scholarly journals Phenotypic Switching in Candida glabrata Involves Phase-Specific Regulation of the Metallothionein Gene MT-IIand the Newly Discovered Hemolysin Gene HLP

2000 ◽  
Vol 68 (2) ◽  
pp. 884-895 ◽  
Author(s):  
Salil A. Lachke ◽  
Thyagarajan Srikantha ◽  
Luong K. Tsai ◽  
Karla Daniels ◽  
David R. Soll
Keyword(s):  
High Frequency ◽  
Candida Glabrata ◽  
Mutational Analysis ◽  
Transcript Level ◽  
Phenotypic Switching ◽  
Transcript Levels ◽  
Metallothionein Gene ◽  
Rapid Responses ◽  
Hemolysin Gene ◽  
Specific Regulation

ABSTRACT Although Candida glabrata has emerged in recent years as a major fungal pathogen, there have been no reports demonstrating that it undergoes either the bud-hypha transition or high-frequency phenotypic switching, two developmental programs believed to contribute to the pathogenic success of other Candida species. Here it is demonstrated that C. glabrata undergoes reversible, high-frequency phenotypic switching between a white (Wh), light brown (LB), and dark brown (DB) colony phenotype discriminated on an indicator agar containing 1 mM CuSO4. Switching regulates the transcript level of the MT-II metallothionein gene(s) and a newly discovered gene for a hemolysin-like protein,HLP. The relative MT-II transcript levels in Wh, LB, and DB cells grown in the presence of CuSO4 are 1:27:81, and the relative transcript levels of HLP are 1:20:35. The relative MT-II and HLP transcript levels in cells grown in the absence of CuSO4 are 1:20:30 and 1:20:25, respectively. In contrast, switching has little or no effect on the transcript levels of the genes MT-I,AMT-I, TRPI, HIS3,EPAI, and PDHI. Switching of C. glabrata is not associated with microevolutionary changes identified by the DNA fingerprinting probe Cg6 and does not involve tandem amplification of the MT-IIa gene, which has been shown to occur in response to elevated levels of copper. Finally, switching between Wh, LB, and DB occurred in all four clinical isolates examined in this study. As in Candida albicans, switching in C. glabrata may provide colonizing populations with phenotypic plasticity for rapid responses to the changing physiology of the host, antibiotic treatment, and the immune response, through the differential regulation of genes involved in pathogenesis. More importantly, because C. glabrata is haploid, a mutational analysis of switching is now feasible.

scholarly journals Three Mating Type-Like Loci in Candida glabrata

2003 ◽  
Vol 2 (2) ◽  
pp. 328-340 ◽  
Author(s):  
Thyagarajan Srikantha ◽  
Salil A. Lachke ◽  
David R. Soll
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mating Type ◽  
High Frequency ◽  
Promoter Region ◽  
Candida Glabrata ◽  
Phenotypic Switching ◽  
Northern Analysis ◽  
Coding Regions ◽  
Dna Strands ◽  
Different Strains

ABSTRACT Candida glabrata, the second most prevalent Candida species colonizing humans, possesses three mating type-like (MTL) loci (MTL1, MTL2, and MTL3). These loci contain pairs of MTL genes with their respective coding regions on complementary Crick and Watson DNA strands. Each pair of genes is separated by a shared intergenic promoter region, the same configuration found at the mating type loci of Saccharomyces cerevisiae. Two of the MTL loci, MTL1 and MTL2, contain either the MTLa1/MTLa2 configuration or the MTLα1/MTLα2 configuration in different strains. All but one of the 38 tested C. glabrata strains were either aaα or aαα. One test strain was ααα. Based on the mating type genotype, the MTL genes at the MTL1 or MTL2 loci, and the size of the XbaI fragment harboring MTL1 or MTL2, four classes of C. glabrata strains (I, II, III, and IV) were distinguished. Northern analysis revealed that strains were either a-expressors or α-expressors and that expression always reflected the genotype of either the MTL1 or MTL2 locus, depending on the class. The expression pattern in each class, therefore, is similar to that observed in S. cerevisiae, which harbors two silent cassette loci, HMR and HML, and the expression locus MAT. High-frequency phenotypic switching between core phenotypes in an α-expressing, but not in an a-expressing, strain modulated the level of MTL expression, suggesting a possible relationship between core phenotypic switching and mating.

