Functional analysis of yeast essential genes using a promoter-substitution cassette and the tetracycline-regulatable dual expression system

A promoter-substitution cassette has been constructed that allows one-step substitution of chromosomal gene promoters for the tetracycline-regulatable tetO promoter in yeast cells, which uses kanMX4 as selective marker for geneticin resistance. Oligonucleotides for PCR amplification of the cassette are designed to allow homologous recombination through short flanking regions of homology with the upstream sequences of the chromosomal gene, upon transformation of target cells. By testing three essential genes of chromosome XV (YOL135c, YOL142w and YOL144w), the system causes tetracycline-dependent conditional growth of the cells, being modulatable by intermediate concentrations of the effector. Analysis of terminal phenotypes of the promoter-substituted cells in the presence of the antibiotic may facilitate functional analysis of essential orphan genes.

[Efficacy and safety of dotarizine vs. cinnarizine in the symptomatic treatment of acute balance disorders (common vertigo)]

One hundred and ten adult patients suffering from peripheral vertigo were treated in a multifactorial double-blind randomized clinical trial with dotarizine (50 mg b.i.d.) or cinnarizine (75 mg b.i.d.). There was a 60 days clinical follow-up. Results showed that dotarizine was significantly active against the vertigo attacks and its associated symptoms (mainly neurovegetative). The global superiority of dotarizine was confirmed by statistically significant differences between treatments in the improvement of the severity of vertigo, hearing loss in audiometries, global relief of symptoms, disability produced by crises and global assessment by the investigators themselves. No clinically significant unwanted effects were seen in either group on blood pressure, heart rate or analytical parameters. No serious adverse effects to dotarizine were reported. This study confirms the value of dotarizine in the treatment of peripheral vertigo.

An activator/repressor dual system allows tight tetracycline-regulated gene expression in budding yeast

We have developed an activator/repressor expression system for budding yeast in which tetracyclines control in opposite ways the ability of tetR-based activator and repressor molecules to bind tetO promoters. This combination allows tight expression of tetO- driven genes, both in a direct (tetracycline-repressible) and reverse (tetracycline-inducible) dual system. Ssn6 and Tup1, that are components of a general repressor complex in yeast, have been tested for their repressing properties in the dual system, using lacZ and CLN2 as reporter genes. Ssn6 gives better results and allows complete switching-off of the regulated genes, although increasing the levels of the Tup1-based repressor by expressing it from a stronger promoter improves repressing efficiency of the latter. Effector-mediated shifts between expression and non-expression conditions are rapid. The dual system here described may be useful for the functional analysis of essential genes whose conditional expression can be tightly controlled by tetracyclines.

The Cln3 cyclin is down-regulated by translational repression and degradation during the G1 arrest caused by nitrogen deprivation in budding yeast

Nutrients are among the most important trophic factors in all organisms. When deprived of essential nutrients, yeast cells use accumulated reserves to complete the current cycle and arrest in the following G1 phase. We show here that the Cln3 cyclin, which has a key role in the timely activation of SBF (Swi4-Swi6)- and MBF (Mbp1-Swi6)-dependent promoters in late G1, is down-regulated rapidly at a post-transcriptional level in cells deprived of the nitrogen source. In addition to the fact that Cln3 is degraded faster by ubiquitin-dependent mechanisms, we have found that translation of the CLN3 mRNA is repressed approximately 8-fold under nitrogen deprivation conditions. As a consequence, both SBF- and MBF-dependent expression is strongly down-regulated. Mainly because of their transcriptional dependence on SBF, and perhaps with the contribution of similar post-transcriptional mechanisms to those found for Cln3, the G1 cyclins Cln1 and 2 become undetectable in starved cells. The complete loss of Cln cyclins and the sustained presence of the Clb-cyclin kinase inhibitor Sic1 in starved cells may provide the molecular basis for the G1 arrest caused by nitrogen deprivation.

