The product has been successfully added to your shopping list.

Ascorbic Acid Assay Kit (L-Ascorbate)

Product code: K-ASCO
€127.00

40 assays (manual) / 400 assays (microplate) / 400 assays (auto-analyser)

Prices exclude VAT

Available for shipping

Content: 40 assays (manual) / 400 assays (microplate) / 400 assays (auto-analyser)
Shipping Temperature: Ambient
Storage Temperature: Short term stability: 2-8oC,
Long term stability: See individual component labels
Stability: > 2 years under recommended storage conditions
Analyte: Ascorbic Acid
Assay Format: Spectrophotometer, Microplate, Auto-analyser
Detection Method: Absorbance
Wavelength (nm): 578
Signal Response: Increase
Linear Range: 0.5 to 30 µg of L-ascorbic acid per assay
Limit of Detection: 0.175 mg/L
Reaction Time (min): ~ 8 min
Application examples: Wine, beer, fruit juices, soft drinks, jam, milk, dairy products (e.g. cheese), dietetic foods, baby foods, processed meat, baking additives, fruit and vegetables (e.g. tomato and potato), pharmaceuticals, feed and other materials (e.g. biological cultures, samples, etc.).
Method recognition: Methods based on this principle have been accepted by MEBAK

The Ascorbic Acid (L-Ascorbate) assay kit is for the specific measurement and analysis of L-ascorbic acid in beverages, meat, flour, dairy and vegetable products.

Note for Content: The number of manual tests per kit can be doubled if all volumes are halved.  This can be readily accommodated using the MegaQuantTM  Wave Spectrophotometer (D-MQWAVE).

See our full list of our organic acid assay kits.

Advantages
  • Very competitive price (cost per test) 
  • All reagents stable for > 6 months after preparation 
  • Mega-Calc™ software tool is available from our website for hassle-free raw data processing 
  • Standard included 
  • Suitable for manual, microplate and auto-analyser formats
Publications
Megazyme publication

Megazyme “advanced” wine test kits general characteristics and validation.

Charnock, S. J., McCleary, B. V., Daverede, C. & Gallant, P. (2006). Reveue des Oenologues, 120, 1-5.

Many of the enzymatic test kits are official methods of prestigious organisations such as the Association of Official Analytical Chemicals (AOAC) and the American Association of Cereal Chemists (AACC) in response to the interest from oenologists. Megazyme decided to use its long history of enzymatic bio-analysis to make a significant contribution to the wine industry, by the development of a range of advanced enzymatic test kits. This task has now been successfully completed through the strategic and comprehensive process of identifying limitations of existing enzymatic bio-analysis test kits where they occurred, and then using advanced techniques, such as molecular biology (photo 1), to rapidly overcome them. Novel test kits have also been developed for analytes of emerging interest to the oenologist, such as yeast available nitrogen (YAN; see pages 2-3 of issue 117 article), or where previously enzymes were simply either not available, or were too expensive to employ, such as for D-mannitol analysis.

Hide Abstract
Megazyme publication

Grape and wine analysis: Oenologists to exploit advanced test kits.

Charnock, S. C. & McCleary, B. V. (2005). Revue des Enology, 117, 1-5.

It is without doubt that testing plays a pivotal role throughout the whole of the vinification process. To produce the best possible quality wine and to minimise process problems such as “stuck” fermentation or troublesome infections, it is now recognised that if possible testing should begin prior to harvesting of the grapes and continue through to bottling. Traditional methods of wine analysis are often expensive, time consuming, require either elaborate equipment or specialist expertise and frequently lack accuracy. However, enzymatic bio-analysis enables the accurate measurement of the vast majority of analytes of interest to the wine maker, using just one piece of apparatus, the spectrophotometer (see previous issue No. 116 for a detailed technical review). Grape juice and wine are amenable to enzymatic testing as being liquids they are homogenous, easy to manipulate, and can generally be analysed without any sample preparation.

Hide Abstract
Publication
Sous‐Vide technique as an alternative to traditional cooking methods in the context of antioxidant properties of brassica vegetables.

Florkiewicz, A., Socha, R., Filipiak‐Florkiewicz, A. & Topolska, K. (2018). Journal of the Science of Food and Agriculture, In Press.

