Question

How could you use zygotic induction in Escherichia coli (lysogenic with lambda phage) to explain how integrated animal viruses could be rescued upon co-cultivation of the transformed cells with non-transformed permissive cells?

Answer 1

Ans

In Zygotic induction of E.Coli, bacteriophages (lambda and lysis) exists symbiotic relationship with virus and goes with the lytic or lysogenic development. In stable lysogenic state, prophage replicates passively with host genome, and expression of the CI repressor is maintained by binding at oL and oR operators which blocks the phage lytic gene expression. In the ‘off’ state, CI repressor dominates phage gene expression, while ‘on’ state, the CI repressor remains inactivated. When they are treated with DNA-damaging agents host SOS response gets activated and DNA repair system is induced. By this process the inactivation of the CI repressor occurs an irreversibly switch into lytic development. In induction and infection processes, the ?Cro protein represses the pL and pR promoters, and efficient lyitc growth occurs.