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PubMed1998

Occurrence of a novel collagen with three distinct chains in the cranial cartilage of the squid Sepia officinalis: comparison with shark cartilage collagen.

A unique collagen with three distinct chains, was purified from the cranial cartilage of the squid Sepia officinalis, by pepsinisation and salt precipitation and compared with shark cartilage collagen. These chains, which were different from the known cartilage collagen chains, were referred as C1, C2 and C3, had approximate molecular weights of 105 kDa, 115 kDa and 130 kDa, respectively, and were present in a ratio of 3:2:1, suggestive of two molecules of composition, [(C1)2C2] and [C1C2C3]. These collagens were purified by fractionation at acid and neutral pH, and by ammonium sulfate precipitation. Solubility data indicated that this collagen was more crosslinked than the type I collagen isolated from cartilage of shark, Carcharius acutus. In vitro fibrillogenesis revealed that the sepia collagen formed denser aggregates, as compared to shark collagen, and was stabilised by a higher degree of carbohydrate association. Polyclonal antisera raised against shark collagen was also reactive against the sepia collagens, while the converse was not true, indicating the high immunospecificity of the latter. These results demonstrate collagen polymorphism in an invertebrate cartilage and may hold significance in understanding tissue calcification and molecular evolution. Further, these collagens may represent ancestral forms of vertebrate minor collagens like typeV/XI.

Animals↗

PubMed2003

Melanogenesis in the ink gland of Sepia officinalis.

Among the various melanin-producing systems, the ink gland of the cuttlefish (Sepia officinalis) has traditionally been regarded as a most convenient model system for the studies of melanogenesis. The ink gland is a highly specialized organ with immature cells in the inner portion, from where the cells gradually mature, migrate towards the outer portion of the gland and become competent to produce melanin giving rise to particulate melanosomes. When cell maturation is complete, melanin is secreted into the lumen of the gland, accumulated into the ink sac and ejected on demand. Biochemical studies carried out over the past two decades have shown that the ink gland contains a variety of melanogenic enzymes, including tyrosinase, a peculiar dopachrome rearranging enzyme (which catalyses the rearrangement of dopachrome to 5,6-dihydroxyindole) and a peroxidase (presumably involved in the later stages of melanin biosynthesis). These enzymes are functionally interactive in close subcellular compartments of ink gland cells and appear to act in a concerted fashion during the process of melanogenesis in the mature portion of the gland. More recent studies have revealed that ink production and ejection are affected and modulated by the N-methyl-D-aspartate (NMDA)-nitric oxide (NO)-cyclic GMP (cGMP) signalling pathway. Glutamate NMDA receptor and NO synthase, the enzyme responsible for the synthesis of NO, have been detected by biochemical and immunohistochemical techniques in immature ink gland cells. Stimulation of NMDA receptors caused a marked elevation of cGMP levels, activation of tyrosinase and increased melanin synthesis in the mature portion of the gland, via the NO-guanylyl cyclase interaction. This signalling is also present in different regions of the nervous system in Sepia and in certain neural pathways controlling contraction of the ink sac sphincters and wall muscle in the ejection mechanism. Overall, these and other findings allowed elaboration of an improved model of melanin formation in Sepia, which underscores the complex interplay of melanogenic enzymes and regulatory factors, highlighting both the similarities and the differences with melanogenesis in mammals.

Animals↗

PubMed2004

Ion-exchange and adsorption of Fe(III) by Sepia melanin.

