scholarly journals Insect Resistance to Neonicotinoids - Current Status, Mechanism and Management Strategies

2021 ◽  
Author(s):  
Shrawan Kumar Sahani ◽  
Vikas Kumar ◽  
Subhajit Pal
Keyword(s):  
Nicotinic Acetylcholine Receptors ◽  
Resistance Management ◽  
Detoxification Enzymes ◽  
Current Status ◽  
Cytochrome P450 Monooxygenases ◽  
Excessive Pressure ◽  
P450 Monooxygenases ◽  
Development Of Resistance ◽  
Application Techniques ◽  
Exposure Risks

Pesticides are any substance used for controlling, preventing, destroying, repelling, or mitigating of pests. Neonicotinoids have been the most commonly used insecticide since the early 1990s, current market share of more than 25% of total global insecticide sales. Neonicotinoid insecticides are highly selective agonists of insect nicotinic acetylcholine receptors (nAChRs) that exhibit physicochemical properties, rendering them more useful over other classes of insecticides. This includes having a wide range of application techniques and efficacy in controlling sucking and biting insects. Although neonicotinoids are applied as foliar insecticides with possible direct exposure risks to honeybees, a large part of neonicotinoid use consists of seed coating or root drench application. There are three major detoxification enzymes involved in the development of resistance against insecticides viz., cytochrome P450 monooxygenases, carboxylesterases, and glutathione S-transferases. The repeatedly used use of compounds of the same active ingredients and application of excessive organophosphates (OPs) and pyrethroids in Bemisia tabaci. Resistance to insecticides resulting in loss of efficacy of many older insecticides has placed excessive pressure on novel products. One of the major limitations to resistance management is the occurrence of cross-resistance. This review briefly summarizes the current status of neonicotinoid resistance, the biochemical and mechanisms involved, and the implications for resistance management.

scholarly journals Knock-Down of Gossypol-Inducing Cytochrome P450 Genes Reduced Deltamethrin Sensitivity in Spodoptera exigua (Hübner)

2019 ◽  
Vol 20 (9) ◽  
pp. 2248 ◽  
Author(s):  
Muhammad Hafeez ◽  
Sisi Liu ◽  
Saad Jan ◽  
Le Shi ◽  
G. Mandela Fernández-Grandon ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Secondary Metabolites ◽  
Molecular Mechanisms ◽  
Spodoptera Exigua ◽  
Plant Secondary Metabolites ◽  
Detoxification Enzymes ◽  
Beet Armyworm ◽  
Cytochrome P450 Monooxygenases ◽  
Control Group ◽  
P450 Monooxygenases

Plants employ an intricate and dynamic defense system that includes physiological, biochemical, and molecular mechanisms to counteract the effects of herbivorous attacks. In addition to their tolerance to phytotoxins, beet armyworm has quickly developed resistance to deltamethrin; a widely used pyrethroid insecticide in cotton fields. The lethal concentration (LC50) required to kill 50% of the population of deltamethrin to gossypol-fed Spodoptera exigua larvae was 2.34-fold higher than the control group, suggesting a reduced sensitivity as a consequence of the gossypol diet. Piperonyl butoxide (PBO) treatment was found to synergize with deltamethrin in gossypol-fed S. exigua larvae. To counteract these defensive plant secondary metabolites, beet armyworm elevates their production of detoxification enzymes, including cytochrome P450 monooxygenases (P450s). Gossypol-fed beet armyworm larvae showed higher 7-ethoxycoumarin-O-deethylase (ECOD) activities and exhibited enhanced tolerance to deltamethrin after 48 and 72 h when compared to the control. Moreover, gossypol pretreated S. exigua larvae showed faster weight gain than the control group after transferring to a deltamethrin-supplemented diet. Meanwhile, gossypol-induced P450s exhibited high divergence in the expression level of two P450 genes: CYP6AB14 and CYP9A98 in the midgut and fat bodies contributed to beet armyworm tolerance to deltamethrin. Knocking down of CYP6AB14 and CYP9A98, via double-stranded RNAs (dsRNA) in a controlled diet, rendered the larvae more sensitive to the insecticide. These data demonstrate that generalist insects can exploit secondary metabolites from host plants to enhance their defense systems against other toxic chemicals. Impairing this defense pathway by RNA interference (RNAi) holds a potential to eliminate the pest’s tolerance to insecticides and, therefore, reduce the required dosages of agrochemicals in pest control.

scholarly journals Susceptibility to acaricides and detoxifying enzyme activities in the red spider mite, Oligonychus coffeae Nietner (Acari: Tetranychidae)

Acarologia ◽  
2018 ◽  
Vol 58 (3) ◽  
pp. 647-654
Author(s):  
Somnath Roy ◽  
Anjali Km. Prasad ◽  
Gautam Handique ◽  
Bipanchi Deka
Keyword(s):  
Spider Mite ◽  
Management Strategies ◽  
Resistance Management ◽  
Management Program ◽  
Cytochrome P450 Monooxygenases ◽  
Tea Plantation ◽  
P450 Monooxygenases ◽  
Red Spider Mite ◽  
Median Lethal Concentrations ◽  
Oligonychus Coffeae

Susceptibility of red spider mite, Oligonychus coffeae Nietner (Acari: Tetranychidae), collected from conventionally-managed (synthetic acaricide usage) versus an organicallymanaged (no acaricide usage) tea plantations in Assam, India, to five synthetic acaricides was determined in laboratory bioassays. Activity of three principal detoxifying enzymes of these mite populations was also assayed. The median lethal concentrations (LC50) of ethion, dicofol, propargite, fenpropathrin, and fenazaquin were 1049.75, 599.21, 232.03, 11.44, and 6.75 ppm, respectively. Field rates of these acaricides were compared with 95% lethal concentration (LC95 in ppm) values, and a decrease in the susceptibility of the test population to ethion, propargite, dicofol and fenpropathrin was observed. There was no change for fenazaquin which was effective at lower doses than the recommended dose. Of all the acaricides tested, fenazaquin was the most toxic and ethion was the least toxic. General esterases (GEs), glutathione- S-transferase (GST), and cytochrome P450 monooxygenases exhibited a higher activity in mite population from the conventionallymanaged tea plantation as compared with the activity in mites from the organicallymanaged tea plantation. These findings may be helpful in the selection of acaricides and in developing resistance management strategies for an effective management program for this major tea pest.

Focal Adhesion Kinase in Ovarian Cancer: A Potential Therapeutic Target for Platinum and Taxane-Resistant Tumors

2019 ◽  
Vol 19 (3) ◽  
pp. 179-188 ◽  
Author(s):  
Arkene Levy ◽  
Khalid Alhazzani ◽  
Priya Dondapati ◽  
Ali Alaseem ◽  
Khadijah Cheema ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Focal Adhesion Kinase ◽  
Focal Adhesion ◽  
Tumor Stage ◽  
Current Status ◽  
Potential Therapeutic Target ◽  
Resistant Disease ◽  
Development Of Resistance ◽  
And Function ◽  
Mdr 1

Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase, which is an essential player in regulating cell migration, invasion, adhesion, proliferation, and survival. Its overexpression and activation have been identified in sixty-eight percent of epithelial ovarian cancer patients and this is significantly associated with higher tumor stage, metastasis, and shorter overall survival of these patients. Most recently, a new role has emerged for FAK in promoting resistance to taxane and platinum-based therapy in ovarian and other cancers. The development of resistance is a complex network of molecular processes that make the identification of a targetable biomarker in platinum and taxane-resistant ovarian cancer a major challenge. FAK overexpression upregulates ALDH and XIAP activity in platinum-resistant and increases CD44, YB1, and MDR-1 activity in taxaneresistant tumors. FAK is therefore now emerging as a prognostically significant candidate in this regard, with mounting evidence from recent successes in preclinical and clinical trials using small molecule FAK inhibitors. This review will summarize the significance and function of FAK in ovarian cancer, and its emerging role in chemotherapeutic resistance. We will discuss the current status of FAK inhibitors in ovarian cancers, their therapeutic competencies and limitations, and further propose that the combination of FAK inhibitors with platinum and taxane-based therapies could be an efficacious approach in chemotherapeutic resistant disease.

scholarly journals Activation modes in biocatalytic radical cyclization reactions

