scholarly journals Influence of the population genetic background on the persistency of a recessive lethal in Drosophila melanogaster

1971 ◽  
Vol 17 (2) ◽  
pp. 103-111 ◽  
Author(s):  
Karl H. Ytterborn
Keyword(s):  
Drosophila Melanogaster ◽  
Inbred Strain ◽  
Genetic Background ◽  
Type Strain ◽  
Detrimental Effect ◽  
Wild Type Strain ◽  
Gene Pools ◽  
Wild Type ◽  
Original Population ◽  
Heterozygous Carriers

SUMMARYIn a population of Drosophila melanogaster started from an inbred wild-type strain the recessive second chromosome lethal studied had shown overdominance which after many generations was lost. In the present study the persistence of this lethal was tested in three series each of five populations. The genetic backgrounds of the different series of populations were obtained from (a) the inbred strain, (b) the above original population after the overdominance had been lost, and (c) a population started from the same inbred strain and where another lethal had shown overdominance which subsequently had been lost. The lethal was overdominant in the (a) background but detrimental to the heterozygous carriers on the other backgrounds. The detrimental effect of the lethal was stronger in the (b) background than in the (c) background. The varying behaviour of the lethal is possibly due to different adapted background genotypes and/or different degrees of heterozygosity of the gene pools.

Isolation of telomere DNA from Neurospora crassa

1987 ◽  
Vol 7 (9) ◽  
pp. 3168-3177
Author(s):  
M G Schechtman
Keyword(s):  
Linkage Group ◽  
Neurospora Crassa ◽  
Genetic Background ◽  
Type Strain ◽  
Wild Type Strain ◽  
The Other ◽  
Wild Type ◽  
Oak Ridge ◽  
Entire Chromosome ◽  
Different Genetic Background

The most distal known gene on Neurospora crassa linkage group VR, his-6, was cloned. A genomic walk resulted in isolation of the telomere at VR. It was obtained from a library in which the endmost nucleotides of the chromosome had not been removed by nuclease treatment before being cloned, and mapping indicates that the entire chromosome end has probably been cloned. Sequences homologous to the terminal 2.5 kilobases of DNA from VR from these Oak Ridge N. crassa strains are found at other sites in the genome. To characterize these sites, I crossed an Oak Ridge-derived his-6 strain with a wild-type strain of different genetic background (Mauriceville) and characterized the hybridization patterns seen in the progeny. It appears that the sequences homologous to the VR terminus are found at genetically different sites in the two parental strains, and no hybridization to the VR telomere from Mauriceville was detected. The other genomic copies identified in the Oak Ridge parent were not telomeres. I suggest that any repeating sequence blocks found immediately adjacent to the VR terminus in Oak Ridge strains must be small and that the repeating element identified in that background may be an N. crassa transposable element integrated near the the chromosome end at VR.

scholarly journals Mapping the Role of AcrAB-TolC Efflux Pumps in the Evolution of Antibiotic Resistance Reveals Near-MIC Treatments Facilitate Resistance Acquisition

2020 ◽  
Author(s):  
Ariel M. Langevin ◽  
Imane El Meouche ◽  
Mary J. Dunlop
Keyword(s):  
Antibiotic Resistance ◽  
Genetic Background ◽  
Parent Strain ◽  
Type Strain ◽  
Wild Type Strain ◽  
Efflux Pumps ◽  
Wild Type ◽  
Antibiotic Concentration ◽  
Drug Concentrations ◽  
Evolution Of Resistance

ABSTRACTAntibiotic resistance has become a major public health concern as bacteria evolve to evade drugs, leading to recurring infections and a decrease in antibiotic efficacy. Systematic efforts have revealed mechanisms involved in resistance; yet, in many cases, how these specific mechanisms accelerate or slow the evolution of resistance remains unclear. Here, we conducted a systematic study of the impact of the AcrAB-TolC efflux pump on the evolution of antibiotic resistance. We mapped how population growth rate and resistance change over time as a function of both the antibiotic concentration and the parent strain’s genetic background. We compared the wild type strain to a strain overexpressing AcrAB-TolC pumps and a strain lacking functional pumps. In all cases, resistance emerged when cultures were treated with chloramphenicol concentrations near the MIC of their respective parent strain. The genetic background of the parent strain also influenced resistance acquisition. The wild type strain evolved resistance within 24 h through mutations in the acrAB operon and its associated regulators. Meanwhile, the strain overexpressing AcrAB-TolC evolved resistance more slowly than the wild type strain; this strain achieved resistance in part through point mutations in acrB and the acrAB promoter. Surprisingly, the strain without functional AcrAB-TolC efflux pumps still gained resistance, which it achieved through upregulation of redundant efflux pumps. Overall, our results suggest that treatment conditions just above the MIC pose the largest risk for the evolution of resistance and that AcrAB-TolC efflux pumps impact the pathway by which chloramphenicol resistance is achieved.IMPORTANCECombatting the rise of antibiotic resistance is a significant challenge. Efflux pumps are an important contributor to drug resistance; they exist across many cell types and can export numerous classes of antibiotics. Cells can regulate pump expression to maintain low intracellular drug concentrations. Here, we explored how resistance emerged depending on the antibiotic concentration, as well as the presence of efflux pumps and their regulators. We found that treatments near antibiotic concentrations that inhibit the parent strain’s growth were most likely to promote resistance. While wild type, pump overexpression, and pump knock out strains were all able to evolve resistance, they differed in the absolute level of resistance evolved, the speed at which they achieved resistance, and the genetic pathways involved. These results indicate that specific treatment regimens may be especially problematic for the evolution of resistance and that the strain background can influence how resistance is achieved.

