Fig. 7.

Determination of the efficiency of the PCR for bombesin receptor target and competitor DNAs. cDNA (1/200th) obtained from a single SCN slice was amplified in the same tube as BB₁ (3.6 attogram) or BB₂ (25.8 attogram) competitor in a 40 μl reaction using the cycling conditions described in Materials and Methods. A 2 μl sample was removed from the reaction at the end of the extension phase from cycles 21–38, and the products were separated on an agarose gel, stained, and quantitated by densitometry. The data show (A) the increase in BB₁ target (filled arrow) and competitor (open arrow) and (B) BB₂ target (filled arrow) and competitor (open arrow) with cycle number during the linear (exponential) phase of the reaction. The efficiency of amplification is calculated from the slope of the linear regression line for each product. Efficiencies were as follows: for BB₁ target 92.4% (filled triangles), BB₁ competitor 98.3% (filled squares), and for BB₂ target 99.3% (filled triangles), BB₂ competitor 96.0% (filled squares).