The association of changes in cerebral ganglion dopamine metabolism with ootheca development in Periplaneta americana

• 1.1. Dopamine levels and DOPA-decarboxylase activity were measured in cerebral ganglia and haemolymph of female Periplaneta americana.
• 2.2. Measurements were made at four points in the oothecal cycle of cockroaches known to drop oothecae at regular three day intervals.
• 3.3. Dopamine levels and DOPA-decarboxylase activity in haemocytes and plasma cycle in phase with ootheca formation; their levels in haemolymph are maximal when a half visible, untanned ootheca is present.
• 4.4. In the cerebral ganglia dopamine levels and DOPA-decarboxylase also cycle in phase with ootheca formation suggesting that cerebral ganglion dopamine metabolism is under the same controls as dopamine metabolism associated with oothecal tanning.

     

Evidence for two isoforms of carbonic anhydrase II in the leech (Hirudo medicinalis) central nervous system

• 1.1. We dissected, homogenized and prepared ganglia and connectives from the central nervous system of medicinal leeches for SDS gel electrophoresis. The isolated proteins were transferred to nitrocellulose and incubated with affinity column-purified antibodies.
• 2.2. The immunoblots showed a strong positive reaction of a bovine carbonic anhydrase standard at a molecular weight of 29 kDa, and a distinct double-bond at the same molecular weight in the analyzed material.
• 3.3. We demonstrated with rat antibodies that carbonic anhydrase II is detectable in the leech central nervous system as the main isoenzyme.
• 4.4. The biochemical knowledge of carbonic anhydrase reported here agrees well with the immunocytochemical locations, thus affirming the validity of specific staining.

     

Axonal pathways of giant neurons identified in the right parietal and visceral ganglia in the suboesophageal ganglia of an African giant snail (Achatina fulica Férussac)

• 1.1. The axonal pathways of thirteen giant neurons identified in the right parietal and the visceral ganglia, found in the suboesophageal ganglia of an African giant snail (Achatina fulica Férussac), were investigated by intracellular injections of Lucifer Yellow, with regard to their axonal projections into the following six peripheral nerves: lap n (left anterior palliai nerve), lpp n (left posterior palliai nerve), int n (intestinal nerve), anal n (anal nerve), rpp n (right posterior palliai nerve) and rap n (right anterior palliai nerve).
• 2.2. These projections were confirmed by the recording of the axonal responses from the nerves.
• 3.3. On the dorsal surface of the right parietal ganglion, the following four giant neurons were identified: PON (periodically oscillating neuron), TAN (tonically autoactive neuron), RAPN (right anterior palliai neuron), and d-RPLN (dorsal-right parietal large neuron).
• 4.4. The PON axonal pathways projected into int n; those of TAN into all of the nerves examined; those of RAPN into lap n, lpp n, int n, anal n and rap n.; and those of d-RPLN into pd nn (pedal nerves) through the pedal ganglia, lpp n, anal n, rap n and sometimes lap n.
• 5.5. On the dorsal surface of the visceral ganglion, the following four giant neurons were also identified: VIN (visceral intermittently firing neuron), FAN (frequently autoactive neuron), INN (intestinal nerve neuron) and d-VLN (dorsal-visceral large neuron).
• 6.6. The VIN axonal pathways, which had no branch into the six nerves examined, went to both the right and the left pedal ganglia, sending a branch into the cerebro-pleural connective; those of FAN projected into lap n, anal n and rap n, and sometimes into lpp n and rpp n; those of INN into int n; and those of d-VLN into pd nn, lap n, lpp n, anal n and rap n.
• 7.7. On the ventral surface of the right parietal ganglion, v-RPLN (ventral-right parietal large neuron) was identified. The axonal pathways went to pd nn, lap n, lpp n, anal n and rap n.
• 8.8. On the ventral surface of the visceral ganglion, the four giant neurons, v-VNAN (ventral-visceral noisy autoactive neuron), v-VLN (ventral-visceral large neuron), r-VMN (right-visceral multiple spike neuron) and 1-VMN (left-visceral multiple spike neuron) were identified.
• 9.9. The axonal pathway of v-VNAN projected into rpp n and rap n; those of v-VLN into pd nn, lap n, anal n, rap n and sometimes to lpp n; those of r-VMN into int n and rpp n; and those of 1-VMN also into int n and rpp n.
• 10.10. The present morphologial investigations of the giant neurons confirmed well the identifications of the neurons previously studied. The axon of the neurons examined here, except for VIN, projected into some of the peripheral nerves, while the VIN axon extended into the cerebro-pleural connective.
• 11.11. The five neurons, PON, TAN, v-VNAN, r-VMN and 1-VMN, formed fine axonal arborizations terminating at the neuropile, while the arborizations of the other neurons were not clearly observed.
• 12.12. Although the anatomical structures of the portion examined of the suboesophageal ganglia are asymmetrical, three pairs of symmetrically-situated neurons, d-RPLN and d-VLN, v-RPLN and v-VLN, and r-VMN and 1-VMN, were found, indicating the existence of symmetrical components in the ganglia.

