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At least 217 records · Page 12Linked to original sources
PubMed1985

A photoproduct with 13-cis retinal generated by irradiation with violet light in the octopus retina.

The photoconversion between rhodopsin (R) and metarhodopsin (MR) was investigated in the retina of Octopus ocellatus by measurements of the fast photovoltage (FPV) in conjunction with high pressure liquid chromatography (HPLC). Following conversion of most of R to MR by short-term exposure to an intense violet light, a large vitreous negative FPV due to photon absorption by MR was observed with an orange test flash. By continuing the exposure to the same violet light, however, the negative FPV became very small, though long-term irradiation with blue-green light produced a recovery. With the violet light exposure a substance other than R and MR is produced, which hardly contributes to FPV generation. Analysis of retinal isomers with HPLC show that such an exposure produces a substance with 13-cis retinal as its chromophore and that it was significantly reduced after exposure to blue-green light.

Animals↗
PubMed1988

IRBP-like proteins in the eyes of six cephalopod species--immunochemical relationship to vertebrate interstitial retinol-binding protein (IRBP) and cephalopod retinal-binding protein.

SDS polyacrylamide gel electrophoresis and immunoblotting were used to examine soluble proteins from the eyes of six species of cephalopods i.e. Lolliguncula brevis, Sepia officinalis, Octopus maya, Octopus bimaculoides, Rossia pacifica and Loligo opalescens. All species had a protein ("IRBP") with molecular weight virtually identical with vertebrate interstitial retinol-binding protein (IRBP) averaging 132,400 +/- 700 (n = 6). "IRBP" reacted on nitrocellulose blot transfers with rabbit antibovine IRBP and rabbit antifrog IRBP antibodies. Unlike vertebrate IRBP, cephalopod "IRBP" (from L. brevis) did not bind exogenous retinol or concanavalin A. The N-terminal amino acid appeared to be blocked in samples electroeluted from SDS gels. The antifrog IRBP antibodies also reacted with a series of proteins with molecular weights between 46,000 and 47,000, identified as retinal-binding protein (RALBP) with anti-RALBP antibodies. Anti-IRBP also reacted with pure RALBP prepared from Todarodes pacificus. Occasionally, anti-RALBP antibodies were seen to react weakly with "IRBP" in some cephalopods. We conclude that RALBP, cephalopod "IRBP" and vertebrate IRBP share a common but distant ancestry, and that a protein resembling IRBP appeared before the vertebrates diverged from the invertebrates. Both RALBP and IRBP appear to have analogous functions in shuttling retinoids between rhodopsin and the corresponding isomerizing system, retinochrome in the cephalopods and retinol isomerase in the vertebrates. The function of cephalopod "IRBP" is unknown.

Amino Acids↗
PubMed1989

Distribution of retinol isomerase in vertebrate eyes and its emergence during retinal development.

Ocular tissue homogenates were incubated in darkness with [11,12-3H] all-trans retinol. Formation of radiolabeled 11-cis retinol was used as an index of isomerase activity and was determined by high-performance liquid chromatography. Isomerase was found in the eyes of cattle, human, rat, chicken, turtle, goldfish and frog, representing the mammals, birds, reptiles, bony fishes and amphibians. The enzyme was concentrated in the pigment epithelium (RPE). Variable activity was found in the retina, where the amount of radiolabeled 11-cis retinol formed under standard incubation conditions at protein concentrations of 0.03-1.08 mg/ml was 6.4 +/- 6.0% of that in the RPE-choroid. Using the same methodology, we could not detect isomerase in the retinas of three cephalopods (Octopus, Sepia and Loligo). In rats, isomerase was present at postnatal day 10 but not at postnatal days 0 and 4. Therefore, the expression in the RPE of retinol isomerase, which is essential for the formation of rhodopsin in the developing photoreceptors, is coordinated with the emergence of the rod outer segment in the retina. However, the continued expression of this enzyme in RCS rats does not depend on the presence of photoreceptors, because loss of photoreceptors was not associated with an absence of isomerase activity in RCS rats. Our findings suggest that a reciprocal flow of retinoids between the retina and the site of isomerase action in the RPE is a feature common to the visual cycle in all vertebrates.

Animals↗
PubMed1991

Light-induced, GTP-binding protein mediated membrane currents of Xenopus oocytes injected with rhodopsin of cephalopods.

Xenopus oocytes that were injected with rhabdomeric membranes of squid and octopus photoreceptors acquired light sensitivity. The injected oocytes showed a light-induced current having characteristics similar to other G-protein-mediated Cl- currents induced by the activation of other membrane receptors. Pretreatment of the oocytes with pertussis toxin before the injection suppressed the generation of the light-induced current, indicating an ability of cephalopod rhodopsin to cross-react with an endogenous G-protein of Xenopus oocytes.