scholarly journals Reproduction and endoreduplication in Drosophila melanogaster Meig. when influenced by lead nitrate

2020 ◽  
Vol 27 ◽  
pp. 303-308
Author(s):  
V. Yu. Strashnyuk ◽  
O. V. Taglina
Keyword(s):  
Drosophila Melanogaster ◽  
Salivary Glands ◽  
Type Strain ◽  
Wild Type Strain ◽  
Lead Nitrate ◽  
Wild Type ◽  
Reproductive Ability ◽  
Dose Dependent Decrease ◽  
Drosophila Cells ◽  
Dose Dependent

Aim. The purpose of investigation was to study the reproductive ability and polyteny degree of chromosomes in Drosophila melanogaster Meig. under the influence of various concentrations of lead nitrate. Methods. Canton-S wild-type strain was used as the material. Flies developed on standard sugar-yeast medium, to which in the experiment lead nitrate was added in concentrations of 0.1, 1, and 10 mg/ml. The reproductive ability of the strain was evaluated by the number of adult offspring. The polyteny degree of chromosomes was studied on squashed preparations of larva salivary glands stained with acetoorsein by cytomorphometry. The preparations were obtained at late 3rd instar. Results. The number of adult offsprings decreased when lead nitrate was added to the nutrient medium: at a concentration of 0.1 mg/ml – by 22.8 %, at 1 mg/ml – by 38.9 %. A concentration of 10 mg/ml was lethal. Males showed greater sensitivity to the drug compared to females. The degree of polyteny of chromosomes in the salivary glands of larvae decreased on average by 5.0–6.5 %. Conclusions. Lead nitrate causes a significant, dose-dependent decrease in the reproductive ability of fruit flies and has a toxic effect on Drosophila cells, inhibiting the process of endoreduplication. Keywords: Drosophila melanogaster Meig., heavy metals, fecundity, giant chromosomes, polyteny.

Notizen: A New Mutant Affecting Aldehyde Oxidase in Drosophila melanogaster

1979 ◽  
Vol 34 (3-4) ◽  
pp. 304-305 ◽  
Author(s):  
Michael M. Bentley ◽  
John H. Williamson
Keyword(s):  
Drosophila Melanogaster ◽  
Type Strain ◽  
Wild Type Strain ◽  
Aldehyde Oxidase ◽  
Heat Stability ◽  
Chromosome 2 ◽  
Control Strain ◽  
Wild Type ◽  
Mutant Stock ◽  
Wild Type Control

Abstract A new locus, Aldox-2, which affects the activity and heat stability of aldehyde oxidase in D. melanogaster is described. The Aldox-2 locus is localized to map position 86 on chromosome 2, between c and px. Aldehyde oxidase activity in Aldox-2 homozygotes is approximately 25 - 30% that of the Oregon-R wild-type control strain. The enzyme from the mutant stock is much more heat labile than is the enzyme from the wild-type strain. Both the activity and heat phenotypes are completely recessive.

scholarly journals Mapping the Role of AcrAB-TolC Efflux Pumps in the Evolution of Antibiotic Resistance Reveals Near-MIC Treatments Facilitate Resistance Acquisition

mSphere ◽  
2020 ◽  
Vol 5 (6) ◽  
Author(s):  
Ariel M. Langevin ◽  
Imane El Meouche ◽  
Mary J. Dunlop
Keyword(s):  
Antibiotic Resistance ◽  
Genetic Background ◽  
Parent Strain ◽  
Type Strain ◽  
Wild Type Strain ◽  
Efflux Pumps ◽  
Wild Type ◽  
Antibiotic Concentration ◽  
Drug Concentrations ◽  
Evolution Of Resistance

