On p. 209 (top left column mid-section) of "The Molecular Biology of
the Yeast Saccharomyces...." (Broach et al), it states mating-type
control is much more severe in cells that show carbon source regulation
of Ty transcription. What does this mean? Is the mating-type
switching repressed due to the type of carbon source?
Also on p. 209 (left column "c." section), "Regulatory Sequences
Defined...", what is the I site? Is it like an enhancer?
The statement was made that Ty transcript levels are regulated to
signals from the metabolic state, mating type and DNA damage.
How is mating-type control tied in with transposition? Is it
of the same molecules in the system like in cassette switching?
Since UV irradiation increases Ty transcript levels, would this
repair or recombination mechanisms having a role in the
On p.211, left column, section "2. Regulation of the sigma promoter"
(Ty3), my first question is on the first sentence, "Transcription from
the...". What is haploid-constitutive? I assume this means you have a
strain which is haploid all the time. How is this accomplished? Does
"mating-type-repressed" mean the mt switching is turned off and is this
accomplished by mutation of one of the silent cassettes?
Biological & Biochemical Sciences
University of Houston
Houston, TX 77204-5934