THE MOLECULAR CHARACTERIZATION OF THE GENOME OF MURAENA-HELENA L .1. ISOLATION AND HYBRIDIZATION OF 2 MBOI-RESTRICTED DNA FRACTIONS

To investigate the genome of the anguilliform fish Muraena helena at t he molecular level we characterized total DNA by agarose gel electroph oresis after cleavage with AluI, HaeIII, MboI, and DdeI restriction en donucleases. Subsequently, we isolated the DNA from two specific elect rophoretic fractions to be used as probes for Southern and in situ hyb ridization experiments. One such fraction showed an electrophoretic pa ttern typical of highly repetitive DNA localized in the centromeres of many chromosomes. The other fraction was shown to be located in the n ucleolar organizer region, partially coincident with 45S rDNA, and to be composed of highly repetitive sequences.