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PubMed1989

Isolation, characterization, and amino acid sequence of a polypeptide neurotoxin occurring in the sea anemone Stichodactyla helianthus.

An aqueous exudate collected from frozen and thawed bodies of a Caribbean sea anemone, Stichodactyla (formerly Stoichactis) helianthus, contained a polypeptide neurotoxin (Sh I) selectively toxic to crustaceans. The polypeptide was purified by G-50 Sephadex, phosphocellulose, and sulfopropyl-Sephadex chromatography and shown to have a molecular size of 5200 daltons and a pI of 8.3. The amino acid sequence determined by automatic Edman degradations of whole RCM Sh I and of its clostripain, staphylococcal protease, and cyanogen bromide digest peptides is A1ACKC5DDEGP10DIRTA15PLTGT20VDLGS25CNAGW30EKCAS35YYTII40ADCCR45KKK . Only 33% of this sequence is identical with the sequence of Anemonia sulcata toxin II, a sea anemone toxin isolated from the taxonomic family Actiniidae. The six half-cystines are located in equivalent positions to those of the actiniid toxins and account for nearly half of the residues common to all of the toxins. However, 69% of the Sh I sequence is identical with that of toxin II from Heteractis paumotensis, another sea anemone belonging to the family Stichodactylidae. Stichodactylid toxins lack the initial N-terminal residue of actiniid toxins and possess three consecutive acidic residues at positions 6-8, a single tryptophan at position 30, and four consecutive basic residues at positions 45-48 (C-terminus). A rabbit IgG prepared by Sh I immunization bound Sh I with a K0.5 of 4.7 nM but failed to bind homologous actiniid (Anemonia sulcata II, Condylactis gigantea III) or bolocerid (Bolocera tuedae II) polypeptide neurotoxins.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed2004

Heat stress induces different forms of cell death in sea anemones and their endosymbiotic algae depending on temperature and duration.

Bleaching of reef building corals and other symbiotic cnidarians due to the loss of their dinoflagellate algal symbionts (=zooxanthellae), and/or their photosynthetic pigments, is a common sign of environmental stress. Mass bleaching events are becoming an increasingly important cause of mortality and reef degradation on a global scale, linked by many to global climate change. However, the cellular mechanisms of stress-induced bleaching remain largely unresolved. In this study, the frequency of apoptosis-like and necrosis-like cell death was determined in the symbiotic sea anemone Aiptasia sp. using criteria that had previously been validated for this symbiosis as indicators of programmed cell death (PCD) and necrosis. Results indicate that PCD and necrosis occur simultaneously in both host tissues and zooxanthellae subject to environmentally relevant doses of heat stress. Frequency of PCD in the anemone endoderm increased within minutes of treatment. Peak rates of apoptosis-like cell death in the host were coincident with the timing of loss of zooxanthellae during bleaching. The proportion of apoptosis-like host cells subsequently declined while cell necrosis increased. In the zooxanthellae, both apoptosis-like and necrosis-like activity increased throughout the duration of the experiment (6 days), dependent on temperature dose. A stress-mediated PCD pathway is an important part of the thermal stress response in the sea anemone symbiosis and this study suggests that PCD may play different roles in different components of the symbiosis during bleaching.

Animals↗

PubMed2000

Acute renal failure after a sea anemone sting.

A 27-year-old man suffering from severe swelling and pain in his right arm was referred to our hospital. He showed signs of acute renal failure (ARF) with severe dermatitis of his right arm. Three days before being admitted, he accidentally touched some kind of marine organism with his right hand while snorkeling in the Sulu Sea around Cebu Island. Within a few minutes, he was experiencing severe pain in his right hand. Then his right hand gradually became swollen. The marine creature responsible for this injury was thought to have been a sea anemone, which is a type of coelenterate. Histologic findings of a renal biopsy indicated that acute tubular necrosis (ATN) had caused ARF in this patient's case. Supportive therapies improved renal function of this patient, and steroid pulse therapy attenuated the severe skin discoloration. The ATN was thought to have been caused by the poison from a sea anemone because there were no other conceivable reasons for the patient's condition. This is the first time that a marine envenomation case has been reported in which the sting of a sea anemone has caused ATN without the failure of any other organs.

Acute Kidney Injury↗

PubMed2002

Ghost anemone dermatitis.

