jan 1, 1950 - 1950: Erwin Chargaff discovers that DNA composition is species specific

Description:

In 1944, scientist Erwin Chargaff had read Oswald Avery's scientific paper, which identified DNA as the substance responsible for heredity. The paper had a huge impact on Chargaff and changed the future course of his career. He later recollected, “Avery gave us the first text of a new language, or rather he showed us where to look for it. I resolved to search for this text. Consequently, I decided to relinquish all that we had been working on or to bring it to a quick conclusion”.

Chargaff was determined to begin work on the chemistry of nucleic acids. His first move was to devise a method of analysing the nitrogenous components and sugars of DNA from different species.

He subsequently submitted two papers to the Journal of Biological Chemistry (JBC) detailing the complete qualitative analysis of a number of DNA preparations. Despite the significance of the paper’s findings, the JBC was initially reluctant to publish it, illustrating the ignorance about nucleic acids amongst elite scientists at the time.

Chargaff continued to improve his research methods and was eventually able to rapidly analyse DNA from a wide range of species. In 1950, he summarised his two major findings regarding the chemistry of nucleic acids: first, that in any double-stranded DNA, the number of guanine units is equal to the number of cytosine units and the number of adenine units is equal to the number of thymine units, and second that the composition of DNA varies between species. These discoveries are now known as 'Chargaff's Rules'.

Added to timeline:

Date: