1,720,970 research outputs found
Nature-based and bioinspired solutions for coastal protection: an overview among key ecosystems and a promising pathway for new functional and sustainable designs
No full textCoastal erosion is occurring at a faster rate than in the past. The adverse impacts are not negligible at environmental, economic, and sociocultural levels. Hence, coastal protection is currently seen as an emerging need to counteract erosion impacts and their many negative effects on worldwide ecosystems. In this regard, natural systems and their organisms represent a complex system of solutions that can efficiently create and/or inspire the development of natural, sustainable, and cutting-edge coastal barriers. Coastal ecosystems, such as coral reefs, oyster reefs, mangroves, saltmarshes, seagrasses, and polychaete reefs, act as a natural barrier for destructive waves and wind forces.Moreover, living organisms have evolved unique strategies to withstand their environmental hydrodynamic loadings. This review intends to provide an overview regarding natural systems and related nature-based and bioinspired strategies in the specific field of coastal protection, describing the state of
the art, methods, processes, and tools, as well as delineating a promising pathway for new functional and sustainable designs
Roe enhancement of Paracentrotus lividus: Nutritional effects of fresh and formulated diets
Full text linkSea urchin gonads are exploited both for gastronomic and scientific purposes; thus, the production of large and mature gonads is essential. Natural populations of the Mediterranean Sea urchin Paracentrotus lividus are subject to increasing fishing ef- forts, due to continuous intensification of consumptions. Aquaculture practices may represent an answer, but the availability of artificial feeds accelerating the produc- tion of high-quality gonads in terms of size, taste, colour, firmness, maturity and via- bility of gametes is critical to boost the productions. The accessibility of cheap and effective feeds promoting the fattening of gonads and the quality of gametes is still a bottleneck slowing down the expansion of echinoculture practices. This investiga- tion is aimed at enabling the development of this strategic sector, by comparing the dietetic effects of fresh foods and a commercial feed for aquaculture, to four newly formulated feeds. The protein contents of diets were strongly related to the GSIs. The abundance of fatty acids appeared inversely related to the viability of embryos and abnormalities of larvae. The features of an ideal diet for this sea urchin were defined, based on the results of experimental trials, and the need for increasing levels of plant-derived proteins during the grow-out period was demonstrated
Coupling feeding activity, growth rates and molecular data shows dietetic needs of Ciona robusta (Ascidiacea, Phlebobranchia) in automatic culture plants
Full text linkThe sea squirt Ciona robusta is a model organism characterized by a transparent body, exhibiting peculiar physiologic and evolutionary characters. In vitro fertilization and breeding of sea squirts is possible, in order to preserve consistent genetic pools. However, some aspects of its biology, as the feeding efficiency according to diet quantity and quality, are still scarcely known. Here we test the effects of three experimental diets on survival and growth, to detect physiological and molecular responses to various types of alimentary suspended particles and the effects of feed concentrations. We also aimed at determining rearing conditions able to limit handling operations, save artificial seawater and control water pollution. Molecular analyses of growth-related genes were performed to detect stressful effects due to feed quality and quantity. A strong effect of doses was highlighted, but water pollution may represent a major concern. A compound diet containing both live algae and non-live particles of a correct size is indispensable to assure development, low stress and high survival rates. Overall, our findings suggest protocols for an easier rearing of Ciona robusta in the laboratory, increasing the potentialities of these organisms as models for research
Analysis of the coding sequences of clownfish reveals molecular convergence in the evolution of lifespan
Full text linkBackground: Standard evolutionary theories of aging postulate that reduced extrinsic mortality leads to evolution of longevity. Clownfishes of the genus Amphiprion live in a symbiotic relationship with sea anemones that provide protection from predators. We performed a survey and identified at least two species with a lifespan of over 20 years. Given their small size and ease of captive reproduction, clownfish lend themselves as experimental models of exceptional longevity. To identify genetic correlates of exceptional longevity, we sequenced the transcriptomes of Amphiprion percula and A. clarkii and performed a scan for positively-selected genes (PSGs). Results: The PSGs that we identified in the last common clownfish ancestor were compared with PSGs detected in long-lived mole rats and short-lived killifishes revealing convergent evolution in processes such as mitochondrial biogenesis. Among individual genes, the Mitochondrial Transcription Termination Factor 1 (MTERF1), was positively-selected in all three clades, whereas the Glutathione S-Transferase Kappa 1 (GSTK1) was under positive selection in two independent clades. For the latter, homology modelling strongly suggested that positive selection targeted enzymatically important residues. Conclusions: These results indicate that specific pathways were recruited in independent lineages evolving an exceptionally extended or shortened lifespan and point to mito-nuclear balance as a key factor
