  A key goal of bioinformatics is to create database systems and software
platforms capable of storing and analysing large sets of biological data.
Hundreds of biological databases are now available and provide access to huge
amount of biological data. SGD, Yeastract, CYGD-MIPS, BioGrid and PhosphoGrid
are five of the most visited databases by the yeast community. These sources
provide complementary data on biological entities. Biologists are brought
systematically to query these data sources in order to analyse the results of
their experiments. Because of the heterogeneity of these sources, querying them
separately and then manually combining the returned result is a complex and
laborious task. To provide transparent and simultaneous access to these
sources, we have developed a mediator-based system called YeastMed. In this
paper, we present YeastMed focusing on its architecture.