BACKGROUND: Vegetables are important components of the human diet. The processing method is crucial for nutritional quality of ready to eat product. The purpose of this study was to assess whether Sous‐vide method could be an alternative for traditional cooking of Brassica vegetables. RESULTS: Sous‐vide method appeared to be the most advantageous technique in relation to vitamin C preservation, both directly after processing and during storage of processed vegetables. Among studied phytochemicals, p‐coumaric and gallic acids were the most stable in vegetables cooked by this method. CONCLUSION: Sous‐vide method should be considered as an optimal technique of Brassica vegetables thermal treatment.

Hide Abstract
Publication
Before and after potato virus Y necrotic strains (PVYN) inoculation.

Bădărău, L. C., Nina, B., Maria, Ș. & Radu, H. (2017). Journal of Hygienic Engineering and Design, 19, 58-63.

Being a staple food crop, the potato provide basic nutrition to many people and offer several nutritional benefits. Despite valued as carbohydrate source, tubers with higher levels of bioactive compounds (as vitamin C) could have a positive impact on the people health. The goal of this research was to evaluate the behavior of 10 potato varieties with different L ascorbic acid content after inoculation with potato virus Y (necrotic strains). Another goal of this study was to elucidate the biochemical basis responsible for different reaction to infection with potato virus Y necrotic strains PVYN among several varieties which differ in their susceptibility or resistance to this pathogen. The potato varieties, including new Romanian and commercial cultivars evaluated for L ascorbic acid content, were the following: Christian, Roclas, Red Lady, Marvis, Castrum, Brasovia, Hermes, Sante, Riviera and Carrera. The vitamin C content was estimated using an enzymatic method (L-ascorbic test kit, Megazyme Ltd., Bioreba). The L ascorbic acid content was analyzed in the flesh only, with variety Hermes showing the highest content (746 mg/kg-1 DW) in tubers after inoculation. Significant differences in vitamin C content were observed across the cultivars before and after virus inoculation. Excepting the cultivars Christian, Riviera and Sante, which were very resistant and resistant to mechanical inoculation, all the other varieties presented 48.6 - 100% infected plants. After 3 months from harvesting, the frequency of tubers with symptoms was between 8.2 - 34.7% for varieties Roclas, Marvis, Castrum, Brasovia and for Red Lady, Carrera, Hermes varieties this percentage was higher (69.2-98.2%). This study provides information on level of important micronutrients as L ascorbic acid in a range of several health and PVYN infected potato cultivars.

Hide Abstract
Publication
Evaluation of vitamin C content in samples from ten potato cultivars inoculated with potato virus Y (Necrotic strains).

Badarau, C. L., Tican, A., stefan, M. & Chiru, N. (2017). Scientific Papers-Series A-Agronomy, 60, 197-202.

Providing basic nutrition to many people, being a staple food, potato tubers with higher levels of bioactive compounds (as vitamin C) could have a positive impact on the people health. This study aimed to evaluate the behaviour of 10 potato varieties with different L ascorbic acid content after inoculation with potato virus Y necrotic strains (PVYN). Another goal of this research work was to elucidate the biochemical basis responsible for different reaction to infection with potato virus Y among several varieties which differ in their susceptibility or resistance to this pathogen. The potato cultivars evaluated were: Christian, Roclas, Red Lady, Marvis, Castrum, Brasovia, Hermes, Sante, Riviera and Carrera. The vitamin C content was estimated in the flesh matter only, using an enzymatic method. Significant differences in total ascorbic acid content were observed across the varieties before and after virus inoculation, the variety Hermes showing the highest content (746 mg.kg-1 DW) in tubers after inoculation. Excepting the cultivars Christian, Riviera and Sante, which were very resistant and resistant to mechanical inoculation, all the other samples tested presented 48.6 - 100% infected plants.

Hide Abstract
Publication
Dual release of a hydrophilic and a hydrophobic osteogenic factor from a single liposome.

Monteiro, N., Martins, A., Pires, R. A., Faria, S., Fonseca, N. A., Moreira, J. N., Reis, R. L. & Neves, N. M. (2016). RSC Advances, 6(115), 114599-114612.

