A 1886bp fragment of the 5' end of ubiquitin (which includes the first non-coding exon, the first intron and the first 11bp of the second exon) drives expression of mei-9 tagged at the N-terminal end with Tag:FLAG.
The level of X chromosome nondisjunction seen in Ercc1X mutants derived from Ercc1X females is not altered if the flies are also carrying mei-9Ubi.T:Zzzz\FLAG.