Abstract to be presented at ASIH meeting, June 1996. Contributed to DFC WWW by Dr. Bruce Turner


An Active L1-like LINE Mobile Sequence Family in Fish Genomes: Its Variation and Divergence In Death Valley Pupfishes.

David D. Duvernell1, Bruce J. Turner1 and Holly A. Wichman2

1Department of Biology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061. 2Department of Biological Sciences, University of Idaho, Moscow, Idaho 83844.

A putative retrotransposable element has been partially characterized in fish genomes. The element contains a DNA sequence similar to the mammalian LINE element family. A segment of a retrotransposon reverse transcriptase gene (309 bp) was initially isolated from pupfish (Cyprinodon) genomic DNA by PCR with degenerate primers and identified by a BLAST search of DNA and protein sequence databases. Parsimony analysis with several LINE sequences from vertebrates and plants confirmed the similarity of the fish reverse transcriptase sequence with mammalian L1 sequences. We have subsequently designed pupfish sequence- specific primers and amplified similar reverse transcriptase sequences from other teleosts, including zebra fish, Cichlasoma octofasciatus, Lamprologus kungweensis, Melanochromis auratus, Fundlulus confluentus, Rivulus marmoratus and Poecilia latipinna. We designate this new family of transposable elements as the "swimmer" family.

Genomic DNA hybridization studies of Death Valley pupfishes were conducted utilizing restriction endonucleases which do not cut within the putative retrotransposon sequence. This technique generated highly individual-specific restriction patterns which indicate that some members of the retrotransposon family may be actively mobile. Additionally, the population-specificity of some restriction fragments has revealed striking examples of differentiation occurring within a few hundred to two thousand years. These analyses revealed more variation and divergence within and among populations of Cyprinodon nevadensis and C. salinus than have been detected with all previous molecular techniques combined. They have allowed us to demonstrate the genetic distinctiveness of populations which otherwise have appeared virtually indistinguishible, including those with identical allozyme, RAPD and mtDNA haplotype profiles.

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