scholarly journals Is the cost of herbicide resistance expressed in the breakdown of the relationships between characters? A case study using synthetic-auxin-resistant Arabidopsis thaliana mutants

2005 ◽  
Vol 85 (2) ◽  
pp. 101-110 ◽  
Author(s):  
FABRICE ROUX ◽  
XAVIER REBOUD
Keyword(s):  
Resource Allocation ◽  
Arabidopsis Thaliana ◽  
Herbicide Resistance ◽  
Resource Acquisition ◽  
Resistance Mutations ◽  
Herbicide Resistant ◽  
Dominance Level ◽  
Cost Of Resistance ◽  
The Cost

A mutation endowing herbicide resistance is often found to induce a parallel morphological or fitness penalty. To test whether such ‘cost’ of resistance to herbicides is expressed through lower resource acquisition, changes in resource allocation, or both, is of ecological significance. Here, we analysed 12 morphological traits in 900 plants covering three herbicide resistance mutations at genes AUX1, AXR1 and AXR2 in the model species Arabidopsis thaliana. Comparing these 2,4-D herbicide-resistant homozygous (RR) and heterozygous (RS) plants to homozygous susceptible (SS) plants, this analysis estimates the dominance level of the resistance allele on morphology. We also demonstrated that the herbicide resistance cost was primarily expressed as a change in resource acquisition (62·1–94% of the analysed traits). Although AUX1, AXR1 and AXR2 genes act in the same metabolic pathway of auxin response, each resistance factor was found to have its own unique signature in the way the cost was expressed. Furthermore, no link was observed between the absolute fitness penalty and the respective modifications of resource acquisition and/or resource allocation in the resistant plants. These results and their implications for herbicide resistance spread and establishment are discussed.

scholarly journals Cost of resistance: an unreasonably expensive concept

2018 ◽  
Author(s):  
Thomas Lenormand ◽  
Noémie Harmand ◽  
Romain Gallet
Keyword(s):  
Evolutionary Biology ◽  
Resistance Mutation ◽  
Evolutionary Genetics ◽  
Resistance Mutations ◽  
Fitness Effects ◽  
Current Usage ◽  
Important Addition ◽  
Cost Of Resistance ◽  
Peer Community ◽  
The Cost

AbstractThis preprint has been reviewed and recommended by Peer Community In Evolutionary Biology (https://doi.org/10.24072/pci.evolbiol.100052). The cost of resistance, or the fitness effect of resistance mutation in absence of the drug, is a very widepsread concept in evolutionary genetics and beyond. It has represented an important addition to the simplistic view that resistance mutations should solely be considered as beneficial mutations. Yet, this concept also entails a series of serious difficulties in its definition, interpretation and current usage. In many cases, it may be simpler, clearer, and more insightful to study, measure and analyze the fitness effects of mutations across environments and to better distinguish those effects from ‘pleiotropic effects’ of those mutations.

scholarly journals The genomic basis of adaptation to the fitness cost of rifampicin resistance in Pseudomonas aeruginosa

2016 ◽  
Vol 283 (1822) ◽  
pp. 20152452 ◽  
Author(s):  
Qin Qi ◽  
Macarena Toll-Riera ◽  
Karl Heilbron ◽  
Gail M. Preston ◽  
R. Craig MacLean
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Low Cost ◽  
Fitness Cost ◽  
Clinical Settings ◽  
Resistance Mutations ◽  
Beneficial Mutations ◽  
Cost Of Resistance ◽  
Compensatory Mutations ◽  
The Cost

Antibiotic resistance carries a fitness cost that must be overcome in order for resistance to persist over the long term. Compensatory mutations that recover the functional defects associated with resistance mutations have been argued to play a key role in overcoming the cost of resistance, but compensatory mutations are expected to be rare relative to generally beneficial mutations that increase fitness, irrespective of antibiotic resistance. Given this asymmetry, population genetics theory predicts that populations should adapt by compensatory mutations when the cost of resistance is large, whereas generally beneficial mutations should drive adaptation when the cost of resistance is small. We tested this prediction by determining the genomic mechanisms underpinning adaptation to antibiotic-free conditions in populations of the pathogenic bacterium Pseudomonas aeruginosa that carry costly antibiotic resistance mutations. Whole-genome sequencing revealed that populations founded by high-cost rifampicin-resistant mutants adapted via compensatory mutations in three genes of the RNA polymerase core enzyme, whereas populations founded by low-cost mutants adapted by generally beneficial mutations, predominantly in the quorum-sensing transcriptional regulator gene lasR . Even though the importance of compensatory evolution in maintaining resistance has been widely recognized, our study shows that the roles of general adaptation in maintaining resistance should not be underestimated and highlights the need to understand how selection at other sites in the genome influences the dynamics of resistance alleles in clinical settings.

