1,721,002 research outputs found
Editorial: risks, threats, and conservation status of cetaceans in the Mediterranean and Black Seas
No full textEditorial: Risks, threats, and conservation status of cetaceans in the Mediterranean and
Black Sea
Studio della genotossicità di particelle di biossido di titanio, TiO2, in leucociti isolati di tursiope, Tursiops truncatus (Montagu, 1821)
No full textRIASSUNTO
Il crescente sviluppo delle tecnologie legate a produzione e impiego di nanoparticelle (materiali con almeno una dimensione compresa tra 1 e 100 nm) ha causato il proliferare di studi riguardanti le proprietà fisicochimiche, le possibili interazioni con i sistemi biologici e il conseguente impatto sull’ambiente e gli organismi viventi di questi materiali. Tuttavia, la maggior parte delle ricerche è focalizzata sui potenziali rischi per la salute umana, mentre ancora poche informazioni si hanno sull’impatto di questi materiali su specie a rischio, quali ad esempio i mammiferi marini.
Scopo di questo studio è stato valutare il potenziale effetto genotossico di particelle di biossido di titanio, TiO2 su leucociti isolati di delfini della specie Tursiops truncatus (Montagu, 1821).
L’imput di particelle di biossido di titanio in ambiente marino ha origine sia industriale che non, derivando sia direttamente che indirettamente da produzione e utilizzo di cosmetici e creme solari, dilavamento da discariche e liquami applicati ai suoli, deposizioni atmosferiche successive all’incenerimento dei rifiuti. Considerata la grande scala di produzione e utilizzo di questi materiali, è inevitabile che le nanoparticelle e i loro derivati si accumulino in ambiente acquatico, e possano esplicare il loro potenziale effetto genotossico sugli organismi viventi sia a breve che a lungo termine. In particolare, vanno monitorati e salvaguardati organismi a rischio come i mammiferi marini che, essendo predatori terminali al vertice delle reti trofiche, tendono ad accumulare alte concentrazioni di contaminanti e sono dunque soggetti ad elevato rischio tossicologico.
Per questi motivi i test condotti sono stati effettuati attraverso un approccio non invasivo, utilizzando leucociti isolati da sangue prelevato da cinque tursiopi in cattività presso il delfinario Oltremare srl di Riccione.
Sono state testate due forme di TiO2, caratterizzate da diversi reticoli cristallini: rutilo, di dimensioni < 5000 nm, e anatasio, di dimensioni < 25 nm. Per l’esposizione in vitro, le nanoparticelle sono state sospese in RPMI e sonicate per 30 minuti ad una frequenza di 35 kHz; i leucociti sono stati isolati attraverso un processo di lisi. L’esperimento ha previsto l’esposizione dei campioni di sangue di ogni animale in tre tempi (4, 24 e 48 ore) a tre dosi (20, 50 e 100 microg/ml) delle due forme di TiO2; un controllo per ogni tempo; due repliche per ogni combinazione di dose e tempo.
La valutazione dell’effetto genotossico è stata effettuata attraverso l’ Alkaline Single Gel Electrophoresis, o Comet Assay, mentre una valutazione dell’effetto citotossico è stata fatta utilizzando la colorazione con Trypan Blue.
I risultati mostrano un’elevata vitalità cellulare, compresa tra l'85% e il 100% anche dopo esposizione alle dosi più alte di TiO2, per tutti i tempi di esposizione. Un aumento significativo della migrazione di DNA (proporzionale al danno genetico) rispetto ai controlli è stato rilevato dopo 24 e 48 ore di esposizione alle dosi più elevate di rutilo e dopo 48 ore di esposizione a anatasio.
I risultati ottenuti indicano, per le dosi e i tempi testati, un effetto geno- e cito- tossico lieve delle particelle di TiO2 sui leucociti isolati, con genotossicità leggermente maggiore per il rutilo.
Da un confronto con gli studi preesistenti, i leucociti di tursiope risultano essere meno suscettibili all’esposizione a particelle di TiO2 rispetto a quelli umani, e più sensibili rispetto a quelli di pesci, organismi marini che non mostrano subire alcun effetto genotossico dopo esposizione a TiO2. Tuttavia, queste differenze potrebbero essere anche legate alle diverse dimensioni delle particelle utilizzate e ai diversi tipi di interazione con il mezzo in cui esse sono state disperse. Si rendono dunque necessarie ulteriori indagini per comprendere l’influenza dei fattori fisicochimici e delle interazioni tra nanoparticelle e biomolecole nel determinare gli effetti di questi materiali sugli esseri viventi.
ABSTRACT
Assessing genotoxicity of TiO2 particles in isolated bottlenose dolphin (Tursiops truncatus) leukocytes
The growing development of technologies based on the production and use of nanoparticles (materials with at least one dimension sized between 1 and 100 nm) is driving an increasing research interest for the interactions of nano-materials with living systems and their potential health hazard. Nevertheless, most of the results that have been published in recent years concern the risks associated with human exposure, while very few information has been produced about the environmental impact of nanomaterials and none of these regard endangered species, like marine mammals.