Animals↗
PubMed1985

Isolation and characterization of a lectin from the hemolymph of the cephalopod Octopus vulgaris (Lam.) inhibited by alpha-D-lactose and N-acetyl-lactosamine.

The hemolymph of Octopus vulgaris is known to contain a lactose-specific agglutinin. This has been isolated by a two-step affinity-chromatographical procedure using, firstly immobilized asialofetuin followed by its binding to and elution from Con A-Sepharose. The lectin is a glycoprotein with a carbohydrate content of about 8%, and has a molecular weight (M.W.) of 260 kDa. Disulfide bridges connect subunits of molecular weights ranging between 30-32 kDa and of differing isoelectric points (pH 6.4, 6.6, 7.0, 7.3). Ca++-ions are required for ligand binding of the lectin; the pH-optimum for binding reactions is between pH 8.2-8.5 as determined by precipitation experiments with asialofetuin. Heating to 60-80 degrees C reduces agglutinating activity which is completely destroyed at 90 degrees C.

Amino Sugars↗
PubMed1990

Problem solving ability of Octopus vulgaris Lamarck (Mollusca, Cephalopoda).

Experiments presented in this study show that Octopus vulgaris Lamarck is able to open transparent glass jars closed with a plastic plug and containing a live crab (Carcinus mediterraneus). The animals remove the plus (Operandum: O) and seize the crab (Predation :P) in one single attack. The number of unsuccessful attacks appears to decrease over a series of trials (p less than .01); during the same period exploration time remains unchanged. There is a statistically significant increase in performance over trials for O (p less than .01) and P (p less than .05) mean times analyzed by single factor ANOVA, suggesting that the learning process is accomplished either by stimulus-response association or by trial and error. We propose that Octopus vulgaris is capable of learning the solutions of both problems, Operandum and Predation, thus showing a highly developed ability of "integration" of the behavioral program.

Animals↗
PubMed1985

A modified, prefixed, Golgi-rapid technique for the cephalopod retina.

A quick and simple method for Golgi staining of neurons and glia in the cephalopod retina is described. The main difference between this method and other Golgi-rapid protocols is that tissue is placed in sachets constructed from dialysis membrane prior to chromation and impregnation. This greatly reduces the amount of surface deposition of silver chromate and can reduce the number of elements impregnated. Together these effects produce improved Golgi staining of the cephalopod retina. Given some modifications to the osmolarity of the solutions employed, the method should be applicable to other, non-cephalopod tissues where superficial structures are obscured by surface precipitation, or neurons are arranged in thin sheets of tissue. The method employs prefixation of tissue in a fixative suitable for light or electron microscopy.

Animals↗
PubMed1993

Primary structure and lens-specific expression of genes for an intermediate filament protein and a beta-tubulin in cephalopods.

Intermediate filament (IF) protein and tubulin cDNAs of cephalopod eye lenses were cloned and sequenced. The rod regions of the deduced IF proteins of the squid and octopus were more similar (68% identical) than were head (33% identical) and tail (40% identical) regions. The rod sequences were closer to squid neuronal IF protein (39% identical) than to any other known IF protein. There was only 31% identity between the rod regions, 21-30% identity between the head regions and 23-32% identity between the tail regions of the present IF proteins of cephalopods and other invertebrates. The rod regions of the cephalopod IF proteins contained the 6 heptads characteristic of nuclear lamins, consistent with an evolutionary relationship between IF proteins and lamins. The present octopus alpha-tubulin was 93% and beta-tubulin was 87% identical to the corresponding tubulins of insects and vertebrates. SDS-PAGE and peptide sequencing indicated that the order of abundance of the cephalopod lens cytoskeletal proteins was IF proteins, actin and tubulins. Northern blot hybridization revealed a 4 kb mRNA for the octopus IF protein and 2.9 and 7.3 kb mRNAs for the squid IF protein; the alpha-tubulin mRNA was about 1.8 kb in the octopus and squid, and the beta-tubulin mRNA was about 2.8 kb in the octopus. The alpha-tubulin mRNA was present in all tissues examined; by contrast, the present beta-tubulin and IF protein mRNAs appeared specialized for lens expression.

Amino Acid Sequence↗
PubMed1982

Two genetically distinct molecular species of octopus muscle collagen.

