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PubMed1991

New vectors in fission yeast: application for cloning the his2 gene.

We describe a new Escherichia coli vector (pON5) that allows positive selection for recombinant clones. In this plasmid, the bla gene from pBR322 is permanently active, whereas the neo gene from transposon Tn5 is repressed by the cI-encoded lambda repressor. When DNA is inserted into the Bc/I or HindIII restriction sites situated within the cI gene, the neo gene becomes transcribed from the lambda pR promoter. We have also made a Schizosaccharomyces pombe derivative of pON5 (= pON163) by introducing the fission yeast ars1 and ura4+ sequences. We show that this plasmid is capable of transforming Sc. pombe ura4 strains, as well as ura 3 strains of the distantly related budding yeast Saccharomyces cerevisiae. We have used pON163 for the construction of two fission yeast genomic libraries. From these gene banks clones were isolated that were able to complement fission yeast his2 mutants. Such plasmids could also rescue his4C mutants of Sa. cerevisiae, defective in the histidinol dehydrogenase activity of the multifunctional HIS4 gene product. Finally, we describe the plasmid pDW232 which is useful for functional analysis of fission yeast genes. It is a pGEM3 derivative adapted to fission yeast, carrying multiple cloning sites between the T7 and SP6 promoters, together with ars1 and ura4+ from Sc. pombe.

Cloning, Molecular↗
PubMed1994

Efficient intra- and extracellular production of human beta-1,4-galactosyltransferase in Saccharomyces cerevisiae is mediated by yeast secretion leaders.

We have compared the function of homologous and heterologous secretion leaders to mediate production of human beta-1,4-galactosyltransferase (Gal-Tf) in the yeast Saccharomyces cerevisiae. Although all genes encoding leader/Gal-Tf fusions were transcribed by strong yeast promoters, only low production levels were obtained for full-length Gal-Tf containing the human membrane-anchor region. In contrast, a gene fusion encoding the membrane-anchor region of the yeast alpha-1,2-mannosyltransferase (Mnt1) fused to soluble Gal-Tf yielded high mRNA and intracellular protein levels. Gal-Tf could also be produced extracellularly using a fusion of the pre-pro region of the yeast Mf alpha 1 precursor (MF alpha 1) to soluble Gal-Tf; a fusion containing only the pre-region of Mf alpha 1 was synthesized intracellularly, but did not lead to Gal-Tf activity in the culture medium. All yeast-produced Gal-Tf proteins were enzymatically active. These results demonstrate that yeast secretion leaders are advantageous to achieve efficient production of active Gal-Tf in S. cerevisiae.

Biological Transport↗
PubMed1995

Expression of the human MGMT O6-methylguanine DNA methyltransferase gene in a yeast alkylation-sensitive mutant: its effects on both exogenous and endogenous DNA alkylation damage.

Common Mer- cell lines deficient in O6-methylguanine DNA methyltransferase (MTase) activity probably result from the down-regulation of, rather than mutations in, the MGMT gene. However, the down-regulation of other unrelated genes was also observed in some of these cell lines, making it difficult to determine the precise functions of the MGMT MTase gene. To study the biological function of human MGMT MTase, we seek to utilize a newly created yeast mgt1 mutant deficient in the DNA repair MTase activity. The human MGMT cDNA was cloned into yeast expression vectors so that the MGMT gene is under the control of either an inducible GAL1 promoter or a constitutive ADH1 promoter. Upon galactose induction, the PGAL1-MGMT transformant had about 40-fold MTase activity compared to the wild-type strain. MGMT overexpression protected the yeast mgt1 mutant against alkylation-induced killing and mutation. Limited expression of the MGMT gene in the mgt1 mutant still provides significant alkylation resistance, albeit at a reduced level. The yeast mgt1 mutants increase spontaneous mutation rate, whereas constitutive expression of the MGMT gene lowered the spontaneous mutation rate in the mgt1 mutant to the wild-type level. We suggest that MGMT MTase may play the same role in human cells as the MGT1 MTase in yeast cells. Thus our results demonstrate that the human MGMT gene functionally complements the yeast MTase-deficient mutant in the protection against exogenous and endogenous DNA alkylation damage, which provides a useful tool for the study of in vivo mammalian MTase functions.

Alkylation↗
PubMed1996

Use of INAA to study the determination of Se, Th, Zn, Co and Fe levels of yeast cells.

