Organization of the 5.8S, 16–18S,and 23–28S ribosomal RNA genes of Cephalosporium acremonium

Summary A 9.2 kb Pst1 restriction fragment, repeated tandemly head-to-tail in the genome, contains the 5.8S, 16–18S, and 23–28S ribosomal RNA (rRNA) genes of Cephalosporium acremonium, a filamentous fungus used at the industrial scale for production of cephalosporin antibiotics. These rRNA genes were located in Pst1 digests of C. acremonium genomic DNA using a hybridization probe that contained the 5.8S, 18S, and 25S rRNA genes from the yeast Saccharomyces cerevisiae. This probe was also used in screening a recombinant lambda library to identify phage carrying rRNA genes of C. acremonium. Yeast rRNA genes contained separately on individual ³²P-labeled plasmids were used to demonstrate that a cloned 7.2 kb C. acremonium sequence, represented in the repeated 9.2 kb Pst1 fragment, contained DNA from the C. acremonium 5.8S, 16–18S, and 23–28S rRNA genes. These genes were ordered with the 5.8S gene located between the 16–18S and 23–28S rRNA genes. The order of the 16–18S, 5.8S, and 23–28S rRNA genes observed in C. acremonium is the same as that observed in rRNA repeats of many other lower eucaryotes, e.g. S. cerevisiae, Aspergillus nidulans, and Neurospora crassa.