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Sand flies infect more than 1 million people annually with Leishmania parasites and other bacterial and viral pathogens. Progress in understanding sand fly adaptations to xenobiotics has been hampered by the limited availability of genomic resources. To address this gap, we sequenced, assembled, and annotated the transcriptomes of 11 phlebotomine sand fly species. Subsequently, we leveraged these genomic resources to generate novel evolutionary insights pertaining to their adaptations to xenobiotics, including those contributing to insecticide resistance. Specifically, we annotated over 2,700 sand fly detoxification genes and conducted large-scale phylogenetic comparisons to uncover the evolutionary dynamics of the five major detoxification gene families: cytochrome P450s (CYPs), glutathione-S-transferases (GSTs), UDP-glycosyltransferases (UGTs), carboxyl/cholinesterases (CCEs), and ATP-binding cassette (ABC) transporters. Using this comparative approach, we show that sand flies have evolved diverse CYP and GST gene repertoires, with notable lineage-specific expansions in gene groups evolutionarily related to known xenobiotic metabolizers. Furthermore, we show that sand flies have conserved orthologs of (i) CYP4G genes involved in cuticular hydrocarbon biosynthesis, (ii) ABCB genes involved in xenobiotic toxicity, and (iii) two primary insecticide targets, acetylcholinesterase-1 (Ace1) and voltage gated sodium channel (VGSC). The biological insights and genomic resources produced in this study provide a foundation for generating and testing hypotheses regarding the molecular mechanisms underlying sand fly adaptations to xenobiotics. [ABSTRACT FROM AUTHOR]

Aedes aegypti is vector of many arboviruses including Zika, dengue, yellow fever, West Nile, and Chikungunya. Its control efforts are hampered by widespread insecticide resistance reported in the Americas and Asia, while data from Africa is more limited. Here we use publicly available 729 Ae. aegypti whole-genome sequencing samples from 15 countries, including nine in Africa, to investigate the genetic diversity in four insecticide resistance linked genes: ace-1, GSTe2, rdl and vgsc. Apart from vgsc, the other genes have been less investigated in Ae. aegypti, and almost no genetic diversity information is available. Among the four genes, we identified 1,829 genetic variants including 474 non-synonymous substitutions, some of which have been previously documented, as well as putative copy number variations in GSTe2 and vgsc. Global insecticide resistance phenotypic data demonstrated variable resistance in geographic areas with resistant genotypes. Overall, our work provides the first global catalogue and geographic distribution of known and new amino-acid mutations and duplications that can be used to guide the identification of resistance drivers in Ae. aegypti and thereby support monitoring efforts and strategies for vector control. [ABSTRACT FROM AUTHOR]

The purpose of this research was to determine how common chemical treatments influence Varroa destructor (Anderson and Trueman) population resurgence rates (defined as time posttreatment for mite populations to reach 3 mites/100 adult bees) in managed honey bee (Apis mellifera L.) colonies seasonally. We conducted 2 experiments that followed the same basic protocol to address this purpose. We established 6 treatment groups in Experiment 1 in the fall of 2014: untreated control, Apivar, Apistan, CheckMite+, ApiLifeVar, and Mite Away II applied to 10 colonies per treatment. In Experiment 2, we applied 8 chemical treatments to each of 4 seasonal (spring, summer, fall, and winter) cohorts of honey bee colonies to determine how mite populations are influenced by the treatments. The treatments/formulations tested were Apivar, Apistan, Apiguard, MAQS, CheckMite+, oxalic acid (dribble), oxalic acid (shop towels), and amitraz (shop towels soaked in Bovitraz). In Experiment 1, Apivar and Mite Away II were able to delay V. destructor resurgence for 2 and 6 months, respectively. In Experiment 2, Apiguard, MAQS, oxalic acid (dribble), and Bovitraz treatments were effective at delaying V. destructor resurgence for at least 2 months during winter and spring. Only the Bovitraz and MAQS treatments were effective at controlling V. destructor in the summer and fall. Of the 2 amitraz-based treatments, the off-label Bovitraz treatment was the only treatment to reduce V. destructor populations in every season. The data gathered through this study allow for the refinement of treatment recommendations for V. destructor , especially regarding the seasonal efficacy of each miticide and the temporal efficacy posttreatment. [ABSTRACT FROM AUTHOR]

Background: Viloxazine ER (viloxazine extended-release capsules; Qelbree®), a nonstimulant attention-deficit/hyperactivity disorder (ADHD) treatment, has known activity as a norepinephrine (NE) transporter (NET) inhibitor. In vitro studies have also shown direct pharmacological effects on specific serotonin (5-HT) receptors, but not on the serotonin transporter (SERT). An in vivo microdialysis study in rats showed viloxazine (50 mg/kg i.p.) increased extracellular 5-HT, NE, and dopamine (DA) in the prefrontal cortex (PFC), a key brain region in ADHD pathology. This study evaluated whether these effects occur at clinically relevant concentrations. Methods: Microdialysis experiments were conducted in freely-moving, Sprague-Dawley rats (males, 8 weeks). Viloxazine (1, 3, 10, 30 mg/kg) was administered intraperitoneally to establish the dose range in rats at which viloxazine plasma concentrations aligned with those of individuals with ADHD administered therapeutic doses of viloxazine ER. Concentrations of unbound viloxazine, NE, 5-HT, DA, and NE and 5-HT metabolites (3,5-dihydroxyphenylglycol [DHPG] and 5-hydroxyindoleacetic acid [5-HIAA]) were measured in PFC interstitial fluid. After identifying a therapeutically relevant dose (30 mg/kg), the experiment was repeated using 30 and 50 mg/kg viloxazine (as 50 mg/kg increased NE, 5-HT, and DA in prior studies). Results: Viloxazine unbound (free drug) plasma concentrations in rats at 30 mg/kg were comparable to free drug concentrations in individuals with ADHD taking clinically effective doses (based on validated population PK models). Viloxazine 30 mg/kg significantly increased extracellular NE, 5-HT, and DA PFC levels compared to vehicle. Concomitant decreases in DHPG, but not 5-HIAA, support the inhibitory effect of viloxazine on NET but not SERT. Conclusion: At clinically relevant concentrations, viloxazine increases PFC NE, DA, and 5-HT. Prefrontal augmentation of 5-HT does not appear to result from 5-HT reuptake inhibition but may be related to activation of 5-HT neurons. The potential therapeutic role of serotonergic effects in ADHD treatment merits further exploration. Plain Language Summary: Viloxazine ER (Qelbree®) is a non-stimulant, FDA-approved treatment for ADHD in children and adults. Viloxazine and other ADHD medications are thought to work by increasing two signaling molecules, called norepinephrine and dopamine, in a brain area called the prefrontal cortex. The prefrontal cortex is important in ADHD as it helps control impulsive behavior, attention, hyperactivity, and learning. A third signaling molecule called serotonin may also be important for ADHD. Previous experiments in rats have shown that viloxazine increases norepinephrine, dopamine, and serotonin in the prefrontal cortex. To better understand how viloxazine increases serotonin and if the increase occurs at the same doses used to treat ADHD, we did another microdialysis study in rats. Our study showed that viloxazine increases norepinephrine, dopamine, and serotonin in the prefrontal cortex at doses used to treat ADHD in humans. We showed that viloxazine increases norepinephrine and dopamine levels in the neuron where these signaling molecules work by blocking the way that they are recycled back into the nerve space. However, viloxazine does not block the serotonin recycling mechanism, meaning viloxazine works differently than selective serotonin reuptake inhibitor (SSRI) medications (often used in depression). Additional studies are needed to determine exactly how viloxazine increases serotonin in the brain and whether this increase plays a role in treating ADHD. These additional studies will also help us understand how viloxazine acts differently than other ADHD medications. [ABSTRACT FROM AUTHOR]