The aim of this study is to evaluate the genotoxic potential of titanium dioxide (TiO2 ) particles on isolated leukocytes of the bottlenose dolphin Tursiops truncatus (Montagu, 1821).
The input of nanoparticles in the aquatic environment is likely to be due both to industrial and non-industrial sources, deriving from the production and use of cosmetics and sun creams, sewer sources, leaching from landfill or soil applied sewage sludge and atmospheric sources from waste combustion. Given that nanotechnology industries plan large scale production, it is inevitable that these products and their by-products will reach and accumulate in the aquatic environments.
Endangered species, like marine mammals, that are subject to contaminants bioaccumulation and prone to pollution impacts, are to be monitored and protected preferentially.
For those reasons, our tests were made using a non-invasive approach, based on the use of cells isolated from blood taken from five specimens of bottlenose dolphin reared in captivity by Oltremare srl in Riccione in order to achieve a preliminary assessment of the susceptibility of a toothed cetacean to particulate TiO2 exposure.
Two different forms of TiO2 were tested: rutile, sized < 5000 nm, and anatase, sized < 25 nm. For in vitro exposure, nanoparticles were suspended in RPMI and sonicated at 35 kHz for 30’; leukocytes were isolated with the lysis procedure. Blood samples were exposed for 4, 24 and 48 hours to three different concentrations (20, 50 e 100 g/ml) of rutile and anatase, including a control.
Genotoxic effects were evaluated by the Alkaline Single Gel Electrophoresis or Comet Assay (detecting single and double DNA strand breaks, as well as alkali labile sites), and cells viability was evaluated by the Trypan Blue exclusion assay. Electron Microscopy was also used for assessing the aggregation of particles in experimental suspensions.
Results show a statistically significant increase of DNA fragmentation detected after 24 and 48 hours of exposure to the highest doses of rutile and after 48 hours of exposure to anatase. These data suggest a slight genotoxic effect of titanium dioxide particles on isolated dolphin leukocytes at the concentrations and times tested. Cell viability was always high, exceeding 85% after experimental exposures, suggesting the absence of a significant cytotoxic effect of TiO2.
Comparing our results with other studies, bottlenose dolphin leukocytes seem to be less susceptible to TiO2 than the human ones, but more than fish cells. However, the influence of particle size and/or interactions with the medium on experimental results cannot be excluded.
More studies are requested to investigate the influence of different physical-chemicals factors as well as of the interactions between nanoparticles and living systems in determining the effects of these materials on organisms
Use of chemical markers in the study of distribution range and population structure of large cetaceans = Uso de marcadores químicos en el estudio del rango de distribución y de la estructura de poblaciones de grandes cetáceos
Get PDFCetaceans have historically been object of heavy exploitation, and are still currently subject to different threats. For conservation and management purposes, most of the large cetacean populations have been categorized in stocks, considered as isolated and demographically independent management units. Many research techniques may contribute in the definition of these stocks, such as morphometric studies, mark recapture studies, genetics, satellite tracking. This thesis focuses on the development and application to cetacean populations of chemical markers of geographical origin and spatial movements. The main objective of the thesis is to evaluate the potentialities of chemical markers, such as stable isotopes and element concentrations, to investigate the patterns of distribution, the level of structuring and, when possible, the migration routes, of cetaceans populations. All these variables are essential to ensure the implementation of proper management measures and to guarantee the conservation of these animals. Three case studies were considered: the Eastern North Atlantic sperm whale (Physeter macrocephalus); the South Western Atlantic right whale (Eubalaena australis), and the North Atlantic fin whale (Balaenoptera physalus). δ15N, δ13C and δ18O values were analyzed in the dentinal growth layers of sperm whales from Denmark and NW Spain, in bone of right whales from Southern Brazil and Northern Argentina, and in bone of fin whales from W Iceland and NW Spain; concentrations of fluoride and selected metals (Zn, Pb, Ti, Sr, Cu) were analyzed in bone of fin whales from W Iceland and NW Spain. To establish the validity of each marker, the degree of compliance of each of the following four properties has been investigated: i) the basal levels of the chemical marker in the environment present significant gradients; ii) the chemical marker can be detected and measured in the tissues of whales; iii) the variability of the chemical marker within each population is moderate or, alternatively, it is predictable through measurable parameters, so that its effect can be taken into account; and iv) the values of the chemical marker in the body tissues reflect basal levels in a predictable and consistent manner. Each marker provided, at different levels, valuable information regarding the studied populations. Some difficulties emerged, connected with the complexity of the migratory cycles of whales, the possible intervention of homeostatic regulation mechanisms, and the characteristics of the tissues investigated. Nevertheless, results highlighted the occurrence of structuring within the North Atlantic sperm whale population, as well as within the South Western Atlantic right whale population, which are both currently considered as a single management unit. Moreover, results regarding the North Atlantic fin whale populations contributed to highlight the complexity of migration patterns and of the level of connectivity among the currently accepted stocks, challenging the