Gymnothorax Javanicus Research Articles

Comparative cytogenetics of six Indo-Pacific moray eels (Anguilliformes: Muraenidae) by chromosomal banding and fluorescence in situ hybridization.

A comparative cytogenetic analysis, using both conventional staining techniques and fluorescence in situ hybridization, of six Indo-Pacific moray eels from three different genera (Gymnothorax fimbriatus, Gymnothorax flavimarginatus, Gymnothorax javanicus, Gymnothorax undulatus, Echidna nebulosa and Gymnomuraena zebra), was carried out to investigate the chromosomal differentiation in the family Muraenidae. Four species displayed a diploid chromosome number 2n = 42, which is common among the Muraenidae. Two other species, G. javanicus and G. flavimarginatus, were characterized by different chromosome numbers (2n = 40 and 2n = 36). For most species, a large amount of constitutive heterochromatin was detected in the chromosomes, with species-specific C-banding patterns that enabled pairing of the homologous chromosomes. In all species, the major ribosomal genes were localized in the guanine-cytosine-rich region of one chromosome pair, but in different chromosomal locations. The (TTAGGG)n telomeric sequences were mapped onto chromosomal ends in all muraenid species studied. The comparison of the results derived from this study with those available in the literature confirms a substantial conservation of the diploid chromosome number in the Muraenidae and supports the hypothesis that rearrangements have occurred that have diversified their karyotypes. Furthermore, the finding of two species with different diploid chromosome numbers suggests that additional chromosomal rearrangements, such as Robertsonian fusions, have occurred in the karyotype evolution of the Muraenidae.

Dollfustrema durum n. sp. and Heterobucephalopsis perardua n. sp. (Digenea: Bucephalidae) from the giant moray eel, Gymnothorax javanicus (Bleeker) (Anguilliformes: Muraenidae), and proposal of the Heterobucephalopsinae n. subfam

Two new species of bucephalid trematode (Platyhelminthes: Digenea) are described from the giant moray eel, Gymnothorax javanicus (Anguilliformes: Muraenidae), from off Lizard Island, Australia. We used a combined morphological and molecular-based approach targeting the internal transcribed spacer 2 (ITS2) of the ribosomal DNA (rDNA) and the D1–D3 region of the large subunit (28S) of rDNA to circumscribe the species. Dollfustrema durum n. sp. is distinguished from seven congeners in having 5–6 rows of enlarged body spines circling the anterior portion of the rhynchus. From the remaining 10 species, D. durum n. sp. differs in body length, and in having a caecum that terminates posteriorly to the confluent arc formed by the vitelline follicles, gonads predominantly anterior to the pharynx, testes in tandem, an anterior testis positioned posteriorly to the vitelline follicles, and the pre-vitelline field 23–40% of the body length. Heterobucephalopsis perardua n. sp. differs from Heterobucephalopsis gymnothoracis, the type- and only other reported species, in being two to three times smaller. Heterobucephalopsis, currently considered a genus inquirendum, is confirmed as valid and is rediagnosed. Bayesian inference analysis of 28S rDNA sequences representing 28 species from nine genera and four subfamilies of bucephalid, indicates that i) subfamily classifications previously based on morphological characters are broadly robust, ii) the sequence representing H. perardua n. sp. is resolved as distinct, and basal, to sequences representing the Bucephalinae, the Prosorhynchinae, the Paurorhynchinae, and the Dolichoenterinae, iii) the Dolichoenterinae and the Prosorhynchinae are monophyletic sister clades, basal to the Bucephalinae and the Paurorhynchinae, iv) sequences representing Grammatorcynicola, Prosorhynchus, and Dollfustrema are also monophyletic, v) the Bucephalinae is paraphyletic relative to the Paurorhynchinae, and vi) the bucephaline genera Prosorhynchoides, Rhipidocotyle, and Bucephalus are each polyphyletic. The morphological and molecular differences observed among the four previously recognised subfamilies in this study lead us to propose Heterobucephalopsinae n. subfam. to accommodate the genus Heterobucephalopsis.

