were stable at least for two months in water suspension without leakage of fixed magnetic particles. Operational stability of magnetically responsive enzymes during eight repeated reaction cycles was generally without loss of enzyme activity. Separation of magnetically modified cross-linked powdered enzymes from reaction mixtures was significantly simplified due to their magnetic properties.

  4. Enzymes for improved biomass conversion

    DOEpatents

    Brunecky, Roman; Himmel, Michael E.

    2016-02-02

    Disclosed herein are enzymes and combinations of the enzymes useful for the hydrolysis of cellulose and the conversion of biomass. Methods of degrading cellulose and biomass using enzymes and cocktails of enzymes are also disclosed.

  5. Profiling the orphan enzymes

    PubMed Central

    2014-01-01

    The emergence of Next Generation Sequencing generates an incredible amount of sequence and great potential for new enzyme discovery. Despite this huge amount of data and the profusion of bioinformatic methods for function prediction, a large part of known enzyme activities is still lacking an associated protein sequence. These particular activities are called “orphan enzymes”. The present review proposes an update of previous surveys on orphan enzymes by mining the current content of public databases. While the percentage of orphan enzyme activities has decreased from 38% to 22% in ten years, there are still more than 1,000 orphans among the 5,000 entries of the Enzyme Commission (EC) classification. Taking into account all the reactions present in metabolic databases, this proportion dramatically increases to reach nearly 50% of orphans and many of them are not associated to a known pathway. We extended our survey to “local orphan enzymes” that are activities which have no representative sequence in a given clade, but have at least one in organisms belonging to other clades. We observe an important bias in Archaea and find that in general more than 30% of the EC activities have incomplete sequence information in at least one superkingdom. To estimate if candidate proteins for local orphans could be retrieved by homology search, we applied a simple strategy based on the PRIAM software and noticed that candidates may be proposed for an important fraction of local orphan enzymes. Finally, by studying relation between protein domains and catalyzed activities, it appears that newly discovered enzymes are mostly associated with already known enzyme domains. Thus, the exploration of the promiscuity and the multifunctional aspect of known enzyme families may solve part of the orphan enzyme issue. We conclude this review with a presentation of recent initiatives in finding proteins for orphan enzymes and in extending the enzyme world by the discovery of new

  6. Enzymes on material surfaces.

    PubMed

    Talbert, Joey N; Goddard, Julie M

    2012-05-01

    Enzyme interactions with material surfaces are of interest for industrial food and pharmaceutical transformations, biosensors, artificial cells, cell free reactions, drug and nutrition delivery technologies, and imaging. When in contact with a material surface, an enzyme may lose or appear to lose activity due to the nature of the enzyme, the nature of the material, and/or the nature of the interface between the enzyme, material, and substrate environment. The purpose of this review is to survey recent advances that have been made towards the preservation, optimization, and enhancement of enzyme activity on material surfaces within the context of well-known concepts that describe the loss of activity after immobilization. This review breaks down the immobilized enzyme system to look at the individual components of the system-namely the enzyme, the material, and the interface. For each piece, possible causes for the loss of enzyme activity are described as well as strategies that have been applied to limit the affect. At the conclusion we identify areas of future research needed to overcome limitations in the current state-of-the art for immobilized enzyme systems.

  7. Food and feed enzymes.

    PubMed

    Fraatz, Marco Alexander; Rühl, Martin; Zorn, Holger

    2014-01-01

    Humans have benefited from the unique catalytic properties of enzymes, in particular for food production, for thousands of years. Prominent examples include the production of fermented alcoholic beverages, such as beer and wine, as well as bakery and dairy products. The chapter reviews the historic background of the development of modern enzyme technology and provides an overview of the industrial food and feed enzymes currently available on the world market. The chapter highlights enzyme applications for the improvement of resource efficiency, the biopreservation of food, and the treatment of food intolerances. Further topics address the improvement of food safety and food quality.

  8. Structurally stable gel bead containing entrapped enzyme and method for manufacture thereof

    DOEpatents

    Woodward, J.

    1998-12-08

    This research provides a structurally stable gel bead containing an entrapped enzyme and a method for its manufacture. The enzyme is covalently cross-linked to gelatin in the presence of glutaraldehyde prior to the formation of the gel bead, to prevent leakage of the enzyme. Propylene glycol alginate is then added to the mixture. Once the gel beads are formed, they are then soaked in glutaraldehyde, which imparts structural stability to the gel beads. This method can be used with many types of enzymes, such as proteases, carbohydrases, proteases, ligases, isomerases, oxidoreductases, and specialty enzymes. These and other enzymes can be immobilized in the gel beads and utilized in a number of enzymatic processes. Exogenously added ions are not required to maintain the structural stability of these gel beads. 7 figs.

  9. Structurally stable gel bead containing entrapped enzyme and method for manufacture thereof

    DOEpatents

    Woodward, Jonathan

    1998-01-01

    A structurally stable gel bead containing an entrapped enzyme and a method for its manufacture. The enzyme is covalently cross-linked to gelatin in the presence of glutaraldehyde prior to the formation of the gel bead, to prevent leakage of the enzyme. Propylene glycol alginate is then added to the mixture. Once the gel beads are formed, they are then soaked in glutaraldehyde, which imparts structural stability to the gel beads. This method can be used with many types of enzymes, such as proteases, carbohydrases, proteases, ligases, isomerases, oxidoreductases, and specialty enzymes. These and other enzymes can be immobilized in the gel beads and utilized in a number of enzymatic processes. Exogenously added ions are not required to maintain the structural stability of these gel beads.

  10. [Disappearance of ALS from Guam: implications for exogenous causes].

    PubMed

    Chen, K M

    1995-12-01

    The author reports the disappearance of amyotrophic lateral sclerosis (ALS) from Guam over past 30 years, which coincided with rapid changes in the ecology, socioeconomy, and westernization of the life style. This slow but steady decline is believed to be the consequences of radical changes from food collection to wage-based life style and dietary improvement in recent years and elimination of exogenous factors. Those risk factor(s) are believed to be the environmental trace metals which must have triggered the accelerated oxidative stresses in the motor neurons of genetically susceptible population. Changing Epidermiology: 1. The annual incidence of 70/100,000 in 1960s down to 7/100,000 in 1990s, and remained unchanged for past 15 years. 2. Upward shift of age at onset by 10 years and at death by 8 years and even out of sex ratio. 3. Birth cohort analysis showed less risks for those born after 1920. No ALS cases born after 1945. 4. No increase in the incidence of ALS among non-Chamorros transients of Guam and Marianas during W.W.II. 5. Long-term resident non-Charmorro and half-Chamorros on Guam are also affected. 6. Charmorro migrants to U.S. Mainland are affected after long absence from Guam. 7. Incubation period for both ways is estimated to be 18 approximately 20 years. 8. Other forms of dementias like Alzheimer disease (AD) and vascular dementias are on the rise and the leading cause of death is cerebro- and cardiovascular diseases. 9. ALS is also declining in past 10 approximately 15 years in Kii peninsula, and West New Guinea. Changing Ecology of Guam: 1. One third of Island land was used for construction of huge military bases after W.W.II. 2. Urbanization of villages including concrete houses, deep well water supply, sewage, and electrification. 3. Tourism boom: high-rise hotels, development of 7 golf courses and other recreational facilities resulted in loss of flora and erosions of soil. Socioeconomic Changes: 1. Shift in population demography; Efflux of

  11. Comparative Physiological, Biochemical, and Genetic Responses to Prolonged Waterlogging Stress in Okra and Maize Given Exogenous Ethylene Priming

    PubMed Central

    Vwioko, Emuejevoke; Adinkwu, Onyekachukwu; El-Esawi, Mohamed A.

    2017-01-01

    Waterlogging is an environmental challenge affecting crops worldwide. Ethylene induces the expression of genes linked to important agronomic traits under waterlogged conditions. The ability of okra (Abelmoschus esculentus L. Moench.) and maize (Zea mays L.) given exogenous ethylene priming to tolerate prolonged waterlogged conditions was investigated in this study. The investigation was carried out as field experiments using 3 week-old plants grouped into four treatments; control, waterlogged plants, ethylene priming of plants before waterlogging, and ethylene priming of plants after waterlogging. Different growth parameters were recorded. Soil chemical and bacterial analyses were performed. The activity and gene expression of antioxidant enzymes were studied. The ethylene biosynthetic genes expression analysis and root anatomy of surviving okra plants were also carried out. Results revealed that okra and maize plants showed increase in their height under waterlogged conditions. Ethylene priming and waterlogged conditions induced early production of adventitious roots in okra and maize. Maize survival lasted between 5 and 9 weeks under waterlogging without reaching the flowering stage. However, okra survived up to 15 weeks under waterlogging producing flower buds and fruits in all treatments. Variable changes were also recorded for total soluble phenolics of soil. Cross sections of waterlogged okra roots showed the formation of a dark peripheral layer and numerous large aerenchyma cells which may have assisted in trapping oxygen required for survival. The activity and gene expression levels of antioxidant enzymes were studied and showed higher increases in the root and leaf tissues of okra and maize subjected to both waterlogging and ethylene priming, as compared to control or waterlogged condition. Quantitative RT-PCR analysis also showed that the ethylene biosynthetic gene expression levels in all okra and maize tissues were up-regulated and showed much higher

  12. Comparative Physiological, Biochemical, and Genetic Responses to Prolonged Waterlogging Stress in Okra and Maize Given Exogenous Ethylene Priming.

    PubMed

    Vwioko, Emuejevoke; Adinkwu, Onyekachukwu; El-Esawi, Mohamed A

    2017-01-01

    Waterlogging is an environmental challenge affecting crops worldwide. Ethylene induces the expression of genes linked to important agronomic traits under waterlogged conditions. The ability of okra (Abelmoschus esculentus L. Moench.) and maize (Zea mays L.) given exogenous ethylene priming to tolerate prolonged waterlogged conditions was investigated in this study. The investigation was carried out as field experiments using 3 week-old plants grouped into four treatments; control, waterlogged plants, ethylene priming of plants before waterlogging, and ethylene priming of plants after waterlogging. Different growth parameters were recorded. Soil chemical and bacterial analyses were performed. The activity and gene expression of antioxidant enzymes were studied. The ethylene biosynthetic genes expression analysis and root anatomy of surviving okra plants were also carried out. Results revealed that okra and maize plants showed increase in their height under waterlogged conditions. Ethylene priming and waterlogged conditions induced early production of adventitious roots in okra and maize. Maize survival lasted between 5 and 9 weeks under waterlogging without reaching the flowering stage. However, okra survived up to 15 weeks under waterlogging producing flower buds and fruits in all treatments. Variable changes were also recorded for total soluble phenolics of soil. Cross sections of waterlogged okra roots showed the formation of a dark peripheral layer and numerous large aerenchyma cells which may have assisted in trapping oxygen required for survival. The activity and gene expression levels of antioxidant enzymes were studied and showed higher increases in the root and leaf tissues of okra and maize subjected to both waterlogging and ethylene priming, as compared to control or waterlogged condition. Quantitative RT-PCR analysis also showed that the ethylene biosynthetic gene expression levels in all okra and maize tissues were up-regulated and showed much higher

  13. Endogenous and exogenous progesterone influence body temperature in dairy cows.

    PubMed

    Suthar, V S; Burfeind, O; Bonk, S; Dhami, A J; Heuwieser, W

    2012-05-01

    Three experiments were conducted to determine the effect of endogenous progesterone (P4) on body temperature comparing lactating, pregnant with lactating, nonpregnant cows, and to study the effect of exogenous P4 administered via a controlled internal drug release (CIDR) insert on body temperature in lactating dairy cows. Body temperature was measured vaginally and rectally using temperature loggers and a digital thermometer, respectively. In experiment 1, 10 cyclic lactating cows (3 primiparous, 7 multiparous) and 10 lactating, pregnant cows (3 primiparous, 7 multiparous) were included. Vaginal temperatures and serum P4 concentrations were greater in pregnant cows (vaginal: 0.3±0.01°C; P4: 5.5±0.4 ng/mL) compared with nonpregnant cows. In experiment 2, estrous cycles of 14 postpartum healthy, cyclic, lactating cows (10 primiparous, 4 multiparous) were synchronized, and cows were assigned randomly to 1 of 2 treatments (CIDR-P4 or CIDR-blank). A temperature logger was inserted 1 d after ovulation using a P4-free CIDR (CIDR-blank) and a CIDR containing 1.38g of P4 (CIDR-P4) in the control (n=7) and the P4-treated group (n=7), respectively. On d 3 after P4 treatment, vaginal temperature was 0.3±0.03°C greater compared with that on d 1 and d 5. In experiment 3, 9 cyclic multiparous lactating cows were enrolled 1±1 d after confirmed ovulation and a temperature logger inserted. Two days later, a CIDR-P4 was inserted on top of the CIDR-blank. On d 5±1 and d 7±1, respectively, the CIDR-P4 and CIDR-blank with the temperature logger were removed. During the CIDR-P4 treatment (48h), vaginal temperature was 0.2±0.05°C and 0.1±0.05°C greater than during the pre- and post-treatment periods (48h), respectively. Serum P4 concentration peaked during CIDR-P4 treatment (2.2±0.8 ng/mL) and was greater than during the pre-treatment period (0.2±0.2 ng/mL) for 48h. An increase in vaginal temperature could be due to endogenous and exogenous P4. However, a correlation between

  14. Exploring exogenic sources for the olivine on Asteroid (4) Vesta

    NASA Astrophysics Data System (ADS)

    Le Corre, Lucille; Reddy, Vishnu; Sanchez, Juan A.; Dunn, Tasha; Cloutis, Edward A.; Izawa, Matthew R. M.; Mann, Paul; Nathues, Andreas

    2015-09-01

    The detection of olivine on Vesta is interesting because it may provide critical insights into planetary differentiation early in our Solar System's history. Ground-based and Hubble Space Telescope (HST) observations of Asteroid (4) Vesta have suggested the presence of olivine on the surface. These observations were reinforced by the discovery of olivine-rich HED meteorites from Vesta in recent years. However, analysis of data from NASA's Dawn spacecraft has shown that this "olivine-bearing unit" is actually impact melt in the ejecta of Oppia crater. The lack of widespread mantle olivine, exposed during the formation of the 19 km deep Rheasilvia basin on Vesta's South Pole, further complicated this picture. Ammannito et al. (Ammannito, E. et al. [2013a]. Nature 504, 122-125) reported the discovery of local scale olivine-rich units in the form of excavated material from the mantle using the Visible and InfraRed spectrometer (VIR) on Dawn. These sites are concentrated in the walls and ejecta of craters Arruntia (10.5 km in diameter) and Bellicia (41.7 km in diameter), located in the northern hemisphere, 350-430 km from Rheasilvia basin's rim. Here we explore alternative sources for the olivine in the northern hemisphere of Vesta by reanalyzing the data from the VIR instrument using laboratory spectral measurements of meteorites. Our rationale for using the published dataset was to bypass calibration issues and ensure a consistent dataset between the two studies. Our analysis of the VIR data shows that while the interpretation of their spectra as an olivine-rich unit is correct, the nature and origin of that olivine could be more complicated. We suggest that these olivine exposures could also be explained by the delivery of olivine-rich exogenic material. This hypothesis is supported by meteoritical evidence in the form of exogenic xenoliths containing significant amount of olivine in some of the HED meteorites from Vesta. Previous laboratory work on HEDs show that

  15. Exogenous DNA uptake by bovine spermatozoa does not induce DNA fragmentation.

    PubMed

    Feitosa, W B; Mendes, C M; Milazzotto, M P; Rocha, A M; Martins, L F; Simões, R; Paula-Lopes, F F; Visintin, J A; Assumpção, M E O A

    2010-09-01

    Sperm-mediated gene transfer (SMGT) is a fast and low-cost method used to produce transgenic animals. The objective of this study was to evaluate the effects of the concentration of exogenous DNA and the duration of incubation on DNA uptake by bovine spermatozoa and subsequently the integrity of sperm DNA and sperm apoptosis. Spermatozoa (5 x 10(6) cells/mL) were incubated with 100, 300, or 500 ng of exogenous DNA (pEYFP-Nuc plasmid) for 60 or 120 min at 39 degrees C. The amount of exogenous DNA associated with spermatozoa was quantified by real-time PCR, and the percentages of DNA fragmentation in spermatozoa were evaluated using SCSA and a TUNEL assay, coupled with flow cytometry. Uptake of exogenous DNA increased significantly as incubation increased from 60 to 120 min (0.0091 and 0.028 ng, respectively), but only when the highest exogenous DNA concentration (500 ng) was used (P < 0.05). Based on SCSA and TUNEL assays, there was no effect of exogenous DNA uptake or incubation period on sperm DNA integrity. In conclusion, exogenous DNA uptake by bovine spermatozoa was increased with the highest exogenous DNA concentration and longest incubation period, but fragmentation of endogenous DNA was apparently not induced. Copyright 2010 Elsevier Inc. All rights reserved.

  16. [Pneumonia or drug-related exogenic allergic alveolitis? Key role of anamnesis in differential diagnosis].

    PubMed

    Skipskiĭ, I M; Efimov, N V; Dantsig, I I; Matiukhina, L M; Kostina, O Ia

    2011-01-01

    A case is reported of an old female patient with exogenic allergic alveolitis which was first diagnosed as pneumonia progressing in the presence of long-term and intensive antibiotic treatment. Detailed analysis of the case history gave grounds for suspected drug-related exogenic allergic alveolitis. Discontinuation of antibiotics, administration of glucocorticoids and antiplatelet drugs led to recovery.

  17. Drug-metabolizing enzymes: mechanisms and functions.

    PubMed

    Sheweita, S A

    2000-09-01

    Drug-metabolizing enzymes are called mixed-function oxidase or monooxygenase and containing many enzymes including cytochrome P450, cytochrome b5, and NADPH-cytochrome P450 reductase and other components. The hepatic cytochrome P450s (Cyp) are a multigene family of enzymes that play a critical role in the metabolism of many drugs and xenobiotics with each cytochrome isozyme responding differently to exogenous chemicals in terms of its induction and inhibition. For example, Cyp 1A1 is particularly active towards polycyclic aromatic hydrocarbons (PAHs), activating them into reactive intermediates those covalently bind to DNA, a key event in the initiation of carcinogenesis. Likewise, Cyp 1A2 activates a variety of bladder carcinogens, such as aromatic amines and amides. Also, some forms of cytochrome P450 isozymes such as Cyp 3A and 2E1 activate the naturally occurring carcinogens (e.g. aflatoxin B1) and N-nitrosamines respectively into highly mutagenic and carcinogenic agents. The carcinogenic potency of PAHs, and other carcinogens and the extent of binding of their ultimate metabolites to DNA and proteins are correlated with the induction of cytochrome P450 isozymes. Phase II drug-metabolizing enzymes such as glutathione S-transferase, aryl sulfatase and UDP-glucuronyl transferase inactivate chemical carcinogens into less toxic or inactive metabolites. Many drugs change the rate of activation or detoxification of carcinogens by changing the activities of phases I and II drug-metabolizing enzymes. The balance of detoxification and activation reactions depends on the chemical structure of the agents, and is subjected to many variables that are a function of this structure, or genetic background, sex, endocrine status, age, diet, and the presence of other chemicals. It is important to realize that the enzymes involved in carcinogen metabolism are also involved in the metabolism of a variety of substrates, and thus the introduction of specific xenobiotics may change

  18. [Cytologic features of bronchoalveolar lavage in evaluation of course of exogenous allergic alveolitis].

    PubMed

    Lepekha, L N; Aleksandrova, E A; Evgushchenko, G V; Makar'iants, N N; Lovacheva, O V

    2012-01-01

    Application of complex of modern cytologic methods of research bronchoalveolar lavage allowed to allocate most characteristics of development of lymphocytic and macrophagic reaction of bronchial tree in different course of exogenous allergic alveolitis. The most indicative in assessment of origin of exogenous allergic alveolitis development is the characteristics of macrophagic population. In acute course of exogenous allergic alveolitis the considerable number of young activated and non-activated macrophages, increased number of mature phagocytes is observed. Even more significant increase of phagocytic macrophages is observed at dissemination which is primarily is connected with participation of these cells in lymphocytic apoptosis which takes place in high percentage of lymphocytes (up to 49%). Increased number of mature phagocytes is observed at chronic course of exogenous allergic alveolitis that is an important diagnostic pattern of this option of development of exogenous allergic alveolitis in association with the lowest T-helpers/T-supressors index.

  19. Enzymes in Fermented Fish.

    PubMed

    Giyatmi; Irianto, H E

    Fermented fish products are very popular particularly in Southeast Asian countries. These products have unique characteristics, especially in terms of aroma, flavor, and texture developing during fermentation process. Proteolytic enzymes have a main role in hydrolyzing protein into simpler compounds. Fermentation process of fish relies both on naturally occurring enzymes (in the muscle or the intestinal tract) as well as bacteria. Fermented fish products processed using the whole fish show a different characteristic compared to those prepared from headed and gutted fish. Endogenous enzymes like trypsin, chymotrypsin, elastase, and aminopeptidase are the most involved in the fermentation process. Muscle tissue enzymes like cathepsins, peptidases, transaminases, amidases, amino acid decarboxylases, glutamic dehydrogenases, and related enzymes may also play a role in fish fermentation. Due to the decreased bacterial number during fermentation, contribution of microbial enzymes to proteolysis may be expected prior to salting of fish. Commercial enzymes are supplemented during processing for specific purposes, such as quality improvement and process acceleration. In the case of fish sauce, efforts to accelerate fermentation process and to improve product quality have been studied by addition of enzymes such as papain, bromelain, trypsin, pepsin, and chymotrypsin. © 2017 Elsevier Inc. All rights reserved.

  20. The metabolic fate of exogenous sorbitol in the rat

    SciTech Connect

    Ertel, N.H.; Akgun, S.; Kemp, F.W.; Mittler, J.C.

    1983-03-01

    Dietary sorbitol is rapidly converted to fructose and other carbohydrates in the liver, but its metabolic fate has not been studied rigorously. Twenty-four rats were given 20.4 muCi (/sup 14/C)sorbitol with 100 mg of sorbitol, and groups of six were killed at 1, 3, 6, and 24 hours after sorbitol administration. Rats were also fed 6.9 muCi (/sup 14/C)sorbitol for 7 or 14 days. Serum, liver, and lens were analyzed for /sup 14/C-labeled sorbitol, fructose, and glucose by using high-performance liquid chromatography. Negligible radioactivity (1.1%) was found in the gastrointestinal content at 24 hours indicating virtually complete absorption. Most of the radioactivity was recovered in the glucose fraction in serum, liver and lens. Glucose and fructose concentrations showed some decline by day 14 compared with day 7 in serum and liver. However, in the lens, sorbitol showed a peak value at the end of the 14th day (37.5 +/- 9.9 micrograms/pair). These findings suggest that: 1) after oral administration, sorbitol is completely absorbed, and 2) that there is a finite accumulation of sorbitol and fructose in the lens in 14 days. Although the radioactive label indicated the exogenous origin of these carbohydrates, it is not certain whether the sorbitol is converted to glucose before entering and accumulating in the lens.

  1. Association of Cervical Microglandular Hyperplasia With Exogenous Progestin Exposure.

    PubMed

    Heller, Debra S; Nguyen, Lena; Goldsmith, Laura T

    2016-04-01

    Although microglandular hyperplasia is a benign endocervical lesion, it may raise concern of malignancy in an inexperienced pathologist, because clinicians may not be familiar with it on a report. It has been reported to occur in association with progestational stimulation, but this has not been well studied. The aim of the study was to evaluate this potential association. This was an observational case control study of patients seen from January 01, 1991 to November 01, 2014 at the University Hospital, Newark, New Jersey. Cases of microglandular hyperplasia and controls were identified from the files of the Department of Pathology. Controls were cases of endocervical curettages for whom no microglandular hyperplasia was detected. Medical records were reviewed for evidence of exogenous progestin exposure within the previous 6 months. Eighty-nine cases of microglandular hyperplasia and 97 controls were identified. Of the cases of microglandular hyperplasia, 26 (29.2%) of 89 cases had exposure to progestational medication, significantly greater than that of controls (10/97, 10.3%; p = .0014). Our data show that a significantly higher percentage of women with microglandular hyperplasia had progestin exposure than women who do not exhibit this benign lesion. Clinicians and pathologists should be aware of this association, as well as the benign nature of the lesion.

