Draft Genome Sequences of Four Aeromonas salmonicida subsp. achromogenes Strains, 23051, 23053, 23055, and 23056, Isolated from Senegalese Sole ( Solea senegalensis )

International audienceThe bacterial species Aeromonas salmonicida officially has five subspecies. A large majority of the currently available sequences come from Aeromonas salmonicida subsp. salmonicida, which causes furunculosis in salmonids. We present the genomic sequences of four Aeromonas salmonicida subsp. achromogenes strains. This will help increase the robustness of genomic analyses for this subspecies

The topographic connectome

Central to macro-connectomics and much of systems neuroscience is the idea that we can summarise macroscopic brain connectivity using a network of ‘nodes’ and ‘edges’ — functionally distinct brain regions and the connections between them. This is an approach that allows a deep understanding of brain dynamics and how they relate to brain circuitry. This approach, however, ignores key features of anatomical connections, such as spatial arrangement and topographic mappings. In this article, we suggest an alternative to this paradigm. We propose that connection topographies can inform us about brain networks in ways that are complementary to the concepts of ‘nodes’ and ‘edges’. We also show that current neuroimaging technology is capable of revealing details of connection topographies in vivo. These advances, we hope, will allow us to explore brain connectivity in novel ways in the immediate future

Evaluating the efficiency and effectiveness of environmental policies for global and local air pollutants

Unregulated global and local air pollutants impose high costs on society. For more than half a century, economists have argued that the introduction of market instruments such as pollution taxes or cap-and-trade markets can cut aggregate emissions at the lowest cost. Market instruments have been implemented by some countries to reduce local pollutants, such as nitrogen oxides, and global pollutants, such as greenhouse gas (GHG) emissions. One problem with this context is the lack of evidence on the cost savings of market-based policies relative to other policies. Particularly for global pollutants, a second problem with the patchwork of policies is carbon leakage, where emission reductions from regulated countries are offset by emission increases in unregulated countries. This dissertation seeks to explore these two problems. The first chapter, Do environmental markets improve allocative efficiency? Evidence from U.S. air pollution, develops a framework to test the allocative efficiency changes of introducing cap-and-trade markets. The framework is applied to landmark U.S. air pollution markets using manufacturing data. The chapter finds evidence of allocative efficiency gains for some markets. The second chapter, Carbon pricing and competitiveness pressures: The case of cement trade, provides empirical evidence of decreased net exports of a carbon-intensive product, cement, in British Columbia, Canada following the introduction of their carbon tax. The third chapter, Do carbon tariffs reduce carbon leakage? Evidence from trade tariffs, combines theory and data to study the effects of proposed carbon tariffs that price the carbon content of imports on foreign GHG emission changes. The chapter finds evidence of reduced GHG emissions from targeted industries and an unintended emission offset effect from downstream industries. Together, these chapters provide evidence on the efficiency and effectiveness of policies promoted to mitigate harmful air pollutants

Finance and green growth: A comment on De Haas and Popov (2023)

De Haas and Popov (2023) estimate the effect of country-level financial sector size and structure on decarbonization to show that countries with relatively more equity versus debt financing have more emission-efficient economies. We uncover multiple coding errors that change the magnitude and the precision of the coefficients of interest. These coding errors include misreporting of standard errors, and misspecifying generalized method of moments (GMM) estimators. We further provide robustness tests of the results to (1) restricting the sample to consistent sets of countries across the country and country-byindustry samples, and (2) using a limited information maximum likelihood (LIML) estimator to address a weak-instrument problem. We find that the results from the robustness checks are qualitatively different from the original results but similar to the corrected results

Extracting functionally feed forward networks from a population of spiking neurons

Neuronal avalanches are a ubiquitous form of activity characterized by spontaneous bursts whose size distribution follows a power-law. Recent theoretical models have replicated power-law avalanches by assuming the presence of functionally feedforward connections (FFCs) in the underlying dynamics of the system. Accordingly, avalanches are generated by a feedforward chain of activation that persists despite being embedded in a larger, massively recurrent circuit. However, it is unclear to what extent networks of living neurons that exhibit power-law avalanches rely on FFCs. Here, we employed a computational approach to reconstruct the functional connectivity of cultured cortical neurons plated on multielectrode arrays, and investigated whether pharmacologically-induced alterations in avalanche dynamics are accompanied by changes in FFCs. This approach begins by extracting a functional network of directed links between pairs of neurons, and then evaluates the strength of FFCs using Schur decomposition. In a first step, we examined the ability of this approach to extract FFCs from simulated spiking neurons. The strength of FFCs obtained in strictly feedforward networks diminished monotonically as links were gradually rewired at random. Next, we estimated the FFCs of spontaneously active cortical neuron cultures in the presence of either a control medium, a GABAA receptor antagonist (PTX), or an AMPA receptor antagonist combined with an NMDA receptor antagonist (APV/DNQX). The distribution of avalanche sizes in these cultures was modulated by this pharmacology, with a shallower power-law under PTX (due to the prominence of larger avalanches) and a steeper power-law under APV/DNQX (due to avalanches recruiting fewer neurons) relative to control cultures. The strength of FFCs increased in networks after application of PTX, consistent with an amplification of feed forward activity during avalanches. Conversely, FFCs decreased after application of APV/DNQX, consistent with fading feed forward activation. The observed alterations in FFCs provide experimental support for recent theoretical work linking power-law avalanches to the feed forward organization of functional connections in local neuronal circuits. \ua9 2012 Vincent, Tauskela and Thivierge.Peer reviewed: YesNRC publication: Ye

Altered network communication following a neuroprotective drug treatment

Preconditioning is defined as a range of stimuli that allow cells to withstand subsequent anaerobic and other deleterious conditions. While cell protection under preconditioning is well established, this paper investigates the influence of neuroprotective preconditioning drugs, 4-aminopyridine and bicuculline (4-AP/bic), on synaptic communication across a broad network of in vitro rat cortical neurons. Using a permutation test, we evaluated cross-correlations of extracellular spiking activity across all pairs of recording electrodes on a 64-channel multielectrode array. The resulting functional connectivity maps were analyzed in terms of their graph-theoretic properties. A small-world effect was found, characterized by a functional network with high clustering coefficient and short average path length. Twenty-four hours after exposure to 4-AP/bic, small-world properties were comparable to control cultures that were not treated with the drug. Four hours following drug washout, however, the density of functional connections increased, while path length decreased and clustering coefficient increased. These alterations in functional connectivity were maintained at four days post-washout, suggesting that 4-AP/bic preconditioning leads to long-term effects on functional networks of cortical neurons. Because of their influence on communication efficiency in neuronal networks, alterations in small-world properties hold implications for information processing in brain systems. The observed relationship between density, path length, and clustering coefficient is captured by a phenomenological model where connections are added randomly within a spatially-embedded network. Taken together, results provide information regarding functional consequences of drug therapies that are overlooked in traditional viability studies and present the first investigation of functional networks under neuroprotective preconditioning. \ua9 2013 Vincent et al.Peer reviewed: YesNRC publication: Ye