Dataset Information

Proteomic analysis of the marine diatom Thalassiosira pseudonana upon exposure to benzo(a)pyrene.

ABSTRACT: BACKGROUND: Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants ubiquitously distributed. They are generated by incomplete combustion of organic materials such as wood or fossil fuels. Due to their carcinogenic, mutagenic effects and to their wide distribution in the environment, these pollutants pose many concerns to researchers and regulators. In our laboratories we investigated the effect of benzo(a)pyrene (BaP) exposure in the marine diatom Thalassiosira pseudonana, which has become an important model organism in aquatic toxicology studies. RESULTS: In order to investigate the mechanism of action of PAHs, we exposed the diatoms for 24 h to 36.45 ?g/L of BaP which inhibits the growth by about 30%, and analysed the relative protein expression profile by a quantitative proteomics approach based on iTRAQ labels. The proteomics profile analysis showed that around 10% of the identified proteins were regulated and one fourth of them confirmed the gene expression changes seen by DNA microarray. Particularly interesting was the down regulation of the Silicon transporter 1 (SIT1), an enzyme that is responsible for the uptake of silicon from the media into the diatom cells. Regulation of SIT1 upon BaP treatment was also confirmed at the gene expression level. CONCLUSIONS: The potential use of the regulated proteins found in this study as early indicators of environmental exposure to PAHs is discussed. In particular, SIT1 is considered a promising biomarker and SIT1 expression changes were confirmed also when the diatoms were exposed to field samples, e.g. marine surface sediments contaminated by PAHs.

SUBMITTER: Carvalho RN

PROVIDER: S-EPMC3076255 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Proteomic analysis of the marine diatom Thalassiosira pseudonana upon exposure to benzo(a)pyrene.

Carvalho Raquel N RN Lettieri Teresa T

BMC genomics 20110324

<h4>Background</h4>Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants ubiquitously distributed. They are generated by incomplete combustion of organic materials such as wood or fossil fuels. Due to their carcinogenic, mutagenic effects and to their wide distribution in the environment, these pollutants pose many concerns to researchers and regulators. In our laboratories we investigated the effect of benzo(a)pyrene (BaP) exposure in the marine diatom Thalassiosira pseudonana, w ...[more]

PMID: 21435224

Similar Datasets

Project description:BackgroundCP12 is a small chloroplast protein that is widespread in various photosynthetic organisms and is an actor of the redox signaling pathway involved in the regulation of the Calvin Benson Bassham (CBB) cycle. The gene encoding this protein is conserved in many diatoms, but the protein has been overlooked in these organisms, despite their ecological importance and their complex and still enigmatic evolutionary background.MethodsA combination of biochemical, bioinformatics and biophysical methods including electrospray ionization-mass spectrometry, circular dichroism, nuclear magnetic resonance spectroscopy and small X ray scattering, was used to characterize a diatom CP12.ResultsHere, we demonstrate that CP12 is expressed in the marine diatom Thalassiosira pseudonana constitutively in dark-treated and in continuous light-treated cells as well as in all growth phases. This CP12 similarly to its homologues in other species has some features of intrinsically disorder protein family: it behaves abnormally under gel electrophoresis and size exclusion chromatography, has a high net charge and a bias amino acid composition. By contrast, unlike other known CP12 proteins that are monomers, this protein is a dimer as suggested by native electrospray ionization-mass spectrometry and small angle X-ray scattering. In addition, small angle X-ray scattering revealed that this CP12 is an elongated cylinder with kinks. Circular dichroism spectra indicated that CP12 has a high content of α-helices, and nuclear magnetic resonance spectroscopy suggested that these helices are unstable and dynamic within a millisecond timescale. Together with in silico predictions, these results suggest that T. pseudonana CP12 has both coiled coil and disordered regions.ConclusionsThese findings bring new insights into the large family of dynamic proteins containing disordered regions, thus increasing the diversity of known CP12 proteins. As it is a protein that is more abundant in many stresses, it is not devoted to one metabolism and in particular, it is not specific to carbon metabolism. This raises questions about the role of this protein in addition to the well-established regulation of the CBB cycle. Choregraphy of metabolism by CP12 proteins in Viridiplantae and Heterokonta. While the monomeric CP12 in Viridiplantae is involved in carbon assimilation, regulating phosphoribulokinase (PRK) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) through the formation of a ternary complex, in Heterokonta studied so far, the dimeric CP12 is associated with Ferredoxin-NADP reductase (FNR) and GAPDH. The Viridiplantae CP12 can bind metal ions and can be a chaperone, the Heterokonta CP12 is more abundant in all stresses (C, N, Si, P limited conditions) and is not specific to a metabolism. Video Abstract.

