Evolution of intermediate mass galaxies up to z~0.7 and studies of SNe
  Ia hosts
  In the first part of this manuscript, I present the results on the properties
of the interstellar medium and the stellar content of galaxies at z=0.6, from a
representative sample of distant galaxies observed with the long slit
spectrograph VLT/FORS2. This study has been realized in the framework of the
ESO large program IMAGES "Intermediate MAss Galaxy Evolution Sequences", which
aims to investigate the evolution of the main global properties of galaxies up
to z~0.9. I discuss the implications of the observed chemical enrichment of the
gas on the scenarios of galaxy formation. I also propose a new method to
estimate reliable stellar masses in starburst galaxies using broadband
photometry and their total star-formation rate.
  In a second part, I present a new method to extract, with high accuracy, the
sky in spectra acquired with a fiber-fed instrument. I have developed this code
in the Framework of the phase A of an instrument proposed for the E-ELT:
OPTIMOS-EVE. This is a multi-fiber spectrograph able to observe at optical and
infrared wavelengths simultaneously.
  In the third part, I show preliminary results from the CENTRA GEPI- survey at
Calar Alto Observatory to study nearby galaxies, hosts of type Ia supernovae,
using integral field spectroscopy. I present the first 2D maps of the gas and
stellar populations of SNe Ia hosts. The results allow us to directly access
the host properties in the immediate vicinity of the SNe Ia. This is a crucial
step to investigate eventual correlations between galaxy properties and SNe Ia
events and evolution, leading to systematic effects on the derivation of the
cosmological parameters.
