Probabilistic identification of rockfall source areas at regional scale in El Hierro (Canary Islands, Spain)

Abstract Modelling rockfall phenomena is complex and requires various inputs, including an accurate location of the source areas. Source areas are controlled by geomorphological, geological, or other geo-environmental factors and may largely influence the results of the modelling. In the Canary Islands, rockfalls are extremely common and pose a major threat to society, costing lives, disrupting infrastructure, and destroying livelihoods. In 2011, the volcanic event on the island of El Hierro triggered numerous rockfalls that affected strategic infrastructures, with a substantial impact on the local population. During the emergency, the efforts performed to map the source areas and to model the rockfalls in the considerably steep landscape characterising the island were not trivial. To better identify the rockfall source areas, we propose a probabilistic modelling framework that applies a combination of multiple statistical models using the source area locations mapped in the field as the dependent variable and a set of thematic data as independent variables. The models use as input morphometric parameters derived from the Digital Elevation Model and lithological data as an expression of the mechanical behaviour of the rocks. The analysis of different training and validation scenarios allowed us to test the model sensitivity to the input data, select the optimal model training configuration, and evaluate the model applicability outside the training areas. The final map obtained from the model for the entire island of El Hierro provides the probability of a given location being a potential source area and can be used as the input for rockfall runout simulation modelling

Caspase-3-mediated cleavage of p65/RelA results in a carboxy-terminal fragment that inhibits IκBα and enhances HIV-1 replication in human T lymphocytes

<p>Abstract</p> <p>Background</p> <p>Degradation of p65/RelA has been involved in both the inhibition of NF-κB-dependent activity and the onset of apoptosis. However, the mechanisms of NF-κB degradation are unclear and can vary depending on the cell type. Cleavage of p65/RelA can produce an amino-terminal fragment that was shown to act as a dominant-negative inhibitor of NF-κB, thereby promoting apoptosis. However, the opposite situation has also been described and the production of a carboxy-terminal fragment that contains two potent transactivation domains has also been related to the onset of apoptosis. In this context, a carboxy-terminal fragment of p65/RelA (ΔNH₂p65), detected in non-apoptotic human T lymphocytes upon activation, has been studied. T cells constitute one of the long-lived cellular reservoirs of the human immunodeficiency virus type 1 (HIV-1). Because NF-κB is the most important inducible element involved in initiation of HIV-1 transcription, an adequate control of NF-κB response is of paramount importance for both T cell survival and viral spread. Its major inhibitor IκBα constitutes a master terminator of NF-κB response that is complemented by degradation of p65/RelA.</p> <p>Results and conclusions</p> <p>In this study, the function of a caspase-3-mediated carboxy-terminal fragment of p65/RelA, which was detected in activated human peripheral blood lymphocytes (PBLs), was analyzed. Cells producing this truncated p65/RelA did not undergo apoptosis but showed a high viability, in spite of caspase-3 activation. ΔNH₂p65 lacked most of DNA-binding domain but retained the dimerization domain, NLS and transactivation domains. Consequently, it could translocate to the nucleus, associate with NF-κB1/p50 and IκBα, but could not bind -κB consensus sites. However, although ΔNH₂p65 lacked transcriptional activity by itself, it could increase NF-κB activity in a dose-dependent manner by hijacking IκBα. Thus, its expression resulted in a persistent transactivation activity of wild-type p65/RelA, as well as an improvement of HIV-1 replication in PBLs. Moreover, ΔNH₂p65 was increased in the nuclei of PMA-, PHA-, and TNFα-activated T cells, proving this phenomenon was related to cell activation. These data suggest the existence of a novel mechanism for maintaining NF-κB activity in human T cells through the binding of the carboxy-terminal fragment of p65/RelA to IκBα in order to protect wild-type p65/RelA from IκBα inhibition.</p

Radical reactions on pinene-oxide derivatives induced by Ti(III)

[EN]A practical, brief and selective synthesis of several pinene oxide derived terpenoids can be achieved from readily available starting materials. The key step is a radical reaction promoted by titanocene chloride

Titanocene-promoted stereoselective eliminations on epoxy alcohols derived from R-(−)-carvone

