Replication of DNA in UV-irradiated Escherichia coli in the absence of amino acids.

Since pyrimidine dimers are considered to be the cause of the synthesis of short DNA segments, normalization of DNA replication after UV irradiation should be in a temporal correlation with their removal. This correlation holds in exponentially growing excision-proficient Escherichia coli cells. However, when these cells are preincubated and postincubated without amino acids, synthesis of short segments continues although dimers are efficiently excised.