Cytophotometric study of nuclear differentiation during pollen development in Tradescantia paludosa

During pollen development the dry weight, total protein, histone, DNA, arginine, and lysine content were analysed by cytophotometric methods in partially isolated nuclei. The amount of analysed substances increased from the end of the meiosis to the mitosis of the microspores to the double of the initial values. After mitosis the ratio histone/DNA remained almost unchanged in both vegetative and generative nuclei. On the other hand a large difference in the ratio non-histone protein/DNA could be observed, the vegetative nucleus containing more non-histone protein than the generative nucleus. The rate of RNA synthesis being higher in the vegetative nuclei, these non-histone proteins may have some function in nuclear activation. The DNA of the generative nucleus is duplicated before anthesis, whilst in the vegetative nucleus the DNA content remains constant.