Tryptophanyl-tRNA synthetase-like immunoreactivity in the central nervous system and midgut of the migratory locust. Comparisons with gastrin-cholecystokinin-like and octopamine-like immunoreactivity

A tryptophanyl-tRNA synthetase (TrpRS)-immunoreactivity is localized in various neurosecretory cells of all ganglia of the central nervous system of the Orthoptera Locusta migratoria, except in deutocerebrum, and in endocrine cells of the midgut. It has been observed that TrpRS-like material never co-localizes either with CCK-like or octopamine-like material. TrpRS immunoreactive perikarya and processes that ramify extensively throughout the neuropiles have been detected in the protocerebrum, optic lobes, tritocerebrum, suboesophageal, thoracic and abdominal ganglia. In the lateral protocerebrum, a particular TrpRS pathway different from the lateral gastrin cholecystokinin (CCK-8(s] pathway is revealed, certain of these processes terminating in the glandular part of the corpora cardiaca. In the metathoracic ganglion, have been observed numerous immunoreactive cell bodies and processes in the neuropiles. Some of them constitute a major pathway and which are distinct from octopamine (OA) cells but in close vicinity with the latter. In the midgut immunopositive TrpRS-like cells are dispersed among the regenerative and digestive cells of the epithelium; they are different from gastrin-cholecystokinin positive cells. The various TrpRS-like immunoreactivities identified in Locusta indicate that TrpRS-like material may occur in different tissues of organisms other than Vertebrates. These results suggest also that TrpRS-like enzyme could be involved in functions other than aminoacylation, as in Vertebrates.     

Tryptophanyl-tRNA synthetase-like immunoreactivity in the central nervous system and midgut of the migratory locust. Comparisons with gastrin-cholecystokinin-like and octopamine-like immunoreactivity

Summary A tryptophanyl-tRNA synthetase (TrpRS)-immunoreactivity is localized in various neurosecretory cells of all ganglia of the central nervous system of the Orthoptera Locusta migratoria, except in deutocerebrum, and in endocrine cells of the midgut. It has been observed that TrpRS-like material never co-localizes either with CCK-like or octopamine-like material.TrpRS immunoreactive perikarya and processes that ramify extensively throughout the neuropiles have been detected in the protocerebrum, optic lobes, tritocerebrum, suboesophageal, thoracic and abdominal ganglia. In the lateral protocerebrum, a particular TrpRS pathway different from the lateral gastrin cholecystokinin (CCK-8(s)) pathway is revealed, certain of these processes terminating in the glandular part of the corpora cardiaca. In the metathoracic ganglion, have been observed numerous immunoreactive cell bodies and processes in the neuropiles. Some of them constitute a major pathway and which are distinct from octopamine (OA) cells but in close vicinity with the latter. In the midgut immunopositive TrpRS-like cells are dispersed among the regenerative and digestive cells of the epithelium; they are different from gastrin-cholecystokinin positive cells.The various TrpRS-like immunoreactivities identified in Locusta indicate that TrpRS-like material may occur in different tissues of organisms other than Vertebrates. These results suggest also that TrpRS-like enzyme could be involved in functions other than aminoacylation, as in Vertebrates.     

Immunohistochemical localization of gastrin-cholecystokinin-like material in the central nervous system of the migratory locust

Brain, corpora cardiaca (CC)-corpora allata (CA) complex, suboesophageal ganglion, thoracic and abdominal ganglia of adults, larvae and embryos of Locusta migratoria have been immunohistochemically screened for gastrin cholecystokinin (CCK-8(s]-like material. In adult, numerous immunoreactive neurons and nerve fibres are located, with a marked symmetry, in various parts of the brain and throughout the ventral nerve cord. In the median part of the brain, cell bodies belonging neither to cellular type A1 nor A2 (following Victoria blue-paraldehyde fuchsin staining) are immunopositive; their processes terminate in the upper protocerebral neuropile. In lateral parts of the brain, external cell bodies send axons into CC and some up to CA, other internal have processes which terminate in the neuropile of the brain. Two of these latter cells react also with methionine-enkephalin antiserum. In the ventral nerve cord, in addition to numerous perikarya, immunoreactive arborizations terminate in the neuropile or in close association with the sheath, at the dorsal part of all ganglia. This CCK-8(s) distribution pattern is observed only at the two last larval instars, but is precociously detected in the abdominal nerve cord of embryos, one day before hatching.     

