Molecular detection of a potentially toxic diatom species

A few diatom species produce toxins that affect human and animal health. Among these, members of the Pseudo-nitzschia genus were the first diatoms unambiguously identified as producer of domoic acid, a neurotoxin affecting molluscan shell-fish, birds, marine mammals, and humans. Evidence exists indicating the involvement of another diatom genus, Amphora, as a potential producer of domoic acid. We present a strategy for the detection of the diatom species Amphora coffeaeformis based on the development of species-specific oligonucleotide probes and their application in microarray hybridization experiments. This approach is based on the use of two marker genes highly conserved in all diatoms, but endowed with sufficient genetic divergence to discriminate diatoms at the species level. A region of approximately 450 bp of these previously unexplored marker genes, coding for elongation factor 1-a (eEF1-a) and silicic acid transporter (SIT), was used to design oligonucleotide probes that were tested for specificity in combination with the corresponding fluorescently labeled DNA targets. The results presented in this work suggest a possible use of this DNA chip technology for the selective detection of A. coffeaeformis in environmental settings where the presence of this potential toxin producer may represent a threat to human and animal health. In addition, the same basic approach can be adapted to a wider range of diatoms for the simultaneous detection of microorganisms used as biomarkers of different water quality levels

First isolation of Salmonella enterica serovar Napoli from wild birds in Italy

AbstractSalmonella enterica serovar Napoli (S. Napoli) is an emerging serovar in Italy. It accounts for 2-4% of all serovars isolated from human infections. The zoonotic origin of this serovar is still unknown and this makes difficult to apply any control intervention. We report here the isolation of S. Napoli from a river nightingale (Cettia cetti, Temminck 1820) which represents the first description of this serovar from wild birds. This finding adds knowledge to the ecology of S. Napoli and addresses further studies aimed to assess the epidemiologic link between S. Napoli isolated from wild birds, food, environmental sources and human infections.

