Cerebroside C Increases Tolerance to Chilling Injury and Alters Lipid Composition in Wheat Roots

<div><p>Chilling tolerance was increased in seed germination and root growth of wheat seedlings grown in media containing 20 µg/mL cerebroside C (CC), isolated from the endophytic <i>Phyllosticta</i> sp. TG78. Seeds treated with 20 µg/mL CC at 4°C expressed the higher germination rate (77.78%), potential (23.46%), index (3.44) and the shorter germination time (6.19 d); root growth was also significantly improved by 13.76% in length, 13.44% in fresh weight and 6.88% in dry mass compared to controls. During the cultivation process at 4°C for three days and the followed 24 h at 25°C, lipid peroxidation, expressed by malondialdehyde (MDA) content and relative membrane permeability (RMP) was significantly reduced in CC-treated roots; activities of lipoxygenase (LOX), phospholipid C (PLC) and phospholipid D (PLD) were inhibited by 13.62–62.26%, 13.54–63.93% and 13.90–61.17%, respectively; unsaturation degree of fatty acids was enhanced through detecting the contents of CC-induced linoleic acid, linolenic acid, palmitic acid and stearic acid using GC-MS; capacities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) were individually increased by 7.69–46.06%, 3.37–37.96%, and −7.00–178.07%. These results suggest that increased chilling tolerance may be due, in part, to the reduction of lipid peroxidation and alternation of lipid composition of roots in the presence of CC.</p></div

Effects of cerebroside C at 20 µg/mL on seedlings growth of wheat.

<p>In each column, the different letter indicates significant (p≤0.05) difference as evaluated by Duncan's Multiple Range Test (DMRT). <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0073380#s3" target="_blank">Results</a> are expressed as the mean (±) standard deviation (SD) of three replicates (n = 3, 10 seedlings in each replicate).</p

Effects of cerebroside C (CC) at 4°C on seed germination of wheat.

<p>0 = 0.5% DMSO distilled water. In each column, the different letter indicates significant (p≤0.05) difference as evaluated by Duncan's Multiple Range Test (DMRT). <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0073380#s3" target="_blank">Results</a> are expressed as the mean (±) standard deviation (SD) of three replicates (n = 3, 10 seedlings in each replicate).</p

Effects of cerebroside C on contents of C16:0, C18:2, C18:0, C18:3.

<p>This was observed in roots of wheat seedlings during 4°C stress at 0, 6, 12, 24, 48, 72 h and recovering 25°C for 24 h (total 96 h). The results were expressed as the mean of three replicates (n = 3, 0.3 g fresh roots from 5–10 seedlings in each replicate). <b>a</b>. Palmitic acid (C16:0), <b>b</b>. linoleic acid C18:2 (2), <b>c</b>. stearic acid C18:0 (3) and <b>d</b>. linolenic acid C18:3 in roots of wheat seedlings was identified by MS and valued through the external standard curve method. CC+4°C, treated with 20 µg/mL CC under cold stress; CK+4°C, treated with 0.5% DMSO under cold stress; CK+25°C treated with 0.5% DMSO in growth chamber at 25°C.</p

Impact of cerebroside C on MDA and RMP.

<p>This was observed in roots of wheat seedlings during 4°C stress at 0, 6, 12, 24, 48, 72 h and recovering 25°C for 24 h (total 96 h). The results were expressed as the mean of three replicates (n = 3, 0.1 g fresh roots from 5–10 seedlings in each replicate). <b>a</b>. MDA, malondialdehyde content in 0.1 g roots of wheat seedlings was demonstrated by assay kit purchased from Nanjing Jiancheng Bioengineering Institute (Nanjing, China); <b>b</b>. RMP, relative membrane permeability was estimated using biochemical assays. CC+4°C, treated with 20 µg/mL CC under cold stress; CK+4°C, treated with 0.5% DMSO under cold stress; CK+25°C, treated with 0.5% DMSO in growth chamber at 25°C.</p

Antioxidant enzyme activities.

<p>This was observed in roots of wheat seedlings during 4°C stress at 0, 6, 12, 24, 48, 72 h and recovering 25°C for 24 h (total 96 h). <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0073380#s3" target="_blank">Results</a> were expressed as the mean of three replicates (n = 3, 0.1 g fresh roots from 5–10 seedlings in each replicate). Activities of <b>a</b>. superoxide dismutase (SOD), <b>b</b>. catalase (CAT), <b>c</b>. glutathione peroxidase (GSH-Px) and <b>d</b>. peroxidase (POD) in roots of wheat seedlings were examined using assay kits purchased from Nanjing Jiancheng Bioengineering Institute (Nanjing, China). CC+4°C, treated with 20 µg/mL CC under cold stress; CK+4°C, treated with 0.5% DMSO under cold stress; CK+25°C treated with 0.5% DMSO in growth chamber at 25°C.</p

Facile Synthesis of Disubstituted Isoxazoles from Homopropargylic Alcohol via CN Bond Formation

A novel iron-catalyzed aerobic oxidative reaction to synthesize disubstituted isoxazoles from homopropargylic alcohol, <i>t</i>-BuONO, and H₂O is developed. The method provides mild conditions to afford a variety of useful substituted heterocycles in an efficient and regioselective manner. The mechanism has been studied and proposed, which indicates that the transformation can be realized through construction of a CN bond and CO bond, C–H oxidation, and then cyclization. Moreover, this method can be enlarged to gram scale