Abstract: The present invention aims to provide a new nucleic acid molecule for suppressing expression of the target gene, which (1) has a gene expression suppressing activity equivalent to or higher than that of siRNA, (2) shows no off-target effect of the sense strand, and (3) makes it possible to design a wider range of antisense strand sequences (extends the range of targetable sequences). Since the nucleic acid molecule of the following formula: wherein each symbol is as defined in the DESCRIPTION, has the superior properties of the above-mentioned (1) to (3), it is extremely useful as a novel gene expression inhibitor that replaces conventional siRNA.

Abstract: The present invention aims to provide a method of producing, more efficiently at a high purity, a phosphoramidite preferable for the production (synthesis) of a nucleic acid. Using a coupling reaction of an ether represented by the following chemical formula (105), an enantiomer, tautomer or stereoisomer thereof, or a salt thereof, and a glycoside compound, phosphoramidite that enables efficient synthesis of nucleic acid can be obtained: wherein n is a positive integer, and R and R? are the same or different and each is a hydrogen atom or a hydroxyl-protecting group.

Abstract: The invention provides a single-stranded nucleic acid molecule and a production method thereof. The single-stranded nucleic acid molecule is represented by formula (I): wherein each symbol is as described in the description.

Abstract: The present invention aims to provide a nucleic acid molecule having improved stability in serum and capable of exhibiting a gene expression regulation function after transfer into the cell. A cyclic nucleic acid molecule represented by the following formula (A): wherein each symbol is as described in the DESCRIPTION can be synthesized easily at a low cost, and can inhibit the translation of a protein encoded by the gene. Since the cyclic nucleic acid molecule of the present invention can inhibit the expression of a target gene as described above, for example, it is useful as a pharmaceutical product, a diagnostic agent, an agricultural chemical, and a tool for conducting research on agriculture, medical science, life science, and the like.

Abstract: The invention provides a single-stranded nucleic acid capable of inhibiting expression of a target gene having a delivery function. The nucleic acid contains, from the 5?-side to the 3?-side, a 5?-side region (Xc), a linker region (Lx), an inner region (Z), a linker region (Ly) and a 3?-side region (Yc) in this order, wherein the inner region (Z) is constituted by linkage of the inner 5?-side region (X) and the inner 3?-side region (Y), the 5?-side region (Xc) is complementary to the inner 5?-side region (X), the 3?-side region (Yc) is complementary to the inner 3?-side region (Y), at least one of the inner region (Z), the 5?-side region (Xc) and the 3?-side region (Yc) comprises an expression inhibitory sequence that inhibits expression of a target gene, and at least one of the 5?-terminus, the 3?-terminus, the linker region (Lx) and the linker region (Ly) is bound to a bio-related substance.

Abstract: The invention provides a single-stranded nucleic acid capable of inhibiting expression of a target gene having a delivery function. The nucleic acid contains, from the 5?-side to the 3?-side, a 5?-side region (Xc), a linker region (Lx), an inner region (Z), a linker region (Ly) and a 3?-side region (Yc) in this order, wherein the inner region (Z) is constituted by linkage of the inner 5?-side region (X) and the inner 3?-side region (Y), the 5?-side region (Xc) is complementary to the inner 5?-side region (X), the 3?-side region (Yc) is complementary to the inner 3?-side region (Y), at least one of the inner region (Z), the 5?-side region (Xc) and the 3?-side region (Yc) comprises an expression inhibitory sequence that inhibits expression of a target gene, and at least one of the 5?-terminus, the 3?-terminus, the linker region (Lx) and the linker region (Ly) is bound to a bio-related substance.

Abstract: The invention provides a single-stranded nucleic acid capable of inhibiting expression of a target gene having a delivery function. The nucleic acid contains, from the 5?-side to the 3?-side, a 5?-side region (Xc), a linker region (Lx), an inner region (Z), a linker region (Ly) and a 3?-side region (Yc) in this order, wherein the inner region (Z) is constituted by linkage of the inner 5?-side region (X) and the inner 3?-side region (Y), the 5?-side region (Xc) is complementary to the inner 5?-side region (X), the 3?-side region (Yc) is complementary to the inner 3?-side region (Y), at least one of the inner region (Z), the 5?-side region (Xc) and the 3?-side region (Yc) comprises an expression inhibitory sequence that inhibits expression of a target gene, and at least one of the 5?-terminus, the 3?-terminus, the linker region (Lx) and the linker region (Ly) is bound to a bio-related substance.

Abstract: The invention provides a single-stranded nucleic acid capable of inhibiting expression of a target gene having a delivery function. The nucleic acid contains, from the 5?-side to the 3?-side, a 5?-side region (Xc), a linker region (Lx), an inner region (Z), a linker region (Ly) and a 3?-side region (Yc) in this order, wherein the inner region (Z) is constituted by linkage of the inner 5?-side region (X) and the inner 3?-side region (Y), the 5?-side region (Xc) is complementary to the inner 5?-side region (X), the 3?-side region (Yc) is complementary to the inner 3?-side region (Y), at least one of the inner region (Z), the 5?-side region (Xc) and the 3?-side region (Yc) comprises an expression inhibitory sequence that inhibits expression of a target gene, and at least one of the 5?-terminus, the 3?-terminus, the linker region (Lx) and the linker region (Ly) is bound to a bio-related substance.