  Data on high-$p_T$ hadron production in heavy ion collisions at Feynman
$x_F=0$ indicate at universality of the observed nuclear suppression. Our
analysis of the production mechanisms demonstrates important role of the color
transparency effects which make the survival probability of a quark-antiquark
dipole independent of the quark flavor, provided that the hadron wave function
is formed outside the medium. The latter condition imposes restrictions on the
range of $p_T$, which should be sufficiently high to make the nuclear
suppression universal. We also found that the in-medium broadening rate $\hat
q$ (frequently called transport coefficient) significantly depends on the quark
flavor, diminishing for heavy quarks.
