1,313 research outputs found

    Density and ecological drivers of free-ranging cat abundance and activity in Madeira Island, Macaronesia

    Get PDF
    Mammalian predators introduced to oceanic islands pose a significant threat to biodiversity and have led to numerous extinctions. Free-ranging cats are particularly problematic due to their predatory habits and negative impact on conservation. However, there is limited information on the ecology and population status of free-ranging cats in insular ecosystems, where they often represent the apex terrestrial predator. Using a peri-urban protected area in the subtropical island of Madeira as a case study, we employed camera traps to assess the density of free-ranging cats and investigate the ecological drivers influencing their abundance and activity in nonurban insular habitats. Based on 582 trapping-nights, we identified 25 individual cats from 156 cat detections. Spatially explicit capture–recapture models revealed a density of 1.4 cats per km2. Cat activity was positively affected by both the proportion of rocky areas in the landscape and the distance to human resource subsidies, whereas no significant driver was found for abundance. Our results indicate that cats are highly abundant throughout the protected area and suggest that their core home ranges are associated with rocky terrain, away from the most humanized sections of the park. Free-ranging cats do not appear to heavily rely on anthropogenic food sources, signaling that they may rely mostly on wild prey to fulfill their dietary needs. Their preference for rocky areas could be explained by the increased availability of shelter and prey, such as the Madeira wall lizard (Teira dugesii). Notably, cat abundance and activity were particularly high in the vicinity of the only known breeding colony of the locally threatened Manx shearwater (Puffinus puffinus) on Madeira Island. Our findings suggest that cats pose a significant threat to the native vertebrate fauna of the protected area and thus their management, particularly during the breeding season of the Manx shearwater, should be considered

    Insights into the habitat associations, phylogeny, and diet of Pipistrellus maderensis in Porto Santo, northeastern Macaronesia

    Get PDF
    Around 60 % of all bat species occur in islands, and nearly one in four is an insular endemic. Bats are often the only native terrestrial mammals in oceanic islands, and despite increasing anthropogenic pressures, little is known about the distribution, natural history, and population status of most insular bat populations. The sub-tropical archipelago of Madeira is composed of the volcanic islands of Madeira, Porto Santo, and Desertas and is home to the Macaronesian endemic Pipistrellus maderensis, to the endemic subspecies Nyctalus leisleri verrucosus, and to Plecotus austriacus. Pipistrellus maderensis is known to both Madeira and Porto Santo, whereas the other two species have only been recorded in the former. However, no bats have been recorded in Porto Santo for over 15 years, raising fears that bats are probably extinct in the island. In July 2021, we conducted an island-wide acoustic survey using AudioMoth passive acoustic recorders, leading to the detection of Pipistrellus maderensis in 28 out of the 46 sampling sites (60 %). The species' activity was strongly associated with artificial water sources, and genetic samples from six captured individuals revealed that the populations of Pipistrellus maderensis in Porto Santo and Madeira have a close phylogenetic affinity. Furthermore, using DNA metabarcoding, we found that the species feeds on a wide variety of insects, including several economically important pest species and disease vectors. These findings emphasise the need to target more conservation and research efforts towards extant island bat populations and the potential ecosystem services they provide

    Influence of random, pile-up and scatter corrections in the quantification properties of small animal PET scanners

    Get PDF
    Proceeding of: 2007 IEEE Nuclear Science Symposium Conference Record (NSS'07), Honolulu, Hawaii, USA, Oct. 27 - Nov. 3, 2007The potential of PET imaging for pre-clinical studies will be fully realized only if repeatable, reliable and accurate quantitative analysis can be performed. The characteristic blurring of PET images due to positron range and non co-linearity, as well as random, pile-up and scatter contributions, that may be significant for fully 3D PET acquisitions of small animal, make it difficult their quantitative analysis. In this work specific activity versus specific counts in the image calibration curves for 3D-OSEM reconstructions from a commercially available small animal PET scanner are determined. Both linear and non-linear calibration curves are compared and the effect of corrections for random and scatter contributions are studied. To assess the improvement in the calibration procedure when scatter and random corrections are considered, actual data from a rat tumor pre- and postcancer therapy are analyzed. The results show that correcting for random and scatter corrections can increase the sensitivity of PET images to changes in the biological response of tumors by more than 15%, compared to uncorrected reconstructions.This work has been partially funded by projects TEC2004-07052-C02 of Ministerio de Educación y Ciencia and CD-TEAM, program CENIT, Ministerio de Industria, Spain. Part of the computations of this work were done at the '`High capacity cluster for physical techniques'' of the Faculty for Physical Sciences of the UCM, funded in part by the UE under the FEDER program and in part by the UCM

