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Repeated DNA in Pneumocystis carinii
S L Stringer1, S T Hong, D Giuntoli
1Department of Molecular Genetics, Biochemistry, and Microbiology, College of Medicine, University of Cincinnati, Ohio 45267-0524.
Abstract:
A 16-kb DNA fragment designated Rp3-1 and cloned from the genome of rat-derived Pneumocystis carinii was found to contain sequences that were repeated approximately 70 times per genome. The repeated sequences in Rp3-1 spanned at least 10.4 kb. Sequences in Rp3-1 were present on each of the 16 P. carinii chromosomes resolved by field inversion gel electrophoresis. Most of the P. carinii genomic sequences homologous to those in the Rp3-1 clone appeared to be as long as those in the Rp3-1 clone but were highly polymorphic with respect to restriction enzyme cleavage sites. The Rp3-1 DNA fragment appears to be a member of a family of large, degenerate, dispersed repeats.
Insights
A cloned DNA fragment from Pneumocystis carinii, called Rp3-1, reveals large, dispersed repetitive DNA sequences. These sequences are present on all chromosomes and show significant genomic variation.
Area of Science:
- Molecular Biology
- Genomics
- Mycology
Background:
- Pneumocystis carinii is an opportunistic fungal pathogen.
- Understanding the genome of P. carinii is crucial for studying its biology and pathogenesis.
- Repetitive DNA elements play significant roles in genome evolution and organization.
Purpose of the Study:
- To characterize a cloned DNA fragment (Rp3-1) from the Pneumocystis carinii genome.
- To investigate the nature and distribution of repetitive sequences within the P. carinii genome.
Main Methods:
- Cloning of a 16-kb DNA fragment (Rp3-1) from P. carinii.
- Analysis of repetitive sequences within the cloned fragment.
- Detection of homologous sequences across P. carinii chromosomes using field inversion gel electrophoresis.
- Restriction enzyme digestion to assess polymorphism.
Main Results:
- The Rp3-1 fragment contains sequences repeated approximately 70 times per genome.
- These repetitive sequences span at least 10.4 kb.
- Sequences homologous to Rp3-1 are found on all 16 resolved P. carinii chromosomes.
- The homologous sequences are large but highly polymorphic regarding restriction sites.
Conclusions:
- The Rp3-1 DNA fragment represents a member of a large, degenerate, and dispersed repeat family in the P. carinii genome.
- These repeats are abundant and widely distributed across the P. carinii chromosomes.
- The high degree of polymorphism suggests ongoing evolution and potential functional significance of these repeats.