Inhibitory action of a new lectin from Xerocomus chrysenteron on cell-substrate adhesion

Lectins are carbohydrate-binding proteins which potentially link to cell surface glycoconjugates and affect cell proliferation. We investigated the effect of a new lectin from the mushroom Xerocomus chrysenteron (XCL) on cell proliferation using adherent and suspension cell lines. XCL caused a dose-dependent inhibition of proliferation of the adherent cell lines NIH-3T3 and HeLa. Several experiments suggest that disruption of cell-substrate adhesion is the main factor affecting cell growth inhibition. (i) No antiproliferative effect was observed on the SF9 cell line, which does not require to be attached to grow. (ii) XCL was shown to affect the adherence of cells following their suspension by trypsin treatment. (iii) XCL was localized on the cell surface where it would act as a coating agent. (iv) XCL induced morphological changes from well spread to rounded cells and disrupted the actin cytoskeleton. By contrast, flow cytometric analysis showed that XCL does not interfere with the cell cycle, and does not induce apoptosis.     

Root anchorage of inner and edge trees in stands of Maritime pine (<Emphasis Type="Italic">Pinus pinaster</Emphasis> Ait.) growing in different podzolic soil conditions

Static winching tests were carried out in order to determine the mechanical resistance of Maritime pine to overturning. The tested stands were selected according to podzolic soil conditions: wet Lande, characterised by a shallow ground water table and a hard pan horizon, and dry Lande, with a deeper ground water table and a hard pan absent or broken up. As this soil horizon limits the vertical growth of tree roots, anchorage resistance was investigated with regards to the presence or absence of a hard pan underneath each tree. To determine if mechanical behaviour differed within a stand, trees from inside the stand and edge trees at the border exposed to prevailing winds were also tested. The critical turning moment (TM_crit,total) at the base of the stem was positively related to the variable (H × DBH²) (H, total tree height; DBH, tree diameter). Linear regression analyses between TM_crit,total and (H × DBH²) showed that the presence of a hard pan had no significant effect on anchorage resistance in uprooted trees. Stem failure occurred for 82% of trees on dry Lande when (H × DBH²) < 1 m³. Moreover, stem failure type on dry Lande indicated that trees were better anchored. On soil with a hard pan, edge trees were found to be 20% more resistant to overturning than inner trees. Edge trees differed from inner trees in that the soil-root plate was two times larger and also possessed a larger surface area on the windward side.     

Natural ligands of hamster aphrodisin

The chemical nature of vertebrate pheromones remains largely to be deciphered. Hamster aphrodisin is a rare instance of mammal proteinaceous sexual pheromone. This protein, found in vaginal secretions, facilitates the mounting behaviour of males via activation of a specialized sensory structure named the vomeronasal organ, which activates the accessory olfactory bulb. Since it might carry small pheromonal ligands due to its lipocalin structure, we analysed organic extracts from natural aphrodisin. We identified five predominant compounds specifically bound onto natural aphrodisin as 1-hexadecanol (44.7%), 1-octadecanol (19.5%), Z-9-octadecen-1-ol (18.2%), E-9-octadecen-1-ol (15.4%) and hexadecanoic acid (2.2%). Interestingly, these compounds are also described as part of insect pheromone blends, disclosing the continuing story of amazing coincidences of chemical communication shared by mammals and insects.     

Mapping 245 SSR markers on the <Emphasis Type="Italic">Vitis vinifera</Emphasis> genome: a tool for grape genetics

The aim of the present work was to develop a microsatellite marker-based map of the Vitis vinifera genome (n=19), useful for genetic studies in this perennial heterozygous species, as SSR markers are highly transferable co-dominant markers. A total of 346 primer pairs were tested on the two parents (Syrah and Grenache) of a full sib population of 96 individuals (S × G population), successfully amplifying 310 markers. Of these, 88.4% markers were heterozygous for at least one of the two parents. A total of 292 primer pairs were then tested on Riesling, the parent of the RS₁ population derived from selfing (96 individuals), successfully amplifying 299 markers among which 207 (62.9%) were heterozygous. Only 6.7% of the markers were homozygous in all three genotypes, stressing the interest of such markers in grape genetics. Four maps were constructed based on the segregation of 245 SSR markers in the two populations. The Syrah map was constructed from the segregations of 177 markers that could be ordered into 19 linkage groups (total length 1,172.2 cM). The Grenache map was constructed with the segregations of 178 markers that could be ordered into 18 linkage groups (total length 1,360.6 cM). The consensus S × G map was constructed with the segregations of 220 markers that were ordered into 19 linkage groups (total length 1,406.1 cM). One hundred and eleven markers were scored on the RS₁ population, among them 27 that were not mapped using the S × G map. Out of these 111 markers, 110 allowed to us to construct a map of a total length of 1,191.7 cM. Using these four maps, the genome length of V. vinifera was estimated to be around 2,200 cM. The present work allowed us to map 123 new SSR markers on the V. vinifera genome that had not been ordered in a previous SSR-based map (Riaz et al. 2004), representing an average of 6.5 new markers per linkage group. Any new SSR marker mapped is of great potential usefulness for many applications such as the transfer of well-scattered markers to other maps for QTL detection, the use of markers in specific regions for the fine mapping of genes/QTL, or for the choice of markers for MAS.     

