Aerobic Metabolism Alterations as an Evidence of Underlying Deltamethrin Resistance Mechanisms in Triatoma infestans (Hemiptera: Reduviidae)

2020 ◽  
Vol 57 (6) ◽  
pp. 1988-1991
Author(s):  
Carmen Rolandi ◽  
Gonzalo Roca-Acevedo ◽  
Pablo E Schilman ◽  
Mónica D Germano
Keyword(s):  
Resistance Mechanism ◽  
Resistance Management ◽  
Resistance Mechanisms ◽  
Target Site ◽  
Triatoma Infestans ◽  
Co2 Production ◽  
Mechanisms Of Resistance ◽  
Metabolic Resistance ◽  
Open Flow ◽  
Deltamethrin Resistance

Abstract Triatoma infestans (Klug, 1834), the main vector of Chagas disease in Latin America, is regularly controlled by spraying the pyrethroid deltamethrin, to which some populations have developed resistance. The three main mechanisms of resistance are 1) metabolic resistance by overexpression or increased activity of detoxifying enzymes, 2) target site mutations, and 3) cuticle thickening/modification. We use open-flow respirometry to measure real-time H2O loss rate (V˙H2O) and CO2 production rate (V˙CO2), on nymphs from susceptible and resistant populations before and after exposure to the insecticide to understand the underlying mechanisms of resistance in live insects. Lack of differences in V˙H2O between populations suggested that cuticular thickness/composition is not acting as a relevant resistance mechanism. Similarly, there was no difference in resting V˙CO2, suggesting a trade-off between resistance mechanisms and other physiological processes. The increment in V˙CO2 after application of deltamethrin was similar in both populations, which suggested that while enhanced enzymatic detoxification may play a role in resistance expression in this population, the main mechanism involved should be a passive one such as target site mutations. Open-flow respirometry provided useful evidence for evaluating the mechanisms involved in deltamethrin resistance. Using this technique could improve efficiency of scientific research in the area of insecticide resistance management, leading to a faster decision making and hence improved control results.

scholarly journals A high diversity of mechanisms endows ALS-inhibiting herbicide resistance in the invasive common ragweed (Ambrosia artemisiifolia L.)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ingvild Loubet ◽  
Laëtitia Caddoux ◽  
Séverine Fontaine ◽  
Séverine Michel ◽  
Fanny Pernin ◽  
...  
Keyword(s):  
Resistance Mechanism ◽  
Resistance Management ◽  
Genotyping By Sequencing ◽  
Ambrosia Artemisiifolia ◽  
Target Site ◽  
Major Type ◽  
Common Ragweed ◽  
Resistance Evolution ◽  
Arable Weed ◽  
Target Site Resistance

AbstractAmbrosia artemisiifolia L. (common ragweed) is a globally invasive, allergenic, troublesome arable weed. ALS-inhibiting herbicides are broadly used in Europe to control ragweed in agricultural fields. Recently, ineffective treatments were reported in France. Target site resistance (TSR), the only resistance mechanism described so far for ragweed, was sought using high-throughput genotyping-by-sequencing in 213 field populations randomly sampled based on ragweed presence. Additionally, non-target site resistance (NTSR) was sought and its prevalence compared with that of TSR in 43 additional field populations where ALS inhibitor failure was reported, using herbicide sensitivity bioassay coupled with ALS gene Sanger sequencing. Resistance was identified in 46 populations and multiple, independent resistance evolution demonstrated across France. We revealed an unsuspected diversity of ALS alleles underlying resistance (9 amino-acid substitutions involved in TSR detected across 24 populations). Remarkably, NTSR was ragweed major type of resistance to ALS inhibitors. NTSR was present in 70.5% of the resistant plants and 74.1% of the fields harbouring resistance. A variety of NTSR mechanisms endowing different resistance patterns evolved across populations. Our study provides novel data on ragweed resistance to herbicides, and emphasises that local resistance management is as important as mitigating gene flow from populations where resistance has arisen.

