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At least 199 records · Page 11Linked to original sources
PubMed1991

Assembly of Octopus dofleini hemocyanin. A study of the kinetics by sedimentation, light scattering and electron microscopy.

The kinetics of association of Octopus dofleini hemocyanin subunits to form the native decameric molecule have been studied with a combination of sedimentation, light scattering and electron microscopy. The reaction, initiated by addition of magnesium, is relatively slow, requiring hours to reach completion, with monomer and decamer as predominant molecular species throughout. Analysis of the light-scattering data, including stopped-flow studies, reveals an initial lag period in the reaction, followed by a second-order process that is rate limiting. The lag period depends on both protein and magnesium ion concentration. Electron microscope studies reveal intermediates in the process, and support a model of assembly in which nucleation begins at the dimer level. Theoretical models for the process are compared.

Animals↗
PubMedDate not supplied

Octopus vulgaris (Mollusca, Cephalopoda) as a model in behavioral pharmacology: a test of handling effects.

Despite the great interest of Cephalopods in learning studies, behavioral pharmacological experiments using these animals are scanty. The purpose of this study was to find an appropriate method of injection of substances for studying their effects on the behavior of octopuses. We injected into the branchial heart a known volume of seawater to test the effect of cold anaesthesia and of different types of manipulation on the predatory performance of Octopus vulgaris. An injection procedure that is simple, reliable, and does not require anaesthesia is proposed. The article also addresses ethical and manipulation requirements of modern behavioral pharmacology.

Anesthesia↗
PubMed1976

Observations on the olfactory organ of adult and juvenile Octopus joubini.

The olfactory organ has an epithelium containing many sense cells and a large subepithelial mass of receptor cells. The epithelium includes cells with cup-shaped, ciliated endings, and hollow, flask-shaped sense cells with ciliated cavities that open to the surface, through a small pore. Below the epithelium are large hollow cells with ciliated cavities and distal processes that either form patent connections between the ciliated cavity and the surface or have a ciliated ending at the surface. There are many synapses between processes in the olfactory nerve. The possible chemosensory function of the olfactory organ is discussed.

Age Factors↗
PubMed1976

Localization of monoamine nerve fibres by formaldehyde fluorescence histochemistry in the posterior salivary duct and gland of Octopus vulgaris.

A bright yellow-green specific fluorescence is induced by formaldehyde histochemistry for monoamines in the secretory nerve trunks of the Octopus vulgaris posterior salivary duct, and in their ramification in the gland tubules. In contrast, the motor nerve trunks of the duct contain few fluorescent elements. The muscular and connective coat of the duct is provided with fluorescent globular and varicose structures, of various sizes and colours, which become numerous in the duct branches. At least some of these peripheral structures belong to varicose monoamine nerve fibres. In the gland, on the contrary, the muscle cells surrounding the tubules are not supplied with fluorescent nerve fibres.

Animals↗
PubMed1976

An unusual receptor in the octopus.

The epithelium of the rim of the octopus sucker in the site of several different types of primary receptors. One is a non-ciliated cell with unusual characteristics. (1) The surface of the cell is extremely irregular with finger-like extension of cytoplasm, especially far reaching in the basal region. (2) The slender neck contains a canal whose apical opening is in contact with the environment. This canal is lined with microvilli and contains granular material in an electron-dense matrix. (3) Patches of presumed glycogen granules occur throughout the cell, being especially abundant in the outer reaches of the cytoplasmic extensions. Their presence, together with numerous mitochondria and free ribosomes, indicate a high intrinsic metabolism. (4) Small fascicles of microtubules are randomly situated throughout the perikaryon. They gather into a coherent system of larger and larger bundles which ultimately enter the axon leading from the cell. This axon extends some distance in the basal region of the epithelium before crossing the subepithelial space to enter the infundibular muscle. Possible functions of this cell are discussed. On the basis of its specific position on the sucker and its intrinsic morphology we suggest that it is a mechanoreceptor involved in shape and/or negative pressure discrimination.

Animals↗
PubMed1979

Octopus microvasculature: permeability to ferritin and carbon.

