Phenyl imidazolidin-2-ones antagonize a ß-adrenergic-like octopamine receptor in diamondback moth (Plutella xylostella).

BACKGROUND: The diamondback moth (Plutella xylostella) is one of the most destructive lepidopteran pests on cruciferous vegetables. However, resistance has emerged to current chemical and biological insecticides used for P. xylostella control, indicating the necessity of screening new targets on P. xylostella, and finding new insecticides against P. xylostella. In particular, octopamine receptors are representative G protein-coupled receptors found only in invertebrates and are potential targets for identifying novel insecticides. RESULTS: A ß-adrenergic-like octopamine receptor gene (PxOA2B1) was cloned, and its pharmacological characteristics in P. xylostella were studied. The results demonstrated that octopamine could activate the PxOA2B1 receptor, with a half-maximal effective concentration (EC50 ) of 49.5 nm. Amitraz, an insecticide and acaricide, and its metabolite (N-2,4-dimethylphenyl-N'-methylformamidine; DPMF) were also found to act as PxOAB1R agonists. We synthesized phenyl imidazolidin-2-one derivatives 3a-h using DPMF as the lead compound, and compounds 3a-h showed similar antagonist activities as phentolamine, mianserin and chlorpromazine. In particular, 3d, with an EC50 of 25.2 nm, showed very similar antagonist activity to mianserin. CONCLUSION: This research found that PxOAB1R might be a potential target for P. xylostella control. Phenyl imidazolidin-2-ones could be novel potential antagonists targeted at octopamine receptors and would be useful tools for the design and development of novel insecticides. © 2021 Society of Chemical Industry.

Expression and alternative splicing analysis of a large-conductance calcium-activated potassium channel gene in Plutella xylostella.

The large-conductance calcium-activated potassium channel (BKCa ) plays an important role in the regulation of insect neural circuits and locomotion, and thus is a potential target of insecticides. In this study, iberiotoxin, an inhibitor of BKCa , was found to prolong the anesthetic time of ethyl acetate on Plutella xylostella larvae. Therefore, the coding sequence of slowpoke gene coding the alpha subunit of BKCa was cloned to investigate the function of this channel in P. xylostella, and the gene expression profile in the developmental stages and tissues was also characterized. The total length of pxslo DNA was more than 19.9 kb, which harbored four alternative splicing sites (ASP-A, ASP-C, ASP-E, and ASP-G), and the coding sequence of pxslo with the highest frequency of splicing (GenBank ID: MN938456) was 3,405 base pair. The characterized PxSlo protein contained conserved domains previously identified in other insects. Quantitative reverse transcription-polymerase chain reaction analysis showed that pxslo was expressed in all the developmental stages of P. xylostella, with the highest level in adults. In the larval stage, pxslo was mainly expressed in the head and epidermis, while a limited protein was expressed in the midgut. In the adult stage, pxslo was highly expressed in the head, followed by in the ovarian tubule, and was not expressed in the testis or wings. These results suggest that BKCa plays an important physiological role in P. xylostella and provides useful information for the functional study and screening of BKCa inhibitors.

Facile Fabrication of Superhydrophobic Copper- Foam and Electrospinning Polystyrene Fiber for Combinational Oil⁻Water Separation.

Membrane-based metal substrates with special surface wettability have been applied widely for oil/water separation. In this work, a series of copper foams with superhydrophobicity and superoleophilicity were chemically etched using 10 mg mL-1 FeCl3/HCl solution with consequent ultrasonication, followed by the subsequent modification of four sulfhydryl compounds. A water contact angle of 158° and a sliding angle lower than 5° were achieved for the copper foam modified using 10 mM n-octadecanethiol solution in ethanol. In addition, the interaction mechanism was initially investigated, indicating the coordination between copper atoms with vacant orbital and sulfur atoms with lone pair electrons. In addition, the polymeric fibers were electrospun through the dissolution of polystyrene in a good solvent of chlorobenzene, and a nonsolvent of dimethyl sulfoxide. Oil absorption and collection over the water surface were carried out by the miniature boat made out of copper foam, a string bag of as-spun PS fibers with high oil absorption capacity, or the porous boat embedded with the as-spun fibers, respectively. The findings might provide a simple and practical combinational method for the solution of oil spill.

