Hapln1b, a central organizer of the ECM, modulates kit signaling to control developmental hematopoiesis in zebrafish

During early vertebrate development, hematopoietic stem and progenitor cells (HSPCs) are produced in hemogenic endothelium located in the dorsal aorta, before they migrate to a transient niche where they expand to the fetal liver and the caudal hematopoietic tissue, in mammals and zebrafish, respectively. In zebrafish, previous studies have shown that the extracellular matrix (ECM) around the aorta must be degraded to enable HSPCs to leave the aortic floor and reach blood circulation. However, the role of the ECM components in HSPC specification has never been addressed. In this study, hapln1b, a key component of the ECM, was specifically expressed in hematopoietic sites in the zebrafish embryo. Gain- and loss-of-function experiments all resulted in the absence of HSPCs in the early embryo, showing that hapln1b is necessary, at the correct level, to specify HSPCs in the hemogenic endothelium. Furthermore, the expression of hapln1b was necessary to maintain the integrity of the ECM through its link domain. By combining functional analyses and computer modeling, we showed that kitlgb interacts with the ECM to specify HSPCs. The findings show that the ECM is an integral component of the microenvironment and mediates the cytokine signaling that is necessary for HSPC specification

One-loop SYM-supergravity relation for five-point amplitudes

We derive a linear relation between the one-loop five-point amplitude of N=8 supergravity and the one-loop five-point subleading-color amplitudes of N=4 supersymmetric Yang-Mills theory.Comment: 17 pages, 2 figures; v2: very minor correction

The Complete KLT-Map Between Gravity and Gauge Theories

We present the complete map of any pair of super Yang-Mills theories to supergravity theories as dictated by the KLT relations in four dimensions. Symmetries and the full set of associated vanishing identities are derived. A graphical method is introduced which simplifies counting of states, and helps in identifying the relevant set of symmetries.Comment: 41 pages, 16 figures, published version, typos corrected, references adde

Caracterização genética de cepas de Corynebacterium pseudotuberculosis pertencentes à coleção de microrganimos patogênicos a caprinos e ovinos.

Corynebacterium pseudotuberculosis é o agente causador da Linfadenite Caseosa (LC), uma doença muito contagiosa, crônica que afeta os ovinos e os caprinos. A LC causa muito transtornos aos produtores, devido não apenas à patogenicidade da infecção bacteriana que leva a formação de abscessos em linfonodos superficiais, internos e em órgãos, como também a sua facilidade de disseminar para todo o rebanho. C. pseudotuberculosis é uma bactéria gram-positiva, que possui dois biovares, Equi e Ovis. Essa classificação é dependente da sua capacidade ou não de reduzir o nitrato em nitrito. Além disso, essa classificação distingue o tipo de hospedeiro de origem (equinos ou pequenos ruminantes) e também aponta a forma de como o patógeno sobrevive no meio ambiente. Portanto, é importante que na rotina de um laboratório, as bactérias sejam isoladas, caracterizadas e identificadas por aspectos morfológicos e bioquímicos

HIV-1 selectively targets gut-homing CCR6+CD4+ T cells via mTOR-dependent mechanisms

Gut-associated lymphoid tissues are enriched in CCR6+ Th17-polarized CD4+ T cells that contribute to HIV-1 persistence during antiretroviral therapy (ART). This raises the need for Th17-targeted immunotherapies. In an effort to identify mechanisms governing HIV-1 permissiveness/persistence in gut-homing Th17 cells, we analyzed the transcriptome of CCR6+ versus CCR6- T cells exposed to the gut-homing inducer retinoic acid (RA) and performed functional validations in colon biopsies of HIV-infected individuals receiving ART (HIV+ART). Although both CCR6+ and CCR6- T cells acquired gut-homing markers upon RA exposure, the modulation of unique sets of genes coincided with preferential HIV-1 replication in RA-treated CCR6+ T cells. This molecular signature included the upregulation of HIV-dependency factors acting at entry/postentry levels, such as the CCR5 and PI3K/Akt/mTORC1 signaling pathways. Of note, mTOR expression/phosphorylation was distinctively induced by RA in CCR6+ T cells. Consistently, mTOR inhibitors counteracted the effect of RA on HIV replication in vitro and viral reactivation in CD4+ T cells from HIV+ART individuals via postentry mechanisms independent of CCR5. Finally, CCR6+ versus CCR6- T cells infiltrating the colons of HIV+ART individuals expressed unique molecular signatures, including higher levels of CCR5, integrin β7, and mTOR phosphorylation. Together, our results identify mTOR as a druggable key regulator of HIV permissiveness in gut-homing CCR6+ T cells

Three-point correlation functions from semiclassical circular strings

The strong-coupling limit of three-point correlation functions of local operators can be analyzed beyond the supergravity regime using vertex operators representing spinning string states. When two of the vertex operators correspond to heavy string states having large quantum numbers, while the third operator corresponds to a light state with fixed charges, the correlator can be computed in the large string tension limit by means of a semiclassical approximation. We study the case when the heavy string states are circular string solutions with one AdS_5 spin and three different angular momenta along S^5, for several choices of the light string state.Comment: 13 pages. Latex. v2: Misprints corrected and references adde

3D Voronoi Tessellation for the Study of Mechanical Behavior of Rocks at Different Scales

Numerical investigation of crack damage development and microfracturing in brittle rocks is a widely studied topic, given the number of applications involved. In the framework of the Discrete Element Method (DEM) formulation, the grain-based distinct element model with random polygonal blocks can represent an alternative to the Bonded-Particle Model (BPM) based on particles. Recently, a new engine called Neper has been made available for generating 3D Voronoi grains. The aim of this study is to investigate the applicability of a Neper-based 3D Voronoi tessellation technique for the simulation of the mechanical macro response of rocks. Simulation of unconfined compression tests on synthetic specimens is conducted and a calibration procedure tested. The issue related to scale effects is also addressed, with an application to the case study of a deep geothermal reservoir