Spontaneous hybridization between durum wheat (Triticum turgidum durum) and Aegilops ovata is regularly observed in nature. The frequency of spontaneous amphiploidy in sympatric populations was estimated at 10(-6) (direct in situ observations and germinated seed collected from A. ovata plants). In nursery conditions some genotype combinations gave frequencies that were much higher at 10(-3). Genomic in situ hybridization revealed that fertile amphiploids had arisen through unreduced gametes, and that some of them carried wheat -A. ovata recombinant chromosomes. The frequency of production of unreduced gametes is probably genetically inherited. Amphiploids provide a route for gene flow, including that of transgenes, to the wild. Gene flow could potentially be minimized through the choice of wheat cultivars that produce a low frequency of unreduced gametes. (C) 2004 The Linnean Society of London.

A set of 240 wild type accessions of Arabidopsis thaliana were cultivated in two contrasting conditions, with or without application of a cold treatment prior to cotyledon emergence. In each condition, 20 primary and 3 derived variables were measured that describe the phenology and morphology of each plant. The cold pre-treatment greatly modified the time to flowering but diversely affected accessions (according to their need for vernalization). Three criteria were then used to identify a minimum subset within the 23 variables to be measured under a timesaving constraint. We combined a criterion of highest genetic heritability so that environmental experimental variance is lowered, a criterion of highest Spearman coefficient so that the rank of any accessions remained stable across treatments and, last, a criterion of highest contribution of the variable to the seed production as estimated in a multilinear regression analysis. Applying this 'three criteria' procedure lead us finally to propose a minimum set of five variables: flowering precocity, maximum plant height, height to first flower, number of flowering heads and mean distance between siliques as best describing variation in life history traits expressed by the whole collection. We believe that these variables definitely affect the ability of Arabidopsis to adjust its life cycle to ecological conditions including the intensity of the interspecific competition prevailing in the environment. The core collection of 24 Arabidopsis accessions that was chosen for maximizing molecular diversity was confirmed here to also maximize most of each trait's variability. Some linkage disequilibrium expressed at the whole genome level when considering accessions from very diverse origin is probably responsible for the conservation of such a high diversity. These 24 accessions could thus provide an important resource for natural variation to be exploited in the identification of quantitative trait loci (QTL), in genotype/phenotype association studies or exploration of ecological and evolutionary relations.

Estimation of long-term effective population size (Ne) from polymorphism data alone requires an independent knowledge of mutation rate. Microsatellites provide the opportunity to estimate Ne because their high mutation rate can be estimated from observed mutations. We used this property to estimate Ne in allotetraploid wheat Triticum turgidum at four stages of its history since its domestication. We estimated the mutation rate of 30 microsatellite loci. Allele-specific mutation rates μ were predicted from the number of repeats of the alleles. Effective population sizes were calculated from the diversity parameter θ = 4Neμ. We demonstrated from simulations that the unbiased estimator of θ based on Nei's heterozygosity is the most appropriate for estimating Ne because of a small variance and a relative robustness to variations in the mutation model compared to other estimators. We found a Ne of 32,500 individuals with a 95% confidence interval of [20,739; 45,991] in the wild ancestor of wheat, 12,000 ([5790; 19,300]) in the domesticated form, 6000 ([2831; 9556]) in landraces, and 1300 ([689; 2031]) in recent improved varieties. This decrease illustrates the successive bottlenecks in durum wheat. No selective effect was detected on our loci, despite a complete loss of polymorphism for two of them.

The effects of factors known to influence the level of polymorphism at microsatellite loci were studied using 99 markers and seven lines of bread wheat. Mutational factors as well as indirect selective events shape diversity at these loci. Theory predicts that the selection of favorable alleles should reduce polymorphism at neutral neighboring loci in genomic areas with low recombination rates. In wheat, local recombination rate is positively correlated with physical distance from the centromere. Seventy four loci among the 99 used could be physically located on the chromosome. We studied how the following affected the diversity among a set of inbred lines: the length of the alleles, the motif (CA versus CT), the structure of the loci (perfect versus imperfect) and the chromosomal position of the loci. For each locus, we determined whether the polymorphism observed at a locus was compatible with the Stepwise Mutation Model (SMM) or the Two-Phase Model (TPM). Both the mutation rate and the compatibility with the SMM or the TPM were shown to be variable between loci. Wheat microsatellite loci were found to be more variable when segregating alleles were perfect and had long motifs (composed of many repetitions). Diversity observed at 19 loci was not compatible with the SMM. Loci located in distal regions, with presumably high recombination rates, had longer allele sizes and were more polymorphic than loci located in proximal regions. We conclude that both mutation factors and indirect selective events vary according to the local recombination rate and therefore jointly influence the level of polymorphism at microsatellite loci in wheat.