Delivery systems may be designed to protect and control the release kinetics of growth/differentiation factors in a spatiotemporal manner. Liposomes are examples of biological-based bioactive agent delivery systems. In this work, ascorbic acid (AscA) was encapsulated in the inner compartment of the liposome and dexamethasone (Dex) was encapsulated within the lipid bilayer in order to develop a dual release system of these bioactive agents involved in the osteogenic differentiation of mesenchymal stem cells (MSCs). The particle size (~150 nm) of the prepared liposomes showed a monodisperse distribution. The bioactive agent release study showed that Dex was released more rapidly from the liposomes than AscA. The Dex release profile showed an initial burst release within 12 h; afterwards, a slower and sustained release was observed until 21 days. The release of AscA from the liposomes was not detected until 6 h; afterwards, a linear release was observed from 24 h until 21 days. The effect of Dex-AscA-loaded liposomes on the viability, proliferation and osteogenic differentiation of human bone marrow-derived MSCs (hBMSCs) were assessed. The cell culture results showed that the Dex-AscA-loaded liposomes (in a single dose or in repeated doses) do not have any cytotoxic effect. Dex-AscA-loaded liposomes given once did not promote induction of hBMSCs differentiation into the osteogenic lineage. However, Dex-AscA-loaded liposomes given repeatedly promoted the hBMSCs differentiation into the osteogenic lineage, both in basal medium and complete osteogenic medium. These results were genotypically demonstrated by the expression of osteoblastic markers. In conclusion, Dex-AscA-loaded liposomes represent a biological nanoparticle strategy with potential safety and efficacy for bone tissue engineering approaches.

Hide Abstract
Publication

The influence of harvest period and fruit ripeness at harvest on minimally processed cactus pears (Opuntia ficus-indica L. Mill.) stored under passive atmosphere.

Allegra, A., Sortino, G., Miciletta, G., Riotto, M., Fasciana, T. & Inglese, P. (2015). Postharvest Biology and Technology, 104, 57-62.

The aim of this study was to investigate the effect of (a) harvest season (summer and late crop), (b) fruit ripening stage at harvest and (c) time of storage, on the quality of minimal processed cactus pear (Opuntia ficus-indica). Fresh cut peeled cactus pears harvested at commercial harvest stage or when ripe on tree in August (summer crop) and October (late crop), were stored for 3, 5, 7 and 12 d at 5°C and 95% RH in polyethylene terephthalate (PET) packages under passive atmosphere conditions. Visual quality and crunchiness score, flesh color, microbiological analysis, total soluble solids (TSS), total acidity (TA), total phenolics, ascorbic acid and β-carotene contents were measured. TSS content in fruit flesh did not change during storage, but late crop fruit harvested fully ripe had the highest content. The CO2 concentration inside the package was higher for summer than late fruit and for fully ripe fruit than commercial harvest stage. Fresh cut summer cactus pears lost their marketability and crunchiness after 3 d, while those from the late crop retained good marketability after 5 or 7 d at 5°C, depending on their ripeness stage at harvest. Fresh cut fruit of the summer crop had twice the ascorbic acid content than late cop fruit until 5 d after storage. Fully ripe fresh cut fruit of the summer crop had the lowest β-carotene content. The mesophilic aerobic microorganisms did not change significantly with treatments, until 12 d after storage, when fully ripe fresh cut fruit had the highest count. Mold content was higher in fully ripe than in fruit harvested at commercial ripeness. Ultimately, late fruit, manually peeled and stored at 5°C under passive atmosphere, retained their original quality longer than fully ripe fruit of the same season or summer fruit harvested at either ripeness stage.

Hide Abstract
Publication

Evaluation of substitutes for rock wool as growing substrate for hydroponic tomato production.

Dannehl, D., Suhl, J., Ulrichs, C. & Schmidt, U. (2015). Journal of Applied Botany and Food Quality, 88(1).

