I'm pretty sure most of you have used the tetracycline system for regulating gene expression in cells or transgenic mice at least once in your life. This exceptional inducible system (imported from bacteria), has proven robust and efficient over the years and is still one of the best approaches for properly activating or silencing a gene at will by administering (or not) simple antibiotics, such as doxycycline. The scientist behind that innovation is Hermann Bujard, a molecular biologist who worked for many years at the ZMBH in Heidelberg. He sadly passed away on the 31st of July at the age of 86.
Hermann Bujard and his collaborator Manfred Gossen presented their idea of using some elements of the prokaryotic operon from E.coli transposon Tn10 that confers tetracycline resistance for reversibly inducing or repressing gene expression in eukaryotes. Their seminal paper was published in PNAS in 1992. The first Tet system is what was later known as TET-OFF or tTA (where Dox is provided for preventing gene expression).
Four years later they obtained a reverse mutant of the TetR and created the TET-ON approach or rtTA (where Dox is provided for activating gene expression), and they showed this system worked in transgenic mice.
You can read about Hermann Bujard's research life through the obituaries published by EMBO and ZMBH, two institutions he had the honor to chair and direct. He's gone but his scientific contributions to our field will remain forever.
May he rest in peace.
Dr. Lluis Montoliu