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.     

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.     

Pathways for the transmission of visual information in the protocerebrum of the drone fly Eristalis tenax]

Studies have been made on the structure of neuropiles and visual pathoways in the brain of the fly E. tenax L. (Diptera, Syrphidae). The retina is projected on laminar structures in the visual ganglia only; other protocerebrum neuropiles lack this projection. All the comissures connecting contralateral visual ganglia, consist of several hundreds of fibers, whereas the binocular zone of both eyes includes more than 4,000 ommatidia. Neither the visual ganglia, nor other protocerebrum neuropiles may serve as a substrate for topographic imposition of projections of the corresponding parts in both retines. The mechanism of binocular interaction in insects presumably differs from that in mammals (primates, carnovores).     

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.     

CNS microstructure in the wandering wolf spider Arctosa kwangreungensis (Araneae: Lycosidae)

The supraesophageal ganglion of the wolf spider Arctosa kwangreungensis is made up of a protocerebral and tritocerebral ganglion, whereas the subesophageal ganglionic mass is composed of a single pair of pedipalpal ganglia, four pairs of appendage ganglia, and a fused mass of abdominal neuromeres. In the supraesophageal ganglion, complex neuropile masses are located in the protocerebrum which include optic ganglia, the mushroom bodies, and the central body. Characteristically, the only nerves arising from the protocerebrum are the optic nerves, and the neuropiles of the principal eyes are the most thick and abundant in this wandering spider. The central body which is recognized as an important association center is isolated at the posterior of the protocerebrum and appears as a complex of highly condensed neurons. These cells give off fine parallel bundles of axons arranged in the mushroom bodies. The subesophageal nerve mass can be divided into two main tracts on the basis of direction of the neuropiles. The dorsal tracts are contributed to from the motor or interneurons of each ganglion, whereas the ventral tracts are from incoming sensory axons.     

Proctolin-like immunoreactivity in the central and peripheral nervous systems of the locust, Locusta migratoria

Proctolin-like immunoreactivity (PLI) was widely distributed in the locust, Locusta migratoria, within the central, peripheral and stomatogastric nervous systems, as well as the digestive system and retrocerebral complex. Proctolin-like immunoreactivity was observed in cells and processes of the brain and all ganglia of the ventral nerve cord. Of interest, PLI was found in the lateral neurosecretory cells, which send axons within the paired nervi corporis cardiaci II (NCC II) to the corpus cardiacum (CC). The CC contained extensive processes displaying PLI, which continued on within the paired nervi corporis allata (NCA) to the paired corpora allata (CA) where the axons entered and branched therein. The frontal and hypocerebral ganglia of the stomatogastric nervous system contained PLI within processes, resulting in a brightly staining neuropile. Each region of the gut contained PLI in axons and processes of varying patterns and densities. The paired ingluvial ganglia contained PLI, including an extensively stained neuropile and immunoreactive axons projecting through the nerves to the foregut. The hindgut contained PLI within longitudinal tracts, with lateral projections originating from the 8th abdominal ganglion via the proctodeal nerve. The midgut contained PLI in a regular latticework pattern with many varicosities and blebs. No difference in PLI in cells and processes of the central nervous system (CNS) was found between males and females.     

Localization of cholecystokinin-like immunoreactivity in the central nervous system of Triatoma infestans (Insecta: Heteroptera)

The distribution of cholecystokinin-like immunoreactivity was studied in the central nervous system of the heteropteran insect Triatoma infestans using high-sensitivity immunocytochemistry. In the protocerebrum, CCK-IR somata were observed in the anteromedial, anterolateral and posterior cell-body layers. The neuropils displayed different densities of immunoreactive neurites. Few immunoreactive somata were found in the optic lobe in both the medial and lateral soma rinds, as well as in the proximal optic lobe. Immunoreactive fibers were present in the medulla and lobula neuropils. The sensory deutocerebrum contained a higher number of immunopositive perikarya than the antennal mechanosensory and motor center. The antennal lobe glomeruli displayed a moderate density of immunoreactive fibers. With regard to the subesophageal ganglion, numerous CCK-IR somata were found close to the root of the mandibular nerve; others were present in the soma rind of the remaining neuromeres. CCK-IR perikarya were present in both thoracic ganglia, with the abdominal neuromeres containing the highest number of positive somata. The neuropils of both ganglia showed moderate densities of immunopositive processes. The distribution of CCK-LI in somata and neuropils of central nervous system of T. infestans is widespread suggesting that a CCK-like peptide may act mainly as a neuromodulator in the integration of information from distinct sensory receptors.     