To reduce the rock wool waste, the present study is focused on the evaluation of sheep wool, Sphagnum and hemp slabs, which may be used as replacement for rock wool as growing substrate for hydroponic tomato production. As such, physical and chemical properties of substrates, the plant growth, yield, fruit characteristics, as well as primary and secondary metabolites of tomatoes were considered. The marketable fruit yield of plants grown in Sphagnum slabs (12.8 kg plant-1) was reduced to only a small extent compared to the yield produced by rock wool slabs (13.8 kg plant-1). Sheep wool (12.3 kg plant-1) and hemp (10.4 kg plant-1), however, showed higher deviations. The lowest yield of blossom end rot (BER) fruit was produced by Sphagnum. Compared to this result, the BER-yield was nearly 2-fold higher caused by sheep wool. The soluble solid content in fruit ripened by the hemp material was decreased compared to those caused by the remaining substrates. Furthermore, it was found that the volume of easy available water (EAW) was mainly responsible for changes in plant development. As such, a high correlation was found between EAW and: leaf area (r = 0.851); flowers (r = 0.785); lycopene (r = -0.918); β-carotene (r = -0.997); penolics (r = -0.918); LAA (r = -0.848). The findings suggested that Sphagnum slabs can be used as replacement for rock wool slabs, whereas the usage of slabs consisting of hemp and sheep wool is not suitable as growing substrate for hydroponic tomato production.

Hide Abstract
Publication
Polyphenols, carotenoids, vitamin c content in tropical fruits and vegetables and impact of processing methods.

Ellong, E. N., Billard, C., Adenet, S. & Rochefort, K. (2015). Food and Nutrition Sciences, 6(03), 299.

Thirty-five fruits and seventeen vegetables from Martinique were evaluated for total phenol content (TPC), Vitamin C and carotenoid content. TPC, Vitamin C and carotenoid contents ranged from 11.7 to 978.6 mg/100g, 0.1 to 2853.8 mg/100g and 9.7 to 9269.7 µg/100g respectively. Fruits and vegetables from Martinique have equivalent or higher TPC, Vitamin C and carotenoid contents than fruits and vegetables from temperate climates. Cashew apple had high values for all three parameters (55.8 mg/100g of Vitamin C, 603 mg/100g of TPC and 924 µg/100g of carotenoids). Bassignac mango and mamey apple had the highest carotenoid contents, with 3800.3 and 3199.7 µg/100g respectively. Acerola had the highest Vitamin C and polyphenol contents with 2853.8 µg/100g and 727.4 mg/100g respectively. Pigeon peas had high values for all three parameters (569.2 mg/100g of Vitamin C, 978.6 mg/100g of TPC and 364.3 µg/100g of carotenoids). Pumpkin and watercress had the highest carotenoid content, with 9269.7 and 4339 µg/100g respectively. TPC, Vitamin C and carotenoid content were significantly impacted by processing techniques. TPC, Vitamin C and carotenoid contents decreased by up to 75.78%, 100% and 70.18% respectively, depending on the processing technique used.

Hide Abstract
Publication
Physicochemical, organoleptic and nutritional characteristics of four sweet cassava (Manihot opi) varieties.

Ellong, E. N., Billard, C. & Adenet, S. (2014). African Journal of Biotechnology, 13(50).

There exist a wide variety of tropical tubercles in Martinique French West Indies (F.W.I.). This study was carried out in order to investigate the development of local varieties of sweet cassava ( Manihot opi). The purpose of this research was to enhance knowledge of the nutritional and agricultural characteristics of these tubers. The first step in the research project was to carry out a survey and screening of selected varieties, which was undertaken by the local department of agriculture throughout the region of Martinique. Phenotypic characterization and identification were then established. The four varieties were distinguished from each other by phenotypic, organoleptic, physicochemical and nutritional characteristics. Sweet cassavas in Martinique are richer in nutritional compounds and vitamin C than ordinary potatoes. Their sensory specificity, high nutritional value and suitability for industrial processing have also been highlighted. Variety KM07 seemed to offer the best compromise between size, nutritional profile and sensory characteristics and would therefore be recommended for production.

Hide Abstract
Publication
Nutritional and sensory quality during refrigerated storage of fresh-cut mints (Mentha x piperita and M. spicata).

Curutchet, A., Dellacassa, E., Ringuelet, J. A., Chaves, A. R. & Viña, S. Z. (2014). Food Chemistry, 143, 231-238.