The arm muscular tissue of an octopus, Octopus vulgaris, was subjected to limited proteolysis with pepsin and the solubilized tissue collagen was separated into two fractions by selective salt precipitation. Biochemical characterization of the major collagen fraction precipitating at 0.45 M NaCl (pH 2.6) has demonstrated that it comprises almost a single type of molecular species with structure (alpha 1)2 alpha 2, which was identified by its CNBr-peptide pattern as being similar to Type I-like collagen of octopus skin. On the other hand, the minor collagen fraction precipitating at 0.90 M NaCl (pH 2.6) was found to contain a unique gamma-chain-sized component cross-linked by disulfide bonds. Sepharose CL-4B gel filtration of the reduced gamma component revealed the presence of an alpha component, which is virtually identical in amino acid composition to the original gamma protein and bears a close resemblance to known basement membrane collagens. This unique alpha component was genetically distinct from alpha 1 and alpha 2 chains of the major muscle collagen as judged by their CNBr-peptide patterns.

Amino Acids↗
PubMed1984

Distribution of copper atoms and binding of carbon monoxide in partially copper-depleted hemocyanin.

Binding of CO to single cuprous (half-apo) or cupric (met-apo) copper of hemocyanin is investigated by a new method which allows estimation of the total amount of CO bound to hemocyanin. Pure half-apo preparations could not be obtained with the molluscan hemocyanins from Helix pomatia and Octopus vulgaris, and a residual fraction of sites with coupled copper is always present. However, the determination of CO bound to the protein before and after addition of H2O2, used to oxidize selectively single copper sites, reveals that CO binds to half-apo Cu(I), and is released upon oxidation of copper to met-apo Cu(II). Binding of CO to half-apo is not associated to luminescence, proving that luminescence of native carboxyhemocyanin demands the presence of a second cuprous copper in the site. In addition, analysis of data indicates that the residual amount of coupled copper sites in partially copper-depleted hemocyanin is underestimated by the residual O2-copper band measured at 340 nm in air, while faithfully quantitated by the residual luminescence in the presence of CO. A distribution of the copper left in the site of three partially copper-depleted hemocyanins is depicted.

Animals↗
PubMed1994

Properties of the flavoenzyme D-aspartate oxidase from Octopus vulgaris.

The properties of D-aspartate oxidase from Octopus vulgaris (EC 1.4.3.1) have been investigated. The protein is a monomer of M(r) 37,000 containing one mol flavin/mol protein. The enzyme as isolated exists at least in two forms, one containing FAD and the other, which is catalytically inactive, probably containing 6-OH-FAD, as inferred from the absorption spectrum of the enzyme. An additional form of the enzyme, as far as the nature of the coenzyme is concerned, has been detected in the purified enzyme and shown to derive from the form originally containing FAD. The modulation of the coenzyme reactivity exerted by Octopus D-aspartate oxidase, as studied by spectrophotometric techniques, conforms to the one expected for an enzyme belonging to the oxidase class of flavoproteins. Structural investigations show similarities in both the amino-acid composition and the N-terminal amino-acid sequence to bovine D-aspartate oxidase and porcine D-amino-acid oxidase. In summary, the general properties of the enzyme from Octopus vulgaris closely resemble those of the enzyme from beef kidney. Moreover, kinetic analyses suggest that two active-site residues with pKa of 7.1 and 9.1 are critical for catalysis, and that the ionization of such residues has different effects on the catalytic activity depending whether mono- or dicarboxylic D-amino acids are used as substrate.

Amino Acid Oxidoreductases↗
PubMed1996

Purification and properties of D-aspartate oxidase from Cryptococcus humicolus UJ1.

D-Aspartate oxidase (EC 1.4.3.1), which is highly specific to D-aspartate, was inducibly produced by a yeast strain which was isolated from soil and identified as Cryptococcus humicolus UJ1. The enzyme was purified to homogeneity as indicated on SDS-polyacrylamide gel electrophoresis. The molecular mass of the monomer subunit was determined to be 40 kDa. The native enzyme was suggested to be a homotetramer by its behavior on gel filtration. The enzyme was shown to be a flavoprotein by its absorption spectral properties, and the flavin was found to be tightly, but not covalently, bound FAD. The purified preparation had a specific activity of 76.1 mumol/min per mg protein with D-aspartate as substrate. Optimum pH was 7.5 and optimum temperature was around 35 degrees C. D-Glutamate was a very poor substrate for the enzyme. N-Methyl-D-aspartate was better than D-glutamate as substrate but markedly poorer than D-aspartate. Malonate was the most effective competitive inhibitor of the compounds tested. The N-terminal amino-acid sequence of the enzyme showed a significant homology with those of D-aspartate oxidases from beef kidney and Octopus vulgaris and those of D-amino-acid oxidases from various sources.

Amino Acid Oxidoreductases↗
PubMed1990

Two distinct light regulated G-proteins in octopus photoreceptors.

