INTRO
Historical figures in biotechnology
5
The first recorded experiment of bacterial transformation was performed by Frederick Griffith in 1928, while trying to find a cure for the Spanish influenza. In Griffith's experiment, he used two different strains of pneumococcus bacteria which infect mice: type III-s (smooth) and type II-R (rough). The III-S strain covers itself with a polusaccharide capsule, which protects it from being killed by the host's immune system, which in turn causes death of the mouse. Since the II-R strain does not posess the protective polysaccharide capsule, the immune system destroys the virus, and the mouse lives. The rough strain is therefore known as nonvirulent, and the smooth strain is known as virulent.
In his experiments, Griffith discovered that the virulent III-S strain could be killed using heat, and when injected into the mouse, it did not die.
While neither the rough strain nor the heat-killed smooth strain alone did not kill the mouse, together, the two killed its host.
Griffith was also able to isolate both live II-R and live III-S strains of pneumococcus from the blood of these dead mice. He concluded that the type II-R strain had to have been transformed into lethal III-S strain by a transforming principle, which was part of the dead III-S strain bacteria.
The experiment showed that one type of bacteria could take up a gene from another, and in turn altering its original properties. This experiment has lead to many other experiments which are still used today.
Frederick Griffith
Frederick Griffith
Oswald Avery
1879-1941
1877-1955
DNA is the material of which genes and chromosomes are made
1909-1972
Colin Macleod
DNA is the active component in Bacterial Transformation
Maclyn McCartney
DNA, rather than protein constitute the chemical nature of a gene
1911-2005
Joshua Lederberg
Bacterial Conjugation:
bacteria are able to exchange genes
1925-2008
NOBEL PRIZE 1958
Martin Chalfie, Osamu Shimomura, and Roger Tsien
Discovery (1962) and development of GFP (Green Fluorescent Protein)
NOBEL PRIZE 2008
pGLO plasmids are engineered and used to create genetically modified organisms. The plasmid contains the green fluorescent protein (GFP) and the ampicillin resistance gene. The GFP protein is only expressed in the presence of arabinose. The plasmid itself is made out of 3 genes: Beta-Lactamase (bla), araC (the promoter region expressing the GFP protein), and GFP.
Green Fluorescent protein has existed for millions of years, in one particular species of jellyfish, known as Aequorea victoria.
The protein is found in the photoorgans of the jellyfish. Aequorin, is a different protein which excretes blue light, which then binds with calcium. The blue light gets absorbed by the GFP which is seen as green light. There is a wide range of GFP uses, such as seeing when proteins are made and where they travel to, or cancer research. In one experiment, a mouse was injected with GFP, and it glowed under UV light. This is useful when monitoring human cancer cells that show DsRed.
The cancer cell within the mouse will glow red. This aids researchers in letting them know ehre the cancer moves in the body, as well as how fast the cancer cells grow.
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