Immunohistochemical localization of gastrin-cholecystokinin-like material in the central nervous system of the migratory locust

Summary Brain, corpora cardiaca (CC)-corpora allata (CA) complex, suboesophageal ganglion, thoracic and abdominal ganglia of adults, larvae and embryos of Locusta migratoria have been immunohistochemically screened for gastrin cholecystokinin (CCK-8(s))-like material. In adult, numerous immunoreactive neurons and nerve fibres are located, with a marked symmetry, in various parts of the brain and throughout the ventral nerve cord. In the median part of the brain, cell bodies belonging neither to cellular type A1 nor A2 (following Victoria blue-paraldehyde fuchsin staining) are immunopositive; their processes terminate in the upper protocerebral neuropile. In lateral parts of the brain, external cell bodies send axons into CC and some up to CA, other internal have processes which terminate in the neuropile of the brain. Two of these latter cells react also with methionine-enkephalin antiserum. In the ventral nerve cord, in addition to numerous perikarya, immunore-active arborizations terminate in the neuropile or in close association with the sheath, at the dorsal part of all ganglia.This CCK-8(s) distribution pattern is observed only at the two last larval instars, but is precociously detected in the abdominal nerve cord of embryos, one day before hatching.     

Studies on the neurosecretory system and retrocerebral endocrine glands of Nezara viridula Linn. (Heteroptera: Pentatomidae)

The neurosecretory system and retrocerebral endocrine glands of Nezara viridula Linn. have been described on the basis of in situ preparations and histological sections employing the paraldehyde fuchsin (PF) and performic acid-victoria blue (PAVB) techniques. In the brain of N. viridula, there are two medial groups–each consisting of five neurosecretory cells which belong to A-type. The lateral neurosecretory cells are absent. The axons of the two groups of medial neurosecretory cells (MNC) compose the two bundles of neurosecretory pathways (NSP) that decussate in the anterodorsal part of the protocerebrum. The two pathways, after the cross-over, run deep into the protocerebrum and deutocerebrum and emerge as NCC-I from the tritocerebrum. The nervi corporis cardiaci-I (NCC-I) of each side which are heavily loaded with NSM terminate in the aorta wall. Thus, the neurosecretory material (NSM), elaborated in the medial neurosecretory cells of the brain, is stored in the aortic wall and nervi corporis cardiaci-I (NCC-I). The NCC-II are very short nerves that originate from the tritocerebrum and terminate in the corpora cardiaca (CC) of their side. Below the aorta, but dorsal to the oesophagus, lie two oval or spherical corpora cardiaca. A corpus allatum (CA) lies posterior to the corpora cardiaca (CC). The corpora cardiaca do not contain NSM; only the intrinsic secretion of their cells has been occasionally observed which stains orange or green with PF staining method. The corpus allatum sometimes exhibits PF positive granules of cerebral origin. A new connection between the corpus allatum and aorta has been recorded. The suboesophageal ganglion contains two neurosecretory cells of A-type which, in structure and staining behaviour, are similar to the medial neurosecretory cells of the brain. The course and termination of axons of suboesophageal ganglion neurosecretory cells, and the storage organ for the secretion of these cells have been reported. It is suggested that the aortic wall and NCC-I axons function as neurohaemal organ for cerebral and suboesophageal secretions.     

Development of blood-cerebrospinal fluid barrier to horseradish peroxidase in the avian choroidal epithelium

Summary Four neurons in the brain of the migratory locust were immunohistologically identified with an anti-met-enkephalin antiserum. The perikarya of two of these cells are located in the center of each of the two groups of lateral protocerebral neurosecretory cells. The fibres coming from these perikarya terminate in numerous immunoreactive ramifications visible at the periphery of both tractus I to the corpora cardiaca, through which pass the neurosecretory products of the pars intercerebralis. The other two cell bodies are located at the bases of the two optic lobes; their fibres enter the posterior part of the protocerebrum and ramify around the root of the nervus corporis cardiaci II, another area through which neurosecretory products pass. The topographic distribution of these met-enkephalin arborizations suggests that these four neurons may act as neuromodulators of the acitivity of the major neurosecretory cells in the brain of this insect.     

