An ochre suppressor of bacteriophage T4 that is associated with a transfer RNA

Ultraviolet circular dichroism spectra have been obtained for native and heat-denatured Drosophila virilis satellite DNAs I, II and III. Gall &; Atherton (1974) have found that these DNAs have simple, unique sequences. We compare here the circular dichroism spectra of these satellite sequences with the circular dichroism spectra of synthetic DNAs of simple sequences which are combined in first-neighbor calculations. We also apply an analytical procedure for determining nearest-neighbor frequencies from the DNA spectra (Allen et al., 1972). The results are an indication of the potential usefulness and present limitations of circular dichroism measurements in confirming or determining the nearestneighbor frequencies of satellite DNAs of simple sequences.