[Effect of alisol A 24-acetate on proliferation of aorta smooth muscle cells in rats induced by ox-LDL].

Alisol A 24-acetate, a triterpenoid extracted from Alisma orientale, has shown anti-atherosclerotic actions and many studies have proved that oxidized low density lipoprotein (Ox-LDL) could promote proliferation of aorta smooth muscle cells (VSMCs) which are closely related to atherosclerosis (AS). The purpose of this study was to evaluate the effect of alisol A 24-acetate on the proliferation of VSMCs isolated from the thoracic aorta of rats induced by ox-LDL. VSMCs were induced by ox-LDL(50 mg·L⁻¹) to establish the proliferation model and intervened by alisol A 24-acetate (5, 10, 20 mg·L⁻¹) for 12, 24 and 48 h. Then the proliferation of VSMCs was detected by MTT assay; protein expression levels of VSMCs PCNA, cyclinD1, cyclinE, p21, p27 and VSMCs PCNA, p21and p27 mRNA expression levels were detected by Western blot and Real-time polymerase chain reaction (RT-PCR) respectively. The results showed that ox-LDL could induce the proliferation of VSMCs (P<0.05), increase the protein expression levels of PCNA, cyclinD1 and cyclinE in the VSMCs (P<0.05) and inhibit the protein and mRNA expression levels of p21 and p27 (P<0.05). As compared with the model group, alisol A 24-acetate inhibited the proliferation of VSMCs in rats induced by ox-LDL and inhibited the protein expression of VSMCs PCNA, cyclinD1, cyclinE and enhanced the protein and mRNA p21 and p27 expression levels (P<0.05). The effect was more obvious with the increase of concentration of alisol A 24-acetate. These data indicate that alisol A 24-acetate can inhibit the proliferation of VSMCs induced by ox-LDL and the mechanism may be associated with inhibiting expression of cyclin protein, including cyclinD1, cyclinE, p21, p27 and so on.

Pharmacological characterization of a ß-adrenergic-like octopamine receptor in Plutella xylostella.

The ß-adrenergic-like octopamine receptor (OA2B2) belongs to the class of G-protein coupled receptors. It regulates important physiological functions in insects, thus is potentially a good target for insecticides. In this study, the putative open reading frame sequence of the Pxoa2b2 gene in Plutella xylostella was cloned. Orthologous sequence alignment, phylogenetic tree analysis, and protein sequence analysis all showed that the cloned receptor belongs to the OA2B2 protein family. PxOA2B2 was transiently expressed in HEK-293 cells. It was found that PxOA2B2 could be activated by both octopamine and tyramine, resulting in increased intracellular cyclic AMP (cAMP) levels, whereas dopamine and serotonin were not effective in eliciting cAMP production. Further studies with series of PxOA2B2 agonists and antagonists showed that all four tested agonists (e.g., naphazoline, clonidine, 2-phenylethylamine, and amitraz) could activate the PxOA2B2 receptor, and two of tested antagonists (e.g., phentolamine and mianserin) had significant antagonistic effects. However, antagonist of yohimbine had no effects. Quantitative real-time polymerase chain reaction analysis showed that Pxoa2b2 gene was expressed in all developmental stages of P. xylostella and that the highest expression occurred in male adults. Further analysis with fourth-instar P. xylostella larvae showed that the Pxoa2b2 gene was mainly expressed in Malpighian tubule, epidermal, and head tissues. This study provides both a pharmacological characterization and the gene expression patterns of the OA2B2 in P. xylostella, facilitating further research for insecticides using PxOA2B2 as a target.

RNA interference-mediated knockdown of the hydroxyacid-oxoacid transhydrogenase gene decreases thiamethoxam resistance in adults of the whitefly Bemisia tabaci.

