Origin & Evolution of Life

Silicification of Cyanobacteria

By Keith Cowing
Status Report
May 27, 2024
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Silicification of Cyanobacteria
Divergence time and Marine silicon concentration for phytoplankton that may contain SITs-like or SITs -like proteins: Decimals near ancestral nodes indicate posterior probabilities. Solid red dots represent fossil calibration points, gray bar represents 95% confidence intervals, and solid black dots represent estimated divergence time by molecular clocks. 95% confidence intervals are shown here for only some nodes, Some solid points are not digitally labeled when their posterior probability is less than 0.5. Different colors in the background represent different geological periods. The diagram shows the representation of each class group. The graph below shows DSI concentrations of different geological ages, modified from Conley et al. (2017) and Siever (1991). — biorxiv.org

The ability to use dissolved silicon has been found in various oceanic phytoplankton, including eukaryotic diatoms and prokaryotic cyanobacteria.

While the silicification process in diatoms has been extensively studied, it is poorly known in cyanobacteria. In this study, the Cyanobacteria (Synechococcus) silicification and its evolutionary relationships of silicon-related proteins with different phytoplankton and algae were compared. Results showed that, compared to others, cyanobacteria have similar silicification proteins as diatoms.

In detail, cyanobacteria and diatoms displayed three silicification-related proteins (SIT, Silaffins, and Pleuralins), while several genera showed one or two of them, suggesting that cyanobacteria might have developed a Si related mechanism earlier than the diatoms and other species.

Our findings show that, despite cyanobacteria’s earlier silicon mechanism compared to others, they might not use efficient Si accumulation, perhaps adapting unique intracellular elemental variation for their cellular processes for growth potential.

Silicification of Cyanobacteria, biorxiv.org


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