The effect of storage time on quality attributes of refrigerated fresh-cut mints (Mentha × piperita and M. spicata) was studied. Atmosphere composition, respiratory activity, weight loss, surface colour, total chlorophyll, carotenoids, browning potential, total phenols, flavonoids, radical-scavenging activity, ascorbic acid and essential oil yield and composition were analysed. Respiratory activity of peppermint and spearmint samples diminished moderately (42% and 28%, respectively) after 21 days at 0°C. A slight modification of the internal atmosphere was achieved. Surface colour, chlorophyll, carotenoid and antioxidant compounds remained almost constant. The yield of essential oil did not change or it showed an apparent increase after 21 days at 0°C, depending on plant growth stage. The characteristic flavour components of peppermint (menthone and menthol) increased, while the contents of the main constituents of spearmint essential oil showed minor variations after storage. The conditions assayed for packaging and storing fresh-cut mints were adequate to achieve a relatively long shelf life and they retained their antioxidant properties.

Hide Abstract
Publication
Reduction of acrylamide formation by vanadium salt in potato French fries and chips.

Kalita, D. & Jayanty, S. S. (2013). Food Chemistry, 138(1), 644-649.

The effects of vanadyl sulphate on the formation of acrylamide have been studied in fried potato products, such as French fries and chips. Acrylamide formation was inhibited by 30.3%, 53.3% and 89.3% when the sliced potato strips were soaked in 0.001, 0.01 and 0.1 M vanadyl sulphate (VOSO4) solutions, respectively, for 60 min before frying. Moreover, 57.7%, 71.4% and 92.5% inhibition of acrylamide formation was observed when chips were soaked in the respective vanadyl sulphate solution before frying. In a separate model reaction, a solution containing an equimolar concentration of L-asparagine and D-glucose showed a significant inhibition of acrylamide formation when heated at 150°C for 30 min in the presence of vanadyl sulphate (VOSO4). The results indicate that the binding of VO2+ to asparagine and the decrease in the pH of the potato samples resulted in a significant reduction of acrylamide formation in fried potato products.

Hide Abstract
Publication
Role of polyphenols in acrylamide formation in the fried products of potato tubers with colored flesh.

Kalita, D., Holm, D. G. & Jayanty, S. S. (2013). Food Research International, 54(1), 753-759.

The levels of asparagine, reducing sugars and total phenolics in some potato cultivars and advanced selections with distinctive flesh color (white, yellow, red and purple) and their potential in acrylamide formation in French fries and potato chips have been investigated in this study. The range of asparagine and reducing sugars were 1.8–9.0 and 1.35–11.7 mg/g respectively. There was no significant correlation of asparagine and reducing sugars with flesh color of the potato tubers. Tubers with red and purple flesh had higher levels of total phenolics than the white and yellow ones. The amount of acrylamide formed in French fries and chips were ranged from 128.1 to 1651.3 µg/kg and from 2104.3 to 2978.5 µg/kg respectively. The levels of asparagine and reducing sugars were positively correlated with acrylamide formation while total phenolics and chlorogenic acid correlated negatively.

Hide Abstract
Publication
Bioactive compounds from endemic plants of Southwest Portugal: Inhibition of acetylcholinesterase and radical scavenging activities.

Tavares, L., Fortalezas, S., Tyagi, M., Barata, D., Serra, A. T., Martins Duarte, C. M. M., Duarte, R. O., Felicano, R. P., Bronze, M. R., Espírito-Santo, M. D., Ferreira, R. B. & Santos, C. N. (2012). Pharmaceutical Biology, 50(2), 239-246.

Context: Natural products are reported to have substantial neuroprotective activity due to their radical scavenging capacity, and also acetylcholinesterase (AChE) inhibitory capacity, both activities important in neurodegeneration. Objective: The undesirable side effects of compounds in pharmacological use make it important to identify natural neuroprotective molecules. This work assesses the potential of five endemic Portuguese plants as sources of neuroprotective compounds. Materials and methods: Antioxidant capacity for peroxyl radical was determined by Oxygen Radical Absorbance Capacity method and for hydroxyl by Electron Paramagnetic Resonance, as well as AChE inhibitory capacity of the plant hydroethanolic extracts. The molecules responsible for these valuable properties were also tentatively identified by HPLC. Results and discussion: Armeria rouyana and Thymus capitellatus presented some of the highest phenolic contents (76.60 ± 7.19 and 12.82 ± 0.24 mg GAE g-1 dw, respectively) and antioxidant capacities (592 ± 116 and 449 ± 57 μmol TE g-1 dw, respectively). The flavonoids were identified as the phytomolecules related to the antioxidant capacity of these plant extracts; in the case of A. rouyana, L-ascorbic acid also made an important contribution (3.27 ± 0.26 mg g-1 dw). Plant extracts clearly demonstrated effective AChE inhibitory activity (480 ± 98 and 490 ± 46 μg mL-1, respectively), that could be associated to polyphenols. Conclusions: The extracts of A. rouyana and T. capitellatus and their active components, especially polyphenols, demonstrate interesting neuroprotective potential. They, therefore, deserve further study as their phytomolecules are promising sources of either natural neuroprotective products and/or novel lead compounds.

