Persistent infection with primate foamy virus type 1 increases human immunodeficiency virus type 1 cell binding via a Bet-independent mechanism

We report that human T cells persistently infected with primate foamy virus type 1 (PFV-1) display an increased capacity to bind human immunodeficiency virus type 1 (HIV-1), resulting in increased cell permissiveness to HIV-1 infection and enhanced cell-to-cell virus transmission. This phenomenon is independent of HIV-1 receptor, CD4, and it is not related to PFV-1 Bet protein expression. Increased virus attachment is specifically inhibited by heparin, indicating that it should be mediated by interactions with heparan sulfate glycosaminoglycans expressed on the target cells. Given that both viruses infect similar animal species, the issue of whether coinfection with primate foamy viruses interferes with the natural course of lentivirus infections in nonhuman primates should be considered.     

A role for auxin redistribution in the responses of the root system architecture to phosphate starvation in Arabidopsis

The changes in root system architecture (RSA) triggered by phosphate (P) deprivation were studied in Arabidopsis (Arabidopsis thaliana) plants grown for 14 d on 1 mM or 3 microM P. Two different temporal phases were observed in the response of RSA to low P. First, lateral root (LR) development was promoted between days 7 and 11 after germination, but, after day 11, all root growth parameters were negatively affected, leading to a general reduction of primary root (PR) and LR lengths and of LR density. Low P availability had contrasting effects on various stages of LR development, with a marked inhibition of primordia initiation but a strong stimulation of activation of the initiated primordia. The involvement of auxin signaling in these morphological changes was investigated in wild-type plants treated with indole-3-acetic acid or 2,3,5-triiodobenzoic acid and in axr4-1, aux1-7, and eir1-1 mutants. Most effects of low P on RSA were dramatically modified in the mutants or hormone-treated wild-type plants. This shows that auxin plays a major role in the P starvation-induced changes of root development. From these data, we hypothesize that several aspects of the RSA response to low P are triggered by local modifications of auxin concentration. A model is proposed that postulates that P starvation results in (1) an overaccumulation of auxin in the apex of the PR and in young LRs, (2) an overaccumulation of auxin or a change in sensitivity to auxin in the lateral primordia, and (3) a decrease in auxin concentration in the lateral primordia initiation zone of the PR and in old laterals. Measurements of local changes in auxin concentrations induced by low P, either by direct quantification or by biosensor expression pattern (DR5::beta-glucuronidase reporter gene), are in line with these hypotheses. Furthermore, the observation that low P availability mimicked the action of auxin in promoting LR development in the alf3 mutant confirmed that P starvation stimulates primordia emergence through increased accumulation of auxin or change in sensitivity to auxin in the primordia. Both the strong effect of 2,3,5-triiodobenzoic acid and the phenotype of the auxin-transport mutants (aux1, eir1) suggest that low P availability modifies local auxin concentrations within the root system through changes in auxin transport rather than auxin synthesis.     

ATR/TEM8 is highly expressed in epithelial cells lining Bacillus anthracis' three sites of entry: implications for the pathogenesis of anthrax infection

Anthrax is a disease caused by infection with spores from the bacteria Bacillus anthracis. These spores enter the body, where they germinate into bacteria and secrete a tripartite toxin that causes local edema and, in systemic infections, death. Recent studies identified the cellular receptor for anthrax toxin (ATR), a type I membrane protein. ATR is one of the splice variants of the tumor endothelial marker 8 (TEM8) gene. ATR and TEM8 are identical throughout their extracellular and transmembrane sequence, and both proteins function as receptors for the toxin. ATR/TEM8 function and expression have been associated with development of the vascular system and with tumor angiogenesis. TEM8 is selectively upregulated in endothelial cells during blood vessel formation and tumorigenesis. However, selective expression of TEM8 in endothelial cells contradicts the presumably ubiquitous expression of the receptor. To resolve this controversial issue, we evaluated the distribution of ATR/TEM8 in a variety of tissues. For this purpose, we generated and characterized a novel anti-ATR/TEM8 polyclonal antibody. Here, we show that this novel antibody recognizes all three ATR/TEM8 isoforms, which are widely and differentially expressed in various tissue types. We found that ATR/TEM8 expression is not only associated with tumor endothelial cells, as previously described. Indeed, ATR/TEM8 is highly and selectively expressed in the epithelial cells lining those organs that constitute the anthrax toxin's sites of entry, i.e., the lung, the skin, and the intestine. In fact, we show that ATR/TEM8 is highly expressed in the respiratory epithelium of the bronchi of the lung and is particularly abundant in the ciliated epithelial cells coating the bronchi. Furthermore, immunostaining of skin biopsies revealed that ATR/TEM8 is highly expressed in the keratinocytes of the epidermis. Finally, we show that the epithelial cells lining the small intestine strongly express ATR/TEM8 isoforms. This is the first demonstration that the ATR/TEM8 protein is highly expressed in epithelial cells, which represent the primary location for bacterial invasion. These results suggest that the ATR/TEM8 expression pattern that we describe here is highly relevant for understanding the pathogenesis of anthrax infection. anthrax; epithelia; lung; skin; intestine; toxin entry; receptor; bacterial pathogenesis     

