Which are the most under-represented oligonucleotides in higher eukaryote genomes?
['Unusual frequencies of certain alternating purine-pyrimidine runs in natural DNA sequences', 'Octanucleotides are the most deficient, occurring at only 60% of the frequency expected in random sequences. An unexpectedly high proportion of these octamers consists of alternating tetramers with the repeat structure (PuPyPuPy)2 or (PyPuPyPu)2', 'For dinucleotides, TA is almost universally under-represented, with the exception of vertebrate mitochondrial genomes, and CG is strongly under-represented in vertebrates and in mitochondrial genomes', 'For trinucleotides, GCA.TGC tends to be under-represented in phage, human viral, and eukaryotic sequences, and CTA.TAG is strongly under-represented in many prokaryotic, eukaryotic, and viral sequences', 'The dinucleotide CpG is significantly under-represented in vertebrate DNA and is usually methylated', 'One such pattern recognition system is based on unmethylated CpG dinucleotides in particular sequence contexts (CpG motifs); these motifs are common in bacterial DNA but are under-represented ("CpG suppression") and methylated in vertebrate DNA', 'We argue that the significant under-represented motif pattern of CpG in an AU context--which is found in both the ssRNA viruses and innate genes, and has decreased throughout the history of H1N1 influenza replication in humans--is immunostimulatory and has been selected against during the co-evolution of viruses and host innate immune genes']
['The oligonucleotides containing the CG and TA dinucleotide are generally under-represented in higher eukaryote genomes', 'TpA is the most underepresented dinucleotide followed closely by CpG. For trinucleotides, GCA/TGC tends to be under-represented in phage, human viral, and eukaryotic sequences, and CTA/TAG is strongly under-represented in many prokaryotic, eukaryotic, and viral sequences. For higher lengts alternating Purine/Pyrimidine tracts are underepresented up to 60%.', 'Oligonucleotides containing CG and TA dinucleoides']
['TA', 'CG', '(PuPy)n', 'GCA/TGC', 'CTA/TAG']