[Chromosome polymorphism in the yeast Saccharomyces].

Area of Science:

• Molecular Biology
• Genetics
• Yeast Research

Background:

• Chromosomal band patterns are key identifiers for yeast strains.
• Variability in DNA band quantity and mobility exists among natural yeast strains.
• Understanding karyotype stability is crucial for Saccharomyces cerevisiae genetics.

Purpose of the Study:

• To analyze chromosomal band pattern variability in Saccharomyces cerevisiae.
• To investigate the segregation patterns and stability of electrophoretic karyotypes in hybrid progeny.
• To determine the impact of genetic manipulations on chromosomal polymorphism.

Main Methods:

• Pulse-field gel electrophoresis was employed to analyze chromosomal DNA band patterns.
• Comparative analysis of band patterns was performed across different Saccharomyces strains and species.
• Hybridization experiments and subsequent crosses were conducted to study segregation and polymorphism.

Main Results:

• Natural Saccharomyces strains exhibited differences in DNA band quantity and electrophoretic mobility.
• Hybrid progeny showed irregular segregation, new bands, and altered mobility, indicating genetic instability.
• Reverse crosses and selection for specific alleles/plasmids induced transient polymorphism followed by stabilization.

Conclusions:

• Electrophoretic karyotyping reveals significant chromosomal polymorphism in Saccharomyces.
• Hybridization and genetic selection can dynamically alter karyotype patterns.
• Karyotype stabilization occurs over generations, though some traits like chromosome III dimorphism can persist.