Chromosome Length Polymorphism Research Articles

Finger printing-RFLP analysis of chromosomal IS6110 insertion sequence and PCR diagnosis of pulmonary tuberculosis, isolated from patients in El Hajeb region of Morocco

Tuberculosis (TB) is one of the contagious diseases caused by M. tuberculosis (MTB) bacteria. Prompt diagnosis is one of the active solutions to control the spread of this infection. Besides, a targeted, specific and non-complex diagnosis can prove promising in this type of epidemic. This study was designed to compare the efficiencies of a diagnosis by Ziehl-Neelsen staining (ZN) and by the polymerase chain reaction (PCR) technique. Samples presented smear-positive pulmonary TB were subjected to Chromosomal restriction fragment length polymorphism of IS6110 (IS6110-RFLP) for fingerprinting profile determination.The results showed that out of 100 sputum samples of suspected case, 53 were positive. Numbers of positive individuals for tuberculosis obtained by the different diagnostic techniques, to know, (ZN staining; culture and PCR) were respectively: 6, 25 and 22. Chromosomal RFLP fingerprinting profile revealed the presence of five different genotypes obtained from seven tested isolates.These results suggest that molecular techniques are alternative tool for fast and specific diagnosis of pulmonary MTB from sputum.

Trypanosoma cruzi Genomic Variability: Array Comparative Genomic Hybridization Analysis of Clone and Parental Strain.

Trypanosoma cruzi, the etiological agent of Chagas disease, exhibits extensive inter- and intrastrain genetic diversity. As we have previously described, there are some genetic differences between the parental G strain and its clone D11, which was isolated by the limiting dilution method and infection of cultured mammalian cells. Electrophoretic karyotyping and Southern blot hybridization of chromosomal bands with specific markers revealed chromosome length polymorphisms of small size with additional chromosomal bands in clone D11 and the maintenance of large syntenic groups. Both G strain and clone D11 belong to the T. cruzi lineage TcI. Here, we designed intraspecific array-based comparative genomic hybridization (aCGH) to identify chromosomal regions harboring copy-number variations between clone D11 and the G strain. DNA losses were more extensive than DNA gains in clone D11. Most alterations were flanked by repeated sequences from multigene families that could be involved in the duplication and deletion events. Several rearrangements were detected by chromoblot hybridization and confirmed by aCGH. We have integrated the information of genomic sequence data obtained by aCGH to the electrophoretic karyotype, allowing the reconstruction of possible recombination events that could have generated the karyotype of clone D11. These rearrangements may be explained by unequal crossing over between sister or homologous chromatids mediated by flanking repeated sequences and unequal homologous recombination via break-induced replication. The genomic changes detected by aCGH suggest the presence of a dynamic genome that responds to environmental stress by varying the number of gene copies and generating segmental aneuploidy.

Evaluation of Chromosomal Structural Anomalies in Fertility Disorders.

Background and objectives: Reproductive disorders may occur not only due to environmental factors (air pollution, stressful lifestyle, previous abortions or the use of contraceptives) but also due to genetic factors. Materials and Methods: The aim of the study was to identify the range and frequency of chromosomal aberrations in couples (n = 99) with infertility or recurrent miscarriages in Lithuania. The data were collected from the out-patient medical histories. The couples were divided into three groups based on pregnancy, childbirth and the number of miscarriages. The Chi-square test was used to carry out the statistical analysis, and the statistical significance was (p < 0.05). Results: There were 6.6% (n = 13) structural changes observed in the karyotype tests. Chromosomal aberrations were found in 3% (n = 6) of the subjects, while 3.6% (n = 7) of them had chromosomal length polymorphisms. No difference was found between the aberration frequency in the karyotypes of men and women (p > 0.05). The most common aberrations were balanced translocations (23.1%, n = 3) which accounted for 15.4% of the reciprocal (n = 2) and 7.7% of the Robertsonian type (n = 1) of translocations. The most frequent aberrations were found in couples with the inability to conceive (42.9% (n = 3), p = 0.031). The childless couples and those with recurrent miscarriages showed an aberration rate of 8.2% (n = 5), while in the couples with at least one child it was 16.1% (n = 5). The group of couples unable to conceive had a significantly higher aberration rate of 28.6% (n = 2), p = 0.029. Miscarriages in partners’ families accounted for 8.1%. Miscarriages on the female side of the family accounted for 4.5% (n = 9), on the male side it accounted for 2.5% (n = 5) and on both sides it accounted for 1.1% (n = 2). There were no statistically significant differences observed between the female and male sides (p > 0.05). The miscarriages observed in the second group of couples (childless with ≥2 miscarriages) were more frequent at 18.1% (n = 11), in the third group (having children ≥2 miscarriages) they were less frequent at 12.9% (n = 4), while no miscarriages were recorded in the first group of infertile couples. In total, 3% of the identified significant chromosomal aberrations were likely to trigger miscarriages or the inability to conceive. Conclusions: In couples with reproductive disorders, chromosomal mutations and chromosomal length polymorphisms were found at similar rates: 3% vs. 3.6%. The highest aberration rate was found in couples that were unable to conceive, a lower one was found in a group with children and ≥2 miscarriages, and the lowest one was found in a childless group of subjects with ≥2 miscarriages. The miscarriage rate in partner families was 8.1%; however, no difference was found between the male and female sides.

