Exploring Bioinorganic Pattern Formation in Diatoms. A Story of Polarized Trafficking

The world's oceans cover 70% of the surface of our planet. The photosynthetic organisms living within its photic zone are responsible for about one-half of global primary productivity. The most successful organisms are thought to be photosynthetic prokaryotes (cyanobacteria and prochlorophytes) and a class of eukaryotic unicellular algae known as diatoms (Norton et al., 1996; Van Den Hoek et al., 1997; Falkowski et al., 1998). Diatoms are likely to have arisen around 280 million years ago following an endosymbiotic event between a red eukaryotic alga and a heterotrophic flagellate related to the Oomycetes (Medlin et al., 1997,2000). As a consequence, their only phylogenetic similarity to green algae and higher plants is derived from the primary endosymbiotic event, which is thought to have occurred at least 700 million years ago (Kowallik, 1992). Therefore, diatom cells have a range of features that make them highly divergent from the classical cellular structure of higher plants, including: