Pyrokinin/PBAN-like peptides in the central nervous system of mosquitoes

Abstract

The pyrokinin/pheromone biosynthesis activating neuropeptide (PBAN) family of peptides is characterized by a common C-terminal pentapeptide, FXPRLamide, which is required for diverse physiological functions in various insects. Polyclonal antisera against the C-terminus was utilized to determine the location of cell bodies and axons in the central nervous systems of larval and adult mosquitoes. Immunoreactive material was detected in three groups of neurons in the subesophageal ganglion of larvae and adults. The corpora cardiaca of both larvae and adults contained immunoreactivity indicating potential release into circulation. The adult and larval brains had at least one pair of immunoreactive neurons in the protocerebrum with the adult brain having additional immunoreactive neurons in the dorsal medial part of the protocerebrum. The ventral ganglia of both larvae and adults each contained one pair of neurons that sent their axons to a perisympathetic organ associated with each abdominal ganglion. These results indicate that the mosquito nervous system contains pyrokinin/PBAN-like peptides and that these peptides could be released into the hemolymph. The peptides in insects and mosquitoes are produced by two genes, capa and pk/pban. Utilizing PCR protocols, we demonstrate that products of the capa gene could be produced in the abdominal ventral ganglia and the products of the pk/pban gene could be produced in the subesophageal ganglion. Two receptors for pyrokinin peptides were differentially localized to various tissues. Abstract Pyrokinin/pheromone biosynthesis activating neuropeptide (PBAN) family of peptides is characterized by a common C-terminal pentapeptide, FXPRLamide, that is required for diverse physiological functions in various insects. Polyclonal antisera against the C-terminus was utilized to determine the location of cell bodies and axons in the central nervous systems of larval and adult mosquitoes. Immunoreactive material was detected in three groups of neurons in the subesophageal ganglion of larvae and adults. The corpora cardiaca of both larvae and adults contained immunoreactivity indicating potential release into circulation. The adult and larval brains had at least one pair of immunoreactive neurons in the protocerebrum with the adult brain having additional immunoreactive neurons in the dorsal medial part of the protocerebrum. The ventral ganglia of both larvae and adults each contained one pair of neurons that sent their axons to a perisympathetic organ associated with each abdominal ganglion. These results indicate that the mosquito nervous system contains pyrokinin/PBAN-like peptides and that these peptides could be released into the hemolymph. The peptides in insects and mosquitoes are produced by two genes, capa and pk/pban. Utilizing PCR protocols we demonstrate that products of the capa gene could be produced in the abdominal ventral ganglia and the products of the pk/pban gene could be produced in the subesophageal ganglion. Two receptors for pyrokinin peptides were differ...

Identification and expression of a new member of the pyrokinin/pban gene family in the sand fly Phlebotomus papatasi

“…This cross-reactivity with capa PKs (with shared FXPRL) makes it difficult to determine whether specific immunoreactivity is from the pk/pban or capa gene. To better understand PK/PBAN localization and neuronal activity in insect CNS both immunocytochemistry and reverse transcription methods need to be employed (Hellmich et al, 2014). Mass spectroscopic analysis of PSO and SEG organ peptide products also helps differentiate pk/pban or capa gene expression (Predel et al, 2013).…”

“…In mosquitoes, expressions of the pk/pban gene, as well as the PBAN and DH receptor genes, have been determined for all life stages of the mosquito Aedes aegypti and both receptors were shown to be functional through expression binding assays (Choi et al, 2013). Hellmich et al (2014) localized PK/PBAN-like peptides to specific neuronal groups in the nervous system of larval and adult Ae. aegypti.…”

Distinct or shared actions of peptide family isoforms: I. Peptide-specific actions of pyrokinins in the lobster cardiac neuromuscular system

“…The fact that peptides with this sequence were not physiologically active suggests the possibility that there are two pyrokinins (one with asparagine and one with serine as the variable amino acid) in the H. americanus nervous system, or that the extended sequence differs sufficiently from any of those we tested that the differences in the sequence are compensated for, enabling the native H. americanus peptide and PevPK2 to bind to the same receptor despite differences in sequence. In insects, the existence of multiple isoforms of pyrokinins generally reflects the presence of two different genes that encode pyrokinin peptides: the capa gene, which normally encodes a single pyrokinin (often with a well-conserved FGPRLamide Cterminus) as well as non-pyrokinin peptides (Loi and Tublitz, 2004;Predel and Wegener, 2006), and the hugin (Drosophila, Lepidoptera) or pk/PBAN (other insects) gene, which most often encodes more than one FXPRLamide peptide (Choi et al, 2011;Hellmich et al, 2014;Stepanyan et al, 2006;Towle and Smith, 2006). Although a relatively extensive collection of lobster expressed sequence tags (ESTs) exists (Stepanyan et al, 2006;Towle and Smith, 2006), it does not contain any pyrokinin sequences (Christie and Chi, 2015); it will thus be of interest to examine any genomic or transcriptomic information that becomes available for the gene(s) encoding H. americanus pyrokinin to determine its identity, and whether there are genes homologous to one or both of the insect pyrokinin genes.…”

Mosquito Peptide Hormones

“…1. For the central nervous system several hormones are detected in the brain, specific neurosecretory cells, and ganglia of the ventral nerve chord (Brown and Cao, 2001; Brown and Lea, 1988; Brown et al, 2008; Cao and Brown, 2001; Estévez-Lao et al, 2013; Hellmich et al, 2014; Hernández-Martínez et al, 2005; Kaufmann and Brown, 2006; Kaufmann et al, 2009; Krieger et al, 2004; Marquez et al, 2011; Meola and Lea, 1972; Meola et al, 1998; Moffett and Moffett, 2005; Predel et al, 2010; Riehle et al, 2006; Siju et al, 2013; Stracker et al, 2002). The corpus cardiacum (CC) and perivisceral organs iteratively present in abdominal segments are neurohemal organs that store and release several different peptide hormones in mosquitoes (Brown and Cao, 2001; Brown and Lea, 1988; Cao and Brown, 2001; Estévez-Lao et al, 2013; Hernández-Martínez et al, 2005; Honegger et al, 2011; Kaufmann and Brown, 2006; Kaufmann et al, 2009; Marquez et al, 2011; Predel et al, 2010; Riehle et al, 2006; Veenstra and Costes, 1999).…”

“…The Class A GPCRs in mosquitoes and drosophilids that bind peptides encoded by the above genes form one clade in subassemblage 2F while the receptors that bind ETHs form a sister group (Choi et al, 2013; Dai and Adams, 2009; Olsen et al, 2007; Vogel et al, 2013). Peptidomic and immunocytochemistry methods detect PKs in the CNS, periviseral organs, CC, and midgut of adult mosquitoes (Hellmich et al, 2014; Predel et al, 2010). The only functional data in mosquitoes show that PK2a from Ae.…”