Role of homologous recombination genesRAD51,RAD52, andRAD59in the repair of lesions caused by γ-radiation to cycling and G2/M-arrested cells ofCandida albicans

We have analysed the role of homologous recombination (HR) genes on the repair of double-strand breaks induced by γ-ionising radiation in Candida albicans. Depletion of either CaRad51 or CaRad52 caused a dramatic drop in the number of survivors compared with wild type, whereas depletion of CaRad59 caused a moderate decrease. Besides, compared with Saccharomyces cerevisiae, C.albicans relies more on HR proteins for repair of ionising radiation lesions. Pulse-field electrokaryotypes of survivors identified genetic alterations mainly in the form of aneuploidy in HR mutants and chromosome length polymorphism and ectopic translocation in wild type. Increasing irradiation (4 to 80krad) of both cycling and nocodazole-treated (G2/M-arrested) cells revealed a gradual loss of chromosomes, larger chromosomes being more affected than smaller ones. For cycling wild-type cells, shattered chromosomes were progressively restored following incubation in yeast extract, peptone, dextrose medium, but not in phosphate-buffered saline, and this accompanied by a moderate increase in colony-forming units, suggesting that repair was followed by replication of survivors. Irradiated G2/M arrested cells from wild type but not from HR mutants partially restored the chromosome ladder following incubation (4-8hr) in yeast peptone dextrose-nocodazole. However, HR mutants showed a chromosome shattering pattern similar to wild type, an indication that lesions other than double-strand breaks, likely single-strand break, are responsible for their drastically reduced survivability.

Intraspecies polymorphisms of Kluyveromyces marxianus strains from Yaghnob valley

In this study, 29 strains of Kluyveromyces marxianus with peculiar genetic and phenotypic traits previously isolated from a fermented goat milk of Yaghnob valley were investigated for chromosome length polymorphism (CLP) by PFGE, adhesion properties and carbon usage by Biolog analysis. Obtained data showed that strains differed in terms of number and size of chromosome bands. The number of bands ranged from 5 to 7, suggesting a probable genome size from 1.4 to 2.6 Mb. Strains showed a certain level of cell surface hydrophobicity ranging from 32% to 77.7%. Strains were also tested for their ability to form a biofilm on polystyrene plates: planktonic cells ranged from 6.3 cfu/mL to 7.95 cfu/mL, while sessile from 7.11 cfu/mL to 8.6 cfu/mL. The strains able to adhere to polystyrene plates were also able to form a mature MAT. Biolog analysis revealed that almost all strains were able to use putrescine, malic acid, α-D lactose, phenylethylamine, β-methyl D-gucoside and xylose; 5 strains were able to grow on cellobiose and 3 were able to catabolise α-ketobutyric. The obtained data highlighted a number of interesting features underlying the peculiar capacities of these strains for industrial applications.

Combating a Global Threat to a Clonal Crop: Banana Black Sigatoka Pathogen Pseudocercospora fijiensis (Synonym Mycosphaerella fijiensis) Genomes Reveal Clues for Disease Control.

