Association of Disomic Chromosome Loss with Ems-Induced Conversion in Yeast

Experimental tests with the yeast Saccharomyces cerevisiae of a previously proposed model suggesting a causal relationship between disomic chromosome loss (n + 1 → n) and centromere-adjacent mitotic gene conversion were performed. Disomic haploid cells heteroallelic at two loci on the left arm of chromosome III were exposed to ethyl methanesulfonate (EMS) under nonlethal conditions; EMS-induced prototrophic gene convertants were selected and tested for coincident chromosome loss. The principal results are: (1) The frequency of chromosome loss among EMS-induced gene convertants selected to arise near the centromere is markedly enhanced over basal levels and remains constant, independent of EMS exposure. There is little such enhancement among EMS-induced convertants selected to arise far from the centromere. (2) Chromosome loss is almost completely associated with induced conversion of the centromere-proximal allele at the centromere-adjacent heteroallelic locus. This result is identical to (and confirms) results found previously for spontaneous loss-associated conversion. (3) The conversion polarity at the centromere-adjacent locus among unselected (nonloss-associated) induced or spontaneous mitotic convertants is identical to that among meiotic convertants and markedly favors the contromere-distal allele. These findings are wholly consistent with, and strengthen, the hypothesis that structural involvement of centromeric regions in nearby recombinational events may interfere with proper segregational function and lead to mitotic chromosome loss.     

A new method for testing genetically active metabolites. Urinary assay with cyclophosphamide (endoxan, cytoxan) and Saccharomyces cerevisiae

Cyclophosphamide (Endoxan, Cytoxan), a cytostatic substance, was tested for its genetic activity in Saccharomyces cerevisiae. The test system used was induction of (I) back mutation and (II) mitotic gene conversion. Given directly to yeast, cyclophosphamide showed no genetic effect. After oral application to BD rats the urine showed medium mutational activity but strong convertogenic activity up to a 100-fold increase of induced convertants. In the host-mediated assay (injection of yeast into the ventral cavity), cyclophosphamide was only weakly active.     

The Waxy Locus in Maize III. Effect of Structural Heterozygosity on Intragenic Recombination and Flanking Marker Assortment

The effect of heterozygosity for structural rearrangements on recombination between two wx heteroalleles (C and 90) and the pattern of flanking markers in the resultant Wx gametes has been examined. The rearrangements are Tp9, an insertional translocation in which a segment of chromosome 3 has been inserted into the short arm of chromosome 9 close to the wx locus; In9a, a long pericentric inversion with wx in the inverted segment; and Rearr 9, a complex rearrangement of chromosome 9. Heterozygosity for rearrangements decreases the frequency of Wx gametes to varying degrees.—Heterozygosity for Tp9 enhances the proportion of Wx gametes that are apparent convertants and allows the conclusion that such gametes do not normally arise from an exchange in the wx locus plus a second exchange distal to wx. Heterozygosity for In9a markedly decreases the frequency of Wx gametes that are recombinant for outside markers but does not decrease the frequency of convertants.—Heterozygosity for Rearr 9 permits a low frequency of Wx gametes, all of which are apparent convertants.—A high proportion of the convertants have the flanking markers that entered the cross with C so recombination is polarized in normal homologs and in heterozygotes for all rearrangements.     

Microbial transformations of chalcones to produce food sweetener derivatives

Biotransformations of two substrates: chalcone (1) and 2′-hydroxychalcone (4) were carried out using four yeast strains and five filamentous fungi cultures. Substrate 1 was effectively hydrogenated in all of tested yeast cultures (80–99% of substrate conversion after 1 h of biotransformation) affording dihydrochalcone 2. In the cultures of filamentous fungi the reaction was much slower, however, Chaetomium sp. gave product 2 in 97% yield. After 12 h of incubation a reduction of dihydrochalcone 2 to alcohol 3 was additionally observed. After 3 days of biotransformation in the culture of Rhodotorula rubra product (S)-3 was obtained with 75% ee (enantiomeric excess) and 99% of conversion. Also after a 3-day biotransformation using the strain Fusarium culmorum product (R)-3 was obtained with 98% ee and 97% of conversion. In most of the tested strains a change in enantiomeric excess of compound 3 during the biotransformation process was noticed. In the culture of Rhodotorula glutinis after 3 h of transformation alcohol (R)-3 was formed with 47% ee and 31% of substrate conversion, whereas after 6 days the (S)-3 enantiomer was obtained with 99% ee and 91% of conversion. In the case of 2′-hydroxychalcone (4), the hydrogenation proceeded much slower and led to 2′-hydroxydihydrochalcone (5) – in the culture of Yarrowia lipolytica 97% of conversion was observed after 3 days. In all cultures of the tested strains no products of 2′-hydroxydihydrochalcone reduction were detected.     