FMRFamide-like material in the earwig, Euborellia annulipes, and its functional significance.

The neurosecretory system of the earwig, Euborellia annulipes, contained material similar to that of FMRFamide, as shown by immunocytochemistry. Within the brain were two pairs of darkly staining perikarya in the medial protocerebrum, and up to four pairs of immunoreactive cells in the lateral protocerebrum. The corpora allata appeared immunoreactive in 10-day females, but not in 2-day-old adults. Additionally, immunoreactive material was detected in midgut endocrine cells of both 2- and 10-day-old females. FMRFamide at 1 to 100 nM did not inhibit juvenile hormone production by earwig corpora allata in vitro. This was true of glands of low activity from 2-day cat food-fed or starved virgin females, 10-day starved females, and those of relatively high activity from 10-day-old, cat food-fed females. In contrast, FMRFamide at 50 and 100 (but not at 1) nM stimulated gut motility in vitro in distended guts from 2-day fed females. Preparations from starved females and those from 10-day fed females (in which feeding behavior is on the decline) did not respond to exogenous FMRFamide with enhanced rates of contraction. Lastly, preparations from females starved for 7 days and subsequently fed for 3 days responded to 10 nM FMRFamide with increases in gut motility.     

Dopamine-like immunoreactivity in the bee brain

Summary The distribution of dopamine-like immunoreactive neurons is described for the brain of the bee, Apis mellifera L., following the application of a pre-embedding technique on Vibratome sections. Immunoreactive somata are grouped into seven clusters, mainly situated in the protocerebrum. Immunoreactive interneurons have been detected in the different neuropilar compartments, except for the optic lobe neuropils. Strong immunoreactivity is found in the upper division of the central body, in parts of the stalk and in the -lobe layers of the mushroom bodies. A dense network of many immunoreactive fibres surrounds the mushroom bodies and the central body. It forms a number of interhemispheric commissures/chiasmata, projecting partly into the contralateral mushroom body and central body. The lateral protocerebral neuropil contains some large wide-field-neurons. The antennal-lobe glomeruli receive fine projections of multiglomerular dopamine-like immunoreactive interneurons.     

A comparative study of leucokinin-immunoreactive neurons in insects

Antisera were raised against leucokinin IV, a member of the leucokinin peptide family. Immunohistochemical localization of leucokinin immunoreactivity in the brain of the cockroach Nauphoeta cinerea revealed neurosecretory cells in the pars intercerebralis and pars lateralis, several bilateral pairs of interneurons in the protocerebrum, and a group of interneurons in the optic lobe. Several immunoreactive interneurons were found in the thoracic ganglia, while the abdominal ganglia contained prominent immunoreactive neurosecretory cells, which projected to the lateral cardiac nerve. The presence of leucokinins in the abdominal nerve cord was confirmed by HPLC combined with ELISA. Leucokinin-immunoreactive neurosecretory cells were also found in the pars intercerebralis of the cricket Acheta domesticus and the mosquito Aedes aegypti, but not in the locust Schistocerca americana or the honey bee Apis mellifera. However, all these species have leucokinin-immunoreactive neurosecretory cells in the abdominal ganglia. The neurohemal organs innervated by abdominal leucokinin-immunoreactive cells were different in each species.     

Leucokinin and diuretic hormone immunoreactivity of neurons in the tobacco hornworm,Manduca sexta,and co-localization of this immunoreactivity in lateral neurosecretory cells of abdominal ganglia

Because leucokinins stimulate diuresis in some insects, we wished to identify the neurosecretory cells in Manduca sexta that might be a source of leucokinin-like neurohormones. Immunostaining was done at various stages of development, using an antiserum to leucokinin IV. Bilateral pairs of neurosecretory cells in abdominal ganglia 3–7 of larvae and adults are immunoreactive; these cells project via the ipsilateral ventral nerves to the neurohemal transverse nerves. The immunoreactivity and size of these lateral cells greatly increases in the pharate adult, and this change appears to be related to a period of intensive diuresis occurring a few days before adult eclosion. Relationships of these neurons to cells that are immunoreactive to a M. sexta diuretic hormone were also investigated. Diuretic hormone and leucokinin immunoreactivity are co-localized in the lateral neurosecretory cells and their neurohemal projections. A median pair of leucokinin-immunoreactive, and a lateral pair of diuretic hormone-immunoreactive neurons in the larval terminal abdominal ganglion project to neurohemal release sites within the cryptonephridium. The immunoreactivity of these cells is lost as the cryptonephridium is eliminated during metamorphosis. This loss appears to be related to the change from the larval to adult pattern of diuresis.     

Immunoreactivity of Glutamic Acid Decarboxylase (GAD) Isoforms in the Central Nervous System of the Barn Spider,Araneus cavaticus

The γ‐aminobutyric acid (GABA) has long been considered as an inhibitory neurotransmitter in the central nervous system (CNS) of both vertebrates and arthropods. Since the glutamic acid decarboxylase (GAD) has a restricted tissue distribution and catalyzes the conversion of L‐glutamate to GABA, immunoreactivity of GAD isoforms can reveal distribution of GABAergic neurons in the CNS. In the CNS of the spider Araneus cavaticus, immunoreactivity of GAD isoforms can be detected in the optic lobes including neurons and neuropiles of the supraesophageal ganglia. Strong GAD‐like immunoreactive cell bodies are concentrated in two bilaterally symmetric cell clusters of the protocerebrum. Some intrinsic cell bodies near the central body also show strong immunoreactivity. However, the intrinsic nerve masses and some of the longitudinal and transverse tracts within the supraesophageal ganglion are only lightly labelled, and the fibers transverse the hemisphere and the central fibrous masses are not labelled. Among the three basic types of cell bodies surrounding the central body, several clusters of the Type‐C cells show strong GAD‐like immunoreactivity, however both of the Type‐A and Type‐B cells are not labelled at all.     

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.     

5-Hydroxytryptamine-like immunoreactivity in the peripheral and central nervous systems of the leech Hirudo medicinalis

Summary Chains of segmental ganglia and various peripheral tissues from the leech (Hirudo medicinalis) were screened as whole-mount preparations for the presence of 5-hydroxytryptamine-like immunoreactivity. The gut was richly supplied with immunoreactive nerve fibres. Plexus of fibres, numerous of which were varicose, were found in the crop, with many immunopositive nerve cell bodies in the posterior region and a few in the anterior region. The intestine contained a few longitudinally oriented nerve fibres, while the rectum contained a dense network of non-varicose and varicose fibres. Fine immunopositive fibres were associated with the lateral blood vessel and reproductive organs. Many immunopositive nerve fibres ran in each of the paired connectives linking the segmental ganglia, and two fine varicose fibres were seen in Faivre's nerve. At least two immunopositive processes left each lateral segmental nerve and branched repeatedly, with many varicosities on the distal branches. The dorso-ventral and longitudinal body wall muscles both contained immunoreactive fibres, the plexus being more dense in the former muscle. The possible roles of the immunoreactive nerve fibres demonstrated in the various tissues of the leech have been discussed in relation to the known peripheral effects of serotoninergic neurone stimulation in the leech and to the actions of exogenously applied 5-hydroxytryptamine in these and other invertebrate tissues.     

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.     

5-HT-like immunoreactivity in the central nervous system of the crayfish,Pacifastacus leniusculus

An immunocytochemical technique with the use of three different antibodies raised against serotonin was applied to localize the immunoreactive neurons in the central nervous system of the crayfish, Pacifastacus leniusculus. Immunoreactive neurons were found in three optic ganglia (medulla externa, interna and terminalis). They appeared in three layers of the medulla externa and interna. The medulla terminalis displayed three prominent groups of immunoreactive perikarya and mainly marginal immunoreactive fibres. Immunoreactive areas of the brain comprised the protocerebral bridge, central body, paracentral lobes and two loci in the anterior portion of the protocerebrum, i.e., the terminal areas for immunoreactive fibres from the optic centres. The olfactory lobes showed a specific immunoreactive pattern. In addition, diffusely and sparsely distributed immunoreactive fibres were found throughout the brain. The immunoreactive neurons are largely localized in the same areas of the central nervous system as the catecholaminergic neurons although some distinct differences occur.     