Black Sigatoka or black leaf streak disease, caused by the Dothideomycete fungus Pseudocercospora fijiensis (previously: Mycosphaerella fijiensis), is the most significant foliar disease of banana worldwide. Due to the lack of effective host resistance, management of this disease requires frequent fungicide applications, which greatly increase the economic and environmental costs to produce banana. Weekly applications in most banana plantations lead to rapid evolution of fungicide-resistant strains within populations causing disease-control failures throughout the world. Given its extremely high economic importance, two strains of P. fijiensis were sequenced and assembled with the aid of a new genetic linkage map. The 74-Mb genome of P. fijiensis is massively expanded by LTR retrotransposons, making it the largest genome within the Dothideomycetes. Melting-curve assays suggest that the genomes of two closely related members of the Sigatoka disease complex, P. eumusae and P. musae, also are expanded. Electrophoretic karyotyping and analyses of molecular markers in P. fijiensis field populations showed chromosome-length polymorphisms and high genetic diversity. Genetic differentiation was also detected using neutral markers, suggesting strong selection with limited gene flow at the studied geographic scale. Frequencies of fungicide resistance in fungicide-treated plantations were much higher than those in untreated wild-type P. fijiensis populations. A homologue of the Cladosporium fulvum Avr4 effector, PfAvr4, was identified in the P. fijiensis genome. Infiltration of the purified PfAVR4 protein into leaves of the resistant banana variety Calcutta 4 resulted in a hypersensitive-like response. This result suggests that Calcutta 4 could carry an unknown resistance gene recognizing PfAVR4. Besides adding to our understanding of the overall Dothideomycete genome structures, the P. fijiensis genome will aid in developing fungicide treatment schedules to combat this pathogen and in improving the efficiency of banana breeding programs.

Unisexual and Heterosexual Meiotic Reproduction Generate Aneuploidy and Phenotypic Diversity De Novo in the Yeast Cryptococcus neoformans

Author SummaryAneuploidy refers to increases or decreases in the copy number of individual chromosomes (rather than of the entire haploid or diploid genome). In humans, aneuploidy is well known to be deleterious, causing genetic disorders such as Down syndrome (trisomy 21), and frequently occurring during mitosis in the genesis of cancer. By contrast, aneuploidy in fungi can be advantageous, conferring antifungal drug resistance and enabling rapid adaptive evolution. Cryptococcus neoformans is a globally distributed human pathogen that often infects patients with compromised immunity. It accounts for significant morbidity and mortality associated with HIV/AIDS and is linked to more than one million infections and >600,000 deaths per year world-wide. Although C. neoformans has a defined heterosexual cycle involving a and α cells, more than 99% of clinical and environmental isolates are α. Interestingly, C. neoformans α cells undergo α-α unisexual reproduction to generate diploid intermediates and infectious haploid spores. Sex is costly, though, and the question therefore arises as to why C. neoformans would undergo selfing unisexual, meiotic reproduction as opposed to more efficient asexual, mitotic reproduction. We show here that unisexual, meiotic reproduction in C. neoformans results in aneuploidy, creating advantageous genetic diversity de novo.

Interclonal Variations in the Molecular Karyotype of Trypanosoma cruzi: Chromosome Rearrangements in a Single Cell-Derived Clone of the G Strain

Trypanosoma cruzi comprises a pool of populations which are genetically diverse in terms of DNA content, growth and infectivity. Inter- and intra-strain karyotype heterogeneities have been reported, suggesting that chromosomal rearrangements occurred during the evolution of this parasite. Clone D11 is a single-cell-derived clone of the T. cruzi G strain selected by the minimal dilution method and by infecting Vero cells with metacyclic trypomastigotes. Here we report that the karyotype of clone D11 differs from that of the G strain in both number and size of chromosomal bands. Large chromosomal rearrangement was observed in the chromosomes carrying the tubulin loci. However, most of the chromosome length polymorphisms were of small amplitude, and the absence of one band in clone D11 in relation to its reference position in the G strain could be correlated to the presence of a novel band migrating above or below this position. Despite the presence of chromosomal polymorphism, large syntenic groups were conserved between the isolates. The appearance of new chromosomal bands in clone D11 could be explained by chromosome fusion followed by a chromosome break or interchromosomal exchange of large DNA segments. Our results also suggest that telomeric regions are involved in this process. The variant represented by clone D11 could have been induced by the stress of the cloning procedure or could, as has been suggested for Leishmania infantum, have emerged from a multiclonal, mosaic parasite population submitted to frequent DNA amplification/deletion events, leading to a 'mosaic' structure with different individuals having differently sized versions of the same chromosomes. If this is the case, the variant represented by clone D11 would be better adapted to survive the stress induced by cloning, which includes intracellular development in the mammalian cell. Karyotype polymorphism could be part of the T. cruzi arsenal for responding to environmental pressure.