Indici per la valutazione della qualit? ecologica dei laghi

Collection of methods to evaluate lake quality using biological element

Diatoms as indicators of transitional water ecosystems

Le diatomee sono organismi ubiquitari presenti in tutti gli ambienti acquatici, date le loro caratteristiche vengono utilizzate come indicatori biologici per la tutela delle acque tanto da essere una delle comunità biotiche richieste dalla Direttiva Quadro 2000/60/CE in materia di acque. Le acque di transizione sono ambienti molto diffusi nella regione mediterranea, la scarsità di conoscenze che sino ad ora le hanno caratterizzate ha finora inciso negativamente sulla conservazione, la gestione e gli interventi di ripristino di questi ecosistemi. Obbiettivo di questa ricerca è stato quello di approfondire le conoscenze degli ecosistemi acquatici di transizione attraverso lo studio delle specie diatomiche e valutare la loro potenzialità come descrittrice ed indicatrice di tali ambienti . L’indagine è stata condotta sulle comunità diatomiche, sulle variabili ambientali, sui parametri chimici e chimico fisici delle acque e sono state analizzate le loro potenziali correlazioni. Sono state esaminati un totale di 28 siti rappresentativi delle diverse tipologie di acque di transizione presenti lungo la costa Tirrenica tra il Lazio e la Toscana: foci fluviali, foci di canali,e laghi costieri. Il campionamento è stato eseguito sulla componente biologica, sulla matrice acquosa ed inoltre sono stati rilevati i principali parametri ambientali. Sono state identificate un totale di 219 tra specie e variètà diatomiche. Tra queste, è stata ritovata una specie potenzialmente tossica, Amphora coffeaeformis Le comunità identificate ed i risultati ottenuti dalle analisi abiotiche, sono stati trattati statisticamente attraverso l’Analisi dei Cluster, l’Analisi delle Componenti Principali e l’Analisi Canonica delle Corrispondenze. I risultati hanno mostrato come le comunità si aggreghino per tipologia di corpo idrico, cosi come le variabili ambientali, chimico e chimico fisiche. Dall ‘Analisi Canonica delle Corrispondenze. è stato possibile individuare una significativa correlazione tra le componenti chimiche e quelle biologiche. I principali fattori abiotici che influenzano la struttura delle comunità diatomiche sono risultati essere, velocità di corrente, substrato, salinità e tra i nutrienti, principalmente nitrati e fosfati. Le foci dei fiumi, sono gli ecosistemi che presentano un numero maggiore di specie, riconducibile all’estrema variabilità dei loro parametri ambientali. Per quanto riguarda i canali, corpi idrici artificiali, che presentano sponde ed alvei cementificati, le specie diatomiche sono risultate essere un valido strumento di descrizione della qualità della matrice acquosa. Non si è ottenuto lo stesso risultato negli ecosistemi lagunari dove sono state ritrovate il minor numero di specie probabilmente dovuto alla selettività dei fattori ambientali (ad esempio la salinità). I risultati hanno mostrato una stretta correlazione delle comunità diatomiche ai diversi parametri ambientali; e inoltre caratterizzano le tre diverse tipologie d’ambienti di transizione: foci fluviali, laghi costieri e foci dei canali. La specie Amphora coffeaeformis, potenzialmente produttrice di neurotossine è stata isolata, ed è stata caratterizzata chimicamente attraverso Cromatografia associata alla spettrometria di massa e biologicamente attraverso Microtox. Le analisi non hanno rilevato la presenza dell’ acido domoico nella coltura, ciò non esclude che possa essere prodotto in condizioni di stress ambientale. Il contributo di questa tesi è stato l’ ampliamento delle conoscenze di base sulla distribuzione delle diatomee negli ecosistemi acquatici di transizione; questa comunità è risultata essere un ottimo descrittore di questi ambienti mostrando una forte correlazione con i fattori abiotici.Diatoms are widespread group in aquatic environments, and due to their characteristics are useful tools of biological monitoring. They are one of the biological elements required by the European Water Frame Directive 2000/60/EC for water quality assessment. Transitional waters are common ecosystems in Mediterranean Ecoregion and the lack of ecological knowledge cause a negative impact on environmental conservation, management and restoration. The aim of this study is to improve the knowledge of transitional water ecosystems through the study of diatom community and the assessment of the potential use of these algae as bioindicator. The study was conducted on diatom communities and environmental variables of several ecosystems and their potential correlations have been also investigated. A total of 28 sites were investigated. They represent different typologies of transitional waters: estuarine zones of lotic systems (rivers and channels) and brackish lentic ecosystems (coastal lagoons) of Tyrrhenian coast line, between Latium and Tuscany Regions. Biological and water samples were collected from each sites. A total of 219 species and varieties were identified. Furthermore, a potential toxic species, Amphora coffeaeformis was recognized. The identified diatom communities and the result of biotic analysis have been treated statistically by Principal Component Analysis and Canonical Correlation Analysis. The results showed that communities were similar as chemical and physical chemical variables for each typology of studied transitional waters. Canonical Correlation Analysis performed on biological and chemical outlined a linear correlation between components. Main factors that influenced diatom community structures were: velocity flow, substrate, salinity and nutrients, particularly nitrates and phosphates. River mouths presented a major numbers of species, probably due to the extreme heterogeneity of environmental parameters. Concerning canal mouths diatoms species resulted a good tool for assessment of water quality. In the lagoon ecosystems we found lower number of species probably related to the environmental selectivity (i.e. salinity). The results showed a strength correlation between diatomic communities and several environmental parameters. Three different diatom assemblages were observed in the three typology of transitional waters: river mouths, channel mouths and coastal lagoons. The potential toxic species Amphora coffeaeformis, was identified, isolated and cultured in fresh media. Besides, the species was submitted to toxicity test to evaluate the presence of domoic acid, using instrumental tests LC-MS and ecotoxiticy assay Microtox. The results of analysis did not detect the presence of domoic acid in the culture, but it could be a producer under environmental stress conditions. This study contribute to improve knowledge on diatoms of the Italian transitional aquatic ecosystems, at both the basic and applied levels.Dottorato di ricerca in Ecologia e gestione delle risorse biologich

