Invoking onPersist of Base-Prototype

Hi List!

I have a base prototype from which i inherit quite a bunch of other 
prototypes.
Now, if I store an object of one of the child-prototypes i want the 
onPersist()-function of the base-prototype to be called.

(Background: I don't want to implement a "if you are stored, make this 
and this" in every child-prototype. if an object has a specific 
base-prototype than some code should automatically be executed when 
storing the object.)

How can i achieve this?


Thanks,
Anton