US Patent 7105324 Nucleic acid isolated from

The present invention relates to nucleic acids isolated from Tetrahymena which code for a ciliate-specific triterpenoid cyclase. The inventive nucleotide sequences and the polypeptide sequences derived therefrom demonstrate a surprisingly minimal sequence identity to known isoprenoid cyclases. The invention also relates to the use of nucleic acids for the regulation of triterpenoid cyclase expression in a host organism, as well as the targeted knockout or repriming of the triterpenoid cyclase gene. As a result of the altered expression of the triterpenoid cyclase, it is possible to modify and enrich the levels of multiple unsaturated fatty acids in the host organism.