Bernard Dujon
He graduated in the top 1% of students and was offered the opportunity to compete for an oral exam at the prestigious Ecole Normale Supérieure (ENS rue d'Ulm), was ranked first and admitted there the following year (1966).
He therefore became a normalien at the early age of 19, when most of the students attracted by this career are still preparing in specialized schools for this written and oral competition.
Subsequently, instead of preparing the agrégation, that would have ensured a permanent position in the education system, he decided to follow doctorate studies under the supervision of Piotr Slonimski, a Polish-French geneticist, at the CNRS campus of Gif-sur-Yvette, in the southern parisian suburban area.
At the same time, he was recruited as a junior scientist by the CNRS (1970), allowing him to complete his PhD thesis, while earning a salary to support his family.
[7] When crossing two haploid yeast species carrying different mitochondrial mutations, conferring the resistance to erythromycin or to chloramphenicol, allele segregation did not follow mendelian rules and recombinants appeared in mysterious proportions.
In 1977, independent researches by Fred Sanger on one side and by Walter Gilbert and Allan Maxam on the other, led to the invention of two different methods to sequence DNA.
Bernard Dujon contacted Walter Gilbert at Harvard University about the possibility to come to his lab for a short post-doctoral period, in order to sequence the omega locus.
[9] Back to Gif-sur-Yvette in 1981, Bernard Dujon set up a small team in an old lab space lent by Piotr Slonimski.
François Michel rapidly joined him and later on Alain Jacquier, Hugues Blanc, Pierre Dehoux and Laurence Colleaux, as well as sabbatical visitors such as Walt Fangman from the University of Washington.
Bernard Dujon decided to adapt the mitochondrial gene to the universal genetic code in order to be able to express it in a heterologous system.
Fortunately, Bernard Dujon met Francis Galibert, who was working at the Hôpital Saint Louis in Paris and who just came back from Fred Sanger laboratory to set up his own lab.
With the help of Francis Galibert's oligonucleotides, Bernard Dujon modified 26 of the 235 codons of the omega reading frame to adapt it to the universal genetic code.
[23] The extremely high level of gene redundancy, due -at least in part- to an ancient whole-genome duplication in the ancestor of Saccharomyces species, led to a new era in biology.
While Bernard Dujon was participating to the EUROFAN program, aiming at determining the function of all discovered genes, he started a completely different approach, based on yeast comparative genomics.
Odile Ozier-Kalogeropoulos and her Master student, Alain Malpertuy, had produced 600 sequence reads of a yeast of biotechnological interest, Kluyveromyces lactis.
Following an informal discussion with Jean Weissenbach, head of the Génoscope, the largest sequencing center in France, Bernard Dujon contacted two French geneticists who were known to be interested in non-conventional yeast species: Jean-Luc Souciet at the University of Strasbourg and Claude Gaillardin at the National Center for Agronomy (INRA) in Grignon.
Their comparison made possible to develop new theories on the molecular mechanisms of evolution of eukaryotic genomes which, thanks to the power of genetics in S. cerevisiae, can be directly subjected to experimentation.
Results were published in a special issue of FEBS Letters, edited by Horst Feldman and appeared in press just a few days before the end of the 20th century.
The Génolevures consortium sequenced to completion four yeast genomes, Candida glabrata, Kluyveromyces lactis, Debaryomyces hansenii and Yarrowia lipolytica.
Bernard Dujon is the author of a vulgarization book on genetics,[34] as well as of a textbook entitled Trajectoires de la génétique.
