THE DIFFERENTIAL RESPONSE OF STRAINS OF WILD CARROT TO 2,4-D AND RELATED HERBICIDES

1963 ◽  
Vol 43 (3) ◽  
pp. 255-262 ◽  
Author(s):  
C. W. Whitehead ◽  
C. M. Switzer
Keyword(s):  
Resistant Strain ◽  
Differential Response ◽  
Susceptible Strain ◽  
Severe Injury ◽  
Radicle Growth ◽  
Cotyledon Stage ◽  
Wild Carrot

Studies were conducted on the effect of 2,4-D and some related herbicides on a susceptible and a resistant strain of wild carrot (Daucus corota L.). When treated with 2,4-D, 4-(2,4-DB) or 4-(MCPB), plants of the susceptible strain died within a few weeks while those of die resistant strain recovered after showing severe injury symptoms. Treatment with 2,4,5-T or silvex killed both the susceptible and resistant strains.Seeds of the two strains, placed in various concentrations of 2,4-D, showed no differences in germination or radicle growth after 7 days. However, sprays of 2,4-D on seedlings just after emergence produced the differential response. Resistance appeared to develop between germination and the cotyledon stage of growth.There were no differences in the effect of 2,4-D on the respiration of whole tissue of the susceptible and resistant wild carrots.

scholarly journals Polygenic and single gene responses to selection for resistance to diazinon in Lucilia cuprina.

Genetics ◽  
1992 ◽  
Vol 130 (3) ◽  
pp. 613-620 ◽  
Author(s):  
J A McKenzie ◽  
A G Parker ◽  
J L Yen
Keyword(s):  
Resistant Strain ◽  
Single Gene ◽  
Natural Populations ◽  
Susceptible Strain ◽  
Selection Line ◽  
Base Population ◽  
Gene Response ◽  
Biochemical Profiles ◽  
Resistant Strains ◽  
Selection For

Abstract Following mutagenesis with ethyl methanesulfonate, selection in a susceptible strain with a concentration of the insecticide diazinon (0.0004%, w/v) above that required to kill 100% of the susceptible strain, the LC100 of that strain, resulted in a single gene response. The resultant four mutant resistant strains have equivalent physiological, genetical and biochemical profiles to a diazinon-resistant strain derived from a natural population and homozygous for the Rop-1 allele. Modification of the microsomal esterase E3 is responsible for resistance in each case. The Rop-1 locus maps approximately 4.4 map units proximal to bu on chromosome IV. Selection within the susceptible distribution, at a concentration of diazinon [0.0001% (w/v)] less than the LC100, resulted in a similar phenotypic response irrespective of whether the base population had been mutagenized. The responses were polygenically based, unique to each selection line and independent of Rop-1. The relevance of the results to selection for insecticide resistance in laboratory and natural populations is discussed.

scholarly journals In vitro anti-mycobacterial activity of (E)-N´-(monosubstituted-benzylidene) isonicotinohydrazide derivatives against isoniazid-resistant strains

2012 ◽  
Vol 4 (1) ◽  
pp. 13 ◽  
Author(s):  
Tatiane S. Coelho ◽  
Jessica B. Cantos ◽  
Marcelle L.F. Bispo ◽  
Raoni S.B. Gonçalves ◽  
Camilo H.S. Lima ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Resistant Strain ◽  
Mechanisms Of Action ◽  
Susceptible Strain ◽  
Clinical Isolates ◽  
Coding Region ◽  
Resistant Strains

A series of twenty-three <em>N-acylhydrazones</em> derived from isoniazid (INH 1-23) have been evaluated for their <em>in vitro</em> antibacterial activity against INH- susceptible strain of <em>M. tuberculosis</em> (RG500) and three INH-resistant clinical isolates (RG102, RG103 and RG113). In general, derivatives 4, 14, 15 and 16 (MIC=1.92, 1.96, 1.96 and 1.86 mM, respectively) showed relevant activities against RG500 strain, while the derivative 13 (MIC=0.98 mM) was more active than INH (MIC=1.14 mM). However, these derivatives were inactive against RGH102, which displays a mutation in the coding region of <em>inhA</em>. These results suggest that the activities of these compounds depend on the inhibition of this enzyme. However, the possibility of other mechanisms of action cannot be excluded, since compounds 2, 4, 6, 7, 12-17, 19, 21 and 23 showed good activities against <em>katG</em>-resistant strain RGH103, being more than 10-fold more active than INH.

