• Ulrich Kenney opublikował 1 rok, 8 miesięcy temu

    ATP-binding cassette (ABC) transporters represent the largest known group of efflux pumps, utilizing ATP to translocate a broad spectrum of substrates across lipid membranes, which play an important role in phase III of the detoxification process. The presence of ABC transporters and their potential association with insecticide resistance have not been investigated in Aphis gossypii, one of the most economically important agricultural pests worldwide. In this study, the ABC transporter inhibitor-verapamil significantly increased thiamethoxam toxicity against resistant cotton aphids, suggesting that ABCs are involved in thiamethoxam resistance. ABC transporter genes were identified using the A. gossypii genome database and transcriptome data. A total of 69 ABC transporters were identified and grouped into seven subfamilies (A-G), including 4 ABCAs, 5 ABCBs, 25 ABCCs, 2 ABCDs, 1 ABCE, 4 ABCFs and 30 ABCGs. Of these ABC transporters, 53 were predicted to be functional, 19 were full transporters, 30 were half-transporters and 4 had two NBDs. Subfamilies C and G accounted for 77% (32 and 45%, respectively) of the genes. The transcripts of 20 of 26 ABCs based on the transcriptome were upregulated, and ABCA1, ABCA2, ABCB1, ABCB4, ABCB8, ABCD1, ABCD2, ABCE1, ABCF1, ABCF3, ABCG7, ABCG15, ABCG17, ABCG24, ABCG27, ABCG30, MRP1, MRP7, MRP14 and MRP21 transcripts were significantly increased in the thiamethoxan resistant strain compared to the susceptible strain with qRT-PCR. The suppression of overexpressed ABCs (ABCA2, ABCD1, ABCD2, ABCE1 and ABCG15) significantly increased the thiamethoxam sensitivity of resistant aphids. These results suggest that ABC transporters might be involved in thiamethoxam resistance in A. gossypii and will facilitate further work to validate the functional roles of these ABCs in thiamethoxam resistance. These results are useful for understanding the multiple resistance mechanisms of thiamethoxam and the management of insecticide-resistant cotton aphids.The physiological and iTRAQ-based proteomic analyses were used to reveal the inhibitory roles of pinocembrin on mitochondria of P. italicum and its cell death mechanism. The results show that pinocembrin damages both mitochondrial structure and function. 167 and 807 differentially expressed proteins (DEPs) were detected in P. italicum mycelia after treatment with pinocembrin for 8 h and 24 h respectively, and the DEPs were significantly enriched in the oxidative phosphorylation (OXPHOS) pathway, especially for mitochondrial respiratory chain (MRC) complexes I and V. Furthermore, the expression levels of proteins related to programmed cell death (PCD) were significantly up-regulated in mycelia with Pinocembrin incubation for 24 h. Combined with the results of physio-chemical analysis, the data revealed that pinocembrin targeted MRC complexes I and V, to induce ATP depletion, enhance ROS accumulation, stimulate mitochondrial permeability transition pore (MPTP) opening, accelerate the loss of mitochondrial membrane potential (MMP) and promote cytochrome c release from mitochondria to the cytoplasm, which, as a result, effectively triggered three classical types of PCD pathways in mycelia of P. italicum.A polysaccharide DNPE6(11) was purified from Dendrobium nobile Lindl. (D. nobile Lindl.). Its structural characteristic, antiviral activity, and preliminary mechanism were studied. The structural characteristic analysis indicated that DNPE6(11) was a novel homogenous heteropolysaccharide from D. nobile Lindl. Bioactivity assays indicated that DNPE6(11) possessed outstanding curative and inactivating activities against cucumber mosaic virus, which were superior to chitosan oligosaccharide and lentinan. Additionally, DNPE6(11) exhibited notable protective activity against potato virus Y, which was better than Ningnanmycin. Furthermore, the preliminary mechanism study found that DNPE6(11) cannot accumulate salicylic acid to induce systemic acquired resistance, but had a strong binding capacity for cucumber mosaic virus coat protein. Therefore, DNPE6(11) could be considered as a promising antiviral agent to study in the future.Dinotefuran, the third-generation neonicotinoid, has been applied against melon/cotton aphid Aphis gossypii Glover in China. The risk of resistance development, cross-resistance pattern and potential resistance mechanism of dinotefuran in A. gossypii were investigated. A dinotefuran-resistant strain of A. gossypii (DinR) with 74.7-fold resistance was established by continuous selection using dinotefuran. The DinR strain showed a medium level of cross resistance to thiamethoxam (15.2-fold), but no cross resistance to imidacloprid. The synergism assay indicated that piperonyl butoxide and triphenyl phosphate showed synergistic effects on dinotefuran toxicity to the DinR strain with a synergistic ratio of 8.3 and 2.5, respectively, while diethyl maleate showed no synergistic effect. The activities of cytochrome P450 monooxygenase and carboxylesterase were significantly higher in DinR strain than in susceptible strain (SS). Moreover, the gene expression results showed that CYP6CY14, CYP6CY22 and CYP6UN1 were significantly overexpressed in DinR strain compared with SS strain. The expression of CYP6CY14 was 5.8-fold higher in DinR strain than in SS strain. Additionally, the transcription of CYP6CY14, CYP6CY22 and CYP6UN1 in A. gossypii showed dose- and time-dependent responses to dinotefuran exposure. Furthermore, knockdown of CYP6CY14, CYP6CY22 and CYP6UN1 via RNA interference (RNAi) significantly increased mortality of A. gossypii, when A. gossypii was treated with dinotefuran. These