Dark areas in the chromosome correspond to late-replicating DNA and light ones
to early-replicating DNA.
The approach based on the modified method of Delany and Bloom (1984) shows
a greater percentage of R-banded metaphases. We suspect that this method, under
our experimental conditions, is better adapted to the asynchronic character of the
cell population.
The R-banding pattern obtained by the BrdU method will enable progress to be
made in the chromosomal characterization and karyotype analysis in fish. R-banding
techniques in fish are essential because the attempts to obtain complementary Gbands
have been unsuccessful (Delany and Bloom, 1984).