scholarly journals Some approaches to new antibacterial agents

2007 ◽  
Vol 79 (12) ◽  
pp. 2143-2153 ◽  
Author(s):  
John B. Bremner
Keyword(s):  
Bacterial Resistance ◽  
Efflux Pump ◽  
Transmembrane Protein ◽  
Resistance Mechanism ◽  
Resistance Mechanisms ◽  
Target Site ◽  
Resistant Bacteria ◽  
General Strategy ◽  
Dual Action ◽  
Hybrid Drugs

Bacteria use a number of resistance mechanisms to counter the antibacterial challenge, and one of these is the expression of transmembrane protein-based efflux pumps which can pump out antibacterials from within the cells, thus lowering the antibacterial concentration to nonlethal levels. For example, in S. aureus, the NorA pump can pump out the antibacterial alkaloid berberine and ciprofloxacin. One general strategy to reduce the health threat of resistant bacteria is to block a major bacterial resistance mechanism at the same time as interfering with another bacterial pathway or target site. New developments of this approach in the context of dual-action prodrugs and dual-action (or hybrid) drugs in which one action is targeted at blocking the NorA efflux pump and the second action at an alternative bacterial target site (or sites) for the antibacterial action are discussed. The compounds are based on a combination of 2-aryl-5-nitro-1H-indole derivatives (as the NorA efflux pump blocking component) and derivatives of berberine. General design principles, syntheses, antibacterial testing, and preliminary work on modes of action studies are discussed.

Carbapenem-resistantAcinetobacter baumannii: diversity of resistant mechanisms and risk factors for infection

2011 ◽  
Vol 140 (1) ◽  
pp. 137-145 ◽  
Author(s):  
Y. J. KIM ◽  
S. I. KIM ◽  
Y. R. KIM ◽  
K. W. HONG ◽  
S. H. WIE ◽  
...  
Keyword(s):  
Risk Factors ◽  
Efflux Pump ◽  
Clinical Epidemiology ◽  
Resistance Mechanism ◽  
Resistance Mechanisms ◽  
Apache Ii Score ◽  
Mechanisms Of Resistance ◽  
High Apache ◽  
Carbapenem Resistant ◽  
Clonal Spread

SUMMARYCarbapenem-resistantAcinetobacter baumannii(CRAB) are an increasing infectious threat in hospitals. We investigated the clinical epidemiology of CRAB infectionsvs. colonization in patients, and examined the mechanisms of resistance associated with elevated minimum inhibitory concentrations (MICs) for carbapenems. From January to June 2009, 75 CRAB strains were collected. CRAB infection was significantly associated with malignancy and a high APACHE II score. The most dominant resistance mechanism was ISAba1preceding OXA-51, producing strains with overexpression of efflux pump. Strains carryingblaOXA-23-like enzymes had higher carbapenem MICs than those carryingblaOXA-51-like enzymes; however, the presence of multiple mechanisms did not result in increased resistance to carbapenems. There was no difference in the resistance mechanisms in strains from infected and colonized patients. The majority of strains were genetically diverse by DNA macrorestriction although there was evidence of clonal spread of four clusters of strains in patients.

scholarly journals Target-Site Resistances to ALS and PPO Inhibitors Are Linked in Waterhemp (Amaranthus tuberculatus)

Weed Science ◽  
2016 ◽  
Vol 65 (1) ◽  
pp. 4-8 ◽  
Author(s):  
Patrick J. Tranel ◽  
Chenxi Wu ◽  
Ahmed Sadeque
Keyword(s):  
Resistance Mechanism ◽  
Acetolactate Synthase ◽  
Resistance Mechanisms ◽  
Target Site ◽  
Recurrent Parent ◽  
Common Waterhemp ◽  
Independent Assortment ◽  
Resistance Evolution ◽  
Amaranthus Tuberculatus ◽  
Molecular Marker Analysis

