A few considerations - OTOF is ~100,000 bp long in the genome, but that includes tons of introns and no one was trying to deliver that. They would do the protein coding part alone which is about 7,200 long - still too long for AAVs (capacity: ~4,200 bp), hence splitting in two. Technically, lentivirus could carry the whole 7,200 bp in one piece, but there's a number of other limitations with these relating to tissue-specific targeting and insertional mutagenesis.
Mouse cloning paper is frankly a bit weird - it seems they were not maintaining large breeding schemes typical for stock laboratory mouse colonies (at best ~25 mice per gen, but likely fewer than that), so their mice probably accumulated defects over time due to genetic "bottlenecking". This is exactly what you'd expect, and the only surprise is that they could keep it going for 20 years. Professional mouse breeders (companies, large mouse research facilities) not only make sure many cross-breeding pairs contribute to the next generation, but also "reset" their stocks every 2-5 years from frozen sperm. Otherwise the genetic make-up of an inbred colony will drift, with functional consequences. And sure, there's some difference between breeding (germline mutations) and cloning (somatic mutations), but it shouldn't take 20 years to map that out.
Thanks for reading the post. I should have mentioned the size of the spliced gene that they packed in the dual-AAV therapy, so thank you for flagging that mistake!
Question about p53: would it make sense to supply it exogenously to prevent cancer? I know that elephants overexpress p53 to address the higher cancer risk from having more tissue.
“One might suspect that a lack of genetic diversity would make the animals non-viable (after all, that’s what happened to royal dynasties in which brothers married sisters or cousins).”
I would delete this part. These animals are not breeding they are just being cloned in a closed environment. Lack of genetic diversity is not an issue.
I was trying to get help from Isaac Asimov while he was busy dying thanks to the Red Cross! That is because he was unique in that he wanted to understand everything. That drove me to start writing books which never found a publisher and now I've progressed to doing this.
I love this newsletter
Thanks for the overview!
A few considerations - OTOF is ~100,000 bp long in the genome, but that includes tons of introns and no one was trying to deliver that. They would do the protein coding part alone which is about 7,200 long - still too long for AAVs (capacity: ~4,200 bp), hence splitting in two. Technically, lentivirus could carry the whole 7,200 bp in one piece, but there's a number of other limitations with these relating to tissue-specific targeting and insertional mutagenesis.
Mouse cloning paper is frankly a bit weird - it seems they were not maintaining large breeding schemes typical for stock laboratory mouse colonies (at best ~25 mice per gen, but likely fewer than that), so their mice probably accumulated defects over time due to genetic "bottlenecking". This is exactly what you'd expect, and the only surprise is that they could keep it going for 20 years. Professional mouse breeders (companies, large mouse research facilities) not only make sure many cross-breeding pairs contribute to the next generation, but also "reset" their stocks every 2-5 years from frozen sperm. Otherwise the genetic make-up of an inbred colony will drift, with functional consequences. And sure, there's some difference between breeding (germline mutations) and cloning (somatic mutations), but it shouldn't take 20 years to map that out.
Thanks for reading the post. I should have mentioned the size of the spliced gene that they packed in the dual-AAV therapy, so thank you for flagging that mistake!
Question about p53: would it make sense to supply it exogenously to prevent cancer? I know that elephants overexpress p53 to address the higher cancer risk from having more tissue.
I don't know the answer, but am also interested in that! People have tried to do it already as gene therapy but it hasn't shown efficacy yet
Oh interesting, I didn't know about the gene therapy results.
For a p53 injection, would probably be challenging to get the protein actually delivered to the nucleus so this might not be the best idea.
RIP, Dr. Braunwald, and thanks for all you did to prolong the life of others, especially heart patients. Enjoy your well-earned rest.
“One might suspect that a lack of genetic diversity would make the animals non-viable (after all, that’s what happened to royal dynasties in which brothers married sisters or cousins).”
I would delete this part. These animals are not breeding they are just being cloned in a closed environment. Lack of genetic diversity is not an issue.
Other than that I love these!
I was trying to get help from Isaac Asimov while he was busy dying thanks to the Red Cross! That is because he was unique in that he wanted to understand everything. That drove me to start writing books which never found a publisher and now I've progressed to doing this.
WHY do proteins fold?
statnews links for Veradermics are broken btw
Ah thanks for pointing that out! I've just fixed it.