Monoclonal antibodies neutralizing the haemolytic activity of box jellyfish (Chironex fleckeri) tentacle extracts

• 1.1. Three monoclonal antibodies have been produced which neutralize in vitro the haemolytic activity present in tentacle extracts of the box jellyfish (Chironex fleckeri).
• 2.2. Two of these monoclonal antibodies bound specifically to a component of relative molecular mass 50,000 in tentacle extract on Western blots.
• 3.3. This binding only occurred when the extracts were electrophoresed under non-reducing conditions.
• 4.4. The third monoclonal antibody did not display binding to Western blots of tentacle extract under any of our experimental conditions.

     

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.

     

In vivo photo-affinity labelling of glutathione receptors mediating the tentacle ball formation,a behavioral response associated with the feeding of Hydra

• 1.1. The tentacle ball formation, a response associated with the feeding of Hydra japonica, with S-(p-azidophenacyl)-glutathione (GSPAP) was reduced upon illumination.
• 2.2. GSPAP did not cause the depression without illumination nor did illumination without GSPAP.
• 3.3. The concentration dependence of the response of the photolabelled animals suggested high and low affinity glutathione receptors. The low affinity receptor may be efficiently tagged with GSPAP upon photolysis.

     

The stimulation of yeast mitochondrial protein synthesis by low molecular weight cytoplasmic factors: Requirement for intact mitochondria and lack of effect by folate derivatives

• 1.1. Protein synthesis by GTP -supplemented yeast mitochondria is stimulated by a fraction of molecular weight less than 2,000 isolated from yeast high-speed supernatant (S-150).
• 2.2. The low molecular weight fraction works independently of the respiratory chain as the stimulation effect is not cyanide-sensitive.
• 3.3. Stimulation of mitochondrial protein synthesis by cytoplasmic factors is dependent upon the method of mitochondrial isolation.
• 4.4. The low molecular weight stimulatory factor(s) are not reduced folate derivatives which supply formyl groups required for initiation of mitochondrial protein synthesis.

     

Properties of the transition from short-term to long-term depression in neurons of Helix pomatia

• 1.1. Synaptic short-term depression could be transferred into long term depression by repetition of series of stimuli.
• 2.2. The transition from short-term depression to long-term depression was blocked by puromycin.
• 3.3. The majority of the transition took place during resting periods between stimulus series.
• 4.4. The initiation of the transition process was 83% completed after 5 min of stimulation.
• 5.5. Short- and long-term depression were quantitatively separated into their two serial sites of origin: afferent axons and synaptic terminals.
• 6.6. Long sequences evoked periods with increased and variable EPSPs not conforming to depression.

     

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.

     

Acetylcholinesterase in the brain of the marine gastropod Murex trunculus L. (Prosobranchia). Isolation and properties

• 1.1. Cholinesterase (ChE) of two types—acetylcholinesterase (AChE, acetylcholine hydrolase, EC 3.1.1.7) and propionylcholinesterase (PrChE, acylcholine hydrolase, EC 3.1.1.8)—was found in the brain of the marine gastropod Murex trunculus L. (Prosobranchia).
• 2.2. PrChE is a soluble enzyme which can be easily extracted by salt solution after freezing-thawing of the untreated brain.
• 3.3. AChE is membrane-bound. It was solubilized by a 0.2% solution of Triton X-100.
• 4.4. Some part of AChE (up to 36%) can spontaneously pass into solution.
• 5.5. The specific activity of AChE in Triton X-100 extracts is 100 ± 10 nmol acetylcholine/mg protein/min.
• 6.6. Enzyme hydrolysis of acetylcholine (ACh), acetylthiocholine (ATCh) and propionylthiocholine (PrTCh) is suppressed by excess of substrate. Michaelis constants (K_m) for their hydrolysis by AChE are 0.33, 0.017 and 0.018 mM, respectively.
• 7.7. Bimolecular rate constants with organophosphorus inhibitors of different structure points to a similarity of the gastropod brain AChE to the typical enzyme of vertebrates in the structure of the active surface.

     

Influence of ions and chemical substances on the response of the frog's tongue to mechanical stimulation

• 1.1. The fungiform papillae responded to the mechanical stimulation of either an air puff or a Frey's hair. but the filiform papillae did not.
• 2.2. The integrated neural response to an air puff was greatest along the margin and at the apex of the dorsum linguae.
• 3.3. More than three quarters of the mechanosensitive fibers responded to CaCl₂ application and one third responded to NaCl application. Mono- and divalent cations had various influences on the response to mechanical stimulation.
• 4.4. Glucose and sucrose dissolved in distilled water depressed the response, but when dissolved in Ringer's solution had no effect. HCl and quinine-HCl depressed the mechanical response.

