Selection of a BHC-resistant Strain of Drosophila melanogaster Mg

1953 ◽  
Vol 44 (2) ◽  
pp. 395-400 ◽  
Author(s):  
F. J. Oppenoorth ◽  
D. Dresden
Keyword(s):  
Drosophila Melanogaster ◽  
Resistant Strain ◽  
Parent Strain ◽  
Laboratory Strain ◽  
Contact Method ◽  
Resistant Parent ◽  
Reciprocal Crosses ◽  
Wild Strains ◽  
Resistant Strains ◽  
Selection Of

Two wild strains of Drosophila and one laboratory strain were selected for resistance to γBHC by a contact method. From each of these three strains equally resistant strains developed in about the same time. They did not become more resistant after prolonged selection. The resistance obtained was further investigated in one of the strains.There was no evidence of any specificity: the susceptibility of the resistant insects to DDT and “Thanite” also appeared to be less than that of the original strains.Although the strains were selected by a contact method they also showed decreased susceptiblity when the poison was applied to the skin and when it was injected. From the reciprocal crosses F1's were obtained the susceptibilities of which were practically the same and differed little from that of the resistant parent strain. It follows that resistance does not depend on cytoplasmatic heredity and that it is incompletely dominant.

α-AMANITIN RESISTANCE IN THREE WILD STRAINS OF DROSOPHILA MELANOGASTER

1982 ◽  
Vol 24 (2) ◽  
pp. 151-162 ◽  
Author(s):  
J. P. Phillips ◽  
J. Willms ◽  
A. Pitt
Keyword(s):  
Drosophila Melanogaster ◽  
Rna Polymerase ◽  
Reference Strain ◽  
Chromosome 3 ◽  
Fungal Toxin ◽  
Wild Strains ◽  
Resistant Strains ◽  
Dominant Genes

Three wild strains of D. melanogaster have been identified which are resistant to normally lethal levels of the fungal toxin, α-amanitin. Dietary LD50s for Oregon-R, the reference strain, and Ama-KTT, Ama-MI and Ama-KLM, the resistant strains, are 1.2, 35, 30 and 10 μg α-amanitin/vial, respectively. Resistance in all three strains is a digenic trait, being determined by two independently acting dominant genes, Ama-1, Ama-2, either of which is sufficient to confer resistance and which are located at approximately 18.8 and 100.7, respectively, on chromosome 3. Resistance to α-amanitin in all three strains is apparently not mediated by modification of RNA polymerase form II nor by failure of toxin transport or by toxin inactivation.

The development of drug-resistant strains of Eimeria maxima in the laboratory

Parasitology ◽  
1975 ◽  
Vol 71 (1) ◽  
pp. 153-165 ◽  
Author(s):  
C. C. Norton ◽  
L. P. Joyner
Keyword(s):  
Drug Administration ◽  
Resistant Strain ◽  
Parent Strain ◽  
Drug Resistant ◽  
Development Of Resistance ◽  
Eimeria Maxima ◽  
Resistant Strains ◽  
Drug Dependent ◽  
Drug Resistant Strains

The development of strains of Eimeria maxima resistant to buquinolate, methyl benzoquate, clopidol, sulphaquinoxaline and robenidine is described. It was not possible to standardize a schedule of inoculations and drug administration, which would enable the development of resistance to the different drugs to be compared directly. Resistance developed most readily to the quinolones. One robenidine-resistant strain proved to be drug-dependent. Dinitolmide showed unusual effects upon sporogony and three attempts to develop resistance against this activity failed. Chicks previously immunized with the parent strain were completely protected against infection with the drug-resistant strains.

scholarly journals Mutations of the Helicobacter pyloriGenes rdxA and pbp1 Cause Resistance against Metronidazole and Amoxicillin

2001 ◽  
Vol 45 (3) ◽  
pp. 962-965 ◽  
Author(s):  
Ralf Paul ◽  
Stefan Postius ◽  
Klaus Melchers ◽  
Klaus P. Schäfer
Keyword(s):  
Helicobacter Pylori ◽  
Resistance Genes ◽  
Resistant Strain ◽  
Parent Strain ◽  
Metronidazole Resistance ◽  
Pcr Products ◽  
Resistant Strains ◽  
H Pylori

ABSTRACT To investigate amoxicillin and metronidazole resistance ofHelicobacter pylori, we compared putative resistance genes between resistant strains obtained in vitro and their sensitive parent strain. All metronidazole-resistant strains hadrdxA mutations, and an amoxicillin-resistant strain hadpbp1 and pbp2 mutations. By transforming PCR products of these mutated genes into antibiotic-sensitive strains, we showed that rdxA null mutations were sufficient for metronidazole resistance, while pbp1mutations contributed to amoxicillin resistance of H. pylori.