Serotonin-like immunoreactivity in the central nervous system of two ixodid tick species

Immunocytochemistry was used to describe the distribution of serotonin-like immunoreactive (5HT-IR) neurons and neuronal processes in the central nervous system (CNS), the synganglion, of two ixodid tick species; the winter tick, Dermacentor albipictus and the lone star tick, Amblyomma americanum. 5HT-IR neurons were identified in the synganglion of both tick species. D. albipictus had a significantly higher number of 5HT-IR neurons than A. americanum. The labeling pattern and number of 5HT-IR neurons were significantly different between sexes in D. albipictus, but were not significantly different between sexes in A. americanum. 5HT-IR neurons that were located in the cortex of the synganglion projected processes into the neuropils, invading neuromeres in the supraesophageal ganglion including the protocerebrum, postero-dorsal, antero-dorsal and cheliceral neuromeres. In the subesophageal ganglion, dense 5HT-IR neuronal processes were found in the olfactory lobes, pedal, and opisthosomal neuromeres. Double-labeling with neurobiotin backfilled from the first leg damaged at the Haller’s organ revealed serotoninergic neuronal processes surrounding the glomeruli in the olfactory lobes. The high number of the 5HT-IR neurons and the extensive neuronal processes present in various regions of the synganglion suggest that serotonin plays a significant role in tick physiology. This article reports the results of research only. Mention of a proprietary product does not constitute an endorsement or a recommendation by the USDA for its use. The U.S. Government’s right to retain a non-exclusive, royalty free license in and to any copyright is acknowledged.     

Immunocytochemical localization of a diuretic hormone of the beetle Tenebrio molitor,Tenmo-DH(37), in nervous system and midgut

Although the mealworm Tenebrio molitor inhabits very dry environments, it has at least two diuretic peptides, which increase fluid secretion by the free portions of the Malpighian tubules. Unlike other insect corticotropin-releasing factor (CRF)-related peptides isolated to date, these are non-amidated peptides. The immunocytochemical localization of Tenmo-DH(37) was investigated using antisera raised against this hormone. Immunoreactive neurosecretory cells were found in the brain and abdominal ganglia with immunoreactive processes projecting to the peripheral nervous system. Intense staining of the neurohaemal release site, the corpora cardiaca, was observed. In addition, neurosecretory cells immunoreactive to Tenmo-DH(37) were found in the posterior midgut and a network of immunoreactive nerve processes extended over the surface of the midgut. Tenmo-DH(37) is widely distributed and its staining pattern resembles that found for other, amidated CRF-related diuretic peptides.     

The vasopressin-like immunoreactive (VPLI) neurons of the locust,Locusta migratoria. I. Anatomy

Summary Antiserum to arginine-vasopressin has been used to characterise the pair of vasopressin-like immunoreactive (VPLI) neurons in the locust. These neurons have cell bodies in the suboesophageal ganglion, each with a bifurcating dorsal lateral axon which gives rise to predominantly dorsal neuropilar branching in every ganglion of the ventral nerve cord. There are extensive beaded fibre plexuses in most peripheral nerves of thoracic and abdominal ganglia, but in the brain, the peripheral plexuses are reduced while neuropilar branching is more extensive, although it generally remains superficial. An array of fibres runs centripetally through the laminamedulla chiasma in the optic lobes. Lucifer Yellow or cobalt intracellular staining of single VPLI cells in the adult suboesophageal ganglion shows that all immunoreactive processes emanate from these two neurons, but an additional midline arborisation (that was only partially revealed by immunostaining) was also observed. Intracellularly staining VPLI cells in smaller larval instars, which permits dye to reach the thoracic ganglia, confirms that there is no similar region of poorly-immunoreactive midline arborisation in these ganglia. It has been previously suggested that the immunoreactive superficial fibres and peripheral plexuses in ventral cord ganglia serve a neurohaemal function, releasing the locust vasopressin-like diuretic hormone, F₂. We suggest that the other major region of VPLI arborisation, the poorly immunoreactive midline fibres in the suboesophageal ganglion, could be a region where VPLI cells receive synaptic input. The function of the centripetal array of fibres within the optic lobe is still unclear.Abbreviations AVP arginine vasopressin - DIT dorsal intermediate tract - FLRF Phe-Leu-Arg-Phe - FMRF-amide Phe-Met-Arg-Phe-amide - LDT lateral dorsal tract - LVP lysine vasopressin - MDT median dorsal tract - MVT median ventral tract - SEM scanning electron microscopy - SOG suboesophageal ganglion - VIT ventral intermediate tract - VNC ventral nerve cord - VPLI vasopressin-like immunoreactive