results demonstrated the overexpression of CYP6CY14, CYP6CY22 and CYP6UN1 contributed to dinotefuran resistance in A. gossypii.Methyl parathion (MP) is a commonly used organophosphorus insecticide in commercial farming. It is well known that MP exposure can affect the function of nervous, respiratory, cardiovascular and reproductive systems. In our previous report we have demonstrated that MP exposure results in poor oocyte maturation and defective embryo development which is mainly mediated through oxidative stress. The present investigation was designed to explore whether using a potent free radical scavenger like Epigallocatechin-3-gallate (EGCG) can help in reducing the detrimental effects of MP on the oocytes. For the study, germinal vesicle (GV) stage oocytes collected from the ovaries of adult Swiss albino mice were subjected to in vitro maturation (IVM) in the presence or absence of MP (100 μg/mL) and/or EGCG (0.25 μM). MP significantly reduced the nuclear maturation rate, and resulted in poor cytoplasmic organization which was evident from the altered distribution pattern of mitochondria, endoplasmic reticulum and abnormal spindle organization. These changes were associated with significant elevation in oxidative stress and expression of ER stress markers such as 78 kDa Glucose regulated protein (GRP78) as well as X-box binding protein-1 (XBP1) in the oocytes. Further, the oocytes exposed to MP had lower activation rate and developmental potential. Supplementation of EGCG during IVM not only improved the nuclear maturation rate but also reduced the cytoplasmic abnormalities. These beneficial effects appear to be due to mitigation of oxidative and ER stress in oocytes. In conclusion, results of our study indicate that EGCG can help in alleviating MP-induced oocyte abnormalities.We have investigated the effect of subchronic exposure to tetradifon (TDF), as an endocrine disruptor chemical, on some parameters related to serious metabolomic disorders such as obesity, type 2 diabetes and hyperlipidemia. TDF promoted significant increases in both duodenal and pancreatic α-amylase and lipase especially in the 12-weeks treated rats. Plasmatic glucose and lipid profile; total cholesterol (T-cholesterol), low density lipoprotein-cholesterol (LDL-c), high-density lipoprotein-cholesterol (HDL-c) and glyceride, were markedly disrupted. Compared with controls, biochemical liver injury parameters aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT) and lactate dehydrogenase (LDH) were significantly increased. Moreover, notable pathological features were reported in liver tissues. These results confirm a strong relationship between exposure to an endocrine disruptor and metabolic disorders. In fact, subchronic exposure to TDF lead to lipidemic and glycemic disruption associated hyperactivity in both α-amylase and lipase. Overall, these disruptions could be an important step on the pathway to metabolic pathology.Translaminar redistribution is valuable for fungicide activity but difficult to measure and predict. The translaminar activity of 38 fungicides active against cucumber powdery mildew was measured experimentally and used to develop a QSAR (Quantitative structure-activity relationship) model of translaminar movement from calculated parameters. Over 300 physiochemical parameters generated from energy-minimized 3D structures were considered and one-parameter, two-parameter, and five-parameter models were developed. The one-parameter lipophilicity model explained 39% of variability in translaminar activity in the full dataset but none of the variability in the small succinate dehydrogenase inhibitor (SDHI) set. Adding a polar surface area parameter to the lipophilicity parameter improved predictability to 52% and explained over 70% of the variability in the SDHI class. The expanded model with five physiochemical parameters explained more than 80% of the variability in overall translaminar redistribution. The three additional parameters were correlated with molecular size and reactivity. The models were validated with a Leave-One-Out method that showed excellent robustness (r2adj = 0.83, q2 = 0.79, p less then .0001) for the five-parameter model. Because the models require only calculated parameters from a 3D chemical structure, they could enable the design or selection of compounds likely to be translaminar.Bacillus thuringiensis (Bt) Cry1Fa and Cry1Ab proteins are important Cry toxins due to their high, selective toxicity against a number of lepidopteran species, including important pests of corn and cotton. Competition binding assays are a classical tool for investigating Cry toxin interactions with target pest insects. We developed a fluorescence-based binding assay and assessed Cry1Fa and Cry1Ab toxin binding to brush border membrane preparations from lepidopteran corn pests including Ostrinia nubilalis (European corn borer, ECB), Diatraea grandiosella (south western corn borer, SWCB), and Helicoverpa zea (corn earworm, CEW). Homologous and heterologous competition binding assays with fluorophore-(Alexa488)-labeled Cry1Fa toxin showed that Cry1Fa shares binding site(s) with Cry1Ab toxin in ECB, and SWCB for which Cry1Ab has higher affinity than Cry1Fa. Apart from the shared binding sites, Cry1Ab and Cry1Fa bind an additional site(s) in ECB and SWCB. In CEW, Cry1Fa and Cry1Ab each, has a high affinity binding site(s), which binds the heterologous toxin with low affinity. The Cry1Ab-Cry1Fa toxin binding models for ECB, SWCB and CEW based on our results are considered in the context of what is known about acquired cross-resistance against Cry1Ab and Cry1Fa toxins.

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