Lactobacillus casei BL23 Produces Microvesicles Carrying Proteins That Have Been Associated with Its Probiotic Effect

Archaea, bacteria, and eukarya secrete membrane microvesicles (MVs) as a mechanism for intercellular communication. We report the isolation and characterization of MVs from the probiotic strain Lactobacillus casei BL23. MVs were characterized using analytical high performance techniques, DLS, AFM and TEM. Similar to what has been described for other Gram-positive bacteria, MVs were on the nanometric size range (30–50 nm). MVs carried cytoplasmic components such as DNA, RNA and proteins. Using a proteomic approach (LC-MS), we identified a total of 103 proteins; 13 exclusively present in the MVs. The MVs content included cell envelope associated and secretory proteins, heat and cold shock proteins, several metabolic enzymes, proteases, structural components of the ribosome, membrane transporters, cell wall-associated hydrolases and phage related proteins. In particular, we identified proteins described as mediators of Lactobacillus’ probiotic effects such as p40, p75 and the product of LCABL_31160, annotated as an adhesion protein. The presence of these proteins suggests a role for the MVs in the bacteria-gastrointestinal cells interface. The expression and further encapsulation of proteins into MVs of GRAS (Generally Recognized as Safe) bacteria could represent a scientific novelty, with applications in food, nutraceuticals and clinical therapies

Implications of a High-Mass Diphoton Resonance for Heavy Quark Searches

Heavy vector-like quarks coupled to a scalar $S$ will induce a coupling of this scalar to gluons and possibly (if electrically charged) photons. The decay of the heavy quark into $Sq$, with $q$ being a Standard Model quark, provides, if kinematically allowed, new channels for heavy quark searches. Inspired by naturalness considerations, we consider the case of a vector-like partner of the top quark. For illustration, we show that a singlet partner can be searched for at the 13$\,$TeV LHC through its decay into a scalar resonance in the $2\gamma+\ell + X$ final states, especially if the diphoton branching ratio of the scalar $S$ is further enhanced by the contribution of non coloured particles. We then show that conventional heavy quark searches are also sensitive to this new decay mode, when $S$ decays hadronically, by slightly tightening the current selection cuts. Finally, we comment about the possibility of disentangling, by scrutinising appropriate kinematic distributions, heavy quark decays to $St$ from other standard decay modes.Comment: 8 pages, 3 figures and 1 table; v3: typos fixed. Matches published versio

The cytosolic invertase NI6 affects vegetative growth, flowering, fruit set, and yield in tomato

Sucrose metabolism is important for most plants, both as the main source of carbon and via signaling mechanisms that have been proposed for this molecule. A cleaving enzyme, invertase (INV) channels sucrose into sink metabolism. Although acid soluble and insoluble invertases have been largely investigated, studies on the role of neutral invertases (A/N-INV) have lagged behind. Here, we identified a tomato A/N-INV encoding gene (NI6) co-localizing with a previously reported quantitative trait locus (QTL) largely affecting primary carbon metabolism in tomato. Of the eight A/N-INV genes identified in the tomato genome, NI6 mRNA is present in all organs, but its expression was higher in sink tissues (mainly roots and fruits). A NI6-GFP fusion protein localized to the cytosol of mesophyll cells. Tomato NI6-silenced plants showed impaired growth phenotype, delayed flowering and a dramatic reduction in fruit set. Global gene expression and metabolite profile analyses of these plants revealed that NI6 is not only essential for sugar metabolism, but also plays a signaling role in stress adaptation. We also identified major hubs, whose expression patterns were greatly affected by NI6 silencing; these hubs were within the signaling cascade that coordinates carbohydrate metabolism with growth and development in tomato

Regulation of a remote Shh forebrain enhancer by the Six3 homeoprotein.

International audienceIn humans, SHH haploinsufficiency results in holoprosencephaly (HPE), a defect in anterior midline formation. Despite the importance of maintaining SHH transcript levels above a critical threshold, we know little about the upstream regulators of SHH expression in the forebrain. Here we describe a rare nucleotide variant located 460 kb upstream of SHH in an individual with HPE that resulted in the loss of Shh brain enhancer-2 (SBE2) activity in the hypothalamus of transgenic mouse embryos. Using a DNA affinity-capture assay, we screened the SBE2 sequence for DNA-binding proteins and identified members of the Six3 and Six6 homeodomain family as candidate regulators of Shh transcription. Six3 showed reduced binding affinity for the mutant compared to the wild-type SBE2 sequence. Moreover, Six3 with HPE-causing alterations failed to bind and activate SBE2. These data suggest a direct link between Six3 and Shh regulation during normal forebrain development and in the pathogenesis of HPE