Fig. 1.

Growth and expression characteristics of IbpA DR2-GFP transformed lines of T. pseudonana. a A representative experiment demonstrating growth differences between wild-type cells and cells expressing IbpA DR2-GFP under the control of either fcp or SIT1 regulatory elements in silicon-replete medium. Wt wild type, DR2-GFP (fcp) fcp-driven expression, DR2-GFP (SIT1) SIT1-driven expression (cells not induced). b Net expression of pTp SIT1/IbpA DR2-GFP as determined by imaging flow cytometry. Net expression calculated as the mean GFP fluorescence intensity in the population of GFP-gated cells multiplied by the percentage of the total population of cells expressing GFP. Expression differences between cells growing in replete medium (uninduced) and medium without silicon (induced) can be observed. c–e Scatterplots demonstrating the effect of silicon availability on the expression of pTp SIT1/IbpA DR2-GFP as observed with imaging flow cytometery. c No detectable expression based on GFP fluorescence under silicon replete conditions. d Expression after 16 h of silicon starvation. e Expression after 24 h of silicon starvation. Yellow and green gates represent no GFP and GFP fluorescence, respectively. Gates were determined based on wild-type cells without GFP. Ten thousand cells were analyzed for each sample