1,720,971 research outputs found
The haemocytes of the marine bivalve Mytilus galloprovincialis as a model for studying the impact of NP on innate immunity
No full textIn this PhD thesis, the effects and interactions of nanoparticles-NPs with the marine mussel Mytilus galloprovincialis were investigated through several exposure pathways, implying the use of distinct methods, in vitro and in vivo.
In a first part, in vitro model served to determine the functional immune responses upon short term exposure of Mytilus hemocytes using microscopy and spectrophotometric methods. In this line, several NPs were tested in suspensions in ASW-artificial seawater and hemolymph serum-HS and showed a general activation of the immune response of Mytilus hemocytes and hemolymph components (Chapter 1 and 2). The results obtained contribute to understand the mechanisms of actions of NPs due to their nature, size and coating and also underline the importance to consider the exposure medium in the characterization and exposure experiment. Complementary experiments were carried on the change in morphology after interactions with NPs, attesting for peculiar activation of the hemocytes according to the NPs types.
In a second part, the effects of NPs were also investigated at different scale of the organism (from cell to tissues) using in vivo experiments, in which mussels were exposed for several days to selected NPs, before determining immune parameters and related parameters.
Mussels exposed in vivo to nanoceria-nCeO2 (Chapter 3), showed specific immunomodulatory and antioxidant effects at different levels of biological organization in the absence of Cerium tissue accumulation.
In addition, the microbiota present in hemolymph of mussels has shown to be affected upon nanotitanium dioxide-nTiO2 exposure (Chapter 4). The results attested for complex interactions between immune cells, the hemocytes, activated in presence of nTiO2, and created an unfriendly medium in hemolymph, that likely lead to affect the most sensible commensal bacterial communities present.
Finally, newly design experiments were performed to investigate innate immune memory/training in Mytilus (Chapter 5). Growing proofs have shown that even relying on innate response, molluscs could present a certain type of memory and recall a response upon a second encounter, also called innate immune memory. Results showed that mussels can mount a more effective response upon re-exposure to a stimulus, PS-NH2 in the present case, to avoid to trigger further stress/damages repeatedly
Soluble mediators of innate immunity in annelids and bivalve mollusks: A mini-review
No full textAnnelids and mollusks, both in the superphylum of Lophotrochozoa (Bilateria), are important ecological groups, widespread in soil, freshwater, estuarine, and marine ecosystems. Like all invertebrates, they lack adaptive immunity; however, they are endowed with an effective and complex innate immune system (humoral and cellular defenses) similar to vertebrates. The lack of acquired immunity and the capacity to form antibodies does not mean a lack of specificity: invertebrates have evolved genetic mechanisms capable of producing thousands of different proteins from a small number of genes, providing high variability and diversity of immune effector molecules just like their vertebrate counterparts. This diversity allows annelids and mollusks to recognize and eliminate a wide range of pathogens and respond to environmental stressors. Effector molecules can kill invading microbes, reduce their pathogenicity, or regulate the immune response at cellular and systemic levels. Annelids and mollusks are “typical” lophotrochozoan protostome since both groups include aquatic species with trochophore larvae, which unite both taxa in a common ancestry. Moreover, despite their extensive utilization in immunological research, no model systems are available as there are with other invertebrate groups, such as Caenorhabditis elegans or Drosophila melanogaster, and thus, their immune potential is largely unexplored. In this work, we focus on two classes of key soluble mediators of immunity, i.e., antimicrobial peptides (AMPs) and cytokines, in annelids and bivalves, which are the most studied mollusks. The mediators have been of interest from their first identification to recent advances in molecular studies that clarified their role in the immune response
Impact of ocean warming on early development of the Mediterranean mussel Mytilus galloprovincialis: Effects on larval susceptibility to potential vibrio pathogens
No full textIn a global change scenario, ocean warming and pathogen infection can occur simultaneously in coastal areas, threatening marine species. Data are shown on the impact of temperature on early larvae of the Mediterranean mussel Mytilus galloprovincialis. Increasing temperatures (18-20-22 °C) altered larval phenotypes at 48 hpf and affected gene expression from eggs to 24 and 48 hpf, with shell biogenesis related genes among the most affected. The effects of temperature on larval susceptibility to infection were evaluated using Vibrio coralliilyticus, a coral pathogen increasingly associated with bivalve mortalities, whose ecology is affected by global warming. Malformations and mortalities at 48 hpf were observed at higher temperature and vibrio concentrations, with interactive effects. In non-lethal conditions, interactions on gene expression at 24 and 48 hpf were also detected. Although temperature is the main environmental driver affecting M. galloprovincialis early larvae, warming may increase the susceptibility to vibrio infection, with consequences on mussel populations
Microplastic exposure and effects in aquatic organisms: A physiological perspective
