Figure 1. Evidence of Ch5 monosomy in the mutant Sor55 or Sor60.

Electrophoretic karyotype is prepared using a contour-clamped homogeneous electric field apparatus (Bio-Rad Laboratories, Hercules, CA). Shown are precisely separated smaller Ch5, Ch6, and Ch7 of the parental strain 3153A, as well as of its derivatives Sor55 and Sor60. Homologous chromosomes are designated a or b. Under this running condition [3] that is optimizing smaller chromosomes, the longer chromosomes are compressed on the top of a gel. Separation of longer chromosomes is not presented. Note similar brightness of Ch5a or Ch5b in all strains (confirmation with densitometry is not presented). In contrast, a band containing co-migrating Ch6b and Ch7a is stained approximately twice stronger.