2021 ◽  
Author(s):  
Yuxuan Ye ◽  
Haigen Fu ◽  
Todd K Hyster
Keyword(s):  
Heme Iron ◽  
Radical Cyclization ◽  
Cytochrome P450 Monooxygenases ◽  
Radical Cyclizations ◽  
Cyclization Reactions ◽  
Complex Molecules ◽  
P450 Monooxygenases ◽  
Non Heme Iron ◽  
Essential Reactions ◽  
Isopenicillin N

Abstract Radical cyclizations are essential reactions in the biosynthesis of secondary metabolites and the chemical synthesis of societally valuable molecules. In this review, we highlight the general mechanisms utilized in biocatalytic radical cyclizations. We specifically highlight cytochrome P450 monooxygenases (P450s) involved in the biosynthesis of mycocyclosin and vancomycin, non-heme iron- and α-ketoglutarate-dependent dioxygenases (Fe/αKGDs) used in the biosynthesis of kainic acid, scopolamine, and isopenicillin N, and radical S-adenosylmethionine (SAM) enzymes that facilitate the biosynthesis of oxetanocin A, menaquinone, and F420. Beyond natural mechanisms, we also examine repurposed flavin-dependent ‘ene’-reductases (ERED) for non-natural radical cyclization. Overall, these general mechanisms underscore the opportunity for enzymes to augment and enhance the synthesis of complex molecules using radical mechanisms.

Characterization of cytochrome P450-monooxygenases of Chinese hamsters with respect to aflatoxin B1 activation

Toxicology ◽  
1994 ◽  
Vol 93 (2-3) ◽  
pp. 165-173 ◽  
Author(s):  
Morio Fukuhara ◽  
Eric Antignac ◽  
Naomi Fukusen ◽  
Kazue Kato ◽  
Masanobu Kimura
Keyword(s):  
Cytochrome P450 ◽  
Aflatoxin B1 ◽  
Cytochrome P450 Monooxygenases ◽  
P450 Monooxygenases ◽  
Chinese Hamsters

Prevention and Detection of Fungicide Resistance Development in Rhizoctonia zeae from Soybean and Corn in Nebraska

2021 ◽  
Author(s):  
Nikita Gambhir ◽  
Srikanth Kodati ◽  
Matthew Huff ◽  
Flávio Silva ◽  
Olutoyosi Ajayi-Oyetunde ◽  
...  
Keyword(s):  
Fungicide Resistance ◽  
Resistance Management ◽  
Dry Weight ◽  
Geographic Region ◽  
Population Characteristics ◽  
Current Status ◽  
In Planta ◽  
Resistance Development ◽  
Rhizoctonia Zeae

The goal of this research was to advance the foundational knowledge required to quantify and mitigate fungicide resistance in Rhizoctonia zeae, the seedling disease pathogen of soybean and corn. In vitro sensitivity to azoxystrobin, fludioxonil, sedaxane, and/or prothioconazole was determined for 91 R. zeae isolates obtained mostly from soybean and corn fields in Nebraska. Isolates were sensitive to fludioxonil, sedaxane, and prothioconazole (EC50 < 3 µg/ml) and had a positively skewed EC50 distribution. Isolates were not sensitive to azoxystrobin in vitro (EC50 > 100 µg/ml) or in planta. Application of azoxystrobin did not significantly decrease disease severity or improve total dry weight of the soybean plants (P > 0.05). The risk of resistance development in R. zeae was estimated by characterizing its population structure. Eighty-one R. zeae isolates were genotyped using six microsatellite markers. Results showed that the population has a mixed mode of reproduction and is structured according to geographic region, suggesting limited dispersal. These population characteristics suggest that R. zeae has an intermediate risk of resistance development. Overall, this research established the current status of fungicide sensitivity in R. zeae in Nebraska and estimated its risk of resistance development, which can inform fungicide resistance management for R. zeae.

