1,721,036 research outputs found
Immunotoxic effects of organotin compounds in Tapes philippinarum
No full textSince 1970 in Italy the cultivation of Tapes philippinarum has experienced a rapid expansion in the lagoons and along te coasts of the Northern Adratic Sea, with important economic and social implications. This type of bivalve culture, however, has developed without a precise plan and the necessary technical assistance. Over the past few years, in parallel with the diffusion of this and other types of mollusc cultures the need to acquire a better knowledge and control of the lagoon environment has arisen. A remarkable problem is the superposition of areas with intense maritime activity and agricultural exploitation with those of mollusc cultivation. Among the main pollutants concerning these areas organotin compounds (OTC) represent one of the most harmful group of substances both for mollusc cultivation and human health, since bivalves are filter-feeding organisms which rapidly bioaccumulate the environmental contaminants. With the aim to study the effects of OTC - already reported to be immunotoxic in mammals - in T. philippinarum, we have investigated whether they exert an immunosuppressant role also on in vitro yeast phagocytosis by haemocytes of this species. The phagocytic index is significantly reduced by OTC in an irreversible manner and depends on concentration and lipophilic affinity, but neither cell mortality nor cytolysis occur. For butyltin compounds, which are used as biocides in antifouling paints, the order of inhibition is TBT > DBT > MBT (p TPTA > TPTH (p < 0.05 for 0.01 μM TPTC and for 0.05 μM TPTA and TPTH). As this test is rapid and easily reproducible, it can effectively applied together with other ecotoxicological bioassays in evaluation studies of OTC environmental impact
Settlement, post-larval growth and gonadal development of Chlamys glabra L. in an off-shore site of the Northern Adriatic Sea (Italy).
No full textA study on the settlement of Pectinidae, mainly of Chlamys glabra, on artificial collectors (“onion-bags”) was carried on in a mussel culture plant, one mile off-shore in the Northern Adriatic Sea, northwards the lagoon of Venice. Samplings were collected every three months, from August 2005 since August 2006. Each sampling consisted of twenty bags suspended at different depths (5m, 7m, 9m, 11m, 13m).
The peak of settlement of Pectinidae was in summer at -13m (average 119 individuals m-2 day-1). Very small unidentified Pectinidae were the most abundant component, mainly close to sea bottom; Chlamys varia, C. glabra and Chlamys proteus settled almost uniformly at any depth. The summer-autumn settlement was mostly represented by C. glabra and C. proteus, that preferred to settle at -11m and -13m (average 51 and 87 ind m-2 day-1, respectively). During winter only little quantities of very small unidentified Pectinidae settled. A. opercularis was collected, even if not very abundant (<15 ind m-2 day-1), in the spring sampling; it preferred collectors toward the bottom, particularly those at -11m (average 14 ind m-2 day-1).
At any seasons, the multivariate statistical analysis confirmed the preference of different identified species of Pectinidae for settling near the sea bottom.
From November to April, in order to assess post-larval growth, bimonthly measures of the length of some specimens of C. glabra, collected in the same site during the previous summer and kept in experimental holders, were carried on. The growth was slow between November and February, showing a mean increase of 2mm between November and December and only 1mm between December and February. In April, the mean size increased up to 2.4cm (maximum 3.6cm).
The gonadal development of C. glabra was followed from October to April in specimens from the same holders. The gonadal maturity was reached after about eight months, at length of 4 cm. The scallops did not show presence of any parasites.
In the experimental site, C. glabra seemed to be suitable for farming; this practice should reduce the fishing effort, that is currently hazarding toward depletion of the natural beds of scallops, linked to impact on the benthic communities in the Northern Adriatic sea
Applicazione della tecnica autometallografica per lo studio di accumulo e disaccumulo del rame nei molluschi bivalvi eduli della specie Tapes philippinarum
No full textReproductive cycle of the mussel (Mytilus galloprovincialis Lmk.) in Venice Lagoon (North Adriatic).
No full textThe reproductive cycle of Mytilus galloprovincialis Lmk cultured in Venice Lagoon has been studied from 1979 to 1982. Histology of the gonads shows that the gametes are ripe from September to May, when several spawnings occur with a peak at the end of winter (January -February). Reproductive activity is quiescent between July and August but release of gametes is possible even in summer, if only to a limited extent
EFFECTS OF TRIBUTYLTIN CHLORIDE ON THE EMBRYONIC DEVELOPMENT OF THE SEA URCHIN PARACENTROTUS LIVIDUS (LMK).
