Cephalopod Octopus Vulgaris Research Articles

Effects of visual conditions and prey density on feeding kinetics of paralarvae of Octopus vulgaris from a laboratory spawning

Consumption rate and feeding success of newly hatched paralarvae of the cephalopod Octopus vulgaris preying on Artemia larvae were investigated in relation to visual conditions and prey density. Each paralarva was tested individually using a small-scale experimental setup; consumption over one day was measured at 208C. A factorial experiment was designed to investigate the effects on the consumption rate of two predictor variables: illumination/background (three levels: 7.5 W m 22 white light þ white background, 7.5 W m 22 white light þ blue background, darkness) and prey density (four levels: 2.35, 4.70, 9.40 and 14.10 Artemia metanauplii ml 21 ). Consumption rate varied significantly between different conditions of illumination and prey density. Light enhanced consumption rate, but different backgrounds yielded similar rates. The maximal consumption rate under illumination was close to 16 Artemia paralarva 21 day 21 , and it was around 5 Artemia paralarva 21 day 21 for assays in darkness. The predatory efficiency, measured as the proportion of prey consumed, was significantly affected by prey density, pointing to a type III functional response. The number of nonfeeding paralarvae was significantly higher in darkness and at low prey density.

The Octopus vulgaris Estrogen Receptor Is a Constitutive Transcriptional Activator: Evolutionary and Functional Implications

Steroid hormones such as estrogens and androgens are important regulators of reproduction, physiology, and development in a variety of animal taxa, including vertebrates and mollusks. Steroid hormone receptors, which mediate the classic cellular responses to these hormones, were thought to be vertebrate specific, which left the molecular mechanisms of steroid action in invertebrates unresolved. Recently an estrogen receptor (ER) ortholog was isolated from the sea hare Aplysia californica, but the functional significance of the receptor was unclear because estrogens and other steroids are not known to be important in that species. Furthermore, the Aplysia ER was found to be a constitutive transcriptional activator, but it was unclear whether the estrogen independence of the ER was an Aplysia-specific novelty or a more ancient character general to the mollusks. Here we report on the isolation and functional characterization of the first ER ortholog from an invertebrate in which estrogens are produced and play an apparent role, the cephalopod Octopus vulgaris. We show that the Octopus ER is a strong constitutive transcriptional activator from canonical estrogen response elements. The receptor does not bind estradiol and is unresponsive to estrogens and other vertebrate steroid hormones. These characteristics are similar to those observed with the Aplysia ER and support the hypothesis that the evolving ER gained constitutive activity deep in the mollusk lineage. The apparent reproductive role of estrogens in Octopus and other mollusks is unlikely to be mediated by the ER and may take place through an ancient, non-ER-mediated pathway.

Complete mitochondrial DNA sequence of a Conoidean gastropod, Lophiotoma ( Xenuroturris) cerithiformis: Gene order and gastropod phylogeny

We have determined the first complete nucleotide sequence of the mitochondrial genome of a venomous mollusc, the Conoidean gastropod, Lophiotoma ( Xenuroturris) cerithiformis. It is 15,380 nucleotide pairs (ntp) and encodes 13 proteins, two ribosomal RNAs and 22 tRNAs of the mitochondrion's own protein synthesizing system. The protein mRNAs, ribosomal RNAs and 13 of the tRNAs are transcribed from the same strand, the remaining tRNAs from the other strand. The longest segment of unassigned sequence is 139 ntp and includes a 82 ntp segment that is a perfect inverted repeat sequence of 37 ntp separated by 8 nt. The gene arrangement of L. cerithiformis mtDNA shows remarkable similarity to the gene arrangements of mtDNAs of the vetigastropod Haliotis rubra, the polyplacophoran Katharina tunicata and the cephalopod Octopus vulgaris, but differs dramatically from the gene arrangements found in the mtDNAs of pulmonate and opisthobranch gastropods, as well as mtDNAs of bivalves and scaphopods. A single sixteen gene inversion that distinguishes L. cerithiformis mtDNA from mtDNAs of H. rubra, K. tunicata and O. vulgaris is shared by mtDNA of a littorinomorph gastropod Littorina saxitalis, suggesting a close relationship of conoidean and littorinomorph gastropods.

