ABSTRACT: Hallmarks of the dynamic responses to silica in Thalassiosira pseudonana - Identification, characterization and classification of signature genes and their corresponding motifs
Project description:The diatom cell wall, or frustule, is a highly complex, three-dimensional structure consisting of nanopatterned silica as well as proteins and other organic components. While some key components have been identified, knowledge on frustule biosynthesis is still fragmented. The model diatom Thalassiosira pseudonana was subjected to silicon (Si) shift-up and shift-down situations. Cellular and molecular signatures, dynamic changes and co-regulated clusters representing the hallmarks of cellular and molecular responses to changing Si availabilities were characterised. 62 silaffin-like proteins (SFLPs), two kinases and a novel family of putatively frustule-associated transmembrane proteins induced by Si shift-up and a possible role in frustule biosynthesis were identified. A separate cluster analysis performed on all significantly regulated SFLPs, as well as fourteen new proteins with silaffin-like motifs, resulted in the classification of silaffins, cingulins and SFLPs into distinct clusters. The genes in the Si-responsive clusters are in general highly divergent, but positive selection does not seem to be the driver behind this variability. This study provides a high-resolution map over transcriptional responses to changes in Si availability in T. pseudonana. Hallmark Si-responsive genes are identified, characteristic motifs and domains are classified, and taxonomic and evolutionary implications outlined and discussed.
Project description:This SuperSeries is composed of the following subset Series: GSE9660: Profiling the transcriptome of Thalassiosira pseudonana under environmentally relevant growth conditions GSE9661: Profiling the transcriptome of Thalassiosira pseudonana under silicon replete and deplete growth Refer to individual Series
Project description:To identify the molecular components involved in diatom cell division, global transcript level changes were monitored over the silicon-synchronized cell cycle the model diatom Thalassiosira pseudonana.
Project description:To generate a baseline proteomic profile of Thalassiosira pseudonana, three samples collected at the exponential, stationary and decline phases were subject to proteomic analysis.
Project description:Comparison of transcriptional profile of Thalassiosira pseudonana exposed for 24h to 36.45 ug/L BaP and methanol-treated controls. Four biological replicates (BaP treatment) and six biological replicates (controls).
Project description:Diatom cell walls, made of nanostructured silica, are of interest in diverse areas ranging from cellular structure, to hierarchical organization in biomineralization, to nanotechnology. Thus far, only cell surface proteins and proteins tightly associated with silica matrix have been characterized, and essential components of the silica deposition vesicle (SDV) are unknown, including components of the SDV membrane, cytoskeletal-interacting proteins, and proteins involved in trafficking associated with the SDV. Thus, an understanding of most of the molecular components and the dynamics of cellular processes involved in cell wall synthesis is lacking. In this work we report the first whole-cell response analysis using whole genome microarrays to identify genes potentially involved in diverse aspects of diatom cell division or cell wall synthesis. Thalassiosira pseudonana transcript profiles from precise time points, known to be associated with specific cell wall formation processes in cell-cycle synchronized cultures, suggests that this gene set includes extracellular proteins, silica matrix proteins, and proteins involved in signal transduction, vesicle trafficking, and transport. Protein localization experiments further confirm the first discovery of proteins associated with the SDV membrane. We propose that these proteins provide the interface between extra-SDV organization by the cytoskeleton and intra-SDV organization of silica polymerization determinants, which lead to the higher order organization of diatom silica structure.
Project description:We applied an iTRAQ-based quantitative proteomic approach to compare the protein expression profiles of Thalassiosira pseudonana grown in nutrient-replete, and N-, P- and Si-deficient conditions.
