R and Y are variable nucleotides. R: Purine (adenine or guanine). Y: Pyrimidine (thymine or cytosine) (http://www.chem.qmul.ac.uk/iubmb/misc/naseq.html)
R và Y là các nucleotide biến. R: purine (adenine hoặc guanine). Y: Pyrimidine (thymine hoặc cytosine) (http://www.chem.qmul.ac.uk/iubmb/misc/naseq.html)