Two‐Dimensional Pulsed Field Minigel Electrophoresis with High Throughput Sample Format

AbstractA rapid procedure for two‐dimensional pulsed field minigel electrophoresis (2D‐mini‐PFGE) with high throughput sample format was standardized to separate chromosomal DNA molecules of yeast. Molecules separation in the first dimension (1D) was done in 4.5 h using the contour‐clamped homogeneous electric field minichamber. 1D‐minigel was negatively stained with zinc‐imidazole and the lanes containing the chromosomal bands were excised from the 1D‐minigel. The strips were loaded into the second dimension (2D) minigel(s). 2D runs were performed in the single or multiple minigels of the transversal alternating field electrophoresis (TAFE) or multi‐TAFE minichamber, respectively, for 7 h. Total running time (1D + 2D) was 11.5 h. The 2D‐mini‐PFGE resolved co‐migrating molecules in the Saccharomyces cerevisiae 1D‐electrophoretic karyotypes and detected chromosome length polymorphisms in three distinct strains. Also, the multi‐TAFE minichamber allowed obtaining up to 12 2D‐DNA patterns simultaneously. This procedure could be suitable for monitoring of industrial yeast strains by molecular methods.Practical ApplicationsThis work reports the standardization of a rapid and economic two‐dimensional pulsed field minigel electrophoresis procedure with high throughput sample format to separate DNA molecules with chromosomal sizes. This procedure enhances the resolution of chromosomal DNA molecules in the 1D‐electrophoretic karyotypes from microorganisms and reveals chromosome length polymorphisms of different yeast strains without using restriction enzymes. The procedure also includes the staining of the 1D‐minigels with zinc‐imidazole. It avoids the environmental pollution caused by the ethidium bromide when the 1D‐DNA molecules are visualized and prevents DNA damages due to UV‐irradiation. The procedure permits to analyze from 1 to 12 DNA samples by 2D‐PFGE simultaneously. It could be suitable for maintenance, monitoring and control of industrial yeast strains by molecular methods.

Spraguea lophii (Microsporidia) parasite of the teleost fish, Lophius piscatorius from Tunisian coasts: Evidence for an extensive chromosome length polymorphism

A microsporidian of the genus Spraguea was found parasitizing the nervous tissues of Lophius piscatorius collected from various localities in the Mediterranean coastal areas of Tunisia. The tissue localization, the infection focus aspect and sporal dimorphism are characteristics of Spraguea lophii species. Molecular data based on partial sequence of SSUrRNA encoding gene shows few nucleotide polymorphisms, compared to all described Spraguea isolates. Molecular karyotype obtained on pulsed field gel electrophoresis (1D-PFGE) shows a profile with 14 stained bands in the range of 230–880kbp and a genome size estimated to 6.700kbp. The rare cutter endonuclease MluI KARD 2-D-PFGE fingerprint shows an extensive chromosome length polymorphism, but the number of chromosome is unchanged and consists of 15 different molecules. The extensive chromosome length polymorphism is associated to a reduced number of genetic events.

Enrichment in methanol-containing broth — A simple method for the isolation ofSaccharomycesfrom grapes

In this study a simple and effective method was developed for the isolation of Saccharomyces strains from grapes. Aseptically collected grape samples were processed by enrichment in a nutritive basal medium supplemented with 10% (v/v) methanol followed by isolation of yeast strains. Sixteen of the 18 grape samples yielded Saccharomyces strain(s). More than 70% of the isolates belonged to the genus Saccharomyces. Based on phenotype and electrophoretic karyotyping, all strains of Saccharomyces were identified as S. cerevisiae. For several grape samples, varying physiological characters, the number of spores per asci, and the observed chromosome length polymorphisms provided evidence for diversity of S. cerevisiae strains obtained by this enrichment in methanol-containing broth. Results indicated that enrichment in methanol-containing broth is an effective alternative method to facilitate isolation of Saccharomyces strains from grapes. The enrichment method described in this work provides a simple and effective tool for isolation of Saccharomyces strains from grapes. The method may be applied in studying wine fermentation ecology, as well as for the isolation of potential starter strains from grapes.

