[Properties of satellite DNA of Citrus limon].

DNA components of C. limon were preparatively separated by equilibrium ultracentrifugation in CsCl density gradient (buoyant density of the main component in CsCl density gradient--1,693 g.cm-3; satellite component--1,712 g.cm-3). The properties of individual DNA fractions were investigated. One third of satellite DNA melts in broad interval of temperature, the rest--at a higher temperature as a narrow peak, containing two components. The half breadth of transition temperature of the peak is 3 degrees. By the kinetics of reassociation it is shown, that 64% of satellite DNA is presented by a fast reassociating component with length of a repeated unit approximately 1,8.10(3) nucleotide pairs. Calculations, carried on the basis of the values of t m and buoyant density show, that satellite DNA per one cytosine residue contains 1,36 5-methylcytosine. In density gradients of actinomycin D--CsCl and Hg2+--Cs2SO4 satellite DNA is divided into several components.