A structure for nucleic acid has already been proposed by Pauling and Corey and it is believed that the material which gives the X-ray diagrams is the salt, not the free acid, so without the acidic hydrogen atoms it is not clear what forces would hold the structure together.
The determination in 1953 of the structure of deoxyribonucleic acid (DNA), with its two entwined helices and paired organic bases, was a tour de force in X-ray crystallography and opened the way for a deeper understanding of perhaps the most important biological process.
As of 2018, most scientists accept Watson and Crick ́s model of DNA presented in the article, which connected the concept of genes to heredity, growth, and development.
The detailed structure described by Crick and Watson has been shown to have too large a diameter, and a drawing has been given of an improved model which is in fairly good agreement with the s-ray data.
Watson and Crick proposed that plant viruses consistently took one of two shapes because the two chemical components of which they were made up, ribonucleic acid surrounded by a large number of identical protein subunits, were assembled according to a general plan that was determined by "symmetry elements".
These studies identify a new source of human IL-2 and establish a valuable reagent for the isolation and further molecular characterization of this immunoregulatory molecule.
Murine helper T cells activated to sheep or horse erythrocyte antigens in vivo have been established as continuous cell lines in culture and stable helper activity for greater than 50 wk in culture is shown.