Abstract
Competent Haemophilus influenzae bacteria were exposed to purified phage HP1 DNA and then plated for transfectants (PFU). When 32% (final concentration) glycerol was added before plating, between 10- and 100-fold more transfectants were observed. Glycerol had no significant effect on transfection with DNA from single or tandem double lysogens. It also had little effect on transformation with chromosomal DNA or on transformation of defective HP1 lysogens with phage HP1 DNA. It was concluded that glycerol induced the release of adsorbed linear double-stranded DNA into the interior of the cells.
Highlights
Competent Haemophilus influenzae cells take up DNA into membranous organelles called transformasomes (2, 5, 11-13; for recent reviews, see references 8 and 14)
I reasoned that the study of the effect of glycerol on transfection of competent H. influenzae cells with pure phage HP1 DNA
Cells were mixed with 0.001 p,g of phage HP1 DNA per ml and shaken at these temperatures
Summary
Competent Haemophilus influenzae cells take up DNA into membranous organelles called transformasomes (2, 5, 11-13; for recent reviews, see references 8 and 14). Circular DNA remains within these transformasomes, whereas linear DNA exits rapidly. This release was shown to be directional from the free 3' end [2]. The end, while undergoing degradation, searches for homologous regions of the chromosome and is, after pairing, integrated in the chromosome [1] This hypothesis implies that transformation of competent cells by circular plasmid DNA should not occur. I have, speculated that a minute fraction of adsorbed circular plasmids can leak out of the transformasomes intact. Evidence for this speculation was obtained by treating recipient cells with glycerol before plating for plasmid transformants I reasoned that the study of the effect of glycerol on transfection of competent H. influenzae cells with pure phage HP1 DNA might provide an answer
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