Plants produce a form of histone H3 protein that assists in the maintenance of chromatin structure in differentiated cells. Genes for such histone H3 variants show very high and constitutive expression. Our studies have shown that polypyrimidine (PPY) sequence elements located in the promoter, in the untranslated regions and in the introns play a role in the control of these genes. We hypothesize that these sequences are target sites for proteins similar to the Drosophila GAGA factors, which can cause chromatin de-repression by preventing nucleosome assembly. Dr. Kapros’ research has the aim to study these PPY-binding proteins to be able to understand the way they function in plants. Transgene silencing by heterochromatin is a major problem in plant biotechnology. Specific PPY sequences as natural gene de-repressors have the potential to become an invaluable tool to prevent gene inactivation and to maintain high gene expression in transgenic crops.