Multi-criteria approach for the environmental impact assessment of inland aquaculture

Trout farming, that represents the most important sector for aquaculture inland production in Italy, can cause negative effects on aquatic ecosystems. Recently, in the framework of Water Frame Directive 2000/60/EC and national law DL 152/2006, concerning the sustainable uses of water resources, multi-criteria approaches have been suggested to evaluate the impact of fish farming on aquatic ecosystems. In this study trout farms of central Italy were selected to investigate the effects of their effluents, on receiving water bodies using a multi-criteria approach based on physicochemical parameters, microbiological and macrobenthonic indicators, detected in sampling stations located upstream/downstream the trout farm. Moreover, antibiotic susceptibility against antibiotics allowed and/or forbidden by current law (D.lgs 193/56/06) was tested on E. coli strains. The results indicate variations of chemical parameters and biological indicators from upstream to downstream sites in some of the investigated farms. Antibiotic resistance of E. coli strains suggested a large use of tetracycline and a possible past use of chloramphenicol. This study represents a first contribute to the knowledge of fish farm impacts on aquatic systems in Central Italy

Multi-criteria approach for the environmental impact assessment of inland aquaculture

Trout farming, that represents the most important sector for aquaculture inland production in Italy, can cause negative effects on aquatic ecosystems. Recently, in the framework of Water Frame Directive 2000/60/EC and national law DL 152/2006, concerning the sustainable uses of water resources, multi-criteria approaches have been suggested to evaluate the impact of fish farming on aquatic ecosystems. In this study trout farms of central Italy were selected to investigate the effects of their effluents, on receiving water bodies using a multi-criteria approach based on physicochemical parameters, microbiological and macrobenthonic indicators, detected in sampling stations located upstream/downstream the trout farm. Moreover, antibiotic susceptibility against antibiotics allowed and/or forbidden by current law (D.lgs 193/56/06) was tested on E. coli strains. The results indicate variations of chemical parameters and biological indicators from upstream to downstream sites in some of the investigated farms. Antibiotic resistance of E. coli strains suggested a large use of tetracycline and a possible past use of chloramphenicol. This study represents a first contribute to the knowledge of fish farm impacts on aquatic systems in Central Italy

Teratogenic effects of environmental concentration of plastic particles on freshwater organisms

Given the widespread presence of plastics, especially in micro- and nanoscale sizes, in freshwater systems, it is crucial to identify a suitable model organism for assessing the potential toxic and teratogenic effects of exposure to plastic particles. Until now, the early life stage of freshwater organisms and the regeneration capacity in relation to plastic particles exposure is a still poorly investigated topic. In this study, we examine the teratogenic effect on diatom Cocconeis placentula and cnidarian Hydra vulgaris under controlled exposure conditions of poly (styrene-co-methyl methacrylate) (P(S-co-MMA)) particles. Significant effects were observed at the lowest concentrations (0.1 & mu;g/L). A significant increase in the teratological frequency in C. placentula and a significant decrease in the regeneration rate in H. vulgaris were found at the lowest concentration. The delay in hydra regeneration impaired the feeding capacity and tentacles reactivity at 96 h of exposure. No effects on diatom growth were observed upon exposure to P(S-co-MMA) particles (0.1, 1, 100, 10,000 & mu;g/L) for 28 days and these findings agree with other studies investigating algal growth. The application of the Teratogenic Risk Index, modified for diatoms, highlighted a moderate risk for the lowest concentration evaluating C. placentula and low risk at the lowest and the highest concentrations considering H. vulgaris. This study suggests the importance of testing organisms belonging to different trophic levels as diverse teratogenic effects can be found and the need to evaluate environmentally relevant concentrations of plastic particles