Differences in the effects of seleno-cystine (CySe)2, glutathione (GSH), Se(IV) [as SeO2] and Se(VI) [as (NH4)2SeO4] on Th(IV) [as Th(CO3)2] uptake by the cells, Saccharomyces cerevisiae, have been studied. The Th, Se, Zn, Co and Fe levels of the yeast cells were measured by instrumental neutron activation analysis. Results obtained show that the addition of Th alone to the culture medium resulting in the Th content of the cells and the Th level of the yeast slightly decreased during the incubation. The addition of Th in combination with GSH produced a higher decrease of the Th content in comparison with the single Th dosage. During the initial 48 h of the incubation the presence of Th and Se(VI) in the medium produced a decrease of the Th level of the cells in comparison with the addition of Th alone. (CySe)2 or SeO2 does not produce a regular change of the Th level of the cells. Th uptake by the yeast influenced the retention of Se in the cells. In fact, the Se levels of the cells were always significantly higher when the yeast was incubated in the medium containing Th and SeO2 or Se(VI). The enhance in the Se level of the cells rises with increasing concentrations of SeO2 in the culture medium. Th decreased the Se content of the yeast when the cells were incubated in the medium containing (CySe)2 and Th. GSH supply in combination with Th and SeO2 produced a very significant enhancement of the Se abundance in the cells in comparison with the single addition of SeO2. Se-compounds and/or Th dosages affected the Zn, Co and Fe contents of the cells. The Fe level of the yeast is below the quantitative detection limit of Fe when the cells were incubated in the medium containing Th.

Cobalt↗
PubMed2004

Expression of a familial amyotrophic lateral sclerosis-associated mutant human superoxide dismutase in yeast leads to decreased mitochondrial electron transport.

Strains of Saccharomyces cerevisiae that express either the wild type or the amyotrophic lateral sclerosis-associated mutant human copper-zinc superoxide dismutase (SOD1) proteins A4V and G93A, respectively, in a yeast SOD1-deficient parent strain were used to investigate the hypothesis that expression of a mutant SOD1 protein causes deficient mitochondrial electron transport as a possible mechanism for disease induction. Mitochondria isolated from the wild type SOD1-expressing yeast were identical to mitochondria from the parent strain in heme content and activities of complexes II, III, and IV. Mitochondria isolated from the A4V-expressing yeast had decreased rates of electron transport in complexes II+III, III, and IV and corresponding decreases in hemes b, c-c1, and a-a3 content compared to mitochondria from wild type human SOD1-expressing yeast. Mitochondria isolated from G93A-expressing yeast had decreased rates of electron transport in complex IV and probably in complex II with a corresponding decrease in heme a-a3 content. These results suggest that mutant SOD1-expression causes defective electron transport complex assembly and that the yeast system will provide an excellent model for the study of the mechanism of mutant SOD1-induced mitochondrial electron transport defects.

Amyotrophic Lateral Sclerosis↗
PubMed2005

Effects of cryoprotectants on the viability and activity of freeze dried recombinant yeasts as novel oral drug delivery systems assessed by an artificial digestive system.

The aim of this study was to investigate, in a gastric-small intestinal system TIM-1, the effect of cryoprotectants on the survival of freeze-dried Saccharomyces cerevisiae expressing the heterologous P450 73A1 and their ability to convert trans-cinnamic acid into p-coumaric acid. Yeasts were lyophilized in suspensions of trehalose, maltose, lactose, or a milk proteins/trehalose mix. Freeze-dried or native yeasts and trans-cinnamic acid were introduced simultaneously into TIM-1 at the beginning of digestion. Yeast survival rate was evaluated by cell counting in the ileal effluents. P450 73A1 activity was followed by HPLC assay of p-coumaric acid. Freeze-dried yeasts showed high tolerance to digestive conditions. Nevertheless, their survival rate was lower than that of non-dried cells (around 80% whatever the protective agent vs. 96%). The ability of recombinant freeze-dried S. cerevisiae to perform a bioconversion reaction in the digestive tract was shown with all the protectants. The highest trans-cinnamic acid conversion rate (24 vs. 41% for native yeasts) was obtained with the milk proteins/trehalose mix. These results show that freeze-drying might be considered for the pharmaceutical formulation of new drug delivery systems based on orally administered recombinant yeasts and that TIM-1 could be a helpful tool for the pre-screening of oral dosage forms.

