SQL & PL/SQL

here is the scenario:
we have 4 oracle databases and have been asked to create a central mysql database which would have parts of the data from all 4 databases. Now the transfer of data from oracle to mysql should be scheduled or triggered by any changes to the tables/ fields in use.

is it possible to create triggers in oracle
with which data from oracle tables can be sent to
a remote mysql database and its table/s populated?

if populating a mysql table remotely using an oracle trigger is not possible then perhaps the trigger can create data files and then throw the files to the mysql server.

if this is not possible then what alternatives do we have?

thanks