  We have mapped the 12CO J=1-0 and J=2-1 line emission in Mrk86, one of the
most metal-deficient Blue Compact Dwarf galaxies so far detected in 12CO. The
12CO emission is distributed in a horseshoe-like structure that follows the
locus of the most recent star formation regions. The minimum in molecular-line
emission corresponds to the position of an older, massive nuclear starburst.
The H2 mass of the galaxy (in the range 0.4-5x10^7 Msun) and its morphology
have been compared with the predictions of hydrodynamic simulations of the
evolution of the interstellar medium surrounding a nuclear starburst. These
simulations suggest that the physical conditions in the gas swept out by the
starburst could have led to the formation of the ring of molecular gas reported
here. This result provides an attractive scenario for explaining the
propagation (in a galactic scale) of the star formation in dwarf galaxies.