Hantavirus pulmonary syndrome in the Province of Rio Negro, Argentina, 1993-1996

Early in 1995 the first case of Hantavirus Pulmonary Syndrome was serologically confirmed in El Bolsón (Province of Río Negro, Argentina), corresponding to the third outbreak reported in Argentina. A total of 26 cases of HPS related to the Andean region of Rio Negro Province, were reported from 1993 to 1996, 17 in El Bolsón, 4 in San Carlos de Bariloche, and 5 in Buenos Aires. The incidence rate was 5.03 x 100,000 with a mortality rate of 51.85 x 100. The occurrence of cases was mainly seasonal, with a significantly greater number in the spring, and the persons affected mainly lived in urban or periurban areas. In four cases, the affected individuals were members of a couple, spouses or live-in contacts. Seven cases were Health workers (physicians, nurses or administrative staff). Twelve cases were related among them, due to an outbreak of 80 days. Two of them did not visit the Andean region. A total of 139 rodents were captured and seven of them, Olygoryzomys longicaudatus, were found to be serologically positive. The possibility of infection by contact with rodents or fecal matter is being analyzed and also hypothesis related with interhuman transmission.

A set of vectors with a tetracycline-regulatable promoter system for modulated gene expression in Saccharomyces cerevisiae

A set of Saccharomyces cerevisiae expression vectors has been developed in which transcription is driven by a hybrid tetO-CYC1 promoter through the action of a tetR-VP16 (tTA) activator. Expression from the promoter is regulated by tetracycline or derivatives. Various modalities of promoter and activator are used in order to achieve different levels of maximal expression. In the presence of antibiotic in the growth medium at concentrations that do not affect cell growth, expression from the tetO promoter is negligible, and upon antibiotic removal induction ratios of up to 1000-fold are observed with a lacZ reporter system. With the strongest system, overexpression levels comparable with those observed with GAL1-driven promoters are reached. For each particular promoter/tTA combination, expression can be modulated by changing the tetracycline concentration in the growth medium. These vectors may be useful for the study of the function of essential genes in yeast, as well as for phenotypic analysis of genes in overexpression conditions, without restrictions imposed by growth medium composition.

The AFT1 transcriptional factor is differentially required for expression of high-affinity iron uptake genes in Saccharomyces cerevisiae

High-affinity iron uptake in Saccharomyces cerevisiae involves the extracytoplasmic reduction of ferric ions by FRE1 and FRE2 reductases. Ferrous ions are then transported across the plasma membrane through the FET3 oxidase-FTR1 permease complex. Expression of the high-affinity iron uptake genes is induced upon iron deprivation. We demonstrate that AFT1 is differentially involved in such regulation. Aft1 protein is required for maintaining detectable non-induced level of FET3 expression and for induction of FRE2 in iron starvation conditions. On the contrary, FRE1 mRNA induction is normal in the absence of Aft1, although the existence of AFT1 point mutations causing constitutive expression of FRE1 (Yamaguchi-Iwai et al., EMBO J. 14: 1231-1239, 1995) indicates that Aft1 may also participate in FRE1 expression in a dispensable way. The alterations in the basal levels of expression of the high-affinity iron uptake genes may explain why the AFT1 mutant is unable to grow on respirable carbon sources. Overexpression of AFT1 leads to growth arrest of the G1 stage of the cell cycle. Aft1 is a transcriptional activator that would be part of the different transcriptional complexes interacting with the promoter of the high-affinity iron uptake genes. Aft1 displays phosphorylation modifications depending on the growth stage of the cells, and it might link induction of genes for iron uptake to other metabolically dominant requirement for cell growth.

Clinical pharmacokinetics and tolerability of dotarizine in healthy subjects after single and multiple oral administration