Referential gestures in fish collaborative hunting

In humans, referential gestures intentionally draw the attention of a partner to an object of mutual interest, and are considered a key element in language development. Outside humans, referential gestures have only been attributed to great apes and, most recently, ravens. This was interpreted as further evidence for the comparable cognitive abilities of primates and corvids. Here we describe a signal that coral reef fishes, the grouper Plectropomus pessuliferus marisrubri and coral trout Plectropomus leopardus, use to indicate hidden prey to cooperative hunting partners, including giant moray eels Gymnothorax javanicus, Napoleon wrasses Chelinus undulatus and octopuses Octopus cyanea. We provide evidence that the signal possesses the five attributes proposed to infer a referential gesture: it is directed towards an object, mechanically ineffective, directed towards a potential recipient, receives a voluntary response and demonstrates hallmarks of intentionality. Thus, referential gesture use is not restricted to large-brained vertebrates.

A potential methodology for differentiation of ciguatgoxin-carrying species of moray eel

A food poisoning incident due to ingestion of an unknown moray eel occurred in Taiwan. To identify the species of causative moray eel implicated in food poisoning, a 376-bp fragment sequence of cytochrome b gene was successfully obtained from four species of moray eel by using a pair of primers (L newest-1/H 15149). This fragment could be amplified using fish meat treated with different heating processes (100 °C for 30 min, 100 °C for 60 min, 121 °C for 15 min, and 121 °C for 30 min). After sequencing, it was found that no variation in sequence was detected among individuals within each species. The species of causative moray eel implicated in food poisoning was judged as Gymnothorax javanicus based on sequence analysis. In addition, using restriction enzyme analysis, including Taq I and Sau96 I, could distinguish these four species of moray eel and identify the fish species of poisoning sample as G. javanicus. The toxicity of viscera in 24 specimens of four moray eel species was not detected, but the food poisoning sample was found to be toxic. Overall, this study proved that DNA sequence and restriction enzyme analyses are useful in identifying that the causative moray eel species was G. javanicus.

Interspecific Communicative and Coordinated Hunting between Groupers and Giant Moray Eels in the Red Sea

Intraspecific group hunting has received considerable attention because of the close links between cooperative behaviour and its cognitive demands. Accordingly, comparisons between species have focused on behaviours that can potentially distinguish between the different levels of cognitive complexity involved, such as “intentional” communication between partners in order to initiate a joint hunt, the adoption of different roles during a joint hunt (whether consistently or alternately), and the level of food sharing following a successful hunt. Here we report field observations from the Red Sea on the highly coordinated and communicative interspecific hunting between the grouper, Plectropomus pessuliferus, and the giant moray eel, Gymnothorax javanicus. We provide evidence of the following: (1) associations are nonrandom, (2) groupers signal to moray eels in order to initiate joint searching and recruit moray eels to prey hiding places, (3) signalling is dependent on grouper hunger level, and (4) both partners benefit from the association. The benefits of joint hunting appear to be due to complementary hunting skills, reflecting the evolved strategies of each species, rather than individual role specialisation during joint hunts. In addition, the partner species that catches a prey item swallows it whole immediately, making aggressive monopolisation of a carcass impossible. We propose that the potential for monopolisation of carcasses by one partner species represents the main constraint on the evolution of interspecific cooperative hunting for most potentially suitable predator combinations.

