Localization of stomatogastric IV neuron cell bodies in lobster brain

Summary The cell bodies of the inferior ventricular nerve (IVN) through-fibers of the lobster stomatogastric nervous system were located using cobalt chloride backfills and intracellular recordings. Following backfills of the IVN, two cell bodies in the supraesophageal ganglion (or brain) were stained with cobalt. These cells, each approximately 30 m in diameter, were located at the base of the IVN, just inside the connective tissue sheath surrounding the brain, and were identifiable on the basis of their close proximity to the IVN.In order to record from the cells, an in vitro preparation was made which included the cell bodies, their axons in the IVN and the stomatogastric nervous system. Intracellular recordings showed that the axons projected to the stomatogastric ganglion and made synaptic connections onto identified neurons. The axon trajectories and synaptic connections correlated with those previously described for the IVN through-fibers using extracellular stimulation and recording techniques.Abbreviations IVN inferior ventricular nerve - SN stomatogastric nerve     

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.     

Structure and development of the larval central complex in a holometabolous insect,the beetle Tenebrio molitor

Summary The neuroarchitecture of the central complex, a prominent neuropil in the midbrain of the holometabolan, Tenebrio molitor, is described throughout larval development. The analysis is based on classical silver impregnations and on fate-mapping of identified neurons using antisera against serotonin and FMRF-amide. In T. molitor, the central body is present in the first larval instar, and is formed by side branches of contralaterally projecting neurons. Glial cells surround eight neuropil compartments in the first larval instar. These subdivisions in the organization of the fan-shaped body are maintained throughout development. Intrinsic interneurons are found from the 5th larval instar onwards. In the last larval stage, the central complex consists of the fan-shaped body, the protocerebral bridge, and the anlage of the ellipsoid body. The cellular architecture of the fan-shaped body of the last larval instar resembles the basic structural characteristics of the adult. Serotonin-immunoreactive neurons and FMRF-amide immunoreactive neurons in the midbrain of the first larval instar show the basic structural features of the respective imaginal cells. The structural organizations of larval and adult midbrain are compared.Abbreviations a Anterior - AGT antenno-glomerular tract - aL -lobus - AL antennal lobe - AP anterior protocerebrum - bL -lobe - BSN bilateral symmetrical - FMRF amide-immunopositive neurons - CA calyx - CL1-CL4 serotonin-immunopositive neurons cluster 1–4 - d dorsal - DAB diaminobenzidine tetrahydrochloride - DC dorsal commissure - DCFB dorsal commissure of the fan-shaped body - DHT dorsal horizontal tract - DLTR dorsal lateral triangle - DMLP dorsal medial lateral protocerebrum - DN serotonin-immunopositive deuterocerebral neuron - EB ellipsoid body - en1, en2 extrinsic neurons connecting two FB-subcompartments - esn extrinsic subcompartmental neuron - l lateral - FB fan-shaped body - FN serotonin-immunopositive fan-shaped neuron - fs1, fs2 fanshaped neurons of type 1 and 2 - GC great commissure - HF horizontal fibres - in intrinsic neuron connecting two FB-subcompartments - isn intrinsic subcompartmental neuron - IT isthmus tract - LF large-field neurons - LFASC lateral fascicle - LMFASC lateral median fascicle - MB median bundles - MLP medial lateral protocerebrum - p posterior - P pedunculus - PB protocerebral bridge - pb-fb protocerebral bridge-fan-shaped body connection - PBS phosphate-buffered saline - PDC posterio-dorsal commissure - PTX phosphate-buffered saline containing Triton X-100 - SU suboesophageal ganglion - SVT small ventral triangles - TN 1,2 tritocerebral serotonin-immunoreactive neuron 1,2 - v ventral - VB ventral body - VBC ventral body commissure - VCBC ventral central body commissure - VCFB ventral commissure of the fan-shaped body     

Anatomy of antenno-cerebral pathways in the brain of the sphinx moth Manduca sexta

Summary In the moth Manduca sexta, the number and morphology of neuronal connections between the antennal lobes and the protocerebrum were examined. Cobalt injections revealed eight morphological types of neurons with somata adjacent to the AL neuropil that project in the inner, middle, and outer antenno-cerebral tracts to the protocerebrum. Neurons innervating the macroglomerular complex and many neurons with fibers in the inner antennocerebral tract have uniglomerular antennal-lobe arborizations. Most neurons in the middle and outer antenno-cerebral tracts, on the other hand, seem to innervate more than one glomerulus. Protocerebral areas receiving direct input from the antennal lobe include the calyces of the mushroom bodies, and circumscribed areas termed olfactory foci in the lateral horn of the protocerebrum and several other regions, especially areas in close proximity to the mushroom bodies. Fibers in the inner antenno-cerebral tract that innervate the male-specific macroglomerular complex have arborizations in the protocerebrum that are distinct from the projections of sexually non-specific neurons. Protocerebral neurons projecting into the antennal lobe are much less numerous than antennal-lobe output cells. Most of these protocerebral fibers enter the antennal lobe in small fiber tracts that are different from those described above. In the protocerebrum, these centrifugal cells arborize in olfactory foci and also in the inferior median protocerebrum and the lateral accessory lobes. The morphological diversity of connections between the antennal lobes and the protocerebrum, described here for the first time on a single-cell level, suggests a much greater physiological complexity of the olfactory system than has been assumed so far.     

