Figure 4.

Effects of synthesized peptides on QS-related gene expression. (a) Cultures of S. mutans were incubated with the vehicle or CSP1 (20 μM) for 2–24 h. Bacteria were collected and subjected to RNA extraction. Expression of the bip gene was investigated by qPCR. (b) Cultures of S. mutans were incubated with CSP1 with or without the synthesized peptides (each one at 20 μM). The expression of the bip gene was investigated 8 h later by qPCR. (c) S. mutans were diluted in BHI containing 0.2% w/v sucrose and AS (1:10) media to obtain biofilm. Cultures were added with the vehicle or CSP1 (20 μM) and incubated for 2–24 h. Adherent bacteria were collected and subjected to RNA extraction. Expression of the vicK gene was investigated by qPCR. (d) S. mutans was incubated with CSP1 with or without synthesized peptides (each one at 20 μM) and cultured to obtain biofilm. The expression of the vicK gene was investigated 16 h later by qPCR. Planktonic cultures of S. mutans were incubated for 8 h with CSP1 with or without synthesized peptides (each one at 20 μM). Bacteria were collected and subjected to RNA extraction. Expressions of comD (e) or comE (f) genes were investigated by qPCR. The results are reported as the log₂ of relative gene expression. The data are expressed as the mean ± SEM of three independent experiments. * denotes p < 0.05 vs. CSP1.