MCC, a new interacting protein for Scrib, is required for cell migration in epithelial cells

To further characterize the molecular events supporting the tumor suppressor activity of Scrib in mammals, we aim to identify new binding partners. We isolated MCC, a recently identified binding partner for β-catenin, as a new interacting protein for Scrib. MCC interacts with both Scrib and the NHERF1/NHERF2/Ezrin complex in a PDZ-dependent manner. In T47D cells, MCC and Scrib proteins colocalize at the cell membrane and reduced expression of MCC results in impaired cell migration. By contrast to Scrib, MCC inhibits cell directed migration independently of Rac1, Cdc42 and PAK activation. Altogether, these results identify MCC as a potential scaffold protein regulating cell movement and able to bind Scrib, β-catenin and NHERF1/2.

Structured summary

MINT-7211022: SCRIB (uniprotkb:Q14160) and MCC (uniprotkb:P23508) colocalize (MI:0403) by fluorescence microscopy (MI:0416)MINT-7210609: SCRIB (uniprotkb:Q14160) physically interacts (MI:0915) with MCC (uniprotkb:P23508) by two hybrid (MI:0018)MINT-7210759, MINT-7210792: SCRIB (uniprotkb:Q14160) physically interacts (MI:0914) with PIX beta (uniprotkb:Q14155) by pull down (MI:0096)MINT-7210883, MINT-7210820: SCRIB (uniprotkb:Q14160) physically interacts (MI:0914) with MCC (uniprotkb:P23508) by anti bait coimmunoprecipitation (MI:0006)MINT-7210634, MINT-7210690, MINT-7210731: SCRIB (uniprotkb:Q14160) physically interacts (MI:0914) with MCC (uniprotkb:P23508) by pull down (MI:0096)MINT-7211267: E6 (uniprotkb:P06463) physically interacts (MI:0915) with SCRIB (uniprotkb:Q14160), SNX27 (uniprotkb:Q96L92), UTRN (uniprotkb:P46939), CASK (uniprotkb:O14936), DMD (uniprotkb:P11532) and Dlg (uniprotkb:Q12959) by pull down (MI:0096)MINT-7211237: MCC (uniprotkb:P23508) physically interacts (MI:0915) with SCRIB (uniprotkb:Q14160), EZR (uniprotkb:P15311), SNX27 (uniprotkb:Q96L92), NHERF1 (uniprotkb:O14745) and NHERF2 (uniprotkb:Q15599) by pull down (MI:0096)     

Genomic island excisions in Bordetella petrii

Background  

Among the members of the genus Bordetella B. petrii is unique, since it is the only species isolated from the environment, while the pathogenic Bordetellae are obligately associated with host organisms. Another feature distinguishing B. petrii from the other sequenced Bordetellae is the presence of a large number of mobile genetic elements including several large genomic regions with typical characteristics of genomic islands collectively known as integrative and conjugative elements (ICEs). These elements mainly encode accessory metabolic factors enabling this bacterium to grow on a large repertoire of aromatic compounds.     

Melanopsin Bistability: A Fly's Eye Technology in the Human Retina

In addition to rods and cones, the human retina contains light-sensitive ganglion cells that express melanopsin, a photopigment with signal transduction mechanisms similar to that of invertebrate rhabdomeric photopigments (IRP). Like fly rhodopsins, melanopsin acts as a dual-state photosensitive flip-flop in which light drives both phototransduction responses and chromophore photoregeneration that bestows independence from the retinoid cycle required by rods and cones to regenerate photoresponsiveness following bleaching by light. To explore the hypothesis that melanopsin in humans expresses the properties of a bistable photopigment in vivo we used the pupillary light reflex (PLR) as a tool but with methods designed to study invertebrate photoreceptors. We show that the pupil only attains a fully stabilized state of constriction after several minutes of light exposure, a feature that is consistent with typical IRP photoequilibrium spectra. We further demonstrate that previous exposure to long wavelength light increases, while short wavelength light decreases the amplitude of pupil constriction, a fundamental property of IRP difference spectra. Modelling these responses to invertebrate photopigment templates yields two putative spectra for the underlying R and M photopigment states with peaks at 481 nm and 587 nm respectively. Furthermore, this bistable mechanism may confer a novel form of “photic memory” since information of prior light conditions is retained and shapes subsequent responses to light. These results suggest that the human retina exploits fly-like photoreceptive mechanisms that are potentially important for the modulation of non-visual responses to light and highlights the ubiquitous nature of photoswitchable photosensors across living organisms.     

