The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform
Hiroshi Nagai - One of the best experts on this subject based on the ideXlab platform.
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the absolute configuration of gambieric acids a d potent antifungal polyethers isolated from the marine dinoflagellate Gambierdiscus toxicus
Tetrahedron, 2000Co-Authors: Akio Morohashi, Yasukatsu Oshima, Masayuki Satake, Hiroshi Nagai, Takeshi YasumotoAbstract:Abstract The absolute configurations of potent antifungal polyether compounds, gambieric acids A–D, isolated from the marine dinoflagellate Gambierdiscus toxicus were determined by combining the modified Mosher method, NMR analysis, and chiral fluorimetric HPLC.
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isolation of a sulfoquinovosyl monoacylglycerol from bryopsis sp chlorophyta identification of a factor causing a possible species specific ecdysis response in Gambierdiscus toxicus dinophyceae 1
Journal of Phycology, 2000Co-Authors: Bryan Sakamoto, Yoshitsugi Hokama, Paul J. Scheuer, Yukiko Kan, David F Horgen, Hiroshi NagaiAbstract:A bioactive compound that induced ecdysis (thecal loss) in Gambierdiscus toxicus Adachi et Fukuyo (Dinophyceae) cultures was isolated from a host macroalga, Bryopsis sp. (Chlorophyta). The ecdysis factor was identified by spectroscopic methods as 1-O-palmitoyl-3-O-(6′-sulfo-α-d-quinovopyranosyl)-sn-glycerol (PSQG). From our results, PSQG induced ecdysis at a high frequency and appeared not to inhibit the growth of G. toxicus cultures. The induction of ecdysis followed a dose-dependent saturation curve from 4 to 8 μM PSQG. To determine specificity of PSQG, the effects of palmitoyl-l-α-lysophosphatidylcholine (PLPC) were observed. Because PLPC contains a lipophilic palmitoyl moiety and hydrophilic phosphatidyl choline group, the compound possesses a detergent-like amphiphathic property similar to PSQG. Our results demonstrate that PLPC induced ecdysis at a high frequency in G. toxicus cultures and generated a similar dose–response curve as PSQG. The ecdysis activity observed in PSQG and PLPC may correlate with the detergent-like amphiphathic property of both compounds. Although PLPC induced a similar ecdysis response as PSQG, PLPC appeared to inhibit the growth of G. toxicus cultures. Preliminary results on the effects of PSQG on the dinoflagellates Prorocentrum lima (Ehrenberg) Dodge and Coolia monotis Meunier did not parallel the results observed in G. toxicus. This study demonstrated the existence of a factor from Bryopsis sp. that elicited a possible species-specific ecdysis response in G. toxicus cultures. This is the first report of a compound that induced ecdysis in G. toxicus or in any dinoflagellate.
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The Absolute Configuration of Gambieric Acids A–D, Potent Antifungal Polyethers, Isolated from the Marine Dinoflagellate Gambierdiscus toxicus
Tetrahedron, 2000Co-Authors: Akio Morohashi, Yasukatsu Oshima, Masayuki Satake, Hiroshi Nagai, Takeshi YasumotoAbstract:Abstract The absolute configurations of potent antifungal polyether compounds, gambieric acids A–D, isolated from the marine dinoflagellate Gambierdiscus toxicus were determined by combining the modified Mosher method, NMR analysis, and chiral fluorimetric HPLC.