The successful exploitation of natural genetic diversity requires a basic knowledge of the extent of the variation present in a species. To study natural variation in Arabidopsis thaliana, we defined nested core collections maximizing the diversity present among a worldwide set of 265 accessions. The core collections were generated based on DNA sequence data from a limited number of fragments evenly distributed in the genome and were shown to successfully capture the molecular diversity in other loci as well as the morphological diversity. The core collections are available to the scientific community and thus provide an important resource for the study of genetic variation and its functional consequences in Arabidopsis. Moreover, this strategy can be used in other species to provide a rational framework for undertaking diversity surveys, including single nucleotide polymorphism (SNP) discovery and phenotyping, allowing the utilization of genetic variation for the study of complex traits.

Evidence exists that a large number of tumor cells such as osteosarcoma cells stimulate platelet aggregation, which can be an early step in the metastatic processes of these tumors. Thromboxane A(2) (TXA(2)) is released during platelet aggregation, and it has been suggested that this release may be pathogenic for tumor metastasis for several reasons:Some tumors release large amounts of TXA(2) compared to normal tissue.TXA(2) potentiates tumor growth in culture and increases metastasis in animals.TXA(2) is a potent stimulant of platelet aggregation and causes vascular injuries that may promote implantation of tumor cell-platelet aggregates. If TXA(2) participates in tumor metastasis, it may be hypothesized that TXA(2) inhibitors should decrease tumor metastasis. So, we have evaluated the effects of the original TXA(2) synthase inhibitor and TXA(2) receptor antagonist BM-567 on platelet aggregation induced by osteosarcoma cells using MG-63 tumor cells. Results obtained showed that this drug inhibited both MG-63 tumor-cell-induced platelet aggregation and platelet TXA(2) release following the tumor cell stimulation with IC(50) values of 3.04x10(-7) and 2.51x10(-8)M, respectively.

The aim of this work was to evaluate the effects of BM-567 (N-pentyl-N'-[(2-cyclohexylamino-5-nitrobenzene)sulfonyl]urea), a torasemide derivative, on both thromboxane A(2) (TXA(2)) receptors (TP) and thromboxane synthase of human platelets. The drug affinity for TP receptors of human washed platelets has been determined. In this test, BM-567 showed a high affinity (IC(50): 1.1+/-0.1nM) for the TP receptors in comparison with BM-531 (IC(50): 7.8+/-0.7nM) and sulotroban (IC(50): 931+/-85nM), two TXA(2) antagonists. We also demonstrated that BM-567 prevented platelet aggregation induced by arachidonic acid (AA) (600 microM) (ED(100): 0.20+/-0.10 microM), U-46619, a stable TXA(2) agonist (1 microM) (ED(50): 0.30+/-0.04 microM) and collagen (1microgram ml(-1)) (% of inhibition: 44.3+/-4.3% at 10 microM) and inhibited the second wave of ADP (2microM). Moreover, when BM-567 was incubated in whole blood from healthy donors, the closure time measured by the Platelet Function analyzer (PFA-100((R))) was significantly prolonged (closure time: 215+/-21s) by using collagen/epinephrine cartridges. Finally, at the concentration of 1 microM, BM-567 completely reduced the TXB(2) production from human platelets stimulated with AA (600 microM). These results indicate that BM-567 is a novel combined TXA(2) receptor antagonist and thromboxane synthase inhibitor characterized by a powerful antiplatelet potency.

Recent analysis of French wild grapevine, Vitis vinifera ssp. silvestris (Cuisset, 1998; This et al., 2000), has demonstrated clear differentiation between wild and cultivated compartment, but on a very small scale. Until now no global inventory of silvestris individuals was available in France.The present work aims to 1. Establish an inventory of wild grapevine in France, 2. Analyze the genetic diversity within the wild compartment and 3. Compare diversity between cultivated and wild compartments.In 2000 and 2001, we prospected several regions in France in order to identify wild grapevine. One hundred and thirty five sites were found, and 517 individuals have been recorded, among which 330 were believed to be native wild grapevines based on morphological characteristics.Out of these, 154 individuals have been further analyzed. They originate from 4 regions: Aquitaine, Corse, Languedoc-Roussillon and Midi-Pyrenees. Based on morphological data, 123 of these were considered as wild grapevine. Analysis of morphological data did not revealed clear geographical differentiation of the wild individuals. On the contrary, analysis of molecular data revealed a clear differentiation between wild grapes from Corsica and from continental France, as well as a differentiation between cultivated and wild compartments. French wild genotypes are more closely related to French cultivars than to cultivars from other parts of Europe.

Platelet aggregation plays a key role in the pathogenesis of thromboembolic diseases such as myocardial infarction, stroke, unstable angina and peripheral artery disease. Until recently, aspirin was the only antiplatelet agent available to prevent or treat these events. Over the past several years, there has been a substantial expansion in the antiplatelet armamentarium as well as in the understanding of the clinical importance of antiplatelet therapy in limiting the complications of thrombosis. Aspirin was one of the first agents to be adopted and it remains as the standard therapy with the higher amount of available clinical information. Following aspirin, ADP receptor antagonists like ticlopidine and clopidogrel as well as phosphodiesterase inhibitors dipyridamole and cilostazol have been introduced. Glycoprotein (GP) IIb/IIIa receptor antagonists like eptifibatide, tirofiban and abciximab are the newer antiplatelet agents which act at the end of the common pathway of platelet aggregation. Although results of clinical studies with the first oral GPIIb/IIIa antagonists were disappointing, agents of the new generation might expand the potential application of GPIIb/IIIa targeted therapy. This review will highlight recent advances in the development of aspirin, phosphodiesterase inhibitors, ADP receptor antagonists and the platelet glycoprotein IIb/IIIa inhibitors. The emphasis of this paper has been placed on the chemical aspects of these agents.