Sepia eumelanin is associated with many metal ions, yet little is known about its metal binding capacity and the chemical nature of the binding site(s). Herein, the natural concentrations of metal ions are presented and the ability to remove metals by exposure of the melanin granules to EDTA is quantified. The results reveal that the binding constants of melanin at pH 5.8 for Mg(II), Ca(II), Sr(II) and Cu(II) are, respectively, 5, 4, 14 and 34 times greater than the corresponding binding constants of these ions with EDTA. By exposing Sepia eumelanin to aqueous solutions of FeCl(3), the content of bound Fe(III) can be increased from a natural concentration of approximately 180 ppm to a saturation limit of approximately 80 000 ppm or 1.43 mmol/g of melanin. Similar saturation limits are found for Mg(II) and Ca(II). Exposure of Sepia melanin granules to aqueous solutions containing Ca(II) results in the stoichiometric replacement of the initially bound Mg(II), arguing that these two ions occupy the same binding site(s) in the pigment. The pH-dependent binding of Mg(II) and Ca(II) suggests coordination of these ions to carboxylic acid groups in the pigment. Mg(II) and Ca(II) can be added to a Fe(III)-saturated melanin sample without affecting the amount of Fe(III) pre-adsorbed, clearly establishing Fe(III) and Mg(II)/Ca(II) occupy different binding sites. Taking recent Raman spectroscopic data into account, the binding of Fe(III) is concluded to involve coordination to o-dihydroxyl groups. The effects of metal ion content on the surface morphology were analyzed. No significant changes were found over the full range of Fe(III) concentration studied, which is supported by the Brunauer-Emmett-Teller surface area analysis. These observations imply the existence of channels within the melanin granules that can serve to transport metal ions.

Adsorption↗

PubMed2005

Metal-ion interactions and the structural organization of Sepia eumelanin.

The structural organization of melanin granules isolated from ink sacs of Sepia officinalis was examined as a function of metal ion content by scanning electron microscopy and atomic force microscopy. Exposing Sepia melanin granules to ethelenediaminetetraacetic acid (EDTA) solution or to metal salt solutions changed the metal content in the melanin, but did not alter granular morphology. Thus ionic forces between the organic components and metal ions in melanin are not required to sustain the natural morphology once the granule is assembled. However, when aqueous suspensions of Sepia melanin granules of varying metal content are ultra-sonicated, EDTA-washed and Fe-saturated melanin samples lose material to the solution more readily than the corresponding Ca(II) and Mg(II)-loaded samples. The solubilized components are found to be 5,6-dihydroxyindole-2-carboxylic acid (DHICA)-rich constituents. Associated with different metal ions, Na(I), Ca(II) and Mg(II) or Fe(III), these DHICA-rich entities form distinct two-dimensional aggregation structures when dried on the flat surface of mica. The data suggest multiply-charged ions play an important role in assisting or templating the assembly of the metal-free organic components to form the three-dimensional substructure distributed along the protein scaffold within the granule.

Animals↗

PubMed1985

Brain vascular volume, electrolytes and blood-brain interface in the cuttlefish Sepia officinalis (Cephalopoda).

Cephalopod molluscs have complex brains and behaviour, yet little is known about the permeability of their blood-brain interface. This paper presents studies on the brain fluid and electrolyte compartments of the cuttlefish Sepia, as a preliminary to characterization of the permeability of the blood-brain interface in this group. Sepia is shown to be a satisfactory experimental animal, and techniques are described for anaesthesia, cannulation, and tissue and fluid analysis. Our ionic analyses of body fluids are in general agreement with those of earlier workers. Analysis of brain tissue suggests that the extracellular space is 17-20 ml 100 g tissue-1 (i.e. 17-20%). Two large molecular weight tracers, 125I-human serum albumin (HSA) and Blue dextran, give consistent values for the brain vascular volume of 3.5-5.5%, slightly higher than in vertebrates. The HSA results further confirm that the Sepia blood-brain interface is relatively tight to proteins. Finally, we have shown that the fluid surrounding the brain, pericerebral fluid (PCF), is in relatively free communication with plasma.

Animals↗

PubMed1994

On the respiratory flow in the cuttlefish sepia officinalis.

The respiratory flow of water over the gills of the cuttlefish Sepia officinalis at rest is produced by the alternate activity of the radial muscles of the mantle and the musculature of the collar flaps; mantle circular muscle fibres are not involved. Inspiration takes place as the radial fibres contract, thinning the mantle and expanding the mantle cavity. The rise in mantle cavity pressure (up to 0.15 kPa), expelling water via the siphon during expiration, is brought about by inward movement of the collar flaps and (probably) mainly by elastic recoil of the mantle connective tissue network 'wound up' by radial fibre contraction during inspiration. Sepia also shows a second respiratory pattern, in which mantle cavity pressures during expiration are greater (up to 0.25 kPa). Here, the mantle circular fibres are involved, as they are during the large pressure transients (up to 10 kPa) seen during escape jetting. Active contraction of the muscles of the collar flaps is seen in all three patterns of expulsion of water from the mantle cavity, electrical activity increasing with increasing mantle cavity pressures. Respiratory expiration in the resting squid Loligo vulgaris is probably driven as in Sepia, whereas in the resting octopus Eledone cirrhosa, the mantle circular musculature is active during expiration. The significance of these observations is discussed.

