Abundance of the Quorum-Sensing Factor Ax21 in Four Strains of Stenotrophomonas maltophilia Correlates with Mortality Rate in a New Zebrafish Model of Infection

Stenotrophomonas maltophilia is a Gram-negative pathogen with emerging nosocomial incidence. Little is known about its pathogenesis and the genomic diversity exhibited by clinical isolates complicates the study of pathogenicity and virulence factors. Here, we present a strategy to identify such factors in new clinical isolates of S. maltophilia, incorporating an adult-zebrafish model of S. maltophilia infection to evaluate relative virulence coupled to 2D difference gel electrophoresis to explore underlying differences in protein expression. In this study we report upon three recent clinical isolates and use the collection strain ATCC13637 as a reference. The adult-zebrafish model shows discrimination capacity, i.e. from very low to very high mortality rates, with clinical symptoms very similar to those observed in natural S. maltophilia infections in fish. Strain virulence correlates with resistance to human serum, in agreement with previous studies in mouse and rat and therefore supporting zebrafish as a replacement model. Despite its clinical origin, the collection strain ATCC13637 showed obvious signs of attenuation in zebrafish, with null mortality. Multilocus-sequence-typing analysis revealed that the most virulent strains, UV74 and M30, exhibit the strongest genetic similitude. Differential proteomic analysis led to the identification of 38 proteins with significantly different abundance in the three clinical strains relative to the reference strain. Orthologs of several of these proteins have been already reported to have a role in pathogenesis, virulence or resistance mechanisms thus supporting our strategy. Proof of concept is further provided by protein Ax21, whose abundance is shown here to be directly proportional to mortality in the zebrafish infection model. Indeed, recent studies have demonstrated that this protein is a quorum-sensing-related virulence factor

African Conflicts in the Early 21st Century; Strategic Insights, v. 10, Special issue (October 2011), 99-104. Topic: Global Trends and Future Warfare ; Part III: New Actors and Belligerents

This article appeared in Strategic Insights, v.10, Special issue (October 2011), 99-104. Topic: Global Trends and Future Warfare ; Part III: New Actors and BelligerentsIn this essay we will be placing ourselves in a perspective where, out of the four possibilities outlined in the NIC's Tomorrow's Security Challenges: The Defense Implications of Emerging Global Trends report, we will consider a combination of two of the global trends presented: a rise in non-state networks and a fragmented international system. The one scenario we cannot see as relevant overall is the concert of powers, a choice it would take too long to justify within the framework of such a short paper. As for the possibility of seeing a return to great power confrontation, even though it may be a more realistic systemic possibility than the emergence of a global concern, it is hard to foresee significant great power confrontation arising in Africa. The emerging powers, particularly China, will not fight for Africa. Even if this trend occurs - and we cannot see it dominate - it will most probably create conditions similar to those of the 19th century. The Soviet Union's Vladimir Lenin was sure that an inter-imperialist war would come out of colonial competition in Africa.1 It did not, and when the great inter-imperialist war came, it came out of a European confrontation. If renewed great power rivalry were to bring about a major military confrontation in the 21st century, the trigger is much more likely to be found in the Middle Eastern or Asia than in Africa.Approved for public release; distribution is unlimited

Burundi: A manageable crisis?

Document collected by the University of Texas Libraries from the web-site of the Reseau Documentaire International Sur La Region Des Grands Lacs Africains (International Documentation Network on the Great African Lakes Region). The Reseau distributes "gray literature", non-published or limited distribution government or NGO documents regarding the Great Lakes area of central Africa including Rwanda, Burundi, and the Democratic Republic of Congo.UT Librarie

Physiological mechanisms involved in the effects of concurrent pregnancy and lactation on foetal growth and mortality in the rabbit

International audienc

Distribution and predictors of wing shape and size variability in three sister species of solitary bees

International audienceMorphological traits can be highly variable over time in a particular geographical area. Different selective pressures shape those traits, which is crucial in evolutionary biology. Among these traits, insect wing morphometry has already been widely used to describe phenotypic variability at the inter-specific level. On the contrary, fewer studies have focused on intra-specific wing morphometric variability. Yet, such investigations are relevant to study potential convergences of variation that could highlight micro-evolutionary processes. The recent sampling and sequencing of three solitary bees of the genus Melitta across their entire species range provides an excellent opportunity to jointly analyse genetic and morphometric variability. In the present study, we first aim to analyse the spatial distribution of the wing shape and centroid size (used as a proxy for body size) variability. Secondly, we aim to test different potential predictors of this variability at both the intra- and inter-population levels, which includes genetic variability, but also geographic locations and distances, elevation, annual mean temperature and precipitation. The comparison of spatial distribution of intra-population morphometric diversity does not reveal any convergent pattern between species, thus undermining the assumption of a potential local and selective adaptation at the population level. Regarding intra-specific wing shape differentiation, our results reveal that some tested predictors, such as geographic and genetic distances, are associated with a significant correlation for some species. However, none of these predictors are systematically identified for the three species as an important factor that could explain the intra-specific morphometric variability. As a conclusion, for the three solitary bee species and at the scale of this study, our results clearly tend to discard the assumption of the existence of a common pattern of intra-specific signal/structure within the intra-specific wing shape and body size variability

Right forewing of a <i>Melitta leporina</i> male specimen with the 18 landmarks selected to describe the shape.

<p>Right forewing of a <i>Melitta leporina</i> male specimen with the 18 landmarks selected to describe the shape.</p