Mining the diatom genome for the mechanism of biosilicification
- Department of Ecology Evolution and Marine Biology and the Marine Science Institute, University of California, Santa Barbara, CA 93106
Ever since the invention of the microscope, scientists and laypeople alike have marveled at the intricate patterning of the silica within the diatom cell wall, termed the frustule (Fig. 1). There are well over 10,000 species of diatoms in marine and freshwaters, and each species has a unique wall morphology (1). Although organisms from multiple kingdoms of life produce siliceous structures (e.g., phytoliths in higher plants, spicules in sponges, frustules in diatom), those produced by diatoms are the most ornate and the most finely detailed. The ability of diatoms to manipulate silicon at the nanoscale exceeds that of human nanotechnology, making the genetic and biochemical underpinnings of biosilicification of great interest in material science. Diatoms are also important ecologically because they are major primary producers supporting the food webs in both marine and fresh waters. Despite the broad scientific interest in the silicification process, the biochemical pathways involved and the underlying genetics are largely a mystery. The sequencing of the first diatom genome (2) has enabled a new suite of approaches in the hunt for pathways involved in biosilicification. In this issue of PNAS, Mock et al. (3) exploit this potential by using whole genome expression profiling to elucidate candidate genes controlling silicification in the marine diatom Thalassiosira pseudonana.
The diatom Thalassiosira pseudonana. (Scale bar: 1 μm.) (Micrograph courtesy of Mark Hildebrand, Scripps Institution of Oceanography, San Diego, CA.)
Diatoms are microscopic unicellular protists and the vast majority are photoautotrophs. Their role in the ecology and biogeochemistry of our planet is impressive. They are responsible for 20% of the carbon fixed through photosynthesis on Earth (4), making diatoms major contributors to global carbon cycling and they collectively produce ≈10 km3 of hydrated amorphous …
*E-mail: brzezins{at}lifesci.ucsb.edu