Cryoprotective Agents↗
PubMed2004

Programmed cell death in fission yeast.

Recently a metacaspase, encoded by YCA1, has been implicated in a primitive form of apoptosis or programmed cell death in yeast. Previously it had been shown that over-expression of mammalian pro-apoptotic proteins can induce cell death in yeast, but the mechanism of how cell death occurred was not clearly established. More recently, it has been shown that DNA or oxidative damage, or other cell cycle blocks, can result in cell death that mimics apoptosis in higher cells. Also, in fission yeast deletion of genes required for triacylglycerol synthesis leads to cell death and expression of apoptotic markers. A metacaspase sharing greater than 40% identity to budding yeast Yca1 has been identified in fission yeast, however, its role in programmed cell death is not yet known. Analysis of the genetic pathways that influence cell death in yeast may provide insights into the mechanisms of apoptosis in all eukaryotic organisms.

Amino Acid Sequence↗
PubMed2005

The human mineralocorticoid receptor only partially differentiates between different ligands after expression in fission yeast.

Cardiac failure is a major health problem with increasing incidence due to aging of the population. Studies in both experimental animals and humans have suggested that aldosterone excess may have deleterious effects on cardiac function. In order to generate a novel screening system for the identification of aldosterone antagonists, we expressed the human mineralocorticoid receptor (MR) and the human glucocorticoid receptor (GR), respectively, in the fission yeast Schizosaccharomyces pombe. Reporter plasmids containing two hormone-responsive elements upstream of a fission yeast minimal promotor and either a lacZ gene (for quantification) or a neomycin gene (for survival screening) were constructed and cotransformed into fission yeast strains with expression plasmids for MR or GR. The functionality of the reporter systems was then tested using physiological ligands of both receptors as well as known inhibitors. Transactivating activity of MR could be stimulated by aldosterone, 11-deoxycorticosterone, 11-deoxycortisol, cortisol, cortisone, and spironolactone, but not by progesterone, while GR activity was stimulated by cortisol and cortisone, but also not by progesterone. Taken together, we have succeeded in establishing fission yeast-based screening systems that allow the identification of MR- or GR-interacting compounds. Moreover, our data show that after expression in fission yeast both receptors did not differentiate between steroids with different configurations at positions 11beta, 17 and 18. This finding suggests that only recognition of C-21 substituents may be accomplished by the receptor proteins alone, while the physiologically important selectivity towards other positions of the steroid ligand depends on other factors which are not conserved from fission yeast to man.

Aldosterone↗
PubMed2003

Evolutionarily conserved cytoprotection provided by Bax Inhibitor-1 homologs from animals, plants, and yeast.

Programmed cell death (PCD) plays important roles in the development and physiology of both animals and plants, but it is unclear whether similar mechanisms are employed. Bax Inhibitor-1 (BI-1) is an intracellular multi-membrane-spanning protein and cell death inhibitor, originally identified by a function-based screen for mammalian cDNAs capable of suppressing cell death in yeast engineered to ectopically express the pro-apoptotic protein Bax. Using this yeast assay, we screened expression libraries for cDNAs from the plant, Lycopersicon esculentum (tomato), and the invertebrate animal Drosophila melanogaster (fruit fly), identifying close homologs of BI-1 as Bax-suppressors. We studied the fly and tomato homologs of BI-1, as well as BI-1 homologs identified in Arabidopsis thaliana, Oryza sativa (rice), and Saccharomyces cerevisiae (budding yeast). All eukaryotic homologs of BI-1 blocked Bax-induced cell death when expressed in yeast. Eukaryotic BI-1 homologs also partially rescued yeast from cell death induced by oxidative stress (H(2)O(2)) and heat shock. Deletion of a C-terminal domain from BI-1 homologs abrogated their cytoprotective function in yeast, demonstrating conserved structure-function relations among these proteins. Expression of tomato BI-1 by agroinfiltration of intact plant leaves provided protection from damage induced by heat-shock and cold-shock stress. Altogether, these findings indicate that BI-1 homologs exist in multiple eukaryotic species, providing cytoprotection against diverse stimuli, thus implying that BI-1 regulates evolutionary conserved mechanisms of stress resistance that are germane to both plants and animals.