Cucullanin Nematodes from Coral Reef Fishes of French Polynesia, with a Description of Cucullanus faliexae n. sp. (Nematoda: Chitwoodchabaudiidae)

Cucullanus faliexae n. sp. is described from the moray eel Gymnothorax javanicus (Muraenidae) collected in Rangiroa (Tuamotu Islands, French Polynesia) in the South Pacific and is reported from the same host collected in Moorea (Society Islands, French Polynesia). This nematode is distinguished from its congeners by its protrubant anus and the presence of a single pair of subdorsal postanal papillae. Cucullanus faliexae resembles C. laurotravassosi from which it is distinguished by the farther anterior position of the first pair of male caudal preanal papillae and by the greater size of its spicules. Cucullanus bourdini Petter and Le Bel, 1992 is reported from the coral reef fishes Balistapus undulatus (Balistidae), Lutjanus gibbus (Lutjanidae), and Myripristis kuntee (Holocentridae) from French Polynesia. Additionally, Cucullanus sp. is reported from the coral reef fish Sufflamen bursa (Balistidae) in Moorea and Rangiroa. Given that C. faliexae and C. bourdini have been found in widely disparate locations between which their definitive hosts cannot migrate, it would seem likely that the life cycles of these worms include an intermediate or transport host that has a greater capability for dispersal.

Isolation and structures of new ciguatoxin analogs, 2,3-dihydroxyCTX3C and 51-hydroxyCTX3C, accumulated in tropical reef fish

Two new ciguatoxin analogs, 2,3-dihydroxyCTX3C and 51-hydroxyCTX3C, were isolated from the moray eel Gymnothorax javanicus. Their structures including relative configurations were elucidated on the basis of 1H-NMR data.

Ciguatoxin extracted from poisonous moray eels Gymnothorax javanicus triggers acetylcholine release from Torpedo cholinergic synaptosomes via reversed Na+ –Ca2+ exchange

Ciguatoxin (CTX) (0.1 pM to 10 nM) added to a suspension of Torpedo synaptosomes incubated in Ca(2+)-free medium caused no detectable acetylcholine (ACh) release. However, subsequent addition of Ca2+ caused a large ACh release that depended on time of exposure, dose of CTX and on [Ca2+]. Tetrodotoxin completely prevented CTX-induced Ca(2+)-dependent ACh release. Simultaneous blockade of Ca2+ channel subtypes by FTX, a toxin extracted from the venom of the spider Agelenopsis aperta, omega-conotoxin and Gd3+ did not prevent ACh release caused by CTX, upon addition of Ca2+. These results suggest that CTX activates the reversed operation of the Na+/Ca2+ exchange system allowing the entry of Ca2+ in exchange for Na+. It is concluded that Torpedo synaptosomes are endowed with Na+ channels sensitive to pico- to nanomolar concentrations of CTX.

Structures and configurations of ciguatoxin from the moray eel Gymnothorax javanicus and its likely precursor from the dinoflagellate Gambierdiscus toxicus

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructures and configurations of ciguatoxin from the moray eel Gymnothorax javanicus and its likely precursor from the dinoflagellate Gambierdiscus toxicusMichio Murata, Anne M. Legrand, Yoshihiko Ishibashi, Masakazu Fukui, and Takeshi YasumotoCite this: J. Am. Chem. Soc. 1990, 112, 11, 4380–4386Publication Date (Print):May 1, 1990Publication History Published online1 May 2002Published inissue 1 May 1990https://doi.org/10.1021/ja00167a040RIGHTS & PERMISSIONSArticle Views1247Altmetric-Citations399LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (845 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Ciguatoxin enhances quantal transmitter release from frog motor nerve terminals