Electrophoretic karyotypes of Rhynchosporium commune, R. secalis and R. agropyri

Pulsed-field gel electrophoresis was used to generate electrophoretic karyotypes for 15 strains representing the three closely related plant-pathogenic fungi Rhynchosporium commune, R. secalis and R. agropyri. Between 13 and 16 chromosomes ranging in size from 0.9 to 6.4 Mb were found among the strains, leading to estimated genome sizes ranging from 54 to 63 Mb. Southern hybridization was used to identify homologous chromosomes, allowing detection of chromosome-length polymorphisms. There were no obvious differences in genome sizes or structures among the three species. The avirulence gene NIP1 is present on a large chromosome that is not likely to be dispensable. Two strains of R. commune that were proposed in earlier studies to be aneuploid as a result of a parasexual cycle did not possess a larger number of chromosomes. The reported information on genome size and chromosome number will be useful for genome sequencing projects that aim to identify genes involved in speciation and host specialization.

Mitochondrial DNA polymorphism of the yeast Saccharomyces bayanus var. uvarum

Genetic relationships among forty-one strains of Saccharomyces bayanus var. uvarum isolated in different wine regions of Europe and four wild isolates were investigated by restriction analysis (RFLP) of mitochondrial DNA (mtDNA) with four restriction endonucleases, AluI, DdeI, HinfI and RsaI. No clear correlation between origin and source of isolation of S. bayanus var. uvarum strains and their mtDNA restriction profiles was found. On the whole, the mtDNA of S. bayanus var. uvarum is much less polymorphic than that of S. cerevisiae. This observation is in good agreement with results obtained by electrophoretic karyotyping. Unlike wine S cerevisiae, strains of S. bayanus var. uvarum display a low level of chromosome length polymorphism.

Dried Yeast: Impact of Dehydration and Rehydration on Brewing Yeast DNA Integrity

As a consequence of fluidized bed drying, yeast cells may be exposed to a series of physiological stresses, of which the most evident is water loss. Desiccation can lead to cell wall crenellation, cytoplasmic crowding, loss of DNA supercoiling, membrane disruption, phase transitions, and ultimately cell death. Although the dehydrated phenotype has been well characterized, the sequence of events that causes damage to the cell has not been widely reported. Here we investigate the impact of dehydration and rehydration on the stability of the brewing yeast genome, including both the chromosomal and mitochondrial DNA (mtDNA). Analysis of rehydrated and control yeast populations for chromosome length polymorphisms (karyotyping), DNA sequence changes (PCR analysis of interdelta sequences), gross mitochondrial damage (presence of respiratory deficient mutants), and mitochondrial sequence changes (mtDNA RFLP [restriction fragment length polymorphisms]) indicated that the genetic constitution of dried yeast is not affected by the drying process. Active dried yeast (ADY) populations also demonstrated an enhanced tolerance to mutagen challenge (targeted at mtDNA), suggesting that the susceptibility of mtDNA to change is not associated with fluidized bed drying. These results demonstrate that the genetic stability of ADY is comparable to control populations.

Genome variability of the yeast Yarrowia lipolytica

Using sequence analysis of internal transcribed spacers ITS1 and ITS2, RAPD-PCR, and pulsed-field gel electrophoresis of intact chromosomal DNA, we investigated the molecular and genetic peculiarities of the genomes of 40 Yarrowia lipolytica strains. All the strains showed nearly identical ITS-sequences. On the other hand, karyotypic analysis revealed significant differences in the chromosomal patterns of Y. lipolytica. The number and order of individual chromosomes vary from strain to strain. Chromosome-length polymorphism of the Y. lipopytica strains was pronounced and independent of their geographic origin and the source of isolation. Intraspecific polymorphism of Y. lipolytica chromosomes is discussed.

Serial Repitching of Dried Lager Yeast

To demonstrate the suitability of active dried yeast (ADY) for serial repitching, dried and wet yeast slurries derived from the same strain were analyzed for five consecutive fermentations (G0–G4). In each instance, cell viability was determined prior to pitching, while yeast performance was assessed by analyzing fermentation profiles and the characteristics of the final products. In addition, beers produced using wet and dried G0 and G4 yeast were analyzed and compared for their concentrations of esters and higher alcohols. Yeast obtained at the end of each fermentation was screened for the presence of respiratory-deficient mutants and flocculent variants. Yeast slurries recovered from G4 beer were examined for genetic changes, as characterized by movement of Ty elements and chromosome length polymorphisms. This study shows that serially repitched wet and dried yeasts perform in a similar fashion and that repitched cultures exhibit more typical fermentation and flavor profiles than fresh slurries. In addition, the study demonstrates that the accumulation of genetic and phenotypic variants is not associated with serial repitching of dried yeast cultures. Consequently, it is proposed that ADY can be reused in a similar fashion to wet yeast without any adverse effects on fermentation performance, yeast quality, or flavor production.