    The architecture of the European-Mediterranean lithosphere: A synthesis of the Re-Os evidence

    Get PDF
    Rhenium-depletion model ages (TRD) of sulfi des in peridotite xenoliths from the subcontinental mantle beneath central Spain (the Calatrava volcanic fi eld) reveal that episodes of mantle magmatism and/or metasomatism in the Iberia microplate were linked to crustal growth events, mainly during supercontinent assembly and/or breakup at ca. 1.8, 1.1, 0.9, 0.6, and 0.3 Ga. A synthesis of available in situ and whole-rock Os-isotope data on mantlederived peridotites shows that this type of mantle (maximum TRD of ca. 1.8 Ga) is widespread in the subcontinental mantle of Europe and Africa outboard from the Betics-Maghrebides- Appenines front. In contrast, the mantle enclosed within the Alpine domain records TRD as old as 2.6 Ga, revealing a previously unrecognized Archean domain or domains in the central and western Mediterranean. Our observations indicate that ancient fragments of subcontinental lithospheric mantle have played an important role in the development of the present architecture of the Mediterranean lithosphere

    Geotechnical and geomechanical characterization of the fault gouge of the Alhama de Murcia active fault, SE Spain

    Get PDF
    Here we present the results of the mechanical and mineralogical study of the fault rock of the Alhama de Murcia fault. This fault is one of the most active faults in the Iberian Peninsula. It shows segments partially formed by exhumed fine grained fault rocks (fault gouge FG) with a thickness of more than 50 m developed mainly in a brittle regime. Several strength and strain tests have been carried out, both in-situ and in laboratory, considering different stress orientations in relation to the tectonic fabric. Undisturbed samples encountered from two fault observatory boreholes drilled near Lorca, (FAM-1 and FAMSIS-IGN, of 174 and 40 m depth, respectively) has been used for the laboratory tests. The FG shows a hard soil and soft rock like mechanical behavior with uniaxial compressive strength 1.19) for planes unfavourably oriente

    RNA-KG: An ontology-based knowledge graph for representing interactions involving RNA molecules

    Full text link
    The "RNA world" represents a novel frontier for the study of fundamental biological processes and human diseases and is paving the way for the development of new drugs tailored to the patient's biomolecular characteristics. Although scientific data about coding and non-coding RNA molecules are continuously produced and available from public repositories, they are scattered across different databases and a centralized, uniform, and semantically consistent representation of the "RNA world" is still lacking. We propose RNA-KG, a knowledge graph encompassing biological knowledge about RNAs gathered from more than 50 public databases, integrating functional relationships with genes, proteins, and chemicals and ontologically grounded biomedical concepts. To develop RNA-KG, we first identified, pre-processed, and characterized each data source; next, we built a meta-graph that provides an ontological description of the KG by representing all the bio-molecular entities and medical concepts of interest in this domain, as well as the types of interactions connecting them. Finally, we leveraged an instance-based semantically abstracted knowledge model to specify the ontological alignment according to which RNA-KG was generated. RNA-KG can be downloaded in different formats and also queried by a SPARQL endpoint. A thorough topological analysis of the resulting heterogeneous graph provides further insights into the characteristics of the "RNA world". RNA-KG can be both directly explored and visualized, and/or analyzed by applying computational methods to infer bio-medical knowledge from its heterogeneous nodes and edges. The resource can be easily updated with new experimental data, and specific views of the overall KG can be extracted according to the bio-medical problem to be studied

