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Repair-defect mutations inhibit rDNA magnification in Drosophila and discriminate between meiotic and premeiotic
Abstract:
We have examined rDNA magnification in Drosophila melanogaster males carrying one of 11 recombination- or repair-defective mutations representing seven loci. We show that mutations defined by a defect in postreplication repair (mus-101, mei-41, and mus-108) are also defective in rDNA magnification, whereas mutations that do not affect postreplication repair have little or no effect on magnification. mei-41 inhibits only premeiotic magnification events, while mus-108 blocks both premeiotic and meiotic events. This suggests that meiotic and premeiotic events share some but not all functions. A molecular analysis of rDNA magnification reveals that in mus-108 males, changes in the rDNA restriction pattern can occur within one or a few generations under magnifying conditions. We interpret these data in terms of the role of DNA repair systems in rDNA magnification and in terms of stable maintenance of tandemly repeated genes.
Insights
DNA repair mechanisms are crucial for rDNA magnification in Drosophila melanogaster. Mutations affecting postreplication repair disrupt this process, impacting the stable maintenance of tandemly repeated genes.
Area of Science:
- Genetics
- Molecular Biology
- Drosophila melanogaster research
Background:
- Ribosomal DNA (rDNA) magnification is a process affecting gene copy number.
- DNA repair pathways play a role in genome stability.
Purpose of the Study:
- To investigate the role of recombination and repair mutations in rDNA magnification in Drosophila melanogaster.
- To elucidate the specific functions of DNA repair in premeiotic and meiotic magnification events.
Main Methods:
- Examined 11 recombination- or repair-defective mutations in Drosophila melanogaster males.
- Assessed the impact of these mutations on rDNA magnification.
- Performed molecular analysis of rDNA restriction patterns under magnifying conditions.
Main Results:
- Mutations in postreplication repair genes (mus-101, mei-41, mus-108) significantly impaired rDNA magnification.
- mei-41 affected only premeiotic magnification, while mus-108 affected both premeiotic and meiotic events.
- Molecular analysis showed rapid changes in rDNA restriction patterns in mus-108 mutants.
Conclusions:
- Postreplication DNA repair is essential for rDNA magnification in Drosophila.
- Premeiotic and meiotic magnification events share some, but not all, DNA repair functions.
- DNA repair systems are critical for the stable maintenance of tandemly repeated genes like rDNA.