Journal Article↗

PubMed2000

[Effect of sepia on intracellular Ca2+ concentration, nuclear Ca2+/Mg(2+)-ATPase activities and c-jun expression in H22 cancer cells].

The effect of sepia on the intracellular Ca2+ concentration, nuclear Ca2+/Mg(2+)-ATPase activities and the expression of c-jun were studied in H22 cancer cells by using fluorescent probe and immunohistochemical method. The results showed that intracellular Ca2+ concentration decreased 69% and 79%, nuclear Ca2+/Mg(2+)-ATPase activities diminished 21% and 37%, c-jun expression decreased obviously. The results suggested that sepia probably diminished the intracellular Ca2+ concentration, affected Ca(2+)-dependent nuclear Ca2+/Mg(2+)-ATPase activities, thus reduced the amount of Ca2+ transporting into nuclei, so lessened the promoting effect of Ca2+ on c-jun expression, and therefore inhibited cellular differentiation and proliferation. This might be one of the possible anti-cancer mechanisms of sepia.

Animals↗

PubMed1995

Modulatory effect of sepia shell extract on activity of glucose-6-phosphatase and alanine amino transferase in diabetic mice.

Alkali extract of sepia shell possesses hypoglycemic effect. The status of glycogen and pyruvate and the activity of glucose-6-phosphatase and alanine amino transferase in liver was studied under the influence of sepia shell extract in both normal and streptozotocin induced diabetic mice. The glycogen concentration was elevated steeply in both and the pyruvate concentration increased substantially in diabetic mice, while the activity of glucose-6-phosphatase and alanine amino transferase was inhibited in normal and diabetic mice. The sepia shell extract enhances glycogenesis and reduces the formation of glucose from metabolic intermediates like pyruvate and glucose-1-phosphate and by suppressing gluconeogenesis.

Alanine Transaminase↗

PubMed2005

Identification of SepCRP analogues in the cuttlefish Sepia officinalis: a novel family of ovarian regulatory peptides.

In the cuttlefish, Sepia officinalis, the ovary appears to be one of the main sources of regulatory peptides involved in the successive steps of egg-laying. Following the identification of the SepCRP-1, which is a peptide extracted from ovary and involved in egg capsule secretion, investigations were focused on the identification of related peptides. Seven related-Sepia Capsule Releasing Peptides (R-SepCRPs) were identified by means of mass spectrometry and characterized using MS/MS spectra and/or Edman degradation. Finally, primary structures were verified by the comparison of MS/MS spectra from endogenic and synthetic peptides. This new ovarian peptide family exhibits a conserved SLXKD tag involved in the biological activity. LC-MS/MS screening clearly demonstrates that R-SepCRPs are restricted to the female genital tract. Expressed during vitellogenesis, they are released by vitellogenic follicles and full-grown oocytes (FGO) in the genital coelom. Biological activities suggest that R-SepCRPs would be responsible for the storage of FGO before mating and would take part in the mechanical secretion of egg capsule products, as previously described for SepCRP-1.

Amino Acid Sequence↗

PubMed2005

Nitric oxide synthase in the nervous system and ink gland of the cuttlefish Sepia officinalis: molecular cloning and expression.

Nitric oxide (NO) signaling is involved in numerous physiological processes in mollusks, e.g., learning and memory, feeding behavior, neural development, and defence response. We report the first molecular cloning of NOS mRNA from a cephalopod, the cuttlefish Sepia officinalis (SoNOS). SoNOS was cloned using a strategy that involves hybridization of degenerate PCR primers to highly conserved NOS regions, combined with RACE procedure. Two splicing variants of SoNOS, differing by 18 nucleotides, were found in the nervous system and the ink gland of Sepia. In situ hybridization shows that SoNOS is expressed in the immature and mature cells of the ink gland and in the regions of the nervous system that are related to the ink defence system.