Project description:BackgroundSilicon plays important biological roles, but the mechanisms of cellular responses to silicon are poorly understood. We report the first analysis of cell cycle arrest and recovery from silicon starvation in the diatom Thalassiosira pseudonana using whole genome microarrays.ResultsThree known responses to silicon were examined, 1) silicified cell wall synthesis, 2) recovery from silicon starvation, and 3) co-regulation with silicon transporter (SIT) genes. In terms of diatom cell wall formation, thus far only cell surface proteins and proteins tightly associated with silica have been characterized. Our analysis has identified new genes potentially involved in silica formation, and other genes potentially involved in signaling, trafficking, protein degradation, glycosylation and transport, which provides a larger-scale picture of the processes involved. During silicon starvation, an overrepresentation of transcription and translation related genes were up-regulated, indicating that T. pseudonana is poised to rapidly recover from silicon starvation and resume cell cycle progression upon silicon replenishment. This is in contrast to other types of limitation, and provides the first molecular data explaining the well-established environmental response of diatoms to grow as blooms and to out-compete other classes of microalgae for growth. Comparison of our data with a previous diatom cell cycle analysis indicates that assignment of the cell cycle specific stage of particular cyclins and cyclin dependent kinases should be re-evaluated. Finally, genes co-varying in expression with the SITs enabled identification of a new class of diatom-specific proteins containing a unique domain, and a putative silicon efflux protein.ConclusionsAnalysis of the T. pseudonana microarray data has provided a wealth of new genes to investigate previously uncharacterized cellular phenomenon related to silicon metabolism, silicon's interaction with cellular components, and environmental responses to silicon.

Project description:Bacteria-diatom interactions in the ocean are diverse but usually studied in static conditions, which limits our understanding of their importance in marine ecosystems and biogeochemical cycles. Here, we explored the dynamic interactions between an ubiquitous marine bacterium Alteromonas sp. and a diatom Thalassiosira pseudonana under different nutrient conditions. In oligotrophic conditions, minor shifts in nutrients qualitatively altered the interactions from mutualism during early exponential growth to weak parasitism during the late stationary phase. Organic matter-activated Alteromonas chemotactically swam toward, attached on, and dramatically broke down T. pseudonana cells, leading to an aggressive parasitic behavior with a 95% algicidal rate. Meanwhile, inorganic matter-activated T. pseudonana showed amensalism against Alteromonas, resulting in an ephemeral decrease of bacterial abundance by 27%. Interestingly, when both organics and inorganics were sufficient, Alteromonas suppressed diatom growth by inhibiting the cell division, while the surviving T. pseudonana restored proliferation with a significantly smaller cell size inconducive to bacterial attachment, demonstrating an intense competition. The results further indicated that the algicidal effect of Alteromonas was controlled by the cell-specific protease activity and the number of attached bacteria on the diatom cell surface, both of which were related to nutrient conditions. Since the nature and intensity of bacteria-diatom interaction depend on the composition and richness of nutrients, it mechanistically explains the tripartite relationship among bacterial proliferation, nutrient viability, and algal demise during blooms. The algicidal behavior of copiotrophs also potentially enhances the contribution of a microbial carbon pump to carbon sequestration in the ocean. IMPORTANCE As the major producers and consumers, phytoplankton and bacteria play central roles in marine ecosystems and their interactions show great ecological significance. Whether mutualistic or antagonistic, the interaction between certain phytoplankton and bacterial species is usually seen as a derivative of intrinsic physiological properties and rarely changes. This study demonstrated that the interactions between the ubiquitously co-occurring bacteria and diatom, Alteromonas and Thalassiosira pseudonana, varied with nutrient conditions. They overcame hardship together in oligotrophic seawater but showed antagonistic effects against each other under nutrient amendment. The contact-dependent algicidal behavior of Alteromonas based on protease activity solved the paradox among bacterial proliferation, nutrient viability, and algal demise haunting other known non-contact-dependent algicidal processes and might actually trigger the collapse of algal blooms in situ. The chemotactic and swarming movement of Alteromonas might also contribute greatly to the breakdown of "marine snow," which could redirect the carbon sequestration pathway in the ocean.

Dataset Information

Proteomic analysis of the marine diatom Thalassiosira pseudonana upon exposure to benzo(a)pyrene.

Publications

Proteomic analysis of the marine diatom Thalassiosira pseudonana upon exposure to benzo(a)pyrene.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets