Restriction endonuclease/nick translation procedure on fixed chromosomes of the Atlantic salmon fish cell line.

We have used a restriction endonuclease/nick translation (RE/NT) procedure to study the ability of restriction enzymes to cleave DNA in fixed chromosomes of a fish cell line. This technique has proved to be very useful in revealing the chromatin heterogeneity underlying the chromosome structure that remains cryptic to other techniques also able to induce longitudinal differentiation on fish chromosomes. The differences observed in the banding patterns after nick translation procedure seem to be due, at least in part, to differences in activity among the enzymes assayed. The results obtained also reveal some evidence about the origin and evolution of the marker chromosomes of the Atlantic salmon cell line.