What metabolically happens when an egg fuses with the nucleus of a somatic cell
Somatic cell nuclear transfer is a method for creating a viable embryo from a somatic cell and egg cell. A somatic nucleus is inserted into an enucleated egg, where the somatic nucleus is reprogrammed by egg cytoplasmic factors to become a zygote (fertilized egg).
This requires the use of eggs in metaphase II of the cell cycle. Somatic cell nuclei must be in interphase (G0/G1). Interphase is the portion of the cell cycle that is not accompanied by observable changes under the microscope.
What determines the success rates of cloning
Oct-4 and other yamanaka factor expression is essential for somatic cell nuclear transfer success (Pay-wall).
Outlined here:

&quot;...we now think that the oocyte cytoplasm might reprogramme the somatic cell nucleus too strongly, or that the somatic cell nucleus is more sensitive to oocyte reprogramming factors than are sperm cell nuclei.&quot;

Thus, Reprogramming and cloning success is unlikely to be influenced by somatic nucleus polymerases and RNA.