     

Responses of dorsal tricorn-type sensilla on Ligia exotica

• 1.1. In order to investigate the function of the dorsal tricorn-type sensilla on Ligia exotica, the morphology and distribution of the setae and neural responses to certain stimulus modalities were studied.
• 2.2. These foraminate sensilla are found to occur over the body surface, except for several appendages and the ventral carapace (sternite); the dorsal carapace (tergite) is covered by only this type of sensilla.
• 3.3. The tricorn-type sensilla located on the dorsal carapace responded to mechanical, gustatory and olfactory stimulation.
• 4.4. The function of the tricorn-type sensilla on the dorsal carapace was discussed.

     

Neuroendocrine regulation of cardiac activity in the snail Strophocheilus oblongus

• 1.1. Cardio-accelerator substances are present both in the brain and heart tissue of the snail Strophocheilus.
• 2.2. The excitatory effect of organ extracts is due not only to the presence of ACh and 5-HT but probably to another substance of neuroendocrine nature as well.
• 3.3. Structural modifications of stainable neurosecretory-like material were found in heart tissue submitted to electrical stimulation through its nerve, and the new excitor substance was found in the blood stream.
• 4.4. The unidentified excitor substance is: (a) heat-stable in different pH; (b) soluble in 50% acetone; (c) inactivated by pronase; (d) non-dialysable and (e) does not migrate with paper electrophoresis.

     

Arginase,ornithine decarboxylase and S-adenosylmethionine decarboxylase in chicken brain and retina

• 1.1. Arginase, ornithine decarboxylase and S-adenosylmethionine decarboxylase are active in both retina and brain. Activity is higher in cerebellum than in the cerebral hemispheres and optical lobes.
• 2.2. Arginase and ornithine decarboxylase are very active in the retina of very young chicks, while S-adenosylmethionine decarboxylase is poorly active. By contrast, S-adenosylmethionine decarboxylase is much more active in brain.
• 3.3. The pattern of activity during development is different; only ornithine decarboxylase is very active during embryonal life; S-adenosylmethionine decarboxylase, at all events in brain, is more active in adult life.
• 4.4. Ornithine decarboxylase is inhibited in vitro by α-difluoromethylornithine, but not in vivo. Diaminopropane inhibits brain ornithine decarboxylase, but does not induce an ornithine decarboxylase-antizyme.
• 5.5. Methylglyoxal bis(guanylhydrazone) promotes an increase of S-adenosylmethionine decarboxylase activity in both the brain and the retina in vivo.

     

Amino acid accumulation in kidney cortex of lambs and piglets as affected by insulin

• 1.1. Insulin stimulated intracellular accumulation of α-amino-isobutyric acid (AIB) in kidney cortex slices from young lambs and piglets.
• 2.2. The effect was similar in the absence or presence of glucose.
• 3.3. The induction of the stimulatory effect on renal AIB transport was blocked by cycloheximide. an inhibitor of protein synthesis.
• 4.4. The insulin stimulation of intracellular AIB accumulation is due to an increased influx and not to a reduced efflux of AIB.
• 5.5. Analysis of transport kinetics for AIB showed that insulin increased V_max but did not change K_m.
• 6.6. It is concluded that insulin stimulates uptake of certain neutral amino acids into kidney cortex cells in young animals.
• 7.7. The effect on renal amino acid transport appears to be mediated through increased synthesis of a membrane carrier.

     

Luminescence of isolated photophores and supracaudal gland from myctophum punctatum: Electrical stimulation

• 1.1. Isolated photophores of the living bathypelagic fish Myctophum punctatum respond to train of weak (10–25 V) and short (2–5 msec) electrical stimuli applied at different frequencies (8–100/sec) by a luminus response.
• 2.2. This response is characterized by a short emission latency time, the peak of light develops within about 2 sec after the beginning of the electrical stimulation: afterwards the light decreases to a constant level within about 8 sec.
• 3.3. Stimuli of higher strength (60–75 V) and longer duration (8–16 msec) applied at different rates (1–100/sec) evoke brief flashes.
• 4.4. The isolated supracaudal gland emits flashes in response to electrical stimulation whatever the strength and the duration of stimuli.
• 5.5. The flash of the supracaudal gland differs from the flash of the isolated photophores in three respects: lower threshold, higher magnitude and longer duration.

     

Vasomotor tone in the dogfish shark

• 1.1. The dogfish, Squalus acanthias, appears to possess arterial vasomotor tone, as evidenced by a significant reduction in arterial blood pressure after administration of an alpha adrenergic blocking agent.
• 2.2. Quick-frezing the entire brain in situ did not reduce arterial pressure, which indicates the vasomotor tone is not generated by neurogenic activity in the brain.
• 3.3. Ganglionic or cholinergic neuro-effector blockade (hexamethonium-atropine) resulted in significant reductions of arterial pressure, which suggests that vasomotor tone is at least partially dependent on neurogenic activity originating in autonomic ganglia or nerve networks.
• 4.4. A hypothesis is advanced that vasomotor tone in this species is maintained by circulating catecholamines, the concentration of which is controlled by peripheral neurogenic activity.
• 5.5. Freezing the brain does not affect the pressor response to angiotensin, thus, the release of catecholamines, which is mediated by angiotensin in the dogfish, is not dependent upon a brain link.

