Growth and Proteome Response of Temperate and Polar Diatoms Thalassiosira pseudonana and Chaetoceros sp. to variations in Cobalt and Zinc: Identification of the High-Affinity Zinc Transporter and Potential for Use as a Biomarker

Marine diatoms such as the temperate Thalassiosira pseudonana (Tp) and the polar Chaetoceros sp (Ch) are known to be important contributors to marine primary productivity and the global carbon cycle. The nutritional use of zinc (Zn) in diatoms and the ability to substitute cobalt (Co) for Zn has been previously demonstrated to be of importance in their growth and biochemistry. We conducted physiological experiments with Zn and Co on these diatoms and analyzed their proteomic response. Growth studies involving Tp confirmed previous studies' findings showing Zn/Co substitution, while studies on Ch showed a toxic response to high Zn abundances. Proteome responses of Tp to Zn limitation identified a putative and previously unidentified transporter that was undetectable at high Zn concentration and became highly abundant at two lower Zn concentrations. The distribution of this protein in nature and its potential use as a Zn stress biomarker in diatoms will be discussed.