Improved Methods Controlling Gene Expression

A method for transgenic expression with enhanced specificity in a eukaryotic organism, said method comprising the steps of:

• a) providing an expression construct comprising a promoter sequence functional in said eukaryotic organism and functionally linked thereto a nucleotide sequence to be expressed into a chimeric RNA sequence, said nucleotide sequence comprising
• i) at least one sequence capable to confer a preferred phenotype or beneficial effect to said eukaryotic organism, and
• ii) at least one sequence substantially complementary to a microRNA sequence naturally expressed in said eukaryotic organism, wherein said microRNA is naturally expressed in tissues, at times, and/or under environmental conditions, where expression is not desired, but is not or substantially less expressed in tissues, at times, and/or under environmental conditions, where such expression is desired,
• wherein at least one of sequence i) and sequence ii) are heterologous to each other, and
• b) introducing said expression construct into a eukaryotic organism,
• wherein the sequence being substantially complementary to the microRNA is positioned in a location of the nucleotide sequence to be expressed corresponding to the 5′-untranslated region or the 3′-untranslated region of said sequence.