Cellular basis for genetically determined enhanced resistance of certain mouse strains to listeriosis

1980 ◽  
Vol 28 (2) ◽  
pp. 381-386
Author(s):  
C Sadarangani ◽  
E Skamene ◽  
P A Kongshavn
Keyword(s):  
Bacterial Growth ◽  
Resistant Strain ◽  
Early Phase ◽  
Dextran Sulfate ◽  
Cellular Mechanism ◽  
Mononuclear Phagocytes ◽  
Susceptible Strain ◽  
Mouse Strains ◽  
Wide Range ◽  
Genetically Determined

The characteristics of the mononuclear phagocytes mediating resistance to infection with Listeria during the early phase (0 to 48 h) of the response have been investigated in genetically determined susceptible (A/J) and resistant (C57BL/6, B10.A/SgSn) strains of mice. Irradiation immediately before infection profoundly enhanced the bacterial growth in the resistant strain, while having no effect in the susceptible strain, over a wide range (3 x 10(3) to 10(5)) of infective doses. This effect of irradiation is demonstrable at low-dose radiation (200 roentgens) and can be reversed by repopulation with 20 x 10(6) syngeneic nucleated bone marrow cells. Administration of dextran sulfate 500 24 h before infection profoundly enhanced the bacterial growth in the susceptible strain, while having much less effect in the resistant strain. Thus, the genetic advantage of the resistant mouse strains to listerial infection, at least during the early phase of the response, appears to be due to a cellular mechanism that is highly radiosensitive and relatively insensitive to dextran sulfate 500. In the susceptible strain, the early protective cellular mechanism is radioresistant and highly dextran sulfate 500 sensitive.

Section 10. Pyrethroid resistance: resistance breaking pyrethroids

1993 ◽  
Vol 1 ◽  
pp. 83-96 ◽  
Author(s):  
Neil W. Forrester ◽  
Matthew Cahill ◽  
Lisa J. Bird ◽  
Jacquelyn K. Layland
Keyword(s):  
Resistant Strain ◽  
Pyrethroid Resistance ◽  
Residual Activity ◽  
Susceptible Strain ◽  
Piperonyl Butoxide ◽  
Monooxygenase System ◽  
Acid Moiety ◽  
Resistance Factors ◽  
Resistance Breaking ◽  
Alcohol Moiety

