Antiproliferative and antioxidant properties of nematocysts crude venom from jellyfish Acromitus flagellatus against human cancer cell lines

This study aimed to investigate the antiproliferative and antioxidant properties of crude venom from the nematocyst of Jellyfish Acromitus flagellates on human lung cancer (A549) and liver cancer (HepG2) cell lines. The prepared crude venom was subjected to analyses of the biochemical constituents, protein profiles, antioxidant and anticancer activities by standard methods. The extracted venom was pale-yellow in color and viscous/sticky. The biochemical composition such as, protein (1.547 mg/ml), lipid (0.039 mg/ml) and carbohydrate (0.028 mg/ml) was estimated. Protein profiles were determined by SDS PAGE, the result revealed that the molecular weight range from 205 ? 3.5 kDa. The free radical scavenging activity was analyzed by the reducing potential (56.36%), DPPH (72.47%), hydroxyl (68.50%), superoxide anion (65.75%), and nitric oxide (33.04%). The cell viability was observed by using different concentrations (20 to 100 µg/ml) of crude venom on A549 and HepG2 cancer cell lines and the IC₅₀ values were recorded in (60 μg/ml and 40 μg/ml) respectively, while it had none cytotoxic effects on Vero cell line up to the concentration of 90 μg/ml. These results suggest that crude venom from nematocyst of A. flagellatus possesses anti-cancer activity and able to develop novel drugs on marine-derived compounds.     

Novel proteinaceous toxins from the nematocyst venom of the Okinawan sea anemone Phyllodiscus semoni Kwietniewski

The Okinawan sea anemone Phyllodiscus semoni is known to cause cases of severe stinging. We isolated P. semoni toxins 60A and 60B (PsTX-60A and PsTX-60B; ca. 60 kDa) as the major toxins from the isolated nematocysts of this species for the first time. PsTX-60A and PsTX-60B showed lethal toxicity to the shrimp Palaemon paucidence when administered via intraperitoneal injection (LD(50) values: 800-900 and 800 microg/kg, respectively) and hemolytic activity toward a 0.8% suspension of sheep red blood cells (ED(50) values: 600 and 300 ng/ml, respectively). Furthermore, we sequenced the cDNA encoding PsTX-60A. The deduced amino acid sequence of PsTX-60A did not show any similarity to previously reported proteins. The N-terminal amino acid sequence of PsTX-60B showed homology with that of PsTX-60A. These toxins represent a novel class of cytolytic proteinaceous toxins.     

Hydroid defenses against predators: the importance of secondary metabolites versus nematocysts

Marine hydroids are commonly thought to be defended by stinging organelles called nematocysts that penetrate predator tissues and inject proteinaceous venoms, but not all hydroids possess these nematocysts. Although an increasing number of bioactive secondary metabolites have been isolated from marine hydroids, ecological roles of these compounds are poorly known. To test the hypothesis that nematocysts and noxious secondary metabolites represent alternative defenses against predation, we examined hydroids from North Carolina, United States for: (1) the palatability of whole polyps before and after nematocysts had been deactivated; (2) the palatability of their chemical extracts; and (3) their nutritional value in terms of organic content, protein content, and levels of refractory structural material (chitin). All hydroids were avoided by a generalist predator, the pinfish Lagodon rhomboides, compared with palatable control foods. Two of these (Halocordyle disticha and Tubularia crocea) became palatable after being treated with potassium chloride to discharge their nematocysts, suggesting that these species rely on nematocysts for defenses against predators. Chemical extracts from nematocyst-defended species had no effect on fish feeding. The four species that remained unpalatable after nematocysts had been discharged (Corydendrium parasiticum, Eudendrium carneum, Hydractinia symbiolongicarpus, Tridentata marginata) possessed chemical extracts that deterred feeding by pinfish. We have isolated and characterized the structures of the deterrent metabolites in two of these species. We found no differences in nutritional content or levels of chitin between nematocyst-defended and chemically defended species, and no evidence that either of these played a role in the rejection of hydroids as prey. Our results suggest that, among hydroids, chemical defenses may be at least as common as nematocyst-based defenses and that the two may represent largely alternative defensive strategies. The four hydroid species with deterrent extracts represent four families and both sub-orders of hydroids, suggesting that chemical defenses in this group may be widespread and have multiple origins. Received: 25 May 1999 / Accepted: 1 February 2000     