Purification and some properties of a carboxypeptidase B from dogfish Scyliorhinus canicula

A carboxypeptidase B (CPB) has been purified from dogfish (Scyliorhinus canicula) pancreas and partially characterized. The purification procedure included acetone precipitation, ion-exchange chromatography on a CM-cellulose column and gel filtration on Sephadex G-75. The purified enzyme migrates as a single band both on PAGE and SDS-PAGE. Its molecular mass is estimated to be about 32 kDa. The optimum of activity is obtained at pH 7.5–8.2. The enzyme is inhibited by typical metal-chelating agents (EDTA and o-phenanthroline) and by Hg²⁺. It is activated by Co²⁺, l-cysteine and by heat treatment at 40° and 50°C. Kinetic parameters, K_m and k_cat, of native enzyme, Co²⁺-activated CPB and heat-treated CPB have been determined     

Development of Molecular Tools for Characterization and Genetic Diversity Analysis in Tunisian Fig (Ficus carica) Cultivars

Fig, Ficus carica L., is a useful genetic resource for commercial cultivation. In this study, RAPD (60), ISSR (48), RAMPO (63), and SSR (34) markers were compared to detect polymorphism and to establish genetic relationships among Tunisian fig tree cultivars. The statistical procedures conducted on the combined data show considerable genetic diversity, and the tested markers discriminated all fig genotypes studied. The identification key established on the basis of SSR permitted the unambiguous discrimination of cultivars and confirmed the reliability of SSR for fingerprinting fig genotypes. The study findings are discussed in relation to the establishment of a national reference collection that will aid in the conservation of Tunisian fig resources.     

Transgelin: An androgen-dependent protein identified in the seminal vesicles of three Saharan rodents

During the breeding season, a major androgen-dependent protein with an apparent molecular weight of 21 kDa was isolated and purified from the seminal vesicles of three Saharan rodents (MLVSP21 from Meriones libycus, MSVSP21 from Meriones shawi, and MCVSP21 from Meriones crassus). The 21-kDa protein was isolated and purified from soluble seminal vesicle proteins of homogenate by one-dimensional polyacrylamide gel electrophoresis (SDS-PAGE). Using polyclonal antibodies directed against POSVP₂₁ (Psammomys obesus seminal vesicles protein of 21 kDa), a major androgen-dependent secretory protein from sand rat seminal vesicles, identified previously as transgelin, we showed an immunological homology with POSVP₂₁ by immunoblotting. These three major androgen-dependent proteins with a same apparent molecular weight of 21 kDa designated as MLVSP₂₁ (Meriones libycus seminal vesicles protein of 21 kDa), MSVSP₂₁ (Meriones shawi seminal vesicles protein of 21 kDa), and MCVSP₂₁ (Meriones crassus seminal vesicles protein of 21 kDa) were localized by immunohistochemistry and identified by applying a proteomic approach. Our results indicated that the isolated proteins MLSVP₂₁, MSSVP₂₁, and MCSVP₂₁ seem to correspond to the same protein: the transgelin. So that transgelin can be used as a specific marker of these rodent physiological reproduction mechanisms.     

Wetting of Planar Surfaces by a Gay-Berne Liquid Crystal

Molecular simulation of the wetting of an unstructured attractive wall by Gay-Berne liquid crystals are reported. Simulations are performed in the grand canonical ensemble on a wide pore at constant temperatures of T *=0.53 and 0.56, corresponding to temperatures below and above the nematic-isotropic-vapor triple point. Close to the coexistence chemical potential, a thick liquid film wets the solid surface. The film is composed of stratified layers of molecules parallel to the solid surface, which follow to a nematic domain at the lower temperature and an isotropic one at the higher temperature. In both cases, the film is in equilibrium with the corresponding vapor phase. Close to the liquid-vapor interface there is a manifest tendency for the molecules to orient themselves parallel to the interface. The adsorption on the wall varies continuously with the thermodynamic parameters considered and no evidence of a first order prewetting transition is observed.