Molecular characterization of contaminant-indicative RAPD markers.

This paper describes genetic markers which can be used to study selection and genetic adaptation of organisms to radionuclide and other types of contaminant stress. Previous research using the randomly amplified polymorphic DNA (RAPD) technique has identified several markers which revealed genetic differences between contaminated and reference western mosquitofish (Gambusia affinis) populations. Experimental evidence suggested that these markers may be associated with loci involved in determining relative fitness in radionuclide-contaminated environments ("contaminant-indicative markers"). In the present study, Southern blot analyses show these markers to be highly conserved in DNA sequence and molecular length in sea urchins, mosquitofish, herring gulls and humans. Such conservation is thought to be rare among RAPD bands. Results of DNA sequencing efforts did not provide definitive evidence as to the identity of these loci, but indicated that short segments (<40 bp) of known DNA sequences were homologous to various regions of the RAPD sequences. Furthermore, the regions of homology seemed to be non-randomly distributed along the length of the RAPD markers. Although the identity of these bands is still unknown, the high degree of conservatism suggests that these loci might play an important role in molecular processes.