Novel oligonucleotide pairs which can form a duplex comprising one or more DNA-like nucleotides (e.g., 2&prime-sub-stituted arabinonucleotides (ANA)) in combination with one or more RNA-like nucleotides (e.g., 2&prime-substituted ribonucleotides (RNA) and/or locked nucleic acid nucleotides (LNA)), are disclosed. The use of such oligonucleotide duplexes, such as for silencing the expression of a nucleic acid or gene of interest using small interfering RNA (siRNA) technologies, is also disclosed.
