A new view into the silica deposition vesicles of diatoms

Abstract

<jats:title>Abstract</jats:title> <jats:p>Diatoms are single-celled microalgae that produce silica-based cell walls with intricate nano- and micropatterns. Biogenesis of diatom biosilica is a bottom-up process that occurs in large intracellular compartments termed silica deposition vesicles (SDVs). Investigating the mechanism of silica morphogenesis has so far been severely limited by the lack of methods for imaging the entire volume of an SDV with high spatial resolution during all stages of development. Here we have developed a method that allows for rapid identification and electron microscopy imaging of many different, full sized SDVs that are in the process of producing biosilica valves. This enabled visualizing the development of characteristic morphological biosilica features with unprecedented spatio-temporal resolution. During early to mid-term development, valve SDVs contained ~20 nm sized particles that were primarily associated with the radially expanding rib-like biosilica structures. The results from electron dispersive X-ray analysis suggests that the immature biosilica patterns are silica-organic composites. This supports the hypothesis that silica morphogenesis is dependent on organic biomolecules inside the SDV lumen.</jats:p>

Physical, Chemical, and Genetic Techniques for Diatom Frustule Modification: Applications in Nanotechnology

“…The extraordinary precision and frequency with which this mechanism occurs has always fascinated and intrigued biologists and different models have been proposed. However, to date none of them is able to explain biosilica morphogenesis in its entirety [109]. Indeed, there are still many components of the process that should be clarified, such as how this higher-order structure is formed and what are the exact spatial and temporal mechanisms that are imparted on the process.…”

“…Cloning technology for GFP fusion proteins. [109] One of the earliest examples of genetic engineering-based approach in the study of frustule biogenesis has been reported for T. pseudonana by Shrestha and Hildebrand in 2015 [121]. The authors, using Gateway technology for GFP fusion proteins and antisense RNA and RNA interference (RNAi) approaches, determined the spatial localization and the regulatory and signaling role for the individual silicon transporters genes (SITs).…”