Ditch network sustains functional connectivity and influences patterns of gene flow in an intensive agricultural landscape.

In intensive agricultural landscapes, plant species previously relying on semi-natural habitats may persist as metapopulations within landscape linear elements. Maintenance of populations' connectivity through pollen and seed dispersal is a key factor in species persistence in the face of substantial habitat loss. The goals of this study were to investigate the potential corridor role of ditches and to identify the landscape components that significantly impact patterns of gene flow among remnant populations. Using microsatellite loci, we explored the spatial genetic structure of two hydrochorous wetland plants exhibiting contrasting local abundance and different habitat requirements: the rare and regionally protected Oenanthe aquatica and the more commonly distributed Lycopus europaeus, in an 83 km(2) agricultural lowland located in northern France. Both species exhibited a significant spatial genetic structure, along with substantial levels of genetic differentiation, especially for L. europaeus, which also expressed high levels of inbreeding. Isolation-by-distance analysis revealed enhanced gene flow along ditches, indicating their key role in effective seed and pollen dispersal. Our data also suggested that the configuration of the ditch network and the landscape elements significantly affected population genetic structure, with (i) species-specific scale effects on the genetic neighborhood and (ii) detrimental impact of human ditch management on genetic diversity, especially for O. aquatica. Altogether, these findings highlighted the key role of ditches in the maintenance of plant biodiversity in intensive agricultural landscapes with few remnant wetland habitats.

The influence of isocyanurate content on the bioperformance of hydrocarbon-based polyurethanes.

Bulk, surface and bioactivity of newly synthesized hydroxy telechelic polyisoprene-based (H-HTPI) polyurethane were investigated by means of ATR-FT-IR, contact-angle measurements, cell viability, calcification, and platelet and fibrinogen quantification. The influence of isophorone diisocyanates isocyanurate (I-IPDI) content on these properties was determined. Results generally showed a non-significant difference in these properties when they were compared with a commercially available biomedical polyurethane (PU), such as Tecoflex. Unexpectedly, where the increase of isocyanate content for commercial diisocyanate-based biocompatible PU significantly increases the surface contact angle, the new hydroxy telechelic polyisoprene-based PU showed a decrease of water contact angle with increasing I-IPDI content in the polymer. Nevertheless, the overall surface exhibited hydrophobic properties, i.e., theta > 85. Polymer cytotoxicity, assessed with L929 cell line in direct contact with the surface of the samples, showed no toxic effects on the cells. Interestingly, regardless of the I-IPDI content, platelet adhesion and fibrinogen adsorption, as well as the mineral deposition were fairly similar for all synthesized PUs. Our findings revealed that replacing diisocyanates by their isocyanurate homologues is a very relevant approach for preparation of polyurethanes with different mechanical properties while maintaining similar surface properties.

Prediction uncertainty of environmental change effects on temperate European biodiversity.

Observed patterns of species richness at landscape scale (gamma diversity) cannot always be attributed to a specific set of explanatory variables, but rather different alternative explanatory statistical models of similar quality may exist. Therefore predictions of the effects of environmental change (such as in climate or land cover) on biodiversity may differ considerably, depending on the chosen set of explanatory variables. Here we use multimodel prediction to evaluate effects of climate, land-use intensity and landscape structure on species richness in each of seven groups of organisms (plants, birds, spiders, wild bees, ground beetles, true bugs and hoverflies) in temperate Europe. We contrast this approach with traditional best-model predictions, which we show, using cross-validation, to have inferior prediction accuracy. Multimodel inference changed the importance of some environmental variables in comparison with the best model, and accordingly gave deviating predictions for environmental change effects. Overall, prediction uncertainty for the multimodel approach was only slightly higher than that of the best model, and absolute changes in predicted species richness were also comparable. Richness predictions varied generally more for the impact of climate change than for land-use change at the coarse scale of our study. Overall, our study indicates that the uncertainty introduced to environmental change predictions through uncertainty in model selection both qualitatively and quantitatively affects species richness projections.

Dispersal and genetic structure in the American marten, Martes americana.

Natal dispersal in a vagile carnivore, the American marten (Martes americana), was studied by comparing radio-tracking data and microsatellite genetic structure in two populations occupying contrasting habitats. The genetic differentiation determined among groups of individuals using F(ST) indices appeared to be weak in both landscapes, and showed no increase with geographical distance. Genetic structure investigated using pairwise genetic distances between individuals conversely showed a pattern of isolation by distance (IBD), but only in the population occurring in a homogeneous high-quality habitat, therefore showing the advantage of individual-based analyses in detecting within-population processes and local landscape effects. The telemetry study of juveniles revealed a leptokurtic distribution of dispersal distances in both populations, and estimates of the mean squared parent-offspring axial distance (sigma2) inferred both from the genetic pattern of IBD and from the radio-tracking survey showed that most juveniles make little contribution to gene flow.

