Sexual hormones in yeast.

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Haploid strains of Saccharomyces cerevisiae exhibit mating-type specific behaviors.
• Cellular communication mechanisms in yeast are crucial for understanding their life cycle.

Purpose of the Study:

• To isolate and characterize hormone-like substances secreted by Saccharomyces cerevisiae.
• To investigate the biological activity and chemical properties of these secreted substances.
• To determine the role of mating-type genes in hormone production and cellular response.

Main Methods:

• Isolation of substances from culture media of haploid yeast strains.
• Assaying cell-expanding activity on different mating types.
• Testing inhibitory effects of actinomycin D, chloramphenicol, and cycloheximide.
• Evaluating heat stability, dialyzability, and extractability with methylene chloride.

Main Results:

• Two distinct hormone-like substances were identified: one produced by a-type cells (a hormone) and another by α-type cells (α hormone).
• a hormone induced cell expansion in α-type cells, while α hormone induced cell expansion in a-type cells.
• The cell-expanding action of a hormone was sensitive to actinomycin D, chloramphenicol, and cycloheximide.
• a hormone was found to be heat-stable and dialyzable, and both hormones were extractable with methylene chloride.
• Mating-type genes were implicated in controlling both hormone production and cellular responsiveness.

Conclusions:

• Saccharomyces cerevisiae produces specific mating hormones that mediate cell-specific responses.
• These hormones play a role in yeast mating and are under genetic regulation by mating-type genes.
• The identified hormones possess distinct biochemical properties and biological activities relevant to yeast cell communication.