Current Status of Pyrethroids Resistance in Aedes aegypti (Culicidae: Diptera) in Lahore District, Pakistan: A Novel Mechanistic Insight

2021 ◽  
Author(s):  
Saira Nawaz ◽  
Hafiz Muhammad Tahir ◽  
Muhammad Asif Mahmood ◽  
Muhammad Summer ◽  
Shaukat Ali ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Enzyme Level ◽  
Laboratory Strain ◽  
Current Status ◽  
Glutathione S Transferase ◽  
Development Of Resistance ◽  
Biochemical Assays ◽  
Dengue Transmission ◽  
Lambda Cyhalothrin ◽  
Glutathione S Transferases

Abstract Aedes aegypti (Linnaeus, 1762) is a major vector responsible for dengue transmission. Insecticides are being used as the most effective tool to control vector populations in Lahore, Pakistan. Control of Ae. aegypti is threatened by the development of resistance against insecticides. The current status of insecticide resistance was evaluated against pyrethroids (deltamethrin, cypermethrin, and lambda-cyhalothrin) in different populations of Lahore (Model Town, Mishri Shah, Sadar Cantt, Walton, and Valencia). The susceptibility of the larval and adult populations was tested following the standard WHO guidelines. Moderate to high levels of resistance were found against pyrethroids in the larval (RR50: 3.6–27.2 and RR90: 5–90) and adult populations (percentage mortality &lt; 98%). Biochemical assays revealed a statistically significant increase in the enzyme level in all field populations compared to the laboratory strain. The value of esterase was one-fold higher, monooxygenase was 3.9- to 4.7-fold higher, and glutathione S-transferases was 1.9- to 2.6-fold higher in field populations compared to the laboratory strain. These results depict the presence of resistance against deltamethrin, cypermethrin, and lambda-cyhalothrin in field populations of Lahore mediated by metabolic enzymes i.e. esterases, monooxygenases, and glutathione S-transferase.

scholarly journals Specificity and mechanism of carbohydrate demethylation by cytochrome P450 monooxygenases

2018 ◽  
Vol 475 (23) ◽  
pp. 3875-3886 ◽  
Author(s):  
Craig S. Robb ◽  
Lukas Reisky ◽  
Uwe T. Bornscheuer ◽  
Jan-Hendrik Hehemann
Keyword(s):  
Cytochrome P450 ◽  
Active Site ◽  
Substrate Recognition ◽  
High Energy ◽  
Cytochrome P450 Monooxygenases ◽  
P450 Monooxygenases ◽  
High Energy Barrier ◽  
Molecular Determinants ◽  
Cytochrome P450 Family ◽  
Carbohydrate Ligand

Degradation of carbohydrates by bacteria represents a key step in energy metabolism that can be inhibited by methylated sugars. Removal of methyl groups, which is critical for further processing, poses a biocatalytic challenge because enzymes need to overcome a high energy barrier. Our structural and computational analysis revealed how a member of the cytochrome P450 family evolved to oxidize a carbohydrate ligand. Using structural biology, we ascertained the molecular determinants of substrate specificity and revealed a highly specialized active site complementary to the substrate chemistry. Invariance of the residues involved in substrate recognition across the subfamily suggests that they are critical for enzyme function and when mutated, the enzyme lost substrate recognition. The structure of a carbohydrate-active P450 adds mechanistic insight into monooxygenase action on a methylated monosaccharide and reveals the broad conservation of the active site machinery across the subfamily.

scholarly journals Biotechnological Methods of Sulfoxidation: Yesterday, Today, Tomorrow

Catalysts ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 624 ◽  
Author(s):  
Wanda Mączka ◽  
Katarzyna Wińska ◽  
Małgorzata Grabarczyk
Keyword(s):  
Cytochrome P450 ◽  
Chemical Industry ◽  
Functional Materials ◽  
Cytochrome P450 Monooxygenases ◽  
Whole Cells ◽  
Historical Significance ◽  
P450 Monooxygenases ◽  
Bacteria And Fungi ◽  
Positive Results ◽  
Huge Variety

The production of chiral sulphoxides is an important part of the chemical industry since they have been used not only as pharmaceuticals and pesticides, but also as catalysts or functional materials. The main purpose of this review is to present biotechnological methods for the oxidation of sulfides. The work consists of two parts. In the first part, examples of biosyntransformation of prochiral sulfides using whole cells of bacteria and fungi are discussed. They have more historical significance due to the low predictability of positive results in relation to the workload. In the second part, the main enzymes responsible for sulfoxidation have been characterized such as chloroperoxidase, dioxygenases, cytochrome flavin-dependent monooxygenases, and P450 monooxygenases. Particular emphasis has been placed on the huge variety of cytochrome P450 monooxygenases, and flavin-dependent monooxygenases, which allows for pure sulfoxides enantiomers effectively to be obtained. In the summary, further directions of research on the optimization of enzymatic sulfoxidation are indicated.

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