scholarly journals Genetic screen for suppressors of increased silencing in rpd3 mutants in Saccharomyces cerevisiae identifies a potential role for H3K4 methylation

2021 ◽  
Author(s):  
Richard A Kleinschmidt ◽  
Laurie M Lyon ◽  
Samantha L Smith ◽  
Jonah Rittenberry ◽  
K Maeve Lawless ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Potential Role ◽  
Rna Polymerase Iii ◽  
Genetic Screen ◽  
Gene Repression ◽  
Initial Assessment ◽  
H3k4 Methylation ◽  
Enzyme Functions ◽  
Rule Out

Abstract Several studies have identified the paradoxical phenotype of increased heterochromatic gene silencing at specific loci that results from deletion or mutation of the histone deacetylase (HDAC) gene RPD3. To further understand this phenomenon, we conducted a genetic screen for suppressors of this extended silencing phenotype at the HMR locus in Saccharomyces cerevisiae. Most of the mutations that suppressed extended HMR-silencing in rpd3 mutants without completely abolishing silencing were identified in the histone H3 lysine 4 methylation (H3K4me) pathway, specifically in SET1, BRE1 and BRE2. These second site mutations retained normal HMR silencing, therefore appear to be specific for the rpd3Δ extended silencing phenotype. As an initial assessment of the role of H3K4 methylation in extended silencing, we rule out some of the known mechanisms of Set1p/H3K4me mediated gene repression by HST1, HOS2 and HST3 encoded HDACs. Interestingly, we demonstrate that the RNA Polymerase III complex remains bound and active at the HMR-tDNA in rpd3 mutants despite silencing extending beyond the normal barrier. We discuss these results as they relate to the interplay among different chromatin modifying enzyme functions and the importance of further study of this enigmatic phenomenon.

scholarly journals A Study on the Potential Role of Occlusal Fissure Fractures in the Etiopathogenesis of Equine Cheek Teeth Apical Infections

2019 ◽  
Vol 36 (3) ◽  
pp. 171-178 ◽  
Author(s):  
Katherina Y. Wellman ◽  
Padraic M. Dixon
Keyword(s):  
Computed Tomography ◽  
Methylene Blue ◽  
Potential Role ◽  
Histological Study ◽  
Extraction Process ◽  
Dental Tissue ◽  
Rule Out

Thirty-nine equine cheek teeth diagnosed as having anachoretic apical infections and also having occlusal fissure fractures, but without occlusal pulpar exposure, that had been orally extracted without causing occlusal damage and 10 control teeth were used in this study. The teeth were individually imaged by computed tomography, occlusally stained with methylene blue and visually reexamined, then sectioned subocclusally at 5 mm intervals until the fissure fractures could no longer be detected. A limited histological study was then performed on 7 apically infected and 5 control teeth. Standard computed tomography only detected 1 of 39 fissure fractures. Thirteen of the 39 stained teeth had subocclusal fissure fractures visually identified at approximately 6 mm beneath the surface, and in 9 of these 13 teeth the fissure fractures had deeper staining to a level immediately above or into a pulp horn, indicating a potential route for bacterial pulpitis. However, the current study cannot rule out the possibility that the extraction process, long-term formalin storage, or the processing of teeth may have allowed for deeper staining. Additionally, methylene blue may penetrate dental tissue more readily than bacteria can invade. Further studies on the potential role of fissure fractures in the etiopathogenesis of cheek teeth apical infection are warranted.

Biomilling of rod-shaped ZnO nanoparticles: a potential role of Saccharomyces cerevisiae extracellular proteins

RSC Advances ◽  
2015 ◽  
Vol 5 (3) ◽  
pp. 1883-1889 ◽  
Author(s):  
Chandrashekhar Sharan ◽  
Puneet Khandelwal ◽  
Pankaj Poddar
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Zno Nanoparticles ◽  
Potential Role ◽  
Zno Nanorods ◽  
Extracellular Proteins ◽  
Zno Nps

Break-down of chemically synthesized ZnO nanorods into small quasi-spherical ZnO NPs possibly due to the proteins secreted by Saccharomyces cerevisiae.

scholarly journals Distinct requirements for the COMPASS core subunits Set1, Swd1, and Swd3 during meiosis in the budding yeast Saccharomyces cerevisiae

2021 ◽  
Author(s):  
Brandon M Trainor ◽  
Kerri Ciccaglione ◽  
Miranda Czymek ◽  
Michael J Law
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Segregation ◽  
Chromatin Conformation ◽  
H3k4 Methylation ◽  
Yeast Saccharomyces Cerevisiae ◽  
The Core ◽  
Methylation Mark ◽  
Histone H3k4 ◽  
Transcription Program

Abstract Meiosis-specific chromatin structures, guided by histone modifications, are critical mediators of a meiotic transient transcription program and progression through prophase I. Histone H3K4 can be methylated up to three times by the Set1-containing COMPASS complex and each methylation mark corresponds to a different chromatin conformation. The level of H3K4 modification is directed by the activity of additional COMPASS components. In this study, we characterized the role of the COMPASS subunits during meiosis in S. cerevisiae. In vegetative cells, previous studies revealed a role for subunits Swd2, Sdc1, and Bre2 for H3K4me2 while Spp1 supported trimethylation. However, we found that Bre2 and Sdc1 are required for H3K4me3 as yeast prepare to enter meiosis while Spp1 is not. Interestingly, we identified distinct meiotic functions for the core COMPASS complex members that required for all H3K4me, Set1, Swd1, and Swd3. While Set1 and Swd1 are required for progression through early meiosis, Swd3 is critical for late meiosis and spore morphogenesis. Furthermore, the meiotic requirement for Set1 is independent of H3K4 methylation, suggesting the presence of non-histone substrates. Finally, checkpoint suppression analyses indicate that Set1 and Swd1 are required for both homologous recombination and chromosome segregation. These data suggest that COMPASS has important new roles for meiosis that are independent of its well-characterized functions during mitotic divisions.

scholarly journals Tryptophan Derivatives by Saccharomyces cerevisiae EC1118: Evaluation, Optimization, and Production in a Soybean-Based Medium

2021 ◽  
Vol 22 (1) ◽  
pp. 472
Author(s):  
Michele Dei Cas ◽  
Ileana Vigentini ◽  
Sara Vitalini ◽  
Antonella Laganaro ◽  
Marcello Iriti ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Kynurenic Acid ◽  
Potential Role ◽  
Defined Medium ◽  
The Other ◽  
Chemically Defined Medium ◽  
Cultural Medium ◽  
Whole Cell Biotransformation ◽  
Tryptophan Derivatives

Given the pharmacological properti es and the potential role of kynurenic acid (KYNA) in human physiology and the pleiotropic activity of the neurohormone melatonin (MEL) involved in physiological and immunological functions and as regulator of antioxidant enzymes, this study aimed at evaluating the capability of Saccharomyces cerevisiae EC1118 to release tryptophan derivatives (dTRPs) from the kynurenine (KYN) and melatonin pathways. The setting up of the spectroscopic and chromatographic conditions for the quantification of the dTRPs in LC-MS/MS system, the optimization of dTRPs’ production in fermentative and whole-cell biotransformation approaches and the production of dTRPs in a soybean-based cultural medium naturally enriched in tryptophan, as a case of study, were included in the experimental plan. Variable amounts of dTRPs, with a prevalence of metabolites of the KYN pathway, were detected. The LC-MS/MS analysis showed that the compound synthesized at highest concentration is KYNA that reached 9.146 ± 0.585 mg/L in fermentation trials in a chemically defined medium at 400 mg/L TRP. Further experiments in a soybean-based medium confirm KYNA as the main dTRPs, whereas the other dTRPs reached very lower concentrations. While detectable quantities of melatonin were never observed, two MEL isomers were successfully measured in laboratory media.

scholarly journals Identification of High-Copy Disruptors of Telomeric Silencing in Saccharomyces cerevisiae