The effect of liquid holding on chemical induced lethality and mitotic gene conversion in Saccharomyces cerevisiae

Summary Mitotic gene conversion was induced with a variety of chemical mutagens in a double heteroallelic strain of Saccharomyces cerevisiae. Cells were treated with various mutagens and plated immediately onto selective and nonselective growth medium or else they were subject before plating to liquid holding in buffer for various lengths of time. In respiratory competent cells liquid holding caused a decrease in lethality and in conversion frequencies. Respiratory deficient cells, unable to use a non-fermentable substrate as an energy source, behaved different. Untreated cells started to die in buffer after two days of storage, and moreover, there was a considerable increase in potential convertants i.e. cells giving rise to gene convertants when plated on selective growth media. Respiratory deficient cells treated with various chemical mutagens were still more sensitive to liquid holding. After low, sublethal doses cells started to die after one day of liquid holding already and when plated on media selective for convertants, showed an increasing frequency of gene convertants. Addition of very low concentrations of glucose to the liquid holding buffer post-poned the lethal and convertogenic effects. Higher concentrations of glucose completely abolished sensitivity to liquid holding-induced lethality and genetic alterations. The results are interpreted to mean that in respiratory deficient cells no repair activities are possible to an accumulation of spontaneous lethal damage and genetic alterations which are expressed as gene conversion when an energy source becomes available. Such a repairless condition causes an increased sensitivity to genetically active agents, and provides a useful system to detect genetic effects of slowly reacting agents.     

Sensitive semi-microcolumn high-performance liquid chromatographic method for the determination of DU-6681, the active parent drug of a new oral carbapenem antibiotic,DZ-2640, in human plasma and urine using a column-switching system as sample clean-up procedure

DZ-2640 is a new oral carbapenem antibiotic having a dihydro-pyrroloimidazole ring as a side chain and a pivaloyloxymethyl (POM) ester prodrug of DU-6681, the active parent compound. A simple and sensitive column-switching semi-microcolumn high-performance liquid chromatographic method for the determination of DU-6681 in human plasma and urine has been developed. Human plasma was diluted with an equal volume of 1 M MOPS buffer (pH 7.0) and the mixture was filtered through an Ultrafree C3GV. The resulting filtrate was injected without further cleanup onto the HPLC system. Human urine was diluted with an equal volume of 1 M MOPS buffer (pH 7.0) and the mixture was directly injected onto the HPLC system. The analyte was detected by monitoring the column effluent with UV light at a wavelength of 300 nm, which resulted in the limit of quantitation of 0.008 μg/ml of plasma and 0.32 μg/ml of urine. Calibration curves were linear in the range of 0.008 to 5.85 μg/ml in plasma and 0.32 to 104.4 μg/ml in urine. The present methods showed greatly increased sensitivity for DU-6681 compared to conventional HPLC methods and also showed satisfactory recovery, selectivity, precision, and accuracy. Stability studies showed that 1 M MOPS buffer (pH 7.0) acted as a stabilizer. In plasma and urine diluted with equal volume of the buffer, DU-6681 showed good stability at −80°C for up to 4 weeks with no significant loss of the drug.     

Effect of post-irradiation inhibition of protein synthesis on UV-induced mitotic gene conversion in Saccharomyces cerevisiae

The effect of post-irradiation inhibition of protein synthesis with cycloheximide was studied on UV-induced mitotic gene conversion in yeast. The frequency of UV-induced mitotic gene convertants as well as survival were reduced when post-irradiation protein synthesis was inhibited beyond 8 h. It is concluded that proteins required for mitotic recombination are not induced by UV irradiation and are already present in mitotic cells.     