No full textTributyltin (TBT) has been used extensively for almost 30 years in marine antifouling paints as a biocide. During this period hazardous levels of TBT and of its less toxic products of degradation, i.e. dibutyltin (DBT) and monobutyltin (MBT), were reached in estuaries and coastal water-sediment ecosystems in various parts of the world. Concern about the negative effects of low concentrations of butyltin compounds in the marine environment, recently as a lot of severe toxic effects on marine invertebrates. These effects were demonstrated mostly in molluscs, in which TBT exposure induced shell thinning, imposex and block of the embryonic development. In tunicates, immunodepression and embryotoxicity were used as indexes of butyltin pollution. Nothing is up to date known about the effects of these compounds on echinoderms. Therefore, we set up a procedure to reveal the effects and the mechanism of action of butyltin compounds on the embryonic development of the sea urchin Paracentrotus lividus. Embryos were obtained in laboratory by cross-fertilization and their development from post-fertilization to pluteus was followed in vivo after incubation with different exposure concentrations (0.1, 0.5, 1, 5, 10 μg l-1). We examined various developmental indexes, i.e. survival, frequency of developmental stages 24 and 48 hs after fertilization, embryonic growth and frequency of larval abnormalities 48 hs after fertilization. Morphological observations were also carried out under light and electron microscopies. Results show that embryotoxic effects occur in the presence of butyltin compounds in a dose-dependent manner. The exposed embryos generally suffer develpmental delay. Growth reduction of plutei, regularly increases as TBT concentration rises and becomes highly significant (p<0.001) at 1 μg l-1. At the same TBT dose plutei exhibit clear disturbance of the skeleton symmetry: the post-oral rods appear particularly short and/or folded. A very significant (p<0.001) interruption at the morula stage is observed begining from 5 μg l-1 TBT. Abnormal morula appear formed by irregular blastomeres from which many cytoplasmatic blisters jut towards a large space between the cells and the fertilization membrane. We suggest an influence of butyltin compounds with calcium homeostasis both in the microtubule polymerization during the cleavage stages and in calcification and organization of pluteus skeleton
Stress meccanico in esemplari sottotaglia di bivalvi eduli: Chamelea gallina
No full textThe effects of repeated disturbance, such as that caused by mechanical fishing systems tipically used in Northern Adriatic, was simulated in a laboratory experiment on the venus clam Chamelea gallina (Bivalvia: Veneridae). Under-sized clams were subjected to experimental shaking, and changes in physiological and behavioural responses were evaluated by determining adenylate energy charge, survival in air time, reburrowing time, and shell damage level
Invertebrati marini come bioindicatori di inquinanti stannorganici: studi di embrio- e immunotossicità
No full textNegli ultimi anni i composti stannorganici hanno destato un crescente interesse in campo biologico per gli elevati effetti tossici di cui sono responsabili. Essi vengono utilizzati quali componenti di vernici antivegetative per scafi di imbarcazioni, moli e reti da pesca, e come pesticidi anticercosporiosi della barbabietola da zucchero in agricoltura. Visto il loro uso incontrollato e non regolamentato, la loro presenza nelle acque e nei sedimenti costieri è da ritenersi certa. La stabile presenza di questi composti nell’ecosistema marino rappresenta un elevato fattore di rischio, in quanto essi sono in grado di provocare effetti deleteri negli organismi già a basse concentrazioni e, inoltre, sono soggetti ad un rapido bioaccumulo con effetti tossici a lungo termine. Nei vertebrati gli organi-bersaglio dei butil- e trifenilstannici sono il cervello, il fegato e gli organi linfatici. I molluschi, sia bivalvi che gasteropodi, esposti a queste sostanze subiscono decalcificazione della conchiglia e vanno incontro ad una riduzione della fertilità. Recentemente è stato dimostrato anche un effetto teratogeno di questi composti nei mammiferi e nei pesci. In questo studio sono state utilizzate specie ampiamente diffuse di molluschi (Mytilus galloprovincialis, Tapes philippinarum), ascidiacei (Botryllus schlosseri, Styela plicata) ed echinodermi (Paracentrotus lividus), come bioindicatori di inquinamento da stannorganici nell’ambiente marino costiero con lo scopo di indagare gli effetti immuno- ed embriotossici di tali contaminanti, proponendo anche metodi di indagine facilmente riproducibili. La scelta di queste specie si è basata sull’elevata sensibilità agli stannorganici dimostrata dai tunicati in precedenti ricerche, sull’importanza economica e il rischio per la salute umana relativi ai bivalvi e infine sulla particolare affidabilità e sensibilità