From a recent review article in Nature Genetics:

[…] current ad hoc IR systems are not able to retrieve our example sentence when they are given the query ‘yeast cell cycle’. Instead, this could be achieved by realizing that ‘yeast’ is a synonym for S. cerevisiae, that ‘cell cycle’ is a Gene Ontology term, that the word ‘Cdc28’ refers to an S. cerevisiae protein and finally, by looking up the Gene Ontology terms that relate to Cdc28 to connect it to the yeast cell cycle. Although this will not be easy, we see this form of query expansion as the next logical step for ad hoc IR.