Novel splice variants of the cytochrome P450 9A19 gene in the domestic silkworm Bombyx mori

CYP9 gene family members participate in neutralization pathways associated with pesticide resistance. Alternative splicing ultimately plays a role in increasing the diversity of the proteome through increasing transcriptome diversity. Here, we characterized various novel CYP9A19 isoforms in Bombyx mori. We first identified an exon 4 deletion isoform that was 203 bp smaller than expected due to a deletion of exon 4 from the protein coding sequence (CDS) region of the CYP9A19 cDNA. Within the CYP9A19 cDNA, there is a 176 bp 5′-untranslated region (UTR); reverse transcription-polymerase chain reaction results showed 74 bp lower and 122 bp higher molecular-weight products compared with the expected size from the 5′-UTR of CYP9A19 cDNA in B. mori. Additionally, we found a new sequence (5′-GTCTCAGGTTCAGGGCTCTAGCAATTTTTCACAG-3′) in the 5′-UTR of CYP9A19. Currently, our understanding of the various CYP9A19 isoform functions in pesticide degradation and resistance and insect development and differentiation stages remains limited. Therefore, additional studies on the alternative splicing process are needed to verify the biological role of the novel splicing variant of CYP9A19 in B. mori. Our findings may provide insight into the genetic background of the processes and mechanisms underlying the stages of insect development and differentiation in lepidoptera species.