dei ricci di mare come modello sperimentale nello studio degli effetti di xenobiotici sula riproduzione e sullo sviluppo. Abbiamo valutato gli effetti immunotossici degli stannorganici su processi quali la fagocitosi (inibizione dell’indice di fagocitosi, del “burst” respiratorio e delle attività enzimatiche associati alla fagocitosi) approntando opportuni saggi in vitro, mentre gli effetti embriotossici (arresto, rallentamenti, anomalie dello sviluppo) sono stati valutati trattando gli embrioni in diversi momenti dello sviluppo, per diversi periodi di tempo e con varie concentrazioni di stannorganici. I risultati ottenuti indicano che gli stannorganici determinano effetti tossici subletali dose- e tempo-dipendenti nonché strettamente correlati alle loro proprietà lipofiliche. Il meccanismo d’azione di tali composti appare complesso. Da un alto, esso comporta una forte interazione con l’omeostasi cellulare del calcio, mediante inibizione dell’attività della Ca2+-ATPasi di membrana calmodulina-dipendente, aumento del calcio intracellulare e depolimerizzazione delle proteine del citoscheletro. Dall’altro lato, il meccanismo d’azione comporta anche un’interazione oligomicina-simile con la fosforilazione ossidativa mitocondriale, mediante inibizione degli enzimi della catena respiratoria osservabile sia dal punto di vista morfologico, come progressivo accumulo di stannorganici sulle creste mitocondriali dei blastomeri embrionali, sia dal punto di vista citochimico e spettrofotometrico, come inibizione della produzione di radicali dell’ossigeno durante la fagocitosi. Si ritiene che questi studi potranno contribuire alla definizione di test biologici affidabili, sensibili e specifici, in grado di essere applicati in ricerche ambientali accanto ai metodi chimici analitici molto precisi e tuttavia costosi che richiedono lunghi e delicati processi preliminari di estrazione
Sedimenti lagunari: prove di tossicità su embrioni di riccio di mare Paracentrotus lividus. Biol. Mar. Medit., 4 (1) : 632-636.
No full textAn experimental model was tested to assess the toxicity of sediment elutriates from the Lagoon of Venice on embryos of sea urchin (Paracentrotus lividus, Echinodermata), and to relate the biological effects to contaminant levels in aqueous extracts
Preliminary results of a field study on some stress-related parameters in Tapes philippinarum naturally infected by the protozoan Perkinsus.
No full textThe aim of the present work was to investigate the possible use of the clam Tapes philippinarum - a filter-feeding bivalve living on soft bottoms - in the monitoring of sediment pollution in the Lagoon of Venice (North-East Italy). To this end, two clam populations, exposed to different environmental conditions (a relative clean site and an industrial polluted area), have been monitored for the prevalence of the protozoan parasite Perkinsus sp. as well as for several biological parameters commonly used as determinants of contaminants exposure. First
results showed a low prevalence, higher in the clean site, but a very diffuse distribution of the parasite throughout the two populations. Nevertheless, greater digestive cells height and longer lysosomal latency time were observed in clams from the clean area. As for the physiological stress-related parameters, even if clearance rates were always higher in these clams, scope for growth values indicated a more complicated biological response
Effects of mechanical stress in under-sized clams, Tapes philippinarum: a laboratory approach.
No full textThe present study is a first attempt at evaluating the effects of repeated disturbance,
such as that caused by mechanical fishing systems, on the target species, Tapes
philippinarum, intensively exploited in the Lagoon of Venice (North-East Italy). In
particular, in free-access fishing grounds, detrimental effects of dredging may be suffered
by under-sized clams, which are disturbed by fishing tools many times throughout their
lives before they are collected. Similar mechanical stress conditions are experienced by
T. philippinarum in licensed areas, where they are farmed in aquaculture conditions and
undergo the harmful impact of hydraulic dredging. To evaluate the effects of short-term
mechanical stress, under-sized clams were subjected to experimental shaking in the
laboratory, and detrimental effects on their well-being were investigated by applying the
biomarker approach. Changes in physiological, biochemical and behavioural responses
were evaluated by determining scope for growth, adenylate energy charge, survival in air
time, reburrowing time, and shell damage level. Responses highlighted general worsening
in clam condition as mechanical stress increased. Among the various measurements,
survival in air and reburrowing time appeared particularly suitable as indices,
their responsiveness and applicability suggesting their use in assessing mechanical stress
due to dredging in field conditions
- …