scholarly journals Epistasis between antibiotic resistance mutations and genetic background shape the fitness effect of resistance across species of Pseudomonas

2016 ◽  
Vol 283 (1830) ◽  
pp. 20160151 ◽  
Author(s):  
T. Vogwill ◽  
M. Kojadinovic ◽  
R. C. MacLean
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Mutations ◽  
Bacterial Strains ◽  
Fitness Effect ◽  
Epistatic Interactions ◽  
Fitness Effects ◽  
Cost Of Resistance ◽  
Pathogen Populations ◽  
The Cost ◽  
Antibiotic Resistance Mutations

Antibiotic resistance often evolves by mutations at conserved sites in essential genes, resulting in parallel molecular evolution between divergent bacterial strains and species. Whether these resistance mutations are having parallel effects on fitness across bacterial taxa, however, is unclear. This is an important point to address, because the fitness effects of resistance mutations play a key role in the spread and maintenance of resistance in pathogen populations. We address this idea by measuring the fitness effect of a collection of rifampicin resistance mutations in the β subunit of RNA polymerase ( rpoB ) across eight strains that span the diversity of the genus Pseudomonas . We find that almost 50% of rpoB mutations have background-dependent fitness costs, demonstrating that epistatic interactions between rpoB and the rest of the genome are common. Moreover, epistasis is typically strong, and it is the dominant genetic determinant of the cost of resistance mutations. To investigate the functional basis of epistasis, and because rpoB plays a central role in transcription, we measured the effects of common rpoB mutations on transcriptional efficiency across three strains of Pseudomonas . Transcriptional efficiency correlates strongly to fitness across strains, and epistasis arises because individual rpoB mutations have differential effects on transcriptional efficiency in different genetic backgrounds.

When Ambiguity in Treaty Design Becomes Destructive: A Study of Transboundary Water

2008 ◽  
Vol 8 (1) ◽  
pp. 111-136 ◽  
Author(s):  
Itay Fischhendler
Keyword(s):  
Resource Allocation ◽  
Natural Resources ◽  
Empirical Studies ◽  
Transboundary Water ◽  
Implementation Phase ◽  
Bilateral Relations ◽  
Environmental Regimes ◽  
The Cost ◽  
Short Time

Ambiguity has a clear role in facilitating closure in negotiations to regulate natural resources. However, there are no empirical studies that examine whether such “constructive ambiguity” can in fact become destructive. The aim of the present study is thus to determine when ambiguity becomes destructive during the management phase of environmental regimes. The implementation of the Israeli-Jordanian water agreement is used as a case study. It was found that when political and hydrological conditions are unstable, the parties see the process of clarifying the ambiguities in a water agreement as broader than simply a question of bilateral relations over resource allocation. As a result, the cost of clarifying ambiguity at the implementation phase dramatically increases. The anatomy of resolving ambiguous agreements teaches us that there are early signs that indicate when ambiguity becomes destructive. Tracing these signals is crucial, since the cost of ambiguity is not linear. Rather, when a disagreement around ambiguity passes a threshold, it can escalate into a conflict in a very short time.

Developing Schedule With Linear Programming (Case Study: STTF II Project Komplek Sukamukti Banjaran)

2020 ◽  
Vol 4 (02) ◽  
pp. 34-45
Author(s):  
Naufal Dzikri Afifi ◽  
Ika Arum Puspita ◽  
Mohammad Deni Akbar
Keyword(s):  
Linear Programming ◽  
Objective Function ◽  
Project Scheduling ◽  
Time Limit ◽  
Minimum Time ◽  
Service Cost ◽  
Trade Off ◽  
Overtime Work ◽  
The Cost

Shift to The Front II Komplek Sukamukti Banjaran Project is one of the projects implemented by one of the companies engaged in telecommunications. In its implementation, each project including Shift to The Front II Komplek Sukamukti Banjaran has a time limit specified in the contract. Project scheduling is an important role in predicting both the cost and time in a project. Every project should be able to complete the project before or just in the time specified in the contract. Delay in a project can be anticipated by accelerating the duration of completion by using the crashing method with the application of linear programming. Linear programming will help iteration in the calculation of crashing because if linear programming not used, iteration will be repeated. The objective function in this scheduling is to minimize the cost. This study aims to find a trade-off between the costs and the minimum time expected to complete this project. The acceleration of the duration of this study was carried out using the addition of 4 hours of overtime work, 3 hours of overtime work, 2 hours of overtime work, and 1 hour of overtime work. The normal time for this project is 35 days with a service fee of Rp. 52,335,690. From the results of the crashing analysis, the alternative chosen is to add 1 hour of overtime to 34 days with a total service cost of Rp. 52,375,492. This acceleration will affect the entire project because there are 33 different locations worked on Shift to The Front II and if all these locations can be accelerated then the duration of completion of the entire project will be effective

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