Bemisia tabaci has developed a high level of resistance to thiamethoxam, a second generation neonicotinoid insecticide that has been widely used to control this pest. In this study, we investigated whether hydroxyacid-oxoacid transhydrogenase (HOT) is involved in resistance to the neonicotinoid insecticide thiamethoxam in the whitefly. We cloned the full-length gene that encodes HOT in B. tabaci. Its cDNA contains a 1428-bp open reading frame encoding 475 amino acid residues. Then we evaluated the mRNA expression level of HOT in different developmental stages, and found HOT expression was significantly greater in thiamethoxam resistance adults than in thiamethoxam susceptible adults. Subsequently, seven field populations of B. tabaci adults were sampled, the expression of mRNA level of HOT significant positive correlated with thiamethoxam resistance level. At last, we used a modified gene silencing system to knock-down HOT expression in B. tabaci adults. The results showed that the HOT mRNA levels decreased by 57% and thiamethoxam resistance decreased significantly after 2 days of feeding on a diet containing HOT dsRNA. The results indicated that down-regulation of HOT expression decreases thiamethoxam resistance in B. tabaci adults.

Alisol A 24-Acetate, a Triterpenoid Derived from Alisma orientale, Inhibits Ox-LDL-Induced Phenotypic Transformation and Migration of Rat Vascular Smooth Muscle Cells through Suppressing ERK1/2 Signaling.

Alisol A 24-acetate, a triterpenoid extracted from Alisma orientale, has shown antiatherosclerotic actions. The purpose of this study was to evaluate the inhibition of alisol A 24-acetate on oxidized low-density lipoprotein (Ox-LDL)-induced phenotypic transformation and migration of rat vascular smooth muscle cells (VSMCs), and to explore the underlying mechanisms. VSMCs were pretreated with alisol A 24-acetate and a specific extracellular signal-regulated kinase (ERK) inhibitor, U0126, and then stimulated with 50 mg/l Ox-LDL in vitro. The expression of VSMC phenotypic marker SM22α was determined using immunocytochemistry, and the migration of VSMCs was detected using a scratch-wound healing assay. The expression of matrix metalloproteinase (MMP)-9, MMP-2, phosphorylated ERK1/2 (pERK1/2) and total ERK was determined. Ox-LDL treatment caused a reduction in SM22α expression, VSMC transformation to the synthetic phenotype, increased MMP-2 and MMP-9 synthesis, the extension of VSMC migration distance and the upregulation of pERK1/2 expression, while the addition of alisol A 24-acetate or U0126 resulted in the elevation of SM22α expression, VSMC transformation to the contractile phenotype, a reduction in MMP-2 and MMP-9 expression, the shortening of cell migration distance and decreased pERK1/2 expression. The results of this study demonstrate that alisol A 24-acetate effectively reverses the phenotypic transformation and inhibits the migration of VSMCs, which may be associated with the suppression of the ERK1/2 signaling pathway.

Chiral Ferrocenyl P,N-Ligands for Palladium-Catalyzed Asymmetric Formal [3 + 2] Cycloaddition of Propargylic Esters with ß-Ketoesters: Access to Functionalized Chiral 2,3-Dihydrofurans.

A highly enantioselective palladium-catalyzed [3 + 2] cycloaddition of propargylic esters with ß-ketoesters has been realized by employing a newly developed chiral ferrocene/benzimidazole-based P,N-ligand. This protocol features a good tolerance of functional groups in both propargylic esters and ß-ketoesters, thereby delivering a variety of highly functionalized chiral 2,3-dihydrofurans bearing an exocyclic double bond at the 3-position in good yields and with high enantioselectivities (up to 98% ee).

Inhibition of ERK1/2 improves lipid balance in rat macrophages via ABCA1/G1 and CD36.

