Project description:The goal of the experiment was to compare the behavior and responses of a warm water diatom species in three different temperatures, low, intermediate and high, with the final aim of investigating possible intraspecific variability and better understanding the physiological plasticity and/or adaptation of diatoms to a wide range of conditions. Three different strains were used as replicates, B651,1A1,3A6. They were isolated from sea surface waters at the LTER-MC site (40°48.5’N, 14°15’E) in the Gulf of Naples on 21/08/2010, 20/12/2013 and 28/01/2014 respectively and grown in cultures. All three strains were acclimated to 13°C, 19°C and 26°C at a light intensity of 100 μmol photons m-2 sec-1 and a photoperiod of L:D, 12:12 and grown to a final concentration of 50,000 cells/ml ensuring they were still at exponential phase.
Project description:Mytilus galloprovincialis (Lmk, 1819) is economically relevant bivalve specie. In Adriatic Sea, periodical temperatures increases define optimal growth conditions for Dinoflagellate spp which can reach high concentrations also in filter-feeding mussels, thus causing potential human health problems. The most commonly used methods for the detection of Diarrhoeic Shellfish Poisoning biotoxins have either a low sensitivity or are too expensive to be used for routine tests. Genomic tools, such as microarray platforms, provide a reliable and alternative solution to overcome these problems. In this study we used a mussel cDNA microarray for studying gene expression changes in mussels exposed to Okadaic acid. Mussels collected in the Gulf of Trieste, located in Northern Adriatic Sea, were fed with Okadaic acid-spiked invertebrates for five weeks. In a time course experiment we were able to describe an early acute response just from the first 4th day time point. Among the differentially expressed genes we found a general up-regulation of stress proteins and proteins involved in cellular synthesis. Overall, we identified 34 transcripts candidate as useful markers to monitor OA-induced stress in mussels. This study contributes to the characterization of many potential genetic markers that could be used in future environmental monitoring, and could lead to explore new mechanisms of stress tolerance in marine mollusc species. Keywords: Time course, stress response
Project description:Mytilus galloprovincialis (Lmk, 1819) is economically relevant bivalve specie. In Adriatic Sea, periodical temperatures increases define optimal growth conditions for Dinoflagellate spp which can reach high concentrations also in filter-feeding mussels, thus causing potential human health problems. The most commonly used methods for the detection of Diarrhoeic Shellfish Poisoning biotoxins have either a low sensitivity or are too expensive to be used for routine tests. Genomic tools, such as microarray platforms, provide a reliable and alternative solution to overcome these problems. In this study we used a mussel cDNA microarray for studying gene expression changes in mussels exposed to Okadaic acid. Mussels collected in the Gulf of Trieste, located in Northern Adriatic Sea, were fed with Okadaic acid-spiked invertebrates for five weeks. In a time course experiment we were able to describe an early acute response just from the first 4th day time point. Among the differentially expressed genes we found a general up-regulation of stress proteins and proteins involved in cellular synthesis. Overall, we identified 34 transcripts candidate as useful markers to monitor OA-induced stress in mussels. This study contributes to the characterization of many potential genetic markers that could be used in future environmental monitoring, and could lead to explore new mechanisms of stress tolerance in marine mollusc species. Keywords: Time course, stress response Loop Design experiment including 5 time points (T0 = control samples, T1 = 3 days post treatment, T2 = 1 week post treatment, T4 = 3 weeks post treatment, T6 = 5 weeks post treatment). 3 biological replicates were done for a total number of 15 samples
Project description:Phytoplankton and bacteria form the base of marine ecosystems and their interactions drive global biogeochemical cycles. The effect of bacteria and bacteria-produced compounds on diatoms range from synergistic to pathogenic and can affect the physiology and transcriptional patterns of the interacting diatom. Here, we investigate physiological and transcriptional changes in the marine diatom Thalassiosira pseudonana induced by extracellular metabolites of a known antagonistic bacterium Croceibacter atlanticus. Mono-cultures of C. atlanticus released compounds that inhibited diatom cell division and elicited a distinctive phenotype of enlarged cells with multiple plastids and nuclei, similar to what was observed when the diatom was co-cultured with the live bacteria. The extracellular C. atlanticus metabolites induced transcriptional changes in diatom pathways that include recognition and signaling pathways, cell cycle regulation, carbohydrate and amino acid production, as well as cell wall stability. Phenotypic analysis showed a disruption in the diatom cell cycle progression and an increase in both intra- and extracellular carbohydrates in diatom cultures after bacterial exudate treatment. The transcriptional changes and corresponding phenotypes suggest that extracellular bacterial metabolites, produced independently of direct bacterial-diatom interaction, may modulate diatom metabolism in ways that support bacterial growth.