SummaryThe structural requirements for designing a resistance breaking pyrethroid to overcome oxidative metabolic pyrethroid resistance in Helicoverpa armigera were studied. A range of pyrethroid structures were tested on a well defined pure breeding pyrethroid resistant strain of H. armigera (homozygous for a metabolic detoxification mechanism fully suppressible by piperonyl butoxide, presumably via a microsomal monooxygenase system). Highest resistance factors were to the ester bonded phenoxybenzyl alcohol pyrethroids, particularly to those with an aromatic acid moiety. Changes to the alcohol moiety alone could overcome most, if not all, resistance. Simple benzyl alcohols were the most effective followed by cyclopentenolones and a methylated biphenyl alcohol. However, the benzylfurylmethyl alcohol (bioresmethrin) was not effective. The incorporation of a synergophore grouping into the alcohol moiety was fully effective for Scott's Py III (methylenedioxyphenyl) and prallethrin (propynyl) but only partially effective for tetramethrin (N-alkyl). Changes to the acid moiety had little effect except for the incorporation of a synergophore methylenedioxyphenyl grouping (Cheminova I) which was just as effective as for the same insertion in the alcohol moiety. The change to a central ether bond from the conventional ester bond lowered resistance. Reversion to an unsubstituted alpha carbon analogue from the conventional alpha cyano group also lowered resistance.Piperonyl butoxide (Pbo) had little effect on pyrethroid toxicity in the susceptible strain except for the single isomers deltamethrin and esfenvalerate. However, it was more than fully effective in overcoming resistance and actually reduced resistance factors to significantly below one in the resistant strain. This indicated the possibility that Pbo could be acting both as a classical monooxygenase inhibitor and a preferential penetration synergist in resistant larvae.Partial or full resolution of racemic mixtures had minimal impact on increasing toxicity in the susceptible strain. However, partially or fully resolved isomers were clearly much more toxic on resistant strains, indicating a possible blocking effect of the inactive isomers during the toxication process with the higher pyrethroid doses applied to resistant larvae. Cis isomers had only slightly higher resistance factors than trans isomers.Seven fully effective resistance breaking pyrethroids were identified in this study and one of these (the simple benzyl alcohol, Series Two) was shown to be equally effective on both adults and larvae of H. armigera. It was also shown to work equally well on laboratory or field material and gave results similar to a pyrethroid/Pbo combination. However, none of the resistance breakers identified so far are able to satisfy all of the requirements necessary for an ideal resistance breaking pyrethroid (i.e. good resistance breaking activity at low rates, photostability, residual activity similar to current pyrethroids and safety to mammals). Factors acting against the possible commercialization of successful resistance breaking compounds are discussed.

scholarly journals Profiling theAspergillus fumigatusProteome in Response to Caspofungin

2010 ◽  
Vol 55 (1) ◽  
pp. 146-154 ◽  
Author(s):  
Steven E. Cagas ◽  
Mohit Raja Jain ◽  
Hong Li ◽  
David S. Perlin
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Resistant Strain ◽  
Drug Action ◽  
Susceptible Strain ◽  
Cell Fractionation ◽  
Wild Type ◽  
Subcellular Compartment ◽  
Minimum Effective Concentration ◽  
Potential Biomarkers

ABSTRACTThe proteomic response ofAspergillus fumigatusto caspofungin was evaluated by gel-free isobaric tagging for relative and absolute quantitation (iTRAQ) as a means to determine potential biomarkers of drug action. A cell fractionation approach yielding 4 subcellular compartment fractions was used to enhance the resolution of proteins for proteomic analysis. Using iTRAQ, a total of 471 unique proteins were identified in soluble and cell wall/plasma membrane fractions at 24 and 48 h of growth in rich media in a wild-type drug-susceptible strain. A total of 122 proteins showed at least a 2-fold change in relative abundance following exposure to caspofungin (CSF) at just below the minimum effective concentration (0.12 μg/ml). The largest changes were seen in the mitochondrial hypoxia response domain protein (AFUA_1G12250), the level of which decreased >16-fold in the secreted fraction, and ChiA1, the level of which decreased 12.1-fold in the cell wall/plasma membrane fraction. The level of the major allergen and cytotoxin AspF1 was also shown to decrease by 12.1-fold upon the addition of drug. A subsequent iTRAQ analysis of an echinocandin-resistant strain (fks1-S678P) was used to validate proteins specific to drug action. A total of 103 proteins in the 2 fractions tested by iTRAQ were differentially expressed in the wild-type susceptible strain but not significantly changed in the resistant strain. Of these potential biomarkers, 11 had levels that changed at least 12-fold. Microarray analysis of the susceptible strain was performed to evaluate the correlation between proteomics and genomics, with a total of 117 genes found to be changing at least 2-fold. Of these, a total of 22 proteins with significant changes identified by iTRAQ also showed significant gene expression level changes by microarray. Overall, these data have the potential to identify biomarkers that assess the relative efficacy of echinocandin drug therapy.