proper definition of their limits and their degree of isolation within the basin. Some further research is recommended to deepen the knowledge about the North Atlantic fin whale population structure, as well as to investigate the levels of chemical markers in other tissues with different turnover characteristics, such as skin or baleen plates. Overall, the results obtained from the analyses performed in this thesis underline the power of chemical markers as a complementary tool to the traditional techniques used for investigating the structure and demography of cetaceans’ populations.Los cetáceos han estado y están actualmente sujetos a diferentes tipos de amenazas. Para su correcta gestión y conservación, la mayoría de las poblaciones de grandes cetáceos han sido categorizadas en “stocks”, considerados como unidades de gestión aisladas y demográficamente independientes. Muchas técnicas de investigación pueden contribuir en la definición de estas unidades, como los estudios morfométricos, los estudios de marcaje y recaptura, la genética y el seguimiento por satélite. El objetivo principal de esta tesis es evaluar las potencialidades de los marcadores químicos, tales como los isótopos estables y las concentraciones de algunos elementos, como herramientas para la investigación de los patrones de distribución y del nivel de estructuración de las poblaciones de cetáceos. Para ello, se han considerado tres casos modelo: el cachalote del Atlántico Nororiental, la ballena franca del Atlántico Suroccidental, y el rorcual común del Atlántico Norte. Se analizaron las proporciones isotópicas de δ15N, δ13C y δ18O en muestras de dientes de cachalote y de hueso de ballena franca y rorcual común; y las concentraciones de flúor y de metales pesados (Zn, Pb, Ti, Sr, Cu) en muestras de hueso de rorcual común. Cada marcador proporcionó, a diferentes niveles, información valiosa sobre las poblaciones estudiadas. Al interpretar los resultados, surgieron algunas dificultades relacionadas con la complejidad de los ciclos migratorios de los cetáceos, la posible intervención de mecanismos de regulación homeostática, y las características de los tejidos investigados. Sin embargo, los resultados destacaron cierto nivel de estructuración dentro de las poblaciones de cachalotes del Atlántico Norte y de ballenas francas del Atlántico Suroccidental, que actualmente están ambas consideradas como unidades de gestión únicas. Por otra parte, los resultados obtenidos en las poblaciones de rorcual común del Atlántico Norte contribuyeron a evidenciar la complejidad de los patrones migratorios y del nivel de conectividad entre sus poblaciones, desafiando la adecuada definición de sus límites y de su grado de aislamiento. En general, los resultados de la tesis destacan las potencialidades de los marcadores químicos como herramienta complementaria a las técnicas utilizadas tradicionalmente para la investigación de la estructura y demografía de las poblaciones de cetáceos
Vessel strikes as a pressure to marine biodiversity
Get PDFMarine mammals and other marine megafauna are subject to a variety of impacts related with human activities. Among those, the collisions with vessels (generally known as ship strikes, or vessel strikes) are a significant source of death and severe injuries for large cetacean species, such as fin whales or sperm whales, especially in areas that are subject to intense maritime traffic, such as the Mediterranean Sea. Other large marine vertebrates, such as sea turtles or whale sharks, are also affected by this issue, but limited information is available on the incidence of vessel strikes on species other than cetaceans. Within the EU waters, stranding networks are actively collecting information on the causes of death of cetaceans, seals, and sea turtles that strand along the coastlines, while a number of research projects, NGOs and research institutions that monitor live megafauna in the open sea to assess their abundance and distribution also collect information on the concurrent incidence of threats, such as those related to maritime traffic. This report addresses the issue of vessel strikes as a pressure to marine biodiversity, including information on monitoring, impacts, and potential mitigation measures, through a review of the scientific literature and reports produced within the international agreements in place to deal with marine mammal research and conservation, as well as by directly addressing the institutions dealing with strandings and live megafauna monitoring through a dedicated questionnaire on this issue.JRC.D.2 - Ocean and Wate
Monitoring of strandings in European waters: state of play
Get PDFMarine mammals and other marine megafauna are subject to a variety of impacts related with human activities. Within the EU waters, stranding networks are actively collecting information on the causes of death of cetaceans, seals, and sea turtles that strand along the coastlines. However, despite the effort made by international agreements to coordinate stranding networks within the European basins and standardise their operational procedures, large differences still exist among European stranding networks. This report addresses this issue with the aim to identify the level of structuring, operational approaches, data collection standards and data pathways, across these networks, through a review of the scientific literature and reports produced within the international agreements in place to deal with marine mammal research and conservation, as well as by directly addressing the institutions dealing with strandings through an online survey. The survey was designed to assess to which extent data are collected, how (i.e., use of dedicated protocols), and where they are stored (i.e., use of common repositories), with a specific focus on the assessment of three major anthropic impacts (marine litter ingestion, vessel strikes and fisheries interactions), to identify the major gaps and needs for improvement in data collection and reporting at EU level.JRC.D.2 - Ocean and Wate
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