2-C-methyl-d-erythritol-phosphate cytidylyltransferase (MCT) is a key enzyme in the MEP pathway of monoterpene synthesis, catalyzing the generation of 4- (5′-pyrophosphate cytidine)-2-C-methyl-d-erythritol from 2-C-methyl-d-erythritol-4-phosphate. We used homologous cloning strategy to clone gene, LiMCT, in the MEP pathway that may be involved in the regulation of floral fragrance synthesis in the Lilium oriental hybrid 'Sorbonne.' The full-length ORF sequence was 837 bp, encoding 278 amino acids. Bioinformatics analysis showed that the relative molecular weight of LiMCT protein is 68.56 kD and the isoelectric point (pI) is 5.12. The expression pattern of LiMCT gene was found to be consistent with the accumulation sites and emission patterns of floral fragrance monoterpenes in transcriptome data (unpublished). Subcellular localization indicated that the LiMCT protein is located in chloroplasts, which is consistent with the location of MEP pathway genes functioning in plastids to produce isoprene precursors. Overexpression of LiMCT in Arabidopsis thaliana affected the expression levels of MEP and MVA pathway genes, suggesting that overexpression of the LiMCT in A. thaliana affected the metabolic flow of C5 precursors of two different terpene synthesis pathways. The expression of the monoterpene synthase AtTPS14 was elevated nearly fourfold in transgenic A. thaliana compared with the control, and the levels of carotenoids and chlorophylls, the end products of the MEP pathway, were significantly increased in the leaves at full bloom, indicating that LiMCT plays an important role in regulating monoterpene synthesis and in the synthesis of other isoprene-like precursors in transgenic A. thaliana flowers. However, the specific mechanism of LiMCT in promoting the accumulation of isoprene products of the MEP pathway and the biosynthesis of floral monoterpene volatile components needs further investigation. [ABSTRACT FROM AUTHOR]

The acetylcholinesterase (AChE) is involved in termination of synaptic transmission at cholinergic synapses and plays a vital role in the insecticide detection and inhibitor screening. Here, we report the heterologous expression of an AChE from Tetronarce californica (TcA) in Escherichia coli (E. coli) as a soluble active protein. TcA was immobilized in calcium alginate beads; the morphology, biochemical properties, and insecticide detection performance of free and immobilized TcA were characterized. Moreover, we used sequence, structure-based approaches, and molecular docking to investigate structural and functional characterization of TcA. The results showed that TcA exhibited a specific activity of 102 U/mg, with optimal activity at pH 8.0 and 30 °C. Immobilized TcA demonstrated superior thermal stability, pH stability, and storage stability compared to the free enzyme. The highest sensitivity of free TcA was observed with trichlorfon, whereas immobilized TcA showed reduced IC50 values towards tested insecticides by 3 to 180-fold. Molecular docking analysis revealed the interaction of trichlorfon, acephate, isoprocarb, λ-cyhalothrin, and fenpropathrin in the active site gorge of TcA, particularly mediated through the formation of hydrogen bonds and π-π stacking. Therefore, TcA expressed heterologously in E. coli is a promising candidate for applications in food safety and environmental analysis. Key points: • T. californica AChE was expressed solubly in prokaryotic system. • The biochemical properties of free/immobilized enzyme were characterized. • The sensitivity of enzyme to insecticides was evaluated in vitro and in silico. [ABSTRACT FROM AUTHOR]

A significant amount of researcher and practitioner effort has focused on developing new chemical controls for the parasitic Varroa destructor mite in beekeeping. One outcome of that has been the development and testing of "glycerol–oxalic acid" mixtures to place in colonies for extended periods of time, an off-label use of the otherwise legal miticide oxalic acid. The majority of circulated work on this approach was led by practitioners and published in nonacademic journals, highlighting a lack of effective partnership between practitioners and scientists and a possible failure of the extension mandate in beekeeping in the United States. Here, we summarize the practitioner-led studies we could locate and partner with a commercial beekeeper in the Southeast of the United States to test the "shop towel–oxalic acid–glycerol" delivery system developed by those practitioners. Our study, using 129 commercial colonies between honey flows in 2017 split into 4 treatment groups, showed no effectiveness in reducing Varroa parasitism in colonies exposed to oxalic acid–glycerol shop towels. We highlight the discrepancy between our results and those circulated by practitioners, at least for the Southeast, and the failure of extension to support practitioners engaged in research. [ABSTRACT FROM AUTHOR]

Isoprenoid precursor synthesis is an ancient and fundamental function of plastid organelles and a critical metabolic activity of the apicoplast in Plasmodium malaria parasites [1–3]. Over the past decade, our understanding of apicoplast properties and functions has increased enormously [4], due in large part to our ability to rescue blood-stage parasites from apicoplast-specific dysfunctions by supplementing cultures with isopentenyl pyrophosphate (IPP), a key output of this organelle [5,6]. In this Pearl, we explore the interdependence between isoprenoid metabolism and apicoplast biogenesis in P. falciparum and highlight critical future questions to answer. [ABSTRACT FROM AUTHOR]

Click reactions on poly[(methyl acrylate)‐co‐(5‐azido‐1‐pentene)], synthesized by radical polymerization of methyl acrylate and 1‐bromo‐5‐pentene, and converted into the click‐ready azido form by nucleophilic substitution with sodium azide, were studied. Propargyl benzoate and propargyl acetate were clicked onto the polymeric substrate, with the latter known to be a poor click reactant. The impact of solvents (dimethyl formamide (DMF) and tetrahydrofuran (THF)), catalytic systems (CuSO4/Na ascorbate, [Cu(BPMEN)(ClO4)2]/Na ascorbate, bromotris(triphenylphosphine) copper(I) ([CuBr(PPh3)3])) and the addition of chelating nitrogenous bases (triethylamine (TEA), diisopropylethylamine, N,N,N′,N″,N″‐pentamethyldiethylenetriamine) on the degree of conversion was analyzed. Only reactions catalyzed with [CuBr(PPh3)3] led to high or complete conversions in both solvents. Reactions catalyzed with the pre‐catalyst complexes CuSO4⋅5H2O and [(CuBPMEN)(ClO4)2], which require the in situ reduction of Cu(II) to Cu(I) by sodium ascorbate, yielded incomplete conversions in both solvents. Adding chelating nitrogenous bases, with TEA being the most effective, yielded complete conversions for propargyl benzoate with all three catalytic systems in DMF. Adding TEA to reactions of propargyl acetate in DMF increased conversion by 17.9% for CuSO4⋅5H2O/Na ascorbate and 29.6% for [(CuBPMEN)(ClO4)2]/Na ascorbate. The addition of chelating bases was more effective in DMF than in THF, which was also the less suited solvent in reactions without chelating bases. The results show that click reactions with propargyl reagents that cannot increase the nucleophilicity of the vinylidene‐like β‐carbon through electron conjugation yield lower conversions. The effectiveness of catalytic systems that undergo in situ reductions can be enhanced by nitrogenous chelating bases that stabilize the Cu(I) stage. © 2023 Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

Halyomorpha halys (Stål) (Heteroptera: Pentatomidae) has brought about agricultural harm throughout the Eastern Black Sea coastline since 2017. It continues to come to a threat because there are no adequate studies on managing this pest. One of the major rein strategies of insecticides is acetylcholinesterase (ACHE) inhibition. Therefore, this study aims to investigate an alternative way to struggle H. halys by inhibiting ACHE. The ACHE was purified from H. halys using edrophonium-Sepharose 6B affinity chromatography and characterized by examining some kinetic properties. The molecular weight of the purified enzyme was determined by Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis and natural polyacrylamide gel electrophoresis. In addition, the inhibitory effects of tacrine and edrophonium chloride, and water extracts of olive leaf, walnut leaf and alder leaf on this ACHE were investigated. The acetylcholinesterase was purified 403-fold with an 83.3% yield. H. halys ACHE was found to have six subunits and a molecular weight of approximately 350 kDa. The ACHE's Km, Vmax, and kcat values were assigned to be 0.02 ± 0.006 mM, 3,333.3 ± 481 EU.mg protein− 1, and 1070.2 ± 184 min− 1, respectively. All inhibitors highly inhibited of activity of h.halys ACHE. Especially, the fact that the water extracts of these plants are effective in ACHE inhibition is significant due to being environmentally amicable pesticides that may be benefited in the struggle with the pest. [ABSTRACT FROM AUTHOR]

Protein oligomerization occurs frequently both in vitro and in vivo, with specific functionalities associated with different oligomeric states. The YqiC protein from Salmonella Typhimurium forms a homotrimer through its C‐terminal coiled‐coil domain, and the protein is closely linked to the colonization and invasion of the bacteria to the host cells. To elucidate the importance of the oligomeric state of YqiC in vivo and its relation with bacterial infection, we mutated crucial residues in YqiC's coiled‐coil region and confirmed the loss of trimer formation using chemical crosslinking and size exclusion chromatography coupled with multiple angle light scattering (SEC‐MALS) techniques. The yqiC‐knockout strain complemented with mutant YqiC showed significantly reduced colonization and invasion of Salmonella to host cells, demonstrating the critical role of YqiC oligomerization in bacterial pathogenesis. Furthermore, we conducted a protein–protein interaction study of YqiC using a pulled‐down assay coupled with mass spectrometry analysis to investigate the protein's role in bacterial virulence. The results reveal that YqiC interacts with subunits of Complex II of the electron transport chain (SdhA and SdhB) and the β‐subunit of F0F1‐ATP synthase. These interactions suggest that YqiC may modulate the energy production of Salmonella and subsequently affect the assembly of crucial virulence factors, such as flagella. Overall, our findings provide new insights into the molecular mechanisms of YqiC's role in S. Typhimurium pathogenesis and suggest potential therapeutic targets for bacterial infections. [ABSTRACT FROM AUTHOR]