scholarly journals Phenotypic Switching and Mating Type Switching ofCandida glabrata at Sites ofColonization

2003 ◽  
Vol 71 (12) ◽  
pp. 7109-7118 ◽  
Author(s):  
Paula J. Brockert ◽  
Salil A. Lachke ◽  
Thyagarajan Srikantha ◽  
Claude Pujol ◽  
Rudolph Galask ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mating Type ◽  
High Frequency ◽  
Candida Glabrata ◽  
Phenotypic Switching ◽  
Vaginal Infection ◽  
Vaginal Colonization ◽  
Type Classes ◽  
Mating Type Switching ◽  
Oral Colonization

ABSTRACT Candida glabrata switches spontaneously at high frequency among the following four graded phenotypes discriminated on agar containing 1 mM CuSO4: white, light brown, dark brown (DB), and very dark brown. C. glabrata also contains three mating type loci with a configuration similar to that of the Saccharomyces cerevisiae mating type cassette system, suggesting it may also undergo cassette switching at the expression locus MTL1. To analyze both reversible, high-frequency phenotypic switching and mating type switching at sites of colonization, primary samples from the oral cavities and vaginal canals of three patients suffering from C. glabrata vaginitis were clonally plated on agar containing CuSO4. It was demonstrated that (i) in each vaginitis patient, there was only one colonizing strain; (ii) an individual could have vaginal colonization without oral colonization; (iii) phenotypic switching occurred at sites of colonization; (iv) the DB phenotype predominated at the site of infection in all three patients; (v) genetically unrelated strains switched in similar, but not identical, fashions and caused vaginal infection; (vi) different switch phenotypes of the same strain could simultaneously dominate different body locations in the same host; (vii) pathogenesis could be caused by cells in different mating type classes; and (viii) mating type switching demonstrated at both the genetic and transcription levels occurred in one host.

scholarly journals Toward an Automatic Quality Assessment of Voice-Based Telemedicine Consultations: A Deep Learning Approach

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 3279
Author(s):  
Maria Habib ◽  
Mohammad Faris ◽  
Raneem Qaddoura ◽  
Manal Alomari ◽  
Alaa Alomari ◽  
...  
Keyword(s):  
Neural Networks ◽  
Deep Learning ◽  
Quality Assessment ◽  
Transcript Level ◽  
Assessment Process ◽  
Classification Model ◽  
Systematic Evaluation ◽  
Transcript Levels ◽  
Perceptual Evaluation

Maintaining a high quality of conversation between doctors and patients is essential in telehealth services, where efficient and competent communication is important to promote patient health. Assessing the quality of medical conversations is often handled based on a human auditory-perceptual evaluation. Typically, trained experts are needed for such tasks, as they follow systematic evaluation criteria. However, the daily rapid increase of consultations makes the evaluation process inefficient and impractical. This paper investigates the automation of the quality assessment process of patient–doctor voice-based conversations in a telehealth service using a deep-learning-based classification model. For this, the data consist of audio recordings obtained from Altibbi. Altibbi is a digital health platform that provides telemedicine and telehealth services in the Middle East and North Africa (MENA). The objective is to assist Altibbi’s operations team in the evaluation of the provided consultations in an automated manner. The proposed model is developed using three sets of features: features extracted from the signal level, the transcript level, and the signal and transcript levels. At the signal level, various statistical and spectral information is calculated to characterize the spectral envelope of the speech recordings. At the transcript level, a pre-trained embedding model is utilized to encompass the semantic and contextual features of the textual information. Additionally, the hybrid of the signal and transcript levels is explored and analyzed. The designed classification model relies on stacked layers of deep neural networks and convolutional neural networks. Evaluation results show that the model achieved a higher level of precision when compared with the manual evaluation approach followed by Altibbi’s operations team.

