S/T Phosphorylation of DLL1 Is Required for Full Ligand Activity In Vitro but Dispensable for DLL1 Function In Vivo during Embryonic Patterning and Marginal Zone B Cell Development

Interaction of Notch receptors with Delta- and Serrate-type ligands is an evolutionarily conserved mechanism that mediates direct communication between adjacent cells and thereby regulates multiple developmental processes. Posttranslational modifications of both receptors and ligands are pivotal for normal Notch pathway function. We have identified by mass spectrometric analysis two serine and one threonine phosphorylation sites in the intracellular domain of the mouse Notch ligand DLL1. Phosphorylation requires cell membrane association of DLL1 and occurs sequentially at the two serine residues. Phosphorylation of one serine residue most likely by protein kinase B primes phosphorylation of the other serine. A DLL1 variant, in which all three identified phosphorylated serine/threonine residues are mutated to alanine and valine, was more stable than wild-type DLL1 but had reduced relative levels on the cell surface and was more effectively cleaved in the extracellular domain. In addition, the mutant variant activated Notch1 significantly less efficient than wild-type DLL1 in a coculture assay in vitro. Mice, however, whose endogenous DLL1 was replaced with the phosphorylation-deficient triple mutant developed normally, suggesting compensatory mechanisms under physiological conditions in vivo.     

The Iranian vole Microtus irani occurs in Lebanon (Mammalia: Rodentia)

We studied 1140 bp cytochrome b sequences of social voles from three localities in Lebanon. The results were compared with published sequences representing seven species of social voles. New sequences from Lebanon clustered with reference samples of two species: M. guentheri and M. irani. While M. guentheri was already reported for Lebanon, M. irani is a new addition to the fauna of Lebanon, and the third known record for the species. Animals were collected in two localities above Tripolis at 855 m and 1430 m a.s.l., respectively.     

Insights from modeling studies on how climate change affects invasive alien species geography

Climate change and biological invasions are threatening biodiversity and ecosystem services worldwide. It has now been widely acknowledged that climate change will affect biological invasions. A large number of studies have investigated predicted shifts and other changes in the geographic ranges of invasive alien species related to climate change using modeling approaches. Yet these studies have provided contradictory evidence, and no consensus has been reached. We conducted a systematic review of 423 modeling case studies included in 71 publications that have examined the predicted effects of climate change on those species. We differentiate the approaches used in these studies and synthesize their main results. Our results reaffirm the major role of climate change as a driver of invasive alien species distribution in the future. We found biases in the literature both regarding the taxa, toward plants and invertebrates, and the areas of the planet investigated. Despite these biases, we found for the plants and vertebrates studied that climate change will more frequently contribute to a decrease in species range size than an increase in the overall area occupied. This is largely due to oceans preventing terrestrial invaders from spreading poleward. In contrast, we found that the ranges of invertebrates and pathogens studied are more likely to increase following climate change. An important caveat to these findings is that researchers have rarely considered the effects of climate change on transport, introduction success, or the resulting impacts. We recommend closing these research gaps, and propose additional avenues for future investigations, as well as opportunities and challenges for managing invasions under climate change.     

Dystrophin predominantly localizes to the transverse tubule/Z-line regions of single ventricular myocytes and exhibits distinct associations with the membrane

Dystrophin is a high molecular weight protein present at low abundance in skeletal, cardiac and smooth muscle and in trace amounts in brain. In skeletal muscle, dystrophin is uniformly distributed along the inner surface of the plasma membrane. Biochemical fractionation studies have shown that all detectable skeletal muscle dystrophin is tightly associated with a complex of wheat germ agglutinin (WGA)-binding and concanavalin A (Con A) binding sarcolemmal glycoproteins. Absence of dystrophin is the primary biochemical defect in patients with Duchenne muscular dystrophy and leads to segmental necrosis of their skeletal myofibers. Although present in similar amounts in normal cardiac and skeletal muscle, the absence of dystrophin from cardiac muscle has less severe effects on the survival of cardiac cells. We have therefore examined whether there are differences in the properties of cardiac and skeletal dystrophin. We report that in contrast to skeletal muscle, cardiac dystrophin is distributed between distinct pools: a soluble cytoplasmic pool, a membrane-bound pool not associated with WGA-binding glycoproteins and a membrane-bound pool associated with WGA-binding glycoproteins. Cardiac dystrophin was not associated with any Con A binding glycoproteins. Immunohistochemical localization studies in isolated ventricular myocytes reveal a distinct punctate staining pattern for dystrophin, approximating to the level of the transverse tubule/Z-line and contrasting with the uniform sarcolemmal staining reported for skeletal muscle fibers. The distinct properties of cardiac dystrophin suggest unique roles for this protein in cardiac versus skeletal muscle function.Abbreviations Dys Dystrophin - T-tubule Transverse tubule - SDS-PAGE Sodium Dodecyl Sulphate-Polyacrylamide Gel Electrophoresis - WGA Wheat Germ Agglutinin - Con A Concanavalin A - DHP Dihydropyridine receptor - FITC Fluorescein Isothiocyanate Conjugate - NAG N-Acetyl-D-Glucosamine - NP-40 NONIDET P-40 - PBS Phosphate-Buffered Saline - TBST Tris Buffered Saline-Tween     

