Integrated physiological, metabolomic, and proteome analysis of Alpinia officinarum Hance essential oil inhibits the growth of Fusarium oxysporum of Panax notoginseng.

Fusarium oxysporum is the main pathogen of Panax notoginseng root rot, and chemical fungicides remain the primary measures to control the disease. Plant essential oil (EO) is a volatile plant secondary metabolic product that does not produce any residue to replace chemical pesticide. To comprehensively understand the antifungal mechanism of Alpinia officinarum Hance EO, the physiological indicators, proteome and metabolome were analyzed using F. oxysporum spores and hyphae treated with different EO concentrations. The cell membrane was damaged after both low and high concentrations of EO treatment, along with leakage of the cell contents. To resist the destruction of membrane structure, fungi can increase the function of steroid biosynthesis and expression of these catalytic enzymes, including squalene monooxygenase (SQLE), sterol 14alpha-demethylase (CYP51, CYP61A), delta14-sterol reductase (TM7SF2, ERG4), methylsterol monooxygenase (MESO1), and sterol 24-C-methyltransferase (SMT1). Furthermore, the tricarboxylic acid cycle (TCA) was influenced by inhibiting the expression of glutamate synthase (GLT1), 4-aminobutyrate aminotransferase (ABAT), and succinate-semialdehyde dehydrogenase (gabD); increasing malate and gamma-aminobutyric acid (GABA); and decreasing citrate content. The spore germination rate and mycelia growth were decreased because the expression of cohesin complex subunit SA-1/2 (IRR1) and cohesion complex subunit (YCS4, BRN1, YCG1) were inhibited. Particularly, under high EO concentrations, cyclin-dependent kinase (CDC28) and DNA replication licensing factor (MCM) were further inhibited to disrupt the cell cycle and meiosis, thus affecting cell division. The results of this study will enrich the understanding of the antifungal mechanism of EOs and provide an important basis to develop new plant-derived fungicides.

[Mechanism of Photochemical Degradation of MC-LR by Pyrite].

Pyrite was used as catalyst to degrade Microcystin-LR (MC-LR) at pH 6.8 under visible light irradiation (λ>420 nm). X-ray diffraction (XRD) and scanning electron microscope (SEM) characterization showed that pyrite had the layered structure. The ion state of pyrite before and after the reaction was identified using X-Ray Photoelectron Spectroscopy (XPS), confirming the conversion process of Fe(Ⅱ) to Fe(Ⅲ) on the sulfur defect sites. Electron Spin Resonance (ESR) test showed that pyrite photochemical reaction produced hydroxyl radical (·OH). The results of high performance liquid chromatography (HPLC) and liquid chromatograph-mass spectrometer (LC-MS) showed that visible light irradiation could effectively activate pyrite to degrade MC-LR. The degradation rate of MC-LR reached 100% after 10 hours and the mineralization rate reached 60% after 20 hours. The two reaction pathways of photochemical oxidation of MC-LR by pyrite were discussed.

Knockdown of Dynamitin in testes significantly decreased male fertility in Drosophila melanogaster.

Dynamitin (Dmn) is a major component of dynactin, a multiprotein complex playing important roles in a variety of intracellular motile events. We previously found that Wolbachia bacterial infection resulted in a reduction of Dmn protein. As Wolbachia may modify sperm in male hosts, we speculate that Dmn may have a function in male fertility. Here we used nosGal4 to drive Dmn knock down in testes of Drosophila melanogaster to investigate the functions of Dmn in spermatogenesis. We found that knockdown of Dmn in testes dramatically decreased male fertility, overexpression of Dmn in Wolbachia-infected males significantly rescued male fertility, indicating an important role of Dmn in inducing male fertility defects following Wolbachia infection. Some scattered immature sperm with late canoe-shaped head distributed in the end of Dmn knockdown testis and only about half mature sperm were observed in the Dmn knockdown testis relative to those in the control. Transmission electron microscopy (TEM) exhibited fused spermatids in cysts and abnormal mitochondrial derivatives. Immunofluorescence staining showed significantly less abundance of tubulin around the nucleus of spermatid and scattered F-actin cones to different extents in the individualization complex (IC) during spermiogenesis in Dmn knockdown testes, which may disrupt the nuclear condensation and sperm individualization. Since dynein-dynactin complex has been shown to mediate transport of many cellular components, including mRNAs and organelles, these results suggest that Dmn may play an important role in Drosophila spermiogenesis by affecting transport of many important cytoplasmic materials.

Knockdown of ATPsyn-b caused larval growth defect and male infertility in Drosophila.

The ATPsyn-b encoding for subunit b of ATP synthase in Drosophila melanogaster is proposed to act in ATP synthesis and phagocytosis, and has been identified as one of the sperm proteins in both Drosophila and mammals. At present, its details of functions in animal growth and spermatogenesis have not been reported. In this study, we knocked down ATPsyn-b using Drosophila lines expressing inducible hairpin RNAi constructs and Gal4 drivers. Ubiquitous knockdown of ATPsyn-b resulted in growth defects in larval stage as the larvae did not grow bigger than the size of normal second-instar larvae. Knockdown in testes did not interrupt the developmental excursion to viable adult flies, however, these male adults were sterile. Analyses of testes revealed disrupted nuclear bundles during spermatogenesis and abnormal shaping in spermatid elongation. There were no mature sperm in the seminal vesicle of ATPsyn-b knockdown male testes. These findings suggest us that ATPsyn-b acts in growth and male fertility of Drosophila.