ABSTRACT Antibiotic resistance has become a major public health concern as bacteria evolve to evade drugs, leading to recurring infections and a decrease in antibiotic efficacy. Systematic efforts have revealed mechanisms involved in resistance. Yet, in many cases, how these specific mechanisms accelerate or slow the evolution of resistance remains unclear. Here, we conducted a systematic study of the impact of the AcrAB-TolC efflux pump on the evolution of antibiotic resistance. We mapped how population growth rate and resistance change over time as a function of both the antibiotic concentration and the parent strain’s genetic background. We compared the wild-type strain to a strain overexpressing AcrAB-TolC pumps and a strain lacking functional pumps. In all cases, resistance emerged when cultures were treated with chloramphenicol concentrations near the MIC of their respective parent strain. The genetic background of the parent strain also influenced resistance acquisition. The wild-type strain evolved resistance within 24 h through mutations in the acrAB operon and its associated regulators. Meanwhile, the strain overexpressing AcrAB-TolC evolved resistance more slowly than the wild-type strain; this strain achieved resistance in part through point mutations in acrB and the acrAB promoter. Surprisingly, the strain without functional AcrAB-TolC efflux pumps still gained resistance, which it achieved through upregulation of redundant efflux pumps. Overall, our results suggest that treatment conditions just above the MIC pose the largest risk for the evolution of resistance and that AcrAB-TolC efflux pumps impact the pathway by which chloramphenicol resistance is achieved. IMPORTANCE Combatting the rise of antibiotic resistance is a significant challenge. Efflux pumps are an important contributor to drug resistance; they exist across many cell types and can export numerous classes of antibiotics. Cells can regulate pump expression to maintain low intracellular drug concentrations. Here, we explored how resistance emerged depending on the antibiotic concentration, as well as the presence of efflux pumps and their regulators. We found that treatments near antibiotic concentrations that inhibit the parent strain’s growth were most likely to promote resistance. While wild-type, pump overexpression, and pump knockout strains were all able to evolve resistance, they differed in the absolute level of resistance evolved, the speed at which they achieved resistance, and the genetic pathways involved. These results indicate that specific treatment regimens may be especially problematic for the evolution of resistance and that the strain background can influence how resistance is achieved.

scholarly journals Melatonin influence on Drosophila melanogaster life span at different light regimes

2008 ◽  
Vol 6 (3) ◽  
pp. 24-32
Author(s):  
Aleksey A Moskalev ◽  
Anna V Krementsova ◽  
Olga A Malysheva
Keyword(s):  
Dna Repair ◽  
Drosophila Melanogaster ◽  
Data Analysis ◽  
Life Span ◽  
Type Strain ◽  
Wild Type Strain ◽  
Combined Effects ◽  
Wild Type ◽  
Maximum Life Span ◽  
Light Regimes

It was investigated the combined effects of different light regimes (round-the-clock lighting or darkening) and antioxidant melatonin on Drosophila melanogaster life span of wild type strain Canton-S,mutant strain with defect of red-ox system (Sod) and mu tant strain with disturbance of excision DNA repair (mus210). It was revealed, that maintenance of Drosophila imago at round-the-clock lighting leads to decrease of mean and/or maximum life span with compare to being at darkening. Adding of melatonin to Drosophila meal induces the geroprotector effects, mainly, in dark conditions. The effects mentioned above were most expressed in strain with mutation of Sod. All effects have revealed in both sexes. The data analysis has shown that mechanisms of different light regimes and melatonin influ ence on life span are rather different.

scholarly journals Isolation of telomere DNA from Neurospora crassa.

1987 ◽  
Vol 7 (9) ◽  
pp. 3168-3177 ◽  
Author(s):  
M G Schechtman
Keyword(s):  
Linkage Group ◽  
Neurospora Crassa ◽  
Genetic Background ◽  
Type Strain ◽  
Wild Type Strain ◽  
The Other ◽  
Wild Type ◽  
Oak Ridge ◽  
Entire Chromosome ◽  
Different Genetic Background

The most distal known gene on Neurospora crassa linkage group VR, his-6, was cloned. A genomic walk resulted in isolation of the telomere at VR. It was obtained from a library in which the endmost nucleotides of the chromosome had not been removed by nuclease treatment before being cloned, and mapping indicates that the entire chromosome end has probably been cloned. Sequences homologous to the terminal 2.5 kilobases of DNA from VR from these Oak Ridge N. crassa strains are found at other sites in the genome. To characterize these sites, I crossed an Oak Ridge-derived his-6 strain with a wild-type strain of different genetic background (Mauriceville) and characterized the hybridization patterns seen in the progeny. It appears that the sequences homologous to the VR terminus are found at genetically different sites in the two parental strains, and no hybridization to the VR telomere from Mauriceville was detected. The other genomic copies identified in the Oak Ridge parent were not telomeres. I suggest that any repeating sequence blocks found immediately adjacent to the VR terminus in Oak Ridge strains must be small and that the repeating element identified in that background may be an N. crassa transposable element integrated near the the chromosome end at VR.

scholarly journals Chiasmata in spermatocytes of Drosophila melanogaster

1964 ◽  
Vol 5 (1) ◽  
pp. 80-84 ◽  
Author(s):  
B. M. Slizynski
Keyword(s):  
Drosophila Melanogaster ◽  
Type Strain ◽  
Wild Type Strain ◽  
Chromosome Behaviour ◽  
Wild Type ◽  
Homologous Chromosomes ◽  
Translocation Heterozygote ◽  
Positive Material ◽  
Chromosome Material

On the basis of chromosome behaviour in three strains of Drosophila melanogaster males—a wild-type strain, a translocation heterozygote strain and a double translocation strain—it is concluded that the cytologically detected apparent chiasmata in the autosomes are only surface associations of homologous chromosomes and do not involve exchange of chromosome material. Such chiasma-like associations occur also between non-homologous chromosomes. The stainable, Feulgen-positive material of the chromosomes is thought to be responsible for the surface associations.

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