     

Three digestive tract endocrine peptides and the circannual cycle of body weight in Spermophilus lateralis

• 1.1. Thirty-one male golden-mantled ground squirrels were divided into four physiological groups: low wt summer, medium wt summer, high wt summer and hibernation period. A second group of 10 females was divided into two groups: hibernation period at low T_b and hibernation period during a periodic arousal.
• 2.2. Blood serum, pancreas and antral stomach region were collected from each animal.
• 3.3. The serum was analysed by radioimmunoassay for pancreatic polypeptide immunoreactivity, the pancreas for pancreatic polypeptide and somatostatin immunoreactivity and the antral region of the stomach for gastrin immunoreactivity.
• 4.4. Significant between-stage differences (P < 0.05) were found in serum pancreatic polypeptide concentration and in pancreatic somatostatin content.

     

The influence of optic nerve section on blood metabolite levels in Carcinus maenas (Crustacea: Brachyura)

• 1.1. Blood metabolite levels were assayed in Carcinus maenas as an indicator of the functioning of the hyperglycemic hormone, HGH, secreted by the crab's eyestalk neuroendocrine tissue.
• 2.2. Bilateral eyestalk ablation eventually resulted in a hypoglycemic response after 2–3 days.
• 3.3. Bilateral optic nerve section produced a significant, long-term hypoglycemic response suggesting that release of HGH from the eyestalk sinus gland is controlled, via a promotive neural pathway, by the CNS and probably by the cerebral ganglia.
• 4.4. Injection of eyestalk extract into operated crabs consistently produced significant, short-term hyperglycemia.

     

Effect of acute temperature change on lung respiration of the mollusc Lymnaea stagnalis

• 1.Temperature-dependent effects on respiratory behaviour as well as the corresponding temperature-dependent activities of identified neurons within the respiratory network of the pulmonate snail Lymnaea stagnalis were investigated.
• 2.Lymnaea lung ventilation terminated at low temperatures (under 10 °C) while temperature elevation increased ventilation rates. The respiratory central pattern generator (CPG) functioning was relatively quiescent at temperatures under 12.5±0.44 °C.
• 3.Identified CPG neurons (RPeD1, VD4, VD1/RPaD2) and the respiratory network motor neurons (Vi- and RPa-cells) were found to exhibit varied temperature-dependent electrophysiological parameters (action potential frequency and amplitude, resting potential value) between cell types.
• 4.The observed alterations in the electrical activity of the Lymnaea respiratory network neurons underlie the marked changes of respiratory behaviour observed in the intact animal during temperature changes.

     

Adaptation in Helix pomatia neurons

• 1.1. Spike frequency adaptation has been studied on neurons of Helix pomatia subesophageal ganglia and interpreted by means of a behavioural model describing the phenomenon in neurons either silent or autorhythmic at rest.
• 2.2. At low stimulating currents the initial discharge frequency F(0) is linearly related to the current strength G.
• 3.3. In the linearity range F(0)/G each neuron was characterized by means of four model parameters: the proportionality constant between F(0) and G, the decay constant of the frequency, the inhibitory current from a single nerve impulse and the decay time constant of the inhibitory current.
• 4.4. The four parameters varied in different cells with a range of 0.18–4.98 Hz/nA, 1.02–3.85 sec, 0.05–0.95 nA and 1.74–22.33 see, respectively.
• 5.5. Experimental results have been analyzed considering inhibitory current, electrogenie sodium pump and other proposed adaptation parameters.