BACKGROUND: Haloclava producta, the "ghost anemone", is a burrowing sea anemone in estuarine sediments of the US East Coast and Gulf of Mexico. It has never been identified as harmful to human beings; however, residents of Long Island, New York develop a pruritic, erythematous, vesiculopapular dermatitis on areas of the body that contact these organisms. Neither the condition nor its cause has been described in the medical literature. METHODS: We reviewed information of all water-related dermatitis reported by beach personnel, health providers, and affected swimmers to the Office of Marine Ecology, Nassau County Department of Health, New York from 1970 to 1991. Several episodes of an unfamiliar dermatitis among clam diggers, first recognized in 1981, initiated sampling efforts in 1985 when one victim, a bay constable, identified the area he frequented. During 1991, >100 persons were affected; sampling continued during reported cases. H. producta was isolated from all suspect sediment samples and tested on healthy subjects. RESULTS: Typical of the phylum Cnidaria, H. producta has nematocysts capable of inflicting the observed dermatitis. Pressing them to the skin of healthy subjects produces dermatitis indistinguishable from that of victims. No other species with the same capability were identified from samples. CONCLUSION: H. producta is the apparent causative agent of ghost anemone dermatitis. Accurate diagnosis will allow appropriate treatment, education regarding prevention, and avoidance of unnecessary diagnostic tests or antibiotic use.

Animals↗

PubMed1986

Isolation of pyroGlu-Gly-Arg-Phe-NH2 (Antho-RFamide), a neuropeptide from sea anemones.

A radioimmunoassay has been developed for peptides containing the carboxyl-terminal sequence Arg-Phe-NH2 (RFamide). Using this radioimmunoassay and applying cation-exchange chromatography and HPLC, we have isolated an RFamide peptide from acetic acid extracts of the sea anemone Anthopleura elegantissima. Three different methods established that the structure of the Anthopleura RFamide peptide (Antho-RFamide) is pyroGlu-Gly-Arg-Phe-NH2. Comparison of synthetic and natural Antho-RFamide and their enzymatic breakdown products on six different HPLC columns confirmed the structure of the sea anemone peptide. Using synthetic Antho-RFamide as a standard in our radioimmunoassay, we measured high concentrations (3.2 nmol/g wet weight) of this peptide in extracts of Anthopleura. It is proposed that Antho-RFamide is a transmitter at neuromuscular synapses in sea anemones.

Amino Acid Sequence↗

PubMed1996

Two mitochondrial group I introns in a metazoan, the sea anemone Metridium senile: one intron contains genes for subunits 1 and 3 of NADH dehydrogenase.

Mitochondrial genes for cytochrome c oxidase subunit I (COI) and NADH dehydrogenase subunit 5 (ND5) of the sea anemone Metridium senile (phylum Cnidaria) each contain a group I intron. This is in contrast to the reported absence of introns in all other metazoan mtDNAs so far examined. The ND5 intron is unusual in that it ends with A and contains two genes (ND1 and ND3) encoding additional subunits of NADH dehydrogenase. Correctly excised ND5 introns are not circularized but are precisely cleaved near their 3' ends and polyadenylylated to provide bicistronic transcripts of ND1 and ND3. COI introns, which encode a putative homing endonuclease, circularize, but in a way that retains the entire genome-encoded intron sequence (other group I introns are circularized with loss of a short segment of the intron 5' end). Introns were detected in the COI and ND5 genes of other sea anemones, but not in the COI and ND5 genes of other cnidarians. This suggests that the sea anemone mitochondrial introns may have been acquired relatively recently.

Amino Acid Sequence↗

PubMed1998

Sea anemone peptides with a specific blocking activity against the fast inactivating potassium channel Kv3.4.

Sea anemone venom is known to contain toxins that are active on voltage-sensitive Na+ channels, as well as on delayed rectifier K+ channels belonging to the Kv1 family. This report describes the properties of a new set of peptides from Anemonia sulcata that act as blockers of a specific member of the Kv3 potassium channel family. These toxins, blood depressing substance (BDS)-I and BDS-II, are 43 amino acids long and differ at only two positions. They share no sequence homologies with other K+ channel toxins from sea anemones, such as AsKS, AsKC, ShK, or BgK. In COS-transfected cells, the Kv3.4 current was inhibited in a reversible manner by BDS-I, with an IC50 value of 47 nM. This inhibition is specific because BDS-I failed to block other K+ channels in the Kv1, Kv2, Kv3, and Kv4 subfamilies. Inward rectifier K+ channels are also insensitive to BDS-I. BDS-I and BDS-II share the same binding site on brain synaptic membranes, with K0.5 values of 12 and 19 nM, respectively. We observed that BDS-I and BDS-II have some sequence homologies with other sea anemone Na+ channels toxins, such as AsI, AsII, and AxI. However, they had a weak effect on tetrodotoxin-sensitive Na+ channels in neuroblastoma cells and no effect on Na+ channels in cardiac and skeletal muscle cells. BDS-I and BDS-II are the first specific blockers identified so far for the rapidly inactivating Kv3.4 channel.