Chromatin organization during spermiogenesis in Octopus vulgaris. II: DNA-interacting proteins.

In this article we study the proteins responsible for chromatin condensation during spermiogenesis in the cephalopod Octopus vulgaris. The DNA of ripe sperm nuclei in this species is condensed by a set of five different proteins. Four of these proteins are protamines. The main protamine (Po2), a protein of 44 amino acid residues, is extraordinarily simple (composed of only three different amino acid types: arginine (R), serine (S), and glycine (G). It is a basic molecule consisting of 79.5 mol% arginine residues. The rest of the protamines (Po3, Po4, Po5) are smaller molecules (33, 28, and 30 amino acid residues, respectively) that are homologous among themselves and probably with the main Po2 protamine. The ripe sperm nucleus of O. vulgaris also contains a small quantity of a molecule (Po1) that is similar to Po2 protamine. This protein could represent a Po2 protamine-precursor in a very advanced step of its processing. We discuss the characteristics of these proteins, as well as the relation between the complexity of chromatin condensation and the transitions of nuclear proteins during spermiogenesis in O. vulgaris.

Single exon structures of the oxytocin/vasopressin superfamily peptides of octopus

Two genes of the oxytocin/vasopressin superfamily in the cephalopod Octopus vulgaris, cephalotocin (CT) and octopressin (OP), lack introns and consist of a single exon in their protein-coding regions, which is unlike the 2 intron–3 exon structures in most vertebrates and Lys-conopressin in a pond snail Lymnaea stagnalis. Octopus may have lost introns during the evolutionary process in mollusks. mRNA that had deleted 202 bp from preproCT cDNA (CT-del) was also expressed in the brain. The deletion occurred in the central part of neurophysin. Immunohistochemical studies suggest that a translational product of CT-del mRNA may not be present in a stable form due to the loss of neurophysin. Genomic Southern blot analysis revealed that a single copy of each of OP-, CT-, and CT-del-genes was present in the genome.

Scratching the sporocyst surface: characterisation of European Aggregata species by atomic force microscopy

The application of atomic force microscopy to the understanding of surface structure and atomic-scale measurements on the sporocyst of European Aggregata species, intracellular coccidia of the cephalopods Octopus vulgaris and Sepia officinalis, is presented here. Using the roughness mean surface (RMS) as an index, we reveal texture to be a key parameter for characterisation of the sporocyst surface properties, which resolve the historical synonymy within the European Aggregatidae. Roughness measurements from RMS algorithms may also be an important diagnostic taxonomic character for the differentiation of Aggregata species in the future.

Presence of two neuropeptides in the fusiform ganglion and reproductive ducts of Octopus vulgaris: FMRFamide and gonadotropin-releasing hormone (GnRH).

We have found evidence of FMRFamide-like and cGnRH-I-like immunoreactivity in the central nervous system (CNS) and in the reproductive ducts of both female and male cephalopod Octopus vulgaris. Cell bodies and fibers were immunolocalized in the fusiform ganglion from which the nerves that reach the female and male reproductive ducts arise. FMRFamide-like and cGnRH-I-like immunoreactive nerve endings were present in the oviduct, and in the oviducal gland of the female and in the seminal vesicle of the male. The GnRH-like peptide from the reproductive ducts has been partially characterized by HPLC. The retention time of the Octopus vulgaris GnRH-like peptide was similar to the retention time of cGnRH-I. Based on these observations we suggest that FMRFamide-like and a novel GnRH-like peptide are involved in the control of reproductive ducts of Octopus vulgaris. One possibility is that the peptides affect gamete transport. Another possibility is that they regulate secretory products such as mucus and mucilaginous substances from the oviducal gland and the seminal vesicle. Our data provide further evidence to support the hypothesis of the existence of a central and peripheral peptidergic control of reproduction of Octopus vulgaris.