    Obtaining antioxidants and natural preservatives from food by-products through fermentation: A review

    Get PDF
    Industrial food waste has potential for generating income from high-added-value compounds through fermentation. Solid-state fermentation is promising to obtain a high yield of bioactive compounds while requiring less water for the microorganism’s growth. A number of scientific studies evinced an increase in flavonoids or phenolics from fruit or vegetable waste and bioactive peptides from cereal processing residues and whey, a major waste of the dairy industry. Livestock, fish, or shellfish processing by-products (skin, viscera, fish scales, seabass colon, shrimp waste) also has the possibility of generating antioxidant peptides, hydrolysates, or compounds through fermentation. These bioactive compounds (phenolics, flavonoids, or antioxidant peptides) resulting from bacterial or fungal fermentation are also capable of inhibiting the growth of commonly occurring food spoilage fungi and can be used as natural preservatives. Despite the significant release or enhancement of an-tioxidant compounds through by-products fermentation, the surface areas of large-scale bioreactors and flow patterns act as constraints in designing a scale-up process for improved efficiency. An in-process purification method can also be the most significant contributing factor for raising the overall cost. Therefore, future research in modelling scale-up design can contribute towards mitigating the discard of high-added-value generating residues. Therefore, in this review, the current knowledge on the use of fermentation to obtain bioactive compounds from food by-products, emphasizing their use as natural preservatives, was evaluated

    Widespread population of invasive ferrets Mustela furo (Carnivora: Mustelidae) on the island of Madeira, Macaronesia

    Get PDF
    Invasive mammalian predators are arguably the most damaging group of alien animals for global biodiversity and their impacts are particularly damaging in endemic-rich insular ecosystems. Ferrets (Mustela furo) are well-known for their potential to establish self-sustaining feral populations. Yet, knowledge about their distribution and trophic interactions is scarce. Here, we provide ample evidence of a well-established and widespread population of ferrets on the subtropical island of Madeira (Portugal). Ferrets are using natural and human-dominated habitats, where they are preying on both native (e.g., Cory’s shearwaters (Calonectris borealis) and the endemic and IUCN Endangered Zino’s petrel (Pterodroma madeira)) and non-native vertebrates

    Floral Morphogenesis: Stochastic Explorations of a Gene Network Epigenetic Landscape

    Get PDF
    In contrast to the classical view of development as a preprogrammed and deterministic process, recent studies have demonstrated that stochastic perturbations of highly non-linear systems may underlie the emergence and stability of biological patterns. Herein, we address the question of whether noise contributes to the generation of the stereotypical temporal pattern in gene expression during flower development. We modeled the regulatory network of organ identity genes in the Arabidopsis thaliana flower as a stochastic system. This network has previously been shown to converge to ten fixed-point attractors, each with gene expression arrays that characterize inflorescence cells and primordial cells of sepals, petals, stamens, and carpels. The network used is binary, and the logical rules that govern its dynamics are grounded in experimental evidence. We introduced different levels of uncertainty in the updating rules of the network. Interestingly, for a level of noise of around 0.5–10%, the system exhibited a sequence of transitions among attractors that mimics the sequence of gene activation configurations observed in real flowers. We also implemented the gene regulatory network as a continuous system using the Glass model of differential equations, that can be considered as a first approximation of kinetic-reaction equations, but which are not necessarily equivalent to the Boolean model. Interestingly, the Glass dynamics recover a temporal sequence of attractors, that is qualitatively similar, although not identical, to that obtained using the Boolean model. Thus, time ordering in the emergence of cell-fate patterns is not an artifact of synchronous updating in the Boolean model. Therefore, our model provides a novel explanation for the emergence and robustness of the ubiquitous temporal pattern of floral organ specification. It also constitutes a new approach to understanding morphogenesis, providing predictions on the population dynamics of cells with different genetic configurations during development
    corecore