ROn-1 SINEs: a tRNA-derived, short interspersed repetitive DNA element from Oreochromis niloticus and its species-specific distribution in Old World cichlid fishes.

A SINE-like repetitive element (ROn-1) has been cloned from the tilapiine cichlid fish Oreochromis niloticus. The element is 345 base pairs (bp) in length and consists of a transfer-RNA-like domain with putative RNA polymerase III recognition sequences, a tRNA-unrelated region, and a poly(A) tail. Approximately 6000 copies of ROn-1 occur in the haploid genome of O. niloticus. Southern blot analysis revealed that ROn-1 is an abundant element in the genomes of many African cichlid fishes, but absent from the genome of the Indian cichlid Etroplus.