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Chromosomal recombination in Haemophilus influenzae.
Genetics
|August 1, 1972
Summary
Internal recombination in Haemophilus influenzae double lysogens produces wild-type phage. This process involves altered prophage marker sequences, suggesting DNA breakage and rejoining mechanisms are key to phage release.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Haemophilus influenzae cultures doubly lysogenic for defective phage HP1 exhibit spontaneous wild-type phage production.
- This phenomenon suggests internal recombination events within the prophage DNA.
Purpose of the Study:
- To investigate the mechanisms underlying wild-type phage production in double lysogens.
- To characterize the genetic alterations associated with phage release.
Main Methods:
- Isolation and characterization of wild-type phage-producing clones from double lysogenic cultures.
- Analysis of prophage marker sequences in resulting clones.
- Comparison of observed recombination patterns with existing models.
Main Results:
- Thirty-one wild-type phage-producing clones were identified, falling into five classes.
- Two classes were explained by Campbell's prophage recombination model.
- Other classes showed loss of prophage markers, consistent with interchromosomal double-strand DNA breakage and rejoining.
Conclusions:
- Wild-type phage production arises from internal recombinants with altered prophage marker sequences.
- Both Campbell's model and DNA breakage/rejoining mechanisms contribute to recombination.
- A single-DNA-strand gene conversion model is proposed, and rec1 mutant derivatives were incapable of internal recombination.