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PubMed1981

Enkephalin-related peptides: direct action on the octopus heart.

Immunocytochemical evidence for the occurrence of "vertebrate" peptides in the neuropil of the vena cava [12, 13] and the structural similarity between enkephalin precursor peptides and the molluscan cardioexcitatory peptide [16], lead us to study the action of enkephalin-related peptides on the octopus heart. Systemic hearts of Octopus vulgaris were perfused with sea wate and test substances and a crude extract of vena cave were added for 1 min; frequency and pressure were monitored continuously. The heptapeptide Leu5-enkephalin-Arg6-Phe7 and the Met5-analogue, both in the amidized form, displayed dose-response relationship with a sensitivity of about 10 nmol. The C-terminal tetrapeptide amides, Phe-Leu/Met-Arg-Phe-NH2, were active at the same doses. Opiate receptors do not seem to be involved in this action on the octopus heart, as naloxone treatment had no effect. Whereas the N-terminal portion of the heptapeptide is known to be crucial for activity as an opioid, the C-terminal NH2 group is essential for cardioexcitatory activity.

Animals↗
PubMed1981

Evidence for visual mapping in the peduncle lobe of octopus.

The first use of horseradish peroxidase in the central nervous system of a cephalopod revealed apparent topographic connections between optic and peduncle lobes in octopus. Optic lobe efferent fibers within the peduncle lobe neuropil and labeled cells in the peduncle lobe exhibited alignment along the anteroposterior and dorsoventral axes of the peduncle lobe. The location and number of labeled peduncle lobe cells depended on the extent of the injection site in the optic lobe.

Afferent Pathways↗
PubMed1984

Synaptic and non-synaptic effects of molluscan cardioexcitatory neuropeptides on locust skeletal muscle.

Neurally evoked contractions of the locust jumping muscle are potentiated by the molluscan cardioexcitatory peptide (FMRFamide) and related peptides. This effect is due to a synaptic and a non-synaptic action of the peptides: (1) excitatory synaptic potentials are increased; (2) excitation-contraction coupling becomes more efficient, as indicated by an increased strength of potassium contractures. Octopus heptapeptide (YGGFMRFamide), which contains the entire enkephalin structure (YGGFM), is 100 times more potent than FMRFamide. Structure-activity studies indicate that the observed actions are not mediated by opioid receptors but are dependent on the C-terminal structure of the peptides.

Animals↗
PubMed1991

Convergent inputs to Octopus oculomotor neurones demonstrated in a brain slice preparation.

A brain slice preparation was developed to permit recordings to be made from neurones in the anterior lateral pedal lobe of the octopus CNS. These are the first intracellular recordings obtained from identified neurones in the cephalopod CNS. The neurones had membrane resting potentials of around -40 mV and action potentials up to 20 mV in amplitude. Spontaneous synaptic potentials could be seen in some cells. All of the oculomotor neurones, identified by stimulation of the anterior oculomotor nerve to evoke an antidromic potential, received an excitatory input from the visual system, shown by electrical stimulation of the optic tract, and some also received an excitatory input from the statocyst, as shown by electrical stimulation of the macula nerve.

Action Potentials↗
PubMed1992

A new peptide of the oxytocin/vasopressin family isolated from nerves of the cephalopod Octopus vulgaris.

An oxytocin/vasopressin-immunoreactive peptide was isolated from nerve terminals of the 'neurosecretory system of the vena cava' in octopus. It was purified by HPLC combined with a RIA for oxytocin. Characterization of the peptide by automated Edman degradation, plasma desorption mass spectroscopy, enzymatic treatment and coelution experiments resulted in the structure: Cys-Tyr-Phe-Arg-Asn-Cys-Pro-Ile-Gly-NH2, a nonapeptide with a molecular weight of 1070 Da and a 1-6 disulfide bond. This cephalopod neuropeptide, here called 'cephalotocin', exhibits 78% sequence homology with the vertebrate neurohypophysial hormone mesotocin and clearly belongs to the oxytocin/vasopressin family of vertebrates, confirming the high conservation of this peptide family.