Distribution and characterization of Corazonin in the central nervous system of Triatoma infestans (Insecta: Heteroptera)

The distribution of corazonin in the central nervous system of the heteropteran insect Triatoma infestans was studied by immunohistochemistry. The presence of corazonin isoforms was investigated using MALDI-TOF mass spectrometry in samples containing the brain, the subesophageal ganglion, the corpora cardiaca-corpus allatum complex and the anterior part of the aorta. Several groups of immunopositive perikarya were detected in the brain, the subesophageal ganglion and the thoracic ganglia. Regarding the brain, three clusters were observed in the protocerebrum. One of these clusters was formed by somata located near the entrance of the ocellar nerves whose fibers supplied the aorta and the corpora cardiaca. The remaining groups of the protocerebrum were located in the lateral soma cortex and at the boundary of the protocerebrum with the optic lobe. The optic lobe housed immunoreactive somata in the medial soma layer of the lobula and at the level of the first optic chiasma. The neuropils of the deutocerebrum and the tritocerebrum were immunostained, but no immunoreactive perikarya were detected. In the subesophageal ganglion, immunostained somata were found in the soma layers of the mandibular and labial neuromeres, whereas in the mesothoracic ganglionic mass, they were observed in the mesothoracic, metathoracic and abdominal neuromeres. Immunostained neurites were also found in the esophageal wall. The distribution pattern of corazonin like immunoreactivity in the central nervous system of this species suggests that corazonin may act as a neurohormone. Mass spectrometric analysis revealed that [Arg⁷]-corazonin was the only isoform of the neuropeptide present in T. infestans tissue samples.     

Crustacean cardioactive peptide-immunoreactive neurons innervating brain neuropils,retrocerebral complex and stomatogastric nervous system of the locust,Locusta migratoria

The distribution and morphology of crustacean cardioactive peptide-immunoreactive neurons in the brain of the locust Locusta migratoria has been determined. Of more than 500 immunoreactive neurons in total, about 380 are interneurons in the optic lobes. These neurons invade several layers of the medulla and distal parts of the lobula. In addition, a small group of neurons projects into the accessory medulla, the lamina, and to several areas in the median protocerebrum. In the midbrain, 12 groups or individual neurons have been reconstructed. Four groups innervate areas of the superior lateral and ventral lateral protocerebrum and the lateral horn. Two cell groups have bilateral arborizations anterior and posterior to the central body or in the superior median protocerebrum. Ramifications in subunits of the central body and in the lateral and the median accessory lobes arise from four additional cell groups. Two local interneurons innervate the antennal lobe. A tritocerebral cell projects contralaterally into the frontal ganglion and appears to give rise to fibers in the recurrent nerve, and in the hypocerebral and ingluvial ganglia. Varicose fibers in the nervi corporis cardiaci III and the corpora cardiaca, and terminals on pharyngeal dilator muscles arise from two subesophageal neurons. Some of the locust neurons closely resemble immunopositive neurons in a beetle and a moth. Our results suggest that the peptide may be (1) a modulatory substance produced by many brain interneurons, and (2) a neurohormone released from subesophageal neurosecretory cells.     

Gastrin/cholecystokinin-like immunoreactivity in the nervous system of Aeschna cyanea (Insecta,Odonata)

Summary Gastrin/cholecystokinin (gastrin/CCK)-like immunoreactivity has been detected in the brain, suboesophageal ganglion and corpora cardiaca of the larva of Aeschna cyanea by radioimmunoassay and immunohistochemistry, by use of two antisera raised against the sulfated (CCK-8S) and the unsulfated form (CCK-8NS) of the carboxyl terminal octapeptide. Numerous immunoreactive neurons were demonstrated in the protocerebrum (exclusive of optic lobes) and suboesophageal ganglion where 20 and 15 symmetrical clusters of reactive cells, respectively, were observed. Immunoreactive cells also occurred in the tritocerebrum, the optic lobes and the frontal ganglion. In the corpora cardiaca, gastrin/CCK-like material was found both within intrinsic cells and axon terminals. RIA measurements support the immunohistochemical results in so far as large amounts of gastrin/CCK-like material were detected in the brain, corpora cardiaca and suboesophageal ganglion complex. Both boiling water-acetic acid- and methanol-extraction procedures were performed. Comparisons of the results lead to the conclusion that a large part of the gastrin/CCK-like material occurs as small molecules. Immunohistochemical procedures performed on material fixed in a solution of picric acid-paraformaldehyde demonstrated differences in the immunoreactivity of the tested antisera. First, the immunohistochemical reaction was always more pronounced when the CCK-8NS antiserum was used instead of the CCK-8S antiserum, which may be interpreted by a lower affinity of the latter. In the second place, some neurons strongly stained by the CCK-8NS antiserum were only very faintly if at all stained by the CCK-8S antiserum, which may mean that different peptides or at least distinct forms of the same precursor are detected.     

