Evolutionary conservation of the transcribed spacer sequences of the rDNA repeat unit in three species of the genus Aspergillus.

We have cloned and sequenced the two intervening transcribed spacers in the rDNA repeat unit of three Aspergillus species--A. nidulans, A. awamori and A. wentii. The A. wentii and A. awamori spacers are almost identical and share a high degree of homology with the A. nidulans spacers. All spacers have a high G-C content (66%-76%) and the potential of forming complex secondary structures, which may indicate that they play a role in the maturation of pre-rRNA molecules.