Quantitative microfluorometric evaluation of DNA content in nerve cells of the Pulmonate Gastropod Planorbarius corneus has indicated that the increase in nuclear volume is due to DNA amplification. Indeed, it has been observed that the DNA contents are scattered at random between 2C and 1,000C values. This is not in agreement with the occurrence of repeated duplications of the whole genome. Furthermore, chromatin photo-oxidation, a technique useful in discriminating GC-rich from AT-rich DNAs, suggests that DNA amplification involves GC-rich sequences