     

Co-localization of locustamyotropin- and pheromone biosynthesis activating neuropeptide-like immunoreactivity in the central nervous system of five insect species

• 1.1. Myotropin I of Locusta and Pheromone Biosynthesis Activating Neuropeptide (PBAN) of Heliothis share the same carboxyterminal pentapeptide FSPRL-amide.
• 2.2. Immunostaining revealed colocalization in cells and axons in the central nervous system, especially in the suboesophageal ganglion, of Locusta, Periplaneta, Leucophaea, Neobellieria (Sarcophaga) and Mamestra.
• 3.3. Following preabsorption with synthetic FSPRL-amide, the PBAN antiserum continued to immunostain cells in Mamestra and Neobellieria only. The preabsorbed Lom-MT I antibody did not yield any positive reaction.
• 4.4. Our results indicate that the functional epitope FXPRL-amide is widespread among insect orders. Its distribution in the nervous system seems to be rather similar in all investigated species.

     

Presynaptic modulation of sensory afferents in the invertebrate and vertebrate nervous system

• 1.1. Ultrastructural examination of the central terminals of sensory afferent neurons in both invertebrates and vertebrates demonstrates that the synapses that form the substrate for presynaptic inhibition and facilitation are almost universally present.
• 2.2. Presynaptic modulation of afferent input acts in many ways which tailor the inflow of sensory information to the behaviour of the animal, effectively providing a means of turning this on and off, or of combining information of the same or different modalities to refine responsiveness or clarify ambiguity.
• 3.3. Presynaptic modulation may act in several different roles on the same afferent.
• 4.4. A comparison of the mechanisms of presynaptic inhibition in different animals demonstrates the likelihood of a variety of common mechanisms,several of which may act simultaneously on the same terminal.These include changes in the conductance of the afferent membrane to Cl^-, K⁺and Ca²⁺ions, in addition to less well understood mechanisms that directly affect transmitter release.
• 5.5.A single transmitter can produce several effects on a terminal through the same or different receptors.
• 6.6. Ultrastructural studies of afferent terminals reveal that only a proportion of boutons on a given afferent may receive presynaptic input and that this may depend on the region of the nervous system in which these are found or on the identity of the postsynaptic neurons contacted.
• 7.7. The synaptic relationships of afferent terminals can be complex. In invertebrates different types of presynaptic neuron may interact synaptically,as may postsynaptic dendrites in vertebrates.
• 8.8. Axons presynaptic to afferent terminals in vertebrates frequently synapse also with dendrites postsynaptic to the afferents.
• 9.9. In both invertebrates and vertebrates reciprocal interactions between afferents and postsynaptic neurons are seen.
• 10.10. Ultrastructural immunocytochemistry reveals the likely dominance of GABA as an agent of presynaptic inhibition but also demonstrates the possible presence of other transmitters some of whose roles are less completely understood.

     

Two kinds of peripheral afferent neurons in the earthworm reflex arc

• 1.1. Two kinds of neurons were identified in the body-wall longitudinal muscle layer of the earthworm, Amynthas hawayanus, by the simultaneous potential recording and Lucifer Yellow-CH injection method with a single microelectrode.
• 2.2. Both kinds of neurons have their somata, neuntes and longitudinal processes imbedded in the longitudinal muscle layer. Those with two circular processes extending into the third segmental nerve trunk are tentatively named “intra-nerve-trunk” neurons and those with four circular processes extending into four setae shafts are tentatively named “intramural” neurons.
• 3.3. Both kinds of neurons responded to electrical and mechanical stimuli applied in an afferent direction to them.
• 4.4. The “intra-nerve-trunk” neuron decreased its response amplitudes to these stimuli after the third nerve trunk was sectioned in correlation to the response amplitude decrease recorded from the nerve trunk after it was sectioned.
• 5.5. The response amplitude decrease due to denervation implies a nonlinear structure of the earthworm reflex circuits.
• 6.6. The “intramural” neurons are believed to be primary sensory neurons connected to the mechanoreceptors in the setae.

     

Immunochemical and immunohistochemical determination of ubiquitin in molluscan (Mytilus edulis) smooth muscle

• 1.1. Immunochemical and immunohistochemical distribution of ubiquitin in the anterior byssus retractor muscle (ABRM) of Mytilus edulis was investigated.
• 2.2. In immunostaining, specific ubiquitin immunoreactivity was observed in the cross-sectioned ABRM, and was uniformly localized in this section.
• 3.3. The amount of free ubiquitin in the ABRM homogenate was 130 ± 4.6 ng/mg protein by western blot analysis, and ubiquitin conjugates were found at about 25, 29 and 200–230 kDa.
• 4.4. These findings were similar to those obtained in the skeletal muscle of rat.