Free-living and symbiotic characteristics of chlorate resistant mutants of Rhizobium japonicum

1980 ◽  
Vol 26 (3) ◽  
pp. 338-342 ◽  
Author(s):  
Laura de Vasconcelos ◽  
Llonas Miller ◽  
Carlos A. Neyra
Keyword(s):  
Nitrate Reductase ◽  
Parent Strain ◽  
Rhizobium Japonicum ◽  
Free Living ◽  
Chlorate Resistance ◽  
Soybean Seedlings ◽  
Resistant Strains ◽  
Resistant Mutants ◽  
Selection Of ◽  
Better Than

This work investigated the usefulness of chlorate resistance as a method for the selection of nitrate reductase negative (NR−) strains from Rhizobium japonicum (61A76) and evaluated the symbiotic characteristics of these strains. Chlorate resistant strains were selected from populations seeded on CS 7 agar containing 10 or 20 mM KClO3 and incubated in 2% air – 98% N2–CO2 (95:5).Over 200 resistant strains were isolated, 58% of which lacked the dissimilatory nitrate reductase. In 12 selected isolates, some strains had also lost the assimilatory nitrate reductase, but all retained hydrogenase activity.Chlorate resistant strains inoculated to soybean seedlings were equal to or better than the parent strain in terms of nodule mass and acetylene reduction. Those strains lacking both assimilatory and dissimilatory nitrate reductase showed the best symbiotic characteristics, suggesting that chlorate resistance in R. japonicum could be a useful method for the selection of strains with superior nitrogen-fixing characteristics.

The development of resistance to glycarbylamide and 2-chloro-4-nitrobenzamide in Eimeria tenella in chicks

Parasitology ◽  
1966 ◽  
Vol 56 (1) ◽  
pp. 25-37 ◽  
Author(s):  
S. J. Ball
Keyword(s):  
Drug Resistance ◽  
Resistant Strain ◽  
Parent Strain ◽  
Technical Assistance ◽  
Eimeria Tenella ◽  
Single Test ◽  
Normal Parent ◽  
Twofold Increase ◽  
Development Of Resistance ◽  
Resistant Strains

A twofold increase in resistance to glycarbylamide was induced in a strain of Eimeria tenella in chicks. This strain remained susceptible to amprolium, nicarbazin, nitrofurazone, zoalene, 3,5-dinitrobenzamide, 2-chloro-4-nitrobenzamide (M & B 5921) and spiramycin.At least an eightfold resistance to 2-chloro-4-nitrobenzamide (M & B 5921) was developed in another strain of E. tenella. This strain was also resistant to nitrofurazone, zoalene and 3,5-dinitrobenzamide, but not to glycarbylamide, amprolium, nicarbazin and spiramycin.A single test showed no transfer of drug-resistance when the two resistant strains were given simultaneously to the same birds.When a small number of parasites of a glycarbylamide-resistant strain of E. tenella was introduced into a larger inoculum of the normal parent strain, the resistant individuals appeared to diminish in number during passages through untreated chicks.I wish to thank Mrs B. M. Mitchell, Miss C. A. Hitchcock and Miss J. Watkins for technical assistance at various stages of the work.

Development of ertapenem resistance in a patient with mediastinitis caused by Klebsiella pneumoniae producing an extended-spectrum β-lactamase

2010 ◽  
Vol 59 (1) ◽  
pp. 115-119 ◽  
Author(s):  
David Skurnik ◽  
Sigismond Lasocki ◽  
Sylvie Bremont ◽  
Claudette Muller-Serieys ◽  
Marie Dominique Kitzis ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Resistant Strain ◽  
Outer Membrane Proteins ◽  
Carbapenem Resistance ◽  
Carbapenem Resistant ◽  
Extended Spectrum ◽  
Severe Infections ◽  
Resistant Strains ◽  
Selection Of

The aim was to study the clinical and microbiological features associated with a carbapenem-resistant Klebsiella pneumoniae isolate that had been selected in vivo by an ertapenem-containing regimen in a patient with mediastinitis despite high blood and mediastinal levels of ertapenem. Carbapenem resistance was characterized by conjugation, PCR, DNA sequencing and analysis of outer-membrane proteins. The isolates susceptible and resistant to the carbapenems were compared by ribotyping and PFGE. Resistance to all available β-lactams was most probably due to combined production of extended-spectrum β-lactamase (ESBL) CTX-M-15 and loss of OmpK36 porin. The results of ribotyping and PFGE suggest that the carbapenem-resistant strain was a derivative of the original mediastinal isolate rather than a superinfecting isolate. This observation stresses the risk of selection of pan-penem resistant strains of enterobacteria when ertapenem is used for the treatment of severe infections due to ESBL-producing enterobacteria.

Microencapsulation: A Prospective to Protect Probiotics

2020 ◽  
Vol 16 (6) ◽  
pp. 891-899 ◽  
Author(s):  
Wissam Zam
Keyword(s):  
Gastrointestinal Tract ◽  
Food Industry ◽  
Health Benefits ◽  
Probiotic Bacteria ◽  
Bacterial Cells ◽  
Beneficial Effects ◽  
Host Health ◽  
Resistant Strains ◽  
Selection Of

Probiotics are viable microorganisms widely used for their claimed beneficial effects on the host health. A wide number of researchers proved that the intake of probiotic bacteria has numerous health benefits which created a big market of probiotic foods worldwide. The biggest challenge in the development of these products is to maintain the viability of bacterial cells during the storage of the product as well as throughout the gastrointestinal tract transit after consumption, so that the claimed health benefits can be delivered to the consumer. Different approaches have been proposed for increasing the resistance of these sensitive microorganisms, including the selection of resistant strains, incorporation of micronutrients, and most recently the use of microencapsulation techniques. Microencapsulation has resulted in enhancing the viability of these microorganisms which allows its wide use in the food industry. In this review, the most common techniques used for microencapsulation of probiotics will be presented, as well as the most usual microcapsule shell materials.

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.

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