Some toxicological characteristics of three venomous soft corals from the Red Sea

Three common Red Sea soft corals (Cnidaria: Anthozoa), Nephthea sp, Dendronephthya sp and Heteroxenia fuscescens sting humans. Nematocyst venoms of each animal are lethal to mice and hemolytic to human erythrocytes. However, these hemolysins are partially inhibited by known anti-hemolytic agents. Venoms and their gel chromatography-separated fractions have different dermonecrosis and vasopermeability potency in mouse skin. The venom of Heteroxenia fuscescens (Hf) was more lethal (LD50: 0.7 mg/kg), with one prominent 97-kDa protein fraction (LD50: 0.55 mg/kg). Hf venom was more hemolytic, more dermonecrotic, and had more vasopermeable factors than that of the two other species. SDS polyacrylamide gel electrophoresis of soft coral whole venoms and fractions showed different protein molecular masses ranging from 200 to less than 6 kDa. High IgG titers were assayed from venom-sensitized mice blood sera. Enzyme-linked immunosorbent assays (ELISA) marked significant immunological cross-reaction between the studied soft coral venoms and their bioactive fractions.     

Morphogenesis of the atrichous isorhiza, a type of nematocyst, in Hydra observed with a monoclonal antibody

 We produced a monoclonal antibody, AE03, which recognized mucous granules in the basal disk gland cells in Hydra and the secreted mucus with which they stick onto substrate. AE03 also recognized atrichous isorhizas, one of the four types of nematocyst present in tentacles, and their nematoblasts present in the body column. With this monoclonal antibody, we could observe the detailed morphogenesis of the atrichous isorhiza from the beginning of its formation. The elongation and invagination processes of external tubes and correspondence between the external tubes and the thread of discharged nematocysts were confirmed. Received: 20 May 1997 / Accepted: 21 September 1997     

A Non-sulfated Chondroitin Stabilizes Membrane Tubulation in Cnidarian Organelles

Membrane tubulation is generally associated with rearrangements of the cytoskeleton and other cytoplasmic factors. Little is known about the contribution of extracellular matrix components to this process. Here, we demonstrate an essential role of proteoglycans in the tubulation of the cnidarian nematocyst vesicle. The morphogenesis of this extrusive organelle takes place inside a giant post-Golgi vesicle, which topologically represents extracellular space. This process includes the formation of a complex collagenous capsule structure that elongates into a long tubule, which invaginates after its completion. We show that a non-sulfated chondroitin appears as a scaffold in early morphogenesis of all nematocyst types in Hydra and Nematostella. It accompanies the tubulation of the vesicle membrane forming a provisional tubule structure, which after invagination matures by collagen incorporation. Inhibition of chondroitin synthesis by β-xylosides arrests nematocyst morphogenesis at different stages of tubule outgrowth resulting in retention of tubule material and a depletion of mature capsules in the tentacles of hydra. Our data suggest a conserved role of proteoglycans in the stabilization of a membrane protrusion as an essential step in organelle morphogenesis.     

Isolation and characterization of a novel protein toxin from fire coral

Fire corals (Millepora spp.) cause severe pain and inflammatory effects in humans upon contact, and the organs responsible for these effects are called nematocysts. Here, we isolated an active cytotoxin of ca. 18 kDa (MCTx-1) from nematocysts of Millepora dichotoma var. tenera. MCTx-1 was potently cytotoxic (EC₅₀ value 79 ng/mL) towards L1210 mouse leukemia cells, hemagglutinated a 0.8% suspension of sheep erythrocytes (0.2 μg protein/mL) and was lethal in crayfish (LD₅₀, 106 μg/kg). We deduced the primary structure of MCTx-1 from the corresponding cDNA sequence and found that MCTx-1 is a novel dermatopontin that is an extracellular matrix protein in mammals. This is the first characterization of a proteinaceous toxin from fire coral.     