Overlapping positive and negative regulatory elements determine lens-specific activity of the delta 1-crystallin enhancer

1993 ◽  
Vol 13 (9) ◽  
pp. 5206-5215 ◽  
Author(s):  
Y Kamachi ◽  
H Kondoh
Keyword(s):  
Mutational Analysis ◽  
Specific Activity ◽  
Regulatory Elements ◽  
Positive Element ◽  
Specific Expression ◽  
Enhancer Activity ◽  
Negative Element ◽  
Positive Elements ◽  
Lens Cells ◽  
Specific Regulation

Lens-specific expression of the delta 1-crystallin gene is governed by an enhancer in the third intron, and the 30-bp-long DC5 fragment was found to be responsible for eliciting the lens-specific activity. Mutational analysis of the DC5 fragment identified two contiguous, interdependent positive elements and a negative element which overlaps the 3'-located positive element. Previously identified ubiquitous factors delta EF1 bound to the negative element and repressed the enhancer activity in nonlens cells. Mutation and cotransfection analyses indicated the existence of an activator which counteracts the action of delta EF1 in lens cells, probably through binding site competition. We also found a group of nuclear factors, collectively called delta EF2, which bound to the 5'-located positive element. delta EF2a and -b were the major species in lens cells, whereas delta EF2c and -d predominated in nonlens cells. These delta EF2 proteins probably cooperate with factors bound to the 3'-located element in activation in lens cells and repression in nonlens cells. delta EF2 proteins also bound to a promoter sequence of the gamma F-crystallin gene, suggesting that delta EF2 proteins are involved in lens-specific regulation of various crystallin classes.

scholarly journals Regulation of Major Cellulosomal Endoglucanases of Clostridium thermocellum Differs from That of a Prominent Cellulosomal Xylanase

2005 ◽  
Vol 187 (7) ◽  
pp. 2261-2266 ◽  
Author(s):  
Tali W. Dror ◽  
Adi Rolider ◽  
Edward A. Bayer ◽  
Raphael Lamed ◽  
Yuval Shoham
Keyword(s):  
Growth Rate ◽  
Clostridium Thermocellum ◽  
Transcript Level ◽  
Clear Correlation ◽  
Transcript Levels ◽  
Batch Cultures ◽  
Processive Endoglucanase ◽  
The Family ◽  
Genes Encoding ◽  
Family 10 Xylanase

ABSTRACT The expression of scaffoldin-anchoring genes and one of the major processive endoglucanases (CelS) from the cellulosome of Clostridium thermocellum has been shown to be dependent on the growth rate. For the present work, we studied the gene regulation of selected cellulosomal endoglucanases and a major xylanase in order to examine the previously observed substrate-linked alterations in cellulosome composition. For this purpose, the transcript levels of genes encoding endoglucanases CelB, CelG, and CelD and the family 10 xylanase XynC were determined in batch cultures, grown on either cellobiose or cellulose, and in carbon-limited continuous cultures at different dilution rates. Under all conditions tested, the transcript levels of celB and celG were at least 10-fold higher than that of celD. Like the major processive endoglucanase CelS, the transcript levels of these endoglucanase genes were also dependent on the growth rate. Thus, at a rate of 0.04 h−1, the levels of celB, celG, and celD were threefold higher than those obtained in cultures grown at maximal rates (0.35 h−1) on cellobiose. In contrast, no clear correlation was observed between the transcript level of xynC and the growth rate—the levels remained relatively high, fluctuating between 30 and 50 transcripts per cell. The results suggest that the regulation of C. thermocellum endoglucanases is similar to that of the processive endoglucanase celS but differs from that of a major cellulosomal xylanase in that expression of the latter enzyme is independent of the growth rate.

scholarly journals Proteolytic and Structural Changes in Rye and Triticale Roots under Aluminum Stress

Cells ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 3046
Author(s):  
Joanna Szewińska ◽  
Elżbieta Różańska ◽  
Ewa Papierowska ◽  
Mateusz Labudda
Keyword(s):  
Heavy Metals ◽  
Structural Changes ◽  
Transcript Level ◽  
Fine Tuning ◽  
Gelatinolytic Activity ◽  
Border Cells ◽  
Aluminum Stress ◽  
Transcript Levels ◽  
Root Border Cells ◽  
Level Analysis