Amino Acid Sequence↗

PubMed2006

Color blindness and contrast perception in cuttlefish (Sepia officinalis) determined by a visual sensorimotor assay.

We tested color perception based upon a robust behavioral response in which cuttlefish (Sepia officinalis) respond to visual stimuli (a black and white checkerboard) with a quantifiable, neurally controlled motor response (a body pattern). In the first experiment, we created 16 checkerboard substrates in which 16 grey shades (from white to black) were paired with one green shade (matched to the maximum absorption wavelength of S. officinalis' sole visual pigment, 492 nm), assuming that one of the grey shades would give a similar achromatic signal to the tested green. In the second experiment, we created a checkerboard using one blue and one yellow shade whose intensities were matched to the cuttlefish's visual system. In both assays it was tested whether cuttlefish would show disruptive coloration on these checkerboards, indicating their ability to distinguish checkers based solely on wavelength (i.e., color). Here, we show clearly that cuttlefish must be color blind, as they showed non-disruptive coloration on the checkerboards whose color intensities were matched to the Sepia visual system, suggesting that the substrates appeared to their eyes as uniform backgrounds. Furthermore, we show that cuttlefish are able to perceive objects in their background that differ in contrast by approximately 15%. This study adds support to previous reports that S. officinalis is color blind, yet the question of how cuttlefish achieve "color-blind camouflage" in chromatically rich environments still remains.

Animals↗

PubMed2006

Critical temperatures in the cephalopod Sepia officinalis investigated using in vivo 31P NMR spectroscopy.

The present study was designed to test the hypothesis of an oxygen limitation defining thermal tolerance in the European cuttlefish (Sepia officinalis). Mantle muscle organ metabolic status and pHi were monitored using in vivo 31P NMR spectroscopy, while mantle muscle performance was determined by recording mantle cavity pressure oscillations during ventilation and spontaneous exercise. Under control conditions (15 degrees C), changes in muscle phospho-L-arginine (PLA) and inorganic phosphate (Pi) levels could be linearly related to frequently occurring, high-pressure mantle contractions with pressure amplitudes (MMPA) of >0.2 kPa. Accordingly, mainly MMPA of >2 kPa affected muscle PLA reserves, indicating that contractions with MMPA of <2 kPa only involve the thin layers of aerobic circular mantle musculature. On average, no more than 20% of muscle PLA was depleted during spontaneous exercise under control conditions. Subjecting animals to acute thermal change at an average rate of 1 deg. h-1 led to significant Pi accumulation (equivalent to PLA breakdown) and decrements in the free energy of ATP hydrolysis (dG/dzeta) at both ends of the temperature window, starting at mean critical temperatures (Tc) of 7.0 and 26.8 degrees C, respectively. Frequent groups of high-pressure mantle contractions could not (in the warm) or only partially (in the cold) be related to net PLA breakdown in mantle muscle, indicating an oxygen limitation of routine metabolism rather than exercise-related phosphagen use. We hypothesize that it is mainly the constantly working radial mantle muscles that become progressively devoid of oxygen. Estimates of very low dG/dzeta values (-44 kJ mol-1) in this compartment, along with correlated stagnating ventilation pressures in the warm, support this hypothesis. In conclusion, we found evidence for an oxygen limitation of thermal tolerance in the cuttlefish Sepia officinalis, as indicated by a progressive transition of routine mantle metabolism to an anaerobic mode of energy production.

Adaptation, Physiological↗

PubMed2004

N-methyl-D-aspartate receptor-like immunoreactivity in the brain of Sepia and Octopus.