Amino Acid Sequence↗
PubMed2007

Chemosensitisation of drug-resistant and drug-sensitive yeast cells to antifungals.

Multidrug resistance in yeast results from overexpression of genes encoding drug efflux transporters owing to gain-of-function mutations in transcription factors regulating their expression. We have screened a library of synthetic compounds for modulators of drug resistance using the multidrug-resistant Saccharomyces cerevisiae pdr3-9 mutant strain. One of the compounds, 7-chlorotetrazolo[5,1-c]benzo[1,2,4]triazine (CTBT), displayed weak antifungal activity and strongly inhibited the growth of yeast cells in combination with subinhibitory concentrations of other antifungals with a different mode of action. Biological activity of CTBT was demonstrated in Saccharomyces, Kluyveromyces and Candida yeast species grown on solid and in liquid media. The chemosensitising effect of CTBT, manifested as increased antifungal activity of fluconazole, was demonstrated in yeast mutant strains with deleted genes encoding the major multidrug resistance transcription factors Yap1p, Pdr1p and Pdr3p as well as the drug efflux pumps Pdr5p and Snq2p in S. cerevisiae or their counterparts in Candida albicans and Candida glabrata, named Cdr1p and Mdr1p, respectively. Importantly, CTBT also increased the sensitivity to fluconazole in multidrug-resistant cells overexpressing the efflux pumps. Yeast cells grown in the presence of subinhibitory concentrations of CTBT exhibited an altered sterol composition and a slightly enhanced accumulation of Rhodamine 6G, which suggests that the plasma membrane plays a role in sensitisation. This novel chemosensitisation by CTBT that can overcome multidrug resistance in yeast may prove useful in combined treatment of infections caused by drug-resistant fungal pathogens.

Antifungal Agents↗
PubMed2004

Synthesis of the measles virus nucleoprotein in yeast Pichia pastoris and Saccharomyces cerevisiae.

The development of a simple, efficient and cost-effective system for generation of measles virus nucleoprotein might help to upgrade reagents for measles serology. The gene encoding measles nucleoprotein was successfully expressed in two different yeast genera, Pichia pastoris and Saccharomyces cerevisiae, respectively. Both yeast genera synthesized a high level of nucleoprotein, up to 29 and 18% of total cell protein, in P. pastoris and S. cerevisiae, respectively. This protein is one of most abundantly expressed in yeast. After purification nucleocapsid-like particles (NLPs) derived from both yeast genera appeared to be similar to those detected in mammalian cells infected with measles virus. A spontaneous assembly of nucleoprotein into nucleocapsid-like particles in the absence of the viral leader RNA or viral proteins has been shown. Compartmentalisation of recombinant protein into large compact inclusions in the cytoplasm of yeast S. cerevisiae by green fluorescence protein (GFP) fusion has been demonstrated. Sera from measles patients reacted with the recombinant protein expressed in both yeast genera and a simple diagnostic assay to detect measles IgM could be designed on this basis.

Blotting, Western↗
PubMed2006

Relationships between the sequence of alpha-synuclein and its membrane affinity, fibrillization propensity, and yeast toxicity.

To investigate the alpha-synuclein protein and its role in Parkinson's disease, we screened a library of random point mutants both in vitro and in yeast to find variants in an unbiased way that could help us understand the sequence-phenotype relationship. We developed a rapid purification method that allowed us to screen 59 synuclein mutants in vitro and discovered two double-point mutants that fibrillized slowly relative to wild-type, A30P, and A53T alpha-synucleins. The yeast toxicity of all of these proteins was measured, and we found no correlation with fibrillization rate, suggesting that fibrillization is not necessary for synuclein-induced yeast toxicity. We found that beta-synuclein was of intermediate toxicity to yeast, and gamma-synuclein was non-toxic. Co-expression of Parkinson's disease-related genes DJ-1, parkin, Pink1, UCH-L1, or synphilin, with synuclein, did not affect synuclein toxicity. A second screen, of several thousand library clones in yeast, identified 25 non-toxic alpha-synuclein sequence variants. Most of these contained a mutation to either proline or glutamic acid that caused a defect in membrane binding. We hypothesize that yeast toxicity is caused by synuclein binding directly to membranes at levels sufficient to non-specifically disrupt homeostasis.

Amino Acid Sequence↗
PubMed2004

A mathematical model of ageing in yeast.