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ISOLATION OF A SULFOQUINOVOSYL MONOACYLGLYCEROL FROM BRYOPSIS SP. (CHLOROPHYTA): IDENTIFICATION OF A FACTOR CAUSING A POSSIBLE SPECIES‐SPECIFIC ECDYSIS RESPONSE IN Gambierdiscus toxicus (DINOPHYCEAE)1,
Journal of Phycology, 2000Co-Authors: Bryan Sakamoto, Yoshitsugi Hokama, F. David Horgen, Paul J. Scheuer, Yukiko Kan, Hiroshi NagaiAbstract:A bioactive compound that induced ecdysis (thecal loss) in Gambierdiscus toxicus Adachi et Fukuyo (Dinophyceae) cultures was isolated from a host macroalga, Bryopsis sp. (Chlorophyta). The ecdysis factor was identified by spectroscopic methods as 1-O-palmitoyl-3-O-(6′-sulfo-α-d-quinovopyranosyl)-sn-glycerol (PSQG). From our results, PSQG induced ecdysis at a high frequency and appeared not to inhibit the growth of G. toxicus cultures. The induction of ecdysis followed a dose-dependent saturation curve from 4 to 8 μM PSQG. To determine specificity of PSQG, the effects of palmitoyl-l-α-lysophosphatidylcholine (PLPC) were observed. Because PLPC contains a lipophilic palmitoyl moiety and hydrophilic phosphatidyl choline group, the compound possesses a detergent-like amphiphathic property similar to PSQG. Our results demonstrate that PLPC induced ecdysis at a high frequency in G. toxicus cultures and generated a similar dose–response curve as PSQG. The ecdysis activity observed in PSQG and PLPC may correlate with the detergent-like amphiphathic property of both compounds. Although PLPC induced a similar ecdysis response as PSQG, PLPC appeared to inhibit the growth of G. toxicus cultures. Preliminary results on the effects of PSQG on the dinoflagellates Prorocentrum lima (Ehrenberg) Dodge and Coolia monotis Meunier did not parallel the results observed in G. toxicus. This study demonstrated the existence of a factor from Bryopsis sp. that elicited a possible species-specific ecdysis response in G. toxicus cultures. This is the first report of a compound that induced ecdysis in G. toxicus or in any dinoflagellate.
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Stimulators of Gambierdiscus toxicus (Dinophyceae) growth: the possible role of gambieric acid-A as an endogenous growth enhancer
Phycologia, 1996Co-Authors: Bryan Sakamoto, Hiroshi Nagai, Yoshltsugi HokamaAbstract:Abstract The effects on the growth of Gambierdiscus toxicus Adachi et Fukuyo (Dinophyceae) cultures by conditioned media from dense-growing cultures were examined and enhanced growth was observed. The increase in Gambierdiscus toxicus cell concentration with the addition of the conditioned media suggested the existence of endogenously produced growth enhancer(s). Gambieric acid-A, a polyether compound, is known to be excreted by G. toxicus, therefore we examined the effects of gambieric acid-A of G. toxicus growth. The growth of G. toxicus clones responded maximally at 1.89 nM gambieric acid-A. Gambierdiscus toxicus growth followed a dose-dependent saturation curve with inhibition at 18.9 nM gambieric acid-A. The results of this study strongly suggest the potential biological function of gambieric acid-A to be an endogenous growth enhancer of G. toxicus. To our knowledge, no endogenously produced factor(s) enhancing the growth of any dino-flagellate have been reported.
Takeshi Yasumoto - One of the best experts on this subject based on the ideXlab platform.
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Gambieroxide, a novel epoxy polyether compound from the dinoflagellate Gambierdiscus toxicus GTP2 strain
Tetrahedron, 2013Co-Authors: Ryuichi Watanabe, Yasukatsu Oshima, Masayuki Satake, Hajime Uchida, Toshiyuki Suzuki, Ryoji Matsushima, Mika Nagae, Yoshikazu Toyohara, Akio Inoue, Takeshi YasumotoAbstract:Abstract A novel epoxy polyether compound named gambieroxide was isolated from the benthic dinoflagellate Gambierdiscus toxicus (GTP2 strain) collected at Papeete, Tahiti, French Polynesia and its structure comprising of a ladder-frame polyether with twelve contiguous trans-fused ether rings (6/7/6/6/6/7/6/8/6/6/6/6), a sulfate ester group, an epoxide, and two olefines in side chains was elucidated by detailed NMR and MS analysis. It is interesting that the structure strikingly resembles yessotoxin, one of lipophilic toxins in shellfish originating from the dinoflagellate Protoceratium reticulatum.
