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Yeast
Colony Group |
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Our Research |
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YCG group studies development and differentiation of yeast colonies and biofilms. Yeast cells growing on solid surfaces
form multicellular structures, colonies, with typical morphologies and organization. During colony development yeast
cells differentiate and form specifically localized cell subpopulations that
perform particular tasks within the structure. Yeast colonies thus behave
like primitive multicellular organisms, in that cells communicate,
synchronize their development and differentiate into primitive
"tissues". Cell differentiation often contributes to longevity of
the whole colony population. [reviews 1, 2, 3, 4]. Current
research includes two major ongoing lines: 1) Development and
differentiation of biofilm colonies formed by
wild Saccharomyces cerevisiae strains. In contrast to smooth
colonies formed by laboratory strains, wild S.
cerevisiae strains isolated
from nature form colonies with structured morphology with features similar to natural
yeast biofilms. These biofilm colonies exhibit a characteristic internal
organization and differentiate during development to form specifically
localized subpopulations that develop different defense mechanisms, providing
colonies with high environmental resistance. Thus, cell subpopulations with
active multidrug resistance transporters as well as those that produce
extracellular matrix are formed and specifically localized within the
colonies. Wild S. cerevisiae strains are able to
"domesticate" when cultivated on rich glucose media, reorganize
their colonial life-style and switch off some of their protective mechanisms.
Domestication is a reversible process. [5, 6, 7, 8] The long-term goal is
to identify new regulatory mechanisms that contribute to biofilm colony
development and cell differentiation with particular emphasis on mechanisms
involved in environmental resistance as well as those that regulate yeast
strain domestication. 2) Development and
differentiation of smooth colonies formed by laboratory and domesticated
strains of S. cerevisiae. One of the
characteristic attributes of multicellular organisms is their ability to emit
and receive signals over long distances. For this long-range, inter-colony
signaling yeast colonies use a simple volatile compound, ammonia, produced by
colonies in pulses. Ammonia action results in synchronization of the
development in neighboring colonies and in Candida
mogii colonies is accompanied by characteristic cell and colony
morphology changes. The transition of colonies from acidic phase to the
ammonia production phase (alkali phase) is connected with extensive adaptive
metabolic reprogramming that is important for longevity of the population.
During this transition colonies differentiate into two major cell
subpopulations - U cells localized in upper and L cells in lower regions of
colonies. U cells are vital stress-resistant cells that activate adaptive
metabolism and release high levels of ammonia, whereas L cells are starving,
stress sensitive cells that activate different hydrolytic mechanisms,
involved in the release of nutrients to feed long-lived U cells.
Interestingly, U cells metabolically resemble cells of solid tumors of
mammals and seem to be atypically regulated as compared with individual yeast
cells grown in liquid cultures. [9, 10, 11, 12, 13, 14, 15, 16] The long-term goal is
to identify new regulatory mechanisms that contribute to ammonia-related cell
differentiation and formation of U and L cells. As our recent data showed the
important role of mitochondrial signaling in colony differentiation [17], identification of
regulators that contribute to mitochondria-driven regulations, specific to
individual cell subpopulations is one of the priority aims. A new research line has been initiated
recently that is focused on identification of selected differentiation
processes in colonies and biofilms of pathogenic yeast and during interaction
with host cells.
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