Hide Abstract
Publication
Influence of starter cultures on the antioxidant activity of kombucha beverage.

Malbaša, R. V., Lončar, E. S., Vitas, J. S. & Čanadanović-Brunet, J. M. (2011). Food Chemistry, 127(4), 1727-1731.

This paper investigates the influence of starter cultures, obtained from kombucha isolates, on the antioxidant activity of kombucha beverages. Three starter cultures were used as follows: (1) mixed culture of acetic bacteria and Zygosaccharomyces sp. (SC1); (2) mixed culture of acetic bacteria and Saccharomyces cerevisiae (SC2); as well as (3) native local kombucha. The starter cultures were added to black and green tea sweetened with 7% of sucrose. Fermentation was carried out at 28°C for 10 days. Antioxidant activity to hydroxyl and DPPH radicals was monitored. Kombucha beverage on black tea has shown the highest antioxidant activity to both types of radicals with starter SC1, while the green tea beverage has shown the highest activity with native kombucha. The main reason for the different antioxidant activities, beside tea composition, was ascribed to differing production of both vitamin C and total organic acids in the investigated systems.

Hide Abstract
Publication
Antioxidant capacity of Macaronesian traditional medicinal plants.

Tavares, L., Carrilho, D., Tyagi, M., Barata, D., Serra, A. T., Duarte, C. M. M. , Duarte, R. O., Feliciano, R. P., Bronze, M. R., Chicau, P., Espírito-Santo, M. D., Ferreira, R. B. & Dos Santos, C. N. (2010). Molecules, 15(4), 2576-2592.

The use of many traditional medicinal plants is often hampered by the absence of a proper biochemical characterization, essential to identify the bioactive compounds present. The leaves from five species endemic to the Macaronesian islands with recognized ethnobotanical applications were analysed: Apollonias barbujana (Cav.) Bornm., Ocotea foetens (Ainton) Baill, Prunus azorica (Mouill.) Rivas-Mart., Lousã, Fern. Prieto, E. Días, J. C. Costa & C. Aguiar, Rumex maderensis Lowe and Plantago arborescens Poir. subsp. maderensis (Dcne.) A. Hans. et Kunk. Since oxidative stress is a common feature of most diseases traditionally treated by these plants, it is important to assess their antioxidant capacity and determine the molecules responsible for this capacity. In this study, the antioxidant capacity of these plants against two of the most important reactive species in human body (hydroxyl and peroxyl radicals) was determined. To trace the antioxidant origin total phenol and flavonoid contents as well as the polyphenolic profile and the amount of trace elements were determined. There was a wide variation among the species analysed in what concerns their total leaf phenol and flavonoid contents. From the High Performance Liquid Chromatography (HPLC) electrochemically detected peaks it was possible to attribute to flavonoids the antioxidant capacity detected in A. barbujana, O. foetens, R. maderensis and P. azorica extracts. These potential reactive flavonoids were identified for A. barbujana, R. maderensis and P. azorica. For R. maderensis a high content (7 mg g-1 dry weight) of L-ascorbic acid, an already described antioxidant phytomolecule, was found. A high content in selenomethionine (414.35 μg g-1 dry weight) was obtained for P. ar borescens subsp. maderensis extract. This selenocompound is already described as a hydroxyl radical scavenger is reported in this work as also possessing peroxyl radical scavenging capacity. This work is a good illustration of different phytomolecules (flavonoids, organic acids and selenocompounds), presents in leaves of the five traditional medicinal plants endemic to Macaronesia, all exhibiting antioxidant properties.