Amino Acid Sequence↗
PubMed1995

Lesions of the vertical lobe impair visual discrimination learning by observation in Octopus vulgaris.

We investigated whether lesions of the vertical lobe of the supraesophageal nervous mass of Octopus vulgaris impair discrimination learning acquired by observation of conspecific behavior. When tested alone, observer octopuses with about 50% of the vertical lobe removed showed a deficit in their learning by observation performance. The level of learning improved 24 h after the observational phase, when observer Octopus vulgaris showed a visual discriminatory performance significantly in agreement with the observed one. Control animals that had no brain tissue removed, did not show any impairment in the discriminative performance they had acquired vicariously. Removal of the vertical lobe of the octopus 'brain' has been reported to induce learning and memory deficits of visual discrimination in direct learning by conditioning experiments. Our findings support the conclusion that the removal of such brain center impairs short-term recall, but does not impair acquisition nor retention of 'observational' long-term memory.

Animals↗
PubMed1983

The effect of isobutylmethylxanthine on the photoresponse and phosphorylation of phosphatidylinositol in octopus retina.

The effect of isobutylmethylxanthine on the photoresponse and the phosphorylation of phosphatidylinositol was studied. The recovery of photoresponse after a bright flash was greatly altered by the addition of isobutylmethylxanthine. Phosphatidylinositol phosphorylation, assessed by the incorporation of label from [gamma-32P]ATP, was influenced by isobutylmethylxanthine. Incorporation of 32P was decreased into diphosphoinositide and triphosphoinositide, and increased into phosphatidic acid. These changes were interpreted by introducing a parameter, phi, calcium charge of the plasma membrane.

1-Methyl-3-isobutylxanthine↗
PubMed1988

Structural modifications in biosynthetic melanins induced by metal ions.

A number of transition metal ions with a wide distribution in biological systems, e.g., Cu2+, Co2+ and Zn2+, are shown to affect markedly the chemical properties of melanins formed by the tyrosinase-catalysed oxidation of dopa. Acid decarboxylation and permanganate degradation provide evidence that melanins prepared in the presence of metal ions contain a high content of carboxyl groups arising from the incorporation of 5,6-dihydroxyindole-2-carboxylic acid (DICA) into the pigment polymer. Naturally occurring melanins from cephalopod ink and B16 mouse melanoma were found to be much more similar to melanins prepared in the presence of metal ions than to standard melanins prepared in the absence of metal ions. These results suggest that the presence of carboxylated indole units in natural melanins is probably due to the intervention in the biochemical pathway of metal ions which, as recently shown, catalyse the formation of DICA versus 5,6-dihydroxyindole in the rearrangement of dopachrome.

Animals↗
PubMed1982

Partial purification and characterization of an alkaline phosphatase in Helix nemoralis and in Octopus vulgaris.

1. Alkaline phosphatase (AP) present in the liver of Helix nemoralis and of Octopus vulgaris; enzyme was purified by homogenization, ultracentrifugation, n-butanol treatment, acetone fractionation and Sephadex G-200 chromatography. 2. The two enzymes show a similar enzyme-substrate affinity, but differ in several properties (molecular weight, electrophoretic mobility, optimum pH, substrate inhibition); a possible correlation of them with different evolutionary adaptations is suggested. 3. Possible roles of AP in Mollusca are discussed.

Alkaline Phosphatase↗
PubMed1991

A dopamine- and octopamine-sensitive adenylate cyclase in the nervous system of Octopus vulgaris.

