Fig. 2. Assessment of qRT-PCR assay by a comparison of RT-PCR efficiencies between standard RNA solutions and sample mRNA solutions that contain cell debris. The solid circles show the relation between the starting quantity of RNA and the threshold cycles for standard Lymnaea CREB2 RNA solutions. The slope of the regression line is –3.98. The open circles show the relation between the starting quantity of mRNA and the threshold cycles for the Lymnaea CREB2 mRNA samples obtained from the cerebral giant cells. The amount of total mRNA in the sample, when 19 cells in a tube were used, was arbitrarily assigned a value of one. The slope of the regression line is –3.94. The two parallel slopes confirmed that RNAs of standard RNA solutions and samples could be amplified with the same RT-PCR efficiency in qRT-PCR.