Abundance,feeding behaviour and nematocysts of scyphopolyps (Cnidaria) and nematocysts in their predator,the nudibranch Coryphella verrucosa (Mollusca)

The abundance of Aurelia and Cyanea scyphopolyps on Laminaria saccharinawas higher in sheltered, shallow areas compared with more exposed or deepones. Liberated planulae probably were not transported far away fromstranded and trapped jellyfish and settled nearby, preferably in patches onthe downward side of the Laminaria thallus. The principal prey for thescyphopolyps seems to be small copepods and the cladocerans Podon sp. andEvadne sp., which are abundant in surface waters during the summer.Temporarily abundant planktonic organisms, e.g., Sagitta setosa,Pleurobrachia pileus and hydromedusae might, also be important prey.Harpacticids, halacarideans and Corophium sp., whose natural habitat is onL. saccharina, were not captured by the scyphopolyps. Scyphopolyps culturedin running sea water rich in detritus and phytoplankton fill their enteronwith organic substrates, particularly diatoms. A new category ofheterotrichous microbasic rhopaloid nematocysts was identified in thescyphopolyps. These rhopaloids were earlier included within the eurytelesand were not considered to be separate nematocysts. They are distinctivefrom the euryteles due to the two swellings on their discharged shaft. Theabsence or presence of the nudibranch Coryphella verrucosa on laminarianthalli possibly has an effect on the number of scyphopolyps, as thisnudibranch consumes numerous scyphopolyps. Isorhizas and the new category ofrhopaloid nematocysts, identical to those present in the Aurelia polyps,occurred in the cnidosacs of examined C. verrucosa. The proportion ofrhopaloid nematocysts compared with a-isorhizas was noticeably higher in C.verrucosa than in scyphopolyps. The nudibranch may selectively storerhopaloids.     

Active Nematocyst Isolation Via Nudibranchs

Cnidarian venoms are potentially valuable tools for biomedical research and drug development. They are contained within nematocysts, the stinging organelles of cnidarians. Several methods exist for the isolation of nematocysts from cnidarian tissues; most are tedious and target nematocysts from specific tissues. We have discovered that the isolated active nematocyst complement (cnidome) of several sea anemone (Cnidaria: Anthozoa) species is readily accessible. These nematocysts are isolated, concentrated, and released to the aqueous environment as a by-product of aeolid nudibranch Spurilla neapolitana cultures. S. neapolitana feed on venomous sea anemones laden with stinging nematocysts. The ingested stinging organelles of several sea anemone species are effectively excreted in the nudibranch feces. We succeeded in purifying the active organelles and inducing their discharge. Thus, our current study presents the attractive possibility of using nudibranchs to produce nematocysts for the investigation of novel marine compounds.     

Comparative toxinological and immunological studies on the nematocyst venoms of the Red Sea fire corals Millepora dichotoma and M. platyphylla

A method appropriate for isolating of fire coral nematocysts of Millepora dichotoma (Md) and Millepora platyphylla (Mp) was described and compared with techniques that had been used before. Isolated nematocyst venoms of Md (Md-TX) and Mp (Mp-TX) were lethal to mice (had LD50 values of 0.51 and 0.21 microg/g mouse body, respectively) and displayed variable hemolytic, vasopermeable and dermonecrotic properties. The potent hemolysins of Md-TX and Mp-TX, which purified by gel filtration chromatography, possessed prominent proteins of molecular weights 35 and 31 kDa and had LD50 values 0.35 and 0.25 microg/g mouse, respectively. Hemolytic activities of crude venoms and their fraction could be inactivated using known anti-hemolytic agents. Both Md-TX and Mp-TX had distinguishable antigenic properties and their antisera raised in immunized mice and stung human were cross-reactive. ELISA assays showed an antigenic similarity among the studied fire coral homologous cytolytic counterparts.