Analysis of cetacean DNA: II. Localization of 18S and 28S ribosomal RNA cistrons in a heavy DNA component

Abstract

DNA was extracted from 10 cetacean species. Three species belong to the sub‐order Mysticeti (baleen whales) and seven to the Odontoceti (toothed whales). Isopycnic centrifugation of these DNAs to equilibrium in neutral CsCl shows the following features in the analytical ultracentrifuge. The main band has an average buoyant density of 1.700 g/ml. A satellite (“shoulder”) appears in four species: Balaenoptera acutorostrata, B. borealis, Platanista indi and Physeter catodon with a buoyant density of 1.710, 1.708, 1.714 and 1.720 g/ml, respectively. In most species the main band also shows a pronounced asymmetry being wider on the heavy side and its top was seen to be divided into two components in one species. B. physalus 28S and 18S H3 RNA of high specific activity were hybridized with B. physalus unlabelled DNA. The position of the 28S and 18S hybridization peaks corresponds to a buoyant density of circa 1.705 g/ml. This location is different from that of the satellites observed in the other balenopterid species. © 1977 Mendelian Society of Lund