Matériaux et Biomatériaux innovants

 

Génétique et Epigénétique des Champignons

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L'équipe GEC fait partie du Laboratoire Interdisciplinaire des Energies de Demain (LIED), UMR 8236

Responsable de l'équipe:
Professeur Philippe Silar

Tel: (33) 1 57 27 84 72

E-mail:philippe.silar@univ-paris-diderot.fr

 

 

CRIPPLED GROWTH

 

Crippled Growth occurs only on media containing high amounts of Yeast Extract. It does not promote death but serious health impairment. Crippled Growth sectors appear spontaneously during growth as depicted in the animation, which recapitulates the evolution of a culture during one week.

CG

 

 

CG

Normal Gowth

Crippled Growth

Comparison of the Normal and Crippled Growth of the filamentous fungus Podospora anserina (AS6-5 strain)

 

We have identified several genes involved either in the development of Crippled Growth (their mutation prevent the development of the growth alteration: genes IDC), or on the contrary genes that facilitate the development of Crippled Growth (their mutations permit  the development of the growth alteration on medium lacking yeast extract: genes PDC).

The cloning of some IDC genes revealed that they code for proteins implied in the transduction of the signal from the outside of the cell towards the interior. The pathway contains a MAP kinase module (PaASK1, PaMKK1 et PaMpk1) as well as a NADPH oxidase (PaNox1). This data enabled us to formulate a hypothesis as for the nature of the infectious element.

The transduction cascade could present two states on and off. The off state would be the normal state of the cells in growth and the on state that of the cells in stationary phase. Normally, during the resumption of growth the cascade must be inactivated. That would not be the case on yeast extract containing medium. A loop of positive self-regulation would make it possible to sustain the activation of the cascade during growth. Such a phenomenon of sustained activity is called hysteresis and could be a phenomenon present in several signalling pathways. The transmission of the two states on and off would be done then in a faithful way during cellular divisions, the active state involving an altered growth.

 

We have also identified some PDC genes. They code for proteins involved in cytosolic translation and the PDC mutations trigger an increase in translation accuracy! We are currently investigation this unexpected relationship between translation fidelity and signal transduction.