A gene family of silicon transporters

Hildebrand, Mark; Volcani, Benjamin E.; Gassmann, Walter; Schroeder, Julian I.

doi:10.1038/385688b0

Cited by 307 publications

(249 citation statements)

References 9 publications

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“…There are two general morphological types of diatoms based on their valve structures: the centrics, which have rotational symmetry, and the pennates, which have bilateral symmetry [39]. Diatom silica is made from the soluble precursor form of silicic acid, which is transported into the cell [19,20] and into a specialized membranebound compartment called the silica deposition vesicle [8,11,36,44], or SDV, where it is polymerized to form the mineral. Once the mineral structure of the valve or girdle band is completed, it is moved in its entirety across the plasma membrane (exocytosed), where it becomes an exoskeleton surrounding the cell.…”

Section: Introductionmentioning

confidence: 99%

Application of AFM in understanding biomineral formation in diatoms

Hildebrand

Doktycz

Allison

2007

Pflugers Arch - Eur J Physiol

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We review previous work and present new data on the application of atomic force microscopy (AFM) to study biomineral formation in diatoms, unicellular algae that make cell walls of silica. Previous studies examined a small subset of mostly larger diatom species, identifying a prevalence of large particulate silica on the nanoscale. We survey different structures including valves, girdle bands, and elongated spines called setae, in a variety of species, and show a diversity of nano-and meso-scale silica morphologies, even on different portions of the same structure. A general trend of highly organized mesoscale silica structure on the proximal face of cell wall components was observed, with less organized structure occurring on the distal face. The highly organized structures have features suggestive of an underlying linear template, which defines the area of initial silica polymerization. Such features have not been imaged with such clarity previously, demonstrating the advantages of AFM to image small differences in surface morphology and providing new insights and confirming evidence for models of diatom silica structure formation. In addition to its imaging capability, more developed application of AFM to map locations of organic template components on the nanoscale will greatly aid in elucidating mechanisms of diatom biosilica synthesis.

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Section: Introductionmentioning

confidence: 99%

Application of AFM in understanding biomineral formation in diatoms

Hildebrand

Doktycz

Allison

2007

Pflugers Arch - Eur J Physiol

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“…Diatoms possess the silicon transporter (SIT) family, whose activity and expression is tightly coupled to biosilicification [6,7]. SIT-like genes have been found in other siliceous stramenopiles (Synura and Ochromonas [8]), but in no other groups.…”

Section: Introductionmentioning

confidence: 99%

A family of diatom-like silicon transporters in the siliceous loricate choanoflagellates

et al. 2013

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Biosilicification is widespread across the eukaryotes and requires concentration of silicon in intracellular vesicles. Knowledge of the molecular mechanisms underlying this process remains limited, with unrelated silicontransporting proteins found in the eukaryotic clades previously studied. Here, we report the identification of silicon transporter (SIT)-type genes from the siliceous loricate choanoflagellates Stephanoeca diplocostata and Diaphanoeca grandis. Until now, the SIT gene family has been identified only in diatoms and other siliceous stramenopiles, which are distantly related to choanoflagellates among the eukaryotes. This is the first evidence of similarity between SITs from different eukaryotic supergroups. Phylogenetic analysis indicates that choanoflagellate and stramenopile SITs form distinct monophyletic groups. The absence of putative SIT genes in any other eukaryotic groups, including non-siliceous choanoflagellates, leads us to propose that SIT genes underwent a lateral gene transfer event between stramenopiles and loricate choanoflagellates. We suggest that the incorporation of a foreign SIT gene into the stramenopile or choanoflagellate genome resulted in a major metabolic change: the acquisition of biomineralized silica structures. This hypothesis implies that biosilicification has evolved multiple times independently in the eukaryotes, and paves the way for a better understanding of the biochemical basis of silicon transport through identification of conserved sequence motifs.

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“…Experimental evidence indicates that transport of silicon from the extracellular medium across the diatom cell membrane is carrier-mediated, electrogenic, involves silicic acid and Na ϩ in a 1:1 ratio, and requires metabolic energy (Azam et al, 1974;Bhattacharya and Volcani, 1980;Hildebrand et al, 1997). Different types of silicic acid transporter genes have been identified, and code for different types of transporters, probably of varying binding character and localization within the cell (Hildebrand et al, 1997(Hildebrand et al, , 1998.…”

Section: Silicon Utilization In Diatomsmentioning

confidence: 99%

“…Different types of silicic acid transporter genes have been identified, and code for different types of transporters, probably of varying binding character and localization within the cell (Hildebrand et al, 1997(Hildebrand et al, , 1998. Using model compounds, we have attempted to determine whether it is more favorable for the transporter to bind silicic acid or a silicateorganic complex (Sahai and Tossell, 2001).…”

Section: Silicon Utilization In Diatomsmentioning

confidence: 99%

Calculation of 29Si NMR shifts of silicate complexes with carbohydrates, amino acids, and muhicarboxylic acids: potential role in biological silica utilization

Sahai

2004

Geochimica et Cosmochimica Acta

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A gene family of silicon transporters

Cited by 307 publications

References 9 publications

Application of AFM in understanding biomineral formation in diatoms

Application of AFM in understanding biomineral formation in diatoms

A family of diatom-like silicon transporters in the siliceous loricate choanoflagellates

Calculation of 29Si NMR shifts of silicate complexes with carbohydrates, amino acids, and muhicarboxylic acids: potential role in biological silica utilization

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