Genetic tools to study juvenile hormone action in Drosophila

A A Baumann,D L Miller,J W Truman,R Warner,L M Riddiford,J N Etheredge,S Picard,M J Texada,H M Chen

doi:10.1038/s41598-017-02264-4

A A Baumann, D L Miller + Show 7 more

Open Access

https://doi.org/10.1038/s41598-017-02264-4

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Abstract

The insect juvenile hormone receptor is a basic helix-loop-helix (bHLH), Per-Arnt-Sim (PAS) domain protein, a novel type of hormone receptor. In higher flies like Drosophila, the ancestral receptor germ cell-expressed (gce) gene has duplicated to yield the paralog Methoprene-tolerant (Met). These paralogous receptors share redundant function during development but play unique roles in adults. Some aspects of JH function apparently require one receptor or the other. To provide a foundation for studying JH receptor function, we have recapitulated endogenous JH receptor expression with single cell resolution. Using Bacteria Artificial Chromosome (BAC) recombineering and a transgenic knock-in, we have generated a spatiotemporal expressional atlas of Met and gce throughout development. We demonstrate JH receptor expression in known JH target tissues, in which temporal expression corresponds with periods of hormone sensitivity. Larval expression largely supports the notion of functional redundancy. Furthermore, we provide the neuroanatomical distribution of JH receptors in both the larval and adult central nervous system, which will serve as a platform for future studies regarding JH action on insect behavior.

Highlights

Juvenile hormone (JH) drives various aspects of insect physiology
We demonstrate JH receptor expression in known JH target tissues, the temporal dynamics of which are consistent with periods of hormone sensitivity
In this study we recapitulated endogenous JH receptors (JHR) expression using transgenic D. melanogaster carrying either (1) one of several Bacteria Artificial Chromosome (BAC) comprised of a gce or Met coding sequence, interrupted by a GAL4::p65 or LexA::p65 driver fragment replacing the first exon, and flanked bilaterally by 40 kb of genomic DNA (Fig. 1a,b), or (2) a T2A-GAL4 fusion construct inserted in frame into the native gce genomic locus (Fig. 1a)

Summary

Introduction

Juvenile hormone (JH) drives various aspects of insect physiology. A well-documented role for this hormone is to prevent early metamorphosis. As larvae gain competence to undergo metamorphosis[1], the JH titer drops, reducing expression of the antimetamorphic, JH response gene Kr-h1, which lifts suppression on pupal or adult developmental programs[2, 3]. This aspect of JH activity has promoted the synthesis of batteries of compounds employed to combat pest insects. We demonstrate JH receptor expression in known JH target tissues, the temporal dynamics of which are consistent with periods of hormone sensitivity In both larvae and adults, paralog-specific expression was evident predominantly in the central nervous system (CNS), suggesting that they have distinct contributions to JH-regulated behavior and CNS development. We provide a neuroanatomical atlas of JHR expression, which will facilitate future studies regarding JH action in CNS development and function

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