  2. Lung protection by inhalation of exogenous solubilized extracellular matrix

    PubMed Central

    Wu, Jinglei; Ravikumar, Priya; Nguyen, Kytai T.; Hsia, Connie C. W.

    2017-01-01

    Decellularized extracellular matrix (ECM) contains complex tissue-specific components that work in concert to promote tissue repair and constructive remodeling and has been used experimentally and clinically to accelerate epithelial wound repair, leading us to hypothesize that lung-derived ECM could mitigate acute lung injury. To explore the therapeutic potential of ECM for noninvasive delivery to the lung, we decellularized and solubilized porcine lung ECM, then characterized the composition, concentration, particle size and stability of the preparation. The ECM preparation at 3.2 mg/mL with average particle size <3 μm was tested in vitro on human A549 lung epithelial cells exposed to 95% O2 for 24 hours, and in vivo by tracheal instillation or nebulization into the lungs of rats exposed intermittently or continuously to 90% O2 for a cumulative 72 hours. Our results showed that the preparation was enriched in collagen, reduced in glycosaminoglycans, and contained various bioactive molecules. Particle size was concentration-dependent. Compared to the respective controls treated with cell culture medium in vitro or saline in vivo, ECM inhalation normalized cell survival and alveolar morphology, and reduced hyperoxia-induced apoptosis and oxidative damage. This proof-of-concept study established the methodology, feasibility and therapeutic potential of exogenous solubilized ECM for pulmonary cytoprotection, possibly as an adjunct or potentiator of conventional therapy. PMID:28151947

  3. Endogenous and exogenous fluorescence of gastrointestinal tumors: initial clinical observations

    NASA Astrophysics Data System (ADS)

    Borisova, Ekaterina; Plamenova, Lilia; Keremedchiev, Momchil; Vladimirov, Borislav; Avramov, Latchezar

    2013-03-01

    The limitations of standard endoscopy for detection and evaluation of cancerous changes in gastrointestinal tract (GIT) are significant challenge and initiate development of new diagnostic modalities. Therefore many spectral and optical techniques are applied recently into the clinical practice for obtaining qualitatively and quantitatively new data from gastrointestinal neoplasia with different level of clinical applicability and diagnostic success. One of the most promising approaches is fluorescence detection using naturally existing fluorescent molecules or added fluorescent markers. Deltaaminolevulinic acid / protoporphyrin IX is applied for exogenous fluorescent tumor detection in the upper part of gastrointestinal tract. The 5-ALA is administered per os six hours before measurements at dose 20mg/kg weight. Highpower light-emitting diode at 405 nm is used as a source and the excitation light is passed through the light-guide of standard video-endoscopic system to obtain 2-D visualization. Both kinds of spectra - autofluorescence signals and protoporphyrin IX signal are recorded and stored using a fiber-optic microspectrometer, as in endoscopy instrumental channel a fiber is applied to return information about fluorescence signals. In such way 1-D detection and 2-D visualization of the lesions' fluorescence are received. The results from in vivo detection show significant differentiation between normal and abnormal tissues in 1-D spectroscopic regime, but only moderate discrimination in 2-D imaging.

  4. Lung Regeneration: Endogenous and Exogenous Stem Cell Mediated Therapeutic Approaches

    PubMed Central

    Akram, Khondoker M.; Patel, Neil; Spiteri, Monica A.; Forsyth, Nicholas R.

    2016-01-01

    The tissue turnover of unperturbed adult lung is remarkably slow. However, after injury or insult, a specialised group of facultative lung progenitors become activated to replenish damaged tissue through a reparative process called regeneration. Disruption in this process results in healing by fibrosis causing aberrant lung remodelling and organ dysfunction. Post-insult failure of regeneration leads to various incurable lung diseases including chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis. Therefore, identification of true endogenous lung progenitors/stem cells, and their regenerative pathway are crucial for next-generation therapeutic development. Recent studies provide exciting and novel insights into postnatal lung development and post-injury lung regeneration by native lung progenitors. Furthermore, exogenous application of bone marrow stem cells, embryonic stem cells and inducible pluripotent stem cells (iPSC) show evidences of their regenerative capacity in the repair of injured and diseased lungs. With the advent of modern tissue engineering techniques, whole lung regeneration in the lab using de-cellularised tissue scaffold and stem cells is now becoming reality. In this review, we will highlight the advancement of our understanding in lung regeneration and development of stem cell mediated therapeutic strategies in combating incurable lung diseases. PMID:26797607

  5. Omori Law After Exogenous Shocks on Supplier-Customer Network

    NASA Astrophysics Data System (ADS)

    Fujiwara, Yoshi

    We study the relaxation process of a supplier-customer network after mass destruction due to two giant earthquakes, Kobe 1995 and East Japan 2011, by investigating the number of chained failures. Firstly, a mass destruction and intervention of business activities in the damaged areas can be considered as a main shock. The exogenous shock was propagated on the supplier-customer network deteriorating financial states of other firms, even if they are not located in geographical neighbors. To quantify such aftershocks, we use chained failures on the network assuming that they indicate the trace of propagation of shocks. We show that the number of chained failures in its temporal change obeys an Omori-law, a power-law relaxation. This finding implies that the relaxation is much more sluggish than one would naively expect, and that it might be possible to estimate the extent and duration of aftershocks by using the empirical law. Several issues are discussed including the origin of the long-time relaxation.

  6. Endogenous or exogenous origin of vaginal candidiasis in Polish women?

    PubMed

    Mnichowska-Polanowskai, Magdalena; Wojciechowska-Koszko, Iwona; Klimowicz, Bogumia; Szymaniak, Ludmia; Krasnodebska-Szponder, Barbara; Szych, Zbigniew; Giedrys-Kalemba, Stefania

    2013-01-01

    Vaginal candidiasis is a common problem of clinical practice. Many studies have been conducted to explain its origin but only a few have included Polish women. The aim of the study was to determine the prevalence and similarity of oral, anal and vaginal Candida albicans strains isolated from Polish women with vaginal candidiasis. The study involved 20 from 37 recruited women. Swab samples were collected from their vagina, anus, and oral cavity at two-month intervals. All the women were treated with nystatin. Yeast were recovered and identified by the germ-tube test, API /Vitek system, typed by API ZYM and RAPD-PCR. Chi-square test was used to analyze the data. A total of 170 Candida albicans isolates were recovered from 180 samples collected 3 times from 3 sites of 20 women. Positive yeast vaginal cultures were found in all patients before administration of nystatin. Vaginal yeast recovery rate was decreased statistically significant in both follow-up visits (p= 0.001; p= 0.003). The same and different genotypes/biotypes were found concomitantly in a few body sites and/ or repeatedly at time interval from the same body site. The results support the concept of dynamic exchange of yeast within one woman and endogenous or exogenous origin of vaginal candidiasis.

  7. Exogenous delta⁹-tetrahydrocannabinol influences circulating endogenous cannabinoids in humans.

    PubMed

    Walter, Carmen; Ferreirós, Nerea; Bishay, Philipp; Geisslinger, Gerd; Tegeder, Irmgard; Lötsch, Jörn

    2013-10-01

    Delta⁹-tetrahydrocannabinol (THC) competes with the endogenous cannabinoids arachidonoyl ethanolamide (anandamide) and 2-arachidonoyl glycerol (2-AG) at cannabinoid receptors. This may cause adaptive changes in the endocannabinoid signaling cascade with possible consequences for the biological functions of the endocannabinoid system. We show that administration of a single oral dose of 20 mg THC to 30 healthy volunteers resulted in higher circulating concentrations of anandamide, 2-AG, palmitoyl ethanolamide, and oleoylethanolamide at 2 and 3 hours after administration as compared with placebo. At 2 hours after THC administration, changes in oleoylethanolamide plasma concentrations from baseline were linearly related to the THC plasma concentrations. In rats, treatment with the CB₁/CB₂ agonist WIN 55,212 also increased plasma endocannabinoid concentrations. However, this was associated with a decrease of ethanolamide endocannabinoids in specific brain regions including spinal cord, cortex, and hypothalamus; whereas 2-arachidonoyl glycerol increased in the cortex. Thus, administration of THC to human volunteers influenced the concentrations of circulating endocannabinoids, which was mimicked by WIN-55,212 in rats, suggesting that exogenous cannabinoids may lead to changes in the endocannabinoid system that can be detected in plasma.

  8. Tracing exogenous Gd and its effects in single Chang cells

    NASA Astrophysics Data System (ADS)

    Altissimo, Matteo; Pascolo, Lorella; Delfino, Riccarda; Salome, Murielle; Lorusso, Vito

    2010-07-01

    X-ray fluorescence (XRF) is rapidly becoming one of the tools of choice in tracing the presence of both endogenous and exogenous chemical elements in biological samples. The sub-micron spatial resolution routinely obtainable at multi-keV energies at third generation light sources, combined with the high brilliance of the photon beam, allows mapping the presence of biologically relevant elements at sub-cell resolution by means of their fluorescent signature. The fluorescent signal also lends itself for a semi-quantitative analysis of the elements composing the specimen. In this work we employed synchrotron-based XRF to analyze two lines of cultured Chang cells. One of them was treated with a Gd-containing magnetic resonance imaging (MRI) contrast agents (CA), and the other was left untreated for control purposes. The experiments highlighted a peri-nuclear distribution of Gd inside the cells, as well as a distinct variation in the distribution and concentration of several elements (P, S, Cl, K, Ca and Fe), with respect to the control line.

  9. Acquisition of exogenous haem is essential for tick reproduction

    PubMed Central

    Perner, Jan; Sobotka, Roman; Sima, Radek; Konvickova, Jitka; Sojka, Daniel; de Oliveira, Pedro Lagerblad; Hajdusek, Ondrej; Kopacek, Petr

    2016-01-01

    Haem and iron homeostasis in most eukaryotic cells is based on a balanced flux between haem biosynthesis and haem oxygenase-mediated degradation. Unlike most eukaryotes, ticks possess an incomplete haem biosynthetic pathway and, together with other (non-haematophagous) mites, lack a gene encoding haem oxygenase. We demonstrated, by membrane feeding, that ticks do not acquire bioavailable iron from haemoglobin-derived haem. However, ticks require dietary haemoglobin as an exogenous source of haem since, feeding with haemoglobin-depleted serum led to aborted embryogenesis. Supplementation of serum with haemoglobin fully restored egg fertility. Surprisingly, haemoglobin could be completely substituted by serum proteins for the provision of amino-acids in vitellogenesis. Acquired haem is distributed by haemolymph carrier protein(s) and sequestered by vitellins in the developing oocytes. This work extends, substantially, current knowledge of haem auxotrophy in ticks and underscores the importance of haem and iron metabolism as rational targets for anti-tick interventions. DOI: http://dx.doi.org/10.7554/eLife.12318.001 PMID:26949258

  10. Exogenous application of glycinebetaine increases chilling tolerance in tomato plants.

    PubMed

    Park, Eung-Jun; Jeknic, Zoran; Chen, Tony H H

    2006-06-01

    Tomato (Lycopersicon esculentum Mill. cv. Moneymaker) plants are chilling sensitive, and do not naturally accumulate glycinebetaine (GB), a metabolite that functions as a stress protectant. We reported previously that exogenous GB application enhanced chilling tolerance in tomato. To understand its protective role better, we have further evaluated various parameters associated with improved tolerance. Although its effect was most pronounced in younger plants, this benefit was diminished 1 week after GB application. When administered by foliar spray, GB was readily taken up and translocated to various organs, with the highest levels being measured in meristematic tissues, including the shoot apices and flower buds. In leaves, the majority of endogenous GB was found in the cytosol; only 0.6-22.0% of the total leaf GB was localized in chloroplasts. Immediately after GB application, levels of H(2)O(2), catalase activity and expression of the catalase gene (CAT1) were all higher in GB-treated than in control plants. One day after exposure to chilling stress, the treated plants had significantly greater catalase activity and CAT1 expression, although their H(2)O(2) levels remained unchanged. During the following 2 d of this chilling treatment, GB-treated plants maintained lower H(2)O(2) levels but had higher catalase activity than the controls. These results suggest that, in addition to protecting macromolecules and membranes directly, GB-enhanced chilling tolerance may involve the induction of H(2)O(2)-mediated antioxidant mechanisms, e.g. enhanced catalase expression and catalase activity.

  11. Exogenous plant hormones and cyclotide expression in Viola uliginosa (Violaceae).

    PubMed

    Slazak, Blazej; Jacobsson, Erik; Kuta, Elżbieta; Göransson, Ulf

    2015-09-01

    Plants from Violaceae produce cyclotides, peptides characterized by a circular peptide backbone and a cystine knot. This signature motif gives stability that can harness a wide spectrum of biological activities, with implications in plant defense and with applications in medicine and biotechnology. In the current work, cyclotide expressing in vitro cultures were established from Viola uliginosa. These cultures are useful models for studying biosynthesis of cyclotides and can also be used in their production. The cyclotide expression pattern is shown to be dependent on exogenous plant growth regulators, both on peptide and gene expression levels. The highest yields of cyclotides were obtained on media containing only a cytokinin and were correlated with storage material accumulation. Exposure to auxins decreased cyclotide production and caused shifting of the biosynthesis pattern to root specific cyclotides. The response to stimuli in terms of cyclotide expression pattern appears to be developmental, and related to polar auxin transportation and the auxin/cytokinin ratio regulating tissue differentiation. By the use of whole transcriptome shotgun sequencing (WTSS) and peptidomics, 20 cyclotide sequences from V. uliginosa (including 12 new) and 12 complete precursor proteins could be identified. The most abundant cyclotides were cycloviolacin O3 (CyO3), CyO8 and CyO13. A suspension culture was obtained that grew exponentially with a doubling time of approximately 3 days. After ten days of growth, the culture provided a yield of more than 4 mg CyO13 per gram dry mass.

  12. Exogenous attention during perceptual group formation and dissolution.

    PubMed

    Gonen, Fahrettin F; Ogmen, Haluk

    2017-02-01

    Under natural viewing conditions, a large amount of information reaches our senses, and the visual system uses attention and perceptual grouping to reduce the complexity of stimuli in order to make real-time perception possible. Prior studies have shown that attention and perceptual grouping operate in synergy; exogenous attention is deployed not only to the cued item, but also to the entire group. Here, we investigated how attention and perceptual grouping operate during the formation and dissolution of groups. Our results showed that reaction times are higher in the presence of perceptual groups than they are for ungrouped stimuli. On the other hand, attentional benefits of perceptual grouping were observed during both the formation and the dissolution of groups. The dynamics were similar during group formation and dissolution, showing a gradual effect that takes approximately half a second to reach its maximum level. In the case of group dissolution, the attentional benefits persisted for about a quarter of a second after dissolution of the group. Taken together, our results reveal the dynamics of how attention and grouping work in synergy during the transient period when groups form or dissolve.

  13. Dynamic structural transformations of coordination supramolecular systems upon exogenous stimulation.

    PubMed

    Li, Cheng-Peng; Chen, Jing; Liu, Chun-Sen; Du, Miao

    2015-02-18

    Reactions in the solid state, especially single-crystal-to-single-crystal (SC-SC) transformations, provide an appealing pathway to obtain target crystalline materials with modified properties via a solvent-free green chemistry approach. This feature article focuses on the progress to date in the context of coordination supramolecular systems (CSSs), especially coordination polymers (CPs) or metal-organic frameworks (MOFs), which show interesting dynamic natures upon exposure to various exogenous stimuli, including concentration, temperature, light and mechanical force, as well as their synergic effect. In essence, dynamic CSSs normally possess crucial crystalline-reactive characteristics: (i) metal ions or clusters with unstable or metastable electronic configurations and coordination geometries; (ii) organic ligands bearing physicochemically active functional groups for subsequent reactions; (iii) polymeric networks of high flexibility for structural bending, rotation, swelling, or shrinking; (iv) guest moieties to be freely exchanged or eliminated by varying the environmental conditions. The significant changes in catalytic, sorption, magnetic, or luminescent properties accompanied by the structural transformations will also be discussed, which reveal the proof-of-concept thereof in designing new functional crystalline materials.

  14. Lung Regeneration: Endogenous and Exogenous Stem Cell Mediated Therapeutic Approaches.

    PubMed

    Akram, Khondoker M; Patel, Neil; Spiteri, Monica A; Forsyth, Nicholas R

    2016-01-19

    The tissue turnover of unperturbed adult lung is remarkably slow. However, after injury or insult, a specialised group of facultative lung progenitors become activated to replenish damaged tissue through a reparative process called regeneration. Disruption in this process results in healing by fibrosis causing aberrant lung remodelling and organ dysfunction. Post-insult failure of regeneration leads to various incurable lung diseases including chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis. Therefore, identification of true endogenous lung progenitors/stem cells, and their regenerative pathway are crucial for next-generation therapeutic development. Recent studies provide exciting and novel insights into postnatal lung development and post-injury lung regeneration by native lung progenitors. Furthermore, exogenous application of bone marrow stem cells, embryonic stem cells and inducible pluripotent stem cells (iPSC) show evidences of their regenerative capacity in the repair of injured and diseased lungs. With the advent of modern tissue engineering techniques, whole lung regeneration in the lab using de-cellularised tissue scaffold and stem cells is now becoming reality. In this review, we will highlight the advancement of our understanding in lung regeneration and development of stem cell mediated therapeutic strategies in combating incurable lung diseases.

  15. The tonsillar immune system: its response to exogenous antigens.

    PubMed

    Mitani, T; Tomoda, K; Maeda, N; Yamashita, T; Kumazawa, T

    1990-01-01

    The palatine tonsil is the only lymphoid organ directly exposed to the outside environment. This characteristic anatomical feature appears to be immunologically significant with the defence activity primarily directed against exogenous antigens. However, the palatine tonsil is also often the site of secondary diseases, such as focal infections. This study investigated how the tonsil responds to horseradish peroxidase (HRP) dropped into the crypts and the effects of this response on the regional lymph node and the kidney as a distant organ. HRP entered through the microcrypts was phagocytosed by macrophages, gathered mostly around the vessels and emigrated to the regional lymph nodes. Anti-HRP antibody-producing cells were observed not only in the tonsil but also in the regional lymph node. In this long-term study with repeated immunization, fusion of the epithelial foot process and reduction of the anionic charge in the glomerulus were often found electron microscopically. This investigation suggests that the tonsil has important roles in the defence activity in relation to the general immune system; otherwise it becomes a primary site for focal infections.

  16. Method for collecting mouse milk without exogenous oxytocin stimulation.

    PubMed

    Muranishi, Yuki; Parry, Laurent; Averous, Julien; Terrisse, Anne; Maurin, Anne-Catherine; Chaveroux, Cédric; Mesclon, Florent; Carraro, Valérie; Bruhat, Alain; Fafournoux, Pierre; Jousse, Céline

    2016-01-01

    It has been reported that breast-feeding more than 6 months strongly decreases the risk of allergy, diabetes, obesity, and hypertension in humans. In order to understand the mechanisms responsible for this benefit, it is important to evaluate precisely the composition of maternal milk, especially in response to environmental cues. Mouse models offer a unique opportunity to study the impact of maternal milk composition on the development and health of offspring. Oxytocin injection of the dam is usually used to stimulate milk ejection; however, exogenous oxytocin might have deleterious effects under some experimental conditions by modifying milk content as well as the physiology and behavior of the dam. Taking advantage of the natural stimulation of the mammary gland that occurs after the reunion of a dam that has been separated from her pups, we developed a new procedure to collect mouse milk without the injection of oxytocin. This method is easy to use, low-cost ,and non-invasive. Moreover, it provides a sufficient amount of milk for use in a wide range of biological analyses.

  17. Endogenous and exogenous control of gametogenesis and spawning in echinoderms.

    PubMed

    Mercier, Annie; Hamel, Jean-François

    2009-01-01

    Most echinoderms display seasonal or other temporal cycles of reproduction that presumably result from the complex interplay of endogenous and exogenous signals. Various environmental, chemical and hormonal factors, acting directly or indirectly, individually or in combination, have been proposed to cue, favour or modulate a suite of reproductive functions from the onset of gametogenesis to gamete release. From as early as the nineteenth century, an astonishing array of studies has been published on topics related to the control of reproduction in echinoderms, ranging from fortuitous behavioural observations to complex experimental demonstrations and molecular analyses. Although the exact pathways involved in the perception of external signals and their transduction into coordinated spawning events remain obscure for most species, significant advances have been made that shed new light on the information gathered over decades of research. By compiling the existing literature (over 1000 references), interpreting the main results, critically assessing the methodologies used and reviewing the emerging hypotheses, we endeavour to draw a clearer picture of the existing knowledge and to provide a framework for future investigation of the mechanisms that underlie reproductive strategies in echinoderms and, by extension, in other marine invertebrates.

  18. Exogenous gangliosides may affect methylation mechanisms in neuronal cell cultures

    SciTech Connect

    Ferret, B.; Hubsch, A.; Dreyfus, H.; Massarelli, R. )

    1991-02-01

    Primary neurons in culture from chick embryo cerebral hemispheres were treated with a mixture of gangliosides added to the growth medium (final concentration: 10(-5)M and 10(-8)M) from the 3rd to the 6th day in vitro. Under these conditions methylation processes measured with (3H) and (35S) methionine and (3H)ethanolamine as precursors showed an increased methylation of (3H)ethanolamine containing phospholipids, a correspondent increased conversion of these compounds to (3H)choline containing phospholipids, and a general increased methylation of trichloroacetic acid precipitable macromolecules containing labeled methionine. A small increase in protein synthesis was observed after incubation of neurons with (3H)- and (35S)methionine. This was confirmed after electrophoretic separation of a protein extract with increased 3H- and 35S-labeling in protein bands with moecular weights between 50 and 60 KDaltons. A protein band of about 55 KDaltons appeared to be preferentially labelled when (3H) methionine was the precursor. The treatment with gangliosides increased the incorporation of (methyl-3H) label after incubation of neurons with (3H) methionine, into total DNA and decreased that of total RNA. The treatment of neurons in culture with exogenous gangliosides hence affects differently methylation processes, a finding which may confirm the involvement of gangliosides on the intracellular mediation of neuronal information mechanisms.

  19. Exogenous specific fluorescence marker location reconstruction using surface fluorescence imaging

    NASA Astrophysics Data System (ADS)

    Avital, Garashi; Gannot, Israel; Chernomordik, Victor V.; Gannot, Gallya; Gandjbakhche, Amir H.

    2003-07-01

    Diseased tissue may be specifically marked by an exogenous fluorescent marker and then, following laser activation of the marker, optically and non-invasively detected through fluorescence imaging. Interaction of a fluorophore, conjugated to an appropriate antibody, with the antigen expressed by the diseased tissue, can indicate the presence of a specific disease. Using an optical detection system and a reconstruction algorithm, we were able to determine the fluorophore"s position in the tissue. We present 3D reconstructions of the location of a fluorescent marker, FITC, in the tongues of mice. One group of BALB/c mice was injected with squamous cell carcinoma (SqCC) cell line to the tongue, while another group served as the control. After tumor development, the mice"s tongues were injected with FITC conjugated to anti-CD3 and anti-CD 19 antibodies. An Argon laser excited the marker at 488 nm while a high precision fluorescent camera collected the emitted fluorescence. Measurements were performed with the fluorescent marker embedded at various simulated depths. The simulation was performed using agarose-based gel slabs applied to the tongue as tissue-like phantoms. A biopsy was taken from every mouse after the procedure and the excised tissue was histologically evaluated. We reconstruct the fluorescent marker"s location in 3D using an algorithm based on the random walk theory.

  20. Germline transmission of exogenous genes in the chicken.

    PubMed

    Bosselman, R A; Hsu, R Y; Boggs, T; Hu, S; Bruszewski, J; Ou, S; Kozar, L; Martin, F; Green, C; Jacobsen, F

    1989-01-27

    Difficulties associated with in vitro manipulation and culture of the early chicken embryo have restricted generation of transgenic chickens to approaches that use replication-competent retroviruses. The need to produce transgenic chickens in the absence of replicating virus prompted development of a new method of gene transfer into the chicken. Microinjection of the replication-defective reticuloendotheliosis virus (REV) vector ME111 beneath unincubated chicken embryo blastoderms results in infection of germline stem cells. This vector contains genetic information exogenous to the chicken genome, including both the herpes simplex virus type 1 thymidine kinase gene and the Tn5 neomycin phosphotransferase gene. About 8 percent of male birds hatched from injected embryos contained vector DNA in their semen. All four positive males tested passed vector sequences onto their progeny. Analysis of G1 offspring showed that gonads of G0 male birds were mosaic with respect to insertion of vector provirus. Thus, primordial germ cells present in the unincubated chicken embryo blastoderm are susceptible to infection by defective REV vectors.

