A new family of repetitive, retroposon-like sequences in the genome of the rainbow trout.

We have identified a new family of interspersed, moderately repetitive DNA elements, termed the RSg-1 family, in the genome of the rainbow trout. Two of the elements examined here are situated upstream of sequences which code for trout nuclear proteins; a protamine gene (p101) and the clustered histone H4 gene. Sequence comparison of various RSg-1 elements indicated a high degree of nucleotide sequence homology between different members of the family. These repetitive elements exhibit well defined 3' ends which contain poly(A) segments preceded by the consensus polyadenylation signal AATAAA. Sequences flanking the 3' end of the poly(A) tract also conform to a consensus sequence. A similar sequence is also found flanking the 5' terminus of the element in the protamine clone p101, and thus may represent a target-site duplication generated upon insertion of the element into the genome. These characteristics, together with the heterogeneous nature of the 5' ends of the elements, are reminiscent of processed pseudogenes and retroposons such as the mammalian L1 family of interspersed repetitive elements.