Directed evolution of Vibrio fischeri LuxR for improved response to butanoyl-homoserine lactone

LuxR is the 3-oxohexanoyl-homoserine lactone (3OC6HSL) dependent transcriptional activator of the prototypical acyl-homoserine lactone (AHL) quorum sensing system of Vibrio fischeri. Wild-type LuxR exhibits no response to butanoyl-HSL (C4HSL) in quantitative bioassays at concentrations of up to 1 µM; a previously described LuxR variant (LuxR-G2E) exhibits a broadened response to diverse AHLs, including pentanoyl-HSL (C5HSL), but not to C4HSL. Here, two rounds of directed evolution of LuxR-G2E generated variants of LuxR that responded to C4HSL at concentrations as low as 10 nM. One variant, LuxR-G4E, had only one change, I45F, relative to the parent LuxR-G2E, which itself differs from wild-type at three residues. Dissection of the four mutations within LuxR-G4E demonstrated that at least three of these changes were simultaneously required to achieve any measurable C4HSL response. The four changes improved both sensitivity and specificity towards C4HSL relative to any of the other 14 possible combinations of those residues. These data confirm that LuxR is evolutionarily pliable and suggest that LuxR is not intrinsically asymmetric in its response to quorum sensing signals with different acyl-side chain lengths

Best Practice Description Document

This work received support and funding from • The BOHAB project (Biological Oceanography of Harmful Algal Blooms off the west coast of Ireland) through the National Development Plan 2000 – 2006 with the support of the Marine Institute and the Marine RTDI (Research, Technology, Development and Innovation) Measure, Productive Sector Operational Programme, Grant-aid Agreement No. ST/02/01. • the ASIMUTH project (Applied simulations and Integrated modelling for the understanding of toxic and harmful algal blooms) through the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013) for Research and Technological Development - EC FP7 Programme, Space Theme, Grant Agreement No. 261860 • the MyOcean 2 project through the EC FP7 Programme, Space Theme, Grant Agreement No. 283367 • the AtlantOS project through the European Union's Horizon 2020 research and innovation programme, Grant Agreement No. 633211 • The PRIMROSE (Predicting the impact of regional scale events on the aquaculture sector) project, co-financed by the European Regional Development Fund through the Interreg Atlantic Area Programme, EAPA_182/2016 • The CoCliME (Co-development of climate services for adaptation to changing marine ecosystems) project is part of the European Research Area for Climate Services (ERA4CS), an ERA-NET initiated by JPI Climate, and funded by EPA (IE), ANR (FR), BMBF (DE), UEFISCDI (RO), RCN (NO) and FORMAS (SE), with co-funding by the European Union (Grant Agreement No. 690462).This document describes the procedural steps in creating an information product focused on toxic and harmful phytoplankton. The product is an online Harmful Algal Bloom (HAB) bulletin for aquaculturists, who can face serious operational challenges in the days after a HAB event. Data from satellite, numerical hydrodynamic models and In-situ ocean observations are organised and presented into visual information products. These products are enhanced through local expert evaluation and their interpretation is summarised in the bulletin. This document aims to provide both process overviews (the “what” of the Best Practice in producing the bulletins) and detail procedures (the “how” of the Best Practice”) so that the bulletins may be replicated in other geographic regions.European Commissio

Freezing Transition, Characteristic Polynomials of Random Matrices, and the Riemann Zeta-Function

We argue that the freezing transition scenario, previously explored in the statistical mechanics of 1/f-noise random energy models, also determines the value distribution of the maximum of the modulus of the characteristic polynomials of large N x N random unitary (CUE) matrices. We postulate that our results extend to the extreme values taken by the Riemann zeta-function zeta(s) over sections of the critical line s=1/2+it of constant length and present the results of numerical computations in support. Our main purpose is to draw attention to possible connections between the statistical mechanics of random energy landscapes, random matrix theory, and the theory of the Riemann zeta function.Comment: published version with a few misprints corrected and references adde

Industrial resources, industries, and potentialities of the seventh congressional district of Texas

No Abstrac

Validation of a Single Inertial Sensor for Measuring Running Kinematics Overground During a Prolonged Run

This article is made available in accordance with the publisher's statement on Open access.Introduction: The purpose of this study was to validate acceleration data from a single inertial sensor containinga tri-axial accelerometer, whilst running overground during a prolonged run against a motion analysis system. Methods: An inertial sensor was placed on the low back of 10 runners who performed an 8 km run on a treadmill.To provide validation of the sensor, data were collected as runners ran along a runway through a motion analysis system at the beginning and throughout the run.Results: High levels of agreement between the two systems were found in the craniocaudal and mediolateral acceleration, with antero posterior having the least agreement with greatest Typical Error of the Estimate (0.66 sample points). Very high to extremely high correlations across all testing times were found in all three directions of accelerations (r=0.75 to 0.95). Heel strike and toe off events were identified in anteroposterior and craniocaudal acceleration, with high levels of agreement and extremely high correlations (r=0.99) between the two systems.Minimal variation and change in agreement and correlation between the data at each testing time were found. Discussion: This study provides evidence that a single inertial sensor placed on the low back is valid for measuring three-dimensional acceleration in overground running during a prolonged run. Further analysis identified specific events of heel strike and toe off and were comparable between the two systems. The minimal variation and change in agreement between the two systems during the run indicates the adherence method of the inertial sensor was suitable. Conclusions: The results of this study indicate that data collected from a single inertial sensor is highly correlated with simultaneous data collected using a motion analysis system, and has the capability to identify heelstrike and toe off events in overground running throughout a prolonged fatiguing run

Novel ultrastructures of Treponema primitia and their implications for motility

Members of the bacterial phylum Spirochaetes are generally helical cells propelled by periplasmic flagella. The spirochete Treponema primitia is interesting because of its mutualistic role in the termite gut, where it is believed to cooperate with protozoa that break down cellulose and produce H2 as a by-product. Here we report the ultrastructure of T. primitia as obtained by electron cryotomography of intact, frozen-hydrated cells. Several previously unrecognized external structures were revealed, including bowl-like objects decorating the outer membrane, arcades of hook-shaped proteins winding along the exterior and tufts of fibrils extending from the cell tips. Inside the periplasm, cone-like structures were found at each pole. Instead of the single peptidoglycan layer typical of other Gram-negative bacteria, two distinct periplasmic layers were observed. These layers formed a central open space that contained two flagella situated adjacent to each other. In some areas, the inner membrane formed flattened invaginations that protruded into the cytoplasm. High-speed light microscopic images of swimming T. primitia cells showed that cell bodies remained rigid and moved in a helical rather than planar motion. Together, these findings support the 'rolling cylinder' model for T. primitia motility that posits rotation of the protoplasmic cylinder within the outer sheath