Elmar Maier

High resolution cosmid and P1 maps spanning the 14 Mb genome of the fission yeast S. pombe

Gridded on high density filters, a P1 genomic library of 17-fold coverage and a cosmid library of 8 genome equivalents, both made from S. pombe strain 972h-, were ordered by hybridizing genetic markers and individual clones from the two libraries. Yeast artificial chromosome (YAC) clones covering the entire genome were used to subdivide the libraries, and hybridization of short oligonucleotides and DNA pools made from randomly selected cosmids provided further mapping information. Restriction digests were generated as an independent confirmation of the clone order. The high resolution clone map was aligned to the genetic map and the physical Notl and YAC maps. The usefulness of the various mapping techniques and cloning procedures could be assessed upon the different data sets.

11 – Integrated Genome Mapping by Hybridization Techniques

This chapter discusses integrated genome mapping by hybridization techniques. Hybridization techniques provide the means for an efficient physical mapping. High-coverage clone libraries are generated and stored. It is found that whole libraries become accessible, with the clones nevertheless individually identifiable and easily retrievable. Work can be done in many places simultaneously on the same material and redundancies in library generation and characterization are much avoided. Due to the common nature of the information obtained, hybridization results are instantly correlated and easily interrelated. It is found that particularly, a combination of long-range and short-distance mapping considerably accelerates an ordering process and especially, the gap closing in both systems is simplified. In an apparent extension to the mere physical mapping, cDNA and exonic libraries can be used as probe sources, thus directly combining the ordering of the genomic DNA with the localization of transcribed sequences. It is suggested that by a simultaneous hybridization to the genomic and back to the transcriptional libraries, such experiments would additionally produce results on sequence homologies between transcribed sequences.