The developmental expression of serotonin-immunoreactivity in the brain of the pupal honeybee

The biogenic amine serotonin is a neurotransmitter and modulator in both vertebrates and invertebrates. In the CNS of insects, serotonin is expressed by identifiable subsets of neurons. In this paper, we characterize the onset of expression in the brain and suboesophageal ganglion of the honeybee during pupal development. Several identified serotonin-immunoreactive neurons are present in the three neuromeres of the suboesophageal ganglion the dorsal protocerebrum, and the deutocerebrum at pupal ecdysis. Further immunoreactive neurons are incorporated into the developing pupal brain in two characteristic developmental phases. During the first phase, 5 days after pupal ecdysis, serotonin immunoreactivity is formed in the protocerebral central body, the lamina and lobula, and the deutocerebral antennal lobe. During the second phase, 2 days later, immunoreactivity appears in neurons of the protocerebral noduli of the central complex, the medulla, and the pedunculi and lobes of the mushroom bodies. Three novel serotonin-immunoreactive neurons that innervate the central complex and the mushroom bodies can be individually identified.     

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.     

On structural-functional organization of dragonfly mushroom bodies and some general considerations about purpose of these formations

Anatomy as well as (for the first time) the fine structure have been studied of the mushroom bodies located in protocerebrum of the supraesophageal ganglion of dragonflies—the most ancient flying insects on Earth. Used in the work are larvae of the last age (prior to winging), in which the mushroom body structure has already been completely formed and corresponds to that in imago. The total organization of the dragonfly mushroom bodies has been established to be more primitive than that of other insects studied so far. This involves both the number of interneurons (Kenyon cells) present in the mushroom bodies and the character of anaptic connections formed by these cells. There is confirmed the absence in dragonflies of the mushroom body calyces that in opinion of some authors are obligatory input gates into these structures. Peculiarities of the neuropil structure in the area of the absent calyces are studied in detail. For the first time in insects there are revealed the direct (without additional synaptic switching) pathways forming the afferent input from optic lobes into the mushroom body calyx area. Also detected are the direct pathways going from the mushroom bodies to the abdominal chain (efferent output). A possible functional significance of these findings as well as the general role of mushroom bodied in control of some forms of insect behavior are discussed.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 40, No. 6, 2004, pp. 495–507     

Immunohistological evidence of dopamine cells in the cephalic nervous system of the silkworm Bombyx mori. Coexistence of dopamine and α endorphin-like substance in neurosecretory cells of the suboesophageal ganglion

Summary Evidence of dopamine cells in the brain and the suboesophageal ganglion of the silkworm Bombyx mori was obtained immunohistologically in larvae and pupae. From six to eight and eight (two symmetrical groups of four) immunoreactive cells are present respectively in median and lateral protocerebral areas of the brain. In the suboesophageal ganglion, two cell clusters with dopamine immunoreactivity were observed. There was no clear difference in the nature of the immunohistochemical reaction and the number of cells between diapause- and non-diapause-egg producers, in both brains and suboesophageal ganglia. By examination of adjacent sections, it was possible to show that dopamine-immunoreactive cells in larval suboesophageal ganglia also contain an endorphin-like substance.     

Central complex substructures are required for the maintenance of locomotor activity in Drosophila melanogaster

In Drosophila melanogaster, former studies based on structural brain mutants have suggested that the central complex is a higher control center of locomotor behavior. Continuing this investigation we studied the effect of the central complex on the temporal structure of spontaneous locomotor activity in the time domain of a few hours. In an attempt to dissect the internal circuitry of the central complex we perturbed a putative local neuronal network connecting the four neuropil regions of the central complex, the protocerebral bridge, the fan-shape body, the noduli and the ellipsoid body. Two independent and non-invasive methods were applied: mutations affecting the neuroarchitecture of the protocerebral bridge, and the targeted expression of tetanus toxin in small subsets of central complex neurons using the binary enhancer trap P[GAL4] system. All groups of flies with a disturbed component of this network exhibited a common phenotype: a drastic decrease in locomotor activity. While locomotor activity was still clustered in bouts and these were initiated at the normal rate, their duration was reduced. This finding suggests that the bridge and some of its neural connections to the other neuropil regions of the central complex are required for the maintenance but not the initiation of walking. Accepted: 21 June 1999     

