Transcriptional regulation by sigma factor phosphorylation controls polymyxin resistance and swarming behavior in Vibrio parahaemolyticus

A major form of bacterial transcriptional regulation occurs by the exchange of the primary σ factor of the RNA polymerase with alternative ECF σ factors, which generally are retained in an inactive state by sequestration into σ/anti-σ factor complexes (until they are needed). Using Vibrio parahaemolyticus as a model organism, we report a novel mechanism of transcriptional regulation, which instead relies on intrinsically inactive ECF σ factors that in turn rely on σ factor phosphorylation for interaction with the RNA polymerase. Particularly, we show that upon polymyxin stress, the threonine kinase PknT phosphorylates the σ factor EcfP, resulting in EcfP activation and expression of an essential polymyxin resistance regulon. EcfP phosphorylation occurs at a highly conserved threonine residue, Thr63, positioned within a divergent region in the σ2.2 helix. EcfP is intrinsically inactive and unable to bind RNA polymerase due to the absence of a negatively charged DAED motif in this region. Our results indicate that phosphorylation at residue Thr63 mimics this negative charge and licenses EcfP for interaction with RNA polymerase and activation of target gene expression. Regulation of gene expression by phosphorylation of ECF σ factor is likely a widespread mechanism in bacteria, presenting a new paradigm in transcriptional regulation. One of the unique features of V. parahaemolyticus is that it exhibits a dual lifestyle. In liquid environments, where the bacteria are free-living, they exist as short swimmer cells with a single polar flagellum. However, upon encountering solid surfaces, the bacteria differentiate into highly elongated swarmer cells that are characterized by the presence of numerous peritrichous lateral flagella. Here, we report the involvement of the aforementioned threonine kinase/ECF σ factor system, namely PknT/EcfP, in regulation of swarming behavior. Strikingly, our findings indicate that this regulatory role depends on a phosphorylation-driven mechanism. We also provide evidence for the role of two other proteins encoded by genes present within the same operon as that of pknT and ecfP, namely VP0054 and VP0056, in regulation of swarming behavior. Our findings also reveal several key targets such as transporters and proteins involved in certain biosynthetic processes that are regulated by PknT. This is the first time that STKs have been implicated in swarming behavior in bacteria

Information Systems in Bangalore Traffic: A Case Study

Year 2012, month of March, Monday morning 8.30 a.m. Ramesh, a techie1in his mid 30s with one of the popular software companies in Bangalore was on his way to office. He was waiting for the traffic signal to turn green in one of the busiest junctions of Bangalore city

Effects Of Electrospun Scaffolds On Epithelial Cell Growth And Morphology

Regeneration of cells on a scaffold is a main aspect in tissue engineering. Nanofibrous scaffolds from electrospinning provide great potential to engineer scaffolds for desired tissue engineering applications because they can mimic in vivo extracellular matrix (ECM). However, there is little known about how the microstructure and surface properties of electrospun nanofibrous scaffold influences the migration and growth of cells. Fundamental studies is demanded to understand the interaction between nanofibrous substrate and cells. In this research, four typical electrospun nanofibrous scaffolds including polyacrylonitrile (PAN), carbon, cellulose acetate (CA) and cellulose were prepared, characterized and then employed as scaffolds for Madin Darby Canine Kidney Epithelial Cells (MDCK). Effects of these electrospun nanofibrous scaffolds on MDCK’s growth and morphology were investigated by confocal microscopy. The results from this research provide bioengineers with basic understandings on the mechanisms involved in cell-nanofibrous substrate and cell-cell interactions

Many-Body Localization in a Quasiperiodic System

Recent theoretical and numerical evidence suggests that localization can survive in disordered many-body systems with very high energy density, provided that interactions are sufficiently weak. Stronger interactions can destroy localization, leading to a so-called many-body localization transition. This dynamical phase transition is relevant to questions of thermalization in extended quantum systems far from the zero-temperature limit. It separates a many-body localized phase, in which localization prevents transport and thermalization, from a conducting ("ergodic") phase in which the usual assumptions of quantum statistical mechanics hold. Here, we present numerical evidence that many-body localization also occurs in models without disorder but rather a quasiperiodic potential. In one dimension, these systems already have a single-particle localization transition, and we show that this transition becomes a many-body localization transition upon the introduction of interactions. We also comment on possible relevance of our results to experimental studies of many-body dynamics of cold atoms and non-linear light in quasiperiodic potentials.Comment: (12 pages + 3 page appendix, 11 figures) This version has been accepted to PRB. We have clarified certain points and slightly modified the organization of the paper in response to comments by two referee

Susceptibility at the superfluid-insulator transition for one-dimensional disordered bosons

