Project description:Proteins associated with diatom silica are likely involved in the biogenesis of the complex, species-specific morphologies of the biomineral, but only very few such proteins have been identified. In this project we extracted and identified proteins from three related, but morphologically distinct, species of centric diatoms: Thalassiosira pseudonana, Thalassiosira oceanica and Cyclotella cryptica.

2022-05-30 | PXD026496 | Pride

The dynamic response to hypoosmotic stress reveals distinct stages of freshwater acclimation by a euryhaline diatom

Project description:The salinity gradient separating marine and freshwater environments is a major ecological divide, and the mechanisms by which most organisms adapt to new salinity environments are poorly understood. Diatoms are a lineage of ancestrally marine microalgae that have repeatedly colonized and diversified in freshwaters. Cyclotella cryptica is a euryhaline diatom that naturally tolerates a broad range of salinities, thus providing a powerful system for understanding the genomic mechanisms for mitigating and acclimating to low salinity. To understand how diatoms mitigate acute hypoosmotic stress, we abruptly shifted C. cryptica from seawater to freshwater and performed transcriptional profiling at 8 time points across 10 hours. We found substantial remodeling of the transcriptome, with over half of the genome differentially expressed in at least one time point. The peak response occurred within 1 hour, with strong repression of genes involved in functions related to cell growth and osmolyte production, and strong induction of genes implicated in stress defense such as scavenging reactive oxygen species and maintaining osmotic balance. Notably, transcripts largely returned to baseline levels within 4–10 hours, with growth resuming shortly thereafter, suggesting that gene expression dynamics may be useful for predicting acclimation. Moreover, comparison to a study of expression profiling following months-long acclimation of C. cryptica to freshwater revealed little overlap between the genes and processes differentially expressed in cells exposed to acute stress versus fully acclimated conditions. Altogether, this study highlights the power of time-resolved transcriptomics to reveal fundamental insights into how cells dynamically respond to an acute environmental shift and provides new insights into how diatoms mitigate natural salinity fluctuations and have successfully diversified across freshwater habitats worldwide.

2022-06-23 | GSE206725 | GEO

Genome Sequences of Bacteria Associated with the Diatom <i>Cyclotella cryptica</i> Strain CCMP332.

Project description:We report draft genomes of two bacterial strains in the genera Hyphobacterium and Reichenbachiella, which are associated with the diatom Cyclotella cryptica strain CCMP332. Genomes from these strains were 2,691,501 bp and 3,325,829 bp, respectively, and will be useful for understanding interactions between diatoms and bacteria.

| S-EPMC7661000 | biostudies-literature

Project description:Cyclotella Cryptica transcriptome

| PRJNA561910 | ENA

Genome and methylome of the oleaginous diatom <i>Cyclotella cryptica</i> reveal genetic flexibility toward a high lipid phenotype.

Project description:BackgroundImprovement in the performance of eukaryotic microalgae for biofuel and bioproduct production is largely dependent on characterization of metabolic mechanisms within the cell. The marine diatom Cyclotella cryptica, which was originally identified in the Aquatic Species Program, is a promising strain of microalgae for large-scale production of biofuel and bioproducts, such as omega-3 fatty acids.ResultsWe sequenced the nuclear genome and methylome of this oleaginous diatom to identify the genetic traits that enable substantial accumulation of triacylglycerol. The genome is comprised of highly methylated repetitive sequence, which does not significantly change under silicon starved lipid induction, and data further suggests the primary role of DNA methylation is to suppress DNA transposition. Annotation of pivotal glycolytic, lipid metabolism, and carbohydrate degradation processes reveal an expanded enzyme repertoire in C. cryptica that would allow for an increased metabolic capacity toward triacylglycerol production. Identification of previously unidentified genes, including those involved in carbon transport and chitin metabolism, provide potential targets for genetic manipulation of carbon flux to further increase its lipid phenotype. New genetic tools were developed, bringing this organism on a par with other microalgae in terms of genetic manipulation and characterization approaches.ConclusionsFunctional annotation and detailed cross-species comparison of key carbon rich processes in C. cryptica highlights the importance of enzymatic subcellular compartmentation for regulation of carbon flux, which is often overlooked in photosynthetic microeukaryotes. The availability of the genome sequence, as well as advanced genetic manipulation tools enable further development of this organism for deployment in large-scale production systems.

| S-EPMC5124317 | biostudies-literature

Contrasting Effects of Acclimated Copper Limitation on the Photosynthetic Apparatus in Two Strains of the open ocean diatom Thalassiosira oceanica

Project description:The physiological adaptations of diatoms to cope with Cu limitation are largely unknown. In the present study we investigated the response to Cu limitation in two strains of the model open ocean diatom T. oceanica (CCMP 1003 and CCMP 1005), focusing on physiological and proteomic changes in the photosynthetic apparatus. Our results show remarkable differences between the adaptations of TO05 and TO03 to low Cu, highlighting significant intra specific variations.

2017-08-15 | PXD006237 | Pride

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