The goal of this work is to understand the structure and possible function of highly repeated DNA sequences and to elucidate the mechanisms by which such sequences are amplified either in tandem or through transposition to new genomic loci. To understand the maintenance and plasticity of satellite DNA sequences we are studying junctions between these long tandem repeats and low copy number genomic sequences. One particular single copy sequence that is conserved in primates and rodents and is joined to species specific satellite DNA in each species analyzed is being characterized. The extensive and rapid changes that occur in satellite DNA sequence on an evolutionary scale are being applied to taxonomic and evolutionary problems: in particular, evolutionary relationships in the carnivores are being investigated. To understand the significance of the LINE-1 family of interspersed repeats, the potential for some family members to be functional genes and encode a protein is being investigated. cDNA clones representing polyadenylated, cytoplasmic LINE-1 RNA from human teratocarcinoma cells have been isolated; the cDNA sequences have defined a subset of LINE-1 sequences that appear to be specifically transcribed (or processed) in these cells. The subset contains at least 19 different members, most of which do not have completely open reading frames and therefore could not encode a full length LINE-1 protein.
