The maize b1 paramutation control region causes epigenetic silencing in Drosophila melanogaster.
Paramutation is an epigenetic process in which a combination of alleles in a heterozygous organism results in a meiotically stable change in expression of one of the alleles. The mechanisms underlying paramutation are being actively investigated, and examples have been described in both plants and mammals, suggesting that it may utilize epigenetic mechanisms that are widespread and evolutionarily conserved. Paramutation at the well-studied maize b1 locus requires a control region consisting of seven 853 bp tandem repeats. To study the conservation of the epigenetic mechanisms underlying seemingly unique epigenetic processes such as paramutation, we created transgenic Drosophila melanogaster carrying the maize b1 control region adjacent to the Drosophila white reporter gene. We show that the b1 tandem repeats cause silencing of the white reporter in Drosophila. A single copy of the tandem repeat sequence is sufficient to cause silencing, and silencing strength increases as the number of tandem repeats increases. Additionally, transgenic lines with the full seven tandem repeats demonstrate evidence of either pairing-sensitive silencing and silencing in trans, or epigenetic activation in trans. These trans-interactions are dependent on repeat number, similar to maize b1 paramutation. Also, as in maize, the tandem repeats are bidirectionally transcribed in Drosophila. These results indicate that the maize b1 tandem repeats function as an epigenetic silencer and mediate trans-interactions in Drosophila, and support the hypothesis that the mechanisms underlying such epigenetic processes are conserved.
Department of Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada. lori.mceachern@dal.ca
Lori A
LA
McEachern
Vett K
VK
Lloyd
D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D000818:Animals; D030801:Animals, Genetically Modified; D018744:DNA, Plant / Q000235:genetics*; D029721:Drosophila Proteins / Q000235:genetics*; D004331:Drosophila melanogaster / Q000235:genetics; D044127:Epigenesis, Genetic; D005123:Eye / Q000378:metabolism; D005136:Eye Proteins / Q000235:genetics*; D005260:Female; D005786:Gene Expression Regulation; D020868:Gene Silencing; D056426:Genetic Loci / Q000235:genetics; D005838:Genotype; D008297:Male; D010858:Pigmentation / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020080:Tandem Repeat Sequences / Q000235:genetics; D003313:Zea mays / Q000235:genetics
D018528:ATP-Binding Cassette Transporters; D018744:DNA, Plant; D029721:Drosophila Proteins; D005136:Eye Proteins; C059254:w protein, Drosophila