Budding yeast, Saccharomyces cerevisiae, is commonly used as a system to study cellular ageing. Yeast mother cells are capable of only a limited number of divisions before they undergo senescence, whereas newly formed daughters usually have their replicative age "reset" to zero. Accumulation of extrachromosomal ribosomal DNA circles (ERCs) appears to be an important contributor to ageing in yeast, and we describe a mathematical model that we developed to examine this process. We show that an age-related accumulation of ERCs readily explains the observed features of yeast ageing but that in order to match the experimental survival curves quantitatively, it is necessary that the probability of ERC formation increases with the age of the cell. This implies that some other mechanism(s), in addition to ERC accumulation, must underlie yeast ageing. We also demonstrate that the model can be used to gain insight into how an extra copy of the Sir2 gene might extend lifespan and we show how the model makes novel, testable predictions about patterns of age-specific mortality in yeast populations.

Aging↗
PubMed2005

The cytidine deaminase AID exhibits similar functional properties in yeast and mammals.

A recent work published in Molecular Immunology examined the editing activity of activation-induced deaminase (AID) in yeast (Krause, K., Marcu, K.B., Greeve, J., 2006. The cytidine deaminases AID and APOBEC-1 exhibit distinct functional properties in a novel yeast selectable system. Mol. Immunol.). It was proposed that expression of AID in yeast is not sufficient for the generation of point mutations in a highly transcribed gene due to the lack of cofactors for AID-induced somatic hypermutation, which are unique to B cells. It was suggested that, on its own, AID does not have an intrinsic specificity for its target sequences. However, it has been shown previously that expression of the human AID gene in yeast was moderately mutagenic in a wild-type strain and highly mutagenic in an ung1 uracil-DNA glycosylase-deficient strain (Mayorov, V.I., Rogozin, I.B., Adkison, L.R., Frahm, C.R., Kunkel T.A., Pavlov Y. I., 2005. Expression of human AID in yeast induces mutations in context similar to the context of somatic hypermutation at G-C pairs in immunoglobulin genes. BMC Immunol. 6, 10; Poltoratsky, V.P., Wilson, S.H., Kunkel, T.A., Pavlov, Y.I., 2004. Recombinogenic phenotype of human activation-induced cytosine deaminase. J. Immunol. 172, 4308-4313). The vast majority of mutations were at G-C pairs. Mutations showed a clear DNA sequence context specificity which resembled the specificity of somatic hypermutation at G-C pairs in immunoglobulin genes and AID mutation specificity in vitro. The inability to detect mutator effects of AID by Krause et al. is likely to be caused by the use of the wild-type yeast strain and a small sample of clones examined for the presence of mutations. In addition, we show that non-uniformity of the mutation hotspot distribution is a factor potentially decreasing the chances of detecting mutations.

Animals↗
PubMed2005

Genotoxicity of stannous chloride in yeast and bacteria.

Stannous chloride was found genotoxic in microbial test systems of the yeast Saccharomyces cerevisiae, in one strain of Salmonella typhimurium and in the Mutoxitest of Escherichia coli. Five isogenic haploid yeast strains differing only in a particular repair-deficiency had the following ranking in Sn2+ -sensitivity: rad52delta>rad6delta>rad2delta>rad4delta>RAD, indicating a higher relevance of recombinogenic repair mechanisms than nucleotide excision in repair of Sn2+ -induced DNA damage. Sn2+ -treated cells formed aggregates that lead to gross overestimation of toxicity when not undone before diluting and plating. Reliable inactivation assays at exposure doses of 25-75 mM SnCl2 were achieved by de-clumping with either EDTA- or phosphate buffer. Sn2+ -induced reversion of the yeast his1-798, his1-208 and lys1-1 mutant alleles, in diploid and haploid cells, respectively, and putative frameshift mutagenesis (reversion of the hom3-10 allele) was observed. In diploid yeast, SnCl2 induced intra-genic mitotic recombination while inter-genic (reciprocal) recombination was very weak and not significant. Yeast cells of exponentially growing cultures were killed to about the same extend at 0.1% of SnCl2 than respective cells in stationary phase, suggesting a major involvement of physiological parameters of post-diauxic shift oxidative stress resistance in enhanced Sn2+ -tolerance. Superoxide dismutases, but not catalase, protected against SnCl2-induced reactive oxygen species as sod1delta had a three-fold higher sensitivity than the WT while the sod2delta mutant was only slightly more sensitive but conferred significant sensitivity increase in a sod1delta sod2delta double mutant. In the Salmonella reversion assay, SnCl2 did not induce mutations in strains TA97, TA98 or TA100, while a positive response was seen in strain TA102. SnCl2 induced a two-fold increase in mutation in the Mutoxitest strain IC203 (uvrA oxyR), but was less mutagenic in strain IC188 (uvrA). We propose that the mutagenicity of SnCl2 in yeast and bacteria occurs via error-prone repair of DNA damage that is produced by reactive oxygen species.