Amino Acid Sequence↗

PubMed2002

The sea anemone toxins BgII and BgIII prolong the inactivation time course of the tetrodotoxin-sensitive sodium current in rat dorsal root ganglion neurons.

We have characterized the effects of BgII and BgIII, two sea anemone peptides with almost identical sequences (they only differ by a single amino acid), on neuronal sodium currents using the whole-cell patch-clamp technique. Neurons of dorsal root ganglia of Wistar rats (P5-9) in primary culture (Leibovitz's L15 medium; 37 degrees C, 95% air/5% CO2) were used for this study (n = 154). These cells express two sodium current subtypes: tetrodotoxin-sensitive (TTX-S; K(i) = 0.3 nM) and tetrodotoxin-resistant (TTX-R; K(i) = 100 microM). Neither BgII nor BgIII had significant effects on TTX-R sodium current. Both BgII and BgIII produced a concentration-dependent slowing of the TTX-S sodium current inactivation (IC50 = 4.1 +/- 1.2 and 11.9 +/- 1.4 microM, respectively), with no significant effects on activation time course or current peak amplitude. For comparison, the concentration-dependent action of Anemonia sulcata toxin II (ATX-II), a well characterized anemone toxin, on the TTX-S current was also studied. ATX-II also produced a slowing of the TTX-S sodium current inactivation, with an IC50 value of 9.6 +/- 1.2 microM indicating that BgII was 2.3 times more potent than ATX-II and 2.9 times more potent than BgIII in decreasing the inactivation time constant (tau(h)) of the sodium current in dorsal root ganglion neurons. The action of BgIII was voltage-dependent, with significant effects at voltages below -10 mV. Our results suggest that BgII and BgIII affect voltage-gated sodium channels in a similar fashion to other sea anemone toxins and alpha-scorpion toxins.

Animals↗

PubMed2003

APETx1, a new toxin from the sea anemone Anthopleura elegantissima, blocks voltage-gated human ether-a-go-go-related gene potassium channels.

A new peptide, APETx1, which specifically inhibits human ether-a-go-go-related gene (HERG) channels, was purified from venom of the sea anemone Anthopleura elegantissima. APETx1 is a 42-amino acid peptide cross-linked by three disulfide bridges and shares 54% homology with BDS-I, another sea anemone K+ channel inhibitor. Although they differ in their specific targets, circular dichroism spectra and molecular modeling indicate that APETx1 and BDS-I have a common molecular scaffold and belong to the same structural family of K+ channel blocking peptides. APETx1 inhibits HERG currents in a heterologous system with an IC50 value of 34 nM by modifying the voltage dependence of the channel gating. Central injections in mice failed to induce any neurotoxic symptoms. APETx1, which has no sequence homologies with scorpion toxins acting on HERG, defines a new structural group of HERG gating modifiers isolated from a sea anemone.

Amino Acid Sequence↗

PubMed1975

Influence of possible in situ ionic environment on kinetics of purified citrate synthase from an osmoconformer sea anemone, Bunedosoma cavernata.

Kinetics of utilization of acetyl coenzyme A by citrate synthase of a sea anemone, an osmoconformer, were compared with those of citrate synthases of various osmoregulators. The Kms of the latter enzymes were substantially increased by higher concentrations of salt and the enzyme exhibited hyperbolic substrate saturation curves. Citrate synthase from sea anemone, on the other hand, exhibited allosteric kinetics and minimal effects of salt on its Km. We suggest that the adaptive advantage of this enzymic property to a sedentary osmoconforming organism such as sea anemone is obvious since the osmoregulating creatures are apparently unable to maintain an appropriate low ionic environment in situ and thus probably the Km of their citrate synthases at a low level.

Allosteric Regulation↗

PubMed2001

Cellular mechanisms underlying temperature-induced bleaching in the tropical sea anemone Aiptasia pulchella.