An active principle from the corpora cardiaca,corpora allata and suboesophageal ganglion of the locust,inducing egg diapause in Bombyx mori

The activity of the substance(s) which are contained in the cephalic endocrine organs of the locust which induce egg diapause in Bombyx mori was examined by implantation and injection of saline extracts of these organs. Extracts from the median and lateral neurosecretory parts of the locust brain were not effective in inducing egg diapause. Extracts of the corpora cardiaca, corpora allata, and suboesophageal ganglion of the locust induced diapause eggs in Bombyx pharate adults from which the suboesophageal ganglion had been removed. The first two extracts could induce egg diapause even in isolated abdomens of pharate adults of Bombyx. In the locust corpora cardiaca, the activity was present only in the glandular lobe and not in the nervous region. This activity decreased when the nervi corporis cardiaci I and II and of nervi corporis allati I were cut. Allatectomy also brought about a decrease in the activity in the glandular lobe which could not be restored by the injection of juvenile hormone. The activity in the corpora allata was enhanced slightly by the disconnection though not significantly.From these results, it is assumed that the corpora cardiaca, corpora allata and suboesophageal ganglion of the locust contain and active principle(s) capable of inducing egg diapause in Bombyx mori. The nervous connections between the brain, corpora cardiaca, and corpora allata are essential for the accumulation of the active substance(s) in the glandular lobes of the corpora cardiaca.     

Neurosecretory system of the earwig Labedura riparia, and the rôle of the aorta as a neurohaemal organ

The neurosecretory system of Labedura riparia has been described from sections and whole mounts using a variety of techniques. The pars intercerebralis contains two clusters of medial neurosecretory cells (MNC), each cluster consisting of 8 to 10 A-cells and occasional B-cells. The lateral sides of the brain have a few B-cells. The axons of the median neurosecretory cells terminate in the cephalic aorta (AO), whereas the axons of the lateral neurosecretory cells (LNC) terminate in the corpora cardiaca (CC). It appears that the neurosecretory material (NSM) elaborated in the MNC is stored in the cephalic aorta and that elaborated in the LNC is stored in the corpora cardiaca, which are two oval or elongate bodies composed of large chromophobe and small chromophil cells. Posteriorly there is the oval or elongate corpus allatum (CA) attached to the CC by thick nerves. The CA consists of one cell type only. Both CC and CA contain no A-cell neurosecretory material. It has been suggested that the neurosecretory system of L. riparia is composed of two complexes. One is formed by the medial neurosecretory cells for which the aorta functions as a neurohaemal organ, and the other is formed by lateral neurosecretory cells-lateral neurosecretory pathways-nervi corporis cardiaci-II in which the corpora cardiaca function as a neurohaemal organ.     

Gastrin-cholecystokinin-like immunoreactivity in the central nervous system of the milkweed bug,Spilostethus pandurus. Ultrastructural aspects of the reactive A cells of the brain

Summary— All the ganglia belonging to the central nervous system of adults of the milkweed bug Spilostethus pandurus (Hemiptera) were screened immunohistochemically for vertebrate gastrin-cholecystokinin (CCK-8(s))-like peptides. Several large reactive perikarya are present in the median part of the protocerebrum, their processes extending to the dorsal ‘aorta’. These cell bodies are also paraldehyde fuchsin-positive, ie they are A-type cells. In the lateral part of the protocerebrum, in the deutocerebrum and tritocerebrum, and in the suboesophageal, prothoracic and abdominal ganglia, a few immunoreactive cell bodies send axonal processes into their respective neuropiles. The A-type cells reactive to CCK antiserum were identified, at the ultrastructural level, by combining paraldehyde fuschin staining of semithin sections with a post-embedding immunogold technique carried out on adjacent ultrathin sections. The neurosecretory cells contain numerous vesicles of elevated electron density. These data suggest that members of the CCK peptide family are present in the central nervous system of Spilostethus pandurus.     