Catalase↗
PubMed2005

Establishment of a yeast system that stably expresses human cytochrome P450 reductase: application for the study of drug metabolism of cytochrome P450s in vitro.

Cytochrome P450s (CYPs) hold a balance in studying pharmacokinetics, toxico-kinetics, drug metabolism, and drug-drug interactions, which require association with cytochrome P450 reductase (CPR) to achieve optimal activity. A novel system of Saccharomyces cerevisiae useful for expression studies of mammalian microsomal CYPs was established. Human CPR (hCPR) was co-expressed with human CYP3A4 (hCYP3A4) in this system, and two expression plasmids pTpLC and pYeplac195-3A4 containing the cDNA of hCPR and hCYP3A4 were constructed, respectively. The two plasmids were applied first and controlled by phosphoglycerate kinase (PGK) promoter. S. cerevisiae BWG1-7alpha transformed with the expression plasmids produced the respective proteins in the expected molecular sizes reactive with both anti-hCYP3A4 immunoglobulin (Ig) and anti-hCPR Ig. The activity of hCPR in yeast BWG-CPR was 443.2 nmol reduced cytochrome c/min/mg, which was about three times the CPR activity of the microsome prepared from the parental yeast. The protein amount of hCYP3A4 in BWG-CPR/3A4 was 35.53 pmol/mg, and the 6beta-hydroxylation testosterone formation activity of hCYP3A4 expressed was 7.5 nmol/min/nmol CYP, 30 times higher than the activity of hCYP3A4 expressed in the parental yeast, and almost two times the activity of hCYP3A4 from homologous human liver microsome. Meanwhile, BWG-CPR/3A4 retained 100 generations under nonselective culture conditions, indicating this yeast was a mitotically stable transformant. BWG-CPR was further tested daily by the PCR amplification of hCPR of yeast genome, Western blot analysis, and the activity assay of hCPR of yeast microsome. This special expression host for CYPs was validated to be stable and efficient for the expression of CYPs, applying as an effective selection model for the drug metabolism in vitro.

Androgens↗
PubMed2006

Metabolic engineering of malolactic wine yeast.

Malolactic fermentation is essential for the deacidification of high acid grape must. We have constructed a genetically stable industrial strain of Saccharomyces cerevisiae by integrating a linear cassette containing the Schizosaccharomyces pombe malate permease gene (mae1) and the Oenococcus oeni malolactic gene (mleA) under control of the S. cerevisiae PGK1 promoter and terminator sequences into the URA3 locus of an industrial wine yeast. The malolactic yeast strain, ML01, fully decarboxylated 5.5 g/l of malate in Chardonnay grape must during the alcoholic fermentation. Analysis of the phenotype, genotype, transcriptome, and proteome revealed that the ML01 yeast is substantially equivalent to the parental industrial wine yeast. The ML01 yeast enjoys 'Generally Regarded As Safe' status from the FDA and is the first genetically enhanced yeast that has been commercialized. Its application will prevent the formation of noxious biogenic amines produced by lactic acid bacteria in wine.

Bacterial Proteins↗
PubMed2006

Transformation of yeast by infectious prion particles.

We present methods to prepare infectious Sup35 protein aggregates and use them for genetic transformation of yeast. The protein aggregates are prepared from bacterially expressed recombinant protein, which is converted to amyloid fibers by extended incubation or by nucleated growth using yeast prion particles as seeds. The aggregates are introduced into yeast by a modified spheroplast transformation protocol. The phenotype of the yeast transformants is further characterized by robust prion strain typing methods. The methodology can be used to introduce different [PSI(+)] particles to many laboratory yeast genetic backgrounds. It can be adapted for applications in other yeast prion systems as well.

Amyloid↗