Submitted to: Journal of Molecular Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/17/2010
Publication Date: 3/9/2010
Citation: Coates, B.S., Sumerford, D.V., Hellmich II, R.L., Lewis, L.C. 2010. A Helitron-like Transposon Superfamily from Lepidoptera Disrupts (GAAA)n Microsatellites and is Responsible for Flanking Sequence Similarity within a Microsatellite Family. Journal of Molecular Evolution. 70(3):278-288. Interpretive Summary: The control of yield-reducing caterpillar pests of U.S. crops costs growers millions of dollars each year. Our understanding of the biological processes that impact control of insect pests of corn has been enhanced by the development of genetic markers. Microsatellite DNA is a useful genetic tool, but has limitations for the study of caterpillar pests. The current research determined an underlying cause for these limitations. Knowledge from our results provides new avenues for genetic-marker development that will aid scientists from the U.S. and Europe in their evaluation of insect movement and insect resistance management strategies.
Technical Abstract: Transposable elements (TEs) are mobile DNA regions that alter host genome structure and gene expression. A novel 588 bp non-autonomous high copy number TE in the Ostrinia nubilalis genome has features in common with miniature inverted-repeat transposable elements (MITEs): high A+T content (62.3%), lack of internal protein coding sequence, and secondary structure consisting of subterminal inverted repeats (SIRs). The O. nubilalis TE has inserted at (GAAA)n microsatellite loci, and was named the microsatellite-associated interspersed nuclear element (MINE-1). Non-autonomous MINE-1 superfamily members also were identified downstream of (GAAA)n microsatellites within Bombyx mori and Pectinophora gossypiella genomes. Of 255 (GAAA)n microsatellites from the B. mori whole genome sequence, 205 (80.4%) were flanked by autonomous or non-autonomous MINE-1 elements. Autonomous B. mori MINE-1s encode zinc finger, helicase, or endonuclease domain proteins similar to those found in RepHel proteins of Helitron-like transposons, but B. mori Helitrons (Helitron_BM) proteins also encoded an optional topoisomerase domain. Evidence from autonomous B. mori MINE-1 elements suggested that superfamily members are Helitron-like TEs. Transposition of MINE-1 members in Lepidoptera has resulted in extensive disruption of (GAAA)n microsatellite loci, and prevalence has impacted genomic structure and application of microsatellite markers.