Improvement in the Nitrogen Use Efficiency and Uptake of Perennial Ryegrass (\u3cem\u3eLolium perenne\u3c/em\u3e) Caused by the \u3cem\u3eEpichloë\u3c/em\u3e Fungal Endophyte AR37

The forage yield and pasture persistence benefits of Epichloë fungal endophyte strain AR37 (AR37) in high rainfall perennial ryegrass (Lolium perenne) pastures in Australia and New Zealand are recognised. However, the effect of beneficial endophytes on nitrogen (N) use efficiency, yield response to applied N and N uptake had not been determined. To investigate this, a replicated trial was managed for three years under irrigation in southern Australia. Five N application rates (0, 20, 40, 80 and 160 kg N/ha) were applied every second harvest to a tetraploid perennial ryegrass variety with and without AR37. Ryegrass biomass was determined by full plot harvest and N percentage determined by near infrared spectroscopy. AR37 caused an increase in perennial ryegrass N use efficiency (the slope of the N response function) in all seasons, with the average increase in marginal response being 2.1 kg DM/kg N or 29.6 % over three-years. Benefit at individual harvests ranged from 0.2 to 6.5 kg DM/kg N. Foliage N percentage was not influenced by AR37 infection, thus AR37 caused enhanced N uptake due to increased forage yield. This trial demonstrates AR37 can contribute to the profitable and sustainable intensification of high rainfall perennial ryegrass pastures by significantly increasing the marginal yield response to N, and the uptake of applied N fertiliser. Further, increased N uptake caused by AR37 will likely have implication for negative environmental externalities associated with N use (leaching, runoff and nitrogenous greenhouse gas emissions) which warrants further investigation, along with research to clarify biotic and abiotic drivers of observed results

Minimal Brownian Ratchet: An Exactly Solvable Model

We develop an exactly-solvable three-state discrete-time minimal Brownian ratchet (MBR), where the transition probabilities between states are asymmetric. By solving the master equations we obtain the steady-state probabilities. Generally the steady-state solution does not display detailed balance, giving rise to an induced directional motion in the MBR. For a reduced two-dimensional parameter space we find the null-curve on which the net current vanishes and detailed balance holds. A system on this curve is said to be balanced. On the null-curve, an additional source of external random noise is introduced to show that a directional motion can be induced under the zero overall driving force. We also indicate the off-balance behavior with biased random noise.Comment: 4 pages, 4 figures, RevTex source, General solution added. To be appeared in Phys. Rev. Let

New paradoxical games based on Brownian ratchets

Based on Brownian ratchets, a counter-intuitive phenomenon has recently emerged -- namely, that two losing games can yield, when combined, a paradoxical tendency to win. A restriction of this phenomenon is that the rules depend on the current capital of the player. Here we present new games where all the rules depend only on the history of the game and not on the capital. This new history-dependent structure significantly increases the parameter space for which the effect operates.Comment: 4 pages, 3 eps figures, revte

Quantum field theory on quantum graphs and application to their conductance

We construct a bosonic quantum field on a general quantum graph. Consistency of the construction leads to the calculation of the total scattering matrix of the graph. This matrix is equivalent to the one already proposed using generalized star product approach. We give several examples and show how they generalize some of the scattering matrices computed in the mathematical or condensed matter physics litterature. Then, we apply the construction for the calculation of the conductance of graphs, within a small distance approximation. The consistency of the approximation is proved by direct comparison with the exact calculation for the `tadpole' graph.Comment: 32 pages; misprints in tree graph corrected; proofs of consistency and unitarity adde

Movement of IS26-Associated Antibiotic Resistance Genes Occurs via a Translocatable Unit That Includes a Single IS26 and Preferentially Inserts Adjacent to Another IS26

TheinsertionsequenceIS26playsakeyroleindisseminatingantibioticresistancegenesinGram-negativebacteria, forming regions containing more than one antibiotic resistance gene that are flanked by and interspersed with copies of IS26. A model presented for a second mode of IS26 movement that explains the structure of these regions involves a translocatable unit consisting of a unique DNA segment carrying an antibiotic resistance (or other) gene and a single IS copy. Structures resembling class I transposons are generated via RecA-independent incorporation of a translocatable unit next to a second IS26 such that the ISs are in direct orientation. Repeating this process would lead to arrays of resistance genes with directly oriented copies of IS26 at each end and between each unique segment. This model requires that IS26 recognizes another IS26 as a target, and in transpo- sition experiments, the frequency of cointegrate formation was 60-fold higher when the target plasmid contained IS26. This re- action was conservative, with no additional IS26 or target site duplication generated, and orientation specific as the IS26s in the cointegrates were always in the same orientation. Consequently, the cointegrates were identical to those formed via the known mode of IS26 movement when a target IS26 was not present. Intact transposase genes in both IS26s were required for high- frequency cointegrate formation as inactivation of either one reduced the frequency 30-fold. However, the IS26 target specificity was retained. Conversion of each residue in the DDE motif of the Tnp26 transposase also reduced the cointegration frequency

Bosonization and Scale Invariance on Quantum Wires

We develop a systematic approach to bosonization and vertex algebras on quantum wires of the form of star graphs. The related bosonic fields propagate freely in the bulk of the graph, but interact at its vertex. Our framework covers all possible interactions preserving unitarity. Special attention is devoted to the scale invariant interactions, which determine the critical properties of the system. Using the associated scattering matrices, we give a complete classification of the critical points on a star graph with any number of edges. Critical points where the system is not invariant under wire permutations are discovered. By means of an appropriate vertex algebra we perform the bosonization of fermions and solve the massless Thirring model. In this context we derive an explicit expression for the conductance and investigate its behavior at the critical points. A simple relation between the conductance and the Casimir energy density is pointed out.Comment: LaTex 31+1 pages, 2 figures. Section 3.6 and two references added. To appear in J. Phys. A: Mathematical and Theoretica

The impacts of feral boar on woodland flora and fauna in Great Britain

Mayle, B., Harmer, R., Kewitt, A., Peace, A., Straw, N., Williams, D., Upson, M

Highly thermostable carboxylic acid reductases generated by ancestral sequence reconstruction (article)

This is the final version. Available on open access from Nature Research via the DOI in this recordThe research data supporting this publication are openly available in ORE at https://doi.org/10.24378/exe.2003Carboxylic acid reductases (CARs) are biocatalysts of industrial importance. Their properties, especially their poor stability, render them sub-optimal for use in a bioindustrial pipeline. Here, we employed ancestral sequence reconstruction (ASR) – a burgeoning engineering tool that can identify stabilizing but enzymatically neutral mutations throughout a protein. We used a three-algorithm approach to reconstruct functional ancestors of the Mycobacterial and Nocardial CAR1 orthologues. Ancestral CARs (AncCARs) were confirmed to be CAR enzymes with a preference for aromatic carboxylic acids. Ancestors also showed varied tolerances to solvents, pH and in vivo-like salt concentrations. Compared to well-studied extant CARs, AncCARs had a Tm up to 35 °C higher, with half-lives up to nine times longer than the greatest previously observed. Using ancestral reconstruction we have expanded the existing CAR toolbox with three new thermostable CAR enzymes, providing access to the high temperature biosynthesis of aldehydes to drive new applications in biocatalysis.Glaxosmithkline Research & Development Lt