Description:
<jats:p>
The synthesis of different early T4 transcripts by
<jats:italic>E. coli</jats:italic>
RNA polymerase
<jats:italic>in vitro</jats:italic>
can be dissociated in two ways: (1) when T4 DNA is mechanically degraded, it selectively loses the ability to serve as a template for the transcription of
<jats:italic>delayed early</jats:italic>
T4 RNA; (2) when initiation of RNA synthesis on intact T4 DNA is limited to a very short time interval
<jats:italic>immediate early</jats:italic>
T4 RNA is synthesized at once but
<jats:italic>delayed early</jats:italic>
polynucleotide sequences appear only after a time lag. We conclude that initiation sites for T4 early RNA synthesis are closer to
<jats:italic>immediate early</jats:italic>
than to
<jats:italic>delayed early</jats:italic>
segments of the T4 template and that
<jats:italic>immediate early</jats:italic>
and
<jats:italic>delayed early</jats:italic>
segments of the T4 chromosome are interspersed. We propose that this interspersing is significant for the programming of transcription during T4 development.
</jats:p>