Fine Structural Analysis of the Central Nervous System in the Spider, Achaearanea tepidariorum (Theridiidae: Araneae)

ABSTRACT Central nervous system (CNS) of arachnids is still mysterious and has a rich unexplored field compare to what is known in insects or crustaceans. The CNS of the spider, Achaearanea tepidariorum, consists of a dorsal brain or supraesophageal ganglion and circumesophageal connectives joining it to the subesophageal mass. As the segmentation of the arachnid brain is still under discussion, we classify the brain as a protocerebral and tritocerebral ganglion depending on the evidences which generally accepted. The subesophageal nerve mass underneath the brain is the foremost part of the ventral nerve cord. All of this nerve mass is totally fused together, and forming subesophageal ganglia in this spider. In the brain, the nerve cells are packed in the frontal, dorsal and lateral areas, but are not absent from the posterior and ventral regions. In addition, the nerve cells of the subesophageal and abdominal ganglia are only restricted to the ventral and ventolateral regions. The CNS of the spider, Achaearanea tepidariorum is similar in feature to the Family Araneidae.     

Topographic anatomy of ascending and descending neurons of the supraesophageal,meso- and metathoracic ganglia in paleo- and neopterous insects

Topographic anatomy of ascending (AN) and descending (DN) neurons of the supraesophageal and thoracic ganglia in the nervous system of winged insects (Pterygota), representatives of the infraclasses Palaeoptera (Odonata, Aeschna grandis, dragonfly) and Neoptera (Blattoptera, Periplaneta americana, cockroach), was studied. These insects differ in ecological niches, lifestyles, sets of behavioral complexes, levels of locomotor system development, evolutionary age and systematic position. Cell bodies and processes of ANs and DNs were stained with nickel chloride (NiCl₂), and their topography was studied on total preparations of the supraesophageal and thoracic ganglia. Unlike cockroaches, the dragonfly protocerebrum was found to contain DNs sending their processes to ocelli. Dragonfly DN processes exhibit a specific branching pattern in thoracic ganglia, with collaterals coming off both ipsi- and contralaterally. In cockroaches, collaterals of DN processes come off ipsilaterally. The AN cell bodies in dragonfly meso- and metathoracic ganglia lie both ipsi- and contralaterally relative to the ascending process, whereas in cockroaches most of the AN cell bodies in the same ganglia are located contralaterally. Substantial differences in the distrubution of DNs and ANs in insects with different manners of locomotion appear to reflect different degrees of control the supraesophageal ganglion exerts over the activity of segmental centers. This does not seem to be related to the evolutionary age of insects or their systematic position. Probably, different degrees of control over locomotion depend on the way of food acquisition: catching prey in the air in “paleopterous” dragonflies versus maneuverable walking or running over a solid substrate in “neopterous” cockroaches.     

Isolation of an insect circadian clock

Summary Under constant conditions the compound eyes of the ground beetleAnthia sexguttata exhibit sensitivity changes in a very clear circadian rhythm. Usually the rhythms in both eyes in constant darkness are mutually coupled. After transection of the optic tract between the lobula and the supraesophageal ganglion the circadian rhythms of the two eyes continue without interruption, but coupling between them is abolished. Even if the entire supraesophageal ganglion is removed, leaving the optic ganglia intact, the circadian rhythms in the eyes continue without interruption independently. But the rhythm is abolished if the region of the lobula is damaged.The experiments show thatAnthia has circadian pacemakers in the left and right optic ganglia in or close to the lobula. These pacemakers can function independently from the rest of the brain and control circadian rhythms of physiological events.Supported by the Deutsche Forschungsgemeinschaft, Sonderforschungsbereich 45 Vergleichende Neurobiologie des Verhaltens E1     

Fine structure of the CNS ganglia in the geometric spider Nephila clavata (Araneae: Nephilidae)

As web spiders usually hang with their head downward, geometrical differences in body position could affect the organization of their central nervous system (CNS). Nevertheless, most of our knowledge of spider's CNS is dependent on what has been revealed from wandering spiders. To fill the gap, we describe here the fine structural organization of the ganglionic neurons and nerves in the geometric orb web spider Nephila clavata. Nerve cells in the supraesophageal ganglion in N. clavata are packed in the frontal, dorsal and lateral regions, but the nerve cells of the subesophageal mass are only restricted to the ventral and ventrolateral regions. High resolution transmission electron microscopy (TEM) reveals the fine structural details of the neuroglial cells and the neuronal cells which have a conspicuous Golgi apparatus, rough ER, free ribosomes and well‐developed mitochondria. Comparing fine structural characteristics of the CNS ganglia with those of wandering spiders in most respects, it has been revealed that the geometrical difference may affects to the arrangement of receptors in the central body known as an important association center for web building behavior. In particular, remarkable differences can be detected in the protocerebral area by the extraordinary development of the central body including absence of the globuli and associated mushroom bodies.     