A Modeling Framework to Describe the Transmission of Bluetongue Virus within and between Farms in Great Britain

Background

Recently much attention has been given to developing national-scale micro-simulation models for livestock diseases that can be used to predict spread and assess the impact of control measures. The focus of these models has been on directly transmitted infections with little attention given to vector-borne diseases such as bluetongue, a viral disease of ruminants transmitted by Culicoides biting midges. Yet BT has emerged over the past decade as one of the most important diseases of livestock.

Methodology/Principal Findings

We developed a stochastic, spatially-explicit, farm-level model to describe the spread of bluetongue virus (BTV) within and between farms. Transmission between farms was modeled by a generic kernel, which includes both animal and vector movements. Once a farm acquired infection, the within-farm dynamics were simulated based on the number of cattle and sheep kept on the farm and on local temperatures. Parameter estimates were derived from the published literature and using data from the outbreak of bluetongue in northern Europe in 2006. The model was validated using data on the spread of BTV in Great Britain during 2007. The sensitivity of model predictions to the shape of the transmission kernel was assessed.

Conclusions/Significance

The model is able to replicate the dynamics of BTV in Great Britain. Although uncertainty remains over the precise shape of the transmission kernel and certain aspects of the vector, the modeling approach we develop constitutes an ideal framework in which to incorporate these aspects as more and better data become available. Moreover, the model provides a tool with which to examine scenarios for the spread and control of BTV in Great Britain.     

Functional habitat area as a reliable proxy for population size: case study using two butterfly species of conservation concern

Accurate estimates of population size are essential for effective conservation and restoration management of threatened species. Nevertheless, reliable methods to estimate population size, such as mark-release-recapture studies (MRR), are time and labour consuming and may generate negative impact(s) on both the habitats and organisms studied. This may complicate their use if several sites need to be studied concurrently. Consequently, there is a strong interest to develop reliable proxies of population size, e.g., to be used in Population Viability Analysis. Habitat area has often been used as an obvious proxy. For butterflies, many studies focused on the area of host plant patches, but resource-based definition of the habitat (i.e., the area containing the different ecological resources and conditions needed by the individuals) has recently gained much attention. Using two peat bog butterflies, we tested the reliability of these two measures of habitat area as proxies for population size by (1) predicting population sizes based on the product of larval habitat area by the number of emerged butterflies per spatial unit of habitat (eliminated by ground cover traps) and (2) comparing these predictions to accurate population size estimates inferred from MRR studies. Results on both species showed that: (1) adult population size was strongly related to larval habitat availability and quality when habitat was accurately defined according to functional resources, (2) resources other than the host plant have to be included in the habitat definition, (3) after careful control of its similarity, the resource-based habitat delineation can be reasonably well transferred among populations of the same species in a wider region.     

Analysis of the cytosolic domains of the hepatitis B virus envelope proteins for their function in viral particle assembly and infectivity

The hepatitis B virus (HBV) envelope proteins have the ability to assemble three types of viral particles, (i) the empty subviral particles (SVPs), (ii) the mature HBV virions, and (iii) the hepatitis delta virus (HDV) particles, in cells that are coinfected with HBV and HDV. To gain insight into the function of the HBV envelope proteins in morphogenesis of HBV or HDV virions, we have investigated subdomains of the envelope proteins that have been shown or predicted to lie at the cytosolic face of the endoplasmic reticulum membrane during synthesis, a position prone to interaction with the inner core structure. These domains, referred to here as cytosolic loops I and II (CYL-I and -II, respectively), were subjected to mutagenesis. The mutations were introduced in the three HBV envelope proteins, designated small, middle, and large (S-HBsAg, M-HBsAg, and L-HBsAg, respectively). The mutants were expressed in HuH-7 cells to evaluate their capacity for self-assembly and formation of HBV or HDV virions when HBV nucleocapsid or HDV ribonucleoprotein, respectively, was provided. We found that SVP-competent CYL-I mutations between positions 23 and 78 of the S domain were permissive to HBV or HDV virion assembly. One mutation (P29A) was permissive for synthesis of the S- and M-HBsAg but adversely affected the synthesis or stability of L-HBsAg, thereby preventing the assembly of HBV virions. Furthermore, using an in vitro infection assay based on the HepaRG cells and the HDV model, we have shown that particles coated with envelope proteins bearing CYL-I mutations were fully infectious, hence indicating the absence of an infectivity determinant in this region. Finally, we demonstrated that the tryptophan residues at positions 196, 199, and 201 in CYL-II, which were shown to exert a matrix function for assembly of HDV particles (I. Komla-Soukha and C. Sureau, J. Virol. 80:4648-4655, 2006), were dispensable for both assembly and infectivity of HBV virions.     

