Publication Date:
2016-04-01
Description:
Chitin synthase (ChS) plays a critical role in chitin synthesis and excretion. In this study, two ChS genes ( LdChSA and LdChSB ) were identified in Leptinotarsa decemlineata . LdChSA contains two splicing variants, LdChSAa and LdChSAb . Within the first, second, and third larval instars, the mRNA levels of LdChSAa , LdChSAb , and LdChSB coincide with the peaks of circulating 20-hydroxyecdysone (20E) and juvenile hormone (JH). In vitro culture of midguts and an in vivo bioassay revealed that 20E and an ecdysteroid agonist halofenozide stimulated the expression of the three LdChS s. Conversely, a reduction of 20E by RNA interference (RNAi) of an ecdysteroidogenesis gene LdSHD repressed the expression of these LdChS s, and ingestion of halofenozide by LdSHD RNAi larvae rescued the repression. Moreover, disruption of 20E signaling by RNAi of LdEcR , LdE75 , LdHR3 , and LdFTZ-F1 reduced the expression levels of these genes. Similarly, in vitro culture and an in vivo bioassay showed that exogenous JH and a JH analog methoprene activated the expression of the three LdChS s, whereas a decrease in JH by RNAi of a JH biosynthesis gene LdJHAMT downregulated these LdChS s. It seems that JH upregulates LdChS s at the early stage of each instar, whereas a 20E pulse triggers the transcription of LdChS s during molting in L. decemlineata .
Print ISSN:
0739-4462
Electronic ISSN:
1520-6327
Topics:
Biology
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