Structural organization of the brain and subesophageal ganglion of male Aedes aegypti (L.) (Diptera : Culicidae)

The brain and subesophageal ganglion of male Aedes aegypti (L.) (Diptera : Culicidae) are described from cryofractures and silver-stained, semithin (0.5 μm) serial sections of whole heads observed in the scanning and light microscopes. The brain and subesophageal ganglion of male A. aegypti are fused. The major structures of the brain include the protocerebral lobes and bridge, the mushroom bodies, central complex of the protocerebrum, the mechanosensory regions and olfactory loves of the deutocerebrum, and the tritocerebrum. Major commissures of the brain are the anterior optic tract, central commissure, posterior dorsal commissure, and subesophageal commissure. The structural associations of brain components with each other and the subesophageal ganglion, as well as the paths of the major nerve tracts in male A. aegypti are described and compared with those in other Diptera.     

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.     

Four new species of Isospora Schneider, 1881 (Apicomplexa: Eimeriidae) from reptiles from the islands of Seychelles

Four new Isospora species (Apicomplexa: Eimeriidae) are described from reptiles collected in Seychelles. Oöcysts of I. gardneri n. sp. from Phelsuma astriata astriata, P. sundbergi sundbergi and P. sundbergi longinsulae are ellipsoid, 28.9 (22–31) × 23.5 (18–24) m with a rough 1.5–2 m thick wall. A micropyle, oöcyst residuum and polar granule are absent. Sporocysts are ellipsoid, 14.9 (12.5–17) × 8.8 (8–9.5) m, with a dome-like Stieda body, globular substieda body and a sporocyst residuum consisting of small granules; and the sporozoites have transversal striations. Oöcysts of I. seychellensis n. sp. from 3/7 Mabuya seychellensis are ellipsoid, 19.8 (17.5–21.5) × 15.3 (14.5–16) m. A micropyle, oöcyst residuum and polar granule are absent. Sporocysts are ovoid to broadly ovoid, 11.2 (10–12) × 7.4 (7–8) m, with Stieda and substieda bodies. A sporocyst residuum is present, consisting of small granules; and the sporozoites have distinct transverse striations. Oöcysts of I. tigris n. sp. from 1/1 Calumma tigris are ellipsoid, 22.5 (19–24) × 18 (16–20) m. A micropyle, oöcyst residuum and polar granule are absent. Sporocysts are ovoid or ellipsoid, 13.6 (12–15) × 7 (6–8) m, with large Stieda body and substieda bodies. A sporocyst residuum is present, consisting of numerous small granules; and the sporozoites are vermiform with distinct transverse striations. Oöcysts of I. ladiguensis n. sp. from Phelsuma sundbergi ladiguensis and P. sundbergi longinsulae are spherical to subspherical, 13.2 (12–13.5) × 12 (9–13) m, without micropyle and oöcyst residuum but with one globular polar granule. Sporocysts ovoid, 9 (8–10) × 5.6 (5–6) m, with dome-like Stieda and subglobular substieda body; and the sporozoites are vermiform with distinct transverse striations.     

Evolution of the central complex in the arthropod brain with respect to the visual system

Modular midline neuropils, termed arcuate body (Chelicerata, Onychophora) or central body (Myriapoda, Crustacea, Insecta), are a prominent feature of the arthropod brain. In insects and crayfish, the central body is connected to a second midline-spanning neuropil, the protocerebral bridge. Both structures are collectively termed central complex. While some investigators have assumed that central and arcuate bodies are homologous, others have questioned this view. Stimulated by recent evidence for a role of the central complex in polarization vision and object recognition, the architectures of midline neuropils and their associations with the visual system were compared across panarthropods. In chelicerates and onychophorans, second-order neuropils subserving the median eyes are associated with the arcuate body. The central complex of decapods and insects, instead, receives indirect input from the lateral (compound) eye visual system, and connections with median eye (ocellar) projections are present. Together with other characters these data are consistent with a common origin of arcuate bodies and central complexes from an ancestral modular midline neuropil but, depending on the choice of characters, the protocerebral bridge or the central body shows closer affinity with the arcuate body. A possible common role of midline neuropils in azimuth-dependent sensory and motor tasks is discussed.