1022-7954/03/3906- $25.00 © 2003
Russian Journal of Genetics, Vol. 39, No. 6, 2003, pp. 610–617. Translated from Genetika, Vol. 39, No. 6, 2003, pp. 739–747.
Original Russian Text Copyright © 2003 by Rakauskaite, Citavicius.
Transduction of signals reﬂecting the state of the
environment is regulated by a set of protein kinases in
haploid and diploid cells of yeast
[1–3]. Activating a particular kinase cascade,
environmental signals determine a certain response of
the cell . The broadest spectrum of effects on cell pro-
cesses and on regulation of other signaling pathways is
characteristic of the products of genes involved in signal
transduction through the pathway depending on Ras-
cyclic adenosine monophosphate (Ras/cAMP) [1, 4–7].
Changes in activity of the Ras/cAMP signal transduction
pathway result in
in expression of certain
phenotypic traits .
Sporulating ability of diploids is an important phe-
notypic characteristic of the Ras/cAMP signaling [1, 2].
Mutations of the structural
) gene, which
codes for adenylate cyclase, and the
genes, which are involved in its regulation, have been
shown to reduce the intracellular cAMP pool [4, 8, 9].
Diploid cells homozygous for these mutations display
meiosis and sporulation even in a complete medium
[9, 10]. Mutations of the
gene, which codes for
the regulatory subunit of the cAMP-dependent protein
kinase, suppress the
[1, 10]. Homozygosity for the
meiosis and sporulation .
, meiosis is induced by starvation.
Starvation also leads to the reduction of the intracellu-
lar cAMP pool, which, in its turn, inhibits cAMP pro-
tein kinase . This implicates the Ras/cAMP signal
transduction pathway in controlling cell transition to
meiosis. Starvation is also known to enhance expres-
sion of the
meiosis activator gene. It is this gene
that mediates the role of the Ras/cAMP pathway in the
regulation of meiosis .
Phenotypic characterization of seven haploid strains
of the Peterhof collection of yeast genetic lines sug-
gested mutations of the genes controlling the
Ras/cAMP signal transduction system for six of these.
Here we report the results of phenotypic analysis of the
activity of the Ras/cAMP metabolic pathway and evaluate
sporulation in diploids obtained by crossing the haploid
strains, which we characterized previously .
MATERIALS AND METHODS
We used seven haploid strains of the Peter-
hof genetic collection of yeast :
), 7A-P192 (
), and 15B-P4 (
, wild type). Diploids
DV201, DV202, DV203, and DV204 were obtained by
strains with haploid 7A-P192. The
haploids were also crossed with strain
The Genetic Control of Cell Growth and Development
: Disturbed Sporulation
in Diploids with a Decreased Activity of the Ras/cAMP Signal
R. Rakauskaite and D. Citavicius
Department of Microbiology and Physiology of Plants, Vilnius University, Vilnius, 2009 Lithuania;
fax: (3702)33-00-68; e-mail: firstname.lastname@example.org
Received April 26, 2002
—Seven haploid strains (four with the
mating type and three with the
mating type) were
selected from the Peterhof genetic collection of yeast. Previous phenotypic analysis assigned six of these strains
to a physiological group of strains with changed activity of the Ras/cAMP signal transduction pathway. The
haploids were crossed, and the resulting 12 diploids showed higher glycogen accumulation, tolerance to heat
shock and nitrogen starvation, and sporulation in complete media. Ten of the diploids expressed the hypersporu-
lation phenotype (higher sporulation efﬁciency). The phenotypic characters of these ten diploids suggested a
reduced activity of the Ras/cAMP pathway. All 12 diploids were tested for sporulation and production of two
groups of asci (those with one or two spores and those with three or four spores) as dependent on culture con-
ditions (21, 30, or 34
C; standard sporulation medium or a complete medium containing potassium acetate or
glycerol in place of glucose). Sporulation proved to depend on temperature and medium composition. The
results are collated with the data on yeast phenotypes associated with a lower activity of the Ras/cAMP signal