Sex Steroid Metabolism in the Antarctic Pteropod Clione antarctica (Mollusca: Gastropoda)

The ability of the antarctic pteropod Clione antarctica (Mollusca: Gastropoda) to synthesize sex from radiolabeled steroids from radiolabeled steroid precursors was examined in individuals sampled near the end of their observed reproductive season from McMurdo Sound, Antarctica. The precursors, 3H-progesterone and 3H-androstenedione, were absorbed and subsequently metabolized to produce several progestin and androgen metabolites, including 5a-pregnane-3,20dione, 3p-hydroxy-5oL-pregnan-20-one, 3 3-hydroxy-4-pregnen-20-one, 5o-androstane-3,17-dione, 3 B-hydroxy-5x-androstan-17-one (androsterone), and 3p3-hydroxy-5a-androstan-17-one (epiandrosterone). Synthesis or accumulation of testosterone and estradiol was not observed. At least 2 unidentified, water-soluble progestin metabolites were synthesized, as well as an unidentified esterified steroid. The metabolic accumulation of these steroidal compounds indicates that C. antarctica can produce potentially bioactive steroids. The activity of steroid metabolic enzymes in a polar species further indicates the universal capacity of invertebrates from various geographic regions to metabolize biologically relevant steroids. Additional key words: androgen, progesterone, invertebrate, polar, endocrinology The potential for endocrine regulation of physiological processes within the Mollusca was recognized several decades ago with classic ablation experiments conducted on the cephalopod Octopus vulgaris. These studies demonstrated the dependency of gonadal development on neuroendocrine signals from the optic glands (Wells & Wells 1959; Wells 1960). Further studies noted the involvement of several organs (particularly the optic tentacles, brain, and gonads) and certain neuronal peptides in the regulation of specific physiological processes such as ovulation (Geraerts et al. 1983), vitellogenesis (Geraerts & Joosse 1975), and growth and differentiation (Feral et al. 1987) in molluscs. The majority of reports on molluscan endocrinology have been concerned with neuroendocrine aspects (reviewed by Joosse 1979). The role of other (potentially) endocrine components such as the sex steroids has not been examined extensively. Early investigations of the giant land slug Ariolimax californicus (see Lehoux & Sandor 1970) revealed the presence of steroids and steroid metabolizing enzymes, suggesting that a class of vertebrate hormones was present in representatives of the Mollusca. Subsequent reports noted the presence of sex steroids (progestins, androgens, and estrogens) in at least three molluscan aTo whom correspondence should be addressed. classes: cephalopods (Carreau & Drosdowsky 1977), pelecypods (De Longcamp et al. 1974; Reis-Henriques & Coimbra 1990), and gastropods (De Jong-Brink et al. 1981; Le Guellec et al. 1987). Variations in the quantity and quality of these steroids were correlated with reproduction, growth, and development, suggesting that steroids are regulators of physiological processes in molluscs. Pteropods are pelagic opisthobranch gastropods and are divided into two orders, thecosomes and gymnosomes. Thecosomatous pteropods possess a shell, feed on algae, and are often protandrous hermaphrodites. In contrast, gymnosomatous pteropods lack a shell, feed exclusively on thecosomatous pteropods, and may occur as simultaneous hermaphrodites (Lalli & Gilmer 1989). Clione antarctica (SMITH 1902), a gymnosomatous pteropod, has a circumpolar distribution around Antarctica (Gilmer & Lalli 1990). Reports concerning the reproductive physiology of C. antarctica are limited to a description of the simultaneous hermaphroditic condition of mature individuals (Lalli & Gilmer 1989) and field observations on mate attraction and copulation (M. Slattery, pers. comm.). The long term goals of this study are to evaluate the endocrine regulation of behavior and reproduction in antarctic pteropods. In this paper we report the ability of C. antarctica to metabolize C21 (progesterone) and C19 (androstenedione) steroids. This content downloaded from 207.46.13.50 on Sat, 09 Apr 2016 06:47:22 UTC All use subject to http://about.jstor.org/terms Hines, Bryan, Wasson, McClintock, & Watts

