  Analytic results for the conductance of a molecular wire attached to
mesoscopic tubule leads are obtained. They permit to study linear transport in
presence of low dimensional leads in the whole range of parameters. In
particular contact effects can be addressed in detail. By focusing on the
specificity of the lead-wire contact, we show that the geometry of this hybrid
system supports a mechanism of channel selection, which is a distinctive
hallmark of the mesoscopic nature of the electrodes.