Ionotropic glutamate receptors have been subdivided into N-methyl-D-aspartate (NMDA) and AMPA/kainate classes. NMDA receptor subunit 2A and 2B immunoreactivity is shown to be present in specific regions of the central nervous system (CNS) of the cephalopod molluscs Sepia officinalis and Octopus vulgaris. An antibody that recognizes both mammalian NMDAR2A and NMDAR2B subunits equally was used. SDS-PAGE/Western blot analysis performed on membrane proteins revealed an immunoreactive band at 170 kDa for both species. Immunoreactive bands from both Octopus and Sepia brains disappeared when the antibody was preabsorbed with membrane proteins from rat hippocampus or from their own brains. The same antibody was then used for immunohistochemical staining of serial sections of the CNS to reveal localized specific staining of cell bodies and fibers in several lobes of the brain. Staining was found in lower motor centers, in some higher motor centers, in learning centers, and in the optic lobes. Immunopositivity was also found in the areas of brain that control the activity of the optic gland, a gonadotropic endocrine gland. These findings suggest that glutamate, via NMDA receptors, may be involved as a signaling molecule in motor, learning, visual, and olfactory systems in the cephalopod brain.

Animals↗

PubMed2000

The SepOvotropin: a new ovarian peptide regulating oocyte transport in Sepia officinalis.

In the cuttlefish Sepia officinalis, the successive steps of egg laying are controlled by multiple neuropeptides. Recent experiments led us to suppose that there was possible involvement of a second regulation pathway by the release of ovarian regulatory peptides in the genital tract. Using HPLC fractionation and an in vitro biological test, a C-terminal amidated peptide modulating the motility of the Sepia officinalis oviduct was isolated from an extract of vitellogenic ovarian follicles. The mass of this peptide as determined by MALDI-TOF (1501.8 Da) and analysis by Edman degradation led to the following sequence: Pro-Lys-Asp-Ser-Met-Leu-Leu-Leu-Gln-Val-Pro-Val-Tyr-amide. The peptide mapping performed by LC/MS revealed a distribution restricted to the follicles, the full grown oocytes and the eggs. This new peptide, called SepOvotropin, modulated contractions of the whole genital tract in physiological conditions from a threshold concentration between 10(-20) and 10(-19) M, demonstrating for the first time the occurrence of a specific peptidergic control of egg-laying in cephalopods.

Amino Acid Sequence↗

PubMed2002

Melanocyte-stimulating hormone plasma levels and environmental illumination in the cuttlefish, Sepia officinalis: a role for the neurosecretory system of the vena cava in cephalopods.

A melanotropin-like peptide (alpha-melanocyte-stimulating hormone or alpha-MSH) is suggested to be released into the circulatory system of cephalopods via the neurosecretory system of the vena cava or NSV, where neurosecretory vesicles contained within the axons of the NSV-neuropil on the inner surface of the vena cava lie in close contact with the venous circulation. Radioimmunoassay of blood plasma samples taken from the cephalic vein of anaesthetised cuttlefish, Sepia officinalis showed that immunoreactive alpha-MSH (ir alpha-MSH) was detectable within the cuttlefish circulatory system. The validity of the assay for determination of cuttlefish ir alpha-MSH was determined by parallelism of the alpha-MSH standard curve against serially diluted cuttlefish plasma samples. Plasma samples taken during a natural day-night-day illumination cycle showed a significant elevation in ir alpha-MSH concentration to 1.44 +/- 0.26 ng ml(-1) during the middle of the dark phase compared to concentrations of 0.48 +/- 0.13 and 0.35 +/- 0.10 ng ml(-1) in the middle of the light phases of the illumination cycle. So far, indirect evidence suggests Sepia officinalis may modulate chromatophore activity, body patterning, and behaviour via neuroendocrine release and circulating titres of this proopiomelanocortin-derived peptide.

Animals↗

PubMed1998

Intramolecular localization of the functional units of Sepia officinalis hemocyanin by immunoelectron microscopy.