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detailed lc ms ms analysis of ciguatoxins revealing distinct regional and species characteristics in fish and causative alga from the pacific
Analytical Chemistry, 2011Co-Authors: Kentaro Yogi, Masahiro Hirama, Naomasa Oshiro, Yasuo Inafuku, Takeshi YasumotoAbstract:Toxin profiles of representative ciguatera species caught at different locations of Japan were investigated in fish flesh by high-performance liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis. Identification and quantification of 16 toxins were facilitated by the use of 14 reference toxins prepared by either synthesis or isolation from natural sources and the previous LC-MS data thereof. Sodium adduct ions [M + Na]+ were used as parent and product ions. Distinct regional differences were unveiled: ciguatoxin-1B type toxins were found in snappers and groupers from Okinawa, ciguatoxin-3C type toxins were found in a spotted knifejaw, Oplegnathus punctatus, from Miyazaki located 730 km north of Okinawa, and both types of toxins were found in a red snapper, Lutjanus bohar, from Minamitorishima (Marcus) Island. Twelve toxins were identified in a dinoflagellate, Gambierdiscus toxicus, collected as the primary toxin source in French Polynesia. Occurrence of M-seco-toxins in fish and oxidized toxi...
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Effect of ciguatoxin 3C on voltage-gated Na+ and K+ currents in mouse taste cells.
Chemical senses, 2006Co-Authors: Valeria Ghiaroni, Takeshi Yasumoto, Masahiro Hirama, Haruhiko Fuwa, Makoto Sasaki, Masayuki Inoue, Keisuke Miyazaki, Gian Paolo Rossini, Giuseppe Scalera, Albertino BigianiAbstract:The marine dinoflagellate Gambierdiscus toxicus produces highly lipophilic, polycyclic ether toxins that cause a seafood poisoning called ciguatera. Ciguatoxins (CTXs) and gambierol represent the two major causative agents of ciguatera intoxication, which include taste alterations (dysgeusiae). However, information on the mode of action of ciguatera toxins in taste cells is scarce. Here, we have studied the effect of synthetic CTX3C (a CTX congener) on mouse taste cells. By using the patch-clamp technique to monitor membrane ion currents, we found that CTX3C markedly affected the operation of voltage-gated Na + channels but was ineffective on voltage-gated K + channels. This result was the exact opposite of what we obtained earlier with gambierol, which inhibits K + channels but not Na + channels. Thus, CTXs and gambierol affect with high potency the operation of separate classes of voltage-gated ion channels in taste cells. Our data suggest that taste disturbances reported in ciguatera poisoning might be due to the ability of ciguatera toxins to interfere with ion channels in taste buds.
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the absolute configuration of gambieric acids a d potent antifungal polyethers isolated from the marine dinoflagellate Gambierdiscus toxicus
Tetrahedron, 2000Co-Authors: Akio Morohashi, Yasukatsu Oshima, Masayuki Satake, Hiroshi Nagai, Takeshi YasumotoAbstract:Abstract The absolute configurations of potent antifungal polyether compounds, gambieric acids A–D, isolated from the marine dinoflagellate Gambierdiscus toxicus were determined by combining the modified Mosher method, NMR analysis, and chiral fluorimetric HPLC.
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The Absolute Configuration of Gambieric Acids A–D, Potent Antifungal Polyethers, Isolated from the Marine Dinoflagellate Gambierdiscus toxicus
Tetrahedron, 2000Co-Authors: Akio Morohashi, Yasukatsu Oshima, Masayuki Satake, Hiroshi Nagai, Takeshi YasumotoAbstract:Abstract The absolute configurations of potent antifungal polyether compounds, gambieric acids A–D, isolated from the marine dinoflagellate Gambierdiscus toxicus were determined by combining the modified Mosher method, NMR analysis, and chiral fluorimetric HPLC.
