Maize line MON 863 was produced by biolistic transformation of the inbred line A634 using linearized plasmid PV-ZMIR13 DNA purified following Mlu I restriction endonuclease digestion. The introduced DNA contained the modified cry3Bb1 gene from B. thuringiensis subsp. kumamotoensis. The modified cry3Bb1 gene encodes a protein of 653 amino acids whose amino acid sequence differs from that of the wild-type protein by the addition of an alanine residue at position 2 and by seven amino acid changes.

The introduced DNA also contained a copy of the neomycin phosphotransferase II (NPTII) encoding gene (nptII) derived from the Tn5 transposon of Escherichia coli. Due to the use of a unique restriction site for the excision of nptII from Tn5, this gene cassette also contains a 153 bp of the 378 bp bleomycin binding protein gene (ble).This segment of ble is located 20 nucleotides downstream of the nptII stop codon, and it is joined to the T-nos.

The mRNA that is transcribed from the nptII cassette contains tandem open reading frames (ORF). The proximal ORF is the complete nptII coding sequence while the distal ORF encodes approximately 40% of the bleomycin binding sequence. Due to differences in the mechanism of initiation of translation between procaryotic and eucaryotic organisms, it is highly unlikely that the partial ble ORF will be translated into protein in Mon863. This means that nptII will be expressed in Mon863, but the ble fragment will not. According to the US FDA, if the partial ble gene were translated into protein, the truncated peptide would not dimerize because it lacks the necessary amino acids to dimerize, and also lacks approximately 50% of the residues that are involved in bleomycin binding.

Molecular analyses of the transformed plant show that one DNA insert has been transferred to the genome of Mon863. This insert contains one copy of the Mlu I plasmid fragment used in transformation. Both cassettes are intact and no DNA from plasmid backbone was detected.