Evolution of a heterochromatic domain, the Muller F element, in Drosophila / Sophophora. SCR Elgin¹, M Burg², J DiAngelo³, A Haberman⁴, C Jones⁵, L Kadlec⁶, SCS Key⁷, J Leatherman⁸, GP McNeil⁹, H Mistry¹⁰, A Nagengast¹⁰, DW Paetkau¹¹, S Parrish¹², L Reed¹³, S Schroeder¹⁴, S Smith¹⁵, M Wawersik¹⁶, L Zhou¹⁷, CD Shaffer¹, W Leung¹. 1) Washington U MO; 2) Grand Valley St MI; 3) Hofstra U NY; 4) Oberlin OH; 5) Moravian PA; 6) Wilkes U PA; 7) NC Central U NC; 8) Northern Colorado CO; 9) York/CUNY NY; 10) Widener U PA; 11) St Mary's IN; 12) McDaniel MD; 13) Alabama-Tuscaloosa AL; 14) Webster U MO; 15) Arcadia U PA; 16) William & Mary VA; 17) U Pittsburgh PA.

   The Muller F element in Drosophila is unusual because it exhibits both heterochromatic and euchromatic properties. Students in the Genomics Education Partnership are analyzing this region (and Muller D euchromatic reference regions) in several Drosophila species to chart the evolution of this unique domain and its genes. Students have generated 4 million bases of high quality sequence and manually curated 1000 gene models from 4 species: D. erecta, D. virilis, D. mojavensis and D. grimshawi. Muller F elements have a higher repeat density than euchromatic domains; we find that their genes are larger, with more exons and larger introns, and show lower codon bias. D. mojavensis has the highest repeat density among these F elements, which partially accounts for the larger size of the banded region (1.7 Mb vs. 1.2 Mb in D. melanogaster). The distribution and types of repeats found in these regions are being analyzed. Histone modification enrichment patterns are largely conserved among F elements. Despite a large number of gene rearrangements, most of the genes found on the D. melanogaster F remain on the F elements in the other species, but there have been at least 13 transposition events. Analysis of the subset of such genes found in a euchromatic domain in at least one species shows that these genes typically adopt the properties of their local genome environment, with some exceptions. The carefully sequenced and annotated domains generated by GEP students provide a high quality resource for these and other types of analyses. Support: HHMI grant 52005780 & NIH grant R01 GM068388 to SCRE.