Characterization of Short Interspersed Elements (SINEs) in a Red Alga,Porphyra yezoensis

Short interspersed element (SINE)-like sequences referred to as PySN1 and PySN2 were identified in a red alga, Porphyra yezoensis. Both elements contained an internal promoter with motifs (A box and B box) recognized by RNA polymerase III, and target site duplications at both ends. Genomic Southern blot analysis revealed that both elements were widely and abundantly distributed on the genome. 3′ and 5′ RACE suggested that PySN1 was expressed as a chimera transcript with flanking SINE-unrelated sequences and possessed the poly-A tail at the same position near the 3′ end of PySN1.