Reverse transcriptase families and a copia-like retrotransposon, Osser, in the green alga Volvox carteri.

By using the polymerase chain reaction (PCR) we have isolated and sequenced two distinct families of reverse transcriptase (RT) sequences from the genome of the colonial alga, Volvox carteri. Probing a genomic library with these RT clones revealed copia-like retrotransposons. One of these elements, named Osser, is 4,875 bp long, bordered by 197-bp identical long terminal repeats (LTRs), and shows the typical organization of retrotransposons belonging to the copia-Tyl group. This is the first complete copia-like retrotransposon sequence described in a green alga.