Comment by dekhn
3 days ago
I think we already knew Franklin recognized the fibre diffraction was consistent with a helix (IIRC, Stokes had already shown that a helix would form a cross shape in a diffraction in 1950, and I believe Franklin was working with him). That wasn't the actual detail that I think is controversial.
Instead, this new paper and several previous papers based on Franklin's notes:
https://link.springer.com/article/10.1007/s10739-026-09866-7 (the paper referenced in the article) -> Franklin's notes say "“evidence for [a] 2-chain […] helix.”Footnote21" where Footnote 21 is Notebook entry for 10 February 1953 (FRKN 1/1, Franklin Papers). The images of her notes are here: https://www.jessiemillsauthor.com/journalism/photo-49-the-x-... (I can't read her handwriting, so I'm taking the 2-chain helix on faith. Also, this article https://philpapers.org/archive/NIETNC-3.pdf interprets her notes to say she recognized the complementary bases: " Franklin’s notebook entry of January 19, 1953—“diads in A. Chargaff data” (Klug index, FRKN 1/1, p. 3)—demonstrates that she had inferred complementary base pairing from the conjunction of Chargaff’s ratios and the crystallographic dyad symmetry, eleven days before Watson saw Photo 51.
So based on the above interpretation, I would probably update my understanding from:
1) Gosling collected the fibre diffraction data and Franklin recognized both that it was a helix, and that the bases were on the inside and complementary. 2) Watson and Crick deduced that DNA formed a double helix with antiparallel chains.
And now I would update it to: 1) Gosling collected the fibre diffraction data and Franklin recognized both that it was a double helix, and that the bases were on the inside and complementary. At that point I think she would have recognized the chains were antiparallel due to dyad symmetry, right?) 2) Watson and Crick deduced that DNA formed a double helix with antiparallel chains.
That's the key bit- I had not previously seen any evidence that Franklin knew it was a double helix or that she knew about the complementary bases. And since this is an area that generates a lot of strong emotions, and there's a lot of noise, I'd like to see her exact text, but I simply cannot read her handwriting.
I can read some of it. I used * for two words I couldn't read. And I'm not sure about the word "containing".
> Evidence for 2-chain (or 1-chain helix)?
> 49c - general trend is as for single containing helix
> (which differs from single * chain in integral no. residues/*
> only in contribn of high order J'n to the latter)
The crossed out bit says:
> and this is indistinguishable from double helix with residues on
> each having same ζ-value, since 2nd chain has opposite signs in
> ξ & η terms (eq 1 - 2), and eqn 2 contains only [...]
She was certainly thinking about double helixes.
From that, it's hard to say she wasn't thinking of a double helix. Combined with the fact that she had to correct W&C on the base placement, and knew about base complementary, it suggests that she did conceive of a bit more than Judson and Klug credited her for (which is odd given Klug's comments and conclusions).
In my mind this doesn't actually meet the final necessary criteria for full credit for the B-DNA double helical structure with base complementarity details, nor the recognition of its implications, it mainly changes some internal bits of the story.
I read pretty much the same thing. First * is 'discontinuous', second might be 'turn'. I'm tempted to read 'continuous' where you have 'containing'.
I'd like someone with more knowledge to comment on that paper - I see a lot of red flags and can't make much sense of it.
The images seem to contain commentary on Klug's commentary on Franklins work, in the same color?? The text contradicts the timelines that it cites from Klug, the paper focuses on some seemingly irrelevant details, and makes claims about the dispute I've never heard before (for example that phosphates on the outside was stolen - years after she published that finding at a conference in which Watson was in the audience). It also suggests that Klug - a fierce advocate for Franklin's legacy - was also trying to diminish her work.