Lysobacter capsici X2-3, a plant growth-promoting rhizobacteria (PGPR), was isolated from wheat rhizosphere and has inhibitory effects against a wide range of pathogens. One important characteristic of L. capsici is its ability to produce diverse antibiotics and lytic enzymes. The GntR family of transcription factors is a common transcription factor superfamily in bacteria that has fundamental roles in bacterial metabolism regulation. However, the GntR family transcription factor in Lysobacter has not been identified. In this study, to obtain an understanding of the GntR/HutC gene function in L. capsici X2-3, a random Tn5-insertion mutant library of X2-3 was constructed to select genes showing pleiotropic effects on phenotype. We identified a Tn5 mutant with an insertion in LC4356 that showed reduced biofilm levels, and sequence analysis indicated that the inserted gene encodes a GntR/HutC family transcription regulator. Furthermore, the LC4356 mutant showed reduced extracellular polysaccharide (EPS) production, diminished twitching motility and decreased survival under UV radiation and high-temperature. The RT‒qPCR results indicated that the pentose phosphate pathway-related genes G6PDH, 6PGL and PGDH were upregulated in the LC4356 mutant. Thus, since L. capsici is an efficient biocontrol agent for crop protection, our findings provide fundamental insights into GntR/HutC and will be worthwhile to improve PGPR biocontrol efficacy. [ABSTRACT FROM AUTHOR]

The leaf-cutting ant Atta sexdens stands out as a pest of several crops of economic importance. The main control method for this species is the application of ant baits. However, one of the most used active ingredients in the ant baits, sulfluramid, was classified as an organic pollutant, highlighting the urgent need to seek new active ingredients with greater ecological and environmental safety. The present goal is to evaluate the bioactivity of botanical extracts in workers of the leaf-cutting ant A. sexdens by ingestion, aiming to select extracts with essential characteristics for use in toxic baits for the subsequent isolation of substances and prospection of insecticides. Insect survival in the first evaluation (24 h) was high in all treatments with extracts. Survival time varied between treatments, with mortality reaching maximum values between 10 and 20 days for most of the treatments. At 21 days, live ants were observed only in treatments T3 (M. maracasana-stem) and T4 (C. mastigophorus-bark), with survival of 10% and 3.3%, respectively, not significantly differing between them. The extracts of Metrodorea maracasana, Conchocarpus mastigophorus, Erythoxylum macrocalyx, and Erythoxylum plowmanii showed insecticidal activity against A. sexdens workers. The insecticidal activity of the species Erythoxylum macrocalyx, E. plowmanii, Metrodorea maracasana, and Conchocarpus mastigophorus against A. sexdens workers is shown for the first time. The studied extracts have potential for the fractionation and selection of substances responsible for insecticidal activity, allowing for the prospection of toxic baits. [ABSTRACT FROM AUTHOR]

The potential for essential oils (EOs) to act as a natural alternative for controlling mosquito populations has aroused extensive interest in recent years. Four EOs (Thymus vulgaris (thyme), Foeniculum vulgare (fennel), Citrus medica (lime), and Camellia sinensis (green tea)) were selected in our previous larvicidal screening assays against Aedes albopictus. In this study, the active constituents of each EO were identified. Next, their acetylcholinesterase (AChE) inhibitory activity was evaluated, and the binding mode was studied by molecular docking. To improve EO stability and duration of activity, nanoemulsions were prepared and characterized. Thirteen constituents of the four EOs at the 100 ppm level led to 100% mortality of the larvae, the four most active constituents being α-hexyl cinnamaldehyde (LC50 = 24.0 ± 0.3 ppm), limonene (LC50 = 34.1 ± 0.7 ppm), α-terpinene (LC50 = 50.0 ± 0.5 ppm), and carvacrol (LC50 = 54.7 ± 0.6 ppm). These compounds, with the exception of α-hexyl cinnamaldehyde, also showed potent AChE inhibitory activity. Nanoemulsions with droplet size of 56.8–224.9 nm were prepared by emulsification at a 1:1 (v/v) ratio of EO and Tween 80. These EO nanoemulsions showed equally potent larvicidal activity as EOs themselves; moreover, they showed better stability and were active for longer time. These results suggest that natural EOs and their constituents have potential as larvicides for mosquito vector control and that nanoemulsification is an effective method for improving their physicochemical properties and efficacy. [ABSTRACT FROM AUTHOR]

In Xinjiang's cotton growing area of China, previous studies have shown that matrine is a selective botanical insecticide, with high toxicity to Aphis gossypii Glover (Hemiptera: Aphididae) and low toxicity to its dominant natural enemy, Hippodamia variegata Goeze (Coleoptera: Coccinellidae). However, lethal effects alone are not sufficient evidence to justify introducing matrine into local IPM strategies. In this context, we systematically evaluated the safety of matrine to H. variegata by investigating the effects of contact and stomach toxicity of matrine on the lady beetle's life-table parameters, predatory ability, flight ability of parental adults, and cross-generational effects on life-table parameters of the predator's offspring. We found that matrine at 2,000 mg/l did not have any significant negative effects to adult fecundity, longevity, or the predatory capacity of parental adults of H. variegata. Moreover, it is the same for cross-generational effects of matrine on H. variegate. The contact toxicity of matrine significantly reduced the flight time of H. variegata males, but did not significantly affect flight time and average velocity. Our results support the view that matrine is safe to H. variegata and can be recommended for use in the local IPM strategy for control of A. gossipii. [ABSTRACT FROM AUTHOR]

Background: Voltage‐gated potassium channel Kv2 is the primarily delayed rectifier in insect nerves and muscles involved in several crucial biological processes, including action potential regulation, photoreceptor performance, and larval locomotor. It is a potential molecular target for developing a novel pesticide for mosquitos. However, there are few studies on the Kv2 channel in agricultural pests. Results: The only α‐subunit gene of the Kv2 channel in Plutella xylostella (L.), PxShab, was cloned, and its expression profile was analyzed. The relative expression level of PxShab was highest in the pupal stage of both sexes and male adults but lowest in female adults. Meanwhile, PxShab had the highest expression in the head in both larvae and adults. Then, PxShab was stably expressed in the HEK‐293 T cell line. Whole cell patch clamp recordings showed an outward current whose current–voltage relationship conformed to a typical delayed‐rectifier potassium channel. 20 μM quinidine could effectively inhibit the potassium current, while the channel was insensitive to 4‐AP even at 10 mM. Several potential compounds and botanical pesticides were assessed, and carvedilol (IC50 = 0.53 μM) and veratrine (IC50 = 2.22 μM) had a good inhibitory effect on the channel. Conclusion: This study revealed the pharmacological properties of PxShab and screened out several high potency inhibitors, which laid the foundation for further functional research of PxShab and provides new insight into designing novel insecticides. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The silverleaf whitefly Bemisia tabaci (Gennadius, 1889) (Homoptera: Aleyrodidae) is a serious invasive herbivorous insect pest worldwide. The excessive use of pesticides has progressively selected B. tabaci specimens, reducing the effectiveness of the treatments, and ultimately ending in the selection of pesticide-resistant strains. The management of this crop pest has thus become challenging owing to the level of resistance to all major classes of recommended insecticides. Here, we used in silico techniques for detecting sequence polymorphisms in ace1 gene from naturally occurring B. tabaci variants, and monitor the presence and frequency of the detected putative mutations from 30 populations of the silverleaf whitefly from Egypt and Pakistan. We found several point mutations in ace1-type acetylcholinesterase (ace1) in the studied B. tabaci variants naturally occurring in the field. By comparing ace1 sequence data from an organophosphate-susceptible and an organophosphate-resistant strains of B. tabaci to ace1 sequence data retrieved from GenBank for that species and to nucleotide polymorphisms from other arthropods, we identified novel mutations that could potentially influence insecticide resistance. Homology modeling and molecular docking analyses were performed to determine if the mutation-induced changes in form 1 acetylcholinesterase (AChE1) structure could confer resistance to carbamate and organophosphate insecticides. Mutations had small effects on binding energy (ΔGb) interactions between mutant AChE1 and insecticides; they altered the conformation of the peripheral anionic site of AChE1, and modified the enzyme surface, and these changes have potential effects on the target-site sensitivity. Altogether, the results from this study provide information on genic variants of B. tabaci ace1 for future monitoring insecticide resistance development and report a potential case of environmentally driven gene variations. [ABSTRACT FROM AUTHOR]

