title: Genotypic effects, maternal effects and grand-maternal effects of immobilized derivatives of the transposable element mariner.
abstract: The baseline rate of spontaneous integration of the autonomous mariner element Mos1 into the germline of Drosophila melanogaster is estimated as 16 +/- 5% (mean +/- SE) among fertile G0 flies. However, the transformation rate is reduced approximately 20-fold in Mos1 constructs with exogenous DNA in the size range 5-12 kb inserted into the SacI site. To provide alternative Mos1 helper plasmids for transformation experiments, two types of Mos1-promoter fusions were constructed: hsp-70:Mos1 and hsp26-Sgs3:Mos1. The former has the Mos1 coding region driven by the hsp70 heat-shock promoter; the latter has it driven by the basal Sgs3 promoter under the control of the hsp26 female-germline specific transcriptional regulator. When introduced into D. melanogaster by P-element-mediated germline transformation, these elements are unable to transpose or excise in the presence of autonomous Mos1-related elements (they are "marooned") because the 5' inverted repeat of Mos1 is missing. As expected, the hsp26-Sgs3:Mos1 fusions exhibit a significantly greater rate of germline excision of a target mariner element than do the hsp70:Mos1 fusions. Unexpectedly, the rate of excision of target mariner elements induced by hsp26-Sgs3:Mos1 is the same in the male germline as in the female germline. Both hsp:Mos1 fusions show strong germline expression and a maternal effect of the mariner transposase. A significant grand-maternal effect of the hsp:Mos1 fusions was also detected as a result of a maternal effect on the germline of the F1 progeny. Among flies carrying the promoter fusions inherited maternally, about three-quarters of the overall rate of germline excision derives from the direct genotypic effect and about one-quarter results from the grand-maternal effect. Despite the strong somatic expression of the hsp:Mos1 fusions, mariner transformants carrying a white+ reporter gene at the SacI site remained stable in the soma.
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
authors.forename: A R
authors.initials: AR
authors.lastname: Lohe
authors.forename: D A
authors.initials: DA
authors.lastname: Lidholm
authors.forename: D L
authors.initials: DL
authors.lastname: Hartl
mesh_terms: D000818:Animals; D004251:DNA Transposable Elements / Q000235:genetics*; D004331:Drosophila melanogaster / Q000235:genetics*; D005127:Eye Color / Q000235:genetics; D005260:Female; D017344:Genes, Insect; D005838:Genotype; D008297:Male; D016254:Mutagenesis, Insertional; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D017384:Sequence Deletion; D014170:Transformation, Genetic
chemical_list: D004251:DNA Transposable Elements; D011993:Recombinant Fusion Proteins