Asymmetric reduction of (4S)-(+)-carvone catalyzed by baker's yeast: A green method for monitoring the conversion based on liquid–liquid–liquid microextraction with polypropylene hollow fiber membranes

The α,β-unsaturated carbonyl compound (4S)-(+)-carvone was selectively reduced to (1R,2R,4S)-iso-dihydrocarveol using baker's yeasts. The conversion of the bioreduction reaction was monitored using a green hollow-fiber liquid–liquid–liquid microextraction (HF-LLLME) technique. Several parameters which may affect the bioreduction of (4S)-(+)-carvone, such as temperature, time, substrate/enzyme ratio, pH and buffer concentration, were evaluated. The effect of some additives, such as trehalose, DMSO and the ionic liquid [BMIm][PF₆], was also studied. The (1R,2R,4S)-iso-dihydrocarveol was recovered with 52.7% conversion and diastereoisomeric excess >99% after 48 h of reaction at 40 °C in an aqueous monophasic system, with 0.1 mol L^?1 buffer concentration (pH 7.5) and a substrate/yeast cell mass ratio of 8.0 mg g^?1. The HF-LLLME microextraction technique allowed the optimization of the reaction with a reduction of over 99.5% in relation to the use of organic solvents.     

Molecular cloning of the ADE1 gene of Saccharomyces cerevisiae and stability of the transformants

Plasmid YEp(ADE1)1a, containing a 2.7-kb Sau3A fragment of Saccharomyces cerevisiae DNA inserted at the BamHI site of the yeast shuttle vector pBTI-1 (Morris et al., 1981), results in high frequency, unstable transformation of ade1 yeast strains. A second plasmid, YRp(ADE1)2, containing adjacent 0.5-kb and 3.0-kb BamHI fragments in pBR322 gave three types of yeast transformants: (1) transformants carrying extrachromosomal copies of the plasmid which indicate the presence of a functional ars sequence, (2) transformants indistinguishable from ade1 strains by hybridization analyis, and (3) a transformant carrying a multimeric form of YRp(ADE1)2. Cells transformed with either of the plasmids are free of the red pigment characteristic of ade1 mutants and indicate potential for direct colour-based selection of yeast transformants using ADE1 plasmids.     

Improved production of ethyl-(R)-2-hydroxy-4-phenylbutyrate with pretreated Saccharomyces cerevisiae in water/organic solvent two-liquid phase systems

Baker's yeast pretreated with α-phenacyl chloride was employed to improve the enantioselectivity of the asymmetric reduction of ethyl-2-oxo-4-phenylbutyrate (EOPB) to ethyl-(R)-2-hydroxy-4-phenylbutyrate ((R)-EHPB) and maintain a high activity of the yeast. A water/organic solvent two-liquid phase system was also introduced to overcome the strong substrate and product inhibition of the enzyme; the highest catalytic activity and enantioselectivity were obtained in a water/benzene two-liquid phase system. When the reduction was catalyzed with pretreated yeast (300 mg mL^?1 buffer) in the water/benzene two-liquid phase system (V_aq/V_ben=20:40), 41.9% molar conversion of EOPB and 87.5% e.e. of (R)-EHPB were obtained in 48 h, using pH 8.0 phosphate buffer with 1.5% (v/v) of ethanol added as a co-substrate at 30°C, even with an initial EOPB concentration of 400 mM and a final EHPB concentration as high as 167.7 mM.     

Inherent G418-resistance in hybridization of industrial yeasts

Eight strains of sake yeast exhibited inherent-resistance to 100 μg/ml of Geneticin (G418). Fourteen wine yeasts and 1 shochu yeast (Saccharomyces cerevisiae) and 1 miso yeast (Zygosaccharomyces rouxii) were inherent G418-sensitive. The petites converted from inherent G418-resistants by treatment with ethidium bromide retained G418-resistance (ϱ⁻ G418R), and thus were hybridized by electrofusion with the wine yeast W3 (ϱ⁺ G418S, wild type). A lag phase of 12–18 h was required prior to administration of the drug in glycerol medium when selecting G418-resistant hybridization products. Colonies were formed in the regeneration medium at a frequency of about 1 × 10⁻⁵ per used protoplasts. No growth of any parental strain (10⁶/_~10⁷ protoplasts) separately subjected to electrofusion and regeneration was observed. The hybridization products were G418-resistant “grande” strains (ϱ⁻ G418R) in which the genetic traits of parental strains had been complemented. Uninucleate cells (DAPI staining) of the hybridization products showed CHEF electrophoretic karyotypes similar to that of wine yeast, but possessed a single chromosome (approx. 320 kb) presumably from sake yeast.     