Dotarizine is a new diphenylmethylpiperazine derivative with Ca2+ channel blocking properties and inhibitory effects on 5-HT2A and 5-HT2C receptors. Previous pilot studies in healthy volunteers demonstrated a good tolerability after single and multiple dosing. Dotarizine appeared to be rapidly and extensively metabolized to an active compound (FI-6020). We aimed to study the physiologic, subjective and psychomotor acute effects of oral dotarizine after single dose administration, to evaluate the tolerability and safety after multiple dosing over 2 weeks, and to study the pharmacokinetic parameters and linearity after single and multiple administration. Two different studies were carried out in 2 groups of 8 healthy male volunteers. Oral single doses of dotarizine 50, 100 and 200 mg were administered in a randomized, double-blind, crossover, placebo-controlled trial. Oral doses of 50 mg twice daily were administered in an open trial over 14 days. Drug effect assessments included vital signs, collection of adverse events, ECG and blood and urine safety evaluations, subjective effects, psychomotor performance tasks and blood sampling. Dotarizine and its metabolite were determined by gas chromatography with N-P detector. The results showed a good tolerability of dotarizine after single oral doses as well as multiple oral doses over 14 days. No clinically relevant adverse events were reported during the study. The highest single dose (200 mg) produced a slight increase in sedation-related symptoms as well as a slight impairment in psychomotor performance tasks. Dotarizine and its major metabolite proved linear kinetics at single doses. The administration of oral doses of dotarizine 50 mg b.i.d. reached the steady state after the 7th day of treatment. The pharmacokinetic parameters remained similar from day 7 to day 14. The terminal elimination half-life of dotarizine and its metabolite appeared to be between 7 and 12 h.

Efficacy of ebrotidine and ranitidine in the treatment of benign gastric ulcer

This is a phase III, randomized, double-blind, clinical trial with two parallel groups of 50 patients to assess the efficacy of ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl]methyl]thio]ethyl ] amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) 800 mg and ranitidine 300 mg as a single evening dose in the treatment of benign gastric peptic ulcer. Prior to treatment, an endoscopy was performed to detect ulcer lesions and to discard malignancies. Clinical and endoscopic examinations were performed at 6, 9 and 12 weeks. Healing rates were significant for both treatments at week 6, while at week 12 there was statistical significance for ebrotidine as compared to ranitidine (96% vs 88% in the intention-to-treat analysis and 98% vs 87.5% in the per protocol analysis). Decrease in ulcer diameter was significant for both treatments at week 6, and for ebrotidine versus ranitidine at weeks 9 and 12. The overall improvement of symptoms was higher with ebrotidine, which was already significant at week 6. Safety was considered to be excellent, since no significant adverse events were reported for the patients included in the study.

Pharmacokinetics of ebrotidine in healthy volunteers. A summary

Several clinical pharmacokinetic studies of ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl] methyl]thio]ethyl]amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) administered by oral route in single and multiple doses to healthy volunteers have been performed. Dosage levels were 150, 300, 400, 500, 600 and 800 mg. Plasma concentrations of unchanged ebrotidine and its major metabolite, ebrotidine sulfoxide, excreted in the urine were determined. The main pharmacokinetic parameters were calculated from the experimental data. Absorption was relatively rapid (Imax = 2 h) and unrelated to dose. Drug behavior was considered as reasonably linear: Cmax = 364-1168 ng/ml and AUC0-12 h = 1427-5997 ng.h/ml (doses from 150 mg to 800 mg). The mean values of terminal elimination half-life (t1/2 beta) ranged from 13.9 to 20.3 h (doses of 400, 600 and 800 mg). After multiple dosing there was no drug accumulation, and no significant changes in the mean values of the main pharmacokinetic parameters were observed. The steady state was reached from the second day of administration, 10-24% of the ebrotidine administered dose was excreted in urine mainly as its major metabolite, ebrotidine sulfoxide, as well as unchanged drug and other minor metabolites. These percentages were constant and independent of the dose administered.

Continuous intragastric pH monitoring in the evaluation of ebrotidine, cimetidine and placebo on gastric acidity in healthy volunteers

