Study of regulators affecting type III and type VI secretion system in Edwardsiella Tarda

Ph.DDOCTOR OF PHILOSOPH

The Impact of Cultural Communication on Team Performance

The trend in today’s corporate workforce continues to move towards becoming more culturally diverse; while beneficial, to maintain competitive edge this element also increases functional challenges between working group members. In order to achieve a high performing team, it is imperative management understands the cultural and lingual differences among the individual members, and develop practices that diminish these challenges. Workforce diversity has been identified as being able to add value to the overall outcome; however, success ultimately depends on the team’s ability to interact culturally, communicate effectively, and understand the mannerisms unique to each team member’s individual culture. Examining Geert Hofstede’s work; a model that quantitatively measures cultural differences, the authors start their discussion on factors that lead to cultural norms and highlight, through management practices, ways to minimize challenges and increase interaction in the team environment. Once members understand the individual nuances of culture midst their counterparts, the team can focus on an equally important aspect to becoming a high performing team; effective communicating. Next, the authors move the analysis to address the hurdles centered around team member’s linguistical challenges. This facet too presents a set of unique challenges; which, if not addressed properly, can lead to poor performance and a lack of trust among the group. Finally, the authors conclude by identifying the unique nonverbal communication norms, among cultures, which too can adversely affect a team’s performance. This paper looks to synthesize the literature which highlights these three aspects of communication in the team environment

A FRET-Based DNA Biosensor Tracks OmpR-Dependent Acidification of Salmonella during Macrophage Infection

10.1371/journal.pbio.1002116PLoS Biology134e100211

Enhanced Vibrational Stability in Glass Droplets

We show through simulations of amorphous solids prepared in open boundary conditions that they possess significantly fewer low-frequency vibrational modes compared to their periodic boundary counterparts. Specifically, using measurements of the vibrational density of states, we find that the $D(\omega) \sim \omega^4$ law changes to $D(\omega) \sim \omega^\delta$ with $\delta \approx 5$ in two dimensions and $\delta \approx 4.5$ in three dimensions. Crucially, this enhanced stability is achieved when utilizing slow annealing protocols to generate solid configurations. We perform an anharmonic analysis of the minima corresponding to the lowest-frequency modes in such open-boundary systems and discuss their correlation with the density of states. A study of various system sizes further reveals that small systems display a higher degree of localization in vibrations. Lastly, we confine open-boundary solids in order to introduce macroscopic stresses in the system which are absent in the unconfined system, and find that the $D(\omega) \sim \omega^4$ behavior is recovered.Comment: 12 pages, 11 figure

Structural Basis for the Secretion of EvpC: A Key Type VI Secretion System Protein from Edwardsiella tarda

The recently identified type VI secretion system (T6SS) is implicated in the virulence of many Gram-negative bacteria. Edwardsiella tarda is an important cause of hemorrhagic septicemia in fish and also gastro- and extra-intestinal infections in humans. The E. tarda virulent protein (EVP) gene cluster encodes a conserved T6SS which contains 16 open reading frames. EvpC is one of the three major EVP secreted proteins and shares high sequence similarity with Hcp1, a key T6SS virulence factor from Pseudomonas aeruginosa. EvpC contributes to the virulence of E. tarda by playing an essential role in functional T6SS. Here, we report the crystal structure of EvpC from E. tarda PPD130/91 at a 2.8 Å resolution, along with functional studies of the protein. EvpC has a β-barrel domain with extended loops. The β-barrel consists of 11 anti-parallel β-strands with an α-helix located on one side. In solution, EvpC exists as a dimer at low concentration and as a hexamer at higher concentration. In the crystal, the symmetry related EvpC molecules form hexameric rings which stack together to form a tube similar to Hcp1. Structure based mutagenesis revealed that N-terminal negatively charged residues, Asp4, Glu15 and Glu26, and C-terminal positively charged residues, Lys161, Lys162 and Lys163, played crucial roles in the secretion of EvpC. Moreover, the localization study indicates the presence of wild type EvpC in cytoplasm, periplasm and secreted fractions, whereas the N-terminal and C-terminal mutants were found mostly in the periplasmic region and was completely absent in the secreted fraction. Results reported here provide insight into the structure, assembly and function of EvpC. Further, these findings can be extended to other EvpC homologs for understanding the mechanism of T6SS and targeting T6SS mediated virulence in Gram-negative pathogens

