FIG 3.

S. gordonii gene expression with nicotine. Overnight S. gordonii cells were treated with 0 and 2 mg/ml nicotine for 8 h in TSBS, and planktonic cells were harvested for qRT-PCR. The value for 2^−ΔCT instead of 2^−ΔΔCT of each sample was recorded. The 16S rRNA data were standardized to 1, and all other gene data were less than 1. Using 2^−ΔCT instead of 2^−ΔΔCT makes between-gene comparisons available. The gene expression levels of the no-nicotine controls were ranked from highest to lowest (left to right). Because the gene expression was very low in cshA, cshB, gtfG, abpB, and sspA, their results were placed in another figure with a different scale than the original one. Results indicated nicotine significantly upregulated abpA, scaA, ccpA, and srtA expression. Although there were only 4 out of 11 genes that indicated significant changes, those four genes accounted for the majority of the total gene expression. *, P < 0.05.