Mosquitoes (Diptera: Culicidae) are insect vectors of epidemiologically important arboviruses owing to their behavior, physiology, morphology, and proximity to humans, which require incisive strategies to contain their spread. The failure of current arbovirus management plans and lack of fully effective treatments suggest that vector control by botanical insecticides could be an effective and safe strategy. Botanical insecticides are obtained from renewable sources and have complex chemical compositions, different modes of action, and selective toxicity for target organisms. In this review, we present the main control strategies for insects belonging to the genera Aedes, Culex, and Anopheles and discuss the possibility of using botanical insecticides in the integrated management of vectors. Numerous botanical insecticide formulations are presented, and their potential modes of action during the immature stages include damage to the egg exocorionic network and abnormal disruption of embryos, which result from deficiencies in egg chitinization, impairment of larval morphology, and inhibition or differential expression of enzymes, promoting changes in the digestive tract epithelium and reduced larval mobility, and impairment of external surfaces or the respiratory system of pupae, altering pupal swimming patterns. In adult insects, botanical insecticides can promote incomplete ecdysis, in addition to dysfunction of olfactory receptors, food traffic, and reproductive function. Thus, broad-spectrum botanical insecticides can be used to control the different stages of insect development. The contributions of nanotechnology to vector control should be further explored to enhance the insecticidal activity and stability of botanical insecticides under different conditions. [ABSTRACT FROM AUTHOR]

Environmental pollution is a global concern, and anthropogenic activities have contaminated natural water sources. Pesticides are one of the most recognised pollutants worldwide. Carbamates are a widely used pesticide family, and bendiocarb is a broad-spectrum carbamate insecticide detected in surface and groundwater. In the present work, acute lethal and chronic effects of bendiocarb on the early life stages of freshwater snail Lymnaea stagnalis were investigated. 24-h LC50 of bendiocarb on L. stagnalis embryos and juveniles was estimated at 20.39 (18.30–22.71) mg/L and 38.35 (29.58–52.89) mg/L, respectively. Chronic tests were conducted for 21-d to evaluate the potential effects of the environmentally realistic concentrations of bendiocarb (5 and 100 µg/L) on the embryos. Mortality, development, growth (embryo: egg ratio and shell height), heart rate, and hatching success were investigated. The test results showed that mortality, developmental progression, embryo: egg ratio, shell height measurements and cumulative hatching rate were not significantly impaired by chronic bendiocarb exposure compared to the control. However, bendiocarb induced increased heart rate in the exposed snails. [ABSTRACT FROM AUTHOR]

Current studies on Anopheles anticholinesterase insecticides are focusing on identifying agents with high selectivity towards Anopheles over mammalian targets. Acetylcholinesterase (AChE) from electric eel is often used as the bioequivalent enzyme to study ligands designed for activity and inhibition in human. In this study, previously identified derivatives of a potent AChE, donepezil, that have exhibited low activity on electric eel AChE were assessed for potential AChE-based larvicidal effects on four African malaria vectors; An. funestus, An. arabiensis, An. gambiae and An. coluzzii. This led to the identification of four larvicidal agents with a lead molecule, 1-benzyl-N-(thiazol-2-yl) piperidine-4-carboxamide 2 showing selectivity for An. arabiensis as a larvicidal AChE agent. Differential activities of this molecule on An. arabiensis and electric eel AChE targets were studied through molecular modelling. Homology modelling was used to generate a three-dimensional structure of the An. arabiensis AChE for this binding assay. The conformation of this molecule and corresponding interactions with the AChE catalytic site was markedly different between the two targets. Assessment of the differences between the AChE binding sites from electric eel, human and Anopheles revealed that the electric eel and human AChE proteins were very similar. In contrast, Anopheles AChE had a smaller cysteine residue in place of bulky phenylalanine group at the entrance to the catalytic site, and a smaller aspartic acid residue at the base of the active site gorge, in place of the bulky tyrosine residues. Results from this study suggest that this difference affects the ligand orientation and corresponding interactions at the catalytic site. The lead molecule 2 also formed more favourable interactions with An. arabiensis AChE model than other Anopheles AChE targets, possibly explaining the observed selectivity among other assessed Anopheles species. This study suggests that 1-benzyl-N-(thiazol-2-yl) piperidine-4-carboxamide 2 may be a lead compound for designing novel insecticides against Anopheles vectors with reduced toxic potential on humans. [ABSTRACT FROM AUTHOR]

Aphelenchoides besseyi could cause great yield losses of rice and many economically important crops. Acetylcholinesterase (AChE) inhibitors were commonly used to manage plant-parasitic nematodes. However, nematodes resistant to AChE inhibitors have been increasingly reported due to the extensive use of these chemicals. The current study was aimed to establish the correlation between fenamiphos (an AChE-inhibitor) sensitivities and acetylcholinesterase genes (ace) by analyzing two isolates of A. besseyi (designated Rl and HSF), which displayed differential sensitivities to fenamiphos. The concentrations of fenamiphos that led to the death of 50% (LD50) of Rl and HSF were 572.2 ppm and 129.4 ppm, respectively. Three ace genes were cloned from A. besseyi and sequenced. Sequence searching and phylogenic analyses revealed that AChEs of R1 and HSF shared strong similarities with those of various vertebrate and invertebrate species. Molecular docking analysis indicated that AChEs-HSF had much higher affinities to fenamiphos than AChEs-R1. Quantitative reverse transcriptase-PCR analyses revealed that expression of three ace genes were downregulated in HSF but were upregulated in Rl after exposure to 100 ppm fenamiphos for 12 h. The results indicated that the expression of the ace genes was modulated in response to fenamiphos in different nematode strains. An increased expression of the ace genes might contribute to fenamiphos-insensitivity as seen in the Rl isolate. [ABSTRACT FROM AUTHOR]

In this research, a series of N‐phenylsulfonamide derivatives (1‐12) were designed, synthesized, and investigated for their inhibitory potencies against carbonic anhydrase isoenzymes I, II, and IX (hCA I, hCA II, and hCA IX) and cholinesterases (ChE), namely, acetylcholinesterase and butyrylcholinesterase. These compounds, whose inhibition potentials were evaluated for the first time, were characterized by spectroscopic techniques (1H‐ and 13C‐NMR and FT‐IR). CA isoenzyme inhibitors are significant therapeutic targets, especially owing to their preventive/activation potential in the therapy processes of some diseases such as cancer, osteoporosis, and glaucoma. On the other hand, Cholinesterase inhibitors are valuable molecules with biological importance that can be employed in the therapy process of Alzheimer's patients. The results showed that the tested molecules had enzyme inhibition activities ranging from 9.7 to 93.7 nM against these five metabolic enzymes. Among the tested molecules, the methoxy and the hydroxyl group‐containing compounds 10, 11, and 12 exhibited more enzyme inhibition activities when compared to standard compounds acetazolamide, sulfapyridine, and sulfadiazine for CA isoenzymes and neostigmine for ChE, respectively. Of these three molecules, compound 12, which had a hydroxyl group in the para position in the aromatic ring, was determined to be the most active molecule against all enzymes. In silico work, molecular docking has also shown similar results and is consistent with the experimental data in the study. As a result, we can say that some of the tested molecules might be used as promising inhibitor candidates for further studies on this topic. [ABSTRACT FROM AUTHOR]

