94 research outputs found
Loss of Smi1, a protein involved in cell wall synthesis, extends replicative life span by enhancing rDNA stability in Saccharomyces cerevisiae
In Saccharomyces cerevisiae, replicative life span (RLS) is primarily affected by the stability of ribosomal DNA (rDNA). The stability of the highly repetitive rDNA array is maintained through transcriptional silencing by the NAD+-dependent histone deacetylase Sir2. Recently, the loss of Smi1, a protein of unknown molecular function that has been proposed to be involved in cell wall synthesis, has been demonstrated to extend RLS in S. cerevisiae, but the mechanism by which Smi1 regulates RLS has not been elucidated. In this study, we determined that the loss of Smi1 extends RLS in a Sir2-dependent manner. We observed that the smi1Δ mutation enhances transcriptional silencing at the rDNA locus and promotes rDNA stability. In the absence of Smi1, the stress-responsive transcription factor Msn2 translocates from the cytoplasm to the nucleus, and nuclear-accumulated Msn2 stimulates the expression of nicotinamidase Pnc1, which serves as an activator of Sir2. In addition, we observed that the MAP kinase Hog1 is activated in smi1Δ cells and that the activation of Hog1 induces the translocation of Msn2 into the nucleus. Taken together, our findings suggest that the loss of Smi1 leads to the nuclear accumulation of Msn2 and stimulates the expression of Pnc1, thereby enhancing Sir2-mediated rDNA stability and extending RLS in S. cerevisiae.Y
Distortion-Free Stretchable Light-Emitting Diodes via Imperceptible Microwrinkles
Stretchable organic light-emitting diodes (OLEDs) have been considered as a promising technology for next-generation free-form and wearable displays. However, an approach to ensure both high device performance and high resolution has not yet been suggested. While introducing a wrinkled structure in the active pixel areas is a decent method, the formation of out-of-plane macroscopic wrinkles having a wavelength of a few hundred mu m has caused distortion in the shape of the pixel, which is a critical drawback for a matrix-configured display demanding a sharp pixel definition. Herein, microwrinkled OLEDs are fabricated to define a distortion-free pixel by direct deposition of OLEDs on biaxially prestretched elastomeric substrate, being feasible by a low-temperature-based solution process. The total thickness of the device can be significantly reduced up to 350 nm, producing the imperceptible microwrinkles having a wavelength under 20 mu m. The microwrinkled OLEDs show a luminance over 8000 cd m(-2) and maximum current efficiency of 7.76 cd A(-1), which is comparable to the device without wrinkled structure. Finally, a stretchable 4 x 4 OLED pixel array with a microwrinkled structure is demonstrated showing sharply defined square-patterned emission, proving the potential in the future high-resolution stretchable display.N
Studies on the Anti-Oxidative Function of trans-Cinnamaldehyde-Included β-Cyclodextrin Complex
trans-Cinnamaldehyde (tCIN), an active compound found in cinnamon, is well known for its antioxidant, anticancer, and anti-inflammatory activities. The β-cyclodextrin (β-CD) oligomer has been used for a variety of applications in nanotechnology, including pharmaceutical and cosmetic applications. Here, we aimed to evaluate the anti-inflammatory and antioxidant effects of tCIN self-included in β-CD complexes (CIs) in lipopolysaccharide (LPS)-treated murine RAW 264.7 macrophages. RAW 264.7 macrophages were treated with increasing concentrations of β-CD, tCIN, or CIs for different times. β-CD alone did not affect the production of nitric oxide (NO) or reactive oxygen species (ROS). However, both tCIN and CI significantly reduced NO and ROS production. Thus, CIs may have strong anti-inflammatory and antioxidant effects, similar to those of tCIN when used alone
A live RSV vaccine with engineered thermostability is immunogenic in cotton rats despite high attenuation
Respiratory syncytial virus (RSV) is a leading cause of infant hospitalization and there remains no pediatric vaccine. RSV live-attenuated vaccines (LAVs) have a history of safe testing in infants; however, achieving an effective balance of attenuation and immunogenicity has proven challenging. Here we seek to engineer an RSV LAV with enhanced immunogenicity. Genetic mapping identifies strain line 19 fusion (F) protein residues that correlate with pre-fusion antigen maintenance by ELISA and thermal stability of infectivity in live RSV. We generate a LAV candidate named OE4 which expresses line 19F and is attenuated by codon-deoptimization of non-structural (NS1 and NS2) genes, deletion of the small hydrophobic (SH) gene, codon-deoptimization of the attachment (G) gene and ablation of the secreted form of G. OE4 (RSV-A2-dNS1-dNS2-ΔSH-dGm-Gsnull-line19F) exhibits elevated pre-fusion antigen levels, thermal stability, immunogenicity, and efficacy despite heavy attenuation in the upper and lower airways of cotton rats
Neural correlates of beat and metre perception: the role of the inferior frontal gyrus
Temporal regularity and metrical organisation are important factors in beat and metre
perception. The current thesis aims to investigate neural correlates of beat and metre
perception in healthy non-musician volunteers, using functional magnetic resonance
imaging (fMRI). In particular, the thesis focuses on determining the role of the Inferior
Frontal Gyrus (IFG, in particular BA44/45) in beat and metre perception. The IFG has
been proposed to be involved in higher order cognitive processes during various
temporal sequencing, such as speech, movement, and music. Previous studies have
shown that the temporal processing of rhythm activates auditory and sensorimotor areas,
but the role of the IFG in rhythm perception has not yet been fully understood.
