scholarly journals The costs of evolving resistance in heterogeneous parasite environments

2011 ◽  
Vol 279 (1735) ◽  
pp. 1896-1903 ◽  
Author(s):  
Britt Koskella ◽  
Derek M. Lin ◽  
Angus Buckling ◽  
John N. Thompson
Keyword(s):  
Host Resistance ◽  
Experimental Evolution ◽  
Specific Resistance ◽  
Control Strategies ◽  
Resistance Mechanism ◽  
Fitness Costs ◽  
Bacterial Host ◽  
Strong Constraint ◽  
Combined Control ◽  
Evolution Of Resistance

The evolution of host resistance to parasites, shaped by associated fitness costs, is crucial for epidemiology and maintenance of genetic diversity. Selection imposed by multiple parasites could be a particularly strong constraint, as hosts either accumulate costs of multiple specific resistances or evolve a more costly general resistance mechanism. We used experimental evolution to test how parasite heterogeneity influences the evolution of host resistance. We show that bacterial host populations evolved specific resistance to local bacteriophage parasites, regardless of whether they were in single or multiple-phage environments, and that hosts evolving with multiple phages were no more resistant to novel phages than those evolving with single phages. However, hosts from multiple-phage environments paid a higher cost, in terms of population growth in the absence of phage, for their evolved specific resistances than those from single-phage environments. Given that in nature host populations face selection pressures from multiple parasite strains and species, our results suggest that costs may be even more critical in shaping the evolution of resistance than previously thought. Furthermore, our results highlight that a better understanding of resistance costs under combined control strategies could lead to a more ‘evolution-resistant’ treatment of disease.

629 Acquired irofulven-resistance is mediated by a novel and drug-specific resistance mechanism associated with overexpression of ABCA12

2004 ◽  
Vol 2 (8) ◽  
pp. 190
Author(s):  
F. Koeppel ◽  
J.-P. Annereau ◽  
A. Escargueil ◽  
V. Poindessous ◽  
G. Szakacs ◽  
...  
Keyword(s):  
Specific Resistance ◽  
Resistance Mechanism

scholarly journals Species diversity and insecticide resistance within the Anopheles hyrcanus group in Ubon Ratchathani Province, Thailand

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Anchana Sumarnrote ◽  
Hans J. Overgaard ◽  
Vincent Corbel ◽  
Kanutcharee Thanispong ◽  
Theeraphap Chareonviriyaphap ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Control Strategies ◽  
Resistance Mechanism ◽  
Abundant Species ◽  
Malaria Vectors ◽  
Pcr Assay ◽  
Insecticide Susceptibility ◽  
Human Landing ◽  
Early Peak

Abstract Background Members of the Anopheles hyrcanus group have been incriminated as important malaria vectors. This study aims to identify the species and explore the insecticide susceptibility profile within the Anopheles hyrcanus group in Ubon Ratchathani Province, northeastern Thailand where increasing numbers of malaria cases were reported in 2014. Methods Between 2013 and 2015, five rounds of mosquito collections were conducted using human landing and cattle bait techniques during both the rainy and dry seasons. Anopheles mosquitoes were morphologically identified and their insecticide susceptibility status was investigated. Synergist bioassays were carried out with An. hyrcanus (s.l.) due to their resistance to all insecticides. An ITS2-PCR assay was conducted to identify to species the Hyrcanus group specimens. Results Out of 10,361 Anopheles females collected, representing 18 taxa in 2 subgenera, 71.8% were morphologically identified as belonging to the Hyrcanus Group (subgenus Anopheles), followed by An. barbirostris group (7.9%), An. nivipes (6.5%), An. philippinensis (5.9%) and the other 14 Anopheles species. Specimens of the Hyrcanus Group were more prevalent during the rainy season and were found to be highly zoophilic. Anopheles hyrcanus (s.l.) was active throughout the night, with an early peak of activity between 18:00 h and 21:00 h. ITS2-PCR assay conducted on 603 DNA samples from specimens within the Hyrcanus Group showed the presence of five sisters species. Anopheles peditaeniatus was the most abundant species (90.5%, n = 546), followed by An. nitidus (4.5%, n = 27), An. nigerrimus (4.3%, n = 26), An. argyropus (0.5%, n = 3), and An. sinensis (0.2%, n = 1). All An. hyrcanus (s.l.) specimens that were found resistant to insecticides (deltamethrin 0.05%, permethrin 0.75% and DDT 4% and synergist tests) belonged to An. peditaeniatus. The degree of resistance in An. peditaeniatus to each of these three insecticides was approximately 50%. Addition of PBO (Piperonyl butoxide), but not DEF (S.S.S-tributyl phosphotritioate), seemed to restore susceptibility, indicating a potential role of oxidases as a detoxifying enzyme resistance mechanism. Conclusions A better understanding of mosquito diversity related to host preference, biting activity and insecticide resistance status will facilitate the implementation of locally adapted vector control strategies.

