Abstract
Juvenile hormone (JH) contributes to the regulation of larval molting and metamorphosis in insects. Herein, we comprehensively identified 55 genes involved in JH biosynthesis, metabolism and signaling in the silkworm (Bombyx mori) as well as 35 in Drosophila melanogaster, 35 in Anopheles gambiae, 36 in Apis mellifera, 47 in Tribolium castaneum, and 44 in Danaus plexippus. Comparative analysis showed that each gene involved in the early steps of the mevalonate (MVA) pathway, in the neuropeptide regulation of JH biosynthesis, or in JH signaling is a single copy in B. mori and other surveyed insects, indicating that these JH-related pathways or steps are likely conserved in all surveyed insects. However, each gene participating in the isoprenoid branch of JH biosynthesis and JH metabolism, together with the FPPS genes for catalyzing the final step of the MVA pathway of JH biosynthesis, exhibited an obvious duplication in Lepidoptera, including B. mori and D. plexippus. Microarray and real-time RT-PCR analysis revealed that different copies of several JH-related genes presented expression changes that correlated with the dynamics of JH titer during larval growth and metamorphosis. Taken together, the findings suggest that duplication-derived copy variation of JH-related genes might be evolutionarily associated with the variation of JH types between Lepidoptera and other insect orders. In conclusion, our results provide useful clues for further functional analysis of JH-related genes in B. mori and other insects.
Highlights
In insects, the sesquiterpenoid juvenile hormone (JH) is synthesized and released from the corpora allata (CA) and cooperates with the steroid 20-hydroxyecdysone (20E) that is synthesized and released from the prothoracic glands to orchestrate insect molting, growth, metamorphosis, via stage-specific changes in the titers of these two endocrine hormones (Dubrovsky, 2005)
The decrease in JH titer is controlled through its metabolism, which is mainly catalyzed by JH esterase (JHE), JH epoxide hydrolase (JHEH), and JH diol kinase (JHDK)
Inventory of genes involved in JH biosynthesis, metabolism, and signaling in B. mori and other insects
Summary
The sesquiterpenoid juvenile hormone (JH) is synthesized and released from the corpora allata (CA) and cooperates with the steroid 20-hydroxyecdysone (20E) that is synthesized and released from the prothoracic glands to orchestrate insect molting, growth, metamorphosis, via stage-specific changes in the titers of these two endocrine hormones (Dubrovsky, 2005). The dynamic change in JH titer is mainly modulated through biosynthetic and metabolic pathways that are cata-. JH biosynthesis involves the mevalonate (MVA) pathway and the isoprenoid branch. The isoprenoid branch converts the FPP into JH through several continuous steps of oxidization and epoxidation (Kinjoh et al, 2007). Proper nutritional signals can affect the release of AT and AS by the brain and further results in the activation or inhibition of JH biosynthesis (Noriega, 2004). Several genes involved in JH biosynthesis, metabolism, and signaling have been previously analyzed in insects (Noriega et al, 2006; Kinjoh et al, 2007; Hua-Jun et al, 2011)
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