FIG 1.

Relationship between the number of starting cells versus the number of quantitative PCR (qPCR) cycles required to reach an estimated threshold of DNA amplification equivalent to a fluorescence value of 2,000 during the first step of transposon-based library preparation (above 2,000 arbitrary value, the negative control starts to amplify). Asterisks indicate statistically significant (P < 0.05 by Student's t test) differences between the number of cells and the value for the negative (−) control (0 ng DNA). The positive (+) control is equal to 2 ng of DNA.