Molecular level probing of preferential hydration and its modulation by osmolytes through the use of pyranine complexed to hemoglobin

Two spectroscopic probes are used to expose molecular level changes in hydration shell water interactions that directly relate to such issues as preferential hydration and protein stability. The major focus of the present study is on the use of pyranine (HPT) fluorescence to probe as a function of added osmolytes (PEG, urea, trehalose, and magnesium), the extent to which glycerol is preferentially excluded from the hydration shell of free HPT and HPT localized in the diphosphoglycerate (DPG) binding site of hemoglobin in both solution and in Sol-Gel matrices. The pyranine study is complemented by the use of vibronic side band luminescence from the gadolinium cation that directly exposes the changes in hydrogen bonding between first and second shell waters as a function of added osmolytes. Together the results form the basis for a water partitioning model that can account for both preferential hydration and water/osmolyte-mediated conformational changes in protein structure.     

French Experience of 2009 A/H1N1v Influenza in Pregnant Women

Background

The first reports on the pandemic influenza 2009 A/H1N1v from the USA, Mexico, and Australia indicated that this disease was associated with a high mortality in pregnant women. The aim of this study was to describe and compare the characteristics of severe critically ill and non-severe pregnant women with 2009 A/H1N1v-related illness in France.

Methodology/Principal Findings

A national registry was created to screen pregnant women with laboratory-confirmed 2009 A/H1N1v influenza. Three hundred and fifteen patients from 46 French hospitals were included: 40 patients were admitted to intensive care units (severe outcomes), 111 were hospitalized in obstetric or medical wards (moderate outcomes), and 164 were outpatients (mild outcomes). The 2009 A/H1N1v influenza illness occurred during all pregnancy trimesters, but most women (54%), notably the severe patients (70%), were in the third trimester. Among the severe patients, twenty (50%) underwent mechanical ventilation, and eleven (28%) were treated with extracorporeal membrane oxygenation. Three women died from A/H1N1v influenza. We found a strong association between the development of a severe outcome and both co-existing illnesses (adjusted odds ratio [OR], 5.1; 95% confidence interval [CI], 2.2–11.8) and a delay in oseltamivir treatment after the onset of symptoms (>3 or 5 days) (adjusted OR, 4.8; 95% CI, 1.9–12.1 and 61.2, 95% CI; 14.4–261.3, respectively). Among the 140 deliveries after 22 weeks of gestation known to date, 19 neonates (14%) were admitted to a neonatal intensive care unit, mainly for preterm delivery, and two neonates died. None of these neonates developed 2009 A/H1N1v infection.

Conclusions

This series confirms the high incidence of complications in pregnant women infected with pandemic A/H1N1v observed in other countries but depicts a lower overall maternal and neonatal mortality and morbidity than indicated in the USA or Australia. Moreover, our data demonstrate the benefit of early oseltamivir treatment in this specific population.     

LppM impact on the colonization of macrophages by Mycobacterium tuberculosis

Mycobacterium tuberculosis produces several bacterial effectors impacting the colonization of phagocytes. Here, we report that the putative lipoprotein LppM hinders phagocytosis by macrophages in a toll‐like receptor 2‐dependent manner. Moreover, recombinant LppM is able to functionally complement the phenotype of the mutant, when exogenously added during macrophage infection. LppM is also implicated in the phagosomal maturation, as a lppM deletion mutant is more easily addressed towards the acidified compartments of the macrophage than its isogenic parental strain. In addition, this mutant was affected in its ability to induce the secretion of pro‐inflammatory chemokines, interferon‐gamma‐inducible protein‐10, monocyte chemoattractant protein‐1 and macrophage inflammatory protein‐1α. Thus, our results describe a new mycobacterial protein involved in the early trafficking of the tubercle bacillus and its manipulation of the host immune response.