Bryan Sakamoto - One of the best experts on this subject based on the ideXlab platform.
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isolation of a sulfoquinovosyl monoacylglycerol from bryopsis sp chlorophyta identification of a factor causing a possible species specific ecdysis response in Gambierdiscus toxicus dinophyceae 1
Journal of Phycology, 2000Co-Authors: Bryan Sakamoto, Yoshitsugi Hokama, Paul J. Scheuer, Yukiko Kan, David F Horgen, Hiroshi NagaiAbstract:A bioactive compound that induced ecdysis (thecal loss) in Gambierdiscus toxicus Adachi et Fukuyo (Dinophyceae) cultures was isolated from a host macroalga, Bryopsis sp. (Chlorophyta). The ecdysis factor was identified by spectroscopic methods as 1-O-palmitoyl-3-O-(6′-sulfo-α-d-quinovopyranosyl)-sn-glycerol (PSQG). From our results, PSQG induced ecdysis at a high frequency and appeared not to inhibit the growth of G. toxicus cultures. The induction of ecdysis followed a dose-dependent saturation curve from 4 to 8 μM PSQG. To determine specificity of PSQG, the effects of palmitoyl-l-α-lysophosphatidylcholine (PLPC) were observed. Because PLPC contains a lipophilic palmitoyl moiety and hydrophilic phosphatidyl choline group, the compound possesses a detergent-like amphiphathic property similar to PSQG. Our results demonstrate that PLPC induced ecdysis at a high frequency in G. toxicus cultures and generated a similar dose–response curve as PSQG. The ecdysis activity observed in PSQG and PLPC may correlate with the detergent-like amphiphathic property of both compounds. Although PLPC induced a similar ecdysis response as PSQG, PLPC appeared to inhibit the growth of G. toxicus cultures. Preliminary results on the effects of PSQG on the dinoflagellates Prorocentrum lima (Ehrenberg) Dodge and Coolia monotis Meunier did not parallel the results observed in G. toxicus. This study demonstrated the existence of a factor from Bryopsis sp. that elicited a possible species-specific ecdysis response in G. toxicus cultures. This is the first report of a compound that induced ecdysis in G. toxicus or in any dinoflagellate.
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ISOLATION OF A SULFOQUINOVOSYL MONOACYLGLYCEROL FROM BRYOPSIS SP. (CHLOROPHYTA): IDENTIFICATION OF A FACTOR CAUSING A POSSIBLE SPECIES‐SPECIFIC ECDYSIS RESPONSE IN Gambierdiscus toxicus (DINOPHYCEAE)1,
Journal of Phycology, 2000Co-Authors: Bryan Sakamoto, Yoshitsugi Hokama, F. David Horgen, Paul J. Scheuer, Yukiko Kan, Hiroshi NagaiAbstract:A bioactive compound that induced ecdysis (thecal loss) in Gambierdiscus toxicus Adachi et Fukuyo (Dinophyceae) cultures was isolated from a host macroalga, Bryopsis sp. (Chlorophyta). The ecdysis factor was identified by spectroscopic methods as 1-O-palmitoyl-3-O-(6′-sulfo-α-d-quinovopyranosyl)-sn-glycerol (PSQG). From our results, PSQG induced ecdysis at a high frequency and appeared not to inhibit the growth of G. toxicus cultures. The induction of ecdysis followed a dose-dependent saturation curve from 4 to 8 μM PSQG. To determine specificity of PSQG, the effects of palmitoyl-l-α-lysophosphatidylcholine (PLPC) were observed. Because PLPC contains a lipophilic palmitoyl moiety and hydrophilic phosphatidyl choline group, the compound possesses a detergent-like amphiphathic property similar to PSQG. Our results demonstrate that PLPC induced ecdysis at a high frequency in G. toxicus cultures and generated a similar dose–response curve as PSQG. The ecdysis activity observed in PSQG and PLPC may correlate with the detergent-like amphiphathic property of both compounds. Although PLPC induced a similar ecdysis response as PSQG, PLPC appeared to inhibit the growth of G. toxicus cultures. Preliminary results on the effects of PSQG on the dinoflagellates Prorocentrum lima (Ehrenberg) Dodge and Coolia monotis Meunier did not parallel the results observed in G. toxicus. This study demonstrated the existence of a factor from Bryopsis sp. that elicited a possible species-specific ecdysis response in G. toxicus cultures. This is the first report of a compound that induced ecdysis in G. toxicus or in any dinoflagellate.