scholarly journals An Extracytoplasmic Function Sigma Factor Controls β-Lactamase Gene Expression in Bacillus anthracis and Other Bacillus cereus Group Species

2009 ◽  
Vol 191 (21) ◽  
pp. 6683-6693 ◽  
Author(s):  
Cana L. Ross ◽  
Kerrie S. Thomason ◽  
Theresa M. Koehler
Keyword(s):  
Bacillus Cereus ◽  
Bacillus Anthracis ◽  
Resistant Strain ◽  
Sigma Factor ◽  
Susceptible Strain ◽  
Closely Related Species ◽  
Naturally Occurring ◽  
Lactamase Gene ◽  
Extracytoplasmic Function Sigma Factor ◽  
Group Species

ABSTRACT The susceptibility of most Bacillus anthracis strains to β-lactam antibiotics is intriguing considering that the closely related species Bacillus cereus and Bacillus thuringiensis typically produce β-lactamases and the B. anthracis genome harbors two β-lactamase genes, bla1 and bla2. We show that β-lactamase activity associated with B. anthracis is affected by two genes, sigP (BA2502) and rsiP (BA2503), predicted to encode an extracytoplasmic function sigma factor and an anti-sigma factor, respectively. Deletion of the sigP-rsiP locus abolished β-lactamase activity in a naturally occurring penicillin-resistant strain and had no effect on β-lactamase activity in a prototypical penicillin-susceptible strain. Complementation with sigP and rsiP from the penicillin-resistant strain, but not with sigP and rsiP from the penicillin-susceptible strain, conferred constitutive β-lactamase activity in both mutants. These results are attributed to a nucleotide deletion near the 5′ end of rsiP in the penicillin-resistant strain that is predicted to result in a nonfunctional protein. B. cereus and B. thuringiensis sigP and rsiP homologues are required for inducible penicillin resistance in these species. Expression of the B. cereus or B. thuringiensis sigP and rsiP genes in a B. anthracis sigP-rsiP-null mutant confers inducible production of β-lactamase activity, suggesting that while B. anthracis contains the genes necessary for sensing β-lactam antibiotics, the B. anthracis sigP and rsiP gene products are not sufficient for bla induction.

Inheritance of DDT dehydrochlorination and of a mechanism restricting uptake of DDT in the mosquito Aedes aegypti

Genome ◽  
1987 ◽  
Vol 29 (2) ◽  
pp. 357-360 ◽  
Author(s):  
H. R. Rathor ◽  
R. J. Wood
Keyword(s):  
Resistant Strain ◽  
Parental Strain ◽  
Susceptible Strain ◽  
In Vitro Assays ◽  
Pesticide Resistance ◽  
Life Stages ◽  
Ddt Resistance ◽  
Clear Relation

Crosses and backcrosses were made between the T8 dichlorodiphenyltrichloroethane (DDT) resistant strain and NS susceptible strain. Each generation was tested for resistance, for internal levels of DDT and dichlorodiphenyldichloroethylene (DDE) (thus "DDT uptake" (DDT + DDE) and percentage DDT dehydrochlorination in vivo), and for DDT dehydrochlorination in vitro, both at the larval and adult stages. The patterns of inheritance of uptake and dehydrochlorination were different. At both life stages, dehydrochlorination (both in vivo and in vitro) was intermediate in the F1, reverting to or exceeding the parental strains in the backcrosses except in adult tests on the backcrosses to the susceptible strain where it remained intermediate. Uptake increased very substantially in the F1 compared with either parental strain and was also high in the backcrosses. This was interpreted as being due to the disruption of an uptake-restricting mechanism in T8 brought about by outcrossing. Larval resistance in the various generations was correlated significantly with dehydrochlorination, both in vivo and in vitro but bore no clear relation to uptake. Resistance in adults was found not to be correlated significantly with either. Key words: DDT dehydrochlorination, pesticide resistance, DDT uptake, DDT resistance, dehydrochlorination in vivo and in vitro assays.