In patients under oral anticoagulation therapy, the risk of haemorrhage following surgery must be balanced with the risk of thrombo-embolism induced by its discontinuation. Dental surgery is usually safe. Indirect anticoagulation may be continued provided rigorous surgical techniques and careful local hemostasis are applied.

This article reports a case of Anton-Babinski syndrome, due to right middle cerebral artery thrombosis and attributed to a likely primary antiphospholipid syndrome. It is always difficult to diagnose the latter, especially in the case of our patient who had a past history of multiple venous thromboses but also a heterozygosity for the mutation of the factor V of Leyden. We reviewed the literature dedicated to the prothrombotic events linked to the presence of these antiphospholipid antibodies: the lupus anticoagulant and the anticardiolipin antibodies.

After two selfing generations of two different Triticum turgidum – Aegilops ovata amphiploids carrying the Ph1 gene, or lacking it ( ph1c mutant), karyotypes of their offspring were scored by GISH (genomic in situ hybridization). On average, the chromosome number was lower than expected (56 chromosomes) on the basis of the parental constitutions ( T. turgidum , AABB, 2n=4 x =28; Ae. ovata , M o M o U o U o , 2n=4 x =28). The lost chromosomes belonged to the wild Aegilops species. The two families differed greatly by their number of intergenomic translocations, also detected by GISH. The ph1c family showed nine translocations over 12 plants while only one translocation was observed in the Ph1 family. All exchanges involved either the M o and U o chromosomes or the M o and wheat chromosomes, the size of the exchanged segment ranging from 3% to 36% of the total chromosome length. The results suggest an epistatic effect of the ph1c deletion over the genetic diploidizing system that operates in Ae. ovata since translocated chromosomes are most-likely derived from homoeologous recombination. The potential of these results for wheat breeding programmes is also considered.

A forty-six-year old in-patient was treated with heparin for massive pulmonary embolism. During the hospitalization, the clinical evolution was unusual and characterised as follows: a) the extent of pulmonary embolism justified a thrombolysis by streptokinase; b) an acute thrombocytopenia occurred a few days later, preceded by a slower, but significant decrease of platelet count; c) a non-occlusive aortic thrombosis developed, distal to renal arteries, causing distal embolisation, successfully treated by local fibrinolysis. The prompt correction of platelet count after interruption of heparin therapy confirmed the diagnosis, before the detection of antibodies against heparin-PF4 complexes. Heparin was immediately replaced by another direct anticoagulant, recombinant hirudin (lépirudine-Refludan), initially given alone and progressively replaced by an antivitamin K (Sintrom). The occurrence of distal embolism from aortic thrombosis, developed during the critical period, characterizes this syndrome, which appears rare but whose incidence is probably underestimated. A subsequent investigation for risk factors for venous thromboembolism in this patient revealed a heterozygous mutation of the Leiden type factor V in our patient, and also in others family members.

BM-531 (N-tert-butyl-N'-[(2-cyclohexylamino-5-nitrobenzene)sulfonyl]urea), a torasemide derivative, is a novel noncarboxylic thromboxane receptor antagonist and thromboxane synthase inhibitor. Indeed, its affinity for human washed platelet TXA2 receptors labeled with [3H]SQ-29548 (IC50 = 0.0078 microM) is higher than sulotroban (IC50 = 0.93 microM) and SQ-29548 (IC50 = 0.021 microM). Moreover, BM-531 is characterized by a potent antiaggregatory property. Indeed, on one hand, in human citrated platelet-rich plasma BM-531 prevents platelet aggregation induced by arachidonic acid (600 microM) (ED100 = 0.125 microM), U-46619, a stable TXA2 agonist (1 microM) (ED50 = 0.482 microM) or collagen (1 microgram/mL) (percentage of inhibition: 42.9% at 10 microM) and inhibits the second wave of ADP (2 microM)-induced aggregation. On the other hand, when BM-531 is incubated in whole blood from healthy donors, the closure time measured by the recently developed platelet function analyser (PFA-100) is significantly prolonged. In addition, at the concentrations of 10 and 1 microM, BM-531 totally prevents the production of TXB2 by human platelets activated by arachidonic acid. Finally, at 10 microM, BM-531 significantly prevents rat fundus contractions induced by U-46619 but not by prostacyclin. These results suggest that BM-531, which is devoid of the diuretic property of torasemide, can be regarded as a promising antiplatelet agent.