Identification and Characterization of the RLIP/RALBP1 Interacting Protein Xreps1 in Xenopus laevis Early Development

Background: The FGF/Ras/Ral/RLIP pathway is required for the gastrulation process during the early development of vertebrates. The Ral Interacting Protein (RLIP also known as RalBP1) interacts with GTP-bound Ral proteins. RLIP/RalBP1 is a modular protein capable of participating in many cellular functions. Methodology/Principal Findings: To investigate the role of RLIP in early development, a two-hybrid screening using a library of maternal cDNAs of the amphibian Xenopus laevis was performed. Xreps1 was isolated as a partner of RLIP/RalBP1 and its function was studied. The mutual interacting domains of Xreps1 and Xenopus RLIP (XRLIP) were identified. Xreps1 expressed in vivo, or synthesized in vitro, interacts with in vitro expressed XRLIP. Interestingly, targeting of Xreps1 or the Xreps1-binding domain of XRLIP (XRLIP(469–636)) to the plasma membrane through their fusion to the CAAX sequence induces a hyperpigmentation phenotype of the embryo. This hyperpigmented phenotype induced by XRLIP(469–636)-CAAX can be rescued by co-expression of a deletion mutant of Xreps1 restricted to the RLIP-binding domain (Xreps1(RLIP-BD)) but not by co-expression of a cDNA coding for a longer form of Xreps1. Conclusion/Significance: We demonstrate here that RLIP/RalBP1, an effector of Ral involved in receptor-mediated endocytosis and in the regulation of actin dynamics during embryonic development, also interacts with Reps1. Although these two proteins are present early during embryonic development, they are active only at the end of gastrulation. Ou

Appropriateness and valuation of traditional cheeses exposed to different innovations – a study in France and Norway

International audienc

Co-ordinated Functions of WASH and Exocyst Complex Underlie the Biogenesis of Invadopodia in Metastatic Breast Tumor Cells

The trade-mark of a metastatic tumor cell is its ability to disseminate from the primary tumor by degrading the extracellular matrix and basement membranes that form a barrier around the tissue. Remodelling of the extracellular matrix by metastatic cells requires formation of actinbased protrusions of the plasma membrane called invadopodia, where the trans-membrane matrix metalloproteinase MT1-MMP accumulates. How the cell coordinates targeting of MT1- MMP with actin assembly to form a functional invadopodium remains unclear. Here, we describe an interaction between the exocyst complex and the endosomal Arp2/3 activator WASH on MT1-MMP-containing late endosomes in MDA-MB-231 human breast adenocarcinoma cells. Exocyst and WASH regulate actin assembly on MT1-MMP-containing endosomes to control their dynamics. Both protein complexes are required for invadopodia formation and matrix degradation by a mechanism that involves transient tubular connections between the endosomes and the plasma membrane, which ensure focal delivery of MT1-MMP. These connections are accompanied by recruitment of another Arp2/3 activator, N-WASP, to mature invadopodia and loss of WASH. These findings imply a new definition of invadopodia as structures where late endosomes fuse transiently with the plasma membrane to promote actin assembly and deliver the matrix metalloproteinase to focal sites of matrix degradation

Partitioning of chromium (VI) and chromium (III) between dissolved and colloidal forms in a stream and reservoir contaminated with tannery waste water

Environmental fate of chromium rejected from tannery wastewater to the Dunajec River (southern Poland) was investigated using separation with tangential flow filtration followed by measurements with Cathodic Adsorptive Stripping Voltammetry (CAdSV) and ICP-MS. Virtually all Cr(VI) was found in the dissolved fraction ($<$1 kDa). Thus form was present at low concentrations. Cr(III) was rapidly transferred from dissolved and low molecular weight colloidal fractions to particles and high molecular weight colloids and thus scavenged from the water column of the Czorsztyn Reservoir to the sediments. The possibility of Cr remobilization via oxidation of Cr(III) in the presence of freshly precipitated Mn-oxides in water or at the water-sediment interface needs further investigation.