Abstract: 【Aim】 To further research the hormone regulation of nutrition metabolism, we analyzed the transcription levels of pyridoxal kinase (PLK) and pyridoxine-5′-phosphate oxidase (PNPO) of the silkworm, Bombyx mori, treated with 20-hydroxyecdysone (20-E) and juvenile hormone analogue (JHA). 【Methods】 The day-1, day-3 and day-5 5th instar larvae of B. mori were fed with 20-E or JHA, and those fed on distilled water were used as the control. We assayed the transcriptional levels of PLK and PNPO in silk glands of the treated larvae at 24 and 48 h post treatment by using real-time quantitative PCR.【Results】 In the day-1 5th instar larvae treated with 20-E for 24 and 48 h, respectively, the transcriptional levels of PLK and PNPO significantly increased compared with the control (P<0.01). In the day-3 5th instar larvae treated by 20-E, the transcriptional level of PLK decreased compared with the control at 48 h after treatment (P<0.05), whereas the transcriptional level of PNPO significantly increased compared with the control at 24 and 48 h after treatment (P<0.01). In the day-5 5th instar larvae treated with 20-E, the transcriptional levels of PLK and PNPO had no apparent change. In the day-1 5th instar larvae treated with JHA, the transcriptional levels of PLK and PNPO had no change; in the day-3 5th instar larvae treated with JHA, however, the transcriptional level of PLK decreased compared with the control at 48 h after treatment (P<0.05), and the transcriptional level of PNPO decreased compared with the control at 24 and 48 h after treatment (P<0.01). In the day-5 5th instar larvae treated with JHA for 24 and 48 h, respectively, the transcriptional levels of PLK and PNPO significantly decreased compared with the control (P<0.01). 【Conclusion】 The transcriptional expression of PLK and PNPO is influenced by 20-E and JHA, 20-E promotes them in the early stage of the 5th instar larvae while JHA represses them in late stages of the 5th instar larvae. These results lay the foundation for further research on hormone regulation of VB₆.

Key words: Bombyx mori, 20-hydroxyecdysone, juvenile hormone analogue, pyridoxal kinase, pyridoxine-5′-phosphate oxidase, transcriptional level