Evolution of target and non-target based multiple herbicide resistance in a single Palmer amaranth (Amaranthus palmeri) population from Kansas

2020 ◽  
Vol 34 (3) ◽  
pp. 447-453
Author(s):  
Sushila Chaudhari ◽  
Vijay K. Varanasi ◽  
Sridevi Nakka ◽  
Prasanta C. Bhowmik ◽  
Curtis R. Thompson ◽  
...  
Keyword(s):  
Resistance Mechanism ◽  
Acetolactate Synthase ◽  
Palmer Amaranth ◽  
Target Site ◽  
Epsp Synthase ◽  
High Incidence ◽  
Evolution Of Resistance ◽  
Target Site Resistance ◽  
Herbicide Atrazine ◽  
Sites Of Action

AbstractThe evolution of resistance to multiple herbicides in Palmer amaranth is a major challenge for its management. In this study, a Palmer amaranth population from Hutchinson, Kansas (HMR), was characterized for resistance to inhibitors of photosystem II (PSII) (e.g., atrazine), acetolactate synthase (ALS) (e.g., chlorsulfuron), and EPSP synthase (EPSPS) (e.g., glyphosate), and this resistance was investigated. About 100 HMR plants were treated with field-recommended doses (1×) of atrazine, chlorsulfuron, and glyphosate, separately along with Hutchinson multiple-herbicide (atrazine, chlorsulfuron, and glyphosate)–susceptible (HMS) Palmer amaranth as control. The mechanism of resistance to these herbicides was investigated by sequencing or amplifying the psbA, ALS, and EPSPS genes, the molecular targets of atrazine, chlorsulfuron, and glyphosate, respectively. Fifty-two percent of plants survived a 1× (2,240 g ai ha−1) atrazine application with no known psbA gene mutation, indicating the predominance of a non–target site resistance mechanism to this herbicide. Forty-two percent of plants survived a 1× (18 g ai ha−1) dose of chlorsulfuron with proline197serine, proline197threonine, proline197alanine, and proline197asparagine, or tryptophan574leucine mutations in the ALS gene. About 40% of the plants survived a 1× (840 g ae ha−1) dose of glyphosate with no known mutations in the EPSPS gene. Quantitative PCR results revealed increased EPSPS copy number (50 to 140) as the mechanism of glyphosate resistance in the survivors. The most important finding of this study was the evolution of resistance to at least two sites of action (SOAs) (~50% of plants) and to all three herbicides due to target site as well as non–target site mechanisms. The high incidence of individual plants with resistance to multiple SOAs poses a challenge for effective management of this weed.

Comparative prevalences of Ascaris lumbricoides, Trichuris trichiura and hookworm infections and the prospects for combined control

Parasitology ◽  
1992 ◽  
Vol 105 (1) ◽  
pp. 151-157 ◽  
Author(s):  
M. Booth ◽  
D. A. P. Bundy
Keyword(s):  
Ascaris Lumbricoides ◽  
Control Strategies ◽  
Trichuris Trichiura ◽  
Hookworm Infection ◽  
Simultaneous Control ◽  
Precise Locality ◽  
Combined Control ◽  
Multiple Species ◽  
Epidemiological Characteristics ◽  
Hookworm Infections

