An example of debris-flows hazard modeling using GIS

International audienceWe present a GIS-based model for predicting debris-flows occurrence. The availability of two different digital datasets and the use of a Digital Elevation Model (at a given scale) have greatly enhanced our ability to quantify and to analyse the topography in relation to debris-flows. In particular, analysing the relationship between debris-flows and the various causative factors provides new understanding of the mechanisms. We studied the contact zone between the calcareous basement and the fluvial-lacustrine infill adjacent northern area of the Terni basin (Umbria, Italy), and identified eleven basins and corresponding alluvial fans. We suggest that accumulations of colluvium in topographic hollows, whatever the sources might be, should be considered potential debris-flow source areas. In order to develop a susceptibility map for the entire area, an index was calculated from the number of initiation locations in each causative factor unit divided by the areal extent of that unit within the study area. This index identifies those units that produce the most debris-flows in each Representative Elementary Area (REA). Finally, the results are presented with the advantages and the disadvantages of the approach, and the need for further research

RNASET2 as a tumor antagonizing gene in a melanoma cancer model

The RNASET2 gene, mapped in 6q27, was previously found to exert control of tumorigenesis in an ovarian cancer system. We present here results indicating a similar control in a melanoma cancer model. Thus, this gene is most likely involved in a common general pathway of tumorigenesis. Moreover, its antitumorigenic activity is manifested in vivo but not in vitro, suggesting that this gene belongs to the growing category of tumor antagonizing/malignancy suppressor genes. A possible role of RNASET2 in the activation of a senescence program, whose responsible locus was mapped in the same chromosomal 6q27 region, seems to be inconsistent with our data

Indications of dynamic effects on scaling relationships between channel sinuosity and vegetation patch size across a salt marsh platform

Salt marshes are important coastal areas that consist of a vegetated intertidal marsh platform and a drainage network of tidal channels. How salt marshes and their drainage networks develop is not fully understood, but it has been shown that the biogeomorphic interactions and feedbacks between vegetation development and channel formation play an important role. We examined the relationships among tidal channel sinuosity, marsh roughness, vegetation type (pioneer, Elymus athericus or Phragmites australis), and patch size at different spatial scales using a high-resolution vegetation map (derived from aerial photography) and lower-resolution satellite imagery processed with linear spectral mixture analysis. The patch-size distribution in all vegetation types corresponded to a power law, suggesting the presence of self-organizational processes. While small vegetation patches are more dominant in pioneer vegetation, they were present in all vegetation types. The largest patch size is restricted to E. athericus. We observed an inverse logarithmic relationship between channel sinuosity and vegetation patch size in all vegetation types. The fact that this relationship is observed in both pioneer and later successional stages suggests that after the establishment of a drainage network in the dynamic pioneer stages of salt marsh development, the later stages of salt marsh succession largely inherit the meandering pattern of the early successional stages. Our study confirms recent evidence that no significant changes in the specific features of tidal channel networks (e.g., channel width, drainage density, and efficiency) take place during the later stages of salt marsh development

γδβ-thalassaemias 1 and 2 are the result of a 100 kpb deletion in the human β-globin cluster.

The DNA spanning two large deletions in the human beta-globin gene cluster (gamma beta-thalassaemia 1 and 2) has been cloned by cosmid cloning and chromosomal walking. The entire region was mapped and analyzed for the presence of repetitive sequences. The results show that the affected loci have lost almost 100 kb of DNA in a deletion event not involving homologous or repetitive sequences

Development of nature inspired antiplasmodial hits possessing the thiazinoquinone pharmacophore

Malaria accounts globally for more than 200 million new cases and 438,000 deaths per year. Since malaria is a disease of worldwide implications, combating it is one of the highest priority programs of the WHO. A worrisome increase in the number of fatal cases has been registered in recent years and it is principally due to the diffusion of multi-drug resistant strains of Plasmodium, making less effective the limited armamentarium of available drugs. Therefore, there is an urgent need of new antimalarial drugs with high efficacy against resistant strains and broad stage mode of action. To reach these challenging aims, the identification and selection of new lead compounds constitutes a crucial point. In this regard, nature remains an ever evolving resource. Recently, the antiplasmodial activity of marine secondary metabolites characterized by a quinone scaffold has been reported. In particular, it is worth to point out that a number of quinones have been shown to be effective antimalarials. The observed effects are most likely related to the most prominent chemical feature of these kind of molecules, that is their ability to undergo redox reaction i) shuttling electrons from reduced flavoproteins to acceptors such as hemoglobin-associated or free Fe(III)-protoporphyrin IX or ii) inhibiting the mitochondrial electron transport chain. In this context, recently, we were inspired by two marine metabolites Aplidinone A and B isolated from the Mediterranean ascidian Aplidium conicum, and we developed a series of synthetic analogues featuring the thiazinoquinone chemotype present in the natural metabolites with simplified side chains and different substituents. Manipulation of this chemical scaffold afforded additional analogues with improved pharmacological proprieties compared to the starting hits identified in the previous series

