<p>Disclosed is a double-stranded polynucleotide which is stable against ribonucleases and has an RNA-silencing activity. Specifically disclosed is a double-stranded polynucleotide composed of a sense strand and an antisense strand. The double-stranded polynucleotide comprises a polynucleotide containing a nucleotide unit comprising an alternating combination of DNA and 2'-O-methyl RNA.</p>