     

Morphology and electrophysiological characteristics of caudodorsal cells of Lymnaea stagnalis in dissociated cell culture

• 1.1. The neuroendocrine caudodorsal cells (CDCs) of Lymnaea stagnalis are a network of about 100 electrotonically coupled neurones. The CDCs release multiple peptides, including an ovulation hormone, during a period of electrical activity, the CDC-discharge.
• 2.2. In isolated brains, a similar period of electrical activity (the afterdischarge) can be induced in all CDCs by a period of intracellular repetitive suprathreshold stimulation of one CDC.
• 3.3. In order to study the regulation of this electrical behaviour in the absence of electrical interactions and in a controlled environment, experiments were performed on CDCs in dissociated cell culture.
• 4.4. Methods for isolation and cell culture are described. Cell cultures had long-term viability and outgrowth of neurities occurred under serum-free conditions.
• 5.5. CDCs in cell culture maintained their capability of producing afterdischarges upon electrical stimulation. Cells in culture appeared more excitable than cells in the intact isolated brain.
• 6.6. The characteristic responses of CDCs in intact isolated brains to acetylcholine and FMRFamide were preserved in cultured CDCs. Both agents induced a transient hyperpolarization of the membrane, inexcitability and inhibition of an ongoing discharge.
• 7.7. In experiments where isolated CDCs were closely apposed, but physically separate, it was found that an afterdischarge in one CDC could induce a discharge in the other CDC.
• 8.8. These results confirm previous results which showed that an excitatory factor is released from the brain during the afterdischarge (Ter Maat et al., 1988, Brain Res., 43, 77–82), and demonstrate that this excitatory factor is released from the CDCs themselves.

     

Cross-correlation analysis of cerebrobuccal connective activity during Aplysia feeding behaviour

• 1.1. Two “en passant” electrodes were implanted around the cerebrobuecal connective (CBC) of Aplysia and used to record the activity, in the unrestrained animal, under three behavioural conditions; (a) absence of feeding behaviour, (b) appetitive feeding behaviour and (c) consummatory feeding behaviour.
• 2.2. The two simultaneous recordings were subjected to cross-correlation analysis, to subdivide spikes on the basis of their direction and speed of propagation.
• 3.3. There was virtually no CBC activity in the absence of food and feeding behaviour.
• 4.4. During appetitive feeding the metacerebral giant cell (MCC) was active and traffic was heaviest in the cerebral-to-buccal direction.
• 5.5. During consummatory feeding, traffic was also sustained in the buccal-to-cerebral direction; there was a reduction in the activity of the MCC, and a peak in the activity travelling to the cerebral ganglia, in the region of higher conduction velocity, was especially pronounced.
• 6.6. Further analysis showed this peak to have its largest amplitude during the actual ingestion of food and to be the result of the firing of several different units.
• 7.7. CBC traffic in both directions was also activated in one case of “spontaneous” biting.

     

Vitellogenesis in the shrimp,Penaeus vannamei: in vitro studies of the isolated hepatopancreas and ovary

• 1.1. Yolk proteins were isolated from ovaries of the shrimp Penaeus vannamei and used as an antigen for antibody production in rabbits.
• 2.2. Protein synthesis was measured for both the hepatopancreas and the ovary in vitro, and proteins present in both tissues were immunoreactive with the antibodies.
• 3.3. Extracts of shrimp eyestalks inhibited in vitro protein synthesis by both tissues. The inhibitory factor from the eyestalks was heat stable and had a molecular weight of 3300 daltons.

     

Structure and bioelectricity of single neurons of Helix pomatia in the intact nervous tissue during epileptic activity: Simultaneous evaluations by confocal microscopy and intracellular recordings of membrane potential changes

• 1.1. Neuronal shape during epileptic activity was studied with confocal laser scanning microscopy and intracellular recording of identified neuronal individuals in the buccal ganglia of Helixpomatia. Simultaneous observations of single Lucifer Yellow stained fibers and epileptic activity of the same neuron were done.
• 2.2. During epileptic activity, the development of several types of morphological changes were observed: local and extended swellings, constrictions, stretching of neuronal processes and release of intracellular material.
• 3.3. Morphological alterations did not only occur with epileptic activity but could also appear due to extended laser exposure of fluorescent neuronal processes.
• 4.4. Phototoxicity is discussed as a limiting factor for a valid interpretation of the morphological changes observed by confocal microscopy.