Effects of prolonged intravenous infusions of adrenaline on glucose utilization, plasma metabolites, hormones and milk production in lactating sheep

Lactating ewes received continuous intravenous infusions of adrenaline (0.05 micrograms/kg liveweight) for 4 days. Prior to, during and after adrenaline infusions, milk yield and composition were monitored. Plasma concentrations of metabolites and hormones were measured each day and glucose biokinetics were measured in non-steady state at the start and end of adrenaline infusions. During adrenaline infusion, milk yield and content of solids-not-fat decreased and milk fat content was reduced on the first day of infusion. Plasma glucose was raised throughout the period of adrenaline infusion, plasma lactate increased over the first 4 h from the start of infusion and plasma non-esterified fatty acids increased for 2 h at the start of infusion and tended to increase during the first 2-3 h after withdrawal of adrenaline. Plasma growth hormone remained relatively stable except for a marked increase at 30 min after withdrawal of adrenaline. At the start and immediately after withdrawal of adrenaline infusion plasma insulin was increased approximately twofold. Glucose production, but not utilization, increased at the start of infusions. Immediately after withdrawal of adrenaline glucose utilization increased 2.5-fold with a smaller response in glucose production. There was essentially no change in glucose clearance during adrenaline infusion but a marked increase occurred after withdrawal of adrenaline.     

Induction of gene conversion in yeast cells continuously cultured at high radiation background

The induction of genetic damage was investigated by culturing diploid yeastSaccharomyces cerevisiae D7 cells continuously at radiation levels ranging from 0.383 µSv/h to 1.275 mSv/h by selecting appropriate concentrations of tritiated water in the growth medium. These radiation levels correspond to 3–10000 times the natural background. Parameters such as growth kinetics, gene conversion frequency at background radiation and after a challenging dose of acute gamma-radiation or alkylating agentN-methyl-N-nitro-N-nitrosoguanidine (MNNG) were assessed. The gene conversion frequency in most of the assays was in the range of 5–10 convertants per 10⁶ cells, as in the case of controls. However, a number of the cultures showed conversion frequencies above 20 per 106 viable cells. This stochastic phenomenon occurred more frequently in cells which were incubated at higher radiation levels and for longer durations. This suggests that radiation is responsible for the phenomenon. When subculturing continued beyond 900 h, gene conversion frequencies reverted back to normal values in all cultures in spite of elevated background radiation levels, thus suggesting an adaptive response. The generation time of the cells was 78 min in all cultures irrespective of the radiation level. The response of the cells cultured at elevated background radiation levels to subsequent challenging treatment with gamma-radiation or MNNG was identical to that of the control cultures. Our results suggest that in eukaryotic yeast, low-level radiation may induce an adaptive response to chronic radiation, whereas no such response could be detected when the cells were challenged with acute high-dose exposure or with MNNG.     

Simultaneous determination of quinine and four metabolites in plasma and urine by high-performance liquid chromatography

The determination of quinine, (3S)-3-hydroxyquinine, 2′-quininone and (10R)- and (10S)-10,11-dihydroxydihydroquinine in plasma and urine samples is described. This is the first time the R and S configurations have been correctly assigned to the two metabolites of 10,11-dihydroxyquinine. One hundred microliter-plasma samples were protein precipitated with 200 μl cold methanol. Urine samples were 10–100× diluted and then directly injected into the HPLC. A reversed-phase liquid chromatography system with fluorescence detection and a Zorbax Eclipse XDB phenyl column and gradient elution was used. The within and between assay coefficients of variation of the method for quinine and its metabolites in plasma and urine was less than 13%. The lower limit of quantitation was in the range of 0.024–0.081 μM.     

Recovery of intravenously infused chromium EDTA and lithium sulphate in the urine of cattle and their use as markers to measure urine volume

