Saccharomyces cerevisiae gene expression changes during rotating wall vessel suspension culture

Abstract

This study utilizes Saccharomyces cerevisiae to study genetic responses to suspension culture. The suspension culture system used in this study is the high-aspect-ratio vessel, one type of the rotating wall vessel, that provides a high rate of gas exchange necessary for rapidly dividing cells. Cells were grown in the high-aspect-ratio vessel, and DNA microarray and metabolic analyses were used to determine the resulting changes in yeast gene expression. A significant number of genes were found to be up- or downregulated by at least twofold as a result of rotational growth. By using Gibbs promoter alignment, clusters of genes were examined for promoter elements mediating these genetic changes. Candidate binding motifs similar to the Rap1p binding site and the stress-responsive element were identified in the promoter regions of differentially regulated genes. This study shows that, as in higher order organisms, S. cerevisiae changes gene expression in response to rotational culture and also provides clues for investigations into the signaling pathways involved in gravitational response.

Microbial Responses to Microgravity and Other Low-Shear Environments

“…A great deal of progress has been made in understanding certain aspects of microbial mechanotransduction, for example, mechanisms used by bacteria to respond to changes in osmotic gradients (7,40,85). Recently, studies have also documented that microbes can sense and respond to changes in culture conditions when grown in the buoyant, low-fluid-shear environment of microgravity (21,52,60,82). Moreover, it has been hypothesized that cells sense changes in mechanical forces, including shear and gravity, at their cell surface (48).…”

“…Although it is true that the gravity force vector present in a liquid environment on Earth is very different in magnitude from that present in the space atmosphere, the low-shear buoyant sensation experienced in both environments is very similar. There is increasing evidence not only that entire organisms sense and respond physiologically to low-shear, buoyant environments but also that cells respond at the molecular level to this environment (43,52,81,106,107).…”

“…Although designed with spaceflight implications in mind, it is becoming increasingly evident that the RWV may find its greatest utility in groundbased applications such as (i) the formation and engineering of 3-D tissue aggregates that structurally and functionally resemble in vivo tissues (80, 82a, 101); (ii) understanding of the molecular mechanisms used by cells to sense and respond to LSMMG and the identities of the genes involved in response to this signaling pathway (43,48,52,107); (iii) understanding of how microbial pathogens modulate their virulence both on Earth and in space, which could provide clues to the functioning of known virulence systems or to the identification of novel, uncharacterized bacterial virulence strategies (81,106,107); and (iv) studies to further understand microbial metabolism and physiology (21,82). This section of the review focuses on the growing body of information regarding the responses of microbes to the LSMMG growth environment of the RWV.…”

“…Recently, microarray analysis was used to examine the kinetic changes in gene expression in the yeast S. cerevisiae during culture in the RWV for different periods (52). The S. cerevisiae RWV cultures incubated at LSMMG were compared to cultures grown in identical RWV bioreactors in the 1 ϫ g orientation on a gyrorotatory shaker.…”

Inhibition of Gene Expression inEscherichia coliunder Hypergravity

“…There have been investigations into the effects of gravity on cells. With regard to low gravity, several studies have demonstrated that microgravity affects the regulation of gene expression in microorganisms, 1,2) but the effects of hypergravity have not been fully investigated for microorganisms, especially bacteria. In the fission yeast Schizosaccharomyces pombe, hypergravity produced by centrifugation stimulated marked activation of the stress-activated protein kinase pathway and the cell-integrity pathway.…”