No full textThe impact of microplastics (MPs) on aquatic life, given their ubiquitous presence in the water compartment, represents a growing concern. Consistently, scientific knowledge is advancing rapidly, although evidence on actual adverse effects is still highly fragmented. This paper summarizes the recent literature on MP impacts on aquatic organisms in an attempt to link routes of uptake, possible alterations of physiological processes, and outcomes at different levels of biological organization. Animal feeding strategies and MP biodistribution is discussed, alongside with relevant effects at molecular, cellular, and systemic level. Pathways from animal exposure to apical physiological responses are examined to define the relevance of MPs for animal health, and to point out open questions and research gaps. Emphasis is given to emerging threats posed by leaching of plastic additives, many of which have endocrine disruption potential. The potential role of MPs as substrates for microorganism growth and vehicle for pathogen spreading is also addressed
Methodological Approaches To Assess Innate Immunity and Innate Memory in Marine Invertebrates and Humans
No full textAssessing the impact of drugs and contaminants on immune responses requires
methodological approaches able to represent real-life conditions and predict long-term
effects. Innate immunity/inflammation is the evolutionarily most widespread and conserved
defensive mechanism in living organisms, and therefore we will focus here on
immunotoxicological methods that specifically target such processes. By exploiting the
conserved mechanisms of innate immunity, we have examined the most representative
immunotoxicity methodological approaches across living species, to identify common
features and human proxy models/assays. Three marine invertebrate organisms are
examined in comparison with humans, i.e., bivalve molluscs, tunicates and sea
urchins. In vivo and in vitro approaches are compared, highlighting common
mechanisms and species-specific endpoints, to be applied in predictive human and
environmental immunotoxicity assessment. Emphasis is given to the 3R principle of
Replacement, Refinement and Reduction of Animals in Research and to the
application of the ARRIVE guidelines on reporting animal research, in order to
strengthen the quality and usability of immunotoxicology research data
First insights into bacterial and microalgal endosymbiont communities of various coral morphotypes from Maldives
No full textThe Maldivian Archipelago is home to valuable coral reefs that have been extensively studied for their ecological diversity. However, the diversity of the microbiome in Maldivian corals remains largely unexplored. In this study, the microbiota compositions (including both algal endosymbionts and bacteria) were investigated for the first time across various coral morphotypes sampled in May 2022 from four Maldivian atolls (Ari, North Malé, South Malé, and Rasdhoo). Coral and gorgonian specimens were collected via scuba diving at reef sites located on both ocean-exposed reefs and lagoon sites, across various depths (0–40 m). Surface seawater samples were also collected near coral assemblages. Metabarcoding analyses were performed, targeting the 16S rRNA gene to assess bacterial composition, and the Internal Transcribed Spacer 2 (ITS2) rRNA region to evaluate microalgal endosymbiont diversity. Generally, the bacterial communities associated with corals exhibited significant diversity, which was primarily influenced by coral morphotype rather than depth or geographic location. These communities were also markedly different when compared to those found in seawater. The three most abundant bacterial taxa in coral samples were Proteobacteria (ranging from 10 to 95%), Bacillota (formerly known as Firmicutes, ranging from 5 to 10%), and Planctomycetota (ranging from < 1–30%). Most Symbiodiniaceae belonged to the genera Cladocopium-C and Durusdinium-D (> 90%), while host specificity was observed for variant types. Overall, this study provides first insights into the structure of Maldivian coral microbiota, which could be crucial for monitoring the health of local coral populations and predicting the potential impacts of changing environmental conditions in the region
Shift in Immune Parameters After Repeated Exposure to Nanoplastics in the Marine Bivalve Mytilus
Full text linkBivalves are widespread in coastal environments subjected to a wide range of environmental fluctuations: however, the rapidly occurring changes due to several anthropogenic factors can represent a significant threat to bivalve immunity. The mussel Mytilus spp. has extremely powerful immune defenses toward different potential pathogens and contaminant stressors. In particular, the mussel immune system represents a significant target for different types of nanoparticles (NPs), including amino-modified nanopolystyrene (PS-NH2) as a model of nanoplastics. In this work, the effects of repeated exposure to PS-NH2 on immune responses of Mytilus galloprovincialis were investigated after a first exposure (10 μg/L; 24 h), followed by a resting period (72-h depuration) and a second exposure (10 μg/L; 24 h). Functional parameters were measured in hemocytes, serum, and whole hemolymph samples. In hemocytes, transcription of selected genes involved in proliferation/apoptosis and immune response was evaluated by qPCR. First exposure to PS-NH2 significantly affected hemocyte mitochondrial and lysosomal parameters, serum lysozyme activity, and transcription of proliferation/apoptosis markers; significant upregulation of extrapallial protein precursor (EPp) and downregulation of lysozyme and mytilin B were observed. The results of functional hemocyte parameters indicate the occurrence of stress conditions that did not however result in changes in the overall bactericidal activity. After the second exposure, a shift in hemocyte subpopulations, together with reestablishment of basal functional parameters and of proliferation/apoptotic markers, was observed. Moreover, hemolymph bactericidal activity, as well as transcription of five out of six immune-related genes, all codifying for secreted proteins, was significantly increased. The results indicate an overall shift in immune parameters that may act as compensatory mechanisms to maintain immune homeostasis after a second encounter with PS-NH2
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
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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