     

An octopamine-sensitive adenylate cyclase in the central nervous system of Limulus polyphemus

• 1.1. Adenylate cyclase (E.C. 4.6.1.1) was assayed and shown to be present in the protocerebrum and circumesophageal ring of Limulus polyphemus.
• 2.2. The enzyme activity from both tissues is stimulated by fluoride and guanylnucleotides.
• 3.3. The circumesophageal ring, but not the protocerebrum, is responsive to octopamine.
• 4.4. Octopamine stimulation of the adenylate cyclase is reversed by phentolamine and dopamine.

     

Identification and estimation of dopamine released from the anterior byssus retractor muscle of Mytilus californianus in response to nerve stimulation

• 1.1. Small quantities of sea water were recyclically perfused over the surface of paired anterior byssus retractor muscles of Mytilus californianus.
• 2.2. Dopamine was identified in the perfusate by thin-layer chromatography.
• 3.3. Stimulation of the pedal ganglion caused the dopamine content of the perfusate to increase.
• 4.4. A significant increment of release of dopamine was detected at stimulation frequencies above 3 Hz and increased progressively with increase in stimulation frequency.
• 5.5. The possibility of a role for dopamine as a relaxing or inhibitory neurotransmitter in Mytilus is considered in relation to the present and related evidence and to the actions of 5-HT, the probable relaxing transmitter.

     

Main kinetic characteristics of acetylcholinesterase from brain of Hypostomus punctatus,a Brazilian bentonic fish (cascudo)

• 1.1. A potentiometric method for the assay of cholinesterase has been proposed and compared with a colorimetric assay.
• 2.2. Main kinetic parameters of cholinesterase from Hypostomus punctatus brain were determined indicating that true acetylcholinesterase is by far the predominant enzyme in the brain of this fish.
• 3.3. We have compared our data with published results described from other fish species.
• 4.4. The enzyme inhibition achieved after 3 hr incubation of brain homogenates with ethyl-parathion have indicated that this enzyme shows a characteristic organophosphorous sensitive behavior.

     

A study of excitatory efferent fibres in the intestinal nerve of the fowl (Gallus domesticus)

• 1.1. The intestinal nerve of the fowl was studied in vitro.
• 2.2. A significantly larger amplitude spike discharge was recorded in side branches of the nerve which innervate the gut when the aboral end of the main nerve trunk was stimulated than when the oral end was stimulated.
• 3.3. Postganglionic autonomic neurones innervating the smooth muscle of the ileum are not located in the intestinal nerve. Evidence is presented, however, supporting the idea that such neurones innervating the rectum are located in the rectal position of the nerve.
• 4.4. The increase in intraluminal pressure and circular muscle tension in the ileum was greater following aboral nerve stimulation than following oral nerve stimulation.
• 5.5. It is suggested that excitatory efferent nerve fibres ascend the intestinal nerve to innervate the ileum.

     

Kinetic studies of catechol-o-methyltransferase from the brain of the African catfish,Clarias gariepinus

• 1.1. Optimum in vitro conditions, and kinetics of the enzyme catechol-O-methyltransferase from the brain of the male African catfish were studied.
• 2.2. A saturated level for S-adenosylmethionine, as methyldonor, and magnesium as cofactor was reached at 5 μM and 10 mM, respectively.
• 3.3. The addition of ascorbic acid, as an antioxidant, and tranylcypromine, as a MAO inhibitor, was not necessary, during incubations with fore-brain homogenates.
• 4.4. Kinetic analysis of the methylation of catecholestrone, catecholestradiol and dopamine showed K_m values of 1.2, 0.6 and 0.5 μM, respectively.
• 5.5. The affinity of the catecholsubstrates for the enzyme catechol-O-methyltransferase is much higher in the brain of the African catfish than in tissues of mammals.

     

Bioelectric activity from isolated brain of Lacerta atlantica

• 1.1. A method of maintaining the isolated lizard brain in a Ringer solution is described.
• 2.2. Microelectrodes and EEG recordings from different areas of telecenphalon and optical tectum were made.
• 3.3. The prolonged cells survival under the experimental conditions described has been demonstrated for several hours.
• 4.4. The isolated brain of Lacerta makes it easy to reach anatomical pathways which otherwise, in the whole animal, would be more difficult to reach.