Regulation of Brucella abortus catalase as a defensive mechanism against oxidative stress

Free radicals in the nature are harmful to organisms because they cause damage to tissues, cell membranes, proteins, and DNA. The animal immune system (cell mediated immune response) uses oxygen molecules to kill foreign organisms. B. abortus causes a cattle disease called brucellosis. The mechanism for bacteria to survive and adapt in the face of oxidative attack is thought to be important for understanding pathogenesis. This dissertation presents the response of B. abortus to oxidative stress and the regulation of catalase as a defensive mechanism;Different protein expression patterns were observed during oxidative stress by conducting 2-D protein gel analysis. DnaK (Hsp70) and GroEL (Hsp60) were not dramatically changed in the protein expression level, whereas, Cu-Zn SOD and catalase were upregulated in response to oxidative stress. Catalase is known as the critical enzyme for removal of hydrogen peroxide and the protection of cells from oxidative damage. I show that catalase is increased both in protein expression and in RNA transcription in the presence of hydrogen peroxide. To elucidate the regulatory mechanism, the regulatory protein (OxyR) of catalase transcription is identified. After cloning and sequencing Brucella oxyR (boxyR) gene, I found that boxyR is one of the LysR family of transcription factors with a helix-turn-helix DNA binding motif. I also show that bOxyR binds to the catalase gene promoter. Brucella oxyR is immediately upstream of the catalase gene but in the opposite orientation. The two genes share the same promoter region. The deduced amino acid sequence of boxyR shows only 40% identity with other known OxyR sequences. This is the first report that OxyR regulates catalase in the a subdivision of Proteobacteria (purple bacteria)

S100A9 Knockout Decreases the Memory Impairment and Neuropathology in Crossbreed Mice of Tg2576 and S100A9 Knockout Mice Model

Our previous study presented evidence that the inflammation-related S100A9 gene is significantly upregulated in the brains of Alzheimer's disease (AD) animal models and human AD patients. In addition, experiments have shown that knockdown of S100A9 expression improves cognition function in AD model mice (Tg2576), and these animals exhibit reduced amyloid plaque burden. In this study, we established a new transgenic animal model of AD by crossbreeding the Tg2576 mouse with the S100A9 knockout (KO) mouse. We observed that S100A9KO/Tg2576 (KO/Tg) mice displayed an increased spatial reference memory in the Morris water maze task and Y-maze task as well as decreased amyloid beta peptide (Aβ) neuropathology because of reduced levels of Aβ, C-terminal fragments of amyloid precursor protein (APP-CT) and phosphorylated tau and increased expression of anti-inflammatory IL-10 and also decreased expression of inflammatory IL-6 and tumor neurosis factor (TNF)-α when compared with age-matched S100A9WT/Tg2576 (WT/Tg) mice. Overall, these results suggest that S100A9 is responsible for the neurodegeneration and cognitive deficits in Tg2576 mice. The mechanism of S100A9 is able to coincide with the inflammatory process. These findings indicate that knockout of S100A9 is a potential target for the pharmacological therapy of AD. © 2014 Kim et al.1

Methylsulfonylmethane ameliorates metabolic-associated fatty liver disease by restoring autophagy flux via AMPK/mTOR/ULK1 signaling pathway

Introduction: Metabolism-associated fatty liver disease (MAFLD) is a global health concern because of its association with obesity, insulin resistance, and other metabolic abnormalities. Methylsulfonylmethane (MSM), an organic sulfur compound found in various plants and animals, exerts antioxidant and anti-inflammatory effects. Here, we aimed to assess the anti-obesity activity and autophagy-related mechanisms of Methylsulfonylmethane.Method: Human hepatoma (HepG2) cells treated with palmitic acid (PA) were used to examine the effects of MSM on autophagic clearance. To evaluate the anti-obesity effect of MSM, male C57/BL6 mice were fed a high-fat diet (HFD; 60% calories) and administered an oral dose of MSM (200 or 400 mg/kg/day). Moreover, we investigated the AMP-activated protein kinase (AMPK)/mechanistic target of rapamycin complex 1 (mTORC1)/UNC-51-like autophagy-activating kinase 1 (ULK1) signaling pathway to further determine the underlying action mechanism of MSM.Results: Methylsulfonylmethane treatment significantly mitigated PA-induced protein aggregation in human hepatoma HepG2 cells. Additionally, Methylsulfonylmethane treatment reversed the PA-induced impairment of autophagic flux. Methylsulfonylmethane also enhanced the insulin sensitivity and significantly suppressed the HFD-induced obesity and hepatic steatosis in mice. Western blotting revealed that Methylsulfonylmethane improved ubiquitinated protein clearance in HFD-induced fatty liver. Remarkably, Methylsulfonylmethane promoted the activation of AMPK and ULK1 and inhibited mTOR activity.Conclusion: Our study suggests that MSM ameliorates hepatic steatosis by enhancing the autophagic flux via an AMPK/mTOR/ULK1-dependent signaling pathway. These findings highlight the therapeutic potential of MSM for obesity-related MAFLD treatment

Meaning-Making Interactions to Co-construct Written Texts between Graduate Student Clinicians (GSCs) and Children with Language and Learning Difficulties (LLD): Two Case Studies

