Juvenile hormone signaling during reproduction and development of the linden bug, Pyrrhocoris apterus Vlastimil Smykal a, b, 1 , Adam Bajgar a, b, 1 , Jan Provaznik a, b , Silvie Fexova a, b , Marcela Buricova a, b , Keiko Takaki a , Magdalena Hodkova a , Marek Jindra a, c, * , David Dolezel a, b, * a Biology Center, Academy of Sciences of the Czech Republic, 37005 Ceske Budejovice, Czech Republic b Department of Molecular Biology, Faculty of Sciences, University of South Bohemia, 37005 Ceske Budejovice, Czech Republic c Animal, Food and Health Sciences Division, Commonwealth Scientific and Industrial Research Organization, North Ryde, NSW 2113, Australia article info Article history: Received 31 October 2013 Received in revised form 9 December 2013 Accepted 11 December 2013 Keywords: Methoprene-tolerant bHLH-PAS Diapause Oogenesis Vitellogenesis Metamorphosis abstract Juvenile hormone (JH), a sesquiterpenoid produced by the insect corpus allatum gland (CA), prevents metamorphosis in larvae and stimulates vitellogenesis in adult females. Whether the same JH signaling pathway regulates both processes is presently unknown. Here, we employ the robust JH response during reproduction and development of the linden bug, Pyrrhocoris apterus, to compare the function of key JH- signaling genes encoding the JH receptor, Methoprene-tolerant (Met), its binding partner Taiman (Tai), and a JH-inducible protein, Krüppel-homolog 1 (Kr-h1). RNA interference (RNAi) with Met or Tai, but not Kr-h1, blocked ovarian development and suppressed vitellogenin gene expression in the fat body of females raised under reproduction-inducing conditions. Loss of Met and Tai matched the effects of CA ablation or the natural absence of JH during reproductive diapause. Stimulation of vitellogenesis by treatment of diapausing females with a JH mimic methoprene also required both Met and Tai in the fat body, whereas Kr-h1 RNAi had no effect. Therefore, the Met-Tai complex likely functions as a JH receptor during vitellogenesis. In contrast to Met and Kr-h1 that are both required for JH to prevent precocious metamorphosis in P. apterus larvae, removal of Tai disrupted larval ecdysis without causing premature adult development. Our results show that while Met operates during metamorphosis in larvae and reproduction in adult females, its partner Tai is only required for the latter. The diverse functions of JH thus likely rely on a common receptor whose actions are modulated by distinct components. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction The sesquiterpenoid juvenile hormone (JH) controls multiple events in insect’s life, from development to reproduction, seasonal diapause, and various polyphenisms (Nijhout, 1994). How JH exerts all of its functions is unclear as our knowledge of the mode of JH action remains limited. JH was discovered and named for its ca- pacity to maintain the juvenile state of insect larvae until they have attained an appropriate stage (Wigglesworth, 1934). Only during the final larval instar, a temporal drop in JH secretion from the corpora allata (CA) glands permits metamorphosis to the adult form (Hiruma and Kaneko, 2013; Jindra et al., 2013). In adult in- sects, JH reappears to fulfill its other major function during repro- duction, particularly in oogenesis (Raikhel et al., 2005). Since JH occurs even in wingless insects that do not undergo meta- morphosis, stimulating reproduction is thought to be the evolu- tionarily older of the JH roles (Sehnal et al., 1996). The molecular basis of JH signaling has been partially unveiled owing to studies in several insect models [see (Jindra et al., 2013) for a review]. A candidate JH receptor gene, Methoprene-tolerant (Met), was originally uncovered through resistance to the JH mimic methoprene in Drosophila melanogaster mutants (Wilson and Fabian, 1986). Met was identified as a novel member of the basic helix-loop-helix Per-ARNT-Sim (bHLH-PAS) family of transcription factors (Ashok et al., 1998). RNA interference (RNAi)-mediated knockdown of a Met ortholog in the flour beetle, Tribolium casta- neum, revealed that Met was required for JH to prevent precocious metamorphosis (Konopova and Jindra, 2007). The anti- metamorphic JH pathway was soon extended to the zinc-finger * Corresponding authors. Biology Center, Academy of Sciences of the Czech Re- public, 37005 Ceske Budejovice, Czech Republic. E-mail addresses: jindra@entu.cas.cz (M. Jindra), david.dolezel@entu.cas.cz (D. Dolezel). 1 These authors contributed equally to this work. Contents lists available at ScienceDirect Insect Biochemistry and Molecular Biology journal homepage: www.elsevier.com/locate/ibmb 0965-1748/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ibmb.2013.12.003 Insect Biochemistry and Molecular Biology 45 (2014) 69e76