Francois Ribalet and co-authors have published a new study in the journal PLoS ONE on phytoplankton cell lysis associated with chemical compounds release by diatoms. The study present data from four oceanographic cruises that took place during diatom blooms in the northern Adriatic Sea where concentrations of particulate and dissolved aldehydes produced by diatoms were monitored along with phytoplankton cell lysis. Cell lysis was positively correlated with both concentrations of particulate and dissolved aldehydes, supporting the hypothesis that these compounds are released by cell lysis. These results also suggest that aldehydes may help shape plankton community composition and function in the oceans.
Gwenn Hennon and co-authors have published a new study in the Journal of Phycology on the physiological changes in the diatom Thalassiosira pseudonana under elevated CO2 in a nitrate-limited chemostat. The study finds that acclimation conditions modify the physiological response of the diatom to elevated CO2, with longer acclimations resulting in moderated physiological changes. These results suggest that gene expression or epigenetic changes over tens of generations may moderate some of the extreme physiological changes observed in diatoms under elevated CO2. Understanding these processes will be key in predicting changes to the marine carbon cycle as atmospheric carbon rises.
Shady Amin and coauthors published a new study on the copper requirements of ammonia-oxidizing archaea (AOA), a major group of prokaryotes that are believed to dominate ammonia oxidation in the oceans. The few publicly available AOA genomes suggested these organisms have a Cu requirement due to the presence of a high number of Cu metalloenzymes. Indeed, this study finds that the only marine AOA available in pure culture is Cu-limited at copper concentrations that are commonly found in the marine environment.
Silicification in Coastal Diatom Communities
Colleen A. Durkin and co-authors published a new study on diatom silicification. The authors used in situ incubation experiments, along with laboratory culturing experiments, to demonstrate that variation in silicic acid supply alters the silicification of coastal diatom blooms and diatom sinking rates. Click here to read more in Limnology and Oceanography: Silicic acid supplied to coastal diatom communities influences cellular silicification and the potential export of carbon
SEAStAR Software for Metagenome Analysis Released
SEAStAR is an open-source package of software tools for the analysis of environmental next-generation (Illumina®, SOLiD™) sequence data. Prototype versions of these tools were used to analyze the metagenomic data in our publication: Untangling Genomes from Metagenomes: Revealing an Uncultured Class of Marine Euryarchaeota. You can learn more by visiting the SEAStAR Home Page.
Positive Gene Selection in Diatoms
Julie Koester and co-authors published new findings on positive selection in diatoms. The authors were able to connect positively selected genes to the selective pressures of nutrient limitation and temperature, successfully integrating genotype with phenotype in diatoms. Click here to read more in Molecular Biology and Evolution: Positive Selection within a Diatom Species Acts on Putative Protein Interactions and Transcriptional Regulation
Investigating Silica Precipitation in Diatoms
Colleen Durkin and co-authors published on the role of diatom community composition and the transcription of key, frustule-related genes on silica precipitation in the environment. Click here to read more in Limnology and Oceanography: Frustule-related gene transcription and the influence of diatom community composition on silica precipitation in an iron-limited environmentt