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Re-defining the Concept of Model Species: An Experimental Approach on a Range of Marine Animals
Full text linkScientific research extensively uses model organisms to address biological, ecological and evolutionary issues. Research employs a limited variety of organisms, ranging from bacteria to complex metazoans, to answer scientific questions and investigate natural aspects. We define “Model Organisms” this small fraction of the biological biodiversity. Generally, they are a simplified tractable system used to study larger scientific questions and to answer complex problems. Researchers expect that results obtained through experiments on these MOs will be applicable to other, more complex, organisms, or to complex communities and ecosystems. Model organisms are sometimes a scarcely representative sample of the global physiological, biochemical and genetic biodiversity and the answers that they can provide could not be easily applicable and transferred to other species. This Ph.D. thesis aims at re-defining the concept of “model species” on an objective point of view. I analysed a standard range of common characteristics that can describe and rank selected model organisms on the basis of their unique features, advantages and disadvantages. I have taken into consideration various “practical” features, such as size and feeding, their reproduction and the optimization of the culture techniques; their use in some scientific fields, such as chemical ecology, stress responses and apoptosis, and the availability of molecular tools and sequenced genomes. A set of laboratory analyses was applied to test the power of selected species to answer our questions and an arbitrary score was assigned to each species for each parameter according to our results and to the data available in scientific literature. The information collected was used to objectively rank the considered model organisms, for improving future experimental approaches and indicate a possible strategy to choose adequate models for selected research
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Distribution of Toxigenic <i>Halomicronema</i> spp. in Adjacent Environments on the Island of Ischia: Comparison of Strains from Thermal Waters and Free Living in <i>Posidonia Oceanica</i> Meadows
No full textOrganisms adaptable to extreme conditions share the ability to establish protective biofilms or secrete defence toxins. The extracellular substances that are secreted may contain monosaccharides and other toxic compounds, but environmental conditions influence biofilm characteristics. Microorganisms that are present in the same environment achieve similar compositions, regardless of their phylogenetic relationships. Alternatively, cyanobacteria phylogenetically related may live in different environments, but we ignore if their physiological answers may be similar. To test this hypothesis, two strains of cyanobacteria that were both ascribed to the genus Halomicronema were isolated. H. metazoicum was isolated in marine waters off the island of Ischia (Bay of Naples, Italy), free living on leaves of Posidonia oceanica. Halomicronema sp. was isolated in adjacent thermal waters. Thus, two congeneric species adapted to different environments but diffused in the same area were polyphasically characterized by microscopy, molecular, and toxicity analyses. A variable pattern of toxicity was exhibited, in accordance with the constraints imposed by the host environments. Cyanobacteria adapted to extreme environments of thermal waters face a few competitors and exhibit a low toxicity; in contrast, congeneric strains that have adapted to stable and complex environments as seagrass meadows compete with several organisms for space and resources, and they produce toxic compounds that are constitutively secreted in the surrounding waters
First evidence of Halomicronema metazoicum (Cyanobacteria) free-living on Posidonia oceanica leaves
No full textCyanobacteria contribute to the ecology of various marine environments, also for their symbioses, since some of them are common hosts of sponges and ascidians. They are also emerging as an important source of novel bioactive secondary metabolites in pharmacological (as anticancer drugs) and biotechnological applications. In the present work we isolated a cyanobacteria in a free-living state from leaves of the seagrass Posidonia oceanica leaves. This newly collected strain was then cultivated under two laboratory conditions, and then characterized by combining morphological observation and molecular studies based on 16S rRNA gene sequences analysis. The strain showed 99% pairwise sequence identity with Halomicronema metazoicum ITAC101, never isolated before as a free-living organisms, but firstly described as an endosymbiont of the Mediterranean marine spongae Petrosia ficiformis, under the form of a filamentous strain. Further studies will investigate the actual role of this cyanobacterium in the leaf stratum of P. oceanica leaves, given its demonstrated ability to influence the vitality and the life cycle of other organisms. In fact, its newly demonstrated free-living stage, described in this study, indicate that Phormidium-like cyanobacteria could play important roles in the ecology of benthic and planktonic communities.</div
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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