Programmes to control Ascaris lumbricoides, Trichuris trichiura and hookworm infections have often been targeted at each infection separately, but the advent of benign and broad-spectrum anthelmintics suggests that combined control ma be feasible. The extent to which the infections co-occur in communities will determine the need for, and potential benefits of, such a combined approach. This paper examines the comparative distribution of the three geohelminths in different geographical areas and shows that A. lumbricoides and T. trichiura have closely related distributions, while hookworm infection is largely independent of the other two. These results indicate that many communities are at risk of disease from infection by more than one species of helminth. The similar distributions and epidemiological characteristics of A. lumbricoides and T. trichiura suggest that simultaneous control of these two parasites by the same strategy would be feasible and highly beneficial to communities. Multiple species control strategies which aim to control hookworm infection may require a more complicated protocol with more precise locality targeting.

The coevolution of host resistance and parasitoid virulence

Parasitology ◽  
1998 ◽  
Vol 116 (S1) ◽  
pp. S29-S45 ◽  
Author(s):  
A. R. Kraaijeveld ◽  
J. J. M. Van Alphen ◽  
H. C. J. Godfray
Keyword(s):  
Genetic Variation ◽  
Artificial Selection ◽  
Host Resistance ◽  
Genetic Basis ◽  
Isofemale Line ◽  
Fitness Costs ◽  
Geographical Patterns ◽  
Wide Range ◽  
Great Scope ◽  
Fertile Area

SummaryHost-parasitoid interactions are abundant in nature and offer great scope for the study of coevolution. A particularly fertile area is the interaction between internal feeding parasitoids and their hosts. Hosts have evolved a variety of means of combating parasitoids, in particular cellular encapsulation, while parasitoids have evolved a wide range of countermeasures. Studies of the evolution of host resistance and parasitoid virulence are reviewed, with an emphasis on work involvingDrosophilaand its parasitoids. Genetic variation in both traits has been demonstrated using isofemale line and artificial selection techniques. Recent studies have investigated the fitness costs of maintaining the ability to resist parasitoids, the comparative fitness of flies that have successfully defended themselves against parasitoids, and the degree to which resistance and virulence act against one or more species of host or parasitoid. A number of studies have examined geographical patterns, and sought to look for local adaptation; or have compared the traits across a range of species. Finally, the physiological and genetic basis of change in resistance and virulence is being investigated. While concentrating onDrosophila, the limited amount of work on different systems is reviewed, and other possible areas of coevolution in host-parasitoid interactions are briefly discussed.

scholarly journals Host resistance factor SLC11A1 restricts Salmonella growth through magnesium deprivation

Science ◽  
2019 ◽  
Vol 366 (6468) ◽  
pp. 995-999 ◽  
Author(s):  
Olivier Cunrath ◽  
Dirk Bumann
Keyword(s):  
Stress Responses ◽  
Host Resistance ◽  
Resistance Mechanism ◽  
Resistance Factor ◽  
Iron Availability ◽  
Transporter Gene ◽  
Divalent Metal Cations ◽  
Main Group Metal ◽  
Magnesium Transporter ◽  
Cell Patterns

The pleiotropic host resistance factor SLC11A1 (NRAMP1) defends against diverse intracellular pathogens in mammals by yet-unknown mechanisms. We compared Salmonella infection of coisogenic mice with different SLC11A1 alleles. SLC11A1 reduced Salmonella replication and triggered up-regulation of uptake systems for divalent metal cations but no other stress responses. SLC11A1 modestly diminished iron availability and acutely restricted Salmonella access to magnesium. Growth of Salmonella cells in the presence of SLC11A1 was highly heterogeneous and inversely correlated with expression of the crucial magnesium transporter gene mgtB. We observed superimposable single-cell patterns in mice lacking SLC11A1 when we restricted Salmonella access to magnesium by impairing its uptake. Together, these findings identify deprivation of the main group metal magnesium as the main resistance mechanism of SLC11A1 against Salmonella.

