A set of three probes specific to sequences located in the 5’-ETS, ITS1 and ITS2, and together hybridizing to most known pre-rRNA intermediates was used.

The sequence of the probes used is as follows:

• 5’-ETS, CGGAGGCCCAACCTCTCCGACGACAGGTCGCCAGAGGACAGCGTGTCAGC
• ITS1, CCTCGCCCTCCGGGCTCCGTTAATGATC
• ITS2, CTGCGAGGGAACCCCCAGCCGCGCA