The Ds1 transposable element acts as an intron in the mutant allele Adh1-Fm335 and is spliced from the message.

The Ds-induced maize Adh1 allele Adh1-Fm335 retains its anaerobic regulation and normal transcription start site despite the presence of the 405 bp Ds element in the 5' untranslated leader region of the gene. The steady state level of Adh1-specific transcript is reduced to about 1% that of the progenitor or revertant alleles. Run-on transcription studies show that the reduced level of Adh1 specific mRNA is not attributable to a decreased transcription rate. S1 mapping indicates that the Ds element is spliced from the Adh1-Fm335 transcript using a donor site 14 bp into the Ds element and an acceptor site at the 3' junction of the Ds element with the flanking genome DNA.