Feel free to use sources of nuclear DNA if you feel that the efficacy gain is worth it.
However, those sources tend to require frequent replacement due to degradation.
The use of nail samples for DNA has a recommendation to be replaced every 30 days due to a light component that was established by Russian experiments and confirmed by other scientist as being a factor we yet fully understand. This light component of DNA fades after 30 days.
However, I have tested nail samples that have been aged for more than a year, and they still elicit reactions that were observed when the nails were fresh.
So in the case where one can not regularly update nail samples, their use past the 30 days is a beneficial factor.
While I have taken and used nails from myself that were over a year old, and then compared to a fresh sample to see if efficacy rates were significant enough to warrant constant updating of the samples, I found that at most it maybe was reduced to a point where that you would have to add one more day to the treatment to gain the same level of efficacy.
Considering that I have many samples in my remotes, I must admit that I found the process of updating 63 samples every 30 days to be too much work and thus needed to test and find out if older samples were viable.
I've confirmed my test observations with others in the remote and so have replicated my results in a way that is satisfactory to myself.
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