Occurrence of free D-aspartic acid in the circumsoesophageal ganglia of [formula omitted][formula omitted

This study reports the presence of high concentrations of free D-aspartic acid (D-Asp) in the circumoesophageal ganglia of the opisthobranch mollusc Aplysia fasciata . D-Asp was discovered using specific methods that employ Octopus D-aspartate oxidase and hog kidney D-amino acid oxidase to measure D-Asp levels. The concentration of D-Asp was 0.281 μmol/g wet tissue weight, which was 8.3% of the total free aspartic acid (D and L forms) present. No other free D-amino acids that were oxidised by D-amino acid oxidase were detected. To our knowledge the only molluscs that have previously been shown to have D-Asp within their nervous tissue are the cephalopods Octopus vulgaris , Loligo vulgaris and Sepia officinalis . In these, as in A . fasciata , no other D-amino acids were detected within the nervous tissue. The fact that free D-Asp occurs specifically in the nervous tissue of the above molluscs suggests that it may have a neurological function that is yet to be described.

The Humboldt-El Niño scenario: coastal benthic resources and anthropogenic influences, with particular reference to the 1982/83 ENSO

The coastal waters of Peru and Chile are among the most productive of the world's oceans. A striking source of interannual variability in this upwelling ecosystem, El Nino, results in large population and community variations. During El Nino the seasonal upwelling ceases and warm, clear oceanic waters occur close inshore, setting a unique oceanographic scenario in which the performance of populations and communities can be studied. While most attention has been focused on the pelagic components of such systems, numerous changes occur in inshore, benthic populations. Likewise, little attention has been paid to the critical role of humans as predators or active users of inshore, benthic resources. Humans as components of the ecosystem can impose significant alterations on population and community structure. In this paper the fishery statistics of three economically important inshore, benthic resources (the gastropod Concholepas concholepas, the cephalopod Octopus vulgaris and the kelp Lessonia nigrescens) a...

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-NH 2, 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.

Ontogenetic and phylogenetic aspects of the cephalopod circulatory system

A brief description of the early embryonic development of the circulatory system in a representative of the coleoid cephalopods (Octopus vulgaris) is presented as an example of the rather uniform pattern observed at the outset of organogenesis. The role of the outer yolk sac both in morphogenesis and in the physiology of the embryo is emphasized. On the basis of recent observations reported in the literature, a preliminary comparison with the yolk sac ofNautilus is made, which in particular allows one to assess the relative importance of embryo size and bauplan constraints, respectively.

Analysis of Octopus vulgaris hemolymph containing a glycoprotein with blood group A-like properties

1. 1. The cell-free hemolymph of the cephalopod Octopus vulgaris was analyzed with respect to protein, carbohydrate components, free amino acids and copper. 2. 2. The dry weight of Octopus serum is 184 mg/ml, the protein concentration is 108 mg/ml, and carbohydrates are 17.1 mg per 100 mg dry weight. 3. 3. One of the hemolymph components, a glycoprotein with blood group A-like properties, was isolated by means of ammonium sulphate precipitation, gel filtration and affinity chromatography on Helix pomatia agglutinin Agarose. 4. 4. The carbohydrate portion of the A-like substance was analyzed by gas chromatography, which showed an extremely high percentage of hexosamines.