ATP-binding cassette transporters A1 (ABCA1) and G1 (ABCG1), and macrophage scavenger receptor, cluster of differentiation (CD)36, function as key mediators of cholesterol efflux and influx from macrophages. In addition, they are associated with foam cell formation and the development of atherosclerosis (AS). The aim of the present study was to investigate the effects of extracellular signal-regulated kinases 1/2 (ERK1/2) inhibition on lipid balance in oxidized-low-density lipoprotein (Ox-LDL)-stimulated rat macrophages, and to examine the role of ERK1/2 inhibitors in AS. Rat peritoneal macrophages were treated with Ox-LDL alone or in combination with an ERK1/2 inhibitor, U0126, and untreated cells served as controls. Ox-LDL-induced lipid accumulation was detected by DiI fluorescence and oil red O staining. In addition, the mRNA and protein expression levels of ABCA1, ABCG1 and CD36 were determined using polymerase chain reaction and western blotting, respectively. Treatment with Ox-LDL significantly increased lipid accumulation and upregulated the mRNA and protein expression levels of ABCA1, ABCG1 and CD36 in macrophages. The addition of U0126 resulted in a marked reduction of lipid deposition, upregulation of ABCA1/G1 expression and suppression of CD36 expression in Ox-LDL-stimulated macrophages. The results of the present study indicated a novel association between ERK1/2 signaling and lipid metabolism, thus suggesting that inhibition of ERK1/2 may be considered a promising therapeutic strategy against AS.

Manipulation of Host Quality and Defense by a Plant Virus Improves Performance of Whitefly Vectors.

Pathogen-mediated interactions between insect vectors and their host plants can affect herbivore fitness and the epidemiology of plant diseases. While the role of plant quality and defense in mediating these tripartite interactions has been recognized, there are many ecologically and economically important cases where the nature of the interaction has yet to be characterized. The Bemisia tabaci (Gennadius) cryptic species Mediterranean (MED) is an important vector of tomato yellow leaf curl virus (TYLCV), and performs better on virus-infected tomato than on uninfected controls. We assessed the impact of TYLCV infection on plant quality and defense, and the direct impact of TYLCV infection on MED feeding. We found that although TYLCV infection has a minimal direct impact on MED, the virus alters the nutritional content of leaf tissue and phloem sap in a manner beneficial to MED. TYLCV infection also suppresses herbivore-induced production of plant defensive enzymes and callose deposition. The strongly positive net effect on TYLCV on MED is consistent with previously reported patterns of whitefly behavior and performance, and provides a foundation for further exploration of the molecular mechanisms responsible for these effects and the evolutionary processes that shape them.

Chiral 1-phenylethylamine-derived phosphine-phosphoramidite ligands for highly enantioselective Rh-catalyzed hydrogenation of beta-(acylamino)acrylates: significant effect of substituents on 3,3'-positions of binaphthyl moiety.

A series of new chiral phosphine-phosphoramidite ligands with a 3,3'-substituted binaphthyl moiety were prepared from 1-phenylethylamine, and successfully applied in the Rh-catalyzed asymmetric hydrogenation of beta-(acylamino)-acrylates. The research disclosed that the substituents on the 3,3'-positions of binaphthyl moiety significantly influenced the enantioselectivity.

Cloning and characterization of a GABA receptor from Plutella xylostella (Lepidoptera: Plutellidae).

A full-length cDNA, with an open reading frame (ORF) of 1,449 bp, encoding a subunit of the gamma-aminobutyric acid (GABA)-activated chloride channel was isolated from Plutella xylostella (L.) (Lepidoptera: Plutellidae) (GenBank accession no. EF156251). The subunit gene encoded a 483-amino acid polypeptide that showed 84% sequence identity with DmRdl subunit (U02042) (Drosophila melanogaster resistant to dieldrin). When expressed in Xenopus laevis oocytes, the subunit assembled as a functional homomeric complex activated by GABA and abamectin in a dose-dependent manner. The EC50 value of GABA was 0.49 mM (0.41-0.58) (n = 5). However, the responses to abamectin were very robust, with an EC50 of 4.85 microM (4.02-5.89) (n = 6), indicating that abamectin was > 100-fold more potent in activating chloride currents than GABA. The results suggest that this subunit is vital to the formation of a functional channel and contains the binding site of abamectin.