Hide Abstract
Publication
A mutation in GDP-mannose pyrophosphorylase causes conditional hypersensitivity to ammonium, resulting in Arabidopsis root growth inhibition, altered ammonium metabolism, and hormone homeostasis.

Barth, C., Gouzd, Z. A., Steele, H. P., & Imperio, R. M. (2010). Journal of Experimental Botany, 61(2), 379-394.

Ascorbic acid (AA) is an antioxidant fulfilling a multitude of cellular functions. Given its pivotal role in maintaining the rate of cell growth and division in the quiescent centre of the root, it was hypothesized that the AA-deficient Arabidopsis thaliana mutants vtc1-1, vtc2-1, vtc3-1, and vtc4-1 have altered root growth. To test this hypothesis, root development was studied in the wild type and vtc mutants grown on Murashige and Skoog medium. It was discovered, however, that only the vtc1-1 mutant has strongly retarded root growth, while the other vtc mutants exhibit a wild-type root phenotype. It is demonstrated that the short-root phenotype in vtc1-1 is independent of AA deficiency and oxidative stress. Instead, vtc1-1 is conditionally hypersensitive to ammonium (NH4+). To provide new insights into the mechanism of NH4+ sensitivity in vtc1-1, root development, NH4+ content, glutamine synthetase (GS) activity, glutamate dehydrogenase activity, and glutamine content were assessed in wild-type and vtc1-1 mutant plants grown in the presence and absence of high NH4+ and the GS inhibitor MSO. Since VTC1 encodes a GDP-mannose pyrophosphorylase, an enzyme generating GDP-mannose for AA biosynthesis and protein N-glycosylation, it was also tested whether protein N-glycosylation is affected in vtc1-1. Furthermore, since root development requires the action of a variety of hormones, it was investigated whether hormone homeostasis is linked to NH4+ sensitivity in vtc1-1. Our data suggest that NH4+ hypersensitivity in vtc1-1 is caused by disturbed N-glycosylation and that it is associated with auxin and ethylene homeostasis and/or nitric oxide signalling.

Hide Abstract
Publication
Effect of 1-MCP on quality and antioxidant capacity of in vitro digests from ‘Sunrise’ apples stored at different temperatures.

Qiu, S., Lu, C., Li, X. & Toivonen, P. (2009). Food Research International, 42(3), 337-342.

The antioxidant capacities of phenolic and non-phenolic fractions for in vitro digestates from ‘Sunrise’ apple were assessed after postharvest application of 1-methylcyclopropene (1-MCP), a ripening inhibitor, and three weeks storage at 5, 13, 15, 18 and 22°C. An in vitro digestion system was used to generate the soluble bioaccessable digestate which was then fractionated into phenolic and non-phenolic fractions. The two fractions were assayed for Folin-Ciocalteu Reaction (FCR) reducing capacity and peroxyl radical scavenging capacity. Quality retention of the fruit was assessed by measuring internal ethylene concentration, firmness and titratable acidity. Treatment with 1-MCP inhibited internal ethylene concentration and better maintained the firmness and titratable acidity of ‘Sunrise’ summer apples as compared with untreated control apples at storage temperatures of 15°C and above. The FCR reducing capacity of the phenolic fraction of the in vitro, simulated gastrointestinal digestates showed similar response as did the quality measures, with significantly higher activity in the 1-MCP treated fruit at higher storage temperatures. However, no consistent differences were found between 1-MCP and control treatments for the FCR reducing capacity of the non-phenolic fraction or for the peroxyl radical scavenging capacity of either fraction. The non-phenolic fractions consistently had higher levels of both types of antioxidant capacities. Treatment and storage of ‘Sunrise’ apples at elevated temperatures (> 13°C) resulted in improved fruit quality and retention of reducing capacity in simulated gastrointestinal digestates.

Hide Abstract
Publication
cMyc increases cell number through uncoupling of cell division from cell size in CHO cells.

Kuystermans, D. & Al-Rubeai, M. (2009). BMC Biotechnology, 9(76).