This study was conducted to determine the efficacy and tolerance of ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl) methyl]thio]ethyl]amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43.9, FI-3542), a new H2-receptor antagonist, on reducing gastric acidity after a single 800 mg dose, compared with cimetidine 800 mg once daily and placebo by means of a continuous intragastric pH monitoring. A total of 30 healthy volunteers were allocated to receive in a double blind, parallel design the study medication. Clinical observations, physical examinations and visual analogue scales (VAS) were performed during the study to assess the tolerability of the three treatments. Ebrotidine and cimetidine caused a greater and longer-lasting gastric acid inhibition than placebo. With ebrotidine, significantly (p < 0.05) higher median pH values (and interquartile range, IQR) were reached in the post-administration (2.61, IQR 2.02-3.93), postprandial (3.38, IQR 2.82-3.91) and nocturnal (2.83, IQR 1.69-3.77) periods than with placebo: 1.82 (IQR, 1.66-2.09), 2.81 (IQR, 2.02-3.28), and 1.89 (IQR, 1.44-2.13), respectively. Cimetidine showed significant differences compared to placebo in the post-administration (2.36, IQR 1.89-3.46) and nocturnal (2.46, IQR 1.88-4.33) periods. No statistical differences were observed between the active treatments. Ebrotidine caused a significantly higher percentage of time above pH 2.0 in the post-administration and nocturnal periods compared to placebo (p < 0.05), and above pH 3.0 in the post-administration, postprandial and nocturnal periods. No serious adverse effects, or disturbances in the VAS or in the vital signs were reported, and all medications were well tolerated. It is concluded that a single dose of ebrotidine 800 mg is as effective as cimetidine 800 mg in reducing total and nocturnal intragastric acidity. The study also confirms the excellent safety profile of the new drug.

Ebrotidine versus ranitidine in the treatment of acute duodenal ulcer. A multicentre, randomized, double-blind, controlled clinical trial

A total of 478 patients with endoscopically confirmed duodenal ulcer entered this randomized, parallel, double-blind trial. Patients were randomly assigned to receive ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]- 4-thiazolyl]methyl]thio]ethyl]amino]methylene]-4-bromo-benzenesulfona mid e, CAS 100981-43-9, FI-3542) 400 mg or ranitidine 300 mg tablets (4:1) respectively, administered in single evening doses. Endoscopy, clinical examination and symptom assessment were performed at baseline and at weeks 4 and 8. Safety evaluations including laboratory tests, treatment compliance and antacid consumption checks were conducted at the beginning and/or at the 4 and 8 week visits. Patients whose ulcer showed endoscopic healing at the 4-week control left the study. Both groups were matched in all parameters studied. The healing rates at 4 weeks were 76.4% and 75.3% for ebrotidine and ranitidine respectively, while at 8 weeks the final rates were 95% and 91.8% respectively. Accompanying symptoms disappeared rapidly and the patients returned to normal. Smoking proved to be a highly significant negative risk factor, since healing rates were 83.4% and 71.2% at 4 weeks and 97.4% and 92.3% at 8 weeks in non-smokers and smokers respectively (p = 0.0046). Smokers treated with ranitidine showed significantly lower final healing rates than non-smokers (86% vs 100%; p = 0.0358), while the healing rates among patients treated with ebrotidine were similar regardless of whether they were smokers or not (93.9% and 96.7% N.S.). Ebrotidine (94%) proved to be more effective than ranitidine (86%) in smokers with higher healing rates (p < 0.05). Alcohol intake showed no significant relationship with the healing rates. Both drugs demonstrated an excellent safety. There were no changes in blood parameters, and no significant adverse events were reported.

Studies on the protective effect of ebrotidine on experimental ulcers induced by non-steroidal anti-inflammatory drugs in healthy volunteers

Ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]- 4-thiazolyl]methyl]thio]ethyl]amino]methylene]-4-bromo-benzenesulfonamid e, CAS 100981-43-9, FI-3542) is a new H2-receptor antagonist providing a new therapy for the prevention and healing of non-steroidal anti-inflammatory drugs-induced gastroduodenal lesions. Carbonic anhydrase is a zinc enzyme, and its isozyme (carbonic anhydrase II) in parietal cells plays a central role in HCl secretion. The effects of ebrotidine on carbonic anhydrase in human subjects are reported. Eighteen healthy volunteers were distributed in 3 equal subgroups and treated for 10 days as follows: ebrotidine 800 mg/d p.o. (Group A); indometacin 4 mg/kg/d p.o. in 3 divided doses (Group B); ebrotidine 800 mg/d p.o. plus indometacin 4 mg/kg/d p.o. (Group C). Assessment of the enzymatic activity of carbonic anhydrase was based on the colorimetric method of changing pH with the stopped-flow technique. In group A, ebrotidine reduced total gastric mucosal carbonic anhydrase activity by 62%; in group B, indometacin increased carbonic anhydrase activity in gastric mucosa by 138%; in group C, the combined treatment with ebrotidine plus indometacin decreased gastric mucosal carbonic anhydrase activity by 38%. The present study shows that, unlike ranitidine, ebrotidine, a competitive H2-receptor antagonist, is also a non-competitive inhibitor of carbonic anhydrase I and II. By antagonizing the activating effects of indometacin on gastric mucosal carbonic anhydrase, ebrotidine prevents mucosal lesions caused by anti-inflammatory drugs.