Experimental Studies on the Biokinetics of Plutonium and Americium in the Cephalopod Octopus vulgaris

Experimental Studies on the Biokinetics of Plutonium and Americium in the Cephalopod Octopus vulgaris

High Concentrations of Transuranics and Natural Radioactive Elements In the Branchial Hearts of the Cephalopod Octopus vulgaris

Data are reported which show elevated levels of plutonium and americium in the branchial hearts of the common cephalopod Octopus vulgaris. These levels were verified in both a laboratory experiment and in environmental samples. At the same time data for certain naturally-occurring radioactive isotopes of thorium, polonium and lead are given for comparison. Attention is d~rec ted to the potential of these small organs as monitors of transuranics and, probably, certain other elements in the marine environment. The behaviour of transuranic elements in marine organisms is currently the subject of detailed study. Development of the nuclear industry will require that monitoring of plutonium, in particular, be continued in marine samples, and the identification of organisms, or organs thereof, which consistently accumulate transu r a n i c ~ to elevated levels is a matter of importance. Investigations are usually of two types: either a laboratory investigation is carried out, in which animals are exposed to sea water and/or food labelled with an appropriate radioactive isotope (Vilquin et al., 1975; Guary and Fowler, 1977; Fowler and Guary, 1977), or measurements are made of the transuranic elements at the very low levels at which they are found in environmental samples (Pillai et al., 1964; Noshkin, 1972; Higgo et al., 1977). The former are less tedious, but their interpretation is frequently ambiguous because it is very difficult to reproduce exactly in the laboratory such factors as the physico-chemical form of the element and the partitioning of its mode of uptake into the animal via the alternative routes of food and water. We report here the results of an investigation in which both approaches were used. Unambiguous confirmation was obtained of elevated levels of plutonium and americium in the branchial hearts of the common octopus; also reported are levels of certain naturally' On leave from the Phys~cs Department, University of Cape Town occurring radioactive isotopes of thorium, polonium and lead in the same organs. We suggest that these small organs have considerable potential as monitors of transuranics and, probably, other elements in the environment. Four individuals of the molluscan cephalopod Octopus vulgaris, ranging in wet weight from 80 to 140 g, were caught off Monaco. They were placed in filtered and aerated sea water maintained at 13 + l C; the sea water was spiked with 237P~ adjusted to the + 4 state (Fowler et al., 1975) at 0.7 kBq (20 nCi) 1-' for two of the cephalopods, and with 2 4 1 ~ m (assumed to be in the + state) at 1 kBq (30 nCi) 1-' for the other two. Throughout a 15-d period the activity of the test animals was monitored regularly by gamma-spectrometry using a 3 NaI (Tl) crystal; at the end of this period the cephalopods were dissected and the concentrations of the nuclides in the various organs were measured. Details of the uptake phase, the many organs involved, etc., will be given elsewhere; for our present purposes, the data given in Table 1 are of primary importance. They highlight the situation in the branchial hearts vis-a-vis the hepatopancreas; it is well-known that the latter organ accumulates many elements effectively. The high percentages of both nuclides in the branchial hearts, which constitute a mere 0.3 % by weight of the whole animal, are immediately apparent, as are the high concentration factors with respect to the labelled sea water. We next performed an elimination experiment. Four further Octopus vulgaris (300 to 400 g wet weight each) were placed in 2 7 P ~ and 2 4 1 ~ r n labelled sea water for 10 d, under the same conditions as previously. Each individual was then transferred to flowing (unlabelled) sea water, and was fed daily with crabs and gamma-counted regularly. For both nuclides the loss curve showed a three component loss. The first component (representing desorption) was very rapid and contained about 24 % of the Pu and Am; the

Association of Americium-241 with Adenochromes in the Branchial Hearts of the Cephalopod Octopus vulgaris

Association of Americium-241 with Adenochromes in the Branchial Hearts of the Cephalopod Octopus vulgaris

Use of the beaks and raduala by Octopus vulgaris in feeding

The role of the chitinous beaks and the radula of the cephalopod Octopus vulgaris Lamarck, when feeding on either live shore crabs or whole dead fish, has been examined. One or more of these mouthparts was removed surgically and the effect on the quantity of food eaten and the method of cleaning the prey followed. The condition of the digestivetract was observed at post‐mortem.