Proteolysis and structural adjustments are significant for defense against heavy metals. The purpose of this study was to evaluate whether the Al3+ stress alters protease activity and the anatomy of cereale roots. Azocaseinolytic and gelatinolytic measurements, transcript-level analysis of phytocystatins, and observations under microscopes were performed on the roots of Al3+-tolerant rye and tolerant and sensitive triticales exposed to Al3+. In rye and triticales, the azocaseinolytic activity was higher in treated roots. The gelatinolytic activity in the roots of rye was enhanced between 12 and 24 h in treated roots, and decreased at 48 h. The gelatinolytic activity in treated roots of tolerant triticale was the highest at 24 h and the lowest at 12 h, whereas in treated roots of sensitive triticale it was lowest at 12 h but was enhanced at 24 and 48 h. These changes were accompanied by increased transcript levels of phytocystatins in rye and triticale-treated roots. Light microscope analysis of rye roots revealed disintegration of rhizodermis in treated roots at 48 h and indicated the involvement of root border cells in rye defense against Al3+. The ultrastructural analysis showed vacuoles containing electron-dense precipitates. We postulate that proteolytic-antiproteolytic balance and structural acclimation reinforce the fine-tuning to Al3+.

scholarly journals Role of ATP-Binding-Cassette Transporter Genes in High-Frequency Acquisition of Resistance to Azole Antifungals in Candida glabrata

2001 ◽  
Vol 45 (4) ◽  
pp. 1174-1183 ◽  
Author(s):  
Dominique Sanglard ◽  
Francoise Ischer ◽  
Jacques Bille
Keyword(s):  
Abc Transporter ◽  
High Frequency ◽  
Candida Glabrata ◽  
Antifungal Agents ◽  
Clinical Isolates ◽  
Azole Resistance ◽  
Atp Binding ◽  
Transporter Gene ◽  
Atp Binding Cassette

ABSTRACT Candida glabrata has been often isolated from AIDS patients with oropharyngeal candidiasis treated with azole antifungal agents, especially fluconazole. We recently showed that the ATP-binding-cassette (ABC) transporter gene CgCDR1 was upregulated in C. glabrata clinical isolates resistant to azole antifungal agents (D. Sanglard, F. Ischer, D. Calabrese, P. A. Majcherczyk, and J. Bille, Antimicrob. Agents Chemother. 43:2753–2765, 1999). Deletion of CgCDR1 in C. glabrata rendered the null mutant hypersusceptible to azole derivatives and showed the importance of this gene in mediating azole resistance. We observed that wild-type C. glabrata exposed to fluconazole in a medium containing the drug at 50 μg/ml developed resistance to this agent and other azoles at a surprisingly high frequency (2 × 10−4 to 4 × 10−4). We show here that this high-frequency azole resistance (HFAR) acquired in vitro was due, at least in part, to the upregulation ofCgCDR1. The CgCDR1 deletion mutant DSY1041 could still develop HFAR but in a medium containing fluconazole at 5 μg/ml. In the HFAR strain derived from DSY1041, a distinct ABC transporter gene similar to CgCDR1, calledCgCDR2, was upregulated. This gene was slightly expressed in clinical isolates but was upregulated in strains with the HFAR phenotype. Deletion of both CgCDR1 and CgCDR2suppressed the development of HFAR in a medium containing fluconazole at 5 μg/ml, showing that both genes are important mediators of resistance to azole derivatives in C. glabrata. We also show here that the HFAR phenomenon was linked to the loss of mitochondria in C. glabrata. Mitochondrial loss could be obtained by treatment with ethidium bromide and resulted in acquisition of resistance to azole derivatives without previous exposure to these agents. Azole resistance obtained in vitro by HFAR or by agents stimulating mitochondrial loss was at least linked to the upregulation of both CgCDR1 and CgCDR2.

scholarly journals Nitrogen Supply and Leaf Age Affect the Expression of TaGS1 or TaGS2 Driven by a Constitutive Promoter in Transgenic Tobacco

Genes ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 406 ◽  
Author(s):  
Yihao Wei ◽  
Aibo Shi ◽  
Xiting Jia ◽  
Zhiyong Zhang ◽  
Xinming Ma ◽  
...  
Keyword(s):  
Amino Acid ◽  
Nitrogen Metabolism ◽  
Soluble Protein ◽  
Leaf Age ◽  
Sufficient Conditions ◽  
Transcript Level ◽  
Nitrogen Supply ◽  
High Accumulation ◽  
Transcript Levels ◽  
Chlorophyll Contents

Glutamine synthetase (GS) plays a key role in nitrogen metabolism. Here, two types of tobacco transformants, overexpressing Triticum aestivum GS1 (TaGS1) or GS2 (TaGS2), were analysed. Four independent transformed lines, GS1-TR1, GS1-TR2, GS2-TR1 and GS2-TR2, were used for the nitrogen treatment. Under nitrogen-sufficient conditions, the leaves of GS2-TR showed high accumulation of the TaGS2 transcript, while those of GS1-TR showed a low TaGS1 transcript levels. However, compared with nitrogen-sufficient conditions, the TaGS1 transcript level increased in the leaves under nitrogen starvation, but the TaGS2 transcript level decreased. In addition, the TaGS1 and TaGS2 transcript levels were highest in the middle leaves under nitrogen-sufficient and starvation conditions. These results show that nitrogen supply and leaf age regulate TaGS expression, even when they are driven by a super-promoter. Additionally, in regard to nitrogen metabolism level, the lower leaves of the GS1-TR exhibited lower NH4+ and higher amino acid contents, while the upper leaves exhibited higher amino acid, soluble protein and chlorophyll contents. The leaves of the GS2-TR exhibited lower NH4+ but higher amino acid, soluble protein and chlorophyll contents. Given the role that GS isoforms play in nitrogen metabolism, these data suggest that TaGS1 overexpression may improve nitrogen transport, and that TaGS2 overexpression may improve nitrogen assimilation under nitrogen stress.

The vsp Locus of Mycoplasma bovis: Gene Organization and Structural Features

1999 ◽  
Vol 181 (18) ◽  
pp. 5734-5741 ◽  
Author(s):  
Inessa Lysnyansky ◽  
Konrad Sachse ◽  
Ricardo Rosenbusch ◽  
Sharon Levisohn ◽  
David Yogev
Keyword(s):  
High Frequency ◽  
Sequence Similarity ◽  
Membrane Surface ◽  
Amino Acid Sequences ◽  
High Rate ◽  
Phenotypic Switching ◽  
Upstream Region ◽  
Mycoplasma Bovis ◽  
High Sequence Similarity ◽  
Polypeptide Structure

ABSTRACT Major lipoprotein antigens, known as variable membrane surface lipoproteins (Vsps), on the surface of the bovine pathogenMycoplasma bovis were shown to spontaneously undergo noncoordinate phase variation between ON and OFF expression states. The high rate of Vsp phenotypic switching was also shown to be linked with DNA rearrangements that occur at high frequency in the M. bovis chromosome (I. Lysnyansky, R. Rosengarten, and D. Yogev, J. Bacteriol. 178:5395–5401, 1996). In the present study, 13 single-copyvsp genes organized in a chromosomal cluster were identified and characterized. All vsp genes encode highly conserved N-terminal domains for membrane insertion and lipoprotein processing but divergent mature Vsp proteins. About 80% of eachvsp coding region is composed of reiterated coding sequences that create a periodic polypeptide structure. Eighteen distinct repetitive domains of different lengths and amino acid sequences are distributed within the products of the variousvsp genes that are subject to size variation due to spontaneous insertions or deletions of these periodic units. Some of these repeats were found to be present in only one Vsp family member, whereas other repeats recurred at variable locations in several Vsps. Each vsp gene is also 5′ linked to a highly homologous upstream region composed of two internal cassettes. The findings that rearrangement events are associated with Vsp phenotypic switching and that multiple regions of high sequence similarity are present upstream of the vsp genes and within the vsp coding regions suggest that modulation of the Vsp antigenic repertoire is determined by recombination processes that occur at a high frequency within the vsp locus of M. bovis.

Sign in / Sign up

Export Citation Format

Share Document