1. Ciguatoxin (CTX), a marine toxin produced by the benthic dinoflagellate Gambierdiscus toxicus, is responsible for a complex endemic disease in man known as ciguatera fish poisoning. In the present study we have investigated the effects of purified CTX extracted for Gymnothorax javanicus moray-eel liver on frog isolated neuromuscular preparations with conventional electrophysiological techniques. 2. CTX (1-2.5 nM) applied to cutaneous pectoris nerve-muscle preparations induced, after a short delay, spontaneous fibrillations of the muscle fibres that could be suppressed with 1 microM tetrodotoxin (TTX) or by formamide to uncouple excitation-contraction. 3. In preparations treated with formamide, CTX (1-2.5 nM) caused either spontaneous or repetitive muscle action potentials (up to frequencies of 60-100 Hz) in response to a single nerve stimulus. Recordings performed at extrajunctional regions of the muscle membrane revealed that during the repetitive firing a prolongation of the repolarizing phase of the action potential occurred. At junctional sites the repetitive action potentials were triggered by repetitive endplate potentials (e.p.ps). 4. CTX (2.5 nM) caused a TTX-sensitive depolarization of the muscle membrane. 5. In junctions equilibrated in solutions containing high Mg2+ + low Ca2+, addition of CTX (1.5 nM) first induced an average increase of 239 +/- 36% in the mean quantal content of e.p.ps. Subsequently CTX reduced and finally blocked nerve-evoked transmitter release irreversibly. 6. CTX (1.5-2.5 nM) increased the frequency of miniature endplate potentials (m.e.p.ps) in junctions bathed either in normal Ringer, low Ca2(+)-high Mg2+ medium or in a nominally Ca2(+)-free solution containing EGTA.2+ Extensive washing with toxin-free solutions did not reverse the effect. Furthermore, Cd2 + (0.1 mM), a potent calcium channel blocker, neither antagonized nor abolished the increase in transmitter release caused by CTX. 7. TTX (1 microM) completely prevented the effect of CTX (2.5nM) on m.e.p.p. frequency. This effect was independent of the presence of extracellular Ca2 +. TTX, when added after CTX (2.5 nM) exposure, antagonized the increase in m.e.p.p. frequency. The antagonism was complete in Ca2 +-free medium. These results strongly suggest that increased permeability of the nerve terminal to Na+ is responsible for the increase in m.e.p.p. frequency caused by CTX. It is likely that CTX may trigger calcium release from internal stores due to an increase of intraterminal Na+ concentration. 8. It is concluded that CTX exerts, in the nanomolar concentration range, a selective action on sodium channels of the neuromuscular junction causing both pre- and postsynaptic effects.

A probable partial structure of ciguatoxin isolated from the moray eel [formula omitted

A probable partial structure of ciguatoxin obtained from the moray eel Gymnothorax javanicus was deduced to be 1 on the basis of MS and NMR spectra. The proposed structure involves 22 carbons, accounting for 37% of the total carbons of the toxin.

Effects of partially purified ciguatoxin from moray-eel, Gymnothorax javanicus, on action potential of isolated rat heart: J. P. Quod and A. M. Legrand (Institut Territorial de Recherches Médicales Louis Malardé, Laboratoire de Pharmaco-Toxicologie, Papeete, Tahiti, Polynésie Française)

Effects of partially purified ciguatoxin from moray-eel, Gymnothorax javanicus, on action potential of isolated rat heart: J. P. Quod and A. M. Legrand (Institut Territorial de Recherches Médicales Louis Malardé, Laboratoire de Pharmaco-Toxicologie, Papeete, Tahiti, Polynésie Française)

RECENT DEVELOPMENTS IN THE MOLECULAR STRUCTURE OF CIGUATOXIN

Crystalline ciguatoxin isolated from moray eel (Lycodontis ≡ Gymnothorax javanicus) viscera has an LD50 of 0.45 g/kg (i.p., mice). It has a molecular weight of 1111.7 ± 0.2 daltons. 1H NMR studies have shown that it is a polar and highly oxygenated molecule belonging to the class of polyethers. On basic alumina ciguatoxin is reversibly converted to a chromatographically distinct less polar form, which is equally toxic and elicits typical ciguatoxin symptoms in mice.From parrotfish (Scarus sordidus), which originated on a ciguateric reef on Tarawa atoll (Kiribati), we have isolated two toxins that evoke ciguatera symptoms in mice at approximately equal levels. Chromatographic evidence suggests that the two toxins are identical with the two ciguatoxins of different polarity and that the less polar form is the previously described scaritoxin.

