Biology Reference
In-Depth Information
CHAPTER THREE
Hormonal Regulation of Insect
Metamorphosis with Special
Reference to Juvenile Hormone
Biosynthesis
Kiyoshi Hiruma
*
,
†
*
Faculty of Agriculture and Life Sciences, Hirosaki University, Hirosaki, Japan
†
Graduate School of Agricultural Sciences, Iwate University, Morioka, Japan
1
Corresponding author: e-mail address: hiruma@cc.hirosaki-u.ac.jp
,
†
,1
, Yu Kaneko
*
Contents
1.
Introduction
74
2. Regulation of JH Biosynthesis
77
2.1 Genes responsible for JH biosynthesis
77
2.2 Regulation by ecdysteroid
77
2.3 Regulation by neurotransmitters
80
2.4 Regulation by peptide hormones
85
2.5 Regulation by nutrition
89
3. Molecular Action of JH on Insect Molting and Metamorphosis
90
3.1 Methoprene-tolerant (Met) as a JH receptor
90
3.2 JH responsive genes and the JH signaling pathway
91
4. Conclusion
93
Acknowledgments
94
References
94
Note Added in Proof
100
Abstract
Ecdysteroids and juvenile hormones (JHs) are key hormones that are responsible for
insect molting and metamorphosis. JH maintains the larval state and the decline of
its level in the hemolymph is crucial to elicit transformation to the pupal stage; therefore,
the precise control of JH biosynthesis is necessary for normal development and the ini-
tiation of metamorphosis. This chapter summarizes mechanisms of the regulation of JH
biosynthesis by the corpora allata and shows that several factors such as ecdysteroids,
neurotransmitters, and peptides act together in the stage-specific manner to guarantee
the accurate production of JH in each stage, in particular, in the last larval stage when
metamorphosis is initiated with the transformation of the larva to the pupa. In addition,
recent progress in understanding the JH signaling pathway is briefly discussed, includ-
ing the identification of a long elusive JH receptor.