A pair of recent Monte Carlo studies have reported evidence for and against a crossover from weak to strong-disorder criticality in the one-dimensional dirty boson problem. The Monte Carlo analyses rely on measurement of two observables: the effective Luttinger parameter K_(eff) and the superfluid susceptibility χ. The former quantity was previously calculated analytically, using the strong-disorder renormalization group (SDRG), by Altman, Kafri, Polkovnikov, and Refael. Here, we use an extension of the SDRG framework to find a non-universal anomalous dimension η_(sd) characterizing the divergence of the susceptibility with system size: χ ~ L^(2-η_(sd)). We show that η_(sd) obeys the hyperscaling relation η_(sd) = 1/2K_(eff). We also identify an important obstacle to measuring this exponent on finite-size systems and comment on the implications for numerics and experiments

Resilient Supply Chain in United Arab Emirates

Supply chain disruption refers to any event or occurrence that interrupts the flow of goods or services from suppliers to customers. This disruption can have a significant impact on businesses and can lead to delays, shortages, and increased costs. To mitigate the impact of supply chain disruptions, businesses can take several steps. These include diversifying their supplier base, maintaining safety stock levels, investing in technology to improve supply chain visibility, and developing contingency plans for dealing with disruptions. In addition, businesses can work with their suppliers and customers to build stronger relationships and improve communication and collaboration. This can help to identify potential issues early and allow for more effective problem-solving when disruptions do occur. Overall, supply chain disruption is a significant challenge for businesses, but with careful planning and proactive measures, it is possible to minimize the impact and maintain business continuity. The mixed methodology used in the research to capture the expertise opinions and the stakeholder’s expectations of the Supply chain and its necessity to be resilient

Microbial interactions with nanoscale features

Bacteria and other microbes interact with their environment through nanoscale mechanical and chemical processes. Understanding these interactions is critical for controlling bacteria, both in preventing biofilm formation and in using these interactions to control bacterial metabolism and behavior in industrially relevant applications such as fermentation and biomaterial generation. Biofilm formation is a key step in the process of biofouling, a process of great importance in shipping and food processing industries and especially in healthcare where it is of utmost importance to prevent the formation of biofilms on medical equipment which would further prevent infections. In this dissertation, I examine the biological responses of the Gram-negative bacterium, Escherichia coli (E. coli) to alterations in the surface nanostructure, persistent photoconductivity, and the stiffness of the surface material. In my characterization of Bacterial interactions with nanostructured surfaces, I examined the behavior of E. coli bacteria, when exposed to twenty-one different nanostructured polymeric substrates etched from seven common and industrially relevant polymers. I demonstrated that in the bacteria respond to the surfaces by changing their adhesion, morphology and biofilm formation. Interestingly neither surface energy nor structure appeared to control these behaviors. The predominant effect on bacterial behavior appeared to be directed by the composition of the surface. To investigate the mechanisms that control the bacterial response to a surface phenomenon known as persistent photoconductivity (PPC), I used E. coli strains that were mutant for genes that encoded specific components of adhesion and/or biofilm formation. One goal of microbial bioelectronics is to develop hybrid organic/inorganic interfaces between living cells and electronic devices. Type III semiconductors such as GaN are a good candidate for such interfaces; Gallium nitride and Oxide materials are biocompatible, a growing material system for electronics, and have a property known as persistent photoconductivity (PPC), which is the persistence of a charge after excitation energy such as ultraviolet light is removed. Work in the Ivanisevic and LaJeunesse labs have shown that PPC changes the physiology of the bacterial cells and results in both an increase in intracellular Ca2+ and alteration to cell adhesion. To determine which cell surface and adhesive components of E. coli are required for the response to PCC, I used a collection of E. coli deletion mutants and examined the loss of these cell structures on the bacteria’s response to PCC. I found that mutation in the synthetic pathways that generate the LPS, curli, and mutations in flagella significantly alter the response of E. coli to PPC. To determine the bacterial adhesive response to material stiffness, I tested the adhesion of E. coli to Polyacrylamide hydrogels of three different stiffnesses (~17kPa, 29kPa and 1547 kPa). Wild type E. coli demonstrated the highest adhesion to the soft PA hydrogel and the least on the hard gel. I used single-gene deletion mutants of E. coli bacterial surface appendages to determine how the loss of these cellular structures would affect bacterial adhesion to these gels. I compared the adhesion trends of the various knockouts to the WT trend and found that they were vastly different, and with no particular pattern. Adhesion of bacteria to the soft gels was significantly lower than the adhesion of the WT except for the csgD mutant. All the knockout bacteria adhered more to the hard gels in comparison to the WT adhesion. Identifying the most important deletion remains a challenge, even though all the deletions resulted in a change in bacterial adhesion. This analysis has provided a framework for the further elucidation of genetic pathways involved in the bacterial responses. [This abstract has been edited to remove characters that will not display in this system. Please see the PDF for the full abstract.]]]> 2019 Escherichia coli $x Biotechnology Microbial biotechnology Nanostructured materials Photoconductivity English http://libres.uncg.edu/ir/uncg/f/Iyer_uncg_0154D_12923.pdf oai:libres.uncg.edu/29255 2020-01-17T11:22:01Z UNCG Traditional vs. self-compassionate expressive writing: differentiating processes through linguistic analysis Kalianivala, Anahita Z. NC DOCKS at The University of North Carolina at Greensboro <![CDATA[Expressive writing (EW) is an experimental paradigm developed by Pennebaker and colleagues (Pennebaker &amp; Beall, 1986). In traditional EW tasks, participants are asked to disclose their deepest thoughts and emotions concerning the most traumatic or stressful event of their lives. Consistent with the notion that EW may be beneficial for those with psychological diagnoses, research has looked to individual differences that infer risk or are associated with the maintenance of psychological disorders. It has been posited that an underlying mechanism of EW is the implicit message for participants to be accepting and non-judgmental towards their emotions and cognitions through the instruction to delve into one’s deepest thoughts and feelings. Thus, EW may be a particularly useful intervention tool for individuals prone to rumination, a repetitive form of thinking about the self, especially one’s sad or depressed feelings (Nolen-Hoeksema, Wisco, &amp; Lyubomirsky, 2008). In particular, Baum and Rude (2013) proposed self-compassion as a related construct that may further enhance the benefit of EW. The current study sought to align multiple arms of EW research that have typically been separately pursued: comparing traditional EW to an adapted paradigm (e.g., providing instructions that guide participants to engage in principles of self-compassion,); measuring individual differences which may impact EW benefit; and conducting linguistic analysis to further understand psychological processes occurring during writing. Overall, participants reported both EW conditions as beneficial, on average. Negative affect increased across writing sessions for the full sample, consistent with typical immediate effects of EW. However, none of the hypothesized differences in affect or cognitive word use by EW condition were supported, nor were the moderation effects of rumination

