In 1940, due to the Second World War, Madeleine Gans and her family left Pont-à-Mousson and Nancy to take refuge first in Britany (Rennes), then in Larche and Toulouse, in non-occupied south-west France.
On December 21st 1951, she defended her doctoral thesis "Etude génétique et physiologique du mutant zeste de Drosophila melanogaster",[2] which was published in French in 1953.
From 1953 onwards she switched to a university teaching career, first as « Chef de travaux pratiques » (Head of the laboratory courses) at the Sorbonne.
She showed that this property is subject to position effect as the w+ gene activity is abolished or reduced when it is transferred close to centromeric heterochromatin via chromosomal rearrangements.
Finally, she precisely characterized conditions leading to variegated eye pigmentation, such as external parameters (temperature) or genetic contexts.
[2] In 1955, Georges Prévost, a new young researcher, recruited as « Chef de travaux pratiques» in the Department of Genetics at the Faculty of Sciences of Paris.
Their research subjects followed two main paths: isolation of mutants and analysis of their metabolism[4][5] and the use of the dicaryotic phase to answer fundamental questions concerning nuclear exchanges.