It is generally expected that, in the case of multiple herbicide resistance, different resistance mechanisms within a weed will follow Mendel’s law of independent assortment. Research was conducted to investigate anecdotal observations suggesting that target site–based resistances to inhibitors of acetolactate synthase (ALS) and protoporphyrinogen oxidase (PPO) did not follow independent assortment in common waterhemp. Cosegregation of the two resistances was observed in backcross lines (population sensitive to both herbicides as recurrent parent). Specifically, whereas 52% of backcross plants were resistant to a PPO inhibitor, this percentage increased to 92% when the backcross plants were preselected for resistance to an ALS inhibitor. Molecular marker analysis confirmed that the corresponding genes (ALSandPPX2) were genetically linked. When data from all plants analyzed were pooled, the genetic distance between the two genes was calculated to be 7.5 cM. The two genes were found to be about 195 kb apart in the recently published grain amaranth genome, explaining the observed genetic linkage. There is likely enough recombination that occurs between the linked genes to prevent the linkage from having significant implications in terms of resistance evolution. Nevertheless, documentation of the happenstance linkage between target-site genes for resistance to ALS and PPO inhibitors in waterhemp is a reminder that one should not assume distinct resistance mechanism will independently assort.

Section 3. Evaluation of the impact of the strategy on pyrethroid resistance: F1 analyses

1993 ◽  
Vol 1 ◽  
pp. 21-27
Author(s):  
Neil W. Forrester ◽  
Matthew Cahill ◽  
Lisa J. Bird ◽  
Jacquelyn K. Layland
Keyword(s):  
Pyrethroid Resistance ◽  
Resistance Mechanism ◽  
Resistance Management ◽  
Resistance Mechanisms ◽  
Field Resistance ◽  
Relative Importance ◽  
Oxidative Resistance ◽  
Tolerance Curve ◽  
The Impact ◽  
Selection Of

SummaryThe classical resistance monitoring technique using full bioassay lines on laboratory reared F1 progeny of field material was compared to the previously described discriminating dose technique on field collected individuals. The Via tolerance curve analysis of the F1 data clearly indicated the predominance of the oxidative metabolic pyrethroid resistance mechanism from the 1984/85 season onwards. There appears to have been an abrupt change in the relative importance of field resistance mechanisms following the introduction of the insecticide resistance management (IRM) strategy in 1983/84. The strategy seems to have favoured the selection of the more amenable oxidative resistance mechanism over the intractable nerve insensitivity mechanism. The Beeman-Nanis analysis was applied to attempt to identify the relative importance of the various field resistance genes. However, it proved of little value in this study as one of the key assumptions underlying the analysis (full genetic dominance) was not satisfied.

scholarly journals Insecticide resistance selection and reversal in two strains of Aedes aegypti

2020 ◽  
Vol 5 ◽  
pp. 183
Author(s):  
Jonathan Thornton ◽  
Bruno Gomes ◽  
Constância Ayres ◽  
Lisa Reimer
Keyword(s):  
Aedes Aegypti ◽  
Insecticide Resistance ◽  
Vector Competence ◽  
Resistance Mechanisms ◽  
Target Site ◽  
Metabolic Resistance ◽  
Resistance Selection ◽  
Similar Phenotype ◽  
Target Site Resistance ◽  
Homozygous Resistant

Background: Laboratory reared mosquito colonies are essential tools to understand insecticide action. However, they differ considerably from wild populations and from each other depending on their origin and rearing conditions, which makes studying the effects of specific resistance mechanisms difficult. This paper describes our methods for establishing multiple resistant strains of Aedes aegypti from two colonies as a new resource for further research on metabolic and target site resistance. Methods: Two resistant colonies of Ae. aegypti, from Cayman and Recife, were selected through 10 generations of exposure to insecticides including permethrin, malathion and temephos, to yield eight strains with different profiles of resistance due to either target site or metabolic resistance. Resistance ratios for each insecticide were calculated for the selected and unselected strains. The frequency of kdr alleles in the Cayman strains was determined using TaqMan assays. A comparative gene expression analysis among Recife strains was conducted using qPCR in larvae (CCae3A, CYP6N12, CYP6F3, CYP9M9) and adults (CCae3A, CYP6N12, CYP6BB2, CYP9J28a). Results: In the selected strain of Cayman, mortality against permethrin reduced almost to 0% and kdr became fixated by 5 generations. A similar phenotype was seen in the unselected homozygous resistant colony, whilst mortality in the susceptible homozygous colony rose to 82.9%. The Recife strains showed different responses between exposure to adulticide and larvicide, with detoxification genes in the temephos selected strain staying similar to the baseline, but a reduction in detoxification genes displayed in the other strains. Conclusions: These selected strains, with a range of insecticide resistance phenotypes and genotypes, will support further research on the effects of target-site and/or metabolic resistance mechanisms on various life-history traits, behaviours and vector competence of this important arbovirus vector.

