jan 1, 1929 - Frederick Griffith: Bacterial Transformation
Description:
In 1929, Griffith conducted experiments with Streptococcus pneumoniae bacteria. He was originally trying to develop a vaccine against pneumonia, but ended up with a way to identify genetic material.
In his experiment, he used "R" (nonvirulent) and "S" (highly virulent) strains of bacteria. Through heating of the S strain of the bacteria he discovered that it's virulence was destroyed. He found that when injected with heat-killed S bacteria and living R bacteria, mice had died which was surprising because they where fine when the strains were injected separately.
This experiment led him to the hypothesis that a chemical component from the virulent S strain had transformed the R strains into a more virulent S form.
Today, looking back at this experiment we know that after being heat-treated, DNA molecules can re-nature, and that bacteria can take up DNA from the environment by a process that we refer to transformation.
Source: https://www.nature.com/scitable/nated/article?action=showContentInPopup&contentPK=336
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DNA TIMELINE
Yana Kryvyak
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