title: Ac-immobilized, a stable source of Activator transposase that mediates sporophytic and gametophytic excision of Dissociation elements in maize.
abstract: We have identified and characterized a novel Activator (Ac) element that is incapable of excision yet contributes to the canonical negative dosage effect of Ac. Cloning and sequence analysis of this immobilized Ac (Ac-im) revealed that it is identical to Ac with the exception of a 10-bp deletion of sequences at the left end of the element. In screens of approximately 6800 seeds, no germinal transpositions of Ac-im were detected. Importantly, Ac-im catalyzes germinal excisions of a Ds element resident at the r1 locus resulting in the recovery of independent transposed Ds insertions in approximately 4.5% of progeny kernels. Many of these transposition events occur during gametophytic development. Furthermore, we demonstrate that Ac-im transactivates multiple Ds insertions in somatic tissues including those in reporter alleles at bronze1, anthocyaninless1, and anthocyaninless2. We propose a model for the generation of Ac-im as an aberrant transposition event that failed to generate an 8-bp target site duplication and resulted in the deletion of Ac end sequences. We also discuss the utility of Ac-im in two-component Ac/Ds gene-tagging programs in maize.
authors.affiliation: Dept. of Plant Breeding and Genetics, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Liza J
authors.initials: LJ
authors.lastname: Conrad
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Brutnell
mesh_terms: D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D017931:DNA Primers; D004251:DNA Transposable Elements / Q000235:genetics*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010641:Phenotype; D012098:Reproduction / Q000235:genetics; D017422:Sequence Analysis, DNA; D015533:Transcriptional Activation / Q000235:genetics*; D019895:Transposases / Q000235:genetics*; D003313:Zea mays / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development
chemical_list: D017931:DNA Primers; D004251:DNA Transposable Elements; D019895:Transposases