A New Role of OmpR in Acid and Osmotic Stress in Salmonella and E. coli

Bacteria survive and respond to diverse environmental conditions and during infection inside the host by systematic regulation of stress response genes. E. coli and S. Typhimurium can undergo large changes in intracellular osmolality (up to 1.8 Osmol/kg) and can tolerate cytoplasmic acidification to at least pHi 5.6. Recent analyses of single cells challenged a long held view that bacteria respond to extracellular acid stress by rapid acidification followed by a rapid recovery. It is now appreciated that both S. Typhimurium and E. coli maintain an acidic cytoplasm through the actions of the outer membrane protein regulator OmpR via its regulation of distinct signaling pathways. However, a comprehensive comparison of OmpR regulons between S. Typhimurium and E. coli is lacking. In this study, we examined the expression profiles of wild-type and ompR null strains of the intracellular pathogen S. Typhimurium and a commensal E. coli in response to acid and osmotic stress. Herein, we classify distinct OmpR regulons and also identify shared OmpR regulatory pathways between S. Typhimurium and E. coli in response to acid and osmotic stress. Our study establishes OmpR as a key regulator of bacterial virulence, growth and metabolism, in addition to its role in regulating outer membrane proteins

Crystal Structure of the Heteromolecular Chaperone, AscE-AscG, from the Type III Secretion System in Aeromonas hydrophila

10.1371/journal.pone.0019208PLoS ONE64

A Hierarchal Decision Model to Determine the Most Promising Tier-2 Space Agency

When it comes to space exploration programs NASA, ISRO, SpaceX, CNSA, JAXA and ESA has made remarkable achievements in the past and is keep making more and more success. The study, on completion, seeks to guide the decision problem of “which space agency has the best future in space exploration?”. This study will seek to find which space agency has the best future prospect in terms of various perspectives. To find a solution to the stated problem, initially available literature was studied and the probable solutions for the decision problem was enlisted. Data Records from the organization websites were studied to determine financial, impact, technical, track record etc., which was followed by a hierarchical decision model (HDM) by mapping out the different factors that affect the preference of country with orbiting space program. A panel of 6 experts was chosen and were requested for assistance to evaluate the model and then the results were evaluated and compared. After further analysis, additional decision-making changes may be done. Revisiting the opinion of panel of experts may or may not conducted to draw the conclusion in the entire decision-making process. The biggest drawback of this study is that the data used for quantitative analysis by the panel of experts. The panel doesn’t include individuals from every organization of the alternatives, resulting is lack of confidential information of these agencies. For future research, study based on data sources from every alternative organization would be helpful as that would affect expert preference and opinion

A New Role of OmpR in Acid and Osmotic Stress in Salmonella and E. coli

10.3389/fmicb.2018.02656Frontiers in Microbiology9NOV265

Adipose Tissue: Understanding the Heterogeneity of Stem Cells for Regenerative Medicine

Adipose-derived stem cells (ASCs) have been increasingly used as a versatile source of mesenchymal stem cells (MSCs) for diverse clinical investigations. However, their applications often become complicated due to heterogeneity arising from various factors. Cellular heterogeneity can occur due to: (i) nomenclature and criteria for definition; (ii) adipose tissue depots (e.g., subcutaneous fat, visceral fat) from which ASCs are isolated; (iii) donor and inter-subject variation (age, body mass index, gender, and disease state); (iv) species difference; and (v) study design (in vivo versus in vitro) and tools used (e.g., antibody isolation and culture conditions). There are also actual differences in resident cell types that exhibit ASC/MSC characteristics. Multilineage-differentiating stress-enduring (Muse) cells and dedifferentiated fat (DFAT) cells have been reported as an alternative or derivative source of ASCs for application in regenerative medicine. In this review, we discuss these factors that contribute to the heterogeneity of human ASCs in detail, and what should be taken into consideration for overcoming challenges associated with such heterogeneity in the clinical use of ASCs. Attempts to understand, define, and standardize cellular heterogeneity are important in supporting therapeutic strategies and regulatory considerations for the use of ASCs