Molecular characterization of the first intact Transib transposon from Helicoverpa zea
Song Chen, firstname.lastname@example.org and Xianchun Li, email@example.com. University of Arizona, department of entomology, Forbes 410 PO BOX 210036, Tucson, AZ
Transib is a superfamily of DNA transposons recently reconstructed in silico from degenerate elements in the genomes of Drosophila melanogaster and Anopheles gambiae. Here we report characterization of the first intact Transib transposon designated Hztransib from Helicoverpa zea. The full-length Hztransib has 3518 bp including a 5’ terminal inverted repeat (TIR) of 552 bp, a promoter sequence of 381 bp, an intact open reading frame encoding 507 amino acids, and a 3’ TIR of 502 bp, and is flanked by 5 bp (GCTCG) target site duplications. The full-length Hztransib is transcriptionally active, producing an 3’-truncated mRNA lacking a termination codon (known as nonstop mRNA) due to alternative polyadenylation in two somatic tissues (midgut and fat body) and one germline tissue (ovary). While the full-length Hztransib inserts into the 5’-flanking region of a xenobiotic- metabolizing P450 gene CYP6B8 in the midgut cell line, it does not inserts into the 5’-flanking region of CYP6B8 in the laboratory strain. Such an insertion dimorphism, together with its complete structural features and mRNA transcripts, demonstrates that the full-length Hztransib not only represents the first intact Transib element in any organism, but has been recently transposed in H. zea. The fact that the intact Hztransib is transcribed into a 3’-truncated nonstop mRNA which may encode a nonfunctional transposase or be blocked from further translation via nonstop mRNA decay suggests that it is silenced at the post-transcriptional, translational, and/or transpositional levels.
Species 1: Lepidoptera Noctuidae Helicoverpazea (corn earworm, bollworm)