  1. SAR11 marine bacteria require exogenous reduced sulphur for growth.

    PubMed

    Tripp, H James; Kitner, Joshua B; Schwalbach, Michael S; Dacey, John W H; Wilhelm, Larry J; Giovannoni, Stephen J

    2008-04-10

    Sulphur is a universally required cell nutrient found in two amino acids and other small organic molecules. All aerobic marine bacteria are known to use assimilatory sulphate reduction to supply sulphur for biosynthesis, although many can assimilate sulphur from organic compounds that contain reduced sulphur atoms. An analysis of three complete 'Candidatus Pelagibacter ubique' genomes, and public ocean metagenomic data sets, suggested that members of the ubiquitous and abundant SAR11 alphaproteobacterial clade are deficient in assimilatory sulphate reduction genes. Here we show that SAR11 requires exogenous sources of reduced sulphur, such as methionine or 3-dimethylsulphoniopropionate (DMSP) for growth. Titrations of the algal osmolyte DMSP in seawater medium containing all other macronutrients in excess showed that 1.5 x 10(8) SAR11 cells are produced per nanomole of DMSP. Although it has been shown that other marine alphaproteobacteria use sulphur from DMSP in preference to sulphate, our results indicate that 'Cand. P. ubique' relies exclusively on reduced sulphur compounds that originate from other plankton.

  2. Exogenous ethylene influences flower opening of cut roses (Rosa hybrida) by regulating the genes encoding ethylene biosynthesis enzymes.

    PubMed

    Ma, Nan; Cai, Lei; Lu, Wangjin; Tan, Hui; Gao, Junping

    2005-10-01

    The purpose of this paper is to investigate the differential responses of flower opening to ethylene in two cut rose cultivars, 'Samantha', whose opening process is promoted, and 'Kardinal', whose opening process is inhibited by ethylene. Ethylene production and 1-aminocyclopropane-1-carboxylate (ACC) synthase and oxidase activities were determined first. After ethylene treatment, ethylene production, ACC synthase (ACS) and ACC oxidase (ACO) activities in petals increased and peaked at the earlier stage (stage 3) in 'Samantha', and they were much more dramatically enhanced and peaked at the later stage (stage 4) in 'Kardinal' than control during vasing. cDNA fragments of three Rh-ACSs and one Rh-ACO genes were cloned and designated as Rh-ACS1, Rh-ACS2, Rh-ACS3 and Rh-ACO1 respectively. Northern blotting analysis revealed that, among three genes of ACS, ethylene-in- duced expression patterns of Rh-ACS3 gene corresponded to ACS activity and ethylene production in both cultivars. A more dramatic accumulation of Rh-ACS3 mRNA was induced by ethylene in 'Kardinal' than that of 'Samantha'. As an ethylene action inhibitor, STS at concentration of 0.2 mmol/L generally inhibited the expression of Rh-ACSs and Rh-ACO in both cultivars, although it induced the expression of Rh-ACS3 transiently in 'Kardinal'. Our results suggests that 'Kardinal' is more sensitive to ethylene than 'Samantha'; and the changes of Rh-ACS3 expression caused by ethylene might be related to the acceleration of flower opening in 'Samantha' and the inhibition in 'Kardinal'. Additional results indicated that three Rh-ACSs genes were differentially associated with flower opening and senescence as well as wounding

  3. Industrial Enzymes and Biocatalysis

    NASA Astrophysics Data System (ADS)

    McAuliffe, Joseph C.; Aehle, Wolfgang; Whited, Gregory M.; Ward, Donald E.

    All life processes are the result of enzyme activity. In fact, life itself, whether plant or animal, involves a complex network of enzymatic reactions. An enzyme is a protein that is synthesized in a living cell. It catalyzes a thermodynamically possible reaction so that the rate of the reaction is compatible with the numerous biochemical processes essential for the growth and maintenance of a cell. The synthesis of an enzyme thus is under tight metabolic regulations and controls that can be genetically or environmentally manipulated sometimes to cause the overproduction of an enzyme by the cell. An enzyme, like chemical catalysts, in no way modifies the equilibrium constant or the free energy change of a reaction.

  4. Exogenous Spermidine Alleviates Low Temperature Injury in Mung Bean (Vigna radiata L.) Seedlings by Modulating Ascorbate-Glutathione and Glyoxalase Pathway

    PubMed Central

    Nahar, Kamrun; Hasanuzzaman, Mirza; Alam, Md. Mahabub; Fujita, Masayuki

    2015-01-01

    The role of exogenous spermidine (Spd) in alleviating low temperature (LT) stress in mung bean (Vigna radiata L. cv. BARI Mung-3) seedlings has been investigated. Low temperature stress modulated the non-enzymatic and enzymatic components of ascorbate-glutathione (AsA-GSH) cycle, increased H2O2 content and lipid peroxidation, which indicate oxidative damage of seedlings. Low temperature reduced the leaf relative water content (RWC) and destroyed leaf chlorophyll, which inhibited seedlings growth. Exogenous pretreatment of Spd in LT-affected seedlings significantly increased the contents of non-enzymatic antioxidants of AsA-GSH cycle, which include AsA and GSH. Exogenous Spd decreased dehydroascorbate (DHA), increased AsA/DHA ratio, decreased glutathione disulfide (GSSG) and increased GSH/GSSG ratio under LT stress. Activities of AsA-GSH cycle enzymes such as ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) increased after Spd pretreatment in LT affected seedlings. Thus, the oxidative stress was reduced. Protective effects of Spd are also reflected from reduction of methylglyoxal (MG) toxicity by improving glyoxalase cycle components, and by maintaining osmoregulation, water status and improved seedlings growth. The present study reveals the vital roles of AsA-GSH and glyoxalase cycle in alleviating LT injury. PMID:26694373

  5. Exogenous Spermidine Alleviates Low Temperature Injury in Mung Bean (Vigna radiata L.) Seedlings by Modulating Ascorbate-Glutathione and Glyoxalase Pathway.

    PubMed

    Nahar, Kamrun; Hasanuzzaman, Mirza; Alam, Md Mahabub; Fujita, Masayuki

    2015-12-17

    The role of exogenous spermidine (Spd) in alleviating low temperature (LT) stress in mung bean (Vigna radiata L. cv. BARI Mung-3) seedlings has been investigated. Low temperature stress modulated the non-enzymatic and enzymatic components of ascorbate-glutathione (AsA-GSH) cycle, increased H₂O₂ content and lipid peroxidation, which indicate oxidative damage of seedlings. Low temperature reduced the leaf relative water content (RWC) and destroyed leaf chlorophyll, which inhibited seedlings growth. Exogenous pretreatment of Spd in LT-affected seedlings significantly increased the contents of non-enzymatic antioxidants of AsA-GSH cycle, which include AsA and GSH. Exogenous Spd decreased dehydroascorbate (DHA), increased AsA/DHA ratio, decreased glutathione disulfide (GSSG) and increased GSH/GSSG ratio under LT stress. Activities of AsA-GSH cycle enzymes such as ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) increased after Spd pretreatment in LT affected seedlings. Thus, the oxidative stress was reduced. Protective effects of Spd are also reflected from reduction of methylglyoxal (MG) toxicity by improving glyoxalase cycle components, and by maintaining osmoregulation, water status and improved seedlings growth. The present study reveals the vital roles of AsA-GSH and glyoxalase cycle in alleviating LT injury.

  6. Recent advances in research on enzymes for poultry diets.

    PubMed

    Slominski, B A

    2011-09-01

    Exogenous enzymes have been used extensively in the diets of poultry to improve productive performance. Further research, however, is needed to evaluate the efficacy of enzyme use and for the expansion of the use of enzymes to accommodate the wide array of dietary constituents used in poultry feeding programs. The use of effective phytase preparations to improve bird performance and to reduce environmental P pollution has shown less than optimum results, partly due to the potential negative effects of nontargeted dietary fiber components and to confounding influence of inadequate knowledge of accurate P requirements and the tendency for the use of excessive safety margins in diet formulation. Targeting specific nonstarch polysaccharides (NSP) of wheat, barley, or rye with enzyme preparations has proven effective for diets based on these cereals but not for corn- and soybean meal-based diets, primarily due to the differences in constituent NSP. The increased use of whole flaxseed in poultry diets represents an additional research area for effective enzyme development to alleviate potential negative effects of constituent NSP components. Such challenges of the enzyme development process and their outcomes are presented in this publication.

  7. Structural comparison of chromosomal and exogenous dihydrofolate reductase from Staphylococcus aureus in complex with the potent inhibitor trimethoprim

    SciTech Connect

    Heaslet, Holly; Harris, Melissa; Fahnoe, Kelly; Sarver, Ronald; Putz, Henry; Chang, Jeanne; Subramanyam, Chakrapani; Barreiro, Gabriela; Miller, J. Richard; Pfizer

    2010-09-02

    Dihydrofolate reductase (DHFR) is the enzyme responsible for the NADPH-dependent reduction of 5,6-dihydrofolate to 5,6,7,8-tetrahydrofolate, an essential cofactor in the synthesis of purines, thymidylate, methionine, and other key metabolites. Because of its importance in multiple cellular functions, DHFR has been the subject of much research targeting the enzyme with anticancer, antibacterial, and antimicrobial agents. Clinically used compounds targeting DHFR include methotrexate for the treatment of cancer and diaminopyrimidines (DAPs) such as trimethoprim (TMP) for the treatment of bacterial infections. DAP inhibitors of DHFR have been used clinically for >30 years and resistance to these agents has become widespread. Methicillin-resistant Staphylococcus aureus (MRSA), the causative agent of many serious nosocomial and community acquired infections, and other gram-positive organisms can show resistance to DAPs through mutation of the chromosomal gene or acquisition of an alternative DHFR termed 'S1 DHFR.' To develop new therapies for health threats such as MRSA, it is important to understand the molecular basis of DAP resistance. Here, we report the crystal structure of the wild-type chromosomal DHFR from S. aureus in complex with NADPH and TMP. We have also solved the structure of the exogenous, TMP resistant S1 DHFR, apo and in complex with TMP. The structural and thermodynamic data point to important molecular differences between the two enzymes that lead to dramatically reduced affinity of DAPs to S1 DHFR. These differences in enzyme binding affinity translate into reduced antibacterial activity against strains of S. aureus that express S1 DHFR.

  8. Cotton cellulose: enzyme adsorption and enzymic hydrolysis

    SciTech Connect

    Beltrame, P.L.; Carniti, P.; Focher, B.; Marzetti, A.; Cattaneo, M.

    1982-01-01

    The adsorption of a crude cellulase complex from Trichoderma viride on variously pretreated cotton cellulose samples was studied in the framework of the Langmuir approach at 2-8 degrees. The saturation amount of adsorbed enzyme was related to the susceptibility of the substrates to hydrolysis. In every case the adsorption process was faster by 2-3 orders of magnitude than the hydrolysis step to give end products. For ZnCl/sub 2/-treated cotton cellulose the Langmuir parameters correlated fairly well with the value of the Michaelis constant, measured for its enzymic hydrolysis, and the adsorptive complex was indistinguishable from the complex of the Michaelis-Menten model for the hydrolysis.

  9. Targetable fluorescent probe for monitoring exogenous and endogenous NO in mitochondria of living cells.

    PubMed

    Yu, Haibo; Zhang, Xinfu; Xiao, Yi; Zou, Wei; Wang, Liping; Jin, Liji

    2013-08-06

    Nitric oxide (NO) is a ubiquitous cellular messenger molecule in the cardiovascular, nervous, and immune systems. Mitochondrion is the main area where endogenous NO is synthesized by inducible NOS enzymes in mammalian cells. Thus, real-time monitoring NO in mitochondria is very meaningful for NO chemical biology. Although a variety of fluorescent probes for NO have been successfully developed, they are not suited for detecting mitochondrial NO because none of them can specifically localize in mitochondria. Herein, Mito-Rh-NO, the first mitochondria-targetable "turn-on" fluorescent probe for NO, has been developed through attaching a triphenylphosphonium to a rhodamine spirolactam. The characteristics of this probe are as following: (1) Mito-Rh-NO exhibits high sensitivity toward NO. In solution, Mito-Rh-NO responds to NO by significant fluorescence enhancement up to 60-fold, and its NO detection limit is as low as 4.0 nM. (2) The NO sensing of Mito-Rh-NO is highly selective, which will not interfere with the other reactive oxygen and nitrogen species. (3) Mito-Rh-NO has a low cytotoxic effect: after being treated with 10 μM Mito-Rh-NO for 24 h, the survival rate is higher than 90%. (4) Mito-Rh-NO specifically localizing in mitochondria: colocalization experiment of Mito-Rh-NO and Rh 123, a typical mitotracker, shows the merged fluorescent microcopy image with a high Pearson's colocalization coefficient 0.92 and overlap coefficient 0.99. (5) Mito-Rh-NO demonstrates high applicability for real-time monitoring of mitochondrial NO in live cells. Both the exogenous NO released by the donor NOC13 and endogenous NO generated in cells under stimulation have been visualized under confocal microscopy.

  10. Exogenous Melatonin Improves Antioxidant Defense in Cucumber Seeds (Cucumis sativus L.) Germinated under Chilling Stress

    PubMed Central

    Marta, Bałabusta; Szafrańska, Katarzyna; Posmyk, Małgorzata M.

    2016-01-01

    The relationship between exogenous melatonin applied into cucumber seeds during osmopriming and modifications of their antioxidant defense was studied. Accumulation of hydrogen peroxide, antioxidant enzyme activities and glutathione pool were investigated in embryonic axes isolated from the control, osmoprimed, and osmoprimed with melatonin seeds. Germinating cucumber seeds are very sensitive to chilling. Temperature 10°C causes oxidative stress in young seedlings. Seed pre-treatment with melatonin seemed to limit H2O2 accumulation during germination under optimal condition as well as during chilling stress and recovery period. Melatonin affected superoxide dismutase (SOD) activity and its isoforms during stress and recovery period but did not influence CAT and POX activities. Thus it is possible that in cucumber this indoleamine could act mostly as a direct H2O2 scavenger, but superoxide anion combat via SOD stimulation. The GSH/GSSG ratio is considered as an indirect determinant of oxidative stress. When the cells are exposed to oxidative stress GSSG is accumulated and the ratio of GSH to GSSG decreases. In our research pre-sowing melatonin application into the cucumber seeds caused high beneficial value of GSH/GSSG ratio that could be helpful for stress countering. Glutathione reductase (GSSG-R) activity in the axes isolated from these seeds was two fold higher than in those isolated from the control and from the osmoprimed without melatonin ones. Additional isoforms of GSSG-R in melatonin treated seeds were also observed. It explains high and effective GSH pool restoration in the seeds pre-treated with melatonin. We confirmed that melatonin could protect cucumber seeds and young seedlings against oxidative stress directly and indirectly detoxifying ROS, thereby plants grown better even in harmful environmental conditions. This work is the first that investigated on plant in vivo model and documented melatonin influence on redox state during seed germination

  11. Exogenous Melatonin Improves Antioxidant Defense in Cucumber Seeds (Cucumis sativus L.) Germinated under Chilling Stress.

    PubMed

    Marta, Bałabusta; Szafrańska, Katarzyna; Posmyk, Małgorzata M

    2016-01-01

    The relationship between exogenous melatonin applied into cucumber seeds during osmopriming and modifications of their antioxidant defense was studied. Accumulation of hydrogen peroxide, antioxidant enzyme activities and glutathione pool were investigated in embryonic axes isolated from the control, osmoprimed, and osmoprimed with melatonin seeds. Germinating cucumber seeds are very sensitive to chilling. Temperature 10°C causes oxidative stress in young seedlings. Seed pre-treatment with melatonin seemed to limit H2O2 accumulation during germination under optimal condition as well as during chilling stress and recovery period. Melatonin affected superoxide dismutase (SOD) activity and its isoforms during stress and recovery period but did not influence CAT and POX activities. Thus it is possible that in cucumber this indoleamine could act mostly as a direct H2O2 scavenger, but superoxide anion combat via SOD stimulation. The GSH/GSSG ratio is considered as an indirect determinant of oxidative stress. When the cells are exposed to oxidative stress GSSG is accumulated and the ratio of GSH to GSSG decreases. In our research pre-sowing melatonin application into the cucumber seeds caused high beneficial value of GSH/GSSG ratio that could be helpful for stress countering. Glutathione reductase (GSSG-R) activity in the axes isolated from these seeds was two fold higher than in those isolated from the control and from the osmoprimed without melatonin ones. Additional isoforms of GSSG-R in melatonin treated seeds were also observed. It explains high and effective GSH pool restoration in the seeds pre-treated with melatonin. We confirmed that melatonin could protect cucumber seeds and young seedlings against oxidative stress directly and indirectly detoxifying ROS, thereby plants grown better even in harmful environmental conditions. This work is the first that investigated on plant in vivo model and documented melatonin influence on redox state during seed germination

  12. [Synergistion mechanism of exogenous Ca2+ to SA-induced resistance to Botrytis cinerea in tomato].

    PubMed

    Li, Lin-lin; Li, Tian-lai; Jiang, Guo-bin; Jin, Hua; Zou, Ji-xiang

    2015-11-01

    In this study, we investigated the effect of exogenous calcium and salicylic acid (SA) on Botrytis cinerea resistance in tomato seedlings. We treated a tomato strain susceptible to Botrytis cinerea with foliar spraying of water, SA, SA+CaCl2 and SA+EGTA (Ca2+ chelating agent) for one to five days. During the treatment, leaves were collected to analyze the reactive oxygen species (ROS) content, phenylalanine ammonia lyase (PAL) activity, chintase and β-1,3-glucanase levels, and the expression of pathogenesis related protein 1, 2, 3 (PR1, PR2, PR3). Three days after infection, the disease index was 74.8 in control plants, and 46.9, 38.5 and 70.3 in SA, SA+Ca and SA+ EGTA treated plants, respectively. SA treatment significantly increased ROS leaf accumulation, and activities of PAL, chintase and β-1,3-glucanase. These values were further enhanced in SA+Ca treated plants, but decreased in SA+EGTA treated plants. Application of SA significantly increased the expression levels of PR1, PR2a and PR3b, which were further elevated by the combination treatment with Ca2+. These effects were counteracted by the combination treatment of SA and EGTA. The transcription levels of PR2b and PR3a were up-regulated by 1-2 folds, and PR1, 2a and 3b by 2-5 folds in SA- and SA+Ca-treated plants relative to control. These data suggested that application of Ca2+ could synergistically increase SA-induced resistance to B. cinerea. The resistance was associated with ROS accumulation, therefore the increase in resistance might be through ROS ability to increase the activity of defense-related enzymes and expression levels of PR1, PR2a and PR3b.

  13. Exogenous phosphorus inputs alter complexity of soil-dissolved organic carbon in agricultural riparian wetlands.

    PubMed

    Liu, Meng; Zhang, Zhijian; He, Qiang; Wang, Hang; Li, Xia; Schoer, Jonathan

    2014-01-01

    High-strengthened farmland fertilization leads to mass inputs of nutrients and elements to agricultural riparian wetlands. The dissolved organic carbon (DOC) of such wetland sediments is an important intermediate in global carbon (C) cycling due to its role in connecting soil C pools with atmospheric CO2. But the impact of phosphorus (P) on sediment DOC is still largely unknown, despite increasing investigations to emphasize P interception by riparian wetlands. Here, we simulated the temporal influences of exogenous P on sediment DOC of riparian wetlands by integrating gradient P loading at rates of 0%, 5%, 10%, 20%, 30%, and 60% relative to the initial total phosphorus content of the sediment with the purpose of illustrating the role of external P on the complexity of soil DOC in terms of its amount and composition. After incubating for nine months, a dramatic linear correlation between Olsen-P and fluorescent and ultraviolet spectral indices considered DOC skeleton was observed. Together with a more microbial-derived origin of DOC and a reduction of DOC aromaticity or humicity, the excitation-emission matrix had shown a blue shift reflecting a trend towards a simpler molecular structure of sediment DOC after P addition. Meanwhile, the content of soil DOC and its ratio with total organic carbon (TOC) were also increased by P loading, coupled with enhanced values of highly labile organic carbon and two C-related enzymes. While TOC and recalcitrant organic carbon decreased significantly. Such implications of DOC amounts and composition stimulated by external P loading may enhance its bioavailability, thereby inducing an accelerated effect on soil C cycling and a potential C loss in response to global climate change.

  14. Pretreatment of different biological matrices for exogenous testosterone analysis: a review.

    PubMed

    Pizzato, Edna Carolina; Filonzi, Marcelo; Rosa, Hemerson Silva da; de Bairros, André Valle

    2017-11-01

    The presence of exogenous testosterone has been monitored mainly in the urine and blood. However, other biological matrices such as hair, nail, and saliva samples can be used successfully for in vivo measurement. Chromatographic analysis requires pretreatment to obtain free testosterone and its metabolites. Among the pretreatment procedures, digestion, hydrolysis and solvolysis steps are conducted to reach the analytical purpose. Digestion assay is indicated for hair and nail samples. First, it is recommended to perform the decontamination step. After that, alkaline solution (NaOH), organic solvents and other reagents can be added to the samples and incubated under determined conditions for the digestion step. Hydrolysis assay is recommended to urine and blood samples. Acid hydrolysis cleaves conjugated testosterone and its metabolites using HCl or H2SO4 solution at appropriate time and temperature. However, there is formation of interferent compounds, degradation of dehydroepiandrosterone and decrease of peak resolution for epitestosterone. Enzymatic hydrolysis is an alternative technique able to promote free testosterone and its metabolites with low degradation. It is important to establish the best conditions according to the biological fluid and the amount of the sample. Sulfatase enzyme is recommended together with β-glucuronidase to cleave sulfoconjugate steroids. Solvolysis assay is similar to acid hydrolysis, but organic solvents are responsible to promote steroid deconjugation. Other approaches such as combination of different pretreatments, surface response or ultrasonic energy have been used to obtain the total of free steroids. So, the biological matrix defines the best procedure for pretreatment to achieve the analytical purpose, knowing its advantages and limitations.

  15. Chemotactic separation of enzymes.

    PubMed

    Dey, Krishna Kanti; Das, Sambeeta; Poyton, Matthew F; Sengupta, Samudra; Butler, Peter J; Cremer, Paul S; Sen, Ayusman

    2014-12-23

    We demonstrate a procedure for the separation of enzymes based on their chemotactic response toward an imposed substrate concentration gradient. The separation is observed within a two-inlet, five-outlet microfluidic network, designed to allow mixtures of active (ones that catalyze substrate turnover) and inactive (ones that do not catalyze substrate turnover) enzymes, labeled with different fluorophores, to flow through one of the inlets. Substrate solution prepared in phosphate buffer was introduced through the other inlet of the device at the same flow rate. The steady-state concentration profiles of the enzymes were obtained at specific positions within the outlets of the microchannel using fluorescence microscopy. In the presence of a substrate concentration gradient, active enzyme molecules migrated preferentially toward the substrate channel. The excess migration of the active enzyme molecules was quantified in terms of an enrichment coefficient. Experiments were carried out with different pairs of enzymes. Coupling the physics of laminar flow of liquid and molecular diffusion, multiphysics simulations were carried out to estimate the extent of the chemotactic separation. Our results show that, with appropriate microfluidic arrangement, molecular chemotaxis leads to spontaneous separation of active enzyme molecules from their inactive counterparts of similar charge and size.

  16. Replacing corn with pearl millet (raw and sprouted) with and without enzyme in chickens' diet.

    PubMed

    Afsharmanesh, M; Ghorbani, N; Mehdipour, Z

    2016-04-01

    An experiment was conducted to compare a commercial corn-soya bean meal diet with a pearl millet (raw and sprouted) diet containing less soya bean meal, alone or in combination with exogenous enzyme, on growth performance and ileal villus development of chicks. Two-hundred-and-forty-one-day-old male broilers (10/pen) were randomly allocated to one of the following dietary treatments: (i) a standard corn-soya bean meal control diet (CTL); (ii) a raw pearl millet-soya bean meal diet (PM); (iii) a sprouted pearl millet-soya bean meal diet (SPM); (iv) CTL + exogenous enzymes (CE); (v) PM + exogenous enzymes (PE); and (vi) SPM + exogenous enzymes (SPE) with four replicate pens/treatment. Body weight of birds at day 21 did not differ between those fed the CTL, and SPM and PE diets. In comparison with feeding broilers the CTL diet, feeding the PE and SPM diets caused significant decrease in feed intake, but with equivalent growth and feed efficiency. However, at day 21, feed conversion ratio did not differ between birds fed the CTL diet and those fed the PM, PE and SPM diets. At day 21, broilers fed the PM and PE diets had longer villi (p < 0.05) than those fed the CTL diet. At day 21, villi width was reduced (p < 0.05) by raw pearl millet supplementation than CTL diet. It is concluded that, in comparison with corn, broiler diets formulated with sprouted pearl millet or pearl millet with enzyme require less soya bean meal and can be used to improve growth performance traits and villus development.