Commensal Escherichia coli of healthy humans: a reservoir for antibiotic-resistance determinants

2010 ◽  
Vol 59 (11) ◽  
pp. 1331-1339 ◽  
Author(s):  
Jannine K. Bailey ◽  
Jeremy L. Pinyon ◽  
Sashindran Anantham ◽  
Ruth M. Hall
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Resistant Strain ◽  
Healthy Adults ◽  
Susceptible Strain ◽  
E Coli ◽  
Resistance Determinants ◽  
Healthy Humans ◽  
Depth Analysis

This study examined in detail the population structure of Escherichia coli from healthy adults with respect to the prevalence of antibiotic resistance and specific resistance determinants. E. coli isolated from the faeces of 20 healthy adults not recently exposed to antibiotics was tested for resistance to ten antibiotics and for carriage of integrons and resistance determinants using PCR. Strain diversity was assessed using biochemical and molecular criteria. E. coli was present in 19 subjects at levels ranging from 2.0×104 to 1.7×108 c.f.u. (g faeces)−1. Strains resistant to one to six antibiotics were found at high levels (>30 %) in only ten individuals, but at significant levels (>0.5 %) in 14. Resistant isolates with the same phenotype from the same individual were indistinguishable, but more than one susceptible strain was sometimes found. Overall, individuals harboured one to four E. coli strains, although in 17 samples one strain was dominant (>70 % of isolates). Eighteen strains resistant to ampicillin, sulfamethoxazole, tetracycline and trimethoprim in 15 different combinations were observed. One resistant strain was carried by two unrelated individuals and a susceptible strain was shared by two cohabiting subjects. Two minority strains were derivatives of a more abundant resistant strain in the same sample, showing that continuous evolution is occurring in vivo. The trimethoprim-resistance genes dfrA1, dfrA5, dfrA7, dfrA12 or dfrA17 were in cassettes in a class 1 or class 2 integron. Ampicillin resistance was conferred by the bla TEM gene, sulfamethoxazole resistance by sul1, sul2 or sul3 and tetracycline resistance by tetA(A) or tetA(B). Chloramphenicol resistance (cmlA1 gene) was detected only once. Phylogenetic groups A and B2 were more common than B1 and D. Commensal E. coli of healthy humans represent an important reservoir for numerous antibiotic-resistance genes in many combinations. However, measuring the true extent of resistance carriage in commensal E. coli requires in-depth analysis.

scholarly journals Inhibiting bacterial cooperation is an evolutionarily robust anti-biofilm strategy

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Lise Dieltjens ◽  
Kenny Appermans ◽  
Maries Lissens ◽  
Bram Lories ◽  
Wook Kim ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Resistant Strain ◽  
Extracellular Polymeric Substances ◽  
Social Evolution ◽  
Cell Attachment ◽  
Susceptible Strain ◽  
Evolution Theory ◽  
Viable Solution ◽  
Evolution Of Resistance ◽  
Inhibitor Treatment

AbstractBacteria commonly form dense biofilms encased in extracellular polymeric substances (EPS). Biofilms are often extremely tolerant to antimicrobials but their reliance on shared EPS may also be a weakness as social evolution theory predicts that inhibiting shared traits can select against resistance. Here we show that EPS of Salmonella biofilms is a cooperative trait whose benefit is shared among cells, and that EPS inhibition reduces both cell attachment and antimicrobial tolerance. We then compare an EPS inhibitor to conventional antimicrobials in an evolutionary experiment. While resistance against conventional antimicrobials rapidly evolves, we see no evolution of resistance to EPS inhibition. We further show that a resistant strain is outcompeted by a susceptible strain under EPS inhibitor treatment, explaining why resistance does not evolve. Our work suggests that targeting cooperative traits is a viable solution to the problem of antimicrobial resistance.

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