The permeability of Octopus microvasculature was investigated by intravascular injection of carbon and ferritin. Vessels were tight to carbon while ferritin penetrated the pericyte junction, and was found extravascularly 1-2 min after its introduction. Vesicles occurred rarely in pericytes; fenestrae were absent. The discontinuous endothelial layer did not consitute a permeability barrier. The basement membrane, although retarding the movement of ferritin, was permeable to it; carbon did not penetrate the basement membrane. Evidence indicated that ferritin, and thus similarly sized and smaller water soluble materials, traverse the pericyte junction as a result of bulk fluid flow. Comparisons are made with the convective (or junctional) and slower, diffusive (or vesicular) passage of materials known to occur across the endothelium of continuous capillaries in mammals. Previous macrophysiological determinations concerning the permeability of Octopus vessels are questioned in view of these findings. Possible reasons for some major structural differences in the microcirculatory systems of cephalopods and vertebrates are briefly discussed.

Animals↗
PubMed1984

Occurrence of a tetrodotoxin-like compound in the eggs of the venomous blue-ringed octopus (Hapalochlaena maculosa).

A lethal toxin was isolated and partly purified from the eggs of the blue-ringed octopus, Hapalochlaena maculosa. Examination of the toxin by thin layer chromatography, isoelectric focusing and its effects upon the compound nerve action potentials of the toad sciatic nerve gave results that were indistinguishable from those displayed by authentic tetrodotoxin, the toxin present in the venom glands of the octopus.

Action Potentials↗
PubMed1985

Lack of effect of tetrodotoxin and of an extract from the posterior salivary gland of the blue-ringed octopus following injection into the octopus and following application to its brachial nerve.

Lack of effect of tetrodotoxin and of an extract from the posterior salivary gland of the blue-ringed octopus following injection into the octopus and following application to its brachial nerve. Toxicon 23, 997-999, 1985. Injections of the blue-ringed octopus salivary gland extract and tetrodotoxin into the blue-ringed octopus have no ill-effect on the animals. Similarly, in vitro nerve preparations from the animal were not affected by these materials although they are both extremely potent on bioelectrically excitable preparations from other species.

Animals↗
PubMed1983

Inhibitory retinal efferents from dopaminergic cells in the optic lobe of the octopus.

The effect of dopamine (DA) and its related compounds upon retinal activities of the octopus was compared with that of repetitive stimulation of the optic nerve, while recording ERGs and light-elicited spike discharges. Retinal perfusion with DA or its agonist, apomorphine, markedly enhanced ERGs. The effect appeared at about 10(-8) M and saturated at 10(-6) M. Norepinephrine and L-DOPA had very little effect. Intraretinal injections of DA at different depths revealed that the site of DA action was in the plexiform layer. ERGs were also enhanced by optic nerve stimulation, which inhibited spike discharges. This inhibitory effect was particularly evident when discharges were weak. Consequently the inhibitory effect of optic nerve stimulation was exerted predominantly to the peripheral areas of the receptive field of a nerve bundle, thus resulting in a considerable reduction in the size of the receptive field. These observations suggest that the spatial resolution of this animal may be improved by the efferent activity.

Animals↗
PubMed1984

Primary intermediates of rhodopsin studied by low temperature spectrophotometry and laser photolysis. Bathorhodopsin, hypsorhodopsin and photorhodopsin.

The primary photochemical processes of rhodopsin studied by low temperature spectrophotometry and picosecond laser spectroscopy in our group was summarized. Low temperature spectroscopic experiments demonstrated that the retinylidene chromophores of hypso- and bathorhodopsins are in a twisted all-trans forms. Excitation of rhodopsin with 532 nm laser pulse (width: 25 psec) yielded a new bathochromic photoproduct "photorhodopsin"; its spectrum was located at longer wavelengths than that of bathorhodopsin. Photorhodopsin decays to bathorhodopsin with time constants of about 200 psec in squid and 40 psec in cattle. Squid and octopus hypsorhodopsins were produced within 25 psec by high energy pulse, but not by low energy pulse. Thus hypsorhodopsin is produced by two photon reactions (sequential two photochemical reactions) and decayed to bathorhodopsin with time constant of 125 psec.

Animals↗