COMPOSITIONAL CORRELATIONS IN THE NUCLEAR GENES OF THE FLATWORM SCHISTOSOMA-MANSONI

We have investigated the genome organization in the flatworm Schistoso ma mansoni. First, we analyzed the compositional distributions of the three codon positions, Second, we investigated the correlations that e xist between (1) the GC levels of exons against flanking regions, (2) the GC levels of third codon positions against flanking regions, (3) t he dinucleotide frequencies of exons against flanking regions, and (4) the GC levels of 5' against 3' regions, The modality of the distribut ion of third codon positions, together with the significant correlatio ns found, leads us to propose that the nuclear genome of this species is compositionally compartmentalized.