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Stimulators of Gambierdiscus toxicus (Dinophyceae) growth: the possible role of gambieric acid-A as an endogenous growth enhancer
Phycologia, 1996Co-Authors: Bryan Sakamoto, Hiroshi Nagai, Yoshltsugi HokamaAbstract:Abstract The effects on the growth of Gambierdiscus toxicus Adachi et Fukuyo (Dinophyceae) cultures by conditioned media from dense-growing cultures were examined and enhanced growth was observed. The increase in Gambierdiscus toxicus cell concentration with the addition of the conditioned media suggested the existence of endogenously produced growth enhancer(s). Gambieric acid-A, a polyether compound, is known to be excreted by G. toxicus, therefore we examined the effects of gambieric acid-A of G. toxicus growth. The growth of G. toxicus clones responded maximally at 1.89 nM gambieric acid-A. Gambierdiscus toxicus growth followed a dose-dependent saturation curve with inhibition at 18.9 nM gambieric acid-A. The results of this study strongly suggest the potential biological function of gambieric acid-A to be an endogenous growth enhancer of G. toxicus. To our knowledge, no endogenously produced factor(s) enhancing the growth of any dino-flagellate have been reported.
J Molgó - One of the best experts on this subject based on the ideXlab platform.
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Ciguatoxin-induced catecholamine secretion in bovine chromaffin cells: Mechanism of action and reversible inhibition by brevenal.
Toxicon, 2009Co-Authors: Truong D Nguyen-huu, Richard J. Lewis, C Mattei, E Benoit, J Molgó, Peter J Wen, Andrea J Bourdelais, Daniel G Baden, Frédéric A. MeunierAbstract:Ciguatoxin (P-CTX-1B) from the dinoflagellate Gambierdiscus toxicus, belongs to the family of polyether neurotoxins responsible for the neurological poisoning disorder ciguatera. Although it is the most widespread marine-borne disease affecting humans, there is no current FDA-approved treatment available except for symptomatic therapies. In this paper, we report that P-CTX-1B promotes catecholamine secretion from bovine chromaffin cells, an effect that is insensitive to concomitant activation of capacitative Ca(2+) entry. Moreover, we confirm that brevenal, a polyether from the dinoflagellate Karenia brevis, blocks P-CTX-1B-induced catecholamine secretion. This effect is partially reversible. Our results therefore raise the prospect of finding functional antagonists for P-CTX-1B that could be useful for the treatment of ciguatera.
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Gambiertoxin (CTX-4B), purified from wild Gambierdiscus toxicus dinoflagellates, induces Na(+)-dependent swelling of single frog myelinated axons and motor nerve terminals in situ.
Neuroscience letters, 1997Co-Authors: C Mattei, A.m. Legrand, E Benoit, P Juzans, J MolgóAbstract:The effects of gambiertoxin (CTX-4B), purified from the dinoflagellate Gambierdiscus toxicus, were assessed on the morphology of both frog myelinated axons and motor nerve terminals, using confocal laser scanning microscopy. During the action of the toxin (24 and 30 nM), a marked swelling of nodes of Ranvier and motor nerve terminals was observed. The CTX-4B-induced swelling could be prevented by blocking voltage-dependent Na+ channels with tetrodotoxin, and could be partly reversed by an external hyperosmotic solution containing 100 mM D-mannitol. The results suggest that CTX-4B, by modifying voltage-dependent Na+ channels, increases internal Na+ concentration of axons and nerve terminals and consequently induces water influx to compensate such an increase. It is suggested that stimulated transmitter release by CTX-4B, as well as by hyperosmotic dmannitol, contribute also to the swelling of the terminals through an increase in their surface area.
