The fate of parental DNA of bacteriophage T2 in crosses with bacteriophage T4.

In mixed infections of the bacteriophages T2 and T4, most of the genes coding for early functions of T2 are nearly absent in the progeny (partial exclusion). Breakdown of the parental T2 DNA is an attractive hypothesis for this exclusion. Precipitation with HClO4 showed that 3–5% of the parental T2 DNA rapidly becomes acid-soluble as a result of crossing with T4. Sucrose-gradient analysis showed that 15% of the parental T2 DNA is broken down to fragments of all size classes. The remaining 85% of the parental DNA showed no detectable breakdown. Breakdown of parental T2 DNA thus does not seem to be the primary event in partial exlusion.