  17. Effects of an exogenous xylanase gene expression on the growth of transgenic rice and the expression level of endogenous xylanase inhibitor gene RIXI.

    PubMed

    Weng, Xiaoyan; Huang, Yingying; Hou, Chunxiao; Jiang, Dean

    2013-01-15

    Xylanases have attracted considerable interest in recent years owing to their various applications in industry and agriculture. The use of transgenic plants to produce xylanases is a less expensive alternative to biotechnological programmes. The aim of this study was to elucidate whether introducing a foreign xylanase gene ATX into rice had any adverse effect on plant growth and development. A recombinant xylanase gene ATX was introduced into rice variety Zhonghua 11 through Agrobacterium-mediated transformation. The T₂ generation of transgenic rice was compared with the control (non-transgenic plants). Exogenous xylanase gene ATX was expressed in rice, and all examined transgenic lines exhibited xylanase activity. The transgenic lines (T₂, 'X1-3' and 'X2-5') appeared to grow and develop normally. There were no differences in net photosynthetic rate between transgenic rice lines ('X1-3' and 'X2-5') and wild type (WT) rice plants at the heading/flowering stage. Xylanases are key enzymes in the degradation of plant cell walls. Cell wall composition analysis showed that that there were no changes in cell wall polysaccharides in the root apex but some alterations in leaves in transgenic rice plants. The results also showed that the expression of exogenous xylanase gene ATX in rice would increase the expression of endogenous xylanase inhibitor gene RIXI, which could play a role in plant defence. Thus the stress resistance of transgenic rice plants might be improved. Exogenous xylanase gene ATX could be successfully expressed in rice, and the exogenous protein had no apparent harmful effects on growth and development in transgenic rice plants. Copyright © 2012 Society of Chemical Industry.

  18. Exogenic olivine on Vesta from Dawn Framing Camera color data

    NASA Astrophysics Data System (ADS)

    Nathues, Andreas; Hoffmann, Martin; Schäfer, Michael; Thangjam, Guneshwar; Le Corre, Lucille; Reddy, Vishnu; Christensen, Ulrich; Mengel, Kurt; Sierks, Holger; Vincent, Jean-Baptist; Cloutis, Edward A.; Russell, Christopher T.; Schäfer, Tanja; Gutierrez-Marques, Pablo; Hall, Ian; Ripken, Joachim; Büttner, Irene

    2015-09-01

    In this paper we present the results of a global survey of olivine-rich lithologies on (4) Vesta. We investigated Dawn Framing Camera (FC) High Altitude Mapping Orbit (HAMO) color cubes (∼60 m/pixel resolution) by using a method described in Thangjam et al. (Thangjam, G., Nathues, A., Mengel, K., Hoffmann, M., Schäfer, M., Reddy, V., Cloutis, E.A., Christensen, U., Sierks, H., Le Corre, L., Vincent, J.-B, Russell, C.T. [2014b]. Meteorit. Planet. Sci. arXiv:1408.4687 [astro-ph.EP]). In total we identified 15 impact craters exhibiting olivine-rich (>40 wt.% ol) outcrops on their inner walls, some showing olivine-rich material also in their ejecta and floors. Olivine-rich sites are concentrated in the Bellicia, Arruntia and Pomponia region on Vesta's northern hemisphere. From our multi-color and stratigraphic analysis, we conclude that most, if not all, of the olivine-rich material identified is of exogenic origin, i.e. remnants of A- or/and S-type projectiles. The olivine-rich lithologies in the north are possibly ejecta of the ∼90 km diameter Albana crater. We cannot draw a final conclusion on their relative stratigraphic succession, but it seems that the dark material (Nathues, A., Hoffmann, M., Cloutis, E.A., Schäfer, M., Reddy, V., Christensen, U., Sierks, H., Thangjam, G.S., Le Corre, L., Mengel, K., Vincent, J.-B., Russell, C.T., Prettyman, T., Schmedemann, N., Kneissl, T., Raymond, C., Gutierrez-Marques, P., Hall, I. Büttner, I. [2014b]. Icarus (239, 222-237)) and the olivine-rich lithologies are of a similar age. The origin of some potential olivine-rich sites in the Rheasilvia basin and at crater Portia are ambiguous, i.e. these are either of endogenic or exogenic origin. However, the small number and size of these sites led us to conclude that olivine-rich mantle material, containing more than 40 wt.% of olivine, is basically absent on the present surface of Vesta. In combination with recent impact models of Veneneia and Rheasilvia (Clenet, H., Jutzi

  19. The EBI enzyme portal.

    PubMed

    Alcántara, Rafael; Onwubiko, Joseph; Cao, Hong; Matos, Paula de; Cham, Jennifer A; Jacobsen, Jules; Holliday, Gemma L; Fischer, Julia D; Rahman, Syed Asad; Jassal, Bijay; Goujon, Mikael; Rowland, Francis; Velankar, Sameer; López, Rodrigo; Overington, John P; Kleywegt, Gerard J; Hermjakob, Henning; O'Donovan, Claire; Martín, María Jesús; Thornton, Janet M; Steinbeck, Christoph

    2013-01-01

    The availability of comprehensive information about enzymes plays an important role in answering questions relevant to interdisciplinary fields such as biochemistry, enzymology, biofuels, bioengineering and drug discovery. At the EMBL European Bioinformatics Institute, we have developed an enzyme portal (http://www.ebi.ac.uk/enzymeportal) to provide this wealth of information on enzymes from multiple in-house resources addressing particular data classes: protein sequence and structure, reactions, pathways and small molecules. The fact that these data reside in separate databases makes information discovery cumbersome. The main goal of the portal is to simplify this process for end users.

  20. Enzyme nanoband electrodes

    SciTech Connect

    Wang, J.; Naser, N. ); Renschler, C.L. )

    1993-07-01

    Enzyme nanoelectrodes have been constructed by immobilizing glucose oxidase, alcohol oxidase or tyrosinase onto ultrathin carbon films (of 35-50 nm thickness). The enzyme immobilization is accomplished via entrapment within electropolymerized poly(o-phenylenediamine) coatings. Cyclic voltammetry and controlled-potential amperometry are used to characterize the performance of the new nanoscopic biosensors under different preparation and operation conditions. The resulting electrodes offer convenient and rapid measurements of millimolar substrate concentrations, and (to the best of the authors' knowledge) are the smallest enzyme probes reported to date. 10 refs., 7 figs.

  1. The EBI enzyme portal

    PubMed Central

    Alcántara, Rafael; Onwubiko, Joseph; Cao, Hong; de Matos, Paula; Cham, Jennifer A.; Jacobsen, Jules; Fischer, Julia D.; Rahman, Syed Asad; Jassal, Bijay; Goujon, Mikael; Rowland, Francis; Velankar, Sameer; López, Rodrigo; Overington, John P.; Kleywegt, Gerard J.; Hermjakob, Henning; O’Donovan, Claire; Martín, María Jesús; Thornton, Janet M.; Steinbeck, Christoph

    2013-01-01

    The availability of comprehensive information about enzymes plays an important role in answering questions relevant to interdisciplinary fields such as biochemistry, enzymology, biofuels, bioengineering and drug discovery. At the EMBL European Bioinformatics Institute, we have developed an enzyme portal (http://www.ebi.ac.uk/enzymeportal) to provide this wealth of information on enzymes from multiple in-house resources addressing particular data classes: protein sequence and structure, reactions, pathways and small molecules. The fact that these data reside in separate databases makes information discovery cumbersome. The main goal of the portal is to simplify this process for end users. PMID:23175605

  2. Enzyme molecules as nanomotors.

    PubMed

    Sengupta, Samudra; Dey, Krishna K; Muddana, Hari S; Tabouillot, Tristan; Ibele, Michael E; Butler, Peter J; Sen, Ayusman

    2013-01-30

    Using fluorescence correlation spectroscopy, we show that the diffusive movements of catalase enzyme molecules increase in the presence of the substrate, hydrogen peroxide, in a concentration-dependent manner. Employing a microfluidic device to generate a substrate concentration gradient, we show that both catalase and urease enzyme molecules spread toward areas of higher substrate concentration, a form of chemotaxis at the molecular scale. Using glucose oxidase and glucose to generate a hydrogen peroxide gradient, we induce the migration of catalase toward glucose oxidase, thereby showing that chemically interconnected enzymes can be drawn together.

  3. Causal mediation analysis for longitudinal data with exogenous exposure.

    PubMed

    Bind, M-A C; Vanderweele, T J; Coull, B A; Schwartz, J D

    2016-01-01

    Mediation analysis is a valuable approach to examine pathways in epidemiological research. Prospective cohort studies are often conducted to study biological mechanisms and often collect longitudinal measurements on each participant. Mediation formulae for longitudinal data have been developed. Here, we formalize the natural direct and indirect effects using a causal framework with potential outcomes that allows for an interaction between the exposure and the mediator. To allow different types of longitudinal measures of the mediator and outcome, we assume two generalized mixed-effects models for both the mediator and the outcome. The model for the mediator has subject-specific random intercepts and random exposure slopes for each cluster, and the outcome model has random intercepts and random slopes for the exposure, the mediator, and their interaction. We also expand our approach to settings with multiple mediators and derive the mediated effects, jointly through all mediators. Our method requires the absence of time-varying confounding with respect to the exposure and the mediator. This assumption is achieved in settings with exogenous exposure and mediator, especially when exposure and mediator are not affected by variables measured at earlier time points. We apply the methodology to data from the Normative Aging Study and estimate the direct and indirect effects, via DNA methylation, of air pollution, and temperature on intercellular adhesion molecule 1 (ICAM-1) protein levels. Our results suggest that air pollution and temperature have a direct effect on ICAM-1 protein levels (i.e. not through a change in ICAM-1 DNA methylation) and that temperature has an indirect effect via a change in ICAM-1 DNA methylation. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Magnetic hyperthermia enhances cell toxicity with respect to exogenous heating.

    PubMed

    Sanz, Beatriz; Calatayud, M Pilar; Torres, Teobaldo E; Fanarraga, Mónica L; Ibarra, M Ricardo; Goya, Gerardo F

    2017-01-01

    Magnetic hyperthermia is a new type of cancer treatment designed for overcoming resistance to chemotherapy during the treatment of solid, inaccessible human tumors. The main challenge of this technology is increasing the local tumoral temperature with minimal side effects on the surrounding healthy tissue. This work consists of an in vitro study that compared the effect of hyperthermia in response to the application of exogenous heating (EHT) sources with the corresponding effect produced by magnetic hyperthermia (MHT) at the same target temperatures. Human neuroblastoma SH-SY5Y cells were loaded with magnetic nanoparticles (MNPs) and packed into dense pellets to generate an environment that is crudely similar to that expected in solid micro-tumors, and the above-mentioned protocols were applied to these cells. These experiments showed that for the same target temperatures, MHT induces a decrease in cell viability that is larger than the corresponding EHT, up to a maximum difference of approximately 45% at T = 46 °C. An analysis of the data in terms of temperature efficiency demonstrated that MHT requires an average temperature that is 6 °C lower than that required with EHT to produce a similar cytotoxic effect. An analysis of electron microscopy images of the cells after the EHT and MHT treatments indicated that the enhanced effectiveness observed with MHT is associated with local cell destruction triggered by the magnetic nano-heaters. The present study is an essential step toward the development of innovative adjuvant anti-cancer therapies based on local hyperthermia treatments using magnetic particles as nano-heaters.

  5. Exogenous sucrose utilization and starch biosynthesis among sweet potato cultivars.

    PubMed

    Ahn, Young Ock; Kim, Sun Ha; Kim, Cha Young; Lee, Joon-Seol; Kwak, Sang-Soo; Lee, Haeng-Soon

    2010-01-11

    Three sweetpotato cultivars were investigated for their starch content and amylose/amylopectin ratio. Ym starch contains 87.2% amylopectin and 12.8% amylose, when total starch was calculated as 100%. The Zm cultivar contains 33.6% amylopectin and 18.2% amylose, and its total starch was calculated as 51.8% of that of Ym. The Hm cultivar contains 39.1% amylopectin and 30.5% amylose, and its total starch was 69.6%. We analyzed the expression levels of starch and sucrose biosynthesis-related genes including AGPases a, b, and c; sucrose synthases I and II; starch synthase I; GBSS I; and SBEs I and II. All genes tested in this experiment were detected only in Ym, while several genes showed very faint or no expression in Zm and Hm. We also measured tissue-specific expression of these genes in whole plants of Ym. Most of the genes are expressed in the stem and roots of the plants. Expression profiles of starch synthesis-related genes of the sweetpotato leaves were investigated after supplementing the different concentrations of sucrose solution. All genes in Ym were clearly induced by sucrose, but the expression levels of some of these genes did not change in Zm and Hm. The total starch content of Ym, Zm, and Hm gradually increased over time on addition of 3%, 6%, and 9% sucrose concentrations. The greatest accumulation was observed in Ym at 48h, and it was almost 2.24 times higher than that of the (0%) control, while Zm and Hm showed 1.76 and 1.91 times higher levels of starch, respectively. These results indicate that cooperative expression of all related genes is essential for starch biosynthesis from sucrose. This is the first report on different sucrose contents and the efficiency with which exogenous sucrose switches on gene expression of starch biosynthesis-related genes among cultivars. Copyright 2009 Elsevier Ltd. All rights reserved.

  6. Legionella dumoffii Utilizes Exogenous Choline for Phosphatidylcholine Synthesis

    PubMed Central

    Palusinska-Szysz, Marta; Szuster-Ciesielska, Agnieszka; Kania, Magdalena; Janczarek, Monika; Chmiel, Elżbieta; Danikiewicz, Witold

    2014-01-01

    Phosphatidycholine (PC) is the major membrane-forming phospholipid in eukaryotes but it has been found in only a limited number of prokaryotes. Bacteria synthesize PC via the phospholipid N-methylation pathway (Pmt) or via the phosphatidylcholine synthase pathway (Pcs) or both. Here, we demonstrated that Legionella dumoffii has the ability to utilize exogenous choline for phosphatidylcholine (PC) synthesis when bacteria grow in the presence of choline. The Pcs seems to be a primary pathway for synthesis of this phospholipid in L. dumoffii. Structurally different PC species were distributed in the outer and inner membranes. As shown by the LC/ESI-MS analyses, PC15:0/15:0, PC16:0/15:0, and PC17:0/17:1 were identified in the outer membrane and PC14:0/16:0, PC16:0/17:1, and PC20:0/15:0 in the inner membrane. L. dumoffii pcsA gene encoding phosphatidylcholine synthase revealed the highest sequence identity to pcsA of L. bozemanae (82%) and L. longbeachae (81%) and lower identity to pcsA of L. drancourtii (78%) and L. pneumophila (71%). The level of TNF-α in THP1-differentiated cells induced by live and temperature-killed L. dumoffii cultured on a medium supplemented with choline was assessed. Live L. dumoffii bacteria cultured on the choline-supplemented medium induced TNF-α three-fold less efficiently than cells grown on the non-supplemented medium. There is an evident effect of PC modification, which impairs the macrophage inflammatory response. PMID:24821544

  7. Increased Microbial Butanol Tolerance by Exogenous Membrane Insertion Molecules.

    PubMed

    Hinks, Jamie; Wang, Yaofeng; Matysik, Artur; Kraut, Rachel; Kjelleberg, Staffan; Mu, Yuguang; Bazan, Guillermo C; Wuertz, Stefan; Seviour, Thomas

    2015-11-01

    Butanol is an ideal biofuel, although poor titers lead to high recovery costs by distillation. Fluidization of microbial membranes by butanol is one of the major factors limiting titers in butanol-producing bioprocesses. Starting with the hypothesis that certain membrane insertion molecules would stabilize the lipid bilayer in the presence of butanol, we applied a combination of in vivo and in vitro techniques within an in silico framework to describe a new approach to achieve solvent tolerance in bacteria. Single-molecule tracking of a model supported bilayer showed that COE1-5C, a five-ringed oligo-polyphenylenevinylene conjugated oligoelectrolyte (COE), reduced the diffusion rate of phospholipids in a microbially derived lipid bilayer to a greater extent than three-ringed and four-ringed COEs. Furthermore, COE1-5C treatment increased the specific growth rate of E. coli K12 relative to a control at inhibitory butanol concentrations. Consequently, to confer butanol tolerance to microbes by exogenous means is complementary to genetic modification of strains in industrial bioprocesses, extends the physiological range of microbes to match favorable bioprocess conditions, and is amenable with complex and undefined microbial consortia for biobutanol production. Molecular dynamics simulations indicated that the π-conjugated aromatic backbone of COE1-5C likely acts as a hydrophobic tether for glycerophospholipid acyl chains by enhancing bilayer integrity in the presence of high butanol concentrations, which thereby counters membrane fluidization. COE1-5C-mitigated E. coli K12 membrane depolarization by butanol is consistent with the hypothesis that improved growth rates in the presence of butanol are a consequence of improved bilayer stability. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Exogenous L-lactate clearance in adult horses.

    PubMed

    De Pedro, Pedro; Wilkins, Pamela A; McMichael, Maureen A; Dirikolu, Levent; Lascola, Kara M; Clark-Price, Stuart C; Boston, Raymond C

    2012-10-01

    To determine endogenous production of L-lactate and the clearance of exogenous sodium L-lactate (ExLC) in healthy adult horses. A sodium L-lactate solution (1 mmol/kg body weight qs to 500 mL final volume in 0.9% NaCl) was adminstered IV over 15 minutes. Blood samples for L-lactate concentration [LAC] measurement were collected immediately prior to infusion, at 5, 10, and 15 minutes during infusion and at 1 minute intervals for 15 minutes, at 30, 45, 60, 120, and 180 minutes postinfusion. Disposition modeling and pharmacokinetic analysis was performed using proprietary software. University Teaching Hospital. Six clinically healthy adult horses. Median (range) baseline [LAC] was 0.43 (0.20-0.72) mmol/L for samples obtained every 3 hours over the 24 hours prior to ExLC and demonstrated variability primarily associated with horse. Median [LAC] immediately prior to ExLC was 0.43 (0.35-0.52) mmol/L. A 2-compartment model was used to specify the pharmacokinetic parameters. Median (range) ExLC was 1.05 (0.073-1.75) L·h(-1) ·kg(-1) and t(1/2) β was 29.54 (20.8-38.6) min. Median lactate production based on basal [LAC] immediately prior to ExLC was was 0.49 (0.31-0.93) mmol·h(-1) ·kg(-1) . ExLC in healthy adult horses is greater than that of hyperlactemic human patients but similar to normolactemic-sick human patients examined using the same model, supporting development of species, and disease specific ExLC parameters. © Veterinary Emergency and Critical Care Society 2012.

  9. Endogenous and exogenous glucocorticoids in experimental enterococcal infection.

    PubMed

    Papasian, Christopher J; Qureshi, Nilofer; Morrison, David C

    2006-03-01

    The potentially protective role of the host adrenal-glucocorticoid response to enterococcal infection was evaluated in an experimental model in which mice were infected intraperitoneally with two distinct Enterococcus faecalis strains (K9 and CP-1). We demonstrated that corticosterone levels in serum and peritoneal-lavage fluid were elevated within 1 hour of infection with either E. faecalis strain. We also demonstrated that adrenalectomized mice generated a more robust localized peritoneal tumor necrosis factor alpha (TNF-alpha) response to both E. faecalis strains than did sham-adrenalectomized mice but that neither E. faecalis strain induced a systemic TNF-alpha response. Further, peritoneal TNF-alpha production in adrenalectomized mice infected with either E. faecalis K9 or CP-1 was suppressed by prior treatment with an exogenous glucocorticoid (dexamethasone). The potential clinical significance of these results was suggested by our findings that adrenalectomy markedly increased susceptibility (a>100-fold decrease in the 50% lethal dose) to lethal infections with E. faecalis CP-1 and that prior dexamethasone treatment partially compensated for adrenalectomy. In marked contrast to these findings, however, adrenalectomy did not substantially increase susceptibility to lethal E. faecalis K9 infection. Further, preinfection with E. faecalis CP-1 1 hour before infection with E. faecalis K9 did not protect mice from lethal E. faecalis K9 infections. Collectively, these studies indicate that the host can generate a glucocorticoid response to E. faecalis infection that suppresses TNF-alpha production. Further, this glucocorticoid response can protect the host from potentially lethal E. faecalis infections, but different strains show heterogeneity with respect to the extent of protection afforded by the adrenal-glucocorticoid response.

  10. Causal mediation analysis for longitudinal data with exogenous exposure

    PubMed Central

    Bind, M.-A. C.; Vanderweele, T. J.; Coull, B. A.; Schwartz, J. D.

    2016-01-01

    Mediation analysis is a valuable approach to examine pathways in epidemiological research. Prospective cohort studies are often conducted to study biological mechanisms and often collect longitudinal measurements on each participant. Mediation formulae for longitudinal data have been developed. Here, we formalize the natural direct and indirect effects using a causal framework with potential outcomes that allows for an interaction between the exposure and the mediator. To allow different types of longitudinal measures of the mediator and outcome, we assume two generalized mixed-effects models for both the mediator and the outcome. The model for the mediator has subject-specific random intercepts and random exposure slopes for each cluster, and the outcome model has random intercepts and random slopes for the exposure, the mediator, and their interaction. We also expand our approach to settings with multiple mediators and derive the mediated effects, jointly through all mediators. Our method requires the absence of time-varying confounding with respect to the exposure and the mediator. This assumption is achieved in settings with exogenous exposure and mediator, especially when exposure and mediator are not affected by variables measured at earlier time points. We apply the methodology to data from the Normative Aging Study and estimate the direct and indirect effects, via DNA methylation, of air pollution, and temperature on intercellular adhesion molecule 1 (ICAM-1) protein levels. Our results suggest that air pollution and temperature have a direct effect on ICAM-1 protein levels (i.e. not through a change in ICAM-1 DNA methylation) and that temperature has an indirect effect via a change in ICAM-1 DNA methylation. PMID:26272993

  11. Object-centered representations support flexible exogenous visual attention across translation and reflection

    PubMed Central

    Lin, Zhicheng

    2013-01-01

    Visual attention can be deployed to stimuli based on our willful, top-down goal (endogenous attention) or on their intrinsic saliency against the background (exogenous attention). Flexibility is thought to be a hallmark of endogenous attention, whereas decades of research show that exogenous attention is attracted to the retinotopic locations of the salient stimuli. However, to the extent that salient stimuli in the natural environment usually form specific spatial relations with the surrounding context and are dynamic, exogenous attention, to be adaptive, should embrace these structural regularities. Here we test a non-retinotopic, object-centered mechanism in exogenous attention, in which exogenous attention is dynamically attracted to a relative, object-centered location. Using a moving frame configuration, we presented two frames in succession, forming either apparent translational motion or in mirror reflection, with a completely uninformative, transient cue presented at one of the item locations in the first frame. Despite that the cue is presented in a spatially separate frame, in both translation and mirror reflection, human performance in visual search is enhanced when the target in the second frame appears at the same relative location as the cue location than at other locations. These results provide unambiguous evidence for non-retinotopic exogenous attention and further reveal an object-centered mechanism supporting flexible exogenous attention. Moreover, attentional generalization across mirror reflection may constitute an attentional correlate of perceptual generalization across lateral mirror images, supporting an adaptive, functional account of mirror images confusion. PMID:23942348

  12. Synthesis of nitrogen and sulfur macrocycles with cis exogenous oxygen and sulfur donor atoms.

    PubMed

    White, Vivienne A; Long, Nicholas J; Robertson, Neil

    2005-12-07

    A series of new N4 and N8 macrocycles has been prepared, that includes cis-exogenous O2, S2 and S/O atoms to allow chelation to a metal external to the macrocyclic ring. We found that thioamide units within the macrocycles were unstable to attack by secondary amines and thus alkylated precursors containing only tertiary amines could lead to exogenous-S2 macrocycles. Cyclisation of alkylated tetraamine precursors with dimethyloxalate or dithiooxamide led to both N4 and N8 macrocycles via 1 + 1 and 2 + 2 cyclisation reactions with exogenous-O2 or S2 respectively. Alkylation of preformed exogenous-O2 macrocycles was explored and led to alkyl substitution at the secondary amine nitrogens in the ring, however synthesis of these species was overall lower yielding than cyclisation using alkylated tetraamine precursors. Thionation of an exo-O2 macrocycle using an analogue of Lawesson's Reagent led to formation of the analogous exogenous-S2 and exogenous-O,S macrocycles. Related S2N2 macrocycles with exogenous-O2 were prepared by a cyclisation route but could not be isolated free of larger ring analogues.