Equilibrium dialysis and carbohydrate-binding studies on the 2-acetamido-2-deoxy--glucopyranosyl-binding lectin from Bandeiraea simplicifolia seeds

The carbohydrate-binding specificity of Bandeiraea simplicifolia lectin II (BS II lectin) has been studied by quantitative precipitin and hapten-inhibition analysis. The BS II lectin precipitated biopolymers having nonreducing 2-acetamido-2-deoxy--glucopyranosyl residues, such as antigen A. Dextran B-1355-S and rabbit-liver glycogen also afforded precipitin curves with high concentrations of the BS II lectin. Phenyl 2-acetamido-2-deoxy-[alpha]--glucopyranoside and p-nitrophenyl 2-acetamido-2-deoxy-[alpha]--glucopyranoside, the best inhibitors of the BS II lectin-p-azophenyl 2-acetamido-2-deoxy-[beta]--glucopyranoside--bovine serum albumin conjugate precipitin-system, were 4 times as active as 2-acetamido-2-deoxy--glucopyranose. Of the free monosaccharides tested, 2-acetamido-2-deoxy--glucopyranose was the most potent inhibitor, being over 100 times better than -fructose and 400 times better than -glucose. Comparison of the inhibiting capacity of methyl or p-nitrophenyl 2-acetamido-2-deoxy-[alpha]--glucopyranoside with their corresponding [beta] anomers showed that the [alpha] anomer was bound 6 to 8 times more avidly than the [beta] anomer. Replacement of the C-3, C-4, or C-6 hydroxyl group of -glucose by a methoxyl group or a fluorine atom abolished the capacity of the resulting sugar to bind the BS II lectin, but substitution of the C-2 hydroxyl group of -glucose, by either a methoxyl group or a fluorine group, had no appreciable effect on binding to the lectin. N,N'-Diacetylchitobiose was as active as N,N'N''-triacetylchitotriose, and they were both twice as potent as disaccharides having a nonreducing 2-acetamido-2-deoxy-[alpha]--glucopyranosyl residue. Disaccharides having [beta]--(1 --&gt; 6) glycosidic bonds were very poor inhibitors. Equilibrium-dialysis experiments with p-nitrophenyl 2-acetamido-2-deoxy-[alpha]--glucopyranoside as binding ligand indicated that the BS II lectin possesses approximately one carbohydrate-binding site per subunit for the tetrameric protein (Mr 113,000), with association constants of 1.3 x 105 M-1 at 4[deg], and 0.4 X 105 M-1 at 37[deg].Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22640/1/0000191.pd