CHARACTERIZATION OF A REPETITIVE DNA ELEMENT IN A BROWN ALGAL VIRUS

We describe a family of repetitive sequences found in viruses infectin g the brown alga Feldmannia sp. Previously we have demonstrated that t he dsDNA genomes of viruses infecting one Feldmannia sp. isolate exist as two size classes of 160 and 179 kb. Repetitive sequences within th ese genomes were first demonstrated based on the anomalous hybridizati on among five BamHI fragments from digested virus DNA. Sequence analys is of one of those fragments, B2.4, revealed the presence of 173-bp di rect repeats. The restriction maps of the cross-hybridizing BamHI frag ments in the two FsV (Feldmannia sp. virus) genome size classes show t hat these repeats are not widely dispersed, rather they are confined t o a small region of each virus genome. We estimate the number of these repeats in the 179-kb genome to be about 109 and in the 160-kb genome to be about 41. In the 179-kb genome, the repeats are contained withi n a 22-kb region, about 12% of that virus genome, and in the 160-kb ge nome the repeats are contained within a 10-kb region, about 6% of the genome. The difference in repeat numbers can account for 62% of the si ze difference between the two size classes of the FsV genome. (C) 1995 Academic Press, Inc.