  13. Estimating distributions of endogenous and exogenous Pb in soils by using Pb isotopic ratios.

    PubMed

    Semlali, R M; van Oort, F; Denaix, L; Loubet, M

    2001-11-01

    Metal contamination of soils by diffuse atmospheric deposition is a worldwide phenomenon. The assessment of incorporation of exogenous metal contaminants in soils is of major environmental importance. Once entering in the soil's biogeochemical cycling, specific pedogenetic soil processes govern metal distribution patterns with depth. In this paper, we attempt to estimate the distribution of endogenous and exogenous Pb in two soils with contrasting pedogenesis, both representative of undisturbed ecosystems. Pb isotope analyses were performed using high-precision thermal ionization mass spectrometry. Endogenous and exogenous Pb concentrations and exogenous 206Pb/207Pb ratios of the samples were calculated using bulk Pb and Sc concentrations and bulk 206Pb/207Pb ratios. Endogenous Pb distribution was in agreementwith dominant soil characteristics, almost constant in the young Andosol and with a clear minimum and maximum in the eluvial and illuvial horizons of the Podzol. The distribution of exogenous Pb was closely related to that of organic C in both soils. Exogenous Pb was evidenced in significant amounts at depth. Using moderate dispersive particle-size fractionation allowed us to evidence the presence of exogenous Pb in functional soil compartments and to highlight preferential distributions of Pb, according to pedology.

  14. Preventive effects of chronic exogenous growth hormone levels on diet-induced hepatic steatosis in rats

    PubMed Central

    2010-01-01

    Background Non-alcoholic fatty liver disease (NAFLD), which is characterized by hepatic steatosis, can be reversed by early treatment. Several case reports have indicated that the administration of recombinant growth hormone (GH) could improve fatty liver in GH-deficient patients. Here, we investigated whether chronic exogenous GH levels could improve hepatic steatosis induced by a high-fat diet in rats, and explored the underlying mechanisms. Results High-fat diet-fed rats developed abdominal obesity, fatty liver and insulin resistance. Chronic exogenous GH improved fatty liver, by reversing dyslipidaemia, fat accumulation and insulin resistance. Exogenous GH also reduced serum tumour necrosis factor-alpha (TNF-alpha) levels, and ameliorated hepatic lipid peroxidation and oxidative stress. Hepatic fat deposition was also reduced by exogenous GH levels, as was the expression of adipocyte-derived adipokines (adiponectin, leptin and resistin), which might improve lipid metabolism and hepatic steatosis. Exogenous GH seems to improve fatty liver by reducing fat weight, improving insulin sensitivity and correcting oxidative stress, which may be achieved through phosphorylation or dephosphorylation of a group of signal transducers and activators of hepatic signal transduction pathways. Conclusions Chronic exogenous GH has positive effects on fatty liver and may be a potential clinical application in the prevention or reversal of fatty liver. However, chronic secretion of exogenous GH, even at a low level, may increase serum glucose and insulin levels in rats fed a standard diet, and thus increase the risk of insulin resistance. PMID:20653983

  15. Induced resistance to Helicoverpa armigera through exogenous application of jasmonic acid and salicylic acid in groundnut, Arachis hypogaea.

    PubMed

    War, Abdul Rashid; Paulraj, Michael Gabriel; Ignacimuthu, Savarimuthu; Sharma, Hari Chand

    2015-01-01

    Induced resistance to Helicoverpa armigera through exogenous application of jasmonic acid (JA) and salicylic acid (SA) was studied in groundnut genotypes (ICGV 86699, ICGV 86031, ICG 2271 and ICG 1697) with different levels of resistance to insects and the susceptible check JL 24 under greenhouse conditions. Activities of oxidative enzymes and the amounts of secondary metabolites and proteins were quantified at 6 days after JA and SA application/insect infestation. Data were also recorded on plant damage and H. armigera larval weights and survival. Higher levels of enzymatic activities and amounts of secondary metabolites were observed in the insect-resistant genotypes pretreated with JA and then infested with H. armigera than in JL 24. The insect-resistant genotypes suffered lower insect damage and resulted in poor survival and lower weights of H. armigera larvae than JL 24. In some cases, JA and SA showed similar effects. JA and SA induced the activity of antioxidative enzymes in groundnut plants against H. armigera, and reduced its growth and development. However, induced response to application of JA was greater than to SA, and resulted in reduced plant damage, and larval weights and survival, suggesting that induced resistance can be used as a component of pest management in groundnut. © 2014 Society of Chemical Industry.

  16. Commercial production of microbial enzymes

    SciTech Connect

    Munro, I.G.

    1985-01-01

    The advantages and uses of industrially produced microbial enzymes are described. The processes involved in the production of these enzymes, cultivation techniques, enzyme extraction, enzyme purification and immobilization are outlined. Both the history of enzyme technology and its future development are discussed.

  17. Where do the immunostimulatory effects of oral proteolytic enzymes ('systemic enzyme therapy') come from? Microbial proteolysis as a possible starting point.

    PubMed

    Biziulevicius, Gediminas A

    2006-01-01

    Enteric-coated proteolytic enzyme preparations like Wobenzym and Phlogenzym are widely used for the so-called 'systemic enzyme therapy' both in humans and animals. Numerous publications reveal that oral proteolytic enzymes are able to stimulate directly the activity of immune competent cells as well as to increase efficiency of some of their products. But origins of the immunostimulatory effects of oral proteolytic enzymes are still unclear. The hypothesis described here suggests that it may be proteolysis of intestinal microorganisms that makes the immune competent cells to work in the immunostimulatory manner. The hypothesis was largely formed by several scientific observations: First, microbial lysis products (lipopolysaccharides, muropeptides and other peptidoglycan fragments, beta-glucans, etc.) are well known for their immunostimulatory action. Second, a normal human being hosts a mass of intestinal microorganisms equivalent to about 1 kg. The biomass (mainly due to naturally occurring autolysis) continuously supplies the host's organism with immunostimulatory microbial cell components. Third, the immunostimulatory effects resulting from the oral application of exogenously acting antimicrobial (lytic) enzyme preparations, such as lysozyme and lysosubtilin, are likely to be a result of the action of microbial lysis products. Fourth, cell walls of most microorganisms contain a considerable amount of proteins/peptides, a possible target for exogenous proteolytic enzymes. In fact, several authors have already shown that a number of proteases possess an ability to lyse the microbial cells in vitro. Fifth, the pretreatment of microbial cells (at least of some species) in vitro with proteolytic enzymes makes them more sensitive to the lytic action of lysozyme and, otherwise, pretreatment with lysozyme makes them more susceptible to proteolytic degradation. Sixth, exogenous proteases, when in the intestines, may participate in final steps of food-protein digestion

  18. RNA as an Enzyme.

    ERIC Educational Resources Information Center

    Cech, Thomas R.

    1986-01-01

    Reviews current findings that explain RNA's function as an enzyme in addition to being an informational molecule. Highlights recent research efforts and notes changes in the information base on RNA activity. Includes models and diagrams of RNA activity. (ML)

  19. Enzymes in Analytical Chemistry.

    ERIC Educational Resources Information Center

    Fishman, Myer M.

    1980-01-01

    Presents tabular information concerning recent research in the field of enzymes in analytic chemistry, with methods, substrate or reaction catalyzed, assay, comments and references listed. The table refers to 128 references. Also listed are 13 general citations. (CS)

  20. Indicators: Sediment Enzymes

    EPA Pesticide Factsheets

    Sediment enzymes are proteins that are produced by microorganisms living in the sediment or soil. They are indicators of key ecosystem processes and can help determine which nutrients are affecting the biological community of a waterbody.

  1. Starch Biorefinery Enzymes.

    PubMed

    Läufer, Albrecht

    2017-03-07

    Nature uses enzymes to build and convert biomass; mankind uses the same enzymes and produces them on a large scale to make optimum use of biomass in biorefineries. Bacterial α-amylases and fungal glucoamylases have been the workhorses of starch biorefineries for many decades. Pullulanases were introduced in the 1980s. Proteases, cellulases, hemicellulases, and phytases have been on the market for a few years as process aids, improving yields, performance, and costs. Detailed studies of the complex chemical structures of biomass and of the physicochemical limitations of industrial biorefineries have led enzyme developers to produce novel tailor-made solutions for improving yield and profitability in the industry. This chapter reviews the development of enzyme applications in the major starch biorefining processes.

  2. RNA as an Enzyme.

    ERIC Educational Resources Information Center

    Cech, Thomas R.

    1986-01-01

    Reviews current findings that explain RNA's function as an enzyme in addition to being an informational molecule. Highlights recent research efforts and notes changes in the information base on RNA activity. Includes models and diagrams of RNA activity. (ML)

  3. Overproduction of ligninolytic enzymes

    DOEpatents

    Elisashvili, Vladimir; Kachlishvili, Eva; Torok, Tamas

    2014-06-17

    Methods, compositions, and systems for overproducing ligninolytic enzymes from the basidiomycetous fungus are described herein. As described, the method can include incubating a fungal strain of Cerrena unicolor IBB 303 in a fermentation system having growth medium which includes lignocellulosic material and then cultivating the fungal strain in the fermentation system under conditions wherein the fungus expresses the ligninolytic enzymes. In some cases, the lignocellulosic material is mandarin peel, ethanol production residue, walnut pericarp, wheat bran, wheat straw, or banana peel.

  4. Molecular phylogenomic study and the role of exogenous spermidine in the metabolic adjustment of endogenous polyamine in two rice cultivars under salt stress.

    PubMed

    Saha, Jayita; Giri, Kalyan

    2017-04-20

    Compelling evidences anticipated the well acclamation of involvement of exogenous and endogenous polyamines (PAs) in conferring salt tolerance in plants. Intracellular PA's anabolism and catabolism should have contributed to maintain endogenous PAs homeostasis to induce stress signal networks. In this report, the evolutionary study has been conducted to reveal the phylogenetic relationship of genes encoding enzymes of the anabolic and catabolic pathway of PAs among the five plant lineages including green algae, moss, lycophyte, dicot and monocot along with their respective exon-intron structural patterns. Our results indicated that natural selection pressure had considerable influence on the ancestral PA metabolic pathway coding genes of land plants. PA metabolic genes have undergone gradual evolution by duplication and diversification process leading to subsequent structural modification through exon-intron gain and loss events to acquire specific function under environmental stress conditions. We have illuminated on the potential regulation of both the pathways by investigating the real-time expression analyses of PA metabolic pathway related enzyme coding genes at the transcriptional level in root and shoot tissues of two indica rice varieties, namely IR 36 (salt sensitive) and Nonabokra (salt-tolerant) in response to salinity in presence or absence of exogenous spermidine (Spd) treatment. Additionally, we have performed tissue specific quantification of the intracellular PAs and tried to draw probable connection between the PA metabolic pathway activation and endogenous PAs accumulation. Our results successfully enlighten the fact that how exogenous Spd in presence or absence of salt stress adjust the intracellular PA pathways to equilibrate the cellular PAs that would have been attributed to plant salt tolerance.

  5. Recombinant hyperthermophilic enzyme expression in plants: a novel approach for lignocellulose digestion.

    PubMed

    Mir, Bilal Ahmad; Mewalal, Ritesh; Mizrachi, Eshchar; Myburg, Alexander A; Cowan, Don A

    2014-05-01

    Plant biomass, as an abundant renewable carbon source, is a promising alternative to fossil fuels. However, the enzymes most commonly used for depolymerization of lignocellulosic biomass are expensive, and the development of cost-effective alternative conversion technologies would be desirable. One possible option is the heterologous expression of genes encoding lignocellulose-digesting enzymes in plant tissues. To overcome simultaneously issues of toxicity and incompatibility with high-temperature steam explosion processes, the use of heterologous genes encoding hyperthermophilic enzymes may be an attractive alternative. This approach could reduce the need for exogenous enzyme additions prior to fermentation, reducing the cost of the complete processing operation. This review highlights recent advances and future prospects for using hyperthermophilic enzymes in the biofuels industry. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Co‐immobilized Phosphorylated Cofactors and Enzymes as Self‐Sufficient Heterogeneous Biocatalysts for Chemical Processes

    PubMed Central

    Velasco‐Lozano, Susana; Benítez‐Mateos, Ana I.

    2016-01-01

    Abstract Enzyme cofactors play a major role in biocatalysis, as many enzymes require them to catalyze highly valuable reactions in organic synthesis. However, the cofactor recycling is often a hurdle to implement enzymes at the industrial level. The fabrication of heterogeneous biocatalysts co‐immobilizing phosphorylated cofactors (PLP, FAD+, and NAD+) and enzymes onto the same solid material is reported to perform chemical reactions without exogeneous addition of cofactors in aqueous media. In these self‐sufficient heterogeneous biocatalysts, the immobilized enzymes are catalytically active and the immobilized cofactors catalytically available and retained into the solid phase for several reaction cycles. Finally, we have applied a NAD+‐dependent heterogeneous biocatalyst to continuous flow asymmetric reduction of prochiral ketones, thus demonstrating the robustness of this approach for large scale biotransformations. PMID:28000978

  7. Co-immobilized Phosphorylated Cofactors and Enzymes as Self-Sufficient Heterogeneous Biocatalysts for Chemical Processes.

    PubMed

    Velasco-Lozano, Susana; Benítez-Mateos, Ana I; López-Gallego, Fernando

    2017-01-16

    Enzyme cofactors play a major role in biocatalysis, as many enzymes require them to catalyze highly valuable reactions in organic synthesis. However, the cofactor recycling is often a hurdle to implement enzymes at the industrial level. The fabrication of heterogeneous biocatalysts co-immobilizing phosphorylated cofactors (PLP, FAD(+) , and NAD(+) ) and enzymes onto the same solid material is reported to perform chemical reactions without exogeneous addition of cofactors in aqueous media. In these self-sufficient heterogeneous biocatalysts, the immobilized enzymes are catalytically active and the immobilized cofactors catalytically available and retained into the solid phase for several reaction cycles. Finally, we have applied a NAD(+) -dependent heterogeneous biocatalyst to continuous flow asymmetric reduction of prochiral ketones, thus demonstrating the robustness of this approach for large scale biotransformations.

  8. The mononuclear molybdenum enzymes

    SciTech Connect

    Hille, R.

    1996-11-01

    Molybdenum is widely available to biological systems due to the solubility of its high-valent oxides in water and is found in two basic forms: as an integral component of the multinuclear M center of nitrogenases and as the mononuclear active sites of a much more diverse group of enzymes that in general function catalytically to transfer an oxygen atom either to or from a physiological acceptor/donor molecule. It is on the basis of this commonly encountered aspect of catalysis that these enzymes are frequently referred to as oxotransferases, although no mechanistic connotation is intended in using the term. Similarly, the vast majority of these enzymes possess a Mo{double_bond}O unit in their active sites and are often referred to as oxomolybdenum enzymes. Neither of these terms is strictly applicable to the entire class of enzymes, however, as some (polysulfide reductase, for example, and possibly formate dehydrogenase) do not possess a Mo{double_bond}O unit. Here the term mononuclear molybdenum enzymes will be used in order to be as generic as possible. 431 refs.

  9. Exogenous thyroid hormones regulate the activity of citrate synthase and cytochrome c oxidase in warm- but not cold-acclimated lake whitefish (Coregonus clupeaformis)

    USGS Publications Warehouse

    Zak, Megan A.; Regish, Amy M.; McCormick, Stephen; Manzon, Richard G.

    2017-01-01

    Thermal acclimation is known to elicit metabolic adjustments in ectotherms, but the cellular mechanisms and endocrine control of these shifts have not been fully elucidated. Here we examined the relationship between thermal acclimation, thyroid hormones and oxidative metabolism in juvenile lake whitefish. Impacts of thermal acclimation above (19 °C) or below (8 °C) the thermal optimum (13 °C) and exposure to exogenous thyroid hormone (60 µg T4/g body weight) were assessed by quantifying citrate synthase and cytochrome c oxidase activities in liver, red muscle, white muscle and heart. Warm acclimation decreased citrate synthase activity in liver and elevated both citrate synthase and cytochrome c oxidase activities in red muscle. In contrast, induction of hyperthyroidism in warm-acclimated fish stimulated a significant increase in liver citrate synthase and heart cytochrome c oxidase activities, and a decrease in the activity of both enzymes in red muscle. No change in citrate synthase or cytochrome c oxidase activities was observed following cold acclimation in either the presence or absence of exogenous thyroid hormones. Collectively, our results indicate that thyroid hormones influence the activity of oxidative enzymes more strongly in warm-acclimated than in cold-acclimated lake whitefish, and they may play a role in mediating metabolic adjustments observed during thermal acclimation.

  10. Exogenous thyroid hormones regulate the activity of citrate synthase and cytochrome c oxidase in warm- but not cold-acclimated lake whitefish (Coregonus clupeaformis).

    PubMed

    Zak, Megan A; Regish, Amy M; McCormick, Stephen D; Manzon, Richard G

    2017-02-14

    Thermal acclimation is known to elicit metabolic adjustments in ectotherms, but the cellular mechanisms and endocrine control of these shifts have not been fully elucidated. Here we examined the relationship between thermal acclimation, thyroid hormones and oxidative metabolism in juvenile lake whitefish. Impacts of thermal acclimation above (19°C) or below (8°C) the thermal optimum (13°C) and exposure to exogenous thyroid hormone (60µg T4/g body weight) were assessed by quantifying citrate synthase and cytochrome c oxidase activities in liver, red muscle, white muscle and heart. Warm acclimation decreased citrate synthase activity in liver and elevated both citrate synthase and cytochrome c oxidase activities in red muscle. In contrast, induction of hyperthyroidism in warm-acclimated fish stimulated a significant increase in liver citrate synthase and heart cytochrome c oxidase activities, and a decrease in the activity of both enzymes in red muscle. No change in citrate synthase or cytochrome c oxidase activities was observed following cold acclimation in either the presence or absence of exogenous thyroid hormones. Collectively, our results indicate that thyroid hormones influence the activity of oxidative enzymes more strongly in warm-acclimated than in cold-acclimated lake whitefish, and they may play a role in mediating metabolic adjustments observed during thermal acclimation.

  11. Regulation of Chloroplast Photosynthetic Activity by Exogenous Magnesium 1

    PubMed Central

    Huber, Steven C.

    1978-01-01

    Magnesium was most inhibitory to photosynthetic reactions by intact chloroplasts when the magnesium was added in the dark before illumination. Two millimolar MgCl2, added in the dark, inhibited CO2-dependent O2 evolution by Hordeum vulgare L. and Spinacia oleracea L. (C3 plants) chloroplasts 70 to 100% and inhibited (pyruvate + oxaloacetate)-dependent O2 evolution by Digitaria sanguinalis L. (C4 plant) mesophyll chloroplasts from 80 to 100%. When Mg2+ was added in the light, O2 evolution was reduced only slightly. O2 evolution in the presence of phosphoglycerate was less sensitive to Mg2+ inhibition than was CO2-dependent O2 evolution. Magnesium prevented the light activation of several photosynthetic enzymes. Two millimolar Mg2+ blocked the light activation of NADP-malate dehydrogenase in D. sanguinalis mesophyll chloroplasts, and the light activation of phosphoribulokinase, NADP-linked glyceraldehyde-3-phosphate dehydrogenase, and fructose 1,6-diphosphatase in barley chloroplasts. The results suggest that Mg2+ inhibits chloroplast photosynthesis by preventing the light activation of certain enzymes. PMID:16660509

  12. Synthesis, transport, and metabolism of serotonin formed from exogenously applied 5-HTP after spinal cord injury in rats

    PubMed Central

    Li, Yaqing; Li, Lisa; Stephens, Marilee J.; Zenner, Dwight; Murray, Katherine C.; Winship, Ian R.; Vavrek, Romana; Baker, Glen B.; Fouad, Karim

    2013-01-01

    Spinal cord transection leads to elimination of brain stem-derived monoamine fibers that normally synthesize most of the monoamines in the spinal cord, including serotonin (5-hydroxytryptamine, 5-HT) synthesized from tryptophan by enzymes tryptophan hydroxylase (TPH, synthesizing 5-hydroxytryptophan, 5-HTP) and aromatic l-amino acid decarboxylase (AADC, synthesizing 5-HT from 5-HTP). Here we examine whether spinal cord caudal to transection remains able to manufacture and metabolize 5-HT. Immunolabeling for AADC reveals that, while most AADC is confined to brain stem-derived monoamine fibers in spinal cords from normal rats, caudal to transection AADC is primarily found in blood vessel endothelial cells and pericytes as well as a novel group of neurons (NeuN positive and GFAP negative), all of which strongly upregulate AADC with injury. However, immunolabeling for 5-HT reveals that there is no detectable endogenous 5-HT synthesis in any structure in the spinal cord caudal to a chronic transection, including in AADC-containing vessels and neurons, consistent with a lack of TPH. In contrast, when we applied exogenous 5-HTP (in vitro or in vivo), AADC-containing vessels and neurons synthesized 5-HT, which contributed to increased motoneuron activity and muscle spasms (long-lasting reflexes, LLRs), by acting on 5-HT2 receptors (SB206553 sensitive) located on motoneurons (TTX resistant). Blocking monoamine oxidase (MAO) markedly increased the sensitivity of the motoneurons (LLR) to 5-HTP, more than it increased the sensitivity of motoneurons to 5-HT, suggesting that 5-HT synthesized from AADC is largely metabolized in AADC-containing neurons and vessels. In summary, after spinal cord injury AADC is upregulated in vessels, pericytes, and neurons but does not endogenously produce 5-HT, whereas when exogenous 5-HTP is provided AADC does produce functional amounts of 5-HT, some of which is able to escape metabolism by MAO, diffuse out of these AADC-containing cells, and

  13. Synthesis, transport, and metabolism of serotonin formed from exogenously applied 5-HTP after spinal cord injury in rats.

    PubMed

    Li, Yaqing; Li, Lisa; Stephens, Marilee J; Zenner, Dwight; Murray, Katherine C; Winship, Ian R; Vavrek, Romana; Baker, Glen B; Fouad, Karim; Bennett, David J

    2014-01-01

    Spinal cord transection leads to elimination of brain stem-derived monoamine fibers that normally synthesize most of the monoamines in the spinal cord, including serotonin (5-hydroxytryptamine, 5-HT) synthesized from tryptophan by enzymes tryptophan hydroxylase (TPH, synthesizing 5-hydroxytryptophan, 5-HTP) and aromatic l-amino acid decarboxylase (AADC, synthesizing 5-HT from 5-HTP). Here we examine whether spinal cord caudal to transection remains able to manufacture and metabolize 5-HT. Immunolabeling for AADC reveals that, while most AADC is confined to brain stem-derived monoamine fibers in spinal cords from normal rats, caudal to transection AADC is primarily found in blood vessel endothelial cells and pericytes as well as a novel group of neurons (NeuN positive and GFAP negative), all of which strongly upregulate AADC with injury. However, immunolabeling for 5-HT reveals that there is no detectable endogenous 5-HT synthesis in any structure in the spinal cord caudal to a chronic transection, including in AADC-containing vessels and neurons, consistent with a lack of TPH. In contrast, when we applied exogenous 5-HTP (in vitro or in vivo), AADC-containing vessels and neurons synthesized 5-HT, which contributed to increased motoneuron activity and muscle spasms (long-lasting reflexes, LLRs), by acting on 5-HT2 receptors (SB206553 sensitive) located on motoneurons (TTX resistant). Blocking monoamine oxidase (MAO) markedly increased the sensitivity of the motoneurons (LLR) to 5-HTP, more than it increased the sensitivity of motoneurons to 5-HT, suggesting that 5-HT synthesized from AADC is largely metabolized in AADC-containing neurons and vessels. In summary, after spinal cord injury AADC is upregulated in vessels, pericytes, and neurons but does not endogenously produce 5-HT, whereas when exogenous 5-HTP is provided AADC does produce functional amounts of 5-HT, some of which is able to escape metabolism by MAO, diffuse out of these AADC-containing cells, and

  14. Effects of exogenous spermidine on photosynthetic capacity and expression of Calvin cycle genes in salt-stressed cucumber seedlings.