A series of metabolism experiments investigated the recovery of continuous-, intravenously infused chromium complexed with ethylenediamine tetra-acetic acid (CrEDTA) and lithium sulphate in the urine of cattle with a view to using the markers to estimate urine and metabolite output in grazing cattle. The recovery of Cr in urine from these infusions was similar (90%) in metabolism trials when cattle consumed three very contrasting diets: high-grain formulated pellet, lucerne hay (Medicago sativa) or low-quality native grass hay (predominantly Heteropogon contortus). By contrast, Li recovery in urine averaged 46.3 ± 0.40% and 72.6 ± 0.43% for native pasture and lucerne hays, respectively, but was not constant across days. There was negligible transfer of Cr from CrEDTA in blood serum to the rumen or faeces, whereas appreciable quantities of infused Li were found in both. The ratio of urine volume estimated by spot samples and marker dilution of Cr, to urine volume measured gravimetrically, was 1.05. In grazing studies using rumen-fistulated (RF) steers grazing seven different tropical and temperate grass and legume pastures, the ratio of concentrations of purine derivatives (PD) to Cr in spot samples of urine was shown to vary diurnally in the range of 49% to 157% of the average 24 h value. This finding indicated the need for regular sampling of urine to achieve an accurate average value for the PD : Cr ratio in urine for use in estimating urinary PD excretion and hence microbial protein production in the rumen. It was concluded that continuous, intravenous infusion of CrEDTA resulted in a constant recovery of Cr in the urine of cattle across diets and, provided an intensive sampling regime was followed to account for diurnal variation, it would be suitable as a marker to estimate urine volume and urinary output of PD in grazing cattle.     

Failure of exogenous LH to prevent PGF2α-induced luteolysis in beef cows

Henderson and McNatty (Prostaglandins 9:779, 1975) proposed that LH from the preovulatory LH surge attached to receptors on luteal cells and that this attachment might protect the early corpus luteum from PGF_2α induced luteolysis. To test this hypothesis, experiments were performed on heifers at day 10–12 of the cycle. Both jugular veins were catheterized and infusions of either saline (0.64 ml/min) or LH-NIH-B9 (10 μg/min; 0.64 ml/min) were given. Saline infusions were from 0–12 h; LH infusions were for 10 h and were preceded by a 2 h saline infusion. All animals were given 25 mg PGF_2α im at 6 h (6 h into the saline infusion and 4 h into the LH infusion). Blood samples were taken at 0.5 h, 1 h and 4 h intervals from 0–12, 13–18 h and 22–24 h respectively. Serum was assayed for LH and progesterone by radioimmunoassay methods. Two animals received saline and two received LH in each experiment. Eact treatment was replicated 6 times. LH infusion resulted in a mean serum LH of 57 ng/ml compared to 0.90 ng/ml in saline infused animals. This elevation of LH did not alter PGF_2α induced luteolysis as indicated by decline in serum progesterone. This experiment does not support the hypothesis that the newly formed corpus luteum is resistant to PGF_2α because of protection afforded by the protestrus LH surge.     

Meiotic recombination and synaptonemal complexes in Saccharomyces cerevisiae.

Summary The course of meiotic recombination, gene conversion and crossing-over, was investigated in Saccharomyces cerevisiae. Gene conversion was used as the selected event by removing cells from a medium inducing and promoting meiosis to a vegetative growth medium selective for convertants. Gene conversion started to increase at the same time as DNA synthesis, and nuclei entered a phase where the chromatin appeared as thread-like structures. Crossing-over of linked and unlinked markers also started early but remained at a low level until synaptonemal complexes were formed. However, gene conversion and a limited amount of crossing-over could be completed without synaptonemal complexes. It was concluded that meiotic recombination in yeast can occur as early as during DNA synthesis and does not require the function of synaptonemal complexes. Moreover, the low incidence of crossing-over early in meiosis is attributed to a low frequency of strand isomerization.     

Post-ruminal or intravenous infusions of carbohydrates or amino acids to dairy cows 1. Early lactation