In this paper, molecular dynamics, full factorial experimental design and molecular docking were used to determine the toxic effects of pesticides on pests (Tetranychus telarius, Lygus lucorum and Helicoverpa armigera) and bees (North Chinese bee) in a cotton field, and an insecticide collocation scheme with the bi-directional selectivity was devised. Firstly, the main insecticides for three stages of cotton growth were identified under the lateral mixing condition. Insecticides for the first phase included abamectin (avermectin B1a and B1b), acetamiprid (N-(N-cyano-ethylimine)-N-methyl-2-chloropyridine-5-methylamine), dicofol (1,1-bis(p-Chlorophenyl)-2,2,2-trichloroethanol) and cypermethrin ((RS)-α-cyano-3-phenoxyebenzyl(SR)-3-(2,2-dichloroyl)-2,2-dimethyl cyclopropane carboxylic acid ester); the insecticides available in the second phase included cypermethrin ((RS)-α-cyano-3-phenoxyebenzyl(SR)-3-(2,2-dichloroyl)-2,2-dimethyl cyclopropane carboxylic acid ester), phoxim (O,O-diethyl-O-α-cyanophenylbenzylamine thiophosphate ester), deltamethrin ((R,cis)-2,2-dimethyl-3-(2,2-dibromovinylcyclopropane ester)-cyano-diphenyl ether) and abamectin (avermectin B1a and B1b). In third phase, cypermethrin ((RS)-α-cyano-3-phenoxyebenzyl(SR)-3-(2,2-dichloroyl)-2,2-dimethyl cyclopropane carboxylic acid ester), and deltamethrin ((R,cis)-2,2-dimethyl-3-(2,2-dibromovinylcyclopropane ester) -cyano-diphenyl ether) were included. Different insecticide application schemes were designed according to whether the application cycle and sequence were considered. The molecular dynamics simulation method was used to determine the effects of different insecticide application schemes on pests and bees. After the simulation, the simplified mixed-weighted model carried out each application scheme. In the case of lateral mixing, the combination of avermectin + acetamiprid + trichlorobacitol + cypermethrin + phoxim + deltamethrin was selected as the optimal application program, which reduced bee toxicity by 98.77% and increased insect toxicity by 55.84%. Whereas in the case of longitudinal residue, avermectin + cypermethrin + deltamethrin was selected. This combination reduced the harm to bees by 126.55% and increased the toxicity to target pests by 34.23%. Finally, by calculating the resultant force from different types of non-bonded forces, the mechanism of the effect of the optimal application scheme on bees and pests under two scenarios was analyzed. The optimally combined scheme prepared by screening could provide the bi-directional selectivity to bees and pests. This study provides an important reference for reducing the environmental problems caused by pesticide application in farmland. [ABSTRACT FROM AUTHOR]

Ricania simulans (Walker, 1851) (Hemiptera: Ricaniidae) has been causing damage in agricultural areas along the eastern Black Sea coastline since 2006. As there are not enough studies on managing this pest, it continues to pose a threat. One of the significant control tactics of insecticides includes the inhibition of acetylcholinesterase. Therefore the present study is aimed to study an alternative way to combat R. simulans through inhibition of acetylcholinesterase (ACHE). The ACHE was purified from adults and nymphs of R. simulans one by one using one-step edrophonium-Sepharose 6B affinity chromatography, and some kinetic properties were studied. The ACHEs were purified 251.6-fold with a yield of 34.2% for adults and 65.5-fold with a yield of 2.2% for nymphs. The Km, Vmax, and kcat values of R. simulans ACHE for acetylthiocholine iodide (ATC) hydrolysis were determined to be 0.04 ± 0.01 mM, 2,000.0 ± 250 EU/mg protein and 104.5 ± 13 min−1 for adults and 0.02 ± 0.01 mM, 500.0 ± 52 EU/mg protein and 30.3 ± 6.4 min−1 for nymphs, respectively. In inhibition studies of R. simulans ACHEs with edrophonium chloride, tacrine and olive leaf extract with water, the IC50 values of the inhibitors were calculated. Although all inhibitors inhibited the ACHEs, they inhibited the nymphs' ACHEs more effectively. In particular, the fact that the olive leaf water extract is effective in the ACHEs inhibition of these two stages is important for it to be an environmentally friendly pesticide that can be used in the fight against this pest. [ABSTRACT FROM AUTHOR]

Bemisia tabaci Gennadius (Homoptera: Aleyrodidae) is a sporadic pest of cotton and several other agricultural crops. The expansion of insecticide resistance has compelled the assessment of chemically novel insecticides. Therefore, the lethal effects of systemic insecticides, flonicamid 50 WG (pyridincarboxamide) and spirotetramat 240 SC (ketoenole) were assessed against different life stages (egg, nymph, pupae and adult) of B. tabaci in the laboratory. The sublethal effects of these insecticides in relation to life table parameters of B. tabaci were also investigated. Spirotetramat was most effective against all nymphal instars and pupae but was relatively less toxic against adult stage of B. tabaci compared to flonicamid. Whereas, flonicamid was highly effective against adult, less effective against nymph and least effective against pupae in comparison to the efficacy of spirotetramat. Flonicamid and spirotetramat possessed weak ovicidal potential at all different tested concentrations. LC50 values (72.96, 76.14 and 85.51 ppm) revealed two-fold toxicity of spirotetramat as compared to LC50 values (123.40, 133.43 and 178.56 ppm) of flonicamid against 1st, 2nd and 3rd instar-nymph, respectively. Flonicamid was 54 folds more toxic against B. tabaci adults with LC50 value of 3.99 ppm than that of spirotetramat (218.36 ppm). With sublethal concentration of flonicamid and spirotetramat, the intrinsic rate of increase of population per day (r = 0.080 and 0.093, respectively) and estimated finite rate of increase in population (λ = 1.083 and 1.097, respectively) were considerably decreased than control (r = 0.157 and λ = 1.170). However, the values of life table parameters (r and λ) were significantly smaller after exposure of flonicamid than spirotetramat. The net reproductive rate (R0= offspring/ female) and mean generation time (T = days) of female B. tabaci were significantly reduced (7.085 and 21.03, respectively) with spirotetramat than those of flonicamid (40.88 and 46.11, respectively). Flonicamid extended the developmental duration of immature stages and the emergence of female and male (sxj: 34 and 39 days, respectively) compared to Spirotetramat. Spirotetramat significantly decreased the rate of age stage survival (lx), age-stage specific fecundity (fxj), age-specific fecundity (mx) and age-specific maternity (lxmx) compared to flonicamid and control treatment. The male and female treated with spirotetramat survived (life expectancy: exj) longer (47 and 37 days, respectively) than flonicamid (26 and 12 days, respectively). The least vxj reproductive curve for females was observed with spirotetramat (11.83) at 16th day compared with control (24.46) at 16th day and the highest with flonicamid (66.50) at 35th day of age. This study is the first stride towards establishing a scientific base for the efficient use of tested insecticides for pest control. [ABSTRACT FROM AUTHOR]

Pinene (C10H16) is a bicyclic terpene present in various plant essential oils mainly in coniferous and eucalyptus species. In the present study, biological activities of two isomers of pinene (α- pinene and β- pinene) against Aedes aegypti Linn. were assessed. The results revealed β- pinene as more effective against egg and larval stages with LC50 value of 21.02 ppm and 108.39 ppm respectively at 72-h exposure period than α-pinene while against adult stage of the insect α- pinene (LC50 value 73.30 ppm) was more effective than β- pinene (LC50 value 111.18 ppm). To understand the effects of the selected pinene on different resistant development associated enzymes namely cytP450 monooxygenase, esterases, glutathione- S- transferase (GST) and acetylcholine esterase (AchE), their activities were analyzed after treating with LC50 dose for 24 h in larval and adult stages of Aedes aegypti. Results revealed that in both stages, in response to pinene, the activity of cytP450 was markedly enhanced but the activities of GST, α- and β-esterases and acetylcholine esterase enzyme were decreased in both target stages in comparison to control. Therefore, compounds like pinene gain more importance to be further used in Aedes control programme to prevent the spread of Aedes borne diseases like dengue. [ABSTRACT FROM AUTHOR]

Recently, photoclick chemistry emerged as a powerful tool employed in several research fields, from medicinal chemistry and biology to material sciences. The growing interest in this type of chemical process is justified by the possibility to produce complex molecular systems using mild reaction conditions. However, the elevated spatio-temporal control offered by photoclick chemistry is highly intriguing, as it expands the range of applications. In this context, the light-triggered reaction of 2,5-diaryl tetrazoles with dipolarophiles emerged for its interesting features: excellent stability of the substrates, fast reaction kinetic, and the formation of a highly fluorescent product, fundamental for sensing applications. In the last years, 2,5-diaryl tetrazoles have been extensively employed, especially for bioorthogonal ligations, to label biomolecules and nucleic acids. In this review, we summarized recent applications of this interesting photoclick reaction, with a particular focus on biological fields. Moreover, we described the main limits that affect this system and current strategies proposed to overcome these issues. The general discussion here presented could prompt further optimization of the process and pave the way for the development of new original structures and innovative applications. [ABSTRACT FROM AUTHOR]

