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Electron microscopy of Achlya deoxyribonucleic acid sequence organization
M Pellegrini1, W E Timberlake, R B Goldberg
1Molecular Biology Section, University of Southern California, Los Angeles 90007.
Molecular and Cellular Biology
|February 1, 1981
Summary
Electron microscopy of Achlya bisexualis deoxyribonucleic acid (DNA) reveals repetitive sequences. Findings show inverted repeats are short and unclustered, while repetitive sequences form tandem arrays, not interspaced with single-copy DNA.
Area of Science:
- Molecular Biology
- Genomics
- Mycology
Background:
- Understanding DNA sequence arrangement is crucial for genomic studies.
- The aquatic fungus Achlya bisexualis serves as a model organism for studying fungal genetics.
Purpose of the Study:
- To elucidate the sequence organization of repetitive DNA elements in Achlya bisexualis.
- To characterize the arrangement of inverted repeats and repetitive sequence clusters within the Achlya genome.
Main Methods:
- Electron microscopic analysis of reassociated deoxyribonucleic acid (DNA).
- Utilized the gene 32 protein-ethidium bromide technique for enhanced DNA contrast.
- Isolated and analyzed long DNA fragments (greater than 6-kilobase) after reannealing to specific repetitive C0t values.
Main Results:
- Inverted repeat sequences are short (0.5 kilobase, number-average) and separated by variable nonhomologous DNA.
- These inverted repeat pairs are not clustered within the genome.
- Highly and moderately repetitive DNA sequences exist as tandem arrays of regularly repeating units, without evidence of permutation or interspersion with single-copy DNA.
Conclusions:
- The Achlya bisexualis genome exhibits a specific organization of repetitive DNA sequences.
- Repetitive DNA elements are arranged in tandem arrays, distinct from interspaced single-copy sequences.
- The findings provide insights into the structural organization of fungal genomes.