Function of the natalisin receptor in mating of the oriental fruit fly, Bactrocera dorsalis (Hendel) and testing of peptidomimetics

Abstract

Natalisins (NTLs) are conservative neuropeptides, which are only found in arthropods and are documented to regulate reproductive behaviors in insects. In our previous study, we have confirmed that NTLs regulate the reproductive process in an important agricultural pest, Bactrocera dorsalis (Hendel). Hence, in this study, to further confirm the in vivo function of NTL receptor (NTLR) and assess the potential of NTLR as an insecticide target, RNA interference targeting NTLR mRNA was performed. We found that mating frequencies of both males and females were reduced by RNAi-mediated knockdown of the NTLR transcript, while there was no effect on mating duration. Moreover, we functionally expressed the B. dorsalis NTLR in Chinese Hamster Ovary (CHO) cells and was co-transfected with an aequorin reporter to measure ligand activities. A total of 13 biostable multi-Aib analogs were tested for agonistic and antagonistic activities. While most of these NTL analogs did not show strong activity, one analog (NLFQV[Aib]DPFF[Aib]TRamide) had moderate antagonistic activity. Taken together, we provided evidence for the important roles of NTLR in regulating mating frequencies of both male and female in this fly and also provided in vitro data on mimetic analogs that serve as leading structures for the development of agonists and antagonists to disrupt the NTL signaling pathway.

Tachykinins: Neuropeptides That Are Ancient, Diverse, Widespread and Functionally Pleiotropic

“…Roles of TKs in reproductive functions have been demonstrated in vertebrates (Satake et al, 2013; Steinhoff et al, 2014), but not yet in insects or other invertebrates. However, in insects and other arthropods natalisins seem to be important in reproductive behavior, as outlined in the next section (Jiang et al, 2013; Gui et al, 2018).…”

“…Manipulations of NTL neurons had no effect on egg laying, however, in T. castaneum systemic NTL-RNAi in either sex resulted in reduced egg numbers after mating (Jiang et al, 2013). Also in the oriental fruit fly Bactrocera dorsalis NTL and its receptor (NTLR) play important roles in mating (Gui et al, 2017a, 2018). In this species the NTL signaling is required for regulation of mating frequency in both males and females.…”

RNAi in fruit flies (Diptera: Tephritidae): Successes and challenges

“…For example, Gui et al (2017Gui et al ( , 2018 silenced an arthropod-specific neuropeptide related to reproduction behaviour, named natalisin (Ntl), in B. dorsalis, and the RNAi-induced downregulation of both Ntl precursors and receptors reduced mating frequencies.…”

“…Most studies focussed on the improvement of SIT by silencing genes related to sexual determination or fertility presented positive results for the production of intersex individuals (Salvemini et al, 2009;Sarno et al, 2010), alteration of the reproduction apparatus (Chen et al, 2008;Thongsaiklaing et al, 2018) and reduction in mating rates (Gui et al, 2017(Gui et al, , 2018, sperm production and quality (Cruz et al, 2018;Sohail et al, 2019), and number of eggs laid and hatched (Ali et al, 2017;Vannini et al, 2010;Zheng et al, 2015).…”

“…Studies using the RNAi technology to control insect fertility have successfully targeted genes that are important to the development of the germ line and the gametes (Gabrieli et al., 2016), as well as to hormone signalling (Grover et al., 2019; Vannini et al., 2010) and reproduction behaviour (Dong et al., 2017; Gui et al., 2017, 2018). For example, Gui et al.…”