The quaternary structure of Sepia officinalis hemocyanin (Hc) as studied in immunoelectron microscopy with rabbit IgGs and Fab fragments raised against functional units (FU) Soc, Sod, Soe, Sof, Sog, and Soh and fragment Soab. The architecture of immunocomplexes shows that (i) epitopes characteristic of FUs Soc and Sog and of fragment Soab are located in the two external tiers of FUs, (ii) FUs Soh and Soe or Sod are located in arches. These results were confirmed using immunocomplexes made up of Sepia Hc and IgGs or Fab fragments purified from antisera raised against FUs of Octopus vulgaris and Octopus dofleini. Frozen-hydrated immunocomplexes containing one Hc molecule and at least one FU-specific Fab fragment were observed in the electron microscope and submitted to image processing. When the Hc molecule is viewed along its 5-fold axis (i) anti-Soc Fab fragments project on a radius passing through the arch's pillar, (ii) anti-Sof Fabs project slightly out of the arches, and (iii) anti-Soh Fabs project between neighboring arches. When applied to a recent three-dimensional (3D) reconstruction volume, these results allow us to deduce the intramolecular location of five of the eight FUs. For the last three FUs limited uncertainties remain: (i) Soc can be located in two positions in the external tier of FUs; (ii) Soa and Sob can both occupy three positions in the external tiers; and (iii) because of an immunological cross-reactivity Sod may be located in the wall and Soe in the arch, or vice versa. An analysis of the quaternary structure considering the possible locations of the 80 FUs and postulating a single type of subunit shows that 80 possibilities of paths still exist for the polypeptide chain. To solve definitely these 80 possibilities only five questions remain to be answered.

Animals↗

PubMed2000

Sepia officinalis hemocyanin: A refined 3D structure from field emission gun cryoelectron microscopy.

The extracellular respiratory pigment of the cuttlefish Sepia officinalis was observed by cryoelectron microscopy with conventional LaB(6) and field emission gun electron sources at 100 and 200 kV, respectively. Each image series was used to compute one 3D reconstruction volume with correction of the contrast transfer function by Wiener filtering. A strong boosting of the contrast was corrected by band-pass filtering of the final volumes, and a qualitative gain in resolution was observed when using the field emission gun electron microscope. In this volume, a strong signal is present down to 1/18 A(-1) and some meaningful information is obtained down to 1/12.5 A(-1). The complex is composed of five pairs of polypeptide chains and resembles a hollow cylinder with five wall oblique units and five inner arches. Three types of wall-wall connections termed pillar P1 to P3 are visible in this volume and the four functional units present in the arches are each linked to the wall by two arch-wall connections. The dispositions of the functional units in the arches of Sepia and Octopus hemocyanins share no common feature.

Animals↗

PubMed1992

Electron-dense tracer evidence for a blood-brain barrier in the cuttlefish Sepia officinalis.

Electron-dense tracers were used to study the permeability of the blood-brain interface in a cephalopod mollusc, the cuttlefish Sepia officinalis. Gel filtration established that horseradish peroxidase is a suitable tracer for in vivo injection, but microperoxidase is not, being subject to binding by plasma proteins. Perfusion-fixed brain vertical and optic lobes showed no endogenous peroxidatic activity. Horseradish peroxidase was injected intravenously, and allowed to circulate for 10-35 min before tissue fixation by immersion or perfusion. Horseradish peroxidase reaction product was undetectable in the bulk of the brain parenchyma. In microvessels, venous vessels and at the brain surface, horseradish peroxidase penetrated the layers of endothelial and pericyte cells, being stopped by the layer of perivascular glia. In arterial vessels, tracer restriction occurred at the level of the pericytes. In the region of tracer blockade, a gradient of tracer could be traced in the intercellular cleft, from high at the luminal end to undetectable at the tissue end. The clefts of the restricting zone were generally wide (15-20 nm), with faint periodicities or linking structures spanning the cleft, and contained a fibrillar extracellular material. Perfusion of lanthanum chloride in saline for 15 min, followed by precipitation of lanthanum phosphate during fixation, resulted in lanthanum tracer distribution similar to that of horseradish peroxidase. Horseradish peroxidase was seen filling extracellular spaces within the neuropile when the blood-brain barrier was breached by a stab wound, indicating that the interstitium itself does not restrict tracer diffusion. It is concluded that Sepia has a blood-brain barrier tight to horseradish peroxidase and ionic lanthanum. The restricting junction is not a typical zonula occludens or septate junction, but appears to reduce tracer penetration by a filtering mechanism within the extracellular cleft. The barrier is formed by perivascular glial cell processes in the microvessels and venous vessels, but by pericytes in arterial vessels. This organization suggests that a glial blood-brain barrier may be the primitive condition, and a barrier associated with vascular elements (endothelium/pericyte) a later development.

Animals↗