     

Subcellular distribution of metals within the kidney of the bivalve Mercenaria mercenaria (L.)

• 1.1. The subcellular distribution of nine transition metals (plus four additional elements) was measured in the kidney tissue of the quahog, Mercenaria mercenaria.
• 2.2. Elemental analyses of the subcellular fractions indicated three main patterns of metal distribution within kidney cells.
• 3.3. Barium, iron, manganese and lead were associated primarily with kidney granules.
• 4.4. Cadmium, copper, potassium and magnesium were found mainly in the cytosolic fraction.
• 5.5. Calcium, phosphorus and zinc were found in all isolated fractions, probably reflecting the important roles that these elements play in bivalve metabolism.
• 6.6. The organelle composition of the isolated subcellular fractions was determined using marker enzyme assays and microscopic techniques.

     

Topography and distribution of motor neurons supplying uropod muscles of a crayfish

• 1.1. The pathway and distribution of motor neurons in the uropod muscles of the crayfish, Procambarus clarkii, was investigated electrophysiologically and histologically.
• 2.2. There were three crossing points of motor neurons between the peripheral motor bundle originating from the second and third roots of the sixth abdominal ganglion.
• 3.3. It seems that there are no anatomical and functional regularity in the innervation pattern of the uropod muscles.

     

Identification of neurons involved in the earthworm Amynthas hawayanus reflex activity

• 1.1. The medial (MGF), lateral (LGF) and motor (RMS-2) giant neurons were confirmed as neural components in the earthworm Amynthas hawayanus polysynaptic reflex circuit by simultaneous potential recording and dye injection.
• 2.2. The reflex was initiated from the mechanoreceptors when evoked by mechanical stimulation but electrical stimulation also evoked an antidromic response in the motoneuron.
• 3.3. The primary reflex response propagates decrementally along both giant axons but directly evoked action potentials conduct in an all-or-none fashion.
• 4.4. The secondary reflex response continues to propagate after the primary response disappears.
• 5.5. A rhythmically discharging neuron of uncertain function was also identified.

     

Haematology of the australian eastern quoll,Dasyurus viverrinus

• 1.1. A variety of haematological parameters were determined in adult Dasyurus viverrinus.
• 2.2. Haemoglobin and red cell counts were high with a very low mean cell volume.
• 3.3. Basophils are absent but the eosinophils contain small numbers of basophilic granules which may indicate a dual role for this cell.
• 4.4. “Ring Form” leucocytes are present.
• 5.5. Three types of red cell picture could be identified, some animals showing large numbers of spherocytes, spicule cells, and inclusion bodies.
• 6.6. These cells resemble those found in some inherited human haemolytic anaemias but there was no evidence of haemolysis in the animals.
• 7.7. An alkali resistant haemoglobin component is present.

     

Relationship between ecg,eeg and sps responses during arousal in the goldfish (Carassius auratus)

• 1.1. Goldfish (Carassius auratus) were fitted with ECG electrodes and intra-cranial stainless steel electrodes to monitor cardiac, EEG and SPS responses, during minimal restraint, to presentation of environmental stimuli (light-on, moving shadow, tap).
• 2.2. All three stimuli evoked a bradycardia and increases in the EEG frequency; correlates of arousal responses in fish.
• 3.3. EEG frequency changes were most evident in the fore- and midbrain regions; in the hindbrain smaller responses nevertheless showed discrimination between stimuli.
• 4.4. EEG amplitude changes were more site- and stimulus-specific than frequency changes.
• 5.5. SPSs occurred on stimulus presentations which were negative in polarity in the midbrain and positive in the forebrain and hindbrain, though the latter were smaller and less consistent.
• 6.6. Principal components analyses and regression analyses were used to examine detailed associations between peripheral and central physiological changes.
• 7.7. It was found that increases in the EEG frequency of fore- and midbrain regions were related to cardiac deceleration on early stimulus presentations.
• 8.8. This was also shown for the negative SPS of the midbrain to the presentation of the tap stimulus.
• 9.9. Positive SPSs of the forebrain were related to the bradycardia on later stimulus presentation i.e. during habituation of the arousal response.
• 10.10. The results indicate that in fish, as in other vertebrates, negative SPSs in the midbrain are associated with arousal and implicate the forebrain in the modulation of arousal by its habituation.