The presence of ncRNA in random sequences. RNA was subjected to primer extension with the oligonucleotides listed in the Additional File 2. The extension products were separated on a 6% polyacrylamide 7 M urea gel next to a labeled marker (pBR322 MspI digest). The size of the marker in nt is indicated. The lanes for the different candidates are marked by their identification number. To control for equal loading, the RNA was extended with oligonucleotide complementary to U3 snoRNA. The relevant extension products are marked with arrows.