Evidence for a crustacean hyperglycemic hormone-like molecule in the nervous system of the stick insect,Carausius morosus

Summary Histological sections of the brain, suboesophageal ganglion, and the corpora cardiaca/corpora allata complex were examined for the presence of crustacean hyperglycemic hormone-like immunoreactive material. With the use of an antiserum directed against the hyperglycemic hormone of Carcinus maenas, immunofluorescence was found in the median portion of the pars intercerebralis, and the corpora cardiaca. Extracts of corpora cardiaca were examined by radioimmunoassay for competitive binding to the antiserum; one pair of corpora cardiaca contains at least 7 pg crustacean hyperglycemic hormone-like material.     

Controle neuroendocrine du fonctionnement du corpus allatum chez Rhodnius prolixus

Cauterization of the dorsal portion of the protocerebrum effected immediately after cessation of feeding in adult females blocks vitellogenesis. The growth of the oöcytes can be re-established by the implantation of corpora allata or by the application of juvenile hormone analogue, and it is suggested that the protocerebrum has a corpus allatum stimulating influence. The corpus allatum deprived of all its cerebral nervous connexions by cutting the aorta just behind the corpora cardiaca induces abundant vitellogenesis. Females with denervated corpora allata or pars intercerebralis cauterized 24 hr after a meal show a phase of vitellogenesis more active than that in normal female adults. This suggests the existence of a cerebral inhibitory centre: its activity through a nervous or endocrine path is discussed.     

Distribution of tachykinin-related neuropeptide in the developing central nervous system of the moth Spodoptera litura

Neuropeptides with similarities to vertebrate tachykinins, designated tachykinin-related peptides (TRPs), have been identified in several insect species. In this investigation we have utilized an antiserum raised to one of the locust TRPs, locustatachykinin-I (LomTK-I), to determine the distribution pattern of LomTK-like immunoreactive (LTKLI) neurons in the developing nervous system of the moth Spodoptera litura. A number of LTKLI neurons could be followed from the larval to the adult nervous system: a set of median neurosecretory cells (MNCs) in the brain, a pair of brain descending neurons and a few sets on neurons in the ventral nerve cord. The distribution of LTKLI neurons in the adult brain is very similar to that seen in other insect species with prominent arborizations in the central body, antennal lobes, mushroom body calyces, optic lobe neuropils and other distinct neuropil areas in the protocerebrum and tritocerebrum. A new finding is the presence of LTKLI neurosecretory cells with axon terminals in the anterior aorta and corpora cardiaca, suggesting for the first time a neurohormonal role of tachykinin-related peptide(s) in insects. During postembryonic development the number of LTKLI neurons in the ventral nerve cord decreases somewhat, whereas the number increases in the brain. Thus the functional roles of TRPs may change to some extent during development.     

The release of a pheromonotropic neuropeptide, PBAN, in the turnip moth Agrotis segetum, exhibits a circadian rhythm

In the female turnip moth, Agrotis segetum, a pheromone biosynthesis activating neuropeptide (PBAN) stimulates sex pheromone biosynthesis which exhibits a daily rhythm. Here we show data supporting a circadian rhythm in PBAN release from the corpora cardiaca, which we propose regulates the endogenous rhythm in sex pheromone biosynthesis. This conclusion is drawn as the observed daily rhythm in PBAN-like immunoreactivity in the hemolymph is persistent in constant darkness and is phase-shifted by an advanced light:dark cycle. PBAN-like immunoreactivity was found in the brain, the optic lobe, the suboesophageal ganglion and in the retrocerebral complex. In each hemisphere ca. 10 immunopositive neurons were observed in the pars intercerebralis and a pair of stained somata in the dorso-lateral protocerebrum. A cluster of cells containing PBAN-like immunoreactive material was found in the tritocerebrum and three clusters of such cells were found in the SOG. Their processes reach the corpora cardiaca via nervi corporis cardiaci and the dorsal surface of the corpora allata via the nervi corporis allati.     

Distribution of locustamyotropin-like immunoreactivity in the nervous system of Locusta migratoria.

