Excision cascade

No conclusive information is as yet available on the mechanism of the initial step of rDNA amplification. It is not known whether the first amplified copy of rDNA is a replica or an excision product. A process whereby amplification is mediated by RNA followed by reverse transcription has also been suggested (Tocchini-Valentini and Crippa, 1971 see later). Furthermore, it remains unknown whether one, a few, or all chromosomal rRNA genes are involved in gene amplification. Two different mechanisms—not necessarily mutually exclusive— have been proposed for the production of additional rDNA replicas (Miller, 1966). The amplified rDNA might be synthesized only on the chromosomal template. Alternatively, the newly synthesized rDNA copies could serve as new templates for subsequent replications, resulting in a cascade effect. Autoradiographic evidence has been presented which favors the second mechanism (Macgregor, 1968). 

What are the components of the molecules that are truly contributing to potency and to the other properties and assays you have defined in your testing cascade Put differently, what parts of the molecules can be readily replaced or excised entirely ... 

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