Fatal Candida albicans infections in the mucosal system can occur in association with immune-compromised diseases and dysbacteriosis. Currently, amphotericin B (AmB) is considered to be the most effective antibiotic in the treatment of C. albicans infections, but its clinical application is limited by side effects and poor bioavailability. In order to use AmB in the local treatment of oral C. albicans infections, AmB/MPEG-PCL-g-PEI (monomethoxy poly(ethylene glycol)-poly(epsilon-caprolactone)-graft-polyethylenimine, MPP) micelles were prepared. A series of characterizations were performed. The micelles allowed a sustained in vitro release in both normal oral conditions (pH 6.8) and C. albicans infection conditions (pH 5.8). Then, buccal tablets containing freeze-dried powder of AmB/MPP micelles were produced by direct compression process and evaluated as regards to weight variation, hardness, and friability. In vitro drug release of the buccal tablets was measured in both the United States Pharmacopeia dissolution apparatus and the dissolution rate test apparatus, which was previously designed for simulating in vivo conditions of the oral cavity. The buccal tablets could sustainably release within 8 h and meet the antifungal requirements. Regarding safety assessment of AmB/MPP micelles, in vivo histopathological data showed no irritation toward buccal mucosa of the rats in both optical microscopy and ultrastructure observation of the tissues. MTT experiment proved that AmB/MPP micelles reduced the cytotoxicity of AmB. The micelles delivered through the gastrointestinal route were also found to be non-systemic toxicity by liquid chromatography-mass spectrometry analysis. Furthermore, the antifungal action of AmB/MPP micelles was evaluated. Although AmB/MPP had no obvious improvement as compared to AmB alone in the antifungal effect on planktonic C. albicans , the micelles significantly enhanced the antifungal activity against the biofilm state of C. albicans . Thus, it was concluded that AmB/MPP micelles represent a promising novel drug delivery system for the local treatment of oral C. albicans infections.
Plant WRKY transcription factors act as either positive or negative regulators of plant basal disease resistance. To comprehensively characterise the complicated functional network, we isolated OsWRKY77 from rice seedlings treated with salicylic acid. OsWRKY77 is a typical WRKY transcription factor, based on in its protein structure analysis, nuclear localisation of the fused OsWRKY77-GFP protein and gel electrophoretic mobility shift assay binding, which demonstrated that OsWRKY77 was able to bind a W-box. Transgenic Arabidopsis lines overexpressing OsWRKY77 repressed growth of Pseudomonas syringae pv. tomato DC3000 (PstDC300), and the reduced susceptibility was associated with enhanced expression of defence-related PR1, PR2 and PR5 genes. These results show that OsWRKY77 is a positive regulator of PR gene expression and basal resistance to the bacterial pathogen PstDC3000.
Brown leaf spots were observed on tea [Camellia sinensis (L.) Kuntze] in Sinan County (27.74 °N, 108.35 °E) and Kaiyang County (27.96 °N, 107.34 °E), Guizhou Province, China, from 2018 to 2020. For the leaf spots with the typical symptoms, the disease incidence was estimated to range between 56% and 61%, respectively. The disease severity was estimated to range from 39 to 43 across 12 tea plantations, respectively. The disease initially occurred at the margins of leaf tips, and the lesions expanded gradually, being dark brown and irregularly shaped and became necrotic. To identify the causal organism, two leaves from each of 15 tea twigs, one or two per plantation, were detached from 8- or 10-year-old tea plants on each of 12 plantations. Samples taken from the lesion margins were sterilized with 75% ethanol followed by 0.5% NaOCl, placed on potato dextrose agar (PDA), and then incubated at 25oC in darkness for 5 days (Wang et al. 2020). For each sample, hyphal tips from the margin of a growing colony were successively transferred to fresh PDA, and pure cultures were obtained. Three representative strains were grown on PDA, malt extract agar (MEA), and oatmeal agar (OA) plates. The colonies had smooth margins and abundant mycelia on all three media, with the colony colors being from gray to light purple on PDA, white on MEA, and purplish-red on OA at 5 days post-inoculation. At 20 days post-inoculation on MEA, stromata began to gradually form, which were droplet-like, 100 to 2,000 μm in diameter, and semi-immersed on the medium’s surface. Black sporodochia were produced on the surfaces of stromata. Conidiophores were aggregated in sporodochia, densely compacted, and dark brown. Conidia were globose or pyriform, dark, multicellular, and measured 22.95 ± 3.59 × 19.82 ± 3.13 μm (n = 50) in diameter. The morphological characteristics of the mycelia and reproductive structures of the strains were identical to those of Epicoccum nigrum. The internal transcribed spacer (ITS) region of rDNA, and the partial 28S large subunit rDNA (LSU), RNA polymerase II second largest subunit (RPB2), and beta-tubulin (TUB) genes of these strains were amplified using the primers V9G/ITS4 (De Hoog and Gerrits van den Ende 1998; White et al. 1990), LR0R/LR5 (Rehner and Samuels 1994), RPB2-5F2/fRPB2-7cR (Sung et al. 2007), and TUB2Fd/TUB4Rd (Woudenberg et al. 2009), respectively, and deposited in GenBank (accession no. MW646378, MW291537, MW602293, and MW602295 for ITS, LSU, RBP2, and TUB, respectively). A maximum parsimony phylogenetic analysis indicated that the representative strains clustered with E. nigrum CBS 173.73 (Chen et al. 2017). Pathogenicity tests were performed on 5-year-old potted tea and on 10-year-old C. sinensis cv. Fuding-dabaicha in the field. Mycelial plugs (6-mm diam.) and a conidial suspension (106 conidial/mL) were applied on punctured leaves using a sterile needle and non-punctured leaves. Inoculation with only a PDA plug or sterile water served as controls. Brown spots appeared on the wounded sites of tea leaves at 2 days post-inoculation. No symptoms were observed on the non-wounded leaves or wounded leaves inoculated with PDA plugs lacking mycelia. The re-isolated pathogen from diseased plants was identical to the purified strain ACCC39731 used for inoculation, with re-isolation frequency being 85.0%. To our knowledge, this is the first report of E. nigrum causing leaf spot on tea plants in China, and our findings will be useful for its management and further research.
Diseases caused by southern rice black-streaked dwarf virus (SRBSDV) and rice ragged stunt virus (RRSV) considerably decrease grain yield. Therefore, determining rice cultivars with high resistance to SRBSDV and RRSV is necessary. In this study, rice cultivars with high resistance to SRBSDV and RRSV were evaluated through field trials in Shidian and Mangshi county, Yunnan province, China. SYBR Green I-based quantitative real-time polymerase chain reaction (qRT-PCR) analysis was used to quantitatively detect virus gene expression levels in different rice varieties. The following parameters were applied to evaluate rice resistance: acre yield (A.Y.), incidence of infected plants (I.I.P.), virus load (V.L.), disease index (D.I.), and insect quantity (I.Q.) per 100 clusters. Zhongzheyou1 (Z1) and Liangyou2186 (L2186) were considered the most suitable varieties with integrated higher A.Y., lower I.I.P., V.L., D.I. and I.Q. features. In order to investigate the mechanism of rice resistance, comparative label-free shotgun liquid chromatography tandem-mass spectrometry (LC-MS/MS) proteomic approaches were applied to comprehensively describe the proteomics of rice varieties’ SRBSDV tolerance. Systemic acquired resistance (SAR)-related proteins in Z1 and L2186 may result in the superior resistance of these varieties compared with Fengyouxiangzhan (FYXZ).
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