Temperature-induced bleaching in symbiotic cnidarians is a result of the detachment and loss of host cells containing symbiotic algae. We tested the hypothesis that host cell detachment is evoked through a membrane thermotropic event causing an increase in intracellular calcium concentration, [Ca(2+)](i), which could then cause collapse of the cytoskeleton and perturb cell adhesion. Electron paramagnetic resonance measurements of plasma membranes from the tropical sea anemone Aiptasia pulchella and the Hawaiian coral Pocillopora damicornis labeled with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) revealed no membrane thermotropic event. In addition, intracellular imaging using Fura-2AM as well as labeling anemones with (45)Ca revealed no significant change in [Ca(2+)](i). However, bleaching could be evoked at ambient temperature with 25 mmol l(-1) caffeine without affecting [Ca(2+)](i). [Ca(2+)](i) could be altered with ionomycin in isolated host cells, but ionomycin could not induce bleaching in A. pulchella. As caffeine can affect levels of intracellular protein phosphorylation, the ability of other agents that alter intracellular levels of protein phosphorylation to evoke bleaching was investigated. The protein phosphatase inhibitor vanadate could induce bleaching in A. pulchella. Two-dimensional gels of (32)P-labeled proteins from cold-shocked, caffeine-treated and control anemones show that both temperature shock and caffeine alter the array of phosphorylated host soluble proteins. We conclude that cnidarian bleaching is linked to a temperature-induced alteration in protein phosphorylation.

Animals↗

PubMed1976

Nervous control of light responses in the sea anemone, Calamactis praelongus.

1. The burrowing sea anemone, Calamactis praelongus, responds to light with local, non-nervous contractions of the column. There are also more extensive responses of the column and retractor muscles co-ordinated by nerve net pulses (NNP's) under pacemaker control. 2. NNP's occur in at least two types of bursts and in sequences which sometimes indicate a rotating site of pulse initiation. 3. Light-evoked NNP sequences can be tape recorded and used later to drive a stimulator to reproduce the original sequences in the same or different anemones, evoking muscular responses which approximate the originals. This technique separates the pacemaker-directed component of the light response from the local effects of light stimulation. 4. Isolated circular and parietal muscles contract slowly when stimulated by light or excited indirectly by NNP's. Retractor muscles are insensitive to light but produce rapid contractions when excited by closely spaced light-evoked NNP's. 5. A model for light responses is proposed which incorporates the characteristics of isolated muscles and intact anemones.

Action Potentials↗

PubMedDate not supplied

Secondary metabolites and insecticidal activity of Anemone pavonina.

The insecticidal properties of the crude extracts of the leaves and flowers of Anemone pavonina were evaluated on Pheidole pallidula ants and showed significant levels of activity. Bioassay-guided fractionations led to the isolation of the butenolide ranunculin (1) as the active principle. Chemical investigations of the extracts showed them to contain as major components the sitosterol glycopyranoside lipids 2-5 and the glycerides 6-8. The structures of the metabolites were elucidated, following acetylation and hydrolysis of the natural products, by interpretation of their NMR and mass spectral data. The uncommon lipid metabolites 2-8 were isolated for the first time from the genus Anemone and this is the first report of insecticidal activity of the Anemone metabolite ranunculin against ants.

Anemone↗

PubMed1997

Homeoboxes in sea anemones (Cnidaria:Anthozoa): a PCR-based survey of Nematostella vectensis and Metridium senile.

Homeobox genes belong to a phylogenetically widespread family of regulatory genes that play important roles in pattern formation and cell-fate specification in several model systems (e.g., Drosophila, mouse, and C. elegans). Although the evolution of many classes of homeobox genes predates the diversification of the Bilateria, comparatively little is known about homeobox genes in outgroups to the Bilateria, such as the Cnidaria. We used the polymerase chain reaction to recover 12 partial homeoboxes from 2 species of sea anemones, Metridium senile and Nematostella vectensis (phylum Cnidaria; class Anthozoa). These homeoboxes appear to represent 9 distinct, mutually paralogous homeobox genes, 5 of which belong to previously identified cnidarian homeobox classes, and 4 of which appear to represent previously unidentified classes. The evolutionary relationships between the homeodomains of sea anemones and of bilaterian animals were assessed through database searches and phylogenetic analyses. As many as 5 of the anemone homeoboxes may belong to the Hox class, which suggests that the Hox gene complement of cnidarians is larger than previously expected. Homologs of the even-skipped gene of Drosophila were also identified in both Metridium and Nematostella.

