To exploit a new source from medical plants for finding bioactive products, endophytic fungi DBR-5 identified as Nigrospora sp., was isolated from the root tubers of the traditional Chinese medicinal plant Stephania kwangsiensis Lo. The antifungal activities of the extract from its fermentation liquids were determined. The ethyl acetate extract of DBR-5 exhibited high and broad antifungal activities against plant pathogenic fungi, and showed high toxicity to Exserohilum turcicum, Bipolaris maydis, Ceratocystis paradoxa, Alternaria oleracea and Cochliobolus miyabeanus with EC 50 values respectively at 0.01 mg/mL, 0.02 mg/mL, 0.03 mg/mL, 0.03 mg/mL and 0.04 mg/mL. By a bioassay guided fractionation, three antifungal secondary metabolites were isolated from liquid culture of DBR-5, and identified as griseofulvin, deoxybostrycin and austrocortirubin on the basis of spectroscopic analysis. In vitro antifungal assay showed that griseofulvin displayed significant inhibition against the hypha growth of tested plant pathogenic fungi with EC 50 values ranging from 0.0013 mg/mL to 0.0202 mg/mL, and showed the highest toxicity to E. turcicum and C. paradoxa with EC 50 values both at 0.0013 mg/mL. Compared with the broad spectrum fungicide carbendazim, except that the toxicity of griseofulvin to Diaporthe citri and Pestalotiopsis theae was lower, the toxicity to the other eight pathogenic fungi was much higher. The inhibitory rates of griseofulvin against spore germination of A. olerace, C. paradoxa and P. theae were 100%, 100% and 94.39% respectively, at a concentration of 0.01 mg/mL. The other two compounds deoxybostrycin and austrocortirubin exhibited only weak antifungal activities. The results indicate the potential of Nigrospora sp. DBR-5 as a source of griseofulvin and also support that griseofulvin is a natural compound with high potential bioactivity against plant pathogenic fungi.
allergic asthma is one of the most common allergic diseases; however, the mechanisms underlying its development have yet to be fully elucidated. although allergic diseases are inheritable, genetic variance alone cannot explain the notable increase in the prevalence of allergic diseases over a short period of time in recent decades. recently, research focus has been shifting to epigenetic factors, such as non-coding rnas. circular rnas (circrnas) are involved in the pathogenesis of various diseases. The aim of the present study was to further elucidate the etiology of allergic asthma by analyzing aberrantly expressed circrnas in a murine asthma model. a mouse model of house dust mite allergen-induced asthma was established, and the qualified libraries were sequenced using next-generation sequencing. The expression levels of circrnas were validated by reverse transcription-quantitative Pcr (rT-qPcr) analysis. Gene ontology (Go) and Kyoto encyclopedia of Genes and Genomes (KeGG) pathway analyses were performed for biological pathway classification and enrichment analysis of the aberrantly expressed circrnas. in addition, the interaction network of the differentially expressed circrnas and micrornas (mirnas) was constructed using cytoscape. By next-generation sequencing, a total of 150 circrnas were revealed to be upregulated and 130 were downregulated in the murine asthma model group compared with in the control group. Go and KeGG analyses demonstrated that the differentially expressed circrnas were mainly involved in processes such as 'autoimmune disease', 'cell adhesion molecules (caMs)' and 'endocytosis', among others. The expression levels of six circrnas, namely three upregulated (circ_0000909, circ_0000629 and circ_0000455) and three downregulated (circ_0001454, circ_0000723 and circ_0001389) circrnas, were validated by rT-qPcr. in conclusion, the analyses suggested that circrnas performed critical functions via endocytosis (such as macrophage endocytosis), cell adhesion molecules and lipid metabolism in allergic asthma. The interaction network revealed that certain mirnas that may serve a role in asthma could be regulated by the differentially expressed circrnas.
Cerbera manghas is a mangrove plant which possesses comprehensive biological activities. A great deal of research has been undertaken on the chemical constituents and medical functions of C. manghas; insecticidal and antifungal activities have also been reported, but the acaricidal activity has not been studied. In our study, the acaricidal activity and active substances of C. manghas were investigated using a spray method, which showed that the methanol extracts of the fruit, twigs and leaves exhibited contact activity against female adults of Panonychus citri, with LC50 values at 24 h of 3.39 g L−1, 4.09 g L−1 and 4.11 g L−1, respectively. An acaricidal compound was isolated from C. manghas by an activity-guided isolation method, and identified as (-)-17β-neriifolin, which is a cardiac glycoside. (-)-17β-Neriifolin revealed high contact activity against female adults, nymphae, larvae and eggs of P. citri, with LC50 values at 24 h of 0.28 g L−1, 0.29 g L−1, 0.28 g L−1 and 1.45 g L−1, respectively.
Exceptional points and skin effect, as the two distinct hallmark features unique to the non-Hermitian physics, have each attracted enormous interests. Recent theoretical works reveal that the topologically nontrivial exceptional points can guarantee the non-Hermitian skin effect, which is geometry-dependent, relating these two unique phenomena. However, such novel relation remains to be confirmed by experiments. Here, we realize a non-Hermitian phononic crystal with exceptional points, which exhibits the geometry-dependent skin effect. The exceptional points connected by the bulk Fermi arcs, and the skin effects with the geometry dependence, are evidenced in simulations and experiments. Our work, building an experimental bridge between the exceptional points and skin effect and uncovering the unconventional geometry-dependent skin effect, expands a horizon in non-Hermitian physics.
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