Non-helical models of DNA structure the top of this article, or there could be an equal number of right-handed and left-handed twists, as in the Rodley structure below. The abbreviation "TN", to be used to refer to any DNA structure whose strands are topologically non-linked, has been proposed. The double-helix model of DNA structure was first published in the journal "Nature" by James D. Watson and Francis Crick in 1953 with further details in 1954.) Their work was based upon the crucial X-ray diffraction image of DNA - labeled as "Photo 51" - from Rosalind Franklin in 1952, followed by her more highly clarified DNA
Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid directions. Crick was thus in a unique position to make this interpretation because he had formerly worked on the X-ray diffraction data for other large molecules that had helical symmetry similar to that of DNA. Franklin, on the other hand, rejected the first molecular model building approach proposed by Crick and Watson: the first DNA model, which in 1952 Watson presented to her and to Wilkins in London, had an obviously incorrect structure with hydrated charged groups on the inside of the model, rather than on the outside. Watson explicitly admitted this in his book "The Double Helix". Molecular Structure