Abstract: An object of the present invention is to provide a polynucleotide having a modification site in a translated region with translation activity retained. The object can be achieved by a polynucleotide containing a translated region from a start codon to a stop codon, in which the translated region contains n codons, and the n is a positive integer of 2 or more, each of the n codons contains first, second and third nucleotides, and the first nucleotides in at least two codons of the n codons are sugar modified nucleotides.

Abstract: A primer for amplifying a nucleic acid having a structure represented by formula (1): where A1 represents —S—, —S—S—, or —Se—, B represents a base, and R1 represents a decomposable protecting group, and the symbol * represents a bond to a sugar of an adjacent nucleotide. A device for producing double-stranded DNA includes: a forward primer and a reverse primer, having a structure represented by formula (1); a PCR device for forming double-stranded DNA with 3?-recessed ends by performing multiple cycles of PCR by using a template DNA as a template; Klenow fragment for making the 3? ends blunt; and a photoirradiation unit for deprotecting R1 and forming a sticky end with a 3?-protruding end.

Abstract: A primer for amplifying a nucleic acid having a structure represented by the formula (1): where B represents a base, R1 represents a decomposable protecting group, and R2 represents hydrogen or a hydroxyl group, and the symbol * represents a bond to a sugar of an adjacent nucleotide. A device for producing double-stranded DNA, includes: a forward primer and a reverse primer, having a structure represented by formula (1); a PCR device for forming double-stranded DNA with 3?-recessed ends by performing multiple cycles of PCR by using a template DNA as a template; and a photoirradiation unit for deprotecting R1 and forming a sticky end with a 3?-protruding end.