The objectives of this study were to compare the effects of post-ruminal and intravenous infusions of wheat starch or glucose (CHO) or a mixture of amino acids (AA) on milk protein yield, nitrogen utilisation, plasma metabolites and mammary extraction rate of dairy cows in early lactation. Eight cow, ruminally fistulated, was assigned to two 4 × 4 Latin squares during 14-day periods, where the last 7 days were for infusions. Infusions were: (1) starch in the abomasum (SP), (2) glucose in the blood (GB), (3) AA in the abomasum (AP), and (4) AA in the blood (AB). The experiment started 54 ± 4 days (mean ± s.e.) post partum (milk yield 33.4 ± 1.7 kg). Daily amounts of nutrients infused were 378, 365, 341, and 333 g for SP, GB, AP and AB, respectively. The cows were fed a basal diet consisting of a concentrate mixture and grass silage (55:45 on dry-matter (DM) basis), and DM intake was 17.2 kg/day. Milk production was affected by site of infusion within substrate, whereas infusion substrates within infusion site (CHO or AA) were of minor importance. Compared with SP infusion, GB infusion increased ( P < 0.05) milk protein yield and concentration by 55 g and 1 g/kg. The AB infusion tended to ( P < 0.10) increase milk yield and ECM and increased ( P < 0.05) protein yield and concentration by 1.8 and 2.2 kg, 83 g and 1.1 g/kg compared with AP infusion, respectively. Nitrogen balance data indicated higher losses of metabolic faecal nitrogen (MFN) by abomasal than by intravenous infusions, and an increased ( P < 0.05) catabolism for AP and AB infusions compared with SP and GB infusions. GB infusion did not increase ( P>0.10) plasma glucose or insulin concentrations above that of SP infusion. Compared with the SP infusion, the GB infusion had minor effect on plasma AA. AP infusion increased ( P < 0.05) plasma non-essential AA (NEAA) concentration compared with AB infusion, whereas infusion site of AA had no effect ( P>0.05) on essential AA (EAA) or branched-chain AA (BCAA). Although a higher milk protein synthesis was observed for AB infusion, the mammary extraction rate was not higher ( P>0.05) than for AP infusion. Across infusion site, AP and AB infusions increased plasma concentration of EAA and BCAA, but compared with GB infusion, the mammary extraction rates tended ( P < 0.10) to be lower. It is concluded that abomasal nutrient infusion increases loss of MFN and that the gastrointestinal metabolism influences the nutrients available for milk synthesis. Our conclusion is that when glucose was infused, AA limited a further milk protein synthesis, but when AA was infused, glucose or energy substrate might have been the limiting factor. Our results verify that glucogenic substrates are limiting when cows are in negative energy balance.     

Meiotic recombination within the centromere of a yeast chromosome

In order to examine the frequency of nonreciprocal recombination (gene conversion) within the centromere of the yeast chromosome, we constructed strains that contained heterozygous restriction sites in the conserved centromere sequences of chromosome III in addition to heterozygous markers flanking the centromere. One of these markers was the selectable URA3 gene, which was inserted less than one kb from the centromere. We found that meiotic conversion of the URA3 gene occurred at normal frequency (about 2% of unselected tetrads) and that more than one-third of these convertants coconverted the markers within the centromere. In addition, we observed tetrads in which conversion events extended through the centromere to include a marker on the opposite side from URA3. We conclude that meiotic conversion events occur within the centromere at rates similar to other genomic sequences.     

Functional expression of parasite drug targets and their human orthologs in yeast

Background

The exacting nutritional requirements and complicated life cycles of parasites mean that they are not always amenable to high-throughput drug screening using automated procedures. Therefore, we have engineered the yeast Saccharomyces cerevisiae to act as a surrogate for expressing anti-parasitic targets from a range of biomedically important pathogens, to facilitate the rapid identification of new therapeutic agents.

Methodology/Principal Findings

Using pyrimethamine/dihydrofolate reductase (DHFR) as a model parasite drug/drug target system, we explore the potential of engineered yeast strains (expressing DHFR enzymes from Plasmodium falciparum, P. vivax, Homo sapiens, Schistosoma mansoni, Leishmania major, Trypanosoma brucei and T. cruzi) to exhibit appropriate differential sensitivity to pyrimethamine. Here, we demonstrate that yeast strains (lacking the major drug efflux pump, Pdr5p) expressing yeast (^ScDFR1), human (^HsDHFR), Schistosoma (^SmDHFR), and Trypanosoma (^TbDHFR and ^TcDHFR) DHFRs are insensitive to pyrimethamine treatment, whereas yeast strains producing Plasmodium (^PfDHFR and ^PvDHFR) DHFRs are hypersensitive. Reassuringly, yeast strains expressing field-verified, drug-resistant mutants of P. falciparum DHFR (^Pfdhfr ^51I,59R,108N) are completely insensitive to pyrimethamine, further validating our approach to drug screening. We further show the versatility of the approach by replacing yeast essential genes with other potential drug targets, namely phosphoglycerate kinases (PGKs) and N-myristoyl transferases (NMTs).

Conclusions/Significance

We have generated a number of yeast strains that can be successfully harnessed for the rapid and selective identification of urgently needed anti-parasitic agents.