Nitrogen deprivation induces triacylglycerol accumulation, drug tolerance and hypervirulence in mycobacteria.

Mycobacteria share with other actinomycetes the ability to produce large quantities of triacylglycerol (TAG), which accumulate as intracytoplasmic lipid inclusions (ILI) also known as lipid droplets (LD). Mycobacterium tuberculosis (M. tb), the etiologic agent of tuberculosis, acquires fatty acids from the human host which are utilized to synthesize TAG, subsequently stored in the form of ILI to meet the carbon and nutrient requirements of the bacterium during long periods of persistence. However, environmental factors governing mycobacterial ILI formation and degradation remain poorly understood. Herein, we demonstrated that in the absence of host cells, carbon excess and nitrogen starvation promote TAG accumulation in the form of ILI in M. smegmatis and M. abscessus, used as surrogate species of M. tb. Based on these findings, we developed a simple and reversible in vitro model to regulate ILI biosynthesis and hydrolysis in mycobacteria. We also showed that TAG formation is tgs1 dependent and that lipolytic enzymes mediate TAG breakdown. Moreover, we confirmed that the nitrogen-deprived and ILI-rich phenotype was associated with an increased tolerance towards several drugs used for treating mycobacterial infections. Importantly, we showed that the presence of ILI substantially enhanced the bacterial burden and granuloma abundance in zebrafish embryos infected with lipid-rich M. abscessus as compared to embryos infected with lipid-poor M. abscessus, suggesting that ILI are actively contributing to mycobacterial virulence and pathogenesis

The physical determinants of the thickness of lamellar polymer crystals

Based upon kinetic Monte Carlo simulations of crystallization in a simple polymer model we present a new picture of the mechanism by which the thickness of lamellar polymer crystals is constrained to a value close to the minimum thermodynamically stable thickness. This description contrasts with those given by the two dominant theoretical approaches.Comment: 4 pages, 4 figures, revte

The Marketing Firm: Retailer and consumer contingencies

acceptedVersionpublishedVersio

Candidate Isolated Neutron Stars and Other Optically Blank X-ray Fields Identified from the ROSAT All-Sky and Sloan Digital Sky Surveys

Only seven radio-quiet isolated neutron stars (INSs) emitting thermal X rays are known, a sample that has yet to definitively address such fundamental issues as the equation of state of degenerate neutron matter. We describe a selection algorithm based on a cross-correlation of the ROSAT All-Sky Survey (RASS) and the Sloan Digital Sky Survey (SDSS) that identifies X-ray error circles devoid of plausible optical counterparts to the SDSS g~22 magnitudes limit. We quantitatively characterize these error circles as optically blank; they may host INSs or other similarly exotic X-ray sources such as radio-quiet BL Lacs, obscured AGN, etc. Our search is an order of magnitude more selective than previous searches for optically blank RASS error circles, and excludes the 99.9% of error circles that contain more common X-ray-emitting subclasses. We find 11 candidates, nine of which are new. While our search is designed to find the best INS candidates and not to produce a complete list of INSs in the RASS, it is reassuring that our number of candidates is consistent with predictions from INS population models. Further X-ray observations will obtain pinpoint positions and determine whether these sources are entirely optically blank at g~22, supporting the presence of likely isolated neutron stars and perhaps enabling detailed follow-up studies of neutron star physics.Comment: Accepted for publication in the AJ; higher resolution figures available at http://www.astro.washington.edu/agueros/pub

Beyond the public and private divide: Remapping transnational climate governance in de 21th century

This article provides a first step towards a better theoretical and empirical knowledge of the emerging arena of transnational climate governance. The need for such a re-conceptualization emerges from the increasing relevance of non-state and transnational approaches towards climate change mitigation at a time when the intergovernmental negotiation process has to overcome substantial stalemate and the international arena becomes increasingly fragmented. Based on a brief discussion of the increasing trend towards transnationalization and functional segmentation of the global climate governance arena, we argue that a remapping of climate governance is necessary and needs to take into account different spheres of authority beyond the public and international. Hence, we provide a brief analysis of how the public/private divide has been conceptualized in Political Science and International Relations. Subsequently, we analyse the emerging transnational climate governance arena. Analytically, we distinguish between different manifestations of transnational climate governance on a continuum ranging from delegated and shared public-private authority to fully non-state and private responses to the climate problem. We suggest that our remapping exercise presented in this article can be a useful starting point for future research on the role and relevance of transnational approaches to the global climate crisis

Model theory of finite and pseudofinite groups

This is a survey, intended both for group theorists and model theorists, concerning the structure of pseudofinite groups, that is, infinite models of the first-order theory of finite groups. The focus is on concepts from stability theory and generalisations in the context of pseudofinite groups, and on the information this might provide for finite group theory

The Dynamic Landscape of Novel Psychoactive Substance (NPS) Use in Ireland: Results from an Expert Consultation

In Ireland, legislators encountered a new phenomenon in 2005 onwards with the advent of ‘legal highs’ sold in headshops. Use of ‘legal highs’ containing herbal and synthetic new psychoactive substances (NPS) was not confined to problematic drug users, and included social recreational users. Legislative controls were enacted in 2010, 2011 and 2015. The study aimed to investigate expert perspectives on the NPS situation with regard to changing and emergent trends in use, health and social consequences and service implications. This brief report presents descriptive findings from a national consultation using a structured guide with experts in 2016. Four themes emerged and centred on; ‘Definitions of NPS used within Professional Roles’; ‘Professional Experiences of NPS‘; ‘Types of NPS Users, Sourcing and Consequences of Use’; and ‘Service Response.’ Findings underscored the mental health and addiction related consequences of NPS use, with prevention, clinical and treatment services ill- equipped to deal with the particular characteristics of this form of drug abuse. Enhanced strategies, services and clinical responses are warranted to address the challenges encountered. © 2016 Springer Science+Business Media New Yor