ABSTRACT
Petit-High Pressure Carbon Dioxide (p-HPCD) is a promising nonthermal technology for foods pasteurization. Cluster analysis of gene expression profiles of Saccharomyces cerevisiae exposed to various stresses exhibited that gene expression profile for p-HPCD stress (0.5MPa, 25°C) was grouped into a cluster including profiles for Sodium Dodecyl Sulfate and Roundup herbicide. Both are detergents that can disorder membrane structurally and functionally, which suggests that cell membrane may be a target of p-HPCD stress to cause cell growth inhibition. Through metabolomic analysis, amount of S-Adenosylmethionine (AdoMet) that is used as methyl donor to participate in phosphatidylcholine synthesis via phosphatidylethanolamine (PE) methylation pathway, was increased after p-HPCD treatment for 2h. The key gene OPI3 encoding phospholipid methyltransferase that catalyzes the last two steps in PE methylation pathway was confirmed significantly induced by RT-PCR. Transcriptional expression of genes (MET13, MET16, MET10, MET17, MET6 and SAM2) related to AdoMet biosynthesis was also significantly induced. Choline as the PC precursor and ethanolamine as PE precursor in Kennedy pathway were also found increased under p-HPCD condition. We also found that amounts of most of amino acids involving protein synthesis were found decreased after p-HPCD treatment for 2h. Moreover, morphological changes on cell surface were observed by scanning electron microscope. In conclusion, the effects of p-HPCD stress on cell membrane appear to be a very likely cause of yeast growth inhibition and the enhancement of PC synthesis could contribute to maintain optimum structure and functions of cell membrane and improve cell resistance to inactivation.
Subject(s)
Carbon Dioxide/chemistry , Phosphatidylcholines/metabolism , S-Adenosylmethionine/metabolism , Saccharomyces cerevisiae/metabolism , Biocatalysis , Cluster Analysis , Metabolomics , Microscopy, Electron, Scanning , Phosphatidyl-N-Methylethanolamine N-Methyltransferase/genetics , Phosphatidyl-N-Methylethanolamine N-Methyltransferase/metabolism , Phosphatidylcholines/chemistry , Pressure , S-Adenosylmethionine/chemistry , Saccharomyces cerevisiae Proteins/genetics , Saccharomyces cerevisiae Proteins/metabolismABSTRACT
We investigated ultrastructural changes in the yeast Saccharomyces cerevisiae when exposed to compressed ethylene gas. Transmission electron microscopy (TEM) revealed that intracellular organelles in yeast cells treated with compressed ethylene at up to 0.640 MPa (6.4 atm), especially the nuclear and plasma membranes, were seriously damaged.
Subject(s)
Air Pollutants/pharmacology , Ethylenes/pharmacology , Gases/pharmacology , Pressure , Saccharomyces cerevisiae/drug effects , Saccharomyces cerevisiae/ultrastructureABSTRACT
The inhibitory action of compressed hydrocarbon gases on the growth of the yeast Saccharomyces cerevisiae was investigated quantitatively by microcalorimetry. Both the 50% inhibitory pressure (IP(50)) and the minimum inhibitory pressure (MIP), which are regarded as indices of the toxicity of hydrocarbon gases, were determined from growth thermograms. Based on these values, the inhibitory potency of the hydrocarbon gases increased in the order methane << ethane < propane < i-butane < n-butane. The toxicity of these hydrocarbon gases correlated to their hydrophobicity, suggesting that hydrocarbon gases interact with some hydrophobic regions of the cell membrane. In support of this, we found that UV absorbing materials at 260 nm were released from yeast cells exposed to compressed hydrocarbon gases. Additionally, scanning electron microscopy indicated that morphological changes occurred in these cells.
Subject(s)
Gases/toxicity , Hydrocarbons/chemistry , Hydrocarbons/toxicity , Pressure , Saccharomyces cerevisiae/drug effects , Saccharomyces cerevisiae/growth & development , Absorption/drug effects , Absorption/radiation effects , Calorimetry , Microscopy, Electron, Scanning , Saccharomyces cerevisiae/radiation effects , Saccharomyces cerevisiae/ultrastructure , Thermography , Ultraviolet RaysABSTRACT
The effect of compressed unsaturated hydrocarbon gases on the growth of the yeast Saccharomyces cerevisiae was investigated by microcalorimetry. The growth thermograms showed that unsaturated hydrocarbon gases inhibited yeast growth. As an approach to determining the comparative toxicity of unsaturated hydrocarbon gases, we determined the 50% inhibitory pressure (IP(50)) and the minimum inhibitory pressure (MIP). On the basis of the IP(50) and MIP values, the inhibitory potency of the gases increased in the order ethylene < propylene < 1-butene. Additionally, scanning electron microscopy showed that cells treated with unsaturated hydrocarbon gases were damaged, including invagination of the cell surface.