Amino Acid Sequence↗

PubMed2000

Biogeography of two species of Symbiodinium (Freudenthal) inhabiting the intertidal sea anemone Anthopleura elegantissima (Brandt).

We have analyzed the genetic profiles of dinoflagellate populations obtained from the Pacific coast sea anemone Anthopleura elegantissima (Brandt) at collection sites from Washington to California. Genetic differences within the symbiont populations of California anemones have been uncovered by restriction length polymorphism (RFLP) analysis of the small subunit (SSU) and large subunit (LSU) ribosomal RNA genes, and by denaturing gradient gel electrophoresis (DGGE) of the internal transcribed spacer region 2 (ITS 2). The existence of two Symbiodinium species is substantiated by sequence analysis of the variable regions V1, V2, and V3 of the SSUrDNA, which also establishes their phylogenetic relatedness to other members of the genus Symbiodinium. Anemones from Washington and Oregon harbor a single dinoflagellate species, for which we propose the name S. muscatinei sp. nov. At these northern locations, S. muscatinei either exists alone or co-occurs with the Chlorella-like green algal symbiont. Our results indicate that S. muscatinei co-occurs with a second dinoflagellate, S. californium, in mixed populations in central and southern California. We suggest that the geographic distribution of these dinoflagellates is related to the temperature cline created by latitude.

Animals↗

PubMed1984

The interaction of sea anemone and scorpion neurotoxins with tetrodotoxin-resistant Na+ channels in rat myoblasts. A comparison with Na+ channels in other excitable and non-excitable cells.

The properties of interactions of several polypeptide neurotoxins isolated from sea anemone and scorpion venom with Na+ channels of rat myoblasts, chick myotubes, neuroblastoma cells, and fibroblasts have been compared. Tetrodotoxin (TTX)-resistant Na+ channels appear to be much more sensitive to the action of sea anemone toxins than TTX-sensitive Na+ channels but have the same affinity for scorpion neurotoxins. This conclusion holds both for Na+ channels that can be activated electrically and for silent forms of Na+ channels. The sensitivity to sea anemone toxins of the different types of Na+ channels that have been studied suggests the existence of multiple forms of Na+ channels.

Animals↗

PubMed1994

Adenylate levels and environmental stress in the sea anemone Anthopleura elegantissima.

The tissue concentrations of adenosine nucleotides in the sea anemone Anthopleura elegantissima were determined during laboratory manipulations simulating natural environmental stresses: desiccation at low and high air temperatures, increased seawater temperature, mechanical disturbance causing column contraction, and starvation. The levels of adenylates significantly decreased during anemone desiccation, column contraction, and starvation. Variations in adenylate energy charge, the ratio of adenosine triphosphate (ATP) to adenosine diphosphate (ADP) and the ratio of ATP to total adenylates were compared with changes in absolute adenylate concentrations to determine the usefulness of these ratios in indicating changes in metabolic activity and physiological stress. The changes in the adenylate levels were far greater than the changes in adenylate ratios. The usefulness of adenylate energy charge, or the other adenylate ratios, as single or exclusive indices of metabolic stress in A. elegantissima is questionable, given these results. Changes in absolute adenylate levels do indicate significant metabolic changes in the anemones associated with desiccation, column contraction, and starvation.

Adenosine Diphosphate↗

PubMed1990

Quantitative structure-activity relationships for sea anemone polypeptide toxins.

Sea anemone polypeptides vary considerably in their affinities for sodium channels occurring in different excitable cells. The amino acid sequence variation in a set of six sea anemone type I polypeptide toxins (46-49 residues long), was parameterized using descriptor scales z1, z2, and z3, derived from a large number of amino acid physicochemical properties. The pharmacological properties of the toxins were represented by the results from four bioassays on crab, mouse, and rat brain and from rat heart. By means of the descriptor scales and the multivariate data analytical method PLS (partial least squares projections to latent structures), it was possible to develop quantitative structure-activity relationships (QSAR). Using the QSARs derived from the set of six polypeptide toxins the pharmacological properties of two homologous sea anemone polypeptide toxins were predicted. Thus it is shown that QSARs may be formulated for relatively long bioactive polypeptides. The QSARs indicate that 11 different amino acid positions may be of importance, but that positions no. 5, 21, 28, 34, 37, and 40 were of main importance in modeling the relative toxicities of the six polypeptides.

Amino Acid Sequence↗