Numerous challenges are confronted when it comes to the recognition of therapeutic agents for treating complex neurodegenerative diseases like Alzheimer's disease (AD). The perplexing pathogenicity of AD embodies cholinergic dysfunction, amyloid beta (Aβ) aggregation, neurofibrillary tangle formation, neuroinflammation, mitochondrial disruption along with vicious production of reactive oxygen species (ROS) generating oxidative stress. In this frame of reference, drugs with multi target components could prove more advantageous to counter complex pathological mechanisms that are responsible for AD progression. For as much as, medicinal plant based pharmaco-therapies are emerging as potential candidates for AD treatment keeping the efficacy and safety parameters in terms of toxicity and side effects into consideration. Huperzine A (Hup A) is a purified alkaloid compound extracted from a club moss called Huperzia serrata. Several studies have reported both cholinergic and non-cholinergic effects of this compound on AD with significant neuroprotective properties. The present review convenes cumulative demonstrations of neuroprotection provided by Hup A in in vitro, in vivo, and human studies in various pathologies. The underlying molecular mechanisms of its actions have also been discussed. However, more profound evidence would certainly promote the therapeutic implementation of this drug thus furnishing decisive insights into AD therapeutics and various other pathologies along with preventive and curative management. [ABSTRACT FROM AUTHOR]

Background: Mepiquat chloride (DPC) enhances the resistance of cotton plants, and it is widely used as a growth regulator. DPC can stimulate photosynthesis, stabilize the structure of cotton leaves, and affect population reproduction and energy substances in Aphis gossypii Glover (cotton aphids), but interactions between DPC and cotton aphids remain unclear. In this study, we analyzed the physiological responses of cotton to DPC, and the toxicity of DPC toward cotton aphids, before and after feeding, to explore the DPC-induced defense mechanism against cotton aphids. Results: Measurements of protective enzyme activity in cotton showed that the soluble protein contents, peroxidase (POD) activity, and catalase (CAT) activity in cotton treated with different concentrations of DPC were higher than in the control. Superoxide dismutase (SOD) activity was higher than that of the control when the concentration of DPC was < 0.1 g/L. Under aphid feeding stress, POD activity in cotton treated with a low insect population density was significantly lower than in the controls, but the reverse was true for cotton treated with a high insect population density, and SOD activity was positively correlated with population density. The activities of detoxification enzymes in field and laboratory experiments showed that DPC promoted the specific activity of glutathione S-transferase (GST) in cotton aphids, while the specific activities of carboxylesterase (CarE) and acetylcholinesterase (AchE) were decreased. Conclusions: DPC enhanced the aphid resistance in cotton by increasing the soluble protein content and the activity of protective enzymes. It also had a toxic effect on cotton aphids by increasing GST activity (the main DPC target). DPC increased the soluble protein content and protective enzymes activity in cotton under aphid stress, and thereby enhanced tolerance to cotton aphids. It conclude that DPC interferes with cotton aphids through indirect (DPC induced cotton defense responses) and direct (DPC toxicity to cotton aphids) ways, which plays a positive role in interfering with cotton aphids. [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder with progressive loss of memory and other cognitive functions. The pathogenesis of this disease is complex and multifactorial, and remains obscure until now. To enhance the declined level of acetylcholine (ACh) resulting from loss of cholinergic neurons, acetylcholinesterase (AChE) inhibitors are developed and successfully approved for AD treatment in the clinic, with a limited therapeutic effectiveness. At present, it is generally accepted that multi-target strategy is potently useful for designing novel drugs for AD. Accumulated evidence reveals that Kv channels, which are broadly expressed in brain and possess crucial functions in modulating the neuronal activity, are inhibited by several acetylcholinesterase (AChE) inhibitors, such as tacrine, bis(7)-tacrine, donepezil and galantamine. Inhibition of Kv channels by these AChE inhibitors can generate neuroprotective effects by either mitigating Aβ toxicity and neuronal apoptosis, or facilitating cell proliferation. These inhibitory effects provide additional explanations for clinical beneficial effectiveness of AChE inhibitors, meaning that Kv channel is a promising candidate target for novel drugs for AD therapy. [ABSTRACT FROM AUTHOR]

Molecular docking has been performed to investigate the binding mode of (−)-meptazinol (MEP) with acetylcholinesterase (AChE) and to screen bis-meptazinol (bis-MEP) derivatives for preferable synthetic candidates virtually. A reliable and practical docking method for investigation of AChE ligands was established by the comparison of two widely used docking programs, FlexX and GOLD. In our hands, we had more luck using GOLD than FlexX in reproducing the experimental poses of known ligands (RMSD<1.5 Å). GOLD fitness values of known ligands were also in good agreement with their activities. In the present GOLD docking protocol, (−)-MEP seemed to bind with the enzyme catalytic site in an open-gate conformation through strong hydrophobic interactions and a hydrogen bond. Virtual screening of a potential candidate compound library suggested that the most promising 15 bis-MEP derivatives on the list were mainly derived from (−)-MEP with conformations of (S,S) and (SR,RS) and with a 2- to 7-carbon linkage. Although there are still no biological results to confirm the predictive power of this method, the current study could provide an alternate tool for structural optimization of (−)-MEP as new AChE inhibitors. [ABSTRACT FROM AUTHOR]

Botanical insecticides are preferred for their environment and user-friendly nature. Eugenol is a plant-based monoterpene having multifarious biocidal activities. To understand whether eugenol would persistently work against Aedes aegypti, we performed larvicidal bioassays on thirty successive generations and determined median lethal concentration (LC50) on each generation. Results showed no apparent differences between LC50 at F0 (63.48 ppm) and F30 (64.50 ppm) indicating no alteration of susceptibility toward eugenol. To analyze, if eugenol has any effect on metabolic detoxification-associated enzymes, we measured esterases (alpha and beta), cytochrome P450, and GST activities from the survived larvae exposed to LC50 concentration from F0–F30. Results revealed a decrease of esterases, GST, and cytochrome P450 activities at the initial 4–8 generations and then a gradual increase as the generations progressed. GST activity remained significantly below the control groups. Synergists (TPP, DEM, and PBO) were applied along with eugenol at F30 and LC50 concentration, and the said enzyme activities were recorded. Results showed a noticeable decrease in LC50 and enzyme activities indicating effective inhibitions of the respective enzymes. Overall, present results inferred that eugenol would effectively work as a larvicide for a longer period in successive generations without initiating rapid resistance and therefore could be advocated for controlling A. aegypti. [ABSTRACT FROM AUTHOR]

The thyroglobulin (TG) protein is essential to thyroid hormone synthesis, plays a vital role in the regulation of metabolism, development and growth and serves as intraglandular iodine storage. Its architecture is conserved among vertebrates. Synthesis of triiodothyronine (T3) and thyroxine (T4) hormones depends on the conformation, iodination and post-translational modification of TG. Although structural information is available on recombinant and deglycosylated endogenous human thyroglobulin (hTG) from patients with goiters, the structure of native, fully glycosylated hTG remained unknown. Here, we present the cryo-electron microscopy structure of native and fully glycosylated hTG from healthy thyroid glands to 3.2 Å resolution. The structure provides detailed information on hormonogenic and glycosylation sites. We employ liquid chromatography–mass spectrometry (LC-MS) to validate these findings as well as other post-translational modifications and proteolytic cleavage sites. Our results offer insights into thyroid hormonogenesis of native hTG and provide a fundamental understanding of clinically relevant mutations. The iodinated thyroglobulin functions as iodine storage and carrier protein and a precursor for thyroid hormone (TH) biogenesis. Here, the authors report the structure of native, fully glycosylated human thyroglobulin, revealing the location of the hTg hormonogenic and glycosylation sites. [ABSTRACT FROM AUTHOR]

Two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is a cosmopolitan pest species that can feed on more than 1000 host plant species. Historically, organophosphate (OP) and carbamate insecticides have been used to control this extremely polyphagous pest. However, its ability to develop acaricide resistance rapidly has led to failure in control. Mutations in acetylcholinesterase gene (ace), the target-site of OP and carbamate insecticides, have been reported to be one of the major mechanisms underlying this developing resistance. In this study, mutations previously associated with resistance (G119S, A201S, T280A, G328A, F331W/Y) in ace have been screened in 37 T. urticae populations collected across Turkey. All mutations were found in various populations, except G119S. Almost all populations had F331W/Y mutation (being fixed in 32 populations), whereas only two populations harboured A201S mutation, but not fixed. On the other hand, more than half of the populations contained T280A and G328A mutations. In addition, the presence of same haplotypes in populations originating from distinct geographic locations and a wide variety of ace haplotypes might indicate multiple origins of F331W and F331Y mutations; however, this needs further investigation. The results of area-wide screening showed that ace mutations are widely distributed among T. urticae populations. Therefore, the use of this group of insecticides should be limited or only rotational use might be regarded as a resistance management tool due to its different mode of action from other main acaricide groups in T. urticae control across Turkey. [ABSTRACT FROM AUTHOR]