scholarly journals Impact of target site mutations and plasmid associated resistance genes acquisition on resistance of Acinetobacter baumannii to fluoroquinolones

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mostafa Ahmed Mohammed ◽  
Mohammed T. A. Salim ◽  
Bahaa E. Anwer ◽  
Khaled M. Aboshanab ◽  
Mohammad M. Aboulwafa
Keyword(s):  
Resistance Genes ◽  
Antimicrobial Agents ◽  
Bacterial Species ◽  
Resistance Mechanism ◽  
Resistance Mechanisms ◽  
Target Site ◽  
Resistant Isolate ◽  
Drug Resistant ◽  
Site Mutation ◽  
Encoding Genes

AbstractAmong bacterial species implicated in hospital-acquired infections are the emerging Pan-Drug Resistant (PDR) and Extensively Drug-Resistant (XDR) Acinetobacter (A.) baumannii strains as they are difficult to eradicate. From 1600 clinical specimens, only 100 A. baumannii isolates could be recovered. A high prevalence of ≥ 78% resistant isolates was recorded for the recovered isolates against a total of 19 tested antimicrobial agents. These isolates could be divided into 12 profiles according to the number of antimicrobial agents to which they were resistant. The isolates were assorted as XDR (68; 68%), Multi-Drug Resistant (MDR: 30; 30%), and PDR (2; 2%). Genotypically, the isolates showed three major clusters with similarities ranging from 10.5 to 97.8% as revealed by ERIC-PCR technique. As a resistance mechanism to fluoroquinolones (FQs), target site mutation analyses in gyrA and parC genes amplified from twelve selected A. baumannii isolates and subjected to sequencing showed 12 profiles. The selected isolates included two CIP-susceptible ones, these showed the wild-type profile of being have no mutations. For the ten selected CIP-resistant isolates, 9 of them (9/10; 90%) had 1 gyrA/1 parC mutations (Ser 81 → Leu mutation for gyrA gene and Ser 84 → Leu mutation for parC gene). The remaining CIP-resistant isolate (1/10; 10%) had 0 gyrA/1 parC mutation (Ser 84 → Leu mutation for parC gene). Detection of plasmid-associated resistance genes revealed that the 86 ciprofloxacin-resistant isolates carry qnrA (66.27%; 57/86), qnrS (70.93%; 61/86), aac (6')-Ib-cr (52.32%; 45/86), oqxA (73.25%; 63/86) and oqxB (39.53%; 34/86), while qepA and qnrB were undetected in these isolates. Different isolates were selected from profiles 1, 2, and 3 and qnrS, acc(6,)-ib-cr, oqxA, and oqxB genes harbored by these isolates were amplified and sequenced. The BLAST results revealed that the oqxA and oqxB sequences were not identified previously in A. baumannii but they were identified in Klebsiella aerogenes strain NCTC9793 and Klebsiella pneumoniae, respectively. On the other hand, the sequence of qnrS, and acc(6,)-ib-cr showed homology to those of A. baumannii. MDR, XDR, and PDR A. baumannii isolates are becoming prevalent in certain hospitals. Chromosomal mutations in the sequences of GyrA and ParC encoding genes and acquisition of PAFQR encoding genes (up to five genes per isolate) are demonstrated to be resistance mechanisms exhibited by fluoroquinolones resistant A. baumannii isolates. It is advisable to monitor the antimicrobial resistance profiles of pathogens causing nosocomial infections and properly apply and update antibiotic stewardship in hospitals and outpatients to control infectious diseases and prevent development of the microbial resistance to antimicrobial agents.

