The hippocampal cholinergic neurostimulating peptide, the N-terminal fragment of the secreted phosphatidylethanolamine-binding protein, possesses a new biological activity on cardiac physiology

Phosphatidylethanolamine-binding protein (PEBP), alternatively named Raf-1 kinase inhibitor protein, is the precursor of the hippocampal cholinergic neurostimulating peptide (HCNP) corresponding to its natural N-terminal fragment, previously described to be released by hippocampal neurons. PEBP is a soluble cytoplasmic protein, also associated with plasma and reticulum membranes of numerous cell types. In the present report, using biochemistry and cell biology techniques, we report for the first time the presence of PEBP in bovine chromaffin cell, a well described secretion model. We have examined its presence at the subcellular level and characterized this protein on both secretory granule membranes and intragranular matrix. In addition, its presence in bovine chromaffin cell and platelet exocytotic medium, as well as in serum, was reported showing that it is secreted. Like many other proteins that lack signal sequence, PEBP may be secreted through non-classic signal secretory mechanisms, which could be due to interactions with granule membrane lipids and lipid rafts. By two-dimensional liquid chromatography-tandem mass spectrometry, HCNP was detected among the intragranular matrix components. The observation that PEBP and HCNP were secreted with catecholamines into the circulation prompted us to investigate endocrine effects of this peptide on cardiovascular system. By using as bioassay an isolated and perfused frog (Rana esculenta) heart preparation, we show here that HCNP acts on the cardiac mechanical performance exerting a negative inotropism and counteracting the adrenergic stimulation of isoproterenol. All together, these data suggest that PEBP and HCNP might be considered as new endocrine factors involved in cardiac physiology.     

Ecological implications on the aggregation of <Emphasis Type="Italic">Amblyomma fuscum</Emphasis> (Acari: Ixodidae) on <Emphasis Type="Italic">Thrichomys laurentius</Emphasis> (Rodentia: Echimyidae), in northeastern Brazil

We investigated the Amblyomma fuscum load on a pullulating wild rodent population and the environmental and biological factors influencing the tick load on the hosts. One hundred and three individuals of Thrichomys laurentius were caught in an Atlantic forest fragment in northeastern Brazil, as part of a longitudinal survey on ticks infesting non-volant small mammals. Ticks (n = 342) were found on 45 individuals and the overall mean intensity of infestation was 7.6 ticks per infested rodent. Ticks were highly aggregated in the host population and the negative binomial distribution model provides a statistically satisfactory fit. The aggregated distribution was influenced by sex and age of the host. The microhabitat preference by T. laurentius probably increases contact opportunities between hosts and aggregated infesting stages of the ticks and represents important clues about the habitat suitability for A. fuscum.     

Neurotoxin gene profiling of clostridium botulinum types C and D native to different countries within Europe

Clostridium botulinum types C and D, as well as their mosaic variants C-D and D-C, are associated with avian and mammalian botulism. This study reports on the development of low-density macroarrays based on the GeneDisc cycler platform (Pall-GeneDisc Technologies) applied to the simultaneous detection of the C. botulinum subtypes C, C-D, D, and D-C. The limit of detection of the PCR assays was 38 fg of total DNA, corresponding to 15 genome copies. Artificially contaminated samples of cecum showed a limit of detection below 50 spores/g. The tests were performed with a large variety of bacterial strains, including C. botulinum types C (n = 12), C-D (n = 29), D (n = 5), and D-C (n = 10), other botulinum neurotoxin (BoNT)-producing Clostridium strains (n = 20), non-BoNT-producing clostridia (n = 20), and other bacterial species (n = 23), and showed a high specificity. These PCR assays were compared to previously published real-time PCRs for the detection of C. botulinum in 292 samples collected from cases of botulism events in four European regions. The majority of the samples originated from wild birds (n = 108), poultry (n = 60), and bovines (n = 56). Among the 292 samples, 144 were positive for either the bont/C-D or the bont/D-C gene by using the GeneDisc arrays. The reliability of the results tallied to 97.94%. Interestingly, only BoNT mosaics, types C-D and D-C, were found in naturally contaminated samples whatever their animal origin and their geographical location. Further investigations should now be performed in order to check that mosaic types dominate in Europe and that acquisition of mosaic types helps in survival or adaptation to particular niche.     

PEM Anchorage on Titanium Using Catechol Grafting

Background

This study deals with the anchorage of polyelectrolyte films onto titanium surfaces via a cathecol-based linker for biomedical applications.

Methodology

The following study uses a molecule functionalized with a catechol and a carboxylic acid: 3-(3,4-dihydroxyphenyl)propanoic acid. This molecule is anchored to the TiO₂ substrate via the catechol while the carboxylic acid reacts with polymers bearing amine groups. By providing a film anchorage of chemisorption type, it makes possible to deposit polyelectrolytes on the surface of titanium.

Principal Findings

Infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), contact angle and atomic force microscopy (AFM) measurements show that the different steps of grafting have been successfully performed.

Conclusions

This method based on catechol anchorage of polyelectrolytes open a window towards large possibilities of clinical applications.     

