Changes in the Content of DNA and NYS-stained Nuclear, Nucleolar and Cytoplasmic Proteins in Cortex Cells of Pea (Pisum sativum cv. De Grace) Roots Treated with Cadmium

Abstract

Summary Roots of Pisum sativum cv. De Grace growing in water or cadmium (Cd) solution at a concentration of 10 -4 M were the object of the present studies. Using double staining Feulgen-NYS technique the amounts of DNA, nuclear, nucleolar and cytoplasmic proteins were established. In the meristematic zone, treatment with Cd lowers the mean DNA as a result of the decrease in 2-4C, 4C DNA nuclei numbers and higher 2C DNA nuclei pool. The mean content of nuclear proteins diminishes whereas the amount of nucleolar and cytoplasmic proteins increases despite the fact that the protein level per volume unit of the latter organelle drops. In the differentiated zone of the Cd treated roots the higher mean DNA content results from the enhanced pool of 4-8C and 8C cells. However, the amount of nuclear proteins is similar whereas that of the nucleolar proteins is higher than in the control material. The amount of cytoplasmic proteins considerably diminishes in the presence of the tested metal. The protein content in the studied organelles increases with the cell ploidy. The cytoplasmic proteins in the cells with 4C content (control) and 8C (Cd), the amount of which diminishes in spite of the higher DNA content, are the exception to this rule. The significance of these findings and understanding the mechanism of cadmium toxicity is discussed.