Abstract: The researches focusing on key developmental genes in non-holometabola insects are relatively insufficient, especially for the reports on the structure and sequences of Hox genes. In order to understand the structure of Ubx gene (a member of Hox genes) in non-holometabola insects, we selected the large milkweed bug, Oncopeltus fasciatus (Dallas, 1852), as a representative, and used RACE and RT-PCR to clone the whole ORF of Ubx gene. The results showed that the full-length ORF of Ubx gene of O. fasciatus (Of-Ubx) is 888 bp, encoding 295 aa. Southern blot analysis verified that Of-Ubx exists as a single copy and has introns within it. We found alternative splicing sites between YPWM and homeodomain motif, which lead to 3 types of transcript variants. Compared with the Ubx gene from Drosophila melanogaster (Meigen, 1830), Of-Ubx had similar splicing sites, conserved elements around splicing sites and isoform combination, suggesting that their splicing mechanism should be similar. This is the first detailed report about the multiple transcripts of Ubx genes within Insecta except for the genus Drosophila.

Key words: Oncopeltus fasciatus, Ubx gene, cloning, open reading frame, multiple transcripts