Cited 52 times since 2015 (5.2 per year) source: EuropePMC G3 (Bethesda, Md.), Volume 5, Issue 5, 4 1 2015, Pages 719-740 Drosophila muller f elements maintain a distinct set of genomic properties over 40 million years of evolution. Leung W, Shaffer CD, Reed LK, Smith ST, Barshop W, Dirkes W, Dothager M, Lee P, Wong J, Xiong D, Yuan H, Bedard JE, Machone JF, Patterson SD, Price AL, Turner BA, Robic S, Luippold EK, McCartha SR, Walji TA, Walker CA, Saville K, Abrams MK, Armstrong AR, Armstrong W, Bailey RJ, Barberi CR, Beck LR, Blaker AL, Blunden CE, Brand JP, Brock EJ, Brooks DW, Brown M, Butzler SC, Clark EM, Clark NB, Collins AA, Cotteleer RJ, Cullimore PR, Dawson SG, Docking CT, Dorsett SL, Dougherty GA, Downey KA, Drake AP, Earl EK, Floyd TG, Forsyth JD, Foust JD, Franchi SL, Geary JF, Hanson CK, Harding TS, Harris CB, Heckman JM, Holderness HL, Howey NA, Jacobs DA, Jewell ES, Kaisler M, Karaska EA, Kehoe JL, Koaches HC, Koehler J, Koenig D, Kujawski AJ, Kus JE, Lammers JA, Leads RR, Leatherman EC, Lippert RN, Messenger GS, Morrow AT, Newcomb V, Plasman HJ, Potocny SJ, Powers MK, Reem RM, Rennhack JP, Reynolds KR, Reynolds LA, Rhee DK, Rivard AB, Ronk AJ, Rooney MB, Rubin LS, Salbert LR, Saluja RK, Schauder T, Schneiter AR, Schulz RW
The Muller F element (4.2 Mb, ~80 protein-coding genes) is an unusual autosome of Drosophila melanogaster; it is mostly heterochromatic with a low recombination rate. To investigate how these properties impact the evolution of repeats and genes, we manually improved the sequence and annotated the genes on the D. erecta, D. mojavensis, and D. grimshawi F elements and euchromatic domains from the Muller D element. We find that F elements have greater transposon density (25-50%) than euchromatic reference regions (3-11%). Among the F elements, D. grimshawi has the lowest transposon density (particularly DINE-1: 2% vs. 11-27%). F element genes have larger coding spans, more coding exons, larger introns, and lower codon bias. Comparison of the Effective Number of Codons with the Codon Adaptation Index shows that, in contrast to the other species, codon bias in D. grimshawi F element genes can be attributed primarily to selection instead of mutational biases, suggesting that density and types of transposons affect the degree of local heterochromatin formation. F element genes have lower estimated DNA melting temperatures than D element genes, potentially facilitating transcription through heterochromatin. Most F element genes (~90%) have remained on that element, but the F element has smaller syntenic blocks than genome averages (3.4-3.6 vs. 8.4-8.8 genes per block), indicating greater rates of inversion despite lower rates of recombination. Overall, the F element has maintained characteristics that are distinct from other autosomes in the Drosophila lineage, illuminating the constraints imposed by a heterochromatic milieu.