Genome Structure and Reproductive Behaviour Influence the Evolutionary Potential of a Fungal Phytopathogen

Modern agriculture favours the selection and spread of novel plant diseases. Furthermore, crop genetic resistance against pathogens is often rendered ineffective within a few years of its commercial deployment. Leptosphaeria maculans, the cause of phoma stem canker of oilseed rape, develops gene-for-gene interactions with its host plant, and has a high evolutionary potential to render ineffective novel sources of resistance in crops. Here, we established a four-year field experiment to monitor the evolution of populations confronted with the newly released Rlm7 resistance and to investigate the nature of the mutations responsible for virulence against Rlm7. A total of 2551 fungal isolates were collected from experimental crops of a Rlm7 cultivar or a cultivar without Rlm7. All isolates were phenotyped for virulence and a subset was genotyped with neutral genetic markers. Virulent isolates were investigated for molecular events at the AvrLm4-7 locus. Whilst virulent isolates were not found in neighbouring crops, their frequency had reached 36% in the experimental field after four years. An extreme diversity of independent molecular events leading to virulence was identified in populations, with large-scale Repeat Induced Point mutations or complete deletion of AvrLm4-7 being the most frequent. Our data suggest that increased mutability of fungal genes involved in the interactions with plants is directly related to their genomic environment and reproductive system. Thus, rapid allelic diversification of avirulence genes can be generated in L. maculans populations in a single field provided that large population sizes and sexual reproduction are favoured by agricultural practices.     

Meiotic regulation of TPX2 protein levels governs cell cycle progression in mouse oocytes

Formation of female gametes requires acentriolar spindle assembly during meiosis. Mitotic spindles organize from centrosomes and via local activation of the RanGTPase on chromosomes. Vertebrate oocytes present a RanGTP gradient centred on chromatin at all stages of meiotic maturation. However, this gradient is dispensable for assembly of the first meiotic spindle. To understand this meiosis I peculiarity, we studied TPX2, a Ran target, in mouse oocytes. Strikingly, TPX2 activity is controlled at the protein level through its accumulation from meiosis I to II. By RNAi depletion and live imaging, we show that TPX2 is required for spindle assembly via two distinct functions. It controls microtubule assembly and spindle pole integrity via the phosphorylation of TACC3, a regulator of MTOCs activity. We show that meiotic spindle formation in vivo depends on the regulation of at least a target of Ran, TPX2, rather than on the regulation of the RanGTP gradient itself.     

Expression of enzymes involved in estrogen metabolism in human prostate.

There is evidence that estrogens can directly modulate human prostate cell activity. It has also been shown that cultured human prostate cancer LNCaP can synthesize the active estrogen estradiol (E2). To elucidate the metabolism of estrogens in the human prostate, we have studied the expression of enzymes involved in the formation and inactivation of estrogens at the cellular level. 17beta-Hydroxysteroid dehydrogenase (17beta-HSD) types 1, 2, 4, 7, and 12, as well as aromatase mRNA and protein expressions, were studied in benign prostatic hyperplasia (BPH) specimens using in situ hybridization and immunohistochemistry. For 17beta-HSD type 4, only in situ hybridization studies were performed. Identical results were obtained with in situ hybridization and immunohistochemistry. All the enzymes studied were shown to be expressed in both epithelial and stromal cells, with the exception of 17beta-HSD types 4 and 7, which were detected only in the epithelial cells. On the basis of our previous results, showing that 3beta-HSD and 17beta-HSD type 5 are expressed in human prostate, and of the present data, it can be concluded that the human prostate expresses all the enzymes involved in the conversion of circulating dehydroepiandrosterone (DHEA) to E2. The local biosynthesis of E2 might be involved in the development and/or progression of prostate pathology such as BPH and prostate cancer through modulation of estrogen receptors, which are also expressed in epithelial and stromal cells.     

Molecular Comparisons of Full Length Metapneumovirus (MPV) Genomes,Including Newly Determined French AMPV-C and –D Isolates,Further Supports Possible Subclassification within the MPV Genus

Four avian metapneumovirus (AMPV) subgroups (A–D) have been reported previously based on genetic and antigenic differences. However, until now full length sequences of the only known isolates of European subgroup C and subgroup D viruses (duck and turkey origin, respectively) have been unavailable. These full length sequences were determined and compared with other full length AMPV and human metapneumoviruses (HMPV) sequences reported previously, using phylogenetics, comparisons of nucleic and amino acid sequences and study of codon usage bias. Results confirmed that subgroup C viruses were more closely related to HMPV than they were to the other AMPV subgroups in the study. This was consistent with previous findings using partial genome sequences. Closer relationships between AMPV-A, B and D were also evident throughout the majority of results. Three metapneumovirus “clusters” HMPV, AMPV-C and AMPV-A, B and D were further supported by codon bias and phylogenetics. The data presented here together with those of previous studies describing antigenic relationships also between AMPV-A, B and D and between AMPV-C and HMPV may call for a subclassification of metapneumoviruses similar to that used for avian paramyxoviruses, grouping AMPV-A, B and D as type I metapneumoviruses and AMPV-C and HMPV as type II.