Spatial and Temporal Dust Source Variability in Northern China Identified Using Advanced Remote Sensing Analysis

The aim of this research is to provide a detailed characterization of spatial patterns and temporal trends in the regional and local dust source areas within the desert of the Alashan Prefecture (Inner Mongolia, China). This problem was approached through multi-scale remote sensing analysis of vegetation changes. The primary requirements for this regional analysis are high spatial and spectral resolution data, accurate spectral calibration and good temporal resolution with a suitable temporal baseline. Landsat analysis and field validation along with the low spatial resolution classifications from MODIS and AVHRR are combined to provide a reliable characterization of the different potential dust-producing sources. The representation of intra-annual and inter-annual Normalized Difference Vegetation Index (NDVI) trend to assess land cover discrimination for mapping potential dust source using MODIS and AVHRR at larger scale is enhanced by Landsat Spectral Mixing Analysis (SMA). The combined methodology is to determine the extent to which Landsat can distinguish important soils types in order to better understand how soil reflectance behaves at seasonal and inter-annual timescales. As a final result mapping soil surface properties using SMA is representative of responses of different land and soil cover previously identified by NDVI trend. The results could be used in dust emission models even if they are not reflecting aggregate formation, soil stability or particle coatings showing to be critical for accurately represent dust source over different regional and local emitting areas

Salinomycin and Other Ionophores as a New Class of Antimalarial Drugs with Transmission-Blocking Activity

The drug target profile proposed by the Medicines for Malaria Venture for a malaria elimination/eradication policy focuses on molecules active on both asexual and sexual stages of Plasmodium, thus with both curative and transmission-blocking activities. The aim of the present work was to investigate whether the class of monovalent ionophores, which includes drugs used in veterinary medicine and that were recently proposed as human anticancer agents, meets these requirements. The activity of salinomycin, monensin, and nigericin on Plasmodium falciparum asexual and sexual erythrocytic stages and on the development of the Plasmodium berghei and P. falciparum mosquito stages is reported here. Gametocytogenesis of the P. falciparum strain 3D7 was induced in vitro, and gametocytes at stage II and III or stage IV and V of development were treated for different lengths of time with the ionophores and their viability measured with the parasite lactate dehydrogenase (pLDH) assay. The monovalent ionophores efficiently killed both asexual parasites and gametocytes with a nanomolar 50% inhibitory concentration (IC50). Salinomycin showed a fast speed of kill compared to that of standard drugs, and the potency was higher on stage IV and V than on stage II and III gametocytes. The ionophores inhibited ookinete development and subsequent oocyst formation in the mosquito midgut, confirming their transmission-blocking activity. Potential toxicity due to hemolysis was excluded, since only infected and not normal erythrocytes were damaged by ionophores. Our data strongly support the downstream exploration of monovalent ionophores for repositioning as new antimalarial and transmission-blocking leads

cAMP-Signalling Regulates Gametocyte-Infected Erythrocyte Deformability Required for Malaria Parasite Transmission.

Blocking Plasmodium falciparum transmission to mosquitoes has been designated a strategic objective in the global agenda of malaria elimination. Transmission is ensured by gametocyte-infected erythrocytes (GIE) that sequester in the bone marrow and at maturation are released into peripheral blood from where they are taken up during a mosquito blood meal. Release into the blood circulation is accompanied by an increase in GIE deformability that allows them to pass through the spleen. Here, we used a microsphere matrix to mimic splenic filtration and investigated the role of cAMP-signalling in regulating GIE deformability. We demonstrated that mature GIE deformability is dependent on reduced cAMP-signalling and on increased phosphodiesterase expression in stage V gametocytes, and that parasite cAMP-dependent kinase activity contributes to the stiffness of immature gametocytes. Importantly, pharmacological agents that raise cAMP levels in transmissible stage V gametocytes render them less deformable and hence less likely to circulate through the spleen. Therefore, phosphodiesterase inhibitors that raise cAMP levels in P. falciparum infected erythrocytes, such as sildenafil, represent new candidate drugs to block transmission of malaria parasites