Effects of ciguatoxin and maitotoxin on isolated rat atria and rabbit duodenum

Ciguatoxin atoxin and maitotoxin, extracted from a species of moray-eel, Gymnothorax javanicus, and from a wild dinoflagellate, Gambierdiscus toxicus, were tested on rat atria and rabbit duodenum. Biphasic inotropic and chronotropic responses with excitatory and inhibitory components were observed. The effects of agents such as reserpine, propranolol, phentolamine, atropine and manganese ions were investigated. We conclude that, at the dosage levels used, ciguatoxin acts mainly at the nerve endings, while maitotoxin exerts prominent toxic effects on muscles.

Le complexe toxinique des poissons perroquets

Clinical and epidemiological observations suggested that a complex toxic molecule is involved in the parrotfish flesh (Scarus gibbus) poisoning from Gambier Islands. The fat soluble extract obtained from the muscles upon ciguatoxin preparation showed two toxic substances after fractionation by DEAE cellulose column chromatography. The major toxin is different from ciguatoxin judging by its chromatographic behaviour. The other is closely similar to (or identical with) ciguatoxin from the moray eel Gymnothorax javanicus. They were named SG1 for the new toxin and SG2 for the ciguatoxin like compound. Successive filtrations on Sephadex LH-20 of SG1 and SG2 gave respectively a lethality to mice of 0.03 microgram/g and 0.06 microgram/g. SG1, specifically occurs in the muscles of the parrotfish family (scaritoxin) while it is absent from other ciguateric fishes. According to that specificity and the lack of SG1 in S. gibbus liver and gut contents, the origin of scaritoxin is briefly discussed.

Marine Toxins from the Pacific — Ciguatoxin: not an In Vivo Anticholinesterase

Although ciguatoxin, prepared from the liver and flesh of the moray eel Gymnothorax javanicus, is an in vitro anticholinesterase, it has not been found to be an in vivo anticholinesterase. Respiratory failure and death due to ciguatoxin is not a function of cholinesterase inhibition as previously speculated, although the toxin may have a widespread action at cholinergic junctions.

ヒラマサの毒性

A fat-soluble toxin was found in the muscle of an amberjack, Seriola aureovittata, which had caused the human illness at Katsuura on May 10, 1967. The symptoms in both human beings and test animals showed a close similarity to those of ciguatera, but slight differences were also observed. The toxic fish were found in a high frequency among the amberjack caught at the fishing ground called “Mashone” and the larger fish seems to be more toxic. As test animals, cats and mice were used and the partial purification of the toxin was carried out by chromatography using silicic acid, DEAE-cellulose, and Sephadex LH-20. The toxin showed a resemblance to ciguatoxin(s) isolated from Gymnothorax javanicus or Lutjanus bohar in the chromatographic behaviors. The most purified toxin was lethal to mice at a level of 20 r/g.

1684. Look out for ciguatoxin: Clark, L. & Whitwell, G. B. (1968). Ciguatera poisoning in cats in Brisbane. Aust. vet. J.44, 81 Kosaki, T. & Stephens, Jane (1967). Pupillary miosis to ciguatoxin(s) (from Gymnothorax javanicus). Fedn Proc. Fedn Am. Socs exp. Biol.26, 322

1684. Look out for ciguatoxin: Clark, L. & Whitwell, G. B. (1968). Ciguatera poisoning in cats in Brisbane. Aust. vet. J.44, 81 Kosaki, T. & Stephens, Jane (1967). Pupillary miosis to ciguatoxin(s) (from Gymnothorax javanicus). Fedn Proc. Fedn Am. Socs exp. Biol.26, 322

Ciguatoxin: isolation and chemical nature.

Ciguatoxin, the agent responsible for ciguatera, a disease produced in humans from ingestion of certain fishes, has been isolated from specimens of the moray eel, Gymnothorax javanicus. The toxin is apparently a lipid containing quaternary nitrogen, hydroxyl, and carbonyl functions.