The reliability of the Aspergillus nidulans physical map

Here we report an evaluation of the Aspergillus nidulans physical map (a cosmid contig map) emphasizing quantification and description of obvious mapping errors. Classification and appraisal of mapping errors should be helpful to researchers working on particular regions of the map. We estimate between 47 (4.1%) and 63 (5.4%) probe/clone-linking errors. The majority of identified false links (38) permit reciprocal exchanges among linking clones located on disconnected mapping regions. The order of adjacent clones or probes on the affected contigs remains unchanged. In addition we describe an Internet-accessible resource in which genetic and physical maps were integrated through a graphic interface. A simple search engine allows retrieval of cosmids from redundant clone lists and provides links to the minimal clone order. Integration of genetic and physical maps provides an additional level of accountability in which mapping discrepancies are visually located.