The Yeast Model

The yeast Saccharomyces cerevisiae is a useful microbiological alternative to bacteria, especially in the field of photobiology [30-32]. Several endpoints such as colonyforming ability (lethal effects), nuclear and cytoplasmic mutations (reversion due to 

EVALUATION OF PHDTOGgNOTOXiCITY (Gene converelon lAVOlvIng Trp locuel 

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Shamir, A., Shaltiel, G., Greenberg, M.L., Belmaker, R.H., and Agam, G., 2003, The effect of lithium on expression of genes for inositol biosynthetic enzymes in mouse hippocampus a comparison with the yeast model. Brain Res. Mol. Brain Res. 115 104—110. 

The model was adapted from Kontoravdi et al. (2005) for cell growth/death, nutrient uptake, and major metabolism. The model was further developed to include description of cell cycle sub-populations. The cell cycle representation was based on the yeast model of Uchiyama Shioya (1999) and the tumour cell model of Basse et al. (2003). Eq.(l)-(4) express viable cell concentration(Xv[cell L" ]) in terms of cells in Gq/Gi, S, and G2/M phases. As a simplification in notation, Gq/Gi cells will be indicated as G unless otherwise stated. Xoi, Xs, X02/M [cell L" ] are concentrations of viable cells in Gq/Gi, S, and G2/M phase, respectively, whereas Fo ,[L h" ] is the outlet flowrate. F[L] is the cell culture volume b, ki, k [h" ] are the transition rates of cells from Gi to S, S to G2, and M to Gi respectively and /[Pg.110]

Pereira, C., Coutmho, L, Soares, J., Bessa, C., Leao, M., Saraiva, L. New insights into cancer-related proteins provided by the yeast model. FEBS J 2012,279(5), 697-712. 

FIGURE 10.18 A model for the structure of the a-factor transport protein in the yeast plasma membrane. Gene duplication has yielded a protein with two identical halves, each half containing six transmembrane helical segments and an ATP-binding site. Like the yeast a-factor transporter, the multidrug transporter is postulated to have 12 transmembrane helices and 2 ATP-binding sites. 

II. PROTEIN KINASE ACTIVITY AND REGULATION OF CELL CYCLE EVENTS IN THE YEAST AND SELECTED VERTEBRATE MODEL SYSTEMS... 

Nurse Work in starfish suggested that Cdk activity remained quite high, so that is the simplest model, and that is likely to be the case in fission yeast as well. We are cataloguing all the different components to see if we can work out the regulation of Cdk. It is consistent with but not yet proven that cdk regulation could regulate S phase between meiosis I and meiosis II. But I am worried about this mouse observation. Did you look at total HI histone kinase ... 

In a later publication, Kishimoto et al. (2004) proposed the water-filled nanotube as a model for the fibrillar N-terminal domain of the yeast prion Sup35p. The authors find that hydrated Sup35p fibrils show no 10-A equatorial reflection in the fiber diffraction pattern, but that dried fibrils... 

Probably the most well-known pathway to exemplify the occurrence of complex dynamics in metabolic networks is the glycolytic pathway of yeast. Arguably one of the most modeled pathways ever, minimal models of yeast glycolysis were studied since the 1960s [94, 273, 305 308] and give rise to a rich spectrum of... 

In addition to bistability and hysteresis, the minimal model of glycolysis also allows nonstationary solutions. Indeed, as noted above, one of the main rationales for the construction of kinetic models of yeast glycolysis is to account for metabolic oscillations observed experimentally for several decades [297, 305] and probably the model system for metabolic rhythms. In the minimal model considered here, oscillations arise due to the inhibition of the first reaction by its substrate ATP (a negative feedback). Figure 24 shows the time courses of oscillatory solutions for the minimal model of glycolysis. Note that for a large... 

Figure 30. A medium complexity model of yeast glycolysis [342], The model consists of nine metabolites and nine reactions. The main regulatory step is the phosphofructokinase (PFK), combined with the hexokinase (HK) reaction into a single reaction vi. As in the minimal model, we only consider the inhibition by its substrate ATP, although PFK is known to have several effectors. External glucose (Glc ) and ethanol (EtOH) are assumed to be constant. Additional abbreviations Glucose (Glc), fructose 1,6 biphosphate (FBP), pool of triosephosphates (TP), 1,3 biphosphogly cerate (BPG), and the pool of pyruvate and acetaldehyde (Pyr).

A paper by Kasprow et al.42 is important because it shows the realization that starting materials need to be analyzed on a routine basis just as with reaction products. Kasprow et al. discuss the correlation of fermentation yield with the yeast extract composition as seen by NIR. Using PLS for the correlations, models were constructed with a correlation of 0.996 and a standard error of 1.16 WSW. The authors used the models to predict yields, using different lots of yeast, and were quite satisfied with the results. 

As part of a subsequent study concerning primarily second-site revertant yeast iso-l-cytochrome c variants, Hazzard et al. evaluated the effect of converting Lys-72 to an aspartyl residue by site-directed mutagenesis on the electron transfer kinetics of the cytochrome c-cytochrome c peroxidase complex [136]. Lys-72 was of interest for this purpose, because it is involved in the hypothetical model for the complex formed by these two proteins that was proposed by Poulos and Kraut on the basis of molecular graphics docking [106]. In these... 

Proteasome inhibitors have been instrumental in identifying numerous protein substrates and in elucidating the importance of the proteasome/ubiquitin pathway in many biological processes. Initially, non-specific cell-penetrating peptide aldehydes were used for this purpose. More recently, it became possible to synthesize compounds with increased potency and selectivity (Adams et al. 1998 Elofsson et al. 1999). Furthermore, based on the crystal structure of the yeast and bovine liver CP (Groll et al. 1997 Unno et al. 2002), molecular modeling can now be used to engineer improved inhibitors. 

Hasegawa and co-workers [18] screened a number of microorganisms for the ability to degrade or deracemize selectively terminal 1,2-diols, useful intermediates for the synthesis of pharmacueticals, agrochemicals and liquid crystals. The yeast Candida parapsilosis IFO 0708 was the strain of choice for deracemization of the model substrate, pentan-l,2-diol 19. This biotransfor-... 

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