DNA reassociation kinetics and genome complexity of a fish ( Psetta maxima: Teleostei) and its gut parasite ( Bothriocephalus gregarius: cestoda)

Abstract

1. 1. The genomic structure of a fish ( Psetta maxima) and of a Tapeworm ( Bothriocephalus), who form a close host-parasite association, was determined by reassociation kinetics experiments. 2. 2. Spectrophotometric readings of single-stranded versus double-stranded DNA separated on hydroxylapatite columns after reassociation at Cot values ranging from 0.0001 to 10 5 allowed the drawing of the reassociation curves of both genomes. 3. 3. Different fractions according to their degree of repetitivity were evidenced, and the relative amounts of repetitive versus single-copy sequences, as well as their complexity, were calculated. 4. 4. It appears that the amount of non-repetitive DNA is lower in the Tapeworm than in its vertebrate host, although the complexity of these single-copy sequences is the same.