Determination of 47 Pesticide Residues in Tea by QuEChERS Method Combined with Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry

An analysis method for simultaneous determination of 47 kinds of pesticide residues in tea was established by QuEChERS method combined with ultra performance liquid chromatography-tandem mass spectrometry. The samples were extracted by acetonitrile containing 1% acetic acid, and purified by QuEChERS method. The 47 pesticides were determined by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) with an electrospray ion source (ESI±) in positive and negative ion switching multiple reaction monitoring (MRM), and quantified by matrix-matched external standard method. Method validation revealed satisfactory linearities with correlation coefficients (r) between 0.9971 and 0.9996, and limits of detection were 0.001~0.006 mg/kg while the limits of quantitation were 0.002~0.020 mg/kg, the average recoveries at three spiked levels were in the range of 73.4%~114.3%, with relative standard deviations (n=6) of 0.3%~19.9%. The method is sensitive, accurate, stable, and can meet the requirements for determination of 47 pesticide residues in tea

Characterization of <i>Pseudomonas</i> sp. En3, an Endophytic Bacterium from Poplar Leaf Endosphere with Plant Growth-Promoting Properties

Growth-promoting endophytic bacteria possess substantial potential for sustainable agriculture. Here, we isolated an endophytic bacterium, Pseudomonas sp. En3, from the leaf endosphere of Populus tomentosa and demonstrated its significant growth-promoting effects on both poplar and tomato seedlings. The phosphorus solubilization and nitrogen fixation abilities of strain En3 were confirmed via growth experiments on NBRIP and Ashby media, respectively. Salkowski staining and HPLC-MS/MS confirmed that En3 generated indole-3-acetic acid (IAA). The infiltration of En3 into leaf tissues of multiple plants did not induce discernible disease symptoms, and a successful replication of En3 was observed in both poplar and tobacco leaves. Combining Illumina and Nanopore sequencing data, we elucidated that En3 possesses a circular chromosome of 5.35 Mb, exhibiting an average G + C content of 60.45%. The multi-locus sequence analysis (MLSA) and genome average nucleotide identity (ANI) supported that En3 is a novel species of Pseudomonas and constitutes a distinct phylogenetic branch with P. rhizosphaerae and P. coleopterorum. En3 genome annotation analysis revealed the presence of genes associated with nitrogen fixation, phosphate solubilization, sulfur metabolism, siderophore biosynthesis, synthesis of IAA, and ethylene and salicylic acid modulation. The findings suggest that Pseudomonas sp. En3 exhibits significant potential as a biofertilizer for crop and tree cultivation

Methyl-Hispolon from Phellinus lonicerinus (Agaricomycetes) Affects Estrogen Signals in MCF-7 Breast Cancer Cells and Premature Aging in Rats

We studied Phellinus lonicerinus to determine the cytotoxic effect and the dual estrogenic activities of methyl-hispolon and their relation to estrogen signals in vivo and in vitro. The Glide scores of methyl-hispolonestrogen receptor alpha (ER alpha) and methyl-hispolon-ER beta docked complexes were -7.29 kcal/mol and -6.68 kcal/mol in docking simulations. Methyl-hispolon had a significant antiproliferative effect for estrogen-sensitive ER(+) MCF-7 cells in the absence of estrogen, and it exhibited dual estrogen activities. Methyl-hispolon increased the serum E-2 in rats with premature ovarian failure and fulfilled the estrogenic function in the uterus and ovary. Methyl-hispolon significantly inhibited the expression of Ras, AP1, ER alpha, C-myc, and cyclinD1, as well as their gene transcription in RL95-2 cells. The phosphorylation of ERK1/2 was inhibited by methyl-hispolon. Thus, methyl-hispolon has potential use in treating estrogen deficiency-related diseases, with good antitumor effects and estrogenic activity