%0 Journal Article %J Environmental Microbiology %D 2017 %T Physiological adjustments and transcriptome reprogramming are involved in the acclimation to salinity gradients in diatoms %A Adrien Bussard %A Corre, Erwan %A Cédric Hubas %A Duvernois‐Berthet, Evelyne %A Gildas Le Corguille %A Jourdren, Laurent %A Coulpier, Fanny %A Pascal Claquin %A Pascal Jean Lopez %X

Salinity regimes in estuaries and coastal areas vary with river discharge patterns, seawater evaporation, the morphology of the coastal waterways, and the dynamics of marine water mixing. Therefore, microalgae have to respond to salinity variations at time scales ranging from daily to annual cycles. Microalgae may also have to adapt to physical alterations that induce the loss of connectivity between habitats and the enclosure of bodies of water. Here, we integrated physiological assays and measurements of morphological plasticity with a functional genomics approach to examine the regulatory changes that occur during the acclimation to salinity in the estuarine diatom Thalassiosira weissflogii. We found that cells exposed to different salinity regimes for a short or long period presented adjustments in their carbon fractions, silicon pools, pigment concentrations and/or photosynthetic parameters. Salinity-induced alterations in frustule symmetry were observed only in the long-term cultures. Whole transcriptome analyses revealed a down-regulation of nuclear and plastid encoded genes during the long-term response and identified only a few regulated genes that were in common between the short- and long-term responses. We propose that in diatoms, one strategy for acclimating to salinity gradients and maintaining optimal cellular fitness could be a reduction in the cost of transcription. This article is protected by copyright. All rights reserved.

%B Environmental Microbiology %V 19 %P 909-925 %8 5 %G eng %U http://dx.doi.org/10.1111/1462-2920.13398 %N 3 %R 10.1111/1462-2920.13398 %0 Journal Article %J Mol Biol Evol %D 2016 %T Insights from the shell proteome: biomineralization to adaptation. %A Arivalagan, Jaison %A Yarra Teja %A Marie, Benjamin %A Sleight, Victoria A %A Duvernois‐Berthet, Evelyne %A Clark, Melody S %A Marie, Arul %A Berland, Sophie %X

Bivalves have evolved a range of complex shell forming mechanisms that are reflected by their incredible diversity in shell mineralogy and microstructures. A suite of proteins exported to the shell matrix space plays a significant role in controlling these features, in addition to underpinning some of the physical properties of the shell itself. Although, there is a general consensus that a minimum basic protein tool kit is required for shell construction, to date, this remains undefined. In this study the shell matrix proteins (SMPs) of four highly divergent bivalves (The Pacific oyster, Crassostrea gigas; the blue mussel, Mytilus edulis; the clam, Mya truncata and the king scallop, Pecten maximus) were analyzed in an identical fashion using proteomics pipeline. This enabled us to identify the critical elements of a "basic tool kit" for calcification processes, which were conserved across the taxa irrespective of the shell morphology and arrangement of the crystal surfaces. In addition, protein domains controlling the crystal layers specific to aragonite and calcite were also identified. Intriguingly, a significant number of the identified SMPs contained domains related to immune functions. These were often are unique to each species implying their involvement not only in immunity, but also environmental adaptation. This suggests that the SMPs are selectively exported in a complex mix to endow the shell with both mechanical protection and biochemical defense.

%B Mol Biol Evol %8 2016 Oct 15 %G eng %R 10.1093/molbev/msw219