Genetics ◽  
1998 ◽  
Vol 150 (2) ◽  
pp. 613-632 ◽  
Author(s):  
Miriam S Singer ◽  
Alon Kahana ◽  
Alexander J Wolf ◽  
Lia L Meisinger ◽  
Suzanne E Peterson ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Molecular Basis ◽  
Dna Helicase ◽  
Genetic Screen ◽  
Gene Repression ◽  
Silent Chromatin ◽  
Repressive Chromatin ◽  
Telomeric Silencing ◽  
Genes Encoding ◽  
Processing Protease

Abstract The ends of chromosomes in Saccharomyces cerevisiae initiate a repressive chromatin structure that spreads internally and inhibits the transcription of nearby genes, a phenomenon termed telomeric silencing. To investigate the molecular basis of this process, we carried out a genetic screen to identify genes whose overexpression disrupts telomeric silencing. We thus isolated 10 DOT genes (disruptor of telomeric silencing). Among these were genes encoding chromatin component Sir4p, DNA helicase Dna2p, ribosomal protein L32, and two proteins of unknown function, Asf1p and Ifh1p. The collection also included genes that had not previously been identified: DOT1, DOT4, DOT5, DOT6, and TLC1, which encodes the RNA template component of telomerase. With the exception of TLC1, all these genes, particularly DOT1 and DOT4, also reduced silencing at other repressed loci (HM loci and rDNA) when overexpressed. Moreover, deletion of the latter two genes weakened silencing as well, suggesting that DOT1 and DOT4 normally play important roles in gene repression. DOT1 deletion also affected telomere tract length. The function of Dot1p is not known. The sequence of Dot4p suggests that it is a ubiquitin-processing protease. Taken together, the DOT genes include both components and regulators of silent chromatin.

POPDC proteins and cardiac function

2019 ◽  
Vol 47 (5) ◽  
pp. 1393-1404 ◽  
Author(s):  
Thomas Brand
Keyword(s):  
Potential Role ◽  
Striated Muscle ◽  
Short Review ◽  
Effector Proteins ◽  
Muscle Disease ◽  
Disease Genes ◽  
Protein Protein Interaction ◽  
Interaction Partners ◽  
And Function

Abstract The Popeye domain-containing gene family encodes a novel class of cAMP effector proteins in striated muscle tissue. In this short review, we first introduce the protein family and discuss their structure and function with an emphasis on their role in cyclic AMP signalling. Another focus of this review is the recently discovered role of POPDC genes as striated muscle disease genes, which have been associated with cardiac arrhythmia and muscular dystrophy. The pathological phenotypes observed in patients will be compared with phenotypes present in null and knockin mutations in zebrafish and mouse. A number of protein–protein interaction partners have been discovered and the potential role of POPDC proteins to control the subcellular localization and function of these interacting proteins will be discussed. Finally, we outline several areas, where research is urgently needed.

The Effect of Path Length and Display Size on Memory for Spatial Information

2012 ◽  
Vol 59 (3) ◽  
pp. 147-152 ◽  
Author(s):  
Katherine Guérard ◽  
Sébastien Tremblay
Keyword(s):  
Path Length ◽  
Potential Role ◽  
Spatial Information ◽  
Recall Performance ◽  
Minor Role ◽  
Length Effect ◽  
Serial Memory ◽  
Fixed Reference ◽  
A Minor

In serial memory for spatial information, some studies showed that recall performance suffers when the distance between successive locations increases relatively to the size of the display in which they are presented (the path length effect; e.g., Parmentier et al., 2005) but not when distance is increased by enlarging the size of the display (e.g., Smyth & Scholey, 1994). In the present study, we examined the effect of varying the absolute and relative distance between to-be-remembered items on memory for spatial information. We manipulated path length using small (15″) and large (64″) screens within the same design. In two experiments, we showed that distance was disruptive mainly when it is varied relatively to a fixed reference frame, though increasing the size of the display also had a small deleterious effect on recall. The insertion of a retention interval did not influence these effects, suggesting that rehearsal plays a minor role in mediating the effects of distance on serial spatial memory. We discuss the potential role of perceptual organization in light of the pattern of results.

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