[EN]The reaction of several stereoisomeric epoxy alcohols, obtained from R-(−)-carvone, and their corresponding formates, acetates, and benzoates, promoted by Cp2TiCl has been studied. The different outcomes of the reaction of epoxy derivatives are rationalized in terms of mechanistically biased processes. The radicals emerging from oxirane cleavage provide two types of reaction: dehydroxylation (deoxycarbonylation) and dehydrogenation. The results offer considerable support for the radical elimination theory of hydroxyl, formyloxyl, and acetoxyl groups. The inability of tertiary radicals to be reduced by the Ti(III) complex is demonstrated unequivocally

On the Mechanism and Kinetics of Radical Reactions of Epoxyketones and Epoxynitriles Induced by Titanocene Chloride

[EN]The reactions of a series of epoxynitriles and epoxyketones induced by titanocene chloride have been studied. The kinetics of the decyanogenation of β,γ-epoxynitriles with Ti(III) corresponds to a radical reaction (k25 ≈ 106 s-1), as demonstrated by competition experiments with H-transfer from 1,4- cyclohexadiene (1,4-CHD) or PhSH or conjugate addition to acrylonitrile. The 5-exo cyclization onto nitrile induced by Ti(III) is a radical reaction (k25 ≈ 107 s-1) as seen in competition experiments with H-transfer from PhSH or the titanocene-water complex. The iminyl or alkoxyl radicals generated by 5-exo cyclization onto nitriles or ketones only undergo a reduction with Ti(III). This reaction overwhelms any alternative process, such as tandem cyclization onto alkenes or β-scission. Iminyl radicals generated by 4-exo cyclizations onto nitriles undergo reduction with Ti(III) and β-scission reaction in a ratio of 96:4 when the R-substituent is CN. Alkoxyl radicals from 4-exo cyclizations onto ketone carbonyls undergo reduction with Ti(III) and β-scission in a ratio of 60:40 when the R-substituent is COOR. In nearly all the reactions studied, the role of Ti(III) is triple: a radical initiator (homolytic cleavage of oxirane), a Lewis acid (coordination to CN or CdO), and a terminator (reduction of iminyl or alkoxyl radicals)

Cytoplasmic- and extracellular-proteome analysis of Diplodia seriata: a phytopathogenic fungus involved in grapevine decline

<p>Abstract</p> <p>Background</p> <p>The phytopathogenic fungus <it>Diplodia seriata</it>, whose genome remains unsequenced, produces severe infections in fruit trees (fruit blight) and grapevines. In this crop is recognized as one of the most prominent pathogens involved in grapevine trunk disease (or grapevine decline). This pathology can result in the death of adult plants and therefore it produces severe economical losses all around the world. To date no genes or proteins have been characterized in <it>D. seriata </it>that are involved in the pathogenicity process. In an effort to help identify potential gene products associated with pathogenicity and to gain a better understanding of the biology of <it>D. seriata</it>, we initiated a proteome-level study of the fungal mycelia and secretome.</p> <p>Results</p> <p>Intracellular and secreted proteins from <it>D. seriata </it>collected from liquid cultures were separated using two-dimensional gel electrophoresis. About 550 cytoplasmic proteins were reproducibly present in 3 independent extractions, being 53 identified by peptide mass fingerprinting and tandem mass spectrometry. The secretome analysis showed 75 secreted proteins reproducibly present in 3 biological replicates, being 16 identified. Several of the proteins had been previously identified as virulence factors in other fungal strains, although their contribution to pathogenicity in <it>D. seriata </it>remained to be analyzed. When <it>D. seriata </it>was grown in a medium supplemented with carboxymethylcellulose, 3 proteins were up-regulated and 30 down-regulated. Within the up-regulated proteins, two were identified as alcohol dehydrogenase and mitochondrial peroxyrredoxin-1, suggesting that they could play a significant role in the pathogenicity process. As for the 30 down-regulated proteins, 9 were identified being several of them involved in carbohydrate metabolism.</p> <p>Conclusions</p> <p>This study is the first report on proteomics on <it>D. seriata</it>. The proteomic data obtained will be important to understand the pathogenicity process. In fact, several of the identified proteins have been reported as pathogenicity factors in other phytopathogenic fungi. Moreover, this proteomic analysis supposes a useful basis for deepening into <it>D. seriata </it>knowledge and will contribute to the development of the molecular biology of this fungal strain as it has been demonstrated by cloning the gene <it>Prx</it>1 encoding mitochondrial peroxiredoxin-1 of <it>D. seriata </it>(the first gene to be cloned in this microorganism; data not shown).</p