Long interspersed elements in three species of Gracilaria (Gracilariaceae, Rhodophyta)

摘要

In order to find out whether long interspersed elements (LINEs) existed in macro-algae genomes or not, we tested the LINE homologues in representative families (species): Gracilaria (G.eucheumoides Harv., G. tenuistipitata Chang et Xia, and G. textorii (Sur) De-Toni), Laminaria (L. longissima Miyabe and L. japonica Aresch.), and Ulva (U. lactuca L. and U. pertusa Kjellm.) during 2004 to 2005. Polymerase Chain Reaction (PCR) was carried out with degenerate oligonucleotide primers designed from LINEs of rice homologues and Cin 4 of maize. Cloning and nucleotide sequencing of the PCR products revealed that 4 clones that derived from 3 species of Gracilaria have LINE homologues. The nucleotide sequences of the 4 LINE homologues diverged greatly, but the amino acid sequences deduced from them were relatively conserved. The endonuclease regions of the LINE homologues greatly diverged from that of other plants, but they had closer phylogenetic relationship to Zepp elements in Chlorella sp., which indicated that sequence divergence by vertical transmission has been a major influence on the evolution of algal LINEs.