    PubMed

    Shu, Sheng; Chen, Lifang; Lu, Wei; Sun, Jin; Guo, Shirong; Yuan, Yinhui; Li, Jun

    2014-11-01

    We investigated the effects of exogenous spermidine (Spd) on growth, photosynthesis and expression of the Calvin cycle-related genes in cucumber seedlings (Cucumis sativus L.) exposed to NaCl stress. Salt stress reduced net photosynthetic rates (PN), actual photochemical efficiency of PSII (ΦPSII) and inhibited plant growth. Application of exogenous Spd to salinized nutrient solution alleviated salinity-induced the inhibition of plant growth, together with an increase in PN and ΦPSII. Salinity markedly reduced the maximum carboxylase activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (Vcmax), the maximal velocity of RuBP regeneration (Jmax), triose-phosphate utilization capacity (TPU) and carboxylation efficiency (CE). Spd alleviated the negative effects on CO2 assimilation induced by salt stress. Moreover, Spd significantly increased the activities and contents of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and fructose-1,6-biphosphate aldolase (ALD; aldolase) in the salt-stressed cucumber leaves. On the other hand, salinity up-regulated the transcriptional levels of ribulose-1,5-bisphosphate (RCA), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and phosphoribrokinase (PRK) and down-regulated the transcriptional levels of ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit (RbcL), ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit (RbcS), ALD, triose-3-phosphate isomerase (TPI), fructose-1,6-bisphosphate phosphatase (FBPase) and 3-phosphoglyceric acid kinase (PGK). However, Spd application to salt-stressed plant roots counteracted salinity-induced mRNA expression changes in most of the above-mentioned genes. These results suggest that Spd could improve photosynthetic capacity through regulating gene expression and activity of key enzymes for CO2 fixation, thus confers tolerance to salinity on cucumber plants.

  15. Exogenous oxytocin modulates human myometrial microRNAs.

    PubMed

    Cook, Joanna R; MacIntyre, David A; Samara, Eleni; Kim, Sung Hye; Singh, Natasha; Johnson, Mark R; Bennett, Phillip R; Terzidou, Vasso

    2015-07-01

    MicroRNAs (miRNAs) play a modulatory role in pathways that lead to labor onset, although oxytocin is known to modulate gene expression within the myometrium. We aimed to identify miRNAs whose expression is regulated by oxytocin in pregnant human myometrium. Myometrial miRNA expression profiles were compared between samples collected from women at term before the onset of labor (no labor; n = 8) and after labor onset after early exogenous oxytocin treatment (n = 8). Multivariate modelling was used to assess differences in miRNA profiles. Biologic validation was undertaken on 3 independent patient cohorts (no labor, n = 10; labor induced with oxytocin, n = 8; and spontaneous labor with no oxytocin treatment, n = 10). In vitro studies that used primary myocytes were undertaken to assess target miRNA expression after oxytocin treatment. Target genes of candidate miRNAs were identified in silico and cross-referenced with genes that are known to be associated with labor or expressed in myometrium. In total, 1309 miRNAs were analyzed by microarray, of which 494 were detected in human myometrium. Multivariate modeling identified 12 target miRNAs the differential expression of which was most responsible for the observed separation of the 2 patient populations in the primary discovery cohorts. Biologic validation in the independent secondary sample cohorts showed that oxytocin independently regulated 5 miRNAs (hsa-miR-146b-3p, hsa-miR-196b-3p, hsa-miR-223-3p, hsa-miR-873-5p, and hsa-miR-876-5p). Additionally, hsa-miR-146b-3p was increased both in labor that was induced with oxytocin and in myometrium from spontaneous labor with no oxytocin treatment compared with no labor samples. Four of the validated miRNAs (hsa-miR-146a-5p, hsa-miR-146b-3p, hsa-miR-196b-3p, and hsa-miR-876-5p) were expressed in primary human myocytes; oxytocin treatment of these cells replicated the directional changes that were observed in vivo. Oxytocin alters the expression of a unique set of

  16. Metabolism and distribution of exogenous histamine in cats

    PubMed Central

    Imrie, P.R.; Marley, E.; Thomas, D.V.

    1978-01-01

    1 The metabolism and disposition in blood and tissues of exogenous [14C]-histamine was examined in cats. 2 The principal metabolites in blood of histamine instilled into the small intestine (directly or by transfer from the stomach) and colon were imidazoleacetic acid and t-methylimidazoleacetic acid, being present in approximately equal amounts although in individual cats one or other acid could predominate. Only small amounts of histamine entered the circulation although in two of four cats given the largest dose (82 μmol/kg) large amounts were recovered. The amount of 14C radioactivity absorbed varied directly with the dose instilled. The chief metabolite in kidney and urine, whether histamine was instilled into the intestine or infused parenterally, was t-methylimidazoleacetic acid. Histamine was not absorbed from the stomach and its metabolism there was negligible. 3 In contrast, when histamine was infused into blood leaving the intestine (portal vein) the main metabolite in blood and tissues was t-methylimidazoleacetic acid being found in approximately 5-fold the concentration of imidazoleacetic acid. The small amount of histamine which eluded inactivation/uptake by liver, lungs, heart during the infusion was halved on circulation through the intestine. When histamine was infused into blood supplying the intestine, (cranial mesenteric artery) t-methylimidazoleacetic acid while still the major metabolite in blood was now only 1.4 times the concentration of imidazoleacetic acid. Additionally, the blood concentration of histamine during the infusion exceeded that of the metabolites. 4 t-Methylimidazoleacetic acid was also the principal metabolite in blood and tissues following histamine infusion into a cannula carrying a replacement venous blood supply to the liver of abdominally eviscerated cats. Imidazoleacetic acid and t-methylhistamine were present in equal concentrations and in one-quarter to one-third that of the methylated acid. The latter was also the

  17. Exogenous and endogenous attention during perceptual learning differentially affect post-training target thresholds

    PubMed Central

    Mukai, Ikuko; Bahadur, Kandy; Kesavabhotla, Kartik; Ungerleider, Leslie G.

    2012-01-01

    There is conflicting evidence in the literature regarding the role played by attention in perceptual learning. To further examine this issue, we independently manipulated exogenous and endogenous attention and measured the rate of perceptual learning of oriented Gabor patches presented in different quadrants of the visual field. In this way, we could track learning at attended, divided-attended, and unattended locations. We also measured contrast thresholds of the Gabor patches before and after training. Our results showed that, for both exogenous and endogenous attention, accuracy in performing the orientation discrimination improved to a greater extent at attended than at unattended locations. Importantly, however, only exogenous attention resulted in improved contrast thresholds. These findings suggest that both exogenous and endogenous attention facilitate perceptual learning, but that these two types of attention may be mediated by different neural mechanisms. PMID:21282340

  18. Clinical breath analysis: Discriminating between human endogenous compounds and exogenous (environmental) chemical confounders

    EPA Science Inventory

    Volatile organic compounds (VOCs) in exhaled breath originate from current or previous environmental exposures (exogenous compounds) and internal metabolic anabolic and catabolic) production (endogenous compounds). The origins of certain VOCs in breath presumed to be endogenous ...

  19. Exogenous attention to angry faces in social anxiety: a perceptual accuracy approach.

    PubMed

    Moriya, Jun; Tanno, Yoshihiko

    2011-11-01

    We investigated the interaction between endogenous and exogenous attention for the processing of emotional stimuli in individuals with high social anxiety using accuracy rates. Following the presentation of an endogenous cue at the centre, exogenous cues (i.e., angry and neutral faces) were presented at peripheral locations. Subsequently, non-emotional masked targets were presented, and the participants were instructed to discriminate between the targets. With respect to exogenous attention, high socially anxious people exhibited higher accuracy when the angry face and target appeared on the same side than when they appeared on different sides, whereas low socially anxious people did not exhibit such effects. On the other hand, different abilities of endogenous attention were not observed between high and low socially anxious people. These results suggest that exogenous attention is biased towards threat in high socially anxious people.

  20. Transformation of Drosophila cell lines: an alternative approach to exogenous protein expression.

    PubMed

    Cherbas, Lucy; Cherbas, Peter

    2007-01-01

    Techniques and experimental applications are described for exogenous protein expression in Drosophila cell lines. Ways in which the Drosophila cell lines and the baculovirus expression vector system differ in their applications are emphasized.

  1. Exogenously produced CO2 doubles the CO2 efflux from three north temperate lakes

    NASA Astrophysics Data System (ADS)

    Wilkinson, Grace M.; Buelo, Cal D.; Cole, Jonathan J.; Pace, Michael L.

    2016-03-01

    It is well established that lakes are typically sources of CO2 to the atmosphere. However, it remains unclear what portion of CO2 efflux is from endogenously processed organic carbon or from exogenously produced CO2 transported into lakes. We estimated high-frequency CO2 and O2 efflux from three north temperate lakes in summer to determine the proportion of the total CO2 efflux that was exogenously produced. Two of the lakes were amended with nutrients to experimentally enhance endogenous CO2 uptake. In the unfertilized lake, 50% of CO2 efflux was from exogenous sources and hydrology had a large influence on efflux. In the fertilized lakes, endogenous CO2 efflux was negative (into the lake) yet exogenous CO2 made the lakes net sources of CO2 to the atmosphere. Shifts in hydrologic regimes and nutrient loading have the potential to change whether small lakes act primarily as reactors or vents in the watershed.

  2. Quantifying the time scales over which exogenous and endogenous conditions affect soil respiration

    USDA-ARS?s Scientific Manuscript database

    Understanding how exogenous and endogenous factors and aboveground-belowground linkages modulate carbon dynamics is difficult because of influences of antecedent conditions. For example, there are variable lags between aboveground assimilation and belowground efflux, and the duration of antecedent p...

  3. The role of exogenic factors in the formation of the lunar surface

    NASA Technical Reports Server (NTRS)

    Florenskiy, K. P.; Bazilevskiy, A. T.; Ivanov, A. V.

    1977-01-01

    The formation of the surface of planetary bodies is determined by the interaction of endogenic and exogenic forces. Clarification of the mutual role of these forces is one of the most important trends in the geological sciences.

  4. Clinical breath analysis: Discriminating between human endogenous compounds and exogenous (environmental) chemical confounders

    EPA Science Inventory

    Volatile organic compounds (VOCs) in exhaled breath originate from current or previous environmental exposures (exogenous compounds) and internal metabolic anabolic and catabolic) production (endogenous compounds). The origins of certain VOCs in breath presumed to be endogenous ...

  5. [Biological activities of exogenous polysaccharides via controlling endogenous proteoglycan metabolism in vascular endothelial cells].

    PubMed

    Sato, Tomoko; Yamamoto, Chika; Fujiwara, Yasuyuki; Kaji, Toshiyuki

    2008-05-01

    Proteoglycan contains glycosmainoglycans, which are endogenous sulfated polysaccharides, in the molecule. The metabolism of proteoglycans regulates cell behavior and cellular events. It is possible that exogenous polysaccharide-related molecules exhibit their biological activities by two mechanisms. One is the interaction with cells and the other is the interaction with growth factors/cytokines that regulate proteoglycans. In this review, we describe sodium spirulan, a sulfated polysaccharide obtained from a hot-water extract of the blue-green alga Spirulina platensis, as an exogenous polysaccharide that stimulates the release of proteoglycans from vascular endothelial cells. Factors that regulate endothelial proteoglycan metabolism are also being described as possible target molecules of exogenous polysaccharides. Further research is required to obtain exogenous polysaccharide-related molecules that exhibit useful biological activities through controlling endothelial proteoglycan metabolism for protection against vascular lesions such as atheroslcerosis.

  6. An anti-Hick's effect for exogenous, but not endogenous, saccadic eye movements.

    PubMed

    Lawrence, Bonnie M

    2010-07-01

    Previously, we have shown that the reaction times (RTs) of exogenously generated saccadic eye movements decrease with an increase in the number of response alternatives (Lawrence et al. in J Vis 8(26):1-7, 2008; Lawrence and Gardella in Exp Brain Res 195(3):413-418, 2009). Because this pattern of RTs is in the direction opposite that predicted by Hick (Q J Exp Psychol 4:11-26, 1952), we termed the effect an "anti-Hick's" effect. In the present study, we examined whether this effect characterizes saccades in general, or only those saccades that are exogenously generated. An anti-Hick's effect was found for exogenous, but not for endogenous, saccades. These results demonstrate a clear dissociation between exogenously and endogenously generated saccades and place an important constraint on the anti-Hick's effect.

  7. Exogenous application of brassinosteroid offers tolerance to salinity by altering stress responses in rice variety Pusa Basmati-1.

    PubMed

    Sharma, Isha; Ching, Erwan; Saini, Shivani; Bhardwaj, Renu; Pati, Pratap Kumar

    2013-08-01

    Plant steroidal hormones, brassinosteroids, play a pivotal role in variety of plant developmental processes and adaptation to various environmental stresses. The present work investigates the response of various stress markers upon exogenous application of 24-epibrassinolide (EBL) on Pusa Basmati-1, a commercially important rice variety, under salt stress conditions. Rice seeds after treatment with different concentrations of NaCl alone or in combination with different concentrations of 24-epibrassinolide (EBL) were analysed for various growth parameters, protein, proline and malondialdehyde content (MDA) and antioxidant enzymes activities. The seedlings exposed to NaCl exhibited a significant decline in growth parameters and changes in the levels of antioxidant enzymes, however, treatment with EBL showed an improvement in growth, levels of protein and proline content and antioxidant enzymes activity. The enhanced levels of MDA content during salt stress in rice seedlings was decreased with EBL treatment. Further, the treatment with EBL increased the expression of various oxidative stress marker genes, although to different levels. Expression of various brassinosteroids (OsBRI1, OsDWF4) and salt (SalT) responsive genes, revealed the down regulation of OsDWF4 with application of EBL and upregulation of SalT in presence of salt stress thereby confirming the efficacy of the treatments. Interestingly, a significant down regulation of SalT gene was observed on application of EBL along with salt compared to salt treatment alone. On the other hand, the application of EBL alone and in combination with salt has resulted in upregulation of OsBRI1. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  8. Aminoglycoside Modifying Enzymes

    PubMed Central

    Ramirez, Maria S.; Tolmasky, Marcelo E.

    2010-01-01

    Aminoglycosides have been an essential component of the armamentarium in the treatment of life-threatening infections. Unfortunately, their efficacy has been reduced by the surge and dissemination of resistance. In some cases the levels of resistance reached the point that rendered them virtually useless. Among many known mechanisms of resistance to aminoglycosides, enzymatic modification is the most prevalent in the clinical setting. Aminoglycoside modifying enzymes catalyze the modification at different −OH or −NH2 groups of the 2-deoxystreptamine nucleus or the sugar moieties and can be nucleotidyltranferases, phosphotransferases, or acetyltransferases. The number of aminoglycoside modifying enzymes identified to date as well as the genetic environments where the coding genes are located is impressive and there is virtually no bacteria that is unable to support enzymatic resistance to aminoglycosides. Aside from the development of new aminoglycosides refractory to as many as possible modifying enzymes there are currently two main strategies being pursued to overcome the action of aminoglycoside modifying enzymes. Their successful development would extend the useful life of existing antibiotics that have proven effective in the treatment of infections. These strategies consist of the development of inhibitors of the enzymatic action or of the expression of the modifying enzymes. PMID:20833577

  9. Random-walk enzymes

    PubMed Central

    Mak, Chi H.; Pham, Phuong; Afif, Samir A.; Goodman, Myron F.

    2015-01-01

    Enzymes that rely on random walk to search for substrate targets in a heterogeneously dispersed medium can leave behind complex spatial profiles of their catalyzed conversions. The catalytic signatures of these random-walk enzymes are the result of two coupled stochastic processes: scanning and catalysis. Here we develop analytical models to understand the conversion profiles produced by these enzymes, comparing an intrusive model, in which scanning and catalysis are tightly coupled, against a loosely coupled passive model. Diagrammatic theory and path-integral solutions of these models revealed clearly distinct predictions. Comparison to experimental data from catalyzed deaminations deposited on single-stranded DNA by the enzyme activation-induced deoxycytidine deaminase (AID) demonstrates that catalysis and diffusion are strongly intertwined, where the chemical conversions give rise to new stochastic trajectories that were absent if the substrate DNA was homogeneous. The C → U deamination profiles in both analytical predictions and experiments exhibit a strong contextual dependence, where the conversion rate of each target site is strongly contingent on the identities of other surrounding targets, with the intrusive model showing an excellent fit to the data. These methods can be applied to deduce sequence-dependent catalytic signatures of other DNA modification enzymes, with potential applications to cancer, gene regulation, and epigenetics. PMID:26465508

  10. Random-walk enzymes.

    PubMed

    Mak, Chi H; Pham, Phuong; Afif, Samir A; Goodman, Myron F

    2015-09-01

    Enzymes that rely on random walk to search for substrate targets in a heterogeneously dispersed medium can leave behind complex spatial profiles of their catalyzed conversions. The catalytic signatures of these random-walk enzymes are the result of two coupled stochastic processes: scanning and catalysis. Here we develop analytical models to understand the conversion profiles produced by these enzymes, comparing an intrusive model, in which scanning and catalysis are tightly coupled, against a loosely coupled passive model. Diagrammatic theory and path-integral solutions of these models revealed clearly distinct predictions. Comparison to experimental data from catalyzed deaminations deposited on single-stranded DNA by the enzyme activation-induced deoxycytidine deaminase (AID) demonstrates that catalysis and diffusion are strongly intertwined, where the chemical conversions give rise to new stochastic trajectories that were absent if the substrate DNA was homogeneous. The C→U deamination profiles in both analytical predictions and experiments exhibit a strong contextual dependence, where the conversion rate of each target site is strongly contingent on the identities of other surrounding targets, with the intrusive model showing an excellent fit to the data. These methods can be applied to deduce sequence-dependent catalytic signatures of other DNA modification enzymes, with potential applications to cancer, gene regulation, and epigenetics.

  11. Lignin-degrading enzymes.

    PubMed

    Pollegioni, Loredano; Tonin, Fabio; Rosini, Elena

    2015-04-01

    A main goal of green biotechnology is to reduce our dependence on fossil reserves and to increase the use of renewable materials. For this, lignocellulose, which is composed of cellulose, hemicellulose and lignin, represents the most promising feedstock. The latter is a complex aromatic heteropolymer formed by radical polymerization of guaiacyl, syringyl, and p-hydroxyphenyl units linked by β-aryl ether linkages, biphenyl bonds and heterocyclic linkages. Accordingly, lignin appears to be a potentially valuable renewable aromatic chemical, thus representing a main pillar in future biorefinery. The resistance of lignin to breakdown is the main bottleneck in this process, although a variety of white-rot fungi, as well as bacteria, have been reported to degrade lignin by employing different enzymes and catabolic pathways. Here, recent investigations have expanded the range of natural biocatalysts involved in lignin degradation/modification and significant progress related to enzyme engineering and recombinant expression has been made. The present review is focused primarily on recent trends in ligninolytic green biotechnology to suggest the potential (industrial) application of ligninolytic enzymes. Future perspectives could include synergy between natural enzymes from different sources (as well as those obtained by protein engineering) and other pretreatment methods that may be required for optimal results in enzyme-based, environmentally friendly, technologies.

  12. Random-walk enzymes

    NASA Astrophysics Data System (ADS)

    Mak, Chi H.; Pham, Phuong; Afif, Samir A.; Goodman, Myron F.

    2015-09-01

    Enzymes that rely on random walk to search for substrate targets in a heterogeneously dispersed medium can leave behind complex spatial profiles of their catalyzed conversions. The catalytic signatures of these random-walk enzymes are the result of two coupled stochastic processes: scanning and catalysis. Here we develop analytical models to understand the conversion profiles produced by these enzymes, comparing an intrusive model, in which scanning and catalysis are tightly coupled, against a loosely coupled passive model. Diagrammatic theory and path-integral solutions of these models revealed clearly distinct predictions. Comparison to experimental data from catalyzed deaminations deposited on single-stranded DNA by the enzyme activation-induced deoxycytidine deaminase (AID) demonstrates that catalysis and diffusion are strongly intertwined, where the chemical conversions give rise to new stochastic trajectories that were absent if the substrate DNA was homogeneous. The C →U deamination profiles in both analytical predictions and experiments exhibit a strong contextual dependence, where the conversion rate of each target site is strongly contingent on the identities of other surrounding targets, with the intrusive model showing an excellent fit to the data. These methods can be applied to deduce sequence-dependent catalytic signatures of other DNA modification enzymes, with potential applications to cancer, gene regulation, and epigenetics.

  13. Investigations into the differential reactivity of endogenous and exogenous mercury species in coastal sediments.

    PubMed

    Bouchet, S; Rodriguez-Gonzalez, P; Bridou, R; Monperrus, M; Tessier, E; Anschutz, P; Guyoneaud, R; Amouroux, D

    2013-03-01

    Stable isotopic tracer methodologies now allow the evaluation of the reactivity of the endogenous (ambient) and exogenous (added) Hg to further predict the potential effect of Hg inputs in ecosystems. The differential reactivity of endogenous and exogenous Hg was compared in superficial sediments collected in a coastal lagoon (Arcachon Bay) and in an estuary (Adour River) from the Bay of Biscay (SW France). All Hg species (gaseous, aqueous, and solid fraction) and ancillary data were measured during time course slurry experiments under variable redox conditions. The average endogenous methylation yield was higher in the estuarine (1.2 %) than in the lagoonal sediment (0.5 %), although both methylation and demethylation rates were higher in the lagoonal sediment in relation with a higher sulfate-reducing activity. Demethylation was overall more consistent than methylation in both sediments. The endogenous and exogenous Hg behaviors were always correlated but the exogenous inorganic Hg (IHg) partitioning into water was 2.0-4.3 times higher than the endogenous one. Its methylation was just slightly higher (1.4) in the estuarine sediment while the difference in the lagoonal sediment was much larger (3.6). The relative endogenous and exogenous methylation yields were not correlated to IHg partitioning, demonstrating that the bioavailable species distributions were different for the two IHg pools. In both sediments, the exogenous IHg partitioning equaled the endogenous one within a week, while its higher methylation lasted for months. Such results provide an original assessment approach to compare coastal sediment response to Hg inputs.

  14. Pinocytosis and intracellular degradation of exogenous protein: modulation by amino acids

    PubMed Central

    1983-01-01

    Intracellular degradation of exogenous (serum) proteins provides a source of amino acids for cellular protein synthesis. Pinocytosis serves as the mechanism for delivering exogenous protein to the lysosomes, the major site of intracellular degradation of exogenous protein. To determine whether the availability of extracellular free amino acids altered pinocytic function, we incubated monolayers of pulmonary alveolar macrophages with the fluid-phase marker, [14C]sucrose, and we dissected the pinocytic process by kinetic analysis. Additionally, intracellular degradation of endogenous and exogenous protein was monitored by measuring phenylalanine released from the cell monolayers in the presence of cycloheximide. Results revealed that in response to a subphysiological level of essential amino acids or to amino acid deprivation, (a) the rate of fluid-phase pinocytosis increased in such a manner as to preferentially increase both delivery to and size of an intracellular compartment believed to be the lysosomes, (b) the degradation of exogenously supplied albumin increased, and (c) the fraction of phenylalanine derived from degradation of exogenous albumin and reutilized for de novo protein synthesis increased. Thus, modulation of the pinosome-lysosome pathway may represent a homeostatic mechanism sensitive to the availability of extracellular free amino acids. PMID:6853596

  15. [Adsorption behavior of exogenous thorium on soil contaminated by rare earth industries].

