Molecular and Functional Characterization of Pyrokinin-Like Peptides in the Western Tarnished Plant Bug Lygus hesperus (Hemiptera: Miridae)

Abstract

The pyrokinin (PK) family of insect neuropeptides, characterized by C termini consisting of either WFGPRLamide (i.e., PK1) or FXPRLamide (i.e., PK2), are encoded on the capa and pk genes. Although implicated in diverse biological functions, characterization of PKs in hemipteran pests has been largely limited to genomic, transcriptomic, and/or peptidomic datasets. The Lygus hesperus (western tarnished plant bug) PK transcript encodes a prepropeptide predicted to yield three PK2 FXPRLamide-like peptides with C-terminal sequences characterized by FQPRSamide (LyghePKa), FAPRLamide (LyghePKb), and a non-amidated YSPRF. The transcript is expressed throughout L. hesperus development with greatest abundance in adult heads. PRXamide-like immunoreactivity, which recognizes both pk- and capa-derived peptides, is localized to cells in the cerebral ganglia, gnathal ganglia/suboesophageal ganglion, thoracic ganglia, and abdominal ganglia. Immunoreactivity in the abdominal ganglia is largely consistent with capa-derived peptide expression, whereas the atypical fourth pair of immunoreactive cells may reflect pk-based expression. In vitro activation of a PK receptor heterologously expressed in cultured insect cells was only observed in response to LyghePKb, while no effects were observed with LyghePKa. Similarly, in vivo pheromonotropic effects were only observed following LyghePKb injections. Comparison of PK2 prepropeptides from multiple hemipterans suggests mirid-specific diversification of the pk gene.

Identification and characterisation of PRXamide peptides in the western flower thrips, Frankliniella occidentalis

“…The PRLamide antiserum used in this study possibly recognise all the CAPA and PK peptides. Because similar results for capa mRNA expressions and PRXamide-like immunoreactivities have been demonstrated in Rhodnius prolixus (Paluzzi & Orchard, 2006), S. invicta (Choi et al, 2014), H. halys (Ahn & Choi, 2018), L. hesperus (Hull et al, 2021), and L. saccharina (Diesner et al, 2021).…”

“…The first PK peptide was isolated from another cockroach, Leucophaea maderae (Holman et al, 1986). The PK peptides encoded by pyrokinin genes are conserved with a pentapeptide (FXPRLamide) or similar peptides at the C‐terminal end that is diversified with WFGPRLamide (Tryptophan (W) positioned six at the C‐terminal end) in trpPK (= DH‐like, PK1), and with FXPRLamide in PK (= PBAN‐like, PK2) (Ahn et al, 2020; Ahn & Choi, 2018; Choi et al, 2017; Hull et al, 2021; Jurenka, 2015; Redeker et al, 2017). These peptides are involved in a variety of biological functions: hindgut muscle contraction by PK in the cockroach (Holman et al, 1986), sex pheromone biosynthesis by PBAN in many moths (Raina et al, 1989), and cuticle melanization by MRCH in Leucunia separata (Matsumoto et al, 1981), induction of embryonic diapause by DH in Bombyx mori (Imai et al, 1991), termination of pupal diapause by DH in Heliothis virescens (Xu & Denlinger, 2003), and potential seasonal reproductive polyphenism by DH in Orgyia thyellina (Uehara et al, 2011).…”

The Comparative Toxicity, Biochemical and Physiological Impacts of Chlorantraniliprole and Indoxacarb on Mamestra brassicae (Lepidoptera: Noctuidae)

“…A 1 μL aliquot of each sample was injected via an automatic splitless mode into a GC-MS unit (Hewlett Packard GC 6890, HP MSD 5973) equipped with a RESTEC (Rxi-5SI) column (0.25 mm internal diameter × 30 m and 0.25 μm film thickness) using helium (6.00) as a carrier gas at a flow rate of 1 mL/min. The running and heating conditions used were as described in Moustafa et al [ 39 ] and Hull et al [ 45 ]. The Selective Ion Method (SIM) was used for the rapid but sensitive fractionation of the main ( Z 11-hexadecenyl acetate) and minor (hexadecenyl acetate) pheromone components.…”

Insect PRXamides: Evolutionary Divergence, Novelty, and Loss in a Conserved Neuropeptide System

“…The pyrokinins (PKs) are confusingly referred to by several different monikers, including the subesophageal ganglion neuropeptides (α- β- and γ- SGNP) and hugin-γ/hugin ( Sato et al 1993 , Bader, Wegener et al 2007 , Jurenka and Nusawardani 2011 , Fodor et al 2017 ). The capa gene encodes 1–2 periviscerokinins (referred to as CAPA-PVKs) that can be identified by a C-terminal sequence of FPRV/Iamide ( Hull et al 2021 ). Both capa and pk/pban genes also typically encode a tryptopyrokinin (trypto-PK) with a C-terminal sequence of WFGPRLamide; these peptides are designated diapause hormones DH1 and DH2, respectively ( Jurenka 2015 ).…”

“…Together these neurons have a characteristic innervation pattern: descending processes travel along the lateral margin of the entire VNC, producing arbors along the way and ending with a broad arbor in the terminal abdominal ganglion. Ascending neurons arborize in the tritocerebrum and around the esophageal foramen, and travel dorsally through the pars intercerebralis (PI) and branch in an arc across the superior medial protocerebrum ( Tips et al 1993 , Choi et al 2001 , Sun et al 2005 , Bader, Wegener et al 2007 , Predel et al 2007 , Choi et al 2009 , Ahn and Choi 2018 , Hull et al 2021 ).…”