# _Saccharomyces cerevisiae_'s Response to Dysprosium Exposure
## 4 Discussion  
_NCW2, PIR1_, and _CRH1_ expression was significantly enhanced by Dy\({}^{3+}\) addition, indicating that Dy\({}^{3+}\) affected the cell wall structure. _NCW2_ encodes GPI-anchored protein involved in cell wall remodeling, the assembly of the cell wall chitin-glucan structure, and repair of cell wall damage caused by the antifungal agent [1]. Therefore, Ncw2 protein plays a role in the cell wall integrity pathway involved in chitin and glucan balance maintenance  
Figure 3: qRT-PCR results for ATP14 in the Dy\({}^{3+}\)-treated yeast cells. Yeast RNA was extracted from cultures at 18 h and 24 h. White and black columns represent the Dy\({}^{3+}\)-free and 0.1 mM Dy\({}^{3+}\)-treated cultures, respectively. Relative expression was calculated using the \(\Delta\Delta\)Ct method. Asterisks represent a statistically significant difference (\(p<0.05\)) between samples with and without Dy\({}^{3+}\) treatment. Figure 2: qRT-PCR results for the Dy\({}^{3+}\)-treated yeast cells. Yeast RNA was extracted from cultures at 18 h and 24 h. White and black columns represent the Dy\({}^{3+}\)-free and 0.1 mM Dy\({}^{3+}\)-treated cultures, respectively. Relative expression was calculated using the \(\Delta\Delta\)Ct method. Asterisks represent a statistically significant difference (\(p<0.05\)) between samples with and without Dy\({}^{3+}\) treatment. in the yeast cell wall, and its expression is upregulated in response to cell wall stress [1]. The enhanced expression of _NCW2_ upon the addition of Dy\({}^{3+}\) suggests that Dy\({}^{3+}\) damages the cell wall. This was also demonstrated by the enhanced expression of _PIR1_ and _CRH1_. _PIR1_ encodes \(O\)-glycosylated protein required for cell wall stability by attachment to beta-1,3-glucan in the cell wall [6]. _PIR1_ expression is induced by heat shock, and its product, accompanied by the _PIR2_ product, helps to maintain the cell wall's structure by protecting it from heat shock damage [6; 7]. _CRH1_ encodes chitin transglycos, which functions in the transfer of chitin to \(\beta\)-(1-6) and \(\beta\)-(1-3) glucans in the cell wall and then prevents cell wall stress [8]. _CRH1_ expression is induced by osmotic stress (via the Hog and Stl1 pathways) resulting from cell wall damage (Zymolyase treatment) [1]. Because every gene examined is enhanced under stress conditions in the cell wall, Dy absorption by the cell wall suggests cell wall stress. Our preliminary experiments suggest that Dy induces cell wall stress, because Dy accumulated in both the cell surface and intracellular component, and they also suggest that the rate of saccharide component increase changes under Dy-absorbing conditions, while the chitin concentration tends to increase in the cell wall (unpublished data). In another experiment, it was found that intracellular oxidation induced by Dy absorption induced oxidative damage to the cellular membrane because of the enhanced expression of _OLE1_, which is an endoplasmic reticulum membrane protein; it is a \(\Delta\)-9 fatty acid desaturase involved in monounsaturated fatty acid synthesis, responsible for palmitoleic acid and oleic acid production and needed for cell membrane organization [1; 13] and its protection against damage caused by oxidative stress induced by Cd, Cu, and Cr [1]. In contrast, _ATP14_ was downregulated. _ATP14_ is known as the \"h\" subunit of the Fo section of mitochondrial H+-Fo-F1 ATP synthase (F-ATP synthase), which is involved in ATP synthase activity and ATP synthase complex assembly in mitochondria [1]. A defect in subunit h results in a respiratory-deficient phenotype by the insufficient ATP synthesis in the respiratory pathway, leading to an absence of growth on glycerol [1]. Our preliminary experiments showed that _S. cerevisiae_ could not grow on glycerol as a carbon source in a Dy-containing medium and that the cellular ATP concentration tended to decrease, while the mitochondrial function was unknown (unpublished data).