Study 1 investigated beat perception in complex rhythms, in which the addition
of volume accents either enhanced or weakened the beat perception, resulting in
Unaccented, Beat Accented or Non-Beat Accented rhythms. Participants (N=14; 6
males) listened to rhythm pairs across all three conditions, and judged whether each
rhythm pair was the same or different. Results showed that left IFG activation (BA44)
was significantly greater during the Non-Beat Accented condition compared to Beat
Accented condition, whereas the right IFG activation showed no significant difference
between the two conditions. Study 2 investigated metre perception of a series of
isochronous sequences, of which metrical organisation was grouped by 2/4 (C2), 3/4
(C3), or 4/4 (C4) using pitch accents, or remained without metrical grouping (or 1/4,
C1). The same participants (N=15; 6 males) listened to the stimuli and indicated the
perceived metrical grouping level. Results showed that the activation of bilateral IFG
parametrically increased from C2 to C3 to C4. Interestingly, the activation was found to
be significantly greater in C1 relative to C2, suggesting that involuntary subjective in C1
may increase the brain response.
Converging results from both Study 1 and Study 2 demonstrated, firstly, that the
bilateral IFG is involved in rhythm perception in addition to the auditory and
sensorimotor areas, including primary and secondary auditory areas, supplementary
motor areas, premotor areas, insula, and basal ganglia. Secondly, the left IFG (BA44) in
particular was significantly modulated by the rhythmic complexity relating to both
temporal regularity and metrical organisation, while showing the suppression during the
Beat Accented rhythm condition of Study 1 and the binary pattern (C2) of Study 2. This
thesis argues that the left IFG (BA44) may have the role the higher order cognitive
processing, such as attention and prediction, in the perception of hierarchical structures
in metric rhythms
Recommended from our members
Transit proximity and trip-making characteristics : a study of 2007 Chicago metropolitan region travel tracking survey
textInfluence of built environment on travel behavior has been recognized by several studies
in last decade (Cervero 2003, 2004, Ewing at al 2003 and etc.). Easy access to the transit
station and mixed land use has been largely emphasized by New Urbanist because of its
influence on transit ridership and reduction of vehicle mile travel. However, empirical
evidence that proximity of residential location to the transit station or mixed land use
reduces auto dependency and encourages transit ridership has been lack for Chicago
metropolitan region in spite of its long history of transit development.
This study uses 2007 Chicago metropolitan region travel tracking study data and travel
characteristics of residents living within walkable distance from the CAT or METRA rail
station in Chicago Metropolitan region was analyzed in comparison with those of
residents living beyond walkable distance from the rail station in order to find any
difference in socio-demographic characteristics and travel characteristics.
In general, households located within walkable distance (a quarter mile for this study)
from the rail station are more likely to be low income households, to reside in a multifamily
rental housing. Residents living within walkable distance show higher portion of
African American or Asian proportion, of smaller-sized households (a single member
household or childless household). They are likely to own fewer cars than residents living far from the rail station. With this observation of some difference in sociodemographic
and travel characteristics between two groups, probability of transit use
and rail use in a relationship with home location and job location were tested using
binary logistic model. The result indicates that the number of household vehicles per
person in the household influences negatively on residential location. The more
available household cars per person, the less likely it is that a household is located
within walkable distance from the rail station. Work location was also an important
factor for transit or rail use. This provides evidence that providing mixed land use
where jobs and housing are all provided within walkable distance from the transit
station can increase transit use and reduces auto-dependency that current American
society is facing severely.Community and Regional Plannin
Estimating the quadratic covariation matrix for asynchronously observed high frequency stock returns corrupted by additive measurement error
This paper studies the estimation problem of the covariance matrices of asset returns in the presence of microstructure noise and asynchronicity between the observations across different assets. Motivated by Malliavin and Mancino (2002, 2009) we propose a new Fourier domain based estimator of multivariate ex-post volatility, which we call the Fourier Realized Kernel (FRK). An advantage of this approach is that no explicit time alignment is required unlike the time domain based methods widely adopted in the existing literature. We derive the large sample properties and establish asymptotic normality of our estimator under some general conditions that allow for both temporal and cross-sectional correlations in the measurement error process. Our results can be viewed as Frequency domain extension of the asymptotic theories for the multivariate realized kernel estimator of Barndorff-Nielsen et al. (2011). We show in extensive simulations that our method outperforms the time domain estimators when two assets with different liquidity are traded asynchronously
Nanocrystalline H-RTH Zeolite: An Efficient Catalyst for the Low-Temperature Dehydration of Ethanol to Ethene
The low-temperature dehydration of bioethanol is an environmentally benign route to ethene production. Here we compare the catalytic properties of a series of cage-based small-pore zeolites with different framework structures, acid strengths, and/or crystallite sizes for ethanol dehydration at 200 degrees C under wet conditions (H2O/EtOH=0.2). Among the zeolites studied here, nanocrystalline H-RTH was found to be considerably more effective than H-mordenite, the best catalyst for this reaction known to date, which can be rationalized by product shape selectivity. Whereas the acidity of this zeolite also plays a crucial role in selectively forming ethene, its nanocrystallinity is primarily responsible for the observed high catalyst durability.11Nsciescopu
- …