BACKGROUND Varroa destructor is among the greatest threats to honey bee health worldwide. Acaricides used to control Varroa are becoming increasingly ineffective due to resistance issues, prompting the need for new compounds that can be used for control purposes. Ideally, such compounds would exhibit high toxicity to Varroa while maintaining relatively low toxicity to bees and beekeepers. We characterized the lethal concentrations (LC50) of amitraz, matrine, FlyNap®, the experimental carbamates 2‐((2‐ethylbutyl)thio)phenyl methylcarbamate (1) and 2‐(2‐ethylbutoxy)phenyl methylcarbamate (2), and dimethoate (positive control) for Varroa using a glass vial assay. The test compounds also were applied to honey bees using an acute contact toxicity assay to determine the adult bee LD50 for each compound. RESULTS: Amitraz was the most toxic compound to Varroa, but carbamate 2 was nearly as active (within 2‐fold) and the most selective due to its lower bee toxicity, demonstrating its promise as a Varroa control. While carbamate 1 was less toxic to honey bees than was amitraz, it was also 4.7‐fold less toxic to the mites. Both matrine and FlyNap® were relatively ineffective at killing Varroa and were moderately toxic to honey bees. CONCLUSION: Additional testing is required to determine if carbamate 2 can be used as an effective Varroa control. As new chemical treatments are identified, it will be necessary to determine how they can be utilized best alongside other control techniques as part of an integrated pest management program. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The continued drug discovery failures in complex neurodegenerative diseases, including Alzheimer's disease (AD), has raised questions about the classical paradigm "one‐drug, one‐target, one‐disease." In parallel, the ever‐increasing awareness of the multiplicity of the underlying pathways has led to the affirmation of polypharmacological approaches. Polypharmacology, which broadly embodies the use of pharmaceutical agents acting on multiple targets, seems to be the best way to restore the complex diseased network and to provide disease‐modifying effects in AD. In this review, our aim is to provide a roadmap into a world that is still only partly explored and that should be seen as a continuum of pharmacological opportunities, from drug combinations to multitarget‐directed ligands (both codrugs and hybrids). Each modality has unique features that can be effectively exploited by medicinal chemists. We argue that understanding their advantages and drawbacks is very helpful in choosing a proper approach and developing successful AD multitarget drug‐discovery endeavors. We also briefly dwell on (co)target validation, an aspect that is quite often neglected, but critical for an efficient clinical translation. We substantiate our discussion with instructive examples taken from the recent literature. Our wish is that, in spite of the specter of the high attrition rates, best researchers preferring to enter, stay, and progress in the field would help grow the sector and develop AD polypharmacology to full potential. [ABSTRACT FROM AUTHOR]

Malaria parasites contain an essential organelle called the apicoplast that houses metabolic pathways for fatty acid, heme, isoprenoid, and iron–sulfur cluster synthesis. Surprisingly, malaria parasites can survive without the apicoplast as long as the isoprenoid precursor isopentenyl pyrophosphate (IPP) is supplemented in the growth medium, making it appear that isoprenoid synthesis is the only essential function of the organelle in blood‐stage parasites. In the work described here, we localized an enzyme responsible for coenzyme A synthesis, DPCK, to the apicoplast, but we were unable to delete DPCK, even in the presence of IPP. However, once the endogenous DPCK was complemented with the E. coli DPCK (EcDPCK), we were successful in deleting it. We were then able to show that DPCK activity is required for parasite survival through knockdown of the complemented EcDPCK. Additionally, we showed that DPCK enzyme activity remains functional and essential within the vesicles present after apicoplast disruption. These results demonstrate that while the apicoplast of blood‐stage P. falciparum parasites can be disrupted, the resulting vesicles remain biochemically active and are capable of fulfilling essential functions. SYNOPSIS: Isoprenoid production is thought to be the key function of the essential apicoplast organelle in blood‐stage malaria parasites. Here, coenzyme A (CoA) generated by dephospho‐CoA kinase (DPCK) even after antibiotics‐mediated apicoplast disruption is found as an indispensable apicoplast product. P. falciparum DPCK is an essential apicoplast‐localized protein that cannot be bypassed through isoprenoid precursor supplementation.Complementation with E. coli DPCK allows for endogenous DPCK deletion, indicating its conserved function and essentiality.DPCK is present in disrupted apicoplast vesicles and remains enzymatically active, generating CoA required for parasite survival. [ABSTRACT FROM AUTHOR]

A new series of metronidazole-1,2,3-triazole derivatives 6a–o was synthesized and evaluated as Helicobacter pylori urease inhibitors. All the synthesized compounds were more potent than standard inhibitor thiourea against urease. Among the synthesized compounds, compound 6f (IC50 = 1.975 ± 0.25 µM) with inhibitory activity around 11-fols more than thiourea (IC50 = 22.00 ± 0.14 µM) was the most potent compound. Kinetic study of this compound revealed that compound 6f inhibited urease in an uncompetitive mode. Based on molecular modeling study, compound 6f pointed toward the bi-nickel center and stabilized by H-bond and T-shape π–π hydrophobic interactions with the critical residues His492 and Asp633. Moreover, it anchored to the helix-turn-helix motif in the active site cavity through interaction with His593 and Arg609. Consequently, it proposed that compound 6f through stabilization of active site flap inhibited urease activity. [ABSTRACT FROM AUTHOR]

BACKGROUND The purpose of this research was to explore the possibility of co‐applying pyrethroids (agonists of voltage‐sensitive sodium channels) with potassium channel blockers in order to potentiate the neurological effects of pyrethroids on Anopheles gambiae. We hypothesized that the toxicity of pyrethroids caused by persistent sodium currents would be augmented by blockage of outward potassium current flow, which normally repolarizes the membrane potential during a nerve membrane action potential. RESULTS: Topical treatments with LD10s (10% mortality doses) of synergists were given with pyrethroids. 2S‐65465 (2S) showed the best synergism of permethrin (8.6‐fold) and deltamethrin (7.2‐fold), whereas piperonyl butoxide and 4‐aminopyridine only showed 2.2‐ to 3.4‐fold synergism with these pyrethroids. In electrophysiological recordings of Periplaneta americana giant axons, 2S (10 μm) and 4‐AP (30 μm) caused multiple spikes after a single stimulation. Permethrin at 10 μm showed significant summating depolarization (4.5 ± 1.1 mV) after a train of ten stimuli were applied at 5 Hz, and deltamethrin at 0.03 μm showed significant membrane depolarization of 2.9 ± 0.4 mV without stimuli. 2S at 0.3 μm and 4‐AP at 1–3 μm significantly synergized the effects of 3 μm permethrin and 0.01 μm deltamethrin. CONCLUSIONS: Co‐application of potassium channel blockers 2S and 4‐AP with pyrethroids can synergize the mosquitocidal activities on An. gambiae, and these activities are correlated with synergistic effects at the level of the nerve membrane. If deployed in the field, this approach can potentially reduce the amount of chemicals needed for effective control of mosquitoes. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND The compound 2‐((4‐ethyl‐5‐(pyridin‐3‐yl)‐4H‐1,2,4‐triazol‐3‐yl)thio)‐N‐(4‐ethylphenyl) acetamide (VUAA1) is reported to be an odorant receptor co‐receptor (Orco) agonist in insects with potential use as an insect repellent. For this study, the biological activity of VUAA1 was investigated in several bioassays with Aedes aegypti, including adult contact, spatial repellency, and larval repellency assays, as well as topical, injection, and feeding toxicity assays. Neurophysiological action was further explored by analysis of fruit fly central nervous system firing, cockroach axon recordings, patch clamp analysis of Kv2 potassium channel, and acetylcholinesterase inhibition studies. Finally, the metabolic impact on the toxicity of VUAA1 was explored by applying it in combination with established metabolic synergists. RESULTS: In repellency and bite protection screens, VUAA1 showed little activity against adult mosquitoes, apparently due to its low volatility, since its effectiveness was increased by heating or mixing with transfluthrin acid and citronella oil. It did produce measurable repellency of mosquito larvae that was more potent than N,N‐diethyl‐m‐toluamide (DEET). Overall, VUAA1 showed low acute toxicity to both insects and mice, and it was weakly synergized by triphenyl phosphate. There was no observed cross‐resistance in a pyrethroid‐resistant strain of Anopheles gambiae. VUAA1 showed a two‐phase effect on the central nervous system, with neuroexcitation at 1 μmol L‐1 and an inhibitory effect at 100 μmol L‐1 that may relate to block of Kv2 potassium channels. CONCLUSIONS: VUAA1 presented low toxicity, similar to other insect repellents. Its limited solubility, low volatility, and resulting poor adult repellency without additional adjuvants may restrict the utility of VUAA1 in typical public health applications. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The non-target toxicity and resistance problems of acetylcholinesterase (AChE) insecticides, such as organophosphates and carbamates, are of growing concern. To explore the potential targets for achieving inhibitor selectivity, the AChE structures at or near the catalytic pocket of Tetranychus urticae (TuAChE), honey bees, and humans were compared. The entrances to the AChE catalytic pocket differ significantly because of their different peripheral sites. The role of these potential mite-specific sites in AChE function was further elucidated by site-directed mutagenesis of these sites and then examining the catalytic activities of TuAChE mutants. The spider mite E316, H369, and V105 active sites are important for AChE function. By further analyzing their physostigmine inhibitory properties and the detailed interaction between physostigmine and TuAChE, the peripheral site H369 locating near the gorge entrance, and S154 at the oxyanion hole, affects substrate and inhibitor trafficking. The discovery of conserved mite-specific residues in Tetranychus will enable the development of safer, effective pesticides that target residues present only in mite AChEs, potentially offering effective control against this important agricultural pest. [ABSTRACT FROM AUTHOR]