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Gambiertoxin (CTX-4B), purified from wild Gambierdiscus toxicus dinoflagellates, induces Na+-dependent swelling of single frog myelinated axons and motor nerve terminals in situ
Neuroscience Letters, 1997Co-Authors: C Mattei, Annemarie Legrand, E Benoit, P Juzans, J MolgóAbstract:The effects of gambiertoxin (CTX-4B), purified from the dinoflagellate Gambierdiscus toxicus, were assessed on the morphology of both frog myelinated axons and motor nerve terminals, using confocal laser scanning microscopy. During the action of the toxin (24 and 30 nM), a marked swelling of nodes of Ranvier and motor nerve terminals was observed. The CTX-4B-induced swelling could be prevented by blocking voltage-dependent Na+ channels with tetrodotoxin, and could be partly reversed by an external hyperosmotic solution containing 100 mM D-mannitol. The results suggest that CTX-4B, by modifying voltage-dependent Na+ channels, increases internal Na+ concentration of axons and nerve terminals and consequently induces water influx to compensate such an increase. It is suggested that stimulated transmitter release by CTX-4B, as well as by hyperosmotic dmannitol, contribute also to the swelling of the terminals through an increase in their surface area.
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gambiertoxin ctx 4b purified from wild Gambierdiscus toxicus dinoflagellates induces na dependent swelling of single frog myelinated axons and motor nerve terminals in situ
Neuroscience Letters, 1997Co-Authors: C Mattei, Annemarie Legrand, E Benoit, P Juzans, J MolgóAbstract:The effects of gambiertoxin (CTX-4B), purified from the dinoflagellate Gambierdiscus toxicus, were assessed on the morphology of both frog myelinated axons and motor nerve terminals, using confocal laser scanning microscopy. During the action of the toxin (24 and 30 nM), a marked swelling of nodes of Ranvier and motor nerve terminals was observed. The CTX-4B-induced swelling could be prevented by blocking voltage-dependent Na+ channels with tetrodotoxin, and could be partly reversed by an external hyperosmotic solution containing 100 mM D-mannitol. The results suggest that CTX-4B, by modifying voltage-dependent Na+ channels, increases internal Na+ concentration of axons and nerve terminals and consequently induces water influx to compensate such an increase. It is suggested that stimulated transmitter release by CTX-4B, as well as by hyperosmotic dmannitol, contribute also to the swelling of the terminals through an increase in their surface area.
C Mattei - One of the best experts on this subject based on the ideXlab platform.
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Ciguatoxin-induced catecholamine secretion in bovine chromaffin cells: Mechanism of action and reversible inhibition by brevenal.
Toxicon, 2009Co-Authors: Truong D Nguyen-huu, Richard J. Lewis, C Mattei, E Benoit, J Molgó, Peter J Wen, Andrea J Bourdelais, Daniel G Baden, Frédéric A. MeunierAbstract:Ciguatoxin (P-CTX-1B) from the dinoflagellate Gambierdiscus toxicus, belongs to the family of polyether neurotoxins responsible for the neurological poisoning disorder ciguatera. Although it is the most widespread marine-borne disease affecting humans, there is no current FDA-approved treatment available except for symptomatic therapies. In this paper, we report that P-CTX-1B promotes catecholamine secretion from bovine chromaffin cells, an effect that is insensitive to concomitant activation of capacitative Ca(2+) entry. Moreover, we confirm that brevenal, a polyether from the dinoflagellate Karenia brevis, blocks P-CTX-1B-induced catecholamine secretion. This effect is partially reversible. Our results therefore raise the prospect of finding functional antagonists for P-CTX-1B that could be useful for the treatment of ciguatera.
