Table 3.

Mono- and dinucleotide frequencies of coding and non-coding sequences in Drosophila species

Mononucleotide	D. melanogaster	D. erecta	D. pseudoobscura	D. willistoni	D. littoralis
			Coding
A = T	0.231	0.222	0.220	0.265	0.224
G = C	0.269	0.278	0.280	0.235	0.276
			Non-coding
A = T	0.300	0.295	0.281	0.324	0.305
G = C	0.200	0.205	0.219	0.176	0.195
Dinucleotide	D. melanogaster	D. erecta	D. pseudoobscura	D. willistoni	D. littoralis
			Coding
TA	0.032	0.028	0.027	0.046	0.030
AT	0.057	0.053	0.056	0.080	0.058
AA = TT	0.057	0.052	0.049	0.076	0.056
AC = GT	0.054	0.053	0.051	0.051	0.051
AG = CT	0.063	0.064	0.064	0.057	0.059
GA = TC	0.067	0.068	0.067	0.063	0.055
CA = TG	0.075	0.074	0.077	0.078	0.082
CG	0.064	0.068	0.068	0.046	0.073
GC	0.081	0.085	0.091	0.067	0.109
CC = GG	0.067	0.072	0.071	0.054	0.061
			Non-coding
TA	0.069	0.068	0.058	0.080	0.075
AT	0.086	0.084	0.077	0.094	0.089
AA = TT	0.110	0.106	0.094	0.126	0.111
AC = GT	0.052	0.052	0.052	0.053	0.053
AG = CT	0.052	0.053	0.058	0.051	0.052
GA = TC	0.053	0.053	0.059	0.052	0.048
CA = TG	0.068	0.068	0.070	0.066	0.071
CG	0.037	0.040	0.039	0.025	0.037
GC	0.052	0.056	0.057	0.038	0.058
CC = GG	0.043	0.044	0.052	0.033	0.035

Values for D. melanogaster are genome-wide averages based on Release 3 sequences/annotations [9,14] and include unmapped scaffolds derived from heterochromatic regions (see [83]). Values in bold indicate the most frequently used mono- or dinucleotide. Frequencies of complementary mono- and dinucleotides were averaged to account for the double-stranded nature of DNA.