The Enigma of the Major Repeat Sequence of Candida Albicans

The major repeat sequence, discovered in the yeast Candida albicans, is a stretch of repeated DNA that occurs nine times in the haploid genome of this opportunistic fungal pathogen and probably a similar number of times in the genome of Candida dubliniensis. In C. albicans it constitutes 1-2% of the genome. Its occurrence is limited to those two species. Despite its major role as a genomic feature, its function, mode of expansion in size due to duplication of internal subunits, and its origin and mechanism of distribution throughout the genome are not understood, although it is associated with chromosome translocations, chromosome length polymorphisms and regulation of the yeast-hypha dimorphic transition. The polymorphism of the major repeat sequence has been exploited in epidemiology and taxonomic studies. This review describes its sequence, occurrence, use in epidemiology and examines the evidence for its role in chromosome dynamics.

Loss of heterozygosity in commensal isolates of the asexual diploid yeast Candida albicans

Candida albicans is a commensal and the most frequent fungal pathogen of humans. One mechanism of genetic variation in this diploid asexual yeast involves loss of heterozygosity (LOH). LOH events occur upon infection and contribute to the acquisition of antifungal resistance in patients. In contrast, little is known about the nature and extent of LOH events during commensalism. Using a combination of single nucleotide polymorphism typing, positional transcript profiling and karyotyping, we have characterized related C. albicans commensal isolates that differ by LOH events. Most of these LOH events encompassed the entirety of the chromosome or a large region extending to the telomere, suggesting chromosome loss or mitotic recombination/break-induced replication events, respectively. They were frequently accompanied by karyotype alterations such as chromosome length polymorphism and copy number variations at other chromosomes. These results demonstrate the high plasticity of the C. albicans genome during commensalism.

Karyotype determination and gene mapping in two clinical isolates ofPenicillium marneffei

Electrophoretic karyotypes from two clinical isolates of Penicillium marneffei were derived using contoured-clamped homogeneous electric field (CHEF) gel electrophoresis. Five chromosome-sized DNA fragments were resolved from each isolate. Chromosomal length polymorphisms were evident among the three largest molecules. Based upon these electrophoretic separation patterns, individual chromosomes were estimated to range in size from 2.0 to > or = 6.3 Mbp with a total genome size of 20.6 to > or = 21.6 Mbp. However, Southern blot analysis using a telomeric probe suggests that P. marneffei may possess as many as seven chromosomes, including two pairs of molecules that co-migrate under the CHEF separation conditions employed in this study. Hence, the total genome size of P. marneffei may be as large as 25.7 to > or = 26.7 Mbp. Further hybridization analysis mapped four chitin synthase homologues to specific chromosomes as well as genes for chitinase, malate synthase, isocitrate lyase, isocitrate dehydrogenase, 5.8S rRNA, and 23S rRNA. The mapping analyses also suggested the existence of multiple chitinase gene homologues in P. marneffei. The collective results of this investigation provide additional foundations for facilitating the genetic characterization of P. marneffei and the molecular epidemiology of penicilliosis due to this fungus.

Comparison of Saccharomyces cerevisiae strains of clinical and nonclinical origin by molecular typing and determination of putative virulence traits

Saccharomyces cerevisiae strains of clinical and nonclinical origin were compared by pulse field gel electrophoresis. Complete separation between strains of clinical origin and food strains by their chromosome length polymorphism was not obtained even though there was a tendency for the clinical and food strains to cluster separately. All the investigated strains, except for one food strain, were able to grow at temperatures ≥37 °C but not at 42 °C. Great strain variations were observed in pseudohyphal growth and invasiveness, but the characters were not linked to strains of clinical origin. The adhesion capacities of the yeast strains to a human intestinal epithelial cell line (Caco-2) in response to different nutritional availabilities were determined, as were the effects of the strains on the transepithelial electrical resistance (TER) across polarized monolayers of Caco-2 cells. The yeast strains displayed very low adhesion capacities to Caco-2 cells (0.6–6.2%), and no significant difference was observed between the strains of clinical and nonclinical origin. Both S. cerevisiae strains of clinical and non-clinical origin increased the TER of polarized monolayers of Caco-2 cells. Based on the results obtained in this study, no specific virulence factor was found that clearly separated the strains of clinical origin from the strains of nonclinical origin. On the contrary, all investigated strains of S. cerevisiae were found to strengthen the epithelial barrier function.