Two distinct light-regulated G-proteins were found in octopus photoreceptors. Gip, a 41 kDa protein from washed microvilli, was ADP ribosylated by pertussis toxin in the presence of GDP in the dark. Light and GTP analogues were inhibitory as with transducin (Gt; G-protein in vertebrate photoreceptors). G34, a 34 kDa protein from fresh octopus retina, was ADP ribosylated by both cholera and pertussis toxin in the dark. Light inhibited labeling of the 34 kDa protein by both toxins. Unlike Gip, G34 is soluble and is very labile to heat, freezing and thawing. Prolonged incubation of octopus retina with cholera toxin and labeled NAD produced an additional radioactive band at 46 kDa. Labeling of the 46 kDa protein, Gsp, was greatly enhanced by GTP analogues, but inhibited by a GDP analogue as with Gs in hormone-sensitive adenylate cyclase. In contrast to Gip and G34, labeling of the 46 kDa protein (Gsp) was not influenced by light. The two distinct light-regulated G-proteins, Gip and G34, found in octopus photoreceptors might be involved in either phototransduction or photoadaptation. The function of Gsp is not known.

Adenosine Diphosphate Ribose↗
PubMed1995

Acetylcholinesterase in tentacles of Octopus vulgaris (Cephalopoda). Histochemical localization and characterization of a specific high salt-soluble and heparin-soluble fraction of globular forms.

Transverse sections of Octopus tentacles were stained for acetylcholinesterase (AChE) activity. An intense staining, that was suppressed by preincubation in 10(-5) M eserine, was detected in a number of neuronal cells, nerve fibres and neuromuscular junctions of intrinsic muscles of the arm. Octopus acetylcholinesterase was found as two molecular forms: an amphiphilic dimeric form (G2) sensitive to phosphatidylinositol phospholipase C and a hydrophilic tetrameric (G4) form. Sequential solubilization revealed that a significant portion of both G2 and G4 forms was recovered only in a high salt-soluble fraction (1 M NaCl, no detergent), Heparin (2 mg/ml) was able to solubilize G2 and G4 forms with the same efficiency than 1 M NaCl. The solubilizing effect of heparin was concentration-dependent and was reduced by protamine (2 mg/ml). This suggests that heparin operates through the dissociation of ionic interactions existing in situ between globular forms of AChE and cellular or extracellular polyanionic components. Interaction of AChE molecular forms with heparin has been reported so far in only a few instances and its physiological meaning is uncertain. G2 and G4 forms, interacting or not with heparin, all belong to a single pharmacological class of AChE. This suggests the existence of a single AChE gene. Amphiphilic and hydrophilic subunits thus likely result either from the processing of a single AChE transcript by alternative splicing (as in vertebrate AChE) or from a post-translation modification of a single catalytic peptide.

Acetylcholinesterase↗
PubMed1983

High concentrations of dimethylamine and methylamine in squid and octopus and their implications in tumour aetiology.

The levels of the common secondary amines in various squid, in octopus and in 17 other seafoods were determined by HPLC. Ammonia and dimethylamine were found in all of the seafoods tested and some of them also contained methylamine and/or ethylamine. Particularly high levels of dimethylamine (946-2043 ppm) and methylamine (38-255 ppm) were detected in various species of squid and in the octopus. Reaction of nitrite in acidic medium with aqueous extract of squid yielded appreciable amounts of N-nitrosodimethylamine. The optimum pH for this reaction was around 2.4. Dimethylamine in dried squid tissues was readily extracted with water or 1% sodium carbonate solution. Heat treatment of dried squid at 200 degrees C was found to increase its amine content dramatically. It appeared that pyrolytic decarboxylation of some amino acids might cause this increase. Squid is a popular seafood in Japan and other oriental countries. The high incidence of stomach cancer in Japan and China is thought by epidemiologists to be associated with traditional Japanese and Chinese diets. Our present finding that squid and other seafoods contain unusually high levels of dimethylamine and other amines adds to the evidence that dietary factors may have an important role in the aetiology of stomach cancer and other gastro-intestinal tumours.

Animals↗
PubMed1979

Met-enkephaline-like immunoreactivity in a cephalopod neurohemal organ.

Using a highly specific antibody we found Met-enkephalin-like immunoreactivity in large granules of numerous distinct cells that are embedded in a layer of secretory terminals inside the octopus vena cava. Application of antibodies against fragments of the mammalian pro-opiocortin precursor -- alpha-MSH, ACTH, beta-endorphin and 16k-fragment -- and against growth hormone did not produce immunostaining in the octopus enkephalin cells. The vena cava neuropil may represent a favourable system for the examination of the physiological role of the opioid peptide enkephalin.

Animals↗