scholarly journals Genome-wide gene expression profiling reveals that cuticle alterations and P450 detoxification are associated with pyrethroid resistance in Anopheles arabiensis populations from Ethiopia

2018 ◽  
Author(s):  
Eba Alemayehu Simma ◽  
Wannes Dermauw ◽  
Vasileia Balabanidou ◽  
Simon Snoeck ◽  
Astrid Bryon ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Anopheles Arabiensis ◽  
Pyrethroid Resistance ◽  
Resistance Mutation ◽  
Resistance Mechanisms ◽  
Target Site ◽  
Malaria Vectors ◽  
Metabolic Resistance ◽  
Genome Wide ◽  
Target Site Resistance

AbstractBACKGROUNDVector control is the main intervention in malaria control and elimination strategies. However, the development of insecticide resistance is one of the major challenges for controlling malaria vectors. Anopheles arabiensis populations in Ethiopia showed resistance against both DDT and the pyrethroid deltamethrin. Although a L1014F target-site resistance mutation was present in the voltage gated sodium channel of investigated populations, the levels of resistance and biochemical studies indicated the presence of additional resistance mechanisms. In this study, we used genome-wide transcriptome profiling by RNAseq to assess differentially expressed genes between three deltamethrin and DDT resistant An. arabiensis field populations (Tolay, Asendabo, Chewaka) and two susceptible strains (Sekoru and Mozambique).RESULTSBoth RNAseq analysis and RT-qPCR showed that a glutathione-S-transferase, gstd3, and a cytochrome P450 monooxygenase, cyp6p4, were significantly overexpressed in the group of resistant populations compared to the susceptible strains, suggesting that the enzymes they encode play a key role in metabolic resistance against deltamethrin or DDT. Furthermore, a gene ontology enrichment analysis showed that expression changes of cuticle related genes were strongly associated with insecticide resistance, although this did not translate in increased thickness of the procuticle.CONCLUSIONOur transcriptome sequencing of deltamethrin/DDT resistant An. arabiensis populations from Ethiopia suggests non-target site resistance mechanisms and pave the way for further investigation of the role of cuticle composition in resistance.

scholarly journals Acaricide resistance mechanisms in Rhipicephalus (Boophilus) microplus

2012 ◽  
Vol 21 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Felix David Guerrero ◽  
Léonore Lovis ◽  
João Ricardo Martins
Keyword(s):  
Resistance Mechanism ◽  
Resistance Mechanisms ◽  
Point Of View ◽  
Boophilus Microplus ◽  
Target Site ◽  
Cattle Tick ◽  
Tick Population ◽  
Acaricide Resistance ◽  
Organophosphate Resistance ◽  
Cattle Ticks

Acaricide resistance has become widespread in countries where cattle ticks, Rhipicephalus (Boophilus) microplus, are a problem. Resistance arises through genetic changes in a cattle tick population that causes modifications to the target site, increased metabolism or sequestration of the acaricide, or reduced ability of the acaricide to penetrate through the outer protective layers of the tick’s body. We review the molecular and biochemical mechanisms of acaricide resistance that have been shown to be functional in R. (B.) microplus. From a mechanistic point of view, resistance to pyrethroids has been characterized to a greater degree than any other acaricide class. Although a great deal of research has gone into discovery of the mechanisms that cause organophosphate resistance, very little is defined at the molecular level and organophosphate resistance seems to be maintained through a complex and multifactorial process. The resistance mechanisms for other acaricides are less well understood. The target sites of fipronil and the macrocyclic lactones are known and resistance mechanism studies are in the early stages. The target site of amitraz has not been definitively identified and this is hampering mechanistic studies on this acaricide.

scholarly journals Insecticide resistance in Anopheles arabiensis populations from Dakar and its suburbs: role of target site and metabolic resistance mechanisms

2018 ◽  
Vol 17 (1) ◽  
Author(s):  
A. Kane Dia ◽  
O. Kalsom Guèye ◽  
E. Amadou Niang ◽  
S. Mocote Diédhiou ◽  
M. Demba Sy ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Anopheles Arabiensis ◽  
Resistance Mechanisms ◽  
Target Site ◽  
Metabolic Resistance
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