- /**
- * 3.3. Pyrimidine (thymine or cytosine): Y
- *
- * Y is the symbol previously recommended [1].
- */
- ambiguityCodes.put("Y", new String[]
- { "T", "C" });
- /**
- * 3.4. Adenine or thymine: W
- *
- * Although several diverse symbols have been used for this pair, (and for
- * the reciprocal pair G+C), only two symbols have a rational basis, L and
- * W: L derives from DNA density (light; G+C - heavy - would thus be H); W
- * derives from the strength of the hydrogen bonding interaction between the
- * base pairs (weak for A+T: G +C - strong - would thus be S). However, the
- * system recommended for the three-base series (not-A = B, etc., see below,
- * section 3.8) rules out H as this would be not-G. W is thus recommended.
- */
- ambiguityCodes.put("W", new String[]
- { "A", "T" });
- /**
- * 3.5. Guanine or cytosine: S
- *
- * The choice of this symbol is discussed above in section 3.4.
- */
- ambiguityCodes.put("S", new String[]
- { "G", "C" });
- /**
- * 3.6. Adenine or cytosine: M
- *
- * There are few common features between A and C. The presence of an NH2
- * group in similar positions on both bases (Fig. 1) makes possible a
- * logically derived symbol. A and N being ruled out, M (from aMino) is
- * recommended.
- *
- *
- * Fig. 1. Origin of the symbols M and K The four bases are drawn so as to
- * show the relationship between adenine and cytosine on the one hand, which
- * both have aMino groups at the ring position most distant from the point
- * of attachment to the sugar, and between guanine and thymine on the other,
- * which both have Keto groups at the corresponding position. The ring atoms
- * are numbered as recommended [24-26], although for the present purpose
- * this has the disadvantage of giving discordant numbers to the
- * corresponding positions.
- */
- ambiguityCodes.put("M", new String[]
- { "A", "C" });
- /**
- * 3.7. Guanine or thymine: K By analogy with A and C (section 3.6), both G
- * and T have Keto groups in similar positions (Fig. 1).
- */
- ambiguityCodes.put("K", new String[]
- { "G", "T" });
- /**
- * 3.8. Adenine or thymine or cytosine: H
- *
- * Not-G is the most simple means of memorising this combination and symbols
- * logically related to G were examined. F and H would both be suitable, as
- * the letters before and after G in the alphabet, but A would have no
- * equivalent to F. The use of H has historical precedence [2].
- */
- ambiguityCodes.put("H", new String[]
- { "A", "T", "C" });
- /**
- * 3.9. Guanine or cytosine or thymine: B
- *
- * Not-A as above (section 3.8).
- */
- ambiguityCodes.put("B", new String[]
- { "G", "T", "C" });
- /**
- * 3.10. Guanine or adenine or cytosine: V
- *
- * Not-T by analogy with not-G (section 3.8) would be U but this is ruled
- * out to eliminate confusion with uracil. V is the next logical choice.
- * Note that T and U may in some cases be considered to be synonyms.
- */
- ambiguityCodes.put("V", new String[]
- { "G", "A", "C" });
- /**
- * 3.11. Guanine or adenine or thymine: D
- *
- * Not-C as above (section 3.8).
- */
- ambiguityCodes.put("D", new String[]
- { "G", "A", "T" });
- /**
- * 3.12. Guanine or adenine or thymine or cytosine: N
- */
- ambiguityCodes.put("R", new String[]
- { "G", "A", "T", "C" });