An electrophoretic karyotype for yeast.

Abstract
The chromosomal DNA molecules of a standard laboratory strain of Saccharomyces cerevisiae were separated into 12 well-resolved bands by orthogonal-field-alternation gel electrophoresis. DNA .cntdot. DNA hybridization probes derived from cloned genes were used to correlate this banding pattern with yeast''s genetically defined chromosomes. The 12 bands are shown to represent 9 singlets and 3 comigrating doublets, thereby accounting for 15 chromosomes that were identified as I-XI and XIII-XVI. Because the 3 comigrating doublets could be readily resolved in certain laboratory yeast strains that contain chromosome-length polymorphisms relative to the standard strain, all 15 of these chromosomes could be displayed as a single band in at least of 4 strains that were studied. A 16th chromosome (number XII), which is known to contain the genes for rRNA, does not reproducibly enter the gels. By making use of the band identifications, the previously unmapped fragment F8 was assigned to chromosome XIII. With the possible exception of chromosomes that differ greatly in size or electrophoretic behavior from all the known chromosomes, the results appear to define a complete "electrophoretic karyotype" for yeast.