Protocol describes the production of double-stranded RNA (dsRNA) from fragments of cDNAs of candidate genes. The cDNA fragments must be cloned in plasmids with a flanking SP6 and T7 promoter (e.g., pSP72 or pCRII). The plasmid is linearized and sense and antisense RNAs are produced separately by in vitro transcription. After purification, the RNA strands are annealed to yield a dsRNA molecule suitable for RNAi in avian embryos. - [Read Production of dsRNA for RNAi in Avian Embryos Protocol]
A synthetic oligonucleotide annealed to single-stranded DNA derived from a recombinant bacteriophage M13 or phagemid template is used to prime the synthesis of complementary radiolabeled DNA. Synthesis is catalyzed by the Klenow fragment of E. coli DNA polymerase I, which extends the annealed primer for various distances along the single-stranded template DNA. - [Read Synthesis of Single-stranded DNA Probes of Defined Length from Bacteriophage M13 Templates Protocol]
The DNA Ligation protocol described here contains the steps required to join together using ligase enzyme both plasmid DNA and insert DNA fragments in order to create a new plasmid. This new ligated plasmid can be transformed after into competent bacteria to produce DNA for mini, midi or maxi-prep isolation.