A method for determining nucleotide sequences of RNA polynucleotides, the method comprising: a) providing a plurality of RNA fragments obtained from the RNA polynucleotides; b) enzymatically phosphorylating 5' ends of the plurality of RNA fragments to provide a plurality of RNA fragments comprising mono-phosphorylated 5' ends; c) enzymatically dephosphorylating 3' ends of the plurality of RNA fragments to provide a plurality of RNA fragments comprising free 3' hydroxyls; wherein a ligase enzymatically phosphorylates the 5' ends of the plurality of RNA fragments to provide a plurality of RNA fragments comprising mono-phosphorylated 5' ends, and wherein the ligase enzymatically dephosphorylates 3' ends of the plurality of RNA fragments to provide the plurality of RNA fragments comprising the free 3' hydroxyls; d) enzymatically adenylylating phosphorylated 5' ends of the plurality of RNA fragments to provide a plurality of 5' mono-adenylated RNA fragments; e) enzymatically polyadenylating 3' ends of the plurality of RNA fragments comprising the free 3' hydroxyls to provide a plurality of RNA fragments comprising polyadenylated 3' ends; wherein the enzymatically adenylating the phosphorylated 5' ends of the plurality of RNA fragments, and the polyadenylating of the 3' ends of the plurality of RNA fragments, is performed using a cyclase and a polymerase, wherein the cyclase comprises an RtcA enzyme; f) ligating oligonucleotide adapters to the 5' ends of the plurality of 5' mono-adenylated RNA fragments, the oligonucleotide adapters optionally comprising a DNA/RNA hybrid 3' end, the DNA/RNA hybrid 3' end optionally comprising rCrC-OH or rGrG-OH as the RNA component of the DNA/RNA hybrid, to provide a plurality of RNA fragments comprising the oligonucleotide adapters at the 5' ends; g) generating cDNAs from the plurality of RNA fragments of f); h) amplifying the cDNAs; and i) determining nucleotide sequences of the cDNAs, thereby determining the nucleotide sequences of the RNA polynucleotides. a) providing a plurality of RNA fragments obtained from the RNA polynucleotides; b) enzymatically phosphorylating 5' ends of the plurality of RNA fragments to provide a plurality of RNA fragments comprising mono-phosphorylated 5' ends; c) enzymatically dephosphorylating 3' ends of the plurality of RNA fragments to provide a plurality of RNA fragments comprising free 3' hydroxyls; wherein a ligase enzymatically phosphorylates the 5' ends of the plurality of RNA fragments to provide a plurality of RNA fragments comprising mono-phosphorylated 5' ends, and wherein the ligase enzymatically dephosphorylates 3' ends of the plurality of RNA fragments to provide the plurality of RNA fragments comprising the free 3' hydroxyls; d) enzymatically adenylylating phosphorylated 5' ends of the plurality of RNA fragments to provide a plurality of 5' mono-adenylated RNA fragments; e) enzymatically polyadenylating 3' ends of the plurality of RNA fragments comprising the free 3' hydroxyls to provide a plurality of RNA fragments comprising polyadenylated 3' ends; wherein the enzymatically adenylating the phosphorylated 5' ends of the plurality of RNA fragments, and the polyadenylating of the 3' ends of the plurality of RNA fragments, is performed using a cyclase and a polymerase, wherein the cyclase comprises an RtcA enzyme; f) ligating oligonucleotide adapters to the 5' ends of the plurality of 5' mono-adenylated RNA fragments, the oligonucleotide adapters optionally comprising a DNA/RNA hybrid 3' end, the DNA/RNA hybrid 3' end optionally comprising rCrC-OH or rGrG-OH as the RNA component of the DNA/RNA hybrid, to provide a plurality of RNA fragments comprising the oligonucleotide adapters at the 5' ends; g) generating cDNAs from the plurality of RNA fragments of f); h) amplifying the cDNAs; and i) determining nucleotide sequences of the cDNAs, thereby determining the nucleotide sequences of the RNA polynucleotides.