Locustamyotropin-like immunoreactivity was visualized in the nervous system of Locusta migratoria by means of the peroxidase antiperoxidase method. Highly specific antibodies to the carboxy-terminus of the locustamyotropins were obtained by elution through an affinity column to which Lom-MT II was covalently bound. Specific cells in the nervous system of Locusta migratoria contain substances immunoreactive to anti-locustamyotropin. In total, about 100 cells immunoreactive to the Lom-MT-II antiserum were detected in the head ganglia, in the abdominal neuromeres of the metathoracic ganglion, and in the five free abdominal ganglia. In the brain, immunoreactive cell groups were situated in the inner and outer edge of the tritocerebrum. Prominent axon bundles tightly surround the tractus I to the corpora cardiaca. The corpora allata were innervated by the nervus corporis allati I coming from the corpora cardiaca and by fibers in the nervus corporis allati II originating from cell bodies in the suboesophageal ganglion. Immunoreactive cell bodies in the suboesophageal and abdominal ganglia are distributed along the anterior posterior midline axis, both dorsally and ventrally. The processes of the cell bodies in the abdominal ganglia leave the ganglia and were traced in the respective median nerves into the neurohaemal organs. Since the Lom-MT-II antiserum cross-reacts with all peptides of the locustamyotropin family that have a carboxy-terminus in common, these cells may contain one or several locustamyotropins. The Lom-MT antiserum also recognizes pheromone biosynthesis activating neurohormone, as was revealed by the intensive labeling of suboesophageal cell bodies in Bombyx mori.     

A comparative ultrastructural and physiological study on melanophores of wild-type and periodic albino mutants of Xenopus laevis

Summary The central and visceral nervous systems of the cockroach Periplaneta americana were studied by means of the peroxidase-antiperoxidase immunocytochemical method, with the use of antibody to bovine pancreatic polypeptide (PP). PP-like immunoreactive neuron somata are most numerous in the brain; at least 6 pairs of cell groups occur in clearly defined regions. Three pairs of cells each are also present in the suboesophageal ganglion and the thoracic ganglia, one pair of a single cell each in the first abdominal and the frontal ganglia, and 4 to 6 pairs of single cells in the terminal ganglion. No reactive cells were found in the retrocerebral complex and the second to the fifth abdominal ganglia. The axons containing PP-like immunoreactivity issue many branches that are distributed in the entire brain-retrocerebral complex, ventral cord, and visceral nervous system. PP-like immunoreactive material produced in the brain seems to be transported by three routes: protocerebrum to corpora cardiaca (-allata) through the nervi corporis cardiaci, tritocerebrum to visceral nervous system through frontal commissures, and to ventral cord through circumoesophageal connectives.A possible homology between the mammalian brain-GEP (gastro-enteropancreatic) system and the brain-midgut system of this insect is discussed.     

Localization of allatostatin-immunoreactive material in the central nervous system,stomatogastric nervous system,and gut of the cockroach Blattella germanica

Immunoreactivity against peptides of the allatostatin family having a typical YXFGL-NH₂ C-terminus has been localized in different areas of the central nervous system, stomatogastric nervous system and gut of the cockroach Blattella germanica. In the protocerebrum, the most characteristic immunoreactive perikarya are situated in the lateral and median neurosecretory cell groups. Immunoreactive median neurosecretory cells send their axons around the circumesophageal connectives to form arborizations in the anterior neuropil of the tritocerebrum. A group of cells in the lateral aspect of the tritocerebrum project to the antennal lobes in the deutocerebrum, where immunoreactive arborizations can be seen in the periphery of individual glomeruli. Nerve terminals were shown in the corpora allata. These terminals come from perikarya situated in the lateral neurosecretory cells in the pars lateralis and in the subesophageal ganglion. Immunoreactive axons from median neurosecretory cells and from cells positioned in the anteriormost part of the tritocerebrum enter together in the stomatogastric nervous system and innervate foregut and midgut, especially the crop and the valve between the crop and the midgut. The hindgut is innervated by neurons whose perikarya are located in the last abdominal ganglion. Besides immunoreactivity in neurons, allatostatin-immunoreactive material is present in endocrine cells distributed within the whole midgut epithelium. Possible functions for these peptides according to their localization are discussed. Arch. Insect Biochem. Physiol. 37:269–282, 1998. © 1998 Wiley-Liss, Inc.     

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

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.