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Gambiertoxin (CTX-4B), purified from wild Gambierdiscus toxicus dinoflagellates, induces Na(+)-dependent swelling of single frog myelinated axons and motor nerve terminals in situ.
Neuroscience letters, 1997Co-Authors: C Mattei, A.m. Legrand, E Benoit, P Juzans, J MolgóAbstract:The effects of gambiertoxin (CTX-4B), purified from the dinoflagellate Gambierdiscus toxicus, were assessed on the morphology of both frog myelinated axons and motor nerve terminals, using confocal laser scanning microscopy. During the action of the toxin (24 and 30 nM), a marked swelling of nodes of Ranvier and motor nerve terminals was observed. The CTX-4B-induced swelling could be prevented by blocking voltage-dependent Na+ channels with tetrodotoxin, and could be partly reversed by an external hyperosmotic solution containing 100 mM D-mannitol. The results suggest that CTX-4B, by modifying voltage-dependent Na+ channels, increases internal Na+ concentration of axons and nerve terminals and consequently induces water influx to compensate such an increase. It is suggested that stimulated transmitter release by CTX-4B, as well as by hyperosmotic dmannitol, contribute also to the swelling of the terminals through an increase in their surface area.
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Gambiertoxin (CTX-4B), purified from wild Gambierdiscus toxicus dinoflagellates, induces Na+-dependent swelling of single frog myelinated axons and motor nerve terminals in situ
Neuroscience Letters, 1997Co-Authors: C Mattei, Annemarie Legrand, E Benoit, P Juzans, J MolgóAbstract:The effects of gambiertoxin (CTX-4B), purified from the dinoflagellate Gambierdiscus toxicus, were assessed on the morphology of both frog myelinated axons and motor nerve terminals, using confocal laser scanning microscopy. During the action of the toxin (24 and 30 nM), a marked swelling of nodes of Ranvier and motor nerve terminals was observed. The CTX-4B-induced swelling could be prevented by blocking voltage-dependent Na+ channels with tetrodotoxin, and could be partly reversed by an external hyperosmotic solution containing 100 mM D-mannitol. The results suggest that CTX-4B, by modifying voltage-dependent Na+ channels, increases internal Na+ concentration of axons and nerve terminals and consequently induces water influx to compensate such an increase. It is suggested that stimulated transmitter release by CTX-4B, as well as by hyperosmotic dmannitol, contribute also to the swelling of the terminals through an increase in their surface area.
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gambiertoxin ctx 4b purified from wild Gambierdiscus toxicus dinoflagellates induces na dependent swelling of single frog myelinated axons and motor nerve terminals in situ
Neuroscience Letters, 1997Co-Authors: C Mattei, Annemarie Legrand, E Benoit, P Juzans, J MolgóAbstract:The effects of gambiertoxin (CTX-4B), purified from the dinoflagellate Gambierdiscus toxicus, were assessed on the morphology of both frog myelinated axons and motor nerve terminals, using confocal laser scanning microscopy. During the action of the toxin (24 and 30 nM), a marked swelling of nodes of Ranvier and motor nerve terminals was observed. The CTX-4B-induced swelling could be prevented by blocking voltage-dependent Na+ channels with tetrodotoxin, and could be partly reversed by an external hyperosmotic solution containing 100 mM D-mannitol. The results suggest that CTX-4B, by modifying voltage-dependent Na+ channels, increases internal Na+ concentration of axons and nerve terminals and consequently induces water influx to compensate such an increase. It is suggested that stimulated transmitter release by CTX-4B, as well as by hyperosmotic dmannitol, contribute also to the swelling of the terminals through an increase in their surface area.