Efficacy of ebrotidine and ranitidine combined with amoxicillin and metronidazole in the eradication of Helicobacter pylori in patients with duodenal ulcer

This double-blind, randomized, phase III clinical trial was carried out in two parallel groups to assess the efficacy of ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene) amino]-4-thiazolyl]methyl]thio]ethyl]amino] methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) 400 mg and ranitidine 300 mg given in single evening dose, combined with amoxicillin 750 mg and metronidazole 500 mg three times daily for 14 days, in the eradication of Helicobacter pylori in patients with duodenal ulcer. Thirty patients were included, divided into two groups of 15, to whom one of the study therapies was administered based on a randomization code. Clinical and endoscopic controls were performed 4, 6 and 8 weeks after the onset of the treatment. No differences were seen between the two treatment groups with regard to demographic parameters and clinical histories. They were both perfectly homogeneous. There were no differences between the eradication of both therapies in both the antrum and gastric body samples (over 80% eradication), allowing the results to be classified as satisfactory. Moreover, perfect control was achieved through the study of clinical symptoms, which even disappeared in some cases. There were no differences in the healing rate of the duodenal ulcer after four weeks, 86.7% being achieved for both groups.

Comparative study of the safety and efficacy of ebrotidine versus ranitidine and placebo in the prevention of piroxicam-induced gastroduodenal lesions

This study assessed the efficacy of ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl] methyl]thio]ethyl]amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) versus ranitidine and placebo in preventing gastroduodenal lesions induced by piroxicam. Thirty patients with rheumatic disease, who were divided into 5 groups, received an oral treatment of piroxicam 20 mg once daily for 6 days plus ebrotidine 400 mg/day (Group I); ebrotidine 800 mg/day (Group II); ranitidine 150 mg/day (Group III); ranitidine 300 mg/day (Group IV); or placebo (Group V). Patients were endoscopically examined before and after treatment. Lanza's score was also determined, and laboratory tests were performed. The results of this study showed that the most powerful protective effect against mucosal gastric lesions induced by piroxicam was achieved with 800 mg/day of ebrotidine. Ranitidine at doses of 150 mg/day did not protect gastric mucosa, and the 300 mg/day dose exerted a poor gastroprotective effect.

Tolerability and pharmacokinetics of ebrotidine in healthy subjects given single and repeated oral doses

The tolerability and safety of ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl]methyl] thio]ethyl]amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) and its basic pharmacokinetic parameters were determined after its oral administration to healthy volunteers. Sixteen subjects were selected to participate in two different studies: an increasing single dose study to determine the maximal tolerated dose (from 25 to 1600 mg), and a multiple dose study (stepped doses from 400 to 1600 mg daily for 12 days). The results of the studies showed that ebrotidine has a good tolerability. Vital signs and laboratory tests were not influenced by the study treatment. No clinically relevant adverse effects were reported during the investigation. Ebrotidine reached peak plasma concentrations 2-3 h after oral administration. Its elimination half-life ranged from 9 to 14 h. In conclusion, ebrotidine was well tolerated after administration of oral single doses of up to 1600 mg, and after repeated administration of up to 800 mg/12 h for 12 days.