In vitro thrombogenicity investigation of new water-dispersible polyurethane anionomers bearing carboxylate groups.

New segmented polyurethane (PU) anionomers based on hydroxytelechelic polybutadiene were synthesized via an aqueous dispersion process. Incorporation of carboxylic groups was achieved using thioacids of different length. Surface properties were investigated by mean of water absorption analysis and static contact-angle measurements using water, diiodomethane, formamide and ethylene glycol. Blood compatibility of the PUs was evaluated by in vitro adhesion assays using 111In-radiolabeled platelet-rich plasma and [125I]fibrinogen. Morphology of the adhered platelets was examined by scanning electron microscopy (SEM). Results were compared to two biomedical-grade PUs, namely Pellethane and Tecoflex. Insertion of carboxylic groups increased surface hydrophilicity and limited water uptake ( < 8% for an ion content of 5% by weight). Surface energy of all synthesized PUs was between 40 and 45 mJ/m2. Platelet adhesion and fibrinogen adsorption on the PU anionomer surfaces were affected as a function to the increase of graft length; thiopropionic was the most haemocompatible, followed by thiosuccinic and then thioglycolic acid. SEM analyses of all ionic PU samples exhibited low platelet adhesion to surfaces with no morphological modification. In conclusion, increased hydrophily, dynamic mobility and charge repulsion are synergistic key factors for enhanced haemocompatibility.

Hemocompatibilty of new ionic polyurethanes: influence of carboxylic group insertion modes.

New segmented polyurethane (PU) anionomers based on hydroxytelechelic polybutadiene (HTPB) were synthesized via two environment-friendly chemical routes. The effects of carboxylic content and ion incorporation mode on the surface properties were investigated by mean of water absorption analysis and static contact angle measurements using water, diiodomethane, formamide and ethylene glycol. Blood compatibility of the PUs was evaluated by in vitro adhesion assay using 111In-radiolabeled platelet rich plasma and 125I-fibrinogen. The morphology of platelet adhesion was also observed by scanning electron microscopy (SEM). Results were compared with a biomedical-grade PU, Pellethane. Insertion of the carboxylic groups on the soft segments (S-alpha series), using thioglycolic acid (TGA), increases surface hydrophilicity, limits water uptake (5%, for an ion content of 3.6 wt%), and reduces platelet adhesion and fibrinogen adsorption on the PUs' surfaces. In contrast, the classical insertion onto the hard segment (H-alpha series), using dimethylolpropionate (DMPA) as chain extender, leads to high water uptake (18%, for an ion content of 3.6 wt%) and promotes platelet and fibrinogen adhesion. SEM analyses of the non-ionic PUs exhibited surfaces with adhered platelets which underwent morphological modification. Similarly, the H-alpha ionic PUs show adherent and activated platelets. On the contrary, no platelet morphology changes were observed on the S-alpha ionic surfaces. In conclusion, insertion of carboxyl groups on the soft segments of PUs reduces their thrombogenicity.

Studying boundary effects on animal movement in heterogeneous landscapes: the case of Abax ater (Coleoptera: Carabidae) in hedgerow network landscapes.

Changes in movement possibilities of insect species can be a response to increasing heterogeneity in man made landscapes. We studied the movement of Abax ater (Coleoptera, Carabidae) between woody and cultivated areas in Brittany. Two woody habitats (woods and hedgerows) and two cultivated areas (cornfields and meadows) were considered. Quantifying the movement of the carabid beetle between woody and cultivated areas was done using Mark-Release-Recapture techniques. Marked individuals were released at the centre of circular enclosures (3 m in diameter), encompassing two adjacent habitats, one being wooded, the other cultivated. Individuals were recaptured at the edge of enclosures. Analysis of recaptures showed that flows of individuals from a given habitat to another were constant during the experiment. Flows can be summed up by a probability of move, which depends on the two adjacent habitats surrounding ecotone. When released in cultivated habitats, forest carabid beetles preferentially moved toward woody habitat, but in some enclosures the forest carabid beetles did not exhibited any preference between cultivated areas and woods. In these cases ecotones may include both woody and cultivated areas, and their functional width should be reconsidered. These conclusions were globally in agreement with knowledge about ecology of Abax ater, but ask for confirmation through replicates on different sites. Nevertheless, these results demonstrated the usefulness of the method and give new guidelines for the study of flows of carabid beetles through ecotones.

Progesterone freeze-dried systems in sublingual dosage form.

