PubMed · 4708837
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
E Cheraskin, W M Ringsdorf, D W Michael, B S Hicks. 1973. The exercise profile.. https://doi.org/10.1111/j.1532-5415.1973.tb01672.x
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Ascorbic acid (AsA) is an essential nutritional component and powerful antioxidant in vegetables, and in plants, AsA levels are regulated by light. AsA levels in the leaves of Chinese chive (Allium tuberosum Rottler ex Spr), a popular vegetable, are poorly understood. Thus, this study was performed to assess the influence of light on AsA biosynthesis in chive and select related genes (AtuGGP1 and AtuGME1); in addition, bioinformatic analyses and gene expression level assays were performed. The biological information obtained for AtuGGP1 and AtuGME1 was analysed with several tools, including NCBI, DNAMAN, and MEGA11. After different light treatments were performed, the Chive AsA content and AtuGGP1 and AtuGME1 expression levels were determined. These results suggest that 1) compared with natural light, continuous darkness inhibited AsA synthesis in chives. 2) The amino acid sequences of AtuGGP1 and AtuGME1 are very similar to those of other plants. 3) The trends observed for the expression levels of AtuGGP1 and AtuGME1 were consistent with the AsA content observed in chives. Hence, we speculated that light controls AsA biosynthesis in chives by regulating AtuGGP1 and AtuGME1 expression. This study provided impactful and informative evidence regarding the functions of GGP and GME in chives.
An enzymatic method is described for measuring L-dehydroascorbic acid in perchloric acid extracts of biological samples. The enzyme used in the assay was glutathione dehydrogenase (glutathione:dehydroascorbate oxidoreductase), which was purified from wheat flour using three column chromatography steps. The enzyme catalyzes the reduction of dehydroascorbic acid by glutathione, and the ascorbic acid product is measured spectrophotometrically at 265 nm. The assay is a fast (about 2 min) and simple two-step procedure. First, a mixture of extract and buffer is set to zero absorbance against air in a spectrophotometer. Second, a solution of glutathione dehydrogenase and glutathione is added and the absorbance after 2 min is used in a formula to calculate nmol dehydroascorbic acid/g or ml sample [513.8(Abs-0.013) x factor for dilution of extract]. The formula was derived from a calibration graph using pure L-dehydroascorbic acid standards. Pure L-dehydroascorbic acid was prepared from pure L-ascorbic acid, and the ascorbate oxidase used to catalyze the reaction was removed by ultrafiltration. Commercial L-dehydroascorbic acid (Aldrich) was unsuitable for use as a standard because the purity was only 56-67% in comparison to laboratory-prepared L-dehydroascorbic acid. The sensitivity of the assay was such that when dehydroascorbic acid was added to healthy human blood plasma during extraction with perchloric acid at the level of 7.5 nmol/ml plasma the dehydroascorbic acid could be measured with complete recovery. Low levels of dehydroascorbic acid were detected in fresh fruits and vegetables. When samples were ground for several minutes before extraction with perchloric acid, the dehydroascorbic acid levels increased more than 10-fold. Dehydroascorbic acid increased rapidly during mixing of bread dough containing added L-ascorbic acid.
Millimolar concentrations of ascorbate in the presence of iron can cause neuronal cell death. This study shows that the human neuronal cell line IMR-32 is sensitive to ascorbate and that cytotoxicity can be blocked by the antioxidant enzymes Cu/Zn-superoxide dismutase and catalase. There was a selective loss of neurofilament proteins after exposure to 5 or 10 mM ascorbate, as assessed by immunostaining and by Western blotting. Loss of actin or tubulin was not seen, suggesting that loss of neurofilaments is a sensitive and selective marker for free radical damage in these cells.