    PubMed

    Guo, Peng-ran; Jia, Xiao-yu; Duan, Tai-cheng; Qiu, Rong-liang; Chen, Hang-ting

    2009-10-15

    The adsorption behavior of exogenous thorium on soil was studied to evaluate the contaminated risk on soil. The adsorption capacity, equilibrium time, distribution coefficient and desorption ability were investigated by the experiments of static adsorption. The strong adsorption ability of exogenous thorium on soil samples was observed by high adsorption ratio (> 92%) and low desorption ratio (< 5%) in equilibrium, and the biggest distribution coefficient was over 10(4). The adsorption capacity and equilibrium time were related to soil properties. According to the results of adsorption, Freundlich equation (r > or = 0.9167) and Elovich equation (R2 > or = 0.8980) were primely fit for describing the thermodynamics and kinetics of the adsorption of exogenous thorium on soil samples, respectively, which indicated that the adsorption was belonged to the nonlinear adsorption, and was affected by the diffusion of thorium on soil surface and in mineral interbed. Sequential extraction procedure was employed to evaluate the bound fractions of exogenous thorium adsorbed on soil samples. Based on the extracted results of thorium fractions, exogenous thorium was presented in the labile nonresidual fractions (over 58%) at the low initial concentration (10(-7) - 10(-6) mol x L(-1)), and nonresidual fractions enhanced with the increase of the initial amount, meanwhile more exogenous throium was transferred to the stable residual fractions.

  16. Effects of exogenous glucose on carotenoid accumulation in tomato leaves.

    PubMed

    Mortain-Bertrand, Anne; Stammitti, Linda; Telef, Nadège; Colardelle, Patrice; Brouquisse, Renaud; Rolin, Dominique; Gallusci, Philippe

    2008-10-01

    To investigate the effect of carbohydrate on carotenoid accumulation in leaves, excised plants of tomato (Lycopersicum esculentum var. cerasiformae, wva 106) were supplied with glucose through the transpiration stream for 48 h. We report here that sugar accumulation in leaves led to a decrease of carotenoid content, which was related to the reduction of Chl. The decrease in carotenoid amount correlated with a sugar-induced repression of genes encoding enzymes of the carotenoid and of the Rohmer pathways. The lower 1-deoxy-D-xylulose-5-phosphate synthase transcript level probably leads to a decreased metabolic flux through the methylerythritol pathway and subsequently to a lower amount of substrate available for plastidic isoprenoid synthesis. Differences between responses of young (sink) and mature (source) leaves to carbohydrate accumulation are discussed.

  17. Effect of exogenous selenium on nicotine induced hyperlipidemia in rats.

    PubMed

    Sreekala, S; Indira, M

    2008-01-01

    The effect of two different doses (1 microg Se/Kg and 50 microg Se/Kg Body wt) of selenium on nicotine induced hyperlipidemia was investigated in rats. Results revealed that nicotine intake caused an increase in concentration of cholesterol, triglycerides, free fatty acids, phospholipids and low density lipoprotein compared to control group. Coadministration of selenium along with nicotine reduced the levels of lipids compared to nicotine group. This reduction was due to reduction in the biosynthesis of lipids as evidenced by the reduced activity of HMGCoA reductase and lipogenic enzymes. Nicotine intake also reduced the absorption of selenium in the intestine. Histopathological studies revealed that selenium at a dose of 1 microg was more effective in reducing lipid levels and higher dose of selenium was toxic.

  18. Enzyme immunoassay for methamphetamine.

    PubMed

    Aoki, K; Kuroiwa, Y

    1983-01-01

    A competitive enzyme immunoassay for methamphetamine with alkaline phosphatase labeled methamphetamine, Sepharose-antibody and p-nitrophenylphosphate as substrate was developed. The anti-methamphetamine antisera produced in rabbits by immunization with N-(4-aminobutyl) methamphetamine-BSA conjugate were specific for methamphetamine and showed low cross-reactivities with p-OH methamphetamine and amphetamine (metabolites of methamphetamine). The range of methamphetamine measurable by the enzyme immunoassay was 1 to 300 ng/tube. According to the assay, methamphetamine could be detected from urine and extract of hair.

  19. Evolution of enzyme superfamilies.

    PubMed

    Glasner, Margaret E; Gerlt, John A; Babbitt, Patricia C

    2006-10-01

    Enzyme evolution is often constrained by aspects of catalysis. Sets of homologous proteins that catalyze different overall reactions but share an aspect of catalysis, such as a common partial reaction, are called mechanistically diverse superfamilies. The common mechanistic steps and structural characteristics of several of these superfamilies, including the enolase, Nudix, amidohydrolase, and haloacid dehalogenase superfamilies have been characterized. In addition, studies of mechanistically diverse superfamilies are helping to elucidate mechanisms of functional diversification, such as catalytic promiscuity. Understanding how enzyme superfamilies evolve is vital for accurate genome annotation, predicting protein functions, and protein engineering.

  20. Entropy and Enzyme Catalysis.

    PubMed

    Åqvist, Johan; Kazemi, Masoud; Isaksen, Geir Villy; Brandsdal, Bjørn Olav

    2017-02-21

    The role played by entropy for the enormous rate enhancement achieved by enzymes has been debated for many decades. There are, for example, several confirmed cases where the activation free energy is reduced by around 10 kcal/mol due to entropic effects, corresponding to a rate enhancement of ∼10(7) compared to the uncatalyzed reaction. However, despite substantial efforts from both the experimental and theoretical side, no real consensus has been reached regarding the origin of such large entropic contributions to enzyme catalysis. Another remarkable instance of entropic effects is found in enzymes that are adapted by evolution to work at low temperatures, near the freezing point of water. These cold-adapted enzymes invariably show a more negative entropy and a lower enthalpy of activation than their mesophilic orthologs, which counteracts the exponential damping of reaction rates at lower temperature. The structural origin of this universal phenomenon has, however, remained elusive. The basic problem with connecting macroscopic thermodynamic quantities, such as activation entropy and enthalpy derived from Arrhenius plots, to the 3D protein structure is that the underlying detailed (microscopic) energetics is essentially inaccessible to experiment. Moreover, attempts to calculate entropy contributions by computer simulations have mostly focused only on substrate entropies, which do not provide the full picture. We have recently devised a new approach for accessing thermodynamic activation parameters of both enzyme and solution reactions from computer simulations, which turns out to be very successful. This method is analogous to the experimental Arrhenius plots and directly evaluates the temperature dependence of calculated reaction free energy profiles. Hence, by extensive molecular dynamics simulations and calculations of up to thousands of independent free energy profiles, we are able to extract activation parameters with sufficient precision for making

  1. [Micro fabricated enzyme battery].

    PubMed

    Sasaki, S; Karube, I

    1996-10-01

    Although various work has been done in the field of implantable micro actuators such as artificial organs and micro surgery robots, a suitable electric power supply for these is yet to be developed. For this purpose a micro fabricated enzyme fuel cell was developed which uses glucose contained in the human body as a fuel. In order to obtain enough voltage each cell was formed as part of a serial array on a silicon wafer. Glucose solution enters the cells by a capillary effect. In this article fuel cells already developed using biocatalysts are described, and the future possibility of a micro fabricated enzyme battery is discussed.

  2. Effect of phenolic monomers on biomass and hydrolytic enzyme activities of an anaerobic fungus isolated from wild nil gai (Baselophus tragocamelus).

    PubMed

    Paul, S S; Kamra, D N; Sastry, V R B; Sahu, N P; Kumar, A

    2003-01-01

    To test the anaerobic fungus, Piromyces sp. FNG5, for its tolerance to phenolic monomers released in the rumen by degradation of lignocellulosic poor-quality feeds. Effects of phenolic monomers on biomass and fibrolytic enzyme activities of a pure culture of lignocellulolytic anaerobic fungus (Piromyces sp. FNG5) isolated from faeces of wild nil gai (blue bull, Baselophus tragocamelus) were evaluated. There was a reduction in fungal biomass at 1 mm concentration of catechol with complete inhibition at 10 mm. p-Coumaric acid caused a reduction in biomass at 10 mm and no growth was observed above 20 mm concentration. The fungal isolate could tolerate up to 5 mm of ferulic acid without any reduction in biomass level, and was able to grow to some extent up to the highest level of ferulic acid tested (20 mm). Vanillic acid had no effect on biomass of the fungus even up to 50 mm level. The phenolic monomers varied in their potential to inhibit the secretion of carboxymethyl cellulase, xylanase, beta-glucosidase and acetyl esterase activities with catechol being the most inhibitory and vanillic acid being the least inhibitory. After 14 days of incubation, 38.49-65.14%p-Coumaric acid, 65.22-74.10% ferulic acid and 34.13-66.78% vanillic acid disappeared from the medium under anaerobic conditions. It is concluded that the anaerobic fungus Piromyces sp. FNG5 is tolerant to phenolic monomers and has ability to degrade them. Therefore, such anaerobic fungi may play an important role in fibre degradation in the rumen.

  3. Transcriptome profiling shows gene regulation patterns in a flavonoid pathway in response to exogenous phenylalanine in Boesenbergia rotunda cell culture.

    PubMed

    Md-Mustafa, Noor Diyana; Khalid, Norzulaani; Gao, Huan; Peng, Zhiyu; Alimin, Mohd Firdaus; Bujang, Noraini; Ming, Wong Sher; Mohd-Yusuf, Yusmin; Harikrishna, Jennifer A; Othman, Rofina Yasmin

    2014-11-18

    Panduratin A extracted from Boesenbergia rotunda is a flavonoid reported to possess a range of medicinal indications which include anti-dengue, anti-HIV, anti-cancer, antioxidant and anti-inflammatory properties. Boesenbergia rotunda is a plant from the Zingiberaceae family commonly used as a food ingredient and traditional medicine in Southeast Asia and China. Reports on the health benefits of secondary metabolites extracted from Boesenbergia rotunda over the last few years has resulted in rising demands for panduratin A. However large scale extraction has been hindered by the naturally low abundance of the compound and limited knowledge of its biosynthetic pathway. Transcriptome sequencing and digital gene expression (DGE) analysis of native and phenylalanine treated Boesenbergia rotunda cell suspension cultures were carried out to elucidate the key genes differentially expressed in the panduratin A biosynthetic pathway. Based on experiments that show increase in panduratin A production after 14 days post treatment with exogenous phenylalanine, an aromatic amino acid derived from the shikimic acid pathway, total RNA of untreated and 14 days post-phenylalanine treated cell suspension cultures were extracted and sequenced using next generation sequencing technology employing an Illumina-Solexa platform. The transcriptome data generated 101, 043 unigenes with 50, 932 (50.41%) successfully annotated in the public protein databases; including 49.93% (50, 447) in the non-redundant (NR) database, 34.63% (34, 989) in Swiss-Prot, 24,07% (24, 316) in Kyoto Encyclopedia of Genes and Genomes (KEGG) and 16.26% (16, 426) in Clusters of Orthologous Groups (COG). Through DGE analysis, we found that 14, 644 unigenes were up-regulated and 14, 379 unigenes down-regulated in response to exogenous phenylalanine treatment. In the phenylpropanoid pathway leading to the proposed panduratin A production, 2 up-regulated phenylalanine ammonia-lyase (PAL), 3 up-regulated 4-coumaroyl

  4. The effect of exogenous melatonin during the non-reproductive season on the seminal plasma hormonal profile and the antioxidant defence system of Rasa Aragonesa rams.

    PubMed

    Casao, Adriana; Pérez-Pé, Rosaura; Abecia, José Alfonso; Forcada, Fernando; Muiño-Blanco, Teresa; Cebrián-Pérez, José Álvaro

    2013-05-01

    The aim of this study was to analyze the effect of melatonin implants, during the non-reproductive season, on the content of melatonin, testosterone and 17-β estradiol levels, and the antioxidant enzymes glutathione peroxidase, glutathione reductase, superoxide dismutase and catalase of seminal plasma in Rasa Aragonesa rams. Five rams were implanted with melatonin, and four others were used as a control group. Seminal plasma was separated from ejaculates collected one week before melatonin treatment until 21 weeks after melatonin placement, and the hormonal levels and the antioxidant enzyme activity were determined. Exogenous melatonin treatment significantly (P<0.05) increased the levels of endogenous melatonin in seminal plasma immediately, and this effect lasted for 14 weeks. Testosterone and 17-β estradiol levels significantly (P<0.05) increased four and eight weeks after melatonin treatment, respectively. As regards the antioxidant enzymes, melatonin treatment significantly increased (P<0.05) glutathione peroxidase and glutathione reductase activity only, and had no effect on superoxide dismutase and catalase. Therefore, melatonin treatment during the non-breeding season modifies the seminal plasma hormonal profile and some antioxidant enzyme activity in Rasa Aragonesa rams. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Enzyme kinetics in drug metabolism: fundamentals and applications.

    PubMed

    Nagar, Swati; Argikar, Upendra A; Tweedie, Donald J

    2014-01-01

    Enzymes are protein catalysts that lower the energy barrier for a reaction and speed the rate of a chemical change. The kinetics of reactions catalyzed by enzymes, as well as several mechanisms underlying the kinetics, have been comprehensively studied and written in textbooks (1, 2). The importance of quantitative evaluation of enzymatic processes has been recognized in many fields of study, including biochemistry, molecular biology, and pharmaceutical sciences to name a few. In pharmaceutical sciences, the applications of enzyme kinetics range from hit finding efforts for new chemical entities on a pharmacological target to concentration effect relationships to large-scale biosynthesis. The study of the science of drug metabolism has two principal concepts-rate and extent. While understanding disposition pathways and identification of metabolites provides an insight into the extent of metabolism, kinetics of depletion of substrates (endogenous or exogenous) and formation of metabolites deals with the rate of metabolism. The current textbook specifically focuses on kinetics of drug-metabolizing enzymes, detailing specific enzyme classes, and discusses kinetics as they apply to drug transporters. This textbook also outlines additional factors that contribute to the kinetics of reactions catalyzed by these proteins such as variability in isoforms (pharmacogenomics) and experimental factors including key concepts such as alterations of substrate concentrations due to binding. Applications of these approaches in predicting kinetic parameters and alternative approaches for enzymes (systems biology) and transporters are also discussed. The final section focuses on real-life examples (case studies) to try and exemplify the applications of enzyme kinetic principles. This chapter provides a brief overview outlining some key concepts within each of the sections and the chapters within this textbook.

  6. Synthetic Helizyme Enzymes

    DTIC Science & Technology

    1989-08-18

    Enzymes START DATE: 1 August 1986; END DATE: 31 July 1989 RESEARCH OBSCTE: The goal of this project as to design, synthesize and test totally new...the peptide from the resin by HF. Coupling reactions were monitored at nearly all steps using qualitative and quantitative ninhydrin reactions

  7. Amperometric Enzyme Electrodes

    DTIC Science & Technology

    1989-12-01

    and C. Lyons. "Electrode systems for continuous monitoring in cardiomuscula murgery," Ann. NY Acad. Sci.. 102 (1962). 20-45. [6]. 1. J. Updike mid G...Chemistry, John Wiley & Sons: New York (1980). 197-236. [2]. L D. Mell and J. T. Maloy, "A Model for the Amperometric Enzyme Electrode Obtained through

  8. Quorum quenching enzymes.

    PubMed

    Fetzner, Susanne

    2015-05-10

    Bacteria use cell-to-cell communication systems based on chemical signal molecules to coordinate their behavior within the population. These quorum sensing systems are potential targets for antivirulence therapies, because many bacterial pathogens control the expression of virulence factors via quorum sensing networks. Since biofilm maturation is also usually influenced by quorum sensing, quenching these systems may contribute to combat biofouling. One possibility to interfere with quorum sensing is signal inactivation by enzymatic degradation or modification. Such quorum quenching enzymes are wide-spread in the bacterial world and have also been found in eukaryotes. Lactonases and acylases that hydrolyze N-acyl homoserine lactone (AHL) signaling molecules have been investigated most intensively, however, different oxidoreductases active toward AHLs or 2-alkyl-4(1H)-quinolone signals as well as other signal-converting enzymes have been described. Several approaches have been assessed which aim at alleviating virulence, or biofilm formation, by reducing the signal concentration in the bacterial environment. These involve the application or stimulation of signal-degrading bacteria as biocontrol agents in the protection of crop plants against soft-rot disease, the use of signal-degrading bacteria as probiotics in aquaculture, and the immobilization or entrapment of quorum quenching enzymes or bacteria to control biofouling in membrane bioreactors. While most approaches to use quorum quenching as antivirulence strategy are still in the research phase, the growing number of organisms and enzymes known to interfere with quorum sensing opens up new perspectives for the development of innovative antibacterial strategies.

  9. Photoperiodism and Enzyme Activity

    PubMed Central

    Queiroz, Orlando; Morel, Claudine

    1974-01-01

    Metabolic readjustments after a change from long days to short days appear, in Kalanchoe blossfeldiana, to be achieved through the operation of two main mechanisms: variation in enzyme capacity, and circadian rhythmicity. After a lag time, capacity in phosphoenolpyruvate carboxylase and capacity in aspartate aminotransferase increase exponentially and appear to be allometrically linked during 50 to 60 short days; then a sudden fall takes place in the activity of the former. Malic enzyme and alanine aminotransferase behave differently. Thus, the operation of the two sections of the pathway (before and after the malate step) give rise to a continuously changing functional compartmentation in the pathway. Circadian rhythmicity, on the other hand, produces time compartmentation through phase shifts and variation in amplitude, independently for each enzyme. These characteristics suggest that the operation of a so-called biological clock would be involved. We propose the hypothesis that feedback regulation would be more accurate and efficient when applied to an already oscillating, clock-controlled enzyme system. PMID:16658749

  10. Cold-Adapted Enzymes

    NASA Astrophysics Data System (ADS)

    Georlette, D.; Bentahir, M.; Claverie, P.; Collins, T.; D'amico, S.; Delille, D.; Feller, G.; Gratia, E.; Hoyoux, A.; Lonhienne, T.; Meuwis, M.-a.; Zecchinon, L.; Gerday, Ch.

    In the last few years, increased attention has been focused on enzymes produced by cold-adapted micro-organisms. It has emerged that psychrophilic enzymes represent an extremely powerful tool in both protein folding investigations and for biotechnological purposes. Such enzymes are characterised by an increased thermosensitivity and, most of them, by a higher catalytic efficiency at low and moderate temperatures, when compared to their mesophilic counterparts. The high thermosensitivity probably originates from an increased flexibility of either a selected area of the molecular edifice or the overall protein structure, providing enhanced abilities to undergo conformational changes during catalysis at low temperatures. Structure modelling and recent crystallographic data have allowed to elucidate the structural parameters that could be involved in this higher resilience. It was demonstrated that each psychrophilic enzyme adopts its own adaptive strategy. It appears, moreover, that there is a continuum in the strategy of protein adaptation to temperature, as the previously mentioned structural parameters are implicated in the stability of thermophilic proteins. Additional 3D crystal structures, site-directed and random mutagenesis experiments should now be undertaken to further investigate the stability-flexibility-activity relationship.

  11. Toying with Enzyme Catalysis.

    ERIC Educational Resources Information Center

    Richards, Debbie

    1998-01-01

    Describes a set of manipulatives that are used to establish a secure understanding of the concepts related to the environmental factors that affect the activities of enzymes. Includes a description of the model components and procedures for construction of the model. (DDR)

  12. Computational enzyme design

    NASA Astrophysics Data System (ADS)

    Bolon, Daniel N.

    2002-08-01

    The long-term objective of computational enzyme design is the ability to generate efficient protein catalysts for any chemical reaction. This thesis develops and experimentally validates a general computational approach for the design of enzymes with novel function. In order to include catalytic mechanism in protein design, a high-energy state (HES) rotamer (side chain representation) was constructed. In this rotamer, substrate atoms are in a HES. In addition, at least one amino acid side chain is positioned to interact favorably with substrate atoms in their HES and facilitate the reaction. Including an amino acid side chain in the HES rotamer automatically positions substrate relative to a protein scaffold and allows protein design algorithms to search for sequences capable of interacting favorably with the substrate. Because chemical similarity exists between the transition state and the high-energy state, optimizing the protein sequence to interact favorably with the HES rotamer should lead to transition state stabilization. In addition, the HES rotamer model focuses the subsequent computational active site design on a relevant phase space where an amino acid is capable of interacting in a catalytically active geometry with substrate. Using a HES rotamer model of the histidine mediated nucleophilic hydrolysis of p-nitrophenyl acetate, the catalytically inert 108 residue E. coli thioredoxin as a scaffold, and the ORBIT protein design software to compute sequences, an active site scan identified two promising active site designs. Experimentally, both candidate ?protozymes? demonstrated catalytic activity significantly above background. In addition, the rate enhancement of one of these ?protozymes? was the same order of magnitude as the first catalytic antibodies. Because polar groups are frequently buried at enzyme-substrate interfaces, improved modeling of buried polar interactions may benefit enzyme design. By studying native protein structures, rules have been

  13. Differential effects of exogenous and endogenous attention on second-order texture contrast sensitivity

    PubMed Central

    Barbot, Antoine; Landy, Michael S.; Carrasco, Marisa

    2012-01-01

    The visual system can use a rich variety of contours to segment visual scenes into distinct perceptually coherent regions. However, successfully segmenting an image is a computationally expensive process. Previously we have shown that exogenous attention—the more automatic, stimulus-driven component of spatial attention—helps extract contours by enhancing contrast sensitivity for second-order, texture-defined patterns at the attended location, while reducing sensitivity at unattended locations, relative to a neutral condition. Interestingly, the effects of exogenous attention depended on the second-order spatial frequency of the stimulus. At parafoveal locations, attention enhanced second-order contrast sensitivity to relatively high, but not to low second-order spatial frequencies. In the present study we investigated whether endogenous attention—the more voluntary, conceptually-driven component of spatial attention—affects second-order contrast sensitivity, and if so, whether its effects are similar to those of exogenous attention. To that end, we compared the effects of exogenous and endogenous attention on the sensitivity to second-order, orientation-defined, texture patterns of either high or low second-order spatial frequencies. The results show that, like exogenous attention, endogenous attention enhances second-order contrast sensitivity at the attended location and reduces it at unattended locations. However, whereas the effects of exogenous attention are a function of the second-order spatial frequency content, endogenous attention affected second-order contrast sensitivity independent of the second-order spatial frequency content. This finding supports the notion that both exogenous and endogenous attention can affect second-order contrast sensitivity, but that endogenous attention is more flexible, benefitting performance under different conditions. PMID:22895879

  14. Elongator Plays a Positive Role in Exogenous NAD-Induced Defense Responses in Arabidopsis.

    PubMed

    An, Chuanfu; Ding, Yezhang; Zhang, Xudong; Wang, Chenggang; Mou, Zhonglin

    2016-05-01

    Extracellular NAD is emerging as an important signal molecule in animal cells, but its role in plants has not been well-established. Although it has been shown that exogenous NAD(+) activates defense responses in Arabidopsis, components in the exogenous NAD(+)-activated defense pathway remain to be fully discovered. In a genetic screen for mutants insensitive to exogenous NAD(+) (ien), we isolated a mutant named ien2. Map-based cloning revealed that IEN2 encodes ELONGATA3 (ELO3)/AtELP3, a subunit of the Arabidopsis Elongator complex, which functions in multiple biological processes, including histone modification, DNA (de)methylation, and transfer RNA modification. Mutations in the ELO3/AtELP3 gene compromise exogenous NAD(+)-induced expression of pathogenesis-related (PR) genes and resistance to the bacterial pathogen Pseudomonas syringae pv. maculicola ES4326, and transgenic expression of the coding region of ELO3/AtELP3 in elo3/Atelp3 restores NAD(+) responsiveness to the mutant plants, demonstrating that ELO3/AtELP3 is required for exogenous NAD(+)-induced defense responses. Furthermore, mutations in genes encoding the other five Arabidopsis Elongator subunits (ELO2/AtELP1, AtELP2, ELO1/AtELP4, AtELP5, and AtELP6) also compromise exogenous NAD(+)-induced PR gene expression and resistance to P. syringae pv. maculicola ES4326. These results indicate that the Elongator complex functions as a whole in exogenous NAD(+)-activated defense signaling in Arabidopsis.

