Rapid identification of mutation-complementing restriction fragments from Aspergillus nidulans cosmids

William E. Timberlake, Margaret T. Boylan, Michael B. Cooley, Peter M. Mirabito, Eileen B. O'Hara, Catherine E. Willett

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


We isolated recombinant DNA cosmid clones that complemented certain mutations in Aspergillus nidulans when covalently closed circular DNA was used to transform cells. We found that DNA from the cosmids was capable of genetic complementation even after digestion to completion with restriction endonucleases that recognize six base pair sequences. Individual restriction fragments were isolated from agarose gels and tested for their ability to complement mutations in cotransformation experiments by using either the A. nidulans trpC or argB gene as selective marker. Specific fragments complemented the mutations. This procedure permits rapid identification of small DNA fragments, from large cosmid inserts, that contain all or part of specific genes, without subcloning the fragments or constructing restriction maps for the cosmids. It therefore significantly simplifies mapping of genes cloned by cosmid complementation or mutations in Aspergillus by providing a starting point for the application of conventional molecular mapping techniques.

Original languageEnglish
Pages (from-to)351-355
Number of pages5
JournalExperimental Mycology
Issue number4
StatePublished - Dec 1985

Bibliographical note

Funding Information:
This work was supported by USPHS Grant GM30349 to W.E.T. M.T.B., M.B.C., and C.E.W. were provided support from a training grant funded by the McKnight Foundation.


  • Aspergillus nidulans
  • cotransformation
  • gene cloning
  • gene mapping

ASJC Scopus subject areas

  • Applied Microbiology and Biotechnology


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