Orcokinin neuropeptides regulate ecdysis in the hemimetabolous insect Rhodnius prolixus

Abstract

To grow and develop insects must undergo ecdysis. During this process, the individual sheds the old cuticle to emerge as the following developmental stage. During ecdysis, different programed behaviors are regulated by neuropeptidergic pathways. In general, components of these pathways are better characterized in crustacean and holometabolous insects than in hemimetabola. In insects, the orkoninin gene produces two different neuropeptide precursors by alternative splicing: orcokinin A and orcokinin B. Although orcokinins are well conserved in insect species, their physiological role remains elusive. Here we describe a new splicing variant of the orcokinin gene in the hemimetabolous triatomine Rhodnius prolixus. We further analyze the expression pattern and the function of the alternatively spliced RhoprOK transcripts by means of immunohistochemistry and RNAi-mediated gene silencing. Our results indicate that orkoninis play an essential role in the peptidergic signaling pathway regulating ecdysis in the hemimetabolous insect Rhodnius prolixus.

Molecular evolutionary trends and feeding ecology diversification in the Hemiptera, anchored by the milkweed bug genome

“…Several orthogroups contain potentially novel genes that show no homology outside the Hemiptera and await direct experimental analysis, for which the Hemiptera are particularly amenable ( e.g. , [49-52, reviewed in 5]). Secondly, there are hemipteran-specific orthogroups of proteins with recognized functional domains and homologs in other insects, but where evolutionary divergence has led to lineage-specific subfamilies.…”

Pedal peptide/orcokinin‐type neuropeptide signaling in a deuterostome: The anatomy and pharmacology of starfish myorelaxant peptide in Asterias rubens

“…The anatomical distribution and pharmacological actions of PP/OK‐type neuropeptides have been characterized in protostomian invertebrates, including mollusks and arthropods (Beck et al, ; De Lange, van Golen, & van Minnen, ; Dircksen et al, ; Hall & Lloyd, ; Jiang et al, ; Lloyd et al, ; Pearson & Lloyd, ; Wulff et al, ). Here we report the first detailed anatomical analysis of PP/OK‐type neuropeptide expression in a deuterostomian invertebrate, the starfish A. rubens .…”

“…The anatomical distribution and pharmacological actions of PP/OKtype neuropeptides have been characterized in protostomian invertebrates, including mollusks and arthropods (Beck et al, 2000;De Lange, van Golen, & van Minnen, 1997;Dircksen et al, 2000;Hall & Lloyd, 1990;Jiang et al, 2015;Lloyd et al, 1996;Pearson & Lloyd, 1989;Wulff et al, 2017). 1950).…”

“…Accordingly, injection of an orcokinin into the accessory medulla of cockroaches causes a phase‐dependent shift in circadian locomotor activity (Hofer & Homberg, ). More recent studies on orcokinin function, employing use of RNA interference‐based gene knockdown methods, indicate that orcokinins are regulators of “awakening” behavior in the beetle Tribolium castaneum (Jiang, Kim, & Park, ) and regulators of ecdysis in the kissing bug Rhodnius prolixus (Wulff et al, ).…”

Functional characterization of a second pedal peptide/orcokinin‐type neuropeptide signaling system in the starfish Asterias rubens

“…Subsequent studies have revealed that OKs also alter the rhythmic motor output of the stomatogastric nervous system in crustaceans (Li et al, 2002;Skiebe, Dreger, Meseke, Evers, & Hucho, 2002). Furthermore, experimental studies on insects have revealed that OKs cause a phase-dependent shift in circadian locomotor activity in cockroaches (Hofer & Homberg, 2006), regulate "awakening" behavior in the beetle Tribolium castaneum (Jiang, Kim, & Park, 2015) and regulate ecdysis in the kissing bug Rhodnius prolixus (Wulff et al, 2017). Thus, PP/OK-type neuropeptides have a variety of actions in mollusks and arthropods but with stimulatory actions appearing to be a common theme.…”