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Phytoplankton Plastid Proteomics: Cracking open Diatoms to Understand Plastid Biochemistry under Iron Limitation

Skyler J. Nunn (1,2), P. Dreux Chappell (3), Kristofer Gomes (4), Anasthasia Bonderenko (2,5), Bethany D. Jenkins (4), Brook L. Nunn (2)*
(1)Telluride High School; 725 West Colorado Avenue, Telluride CO 81435. (2)University of Washington, Department of Genome Sciences; Seattle WA 98195. (3)Old Dominion University, Ocean, Earth & Atmospheric Sciences; Norfolk, VA 23529. (4)University of Rhode Island, Department of Cell and Molecular Biology, Rhode Island 02881. (5)Newport High School, Newport, WA 99156. *Corresponding author,

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Diatoms, such as Thalassiosira pseudonana, are important oceanic primary producers, as they sequester carbon dioxide (CO₂) out of the atmosphere, die, and precipitate to the ocean floor. In many areas of the world’s oceans, phytoplankton, such as diatoms, are limited in growth by the availability of iron (Fe). Fe is an essential nutrient for phytoplankton, as it is central in the electron transport chain component of photosynthesis. Through this study, we examined if Fe-limitation makes a significant difference in the proteins expressed within the chloroplast, the power source for diatoms. Here, we utilized a new plastid isolation technique specific to diatoms and completed 14 mass spectrometry experiments to determine how many proteins transit the plastid membrane, if there are any differences in the expressed proteomes within the plastid grown under Fe-replete and Fe-limited conditions, and what those differences are. Over 900 unique proteins were identified from the isolated plastids, and cluster analyses of the data verified that statistical differences are present between the Fe-replete and Fe-limited growth conditions. Furthermore, our plastid proteome is in agreement with many of the recognized proteins previously discovered in land plant plastids, suggesting the isolation method followed by proteomic mass spectrometry is valid and sensitive. Through the isolation and analysis of plastid proteins, as shown here, scientists can now better identify which nutrients and/or trace metals directly affect diatom photosynthetic capacity so they can design better experiments to increase CO₂ fixation rates.

Received: April 25, 2016; Accepted: December 11, 2016; Published: February 10, 2017

Copyright: © 2016 Nunn et al. All JEI articles are distributed under the attribution non-commercial, no derivative license ( This means that anyone is free to share, copy and distribute an unaltered article for non-commercial purposes provided the original author and source are credited.

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