The purpose of this study is to identify the complex features of writing intervention of Graduate Student Clinicians (GSCs) for children with Language and Learning Difficulties (LLD) upon the qualitative research paradigm. To do this, verbal and non-verbal interactions, a total of two hours 18 minutes and 44 four seconds and a total of 2,170 turns of the four writing sessions of the two dyads, were video-taped, transcribed, and encoded depending on the contexts, purposes, and strategies. The complexity in the process of writing by the two dyads was revealed and compared in terms of the activities of turns exchanged and time allocated in the two GSCs’ strategies for writing intervention and the two children’s responses throughout the writing sessions. The findings of this study indicate the two dyads demonstrated two distinct interactional features in verbal and non-verbal behaviors in terms of whether GSCs were concentrated on process or products, and they used different strategies for verbal and non-verbal intervention. The responses of children with LLD revealed in the overall dynamic features of writing sessions were greatly influenced by the GSCs’ verbal and non-verbal strategies. The child in Dyad One in which GSC-One focused more on implicit and symmetric process-oriented mediations successfully engaged in various writing activities while the child in Dyad Two in which GSC-Two focused on explicit asymmetric product-oriented mediations tended to be confused while less effectively engaged in the verbal and non-verbal interactions. The conclusion was made to emphasize that the transferability of GSCs’ writing interventions strategies into the writing process of children with LLD, and the importance of training future Speech Language Pathologists by allowing them understand their roles in the process rather than the results of writing

Regulation of Brucella abortus catalase as a defensive mechanism against oxidative stress

Free radicals in the nature are harmful to organisms because they cause damage to tissues, cell membranes, proteins, and DNA. The animal immune system (cell mediated immune response) uses oxygen molecules to kill foreign organisms. B. abortus causes a cattle disease called brucellosis. The mechanism for bacteria to survive and adapt in the face of oxidative attack is thought to be important for understanding pathogenesis. This dissertation presents the response of B. abortus to oxidative stress and the regulation of catalase as a defensive mechanism;Different protein expression patterns were observed during oxidative stress by conducting 2-D protein gel analysis. DnaK (Hsp70) and GroEL (Hsp60) were not dramatically changed in the protein expression level, whereas, Cu-Zn SOD and catalase were upregulated in response to oxidative stress. Catalase is known as the critical enzyme for removal of hydrogen peroxide and the protection of cells from oxidative damage. I show that catalase is increased both in protein expression and in RNA transcription in the presence of hydrogen peroxide. To elucidate the regulatory mechanism, the regulatory protein (OxyR) of catalase transcription is identified. After cloning and sequencing Brucella oxyR (boxyR) gene, I found that boxyR is one of the LysR family of transcription factors with a helix-turn-helix DNA binding motif. I also show that bOxyR binds to the catalase gene promoter. Brucella oxyR is immediately upstream of the catalase gene but in the opposite orientation. The two genes share the same promoter region. The deduced amino acid sequence of boxyR shows only 40% identity with other known OxyR sequences. This is the first report that OxyR regulates catalase in the a subdivision of Proteobacteria (purple bacteria).</p

Sequential Recommendations on GitHub Repository

The software development platform is an increasingly expanding industry. It is growing steadily due to the active research and sharing of artificial intelligence and deep learning. Further, predicting users’ propensity in this huge community and recommending a new repository is beneficial for researchers and users. Despite this, only a few researches have been done on the recommendation system of such platforms. In this study, we propose a method to model extensive user data of an online community with a deep learning-based recommendation system. This study shows that a new repository can be effectively recommended based on the accumulated big data from the user. Moreover, this study is the first study of the sequential recommendation system that provides a new dataset of a software development platform, which is as large as the prevailing datasets. The experiments show that the proposed dataset can be practiced in various recommendation tasks

Catechol as a New Electron Hot Spot of Carbon Nitride

Graphitic carbon nitride (CNx) is a promising photocatalyst with visible-light sensitivity, attractive band-edge positions, tunable electronic structure, and eco-friendliness. However, their applications are limited by a low catalytic activity due to inefficient charge separation and insufficient visiblelight absorption. Here we show a new method to generate the electron polarization of CNx toward the edge via the chemical conjugation of catechol to CNx for enhanced photochemical activity. The electron-attracting property of catechol/quinone pairs induces the accumulation of photoexcited electrons at the edge of conjugated catechol-CNx hybrid nanostructure (Cat-CNx), , serving as an electron hot spot, as demonstrated by positive open-circuit photovoltage, which increases electron transfer through the conjugated catechol while suppressing charge recombination in the CNx. The catechol conjugation also widens the photoactive spectrum via the larger range delocalization of π-electrons. Accordingly, Cat-CNx reveals a 6.3 higher reductive photocurrent density than CNx. Gold ion reduction dramatically increased due to the enhanced electron transfer activity of Cat-CNx in cooperation with the inherent hydrophilicity and metal chelating property of catechols. Cat-CNx exhibits a 4.3 higher maximum adsorption capacity for gold ions under simulated sun light illumination compared to CNx. This work suggests that the post-modification of CNx’s π-conjugated system is a promising route to handle varied shortcomings and broaden availability of CNx

Evaluation of Temporal Contribution of Groundwater to a Small Lake through Analyses of Water Quantity and Quality

Groundwater can flow into or out of surface water and thus can greatly affect the quantity and quality of surface water. In this study, we conducted a water quantity and quality analysis for 11 months in 2018 and 2019 to evaluate the temporal contribution of groundwater to surface water at Osongji, a small lake located in Jeonju-si, Jeollabuk-do, Korea. Groundwater fluxes and groundwater and surface water levels were measured using seepage meters and a piezometer, respectively. On-site water quality parameters, cations, and anions for groundwater and surface water were analyzed. Hydrogen and oxygen isotopes for groundwater, surface water, and rainwater were also analyzed. Groundwater influx did not correlate directly to precipitation, suggesting that it may be delayed after rainwater infiltration. Aqueous chemistry indicated that the hydrogeochemical characteristics of surface water were substantially affected by groundwater. The isotopic composition of surface water changed over time, indicating a different contribution of groundwater in different seasons. This study shows that water quantity and quality data can be used in combination to evaluate temporal changes in the groundwater contribution to surface water