Methods and Means for Obtaining Modified Phenotypes

A chimeric DNA comprising a promoter operably linked to a target specific DNA region which encodes an unpolyadenylated hairpin RNA, wherein the target specific DNA region comprises a target specific sense nucleotide sequence and a target specific antisense nucleotide sequence, wherein the target specific antisense nucleotide sequence comprises 20 consecutive nucleotides in a sequence identical to the sequence of a complement of a part of an RNA molecule transcribed or produced from a nucleic acid of interest in an animal cell, wherein the target specific sense nucleotide sequence comprises 20 consecutive nucleotides in a sequence identical to the sequence of the part of the RNA molecule transcribed or produced from the nucleic acid of interest, wherein the target specific sense nucleotide sequence and the target specific antisense nucleotide sequence are separated and linked by a spacer sequence, such that the unpolyadenylated hairpin RNA resulting from transcription of the target specific DNA region comprises the spacer sequence located between sense and antisense nucleotide sequences in the unpolyadenylated hairpin RNA, and the sense and antisense nucleotide sequences are complementary to each other so as to form the unpolyadenylated hairpin RNA.

An animal cell in culture comprising a chimeric DNA which comprises a promoter operably linked to a target specific DNA region which encodes an unpolyadenylated hairpin RNA, wherein the target specific DNA region comprises a target specific sense nucleotide sequence and a target specific antisense nucleotide sequence, wherein the target specific antisense nucleotide sequence comprises 20 consecutive nucleotides in a sequence identical to the sequence of a complement of a part of an RNA molecule transcribed or produced from a nucleic acid of interest in the animal cell, wherein the target specific sense nucleotide sequence comprises 20 consecutive nucleotides in a sequence identical to the sequence of the part of the RNA molecule transcribed or produced from the nucleic acid of interest, wherein the target specific sense nucleotide sequence and the target specific antisense nucleotide sequence are separated and linked by a spacer sequence, such that the unpolyadenylated hairpin RNA resulting from transcription of the target specific DNA region comprises the spacer sequence located between sense and antisense nucleotide sequences in the unpolyadenylated hairpin RNA, and wherein the sense and antisense nucleotide sequences are complementary to each other so as to form the unpolyadenylated hairpin RNA.