  15. Peroxisomal bifunctional enzyme deficiency.

    PubMed Central

    Watkins, P A; Chen, W W; Harris, C J; Hoefler, G; Hoefler, S; Blake, D C; Balfe, A; Kelley, R I; Moser, A B; Beard, M E

    1989-01-01

    Peroxisomal function was evaluated in a male infant with clinical features of neonatal adrenoleukodystrophy. Very long chain fatty acid levels were elevated in both plasma and fibroblasts, and beta-oxidation of very long chain fatty acids in cultured fibroblasts was significantly impaired. Although the level of the bile acid intermediate trihydroxycoprostanoic acid was slightly elevated in plasma, phytanic acid and L-pipecolic acid levels were normal, as was plasmalogen synthesis in cultured fibroblasts. The latter three parameters distinguish this case from classical neonatal adrenoleukodystrophy. In addition, electron microscopy and catalase subcellular distribution studies revealed that, in contrast to neonatal adrenoleukodystrophy, peroxisomes were present in the patient's tissues. Immunoblot studies of peroxisomal beta-oxidation enzymes revealed that the bifunctional enzyme (enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase) was deficient in postmortem liver samples, whereas acyl-CoA oxidase and the mature form of beta-ketothiolase were present. Density gradient centrifugation of fibroblast homogenates confirmed that intact peroxisomes were present. Immunoblots of fibroblasts peroxisomal fractions showed that they contained acyl-CoA oxidase and beta-ketothiolase, but bifunctional enzyme was not detected. Northern analysis, however, revealed that mRNA coding for the bifunctional enzyme was present in the patient's fibroblasts. These results indicate that the primary biochemical defect in this patient is a deficiency of peroxisomal bifunctional enzyme. It is of interest that the phenotype of this patient resembled neonatal adrenoleukodystrophy and would not have been distinguished from this disorder by clinical study alone. Images PMID:2921319

  16. The Enzyme Function Initiative†

    PubMed Central

    Gerlt, John A.; Allen, Karen N.; Almo, Steven C.; Armstrong, Richard N.; Babbitt, Patricia C.; Cronan, John E.; Dunaway-Mariano, Debra; Imker, Heidi J.; Jacobson, Matthew P.; Minor, Wladek; Poulter, C. Dale; Raushel, Frank M.; Sali, Andrej; Shoichet, Brian K.; Sweedler, Jonathan V.

    2011-01-01

    The Enzyme Function Initiative (EFI) was recently established to address the challenge of assigning reliable functions to enzymes discovered in bacterial genome projects; in this Current Topic we review the structure and operations of the EFI. The EFI includes the Superfamily/Genome, Protein, Structure, Computation, and Data/Dissemination Cores that provide the infrastructure for reliably predicting the in vitro functions of unknown enzymes. The initial targets for functional assignment are selected from five functionally diverse superfamilies (amidohydrolase, enolase, glutathione transferase, haloalkanoic acid dehalogenase, and isoprenoid synthase), with five superfamily-specific Bridging Projects experimentally testing the predicted in vitro enzymatic activities. The EFI also includes the Microbiology Core that evaluates the in vivo context of in vitro enzymatic functions and confirms the functional predictions of the EFI. The deliverables of the EFI to the scientific community include: 1) development of a large-scale, multidisciplinary sequence/structure-based strategy for functional assignment of unknown enzymes discovered in genome projects (target selection, protein production, structure determination, computation, experimental enzymology, microbiology, and structure-based annotation); 2) dissemination of the strategy to the community via publications, collaborations, workshops, and symposia; 3) computational and bioinformatic tools for using the strategy; 4) provision of experimental protocols and/or reagents for enzyme production and characterization; and 5) dissemination of data via the EFI’s website, enzymefunction.org. The realization of multidisciplinary strategies for functional assignment will begin to define the full metabolic diversity that exists in nature and will impact basic biochemical and evolutionary understanding, as well as a wide range of applications of central importance to industrial, medicinal and pharmaceutical efforts. PMID

  17. Monitoring enzyme kinetic behavior of enzyme-quantum dot bioconjugates

    NASA Astrophysics Data System (ADS)

    Claussen, Jonathan C.; Walper, Scott A.; Susumu, Kimihiro; Ancona, Mario G.; Medintz, Igor L.

    2014-05-01

    Luminescent semiconductor nanocrystals or quantum dots (QDs) hold tremendous promise for in vivo biosensing, cellular imaging, theranostics, and smart molecular sensing probes due to their small size and favorable photonic properties such as resistance to photobleaching, size-tunable PL, and large effective Stokes shifts. Herein, we demonstrate how QD-based bioconjugates can be used to enhance enzyme kinetics. Enzyme-substrate kinetics are analyzed for solutions containing both alkaline phosphatase enzymes and QDs with enzyme-to- QD molar ratios of 2, 12, and 24 as well as for a solution containing the same concentration of enzymes but without QDs. The enzyme kinetic paramters Vmax, KM, and Kcat/KM are extracted from the enzyme progress curves via the Lineweaver-Burk plot. Results demonstrate an approximate increase in enzyme efficiency of 5 - 8% for enzymes immobilized on the QD versus free in solution without QD immobilization.

  18. The Moderately Efficient Enzyme: Futile Encounters and Enzyme Floppiness.

    PubMed

    Bar-Even, Arren; Milo, Ron; Noor, Elad; Tawfik, Dan S

    2015-08-18

    The pioneering model of Henri, Michaelis, and Menten was based on the fast equilibrium assumption: the substrate binds its enzyme reversibly, and substrate dissociation is much faster than product formation. Here, we examine this assumption from a somewhat different point of view, asking what fraction of enzyme-substrate complexes are futile, i.e., result in dissociation rather than product formation. In Knowles' notion of a "perfect" enzyme, all encounters of the enzyme with its substrate result in conversion to product. Thus, the perfect enzyme's catalytic efficiency, kcat/KM, is constrained by only the diffusion on-rate, and the fraction of futile encounters (defined as φ) approaches zero. The available data on >1000 different enzymes suggest that for ≥90% of enzymes φ > 0.99 and for the "average enzyme" φ ≥ 0.9999; namely, <1 of 10(4) encounters is productive. Thus, the "fast equilibrium" assumption holds for the vast majority of enzymes. We discuss possible molecular origins for the dominance of futile encounters, including the coexistence of multiple sub-states of an enzyme's active site (enzyme floppiness) and/or its substrate. Floppiness relates to the inherent flexibility of proteins, but also to conflicting demands, or trade-offs, between rate acceleration (the rate-determining chemical step) and catalytic turnover, or between turnover rate and accuracy. The study of futile encounters and active-site floppiness may contribute to a better understanding of enzyme catalysis, enzyme evolution, and improved enzyme design.

  19. Efficient production and evaluation of lignocellulolytic enzymes using a constitutive protein expression system in Penicillium oxalicum.

    PubMed

    Hu, Yibo; Xue, Haizhao; Liu, Guodong; Song, Xin; Qu, Yinbo

    2015-06-01

    Native lignocellulolytic enzyme systems secreted by filamentous fungi can be further optimized by protein engineering or supplementation of exogenous enzyme components. We developed a protein production and evaluation system in cellulase-producing fungus Penicillium oxalicum. First, by deleting the major amylase gene amy15A, a strain Δ15A producing few extracellular proteins on starch was constructed. Then, three lignocellulolytic enzymes (BGL4, Xyn10B, and Cel12A) with originally low expression levels were successfully expressed with selected constitutive promoters in strain Δ15A. BGL4 and Cel12A overexpression resulted in increased specific filter paper activity (FPA), while the overexpression of Xyn10B improved volumetric FPA but not specific FPA. By switching the culture medium, this platform is convenient to produce originally low-expressed lignocellulolytic enzymes in relatively high purities on starch and to evaluate the effect of their supplementation on the performance of a complex cellulase system on cellulose.

  20. An Exogenous Surfactant-Producing Bacillus subtilis Facilitates Indigenous Microbial Enhanced Oil Recovery.

    PubMed

    Gao, Peike; Li, Guoqiang; Li, Yanshu; Li, Yan; Tian, Huimei; Wang, Yansen; Zhou, Jiefang; Ma, Ting

    2016-01-01

    This study used an exogenous lipopeptide-producing Bacillus subtilis to strengthen the indigenous microbial enhanced oil recovery (IMEOR) process in a water-flooded reservoir in the laboratory. The microbial processes and driving mechanisms were investigated in terms of the changes in oil properties and the interplay between the exogenous B. subtilis and indigenous microbial populations. The exogenous B. subtilis is a lipopeptide producer, with a short growth cycle and no oil-degrading ability. The B. subtilis facilitates the IMEOR process through improving oil emulsification and accelerating microbial growth with oil as the carbon source. Microbial community studies using quantitative PCR and high-throughput sequencing revealed that the exogenous B. subtilis could live together with reservoir microbial populations, and did not exert an observable inhibitory effect on the indigenous microbial populations during nutrient stimulation. Core-flooding tests showed that the combined exogenous and indigenous microbial flooding increased oil displacement efficiency by 16.71%, compared with 7.59% in the control where only nutrients were added, demonstrating the application potential in enhanced oil recovery in water-flooded reservoirs, in particular, for reservoirs where IMEOR treatment cannot effectively improve oil recovery.

  1. Lipid phosphate phosphohydrolase-1 degrades exogenous glycerolipid and sphingolipid phosphate esters.

    PubMed Central

    Jasinska, R; Zhang, Q X; Pilquil, C; Singh, I; Xu, J; Dewald, J; Dillon, D A; Berthiaume, L G; Carman, G M; Waggoner, D W; Brindley, D N

    1999-01-01

    Lipid phosphate phosphohydrolase (LPP)-1 cDNA was cloned from a rat liver cDNA library. It codes for a 32-kDa protein that shares 87 and 82% amino acid sequence identities with putative products of murine and human LPP-1 cDNAs, respectively. Membrane fractions of rat2 fibroblasts that stably expressed mouse or rat LPP-1 exhibited 3.1-3. 6-fold higher specific activities for phosphatidate dephosphorylation compared with vector controls. Increases in the dephosphorylation of lysophosphatidate, ceramide 1-phosphate, sphingosine 1-phosphate and diacylglycerol pyrophosphate were similar to those for phosphatidate. Rat2 fibroblasts expressing mouse LPP-1 cDNA showed 1.6-2.3-fold increases in the hydrolysis of exogenous lysophosphatidate, phosphatidate and ceramide 1-phosphate compared with vector control cells. Recombinant LPP-1 was located partially in plasma membranes with its C-terminus on the cytosolic surface. Lysophosphatidate dephosphorylation was inhibited by extracellular Ca2+ and this inhibition was diminished by extracellular Mg2+. Changing intracellular Ca2+ concentrations did not alter exogenous lysophosphatidate dephosphorylation significantly. Permeabilized fibroblasts showed relatively little latency for the dephosphorylation of exogenous lysophosphatidate. LPP-1 expression decreased the activation of mitogen-activated protein kinase and DNA synthesis by exogenous lysophosphatidate. The product of LPP-1 cDNA is concluded to act partly to degrade exogenous lysophosphatidate and thereby regulate its effects on cell signalling. PMID:10359651

  2. [Effects of exogenous spermidine on Cucumis sativus L. seedlings photosynthesis under root zone hypoxia stress].

    PubMed

    Wang, Tian; Wang, Suping; Guo, Shirong; Sun, Yanjun

    2006-09-01

    With water culture, this paper studied the effects of exogenous spermidine (Spd) on the net photosynthetic rate (Pn), intercellular CO2 concentrations (Ci), stomatal conductance (Gs), transpiration rate (Tr), apparent quantum yield (phi c), and carboxylation efficiency (CE) of cucumber seedlings tinder hypoxia stress. The results showed that the Pn decreased gradually under hypoxia stress, and reached the minimum 10 days after by 63. 33% of the control. Compared with that of hypoxia-stressed plants, the Pn after 10 days application of exogenous Spd increased 1.25 times. A negative correlation (R2 = 0.4730 - 0.7118) was found between Pn and Ci. Gs and Tr changed in wider ranges, which decreased under hypoxia-stress, but increased under hypoxia-stress plus exogenous Spd application. There was a significant positive correlation between Gs and Tr (R2 = 0.7821 - 0.9458), but these two parameters had no significant correlation with Pn; Hypoxia stress induced a decrease of phi c and CE by 63.01% and 72.33%, respectively, while hypoxia stress plus exogenous Spd application made phi c and CE increase by 23% and 14%, respectively. The photo-inhibition of cucumber seedlings under hypoxia stress was mainly caused by non-stomatal limitation, while exogenous Spd alleviated the hypoxia stress by repairing photosynthesis system.

  3. Exogenous attention and endogenous attention influence initial dominance in binocular rivalry.

    PubMed

    Chong, Sang Chul; Blake, Randolph

    2006-05-01

    We investigated the influence of exogenous and endogenous attention on initial selection in binocular rivalry. Experiment 1 used superimposed +/-45 degrees gratings viewed dioptically for 3s, followed by a brief contrast increment in one of the gratings to direct exogenous attention to that grating. After a brief blank period, dichoptic stimuli were presented for various durations (100-700 ms). Exogenous attention strongly influenced which stimulus was initially dominant in binocular rivalry, replicating an earlier report (Mitchell, Stoner, & Reynolds. (2004). Object-based attention determines dominance in binocular rivalry. Nature, 429, 410-413). In Experiment 2, endogenous attention was manipulated by having participants track one of two oblique gratings both of which independently and continuously changed their orientations and spatial frequencies during a 5s period. The initially dominant grating was most often the one whose orientation matched the grating correctly tracked using endogenous attention. In Experiment 3, we measured the strength of both exogenous and endogenous attention by varying the contrast of one of two rival gratings when attention was previously directed to that grating. The contrast of the attended grating had to be reduced by an amount in the neighborhood of 0.3 log-units, to counteract attention's boost to initial dominance. Evidently both exogenous and endogenous attention can influence initial dominance of binocular rivalry, effectively boosting the stimulus strength of the attended rival stimulus.

  4. An Exogenous Surfactant-Producing Bacillus subtilis Facilitates Indigenous Microbial Enhanced Oil Recovery

    PubMed Central

    Gao, Peike; Li, Guoqiang; Li, Yanshu; Li, Yan; Tian, Huimei; Wang, Yansen; Zhou, Jiefang; Ma, Ting

    2016-01-01

    This study used an exogenous lipopeptide-producing Bacillus subtilis to strengthen the indigenous microbial enhanced oil recovery (IMEOR) process in a water-flooded reservoir in the laboratory. The microbial processes and driving mechanisms were investigated in terms of the changes in oil properties and the interplay between the exogenous B. subtilis and indigenous microbial populations. The exogenous B. subtilis is a lipopeptide producer, with a short growth cycle and no oil-degrading ability. The B. subtilis facilitates the IMEOR process through improving oil emulsification and accelerating microbial growth with oil as the carbon source. Microbial community studies using quantitative PCR and high-throughput sequencing revealed that the exogenous B. subtilis could live together with reservoir microbial populations, and did not exert an observable inhibitory effect on the indigenous microbial populations during nutrient stimulation. Core-flooding tests showed that the combined exogenous and indigenous microbial flooding increased oil displacement efficiency by 16.71%, compared with 7.59% in the control where only nutrients were added, demonstrating the application potential in enhanced oil recovery in water-flooded reservoirs, in particular, for reservoirs where IMEOR treatment cannot effectively improve oil recovery. PMID:26925051

  5. Lipid phosphate phosphohydrolase-1 degrades exogenous glycerolipid and sphingolipid phosphate esters.

    PubMed

    Jasinska, R; Zhang, Q X; Pilquil, C; Singh, I; Xu, J; Dewald, J; Dillon, D A; Berthiaume, L G; Carman, G M; Waggoner, D W; Brindley, D N

    1999-06-15

    Lipid phosphate phosphohydrolase (LPP)-1 cDNA was cloned from a rat liver cDNA library. It codes for a 32-kDa protein that shares 87 and 82% amino acid sequence identities with putative products of murine and human LPP-1 cDNAs, respectively. Membrane fractions of rat2 fibroblasts that stably expressed mouse or rat LPP-1 exhibited 3.1-3. 6-fold higher specific activities for phosphatidate dephosphorylation compared with vector controls. Increases in the dephosphorylation of lysophosphatidate, ceramide 1-phosphate, sphingosine 1-phosphate and diacylglycerol pyrophosphate were similar to those for phosphatidate. Rat2 fibroblasts expressing mouse LPP-1 cDNA showed 1.6-2.3-fold increases in the hydrolysis of exogenous lysophosphatidate, phosphatidate and ceramide 1-phosphate compared with vector control cells. Recombinant LPP-1 was located partially in plasma membranes with its C-terminus on the cytosolic surface. Lysophosphatidate dephosphorylation was inhibited by extracellular Ca2+ and this inhibition was diminished by extracellular Mg2+. Changing intracellular Ca2+ concentrations did not alter exogenous lysophosphatidate dephosphorylation significantly. Permeabilized fibroblasts showed relatively little latency for the dephosphorylation of exogenous lysophosphatidate. LPP-1 expression decreased the activation of mitogen-activated protein kinase and DNA synthesis by exogenous lysophosphatidate. The product of LPP-1 cDNA is concluded to act partly to degrade exogenous lysophosphatidate and thereby regulate its effects on cell signalling.

  6. [Effects of exogenous dimethylarsinic acid on Brassica campestris growth and soil arsenic bioavailability].

    PubMed

    Bai, Ling-Yu; Zeng, Xi-Bai; Hu, Liu-Jie; Li, Lian-Fang; He, Qiu-Hong

    2011-02-01

    A pot experiment was conducted to study the effects of exogenous dimethylarsinic acid (DMA) on the growth of Brassica campestris and the bioavailability of soil arsenic (As). With the increasing concentration of applied DMA, the emergence rate and biomass of B. campestris increased at low concentration DMA, but decreased at high concentration DMA. When the DMA concentration reached 90 mg x kg(-1), the emergence rate and biomass of B. campestris in the second cropping decreased by 9.5% and 57.0%, respectively, compared with those in the control, indicating that exogenous DMA had longer-term effects on the growth of B. campestris. The soil available As and the As uptake by B. campestris all increased with increasing concentration of exogenous DMA, and there existed significant correlations among them. After applied into soil, the exogenous DMA demethylated, with As(V) as the main product and lesser amount of As (III), and the concentrations of soil As(V) and As(III) increased with increasing application rate of exogenous DMA.

  7. "Delayed death" phenomenon: a synergistic action of cyclophosphamide and exogenous DNA.

    PubMed

    Dolgova, Evgenia V; Proskurina, Anastasia S; Nikolin, Valeriy P; Popova, Nelly A; Alyamkina, Ekaterina A; Orishchenko, Konstantin E; Rogachev, Vladimir A; Efremov, Yaroslav R; Dubatolova, Tatiana D; Prokopenko, Anastasia V; Chernykh, Elena R; Ostanin, Alexandr A; Taranov, Oleg S; Omigov, Vladimir V; Zagrebelniy, Stanislav N; Bogachev, Sergey S; Shurdov, Mikhail A

    2012-03-10

    Morbidity and mortality in mice were observed upon administration of exogenous DNA following their pre-treatment with a cytostatic agent cyclophosphamide. Upon intraperitoneal injections, the fragments of exogenous DNA reached bone marrow cells. These cells were also found to internalize up to 1800 kb of exogenous DNA ex vivo. The 18-24 h time frame represents a final stage in the repair of DNA double-strand breaks, so when exogenous DNA was administered within this critical period of time, pathological changes were observed in many target organs. Namely, bone marrow cells underwent a sustained increase in apoptosis. Copy number of B1 and B2 DNA repeats in bone marrow cells remained unchanged, whereas in the control group of animals their levels were significantly decreased. Finally, the bone marrow cells of moribund animals completely lacked lymphoid progenitors, yet the CD34+ hematopoietic stem cell counts were normal. Histopathology analysis suggested that mice died due to accidental involution of lymphoid organs combined with a systemic inflammatory process induced by massive administration of exogenous DNA and depletion of lymphoid lineage. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. On the relative contributions of multisensory integration and crossmodal exogenous spatial attention to multisensory response enhancement.

    PubMed

    Van der Stoep, N; Spence, C; Nijboer, T C W; Van der Stigchel, S

    2015-11-01

    Two processes that can give rise to multisensory response enhancement (MRE) are multisensory integration (MSI) and crossmodal exogenous spatial attention. It is, however, currently unclear what the relative contribution of each of these is to MRE. We investigated this issue using two tasks that are generally assumed to measure MSI (a redundant target effect task) and crossmodal exogenous spatial attention (a spatial cueing task). One block of trials consisted of unimodal auditory and visual targets designed to provide a unimodal baseline. In two other blocks of trials, the participants were presented with spatially and temporally aligned and misaligned audiovisual (AV) targets (0, 50, 100, and 200ms SOA). In the integration block, the participants were instructed to respond to the onset of the first target stimulus that they detected (A or V). The instruction for the cueing block was to respond only to the onset of the visual targets. The targets could appear at one of three locations: left, center, and right. The participants were instructed to respond only to lateral targets. The results indicated that MRE was caused by MSI at 0ms SOA. At 50ms SOA, both crossmodal exogenous spatial attention and MSI contributed to the observed MRE, whereas the MRE observed at the 100 and 200ms SOAs was attributable to crossmodal exogenous spatial attention, alerting, and temporal preparation. These results therefore suggest that there may be a temporal window in which both MSI and exogenous crossmodal spatial attention can contribute to multisensory response enhancement.

  9. Halophilic adaptation of enzymes.

    PubMed

    Madern, D; Ebel, C; Zaccai, G

    2000-04-01

    It is now clear that the understanding of halophilic adaptation at a molecular level requires a strategy of complementary experiments, combining molecular biology, biochemistry, and cellular approaches with physical chemistry and thermodynamics. In this review, after a discussion of the definition and composition of halophilic enzymes, the effects of salt on their activity, solubility, and stability are reviewed. We then describe how thermodynamic observations, such as parameters pertaining to solvent-protein interactions or enzyme-unfolding kinetics, depend strongly on solvent composition and reveal the important role played by water and ion binding to halophilic proteins. The three high-resolution crystal structures now available for halophilic proteins are analyzed in terms of haloadaptation, and finally cellular response to salt stress is discussed briefly.

  10. Changes in digestive enzyme activities during larval development of leopard grouper (Mycteroperca rosacea).

    PubMed

    Martínez-Lagos, R; Tovar-Ramírez, D; Gracia-López, V; Lazo, J P

    2014-06-01

    The leopard grouper is an endemic species of the Mexican Pacific with an important commercial fishery and good aquaculture potential. In order to assess the digestive capacity of this species during the larval period and aid in the formulation of adequate weaning diets, this study aimed to characterize the ontogeny of digestive enzymes during development of the digestive system. Digestive enzymes trypsin, chymotrypsin, acid protease, leucine-alanine peptidase, alkaline phosphatase, aminopeptidase N, lipase, amylase and maltase were quantified in larvae fed live prey and weaned onto a formulated microdiet at 31 days after hatching (DAH) and compared with fasting larvae. Enzyme activity for trypsin, lipase and amylase were detected before the opening of the mouth and the onset of exogenous feeding, indicating a precocious development of the digestive system that has been described in many fish species. The intracellular enzyme activity of leucine-alanine peptidase was high during the first days of development, with a tendency to decrease as larvae developed, reaching undetectable levels at the end of the experimental period. In contrast, activities of enzymes located in the intestinal brush border (i.e., aminopeptidase and alkaline phosphatase) were low at the start of exogenous feeding but progressively increased with larval development, indicating the gradual maturation of the digestive system. Based on our results, we conclude that leopard grouper larvae possess a functional digestive system at hatching and before the onset of exogenous feeding. The significant increase in the activity of trypsin, lipase, amylase and acid protease between 30 and 40 DAH suggests that larvae of this species can be successfully weaned onto microdiets during this period.

  11. Enzyme catalysis "reilluminated".

    PubMed

    Gärtner, Wolfgang

    2009-01-01

    In a new light: The NADPH:protochlorophyllide (Pchlide) oxidoreductase (POR; see structure, green Pchlide, yellow NADPH) is a good model to investigate catalytical processes in enzymes, as its light activation allows an immediate start of the catalyzed reaction. By irradiation with weak, short laser pulses it is possible to detect conformation changes during the reaction and thus to uncover the elementary steps of the catalytic process.

  12. Uronic polysaccharide degrading enzymes.

    PubMed

    Garron, Marie-Line; Cygler, Miroslaw

    2014-10-01

    In the past several years progress has been made in the field of structure and function of polysaccharide lyases (PLs). The number of classified polysaccharide lyase families has increased to 23 and more detailed analysis has allowed the identification of more closely related subfamilies, leading to stronger correlation between each subfamily and a unique substrate. The number of as yet unclassified polysaccharide lyases has also increased and we expect that sequencing projects will allow many of these unclassified sequences to emerge as new families. The progress in structural analysis of PLs has led to having at least one representative structure for each of the families and for two unclassified enzymes. The newly determined structures have folds observed previously in other PL families and their catalytic mechanisms follow either metal-assisted or Tyr/His mechanisms characteristic for other PL enzymes. Comparison of PLs with glycoside hydrolases (GHs) shows several folds common to both classes but only for t