Neuronal and muscular alterations caused by two wheat endosperm proteins,puroindoline-a and alpha1-purothionin,are due to ion pore formation

Using the patch-clamp technique it was found that the toxicity of the two wheat endosperm proteins puroindoline-a and alpha1-purothionin probably results from the dissipation of ion concentration gradients essential for the maintenance of cellular homeostasis.Abbreviations PIN-a puroindoline-a - PTH alpha1-purothionin Presented at the Biophysical Society Meeting on Ion Channels—from structure to disease held in May 2003, Rennes, France     

Hsp90 invades the outside

Metalloproteases are required for the invasive nature of cancer cells. Surprisingly, the cytosolic molecular chaperone Hsp90 is now shown to promote maturation of the extracellular metalloprotease MMP2. This finding extends the multiplicity of roles assigned to the Hsp90 family to a new function outside the cell.     

Nifedipine protects against overproduction of superoxide anion by monocytes from patients with systemic sclerosis

We have reported previously that dihydropyridine-type calcium-channel antagonists (DTCCA) such as nifedipine decrease plasma markers of oxidative stress damage in systemic sclerosis (SSc). To clarify the cellular basis of these beneficial effects, we investigated the effects in vivo and in vitro of nifedipine on superoxide anion (O₂ ^•-) production by peripheral blood monocytes. We compared 10 healthy controls with 12 patients with SSc, first after interruption of treatment with DTCCA and second after 2 weeks of treatment with nifedipine (60 mg/day). O₂ ^•- production by monocytes stimulated with phorbol myristate acetate (PMA) was quantified by the cytochrome c reduction method. We also investigated the effects in vitro of DTCCA on O₂ ^•- production and protein phosphorylation in healthy monocytes and on protein kinase C (PKC) activity using recombinant PKC. After DTCCA had been washed out, monocytes from patients with SSc produced more O₂ ^•- than those from controls. Nifedipine treatment considerably decreased O₂ ^•- production by PMA-stimulated monocytes. Treatment of healthy monocytes with nifedipine in vitro inhibited PMA-induced O₂ ^•- production and protein phosphorylation in a dose-dependent manner. Finally, nifedipine strongly inhibited the activity of recombinant PKC in vitro. Thus, the oxidative stress damage observed in SSc is consistent with O₂ ^•- overproduction by primed monocytes. This was decreased by nifedipine treatment both in vivo and in vitro. This beneficial property of nifedipine seems to be mediated by its cellular action and by the inhibition of PKC activity. This supports the hypothesis that this drug could be useful for the treatment of diseases associated with oxidative stress.     

Thermal selection of PGM allozymes in newly founded populations of the thermotolerant vent polychaete Alvinella pompejana

Alvinella pompejana lives on the top of chimneys at deep-sea hydrothermal vents of the East Pacific Rise. It is thought to be one of the most thermotolerant and eurythermal metazoans. Our experimental approach combines methods of population genetics and biochemistry, considering temperature as a potential selective factor. Phosphoglucomutase (Pgm-1 locus) is one of the most polymorphic loci of A. pompejana and exhibits four alleles, from which alleles 90 and 100 dominate with frequencies of approximately 0.5 in populations. Results from previous studies suggested that allele 90 might be more thermostable than allele 100. Significant genetic differentiation was found by comparing contrasted microhabitats, especially the young, still hot, versus older and colder chimneys, with allele 90 being at highest frequency on young chimneys. Moreover the frequency of allele 90 was positively correlated with mean temperature at the opening of Alvinella tubes. In parallel, thermostability and thermal optimum experiments demonstrated that allele 90 is more thermostable and more active at higher temperatures than allele 100. This dataset supports an additive model of diversifying selection in which allele 90 is favoured on young hot chimneys but counterbalanced over the whole metapopulation by the dynamics of the vent ecosystem.     

Cardiovascular drugs inhibit MMP-9 activity from human THP-1 macrophages

It is now recognized that atherosclerosis complications are related to the unstable character of the plaque rather than its volume. Vulnerable plaques often contain a large lipid core, a reduced content of smooth muscle cells, and accumulation of inflammatory cells. Colocalization of macrophages and active matrix metalloproteinases (MMPs) is likely relevant for atherosclerotic lesion disruption. Nevertheless, MMP activity and regulation by cardiovascular drugs remains poorly defined. In this study, we evaluated the effects of avasimibe, fluvastatin, and peroxisome proliferator-activated receptor (PPAR) ligands on 92-kDa gelatinase B (MMP-9) secretion by human THP-1 macrophages. THP-1 macrophages were treated with compounds for 48 h, and secreted MMP-9 protein was quantified by immunoassay. Avasimibe, fluvastatin, and PPARalpha agonists (fenofibric acid and Wy-14643) significantly reduced, in a concentration-dependent manner, MMP-9 protein (up to 67 +/- 5% for fenofibric acid). In these assays, the PPARgamma selective agonist rosiglitazone displayed a lower efficacy than other compounds. Enzymatic activity of MMP-9 was also decreased by all cardiovascular drugs tested. MMP-9 protein/activity inhibition by cardiovascular drugs was due, at least in part, to a decrease in MMP-9 mRNA. These results show that THP-1 macrophages could be an useful cellular model to investigate effects of compounds on plaque vulnerability through MMP-9 activity.