Satellite DNAs in Crustacea: Two Different Components with the Same Density in Neutral CsCI Gradients

Abstract

SINCE the first reports of satellite DNAs in the Jonah crab, Cancer borealis¹, and in the mouse², satellite DNAs have been described for a number of animal species, both vertebrate and invertebrate. We now report our findings on the satellite DNAs of five species of Crustacea. We find at least one and in some instances two DNA satellites in each species and were surprised to discover that two distinctly different satellite DNAs band at the same density, 1.677 g/cm³, in CsC1. DNAs banding at this density are usually assumed to be “crab poly d(A–T)”, the satellite DNA composed of more than 90 per cent alternating adenylate and thymidylate residues^3,4. It now seems that this cannot be assumed without further characterization of the DNA species having that density. We emphasize that the satellites described in this note are not mitochondrial in origin: even though we find a mitochondrial DNA of ρ = 1.688 g/cm³ in each of the five species, the quantity is too small to be detectable in a “total” DNA preparation. These data will be presented elsewhere.