Membranes and fivebranes with lower supersymmetry and their AdS supergravity duals

We consider superconformal field theories in three and six dimensions with eight supercharges which can be realized on the world-volume of M-theory branes sitting at orbifold singularities. We find that they should admit a N=4 and N=2 supergravity dual in AdS4 and AdS7, respectively. We discuss the characteristics of the corresponding gauged supergravities.