Various polymer matrices were tested to enhance progesterone bioavailability as part of an emergency therapy. Among the different polymers used, i.e. poly(N-vinylpyrrolidone) (PVP), poly(ethylene oxide) (PEO), Dextran T70 and partially saponified poly(methyl glyoxylate) (PMGz), the latter gives the fastest solubilization rate. The best results were obtained with the lyophilized dosage form instead of a simple mixture of the drug within the polymer matrix. A nearly instantaneous solubilization was observed with PMGz copolymers bearing 10-40% of carboxylic groups and containing up to 20% of the drug. The instantaneous solubilization of the PMGz matrix is due to the hydrophilic moieties, and the presence of hydrophobic zones in PMGz promotes good affinity with the drug and optimal dispersion into the matrix.

[Spindle cell lipoma and 13q deletion: diagnostic utility of cytogenetic analysis]. / Lipomes à cellules fusiformes et délétion 13q: apport de la cytogénétique dans l'aide au diagnostic.

AIM: Spindle cell lipomas are rare adipose tissues tumors. Histologically, these lesions are composed of mature adipocytes and spindle cells associated with collagen bundles. Spindle cell lipomas are benign tumors that can be difficult to distinguish from malignant tumors such as spindle cell liposarcomas, myxoid liposarcomas or well-differentiated liposarcomas. RESULTS: We report herein the description of two new cases. The first case was a deeply situated and infiltrating tumor located in the retromastoidian area. The karyotype showed the presence of two chromosomal abnormalities, a partial deletion of the long arm of chromosome 13, del(13)(q12) and a balanced reciprocal translocation t(2;6)(p16~21;p21). The second case was a subcutaneous tumor of posterior cervical localization. The karyotype showed a 13q deletion associated with a complex rearrangement of chromosomes 5, 6 and 10. The presence of the 13q deletion allowed us to confirm the diagnosis of spindle cell lipoma in both cases. This deletion has been previously described in six out the eleven published karyotype reports. The 13q deletion is usually associated with partial monosomy 16. The present case confirms that it can occur independently. The 6p21 rearrangement may also play a role in the pathobiology of this tumor, as suggested by the positive HMGIY expression detected by immunohistochemistry. CONCLUSION: Our study further illustrates that spindle cell lipomas can infiltrate the surrounding muscle and emphasizes the usefulness of cytogenetic analysis in the differential diagnosis of soft tissue tumors.

[A rare etiology of hepatic steatosis associated with lactic acidosis: the toxicity of antiviral nucleoside analogues]. / Une étiologie rare de stéatose hépatique avec acidose lactique: la toxicité des analogues nucléosidiques anti-viraux.

We report three cases of hepatic steatosis associated with lactic acidosis occurring in HIV positive patients and due to a toxicity of antiviral nucleoside analogues. The clinico-pathological presentation was similar associating digestive signs (vomiting and abdominal pain), polypnea, lactic acidosis, a lethal clinical course, and an hepatomegaly with a diffuse macrovacuolar steatosis. The ultrastructural study performed in two cases showed mitochondrial alterations in hepatocytes. The toxicity of antiviral nucleoside analogues is due to a mitochondrial DNA polymerase inhibition. The incidence of this disease is actually low but probably underestimated. The diagnosis should be rapidly performed and the treatment immediatly interrupted.

Characterization of centromere alterations in liposarcomas.

Supernumerary ring and large marker chromosomes are a characteristic of atypical lipomas and well-differentiated liposarcomas (ALP-WDLPS) and are composed of amplified 12q14-15 sequences in association with variable segments from other chromosomes. Although stably transmitted, these chromosomes contain centromeric alterations, showing no detectable alpha-satellite sequences. We performed C-banding, fluorescence in situ hybridization, and immunostaining with anti-centromere antibodies in 8 cases of liposarcomas with supernumerary rings and large markers, including 5 ALP-WDLPS and 3 dedifferentiated-LPS and high-grade LPS. Our results with alpha-satellite probes and anti-CENPB antibodies confirm the lack of detectable alpha-satellite sequences in the five ALP-WDLPS supernumerary chromosomes, whereas centromeric activity was proved by the detection of kinetochores by using anti-CENPC antibodies. In contrast, the high grade and dedifferentiated liposarcomas showed a different pattern. In 2 cases, amplified chromosome 12 sequences, including amplification of alpha-satellite 12 sequences in 1 case, were present on chromosomes with typical centromeres. In another case, the rings were similar to WDLPS-ALP rings, but a large marker contained a chromosome 5 centromere and amplified alpha-satellite sequences from chromosome 8. ALP-WDLPS is the first example of a tumor class for which the presence of stable analphoid chromosomes is a constant and specific abnormality. Formation of newly derived centromeres, so-called neocentromeres, could be an original and effective way to maintain a selective advantage in neoplastic cells by conferring stability to the supernumerary chromosomes of ALP-WDLPS. The activation of normally non-centromeric sequences might be obtained by an epigenetic mechanism due to the peculiar chromatin conformation of these highly complex chromosomes.