The difference between Oligo(dT) Primer and Random Primers

1, Oligo(dT) Primer can also be called oligo-thymine Primer, is only thymine composed of oligonucleotide chain, the length range between 10 to 20 bases, commonly used Oligo(dT) Primer has 15 bases, 16 bases and 18 bases.

The Oligo(dT) Primer takes advantage of the principle of complementary base pairing and the fact that mRNA contains A poly (A) tail. Due to this feature, the Oligo(dT) Primer can only pair with mRNA and complete reverse transcription under suitable conditions. Prokaryotic RNA, eukaryotic rRNA, and tRNA do not have A poly (A) tail, so the Oligo(dT) Primer cannot be used as a template for reverse transcription primers. This limits the number and variety of total Cdnas obtained after reverse transcription. In addition, if the mRNA is too long, it may form secondary structures, and the amplification of Oligo(dT) Primer will also be difficult. It is also suggested that primers should be selected according to the need during reverse transcription.

2. Random Primers refers to random primers, usually 6 bases or 9 bases in length. It is a kind of mixture, in which four bases can appear randomly at each position, such as AATCGC, TTAAGCG, etc., so there can be 46 or 49 combinations.

Random primers can bind to almost all Rnas, including mRNA, tRNA, and rRNA, depending on the love situation of base homosexuality. Therefore, Random Primers is applicable to the reverse transcription reaction of all Rnas such as mRNA, tRNA and rRNA, as well as RNA with long or hairpin structure, with no restriction on species, and can be used by viruses, bacteria, plants, animals, etc.

3. At present, some companies and laboratories advocate the mixed use of Oligo(dT) and Random Primers to ensure a more complete cDNA.