Background: Over the past decades, the increase in maximal cell numbers for the production of mammalian derived biologics has been in a large part due to the development of optimal feeding strategies. Engineering of the cell line is one of probable approaches for increasing cell numbers in bioreactor. Results: We have demonstrated that the over-expression of the c-myc gene in immortalised CHO cells can increase proliferation rate and maximal cell density in batch culture compared to the control. The changes were attributed to a rapid transition into S-phase from a shortened duration of G1 phase and to the uncoupling of cell size from cell proliferation. To achieve the >70% increase in maximal cell density without additional supply of nutrients the cells underwent an overall reduction of 14% in size as well as a significant decrease in glucose and amino acid consumption rate. Consequently, the total biomass accumulation did not show a significant change from the control. The amount of hSEAP-hFc activity of the over expressing c-myc cell line was found to be within 0.7% of the control.Conclusion: It is shown that the manipulation of cell cycle kinetics and indirectly cell metabolism gives higher cell densities in CHO batch cultures. The unaltered apoptotic rate supported the proposition that the increase in cell number was a result of enhance cell cycle kinetics and cellular metabolism rather than increasing viability. Production of hSEAP-hFc from a constitutive c-myc over-expressing cell line did not increase with the increase in cell number.

Hide Abstract
Publication
A high‐grain protein content locus on barley (Hordeum vulgare) chromosome 6 is associated with increased flag leaf proteolysis and nitrogen remobilization.

Jukanti, A. K. & Fischer, A. M. (2008). Physiologia Plantarum, 132(4), 426-439.

Leaf senescence and nitrogen remobilization from senescing tissues are two important factors determining grain protein content (GPC) in cereals. We compared near-isogenic barley (Hordeum vulgare L.) germplasm varying in the allelic state of a major GPC quantitative trait locus on chromosome 6, delineated by molecular markers HVM74 and ABG458 and explaining approximately 46% of the variability in this trait. High GPC was consistently associated with earlier whole-plant senescence. SDS–PAGE and immunoblot analysis of flag leaf proteins indicated earlier leaf protein [including ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco)] degradation in high-GPC germplasm. This was accompanied by enhanced availability of ammonium and glutamine in developing kernels, suggesting increased phloem retranslocation of nitrogen. Based on previous microarray analysis, we performed a detailed expression study of six leaf genes, tentatively involved in plastidial proteolysis, vacuolar proteolysis, intermediary N metabolism and N transport. All of these were upregulated in high-GPC barley, mostly around 21 to 28 days past anthesis, prior to or around the time demonstrating maximal differences in leaf protein (including Rubisco) levels. Therefore, these genes represent potential targets to manipulate grain protein accumulation. It appears likely that their functional analysis will enhance our understanding of whole-plant N recycling. Additionally, earlier leaf (photosynthetic) protein degradation may lead to reduced N carbon assimilation in high-GPC germplasm, explaining past studies demonstrating a negative correlation between GPC and yield.

Hide Abstract
Safety Information
Symbol : GHS05, GHS08
Signal Word : Danger
Hazard Statements : H318, H341, H412
Precautionary Statements : P201, P202, P273, P280, P305+P351+P338, P308+P313, P310, P405, P501
Safety Data Sheet
Customers also viewed
L-Malic Acid Assay Kit Manual Format K-LMAL LMAL
L-Malic Acid Assay Kit (Manual Format)
€110.00
JIM5 [Anti-Homogalacturonan] Antibody AB-JIM5
JIM5 [Anti-Homogalacturonan] Antibody
€156.00
Raffinose Sucrose D-Glucose Assay Kit K-RAFGL
Raffinose/Sucrose/D-Glucose Assay Kit
€254.00
Maltose Sucrose D-Glucose Assay Kit K-MASUG
Maltose/Sucrose/D-Glucose Assay Kit
€198.00
L-Malic Acid Assay Kit Liquid Ready Reagents K-LMALQR
L-Malic Acid Assay Kit (Liquid Ready)
€146.00
L-Malic Acid Assay Kit Analyser Format K-LMALAF
L-Malic Acid Assay Kit (Analyser Format)
€190.00
beta-Glucan Assay Kit Yeast Mushroom K-YBGL YBGL
β-Glucan Assay Kit (Yeast & Mushroom)
€227.00
D-Fructose D-Glucose Assay Kit Liquid Ready Reagents K-FRGLQR
D-Fructose/D-Glucose Assay Kit (Liquid Ready)
€146.00