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Title: The evolution of silicon transporters in diatoms

Diatoms are highly productive single‐celled algae that form an intricately patterned silica cell wall after every cell division. They take up and utilize silicic acid from seawater via silicon transporter (SIT) proteins. This study examined the evolution of theSITgene family to identify potential genetic adaptations that enable diatoms to thrive in the modern ocean. By searching for sequence homologs in available databases, the diversity of organisms found to encodeSITs increased substantially and included all major diatom lineages and other algal protists. A bacterial‐encoded gene with homology toSITsequences was also identified, suggesting that a lateral gene transfer event occurred between bacterial and protist lineages. In diatoms, theSITgenes diverged and diversified to produce five distinct clades. The most basalSITclades were widely distributed across diatom lineages, while the more derived clades were lineage‐specific, which together produced a distinct repertoire ofSITtypes among major diatom lineages. Differences in the predicted protein functional domains encoded amongSITclades suggest that the divergence of clades resulted in functional diversification amongSITs. Both laboratory cultures and natural communities changed transcription of eachSITclade in response to experimental or environmental growth conditions, with distinct transcriptional patterns observed among clades. Together, these data suggest that the diversification ofSITs within diatoms led to specialized adaptations among diatoms lineages, and perhaps their dominant ability to take up silicic acid from seawater in diverse environmental conditions.

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Author(s) / Creator(s):
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Date Published:
Journal Name:
Journal of Phycology
Medium: X Size: p. 716-731
["p. 716-731"]
Sponsoring Org:
National Science Foundation
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