  In an effective theory containing only quark degrees of freedom, such as the
extended Nambu-Jona-Lasinio model, the influence of the axial anomaly can be
incorporated by a self-interaction of the 't Hooft determinant type.
  I will show that despite the theshold problem related to the eta-prime meson
this leads to a significant suppression of the eta-prime coupling g_{\eta' q
\bar{q}} to dynamical quarks which suggests a suppression of the eta-prime-NN
vertex as compared to the eta-NN vertex.
