parA and parB mRNA synthesis during growth of Mycobacteria in broth culture. (A): Total RNA isolated from exponential (7 days) and stationary (21 days) cultures of M. bovis BCG. (B): Total RNA isolated from exponential (OD595 nm = 0.9), late exponential (OD595 nm = 1.2) and stationary (OD595 nm = 3.0) cultures of M. smegmatis. At the indicated time, bacterial RNA was extracted and transcript levels of parA (black bars) and parB (white bars) were analysed by real-time PCR; 16S rRNA levels were used for normalization. The error bars show the mean (± SD) of at least two separate determinations made with different batches of total RNA.