1. Adenylate cyclase activity was assayed in the optic lobe of Octopus vulgaris. 2. Both octopamine and dopamine stimulate the octopus adenylate cyclase, apparently by competing with the same receptor site. 3. (+/-)-2-Amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene-HBr (6,7-ADTN) and a number of phenylethanolamine derivatives stimulate the octopus adenylate cyclase activity. 4. The dopamine D-1 antagonists R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl- 2,3,4,5-tetrahydro-1H-3-benzazepine-HCl (SCH-23390) and (+/-)-7-bromo-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H- 3-benzazepine-HCl (SKF-83566) are unable to antagonize the effects of dopamine and octopamine, and similarly ineffective is the agonist (+/-)-1-phenyl-2,3,4,5-tetrahydro-1H-3- benzazepine-7,8-diol-HCl (SKF-38393). 5. No detectable binding of labelled SCH-23390 occurs on membrane preparations from octopus optic lobe.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMedDate not supplied

Further study on the specificity of D-amino acid oxidase and D-aspartate oxidase and time course for complete oxidation of D-amino acids.

1. D-Amino acid oxidase (D-AAO) oxidizes: D-Met, D-Pro, D-Phe, D-Tyr, D-Ile, D-Leu, D-Ala and D-Val. D-Ser, D-Arg, D-His, D-norleucine and D-Trp are oxidized at a low rate. D-Ornithine, cis-4-hydroxy-D-proline, D-Thr, D-Trp-methyl ester, N-acetyl-D-Ala and D-Lys are oxidized at a very low rate. 2. D-Asp, D-Glu and their derivatives, Gly and all the L-amino acids are not oxidized (or are at a rate which is undetectable). 3. Among all D-amino acids, D-Met is the most highly oxidized compound. The Km value is 1.7 mM. 4. D-Aspartate oxidase (D-Aspo) either purified from Octopus vulgaris or from beef kidney oxidizes only D-Asp, D-Glu and their following derivatives: D-Asn, D-Gln, D-Asp-dimethyl-ester and N-methyl-D-Asp. 5. However, D-Pro, D-Leu, D-Ala and D-Met, are also oxidized by this enzyme, but at a very low rate (between 0.2 and 0.6% of D-Asp). 6. All other D-amino acids, glycine and all the L-amino acids are not oxidized. 7. Under experimental conditions, 1 U of D-AAO is able to totally oxidize 0.2 micromol of the following amino acids: D-Met, D-Pro, D-Phe, D-Thy, D-Ile, D-Leu, D-Ala, D-Val, D-Ser and D-Arg. 8. Similarly, 1 U of D-AspO in 1 hr of incubation totally oxidizes 0.1 micromol of D-Asp, D-Glu, D-Asn and D-Gln.

Amino Acid Oxidoreductases↗
PubMed1982

The central afferent and efferent organization of the gravity receptor system of the statocyst of Octopus vulgaris.

In Octopus vulgaris, the projections of the afferent fibers from, and the locations of cell bodies of the efferent fibers of, the nerve innervating and macula (statocyst gravity receptor epithelium) were studied within the CNS using iontophoretic whole nerve injection of either cobalt chloride or Lucifer Yellow CH.13 Afferent fibers from the macula nerve project to subesophageal, periesophageal and supraesophageal areas of the brain. Large numbers of such fibers were found in the subeosophageal lateral pedal and posterior lateral pedal lobes, palliovisceral lobe, and the magnocellular commissure. Afferent fibers were also found in the periesophageal ventral and dorsal magnocellular lobes. Supraesophageal macular nerve afferent projections were seen to the peduncle lobe and the ipsilateral median basal lobe. There is evidence for two different macular nerve afferent projections to the contralateral median basal lobe, via and suprapedal commissure and the macula-to-contralateral-median-basal-lobe tract. Evidence is presented for the location of at least some of the macula's efferent fiber's cell bodies in the lateral and posterior lateral pedal lobes, and magnocellular lobes. The differences between the results obtained here with the two different staining methods are discussed. The results imply that processing of static information occurs in many areas of the Octopus CNS, and is much more complex than previously thought. Some of the possible physiological consequences are considered.

Afferent Pathways↗