Experimental evolution of resistance against a competing fungus in Drosophila melanogaster

Oecologia ◽  
2009 ◽  
Vol 161 (4) ◽  
pp. 781-790 ◽  
Author(s):  
Susanne Wölfle ◽  
Monika Trienens ◽  
Marko Rohlfs
Keyword(s):  
Drosophila Melanogaster ◽  
Experimental Evolution ◽  
Evolution Of Resistance

The Application of the Elman Network on the Vehicle Handling Stability Control

2011 ◽  
Vol 199-200 ◽  
pp. 1457-1461 ◽  
Author(s):  
Si Jia Zhou ◽  
Jiang Qi Long ◽  
Ke Gang Zhao
Keyword(s):  
Driving Force ◽  
Control Method ◽  
Control Strategies ◽  
Stability Control ◽  
Vehicle Stability ◽  
Elman Network ◽  
Vehicle Handling ◽  
Combined Control ◽  
One Step ◽  
Tracking Response

In this paper, an expanded Elman network is applied to forecast the vehicle dynamic characteristic and a one step predictive control is also put into use to reinforce its handling stability. The combined control strategy is established based on the conception of the distribution of the driving force between the front and rear driving axles that can be easily achieved in an EV. Moreover, in this research, the distribution proportion of longitudinal driving force defining as a parameter is introduced and the control method of vehicle stability with the aid of the distribution proportion between axles is investigated．Simu1ations have been carried out and the results indicate that the proposed control strategies achieve smooth control effects and rapid target tracking response. This method can be easily applied to the vehicles that are driven by motors, and is capable of improving the lateral dynamic stability of vehicles in most conditions．

Culture of an organophosphorus-resistant strain ofBoophilus microplus(Can.) and an assessment of its resistance spectrum

1966 ◽  
Vol 56 (3) ◽  
pp. 389-405 ◽  
Author(s):  
R. D. Shaw
Keyword(s):  
Resistant Strain ◽  
Specific Resistance ◽  
Dominant Gene ◽  
Resistance Mechanism ◽  
Tick Control ◽  
Boophilus Microplus ◽  
Test Method ◽  
Organophosphorus Insecticides ◽  
Development Of Resistance ◽  
Low Order

Field observations indicated that a strain ofBoophilus microplus(Can.) in the Rockhampton area in Queensland was resistant to an organophosphorus insecticide, dioxathion (applied as Delnav), which had previously controlled it successfully. Ticks of this strain were despatched to the Cooper Technical Bureau in England, where a culture was established and maintained under selective pressure from dioxathion.The non-parasitic stages of the culture were maintained in an incubator under controlled conditions, and the parasitic stages on cattle in a tick rearing house designed for the purpose. Careful security precautions were taken to ensure that there was no dissemination of tick life outside the confines of the culture. The tick rearing house was provided with double doors, the inner ones of which were screened with copper gauze to prevent the possible transmission of anaplasmosis by biting flies.The activities of 23 insecticides against larvae of this strain and larvae of a strain ofB. microplussusceptible to organophosphorus poisoning were compared. The test method was an immersion technique, usually employing the insecticide in the form of an emulsion. Mortality was assessed 17 hours after treatment. These comparisons indicated that the strain was resistant to the organophosphorus insecticides carbophenothion (62 ×), dioxathion (25 ×), diazinon (15 ×), parathion (10×) and a carbamate, carbaryl (38×). It is suggested that these resistances may be due to a specific mechanism effective against these compounds.Nine other organophosphorus insecticides, one carbamate and rotenone were subject to low-order resistance by this strain significant at P ≤0·05. This was considered to be non-specific resistance.Dioxathion had been in use for tick control on the property concerned for four years before resistance was demonstrated. The property is situated in an area where the tick season lasts for ten months. In other parts of the world, dioxathion has been in use againstBoophilusticks for seven years without the development of resistance to it. The length of time resistance has taken to develop suggests that the resistance mechanism is not the expression of a single dominant gene, as has been demonstrated for dieldrin-resistance.The results suggest that resistance to one or more organophosphorus insecticides will not necessarily prevent the use of other members of this wide and diverse group for tick control. Several of the insecticides shown here to be subject to low-order non-specific resistance are known to be effective tick dips, and one of them, ethion, has been used with success against the resistant strain.An interesting corollary of the results was that the organophosphorus thions showed greater activity than their corresponding oxons against the susceptible strain.

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