Co-purification of soluble human galactosyltransferase and immunoglobulins

Preparations of human malignant effusion galactosyltransferase activity purified according to previously published techniques using enzyme-specific affinity chromatography consistently produced antibodies directed toward immunoglobulins with no detectable antigalactosyltransferase. Double immunodiffusion analysis of the antigen showed the presence of both IgG and IgA. Affinity chromatography with anti-human IgG-Sepharose and anti-human serum-Sepharose resulted in a 48,000-fold purification of galactosyltransferase activity with no detectable IgG by radioimmunoassay. Immunization of rabbits with this preparation produced antibodies directed against galactosyltransferase activity and minimal anti-Ig. The persistence of immunoglobulins during the purification of soluble galactosyltransferase activity through two enzyme-specific affinity chromatographic steps suggests an association of immunoglobulins with galactosyltransferase activity.     

Inducer exclusion by glucose 6-phosphate in Escherichia coli

The main mechanism causing catabolite repression by glucose and other carbon sources transported by the phosphotransferase system (PTS) in Escherichia coli involves dephosphorylation of enzyme IIA^Glc as a result of transport and phosphorylation of PTS carbohydrates. Dephosphorylation of enzyme IIA^Glc leads to 'inducer exclusion': inhibition of transport of a number of non-PTS carbon sources (e.g. lactose, glycerol), and reduced adenylate cyclase activity. In this paper, we show that the non-PTS carbon source glucose 6-phosphate can also cause inducer exclusion. Glucose 6-phosphate was shown to cause inhibition of transport of lactose and the non-metabolizable lactose analogue methyl-β- D -thiogalactoside (TMG). Inhibition was absent in mutants that lacked enzyme IIA^Glc or were insensitive to inducer exclusion because enzyme IIA^Glc could not bind to the lactose carrier. Furthermore, we showed that glucose 6-phosphate caused dephosphorylation of enzyme IIA^Glc. In a mutant insensitive to enzyme IIA^Glc-mediated inducer exclusion, catabolite repression by glucose 6-phosphate in lactose-induced cells was much weaker than that in the wild-type strain, showing that inducer exclusion is the most important mechanism contributing to catabolite repression in lactose-induced cells. We discuss an expanded model of enzyme IIA^Glc-mediated catabolite repression which embodies repression by non- PTS carbon sources.     

Behavioral Phenotyping of Murine Disease Models with the Integrated Behavioral Station (INBEST)

Due to rapid advances in genetic engineering, small rodents have become the preferred subjects in many disciplines of biomedical research. In studies of chronic CNS disorders, there is an increasing demand for murine models with high validity at the behavioral level. However, multiple pathogenic mechanisms and complex functional deficits often impose challenges to reliably measure and interpret behavior of chronically sick mice. Therefore, the assessment of peripheral pathology and a behavioral profile at several time points using a battery of tests are required. Video-tracking, behavioral spectroscopy, and remote acquisition of physiological measures are emerging technologies that allow for comprehensive, accurate, and unbiased behavioral analysis in a home-base-like setting. This report describes a refined phenotyping protocol, which includes a custom-made monitoring apparatus (Integrated Behavioral Station, INBEST) that focuses on prolonged measurements of basic functional outputs, such as spontaneous activity, food/water intake and motivated behavior in a relatively stress-free environment. Technical and conceptual improvements in INBEST design may further promote reproducibility and standardization of behavioral studies.     

Staphylococcus aureus Lpl protein triggers human host cell invasion via activation of Hsp90 receptor

Staphylococcus aureus is a facultative intracellular pathogen. Recently, it has been shown that the protein part of the lipoprotein‐like lipoproteins (Lpls), encoded by the lpl cluster comprising of 10 lpls paralogue genes, increases pathogenicity, delays the G2/M phase transition, and also triggers host cell invasion. Here, we show that a recombinant Lpl1 protein without the lipid moiety binds directly to the isoforms of the human heat shock proteins Hsp90α and Hsp90ß. Synthetic peptides covering the Lpl1 sequence caused a twofold to fivefold increase of S. aureus invasion in HaCaT cells. Antibodies against Hsp90 decrease S. aureus invasion in HaCaT cells and in primary human keratinocytes. Additionally, inhibition of ATPase function of Hsp90 or silencing Hsp90α expression by siRNA also decreased the S. aureus invasion in HaCaT cells. Although the Hsp90ß is constitutively expressed, the Hsp90α isoform is heat‐inducible and appears to play a major role in Lpl1 interaction. Pre‐incubation of HaCaT cells at 39°C increased both the Hsp90α expression and S. aureus invasion. Lpl1‐Hsp90 interaction induces F‐actin formation, thus, triggering an endocytosis‐like internalisation. Here, we uncovered a new host cell invasion principle on the basis of Lpl‐Hsp90 interaction.