Purine metabolism in patients with gout: the role of lead

Primary gout is characterized by increased plasma and decreased urinary concentrations of hypoxanthine, xanthine and uric acid. To examine whether lead could explain the disturbance of purine metabolism in gout, we determined hypoxanthine, xanthine and uric acid metabolism and 5-day cumulative urinary lead excretion rates after an EDTA (calcium disodium edetate) test in 27 patients with primary gout and reduced creatinine clearance (C(cr)) and in 50 patients with gout and normal C(cr). The results were compared to those obtained in 26 normal subjects matched for age. All gout patients evidenced a marked renal underexcretion of hypoxanthine, xanthine and uric acid relative to their increased plasma levels. Purine metabolism was remarkably similar in both gout groups except for a significantly lower uric acid excretion in patients with reduced C(cr). Blood lead levels and cumulative lead excretion rates were significantly higher in gout patients with renal failure as compared to patients with normal C(cr). Fourteen patients (52%) with renal insufficiency and 6 (12%) with normal C(cr) showed increased lead excretion rates (95% Cl for the difference, 29-51%, p < 0.001). Mobilizable lead was not significantly correlated with serum or urinary purine concentrations. Hypoxanthine, xanthine and uric acid underexcretion was similar in gout patients with increased or normal cumulative lead excretion rates. The prevalence of atheromatosis and arterial hypertension together was significantly higher in gout patients with renal failure than in patients with normal C(cr) (81 vs. 60%, 95% Cl for the difference, 11-31%, p < 0.005). These results indicate that lead is not a significant contributor to the renal underexcretion of purines in gout. An increased mobilizable lead is not by itself evidence that lead is the cause of the renal insufficiency in patients with primary gout. Atheromatous nephropathy and/or nephroangiosclerosis may explain impaired renal function in patients with primary gout.

Sequence analysis of a 12 801 bp fragment of the left arm of yeast chromosome XV containing a putative 6-phosphofructo-2-kinase gene, a gene for a possible glycophospholipid-anchored surface protein and six other open reading frames

The DNA sequence of a 12,801 bp fragment located near the left telomere of chromosome XV has been determined. Sequence analysis reveals eight open reading frames (ORFs) encoding polypeptides larger than 100 residues. ORFs AOE129 and AOAA121 are in opposite strands and they overlap at their 3' ends. AOE397 has similarity with phosphofructokinase genes from other organisms and may code for a second 6-phosphofructo-2-kinase of Saccharomyces cerevisiae. Sequence of AOA471 shows significant similarity with yeast genes coding for glycophospholipid-containing proteins. AOD1341 would code for a 1341 amino acids long protein with a predicted ATP/GTP-binding site and a transmembrane domain.

Sequence analysis of a 13.4 kbp fragment from the left arm of chromosome XV reveals a malate dehydrogenase gene, a putative Ser/Thr protein kinase, the ribosomal L25 gene and four new open reading frames

A 13421 bp fragment located near the left telomere of chromosome XV (cosmid pEOA461) has been sequenced. Seven non-overlapping open reading frames (ORFs) encoding polypeptides longer than 100 residues have been found (AOB859, AOC184, AOE375, AOX142i, AOE423, AOA476 and AOE433). An additional ORF (AOE131) is found within AOA476. Three of them (AOC184, AOA476 and AOE433) show no remarkable identity with proteins deposited in the data banks. ORF AOB859 is quite similar to a hypothetical yeast protein of similar size located in chromosome VI, particularly within the C-terminal half. AOE375 encodes a new member of the glycogen synthase kinase-3 subfamily of Ser/Thr protein kinases. AOX142i is the gene encoding the previously described ribosomal protein L25. AOE423 codes for a protein virtually identical to the MDH2 malate dehydrogenase isozyme. However, our DNA sequence shows a single one-base insertion upstream of the reported initiating codon. This would produce a larger ORF by extending 46 residues the N-terminus of the protein. The existence of this insertion has been confirmed in three different yeast strains, including FY1679.

Analysis of the DNA sequence of a 15,500 bp fragment near the left telomere of chromosome XV from Saccharomyces cerevisiae reveals a putative sugar transporter, a carboxypeptidase homologue and two new open reading frames

We report the sequence of a 15.5 kb DNA segment located near the left telomere of chromosome XV of Saccharomyces cerevisiae. The sequence contains nine open reading frames (ORFs) longer than 300 bp. Three of them are internal to other ones. One corresponds to the gene LGT3 that encodes a putative sugar transporter. Three adjacent ORFs were separated by two stop codons in frame. These ORFs presented homology with the gene CPS1 that encodes carboxypeptidase S. The stop codons were not found in the same sequence derived from another yeast strain. Two other ORFs without significant homology in databases were also found. One of them, O0420, is very rich in serine and threonine and presents a series of repeated or similar amino acid stretches along the sequence.