BACKGROUND: The selective insecticide flonicamid shows highly insecticidal activities against piercing-sucking insects and has been widely used for the control of Hemipteran insect pests, whereas its effects on Lepidopteran insect pests remain largely unknown. Recently, inward rectifier potassium (Kir) channel has been verified to be a target of flonicamid, however, functional characterization of Lepidopteran Kir genes is still lacking. RESULTS: Flonicamid shows no insecticidal toxicity against Chilo suppressalis larvae. However, the feeding and growth of larvae were reversibly inhibited by flonicamid (50–1200 mg L−1). Flonicamid treatment also remarkably reduced and delayed the pupation and eclosion of Chilo suppressalis. Additionally, five distinct Kir channel genes (CsKir1, CsKir2A, CsKir2B, CsKir3A and CsKir3B) were cloned from Chilo suppressalis. Expression profiles analysis revealed that CsKir2A was predominately expressed in the hindgut of larvae, whereas CsKir2B had high expressions in the Malpighian tubules and hindgut. RNA interference (RNAi)-mediated knockdown of CsKir2B significantly reduced the growth and increased the mortalities of larvae, whereas silencing of CsKir2A had no obvious effects on Chilo suppressalis. CONCLUSION: Flonicamid exhibits adverse effects on the growth and development of Chilo suppressalis. CsKir2B might be involved in the feeding behavior of Chilo suppressalis. These results provide valuable information on the effects of flonicamid on non-target insects as well as the function of insect Kir channels, and are helpful in developing new insecticide targeting insect Kir channels. [ABSTRACT FROM AUTHOR]

G-quadruplexes (G4s) are guanine rich and i-motifs are cytosine rich non-canonical four-stranded DNA secondary structures present throughout the genome. Their presence in important regulatory regions of the genome marks their significance in biology. This perspective discusses the importance of both G-quadruplex and i-motif structures and highlights their discovery, structural uniqueness, prevalence, and role in the biological system. Herein, we discuss the ligands developed in our laboratory that target G-quadruplexes and i-motifs and modulate gene expression in cancer cells. We also shed light on some recent techniques developed by us to simplify the synthesis and screening of G4 and i-motif specific ligands and their importance in anti-cancer therapeutics. Synopsis: G-quadruplexes and i-motifs are non-canonical DNA secondary structures prevalent in the telomeric region as well as in the regulatory regions of proto-oncogenes. We have described selective targeting of DNA secondary structures by small molecules and their functional role in the regulation of gene expression. [ABSTRACT FROM AUTHOR]

Vector population control using insecticides is a key element of current strategies to prevent malaria transmission in Africa. The introduction of effective insecticides, such as the organophosphate pirimiphos-methyl, is essential to overcome the recurrent emergence of resistance driven by the highly diverse Anopheles genomes. Here, we use a population genomic approach to investigate the basis of pirimiphos-methyl resistance in the major malaria vectors Anopheles gambiae and A. coluzzii. A combination of copy number variation and a single non-synonymous substitution in the acetylcholinesterase gene, Ace1, provides the key resistance diagnostic in an A. coluzzii population from Côte d'Ivoire that we used for sequence-based association mapping, with replication in other West African populations. The Ace1 substitution and duplications occur on a unique resistance haplotype that evolved in A. gambiae and introgressed into A. coluzzii, and is now common in West Africa primarily due to selection imposed by other organophosphate or carbamate insecticides. Our findings highlight the predictive value of this complex resistance haplotype for phenotypic resistance and clarify its evolutionary history, providing tools to for molecular surveillance of the current and future effectiveness of pirimiphos-methyl based interventions. Author summary: Control of mosquito populations via insecticidal tools or interventions is a mainstay of campaigns to reduce malaria transmission. However, especially in sub-Saharan Africa, continued insecticidal selection pressure on the most important species of Anopheles malaria mosquitoes has favoured the evolutionary selection of increasingly effective resistance mechanisms. We investigate the genetic basis of resistance to the organophosphate pirimiphos-methyl, the dominant insecticide now used for indoor residual spraying campaigns in Africa. Genome-wide association analysis of a population from Cote d'Ivoire showed that resistant specimens share a unique combination of mutations in one gene, the acetylcholinesterase enzyme, which constitute the prime cause of pirimiphos-methyl resistance. Further testing of these mutations in diagnostic assays involving two major malaria vectors, A. coluzzii and A. gambiae, validate their use as informative predictors of pirimiphos-methyl resistance. Using data from a large collection of whole genome sequenced specimens from a broader range of locations (Burkina-Faso, Côte d'Ivoire, Ghana, and Guinea), our evolutionary analyses demonstrate that these mutations emerged in A. gambiae and transferred into A. coluzzii by inter-specific hybridisation. Our results show how resistance mechanisms in key malaria vectors have developed and spread, and provide validated tools for molecular surveillance to inform public health campaigns. [ABSTRACT FROM AUTHOR]

Herein, I intend to capture highlights shared with my academic and research colleagues over the 60 years I devoted initially to my graduate and postdoctoral training and then to academic endeavors starting as an assistant professor in a new medical school at the University of California, San Diego (UCSD). During this period, the Department of Pharmacology emerged from a division within the Department of Medicine to become the first basic science department, solely within the School of Medicine at UCSD in 1979. As part of the school's plans to reorganize and to retain me at UCSD, I was appointed as founding chair. Some years later in 2002, faculty, led largely within the Department of Pharmacology and by practicing pharmacists within UCSD Healthcare, started the independent Skaggs School of Pharmacy and Pharmaceutical Sciences with a doctor of pharmacy (PharmD) program, where I served as the founding dean. My career pathway, from working at my family-owned pharmacy to chairing a department in a school of medicine and then becoming the dean of a school of pharmacy at a research-intensive, student-centered institution, involved some risky decisions. But the academic, curricular, and accreditation challenges posed were met by a cadre of creative faculty colleagues. I offer my experiences to individuals confronted with a multiplicity of real or imagined opportunities in academic health sciences, the related pharmaceutical industry, and government oversight agencies. [ABSTRACT FROM AUTHOR]

Aloysia citrodora essential oil has been described as a potential new candidate for treating Alzheimer's disease (AD). It displays a range of pharmacological properties, including acetylcholinesterase (AChE) inhibition worthy of investigation. The essential oil of the fresh leaves of A. citrodora was obtained by hydrodistillation, and the composition of the essential oil was investigated using GC-MS (Gas Chromatography-Mass Spectrometry). Sixty compounds were identified, which were composed of oxygenated monoterpenes and sesquiterpenes. In the evaluation of the anticholinesterase activity of the essential oil through virtual screening, molecular docking and bioassay were used. Seven main components were identified namely caryophyllene oxide, geranyl acetate, ß-sesquiphellandrene ß-curcumene, ß-/ar-curcumene, ß-/(Z)-a-bisabolene, trans-calamenene, and ß-sesquiphellandrene. Three compounds (geranyl acetate, caryophyllene oxide and bisabolene) were available commercially and assessed for AChE inhibitory activity to validate the approach. The dose-response relationship showed that AChE inhibitory with ICR50R= 5.3 µM for caryophyllene oxide and 244.5 µM for geranyl acetate. The molecular docking study revealed that A. citrodora may yield new selective inhibitors of AChE from plant-originated essential oils. [ABSTRACT FROM AUTHOR]